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APPLETON’S 


DICTIONARY 


AND 


ENGINEERING. 


ILLUSTRATED  WITH  FOUR  THOUSAND  ENGRAVINGS  ON  WOOD. 


IN  TWO  VOLUMES. 


VOL.  XX. 


NTGNV  EDITION,  WITH  APPENDIX 


NEW  Y 0 R Iv  : 

TV.  APPLETON  & COMPANY, 
549  & 551  BROADWAY. 

1 8 7 4. 


Entered,  according  to  Act  of  Congress,  in  tlie  year  1851,  by 
D.  APPLETON  & CO., 

In  the  Clerk’s  Office  of  the  District  Court  of  the  United  States  for  the  Southern 
District  of  New  York. 


Entered,  according  to  Act  of  Congress,  in  the  year  1868,  by 
D.  APPLETON  & CO., 

In  the  Clerk’s  Office  of  the  District  Court  of  the  United  States  for  the  Southern 
District  of  New  York. 


A DICTIONARY 


OF 

MACHINES,  MECHANICS,  ENGINE-WORK, 
AND  ENGINEERING. 


HACKLE  or  LIAX.  A kind  of  comb  or  brush  made  of  iron  spikes ; used  for  combing  or  pulling  tli« 
fibres  of  wool  or  flax,  so  as  to  reduce  them  from  a tangled  to  a smooth  state. 

HADE.  In  mining,  the  underlay  or  inclination  of  the  vein. 

HALF-TIMBERED  HOU  SES.  Buildings  in  which  the  foundations  and  principal  supports  were  0/ 
stout  timber,  and  the  interstices  of  the  fronts  were  filled  with  plaster. 

HALLIARDS.  In  navigation,  the  ropes  or  tackles  usually  employed  to  hoist  or  lower  any  sail. 

HAMMER.  A well  known  carpenter’s  tool,  Fig.  2243  represents  a modification 
known  as  Anderson's  Patent  Hammer.  In  this  hammer,  the  claw,  as  will  be  seen  by 
the  cut,  extends  to  the  handle  and  clasps  it  with  a strong  ring,  which  makes 
it  impossible,  in  drawing  nails,  for  the  handle  to  give  way,  draw  out,  or  become 
loose.  The  face  of  the  patent  hammer  w7ill  thus  always  remain  true,  it  being 
kept  at  the  same  angle  with  the  handle.  Six  different  sizes  are  now  made, 
weighing  from  half  a pound  to  one  and  a half  pounds* 

HAMMER,  steam.  James  Nasmyth’s  patent  steam-hammer.  Before  pro- 
ceeding to  describe  the  principle,  mode  of  action,  and  constructive  details  of  the 
direct-action  steam-hammer,  it  may  be  proper  to  make  a few  remarks  on  the 
ordinary  forge-hammers,  so  that  the  nature  of  the  advantages  possessed  by  the 
steam-hammer  may  be  more  clearly  understood. 

In  all  forge-hammers  previously  in  use,  the  force  necessary  to  set  them  into  operation  had  to  be 
transmitted  in  a very  indirect  manner, — for  whether  a water-wheel  or  steam-engine  w'ere  the  moving 
power,  the  requisite  lifting  and  falling  action  of  the  hammer  had  to  be  produced  by  the  employment  of 
rotatory  motion,  thus  rendering  necessary  the  use  of  wheels,  shafts,  cams,  and  other  cumbrous  details, 
which,  together  with  the  apparatus  requisite  to  connect  the  various  parts  of  the  machinery,  and  give  due 
strength  and  solidity  to  the  whole,  not  only  caused  great  outlay  and  sacrifice  of  valuable  space,  but 
also  occasioned  much  loss  of  power,  by  reason  of  the  very  circuitous  manner  in  which  the  force  of  the 
prime  moving  agent  had  to  travel  ere  it  reached  its  final  destination,  and  came  forth  in  blows  from  the 
forge-hammer.  Great  inconvenience,  also,  was  found  to  result  from  having  a considerable  portion  of  the 
working  machinery  close  to  the  hammer,  as  thereby  a very  serious  impediment  was  offered  to  the  free 
execution  of  the  work.  And  when  we  add  to  this  very  limited  range  in  the  clear  fall  of  an  ordinary 
forge-hammer,  (seldom,  in  any  case,  exceeding  18  inches,)  causing  the  force  of  the  vlow  to  decrease  in  a 
very  rapid  ratio,  with  a moderate  increase  in  the  diameter  or  depth  of  the  work  ; and  when  we  take 
into  consideration  the  fact  that,  in  consequence  of  the  helve  of  the  hammer  working  on  a centre  or  joint, 
its  face  is  parallel  to  that  of  the  anvil  only  at  one  particular  distance ; and  finally,  when  to  this  list  of 
inconveniences  we  add  that  in  the  ordinary  forge-hammer  we  possess  no  power  or  control  over  the  force 
of  its  blows,  but  are  compelled  to  make  the  best  use  y/e  can  of  them,  whether  they  be  adapted  to  our 
purpose  at  the  time  or  otherwise,  we  find  inherent  in  the  very  principle  of  such  hammers,  a combina- 
tion of  evils  and  inconveniences  that  only  excite  surprise  that  they  should  have  been  suffered  to  exist 
for  so  great  a length  of  time. 

This  remark  is  most  strikingly  applicable  in  file  case  of  those  forge-hammers  which  receive  their 
power  from  a steam-engine,  inasmuch  as  the  power  in  question  originates  in  the  motion  of  the  piston, 
m the  very  state  and  condition  in  which,  for  the  purpose  of  hammering,  we  desire  it  ultimately  to  be, 
namely,  as  a straight  up  and  down  motion  ; so  that  instead  of  causing  this  reciprocating  action  of  the 
piston-rod  to  pass  through  all  the  complex  media  of  beam,  connecting-rod,  crank  and  cam  shaft,  for  no 


4 


HAMMER. 


other  purpose  than  to  cause  it  to  act  in  the  same  manner  as  at  first,— if  we  dispense  with  all  this  mas* 
of  intermediate  machinery,  and  simply  invert  the  steam  cylinder  so  as  to  bring  its  piston-rod  out  at  tbs 
bottom  of  the  cylinder,  and  attach  it  directly  to  a block  of  iron  working  in  guides  right  over  the  anvii 


HAMMER. 


3 


Some  idea  of  its  efficiency  in  shingling  puddled  balls  may  be  formed  from  the  fact,  that  one  of  3C 
rwt.,  which  has  been  for  nearly  two  years  in  constant  operation  at  the  Gartness  Works  of  the  Monkland 
Iron  Company,  in  the  West  of  Scotland,  works  off  with  perfect  ease  the  constant  produce  of  from  18  to 
20  puddling  furnaces.  For  this  duty  the  steam-hammer  is  found  to  be  peculiarly  adapted,  as  it  can  be 
made  to  act  for  the  first  few  strokes  as  a squeezer,  to  bring  the  puddled  ball  to  a neat  cubical  form ; 
after  which  it  may  be  made  to  deal  out  upon  it  such  energetic  blows  as  secures  the  entire  expulsion  of 
all  cinder  and  other  non-metallic  impurities,  the  absence  of  which,  to  a greater  or  less  extent,  mainly 
determines  the  quality  of  wrought-iron.  In  short,  in  every  process  where  either  blows  of  the  most 
enormous  energy,  or  slight  taps  of  {lie  utmost  gentleness  are  required,  either  continuously  or  in  all 
grades  of  variation  from  the  one  extreme  to  the  other,  the  steam-hammer  offers  facilities  which  have 
never  hitherto  been  obtained  from  any  mechanical  contrivance  for  such  purposes. 

Fig.  2244  represents  a side  elevation  of  the  steam-hammer,  exhibited  in  full  operation,  the  hammer 
block,  valve-geer,  and  other  working  parts  being  disposed  in  the  positions  which  they  occupy  at  the 
termination  of  a stroke.  Fig.  2245  is  a general  plan  corresponding  to  the  above. 

Fig.  2246  is  an  end  elevation,  and  Fig.  224*7  a vertical  transverse  section  of  the  machine. 

Fig.  2248  is  a sectional  elevation  of  a portion  of  the  machine,  showing  the  positions  of  the  hammer- 
block,  valve-geer,  and  other  working  parts  when  the  hammer  is  raised  for  a fresh  stroke. 

The  framing  of  the  steam-hammer  consists  of  two  strong  cast-iron  standards  A A,  bolted  and  further 
secured  by  keys  to  a broad  base-plate  B B,  embedded  in  the  solid  masonry  forming  part  of  the  floor  of 
the  forge.  The  standards  are  surmounted,  and  their  upper  extremities  united  by  a species  of  entabla- 
ture C,  in  which  the  steam-passages  and  valve-face  are  formed,  and  to  the  upper  surface  of  which  the 
steam  cylinder  D is  bolted.  The  piston-rod  E is  fitted  to  work  vertically  through  a stuffing-box  in  the 
centre  of  this  entablature,  and  its  lower  extremity  is  directly  attached  to  the  mass  of  cast-iron  F,  form- 
ing the  hammer-block,  which  is  guided  to  a strictly  vertical  and  rectilinear  course  by  being  made  to 
work  freely  in  planed  guides  formed  on  the  interior  surfaces  of  the  standards  A A.  The  hammer  a 
itself  is  inserted  into  a dovetail  recess  in  the  bottom  of  the  block  F,  where  it  is  retained  by  wooden 
packing  and  iron  wedges ; while  the  anvil  b is  in  a similar  manner  secured  to  the  anvil-block  G,  which 
is  a mass  of  cast-iron  of  such  weight  as  effectually  to  oppose,  by  its  inertia,  the  momentum  of  the  ham- 
mer, and  prevent  the  force  of  the  blows  from  being  dissipated. 

Such  are  the  main  features  of  this  machine ; from  which  it  will  be  at  once  understood  that,  if  we  can 
provide  the  means  of  rapidly  raising  the  hammer-block  to  a sufficient  elevation,  and  then  as  rapidly 
letting  it  fall  down  upon,  and  so  give  a blow  to  the  work  placed  upon  the  anvil,  we  have  all  that  is 
requisite  to  produce  a forge-hammer  in  its  simplest,  and,  at  the  same  time,  its  most  powerful  and  per 
feet  form. 

The  duty  above  adverted  to,  of  raising  the  hammer-block,  is  performed  by  the  direct  application  of 
the  elastic  force  of  steam.  For  this  purpose,  the  steam  is  led  on  to  the  machine  by  the  steam-pipe  H. 
communicating  with  a neighboring  high-pressure  boiler ; a throttle,  or  shut-off  valve  c,  inclosed  within 
the  valve-box  I,  being  situated  close  to  its  junction  with  the  main  steam-valve  chest  J,  and  brought 
within  the  control  of  the  attendant  workman  by  means  of  the  rod  and  lever  eld.  The  alternate  admis- 
sion of  the  steam  into  the  cylinder  by  the  port/,  and  its  escape  therefrom  by  the  passage  g , and  waste 
steam-pipe  K,  are  regulated  by  means  of  the  slide-valve  e,  which  may  either  be  worked  by  hand,  or, 
through  the  intervention  of  the  self-acting  mechanism  to  be  hereafter  specified,  by  the  action  of  the 
machine  itself.  The  piston  L,  which  is  strongly  constructed  of  malleable  iron,  and  fitted  with  a single 
packing  ring,  works  steam-tight  within  the  cylinder  D ; and  being  directly  attached  by  the  piston-rod 
E to  the  hammer-block  F,  it  will  be  obvious  that,  on  the  admission  of  steam  of  sufficient  elastic  force 
beneath  the  piston,  we  are  supplied  with  the  means  of  raising  the  hammer-block  to  any  required  height 
within  the  range  of  the  machine ; while  by  opening  the  communication  between  the  under  side  of  the 
piston  and  the  external  atmosphere,  the  action  of  gravity  will  be  unimpeded,  and  the  hammer  will  de- 
scend upon  the  work  placed  on  the  anvil,  and  discharge  a blow  upon  it,  energetic  in  proportion  to  the 
weight  of  the  hammer-block,  and  the  height  from  which  it  has  fallen. 

And  as,  by  these  simple  means,  there  is  no  practical  inconvenience  in  supplying  the  power  to  raise  a 
hammer-block  of  5 or  6 tons  weight  to  an  elevation  of  *7  or  8 feet  above  the  anvil,  some  idea  may  be 
formed  of  the  vast  energy  of  the  blows  given  out  by  such  a mass  of  iron  falling  rapidly  through  so  great 
a space,  and  discharging  the  whole  of  its  momentum  upon  the  work  placed  below  on  the  anvil  to  re- 
ceive it.  In  the  case  of  the  old  system  of  forge  or  helve  hammers,  about  one-third  only  of  the  total 
weight  of  the  hammer  was  effective,  the  other  two-thirds  resting  on  the  pivot-standards;  so  that,  in  this 
point  of  view,  the  proportion  between  the  blow  of  a steam-hammer  and  that  of  a helve-hammer  is 
nearly  3 to  1 in  favor  of  the  former. 

It  will  be  seen,  further,  that  the  anvil-face  and  hammer-face  are  at  all  times  parallel  to  each  other, 
whatever  be  the  height  or  distance  between  them.  The  practical  value  and  importance  of  this  prop- 
erty,  which  is  inherent  in  the  principle  of  the  steam-hammer,  has  been  duly  appreciated  by  all  who 
have  had  experience  of  the  working  of  this  machine. 

With  a view  to  prevent  any  risk  of  the  piston  striking  the  cylinder-cover  when  working  to  the  full, 
or  veiy  highest  stroke  of  the  hammer,  a very  simple  but  effective  air  or  steam  recoil  spring  is  provided, 
by  having  the  cylinder-cover  screwed  down  quite  air-tight,  so  that  as  soon  as  the  piston  passes,  in  its 
upward  motion,  the  holes  hh,  the  air  or  steam  remaining  above  is  shut  up  in  the  upper  chamber;  and 
as  it  has  no  means  of  escape,  it  acts  as  a most  perfect  spring  in  arresting  any  further  rise  of  the  piston ; 
and  has,  besides,  the  important  advantage  of  converting  into  increased  downward  velocity  of  action  the 
undue  upward  action,  which  might  otherwise  have  proved  not  only  useless,  but  destructive.  The  in- 
crease of  energy  in  the  blows  which  can  be  obtained  by  this  simple,  means  is  a point  of  considerable 
importance.  It  is  scarcely  necessary  to  remark  that,  in  the  emergency  above  adverted  to,  the  aper- 
tures h h act  as  safety-valves  for  the  issue  of  the  main  body  of  the  steam,  which  escapes  through  th# 
passage  i i,  into  the  exhaust  or  waste  steam-pipe  Iv. 


0 


HAMMER 


HAMMER 


Another  point  of  constructive  detail  worthy  of  special  notice  is,  the  peculiar  mode  adopted  for  con- 
necting the  piston-rod  to  the  hammer-block.  This  is  one  of  the  most  important  details  in  the  entir* 
invention,  and  without  which  no  practical  success  would  have  attended  it.  Had  the  piston-rod 
been  attached  to  the  hammer  in  the  ordinary 
mode  of  attaching  pistons  to  the  machinery  of  a 
steam-engine  or  such  like,  namely,  by  a cotter, 
or  by  screwing  the  rod  into  the  hammer,  or  such 
other  solid,  unyielding  mode,  the  effect  of  the 
blow  or  fall,  at  each  stroke  of  the  hammer,  would 
have  been  that  the  piston-rod  and  piston  (being 
composed  of  a considerable  mass  of  materials) 
would  have  themselves  acted  as  a hammer,  and 
would  have  discharged  their  momentum  upon 
the  means  of  fastening,  and  this  with  such  de- 
structive effect  as  to  break  through  all  such  solid, 
unyielding  means  of  resistance,  after  a few  blows. 

This  was  foreseen  from  the  first  as  an  action 
to  be  prevented,  and  accordingly,  in  my  original 
drawing,  already  adverted  to,  a remedy  was  pro- 
vided, which  experience  has  proved  to  be  entirely 
effectual. 

This  contrivance  consists  in  placing,  in  a cylin- 
drical recess  formed  in  the  body  of  the  hammer- 
block,  and  under  the  knob  i,  on  the  end  of  the 
piston-rod,  a series  of  pieces  of  hard  wood,  or 
other  slightly  elastic  material,  as  in  Fig.  2246. 

The  effect  of  this  arrangement  is  to  allow  the 
momentum  of  the  piston  and  piston-rod  to  de- 
posit itself  in  such  a comparatively  gradual  man- 
ner as  to  cause  the  concussion  arising  from  the 
most  severe  and  energetic  blows  of  the  hammer 
to  have  not  the  slightest  evil  effects  on  the  piston 
and  rod ; it  is,  in  fact,  the  very  same  expedient 
to  which  nature  has  had  recourse  for  the  pur- 
pose of  obviating  those  unpleasant  and  destruc- 
tive shocks  and  vibrations  which  we  should  ex- 
perience at  every  step  or  stamp  of  the  foot,  had 
no  cartilage  been  provided  between  the  joints  of 
our  bones.  It  is  surprising  to  observe  by  how 
small  an  amount  of  elasticity,  from  the  employ- 
ment of  such  compressible  material,  the  evil 
effect  of  violent  shocks  may  be  removed.  The 
connection  of  the  piston-rod  and  hammer-block 
is  secured  by  means  of  the  two  keys  k k,  driven 
very  firmly  above  the  knob  or  button  j,  a layer  or 
two  of  the  elastic  material  being  interposed  for 
the  purpose  of  neutralizing  any  shock  in  the  con- 
trary direction. 

We  shall  now  proceed  to  describe  the  mechan- 
ism by  which  the  height  of  the  fall  of  the  ham 
mer,  and  consequent  intensity  of  the  blow,  may 
be  modified  according  to  circumstances,  and  the 
machine  made  perfectly  self-acting. 

The  requisite  alternating  motion  of  the  steam- 
valve  e is  produced  in  the  following  manner : — 

The  valve-spindle  l is  prolonged  upwards  and 
attached  to  a small  solid  piston  m,  working 
within  a short  cylinder  M,  bolted  to  the  main 
steam  cylinder  D.  A small  portion  of  steam  is 
supplied  above  the  piston  m,  by  a slender  copper 
tube  n,  communicating  with  the  steam  valve- 
chest  J ; by  this  arrangement  it  will  be  seen 
that,  unless  counteracted  by  some  superior  force, 
the  pressure  of  the  steam  upon  the  piston  m will 
tend  to  keep  the  valve  e constantly  depressed, 
in  which  position  the  steam-port  / is  full  open. 

This  counteracting  force  is  supplied  by  the  action 
of  the  hammer  itself;  for,  by  means  of  the  tap- 
pet 1ST,  (which  is  bolted  to  the  hammer-block,) 
coming  into  sliding  contact,  when  the  latter  is 
raised,  with  the  small  friction-roller  o,  mounted  on  the  end  of  a bent  lever  0 0,  the  screwed  rod  P 
which  is  jointed  to  the  opposite  end  of  that  lever,  is  depressed,  and  that  motion  being  communicated  to 
the  valve-spindle  l,  through  the  intervention  of  the  oonnecting-rod  Q and  valve-lever  R,  the  steam 


8 


HAMMER. 


valve  e is  raised,  thus  cutting  off  all  further  ingress  of  steam  under  the  piston,  and  almost  at  the  same 
instant  permitting  the  escape  of  that  which  had  served  to  raise  the  hammer.  By  this  simple  contri- 
vance the  upward  motion  of  the  hammer  is  made  the  agent  for  its  own  control  in  that  respect.  By  com- 
paring the  relative  positions  of  the  parts  referred  to,  as  exhibited  in  Figs.  2244  and  2248,  the  nature  of 
the  motion  above  described  will  be  at  once  most  fully  understood.  To  obviate  the  injurious  effects  oi 
the  shock  of  the  tappet  N against  the  lever  0,  a connection  is  provided  at  p,  on  a similar  principle  to 
that  formerly  described  in  reference  to  the  connection  of  the  piston-rod  and  the  hammer-block ; and  in 
order  to  restrict  the  downward  travel  of  the  valve  to  the  proper  point,  a check  or  buffer-box  S is  pro- 
vided, consisting  of  a small  cylinder  bolted  firmly  to  the  framing  of  the  machine,  within  which  a circular 
nut,  screwed  on  the  lower  end  of  the  rod  P,  works  as  a piston,  a few  leather  washers  being  interposed 
between  the  latter  and  the  close  or  upper  end  of  the  cylinder. 

It  may  be  here  remarked,  that  it  is  by  no  means  necessary  to  continue  the  admission  of  steam  under 
the  piston  until  the  termination  of  the  upward  stroke,  or  lift  of  the  hammer,  seeing  that  the  velocity 
which  the  hammer-block  has  acquired  in  its  upward  motion  makes  it  continue  to  ascend  after  the  fur- 
ther ingress  of  the  steam  has  been  arrested.  This  circumstance  is  a source  of  considerable  economy  of 
steam,  as  we  have  by  such  action  (as  well  as  by  that  due  to  the  expansive  energy  of  the  steam)  an 
effect  as  to  height  of  lift  of  the  hammer,  greater  than  that  which  is  due  to  the  actual  expenditure  of 
steam  at  its  original  pressure.  It  is  worthy  of  remark,  also,  that  as  the  over-running  action  above 
alluded  to  will  necessarily  increase  in  proportion  to  the  velocity  of  ascent  of  the  hammer-block,  this  cir- 
cumstance will,  to  a considerable  extent,  compensate  for  the  increased  expenditure  of  steam  due  to  that 
increased  velocity. 

From  the  above  description  it  will  be  obvious,  that  the  lift  of 'the  hammer,  and  consequent  intensity 
of  the  blows,  depends  simply  upon  the  position  of  the  lever  0,  in  relation  to  that  of  the  hammer-block 
when  at  its  lowest  point.  Therefore,  if  we  can  provide  the  means  of  altering  the  distance  between 
these  two  points,  we  shall  have  it  in  our  power  to  modify  permanently  the  force  of  the  blows  to  any 
required  extent  within  the  range  of  the  machine.  This  condition  is  most  completely  satisfied  by  the 
arrangement  of  mechanism  employed  by  me,  and  which  is  clearly  represented  in  the  figures. 

The  rod  P which  conveys  the  action  of  the  lever  O to  the  valve-lever  R,  is  screwed  throughout  the 
greater  part  of  its  length,  and  is  so  adjusted  in  its  bearings,  as  to  be  susceptible  of  rotatory  as  well  as 
vertical  motion.  This  motion  of  rotation  is  imparted  to  it  by  means  of  a handle  fixed  to  a short  axis, 
working  in  a bracket  T bolted  to  the  framing,  and  actuating  a pair  of  small  bevel- wheels  q q.  The  nut 
through  which  the  screw  works  forms  the  point  of  attachment  between  the  rod  P and  the  lever  O,  the 
connection  being  effected  by  means  of  a short  intermediate  rod  for  the  sake  of  insuring  parallelism  of 
motion.  A pair  of  small  spur-wheels  r r,  (through  the  first  of  which  the  rod  P works  by  means  of  a 
sunk  feather,)  serve  to  transmit  the  angular  motion  of  the  rod  P to  a similar  screwed-rod  U,  situated 
parallel  to  and  at  a short  distance  from  the  former ; the  nut  of  the  screw  U forms  the  fulcrum  or  centre 
of  motion  of  the  lever  O,  and  the  pitch  of  the  threads  of  both  screws  being  equal,  though  formed  in  con- 
trary directions  to  each  other,  it  is  obvious  that,  on  turning  the  handle,  the  lever  O and  all  its  appen- 
dages will  be  simultaneously  raised  or  depressed,  and  consequently  the  lift  of  the  hammer  regulated  to 
any  required  extent,  and  its  amount  altered  witli  the  utmost  ease  and  precision.  The  pin  which  forms 
the  centre  of  motion  of  the  lever  0 is  protected  and  secured  from  lateral  strains  by  the  cast-iron  guides 
Y and  W,  seen  most  distinctly  in  the  sectional  plan,  Fig.  2245. 

A most  essential  part  of  the  self-acting  geer  remains  yet  to  be  noticed.  It  is  obvious  that,  were  no 
provision  made  for  the  retention  of  the  steam-valve  in  the  position  into  which  it  is  thrown  by  the  up- 
ward motion  of  the  hammer-block,  the  latter  would  not  be  permitted  to  have  its  due  effect  in  the 
accomplishment  of  its  work ; for,  as  soon  as  it  descended  so  far  as  to  relieve  the  end  of  the  lever  0 from 
contact  witli  the  tappet  X,  the  valve  would  resume  the  position  into  which  it  is  constantly  solicited  by 
the  action  of  the  steam-spring  at  M,  and  the  descent  of  the  blow  would  be  impeded  by  the  return  of  the 
steam  into  the  cylinder,  before  the  hammer  had  completed  its  fall.  To  obviate  this  inconvenience,  a 
simple  but  most  effectual  contrivance  has  been  applied.  Towards  the  lower  extremity  of  the  valve- 
screw  P a shoulder  is  formed,  against  which  a short  lever  w,  called  the  trigger,  is  constantly  pressed  by 
the  spring  x,  so  that  when  the  rod  P is  depressed  by  the  action  of  the  lever  0,  it  is  arrested  by  the 
trigger  and  retained  in  that  position  until  the  blow  has  been  struck.  This  delicate  and  most  important 
part  of  the  mechanism  is  very  carefully  constructed,  the  point  of  the  trigger,  and  the  shoulder  against 
which  it  acts,  being  formed  oPsteel,  and  hardened  to  resist  wear. 

To  release  the  valve-screw  from  the  trigger,  and  so  permit  the  return  of  the  valve  into  the  position 
requisite  for  effecting  a fresh  stroke,  the  following  mechanism  has  been  adopted : on  the  front  of  the 
hammer-block,  Figs.  2244  and  2248,  a lever  X,  called  the  latch-lever,  is  fitted  to  work  freely  on  a pin 
passing  through  the  body  of  the  hammer-block.  That  portion  of  the  latch-lever  which  is  most  remote 
from  the  valve-geer  is  considerably  heavier  than  the  opposite  end,  and  is  constantly  pressed  upwards 
by  means  of  a spring.  The  lighter  end  is  brought  into  contact  with  a long  bar  s s,  called  the  parallel 
bar,  the  extremities  of  which  are  suspended  upon  two  small  bell-cranks  1 1,  whose  other  arms  are  con 
nected  by  means  of  a slender  rod  u.  Fig  2247,  forming  a species  of  parallel  motion,  for  the  purpose  of 
adapting  this  geer  to  come  into  efficient  operation,  at  whatever  point  in  the  range  of  the  hammer  its 
blow  may  be  arrested.  A small  connecting-rod  v,  between  the  lower  bell-crank  and  a short  lever  on 
the  axis  of  the  trigger  w,  completes  this  part  of  the  mechanism. 

The  action  of  this  geer  is  of  a very  peculiar  nature,  and  is  admirably  adapted  to  fulfil  the  object  in- 
tended. At  the  instant  the  hammer  gives  a blow  to  the  work  upon  the  anvil,  the  effect  of  the  concus- 
sion is  to  cause  the  momentum  of  the  heavy  end  of  the  lever  X to  overcome  the  upward  pressure  of  the 
spring,  and  thereby  to  protrude  its  opposite  end  against  the  edge  of  the  parallel  bar  s,  which  motion, 
though  but  slight  in  amount,  is  yet  adequate,  through  the  arrangements  above  described,  to  throw  back 
the  trigger  from  contact  with  the  valve-screw,  and  leave  the  latter  free  to  obey  the  impulse  of  the  steam- 
spring in  the  readjustment  of  the  valve  into  its  original  position. 


HAT-MAKING. 


9 


These  various  movements,  which  have  taken  so  long  to  describe,  are  all  performed  in  less  than  half 
% second,  and  consequently  the  action  of  the  hammer  is  proportionally  rapid. 

The  construction  of  the  self-acting  geer  is  so  arranged  as  to  admit  of  advantage  being  taken,  when 
circumstances  render  it  desirable,  of  the  very  action  to  obviate  which  the  trigger  w is  introduced.  WheD 
it  is  desired  to  strike  a gentle  blow,  such  as  is  frequently  required  during  particular  stages  in  the  prog- 
ress of  a piece  of  work,  it  is  not  requisite,  for  this  purpose,  to  change  the  position  of  the  valve-lever  O. 
All  that  has  to  be  done  is  to  hold  back  the  point  of  the  trigger  w,  by  its  handle  y ; this  permits  the 
valve  to  reopen  and  let  the  steam  in  under  the  piston  L,  at  the  instant  the  tappet  N has  fallen  away 
from  contact  with  the  lever  0.  The  effect  of  this  is,  that  a quantity  of  steam  is  admitted  into  the  cylin- 
der under  the  piston,  which  serves  as  a cushion,  by  which  the  violent  fall  of  the  hammer  is  arrested, 
and  its  momentum  modified  to  any  extent,  or  at  the  pleasure  of  the  person  in  charge  of  the  handles. 
The  handle  2,  is  for  the  purpose  of  placing  the  steam-valve  also  under  his  control,  and,  for  Iris  further 
convenience  in  the  management  of  the  hammer,  a platform  Y and  hand-rail  Z are  erected  against  the 
framing  of  the  machine. 

A modification  of  the  frame  of  this  machine  has  been  made  at  the  Washington  Navy  Yard,  one  sup- 
port only  being  used,  by  which  means  access  is  had  to  the  anvil  on  all  sides  except  that  occupied  by 
the  support. 

HAMMER,  Tilt  or  Trip.  See  Tilting. 

HARVESTER.  An  agricultural  machine  for  reaping  and  gathering  in  grain,  much  used  in  the 
western  country.  There  are  many  forms  of  them,  known  in  this  part  of  the  country  as  Reapers, 
which  see. 

HAT-MAKING  embraces  two  distinct  kinds  of  manufacture,  felted  and  covered  hats ; the  covering 
of  the  latter  being  sometimes  silk,  and  at  other  times  cotton. 

Felted  hats  comprehend  two  classes,  differing  chiefly  in  the  materials  used  in  making,  the  process 
being  nearly  identical.  The  lower  class  is  marked  by  inferior  ingredients,  unmixed  with  beaver,  and 
embraces  wool,  plated,  and  short-nap  hats. 

Wool  hats  are  made  entirely  of  coarse  native  wool  and  hair  stiffened  with  glue.  Plates  have  a nap 
or  pile  rather  finer  than  their  body,  and  are  sometimes  water-proof  stiffened.  Short  naps  are  distin- 
guished from  plates  by  additional  kinds  of  wool,  viz.  hare’s  back,  seal,  neuter,  musquash,  (Muscovy  cat,) 
and  are  all  water-proof  stiffened. 

The  second  class  may  be  said  to  comprehend  two  orders,  called  stuff  and  beaver  hats.  The  first  in- 
cludes mottled  and  stuff  bodies.  The  latter  term  is  not  used  generally,  as  all  stuffs  are  understood  to 
be  of  this  sort  when  mottled  is  not  expressed.  Mottled  bodies  are  made  chiefly  of  fine  wool,  and  inferior 
rabbit  down  or  coney  wool.  Stuff  bodies  consist  of  the  best  hare,  Saxony,  and  red  wools,  mixed  with 
Cashmere  hair  and  silk.  Stuff  hats  are  napped,  that  is,  covered  with  pile  of  mixed  seal,  neuter,  hare- 
back,  inferior  beaver,  and  musquash.  Beaver  hats  are,  or  ought  to  be,  napped  with  beaver  only  ; the 
lower  priced  qualities  with  brown  wooms  taken  from  the  back ; the  more  valuable  kinds  with  cheek  and 
white  wooms,  being  the  finest  parts  of  the  fur  found  on  the  belly  and  cheeks  of  the  beaver. 

The  apparatus  and  terms  used  in  making  felted  hats,  which  it  is  necessary  to  describe  briefly,  are  the 
bow,  basket,  hurdle,  battery,  and  planks. 

The  bow  is  about  six  feet  long,  usually  made  of  ash,  thick  enough  not  to  be  elastic.  The  handle  is 
called  the  stang.  The  bow-string  is  a strong  catgut  cord  tensely  fastened. 

The  hurdle  is  a fixed  bench,  with  three  enclosing  sides,  to  prevent  the  stuff  being  flittered  off  in 
bowing. 

The  basket  is  of  light  wicker-work,  about  twenty  by  twenty-two  inches  in  size. 

The  battery  consists  of  the  kettle  and  the  planks,  which  are  inclined  planes,  usually  eight  in  number, 
one  only  being  appropriated  to  each  workman.  The  half  of  each  plank  next  the  kettle  is  lead,  the 
upper  half  is  mahogany. 

The  first  process  in  hat-making  is  bowing  the  stuff  or  furs,  which  are  weighed  out  to  a proportionate  scale, 
and  laid  on  the  hurdle,  immediately  under  the  bow,  which  is  suspended  by  a pulley.  The  bow  is  held 
firmly  with  the  left  hand,  rather  towards  the  breech-end,  not  edgewise,  but  on  its  side,  with  the  string  in 
contact  with  the  stuff,  the  clotted  and  adherent  portions  of  which  are  separated  into  single  fibres,  and 
attain  a loose,  flocky,  mixed  condition  by  the  continued  viiration  of  the  bow-string,  caused  by  a very  rapid 
succession  of  touches  with  the  bow-stick.  It  is  then  divided  as  nearly  as  possible,  and  one-half  laid  aside, 
whilst  the  other  is  again  bowed.  In  this  second  operation,  partly  by  the  bowing,  but  chiefly  by  the  gather- 
big,  or  patting  use  of  the  basket,  the  stuff  is  loosely  matted  into  a conical  figure,  about  fifty  by  thirty-six 
inches,  called  a bat.  In  this  formation  care  is  taken  to  work  about  two-thirds  of  the  wools  down  to- 
wards what  is  intended  for  the  brim,  which  being  effected,  greater  density  is  induced  by  gentle  pressure 
with  the  basket.  It  is  then  covered  with  a wettish  linen  cloth,  upon  which  is  laid  the  hardening  skin. 
a piece  of  dry  half-tanned  horse-hide.  On  this  the  workman  presses  or  bakes  for  seven  or  eight 
minutes,  until  the  stuff  shall  have  adhered  closely  to  the  damp  cloth,  in  which  it  is  then  doubled  up, 
freely  pressed  with  the  hand,  and  laid  aside.  By  this  process,  called  basoning,  (from  a metal  plate  or 
bason,  used  for  like  purposes  in  making  wool  hats,)  the  bat  has  become  compactly  felted  and  thinned 
towards  the  sides  and  point.  The  other  half  of  the  flocked  stuff  is  next  subjected  to  precisely  the  same 
proceedings,  after  which,  a cone-shaped  slip  of  stiff  paper  is  laid  on  its  surface,  and  the  sides  of  the  bat 
folded  over  its  edges  to  its  form  and  size.  It  is  then  laid  paper-side  downward  upon  the  first  bat, 
which  is  now  replaced  on  the  hurdle,  and  its  edges  transversely  doubled  over  the  introverted  side-lays 
of  the  second  bat,  thus  giving  equal  thickness  to  the  whole  body.  In  this  condition  it  is  reintroduced 
between  folds  of  damp  linen  cloth,  and  again  hardened,  so  as  to  unite  both  halves,  the  knitting  together 
of  which  is  quickly  effected.  The  paper  is  now  withdrawn,  and  the  body  being  folded  into  three  plies, 
is  removed  to  the  plank  or  battery-room. 

In  the  battery  the  liquor  is  scalding  heat,  composed  of  pure  soft  water,  with  about  half  a gill  of 
nil  of  vitriol  as  an  astringent.  Herein  the  body  is  imbrued,  and  withdrawn  to  the  plank  to  partly 


10 


HAT-MAKING. 


cool  and  drain,  when  it  is  unfolded,  rolled  gently  with  a pin  tapering  towards  the  ends  like  a liqnot 
horse,  turned,  and  worked  with  in  every  direction,  to  toughen,  shrink,  and  at  the  same  time  prevent 
adhesion  of  its  sides.  Stopping  or  thickening  the  thin  spots  which  now  appear  on  looking  through  the 
body,  is  carefully  performed,  by  additional  stuff  daubed  on  by  successive  supplies  of  the  hot  liquor 
from  a brush  frequently  dipped  into  the  kettle,  until  the  body  be  shrunk  sufficiently,  (about  one-half,) 
and  thoroughly  equalized.  When  quite  dried,  stiffening  is  performed  with  a brush  dipped  into  a 
glutinous  pulpy  composition,  and  rubbed  into  the  body ; the  surface  intended  for  the  inside  having  much 
more  imposed  than  the  outer,  while  the  brim  is  made  to  absorb  many  times  the  quantity  applied  to 
any  other  part.  This  viscous  matter  contains  proofing,  or  those  ingredients  which  render  the  hat  water- 
proof. 

On  being  again  dried,  the  body  is  ready  to  be  covered,  and  is  once  more  taken  to  the  battery.  The 
first  cover  of  beaver  or  napping,  which  has  been  previously  bowed,  is  equally  strewed  on  the  body,  and 
patted  upon  with  the  brush  charged  with  the  hot  liquor,  until  incorporated ; the  cut  ends  only  being 
the  points  which  naturally  intrude.  Here  the  body  is  put  into  a coarse  hair-cloth  dipped  and  rolled  in 
the  hot  liquor,  until  the  beaver  is  quite  worked  in.  This  is  called  rolling  off,  or  ruffing.  A stripe  for 
the  brim  round  the  edge  of  the  inside,  is  treated  in  like  manner,  and  is  thus  prepared  for  the  second 
cover,  which  is  applied  and  inworked  in  like  manner ; the  rolling,  &e.,  being  continued  until  the  whole 
has  become  incorporated,  and  a clean,  regular',  close,  and  well-felted  hood  is  the  result.  The  dry  hood, 
after  having  the  nap  beat  up  and  freed,  is  clipped  to  the  length  which  may  be  thought  best,  by  means 
of  common  shears.  A clipping  machine,  invented  nearly  four  years  ago  in  Scotland,  is  now  very 
generally  preferred,  and  doubtless  will  soon  everywhere  supersede  the  ordinary  process ; much  greater 
regularity,  speed,  and  certainty  being  secured  by  it.  When  the  nap  is  thus  disposed  of,  the  hood  is 
soaked  in  the  battery  kettle,  and  then  drawn  down  on  a block  to  the  size  and  shape  wanted,  firmly  tied 
at  the  bottom  with  a cord,  around  which  the  brim  is  left  in  a frilled  condition. 

Dyeing  is  the  next  step.  A suit,  or  six  dozen,  are  put  into  the  dye-kettle  at  a time,  all  on  the  crown- 
blocks  already  mentioned,  and  allowed  to  remain  three-quarters  of  an  hour  in  the  liquor,  which  is  kept 
as  near  as  possible  one  degree  below  the  boiling  point.  These  being  taken  out  and  set  in  the  yard  to 
cool,  another  suit  is  introduced  for  a like  period,  and  the  various  suits  are  so  treated  at  least  twelve 
times  in  successive  order.  Each  of  the  first  four  introgressions  of  every  suit  is  accompanied  by  about 
seven  pounds  of  copperas,  and  two  pounds  of  verdigris.  The  body  is  then  washed  and  brushed  out  in 
changes  of  hot  water,  until  no  coloring  can  be  recognized  in  it.  When  thus  thoroughly  cleansed,  it  is 
steamed  on  a block  shaped  as  the  hat  is  wished  to  be  when  complete ; and  in  the  finishing  shop  by 
neavy  (21 -pound)  heated  irons  and  moisture,  the  frilled  brim  is  shrunk  until  rendered  quite  level,  the 
nap  gently  raised  all  over  with  a fine  wire  card,  and  brushed  and  ironed  smooth  in  the  uniform  direc- 
tions. The  tip,  a thin  lath-sheet,  is  then  fitted  and  stuck  to  the  inside  of  the  crown,  and  robbined  or 
secured  all  round  the  edges  by  stripes  of  prepared  paper.  When  thus  got  down,  it  is  sent  to  th e picker, 
who,  with  tweezers,  extracts  the  hemps,  or  “ gray  hairs,”  which  are  a few  of  those  thick  fibres  peculiar 
to  the  fur  of  amphibious  animals,  that  have  escaped  the  search  of  the  machine  used  in  blowing  the 
beaver,  so  as  to  separate  them  from  its  fine  parts.  This  being  carefully  accomplished,  it  is  transferred 
to  the  finisher,  who,  with  a plush  cushion,  a brush,  and  hot  iron,  imparts  to  it  that  bright  sleeky 
lustre.  The  shaper  then  rounds  the  brim  with  a knife  and  notched  segment  to  the  breadth  wanted ; 
and  shapes  it  in  varied  styles  by  means  of  a hot  iron  and  damp,  with  about  a foot  length  of  rope, 
over  which  the  curl  is  laid.  The  trimming  is  next  done,  when  the  tipper-off  corrects  the  twists, 
smooths  the  ruffled  nap  caused  by  trimming,  and  papers  it  up  with  tissue  and  cartridge,  which  com- 
pletes it  for  the  retailer. 

Silk  bats  are  made  upon  bodies  of  wool,  stuff,  willow,  straw,  and  Leghorn  plait,  and  cambric  and 
woollen  cloth,  although  chiefly  on  felted  wool  bodies,  which  are  dipped  in  glue  size,  wrung  out,  blocked, 
and  dried.  The  tipi  is  then  fitted  and  robbined,  when  a flour-box,  charged  with  powdered  shell-lac  and 
rosin  in  like  quantities,  is  used  to  strew  equally  its  grainy  mixture  on  the  external  surface  of  the  shell, 
so  called  from  being  the  frame-work.  This  is  burned  in  by  hot  irons,  first  on  the  top,  which  passes 
through  to  the  lath-tip  within  ; then  on  the  upper  brim,  the  sides,  and,  finally,  the  under  brim.  When 
this  is  hardened  it  is  coated  with  thick  ordinary  flour-paste,  which  is  dried,  and  the  shell  again  blocked 
and  smoothed ; then  once  more  glue-sized  outside,  dried,  and  varnished,  which  prepares  it  for  covering. 
The  shag  for  the  sides  is  cut  across  the  web,  iu  a ratio  of  obliquity  increased  by  inferiority.  This  cross 
part  is  sown  to  a circular  piece  for  the  crown,  whilst  the  brims  are  singly  patched  together.  These 
preparations  being  completed,  the  top-side  or  upper  brim  is  first  stuck,  then  the  crown,  next  the  sides, 
and,  finally,  the  under  brim.  Sticking  is  effected  simply  by  the  heat  of  the  iron  passing  through  the 
covering  and  melting  the  varnished  surface.  In  the  finish  of  this  manufacture,  the  most  particular  part 
is  the  side-seam,  which  is  disposed  of  thus : The  selvidge  end  is  cut  perpendicularly  from  top  to  brim, 
by  a sharpened  pallet-knife,  the  nap  having  been  previously  brushed  clear  off  its  edge.  The  other 
selvidge  end  is  then  stuck  and  cut  with  the  utmost  nicety,  in  close  parallel  with  the  other.  It  is  then 
finished  very  much  in  the  same  manner  as  a beaver  hat. 

The  above-mentioned  method  of  making  hat-bodies  is  now  mostly  superseded  in  this  part  of  the 
country  by  the  adoption  of  machinery,  the  manual  labor  being  confined  to  the  getting  up  the  hat,  and  is 
a distinct  business ; the  hatter  for  the  most  part  purchasing  his  hat-bodies  far  cheaper  than  he  can 
make  them. 

The  machinery  is  very  simple.  The  fur  or  hair  of  which  the  felt  is  to  be  made,  after  being  cleaned 
and  lightly  beat  up,  by  passing  through  a kind  of  winnowing  machine,  is  delivered  to  a boy,  who 
spreads  the  fur  very  lightly  and  in  small  quantities  on  an  endless  web  before  him,  which,  passing  between 
rollers,  carries  the  fur  into  the  body  of  the  machine,  where  it  encounters  a cylindrical  brush  in  rapid 
motion,  which  separates  the  hair  or  fur  completely,  throwing  it  towards  a contracted  opening  in  the 
s'des  of  the  cylinder-case.  This  opening,  about  an  inch  wide  at  top  and  nearly  three  inches  at 
bottom,  is  in  height  equal  to  the  cone  of  the  hat-body,  Immediately  in  front,  and  close  to  this  opening. 


HEAT. 


11 


is  placed  a perforated  copper  cone,  the  perforations  so  small,  and  in  such  number,  as  almost  to  render 
the  surface  of  the  cone,  from  base  to  apex,  a wire-gauze  surface.  This  cone  is  open  at  the  bottom  and 
placed  on  an  opening  equal  to  its  base,  which  opening  is  in  communication  with  a fan  or  blast,  so  ar- 
ranged as  to  exhaust  the  interior,  or  “ suck,”  so  to  speak,  the  air  through  the  meshes  of  the  copper  cone. 
The  hair  or  fur  in  its  divided  state,  thrown  towards  this  opening  in  the  cylinder  case,  is  brought  under 
the  influence  of  the  powerful  draught  towards  and  through  the  cone ; the  latter  at  the  same  time  slowly- 
revolving  on  its  axis,  exposes  all  its  sides  to  the  opening,  and  the  hair  is  driven  against  it  with  such  force 
as  to  adhere  for  the  time,  and  receive  and  retain  on  all  sides,  as  it  revolves,  the  fine  particles  of  hair  as 
they  are  drawn  from  the  cone.  In  the  space  of  half  a minute  a dry  hat-bodv  is  formed  on  the  copper 
cone ; this  is  immediately  enveloped  by  a wetted  felt,  and  the  whole  immediately  removed,  and  its  place 
supplied  by  a fresh  copper  while  the  first  is  being  stripped  of  its  now  wet  felt.  The  whole  operation  is 
performed  with  wonderful  dispatch,  the  hat-body  resulting  from  it  being  exceedingly  light  and  uniform 
in  texture,  and  requires  but  little  labor  before  it  is  in  condition  to  be  transferred  to  the  hands  of  the 
hatter  for  working  up.  In  this  manner  any  form  of  felt  may  be  made.  The  opening  in  the  cylinder 
case  being  of  flexible  metal,  admits  of  adjustment  to  the  wants  of  the  particular  form  of  the  felt  to  be 
constructed.  The  application  of  this  principle  is  universal  in  the  manufacture  of  felt. 

HEART -WHEEL.  A cam  for  converting  a uniform  circular  into  a uniform  rectilinear  motion. 

HEAT.  Heat  in  the  ordinai-y  application  of  the  word,  implies  the  sensation  experienced  upon  touching 
a body  hotter  or  of  a higher  temperature.  Caloric , the  principle  or  cause  of  the  sensation  of  heat.  On  touch- 
ing a hot  body,  caloric  passes  from  it,  and  excites  the  feeling  of  warmth  : when  we  touch  a body  having  a 
lower  temperature  than  our  hand,  caloric  passes  from  the  hand  to  it,  and  thus  arises  the  sensation  of  cold. 

Caloric  is  usually  treated  of  as  if  it  were  a material  substance  ; but,  like  light  and  electricity,  its  true 
nature  has  yet  to  be  determined. 

Caloric  passes  through  different  bodies  with  different  degrees  of  velocity.  This  has  led  to  the  division 
of  bodies  into  conductors  and  non-conductors  of  caloric : the  former  includes  such  bodies  as  metals  which 
allow  caloric  to  pass  freely  through  their  substance,  and  the  latter  comprises  those  that  do  not  give  an 
easy  passage  to  it,  such  as  stones,  glass,  wood,  charcoal,  &c. 


Gold 

Silver 

Iron  

Tin 

Marble  ... 
Fire-brick 


Table  of  the  relative  Conducting  Power  of  different  Bodies. 


1000 

Platinum 

973 

Copper . . 

374 

Zinc  

304 

Lead 

24 

Porcelain 

11 

Fire-clay 

With  Water  as  the  Standard. 


Water 
Pine  . 
Lime . 
Oak... 


10 

39 

39 

33 


Elm  .. 
Ash.... 
A pple . 
Ebony 


Relative  Conducting  Power  of  different  Substances  compared  with  each  other. 


Hares’  fur .. 
Eider-down 
Beavers’  fur 
Raw  silk  . .. 

Wool 

Lamp-black 


1-315 

1-305 

1-296 

1-284 

1-118 

1-117 


Cotton  

Lint  

Charcoal  

Ashes  (wood) 
Sewing-silk  . . 
Air 


981 

898 

363 

180 

12-2 

11-4 


32 

31 

28 

oo 


1-046 

1-032 

•937 

•927 

■917 

■576 


Relative  Conducting  Power  of  Fluids. 

Mercury l'OOO  I Proof  spirit -312 

Water  -357  j Alcohol  (pure) -232 


Radiation  of  caloric. — When  heated  bodies  are  exposed  to  the  air,  they  lose  portions  of  their  heat, 
by  projection  in  right  lines  into  space,  from  all  parts  of  their  surface. 

Bodies  which  radiate  heat  best,  absorb  it  best. 

Radiation  is  affected  by  the  nature  of  the  surface  of  the  body ; thus,  black  and  rough  surfaces  radiate 
and  absorb  more  heat  than  light  and  polished  surfaces. 


Water 

Lamp-black  ... 
Writing-paper 

Glass 

India-ink  

Bright  lead  ... 
Silver  


Table  of  the  Radiating  Power  of  different  Bodies. 


100 

100 

100 

90 

88 

19 

12 


Blackened  tin 
Clean  “ 

Scraped  “ 

Ice  

Mercury 

Polished  iron  . 
Copper 


100 

12 

16 

85 

20 

15 

12 


Reflection  of  caloric  differs  from  radiation,  as  the  caloric  is  in  this  case  reflected  from  the  surface 
without  entering  the  substance  of  the  body : hence  the  body  which  radiates,  and  consequently  absorbs 
most  caloric,  reflects  the  least,  and  vice  versa. 

Latent  caloric  is  that  which  is  insensible  to  the  touch,  or  incapable  of  being  detected  by  the  thermom- 
eter. The  quantity  of  heat  necessary  to  enable  ice  to  assume  the  fluid  state  is  equal  to  that  wliiclt 


12 


HEAT. 


would  raise  the  temperature  of  the  same  weight  of  water  140°  ; and  an  equal  quantity  of  heat  ia  set 
free  from  water  when  it  assumes  the  solid  form. 

If  5^-  lbs.  of  water,  at  the  temperature  of  32°,  be  placed  in  a vessel  communicating  with  another  one, 
(in  which  water  is  kept  constantly  boiling  at  the  temperature  of  212°,)  until  the  former  reaches  this 
temperature  of  the  latter  quantity,  then  let  it  be  weighed,  and  it  will  be  found  to  weigh  6J  lbs.,  showing 
that  1 lb.  of  water  has  been  received  in  the  form  of  steam  through  the  communication,  and  reconverted 
'-■v.  water  by  the  lower  temperature  in  the  vessel. 

i >v  this  pound  of  water,  received  in  the  form  of  steam,  had,  when  in  that  form,  a temperature  oi 
21~J.  It  is  now  converted  into  the  liquid  form,  and  still  retains  the  same  temperature  of  212°,  but  it 
has  caused  5-J  lbs.  of  water  to  rise  from  the  temperature  of  32°  to  212°,  and  this  without  losing  any 
temperature  of  itself.  It  follows,  then,  that  in  returning  to  the  liquid  state,  it  has  parted  with  5-J-  times 
the  number  of  .degrees  of  temperature  between  32°  and  212°,  which  are  equal  180°,  and  180°  X 54  = 
990°.  Now  this  heat  was  combined  with  the  steam ; but  as  it  was  then  not  sensible  to  a thermometer, 
it  was  called  Latent. 

It  is  manifest,  then,  that  a pound  of  water,  in  passing  from  a liquid  at  212°  to  steam  at  212°,  receives 
as  much  heat  as  would  be  sufficient  to  raise  it  through  990  thermometric  degrees,  if  that  heat,  instead 
of  becoming  latent,  had  been  sensible. 

The  sum  of  the  sensible  and  latent  heat  of  steam  is  always  the  same  at  any  one  temperature ; thus, 
890° -f- 212°  = 1202°. 

If  to  a pound  of  newly  fallen  snow  were  added  a pound  of  water  at  172°,  the  snow  would  be  melted, 
and  32°  will  be  the  resulting  temperature,  138°  of  heat  becoming  latent  in  the  melted  snow. 


Latent  Heat  of  various  Substances. 


Fluids. 


Ice  140° 

Sulphur  144 

Lead 162 

Beeswax.: 175 

Zinc 493 


Vapors. 

Steam 990° 

Vinegar 875 

Ammonia 860 

Alcohol 442 

Ether 302 


Sensible  caloric  is  free  and  uncombined,  passing  from  one  substance  to  another,  affecting  the  senses  in 
its  passage,  determining  the  height  of  the  thermometer,  and  giving  rise  to  all  the  results  vfhich  are 
attributed  to  this  active  principle.  See  Steam. 

It  is  frequently  desirable  to  convert  the  degrees  of  heat,  as  indicated  by  one  thermometer,  into  its 
equivalent  as  denoted  by  another.  The  following  rules  will  serve  this  purpose  for  the  thermometers  in 
general  use : — 

To  reduce  the  degrees  of  a Fahrenheit  thermometer  to  those  of  Reaumur  and  of  the  centigrade ; the 
i,ero  of  the  Reaumur  scale  being  at  the  freezing  point,  and  80°  at  the  boiling  point,  whilst  the  zero  oi 
the  centigrade  is  at  the  freezing  point,  and  100°  at  the  boiling.  See  Thermometer. 

Fahrenheit  to  Reaumur. — Rule. — Multiply  the  number  of  degrees  above  or  below  the  freezing  point 
t>v  4,  and  divide  by  9. 

Thus,  212°  — 32  = 180  X 4 = 720  9 = 80,  Ans. 

+ 24°  — 32  = 8X4=  32  -7-9  = 3’5,  Ans. 

or  3'5  below  zero. 

Fahrenheit  to  centigrade. — Rule. — Multiply  the  number  of  degrees  above  or  below  the  freezing  point 
by  5,  and  divide  by  9. 

Thus,  212°  — 32  = 180  X 5 = 900  Q-  9 = 100,  Ans. 

Or  multiply  the  degrees  of  Fahrenheit  by  '444  for  reducing  them  to  Reaumur,  and  by  '555  for  reducing 
them  to  centigrade. 

Medium  heat  of  the  globe  is  placed  at  50°  ; at  the  torrid  zone,  75°  ; at  moderate  climates,  50°  ; near 
the  polar  regions,  36°. 

The  extremes  of  natural  heat  are  from  .70°  to  120°  ; of  artificial  heat,  from  91°  to  36,000°.’ 

Evaporation  produces  cold,  because  caloric  must  be  absorbed  in  the  formation  of  vapor,  a large 
quantity  of  it  passing  from  a sensible  to  a latent  state,  the  capacity  for  heat  of  the  vapor  formed  being 
greater  than  that  of  the  fluid  from  which  it  proceeds. 

Evaporation  proceeds  only  from  the  surface  of  the  fluids,  and  therefore,  other  things  equal,  must  depend 
uj>on  the  extent  of  surface  exposed. 

When  a liquid  is  covered  by  a stratum  of  dry  air,  evaporation  is  rapid,  even  when  the  temperature 
is  low. 

Table  of  Effects  upon  Bodies  by  Heat. 


Fahrenheit. 


Cast-iron,  thoroughly  smelted 27  54° 

Fine  gold,  melts 1983 

Fins  silver,  melts 1850 

Copper  melts  2160 

Brass,  melts 1900 

Red  heat,  visible  by  day 1077 

Iron,  red-hot  in  twilight 884 

Common  fire 790 

Iron,  bright-red  in  the  dark 752 

Zinc,  melts  740 

Quicksilver,  boils 630 

Linseed  oil  boils 600 


Fahrenheit 


Lead,  melts 5943 

Bismuth,  melts 476 

Tin,  melts 421 

Tin  and  bismuth,  equal  parts,  melt 283 

Tin  3 parts,  bismuth  5,  and  lead  2,  melt...  212 

Alcohol,  boils 174 

Ether,  boils 98 

Human  blood  (heat  of) 98 

Strong  wines,  freeze 20 

Brandy,  freezes 7 

Mercury,  melts - -89 


HEDDLES. 


15 


Wedge-wood’s  zero  is  10‘7'7°  of  Fahrenheit,  and  each  of  his  degrees  is  equal  to  130°  of  Fahrenheit. 

Expansion  of  Solids. 

At  212°,  the  length  of  the  bar  at  32°  considered  as  1-0000000. 


-001495€ 

-0017450 

-0019062 

-0020100 

-0004928 

-0028436 

-0029420 

To  find  the  expansion  in  surface  or  in  volume,  it  must  be  remembered  that  each  dimension  of  a solid 
experiences  a similar  proportional  expansion. 


Glass 

Platina  

-0009542 

-0011112 

Gold 

Copper.. 

-0011899 

Silver 

Marble 

-0011041 

Fire  oriek 

Forged  iron 

-0O12575 

Lea  1 .... 

Granite  

Zim  

Table  of  the  Expansion  of  Air  by  Heat. — By  Mr.  Dalton. 


Fahrenheit. 

Fahrenheit. 

Fahrenheit. 

32° 1000 

33  1002 

34  1004 

85  1107 

40  1021 

45  1032 

50° 1043 

55  1055 

60  1066 

65  1077 

TO  1089 

75  1099 

80° 1110 

85  1121 

90  1132 

100  1152 

200  1354 

212  1376 

Melting  Point  of  Alloys. 


Lead  2 parts,  tin  3 parts,  bismuth  5 parts,  melts  at  212° 

“ 1 “ “4  “ “ 5 “ melts  at  246 

“ 1 “ “1  “ melts  at 286 

“ 2 “ “1  “ melts  at 336 

“ 2 “ “ 3 “ melts  at  334 

“ 8 “ “1  “ melts  at 392 

“ 2 “ “1  “ common  solder,  melts  at 475 

“ 1 “ “2  “ soft  solder,  melts  at 360 


Boiling  points. — The  boiling  point  of  water,  from  27  to  31  inches  of  the  mercurial  column,  varies 
1-65°  for  every  inch,  being  at  30  inches  212°  ; and  on  this  variation  is  founded  the  apparatus  for  deter- 
mining altitudes. 

, Comparative  Heat  from  various  Fuels. 

3 lb.  of  tolerably  good  coal  will  raise  the  temperature  of  60  lbs.  of  water  from  32°  to  212°. 

1 lb.  of  kiln  or  perfectly  dried  wood  will  effect  the  same  on  35  lbs. 

1 lb.  of  wood  simply  dried  in  the  air  “ “ 26  lbs. 

1 lb.  charcoal  “ “ 79  lbs. 

Turf  of  good  quality  yields  as  much  heat  for  equal  weights  as  wood,  and  the  heat  it  gives  out  by 
radiation  whilst  burning  has  been  considered  even  greater  than  that  of  wood. 

For  the  various  methods  of  applying  heat  to  the  warming  of  buildings,  see  article  Warming. 

HEDDLES,  Machine  for  making  Weavers'.  This  machine  is  the  invention  of  Mr.  Kassimir  Yogel, 
of  Lowell,  Massachusetts. 

The  object  of  the  machine  is  to  make  weavers’  heddles  from  the  thread,  casting  the  loop  by  braiding 
instead  of  knotting,  and  performing  triple  the  amount  of  work,  and  better  than  can  be  done  by  hand. 
A patent  is  also  secured  for  the  peculiar  eye  of  the  heddle,  so  that  both  machine  and  its  results  are 
protected. 

Description. — Fig.  2251  is  a perspective  view,  and  shows  gangs  of  different  heddles  winding  on  the 
Deams.  A A is  the  iron  framing.  B are  the  driving  and  slack  pulleys.  C is  the  lever  to  geer  and  un- 
geer.  E E are  the  bobbins,  with  the  thread  to  make  the  heddles.  There  is  a small  shaft  under  the  bed 
of  E,  which,  by  small  cog-wheels  on  the  same,  operate  and  revolve  the  bobbins  by  geering  into  F.  1 1 
are  the  heddles  after  the  eye  is  formed,  winding  up  on  the  beams  L L.  The  gang  of  wheels  at  the  left 
are  for  the  purpose  of  connecting  the  shafts  of  the  beams  to  be  driven  by  the  main  shaft  below.  The 
number  of  eyes  to  the  foot  in  the  heddles  can  be  increased  or  diminished  by  the  geering  of  these  small 
wheels.  K is  a small  bearing  for  the  shaft  of  L,  and  J is  the  shaft  with  a screw  cut  on  part  of  it.  This 
is  for  winding  the  heddle  gradually  along  the  beam,  and  as  K is  a grooved  and  wormed  faced  pulley- 
driven  slowly  by  the  small  gang  of  wheels  at  the  right,  the  shaft  J is  wormed  slowly  through  its  bear- 
ings, carrying  the  beam  to  let  the  heddles  wind  one  after  another  on  the  same.  The  heddles  are  formed 
of  a double  cord,  which  is  twisted  by  the  bobbins  revolving,  and  the  eyes  or  loops  are  formed  by  the 
bobbins  being  interlocked,  braiding  the  two  strands  at  the  two  points  which  form  the  eye  of  the  heddles. 
The  section  views  will  explain  the  operations  better  in  detail. 

As  the  same  letters  indicate  like  parts  on  all  the  following  engravings,  we  shall  describe  them  col 
lectively.  Fig.  2252  is  a side  elevation.  Fig.  2253  is  a top  view  of  the  revolving  tables  and  spindles. 
Fig.  2254  is  an  end  elevation.  Fig.  2255  is  a view  of  the  under  side  of  the  machine,  showing  the  geer- 
ing by  which  the  tables  that  carry  the  spindles  are  made  to  revolve. 


14 


HEDDLES. 


A is  the  heddle-beam.  B B BB  are  revolving  spool-frames  or  tables.  C represents  the  spool-spin- 
dles. a are  slots  in  the  spool-tables.  Each  table  has  six  slots  or  spindle  recesses,  but  only  three  are 
occupied  at  once  with  the  spindles.  As  the  tables  revolve,  three  slots  are  occupied  with  spindles  and 
three  are  empty  alternately,  and  an  occupied  slot  in  one  is  brought  opposite  to  an  empty  recess  in  ita 

2251. 


fellow-table,  as  seen  in  Fig.  2253.  The  tables  BB  constitute  one  pair,  and  the  tables  B 2,  B 3,  another, 
forming  two  distinct  harness,  one  on  each  side  on  two  beams,  but  driven  by  the  same  geering.  The 
yarn  is  put  on  the  spindles  0,  and  passes  through  a hole  in  the  top  of  the  flyers  D,  or  over  a depression, 
tig.  2252,  to  hold  it  in  its  place,  and  then  passes  under  c,  a recurved  wire,  that  has  a perforated  weight 


j a at  each  end.  The  flyers  pass  through  these  holes,  and  the  legs  serve  as  guides  to  the  weights. 
Phis  is  to  take  up  the  slack  of  the  yarn.  The  spindles  have  each  a groove  in  their  lower  parts,  adapted 
to  slide  into  the  recesses  of  the  tables  when  the  recesses  coincide.  The  platform  E E has  circular 
avities  for  the  lower  ends  of  the  spindles.  F F,  Fig.  2252,  are  fast  and  loose  pulleys  to  drive  the 


HEDDLES. 


1 


shaft  G.  A bevel-wheel  H,  on  G,  gives  motion  to  the  revolving  spool-tables  by  toothed  wheels,  as  seen 
at  Fig.  2255.  The  bevel-wheel  I,  Fig.  2252,  gives  motion  to  the  heddle-beams  by  geering  into  J,  on 
the  shaft  K.  This  shaft  carries  a worm-wheel,  which  geers  into  M to  drive  A.  N is  an  eccentric  on  K 


to  vibrate  g,  a shipper,  which  shifts  the  spindles  from  one  table  to  another;  the  opposite  ends  of  g 
eperate  on  two  pairs  of  tables.  A connecting-rod  with  N vibrates  the  shippers.  N is  connected  with  K, 
and  turn9  with  it  by  clutch-pins,  and  when  these  are  not  engaged  the  shafts  turn  without  1ST.  i i,  Fig. 
2254,  is  a pin  that  passes  through  If,  projecting  out  above  and  below,  nearly  in  contact  with  K.  There 


are  two  clutch  pins  on  K,  either  of  which  may  be  brought  in  contact  with  i,  as  the  eccentric- wheel  is 
made  to  slide  up  and  down  on  the  shaft.  O,  Figs.  2252  and  2254,  is  a forked  lever  with  its  fulcrum  at  e 
Its  fork  ends  m m embrace  1ST,  the  eccentric,  and  raise  and  lower  it  at  proper  times,  n n is  a spiral 
spring  attached  to  the  forked  lever,  serving  to  draw  it  inwards  to  depress  the  eccentric  and  make  it 


HELIOTROPE. 


16 


clutch  with  the  lever  clutch-pin.  On  the  wheel  M are  cams  or  lifting  pieces  jj p,  which,  when  they 
come  in  contact  with  the  end  of  0,  force  it  out  and  raise  hi,  the  eccentric,  so  as  to  en,ra<re  with  the 
upper  clutch-pin  at  the  required  time,  as  will  be  understood  by  Fig.  2254.  The  axis  of  A°is°P,  a screw 
Tig.  2252,  tapped  into  the  frame  of  the  machine  and  moves  A endwise  as  it  revolves,  to  wind  th* 
heddles,  as  they  are  made  spirally  on  the  beams,  q is  the  smooth  axis  of  A,  on  which  the  beam  slides, 
moved  by  the  screw  on  the  guide-rods  rr.  Q Q are  rods  that  may  be  inserted  in  grooves  in  A.  The 
semi-diameter  of  A must  be  of  the  length  of  the  heddles.  After  the  number  of  heddles  for  a harness 
have  been  made,  grooved  pieces  may  be  slipped  over  Q and  glued  upon  them  to  embrace  the  twisted 
strands,  or  any  other  mode  may  be  adopted.  The  shipper  connecting-rod  h,  (which  looks  like  an  «,) 
Figs.  2252  and  2253,  has  a hinge-joint  t,  to  allow  it  to  be  lifted  from  the  shipper  g.  The  small  bevel- 
wheel  J,  on  the  shaft  K,  is  one-third  of  the  diameter  of  the  driving-wheels,  when  there  are  three  spindles 
on  the  table,  and  therefore  makes  the  changes  of  the  spindles  in  the  recesses  in  one  revolution  of  the 
revolving  spool-tables.  If  there  were  four  spindles  in  the  table,  the  wheel  J would  be  one-fourth  the 
diameter  of  the  driving-wheel,  drc. 


To  explain  its  operation,  Fig.  2251  exhibits  a different  arrangement  of  mechanical  parts  from  the  sec- 
tion views,  but  they  are  just  the  mechanical  equivalents  to  accomplish  the  same  thing.  Heddle  or 
harness  making  is  the  formation -of  eyes  by  two  cords  being  knotted  together.  These  eyes  must  be 
formed  at  regular  distances  on  the  harness.  This  machine  forms  two  cords  by  B B,  revolving  and  twist- 
ing the  yarn  on  the  three  spindles,  one  by  each  table  revolving,  the  cord  winding  at  the  same  time  as  it 
is  twisted  on  the  beam  A.  Row  to  form  four  eyes  on  the  heddles  every  revolution  of  the  beam, 
look  at  Fig.  2253.  If  the  strands  that  make  the  two  cords  were  interlocked  at  certain  periods,  eight 
times  during  the  revolution  of  A,  that  four  eyes  would  be  formed  by  the  strands  of  the  two  cords  being 
thus  at  certain  points  braided  into  one  another.  This  is  the  way  this  machine  does  its  work,  and  this 
can  be  done  by  the  forked  lever  in  Fig.  2254  shifting  the  shipper,  or  by  cams  on  the  inside  of  the  upper 
geer-wheel  of  Fig.  2251.  To  make  the  spindles  in  c interlock  to  braid  the  eyes.  The  cams  or  clutch 
operate  the  shipper  g,  so  that  instead  of  vibrating  from  side  to  side,  as  now  seen  in  Fig.  2253,  touching 
the  spindles  outside,  it  is  (the  shipper)  stopped  by  the  resting  of  the  eccentric  one-sixth  of  the  revolu- 
tion of  the  tables,  and  then  it  will  be  easily  perceived  that  the  shipper  will  take  into  the  inside  of  the 
spindle  e and  throw  it  into  the  empty  recess  a of  the  other  table,  which  coincides,  thus  interlocking  the 
threads  and  braiding  the  two  cords  together  into  one,  forming  an  eye  of  the  heddle  by  braiding  instead 
of  knotting.  It  will  be  observed,  too,  that  the  clutch  can  be  changed  by  cams,  to  operate  the  shipper, 
to  make  as  large  or  as  many  eyes  in  a foot  as  may  be  desired ; but  the  changing  or  passing  of  the 
spindles  from  one  table  to  another  must  be  performed  by  the  shipper  twice  for  one  eye,  according  to 
the  length  of  the  eye,  and  they  are  not  shifted  again  until  A has  revolved  the  distance  wanted  to  form 
the  base  of  a new  eye  for  the  harness. 

HELIOTROPE  Reflecting  Lantern,  used  by  Major  J.  D.  Graham  as  meridian  marks  for  great  distances, 
in  1841,  while  tracing  the  due  north  line  from  the  monument  at  the  source  of  the  river  St.  Croix. 

The  lantern  was  constructed  by  Messrs.  Hemy  N.  Hooper  & Co.  of  Boston,  under  Maj.  G.’s  directions. 
It  was  similar  in  form  to  the  Parabolic  Reflector  Lantern,  sometimes  used  in  light-houses,  but  much 
smaller,  so  as  to  be  portable. 

The  burner  was  of  the  argand  character,  with  a cylindrical  wick,  whose  transverse  section  was  half 
an  inch  in  diameter,  supplied  with  oil  in  the  ordinary  manner.  This  was  placed  in  the  focus  of  a para- 
bolic reflector,  or  paraboloid,  of  sheet-copper,  lined  inside  with  silver  about  l-20th  of  an  inch  in  thick- 
ness, polished  very  smooth  and  bright.  The  dimensions  were  as  follows  : 

Inches, 


Diameter  of  the  base  of  frustrum  of  reflector 16- 

Distance  of  vertex  from  base S'15 

Distance  of  focus  from  vertex 2’25 

Diameter  of  cylindrical  burner '60 

Diameter  of  a larger  burner  which  was  never  used,  but  which,  by  an  adapting  piece, 

could  be  easily  substituted 1 26 


HELIX. 


17 


The  instrument  answered  the  purpose  for  which  it  was  intended  admirably  well,  and  was  of  great 
use  in  tracing  the  due  north  line.  While  it  occupied  the  station  at  Park’s  Hill,  15  feet  above  the  sur- 
face  of  the  ground,  or  828  feet  above  the  sea,  in  the  latter  part  of  September  and  early  part  of  October, 
1841,  the  light  from  it  was  distinctly  seen  with  the  naked  eye  at  night,  when  the  weather  was  clear 
from  Blue  Hill,  whose  summit,  where  crossed  by  the  meridian  line,  is  1071  feet  above  the  sea,  the 
intervening  country  averaging  about  500  feet  above  the  sea,  and  the  stations  being  36  miles  apart.  The 
light  appeared  to  the  naked  eye,  at  that  distance,  as  bright,  and  of  about  the  same  magnitude,  as  the 
planet  Venus. 

The  wick  employed  by  Major  G.  was  considerably  smaller  than  that  usually  made,  even  for  parlor 
lamps ; and  to  this  cause  is  attributed,  in  a great  measure,  the  perfection  with  which  the  parallel  rays 
were  transmitted  from  the  reflecting  parabolic  surface,  so  as  to  make  them  visible  at  so  great  a distance. 
Though  a greater  quantity  of  light  is  generated  by  a larger  wick,  the  portion  of  rays  reflected  in  a 
direction  parallel  to  the  axis,  and  which  alone  come  to  the  eye,  is  the  smaller  as  the  flame  transcends 
the  focal  limit.  The  size  of  wick  most  advantageous  for  use  may  easily  be  determined  by  experiment. 
The  smaller  is  its  transvere  section,  provided  it  is  only  large  enough  to  escape  being  choked  up  by 
the  charred  particles,  even  one-third,  or  perhaps  less,  the  further  the  light  would  he  visible. 

The  heliotrope,  which  is  employed  in  the  day  time,  was  made  by  order  of  Mr.  Hassler,  at  the  instru- 
ment shop  of  the  coast  survey  office.  It  was  a rectangular  parallelogram  of  good  German  plate-glass, 
1 4-5ths  by  1 l-5th  inch  in  size,  giving  an  area  of  reflecting  surface  of  2 square  inches.  This  also 
was  seen  at  the  distance  of  30  miles. 

HELIX.  A spiral  curve.  The  cy- 
lindrical or  screw  helix  is  the  curve 
described  upon  the  surface  of  a cy- 
linder by  a point  revolving  round  it, 
and  at  the  same  time  moving  par- 
allel to  its  axis  by  a certain  invaria- 
ble distance  during  each  revolution. 

Figs.  2256  and  2257,  to  con- 
struct the  helical  curve  described 
by  the  point  A upon  a cylinder  pro- 
jected horizontally  in  the  circle  A' 

C'  F',  the  pitch  being  represented 
by  the  line  A'  A3.  Divide  the  pitch 
A'  A3  into  any  number  of  equal 
parts,  say  eight ; and  through  each 
point  of  division,  1,  2,  3,  &c.,  draw 
straight  lines  parallel  to  the  ground 
line.  Then  divide  the  circumfe- 
rence A'  C'  F'  into  the  same  num- 
ber of  parts ; the  points  of  division 
B',  C',  E',  F',  &c.,  will  be  the  hor- 
izontal projections  of  the  different 
positions  of  the  given  point  during 
its  motion  round  the  cylinder. 

Thus,  when  the  point  is  at  B'  in 
the  plan,  its  vertical  projection  will 
be  the  point  of  intersection  B of  the 
perpendicular  drawn  through  B’ 
and  the  horizontal  drawn  through 
the  first  point  of  division.  Also 
when  the  point  arrives  at  C'  in  the 
plan,  its  vertical  projection  is  the 
point  C,  where  the  perpendicular 
drawn  from  C'  cuts  the  horizontal 
passing  through  the  second  point  of 
division,  and  so  on  for  all  the  re- 
maining points.  The  curve  ABC 
F A3  drawn  through  all  the  points 
thus  obtained,  is  the  helix  required. 

A helical  surface  is  generated  by 
the  revolution  of  a straight  line 
round  the  axis  of  a cylinder;  its 
outer  end  moving  in  a helix,  and 
the  fine  itself  forming  with  the  axis 
a constant  and  invariable  angle. 

The  conical  helix  differs  from  the  cylindrical  one  in  that  it  is  described  on  the  surface  of  a cone  in- 
stead of  on  that  of  a cylinder ; but  the  construction  differs  hut  slightly  from  the  one  described.  By 
following  out  the  same  principles,  helices  may  be  represented  as  lying  upon  spheres  or  any  other  surfaces 
of  revolution.  In  the  arts  are  to  he  found  numerous  practical  applications  of  the  helical  curve,  as  wood 
and  machine  screws,  geers  and  staircases. 

HEPTAGON.  A figure  having  seven  equal  angles  and  sides. 

Vol.  II.— 2 


18 


HORN. 


H F.  X A ED  RON,  the  Cube.  One  of  the  five  regular  or  Platonic  bodies,  and  so  called  from  its  having 
six  faces.  The  square  of  the  side  or  edge  of  a hexaedron  is  one-third  of  the  square  of  the  diameter  of 
the  circumscribing  sphere ; and  hence  the  diameter  of  a sphere  is  to  the  side  of  its  inscribed  hexaedron 
as  V 3 to  1 . 

HEXAGON.  A figure  of  six  sides  and  angles.  Angle  at  the  centre  = 60° ; angle  at  the  circum- 
ference = 120° ; area  to  side,  1 = 2-5980762  ; area  to  any  side,  (S)  = 32  x 2-5980762. 

HIGH-PRESSURE  ENGINE.  The  simplest  form  of  the  steam  engine  is  the  non-condensing,  or 
high-pressure  engine.  In  this  engine  the  condensing  apparatus  is  dispensed  with,  and  steam  being  ad- 
mitted into  the  cylinder,  at  a high  temperature,  and  consequently  high  pressure,  and  having  acted  on 
the  piston,  is  allowed  to  escape  into  the  open  air.  A part  of  the  force  of  the  steam  is  of  course  ex- 
pended in  overcoming  the  pressure  of  the  atmosphere,  and  it  is  only  that  portion  of  the  steam’s  elastic 
force  that  exceeds  15  pounds  to  the  square  inch  that  is  effective  in  moving  the  engine.  The  surplus  pres- 
sure is  usually  from  30  to  40  pounds  on  the  circular  inch.  See  Stationary  Engines,  and  Engines 
Varieties  of. 

HINGE,  Taft’s  double-jointed  hinge  and  door-spring.  Figs.  2260  and  2261.  This  hinge  is  so  constructed 
that  it  admits  of  the  opening  of  the  door,  or  gate,  in  either  direction,  and  in  combination  with  it  is  a spring 
connected  by  a chain  with  the  casing,  whereby  the  door  is  held  close  to  it  as  well  as  made  to  close 
itself.  Each  hinge  employed  in  this  improvement  may  consist  of  four  or  more  pieces,  two  of  which  are 


side  plates  with  knuckles  attached  thereto.  The  connecting  plates  with  their  knuckles  are  connected 
by  pivots  to  those  of  the  plates,  and  each  connects  the  plate  to  the  other,  so  that  when  the  hinge  is 
opened  in  the  opposite  direction  the  connecting  plate  changes  sides  and  folds  upon  the  plate,  so  that  the 
hinge  presents  the  same  appearance  in  either  position. 

HINGES.  The  joints  on  which  doors,  gates,  &c.,  turn. 

HIP.  The  external  angle  formed  by  the  meeting  of  the  sloping  sides  of  roofs  which  have  their  'wall- 
plates  running  in  different  directions. 

HORN.  See  Animal  Matter  used  in  the  Arts. 

HORN,  machine  for  pressing.  Horn,  tortoise-shell,  and  many  other  animal  substances,  are  capable 
of  being  softened  by  heat  and  moulded  by  pressure  into  any  shape  and  with  any  design  in  the  sharpest 


*nd  most  delicate  relief.  A screw  press  has  usually  been  employed  for  this  purpose,  but  the  one  rep- 
res  .nted  bv  Fig.  2262,  which  is  a section  through  its  centre,  is  far  superior. 


HORSE. 


10 


A A is  a box  of  cast-iron.  B is  a copper  to  contain  the  hot  water,  and  M is  a grata  for  the  fire  to  heat 
the  same.  0 is  the  smoke-pipe.  F F G-  is  the  press,  made  of  strong  cast-iron,  and  capable  of  being 
drawn  up  and  let  down  in  the  water  at  pleasure,  by  means  of  racks  D D,  at  each  side,  actuated  by 
pinions  J J.  The  axles  of  these  pinions  cross  the  machine  and  have  each  a wheel  at  the  end,  moved  by 
two  arms,  or  screws  cut  upon  the  axis  and  turned  by  the  handle  H.  The  press  is  guided  in  the  ascent  or 
descent  by  grooves  in  the  side  of  the  boiler.  When  raised  up  out  of  the  water,  the  moulds,  with  the  horn 
or  tortoise-shell  between  them,  are  put  beneath  the  presser,  and  a severe  pressure  is  produced  by  turn- 
ing the  wheel  K.  This  wheel  has  an  endless  screw  R upon  its  axis,  which  works  the  teeth  of  a large 
wheel  L,  fixed  on  the  top  of  the  screw  P.  The  screw  is  received  into  an  interior  screw  formed  within 
the  box  or  presser  I,  which  is  guided  and  prevented  turning  round  by  the  cross-bar  E,  through  which 
the  presser  is  fitted;  by  this  means,  when  the  screw  P is  turned  round  by  the  wheel  L and  endless 
screw,  the  horn  or  tortoise-shell  is  pressed  between  the  moulds ; the  press  is  then  lowered  again  into 
the  water  of  the  boiler,  in  order  to  be  still  further  softened  by  the  boiling ; but  when  the  press  is  down 
in  the  boiler,  the  screw  can  be  screwed  tighter  by  turning  the  wheel  K until  the  desired  impression  is 
obtained.  By  turning  the  handle  H,  the  press  is  then  raised  up  out  of  the  boiler,  and  by  turning  back 
tire  wheel  K the  pressure  is  released  and  the  moulds  can  be  removed. 

HORSE.  The  power  of  a horse  when  applied  to- draw  loads,  as  well  as  when  made  the  standard  of 
comparison  for  determining  the  value  of  other  powers,  has  been  variously  stated. 

The  relative  strength  of  men  and  horses  depends,  of  course,  upon  the  manner  in  which  their  strength 
is  applied.  Thus,  the  worst  way  of  applying  the  strength  of  a horse  is  to  make  him  carry  a weight  up 
a steep  hill,  while  the  organization  of  the  man  fits  him  very  well  for  that  kind  of  labor.  And  three 
men,  climbing  up  a steep  hill,  with  each  100  lbs.  on  his  shoulders,  will  proceed  faster  than  most  horses 
with  300  lbs. 

It  is  highly  useful  to  load  the  back  of  a drawing  horse  to  a certain  extent ; though  this,  on  a slight 
consideration,  might  be  thought  to  augment  unnecessarily  the  fatigue  of  the  animal:  but  it  must 
be  recollected  that  the  mass  with  which  the  horse  is  charged  vertically  is  added  in  part  to  the  effort 
Which  he  makes  in  the  direction  of  traction,  and  thus  dispenses  with  the  necessity  of  his  inclining  so 
much  forward  as  he  must  otherwise  do : and  may,  therefore,  under  this  point  of  view,  relieve  the 
draught  more  than  to  compensate  for  the  additional  fatigue  occasioned  by  the  vertical  pressure.  Carmen, 
and  wagoners  in  general,  are  well  aware  of  this,  and  are  commonly  very  careful  to  dispose  of  the  load  in 
such  a manner  that  the  shafts  shall  throw  a due  proportion  of  the  weight  on  the  back  of  the  shaft  horse. 

The  best  disposition  of  the  traces  during  the  time  a horse  is  drawing  is  to  be  perpendicular  to  the 
position  of  the  collar  upon  his  breast  and  shoulders : when  the  horse  stands  at  ease,  this  position  of  the 
traces  is  rather  inclined  upwards  from  the  direction  of  the  road ; but  when  he  leans  forward  to  draw 
the  load,  the  traces  should  then  become  nearly  parallel  to  the  plane  over  which  the  carriage  is  to  be 
drawn ; or,  if  he  be  employed  in  drawing  a sledge,  or  any  thing  without  wheels,  the.  inclination  of  the 
traces  to  the  road  should  be  about  18£°,  when  the  friction  is  one-third  of  the  pressure. 

When  a horse  is  made  to  move  in  a circular  path,  as  is  often  practised  in  mills  and  other  machines 
moved  by  horses,  it  will  be  necessary  to  give  the  circles  which  the  animal  has  to  walk  round  the 
greatest  diameter  that  will  comport  with  the  local  and  other  conditions  to  which  the  motion  must  be 
subjected.  It  is  obvious,  indeed,  that,  since  a rectilinear  motion  is  the  most  easy  for  the  horse,  the  less 
the  line  in  which  he  moves  is  curved,  with  the  greater  facility  he  will  walk  over  it,  and  the  less  he  need 
recline  from  a vertical  position : and  besides  this,  with  equal  velocity  the  centrifugal  force  will  be  less 
in  the  greatest  circle,  which  will  proportionally  diminish  the  friction  of  the  cylindrical  part  of  the  trun- 
nions, and  the  labor  of  moving  the  machine.  And,  further,  the  greater  the  diameter  of  the  horse-walk, 
the  nearer  the  chord  of  the  circle  in  which  the  horse  draws  is  to  coincidence  with  the  tangent,  which  is 
the  most  advantageous  position  of  the  line  of  traction.  On  these  accounts  it  is  that,  although  a horse 
may  draw  in  a circular  walk  of  18  feet  diameter,  yet  in  general  it  is  advisable  that  the  diameter  of  such 
a walk  should  not  be  less  than  25  or  30  feet ; and  in  many  instances  40  feet  would  be  preferable  to  either. 

It  has  been  stated  by  Desaguliers  and  some  others,  that  a horse  employed  daily  in  drawing  nearly 
horizontally  can  move,  during  eight  hours  in  the  day,  about  200  lbs.  at  the  rate  of  2£  miles  per  hour,  or 
3f  feet  per  second.  If  the  weight  be  augmented  to  about  240  or  250  lbs.,  the  horse  cannot  work  more 
than  six  hours  a day,  and  that  with  a less  velocity.  And,  in  both  cases,  if  he  carry  some  weight,  he 
will  draw  better  than  if  he  carried  none.  M.  Sauveur  estimates  the  mean  effort  of  a horse  at  175 
French,  or  189  avoird.  pounds,  with  a velocity  of  rather  more  than  three  feet  per  second.  But  all  these 
are  probably  too  high  to  be  continued  for  eight  hours,  day  after  day.  In  another  place  Desaguliers 
states  the  mean  work  of  a horse  as  equivalent  to  the  raising  a hogshead  full  of  water  (or  550  lbs.)  50 
feet  high  in  a minute.  But  Mr.  Smeaton,  to  whose  authority  much  is  due,  asserts,  from  a number  of 
experiments,  that  the  greatest  effect  is  the  raising  550  lbs.  forty  feet  high  in  a minute.  And,  from 
some  experiments  made  by  the  Society  for  the  Encouragement  of  Arts,  it  was  concluded,  that  a horse 
moving  at  the  rate  of  three  miles  an  hour  can  exert  a force  of  80  lbs.  The  proper  estimate  would  be 
that  which  measures  the  weight  that  a horse  would  draw  up  out  of  a well ; the  animal  acting  by  a hor- 
izontal line  of  traction  turned  into  the  vertical  direction  by  a simple  pulley,  or  roller,  whose  friction 
ehould  be  reduced  as  much  as  possible. 

Tredgold  has  directed  his  attention  to  the  subject  of  “ horse-power .”  His  expression  for  (he 


power  of  a horse  is  250  v 


and 


250  dv 


(-0 


1 -j-  n 


for  the  day's  work  in  lbs.  raised  oue 


mile;  d being  the  hours  which  the  horse  works  in  a day,  and  the  weight  of  the  carriage  to  that  of  the 


load  as  n . 1 


„ , ■ 14‘7 

He  also  gives  —f~r, 

V “ 


for  the  greatest  speed  in  miles  per  hour,  when  the  horse  is  unloaded. 


20 


HORSE-POWER. 


He  gives  the  following  table  of  the  comparison  of  duration  of  a horse’s  daily  labor  and  maximuir 
velocity  unloaded : — 


Duration  of  labor.  Maximum  velocity  unloaded 

Hours.  in  miles  per  hour. 

1 14*7 

2 10-4 

Duration  of  labor.  Maximum  velocity  unloaded 

Hours.  in  miles  per  hour. 

6 G* 

3 8 5 

8 5-2 

4 73 

5 6-6 

9 4-9 

10  40 

Taking  the  hours  of  labor  at  6 per  diem,  the  utmost  he  would  recommend,  the  maximum  of  useful 
effect  he  assigns  at  125  lbs.,  moving  at  the  rate  of  three  miles  per  hour;  and  regarding  the  expense  of 
carriage  in  that  case  as  unity,  then, 


Miles  per 

Proportional 

Moving  force 

hour. 

expense. 

or  traction. 

o 

1-125  

166  lbs. 

3 

1*  

125  “ 

34  

1 0285  

104  “ 

4 

1-125  

83 

44  

1-333  

024  “ 

5”  

1-8  

41  * “ 



9. 

364  “ 

That  is,  the  expense  of  carrying  goods  at  3 miles  per  hour  being  1,  the  expense  at  4-J  miles  per  hour 
will  be  1 ; the  expense  being  doubled  when  the  speed  is  5J  miles  per  hour. 

Various  estimates  have  been  made  of  a horse’s  power  by  Desaguliers,  Smeaton,  and  others  ; but  the 
estimate  now  generally  adopted  as  a standard  for  measuring  the  power  of  steam-engines,  is  that  of  Mr. 
Watt,  whose  computation  is  about  the  average  of  those  given  by  the  other  writers.  The  measure  of  a 
horse’s  power,  according  to  Mr.  Watt,  is,  that  he  can  raise  a weight  of  33,000  pounds  to  the  height  of 
one  foot  in  a minute. 

Horse-power , as  the  measure  of  the  force  of  steam-engines. — It  is  by  this  nominal  power  that  engines 
are  usually  bought  and  sold  and  always  spoken  of,  unless  when  the  contrary  is  expressly  stated. 

The  following  is  Boulton  and  Watt’s  rule  for  determining  the  nominal  horses’  power. 

Let  D = the  diameter  of  the  cylinder  in  inches. 

V = half  the  velocity  of  the  piston  in  feet  per  minute. 


Then 


(D"  — 4 D)  V 
2650 


the  number  of  nominal  horses’  power. 


But  in  order  to  determine  V before  the  engine  has  been  made,  Boulton  and  Watt  fixed  upon  an  em- 
pirical velocity  for  each  different  length  of  stroke.  The  several  velocities  are  as  follow : 


Stroke, 
ft.  in. 
2 0 
2 6 
3 0 

3 6 


Velocity. 

ft. 

160 

170 

180 

190 


Stroke, 
ft.  in. 
4 0 

4 6 

5 0 


Velocity. 

ft. 

200 

210 

220 


And  so  on,  with  10  feet  of  additional  velocity  for  every  6 inches  of  additional  stroke.  The  original 
engines  of  the  Thames  and  Shannon,  constructed  by  Boulton  and  Watt,  were  rated  at  80  horse-power, 
the  cylinders  being  411  inches  in  diameter,  and  the  length  of  stroke  4 feet  6 inches,  (47’5)2 — 4 (47'5)  =: 
2066-25  X 105  = 217930  2650  = 83  horse-power  nearly,  instead  of  80.  Land  engines  of  43J  inches 

diameter  of  cylinder  and  8 feet  stroke,  making  16  double  strokes  in  a minute,  were  rated  by  Boulton 
and  Watt  at  80  horse-power.  The  average  effective  pressure  on  the  piston  is  rated  at  barely  7 lbs.  per 
square  inch,  and  the  power  may  be  thus  computed,  (43-R2  X '7854  = 1486'2  X by  7 and  266,  and  — by 
33,000  = about  80  horse-power.  In  marine  engines  a greater  area  of  piston  is  allowed  to  represent  a 
horse-power  than  in  land  engines,  because  the  motion  of  the  piston  is  supposed  to  be  slower,  but  the 
effective  force  is  calculated  a little  higher,  or  at  7’3  per  square  inch. 

HORSE-POWER,  Bogardus’s.  This  improvement  in  the  horse-power  for  driving  machinery  is  based 
on  the  principle  of  the  well-known  sun  and  planet  motion,  and  consists  of  a base-frame  having  cogs  in 
the  inner  periphery  of  the  rim  into  which  mash  the  cogs  of  a pinion  on  the  lower  end  of  the  arbor  of  the 
planet-wheel,  the  cogs  of  which  drive  a pinion  on  a central  shaft  that  carries  the  driving-pulley,  the  arbor 
of  the  planet-wheel  being  adapted  to  turn  in  a sleeve,  in  a travelling  wing  to  which  the  horse-beam  is 
secured ; and  the  said  wing  having  another  and  parallel  sleeve  that  turns  on  a central  hollow  standard 
of  the  frame  through  which  the  shaft  of  the  central  pinion  arid  driving-pulley  passes,  and  in  which 
it  turns. 

The  base-frame  is  cast  in  one  piece,  consisting  of  the  central  hub.  and  the  outer  ring  connected  by 
radial  arms,  and  standing  on  legs.  The  central  hub  is  cast  with  a hollow  standard  properly  turned  with 
a slight  taper,  to  which  is  fitted  a sleeve  that  turns  thereon  freely  but  accurately,  and  resting  on  the 
upper  surface  of  the  hub ; and  likewise  with  this  sleeve,  and  making  part  thereof,  is  cast  a wing,  to 
which  is  secured  by  bolts  the  liorse-beam  or  lever,  by  which  the  whole  is  operated.  The  other  end  ot 
the  wing  is  also  provided  with  another  sleeve  cast  therewith,  and  parallel  to  the  other,  to  which  is  fitted 
accurately  (but  yet  to  admit  of  turning  freely)  the  arbor  of  the  planet-wheel  and  planet-wheel  pinion, 
the  former  being  at  the  top  and  the  latter  at  the  bottom.  One  of  these,  either  the  wheel  or  the  pinion, 
can  be  permanently  attached  to  the  arbor,  and  the  other  keyed  on  after  it  has  been  inserted  in  the 


HORSE-POWER. 


21 


sleeve.  The  cogs  of  the  pinion  of  the  planet-wheel  take  into  the  cogs  formed  in  the  inner  periphery  ol 
the  rim  of  the  base-frame,  and  which  may  be  called  the  master-wheel ; and  the  cogs  of  the  planet-wheel 
take  into  the  cogs  of  and  drive  the  central  pinion  on  the  upper  end  of  a vertical  shaft  that  passes  through 
and  turns  freely  but  accurately  in  the  central  hollow  standard,  which  is  adapted  to  it,  the  driving-pulley 
being  keyed  on  the  lower  end  and  below  the  hub. 

A band  from  the  driving-pulley  can  be  carried  under  the  frame  and  between  the  legs,  to  any.  place 
required  in  the  usual  manner  to  drive  any  piece  of  machinery  ; but  if  desired,  the  driving-pulley  can  be 
attached  to  the  central  shaft  above  the  central  pinion,  Fig.  2264.  The  arbor  of  the  planet-wheel  is 
oiled  through  a hole  in  the  wheel  which  delivers  it  at  the  junction  of  the  sleeve  and  arbor;  and  in  like 
manner  the  central  shaft  and  the  sleeve  that  turns  on  the  central  standard  are  oiled  by  pouring  the  oil 
through  a hole  in  the  central  pinion,  which  delivers  it  on  the  upper  end  of  the  hollow  standard,  and 
which  is  grooved  to  direct  the  oil  to  its  inner  and  outer  periphery. 


The  whole  apparatus  is  made  light  and  portable,  rests  on  the  case-frame,  and  turns  on  the  central 
standard,  which  makes  part  of  the  base-frame,  without  supports  or  bearings  at  the  top.  The  whole  can 
be  taken  apart  for  transportation,  and  can  be  again  put  together  with  ease.  The  whole  strain  comes 
on  and  is  supported  by  the  hollow  standard,  which  being  cast  with  the  base-frame  will  resist  any  strain 
that  can  be  applied  to  it  by  the  horses  employed  to  drive  the  machine.  The  sleeves  of  the  wing  and 
the  inside  of  the  central  standard  are  or  may  be  laid  with  soft  metal. 


Arranged  to  carry  a shaft  under  the  foot-path,  or  an  upright  shaft  to  the  floor  above. 


In  some  ferry-boats  and  machines,  horses  are  placed  on  a revolving  platform,  which  passes  backward 
under  the  feet  whenever  the  horse  exerts  his  strength  in  drawing  against  a fixed  resistance,  so  that  the 
horse  propels  the  machinery  without  moving  from  his  place.  A horse  may  act  within  still  narrower 
limits,  if  he  is  made  to  stand  on  the  circumference  of  a large  vertical  wheel,  or  upon  a bridge  supported 


HOrtSE-SHOE  MACHINE. 


22 


by  endless  chains  which  pass  round  two  drums,  and  are  otherwise  supported  by  friction-wheels.  Va- 
rious other  methods  have  been  practised  for  applying  the  force  of  animals,  but  most  of  them  are  attended 
with  great  loss  of  power,  either  from  friction,  or  from  the  unfavorable  position  of  the  animal. 

For  agricultural  purposes,  the  movable-platform  horse-power  is  probably  the  best,  and  is  coming  very 
much  into  use.  It  consists  of  an  inclined  platform,  or  endless  chain,  provided  with  slats  of  wood  upon 
which  the  horse  treads,  giving  motion  to  a horizontal  shaft  by  means  of  teeth  in  the  chain  or  rack,  work 
mg  into  a pinion  on  the  shaft.  It  has  very  lately  been  patented  in  Italy  under  the  name  of  impulsoria, 
and  is  in  experimental  use  on  the  Southwestern  Railway  in  England,  and  is  thus  described  in  a late 
number  of  the  London  News : — 

The  patent  impulsoria,  for  railways,  consists  in  introducing  the  animals  into  a kind  of  coach,  called 
impulsoria,  by  which  they  transmit  their  acting  power  to  the  leading  -wheels.  This  transmission  is 
conveyed  by  a very  simple  means,  rendering  useful  both  the  driving  power  of  the  animals  and  their  own 
weight.  The  horse  being  thus  introduced  into  the  impulsoria,  is  placed  upon  a perfect  rectilinear,  arti- 
ficial ground,  or  platform,  turning  so  easily  that  the  animal,  which  is  yoked  to  the  shafts,  when  it  walks, 
does  not  itself  advance,  but,  what  amounts  to  the  same  thing,  the  platform  itself  is  pushed  backward, 
as  shown  in  Fig.  2266.  By  this  artificial  ground  platform,  called  by  the  patentee  pcdivella,  is  moved  an 
axle,  armed  with  a pulley,  from  which,  by  means  of  a rope,  the  motion  is  conveyed  to  the  axletree  oi 
the  leading  wheels.  The  varying  proportions  between  the  diameters  of  the  pulleys  give  different  de- 
grees of  speed.  The  horses  are  to  be  worked  always  at  their  usual  pace,  whilst  the  new  locomotive 
will  be  able  to  run  at  any  requisite  speed,  without  ever  altering  the  usual  walking  pace  of  the  horses, 
which  are  inside  the  impulsoria,  as  on  the  floor  of  a room,  sheltered  from  the  weather. 


The  importance  of  introducing  the  horses  into  the  carriage  in  order  to  get  more  speed  from  the  sur- 
plus of  the  acting  power,  had  been  long  thought  of,  and  the  principle  has  been  several  times  attempted 
in  England,  France,  and  Italy,  but  hitherto  without  success. 

The  new  machine  (whose  inventor  is  Signor  Clemente  Masserano,  from  Pignerol,  Piedmont)  haa 
been  brought  from  Italy  to  England,  and  deposited  at  the  Nine-elms  terminus  of  the  Southwestern 
Railway,  where  it  may  be  seen  working  on  the  line.  It  has  been  made  for  two  horses  only,  and  they 
work  it  very  well  on  the  pedivella.  More  than  thirty  wagons  have  been  already  experimentally  drawn 
by  it  up  the  very  inclined  line  of  the  station.  For  working  it  up  and  down  the  station,  a wagon  is  fast- 
ened to  it  when  it  attains  a speed  of  seven  miles  an  hour.  In  the  experiment  to  be  made  on  the  great 
line,  it  is  expected  to  gain  a speed  of  from  fifteen  to  twenty  miles  an  hour.  The  impulsoria  runs  either 
way,  like  the  steam-engine ; but  the  driving  horses  do  not  change  direction  or  movement.  They  can 
instantly  be  stopped,  without  stopping  the  machine ; and  the  machine  can  likewise  be  stopped  while 
the  horses  continue  to  walk  on  th e pedivella,  without  transmitting  motion  to  the  leading  wheels. 

By  the  simple  manner  in  which  the  horses  exercise  their  moving  power  on  the  new  machine,  they 
can  work  easily  the  usual  time,  commonly  about  eight  hours  a day. 

Such  economy  is  of  the  utmost  importance  to  the  numerous  interests  engaged  in  the  railways  subject 
to  enormous  working  expenses.  The  principal  advantage  of  the  new  machine  will  be  to  afford  very 
cheap  locomotion  on  all  branch  lines,  thus  extending  the  advantage  of  the  railway  to  localities  hitherto 
impracticable  from  the  expensive  moving  power. 

The  directors  of  the  Southwestern  Railway  were  the  first  to  receive  the  impulsoria  on  their  line 
where  they  have  granted  every  facility  to  its  ingenious  inventor. 

HORSE-SHOE,  Burden’s  Patent  Machine  for  making.  From  the  specifications  of  the  patents  we 
extract  the  following  description  of  the  machine  and  its  operation. 

Fig.  2207,  section  and  plan  of  the  machine  for  rolling,  drawing,  and  shaping  horse-shoes;  aaaa  sta- 
tionary or  outside  frame ; bhhh  feet  which  support  the  same ; c the  fly-wheel ; d the  connecting-rod 
e e the  crank  ; ff  the  moving-frame ; g the  rack,  having  cogs  in  it,  which  is  bolted  into  the  moving-frame, 
and  which  mashes  or  fits  into  the  segment  A,  having  long  cogs,  as  seen  at  h,  the  lower  or  under  segment 
which  is  fastened  into  the  roller  i,  as  seen  at  i.  Fig.  2269,  K the  moving-jaw  ; / 1 the  side  steels  or  iron, 
between  which  the  piece  of  iron  is  confined  and  the  sides,  while  it  is  drawn  or  rolled  by  the  swedges  D D 
having  steels  or  swedges  E E the  exact  thickness  of  the  shoe  intended. 

It  will  be  observed  that  one  of  these  side  steels  or  irons  is  fastened  into  the  moving-jaw  k or  K,  by 
means  of  screw-bolts,  while  the  other  is  similarly  fastened  into  the  moving-frame  f f.  m a button,  or  cam, 
which,  when  the  moving-frame  ff  is  moved  or  drawn  backwards  and  forwards  by  the  crank  e , through 
the  connecting-rod  d,  it  strikes  against  the  pin  or  stop  n,  which  permits  the  button  or  cam  o to  push  back 
or  open  the  moving-jaw  k,  when  it  strikes  against  the  pin  or  stop  p on  the  other  side  of  the  stationary 
frame,  by  which  means  the  piece  of  iron  which  may  be  between  the  side  steels  or  irons,  and  which  is 


HORSE-SHOE  MACHINE. 


23 


drawn  or  rolled  to  the  shape  desired,  is  permitted  to  drop  out.  q,  a pin  or  stop,  which,  when  the  earn 
o strikes  against  it  on  the  moving-frame’s  return  motion,  permits  the  cam  in,  when  it  strikes  against  tho 
pin  or  stop  r,  to  close  the  moving-jaw  k.  It  will  be  observed  that  when  the  moving- frame//  has  per- 
formed its  forward  motion,  then  the  cam  in  strikes  against  the  stop  n,  which  permits  the  cam  o to  open 
the  moving-jaw  k by  striking  against  the  stop  p,  which  allows  the  piece  of  iron,  which  may  have  been 
rolled  or  shaped  to  a horse-shoe,  to  drop  from  between  the  side  steels  or  irons  ll.  s,  a chisel  fastened 
'■y  screw-bolts  on  the  top  of  the  side  steel  or  iron  l\  t,  a chisel  fastened  by  screw-bolts  in  the  chise’ 
box  u u u. 


It  will  be  observed  that  the  box  uuu  turns  on  a pin  in  the  moving-frame,  which,  when  the  crank 
pushes  back  the  moving-frame,  the  head  or  box  part  strikes  against  the  pin  or  piece  of  iron  w,  and 
presses  up  the  chisel  t against  the  chisel  .s,  and  cuts  off  the  piece  of  iron  to  the  length  intended  for  a 
horse-shoe,  v , a piece  of  iron  intended  to  draw  back  the  chisel-box  uuu,  as  seen  at  Fig.  2268  ; xxxx, 
brasses  on  which  the  moving-frame  slides  backwards  and  forwards ; y , a piece  of  iron  to  lay  the  bar  on 
as  a guide  while  in  the  act  of  feeding  into  the  machine.  Z Z end  view  and  section  of  the  posts  through 
which  the  rollers  i i are  fastened  and  revolve ; A,  piece  of  iron  or  stop  which  graduates  the  length  o, 
shoe ; B,  piece  of  iron  having  a hole  in  it,  through  which  the  iron  or  stop  A passes,  which  graduates  the 
length  of  shoe ; C,  the  piece  of  iron  which  prevents  the  shoe  from  being  drawn  back  by  the  chisel  or 
the  side  steel  l,  previous  to  the  swedges  pressing  it  between  them. 


Fig.  2268,  section  and  elevation  of  machine.  A,  segments  which  are  fastened  into  the  rollers  ii\  O, 
the  rack  which  mashes  or  works  into  the  upper  segment  h,  the  cogs  of  which  being  twice  the  length  i i 
the  under  segment  h permits  the  rack  to  operate  into  it,  which,  when  pushed  backwards  and  forwards 
by  the  moving-frame  / / the  whole  is  put  in  motion,  i i,  the  rollers  into  which  the  segments,  witli 
cogs  h h and  swedges  I)  D,  with  pieces  or  swedges  EE,  are  fastened,  k the  moving-jaw;  1 1 the  side 
steels  or  irons  between  which  the  piece  of  iron  is  held,  while  it  is  rolled  or  drawn  by  the  vertical 
swedges  D D and  the  steels  or  swedges  E E to  the  desired  shape  of  shoe.  It  will  be  perceived  that 
the  rollers  i i revolve  on  gudgeons.  Z Z,  posts  or  stationary  frame,  into  which  the  rollers  i i are  fastened 
and  revolve. 

Fig.  2271,  sectional  elevation  of  part  of  the  machine,  i i,  the  rollers  in  which  the  swedges  with  the 
pieces  of  steel  or  swedges  E E are  fastened.  1 1,  one  of  the  side  steels  or  irons.  Id  represents  a piece  of 
iron  as  being  formed  into  a horse-shoe.  It  will  readily  be  perceived  that  by  grinding  the  steels  or  swedges 
E E,  any  shape  or  taper  required  can  be  given  to  the  piece  of  iron  or  shoe  marked  H.  It  will  be  ob- 
served that  the  four  views  or  figures,  as  above  described,  represents  the  part  or  parts  of  machinery  for 
cutting  ofti  rolling,  or  drawing  the  iron  into  the  shape  required  for  horse-shoes,  and  that  Fig.  2267*  is  a 


24 


HORSE-SHOE  MACHINE. 


section,  having  the  upper  roller  i removed  for  the  purpose  of  showing  more  distinctly  the  interim 
arrangements  of  the  machine. 

Fig.  2270,  sectional  elevation  of  part  of  the  machine,  ii  the  rollers.  DD  the  swedges:  the  under 
one,  which  is  cast-iron,  or  may  be  fitted  with  steel  swedge  similar  to  those  used  for  rolling  or  shaping 
the  shoe,  as  seen  at  D D,  E E,  the  edge  of  which  being  similar  to  the  flat  side  of  a horse-shoe.  The 
upper  one  is  also  of  cast-iron,  so  constructed  as  to  fasten  in  two  pieces  of  steel  under  the  covers  or 
caps  i i.  These  pieces  of  steel  are  so  shaped  at  their  edges  as  to  groove  and  punch  the  holes  at  one 
operation.  They  are  graduated  as  to  depth  by  the  four  screws  which  pass  through  the  ftanch  above 
l L,  one  of  the  side  steels.  H represents  a horse-shoe  in  the  act  of  being  grooved  and  punched. 


2270.  2271. 


The  machine  for  grooving  and  punching  is  precisely  as  the  one  for  rolling  or  drawing  the  shoe  to  the 
required  shape,  with  the  exception  of  the  upper  swedge,  as  described  above. 

Fig.  2272,  elevation  of  machine  for  bending  horse-shoes,  aaa  the  frame,  b b the  feet  which  support 
the  same,  ccthe  fly-wheel,  d the  connecting-rod.  E the  crank-shaft,  ff  the  rack.  gg  the  two 
shafts.  K the  piece  of  iron  round  which  the  shoe  is  bent,  having  cogs  on  its  edges  shaped  so  as  to  fit 
and  mash  into  the  piece  K,  while  they  revolve  round  on  their  respective  shafts  g g.  M the  wheel  which 
mashes  and  tits  into  the  rack  ff,  and  which  communicates  motion  to  the  shafts  g g and  pieces  of  iron  K 
and  L.  If  a button  or  nipper  which  takes  hold  at  the  end  of  the  horse-shoe,  in  consequence  of  its 
coming  in  contact  with  the  piece  of  iron  L,  and  holds  it  fast  while  it  is  in  the  act  of  bending ; and  when 
bent,  said  button  or  nipper  strikes  against  the  other  side  of  piece  L,  which  opens  and  lets  the  shoe  drop. 
It  will  be  observed  that  the  shafts  g g and  pieces  of  iron  K and  L do  not  make  a full  revolution 


Fig  227 J-,  plan  of  machine  for  bending  horse-shoes,  a a the  frame,  c the  fly-wheel,  e the  crank-shaft 
J.  the  connecting-rod.  f a rack.  M a wheel,  whose  cog  mashes  or  fits  into  the  cogs  of  the  rack  f 
L the  eccentric  piece  of  iron  which  tits  into  the  piece  K,  on  which  the  shoe  is  formed,  as  seen  at  Figs 


HORSE-SHOE  MACHINE. 


2272  and  2273.  0,  cap  which  confines  the  piece  of  iron  while  in  the  act  of  bending  around  the  piece  K, 
as  represented  by  the  dotted  lines  at  Fig.  2273. 

Fig.  2273,  section  of  the  irons  K and  L.  These  two  pieces,  K and  L,  are  fastened  on  the  shaft  g g 
with  their  reversed  sides  up  from  what  they  appear  in  the  drawing.  The  dotted  lines  represent  a cap, 
which  is  fastened  on  the  piece  of  iron  L with  screw-bolts.  This  cap  is  about  one  inch  thick,  and  serves 
the  purpose  of  keeping  the  iron  close  up  while  in  the  operation  of  bending  around  the  piece  of  iron  K. 


2274. 


The  nature  of  the  operation  is  as  follows : — 

Firstly : Fig.  2267  represents  a section  of  the  machine,  having  the  upper  roller  i removed,  so  as  to 
show  more  distinctly  the  interior  arrangement  of  the  machine.  Supposing  a pulley  of  about  four  feet 
diameter  were  bolted  to  the  arms  of  the  fly-wheel  c,  (which  is  omitted  in  the  drawing,)  and  to  which 
motion  were  communicated  by  a leather  strap  or  belt  from  a corresponding  pulley  on  a shaft  connected 
with  a water-wheel  or  other  power ; it  is  evident  that  every  revolution  of  the  fly-wheel  c would  move 
the  carriage  or  moving -frame  ff  backwards  and  forwards,  giving  motion  to  the  different  parts  of  the 
machine,  as  described  and  shown  above. 

Aud  supposing  the  crank  e e,  by  the  connecting-rod  d,  had  pulled  or  drawn  the  moving-frame  ff 
forward  so  as  to  cause  the  button  or  cam  m to  strike  against  the  stop  n,  the  cam  o would  also  strike 
against  the  stopp,  and  consequently  push  back  or  open  the  moving-jaw  k,  which  turns  on  a pivot  at 
the  other  end.  And  supposing  the  moving-frame// were  pushed  back  on  the  brasses  x x,  and  towards 
the  last  part  of  the  motion  a hot  piece  of  iron  (previously  rolled  to  the  desired  size)  were  introduced  be- 
tween the  side  steels  or  irons  1 1,  it  is  evident  that  the  cutter-box  uuu  would  strike  against  the  stop  w and 
press  up  the  chisel  t against  the  chisel  s,  cutting  off  the  necessary  length  of  iron  to  make  the  shoe  ; and 
should  the  moving-frame  be  drawn  forward  by  the  crank  e,  the  piece  of  iron,  being  confined  bv  the  side 
steels  or  irons  1 1 on  the  sides,  would  be  rolled  or  shaped  by  the  vertical  steels  or  swedges  E E,  when 
the  cam  m would  strike  against  the  stop  n and  permit  o to  open  the  jaw  k and  let  the  piece  drop ; the 
appearance  and  shape  of  which  may  be  seen  as  represented  by  H,  are  so  ground  or  shaped  as  to  roll 
or  taper  the  piece  H at  each  end  intended  for  the  heels  of  the  shoe ; but  it  is  found  by  experiment  that 
by  using  the  iron  square,  and  so  grinding  the  steel  or  swedges  E E as  to  flatten  or  roll  down  the-  middle 
of  the  piece,  leaving  the  ends  square  for  the  heels  of  the  shoe,  makes  the  best  shoe. 

Secondly : Having  explained  the  process  of  cutting  the  bar  or  rod  into  suitable  lengths,  and  rolling  or 
shaping  the  same  suitable  for  horse-shoes,  it  remains  to  describe  the  method  of  punching  and  grooving 
them.  And  having  already  stated  that  the  machine  for  grooving  and  punching  is  precisely  the  same 
as  the  one  above  described  for  rolling  or  shaping  the  shoe,  with  the  exception  of  the  upper  swedge, 
which  is  substituted  for  the  swedge  represented  in  Fig.  2271 : supposing  in  a machine  every  way  similar 
to  the  one  for  rolling  or  shaping  the  shoe,  as  described  under  the  first  head,  (with  the  exception  of  the 
upper  swedge,  in  lieu  of  which  the  one  represented  by  Fig.  2270  was  substituted,)  the  piece  of  iron 
which  came  from  the  first  machine  were  introduced  between  the  side  steels  or  irons  l /,  and  the  machine 
set  in  motion,  it  is  evident  it  would  be  grooved  and  punched  and  drop  out  of  the  machine  on  the  moving- 
jaw  K being  opened  in  the  same  manner  as  the  piece  dropped  out  from  the  first  machine,  as  described 
under  the  first  head. 

Thirdly : Having  described  the  manner  in  which  the  piece  is  grooved  and  punched,  it  remains  to 
show  how  it  is  bent,  which  is  the  last  operation.  The  piece  of  iron  being  now  rolled  or  shaped  as  may 
be  desired  for  a horse-shoe,  as  also  grooved  and  punched,  is  introduced  into  the  machine,  as  shown  and 
described  in  Figs.  2272  to  2274. 

We  here  copy  Mr.  Burden’s  claim : 

“ First : I claim  the  machine  for  rolling,  drawing,  or  shaping  horse-shoes,  as  described  and  represented 
by  Figs.  2267  to  2272,  as  a whole  as  there  arranged ; namely,  those  parts  called  side  steels  or  irons  1 1, 
which  confine  the  piece  of  iron  intended  for  a horse-shoe,  on  the  sides,  while  it  is  rolled  or  shaped  by 
the  vertical  swedges  EE.  I also  claim  the  vibrating  or  reciprocating  motion  of  moving-frame  ff, 
which  gives  motion  to  all  the  other  parts  of  the  machine,  which  enables  the  operator  to  feed  up  the  iron 
intended  for  horse-shoes  to  the  stop  A,  cutting  it  off  accurately,  and  rolling  aud  shaping  them  at  the 
same  time. 

And  I claim  the  above-named  reciprocating  motion,  whether  it  be  by  side  steels  or  swedges,  as 
above  named,  or  whether  it  be  merely  a pair  of  common  grooved  rollers,  the  one  having  a groove  or 
channel  turned  or  cut  the  shape  of  the  shoe,  the  other  having  a fongue  so  shaped  as  to  tit  the  groove 
exactly,  the  periphery  of  said  tongue  being  so  shaped  as  to  roll  the  shoe  thinner  at  some  parts  than  at 
others,  as  may  be  desired. 

It  will  be  observed  that  if  two  rollers,  as  aboved  named,  were  connected  together  at  the  end  by  two 
pinions,  and  on  the  other  end  of  one  were  fastened  a wheel  similar  to  the  wheel  M on  one  of  the  shafts  z 
of  the  bending  machine,  having  a jack  operating  into  said  wheel,  connected  to  a crank  in  every  respect 


26 


HYDRODYNAMICS. 


similar  to  the  bending  machine,  it  is  evident  that  said  rollers  would  move  backwards  and  forwards,  making 
such  part  of  a revolution  as  the  length  of  the  crank  might  give  them.  I therefore  claim  said  recipro- 
cating motion  when  applied  to  rolling  or  shaping  horse-shoes  by  rollers.  I do  not  claim  the  use  of  solid 
rollers  in  rolling  horse-shoes ; for  I believe  this  has  been  done,  or,  rather,  attempted  to  be  done,  and  has 
universally  proved  a failure,  in  consequence  of  not  having  reciprocating  motion  to  enable  the  operator  to 
feed  up  the  iron  to  a stop  so  as  to  insure  the  piece  of  iron  intended  for  a horse-shoe  being  always  in  the 
proper  place  to  receive  the  impression  from  the  roller. 

Another  reason  why  rolling  horse-shoes  by  solid  rollers  has  failed,  is,  that  the  tongue  of  the  one  and 
socket  of  the  other  are  liable  to  wear,  and  consequently  have  to  be  laid  aside.  Whereas,  my  method 
of  having  the  tongue  or  swedges,  as  also  the  socket,  divided  into  sections,  allows  the  whole  being 
ground,  repaired,  and  moved  at  pleasure  by  screws,  so  as  to  insure  the  sides  of  the  socket  fitting  close 
to  the  tongue,  as  also  having  one  side  of  the  socket  movable,  to  allow  the  shoes  being  discharged.  I 
also  claim  the  method  of  having  those  parts  of  the  machine  which  confine  the  iron  on  the  sides,  repre- 
sented as  side  steels,  marked  1 1,  movable,  so  as  to  permit  their  being  ground,  when  worn,  at  the 
same  time  moving  them  close  up  to  the  swedges  E E by  screws.  I also  claim  the  plan  of  making  the 
rollers  i i,  with  an  open  mortise,  so  as  to  permit  the  swedges  D D being  moved.  In  fine,  I claim 
the  method  of  dividing  the  working  parts  which  roll  or  shape  the  shoe  into  such  sections  as  enables  me 
to  grind,  replace,  and  remove  them  at  pleasure ; in  lieu  of  solid  rollers,  which,  when  worn,  have  to  be  laid 
aside  altogether.  I wish  it  to  be  particularly  understood  that  I do  not  confine  myself  to  the  precise 
method  of  operating  the  machine  for  rolling  or  shaping  horse-shoes,  as  represented  by  the  drawing 
hereunto  annexed ; as,  in  lieu  of  the  frame  ff  being  moved,  it  may  be  made  stationary,  and  the  rollers  i i 
moved  backwards  and  forwards  in  slides,  with  corresponding  movements  given  to  the  other  parts,  which 
would  give  analogous  results. 

Secondly : I claim  the  machine  for  grooving  and  punching  horse-shoes,  as  represented  by  the  figures 
and  descriptions  thereof.  That  is  to  say,  I claim  the  manner  of  confining  the  piece  of  iron  intended  for 
a horse-shoe,  between  the  side  steels  1 1,  while  in  the  act  of  grooving  and  punching,  by  the  upper  swedge 
D having  the  pieces  of  steel  fastened  under  the  caps  ii.  I also  claim  the  vibrating  or  reciprocating 
motion  of  the  machine  in  grooving  and  punching,  for  the  same  reasons  as  set  forth  in  my  claim  to  the 
machine  for  rolling  or  shaping.  I claim  the  manner  of  so  shaping  the  edge  of  the  steels  as  to  leave 
projections  for  the  heads  of  the  nails,  as  in  all  cases,  even  when  made  by  hand,  the  groove  is  first 
made,  then  the  holes ; but  by  my  plan  I make  both  at  once,  which  serves  the  double  purpose  of  adding 
strength  to  the  punches,  by  being  formed  and  composing  part  of  the  steel  which  forms  the  groove  or 
channel,  as  also  performing  both  operations  at  once.  I also  claim  the  method  of  fastening  the  two 
pieces  of  steel  which  groove  and  punch  the  shoe  under  the  caps  ii,  which  permits  their  being  screwed 
down  by  four  screws,  when  necessary,  in  consequence  of  their  becoming  short  by  filing  or  other  causes. 
And  as  I deem  the  discovery  of  forming  the  projections  or  punches  on  the  same  piece  of  steel  which 
grooves  or  channels  the  shoe  of  great  importance,  I shall  describe  the  manner  in  which  it  is  done.  Take 
a piece  of  cast  or  other  steel,  previously  rolled  or  hammered  to  about  one-fourth  of  an  inch  in  thickness, 
about  four  inches  wide,  and  as  long  as  necessary,  to  form  the  groove  on  ope  side  of  the  shoe.  Then 
grind  or  reduce  the  edge  by  a file  to  the  proper  shape  to  form  the  groove  : then  mark  the  projections  or 
punches,  filing  down  the  spaces  between  the  projections  so  as  to  give  them  sufficient  length  to  form  the 
holes,  which  adds  great  strength  to  the  punches,  compared  with  the  method  of  inserting  small  pieces  oi 
steel  into  a roller  to  form  punches. 

Thirdly : I claim  the  machine  for  bending  horse-shoes,  as  represented  and  described  by  the  drawings 
thereof,  in  every  particular  as  there  arranged.  And  in  addition  to  which,  I claim  any  other  method  oi 
bending  horse-shoes,  so  long  as  the  piece  is  taken  hold  of  by  one  end,  while  the  other  is  bent  round  the 
mould,  no  matter  whether  the  mould  revolve  round  or  is  stationary,  and  the  piece  of  iron  is  pulled  or 
bent  round  it. 

I also  claim,  in  a particular  jnanner,  the  placing  of  the  face  of  the  mould  downwards,  so  as  to  permit 
the  shoe  to  drop  or  discharge  itself.  I also  claim  the  using  of  a piece  of  flat  iron,  as  represented  by  the 
dotted  lines  in  Eig.  2273,  for  the  purpose  of  keeping  the  shoe  close  up  to  the  mould  while  in  the  act  of 
bending.  I also  claim  the  nipper  or  button,  which  closes  and  holds  fast  the  end  of  the  horse-shoe  by 
striking  against  the  piece  L while  in  the  act  of  bending  round  the  shoe  shape  K,  and  which  opens  in 
consequence  of  its  coming  in  contact  with  the  other  side  of  the  piece  L,  and  lets  the  shoe  drop. 

I also  claim  the  manner  of  making  the  geering  or  wheels  connected  with  the  pieces  of  iron  K and  L 
eccentric,  or  so  shaped  as  to  have  the  pitched  line  describe  the  same  circle  as  the  shoe. 

HYDRAULIC  RAM.  See  Ram. 

HYDRODYNAMICS,  is  that  branch  of  general  mechanics  which  treats  of  the  equilibrium  and  motion 
of  fluids.  The  terms  hydrostatics  and  hydrodynamics  have  corresponding  signification  to  the  statics  and 
dynamics  in  the  mechanics  of  solid  bodies;  viz.,  hydrostatics  is  that  division  of  the  science  which  treats 
of  the  equilibrium  of  fluids,  and  hydrodynamics  that  which  relates  to  their  forces  and  motion.  It  is, 
however,  very  usual  to  include  the  whole  doctrine  of  the  mechanics  of  fluids  under  the  general  term  of 
hydrodynamics,  and  to  denote  the  divisions  relative  to  their  equilibrium  and  motion  by  the  terms  hydro- 
statics and  hydraulics.  We  adopt  the  latter  division,  and  shall  confine  onrselves  to  a few  of  the 
most  usually  received  theoretical  deductions,  and  state  those  rules  which  have  been  the  result  of  a ju- 
ciicious  application  of  theory  to  experiment,  as  the  subject  itself  is  the  one  the  least  advanced  of  any 
branch  of  mechanics,  and  we  are  as  yet  far  from  being  in  possession  of  the  requisite  data  for  a rigorous 
solution  of  the  problems  which  arise.  Very  many  excellent  treatises  have  been  written,  to  which  we 
refer  the  scientific  reader ; but  the  extent  of  the  subject  forbids  the  introduction  of  any  of  them  into 
this  work,  further  than  to  select  the  best  practical  rules  for  the  use  of  the  mechanic. 

Hydrostatics  comprises  the  doctrine  of  the  pressure  and  the  equilibrium  of  non-elastic,  fluids,  as  water 
mercury,  &c.,  and  that  of  the  wreight  and  pressure  of  solids  immersed  in  them. 

1 . Fluids  press  equally  in  all  directions,  upwards,  downwards,  aslant  or  laterallv 


HYDRODYNAMICS. 


27 


This  constitutes  one  essential  difference  between  fluids  and  solids,  solids  pressing  only  downwards  01 
ji  the  direction  of  gravity. 

2.  The  upper  surface  of  a gravitating  fluid  at  rest  is  horizontal. 

3.  The  jiressure  of  a fluid  on  every  particle  of  the  vessel  containing  it,  or  of  any  othei  surface,  real  oi 
imaginary,  in  contact  with  it,  is  equal  to  the  weight  of  a column  of  the  fluid,  whose  base  is  equal  to  that 
particle,  and  whose  height  is  equal  to  its  depth  below  the  upper  surface  of  the  fluid. 

4.  If,  therefore,  any  portion  of  the  upper  part  of  a fluid  be  replaced  by  a part  of  the  vessel,  the  pres- 
sure against  this  from  below  will  be  the  same  which  before  supported  the  weight  of  the  fluid  removed, 
and  every  part  remaining  in  equilibrium,  the  pressure  on  the  bottom  will  be  the  same  as  it  would  if  the 
vessel  were  a prism  or  a cylinder. 

5.  Hence,  the  smallest  given  quantity  of  a fluid  may  be  made  to  produce  a pressure  capable  of  sus- 
taining any  proposed  weight,  either  by  diminishing  the  diameter  of  the  column  and  increasing  its  height, 
or  by  increasing  the  surface  which  supports  the  weight.  It  is  upon  this  principle  that  the  hydrostatic 
press  is  made  to  operate.  See  Hydrostatic  Press. 

6.  The  pressure  of  a fluid  on  any  surface,  whether  vertical,  oblique,  or  horizontal,  is  equal  to  tin 
weight  of  a column  of  the  fluid  whose  base  is  equal  to  the  surface  pressed,  and  height  equal  to  the  dis 
tance  of  the  centre  of  gravity  of  that  surface  below  the  upper  horizontal  surface  of  the  fluid. 

7.  Fluids  of  different  specific  gravities  that  do  not  mix,  will  counterbalance  each  other  in  a bent  tube 
when  their  heights  above  the  surface  of  junction  are  inversely  as  their  specific  gravities. 

A portion  of  fluid  will  be  quiescent  in  a bent  tube,  when  the  upper  surface  in  both  branches  oi  the 
tube  is  in  the  same  horizontal  plane,  or  is  equidistant  from  the  earth’s  centre.  And  water  poured  down 
one  branch  of  such  a tube,  (whether  it  be  of  uniform  bore  throughout  or  not,)  will  rise  to  its  own  level 
in  the  other  branch. 

Thus,  water  may  be  conveyed  by  pipes  from  a spring  on  the  side  of  a hill,  to  a reservoir  of  equal 
height  on  another  hill. 

8.  The  ascent  of  a body  in  a fluid  of  greater  specific  gravity  than  itself,  arises  from  the  pressure  of 
the  fluid  upwards  against  the  under  surface  of  the  body. 

The  centre  of  pressure  is  that  point  of  a surface  against  which  any  fluid  presses,  to  which  if  a force 
equal  to  the  whole  pressure  were  applied,  it  would  keep  the  surface  at  rest,  or  balance  its  tendency  to 
turn  or  move  in  any  direction. 

The  centre  of  pressure  of  a parallelogram,  whose  upper  side  is  in  the  plane  of  the  horizontal  level  of 
the  liquid,  is  at  § of  the  line  (measuring  downwards)  that  joins  the  middles  of  the  two  horizontal  sides 
of  the  parallelogram. 

If  the  base  of  a triangular  plane  coincides  with  the  upper  surface  of  the  water,  then  the  centre  oj 
pressure  is  at  the  middle  of  the  line  drawn  from  the  middle  of  the  base  to  the  vertex  of  the  triangle , 
]3ut,  if  the  vertex  of  the  triangle  be  in  the  upper  surface  of  the  water,  while  its  base  is  horizontal,  he 
centre  of  pressure  is  at  J of  the  line  drawn  from  the  vertex  to  bisect  the  base. 

If  b the  breadth  and  d the  depth  of  a rectangular  gate,  or  other  surface,  exposed  to  the  pressure  of 
water  from  top  to  bottom,  then  the  entire  pressure  is  equal  to  the  weight  of  a prism  of  water  "whose 
content  is  \b  d2.  Or,  if  b and  d be  in  feet,  then  the  whole  pressure  — 311  b d2,  in  pounds. 

If  the  gate  be  in  form  of  a trapezoid,  widest  at  top,  then,  if  b and  b be  the  breadths  at  the  top  and 
bottom  respectively,  and  d the  depth, 

Whole  pressure  in  pounds  = 31J  [ J (b  — b)  -f-  b]  d2. 

Floating  bodies. — If  any  body  float  on  a fluid,  it  displaces  a quantity  of  the  fluid  equal  to  itself  in  weight. 

Also,  the  centres  of  gravity  of  the  body  and  of  the  fluid  displaced,  must,  when  ihe  body  is  at  rest,  be 
in  the  same  vertical  line. 

If  a vessel  contain  two  fluids  that  will  not  mix,  (as  water  and  mercury,)  and  a solid  of  some  interme- 
diate specific  gravity  be  immersed  under  the  surface  of  the  lighter  fluid  and  float  on  the  heavier,  the 
part  of  the  solid  immersed  in  the  heavier  fluid,  is  to  the  whole  solid  as  the  difference  between  the  spe- 
cific gravities  of  the  solid  and  the  lighter  fluid  is  to  the  difference  between  the  specific  gravities  of  the 
two  fluids. 

Tire  buoyancy  of  casks,  or  the  load  which  they  will  carry  without  sinking,  may  be  estimated  by  reck- 
oning 10  pounds  avoirdupois  to  the  ale  gallon. 

The  buoyancy  of  pontoons  may  be  estimated  at  about  half  a hundred  weight  for  each  cubic  foot. 

Thus  a pontoon  which  contained  96  cubic  feet,  would  sustain  a load  of  48  cwt.  before  it  would  sink. 
This  is  an  approximation,  in  which  the  difference  between  T6f  and  4,  that  is,  A of  the  whole  weight,  is 
allowed  for  that  of  the  pontoon  itself. 

Tins  property  has  been  successfully  employed  in  pulling  up  piles  in  a river  where  the  tide  ebbs  and 
flows.  A barge  of  considerable  dimensions  is  brought  over  a pile  as  the  water  begins  to  rise ; a strong 
chain  which  has  been  previously  fixed  to  the  pile  by  a ring,  &c.,  is  made  to  gird  the  barge,  and  is  then 
fastened.  As  the  tide  rises  the  vessel  rises  too,  and  by  means  of  its  buoyant  force  draws  up  the  pile 
with  it. 

In  an  actual  case,  a barge  50  feet  long,  12  feet  wide,  6 deep,  and  drawing  2 feet  of  water,  was  em- 

50  V 1 o V 1 6 

ployed.  Here,  50  X 12  X (6  — 2)  X :}  = ’ ~ = 192  X 7 = 1344  -f  27?  = 1371-J  cwt.  •= 

66£  tons,  nearly,  the  measure  of  the  force  with  which  the  barge  acted  upon  the  pile. 

Specific  gravities. — If  a body  float  on  a fluid,  the  part  immersed  is  lo  the  whole  body  as  the  specific 
gravity  of  the  body  to  the  specific  gravity  of  the  fluid.  (See  Gravity  and  Specific  Gravity.) 

Hydraulics  is  that  part  of  mechanical  science  which  relates  to  the  motion  of  non-elastic  fluids,  and  the 
forces  with  which  they  act  upon  bodies. 


28 


HYDRODYNAMICS. 


Motion  and  effluence  of  liquids. — 1.  A jot  of  water,  issuing  from  an  orifice  of  a proper  form,  and  di- 
rected upwards,  rises,  under  favorable  circumstances,  nearly  to  the  height  of  the  head  of  water  in  the 
reservoir ; and  since  the  particles  of  such  a stream  are  but  little  influenced  by  the  neighboring  ones, 
they  may  be  considered  as  independent  bodies,  moving  initially  with  the  velocity  which  would  be  ac- 
quired in  falling  from  the  height  of  the  reservoir.  And  the  velocity  of  the  jet  will  be  the  same  whatever 
may  be  its  direction. 

2.  Hence,  if  a jet  issue  horizontally  from  any  part  of  the  side  of  a vessel  standing  on  a horizontal 
plane,  and  a circle  be  described  having  the  whole  height  of  the  fluid  for  its  diameter,  the  fluid  will  reach 
the  plane  at  a distance  from  the  vessel,  equal  to  that  chord  of  the  circle  in  which  the  jet  initially  moves. 

3.  When  a cylindrical  or  prismatic  vessel  empties  itself  by  a small  orifice,  the  velocity  at  the  surface 
is  uniformly  retarded ; and  in  the  time  of  emptying  itself,  twice  the  quantity  would  be  discharged  if  it 
were  kept  full  by  a new  supply. 

4.  But  the  quantity  discharged  is  by  no  means  equal  to  what  would  fill  the  whole  orifice,  with  this 
velocity.  If  the  aperture  is  made  simply  in  a thin  plate,  the  lateral  motion  of  the  particles  towards  it 
tends  to  obstruct  the  direct  motion,  and  to  contract  the  stream  which  has  left  the  orifice,  nearly  in  the 
ratio  of  two  to  three.  So  that  in  order  to  find  the  quantity  discharged,  the  section  of  the  orifice  must 
be  supposed  to  be  diminished  from  100  to  62  for  a simple  aperture,  to  82  for  a pipe  of  which  the  length 
is  twice  the  diameter,  and  in  other  ratios  according  to  circumstances. 

5.  When  a siphon,  or  bent  tube,  is  filled  with  a fluid,  and  its  orifices  immersed  in  the  fluids  of  different 
vessels,  if  both  surfaces  of  the  fluids  are  in  the  same  level,  the  whole  remains  at  rest ; but  if  otherwise, 
the  longer  column  of  fluid  in  the  siphon  preponderates,  and  the  pressure  of  the  atmosphere  forces  up 
the  fluid  from  the  higher  vessel,  until  the  equilibrium  is  restored ; and  the  motion  is  the  more  rapid  as 
the  difference  of  levels  is  greater:  provided  that  the  greatest  height  of  the  tube  above  the  upj>er  sur- 
face be  not  more  than  a counterpoise  to  the  pressure  of  the  atmosphere. 

6.  If  a notch  or  sluice  in  form  of  a rectangle  be  cut  in  the  vertical  side  of  a vessel  full  of  water,  or 
any  other  fluid,  the  quantity  flowing  through  it  wall  be  § of  the  quantity  which  would  flow  through  an 
equal  orifice  placed  horizontally  at  the  whole  depth,  in  the  same  time,  the  vessel  being  kept  constantly  full. 

7.  If  a short  pipe,  elevated  in  any  direction  from  an  aperture  in  a conduit,  throw  the  water  in  a par- 
abolic curve  to  the  distance  or  range  r,  on  a horizontal  plane  passing  through  the  orifice,  and  the  greatest 
height  of  the  spouting  fluid  above  that  plane  be  h,  then  the  height  of  the  head  of  water  above  that  con- 
duit pipe  may  lie  found,  nearly : viz.,  by  taking,  first,  2 cot  e = - — ; and,  secondly,  the  altitude  of  the 
head  a = J r X cosec  2 e. 

Ex.  Suppose  that  r = 40  feet,  and  h = 18  feet.  Then  ~ — 1111111 1 = 2 cot  60°  57' : and 

X cosec  2e  = 20  X cosec  121°  54'  = 20  X T177896  = 23'55'792  feet,  height  required. 

Note.  This  result  of  theory  will  usually  be  found  about  4-5ths  of  that  which  is  furnished  by 
experiment. 

Motion  of  water  in  conduit  pipes  and  open  canals,  over  weirs,  dec. — 1.  When  the  water  from  a reser- 
voir is  conveyed  in  long  horizontal  pipes  of  the  same  aperture,  the  discharges  made  in  equal  times  are 
nearly  in  the  inverse  ratio  of  the  square  roots  of  the  lengths. 

It  is  supposed  that  the  lengths  of  the  pipes  to  which  this  rule  is  applied  are  not  very  unequal.  It  is 
an  approximation  not  deduced  from  principle,  but  derived  immediately  from  experiment. 

2.  Water  running  in  open  canals,  or  in  rivers,  is  accelerated  in  consequence  of  its  depth,  and  of  the 
declivity  on  which  it  runs,  till  the  resistance  increasing  with  the  velocity,  becomes  equal  to  the  accel- 
eration, when  the  motion  of  the  stream  becomes  uniform. 

It  is  evident  that  the  amount  of  the  resisting  forces  can  hardly  be  determined  by  principles  already 
known,  and  therefore  nothing  remains  but  to  ascertain,  by  experiment,  the  velocity  corresponding  to 
different  declivities,  and  different  depths  of  water,  and  to  try,  by  multiplying  and  extending  these  ex- 
periments, to  find  out  the  law  which  is  common  to  them  all. 

The  Chevalier  Du  Buat  has  given  a formula  for  computing  the  velocity  of  running  water,  whether  in 
close  pipes,  open  canals,  or  rivers,  which,  though  it  may  be  called  empirical,  is  extremely  useful  hi 
practice. 

Let  v be  the  velocity  of  the  stream,  measured  by  the  inches  it  moves  over  in  a second  ; r a constant 
quantity,  viz.,  the  quotient  obtained  by  dividing  the  area  of  the  transverse  section  of  the  stream,  ex- 
pressed in  square  inches,  by  the  boundary  or  perimeter  of  that  section,  minus  the  superficial  breadth 
of  the  stream  expressed  in  linear  inches. 

The  mean  velocity  is  that  with  which,  if  all  the  particles  were  to  move,  the  discharge  would  be  the 
same  with  the  actual  discharge. 

The  line  r is  called  by  Du  Buat  the  radius,  and  by  Dr.  Robison  the  hydraulic  mean  depth.  As  its 
affinity  to  the  radius  of  a circle  seems  greater  than  to  the  depth  of  a river,  we  shall  call  it,  with  the 
former,  the  radius  of  the  section. 

Lastly,  let  s be  the  denominator  of  a fraction  which  expresses  the  slope,  the  numerator  being  unity, 
that  is,  let  it  be  the  quotient  obtained  by  dividing  the  length  of  the  stream,  supposing  it  extended  in  a 
Itraight  line,  by  the  difference  of  level  of  its  two  extremities ; or,  which  is  nearly  the  same,  let  it  be  the 
co-tangent  of  the  inclination  or  slope. 

The  above  denominations  being  understood,  and  the  section,  as  well  as  the  velocity,  being  supposed 
uniform,  v in  English  feet, 

307  ^(r-A) 
si-ilog.(s+  -|J) 


HYDRODYNAMICS. 


29 


orv  = v/u- 

When  r and  s are  very  great, 


307 


• I log.  (s  -f  If) 


A 

i o.  I 


307 


nearly. 


S*  4 log.  S 

The  logarithms  understood  here  are  the  hyperbolic,  and  are  found  by  multiplying  the  common  loga 
?ithms  by  2-3025851. 

The  slope  remaining  the  same,  the  velocities  are  as  y/  r — T’(|. 

The  velocities  of  two  rivers  that  have  the  same  declivity,  are  as  the  square  roots  of  the  radii  of  the!' 
sections. 

If  r is  so  small,  that  r — > = 0,  or  u = -A,  the  velocity  will  be  nothing,  wbidi  is  agreeable  to 
experience  ; for  in  a cylindric  tube  r = •$•  the  radius ; the  radius,  therefore,  equal  two-tenths ; so  that 
the  tube  is  nearly  capillary,  and  the  fluid  will  not  flow  through  it. 

The  velocity  may  also  become  nothing  by  the  declivity  becoming  so  small,  that 

— ^2 3=0  ; but 


s — i log-  (s  + |f) 


if  — is  less  than , or  than  I-  of  an  inch  to  an  English  mile,  the  water  will  have  sensible  motion. 

s 500000  10 


In  a river,  the  greatest  velocity  is  at  the  surface,  and  in  the  middle  of  the  stream,  from  which  it 
diminishes  towards  the  bottom  and  the  sides,  where  it  is  least.  It  has  been  found  by  experiment,  that, 
if  from  the  square  root  of  the  velocity  in  the  middle  of  the  stream,  expressed  in  inches  per  second,  unity 
be  subtracted,  the  square  of  the  remainder  is  the  velocity  at  the  bottom. 

Hence,  if  the  former  velocity  be  = v,  the  velocity  at  the  bottom  —v  — 2 y/  v l.  (A.) 

The  mean  velocity,  or  that  with  which,  were  the  whole  stream  to  move,  the  discharge  would  be  the 
same  with  the  real  discharge,  is  equal  to  half  the  sum  of  the  greatest  and  least  velocities,  as  computer 
in  the  last  proposition. 

The  mean  velocity  is,  therefore,  =v  — s/  v -f-  (B.) 

This  is  also  proved  by  the  experiments  of  Du  Buat. 

When  the  water  in  a river  receives  a permanent  increase,  the  depth  and  the  velocity,  as  in  the  ex 
ample  above,  are  the  first  things  that  are  augmented.  The  increase  of  the  velocity  increases  the  action 
on  the  sides  and  bottom,  in  consequence  of  which  the  width  is  augmented,  and  sometimes  also,  but 
more  rarely,  the  depth.  The  velocity  is  thus  diminished,  till  the  tenacity  of  the  soil,  or  the  hardness  of 
the  rock,  afford  a sufficient  resistance  to  the  force  of  the  water.  The  bed  of  the  river  then  changes  only 
by  insensible  degrees,  and,  in  the  ordinary  language  of  hydraulics,  is  said  to  be  permanent,  though  in 
strictness  this  epithet  is  not  applicable  to  the  course  of  any  river. 

When  the  sections  of  a river  vary,  the  quantity  of  water  remaining  the  same,  the  mean  velocities  are 
inversely  as  the  areas  of  the  sections. 

This  must  happen,  in  order  to  preserve  the  same  quantity  of  discharge. 

The  following  table,  abridged  from  Du  Buat,  serves  at  once  to  compare  the  surface,  bottom,  and 
mean  velocities  in  rivers,  according  to  the  formulte  (A)  and  (B). 


VELOCITY  IN  INCHES. 

VELOCITY  IN  INCHES. 

Surface. 

Bottom. 

Mean. 

Surface. 

Bottom. 

Mean. 

4 

i- 

2-5 

56 

42-016 

49-008 

8 

3-342 

5-67 

60 

45-509 

52-754 

12 

6-071 

9-036 

64 

49- 

56'5 

16 

9- 

12-5 

68 

52-505 

60-252 

20 

12-055 

16-027 

72 

66-025 

64-012 

24 

15194 

19'597 

76 

59-568 

67-7S4 

28 

18421 

23-210 

80 

63-107 

71-553 

32 

21-678 

26-839 

84 

66-651 

75-325 

36 

25- 

30-5 

88 

70-224 

79-112 

40 

28-345 

34-172 

92 

73-788 

82-894 

44 

31-742 

37-871 

96 

77-370 

86‘685 

48 

35-151 

41-570 

100 

81- 

905 

52 

38-564 

45-282 

The  knowledge  of  the  velocity  at  the  bottom  is  of  the  greatest  use  for  enabling  us  to  judge  of  tne 
action  of  the  stream  on  its  bed. 

Every  kind  of  soil  has  a certain  velocity  consistent  with  the  stability  of  the  channel.  A greater  ve- 
locity would  enable  the  waters  to  tear  it  up,  and  a smaller  velocity  would  permit  the  deposition  of 
more  movable  materials  from  above.  It  is  not  enough,  then,  for  (lie  stability  of  a river,  that  the  aceel- 


30 


HYDRODYNAMICS. 


erating  forces  are  so  adjusted  to  the  size  and  figure  of  its  channel  that  the  current  may  be  in  train : it 
must  also  be  in  equilibrio  with  the  tenacity  of  the  channel. 

<We  learn  from  the  observations  of  Du  Buat,  and  others,  that  a velocity  of  three  inches  per  second  at 
the  bottom  will  just  begin  to  work  upon  the  fine  clay  fit  for  pottery,  and  however  firm  and  compact  it 
may  be,  it  will  tear  it  up.  Yet  no  beds  are  more  stable  than  clay,  when  the  velocities  do  not  exceed 
this ; for  the  water  soon  takes  away  the  impalpable  particles  of  the  superficial  clay,  leaving  the  particles 
of  sand  sticking  by  their  lower  half  in  the  rest  of  the  clay,  which  they  now  protect,  making  a very  per 
manent  bottom,  if  the  stream  does  not  bring  down  gravel  or  coarse  sand,  which  will  rub  off  this  very 
thin  crust,  and  allow  another  layer  to  be  worn  off.  A velocity  of  six  inches  will  lift  fine  sand ; eight 
inches  will  lift  sand  as  coarse  as  linseed ; twelve  inches  will  sweep  along  fine  gravel ; twenty-four 
inches  will  roll  along  rounded  pebbles  an  inch  diameter ; and  it  requires  three  feet  per  second  at  the 
bottom  to  sweep  along  angular  stones  of  the  size  of  an  egg.  ( Robison  on  Rivers.) 

Eytelwein,  a German  mathematician,  has  devoted  much  time  to  inquiries  in  hy- 
drodynamics. His  formulae  apply  to  the  motion  of  water;  1st,  in  a cylindric 
tube ; 2d,  in  an  open  canal. 

Let  d be  the  diameter  of  the  cylindric  tube  E F,  h the  total  height  F G of  the 
head  of  water  in  the  reservoir  above  the  middle  of  the  orifice  F,  and  l the  length 
E F of  the  tube,  all  in  inches;  then  the  velocity  in  inches  with  which  the  fluid  will 
issue  from  the  orifice  F will  be 

/ 57  li  d 

v = 23J  v'  Z-t-57  d' 

this  multiplied  into  the  area  of  the  orifice  will  giye  the  quantity  per  second. 

Let  d = diameter  of  the  pipe  in  inches,  Q = the  quantity  of  water  in  cubic  feet  discharged  through 
the  pipe  per  minute,  l = the  length  of  the  pipe  in  feet,  and  h = the  difference  of  level  between  the 
surface  of  the  water  in  the  reservoir  and  at  the  end  of  the  pipe  or  the  head ; then,  any  three  of  these 
Quantities  being  given,  the  fourth  may  be  determined  from  the  following  formulae: — 


l 


i=5 
Q = \/ 


•0448  Q2  (l  -f  4-2  d 
h 

hd' ‘ 

•0448  (l  + 4-2  d) 


h d5  . , -0448  Q"  ( l + 4-2  d) 

— — 42  d h = t 

•0448  Qa  d5 


These  formulas  are  more  convenient  expressed  logarithmically,  thus — 

Log.  d = i {2  log.  Q + 2-6515  + log.  (I  + 4’2  d)  — log.  h } . 

Log.  Q = 4 {log.  h + 5 log.  d — 2-6515  — log.  ( l + 4“2  d)\. 

Log.  I = log.  li  -f-  log.  d — 2-6515  — 2 log.  Q (neglecting  — 4'2  d). 

Log.  h = 2 log.  Q -j-  2-6515  + log.  (/  + 4'2  d)  — 5 log.  d. 

When  a pipe  is  bent  in  one  or  more  places,  then  if  the  squares  of  the  sines  of  the  several  changes  oj 
direction  be  added  into  one  sum  s,  the  velocity  v will  be  found  by  the  formula 


* 


548  d h 
hl+^ds 


l,  h,  d,  and  v,  being  all  in  inches. 

Prouy  gives  a very  safe  formula  for  calculating  the  velocity  of  water  in  pipes,  and  it  is  very  conve- 
nient for  use,  and  is  reliable. 

Y = velocity  in  feet  per  second. 

D = diameter  of  pipe  in  feet. 

H = the  head,  from  surface  of  water  in  reservoir  to  the  surface  of  water  above  the  mouth  of  pipe. 

L = the  length  of  pipe. 


S = - . Then  V = 48  5254  ,/D  S.  The  measures  are  all  in  feet. 

L 

For  open  canals. — Let  v be  the  mean  velocity  of  the  current  in  feet,  a area  of  the  vertical  section  of 
the  stream,  p perimeter  of  the  section,  or  sum  of  the  bottom  and  two  sides,  l length  of  the  bed  of  the 
canal  corresponding  to  the  fall  h,  all  in  feet : then 

v = * / 9582  — , + 0-0111  — 0-109. 

V pi 

The  experiments  of  M.  Bidone,  on  the  motion  of  water  in  canals,  agree  within  the  80th  part  of  the 
•esults  of  computations  from  the  preceding  formulae. 

We  have  used  the  following  formula  of  Eytelwein,  taken  from  the  Edinburgh  Encyclopedia,  article 
Hydrodynamics , for  ascertaining  the  velocity  of  water  in  an  open  canal,  and  the  results  have  been  satis- 
factory. 

d ==  hydraulic  mean  depth , or  mean  radius  in  inches,  called  R in  preceding  formulae  of  Du  Buat 

f = fall  in  two  mile  of  canal,  in  inches. 

V = velocity  in  inches  per  second. 

Then,  V = 0-91  JJd. 


HYDRODYNAMICS. 


81 


For  apertures  in  the  sides  or  bottom  of  vessels. — If  q equal  the  quantity  of  water  discharged  in  cubic 
feet  per  minute,  v the  velocity  of  the  affluent  water  in  feet  per  second  through  the  aperture,  a the  area 
of  the  aperture  in  square  inches,  and  h the  height  from  its  centre  to  the  surface  of  the  water,  we  have 

v = cifh  ; and  q = -4167  a c\fh  ; 

in  which  c is  a constant  quantity,  depending  upon  the  nature  of  the  aperture,  and  the  value  of  which, 
for  several  different  forms,  is  contained  in  the  following  table : — 


Nature  of  the  Orifices  employed. 

Ratio  between  the 
theoretical  and  real 
discharges. 

Coefficients  for 
finding  the  velo- 
cities in  Eng.  ft. 

For  the  whole  velocity  due  to  the  height 

1 to  1-00 

8-04 

For  wide  openings  whose  bottom  is  on  a level  with  that  of  1 

1 to  0'9C1 

7-7 

the  reservoir j 

For  sluices  with  walls  in  a line  with  the  orifice 

1 to  0-961 

7-7 

For  bridges  with  pointed  piers  

1 to  0-961 

7-7 

For  narrow  openings  whose  bottom  is  on  a level  with  that  of  / 

1 to  0-861 

6-9 

the  reservoir \ 

For  smaller  openings  in  a sluice  with  side  walls 

1 to  0-861 

6-9 

For  abrupt  projections  and  square  piers  of  bridges 

1 to  0-861 

6-9 

For  openings  in  sluices  without  side  walls 

1 to  0'635 

5*1 

For  an  orifice  in  a thin  plate  

1 to  0-621 

5-0 

The  following  table  of  Smeaton  is  mainly  the  result  of  experiments. 

Table,  abridged  from  one  by  Mr.  Smeaton , for  showing  the  height  of  head  necessary  to  overcome 
the  friction  of  water  in  horizontal  pipes. 

I i 

Velocities  per  second  of  water  in  the  pipes. 


Ft. 

0 

in. 

6 

Ft.  in. 
1 0 

Ft.  in. 
1 0 

Ft.  in. 
2 0 

Ft 

in. 

6 

Ft. 

3 

in. 

0 

Ft. 

3 

in. 

G 

Ft. 

4 

in. 

0 

Ft. 

4 

in. 

*0 

Ft. 

5 

in. 

0 

pipes. 

0 

4-5 

1 

4-7 

o 

110 

4 

9-7 

7 

1-7 

10 

1-0 

13 

8-0 

17 

100 

22 

G-7 

28 

0-2 

£ inch. 

0 

3(1 

0 

11-1 

T 

11-3 

3 

25 

4 

92 

G 

80 

9 

1-3 

n 

10-6 

Is 

0-5 

18 

8-1 

# “ 

0 

2*o 

0 

8-4 

i 

5-5 

2 

4-9 

3 

69 

5 

0-5 

6 

10-0 

8 

11  0 

11 

3-4 

14 

o-o 

1 “ 

0 

1*8 

0 

0-7 

i 

2-0 

i 

1 1-1 

2 

10-3 

4 

0-4 

5 

5*6 

7 

to 

9 

0-3 

11 

2-5 

' H 

() 

1-5 

0 

5'6 

0 

11-7 

1 

7>2 

2 

4-6 

3 

43 

4 

0-7 

5 

1 1-3 

7 

G-2 

9 

4-1 

H “ 

0 

J*3 

0 

4*8 

0 

10-0 

i 

4-5 

2 

05 

2 

100 

3 

10-9 

5 

M 

G 

5-4 

8 

o-i 

1-3-  “ 

0 

it 

0 

4-2 

0 

8-7 

i 

24 

i 

9 4 

o 

6-2 

3 

5-0 

4 

55 

5 

7’7 

7 

o-o 

2 

0 

1-0 

0 

3-7 

0 

7-8 

i 

0-8 

i 

7 0 

2 

2-9 

3 

04 

3 

110 

5 

0-1 

G 

2-7 

21  “ 

0 

0-9 

0 

3-3 

0 

7-0 

0 

11-5 

1 

51 

o 

02 

o 

8-8 

3 

G-8 

4 

G1 

5 

7-2 

2i  u 

0 

0-7 

0 

2-8 

0 

50 

0 

9-G 

1 

2-3 

I 

8-2 

o 

3-3 

2 

11-7 

3 

91 

4 

8-0 

3 “ 

0 

0*6 

0 

2-4 

0 

5-0 

0 

8-2 

t 

0-2 

i 

5-3 

I 

11-4 

2 

G-6 

3 

2-7 

4 

00 

3i  “ 

0 

O-Ii 

0 

2-1 

0 

4-4 

0 

7*2 

0 

10-7 

i 

31 

l 

8-5 

2 

2-7 

2 

9-8 

3 

GO 

4 “• 

0 

0*5 

0 

1-9 

0 

39 

0 

6-4 

0 

9-5 

i 

1-4 

l 

G-2 

i 

11-8 

2 

G1 

3 

1-4 

41 

0 

04 

0 

1-7 

0 

3-5 

0 

5-8 

0 

8 0 

i 

o-i 

l 

4-4 

i 

9-4 

o 

3-1 

2 

9-G 

5 u . 

0 

0*4 

0 

1 4 

0 

2-9 

0 

4-8 

0 

71 

0 

10-1 

l 

1-7 

i 

5 8 

I 

10-6 

2 

4-0 

G 

0 

0-3 

0 

1-2 

0 

25 

0 

4-1 

0 

o-t 

0 

8-6 

0 

11-7 

1 

3-3 

i 

7-3 

o 

o-o 

7 u 

0 

0*3 

0 

l-o 

0 

2'2 

0 

30 

0 

54 

0 

7-0 

0 

10-2 

1 

1-4 

i 

4-9 

i 

90 

8 “ 

0 

0 25 

0 

0-9 

0 

1-9 

0 

3-2 

0 

4-8 

0 

6*7 

0 

9*1 

0 

11-9 

i 

3-0 

i 

6-7 

9 “ 

0 

0-2 

0 

0-8 

0 

1-7 

0 

2-9 

0 

4-3 

0 

6*0 

0 

8-2 

0 

10-7 

i 

1*5 

i 

4-8 

10  “ 

() 

0-2 

0 

0 8 

0 

1-6 

0 

2-6 

o 

3*9 

0 

5*5 

0 

7-5 

0 

9-7 

l 

0-3 

i 

3-3 

11  “ 

0 

019 

0 

07 

0 

1-5 

0 

2-4 

0 

3-G 

0 

5*0 

0 

G-8 

0 

8-9 

0 

11-3 

i 

2-0 

12  “ 

Look  for  the  velocity  of  water  in  the  pipe  in  the  upper  row,  and  in  the  column  below  it,  and  opposite 
to  the  given  diameter  of  the  pipe  standing  in  the  last  column,  will  be  found  the  perpendicular  height  of 
a column  or  head,  in  feet,  inches,  and  tenths,  requisite  to  overcome  the  friction  of  such  pipe  for  100  feet 
in  length,  and  obtain  the  given  velocity. 

From  the  present  standard  work,  Lowell  Hydraulic  Experiments,  by  Jas.  B.  Francis,  Esq.,  we  extract 
the  following  on  weirs : 

The  formula  proposed  for  weirs  of  considerable  length  in  proportion  to  the  depth  upon  them,  and  hav- 
ing complete  contraction,  (as  first  suggested  to  the  author  by  Mr.  Boyden  in  1846,)  is 

Q = C {l— bn  h)  h*  ; 

m which 

Q = the  quantity  discharged  in  cubic  feet  per  second. 

C — a constant  coefficient. 

I = the  total  length  of  the  weir  in  feet. 
b = a constant  coefficient. 

n = the  number  of  end  contractions.  In  a single  weir  having  complete  contraction,  n always 
equals  2,  and  when  the  length  of  the  weir  is  equal  to  the  width  of  the  canal  leading  to 
it,  n — 0. 

h = the  depth  of  water  flowing  over  the  weir,  taken  far  enough  upstream  from  the  weir,  to  be  un- 
affected by  the  curvature  in  the  surface  caused  by  the  discharge. 
a — a constant  power. 


32 


HYDRODYNAMICS. 


By  experiments  the  numerical  values  were  determined  as  follows: 

Q = 3.33  (A  — 0.1  nH)H^: 
the  English  foot  being  the  unit  of  measure. ' 

This  formula  is  only  applicable  to  rectangular  weirs,  made  in  the  side  of  a dam,  which  is  vertical  on 
the  upstream  side,  the  crest  of  the  weir  being  horizontal,  and  the  ends  vertical ; also,  the  edges  of  the 
orifice  presented  to  the  current  must  be  sharp ; for,  if  bevelled  or  rounded  off  in  any  perceptible  degree, 
a material  effect  will  be  produced  on  the  discharge  ; it  is  essential,  moreover,  that  the  stream  should 
touch  the  orifice  only  at  these  edges,  after  passing  which  it  should  be  discharged  through  the  air,  in  the 
same  manner  as  if  the  orifice  was  cut  in  a thin  plate.  The  formula  is  not  applicable  to  cases  in  which 
the  depth  on  the  weir  exceeds  one  third  of  the  length  ; nor  to  very  small  depths.  There  seems  ijo  rea- 
son why  it  should  not  be  applied  with  safety  to  any  depths  between  6 inches  and  24  inches. 

The  height  of  the  surface  of  the  water  in  the  canal,  above  the  crest  of  the  weir,  is  to  be  taken  for  the 
depth  upon  the  weir ; this  height  should  be  taken  at  a point  far  enough  from  the  weir  to  be  unaffected 
by  the  curvature  caused  by  the  discharge ; if  more  convenient,  it  may  be  taken  by  means  of  a pipe 
opening  near  the  bottom  of  the  canal  near  the  upstream  side  of  the  weir,  which  pipe  may  be  made  to 
communicate  with  a box  placed  in  any  convenient  situation  ; and  if  the  box  and  pipe  do  not  leak,  the 
height  may  be  observed  in  this  manner,  very  correctly.  However  the  depth  may  be  observed,  it  may 
require  to  be  corrected  for  the  velocity  of  the  water  approaching  the  weir. 

The  end  contraction  must  either  be  complete,  or  entirely  suppressed ; the  necessary  distance  from  the 
6ide  of  the  canal  or  reservoir  to  the  end  of  the  weir,  in  order  that  the  end  contraction  may  be  complete, 
is  not  definitely  determined.  In  cases  where  there  is  end  contraction,  we  may  assume  a distance  from 
the  side  of  the  canal  to  the  end  of  the  weir  equal  to  the  depth  on  the  weir,  as  the  least  admissible,  in 
order  that  the  proposed  formula  may  apply. 

As  to  the  fall  below  the  weir,  requisite  to  give  a free  discharge  to  the  water,  it  is  not  definitely  deter- 
mined ; it  appears  that  when  the  sheet,  passing  the  weir,  falls  into  water  of  considerable  depth,  the 
depth  on  the  weir  being  about  0.85  feet,  no  difference  is  perceptible  in  the  discharge,  whether  the  water 
is  1.05  feet  or  0.235  feet  below  the  crest  of  the  weir;  it  is  very  essential,  however,  in  all  cases,  that  the 
air  under  the  sheet  should  have  free  communication  with  the  external  atmosphere.  With  this  precau- 
tion it  appears  that,  if  the  fall  below  the  crest  of  the  weir  is  not  less  than  half  the  depth  upon  the  weir, 
the  discharge  over  the  weir  will  not  be  perceptibly  obstructed.  If  the  sheet  is  of  very  great  length, 
however,  more  fall  will  be  necessary,  unless  some  special  arrangement  is  made  to  supply  air  to  the  space 
under  the  sheet  at  the  places  that  would  otherwise  not  have  a free  communication  with  the  atmosphere. 

In  respect  to  the  depth  of  the  canal  leading  to  the  weir,  experiments  show  that,  with  a depth  as 
small  as  three  times  that  on  the  weir,  the  proposed  formula  agrees  with  experiment,  within  less  than  one 
per  cent. ; this  proportion  may  be  taken  as  the  least  admissible,  when  an  accurate  gauging  is  required. 

It  not  unfrequently  happens  that,  in  consequence  of  the  particular  form  of  the  canal  leading  to  the 
weir,  or  from  other  causes,  the  velocity  of  the  water  in  the  canal  is  not  uniform  in  all  parts  of  the  sec- 
tion ; this  is  a frequent  cause  of  serious  error,  and  is  often  entirely  overlooked.  If  great  irregularities 
exist,  they  should  be  removed  by  causing  the  wafer  to  pass  through  one  or  more  gratings,  presenting 
numerous  small  apertures  equally  distributed,  or  otherwise,  as  the  case  may  require,  through  which  the 
water  may  pass  under  a small  head ; these  gratings  should  be  placed  as  far  from  the  weir  as  practi- 
cable. 

If  the  canal  leading  to  the  weir  has  a suitable  depth,  it  will  be  requisite  only  when  great  precision  is 
required,  to  correct  the  depth  upon  the  weir  for  the  velocity  of  the  water  in  the  canal  bv  the  formula 
(D). 

li  being  the  head  due  to  the  velocity  with  which  the  water  approaches  the  weir : — 

II'  .=  — 

Substituting  IT  for  II  in  the  previous  formula,  we  obtain  the  flow  increased  for  the  velocity  with  which 
the  water  approaches  the  weir. 

Of  gauging  the  flow  of  water  in  open  canals  of  uniform  rectangular  section. — It  has  been  frequently 
found  convenient  at  Lowell,  to  gauge  large  streams  of  water  by  causing  them  to  flow  through  short  rec- 
tangular canals  of  uniform  section,  and  a particular  method  of  obtaining  the  mean  velocity  has  been 
practised,  which  will  now  be  dec  ’ribed. 

A convenient  part  of  the  feeding  canal  is  selected  and  lined  with  timbers  and  planks,  so  as  to  make  a 
smooth  and  uniform  rectangular  channel;  this  is  called  a flume.  The  mean  velocity  is  obtained  by 
means  of  tubes,  loaded  at  one  end,  so  that  they  may  float  in  nearly  a perpendicular  position,  the  lower 
ends  just  clearing  the  bottom  of  the  flume ; these  tubes  are  put  in  near  the  upper  end  of  the  flume,  and 
from  the  observed  paths  and  velocities  that  they  assume  through  a defined  portion  of  the  length  of  the 
flume,  a mean  velocity  is  deduced.  The  times  of  the  transits  are  observed  by  the  same  chronometer, 
the  signals  being  made  by  an  electric  telegraph  erected  for  the  purpose.  The  telegraph  used  for  this 
purpose  is  a very  simple  apparatus ; the  circuit  is  formed  by  an  insulated  copper  wire,  about  ^ of  an 
inch  in  diameter,  and  the  electric  current  is  maintained  by  a small  galvanic  battery.  "Whenever  the  cir- 
cuit is  broken,  a small  electro-magnet  becomes  demagnetized,  which  causes  a slight  blow  to  be  struck 
on  a vertical  glass  plate,  placed  near  the  observer,  who  notes  the  times  of  the  transits.  The  tubes  are 
cylinders,  made  of  tinned  plate,  about  two  inches  in  diameter,  and  of  a length  usually  a little  exceeding 
the  depth  of  the  water  in  the  flume  By  a comparison  of  the  results  obtained  by  gauging,  by  the  floats 
and  by  weir,  the  error  in  assuming  the  average  velocity  of  the  floats  for  that  of  the  stream,  was  found 
to  be  correct  within  a trifling  per  centage. 


HYDRO-ELECTRICAL  MACHINE. 


33 


Contrivances  to  measure  the  velocity  of  running  waters. — For  these  purposes,  various  contrivances 
have  been  proposed,  of  which  two  or  three  may  be  here  described. 

Suppose  it  be  the  velocity  of  the  water  in  a river  that  is  required;  or,  indeed,  both  the  velocity  and 
the  quantity  which  flows  down  it  in  a given  time.  Observe  a place  where  the  banks  of  the  river  are 
steej)  and  nearly  parallel,  so  as  to  make  a kind  of  trough  for  the  water  to  run  through,  and  by  taking 
the  depth  at  various  places  in  crossing  make  a true  section  of  the  river.  Stretch  a string  at  right  angles 
over  it,  and  at  a small  distance  another  parallel  to  the  first.  Then  take  an  apple,  an  orange,  or  other 
small  ball,  just  so  much  lighter  than  water  as  to  swim  in  it,  or  a pint  or  quart  bottle  partly  filled  with 
water,  and  throw  it  into  the  water  above  the  strings.  Observe  when  it  comes  under  the  first  string,  by 
means  of  a quarter  second  pendulum,  a stop-watch,  or  any  other  proper  instrument ; and  observe  like- 
wise when  it  arrives  at  the  second  string.  By  this  means  the  velocity  of  the  upper  surface  will  be 
obtained.  And  the  section  of  the  river  at  the  second  string  must  be  ascertained  by  taking  various 
depths,  as  before.  If  this  section  be  the  same  as  the  former,  it  may  be  taken  for  the  mean  section : if 
not,  add  both  together,  and  take  half  the  sum  for  the  mean  section.  Then  the  area  of  the  mean  section 
in  square  feet  being  multiplied  by  the  distance  between  the  strings  in  feet,  will  give  the  contents  of  the 
water  in  solid  feet,  which  passed  from  one  string  to  the  other  during  the  time  of  observation ; and  this 
by  the  rule  of  three  may  be  adapted  to  any  other  portion  of  time.  The  operation  may  often  be  greatly 
abridged  by  taking  notice  of  the  arrival  of  the  floating  body  opposite  two  stations  on  the  shore,  espe- 
cially when  it  is  not  convenient  to  stretch  a string  across. 

M.  Pitot  invented  a stream  measurer  of  a simple  construction,  by  means  of  which  the  velocity  of  any 
part  of  a stream  may  readily  be  found.  This  instrument  is  composed  of  two  long  tubes  of  glass  open 
at  both  ends:  one  of  these  tubes  is  cylindrical  throughout;  the  other  has  one  of  its  extremities  bent 
into  nearly  a right  angle,  and  gradually  enlarges  like  a funnel,  or  the  mouth  of  a trumpet : these  tubes 
are  both  fixed  in  grooves  in  a triangular  prism  of  wood ; so  that  their  lower  extremities  are  both  on  the 
same  level,  standing  thus  one  by  the  side  of  the  other,  and  tolerably  well  preserved  from  accidents. 
The  fl  ame  in  which  these  tubes  stand  is  graduated,  close  by  the  side  of  them,  into  divisions  of  inches 
and  lines. 

To  use  this  instrument,  plunge  it  perpendicularly  into  the  water,  in  such  manner  that  the  opening  of 
the  funnel  at  the  bottom  of  one  of  the  tubes  shall  be  completely  opposed  to  the  direction  of  the  cur- 
rent, and  the  water  pass  freely  through  the  funnel  up  into  the  tube.  Then  observe  to  what  height  the 
water  rises  in  each  tube,  and  note  the  difference  of  the  sides ; for  this  difference  will  be  the  height  due 
to  the  velocity  of  the  stream.  It  is  manifest,  that  the  water  in  the  cylindrical  tube  will  be  raised  to  the 
same  height  as  the  surface  of  the  stream,  by  the  hydrostatic  pressure : while  the  water  entering  from 
the  current  by  the  funnel  into  the  other  tube,  will  be  compelled  to  rise  above  that  surface  by  a space 
at  which  it  will  be  sustained  by  the  impulse  of  the  moving  fluid  : that  is,  the  momentum  of  the  stream 
will  be  in  equilibrio  with  the  column  of  water  sustained  in  one  tube  above  the  surface' of  that  in  the 
other.  In  estimating  the  velocity  by  means  of  this  instrument,  we  must  have  recourse  to  theory  as 
corrected  by  experiments.  Thus,  if  h,  the  height  of  the  column  sustained  by  the  stream,  or  the  differ- 
ence of  heights  in  the  two  tubes,  be  in  feet,  we  shall  have  v = 6‘5  f h,  nearly,  the  velocity,  per  second, 
of  the  stream ; if  h be  in  inches,  then  v = 22'47  -f  h,  nearly : or  further  experiments  made  with  the 
instrument  itself  may  a little  modify  these  coefficients. 

Note.  In  an  example  like  this,  it  is  a good  approximation,  to  multiply  continually  together,  the  area 
of  the  orifice,  the  number  336,  (336  = 5'6  X 66,)  and  the  square  root  of  the  dej)th  in  feet  of  the  middle 
of  the  orifice. 

Thus,  in  the  preceding  example,  it  will  be  4 X i X 336  X x/4'25  = j X 336  X 2 062  = 173'2  cubic 
feet. 

The  less  the  height  of  the  orifice  compared  with  its  depth  under  the  water,  the  nearer  will  the  result 
thus  obtained  approach  to  the  truth.  If  the  height  of  the  orifice  be  such  as  to  require  consideration,  the 
principle  of  Art.  6,  page  17,  may  be  blended  with  this  rule. 

Thus,  applying  this  rule  to  Ex.  2,  we  shall  have  area  X %/  depth  X 336  X | = 9 X 3 X 224  = 6048, 
for  the  cubic  feet  discharged.  This  is  less  than  the  former  result  by  about  its  900th  part.  It  is,  there- 
fore, a good  approximation,  considering  its  simplicity : it  may,  in  many  cases,  supersede  the  necessity  of 
recurrence  to  tables. 

HYDRO-ELECTRICAL  MACHINE.  The  production  of  electricity  by  the  passage  of  steam  through 
a small  jet,  was  unknown  till  1840.  It  is  now  generally  concluded  that  it  is  the  effect  of  the  friction 
of  globules  of  water  against  the  sides  of  the  opening,  urged  forward  by  the  rapid  passage  of  the 
steam  ; the  effect  of  this  is  to  render  the  steam  or  water  positive,  and  the  pipes  from  which  it  issues 
negative. 

Fig.  2275  represents  this  machine,  as  manufactured  by  Benjamin  Pike,  Jr.,  of  294  Broadway,  New 
York,  in  which  A A,  die.,  are  six  green  glass  supports,  three  feet  long ; B is  a cylindrical  tubular  boiler 
of  rolled  iron-plate,  § inch  thick  ; its  extreme  length  is  seven  feet  six  inches,  one  foot  of  which  is  occu- 
pied by  the  smoke-chamber,  making  the  actual  length  of  the  boiler  six  and  a half  feet ; its  diameter 
three  and  a half  feet.  The  furnace  D and  ash-hole  C are  contained  within  the  boiler,  and  are  furnished 
with  a metal  screen  to  be  applied  for  the  purpose  of  excluding  the  light  during  the  progress  of  one 
class  of  experiments;  F is  the  water-gage;  E the  feed-valve;  JJ  are  two  tubes  leading  from  the 
valves  K K to  the  two  tubes  H ; A and  I are  forty-six  bent  iron  tubes,  terminating  in  jets,  either  half  or 
the  whole  of  which  may  be  opened  by  means  of  the  lever  G G ; L is  a valve  for  liberating  steam  during 
the  existence  of  the  maximum  pressure ; M is  the  safety-valve ; N is  a cap  covering  a jet,  that  is  em- 
ployed for  illustrating  a certain  mechanical  action  of  a jet  of  steam ; O is  the  first  portion  of  the  funnel ; 
P the  second  portion,  which  slides  into  itself  by  a telescope  joint,  so  that  the  boiler  may  be  insulated 
when  the  experiments  commence.  The  boiler  is  cased  in  wood. 

Fig.  227  6,  which  may  be  called  the  prime  conductor,  but  which  is  not  used  for  the  purpose,  is  a zinc 
case,  furnished  with  four  rows  of  points.  It  is  placed  in  front  of  the  jets,  in  order  to  collect  the  elec 
Vol.  II.— 3 


34 


HYDRO-EXTRACTOR. 


tricity  from  the  ejected  vapor,  and  thus  prevent  its  returning  to  restore  the  equilibrium  of  the  boiler 
The  maximum  pressure  at  the  commencement  of  the  experiments  is  80  pounds,  which  gradually  gets 
reduced  to  40  pounds,  or  lower.  The  portion  of  the  apparatus  which  is  peculiarly  connected  with  the 
generation  of  the  electricity,  is  a series  of  bent  tubes  with  their  attached  jets.  Each  jet  consists  of  a brass 
socket,  containing  a cylindrical  piece  of  partridge-wood,  with  a circular  hole  or  passage  through  it,  £ of 
an  inch  in  diameter,  into  which  the  steam  is  admitted  through  an  aperture.  The  peculiar  shape  of  this 
aperture  appears  to  derive  its  efficacy  from  the  tendency  it  gives  the  steam  to  spread  out  in  the  form 
of  a cup,  on  entering  the  wooden  pipe,  and  by  that  means  to  bring  it  and  the  particles  of  water  of 
which  it  is  the  carrier,  into  very  forcible  collision  with  the  rubbing  surface  of  the  wood. 


The  electricitj'  produced  by  this  engine  is  not  so  remarkable  for  its  high  intensity,  as  for  its  enormous 
quantity.  In  no  case,  antecedent  to  this,  has  the  electricity  of  tension  taken  so  rapid  a stride  towards 
assimilating  with  galvanic  electricity.  Mr.  Faraday’s  experiments  on  the  identity  of  the  electricities  had 
shown  how  small  was  the  quantity  obtained  from  the  best  machines ; and  had  given  good  reason  to 
expect  that  chemical  effects  would  be  exalted  when  the  quantity  could  be  increased.  And  such  is  the 
case  here  ; a very  remarkable  experiment  in  illustration  of  this  is,  that  not  only  is  gunpowder  ignited 
by  the  passage  of  the  spark,  but  even  paper  and  wood  shavings  will  be  inflamed  when  placed  in  the 
course  of  the  spark  passing  between  two  points — such  an  effect  was  never  before  produced  with 
common  electricity.  In  like  manner,  chemical  decompositions  are  effected  much  more  readily  by  means 
of  the  hydro-electric,  than  by  that  from  the  common  machine. 

HYDRO-EXTRACTOR.  An  apparatus 
for  removing  liquids  or  moisture  from  yarns  fi  2277. 

or  cloths  in  the  process  of  manufacture. 

The  main  feature  or  principle  of  the  machine 
is  extremely  simple,  consisting  merely  of  a 
circular  open  wire-basket,  in  which  the  wet 
cloths  are  placed  as  uniformly  as  possible, 
and  which  is  then  made  to  revolve  with  such 
rapidity  that  the  moisture  is  thrown  out 
by  the  centrifugal  force  through  the  inter- 
stices of  the  basket.  As  the  vis  inertias 
prevents  the  instant  communication  of  a 
sufficient  velocity  to  the  basket  loaded  with 
heavy  goods,  various  expedients  have  been 
resorted  to  to  make  communicated  velocity 
progressive.  The  contrivances  for  this  pur- 
pose, on  the  original  English  patent,  are  ex- 
tremely complicated;  but  the  arrangement 
shown  in  Fig.  2217,  (which  is  an  exterior 
view  of  the  machine  and  the  driving  appa- 
ratus,) is  much  more  simple,  and  perfectly 
effective.  It  is  the  invention  of  M.  C.  Bry- 
ant, of  Lowell,  Massachusetts.  The  whole 
machine  rests  on  two  square  bed-stones ; 
the  outside  of  the  case,  or  tub,  is  only  shown 
in  the  figure,  within  which  the  wire-basket, 
open  at  the  top  for  the  reception  of  the 
goods,  revolves  on  a vertical  shaft ; to  this 
shaft  motion  is  communicated  from  the 
horizontal  shaft  beneath  the  tub  by  means 
of  bevel-geers.  On  the  extremity  of  this 
horizontal  shaft  is  fixed  the  driving-pulley, 

'as  shown  in  the  figure.)  This  pulley  is  of 


vi'-v  Stone 
2C./V. 


HYDROMETER. 


oD 


the  form  usually  employed  on  small  tilt  or  trip  hammers ; a belt  passing  round  this  pulley,  and  contin 
ually  moving,  communicates  motion  to  the  pulley  ■whenever  a binder  brings  the  belt  in  close  contact 
with  its  periphery.  The  binder  is  attached  to  an  extremity  of  an  oscillating  frame,  suspended  from  the 
top  of  the  tub,  as  shown  in  the  figure.  The  binder  presses  against  the  belt  so  as  to  communicate  motion 
to  the  pulley.  To  stop  the  motion,  the  upper  end  of  the  oscillating  binder-frame  is  pressed  down  by  a 
handle;  the  binder  relieves  the  belt,  and  a rope  attached  to  the  periphery  of  a small  pulley  on  the 
binder-frame  passing  over  a pulley  fixed  on  the  horizontal  driving-shaft,  and  fastened  at  the  other  end 
to  the  bottom  of  the  tub,  acts  as  a friction-brake  to  retard  the  motion  of  the  shaft,  and  consequently  ot 
the  basket.  To  keep  the  binder-frame  in  extreme  positions  a movable  weight  is  placed  on  the  handle 
rod  at  the  top  of  the  frame,  which  slides  from  one  end  to  the  other  of  the  rod,  as  the  binder  is  raised  or 
depressed. 

The  basket  in  this  hydro-extractor  is  about  three  and  a half  feet  in  diameter;  and  in  full  action, 
should  make  about  800  revolutions  per  minute.  The  driving-belt  is  about  eight  inches  wide  ; the 
driving-pulley  eighteen  inches  diameter. 

This  machine  is  in  operation  at  the  Bay  State  Mills,  in  Lawrence,  and  at  the  carpet  mill  in  Lowell ; 
and  machines  similar  in  the  main  principle  are  employed  in  many  of  the  mills  in  this  country,  and 
give  complete  satisfaction. 

HYDROMETER.  An  instrument  for  determining  the  specific  gravities  of  liquids,  and  thence  the 
strength  of  spirituous  liquors  ; these  being  inversely  as  their  specific  gravities.  V arious  instruments  of 
different  forms  have  been  proposed  for  ascertaining  readily  the  specific  gravities  of  fluids,  but  only  two 
or  three  of  them  are  deserving  of  description. 

The  hydrometer  represented  in  Fig.  2278  consists  of  a hollow  glass  ball  B,  with  a smaller  ball  0 
appended  to  it,  and  which,  from  its  superior  weight,  serves  to  keep  the  instrument  in  a vertical  position, 
to  whatever  depth  it  may  be  immersed  in  a liquid.  From  the  large  ball  rises  a cylindrical  stem  a d,  on 
which  are  marked  divisions  into  equal  parts  ; and  the  depth  to  which  the  stem  will  sink  in  water,  or 
any  other  liquid  fixed  on  as  a standard  of  specific  gravity,  being  known,  the  depth  to  which  it  sinks  in  a 
liquid  whose  specific  gravity  is  required,  will  indicate,  by  the  scale,  how  much  greater  or  less  it  is  than 
that  of  the  standard  liquid. 

Those  most  celebrated  are  the  scales  of  Baume,  Cartier,  Twaddell,  and  Guy  Lussac.  Most  of  these 
scales  are  arbitrary,  and  formed  after  the  ideas  of  their  projectors,  but  having  no  particular  reference  by 
which  they  may  be  understood. 

The  centesimal  hydrometer,  by  Guy  Lussac,  is  an  exception,  the  extreme  points  22,  b. 

being  water  and  absolute  alcohol ; this  space  is  divided  into  one  hundred  parts, 
thus  showing  in  alcoholic  mixtures  the  per  rentage  of  alcohol  in  the  liquid.  They  1 

are  made  of  glass,  brass,  and  silver,  usually  from  six  to  ten  inches  long,  of  the  1 

form  represented  in  the  cut,  the  graduations  being  marked  on  the  stem. 


Table  showing  the  Comparative  Scales  of  Guy  Lussac  and  Baume,  with  the 
Specific  Gravities  and  Proof,  at  the  Temperature  of  60°. 


Guy  Lussac’s  Scale. 

Baum6’s  Scale. 

Specific  Gravity. 

Proof. 

100 

45 

796 

100' 

95 

40 

815 

92 

"o 

90 

85 

36 

33 

833 

848 

82 

72 

fep -3 
G 0 

s 

80 

31 

863 

62 

O s_ 

a 

. 75 

28 

876 

52 

s > 

| 

70 

26 

889 

42 

Pm  0 

P- 

65 

24 

901 

32 

o 

60 

23 

912 

22  4thpi;oof. 

<D 

tl) 

55 

21 

923 

12 

03 

50 

19 

933 

0 Proof. 

O 

45 

18 

942 

S') 

40 

17 

951 

18 

u , . 

<D 

35 

16 

958 

29 

►i>  8 

30 

15 

964 

35 

P-i 

25 

14 

970 

48  ) 

Explanation  of  Baume’s  scale. — Manufacturers  who  employ  BaumtS’s  hydrometer,  or  have  occasion 
to  know  the  value  of  the  degrees  on  his  scale,  may  find  the  following  formula  useful : — 

Let  B = Baum6’s  degrees,  and  100  = water.  Then 

144 

Specific  gravity  = 1j4_B' 

That  is  to  say,  144  divided  by  the  difference  between  144  and  the  given  degree  of  Baume,  is  the  specific 
gravity  in  question,  stated  in  reference  to  water  assumed  = 100.  Thus,  suppose  Baume  = 66°.  Then 

144  144  • 

- — — or  — — = 1-846  = specific  gravitv. 

144—  66  78  1 ° 


Specific  gravity 


86 


HYDROSTATIC  PRESS. 


Scale  of  Specific  Gravities  indicated  by  Twaddell’ s Scale. 


Twaddell. 

Sp.  Gr. 

Twaddell. 

Sp.  Gr. 

Twaddell. 

Sp.  Gr. 

Twaddell. 

Sp.  Gr. 

0 

....1000 

50 

....1250 

100 

....1500 

150 

....1750 

10 

60 

110 

160 

....1800 

20 

....1100 

70 

....1350 

120 

....1600 

170 

....1850 

80 

....1150 

80 

....1400 

130 

....1650 

180 

....1900 

40 

....1200 

90 

140 

....1700 

190 

....1950 

Hydrometer  with  weights. — There  is  a variety  of  kinds  of  hydrometers,  with  weights ; the  principal 
ones  are  Diea’s  and  Sikes's.  They  are  used  for  ascertaining  the  strength  of  spirituous  liquors. 

Another  easy  method  of  determining  the  densities  of  different  liquids,  frequently  practised,  is  by  means 
of  a set  of  glass  beads  previously  adjusted  and  numbered.  Thrown  into  any  liquid,  the  heavier  balls 
sink  and  the  lighter  float  at  the  surface  ; but  one  of  them  approaching  the  density  of  the  liquid  will  be 
in  a state  of  indifference  as  to  buoyancy,  or  will  float  under  the  surface.  The  number  on  this  ball  indi- 
cates, in  thousandth  parts,  the  specific  density  of  the  liquid. 

HYDROSTATIC  PRESS.  If  there  be  any  number  of  pistons  of  different  magnitudes,  any  how 
applied  to  apertures  in  a cylindrical  vessel  filled  with  an  incompressible  and  non-elastic  fluid,  the 
forces  acting  on  the  pistons  to  maintain  an  equilibrium,  will  be  to  one  another  as  the  areas  of  the 
respective  apertures,  or  the  squares  of  the  diameters  of  the  pistons. 

Let  A B C D represent  a section  passing  along  the  axis  of  a cylindrical  vessel  filled 
with  an  incompressible  and  non-elastic  fluid,  and  let  E F be  two  pistons  of  different  mag- 
nitudes, connected  with  the  cylinder  and  closely  fitted  to  their  respective  apertures  or 
orifices ; the  piston  F being  applied  to  the  aperture  in  the  side  of  the  vessel,  and  the  pis- 
ton E occupying  an  entire  section  of  the  cylinder  or  vessel,  by  which  the  fluid  is  con- 
tained. 

Then,  because  by  the  nature  of  fluidity,  the  pressures  on  every  part  of  the  pistons  E and  F,  are 
mutually  transmitted  to  each  other  through  the  medium  of  the  intervening  fluid  ; it  follows  that  these 
pressures  will  be  in  a state  of  equilibrium  when  they  are  equal  among  themselves. 

Now,  it  is  manifest,  that  the  sum  of  the  pressures  propagated  by  the  piston  E,  is  proportional  to  the 
area  of  a transverse  section  of  the  cylinder ; and  in  like  manner  the  sum  of  the  pressures  propagated  by 
the  piston  F is  proportional  to  the  area  of  the  aperture  which  it  occupies ; consequently,  an  equilibrium 
must  obtain  between  these  pressures  when  the  forces  on  the  pistons  are  to  one  another,  respectively, 
as  the  areas  of  the  apertures  or  spaces  which  they  occupy. 

Hence  it  appears,  that  by  taking  the  areas  of  the  pistons  E and  F,  in  a proper  ratio  to  one  another, 
we  can,  by  means  of  an  incompressible  fluid,  produce  an  enormous  compression,  and  that  too  by  the 
application  of  a very  small  force. 

Put  P = the  force  or  pressure  on  the  piston  E, 

A = the  area  of  the  orifice  which  it  occupies, 
p = the  pressure  on  the  piston  F,  and 
a = the  area  of  the  orifice  or  space  to  which  it  is  fitted : 
then,  according  to  the  principle  announced  in  the  foregoing  proposition  and  demonstrated  above,  we 
shall  obtain 

a : A : : p : P. 

But  because,  by  the  principles  of  mensuration,  the  areas  of  different  circles  are  to  one  another  as  the 
squares  of  their  diameters ; if,  therefore,  we  substitute  d2  and  D2  respectively  for  a and  A in  the  above 
analogv,  we  shall  have 

<T- : D2 : : p : P ; 

and  from  this,  by  making  the  product  of  the  mean  terms  equal  to  the  product  of  the  extremes,  we  get 
the  general  equation, 

p D!  = P d2 ;A) 

This  is  the  principle  upon  which  depends  the  construction  and  use  of  that  very  powerful  instrument,  the 
Hydrostatic  Press , first  brought  into  notice  about  the  year  1196,  by  Joseph  Bramah,  Esq.,  of  London. 

The  improvement  introduced  by  Mr.  Bramah,  consisted  in  the  application  of  the  common  forcing- 
pump  to  the  injection  of  water,  or  some  other  incompressible  and  non-elastic  fluid,  into  a strong  metallic 
cylinder,  truly  bored  and  furnished  with  a movable  piston,  made  perfectly  water-tight  by  means  of 
leather  collars  or  packing,  neatly  fitted  into  the  cylinder. 

The  proportion  which  subsists  between  the  diameter  of  this  piston,  and  that  of  the  plunger  in  the 
forcing-pump,  constitutes  the  principal  element  by  which  the  power  of  the  instrument  is  calculated;  for, 
by  reason  of  the  equal  distribution  of  pressure  in  the  fluid,  in  proportion  as  the  area  of  the  transverse 
section  of  the  one  exceeds  the  area  of  a similar  section  of  the  other,  so  must  the  pressure  sustained  by 
the  one  exceed  that  sustained  by  the  other. 

Therefore,  if  the  piston  F,  in  the  preceding  diagram,  be  assimilated  to  the  plunger  in  the  barrel  of  a 
forcing-pump,  and  the  piston  E to  that  in  the  cylinder  of  the  hydrostatic  press  ; then,  the  equation  (A ) 
involves  every  particular  respecting  the  power  and  effects  of  the  engine. 

Example.  If  the  diameter  of  the  cylinder  is  5 inches,  and  that  of  the  forcing-pump  one  inch ; what 
is  the  pressure  on  the  piston  in  the  cylinder,  supposing  the  force  applied  on  the  plunger  or  smaller  pis- 
ton to  be  equivalent  to  150  lbs.  ? 

Here  we  have  given  D = 5 inches,  d — 1 inch,  and  p = 750  lbs. ; therefore,  by  substitution,  equation 
(A)  becomes 

PD2 

52  X 750  = P XI2;  that  is,  P = — = 18,750  lbs. 

a ■ 


HYDROSTATIC  PRESS. 


37 


Ride. — Multiply  the  square  of  the  diameter  of  the  cylinder  by  the  pressure  on  the  piston,  of  the  forc- 
ing pump,  and  divide  the  product  by  the  square  of  its  diameter,  and  the  quotient  will  express  the  in- 
tensity of  the  pressure  on  the  piston  of  the  cylinder. 

, _ P d2 

* jyi  ’ or,  in  words : — 

Rule. — Multiply  the  given  pressure  on  the  piston  of  the  cylinder  by  the  square  of  the  diameter  of  the 
forcing  pump,  and  divide  the  product  by  the  square  of  the  diameter  of  the  cylinder  for  the  power  re- 
quired. 

D = j/TT2. 

P 

Rule. — Multiply  the  pressure  on  the  piston  of  the  cylinder  by  the  square  of  the  diameter  of  the  forc- 
ing pump,  and  divide  the  product  by  the  force  with  which  the  plunger  descends ; then  the  square  root 
of  the  quotient  will  be  the  diameter  of  the  cylinder  sought. 

d=  V pD\ 

Rule.- — Multiply  the  force  with  which  the  plunger  descends  by  the  square  of  the  diameter  of  the  cylin- 
der and  divide  the  product  by  the  entire  pressure  on  the  piston ; then  extract  the  square  root  of  the 
quotient  for  the  diameter  of  the  forcing  pump. 

The  Hydrostatic  press  is  generally  furnished  with  an  indicator  or  safety-valve  for  measuring  the  inten- 
sity of  pressure,  which  maybe  easily  estimated  by  considering  the  diameter  of  the  valve,  and  the  pres- 
sure upon  it  as  the  plunger  of  the  forcing  pump,  and  using  previous  rules. 

To  determine  the  thickness  of  metal  in  the  cylinder  to  withstand  the  required  pressure. — The  amount 
of  force  which  tends  to  rupture  the  cylinder  along  the  curved  side,  that  is  to  divide  the  cylinder  in  halves 
lengthways,  is  equal  to  the  pressure  per  square  inch  on  each  lineal  unit  of  the  diameter  multiplied  by 
the  length  of  the  cylinder. 

Thus,  let  the  piston  of  a hydraulic  press  be  10  inches  in  diameter,  and  the  pressure  300  tons  net ; then 
the  pressure  per  square  inch  of  piston  will  be  300  tons  divided  by  the  number  of  square  inches  in  the 
piston,  or  6iL|jdj.J.0  = 7.639  lbs.  The  pressure  per  inch  in  length  of  the  cylinder  tending  to  ^plit  or  tear 
it  apart,  is  equal  to  the  diameter  multiplied  by  the  pressure  per  square  inch,  or  in  this  case,  10  x 7639= 
76,390  lbs.,  of  which,  of  course,  each  side  sustains  one  half. 

The  cohesive  strength  of  cast  iron  varies  from  13,000  to  20,000  lbs.  per  square  inch  ; of  wrought 
iron,  from  50  to  60,000  lbs. ; 8,000  lbs.  may  be  taken  as  the  safe  limit  for  cast  iron,  20,000  for  wrought 
iron  ; hence,  to  withstand  a force  equal  ’U?-2iL0  or  38,195  lbs.  on  each  side  ; the  thickness,  if  cast  iron, 
should  be  about  5 inches ; if  wrought  iron,  2 inches. 

Presses  made  to  withstand  but  little  pressure,  that  is  per  square  inch,  are  mostly  made  with  cylinders 
of  cast  iron.  Some  of  the  cylinders  of  large  presses  are  made  of  cast  iron,  bound  with  wrought  iron 
hoops,  as  fig.  2289,  but  the  best  material  to  withstand  great  pressure,  is  wrought  iron.  Of  this  material 
R.  Hoe  & Co.,  of  New  York,  make  their  presses,  and  of  this  are  the  jacks  of  R.  Dudgeon  constructed. 

An  English  rule  for  the  construction  of  cast  iron  cylinders,  is  to  make  the  thickness  of  metal  equal 
to  the  interior  radius  of  the  cylinder,  and  to  determine  the  entire  pressure  in  tons.  When  the  diameter 
of  the  cylinder  is  given,  the  following  simple  rule  is  used : 

Rule. — Multiply  the  square  of  the  diameter  in  inches  by  the  constant  number,  2-9186,  and  the  product 
will  be  the  pressure  in  tons. 

And  again,  when  the  pressure  in  tons  is  given,  the  diameter  of  the  cylinder  may  be  determined  by 
reversing  the  process,  or  by  the  following  rule  : 

Rule. — Divide  the  given  pressure  in  tons  by  the  constant  number  2-9186,  and  extract  the  square  root 
of  the  quotient  for  the  diameter  of  the  cylinder  in  inches. 

Example. — The  diameter  of  the  cylinder  in  a hydrostatic  press,  is  10  inches;  what  is  its  power-,  or 
what  pressure  does  it  transmit  ? 

Here,  by  the  first  rule  above,  we  have,  P = 102  x 2-9186  = 291'86  tons. 

Example. — What  is  the  diameter,  and  what  the  thickness  of  metal,  in  a press  of  300  tons  power? 

By  the  second  rule  above,  we  have,  D*  = 300  -f-  2-9186  = 102-81  nearly; 
therefore  by  extracting  the  square  root,  we  obtain,  D = ^ 102-81  = 10-13  inches  ; 
consequently,  the  thickness  of  metal  is,  t—  10-13-t-2  = 5-065  inches. 

The  hydrostatic  press  is  one  of  the  most  convenient  and  simplest  of  all  machines  for  transmitting 
great  force ; it  is  used  for  punching,  pressing,  lifting  and  pulling.  It  was  used  for  raising  the  immense 
tubes  of  the  Conway  Tubular  Bridge,  and  is  in  general  use  for  the  baling  and  pressing  of  mate- 
rials and  goods.  At  the  United  States  Navy  Yard,  Washington,  it  is  used  as  a proving  machine  for 
proving  chain  cables ; as  a jack  it  is  made  portable,  and  is  applicable  to  all  the  purposes  for  which 
such  machines  are  intended. 

Figs.  2280,  2283  represent  the  front  and  side  elevation  of  a small  hydraulic  press  with  a hand  forcing 
pump : F is  a strong  metallic  cylinder  of  cast-iron,  or  some  other  material  of  sufficient  density  to  pre- 
vent the  fluid  from  issuing  through  its  pores,  and  of  sufficient  strength  to  preclude  the  possibility  of 
rupture,  by  reason  of  the  immense  pressure  which  it  is  destined  to  withstand. 

The  cylinder  F is  bored  and  polished  with  the  most  scrupulous  precision,  and  fitted  with  the  movable 
piston  D,  which  is  rendered  perfectly  water-tight,  by  means  of  leather  collars  constructed  for  the  purpose, 
and  fixed  in  the  cylinder  by  a simple  but  ingenious  contrivance  to  be  described  hereafter. 

Into  the  side  or  base  of  the  cylinder  F,  the  end  of  a small  tube  b b b is  inserted,  and  by  this  tube  the 


38 


HYDROSTATIC  PRESS. 


water  is  conveyed  or  forced  into  the  cylinder ; the  other  end  of  the  tube  is  attached  to  the  forcing-puinp 
as  represented  in  Fig.  2280 ; but  this  will  be  more  particularly  explained  in  another  place. 

A A are  two  very  strong  upright  bars,  generally  made  of  wrought-iron,  and  of  any  form  whatever, 
corresponding  to  the  notches  in  the  sides  of  the  flat  table  E,  which  is  fixed  upon  the  end  of  the  piston  D, 
and  by  workmen  is  usually  denominated  the  “ follower ” or  “ pressing-table .” 

B is  the  top  of  the  frame  into  which  the  upright  bars  A A are  fixed,  and  c c is  the  bottom  thereof 
both  of  which  are  made  of  cast,  in  preference  to  wrought-iron,  being  both  cheaper  and  more  easily 
moulded  into  the  intended  form. 


The  bottom  of  the  frame  c c is  furnished  with  four  projections  or  lobes,  with  circular  perforations,  for 
/he  purpose  of  fastening  it  by  iron  bolts  to  the  massive  blocks  of  wood,  whose  transverse  sections  are 
indicated  by  the  lighter  shades  at  G G.  The  top  B has  two  similar  perforations,  through  which  are 
passed  the  upper  extremities  of  the  vertical  bars  A A,  and  there  made  fast,  by  screwing  down  the  cup- 
nuts  represented  at  a and  a. 

Fig.  2281  represents  the  plan  of  the  top,  or,  as  it  is  more  frequently  termed,  the  head  of  the  frame; 
the  lower  side  or  surface  of  which  is  made  perfectly  smooth,  in  order  to  correspond  with,  and  apply  to 
the  upper  surface  of  the  pressing-table  E,  in  Fig.  2280 ; this  correspondence  of  surfaces  becomes  neces- 
sary on  certain  occasions  such  as  the  copying  of  prints,  taking  fac-similes  of  letters,  and  the  like ; in  all 
such  cases,  it  is  manifest,  that  smooth  and  coincident  surfaces  are  indispensable  for  the  purpose  of  ob- 
mmng  true  impressions. 

Fig.  2281  represents  the  upper  side  of  the  block,  in  which  the  middle  part  B (through  whose 
rounded  extremities  a and  a,  the  circular  perforations  are  made  for  receiving  the  upright  bars  or 
rods  A A,  Fig.  2280,  is  considerably  thicker  than  the  parts  cn  ee.ch  side  of  it ; this  augmentation  of 
thickness  is  necessary  to  resist  the  immense  strain  that  comes  upon  it  in  that  part ; for  although  the 
pressure  may  be  equally  distributed  throughout  the  entire  surface,  yet  it  is  obvious  that  the  mechani- 
cal resistance  to  fracture  must  principally  arise  f.-om  that  part  which  is  subjected  to  the  reaction  of  the 
upright  bars. 

Fig.  2282  represents  the  plan  of  the  base  or  bottom  of  the  frame ; it  is  generally  made  of  uniform 
thickness,  and  of  sufficient  strength  to  withstand  the  pressure  ; for  be  it  understood,  that  all  the  parts  of 
the  machine  are  subjected  to  the  same  quantity  of  strain,  although  it  is  exerted  in  different  ways.  The 
upright  bars,  cylinders,  and  connecting-tubes  resist  by  tension,  the  pistons  by  compression,  and  the 
pressing-table,  together  with  the  top  and  bottom  of  the  frame,  resist  transversely. 

The  circular  perforations  cc  correspond  to  a a in  the  top  of  the  frame,  and  receive  the  upright  bars  in 
the  same  manner ; the  perforations  clddd  receive  the  screw-bolts  which  fix  the  frame  to  the  beams  oi 
timber  represented  at  G G,  Fig.  2280  ; the  large  perforation  F receives  the  cylinder,  the  upper  extremity 
of  which  is  furnished  with  a flanch,  for  the  purpose  of  fitting  the  circular  swell  around  the  perforation, 
and  preventing  it  from  moving  backwards  during  the  operation  of  the  instrument. 

A side  view  of  the  engine,  as  thus  completed,  is  represented  in  Fig.  2283,  where,  as  is  usual  in  ail 
such  descriptions,  the  same  letters  of  the  alphabet  refer  to  the  same  parts  of  the  structure. 

F is  the  cylinder  into  which  the  fluid  is  injected  ; D the  piston,  on  whose  summit  is  the  pressing-ta- 
ole  E ; A one  of  the  upright  rods  or  bars  of  malleable  iron ; B the  head  of  the  press,  fixed  to  the 
upright  bar  A by  means  of  the  cup-nut  a ; c the  bottom,  in  which  the  upright  bar  is  similarly  fixed  ; 
ind  G a beam  of  timber  supporting  the  frame  with  all  its  appendages. 

But  the  hydrostatic  press , as  here  described  and  constructed,  must  not  be  considered  as  fit  for  imme- 
diate action ; for  it  is  manifestly  impossible  to  bore  the  interior  of  the  cylinder  so  truly,  and  to  turn  the 
piston  with  so  much  precision,  as  to  prevent  the  escape  of  water  between  their  surfaces,  without  in- 
creasing the  friction  to  such  a degree,  that  it  would  require  a very  great  force  to  counterbalance  it. 

In  order,  therefore,  to  render  the  piston  water-tight,  and  to  prevent  as  much  as  possible 
the  increase  of  friction,  recourse  must  be  had  to  other  principles,  which  we  now  proceed  to 
explain. 

The  piston  D is  surrounded  by  a collar  of  pump  leather  o o,  represented  in  Fig.  2284,  which 
collar  being  doubled  up,  so  as  in  some  measure  to  resemble  a lesser  cup  placed  within  a 
greater,  it  is  fitted  into  a cell  made  for  its  reception  in  the  interior  of  the  cylinder ; and  when 
there,  the  two  parts  are  prevented  from  coming  together  by  means  of  the  copper  ring  p p,  represented 
in  Fi<>'.  2285,  being  inserted  between  the  folds,  and  retained  in  its  place,  by  a lodgment  made  for  that 
purpose  on  the  interior  of  the  cylinder. 


HYDROSTATIC  PRESS. 


39 


The  leather  collar  is  kept  down  by  means  of  a brass  or  bell-metal  ring  m m,  Fig.  2286,  2286. 

which  ring  is  received  into  a recess  formed  round  the  interior  of  the  cylinder,  and  the  cir- 
cular aperture  is  fitted  to  admit  the  piston  D to  pass  through  it,  without  materially  in- 
creasing the  effects  of  friction,  which  ought  to  be  avoided  as  much  as  possible. 

The  leather  is  thus  confined  in  a cell,  with  the  edge  of  the  inner  fold  applied  to  the 
piston  D,  while  the  edge  of  the  outer  fold  is  in  contact  with  the  cylinder  all  around  its 
interior  circumference ; in  this  situation,  the  pressure  of  the  water  acting  between  the  folds  of  the 
leather,  forces  the  edges  into  close  contact  with  both  the  cylinder  and  piston,  and  renders  the  w7hole 
water-tight ; for  if  the  leather  be  properly  constructed  and  rightly  fitted  into  its  place,  it  is  almost  im- 
possible that  any  of  the  fluid  can  escape ; for  the  greater  the  pressure,  the  closer  will  the  leather  be 
applied  to  both  the  piston  and  the  cylinder. 

The  metal  ring  mm  is  truly  turned  in  a lathe,  and  the  cavity  in  which  it  is  placed  is  formed  with  the 
same  geometrical  accuracy ; but  in  order  to  fix  it  in  its  cell,  it  is  cut  into  five  pieces  by  a very  fine  saw7, 
as  represented  by  the  lines  in  Fig.  2286,  which  are  drawn  across  the  surface  of  the  ring.  The  four  seg- 
ments which  radiate  to  the  centre  are  put  in  first,  then  the  segment  formed  by  the  parallel  kerfs,  (the 
copper  ring  pp  and  the  leather  collar  o o being  previously  introduced,)  and  lastly,  the  piston  w7hich  car- 
ries the  pressing-table. 

That  part  of  the  cylinder  above  the  ring  m m,  where  the  inner  surface  is  not  in  contact  with  the  pis- 
ton, is  filled  with  tow,  or  some  other  soft  material  of  a similar  nature ; the  material  thus  inserted  has  a 
twofold  use : in  the  first  place,  when  saturated  with  sweet  oil,  it  diminishes  the  friction  that  necessarily 
arises,  when  the  piston  is  forced  through  the  ring  m m ; and  in  the  second  place,  it  prevents  the  admis- 
sion of  any  extraneous  substance,  which  might  increase  the  friction  or  injure  the  surface  of  the  piston, 
and  otherwise  lessen  the  effects  of  the  machine. 

The  packing  here  alluded  to,  is  confined  by  a thin  metallic  annulus,  neatly  fitted  and  fixed  on  the 
top  of  the  cylinder,  the  circular  orifice  being  of  sufficient  diameter  to  admit  of  a free  and  easy  motion 
to  the  piston. 

If  a cylinder  thus  furnished  with  its  several  appendages  be  placed  in  the  frame,  and  the  whole  firmly 
screwed  together  and  connected  with  the  forcing-pump,  as  represented  in  Fig.  2280,  the  press  is  com- 
pleted and  ready  for  immediate  use ; but  in  order  to  render  the  construction  still  more  explicit  and 
intelligible,  and  to  show  the  method  of  connecting  the  press  to  the  forcing-pump, 
let  Fig.  2287  represent  a section  of  the  cylinder  with  all  its  furniture,  and  a small 
portion  of  the  tube  immediately  adjoining,  by  which  the  connection  is  effected. 

Then  is  F F the  cylinder ; D the  piston  ; the  unshaded  parts  o o the  leather  collar, 
in  the  folds  of  which  is  placed  the  copper  ring  pp,  distinctly  seen,  but  not  marked 
in  the  figure ; m m is  the  metal  ring  by  which  the  leather  collar  is  retained  in  its 
place ; n n the  thin  plate  of  copper  or  other  metal  fitted  to  the  top  of  the  cylinder,  SB 
between  which  and  the  plate  m m is  seen  the  soft  packing  of  tow,  which  we  have 
described  above,  as  performing  the  double  capacity  of  oiling  the  piston  and  jjre- 
venting  its  derangement. 

The  combination  at  w x represents  the  method  of  connecting  the  injecting-tube  to  the  cylinder:  if 
may  be  readily  understood  by  inspecting  the  figure ; but  in  order  to  remove  all  causes  of  obscurity,  it 
may  be  explained  in  the  following  manner. 

The  end  of  the  pipe  or  tube,  which  is  generally  made  of  copper,  has  a projecting  piece  or  socket- 
flanch  soldered  or  screwed  upon  it,  which  fits  into  a perforation  in  the  side  or  base  of  the  cylinder, 
according  to  the  fancy  of  the  projector,  but  in  this  figure  the  perforation  is  in  the  side. 

The  tube  thus  furnished  is  forcibly  pressed  into  its  seat  by  a hollow  screw  vi,  called  a union  screw, 
which  fits  into  another  screw  of  equal  thread  made  in  the  cavjty  of  the  cylinder;  the  joint  is  made 
water-tight,  by  means  of  a collar  of  leather,  interposed  between  the  end  of  the  tube  and  the  bottom  of 
the  cavity. 


A similar  mode  of  connection  is  employed  in  fastening  the  tube  to  the  forcing-pump,  the  description 
of  which,  although  it  constitutes  an  important  portion  of  the  apparatus,  does  not  properly  belong  to  this 
place ; the  principles  of  its  construction  and  mode  of  action  must  therefore  be  supposed  as  known,  until 
we  come  to  treat  of  the  construction  and  operation  of  pumps  in  general. 

Admitting,  therefore,  that  the  action  of  the  forcing-pump  is  understood,  it  only  now  remains  to  explain 
the  nature  of  its  operation  in  connection  with  the  hydrostatic  press,  the  construction  of  which  we  have 
so  copiously  exemplified. 

In  order  to  understand  the  operation  of  the  press,  we  must  conceive  the  piston  D,  Fig.  2280,  as  being 
at  its  lowest  possible  position  in  the  cylinder,  and  the  body  or  substance  to  be  pressed,  placed  upon  the 
crown  or  pressing-table  E ; then  it  is  manifest,  that  if  water  be  forced  along  the  tube  b b b by  means  ot 
the  forcing-pump,  it  will  enter  the  chamber  of  the  cylinder  F immediately  beneath  the  piston  D,  and 
cause  it  to  rise  a distance  proportioned  to  the  quantity  of  fluid  that  has  been  injected,  and  with  a force 
determinable  by  the  ratio  between  the  square  of  the  diameter  of  the  cylinder  and  that  of  the  forcing- 
pump.  The  piston  thus  ascending,  carries  its  crown,  and  consequently,  the  load  along  with  it,  and  by 
repeating  the  operation,  more  water  is  injected,  and  the  piston  continues  to  ascend,  till  the  body  comes 
into  contact  with  the  head  of  the  frame  B,  when  the  pressure  begins ; thus  it  is  manifest,  that  by  con- 
tinuing the  process,  the  pressure  may  be  carried  to  any  extent  at  pleasure ; but  we  have  already 
stated,  in  developing  the  theory,  that  there  are  limits,  beyond  which,  with  a given  bore  and  a given 
thickness  of  metal,  it  would  be  unsafe  to  continue  the  strain. 

When  the  press  has  performed  its  office,  and  it  becomes  necessary  to  relieve  the  action,  the  dis- 
charging-valve, placed  in  the  furniture  of  the  forcing-pump,  must  be  opened,  which  will  admit  the  water 
to  escape  out  of  the  cylinder  and  return  to  the  cistern,  while  the  table  and  piston,  by  means  of  theii 
own  weight,  return  to  their  original  position. 

Theory  of  construction  and  description  of  the  hydrostatic  weighing  machine. — If  into  the  side  of  ac 


40 


HYDROSTATIC  PRESS. 


open  cylindrical  or  other  vessel  a bent  tube  be  inserted,  and  if  on  the  surface  of  the  fluid  a movable 
cover  exactly  fitting  the  vessel  be  placed  with  a weight  upon  it,  and  the  tube  graduated: — 

Then,  any  additional  weight  placed  upon  the  cover,  may  be  determined  by  knowing  the  height  tc 
which  the  fluid  rises  in  the  tube  ; and  conversely  : — If  the  additional  weight  be  known,  the  height  to 
which  the  fluid  rises  in  the  tube  may  be  found. 

Let  A B C D represent  a vertical  section  of  a cylindrical  vessel,  or  of  any  other  vessel,  whose  side? 
are  perpendicular  to  the  horizon ; and  let  K I C be  the  corresponding  section  of  the  equilibrating  tube. 

Let  both  the  vessel  and  the  communicating  tube  be  open  at  the  upper  parts  A B and 
d c,  and  conceive  the  vessel  to  be  filled  with  fluid  to  the  line  E F or  altitude  D E ; 
then,  on  the  surface  of  the  fluid  at  E F,  let  there  be  placed  a movable  cover  exactly 
fitting  the  vessel,  so  that  the  whole  may  be  water-tight. 

Produce  E F to  b,  then  is  the  point  b at  the  same  level  in  the  tube  I K,  as  the  surface 
of  the  fluid  in  the  vessel  whose  level  is  EF:  upon  the  cover  EF  let  the  weight  w be 
placed,  and  suppose  a to  be  the  point  in  the  tube,  to  which  the  fluid  will  rise  by  the 
action  of  the  cover,  together  with  the  weight  w which  is  placed  upon  it ; in  this  case, 
the  machine  is  in  a state  of  equilibrium. 

If  some  additional  weight  w'  be  placed  upon  the  cover,  then  the  original  equilibrium 
will  be  destroyed,  and  can  only  be  restored  by  the  fluid  ascending  in  the  tube  to  a sufficient  height  to 
balance  the  additional  weight. 

Put  D = A B or  D C,  the  diameter  of  the  cylindrical  vessel,  of  which  A B C D is  a section, 
d = de,  the  diameter  of  the  communicating  tube  K I C, 
h — b a,  the  height  of  the  original  equilibrating  column, 
w — the  weight  supported  by  the  column  b a , 
w‘  — the  additional  weight,  whose  quantity  is  required, 
h'  — a K,  the  increased  altitude  of  the  supporting  column, 

J = Ei#,  the  descent  of  the  cover  occasioned  by  the  additional  load  w',  and 
s — the  specific  gravity  of  the  fluid. 

Then  it  is  manifest,  that  when  the  equilibrium  originally  obtains ; that  is,  when  the  surface  of  the 
fluid  in  the  tube  is  at  a,  and  that  in  the  vessel  at  E F,  the  pressure  of  the  fluid  in  the  tube  exerted  at  b,  is 

p = '7854  d2  h s, 

where  the  symbol  p denotes  the  pressure  at  b ; omitting  the  steps  of  the  algebraic  calculation,  we  obtain 

w'  = 7854  h’ s (D2  d~). 

If  the  fluid  be  water,  whose  specific  gravity  is  represented  by  unity,  the  equation  becomes  somewhat 
simpler ; for  in  that  case,  we  have 

w'  = -7854  h'  (D2  + d2). 

From  this  equation  the  magnitude  of  the  additional  weight,  or  the  measure  by  which  it  is  expressed, 
can  very  easily  be  ascertained ; and  the  practical  rule  by  which  it  is  discovered  is  as  follows : 

Rule. — Multiply  the  sum  of  the  squares  of  the  diameters  by  '7854  times  the  rise  of  the  fluid  in  the 
tube,  or  the  elevation  above  the  first  level,  and  the  product  will  express  the  magnitude  of  the  additional 
weight. 

Example.— The  diameter  of  a cylindrical  vessel  is  16  inches,  and  that  of  the  communicating  tube  one 
inch ; now,  supposing  the  macliine  in  the  first  instance  to  be  in  a state  of  equilibrium,  and  that  by  the 
addition  of  a certain  weight  on  the  movable  cover,  the  water  in  the  tube  rises  6 inches  above  the  origi- 
nal equilibrating  level ; how  much  weight  has  been  added  ? 

By  proceeding,  according  to  the  rule,  we  have  D2  + d1  = 162  4-  l2  = 256  + 1 = 257, 
and  by  multiplication,  we  obtain  w'  = '7854  X 6 X 257  = 121P0868  avoirdupois  lbs. 

If  the  additional  weight  by  which  the  water  is  made  to  rise  in  the  tube  be  given,  the  distance  above 
the  first  level  to  which  it  will  rise,  can  easily  be  found ; for  let  both  sides  of  the  equation  w'  = '7854  h' 
(D2  4-  i2)  be  divided  by  the  quantity  '7854  (D'-  + d2),  and  we  shall  obtain 


■7854  (D2  + d-j 

And  from  this  equation,  we  deduce  the  following  rule : — 

Rule. — Divide  the  additional  weight  bv  the  sum  of  the  areas  of  the  movable  cover  and  the  cross 
section  of  the  communicating  tube,  and  the  quotient  will  give  the  height  to  which  the  fluid  will  rise 
above  the  first  level. 

Example. — The  diameter  of  the  movable  cover  is  16  inches,  and  that  of  the  communicating  tube  one 
inch ; then,  supposing  that  the  machine  in  the  first  instance  is  brought  to  a state  of  equilibrium,  and 
that  a load  of  1211  lbs.  is  applied  on  the  cover,  in  addition  to  that  which  produces  the  equipoise;  to 
what  height  above  the  first  level  will  the  water  ascend  in  the  communicating  tube  ? 

Proceeding,  according  to  the  rule,  we  obtain  '7854  (D2  -f-  d")  — -7854  (162-f-  l2)  = 20P8478  divisor; 


2288. 


consequently,  by  division  it  is 


h' 


1211 

201-8478 


6 inches  nearly. 


And  exactly  after  the  manner  of  these  two  examples,  may  any  other  case  be  calculated ; but  in 
applying  the  principles  to  the  determination  of  weights,  mercury  ought  to  be  employed  in  preference 
to  water,  as  it  exerts  an  equal  influence  in  less  space,  and  besides,  it  is  not  subject  to  a change  of  den- 
sity by  putrefaction  and  the  like. 


18® 


Si  pipe  leading  to  small 
press,  Fig.  2290. 


WNV'W'WWXtVA^NN 


it  ft  tn 


HYDROSTATIC  PRESS. 


42 


HYDROSTATIC  PRESS. 


Figs.  2280  and  2290  show  the  elevation  and  plan  of  a press  capable  of  giving  a pressure  equal 
to  200  tons  weight ; also  of  a press  which  is  suitable  for  a pressure  of  50  tons  weight.  Bv  the  arrant 
ment  shown,  one  set  of  pumps  is  sufficient  to  operate  both  presses. 

2290. 


The  hand-wheels  s and  r operate  valves  which  can  be  opened  or  shut  as  is  wanted,  so  as.  to  connect 
or  shut  off  either  press  from  the  pumps,  vi  is  a hand-wheel  moving  a valve  which  allows  either  of  the 
press  cylinders  to  be  drawn  off,  and  returns  the  water  into  the  tank  under  the  pump  through  the  pipe  t2. 
i is  a pipe  through  which  the  water  is  pumped  on  its  passage  to  the  presses  until  it  reaches  the  valves 
s and  r,  where  it  passes  through  the  pipes  r 2 or  s 2 to  either  or  both  presses,  as  is  wanted.  The  pumps 
have  three  pistons,  which  are  operated  by  the  three-throw  crank  H,  and  are  driven  by  means  of  the 
pulleys  G.  . 

ssss  are  foundation  blocks,  of  stone,  on  which  the  presses  are  placed,  m m m m is  a wooden  frame 
under  the  small  press  to  raise  it  to  a convenient  height.  A and  a,  are  the  chambers  or  cylinders  of  the 
presses.  B and  b , are  the  pistons.  D D and  d d,  are  the  top  and  bottom  pieces,  and  EE.fc,  are  the 
columns  to  the  frames.  C and  c,  are  the  platens  or  followers  which  are  moved  up  by  the  pistons 
B and  b.  These  presses  are  from  the  Lowell  Machine  Shop. 


IIYG  ROMETER, 


43 


HYGROMETER,  an  instrument  for  measuring  the  degrees  of  moisture  or  dryness  of  the  atmosphere 

Variations  in  the  state  of  the  atmosphere,  with  respect  to  moisture  and  dryness,  are  manifested  by  a 
great  variety  of  phenomena,  and,  accordingly,  numerous  contrivances  have  been  proposed  for  ascertain . 
ing  the  amounts  of  those  variations  by  referring  them  to  some  conventional  scale.  All  such  contrivances 
are  called  hygrometers ; but  though  the  variety  of  form  that  may  be  given  to  them,  or  of  substances 
that  may  be  employed,  is  endless,  they  may  all  be  referred  to  two  classes ; namely,  1st,  those  which 
act  on  the  principle  of  absorption ; and,  2d,  those  which  act  on  the  principle  of  condensation. 

1.  Hygrometers  on  the  principle  of  absorption. — Many  substances  in  each  of  the  three  kingdoms  of 
nature  absorb  moisture  from  the  atmosphere  with  greater  or  less  avidity,  and  thereby  sutt'er  some 
change  in  their  dimensions,  or  weight,  or  some  of  their  physical  properties.  Animal  fibre  is  softened 
and  relaxed,  and  consequently  elongated,  by  the  absorption  of  moisture.  Cords  composed  of  twisted 
vegetable  substances  are  swollen,  and  thereby  shortened,  when  penetrated  by  humidity ; and  the 
alternate  expansion  and  shrinking  of  most  kinds  of  wood,  especially  when  used  in  cabinet-work,  and 
after  the  natural  sap  has  been  evaporated,  is  a phenomenon  with  which  every  one  is  familiar.  Many 
mineral  substances  absorb  moisture  rapidly,  and  thereby  obtain  an  increase  of  weight.  Now  it  is  evident 
that  any  of  these  changes,  either  of  dimension  or  of  weight,  may  be  regarded  as  the  measure  of  the 
quantity  of  moisture  absorbed,  from  which  the  quantity  of  water  existing  in  the  atmosphere  in  the  state 
of  vapor  is  inferred ; but  many  of  them  are  so  small  in  amount,  or  take  place  so  slowly,  that  they  afford 
no  certain  indication  of  the  actual  state  of  the  atmosphere  at  any  particular  moment. 

Saussure’s  hygrometer  consists  of  a human  hair,  prepared  by  boiling  it  in  a caustic  ley.  One  ex- 
tremity of  the  hair  is  fastened  to  a hook,  or  held  by  pincers ; the  other  has  a small  weight  attached  to 
it,  by  which  it  is  kept  stretched.  The  hair  is  passed  over  a grooved  wheel  or  pulley,  the  axis  of  which 
carries  an  index  which  moves  over  a graduated  arch.  Such  is  the  essential  part  of  the  instrument,  and 
it  is  easy  to  conceive  how  it  acts.  When  the  surrounding  air  becomes  more  humid,  the  hair  absorbs  an 
additional  quantity  of  moisture,  and  is  elongated ; the  counterpoise  consequently  descends,  and  turns 
the  pulley,  whereby  the  index  is  moved  towards  the  one  hand  or  the  other.  On  the  contrary,  when  the 
air  becomes  drier  the  hair  loses  a part  of  its  humidity,  and  is  shortened.  The  counterpoise  is  conse- 
quently drawn  up,  and  the  index  moves  in  the  opposite  direction.  The  accuracy  of  the  indications  01 
this  instrument  depends  on  the  assumed  principle  that  the  expansion  and  contraction  of  the  hair  are  due 
to  moisture  alone,  and  are  not  affected  by  temperature,  or  other  changes  in  the  condition  of  the  atmo- 
sphere. Experiment  shows  that  the  influence  of  temperature 
is  not  very  great ; but  after  all  precautions  have  been  taken 
in  preparing  the  instrument,  it  is  found  to  be  exceedingly 
irregular  in  its  movements,  and  subject  to  great  uncertain- 
ties. Besides,  the  substance  is  soon  deteriorated,  and  will 
scarcely  maintain  its  properties  unimpaired  during  a single 
year. 

The  hygrometer  of  De  Luc  consists  of  a very  thin  slip  of 
whalebone,  cut  transversely  or  across  the  fibres,  and  stretch- 
ed, by  means  of  a spring,  between  two  points.  One  end  is 
fixed  to  a bar,  while  the  other  acts  on  the  shorter  arm  of  the 
index  of  a graduated  scale.  When  the  whalebone  absorbs 
moisture  it  swells,  and  its  length  is  increased ; as  it  becomes 
dry  it  contracts ; and  the  space  over  which  the  index  moves 
by  the  one  or  the  other  of  these  effects,  gives  the  measure 
of  the  expansion  or  contraction,  and  the  corresponding 
change  in  the  hygrometric  state  of  the  atmosphere.  The 
action  of  this  hygrometer  appears  to  be  more  uncertain  than 
that  of  Saussure. 

The  hygrometers  which  have  been  proposed  on  the  prin- 
ciple of  a change  of  weight  arising  from  the  absorption  of 
moisture,  are  liable  to  still  greater  objections.  Changes  of 
weight  may  indeed  be  measured  with  greater  accuracy  by 
the  common  or  torsion  balance : but  in  the  present  case 
they  are  so  small,  that  the  particles  of  dust  which  are  at  all 
times  floating  in  the  atmosphere  may  produce  a great  alter- 
ation in  the  results. 

Hygrometer,  portable. — This  hygrometer  is  of  very  simple 
construction,  and  is  so  arranged  as  to  show  the  humidity  of 
the  atmosphere  in  decimal  parts  of  the  saturation,  as  well 
as  to  afford  a means  of  ascertaining  the  dew-point.  Fig. 

2291  represents  a front  elevation  of  the  instrument,  with  the 
details  dotted.  A is  the  back  or  main  supporting  piece, 
of  metal  or  glass,  to  which  is  attached,  at  the  lower  ex- 
tremity, a long  thin  strip  of  wood,  the  grain  of  which  runs 
in  a direction  transverse  to  the  length  of  the  strip.  The 
upper  end  of  this  strip  is  attached  to  the  axis  of  the  index 
C,  which  points  out  the  degrees  of  saturation  of  the  atmo- 
sphere. A helical  spring  D is  fastened  at  its  lower  end  to 
a bracket  projecting  from  the  front  of  the  back  piece  A,  its 
contrary  extremity  being  fastened,  by  means  of  a connecting-cord,  to  the  index  axis  0.  The  action 
of  the  spring  upon  the  index  is  such  as  to  tend  constantly  to  hold  it  at  its  original  position,  while  the 
expansion  and  contraction  of  the  wood-slip,  due  to  the  greater  or  less  amount  of  moisture  hi  the  atmo- 


2291. 


44 


HYGROMETER. 


iphere,  moves  the  index  round  accordingly,  and  thus  indicates  upon  the  graduated  dial  the  ratio  o 
moisture  existing  at  the  time  being. 

The  dew-point  is  readily  found  by  first  ascertaining  the  exact  temperature  at  the  time  of  observation, 
and  from  this  subtracting  the  number  indicated  on  the  dial  by  the  hand  C,  the  remainder  being  the 
temperature  corresponding  to  the  amount  of  moisture  in  the  atmosphere,  or,  as  it  is  technically  termed, 
the  dew-point. 

2.  Hygrometers  on  the  principle  of  condensation. — The  instruments  of  this  class  are  of  a more  refined 
nature  than  those  which  we  have  been  describing.  In  order  to  give  an  idea  of  the  general  principle  on 
which  they  depend,  let  us  conceive  a glass  jar,  having  its  sides  perfectly  clean  and  transparent,  to  be 
filled  with  water,  and  placed  on  a table  in  a room  where  the  temperature  is,  for  example,  50°,  the  tem- 
perature of  the  water  being  the  same  as  that  of  the  room.  Let  us  next  suppose  pieces  of  ice,  or  a 
freezing  mixture,  to  be  thrown  into  the  water,  whereby  the  water  is  gradually  cooled  down  to  55,  50, 
‘15,  &c.,  degrees.  As  the  process  of  cooling  goes  on,  there  is  a certain  instant  at  which  the  jar  loses  its 
transparency,  or  becomes  dim;  and  on  attentively  examining  the  phenomenon,  it  is  found  to  be  caused 
by  a very  fine  dew,  or  deposition  of  aqueous  vapor,  on  the  external  surface  of  the  vessel.  The  precise 
temperature  of  the  water,  and,  consequently,  of  the  vessel,  at  the  instant  when  this  deposition  begins 
to  be  formed,  is  called  the  dew-point , and  is  capable  of  being  noted  with  great  precision.  Now  this 
temperature  is  evidently  that  to  which,  if  the  air  were  cooled  down,  under  the  same  pressure,  it  would 
be  completely  saturated  with  moisture,  and  ready  to  deposit  dew  on  any  body  in  the  least  degree  colder 
than  itself.  The  difference,  therefore,  between  the  temperature  of  the  air,  and  the  temperature  of  the 
water  in  the  vessel  when  the  dew  begins  to  be  formed,  will  afford  an  indication  of  the  dryness  of  the 
air,  or  of  its  remoteness  from  the  state  of  complete  saturation. 

But  the  observation  which  has  now  been  described  is  capable  of  affording  far  more  interesting  and 
precise  results  than  a mere  indication  of  the  comparative  dryness  or  moisture  of  the  atmosphere.  With 
the  help  of  tables  of  the  elastic  force  of  aqueous  vapor  at  different  temperatures,  it  gives  the  means  of 
determining  the  absolute  weight  of  the  aqueous  vapor  diffused  through  any  given  volume  of  air,  the 
proportion  of  vapor  existing  in  that  volume  to  the  quantity  that  would  be  required  to  saturate  it,  and 
of  measuring  the  force  and  amount  of  evaporation. 

The  elastic  force  of  aqueous  vapor  at  the  boiling  point  of  water  is  evidently  equal  to  the  pressure  of 
the  atmosphere.  This  may  be  assumed  as  corresponding  to  a column  of  mercury  30  inches  in  height. 
Mr.  Dalton,  in  the  fifth  volume  of  the  Manchester  Memoirs,  has  given  the  details  of  a most  valuable  and 
beautiful  set  of  experiments,  by  which  he  ascertained  the  elastic  force  of  vapor  from  water  at  every 
degree  between  its  freezing  and  boiling  points,  in  terms  of  the  column  of  mercury  which  it  is  capable  of 
supporting.  As  the  same  experiments  have  since  been  frequently  repeated,  and  the  different  results 
present  all  the  accordance  which  can  be  expected  in  so  delicate  an  investigation,  the  tension  of  vapor 
at  the  different  temperatures  may  be  regarded  as  sufficiently  well  determined.  Supposing,  then,  we 
have  a table  exhibiting  the  elasticity  or  tension  corresponding  to  every  degree  of  the  thermometer,  the 
weight  of  a given  volume  of  vapor,  for  example,  a cubic  foot,  may  be  determined  as  follows  : — 

Steam  at  212°,  and  under  a pressure  of  30  inches  of  mercury,  is  1100  times  lighter  than  an  equal 
bulk  of  water  at  its  greatest  density,  or  a temperature  of  about  40°,  and  a cubic  foot  of  water  at  that 
temperature  weighs  437,272  grains ; the  weight,  therefore,  of  a cubic  foot  of  steam  at  that  temperature 
and  pressure  is,  437272  -j-  1700  = 257'218  grains.  Hence  we  may  find  the  weight  of  an  equal  bulk  of 
vapor  of  the  same  temperature  under  any  other  given  pressure,  suppose  0'56  of  an  inch ; for  the  density 
being  directly  as  the  pressure,  we  have  30  in.  ; 0'56  in.  : : 257'218  grs.  : 4’801  grs.,  which  is  the  weight 
required. 

Having  thus  explained  the  principle  of  the  condensation  hygrometer,  we  will  now  describe  one  or  two 
of  the  forms  under  which  it  has  been  most  frequently  constructed.  Daniell’s  hygrometer  is  represented 
in  Fig.  2292  : a and  b are  two  thin  glass  balls  of  1 j inch  diameter,  connected  together  by  a tube  having 
a bore  about  J of  an  inch.  The  tube  is  bent  at  right  angles  over  the  two  balls,  and  the  arm  b c contains 
a small  thermometer  d e,  whose  bulb,  which  should  be  of  a lengthened 
form,  descends  into  the  ball  b.  This  ball  having  been  about  two-thirds 
filled  with  ether,  is  heated  over  a lamp  till  the  fluid  boils,  and  the  vapor 
issues  from  the  capillary  tube  f which  terminates  the  ball  a.  The  vapor 
having  espelled  the  air  from  both  balls,  the  capillary  tube  is  hermetically 
closed  by  the  flame  of  a lamp.  The  other  ball  a is  now  to  be  covered 
with  a piece  of  muslin.  The.  stand  y li  is  of  brass,  and  the  transverse 
socket  i is  made  to  hold  the  glass  tube  in  the  manner  of  a spring,  allow- 
ing it  to  turn  and  be  taken  out  with  little  difficulty.  A small  thermom- 
eter kl  is  inserted  into  the  pillar  of  the  stand.  The  manner  of  using  the 
instrument  is  this : After  having  driven  out  all  the  ether  into  the  ball  b 
by  the  heat  of  the  hand,  it  is  to  be  placed  at  an  open  window,  or  out  of 
doors,  with  the  ball  b so  situated  that  the  surface  of  the  liquid  may  be 
on  a level  with  the  eye  of  the  observer.  A little  ether  is  then  to  be 
dropped  on  the  covered  ball.  Evaporation  immediately  takes  place, 
which,  producing  cold  upon  the  ball  a,  causes  a rapid  and  continuous 
condensation  of  the  ethereal  vapor  in  the  interior  of  the  instrument.  The 
consequent  evaporation  from  the  included  ether  produces  a depression 
of  temperature  in  the  ball  b,  the  degree  of  which  is  measured  by  the 
thermometer  d e.  This  action  is  almost  instantaneous,  and  the  thermom- 
eter begins  to  fall  in  two  seconds  after  the  ether  has  been  dropped.  A depression  of  30  to  40  degrees 
is  easily  produced,  and  the  ether  is  sometimes  observed  to  boil,  and  the  thermr meter  to  be  driven 
below  zero  of  Fahrenheit’s  scale.  The  artificial  cold  thus  produced  causes  a condensation  of  the  atmo- 
spheric vapor  upon  the  ball  6,  which  first  makes  its  appearance  in  a thin  ring  of  dew  coincident  with  the 


2202. 


ICE. 


4; 


Burface  of  the  ether.  The  degree  at  which  this  takes  place  must  be  carefully  noted.  In  very  damp  oi 
windy  weather  the  ether  should  be  very  slowly  dropped  upon  the  ball,  otherwise  the  descent  of  the 
thermometer  will  be  so  rapid  as  to  render  it  extremely  difficult  to  be  certain  of  the  degree.  In  dry 
weather,  on  the  contrary,  the  ball  requires  to  be  well  wetted  more  than  once,  to  produce  the  requisite 
degree  of  cold.  (Daniel!  s Meteorological  Essays.) 

The  instrument  which  has  now  been  described  is  extremely  beautiful  in  principle ; but  it  may  be 
uoubted  whether,  even  when  the  greatest  caution  is  observed,  the  temperature  which  it  indicates  is 
precisely  that  at  which  the  deposition  of  dew  takes  place.  The  deposition  first  occurs  in  a narrow  ring 
on  a level  with  the  surface  of  the  ether  in  the  ball  b,  thereby  indicating  that  the  ether  is  colder  at  the 
surface  than  a little  under  it.  But  if  the  temperature  is  not  uniform  throughout  the  ball,  it  is  evident 
that  only  a small  part  of  the  bulb  of  the  thermometer  can  be  placed  in  the  point  where  the  greatest 
cold  exists ; consequently,  the  temperature  indicated  by  the  thermometer  will  be  greater  than  is  neces- 
sary for  producing  the  deposition  of  moisture : in  other  words,  the  dew-point  will  be  given  too  high. 

HYPERBOLA.  A plane  figure,  formed  by  cutting  a section  from  a cone  by  a plane  parallel  to  its 
axis,  or  to  any  plane  within  the  cone  which  passes  through  the  cone’s  vertex. 

The  curve  of  the  hyperbola  is  such,  that  the  difference  between  the  distances  of  any  point  in  it  from 
two  given  points  is  always  equal  to  a given  right  line. 

If  the  vertexes  of  two  cones  meet  each  other  so  that  their  axes  form  one  continuous  straight  line,  and 
the  plane  of  the  hyperbola  cut  from  one  of  the  cones  be  continued,  it  will  cut  the  other  cone,  and  form 
what  is  called  the  opposite  hyperbola,  equal  and  similar  to  the  former ; and  the  distance  between  the 
vertexes  of  the  two  hyperbolas  is  called  the  major  axis,  or  transverse  diameter.  If  the  distance  between 
h certain  point  within  the  hyperbola,  called  the  focus,  and  any  point  in  the  curve,  be  subtracted  from 
the  distance  of  said  point  in  the  curve  from  the  focus  of  the  opposite  hyperbola,  the  remainder  will 
always  be  equal  to  a given  quantity,  that  is,  to  the  major  axis ; and  the  distance  of  either  focus  from 
the  centre  of  the  major  axis  is  called  the  eccentricity,  The  line  passing  through  the  centre  perpendicu- 
lar to  the  major  axis,  and  having  the  distance  of  its  extremities  from  those  of  this  axis  equal  to  the 
eccentricity,  is  called  the  minor  axis,  or  conjugate  diameter.  An  ordinate  to  the  major  axis,  a double 
ordinate,  and  an  absciss,  mean  the  same  as  the  corresponding  lines  in  the  parabola. 

HYPERBOLIC  LOGARITHMS.  A system  of  logarithms,  so  called  because  the  numbers  express 
the  areas  between  the  asymptote  and  curve  of  the  hyperbola,  those  areas  being  limited  by  ordinates 
parallel  to  the  other  asymptote,  and  the  ordinates  decreasing  in  geometrical  progression.  But  as  such 
areas  may  be  made  to  denote  any  system  of  logarithms  whatever,  the  denomination  is  not  correct.  The 
hyperbolic  logarithm  of  any  number  is  to  the  common  logarithm  of  the  same  number  in  the  ratio  ol 
2-30258509  to  1,  or  as  1 to  -43429448. 


ICE.  Water  in  a solid,  crystallized  state,  owing  to  the  abstraction  of  its  combined  heat.  Its  specific 
gravity,  according  to  Hr.  Thomson,  is  -92.  The  force  of  expansion  exerted  by  water  in  the  act  of  freez- 
ing has  been  found  irresistible  in  all  mechanical  experiments  to  prevent  it.  Advantage  of  this  wonder- 
ful phenomenon  is  taken  to  burst  bomb-shells,  and  other  massive  vessels,  by  filling  them  with  water, 
plugging  them  up,  and  then  exposing  them  to  the  frost.  Hie  effects  of  this  expansive  force  are  often 
observable  by  the  bursting  of  trees,  and  the  rending  of  rocks,  attended  with  a noise  resembling  the  ex- 
plosion of  confined  gunpowder.  Water,  after  being  long  kept  boiling,  affords  an  ice  more  solid,  and  with 
fewer  air-bubbles,  than  that  which  is  formed  from  unboiled  water;  also  pure  water,  kept  for  a long  time 
in  vacuo,  and  afterwards  frozen  there,  freezes  much  sooner  than  common  water  exposed  to  the  same 
degree  of  cold  in  the  open  atmosphere ; and  the  ice  formed  of  water  thus  divested  of  its  air,  is  much 
more  hard,  solid,  heavy,  and  transparent,  than  common  ice.  Ice,  after  it  is  formed,  continues  to  expand 
by  decrease  of  temperature  ; to  which  fact  is  probably  attributable  the  occasional  splitting  and  breaking 
up  of  the  ice  of  ponds  during  the  time  of  freezing,  and  sometimes,  independent  of  other  causes,  the  sep- 
aration of  icebergs  from  the  great  frozen  continent  at  the  poles.  According  to  Dr.  Black,  ice  requires 
147  degrees  of  heat  to  reduce  it  to  a fluid. 

The  thickness  of  ice  required  for  supporting  foot-passengers  is  about  two  inches ; for  horsemen  and 
light  carts,  four  inches ; and  for  heavy  carriages,  not  less  than  six  inches : also,  if  eight  inches  thick, 
24-pounder  guns  on  sleighs  may  pass  over  it,  or  any  load  not  causing  a greater  pressure  than  1000  lbs. 
per  square  foot  on  the  surface,  covered  by  the  runners  or  skids  on  which  it  moves ; and  if  the  ice  is 
weak,  they  may  have  balks  secured  by  lashings  to  the  tires  of  the  wheels,  for  them  to  slide  upon,  so  as 
to  spread  the  weight  over  a larger  surface,  or  lines  of  planks  should  be  laid  down  for  them  to  pass  over. 

Weak  ice  may  be  made  capable  of  bearing  even  heavy  loads  in  a very  short  time  during  frost,  by 
spreading  upon  it  layers  of  straw  or  brushwood  crossing  each  other,  and  sprinkling  them  with  water, 
so  as  to  form  a solid  road  when  frozen ; and  if  any  portion  of  the  river  remains  unfrozen  from  the 
rapidity  of  the  current,  it  may  be  made  to  freeze  by  mooring  trees  and  brushwood  so  as  to  float  in  it. 

When  the  ice  is  too  thin  for  walking  upon  it,  a man  may  often  skate  over  it,  and  ice-boats,  similar  to 
those  used  in  Canada,  might  also  be  used  for  this  purpose.  They  consist  of  a slight  frame  supported 
on  three  skates  or  runners,  one  of  which  serves  as  a rudder ; and,  provided  with  masts  and  sails,  they 
tack  like  a ship,  with  great  rapidity,  directly  to  windward,  and  attain  a velocity  of  twenty  miles  an 
hour  with  a fair  wind. 

Floating  ice  is  very  liable  to  destroy  bridges;  and  its  effects  in  rubbing  against  the  piers,  when  pro 
pelled  by  a strong  current,  are  amazing,  tearing  off  the  smallest  projecting  portions,  even  if  of  iron.  To 
resist  this,  ice-breakers  in  front  of  the  piers  are  indispensable  ; they  consist  of  a frame  supported  on  two 
rows  of  piles  meeting  each  other,  and  forming  a small  angle  against  the  current : the  upper  surface 
should  be  planked  over,  and  should  slope  upwards  from  the  water’s  edge  towards  the  top  of  the  pier 
*o  that  the  floating  ice  may  rise  over  it,  and  thus  break  itself  up,  so  as  to  pass  harmlessly  between  the 
piers,  which,  if  of  piles  or  trestles,  should  be  carefully  planked  over,  to  prevent  the  ice  catching  in  them. 


46 


ICE-HOUSE. 


To  cross  rivers  full  of  floating  ice,  very  strong  boats  or  canoes,  cut  out  of  entire  trees,  are  required  tc 
resist  the  pressure  ; they  may  be  dragged  over  the  floes  (even  if  in  motion)  which  are  too  solid  to  admit 
of  breaking  canals  through  them. 

Small  barriers  of  ice,  or  the  keys  of  barriers  interrupting  the  navigation,  or  causing  an  inundation, 
may  be  destroyed  by  turning  streams  of  water  against  certain  points,  so  as  to  melt  an  opening,  or  by 
means  of  charges  of  powder  in  casks  or  bags,  fixed  underneath  or  lodged  in  holes  bored  in  the  ice,  anc 
fired  simultaneously.  A charge  of  six  pounds,  placed  in  the  centre  of  ice  two  feet  thick,  will  break  it 
up  into  small  pieces  throughout  a circle  of  ten  feet  radius. 

Ice  and  snow,  well  rammed  together,  form  temporary  parapets  capable  of  even  more  resistance 
against  shot  than  those  of  earth. 

ICE-BOATS.  There  are  many  descriptions  of  boats  which  come  under  this  denomination ; namely, 
those  that  are  designed  to  sail  upon  the  surface  of  the  ice,  and  those  that  are  employed  to  ojsen  the 
navigation  of  frozen  rivers  or  canals,  by  breaking  up  the  ice.  The  first  mentioned  kind  of  boats  is 
much  used  in  Holland,  on  the  river  Maeze  and  the  lake  Y.  These  ice-boats  are  propelled,  it  is  said, 
with  incredible  swiftness,  sometimes  so  quick  as  to  render  respiration  difficult;  they  are  found  very 
useful  in  conveying  goods  and  passengers  over  lakes  and  great  rivers  in  that  country.  For  this  pur 
pose  a boat  is  fixed  transversely  over  a thick  plank,  or  three-inch  deal,  under  which,  at  the  extremities, 
are  fixed  irons,  turned  up  forwards,  resembling  and  operating  as  skates ; upon  this  board  the  boat  rests, 
with  its  keel  at  right  angles  to  it;  and  the  extremities  of  the  boards  serve  as  out-riggers  to  prevent  the 
boat  from  upsetting,  whence,  therefore,  ropes  are  fastened  that  lead  to  the  head  of  the  mast,  in  the 
nature  of  shrouds,  and  others  passed  through  a block  across  the  bowsprit.  The  rudder  is  made  some- 
what like  a hatchet,  with  the  edge  placed  downwards,  which,  being  pressed  down,  cuts  the  ice,  and 
serves  all  the  purposes  of  a rudder  in  the  water,  by  enabling  the  helmsman  to  steer,  tack,  Ac. 

The  other  kind  of  ice-boat  alluded  to,  is  a strong  and  heavy-laden  canal  boat,  fitted  up  for  the  pur 
nose  of  breaking  the  ice,  by  arming  the  fore-part  of  the  keel  and  the  bows  with  iron,  which  penetrate 
and  break  down  the  ice  as  the  boat  is  drawn  forcibly  along  by  an  adequate  number  of  horses  towing  it 
on  the  path.  This  measure  of  opening  the  navigation  of  a canal  is  seldom  adopted,  except  when  the 
iee  is  only  a few  inches  in  thickness,  or  when  a thaw  has  rendered  thicker  ice  cf  little  tenacity. 

ICE-HOUSE.  A repository  for  ice  during  the  summer  season.  In  America  and  other  places  ice' is 
kept  in  deep  cellars,  from  which  the  external  air  is  excluded  as  much  as  possible,  and  provided  with 
drains  to  keep  them  dry.  When  the  surrounding  soil  is  moist,  a frame-work  or  case  of  carpentry  is 
constructed,  having  a grating  at  bottom,  and  is  so  placed  in  the  cellar  as  to  be  two  or  more  feet  distant 
from  the  floor,  sides,  and  roof  of  the  cellar.  In  this  the  ice  is  said  to  be  as  perfectly  preserved  as  in  a 
dry  cellar.  Some  market-gardeners  preserve  ice  in  great  heaps,  by  merely  building  it  upon  an  ele- 
vated base  in  the  open  garden,  and  covering  it  over  and  around  by  a very  thick  stratum  of  straw  or 
reeds.  This  plan  of  preserving  ice  is  in  accordance  with  Mr.  Cobbett’s  recommendation  in  his  Cottage 
Economy , wherein  he  observes  that  “ an  ice-house  should  not  be  underground,  nor  shaded  by  trees,  but 
be  exposed  to  the  sun  and  air ;”  that  its  bed  should  be  three  feet  above  the  level  of  the  ground,  and 
composed  of  something  that  will  admit  of  the  drippings  flowing  instantly  off;  and  he  adds,  that  “with 
some  poles  and  straw,  a Virginian  will  construct  an  ice-house  for  ten  dollars,  worth  a dozen  of  those 
which  cost  the  man  of  taste  in  England  as  many  scores  of  pounds.”  The  ice-houses  built  by  the  Vir- 
ginians consist  of  an  inner  shed,  surrounded  by  an  outer  one,  and  having  a sufficient  vacant  space 
between  the  two  to  enable  a person  to  walk  round ; the  walls  and  roofs  of  both  the  sheds  are  made  of 
thatch,  laid  on  about  a foot  thick ; and  the  ice  is  deposited  in  the  inner  shed  on  a bed  of  straw.  In 
England  and  France,  the  common  form  of  ice-houses  is  that  of  an  inverted  cone,  or  rather  of  a hen’s 
egg,  with  the  broad  end  uppermost.  The  situation  of  an  ice-house  should  be  dry,  as  moisture  has  a 
tendency  to  dissolve  the  ice  ; it  should  also  be  so  elevated  that  water  may  freely  run  off.  It  should  be 
exposed  to  the  sun  and  air,  not  under  the  drip,  or  in  the  shade  of  trees,  in  order  that  the  external  de- 
posit of  moisture  may  be  readily  evaporated.  The  form  of  the  building  may  be  varied  according  to 
circumstances ; but  in  the  well  or  receptacle  for  the  ice,  it  is  desirable  to  have  sufficient  room  for  the 
deposit  of  two  or  three  years’  consumption,  as  a provision  against  mild  winters.  Where  the  situation 
is  of  a dry,  chalky,  gravelly,  or  sandy  kind,  the  pit  may  be  entirely  below  the  surface  of  the  ground ; 
in  which  case,  an  ice-house  on  the  following  plan  may  be  advantageously  introduced. 

Dig  a pit  of  about  twelve  feet  deep,  and  wide  enough  to  permit  the  erection  therein  of  a frame  of 
rough  wood  posts.  This  frame  is  to  be  fourteen  feet  wide  each  way  at  the  bottom,  and  sixteen  feet 
each  way  at  the  top.  The  posts  may  be  about  nine  inches  in  diameter,  placed  near  enough  to  each 
other  for  thin  laths  to  be  nailed  upon  them,  and  the  inside  be  dressed  to  an  acute  angle,  so  that  as  little 
wood  as  possible  may  touch  the  ice.  On  the  inside  let  thin  laths  be  nailed  at  about  two  feet  apart.  On 
the  outside,  at  moderate  distances,  nail  rough  boards,  and  fill  the  place  within  with  wheat  or  rye  straw 
set  on  end.  The  inside  of  the  roof  to  be  made  in  the  same  way,  and  also  the  gables.  Straw  is  to  be 
sewed  on  the  inside,  and  heath  or  straw  on  the  outside  of  the  door.  The  outside  of  the  roof  is  to  be 
thickly  thatched  with  straw  or  heath ; and  heath,  brushwood,  or  fir-tops,  to  be  filled  in  between  the 
outside  boarding  and  the  surrounding  ground,  and  then  neatly  thatched  or  turfed  over.  The  bottom  oi 
the  house,  for  two  feet  deep,  should  be  laid  with  large  logs  or  stones,  next  with  heath,  fir-tops,  or  brush- 
wood, and  then  with  straw.  The  ice-house,  thus  completed,  will  look  like  a square  beehive  inverted, 
and  is  then  ready  to  receive  the  ice  or  snow.  But,  unless  the  house  be  in  a very  shady  place,  it  may 
be  necessary  to  extend  the  roof,  where  the  door  is  placed,  five  or  six  feet,  making  a second  gable  and 
door,  finished  in  the  same  way  as  the  first,  and  fill  up  the  intervening  space,  except  a passage,  with 
heath  or  straw. 

Mode  of  filling  the  house. — When  the  ice  (or  snow,  if  ice  cannot  be  procured,)  is  put  into  the  house, 
it  must  be  well  beaten  down  with  a pavior’s  rammer,  or  mallet,  and  the  surface  always  kept  concave, 
as  by  this  means  any  snow  or  ice  that  may  melt  will  run  to  the  middle,  or  interstices,  and  freeze.  For 
the  same  reason,  the  ice  ought  always  to  be  kept  concave  when  it  is  taken  out  for  use.  Should  the 


ICE-SAWS. 


47 


frost  be  very  intense  when  the  ice-house  is  getting  filled,  it  may  be  very  beneficial  at  the  close  cf 
each  day’s  felling  to  throw  in  thirty  or  forty  pails  of  water,  which  will  fill  the  interstices  and  freeze. 
When  the  house  is  full,  spread  upon  the  concave,  surface  a carpet,  or  sail  split  up  in  the  middle,  and 
upon  the  top  thereof  a foot  thick  of  water  When  ice  is  required  for  the  use  of  the  family,  or  when  it 
is  necessary  to  put  in  fresh  meat  to  lie  on  the  face  of  the  ice  for  preservation,  or  to  take  out  for  use,  the 
straw  and  carpet,  or  sail,  is  to  be  opened  in  the  middle.  Should  rats  infest  the  place,  an  iron-wire 
frame  or  case  may  be  required  to  put  the  meat  or  fish,  &c.,  into  when  lying  on  the  ice.  A small  open 
surface-drain  ought  to  be  dug  round  the  house,  to  prevent  any  water  running  into  it.  Opening  the  door 
of  the  house  does  little  harm.  Damp  or  dense  substances  touching  the  ice  are  much  more  prejudicial 
than  dry  air. 

ICE-SAWS.  Large  saws  used  for  cutting  through  the  ice,  for  relieving  ships  when  frozen  up.  The 
vessels  employed  in  the  Greenland  fisheries,  and  others  that  navigate  the  polar  seas,  are  regularly  fur- 
nished with  these  machines,  as  the  lives  of  the  crew  not  unfrequently  depend  on  the  expedition  with 
which  a passage  can  be  cut,  so  as  to  disengage  the  vessel  before  the  further  accumulation  of  ice  renders 
it  an  impossible  undertaking.  The  saw,  with  a weight  suspended  to  it,  is  introduced  by  means  of  a 
hole  broken  through  the  ice,  and  is  suspended  by  a rope  passed  over  a pulley  fixed  to  a triangle.  A 
party  of  a dozen  or  more  men  run  out  and  back  again  with  a rope,  and  thus  move  the  saw  up  and 
down  till  it  has  cut  its  way  so  far  as  to  hang  perpendicularly  from  the  pulley.  The  triangle  is  then 
moved  a foot  or  two  further,  and  the  sawing  recommences,  the  services  of  the  whole  crew  being  required 
m this  laborious  undertaking. 

In  Hood’s  machine,  the  saw  is  suspended  by  a slight  sledge,  and  is  worked  by  the  power  of  only  two 
or  three  men  at  the  end  of  a lever ; a bar,  called  a propeller,  is  fixed  on  the  lever  between  the  fulcrum 
and  the  saw,  the  other  end  resting  on  the  surface  of  the  ice,  and  so  adjusted  that  each  motion  of  the 
iever  shall  produce  a cut  of  a given  length,  and  at  the  same  time,  by  means  of  the  propeller,  push  the 
sledge  on,  so  that  the  teeth  of  the  saw  shall  always  be  in  contact  with  the  ice. 


Fig.  2293  gives  a side  elevation  of  the  machine,  aaa  is  a sledge,  of  open  frame-work,  resting  on  the 
surface  of  the  ice ; b a transverse  bar  passing  through  the  lever  c c,  and  forming  the  fulcrum  on  which 
it  moves ; this  lever  has  a cross-handle,  as  represented  in  perspective  in  dotted  lines ; e a clamp  or 
brace  consisting  of  two  cheeks,  one  on  each  side  of  the  lever,  loosely  pinned  at  top  to  the  lever,  and  at 
bottom  to  the  saw /;  g a clamp  similar  to  e,  by  which  the  weight  cl  (which  is  of  the  shape  of  a double 
convex  lens)  is  hung  to  the  lower  end  of  the  saw;  i the  propeller,  an  iron  bar,  terminating  below  in  two 
claws,  and  at  top  in  a fork,  and  suspended  on  the  lever  by  means  of  a transverse  pin  k ; l a weight 
hung  to  the  propeller  at  m ; n a transverse  bar,  limiting  the  motion  of  the  handle-end  of  the  lever  in  an 
upward  direction.  It  should  be  understood  that  there  is  a duplicate  frame  similar  to  that  brought  into 
view,  on  the  other  side  of  the  machine,  about  18  inches  apart,  and  connected  by  transverse  bars.  To 
prevent  the  lever  from  swerving  laterally,  there  are  at  the  handle  ends  two  upright  bars,  between 
which  the  lever  moves.  The  saw,  after  having  once  entered  the  ice,  will  only  require  from  two  to  four 
men  to  \Vork  it ; and  it  should  not  be  taken  out  of  the  ice  till  after  the  distance  required  to  be  cut 
through  is  accomplished.  The  saw  can  be  guided  by  the  lever  in  any  direction,  so  as  to  cut  the  ice  into 


48 


ICE-TRADE. 


pieces  most  convenient  for  removal,  either  by  pushing  them  under  the  adjacent  floor  of  ice,  or  by  drag- 
ging them  out  of  the  ship’s  track  into  clear  water. 

ICE-TRADE.  The  ice-trade  of  the  United  States  was  commenced  by  Frederic  Tudor,  of  Boston,  in 
1805.  The  first  enterprise  resulted  in  a loss,  but  was,  nevertheless,  followed  up  until  the  embargo  and 
war  put  an  end  to  the  foreign  trade,  at  which  period  it  had  yielded  no  profit  to  its  projector.  After  the 
close  of  the  war,  in  1815,  Mr.  Tudor  recommenced  his  operations  by  shipments  to  Havana  under  a con- 
tract with  the  government  of  Cuba,  which  enabled  him  to  pursue  his  undertaking  without  loss,  and 
extend  it,  in  1817,  to  Charleston,  S.  C. ; in  the  following  year  to  Savannah,  Ga.;  and  in  1820  to  New 
Orleans.  On  the  18th  May,  1833,  the  first  shipment  of  ice  was  made  to  the  East  Indies,  by  Mr.  Tudor, 
and  since  that  period  he  has  extended  his  operations  to  Madras  and  Bombay. 

Previously  to  1832  the  trade  had  been  chiefly  confined  to  the  operations  of  the  original  projector, 
although  several  enterprises  had  been  undertaken  by  other  persons  and  abandoned.  The  increase  of 
shipments  to  this  period  had  been  small,  the  whole  amounting,  in  1832,  to  4352  tons,  which  was  taken 
entirely  from  Fresh  Pond,  in  Cambridge,  and  shipped  by  Mr.  Tudor,  who  was  then  alone  in  the  trade. 
Up  to  this  time  the  ice  business  was  of  a very  complicated  nature.  Ship-owners  objected  to  receive  it 
on  freight,  fearing  its  effect  on  the  durability  of  their  vessels  and  the  safety  of  voyages ; ice-houses 
abroad  and  at  home  were  required,  and  the  proper  mode  of  constructing  them  was  to  be  ascertained. 
The  best  modes  of  preparing  ships  to  receive  cargoes  were  the  subject  of  expensive  and  almost  endless 
experiments.  The  machines  to  cut  and  prepare  ice  for  shipping  and  storing,  and  to  perform  the  opera- 
tions of  hoisting  it  into  storehouses  and  lowering  it  into  the  holds  of  vessels,  were  all  to  be  invented, 
involving  much  expense  and  vexation.  Many  of  these  difficulties  have  now  been  overcome,  and  since 
1832  the  trade  has  increased  much,  and  appears  destined  to  a still  more  rapid  increase  for  some  years. 
It  has  also  been  divided  among  many  parties,  and  its  methods  have  been  further  improved  and  a knowl- 
edge of  them  more  widely  diffused. 

The  ice  has  been  chiefly  taken  from  Fresh  and  Spy  Ponds,  and  since  1841  mainly  transported  on  the 
Charlestown  Branch  Railroad,  which  was  constructed  for  that  purpose.  Quite  recently,  ice  establish- 
ments have  been  made  at  most  of  the  ponds  near  Boston,  and  it  is  probable  that  in  a few  years  the 
product  of  all  these  waters  may  be  required  to  supply  the  trade.  In  the  year  1839  the  great  quantity 
of  ice  cut  at  Fresh  Pond,  and  the  consequent  difficulties  which  had  arisen  among  the  proprietors  as  to 
where  each  should  take  ice,  induced  them  to  agree  to  distinct  boundary  lines,  which  were  settled  by 
three  commissioners,  on  the  principle  of  giving  to  each  the  same  proportion  of  contiguous  surface  of  the 
lake,  as  the  length  of  his  shore-line  was  to  its  whole  border. 

The  shipments  of  ice  from  Boston  coastwise,  for  the  year  ending  December  31,  1847,  amounted  to 
51,887  tons.  The  ice  shipped  to  foreign  ports  during  the  same  period  amounted  to  22,591  tons. 

The  freight  paid  during  this  year  is  supposed  to  have  averaged  as  high  as  $2.50  per  ton,  at  which 
rate  it  would  amount,  on  the  74,478  tons  shipped  abroad  and  coastwise,  to $186,195 

There  is  a great  variation  in  the  cost  of  seeming  ice  and  stowing  it  on  board  vessels,  caused 
by  winters  favorable  or  otherwise  for  securing  it,  and  by  the  greater  or  less  expense  of  the 
fittings  required  for  voyages  of  different  duration,  or  by  difference  of  season  when  the  ship- 
ments are  made.  Taking  all  these  contingencies  into  consideration,  the  cost  of  ice  when  stowed 
on  board  may  be  estimated  to  average  $2  per  ton,  which  would  give  for  the  quantity  shipped. . 148,956 

There  were  in  1847  upwards  of  29  cargoes  of  provisions,  fruits,  and  vegetables  shipped  in 
ice  to  ports  where  otherwise  such  articles  could  not  be  sent,  the  invoiced  cost  of  which,  at 


Boston,  would  average  about  $2,500  each 72,500 

To  these  items  may  be  added  the  profits  of  the  trade  to  those  engaged  in  it 100,000 

Total  returns §507,651 


The  methods  and  materials  for  preparing  vessels  for  the  transportation  of  ice  have  been  various. 
Formerly  their  holds  were  ceiled  up  at  tire  sides,  bottom,  and  top,  with  boards  nailed  to  joist-ribs  se- 
cured to  the  side  of  the  vessel,  and  with  double  bulkheads  forward  and  aft.  The  spaces  thus  formed 
were  filled  with  refuse  tan,  rice-hulls,  meadow-hay,  straw,  wood-shavings,  or  like  materials.  These 
spaces  were  made  of  a thickness  proportionate  to  the  length  of  the  voyage,  and  with  reference  to  the 
season.  The  immediate  surface  of  the  ice  was  covered  with  the  same  materials,  excepting  tan.  At 
the  present  time  sawdust  is  used  almost  exclusively  for  voyages  of  considerable  length.  It  is  placed 
immediately  between  the  ice  and  the  side  of  the  vessel.  This  material  is  obtained  from  the  State  of 
Maine,  and  before  its  use  for  this  purpose  was  entirely  wasted  at  the  water-mills,  and,  falling  into  the 
streams,  occasioned  serious  obstructions.  During  the  year  1847,  4600  cords  were  brought  to  Boston,  at 
an  average  value  of  $2.50  per  cord,  delivered. 

Almost  the  whole  value  of  the  returns  of  the  ice-trade,  including  freight,  are  a gain  to  this  country. 
The  ice  itself,  the  labor  expended  on  it,  the  materials  for  its  preservation,  and  the  means  of  its  trans- 
portation, would  be  worthless  if  the  trade  did  not  exist. 

Ice  being  shipped  and  used  at  all  seasons,  large  storehouses  are  required  to  preserve  it.  Exclusiv 
of  ice-houses  on  the  wharves  at  Charlestown  and  East  Boston,  in  which  ice  is  stored  for  short  periods 


there  had  been  erected  in  1847,  and  previously — 

At  Fresh  Pond,  in  Cambridge,  ice-houses  capable  of  containing 86,732  tons. 

At  Spy  Pond,  in  West  Cambridge 28,000 

At  Little  Pond 2,400  “ 

At  Wenham  Pond 13,000 

At  Medford  Pond 4,000  “ 

At  Eel  Pond,  in  Malden  2,000  “ 

At  Horn  Pond,  in  Woburn  4,000  “ 

At  Sumner’s  Pond 1,200  “ 

Total 141,332  tons. 


ICE-TRADE. 


49 


The  ice-houses  now  in  use  are  built  above  ground.  In  southern  countries,  where  ice  is  most  valuable, 
they  are  constructed  at  greater  expense,  usually  of  brick  or  stone,  and  the  protection  to  the  ice  consists 
in  air-spaces,  or  in  dry,  light  vegetable  substances  inclosed  between  two  walls.  In  this  vicinity,  on  the 
borders  of  the  lakes,  where  ice  is  least  valuable,  they  are  usually  built  of  wood,  in  which  case  they  ar$ 
of  two  walls,  formed  by  placing  two  ranges  of  joist  upright,  framed  into  plates  at  the  top,  and  placed 
in  the  ground  at  the  bottom,  or  framed  into  silis ; these  two  ranges  are  ceiled  with  boards  secured  to 
that  side  of  each  range  which  is  nearest  the  other,  and  the  space  between  the  two  boardings  filled  with 
refuse  tan,  wet  from  the  yards.  This  wet  tan  is  frozen  during  the  winter,  and  until  it  is  thawed  in  the 
spring  and  summer,  little  waste  occurs ; afterwards  the  waste  is  more  rapid ; but,  as  a large  portion  oi 
the  ice  is  shipped  or  otherwise  used  before  this  takes  place,  the  loss  in  quantity  is  small,  and,  occurring 
before  the  expenses  of  transportation  have  been  paid,  is  of  less  pecuniary  moment. 

In  one  instance  brick  has  been  used  in  the  construction  of  an  ice-house,  which  covers  36,000  feet  of 
land,  and  the  vaults  of  this  ice-house  are  40  feet  in  depth,  and  its  walls  are  four  feet  thick  from  outside 
to  inside,  inclosing  two  sets  of  air-spaces.  Such  a construction  is  more. costly,  but  has  the  advantage  of 
durability  and  safety  from  fire,  to  which  ice-houses  are  much  exposed  from  the  frequent  juxtaposition 
of  railroad-engines,  and  the  light,  dry  materials  used  about  them  to  cover  and  otherwise  preserve  ice. 

In  the  winter  of  1847,  about  1650  were  paid  daily  for  labor  of  men,  and  ?230  for  that  of  horses,  when 
the  weather  was  most  favorable  for  cutting  ice.  Such  activity  is,  however,  of  short  duration,  as  there 
are  not  generally  more  than  20  days  in  a season  which  are  really  favorable  to  the  operation  of  securing 
ice.  The  price  paid  is  usually  §1  per  day  for  horses  and  men. 

At  first  the  implements  of  husbandry  only  were  used  in  securing  ice ; but  as  the  trade  became  more 
important,  other  machines  and  different  method's  were  adopted,  and  abandoned  when  better  were 
brought  forward,  or  when  the  increased  magnitude  of  the  business  required  greater  facilities.  More  ice 
is  now  secured  in  one  favorable  day  than  would  have  supplied  the  whole  trade  in  1832.  Ordinarily, 
before  there  has  been  cold  enough  to  form  ice  of  suitable  thickness,  snows  fall  on  its  surface.  If  this 
occurs  when  the  ice  is  four  or  more  inches  in  thickness,  and  the  snow  not  heavy  enough  to  sink  the  ice, 
it  can  be  removed  by  using  horses  attached  to  the  “ snow-scraper and  under  such  circumstances  this 
is  the  method  in  common  use.  But  if  snow  falls  so  heavy  as  to  bring  the  water  above  the  surface  of 
the  ice,  it  is  removed,  after  it  has  congealed  into  snow-ice,  with  the  “ ice-plane.” 

These  preliminary  expenses  are  often  very  great ; frequently,  after  much  expense  has  been  incurred 
to  remove  a body  of  snow  or  snow-ice,  the  weather  becomes  warm,  and  spoils  the  ice  on  which  so  much 
has  been  expended.  And,  on  the  other  hand,  if  it  is  not  done,  and  the  cold  continues,  there  will  be 
little  or  no  increase  of  thickness  to  the  ice,  which  is  equally  a disaster. 

When  the  ice  is  made  up  for  transportation,  it  is  employed  in  ships  as  ballast,  for  which  purpose  it  is 
carefully  cut  up  into  blocks  to  fit  the  hold,  and  covered  with  sawdust,  straw,  and  charcoal  dust,  all  non 
conductors  of  heat,  under  cover  of  which  it  is  conveyed  on  the  voyage.  When  the  ice  is  regularly 
shipped  as  cargo,  being  cut  into  blocks,  it  is  packed  on  board  the  vessel,  in  thin  air-tight  boxes,  with 
straw  and  hay.  In  this  manner  it  is  conveyed  without  loss. 

The  machinery  employed  for  cutting  the  ice  is  worked  by  men  and  horses  in  the  following  manner : — 
From  the  time  when  the  ice  first  forms,  it  is  carefully  kept  free  from  snow  until  it  is  thick  enough  to 
be  cut;  that  process  commences  when  the  ice  is  a foot  thick.  A surface  of  some  two  acres  is  then  se- 
lected, which  at  that  thickness  will  furnish  about  2000  tons ; and  a straight  line  is  then  drawn  through 
its  ceutre,  from  side  to  side  each  way.  A small  hand-plough  is  pushed  along  one  of  these  lines,  until 
the  groove  is  about  three  inches  deep  and  a quarter  of  an  inch  in  width,  when  the  “ marker,”  Fig.  2294, 
is  introduced.  This  implement  is  drawn  by  two  horses,  and  makes  two  new  grooves,  parallel  with  the 
first,  21  inches  apart,  the  gage  remaining  in  the  original  groove.  The  marker  is  then  shifted  to  the  out- 
side groove,  and  makes  two  more.  Having  drawn  these  lines  over  the  whole  surface  in  one  direction, 
the  same  process  is  repeated  in  a transverse  direction,  marking  all  the  ice  out  into  squares  of  21  inches. 
In  the  mean  time,  the  “ plough,”  Fig.  2295,  drawn  by  a single  horse,  is  following  in  these  grooves,  cutting 
the  ice  to  a depth  of  six  inches. 


One  entire  range  of  blocks  is  then  cut  out  with  the  “ ice-saw,”  Fig.  2296,  and  the  remainder  are  split 
off  towards  the  opening  thus  made  with  an  iron  bar.  This  bar,  represented  in  Fig.  2297,  is  shaped  like 
a spade,  and  is  of  a wedge-like  form.  When  it  is  dropped  into  the  groove,  the  block  splits  off ; a very 
slight  blow  being  sufficient  to  produce  that  effect,  especially  in  very  cold  weather.  The  labor  of  “ split- 
ting” is  slight  or  otherwise,  according  to  the  temperature  of  the  atmosphere.  “ Platforms,”  or  low  tables 
of  frame-work,  are  placed  near  the  opening  made  in  the  ice,  with  iron  slides  extending  into  the  water, 
and  a man  stands  on  each  side  of  this  slide  armed  with  an  “ice-hook.”  With  this  hook,  Fig.  229S,  the 
ice  is  caught,  and  by  a sudden  jerk  thrown  up  the  “ slide”  on  to  the  “ platform.”  In  a cold  day  every 
thing  is  speedily  covered  with  ice  by  the  freezing  of  the  water  on  the  platforms,  slides,  Ac.,  and  the 
enormous  blocks  of  ice,  weighing,  some  of  them,  more  than  200  pounds,  are  hurled  along  these  slippery 
surfaces  as  if  they  were  without  weight.  Beside  this  platform  stands  a “sled”  of  the  same  height,  ca- 
pable of  containing  about  three  tons,  which,  when  loaded,  is  drawn  upon  the  ice  to  the  front  of  the 
storehouse,  where  a large  stationary  platform,  of  exactly  the  same  height,  is  ready  to  receive  its  load, 
whicn,  as  soon  as  discharged,  is  hoisted,  block  by  block,  into  the  house,  by  horse-power.  This  process 
of  hoisting  is  so  judiciously  managed,  that  both  the  taking  up  of  the  ice  and  the  throwing  it  into  the 


50 


ILLUMINATION. 


building  are  performed  by  the  horse  himself.  The  frame  which  receives  the  block  of  ice  to  be  hoisted 
is  sunk  into  a square  opening  cut  in  the  stationary  platform,  the  block  of  ice  is  pushed  on  to  it,  the  horse 
starts,  and  the  frame  rises  with  the  ice  until  it  reaches  the  opening  in  the  side  of  the  storehouse  ready 
for  its  reception,  when,  by  an  ingenious  piece  of  mechanism,  it  discharges  itself  into  the  building,  and 
the  horse  is  led  back  to  repeat  the  process. 

Forty  men  and  twelve  horses  will  cut  and  stow  away  400  tons  a day.  In  favorable  weather  100  men 
are  sometimes  employed  at  once.  When  a thaw  or  a fall  of  rain  occurs,  it  entirely  unfits  the  ice  for 
market,  by  rendering  it  opaque  and  porous ; and  occasionally  snow  is  immediately  followed  by  rain, 
and  that  again  by  frost,  forming  snow-ice,  which  is  valueless,  and  must  be  removed  by  the  “ plane.” 


The  operation  of  planing  is  somewhat  similar  to  that  of  cutting.  A plane,  Fig.  2299,  gaged  to  run  in 
the  grooves  made  by  the  marker,  and  which  shaves  the  ice  to  the  depth  of  three  inches,  is  drawn  by  a 
horse  until  the  whole  surface  of  the  ice  is  planed.  The  chips  thus  produced  are  then  scraped  off,  and  if 
the  clear  ice  is  not  reached,  the  process  is  repeated.  If  this  makes  the  ice  too  thin  for  cutting,  it  is  left 
in  statu  quo,  and  a few  nights  of  hard  frost  will  add  below  as  much  as  has  been  taken  off  above. 

In  addition  to  filling  their  ice-houses  at  the  lake  and  in  the  large  towns,  the  company  fill  a large 
number  of  private  ice-houses  during  the  winter — all  the  ice  for  these  purposes  being  transported  by 
railway.  It  will  be  easily  believed  that  the  expense  of  providing  tools,  building  houses,  furnishing 
labor,  and  constructing  and  keeping  up  the  railway,  is  very  great,  but  the  traffic  is  so  extensive,  and  the 
management  of  the  trade  so  good,  that  the  ice  can  be  furnished  at  a very  trifling  cost. 

ICOSAHEDRON,  or  ICOSAEDRON,  in  geometry,  one  of  the  regular  platonic  bodies,  comprehended 
under  twenty  equal  triangular  sides  or  faces.  It  is  formed  of  twenty  pyramids,  whose  bases  are  the 
twenty  equal  and  equilateral  triangles,  the  summits  of  which  terminate  in  the  centre  of  the  body. 

Let  S represent  the  side  ; then  will  surface  = 5 S2  ■f  3 = 8’66025403  S2,  and  solidity  = | Sa 

^ + 5__  o.1S16950  g3 

o 

ILLUMINATION.  Without  entering  minutely  into  the  subject,  it  is  evident  that  the  value  of  any 
means  of  illumination  must  depend  upon  two  things — namely,  upon  the  quantity  of  light  evolved,  and 
upon  the  consumption  of  lighting  material  which  accompanies  it.  A candle,  or  a lamp,  &c.,  will  be  the 
more  valuable,  the  more  light  it  gives  from  as  little  tallow  or  oil  as  possible.  Light  cannot  be  measured 
with  reference  to  its  quantity  any  more  than  heat ; it  cannot  be  estimated  how  much  light  a flame 
emits,  but  it  can  be  scientifically  ascertained  how  much  more  or  less  light  it  evolves,  than  another  flame. 

All  determinations  of  this  nature  are,  therefore,  comparative.  The  most  casual  observation  of  two 
flames,  for  example,  that  of  a candle  and  of  gas,  shows  the  one,  although  both  are  of  equal  size,  to  be 
infinitely  brighter  than  the  other. 

.The  dissemination  of  light  is  entirely  effected  by  radiation;  the  intensity  may,  therefore,  be  said  to 
express  the  sum  of  the  rays  which  are  emitted  to  a certain  surface,  for  example,  to  a square  foot.  It  is 
evident,  that  the  sum  must  be  diminished  by  the  distance  from  the  source,  as  the  rays  separate  more 
and  more  from  each  other.  According  to  the  laws  of  optics,  the  intensity  is  in  relation  to  the  square  of 
the  distance  ; when,  therefore,  a surface  is  illumined  to  the  same  extent  by  two  flames,  the  rays  of  light 
from  each  will  be  proportional  to  the  square  of  the  distance  at  which  each  flame  must  be  placed  in 
order  to  produce  an  equal  amount  of  light.  It  is  upon  this  principle  that  the  actual  determination  of 
the  intensities  and  quantities  of  light  depends ; the  measure  for  both  is,  therefore,  the  distance  to  which 
the  flames  to  be  compared  must  be  brought,  in  order  to  produce  an  equal  amount  of  light.  (See  Pho- 
tometer, in  article  Gas.)  Practically,  however,  it  is  not  possible  to  determine,  even  approximatively, 
the  degree  of  brilliancy ; the  degree  of  light  is  fherefore  not  observed,  but  its  negation,  the  shadow. 

In  such  experiments  a board  is  used,  covered  with  unglazed  white  paper,  before  which,  at  a distance 
of  from  two  to  three  inches,  an  iron  rod  is  placed,  which  has  been  previously  blackened  by  holding  it 
in  the  candle.  Opposite  this  boardj  but  at  the  same  height,  the  flames  to  be  compared  are  so  placed 
that  both  the  shadows  (for  e^ich  throws  a shadow)  fall  close  to  each  other  upon  the  board,  and  then  the 
stronger  flame  is  so  far  removed,  or  the  weaker  one  approached,  until  both  shadows  appear  equally 
deep,  and  lastly,  their  respective  distances  from  the  centres  of  the  flames  are  measured.  The  squares 
of  these  distances  give  the  relative  intensities  of  light ; if  a flame,  for  example,  has  been  three  times  as 
far  removed  as  another,  its  intensity  will  be  to  that  of  the  latter,  as  32  to  l2  = 9 : 1 = 1 : 9,  or  9 times 
greater.  As  such  observations  are  simultaneous,  and  of  like  duration,  they  give  likewise  the  relative 
quantities  of  light ; for  unequal  lengths  of  time,  this  has  only  to  be  multiplied  with  the  respective  du- 
ration. When  one  of  these  flames,  therefore,  burns  3 hours,  and  the  other  only  2,  then  the  quantities  oi 
light  evolved  will  be  in  the  proportion,  3 X 9 : 2 X 1 or  27  : 2. 

One  circumstance  in  particular  requires  notice : that  when  two  perfectly  similar  shadows  of  this  kind 
are  observed  from  one  side,  the  one  appears  brighter  than  the  other,  and  the  same  is  the  case,  the  order 
only  being  reversed,  when  they  are  observed  from  the  other  side ; so  that  the  rule  is,  to  observe  them 
always  from  a position  exactly  opposite  the  board.  Practice  is  here  the  best  guide  in  forming  rules. 

The  usual  dimensions  of  a candle  are  not  fixed  arbitrarily  or  by  chance,  but  are  absolutely  necessary 
to  a well-regulated  process  of  combustion.  If  the  wick  is  too  large  in  proportion  to  the  surrounding 
mass  of  fat,  as  is  the  case  in  tapers,  no  reservoir  is  then  formed,  and  all  the  advantages  attending  it  are 
lost.  In  the  opposite  case,  which  applies  to  all  common  candles,  the  wick  which  is  rather  too  small 
produces  a flame,  whilst  the  outermost  layer  of  fat  is  beyond  the  sphere  in  which  fusion  is  going  on. 


ILLUMINATION. 


51 


A thin  ring-shaped  wall,  as  is  easily  observed  in  the  less  fusible  stearine  candles,  remains  erect  up  to  a 
certain  height,  and  is  very  objectionable  from  the  shadow  which  it  throws,  but  more  so  from  its  being 
gradually  undermined  and  falling  into  th%  reservoir,  which  it  overfills  and  causes  the  candle  to  gutter. 
When  it  has  once  overflowed,  the  evil  is  doubled,  for  all  the  fat  which,  by  overflowing,  has  formed 
ridges,  is  still  further  removed  from  the  region  of  the  flame.  In  night  lights,  made  of  stearine  or  wax, 
where  intensity  of  light  is  a secondary  consideration,  this  circumstance  has  been  turned  to  account. 
These  are  made  with  a common-sized  wick,  but  a disproportionate  thickness  of  fat,  so  that  a very  deep 
and  full  reservoir  is  formed ; an  excess  therefore  of  melted  fat,  which,  as  too  much  of  the  free  part  of  the 
wick  remains  immersed,  causes  them  to  give  a very  small  quantity  of  light.  For  the  sake  of  safety, 
they  are  made  so  short  that  they  will  swim  upright  upon  a basin  of  water.  Several  periods  must  be 
distinguished  in  the  whole  course  of  the  process  which  is  going  on  in  a lighted  candle.  The  heat  gen- 
erated by  the  flame,  and  for  the  greater  part  carried  upwards  by  the  current  of  air,  acts  however  by 
radiation  to  such  a degree  downwards,  that  sufficient  or  rather  too  much  fat  is  melted,  for  supplying 
food  to  the  flame.  The  fat  is  supplied  directly  by  the  wick,  the  capillarity  of  which  is  constantly  at 
work,  sucking  up  the  fluid  matter,  and  carrying  it  to  the  sphere  of  combustion.  The  lower  uncharred 
portion  of  the  wick  (up  to  d,  Fig.  2300)  acts  the  part  of  a sucking-pump ; the  decomposi-  23q0 

tion  takes  place  in  the  entire  upper  black  portion : the  fat,  which  arrives  there,  is  im- 
mediately exposed  to  a high  temperature,  without  being  able  to  come  into  direct  contact 
with  the  air ; it  is  in  the  same  position  as  if  it  were  inclosed  in  an  iron  retort  between  red- 
hot  coals,  and  it  suffers,  consequently,  dry  distillation.  The  gaseous  and  vaporous  com- 
bustible products  form  the  dark  nucleus /of  the  flame,  between  which  and  the  surrounding 
air,  the  sphere  of  successive  combustion  is  situated.  The  air  streaming  from  below  up- 
wards, to  the  gases  in  f consumes  in  the  first  instance  the  hydrogen,  and  separates  the 
carbon  as  incandescent  soot ; this  occurs  in  the  luminous  part  of  the  flame  i.  Lastly,  on 
the  outside,  in  the  hardly  perceptible  bluish  halo  g,  the  carbon  is  consumed ; this  occurs 
chiefly  at  the  base,  which  does  not  appear  luminous,  in  consequence  of  the  air  exerting  its 
full  influence  at  that  part. 

Every  portion  of  tallow,  which  burns  and  gives  out  light,  prepares  the  following  portion 
for  undergoing  the  same  process.  The  different  states  of  the  flame  may  be  partially  made 
visible  by  an  interesting  experiment  that  is  easy  of  execution.  If  a bottle  is  filled  with 
water,  and  supplied  through  the  cork  with  a siphon  in  a downward  direction,  and  a tube 
drawn  out  to  a point  in  an  upward  direction,  and  this  point  be  brought  into  the  interior  of 
tire  flame  whilst  the  water  is  allowed  to  run  slowly  from  the  siphon,  the  bottle  becomes 
filled  with  the  combustible  vapors  in  the  form  of  a gray  smoke.  The  vapors  obtained  from  a stearine 
candle  condense,  for  the  most  part,  to  a dry,  solid,  fatty  acid ; not  so  those  from  oil  or  tallow.  On  blow- 
ing with  the  mouth,  these  vapors  may  be  exp>elled  from  the  bottle,  and  they  burn,  when  ignited,  with  a 
distinct  flame,  which  is  but  slightly  luminous,  in  consequence  of  the  admixture  of  ah'.  The  experiment 
may  be  made  without  danger  with  a common  pipe,  and  by  suction  with  the  mouth.  The  importance  of 
using  hard,  solid  tallow,  to  prevent  guttering,  is  obvious,  and  all  the  materials  should  likewise  be  as 
pure  as  possible  ; for  whatever  is  not  decomposed  in  the  same  manner  as  tallow,  or  wax,  will  obstruct 
the  capillary  tubes  of  the  wick. 

It  is  not  remarkable  from  the  nature  of  candles  and  the  mode  in  which  they  disseminate  light,  that 
their  intensity  and  consequent  power  of  illumination,  even  under  the  same  circumstances,  should  be  so 
very  variable.  In  the  beginning,  when  the  wick  is  freshly  snuffed,  this  variation  is  comparatively  slight, 
and  the  intensity  increases  up  to  a certain  point,  when,  from  an  excessive  length  of  snuff,  deposit  of 
spongy  matter,  <fec.,  it  constantly  diminishes,  until  the  candle  is  again  snuffed  or  the  deposit  burnt,  and 
then  the  process  is  repeated.  Peclet  found  (by  comparison  with  Carcel’s  lamp)  that  the  primary  inten- 
sity of  a candle  = 100,  (6  = 1 lb.,)  became  in  4 minutes  92,  in  8 minutes  50,  in  10  minutes  41,  in  12 
minutes  38,  in  15  minutes  34,  in  20  minutes  32,  in  22  minutes  25,  in  24  minutes  20,  in  28  minutes  19, 
in  30  minutes  17,  and  in  40  minutes  14.  Another  candle,  (5  to  the  lb.,)  diminished  from  its  original 
intensity,  = 100,  in  5 minutes  to  76,  in  10  to  55,  in  15  to  44,  in  20  to  89,  in  25  to  32,  iu  30  to  30,  in  35 
to  24,  and  lastly,  in  40  minutes  to  15.  Less  than  half  an  hour,  therefore,  is  sufficient  to  reduce  the  light 
from  a candle  to  -I  of  its  original  brilliancy.  The  same  diminution  was  the  result  of  Rumford’s  observa- 
tions, namely,  after  29  minutes.  When,  below,  the  intensity  of  candles  is  compared  with  Oarcel’s 
lamp,  the  mean  intensity  of  10  minutes’  duration  in  tallow  candles  is  to  be  understood,  which  is  about 
the  usual  time  suffered  to  elapse  between  each  snuffing ; in  stearine,  wax,  and  spermaceti  candles,  how- 
ever, the  highest  intensity  is  taken,  which  occurs  when  the  wick,  without  any  deposition  of  snuff,  has 
begun  to  emerge  from  the  flame. 

It  has  already  been  pointed  out,  that  all  determinations  of  the  illuminating  power  are  entirely  rela- 
tive, and  hence  arises  the  demand  for  a suitable  point  of  comparison. 

The  flame  of  Carcel’s  clock-work  lamp  (see  Lamps)  is  of  such  very  uniform  brilliancy,  remaining  un- 
impaired for  several  hours  after  it  has  been  ignited,  that  lamps,  candles,  and  gas,  are  very  generally 
compared  with  it.  On  comparing  two  exactly  similar  lamps  of  this  kind  in  such  a manner,  that  one 
was  kept  constantly  burning,  whilst  the  other  was  freshly  ignited  for  each  observation,  it  was  found  that 
the  brilliancy  which  in  the  beginning  was  100,  increased  in  half  an  hour  to  103  ; in  one  hour  to  116, 
*nd  in  four  hours  to  117,  which  it  then  retained  for  four  consecutive  hours 


INCIDENCE. 


d2 


Illuminating  Pov:er  of  Candles. 


Variety  of  Candle. 

Comparison  of 
the  intensity 
of  light. 

• 

Consumption 
of  material  in  an 
hour. 

Comparison  of  illuminating  power  ! 

Directly. 

With  Carcel’s 
lamp  =100. 

[Carcel’s  lamp 

Tallow  candles,  6s  

“ “ 8 s 

100-00 

10-66 

8-74 

7-50 

13- 61 

14- 40 
11-40 

42-00  raPefed 

oil. 

8-51 

7'51 

7- 42 

8- 71 

9- 33 
8-92 

2-318 

1-253 

1-164 

1-011 

1-563 

1-543 

1-614 

100] 

54-04 

50-21 

43-61 

67-41 

66-58 

85’68 

“ “ 5s  

Wax  “ 5s  

Stearine  “ 5s  

Spermaceti  5s  

Illuminating  Power  of  Lamps. 


Sort  of  Lamp. 

Breadth  of  the 
wick,  or  diameter 
of  the  burner. 

Inner.  | Outer. 

Average 
intensity  of 
light  from 
twelve  ex- 
periments. 

Consump- 
tion of  rape- 
seed  oil  in 
one  hour  in 
grammes. 

Quantity  of 
light  from 
an  equal 
quantity  of 
oil,  CarcePs 
lamp  =101). 

No.  I.  Carcel’s  clock-work  lamp 

Lines. 

68  I 92 

100 

40-64 

100 

...  II.  Kitchen  lamp  

3-2 

(thick) 

6-65 

8-05 

33-5S 

. . . III.  Lamp  with  flat  wick 

8-2 

(broad) 

15-13 

9-40 

65-71 

...  IV.  Lamp  with  chimney 

7 

G 

19-37 

12-33 

63-82 

...  Y.  Table  lamp  with  circular  oil- vessel,  and  semi- 
circular wick 

12 

•5 

32-64 

20-88 

63-54 

...  VI.  Astral  lamp 

6-2 

9-4 

44-98 

28-70 

63-72 

...  VII.  Sinumbra  lamp 

5-2 

8-8 

52-50 

26-74 

79-78 

...  VIII.  Lamp  with  flat  wick  and  invert’d  reservoir 

8'4  (broad) 

21'50 

14-90 

54-80 

...  IX.  Wall  lamp  with  inverted  reservoir  and  semi- 
circular wick 

13-0 

39-33 

2015 

79-35 

...  X.  The  same  with  round  wick 

7-4 

io-o 

52-54 

29-33 

72-81 

...  XI.  Liverpool  lamp  with  inverted  reservoir 

60 

9-2 

41-80 

26-78 

63-45 

...  XII.  Wall  lamp  with  constant  oil  level  and 
regulator 

5-8 

8-0 

82-46 

35  44 

111-60 

. . . XIII.  Hydrostatic  lamp  

7-4 

9-2 

92-44 

38-94 

113-90 

(See  Lamps,  Light.) 

IMPACT.  The  single  instantaneous  blow  or  stroke  communicated  from  one  body,  in  motion,  to  an- 
other, either  in  motion  or  at  rest. 

IMPENETRABILITY.  In  physics,  one  of  the  essential  properties  of  matter,  or  body.  It  is  a prop- 
erty inferred  from  invariable  experience,  and  resting  on  this  incontrovertible  fact,  that  no  two  bodies 
can  occupy  the  same  portion  of  space  in  the  same  instant  of  time.  Impenetrability,  as  respects  solid 
bodies,  requires  no  proof ; it  is  obvious  to  the  touch.  With  regard  to  liquids,  the  property  may  be 
proved  by  very  simple  experiments.  Let  a vessel  be  filled  to  the  brim  with  water,  and  a solid  incapa- 
ble of  solution  in  water  be  plunged  into  it ; a portion  of  the  water  will  overflow  exactly  equal  in  bulk 
to  the  body  immersed.  If  a cork  be  rammed  hard  into  the  neck  of  a vial  full  of  water,  the  vial  will 
burst,  while  its  neck  remains  entire.  The  disposition  of  air  to  resist  penetration  may  be  illustrated  in 
the  following  way : Let  a tall  glass  vessel  be  nearly  filled  with  water,  on  the  surface  of  which  a lighted 
taper  is  set  to  float.  If  over  this  glass  a smaller  cylindrical  vessel,  likewise  of  glass,  be  inverted  and 
pressed  downwards,  the  contained  air  maintaining  its  place,  the  internal  body  of  the  water  will  descend, 
while  the  rest  will  rise  up  at  the  sides,  and  the  taper  will  continue  to  burn  for  some  seconds,  encom- 
passed by  the  whole  mass  of  liquid. 

IMPETUS.  The  product  of  the  mass  and  velocity  of  a moving  body,  considered  as  instantaneous,  in 
distinction  from  momentum,  with  reference  to  time,  and  force,  with  reference  to  capacity  of  continuing 
its  motion.  Impetus,  in  gunnery,  is  the  altitude  through  which  a heavy  body  must  fall  to  acquire  a 
velocity  equal  to  that  with  whicn  the  ball  is  discharged  from  the  piece. 

INCIDENCE,  in  mechanics,  is  used  to  denote  the  direction  in  which  a body,  or  ray  of  light,  strikes 
another  body,  and  is  otherwise  called  inclination.  In  moving  bodies  their  incidence  is  said  to  be  per- 
pendicular or  oblique,  according  as  their  lines  of  motion  make  a straight  line  or  an  angle,  at  the  point 
of  contact. 

Angle  of  incidence,  generally  denotes  the  angle  formed  by  the  line  of  incidence,  and  a perpendicular 
drawn  from  the  point  of  contact  to  a plane  or  surface  on  which  the  body  or  ray  impinges. 

Thus  if  a body  impinges  on  the  plane  at  a point,  and  a perpendicular  be  drawn,  then  the  angle  made 
by  this  perpendicular  and  the  incident  ray  is  generally  called  the  angle  of  incidence,  and  the  comple- 
ment of  this  the  angle  of  inclination. 

When  light,  or  any  elastic  body,  is  reflected  from  a surface,  the  angle  of  incidence  is  equal  to  the 


INDICATORS. 


53 


angle  of  reflection;  and  in  the  case  of  refraction,  the  sine  of  the  angle  of  incidence  has  to  the  sine  of  the 
angle  of  refraction  a constant  ratio. 

INCLINATION,  denotes  the  mutual  approach  or  tendency  of  two  bodies,  lines,  or  planes,  towards  each 
other,  so  that  the  lines  of  their  direction  make  at  the  point  of  contact  an  angle  of  greater  or  less  magnitude. 

INCLINED  PLANE.  One  of  the  mechanical  powers:  a plane  which  forms  an  angle  with  the  ho- 
rizon. The  force  which  accelerates  the  motion  of  a heavy  body  on  an  inclined  plane,  is  to  the  force  of 
gravity,  as  the  sine  of  the  inclination  of  the  plane  to  the  radius,  or  as  the  height  of  the  plane  to  its 
length.  If/=  force  accelerating  the  body  on  an  inclined  plane,  of  which  the  inclination  is  i,  and  if 
g = force  of  gravity,  f = ff  sine  i.  Hence  the  motion  of  a body  on  an  inclined  plane,  is  a motion  uni- 
formly accelerated. 

If  two  bodies  begin  to  descend  from  rest,  and  from  the 'same  point,  the  one  on  an  inclined  plane  and 
the  other  falling  freely  to  the  ground,  their  velocities  at  all  equal  heights  above  the  surface  will  be 
equal.  Hence  the  velocity  acquired  by  a body  in  falling  from  rest  through  a given  height  is  the  same, 
whether  it  fall  freely,  or  descend  on  a plane  any  how  inclined.  The  space  through  which  a body  will 
descend  on  an  inclined  plane,  is  to  the  space  through  which  it  would  fall  freely  in  the  same  time,  as  the 
sine  of  the  inclination  of  the  plane  to  the  radius. 

When  a power  acts  on  a body,  on  an  inclined  plane,  so  as  to  keep  that  body  at  rest,  then  the  weight, 
the  power,  and  the  pressure  on  the  plane,  will  be  as  the  length,  the  height,  and  the  base  of  the  plane, 
when  the  power  acts  parallel  to  the  inclined  surface ; that  is, 

If  the  weight  be  measured  by  A 0, 

The  power  will  be  measured  by  B 0, 

And  the  pressure  on  the  plane  A B. 

These  properties  give  rise  to  the  following  rules : — 


2301. 


weight  X height  of  plane 

power  = — ^ 1 

length  ot  plane 

. , power  X length  of  plane 

weight  = c- ^-rr-S— — - 

height  ot  plane 

, weight  X base  of  plane 

pressure  on  the  plane  = — 1 — 

length  of  plane 


A 


These  rules  express  the  conditions  of  equilibrium,  and  it  is  obvious,  that  if  either  the  weight  or  the 
power  be  increased,  (friction  excepted,)  motion  of  the  body  must  ensue. 

When  the  power  does  not  act  parallel  to  the  plane,  the  conditions  of 
equilibrium  may  be  found  thus  : Draw  a line  perpendicular  to  the  direction 
of  the  power's  action ; the  weight,  power,  and  pressure  on  the  plane,  will 
be  as  A C,  C B,  A B. 

When  the  line  of  direction  of  the  power  is  parallel  to  the  plane,  the 
power  is  least. 

If  two  bodies,  on  two  inclined  planes,  sustain  each  other  by  means  of  a 
string  over  a pulley,  their  weights  will  be  inversely  as  the  lengths  of  the 
planes. 

The  space  which  a body  descends  upon  an  inclined  plane,  when  descending  on  the  plane  by  the  force 
of  gravity,  is  to  the  space  which  it  would  fall  freely  in  the  same  time,  as  the  height  is  to  the  length  of 
the  plane ; and  the  spaces  being  the  same,  the  times  will  be  inversely  hi  that  proportion. 

INDICATORS.  The  important  and  useful  little  instrument  which  we  have  represented  in  the  fol- 
lowing figures  has  very  materially  contributed  to  the  perfection  and  efficiency  of  our  modern  steam- 
engines ; not  only  by  enabling  the  engineer  to  ascertain  and  register  the  exact  values  of  the  forces  from 
which  its  power  is  derived,  at  the  point  where  these  forces  come  into  effective  operation,  but  also  by 
pointing  out  the  precise  periods,  in  relation  to  the  different  parts  of  the  stroke,  at  which  these  elements 
of  power  come  into  action,  and  thereby  conducing  to  the  most  economical  and  perfect  combination  of 
them.  By  its  use  he  is  introduced,  as  it  were,  into  the  interior  of  his  engine,  and  is  made  cognizant  of 
its  most  occult  and  delicate  movements. 

The  idea  embodied  in  this  ingenious  and  beautiful  instrument  was  originated  by  the  justly  celebrated 
James  Watt,  who,  at  a very  early  period  in  the  history  of  the  steam-engine,  employed  a machine  iden- 
tical in  the  principle  of  its  operation,  though  less  compact  in  form  than  that  now  so  extensively  in  use. 
His  object  was  to  ascertain  with  certainty  the  mean  steam  pressure,  and,  more  particularly,  the  propor- 
tion which  the  vacuum  in  the  cylinder  bore,  at  different  parts  of  the  stroke,  to  that  in  the  condenser,  in 
order  to  determine  the  dimensions  of  cylinder  required  for  any  given  power,  as  also  the  relative  pro- 
portions proper  to  be  given  to  the  steam  and  exhaust  ports,  Ac.  Having  attained  these  objects,  and 
given  to  the  world  so  many  imperishable  monuments  of  his  genius,  succeeding  mechanicians  seem  to 
have  despised  the  unpretending  little  instrument  by  whose  assistance  he  had  been  led  to  such  splendid 
results,  and,  during  the  space  of  nearly  half  a century,  to  have  trusted  implicitly,  in  the  construction  of 
(heir  engines,  either  to  the  absolute  accuracy  of  Watt’s  data,  or  of  their  own  theoretical  deductions,  in 
many  cases  extremely  fallacious.  From  this  state  of  oblivion,  the  indicator  has  been,  at  a comparatively 
recent  period,  rescued  by  the  late  Mr.  Macnaught,  of  Glasgow,  who  has  greatly  improved  its  construc- 
tion, and  put  it  into  such  a compact  and  portable  form  as  to  be  easily  applicable  to  steam-engines  of 
every  description.  Its  consequent  general  adoption  has  led  to  some  notable  improvements,  and  mate- 
rially elevated  the  standard  of  duty  in  steam-engines ; it  has  demonstrated  the  economy  resulting  from 
a liberal  use  of  the  expansive  power  of  the  steam,  and  the  great  advantage  attendant  upon  a more 
rapid  and  complete  exhaustion  than  could  be  attained  by  the  arrangement  of  slide-valve  previously 
employed. 


54 


INDICATORS. 


Macnamght' s Indicators. — The  figure  comprised  under  this  head  represents  the  form  of  the  indicator 
as  at  present  constructed  by  Mr.  William  Macnaught,  being  that  employed  to  measure  the  power  ol 
high-pressure  engines,  and  is  also  adapted  to  those  hi  which  steam  of  a tension  not  greatly  exceeding 
that  of  the  atmosphere  is  employed.  The  two  instruments  differ  in  no  respect  from  each  other  in  the 
principle  of  then  action,  and  but  little  in  the  details  of  their  construction ; accordingly  one  description 
will  suffice  for  both,  in  the  course  of  which  we  shall  notice  the  points  in  which  each  respectively  differs 
from  the  other.  The  figures  are  to  a scale  of  I of  an  incli  to  an  inch. 

General  description. — From  a glance  at  the  drawings  it  will  be  at  once  perceived  that  the  indicator 
is  neither  more  nor  less  than  a small  atmospheric  steam-engine,  with  the  addition  of  a spiral  spring 
and  graduated  scale  to  mark  the  degrees  of  pressure.  The  steam-cylinder  A,  Fig.  2303,  is  of  gun- 
metal,  very  accurately  bored  out  and  fitted  with  a solid  piston  a,  ground  into  the  cylinder  so  as  to  be 
perfectly  steam-tight.  A slender  steel  rod  b b is  screwed  into  the  piston,  and  is  guided  at  its  upper  ex 
tremity  by  passing  through  the  cover  c of  an  external  brass  casing  or  cylinder  B,  screwed  to  the  lower 
end  of  the  steam-cylinder.  At  this  point  is  also  fixed  a stop-cock  C,  destined  to  form  a communication 
between  the  cylinder  of  the  steam-engine  and  that  of  the  indicator ; in  the  high-pressure  indicator  this 
cock  is  formed  with  a screw  at  its  lower  end,  for  the  purpose  of  attaching  it  to  the  socket-cock,  which  is 
permanently  fixed  to  the  cylinder  cover,  while,  in  the  instrument  as  adapted  to  low-pressure  engines, 
this  attachment  is  considered  to  be  sufficiently  secure  by  the  more  convenient  method  of  simply  inser* 
ing  the  tapered  end  of  the  cock  C into  a corresponding  socket  accurately  ground  to  fit  it. 


.towards  the  middle  of  the  piston-rod  b b a small  stud  d is  fixed  immovably  by  soldering,  and  to  it  is 
screwed  a brass  disk,  having  the  end  of  a spiral  spring  D soldered  into  it.  The  opposite  extremity  ol 
this  spring  is  secured,  in  the  case  of  the  high-pressure  indicator,  to  the  steam-cylinder,  and  in  that 
used  for  condensing  engines,  to  the  cover  of  the  external  casing.  This  difference  in  the  arrangement 
of  the  springs  is  owing  to  the  difference  in  the  prevailing  directions  of  the  motion  of  the  piston  a,  in 
either  case ; it  being  considered  most  expedient  to  make  the  springs  act  by  distension,  rather  than  by 
compression.  In  the  stud  is  a small  square  socket,  into  which,  through  a slot  or  opening  in  the  ex- 
ternal casing  B,  is  inserted  a steel  piece,  part  of  which  is  formed  into  an  index  or  pointer,  adapted  to 
work  against  an  adjustable  graduated  scale,  screwed  to  the  outside  of  the  casing  B,  Fig.  2301. 

Figs.  2305  and  2306  represent  plans  of  2303  and  2304  respectively. 

The  principle  on  which  the  strength  of  the  springs  is  regulated  and  the  scales  are  graduated  is  as 
follows : The  area  of  the  piston,  the  resistance  of  the  spring,  and  the  divisions  upon  tlie  scale,  are  so 
proportioned  to  each  other  that  one  pound  of  pressure  in  either  direction  upon  the  piston  will  cause  the 
sidex  to  move  through  one  division  upon  the  scale.  In  the  high-pressure  indicator,  although  the  size  ol 


INDICATORS. 


55 


the  piston  is  invariable,  (being  uniformly  made  equal  to  J of  a square  inch  in  area,)  the  length  of  the 
divisions  upon  the  scale  is  arbitrary,  being  determined  by  the  amount  of  steam  pressure  to  which  the 
machine  may  at  any  time  be  subjected,  and  by  the  length  of  scale  that  can  conveniently  be  applied. 
The  instrument  represented  in  the  figures  is  adapted  to  indicate  up  to  60  pounds  of  pressure,  and  the 
scale  is  equally  divided  into  20ths  of  an  inch,  each  of  these  divisions  representing'  one  pound  of  pressure 
upon  the  square  inch  of  the  piston.  From  these  data  the  spring  is  to  be  very  carefully  constructed,  so 
that  2 ounces  (or  § of  a pound)  will  move  the  index  through  one  division  of  the  scale. 

In  the  low-pressure  indicator  the  process  is  precisely  the  same  in  principle,  though  somewhat  lesc 
involved.  The  tension  of  the  steam  being  low,  and  the  atmospheric  pressure  limited  within  15  pounds 
to  the  square  inch,  the  scale  is  divided  into  lOths  of  an  inch.  The  piston  is  made  equal  to  -J  of  a square 
inch  in  area,  and  the  elasticity  of  the  spring  is  such  that  4 ounces  (or  \ of  a pound)  acting  upon  the 
piston  in  either  direction,  will  cause  the  index  to  move  througli  one  division  of  the  scale,  which,  conse- 
quently, represents  one  pound  of  pressure  upon  the  piston  of  the  steam-engine  to  which  this  instrument 
is  applied.  The  zero-point  is  that  at  which  the  index  stands  when  the  cock  C is  shut  and  the  piston  a 
remains  undisturbed,  and,  therefore,  when  the  instrument  is  in  action,  it  denotes  that  point  in  the  stroko 
at  which  the  pressures  above  and  below  the  piston  are  balanced. 

From  these  explanations  it  will  be  obvious  that,  by  attaching  the  instrument  to  the  cylinder  of  a 
steam-engine,  and  observing  the  motion  of  the  index  upon  the  scale,  the  maximum  steam  pressure  and 
vacuum  may  be  at  once  ascertained.  But  this  is  not  the  only,  nor  even  the  most  important  function  of 
the  indicator.  It  was  desirable  to  find  out  the  exact  periods  and  modes  in  which  these  two  elements  of 
power  come  into  operation,  and  especially  the  mean  effective  values  of  each  ; the  rapidity  of  the  motion 
through  so  short  a space  precluding  the  possibility  of  taking  these  observations  with  any  degree  of  ac- 
curacy. These  important  objects  are  fully  attained  by  the  help  of  a simple  and  beautiful  contrivance, 
by  which  the  instrument  is  made  to  register  its  own  performances. 

An  arm  or  bracket  g is  firmly  attached  to  the  indicator  by  being  clamped  to  the  external  casing  B 
on  which  it  may  be  set  to  any  convenient  elevation,  and  there  secured  by  a screw.  To  this  bracket  is 
riveted  an  upright  axis,  on  which,  by  a long  socket,  to  insure  steadiness  of  motion,  is  accurately  fitted 
a cylindrical  piece  F,  formed  into  a pulley  at  its  lower  end.  The  other  extremity  of  the  socket  carries 
a small  cylindrical  box  containing  a spiral-spring  similar  to  the  main-spring  of  a watch,  and  attached 
at  one  end  to  the  fixed  axis,  and  at  the  other  to  the  internal  surface  of  the  box  in  which  it  is  inclosed. 
The  bracket  g carries  also  a small  friction-pulley  j,  for  the  purpose  of  guiding  a cord  wrapped  round 
and  attached  to  the  pulley  F,  to  any  convenient  moving  part  of  the  engine  ; a small  catch  screwed 
into  the  latter,  serving  to  circumscribe  its  motion  to  a single  revolution.  An  external  cylinder  or  drum 

E,  which  may  be  withdrawn  from  the  instrument  at  pleasure,  is  fitted  over  the  revolving  cylindrical  piece 

F,  so  as  to  partake  of  its  motion,  and  upon  it  is  fixed  a slip  of  brass  formed  into  a double  spring  1 1,  Fig. 
2304,  for  the  purpose  of  securing  the  slip  of  paper  on  which  the  instrument  is  to  register  its  performance. 
This  is  effected  by  means  of  a pencil 
f placed  in  a holder  e,  jointed  to  the 
piece  of  steel  on  which  the  index  or 
pointer  is  formed,  and  fitted  with  a 
small  spring,  so  as  to  press  the  point 
of  the  pencil  gently  against  the  paper 
cylinder,  or  admit  of  its  being  with- 
drawn from  contact  with  it  at  plea- 
sure. From  these  arrangements  it 
will  be  seen  that  if  the  piston  a be 
moved  up  and  down,  while  the  pencil 
is  in  contact  with  the  cylinder  E,  a 
straight  line  will  be  traced  upon  it  in 
the  direction  of  its  length  ; and  if,  on 
the  other  hand,  the  cylinder  be  made 
to  turn  upon  its  axis  by  pulling  the 
cord,  while  the  piston  remains  at  rest, 
a straight  line  will  be  traced  round 
it  at  right  angles  to  the  former.  By 
the  combination  of  these  two  motions 
when  the  instrument  is  in  operation, 
a diagram  is  produced,  which  repre- 
sents the  performance  of  the  engine 
at  all  parts  of  its  stroke. 

Action  of  the  instrument.  — The 
rock  C is  inserted  into  the  correspond- 
ing socket  prepared  for  its  reception, 
and  the  cord  which  passes  under  the 
pulley  j is  attached  to  the  radius-bar 
or  other  moving  part  of  the  engine,  so 
as  to  cause  the  cylinder  E to  make 
one  revolution  on  its  axis,  coincident 
with  and  representing  the  stroke  of  the  engine ; on  the  relaxation  of  the  cord  at  the  termination  of  the 
up  stroke,  it  is  taken  up  again  by  the  action  of  the  spring  in  the  upright  of  the  cylinder  F,  and  the  cylin- 
der E resumes  its  original  position.  The  slip  of  paper  is  then  wrapped  tightly  round  the  cylinder,  its 
ends  being  secured  by  the  pressure  of  the  two  springs  1 1.  These  arrangements  made,  the  pencil  f is 
turned  down  into  contact  with  the  paper,  and  the  engine  allowed  to  make  a stroke  or  two  with  the  cock 


56 


INDICATORS. 


C shut,  so  as  to  form  an  atmosphere  line.  A communication  is  then  opened  with  the  interior  of  the  cyl 
inu^r  of  the  engine  by  turning  the  cock  C,  and  a figure  or  diagram  is  traced  upon  the  slip  of  paper,  ex- 
acUy  representing  the  successive  pressures  of  the  steam  above,  and  corresponding  degrees  of  exhaustion 
below  the  atmosphere  line,  at  every  part  of  the  stroke.  To  find  the  mean  effective  values  of  each  of 
these  pressures  respectively,  the  figure  is  to  be  divided,  in  the  direction  of  its  length,  into  any  number 


of  equal  parts,  the  perpendicular  distances  of  the  outline  of  the  diagram  above  and  below  the  atmos 
phere  line  at  each  of  these  points,  to  be  carefully  measured  upon  the  scale  of  the  instrument,  and  th« 
sum  of  these  to  be  divided  by  the  number  of  points  taken.  Hence  the  actual  power  of  the  engine  is 
easily  calculated. 


STorin's  Indicator. — That  eminent  French  mechanician,  M.  Arthur  Morin,  conceiving,  with  reason,  that 
considerable  inaccuracy  was  likely  to  result  from  the  difficulty  of  constructing  the  spiral  springs  in 
Macnaught’s  indicator,  so  as  at  all  parts  of  the  stroke  to  denote  equal  pressures  by  equal  divisions ; 
and,  moreover,  considering  it  desirable  to  ascertain  with  greater  precision  the  mean  pressures  and  conse- 


INDICATORS. 


57 


quent  actual  power  of  engines  by  taking  indications  throughout  several  consecutive  strokes,  has  in- 
vented a machine  by  which  the  former  difficulty  is  obviated,  and  the  latter  object  is  attained.  This 
instrument  we  have  represented  in  the  accompanying  figures. 

Fig  2307  is  a side  elevation,  Fig.  2308  an  end  elevation,  and  Fig.  2309  a plan  of  the  machine. 

This  indicator,  like  that  we  have  already  described,  is  adapted  for  being  fitted  to  the  cylinder  covet 
of  the  engine  ; it  carries  a stop-cock  pipe  G,  furnished  with  two  keys ; between  these  is  situated  a small 
horizontal  cylinder  H,  in  which  a solid  piston  is  accurately  fitted  to  work  steam-tight.  Towards  the 
middle  of  the  piston-rod  m,  which  is  properly  guided  to  a rectilinear  course,  is  a square  part  in  which 
is  inserted  the  lower  end  of  a long  parabolic  spring  n,  the  other  extremity  of  which  is  fixed  to  the  sum- 
mit of  a standard  I,  forming  part  of  the  frame-work  of  the  machine,  the  spring  being  so  fitted  as  to 
admit  of  a certain  amount  of  travel  in  the  piston  in  both  directions.  The  square  boss  of  the  piston-rod 
carries  also  a small  pencil  o,  for  the  purpose  of  tracing  the  different  degrees  of  tension  of  the  steam  on 
the  opening  of  the  lower  cock  G. 

Two  pencils  pp  are  placed  in  holders  fixed  to  the  framing  exactly  opposite  to  the  point  at  which  the 
pencil  o stands  when  the  stop-cock  G is  shut,  and  being  thus  immovable,  serve  to  mark  a continuous 
atmosphere  line.  A third  pencil  q,  which  is  susceptible  of  a slight  degree  of  vertical  motion  in  its  socket, 
and  is  destined  to  mark  the  termination  of  each  stroke,  is  brought  into  contact  with  the  paper  by  placing 
the  instrument  so  that  the  working-beam,  cross-head,  or  any  other  rigid  part  of  the  engine  may  touch 
lightly  at  the  end  of  the  stroke,  the  top  of  an  upright  rod  u,  which  is  connected  by  a system  of  levers 
rst  with  the  top  of  the  pencil  q. 

A continuous  band  or  roll  of  paper  may  be  subjected  to  the  action  of  this  machine  for  an  indefinite 
period,  so  as  to  produce  diagrams  representing  the  action  of  the  engine  during  several  successive  strokes. 
The  manner  in  which  this  is  accomplished  is  as  follows : The  roll  of  paper  is  first  wound  upon  the  cyl- 
inder L,  by  means  of  the  handle  y ; it  is  then  passed  over  the  three  small  rollers  vvv  placed  to  oppose 
the  pressure  of  the  pencils,  and  is  received  upon  the  cylinder  M situated  at  the  opposite  end  of  the 
framing  Q Q.  The  axis  of  this  latter  cylinder  is  produced  on  one  side  so  as  to  form  also  the  axis  of  a 
conical  pulley  or  fusee  N,  opposite  to  which  is  situated  a cylindrical  drum  O,  which  receives  a uniform 
motion  from  any  rotating  part  of  the  engine  to  be  operated  on,  by  means  of  a worm-wheel  w on  its  axis, 
geering  with  an  endless  screw  on  the  axis  of  the  strap-pulley  P.  The  cylindrical  roller  0 communicates 
motion  to  the  conical  roller  1ST  by  a cord  wrapped  round  both,  and  fastened  at  opposite  extremities  of 
each.  The  object  of  this  arrangement  is  to  compensate  for  the  increased  surface  velocity  due  to  the 
increased  diameter  of  the  cylinder  M as  the  paper  is  wound  on  to  it,  by  imparting  to  it  a proportionally 
retarded  motion. 

This  instrument,  although  highly  ingenious  in  many  of  its  details,  and  capable  of  giving  very  correct 
indications,  is  wanting  in  that  portability  and  compactness  which  has  very  materially  contributed  to 
bring  Macnaught’s  instruments  into  such  general  use.  Moreover,  although  in  any  instrument  of  this 
nature  the  observations  will  be  more  or  less  accurate  in  proportion  as  the  space  through  which  the 
spring  is  made  to  act  is  more  or  less  limited,  yet  a considerable  advantage  results  from  the  length  of 
range  in  the  common  indicators.  The  diagrams  being  made  upon  a large  scale,  the  expert  engineer  is 
able,  at  a glance,  and  without  reference  to  the  scale,  to  ascertain  by  the  mere  contour  of  the  figure 
whether  his  engine  is  performing  all  its  functions  properly. 

The  indicator  of  the  steam-engine  appears  to  fulfil  two  distinct  and  very  important  ends. 

It  enables  us  to  discover  whether  there  are  any  defects  in  those  parts  of  the  machinery  by  which  the 
steam  is  admitted  to  the  piston ; for  instance,  it  indicates  whether  the  slides  are  properly  set,  or  leaky ; 
whether  the  stops  on  the  intermediate  shaft  are  properly  placed ; whether  the  steam-ports  are  large 
enough ; and,  consequently,  whether  a different  arrangement  of  the  working  part  of  the  machinery 
would  be  advisable.  In  fact,  in  the  hands  of  a skilful  engineer,  the  indicator  is  as  the  stethoscope  of 
the  physician,  revealing  the  secret  workings  of  the  inner  system,  and  detecting  minute  derangements  in 
parts  obscurely  situated. 

It  discovers,  at  any  instant  of  time,  and  under  any  given  circumstances,  when  it  may  be  desirable  to 
apply  it,  what  is  the  actual  power  of  the  engine. 

We  will  first  give  a description  of  the  instrument,  and  then  proceed  to  its  various  uses. 

Fig.  2310  is  an  external  view  of  the  indicator  as  constructed.  The  dotted  lines  are  intended  to  show 
the  internal  parts.  A is  a hollow  cylinder,  whose  upper  end  E H is  open;  the  lower  end  being  intended 
to  fit  into  an  orifice  in  some  part  of  the  engine  (generally  the  top  or  bottom  of  the  cylinder)  by  means 
of  the  screw  a ; b is  a stop-cock,  by  which,  when  the  instrument  is  attached,  we  can,  at  will,  make  or 
cut  off  a communication  with  the  internal  parts  of  the  engine.  Within  the  hollow  cylinder  A is  a piston 
in  n packed  and  fitting  steam-tight.  In  practice  this  piston  must  not  be  packed  over-tight,  for  fear  of 
increasing  the  friction  and  preventing  the  free  motion  of  the  pencil;  but  the  defect,  if  any,  must  be 
remedied  by  keeping  melted  tallow  or  oil  on  the  upper  surface. 

Let  us  suppose,  for  perspicuity,  the  instrument  to  be  in  communication  with  the  top  of  the  steam 
cylinder.  Then,  when  a vacuum  is  formed  above  the  steam-piston,  the  atmospheric  pressure  will  force 
down  the  piston  of  the  indicator,  and  it  will  remain  at  its  lowest  position  till  fresh  steam  enters ; but  it 
would  immediately,  (unless  prevented,)  on  receiving  a new  impulse,  be  blown  out  at  the  open  top  H E. 
To  prevent  this,  and  at  the  same  time  to  enable  us  to  measure  the  force  of  the  steam,  a spiral  spring 
presses  with  its  lower  extremity  against  the  surface  of  the  piston,  while  its  upper  end  rests  against  the 
fixed  cross-piece  c.  By  this  arrangement  the  pressure  of  the  steam  will  always  vary  as  the  place  of  the 
piston  varies  ; for  it  is  a mechanical  fact,  that  the  tension  of  a spring  varies  as  the  extension.  Hence, 
the  greater  the  pressure  of  the  steam,  the  more  the  spring  is  compressed ; and,  on  the  contrary,  as  the 
steam  loses  its  elastic  force,  the  spring  expands  and  the  piston  descends.  So  that,  to  get  a clear  idea  oi 
the  instrument,  conceive  the  piston  to  be  acted  on  by  opposing  forces ; on  the  lower  surface  by  the 
pressure  of  the  steam,  (continually  varying,)  and  on  the  upper  surface  by  the  pressure  of  the  atmos- 
phere, (constant,)  and  by  the  force  of  the  spring  varying  so  as  to  balance  the  steam-pressure  Now,  as 


58 


INDICATORS. 


the  steam-force  is  perpetually  varying,  it  follows  that  the  piston-tube  de  will  be  continually  rising  01 
falling.  If  a pencil  be  attached  to  the  upper  end  of  this  tube  d e,  iu  which  the  spring  works,  it  will 
describe  a vertical  straight  line  on  a piece  of  paper  brought  into  contact  with  it.  This,  however,  is  not 
sufficient  for  our  purpose.  It  would,  after  it  was  traced,  tell  us  the  maximum  and  minimum  pressure 
during  the  stroke ; but  the  pressure  at  any  particular  portion  of  the  stroke  would  still  be  undetermined. 
We  must,  therefore,  have  some  plan  similar  to  that  adopted  in  other  cases  where  the  vertical  motion  ol 
a pencil  under  particular  circumstances  is  to  be  tegistered.  In  all  such  instances,  the  paper  on  which 
the  variation  is  to  be  laid  down  is  drawn  horizontally  at  a certain  rate.  If,  for  instance,  we  were  desirous 
of  recording  how  the  pressure  varies  with  the  time,  the  paper  must  be  drawn  uniformly,  by  connecting 
it  with  clock-work,  or  some  other  apparatus  for  giving  a uniform  motion.  But  this,  however,  is  not 
usually  the  desideratum  in  the  steam-engine.  Our  object  is  here  to  have  represented  before  our  eyes 
the  variation  of  the  pressure  for  every  portion  of  the  stroke  of  the  piston ; and  this  is  contrived  as  fol- 


lows : the  paper  is  wrapped  round  a cylindrical  barrel  C,  which  is  brought  back  against  a stop  by  a 
strong  watch-spring  contained  in  the  box  E F.  A string  passes  round  the  pulley  D,  and  is  led  away 
through  a fair-leader  G to  some  part  of  the  engine  having  a similar  motion  to  the  piston  cross-head,  only 
much  reduced,  by  which  means  the  watch-spring  and  the  string  are  always  opposing  each  other.  As 
the  piston  rises,  the  barrel  will  be  pulled  from  left  to  right ; and,  on  the  contrary,  as  the  piston  descends 
the  string  having  a tendency  to  slacken,  the  barrel  will,  by  the  force  of  the  spring,  be  brought  back  from 
right  to  left.  Tire  pencil  is  attached  to  the  upper  end  of  the  tube  dg , and  rising  and  falling  with 
the  indicator  piston.  It  can  be  brought  into  contact  with  the  paper  on  the  barrel  C or  removed  from  it 
at  will,  by  means  of  the  joint  at  g.  The  rod  z,  and  another  one  on  the  opposite  side  of  the  cylinder, 
serve  as  guides  to  the  piston. 

The  paper  is  kept  on  the  barrel  by  means  of  a strip  of  metal,  which  also  serves  another  impor- 


INDICATORS. 


59 


taut  purpose.  It  will  be  seen  that  it  is  graduated,  beginning  from  zeio,  and  proceeding  upwards  and 
downwards.  Now  this  zero  is  the  level  at  which  the  pencil  stands  when  the  instrument  is  unconnected 
with  the  steam-engine,  and  therefore  acted  on  by  the  atmospheric  pressure  above  and  below  the  piston. 
The  pencil  will  be  seen  at  this  level  in  the  figure.  If  the  barrel  be  made  to  revolve  under  these  cir- 
cumstances, a horizontal  line  will  be  traced  out.  This  is  called  the  atmospheric  or  zero  line.  And, 
therefore,  the  pencil  will  also  be  at  this  level  whenever  the  steam,  taking  the  place  of  the  atmosphere 
below  the  piston,  exerts  the  same  pressure ; and,  consequently,  wherever  the  diagram  cuts  this  hori- 
zontal line,  the  pressure  of  the  steam  is  15  pounds  on  the  inch;*  when  on  the  level  of  the  marks 
1,  2,  3,  <fec.,  above  this  zero,  the  pressure  is  16,  17,  18,  (fee. ; and  when  on  the  level  of  the  marks  1,  2,  3, 
&c.,  below  this,  the  pressure  is  14,  13,  12,  <fec. 

The  atmospheric  line  should  not  be  drawn  till  after  the  diagram  is  taken ; because,  as  the  parts 
become  warm  by  the  steam,  slight  variations  occur  in  its  position,  depending  principally  on  the  altera- 
tion in  the  force  of  the  spring ; and  since  this  line  serves  as  the  origin  from  which  the  pressures  are 
dated,  it  is  necessary  to  have  it  laid  down  as  correctly  as  possible. 

The  small  hole  in  the  side  of  the  stop-cock  b serves  to  let  the  air  into  the  cylinder  A when  the 
steam  is  cut  off  by  the  stop-cock,  and  thus  enables  us  to  take  the  atmospheric  line ; it  enables  the  stop- 
cock to  perform  the  office  of  a four-way  cock ; for  by  turning  it  in  one  direction  we  allow  the  steam  to 
enter,  and  exclude  the  external  air,  and  by  turning  it  in  the  opposite  direction  we  admit  the  air  and 
exclude  the  steam. 

Having  an  indicator,  a diagram  is  obtained  by  looking  out  for  some  part  of  the  engine  whose  motion 
is  proportioned  to  that  of  the  steam-piston, j-  taking  care  that  the  space  moved  through  at  that  part 
shall  be  somewhat  less  than  the  circumference  of  the  traversing  barrel ; that  is  to  say,  whatever  be  the 
diameter  of  the  traversing  barrel,  let  the  movement  of  the  part  you  are  looking  for  be  not  greater  than 
three  times  this  diameter.  Fasten  a string  firmly  to  this  point,  and  have  a traversing  loop  in  the  loose 
end  of  the  string ; it  must  be  of  such  a length  that  it  may  be  connected  with  the  string  passing  round 
the  pulley  of  the  indicator.  Then  close  the  stop-cock  of  the  indicator,  and  fix  it  by  the  screw  a a to 
some  orifice  previously  prepared  in  the  top  or  bottom  of  the  cylinder.:];  Insert  the  pencil  you  intend  to 
use  in  the  small  hole  made  for  its  reception,  and  clamp  it  there.  The  pencil  should  be  hard,  and  have 
a fine  point,  to  give  as  clear  and  distinct  a line  as  possible.  Have  some  pieces  of  clean  writing-paper 
provided,  long  enough  to  be  brought  round  the  traversing  barrel  and  overlap  about  an  inch.  Wrap  a 
piece  smoothly  round  the  barrel,  and  fix  it  by  means  of  the  clasp  containing  the  scale.  Then  tear 
away  all  the  surplus  paper,  and  examine  what  remains,  to  see  if  it  be  quite  smooth ; for  if  there  be  any 
ridges  the  curve  will  have  an  irregular  appearance,  and  might  lead  us  to  suppose  some  of  the  geer  for 
working  the  slides  had  become  loose,  or  much  worn.  Next  wind  the  indicator  string  round  the  pulley 
of  the  barrel  D,  and  connect  the  hook  at  its  extremity  with  the  loop  of  the  string  attached  to  the  engine. 
Adjust  the  string  by  means  of  the  running  loop,  till  you  are  satisfied  of  the  motion  of  the  barrel ; al- 
lowing it  to  make  nearly  a whole  revolution,  but  examining  it  most  carefully  to  see  whether  it  becomes 
slack,  or  overtaut.  The  stop-cock  b may  now  be  opened  wide,  and  the  indicator-piston  will  immediately 
start  into  motion ; the  piston  must  be  well  lubricated,  to  reduce  the  friction  as  much  as  possible,  and  at 
the  same  time  to  prevent  leakage.  Let  the  instrument  work  for  a few  seconds,  to  allow  it  to  become 
thoroughly  heated ; and  when  it  has  arrived  at  the  same  temperature  as  the  steam-cylinder,  it  is  in  a 
fit  state  to  trace  its  diagram.  When  satisfied  of  the  working  of  the  machine,  take  hold  of  the  pencil 
when  it  comes  to  the  bottom  of  its  stroke,  and  bring  it  gently  into  contact  with  the  paper.  This  part  oi 
the  operation  requires  some  practice ; for  if  the  pencil  be  allowed  to  come  forward  too  rapidly,  the 
spring  at  g,  by  which  it  is  pressed  against  the  barrel,  will  break  the  point;  and  again,  if  held  too  long, 
the  force  of  the  steam,  suddenly  acting  on  the  machine,  will  tear  it  out  of  the  hand,  or  break  the  bolder. 
When  left  to  itself,  it  will  trace  out  its  curve  on  the  paper.  As  soon  as  it  has  made  a complete  circuit, 
let  the  pencil  be  withdrawn  from  the  paper,  (being  again  careful  to  take  hold  of  it  when  at  the  bottom 
of  its  stroke.)  In  order  to  have  the  line  distinct,  the  pencil  should  not  go  over  the  same  ground  twice. 
Shut  off  the  stop-cock  and  the  piston  will  become  stationary,  both  sides  being  acted  on  by  the  pressure 
of  the  atmosphere.  Bring  the  pencil  again  in  contact  with  the  paper,  and  as  the  barrel  traverses,  the 
atmospheric  or  zero  line  will  be  drawn.  The  operation  is  now  complete,  so  far  as  the  curve  is  concerned. 
Withdraw  the  pencil  once  more,  unhook  the  line,  and  take  off  the  traversing  barrel.  Next  take  a fine- 
pointed  hard  pencil,  and  mark  off  upon  the  paper  the  scale  of  pounds,  beginning  with  the  atmospheric 
line,  and  proceeding  upwards  and  downwards.  After  taking  the  paper  from  the  barrel,  it  is  completed 
by  writing  on  it  the  date  of  the  month,  the  name  of  the  ship,  that  of  the  engine,  (whether  starboard  or 
port,)  top  or  bottom  of  cylinder,  as  the  case  may  be,  the  number  of  revolutions,  the  pressure  of  steam 
by  steam-gage,  and  of  condensation  by  barometer-gage. 

It  is  important  to  have  a running  loop,  or  other  means  of  shortening  or  lengthening  the  string  attached 
to  the  indicator.  Too  much  attention  cannot  be  paid  to  this  circumstance.  If  too  much  strain  be 
brought  upon  the  string  it  will  stretch,  and  if  the  string  be  too  long  it  will  become  slack ; and  in  either 
case  the  barrel  will  be  stationary  for  a small  interval  while  the  steam-piston  is  moving,  and  the  curve 
will  not  be  a true  indication  of  the  motion. 

It  is  well  known  that  the  pressure  of  the  steam  and  the  state  of  the  vacuum  on  the  diagram  do  not 
correspond  with  the  boiler-pressure  and  condenser-vacuum.  The  truth  is,  the  result  will  always  be  less. 
The  difference  will  depend  on  the  size  of  the  ports,  and  the  work  the  engine  has  to  do  ; the  distance 


* More  strictly,  14-75  pounds,  or  a quantity  differing  from  this  slightly,  according  to  the  state  of  the  weather, 
t That  is  to  say,  when  you  are  wishing  to  find  how  the  pressure  varies  with  the  stroke  of  the  engine. 

X If  the  top  of  the  cylinder  be  chosen,  the  orifice  for  the  grease-cup  will  generally  answer  the  purpose.  In  some  cases  a 
pipe  leads  from  the  top  to  the  bottom  of  the  steam-cylinder,  and  the  indicator  is  attached  to  this  pipe.  It  is  provided  with 
“top-cocks,  so  that  when  once  fixed  the  arrangement  is  very  convenient  for  taking  two  diagrams  almost  simultaneously 
from  the  upper  and  lower  part  of  t®  ■ cylinder.  The  only  objection  to  it  seems  to  consist  in  the  tendency  of  the  steam  to 
condense  in  the  pipe.  For  this  reason  it  is  advisable  to  have  the  indicator  as  close  to  the  cylinder  as  possible. 


30 


INDICATORS. 


the  steam  lias  to  travel,  the  impediments  it  meets  with  in  its  passage  from  the  boiler  to  the  cylinder, 
and  from  the  cylinder  to  the  condenser.  It  is  evident  that  the  diagram  taken  from  the  top  of  the  cyl- 
inder shows  only  the  pressure  and  vacuum  on  the  upper  surface  of  the  piston,  and  therefore  cannot 
indicate  what  is  going  on  below  the  piston.  If  our  object  be  merely  to  calculate  the  horse-power  of  the 
engine,  and  it  be  in  tolerably  good  working  condition,  it  is  not  of  much  consequence  whether  the  diagram 
be  taken  from  above  or  below;  but  if  the  actual  state  of  the  engine  be  required,  it  is  necessary  to  ex- 
amine into  what  is  passing  both  above  and  below  the  piston,  because  the  errors  in  one  part  may  have 
no  connection  with  the  errors  in  another.  This  will  be  the  case  if  the  slide  is  too  long  or  too  short,  so 
that  the  upper  part  may  be  properly  covered,  and  the  lower  one  disarranged ; or  the  upper  slide  may 
be  steam-tight,  and  the  lower  one  leaky ; and  if  the  indicator  be  applied  to  top  and  bottom,  it  will  de- 
tect all  these  inaccuracies,  and  prevent  our  attempting  to  improve  the  working  of  one  end  to  the  detri- 
ment of  the  other.  It  ought  to  be  remarked  here,  that  in  unbalanced  engines  the  diagram  from  below 
the  piston  is  generally  superior  to  the  other;  because,  since  the  steam  has  more  work  to  accomplish,  the 
piston  does  not  run  away  from  the  steam  so  readily,  and,  in  consequence,  the  steam-pressure  is  better 
maintained ; and  there  is  generally  a little  more  lead  to  the  slide,  to  allow  a freer  ingress  to  the  steam. 
And,  therefore,  if  great  accuracy  be  required,  the  mean  of  the  top  and  bottom  diagrams  should  be  taken 
for  the  horse-power.* * * § 

The  string  carrying  the  running  loop  must  not  be  attached  to  any  part  of  the  engine  indiscriminately. 
Generally  speaking,  we  wish  to  obtain  the  pressure  of  the  steam  for  different  portions  of  the  stroke  ol 
the  piston ; therefore,  the  string  must  be  fastened  to  some  part  of  the  engine  having  a stroke  propor- 
tioned to  that  of  the  piston,  only  much  reduced.  The  part  selected  must  be  as  near  the  indicator  as 
other  circumstances  will  permit ; for  the  greater  the  distance  the  longer  the  string,  and  consequently 
the  greater  is  the  chance  of  error  from  its  stretching.  Caution  must  be  used  also  to  prevent  the  string 
from  slipping  on  the  rod  to  which  it  is  attached.  One  of  the  best  contrivances  for  giving  a free  and 
proper  motion  to  the  string  is  to  fasten  a wooden  pulley  to  the  radius-shaft, \ to  the  groove  of  which  the 
fixed  end  of  the  string  can  be  connected.  It  will  be  necessary,  in  most  cases,  to  make  use  of  fair-leaders 
for  the  purpose  of  conveying  the  motion  from  the  part  chosen  to  the  indicator ; and  due  regard  must  be 
paid  to  this,  to  ascertain  whether  the  motion  of  the  engine  will  be  fairly  represented  by  the  indicator. 

We  must  bear  in  mind  that  all  vertical  ascending  motions  are  caused  by  an  increasing  pressure  oi 
the  steam,  and  that  the  descent  of  the  pencil  is  the  consequence  of  the  elasticity  becoming  diminished : 
and  again,  that  as  the  traversing  barrel  revolves  from  right  to  left,  the  piston  is  descending  ; while,  on 
the  contrary,  as  the  pencil  moves  from  right  to  left,  the  piston  is  ascending  hence  we  shall  arrive  at 
the  following  general  conclusions  : — 

1.  If  the  motion  of  the  pencil  be  vertically  upwards,  the  steam-pressure  is  increasing,  but  the  piston 
is  not  moving. 

2.  If  the  motion  be  downwards,  the  steam-pressure  is  decreasing,  but  the  piston  not  moving. 

8.  If  the  line  traced  be  horizontal  to  the  right,  the  steam-pressure  does  not  vary,  but  the  piston  is 
descending.^ 

4.  If  the  line  be  to  the  left,  the  steam-pressure  does  not  vary,  but  the  piston  is  ascending. 

5.  If  the  line  run  obliquely  to  the  right  upwards,  the  steam-pressure  is  increasing,  and  the  piston  is 
descending. \ 

6.  If  the  line  run  obliquely  to  the  right  downwards,  the  pressure  is  decreasing,  and  the  piston 
descending 4 

7.  If  the  line  run  obliquely  to  the  left  downwards,  the  pressure  is  decreasing,  and  the  piston 
ascending .% 

8.  If  the  line  run  obliquely  to  the  left  upwards,  the  pressure  is  increasing,  and  the  piston 
ascending .\ 

Let  us  refer  to  the  accompanying  diagram,  Fig.  2312,  taken  from  above  the  piston  of  an  American 
steamer,  and  explain  it. 

First,  we  will  put  numbers  round  the  diagram,  in  conformity  with  the  principles  laid  down  in  the  last 
paragraph.§  Then,  supposing  the  pencil  to  commence  at  A,  and  trace  out  the  curve  in  the  direction  of 
the  arrows,  we  see  that  the  steam  preserves  its  first  and  highest  pressure  for  a considerable  portion  ot 
the  stroke,  viz.  from  A to  C ; from  C to  B the  downward  stroke  continues,  but  the  steam  rapidly  loses 
its  pressure,  although  at  a variable  rate,  decreasing  rapidly  at  D.  At  B the  motion  of  the  piston  ceases, 
but  the  steam  continues  to  fall,  till  at  length  the  pencil  moves  back  nearly  horizontally  for  some  space, 
showing  the  pressure  to  continue  invariable,  although  the  piston  is  rising.  At  F,  however,  8 shows  the 
steam-pressure  to  increase  rapidly  and  suddenly,  the  piston  still  ascending,  till,  as  this  oblique  line 
merges  into  the  vertical  one  at  G,  we  perceive  that  the  piston  has  arrived  at  the  upper  end  of  its  stroke, 
and  the  fresh  influx  of  steam  drives  the  pencil  up  to  A.  From  this  point  the  pencil  will  retrace  the 
same  curve.  G D is  the  atmospheric  or  zero  line. 

When  the  pencil  is  at  G (or,  it  may  be,  rather  before  arriving  at  G)  the  slide  is  in  the  position  repre- 
sented at  Fig.  2311,  and  is  rising,  so  that  the  steam  is  about  to  enter  the  cylinder.  Now  this  will 


* We  ought  further  to  remark,  that  there  is  a difference  between  the  motion  of  the  slide  in  the  up  and  down  stroke. 
When  the  centre  of  the  eccentric  has  reached  that  part  of  its  orbit  furthest  removed  from  the  slide,  the  motion  ol  the 
slide  is  slowest;  and  when  at  that  part  nearest  to  the  slide,  the  slide’s  motion,  though  slow,  is  comparatively  quick.  But 
at  such  times  the  piston  is  moving  very  quick,  and,  consequently,  in  the  former  case  the  steam-iine  is  further  extended 
than  in  the  latter.  This  will  therefore  help  to  account  for  onr  getting  a better  diagram  from  the  top  of  the  cylinder  of  a 
beam-engine,  and  from  the  bottom  of  a direct-engine ; and  the  difference  becomes  more  marked  in  engines  having  a short 
connecting-rod.  This  is  fortunate,  for  it  assists  in  balancing  the  engine. 

f In  most  direct-engines  a pin  can  be  fixed  on  the  main  centre  of  the  air-pump  beam.  In  Seaward’s  direct-engine  the 
string  may  be  attached  to  the  centre-tine  of  the  radius-bar. 

1 This  will  be  the  case  in  one  engine,  but  not  necessarily  so  in  another  engine;  and  moreover,  if  the  string  be  led  in 
another  direction  the  reverse  will  happen;  hut  this  the  practical  man  can  correct  fo^himself  according  to  circumstances, 
and  substitute  ascending-  tor  descending,  and  vice  versa. 

§ These  diagrams  should  be  reversed ; that  is  to  say,  the  right  side  should  he  in  place  of  the  left. 


INDICATORS. 


61 


take  place,  as  the  diagram  shows,  very  slightly  before  the  upward  stroke  of  the  piston  is  accomplished 
and  since  the  piston  and  slide  are  both  on  the  ascent,  the  lower  edge  A will  have  ascended  a trifling 
space  when  the  piston  is  at  its  highest.  This  slight  space,  though  trifling  in  amount,  is  important  in  its 
results  on  the  working  of  the  engine.  It  is  denominated  the  had  of  the  slide.  As  the  piston  descends 
the  valve  rises,  and  the  admitting  orifice  becomes  larger,  so  that  although  the  piston  is  gaining  speed  in 
its  downward  course,  yet  in  well-contrived  engines  the  first  pressure  is  continued,  as  we  find  in  the 
diagram,  through  a considerable  portion  of  the  stroke. 


The  slide,  however,  has  already  begun  its  downward  motion,  and  when  the  pencil  arrives  at  C it  has 
returned  into  the  position  it  had  in  Tig.  J.  It  is  clear  that  as  it  continues  to  descend  no  more  steam 
can  be  admitted;  whatever  the  cylinder  contains  will  remain  pent  up;  and  as  the  piston  continues  to 
move  downwards  the  steam  relaxes  its  force,  and  we  trace  a corresponding  depression  in  the  diagram 
from  C to  D.  But  a still  greater  change  is  to  be  expected  before  the  piston  arrives  at  its  lowest  place. 
Ere  that  happens  the  slide  will  have  come  into  the  position  shown  by  Fig.  III.;  for  it  is  found  to  be 
disadvantageous  to  allow  the  steam  to  be  kept  in  the  cylinder  till  the  end  of  the  stroke,  because  the 
entering  steam  at  the  reverse  stroke  would  meet  with  so  much  opposition,  till  the  vacuum  on  the  oppo- 
site side  had  become  tolerably  good,  that  the  equability  of  the  motion  would  be  much  affected.  This 
being  granted,  we  see  that  the  port  will  be  open  for  eduction  before  the  end  of  the  stroke,  consequently 
a rapid  fall  in  the  curve  takes  place  at  D.  Moreover,  the  slide  continues  to  fall,  not  only  after  the  piston 
has  come  to  the  bottom,  but  evidently  during  the  greater  portion  of  the  up  stroke.  Although  after  a 
very  short  interval,  from  the  great  rate  at  which  the  steam  rushes  into  a vacuum,  the  state  of  the  va- 
cuum is  nearly  unaltered,  and  but  little  different  from  that  in  the  condenser ; hence,  after  turning  the 
right-hand  corner,  the  pencil  runs  nearly  horizontally.  At  F,  however,  the  slide  has  returned  to  the 
position  represented  in  Fig.  III.,  and  is  rising  ; the  piston  is  also  rising,  and  near  the  top ; consequently 
the  steam  that  has  not  yet  made  its  escape  is  pent  up,  and,  becoming  more  and  more  compressed,  the 
pencil  rises  rapidly,  till,  the  fresh  steam  entering,  it  starts  up  suddenly  to  A and  retraces  the  curve. 

The  accompanying  diagram,  Fig.  2313,  though  being  taken  from  the  same  engine  as  that  represented 
in  Fig.  2312,  differs  in  many  respects. 

We  observe,  in  the  first  place,  that  the  steam-line  I K is  shorter 
than  in  Fig.  2312,  while  the  exhaust-line  LM  is  longer  than  in  the 
latter;  we  infer,  therefore,  that  the  steam  had  a shorter  time  to  come 
into  the  cylinder,  and  a longer  time  to  make  its  escape.  We  observe, 
likewise,  that  the  engine  had  made  a considerable  portion  of  its  down- 
ward stroke  before  fresh  steam  was  admitted.  Now,  these  phenom- 
ena can  be  explained  by  supposing,  from  some  cause,  the  slide  to  be 
removed  bodily  below  the  place  it  had  when  the  former  diagram 
was  traced.  For  let  us  refer  to  the  series  of  representations  of  the 
slide  before  noticed : Thus  the  point  I shows  us  the  steam  comes  in 
later  in  tliis  diagram  than  in  the  former,  and  the  valve  is  rising ; consequently  its  lower  edge  will  oe  at 
some  point  lower  than  it  would  be  in  ordinary  circumstances.  Again,  the  point  K of  the  diagram  indi- 
cates to  us  that  the  steam  is  cut  off  again  sooner,  but  the  slide  is  descending,  and  therefore,  also,  the 
lower  edge  is  lower  than  it  ought  to  be.  Again,  N being  too  far  from  the  end  of  the  stroke,  we  see  that 
the  exhaust  takes  place  too  early ; in  other  words,  the  upper  edge  of  the  slide  is  too  low.  And  lastly, 
the  point  L (where  the  cushioning  commences)  being  carried  too  far  to  the  left,  shows  us  that  too  great 
an  interval  elapses  before  the  upper  edge  of  the  slide  reaches  the  upper  edge  of  the  port.  And,  conse- 
quently, every  part  of  the  reasoning  proves  to  us  the  fact  that  the  slide  is  lower  than  should  have  been 
the  case.  Now,  in  pursuing  our  inquiries,  we  shall  find  this  is  caused  by  one  of  two  defects,  viz.,  either 
the  slide-rod  is  too  long,  or  the  eccentric-rod  is  not  of  the  proper  length.  But  in  seeking  for  the  remedy, 
we  must  look  to  the  slide-rod  alone,  because  its  length  can  be  more  easily  adjusted  than  the  eccentric- 
rod,  by  means  of  the  nuts  and  screw  by  which  it  is  fastened  to  the  cross-head.  The  derangement  of 
the  engine,  when  the  diagram  represented  in  Fig.  2313  was  taken,  was  obtained  by  lengthening  the 
slide-rod  fths  of  an  inch.  The  projection  at  the  point  0 remains  to  be  noticed,  although  it  would  never 
appear  except  in  exaggerated  cases,  such  as  the  one  before  us.  It  will  be  seen  that  the  cushioning  takes 
place  from  L to  O,  and  consequently  the  pencil  rises  because  the  steam  is  compressed ; but  the  fresh 
steam  does  not  yet  enter,  and  therefore  as  the  piston  descends,  this  steam,  till  now  compressed,  loses  its 
elastic  force  and  the  pencil  drops,  till  at  o a fresh  supply  enters  and  the  pencil  starts  up  from  o to  I, 
taking  a motion  compounded  of  the  motion  of  the  piston  and  the  pressure  of  the  steam,  for  it  is  to  be 
noticed  that  the  line  o I bends  sensibly  to  the  left ; this  arises  from  the  increasing  velocity  of  the  piston, 
and  is  not  observable  in  the  standard  diagram,  Fig.  2312,  except  near  the  top,  because  the  piston  is  all 
but  stationary  during  the  short  time  the  steam  is  entering. 


2313. 


M L 


62 


INDICATORS. 


The  opposite  effects  would  have  taken  place  if  the  slide-rod  had  been  shortened ; that  is  to  say,  the 
upper  portion  of  the  diagram  would  have  been  spread  out,  and  the  lower  part  contracted.  If  the  whole 
slide  be  of  the  proper  length,  it  is  clear  that  when  we  get  a faulty  dia- 
gram taken  from  above  the  piston,  the  one  taken  from  below  it  will  be 
similar  to  Fig.  2314,  and  vice  versa.  Hence,  therefore,  we  see  one  advan- 
tage of  taking  both  a top  and  bottom  diagram.  But  if  the  one  diagram 
be  similar  to  one  of  those  just  exhibited,  and  the  other  be  satisfactory,  the 
fault  lies  with  the  slide  itself,  and  cannot  be  remedied  but  by  the  engine- 
makers.  The  only  plan  for  the  engineer  is  to  divide  the  fault  as  equally 
as  he  can  between  the  upper  and  lower  parts,  by  lengthening  or  shorten- 
ing the  rod,  according  to  circumstances.  Moreover,  we  conceive  an  engineer  should  not  be  satisfied 
that  he  has  done  all,  when  he  has  obtained  a good  diagram  from  one  end  of  the  cylinder ; because,  if 
the  fault  lay  with  the  slide,  he  would  be  improving  one  to  the  injury  of  the  other. 

All  the  motions  of  the  slide,  whether  up  or  down,  would  take  place  sooner  than  ordinary,  if  the  stop 
on  the  eccentric  were  too  far  advanced ; that  is  to  say,  the  cushioning,  the 
introduction  of  fresh  steam,  the  cutting  off,  and  the  exhaust,  would  all  com- 
mence sooner.  The  curve,  therefore,  instead  of  being  like  the  standard 
diagram,  will  be  similar  to  Fig.  2315,  assuming  somewhat  of  a lozenge- 
shape,  the  upper  right  and  lower  left  corners  being  acute-angled,  and  the 
other  two  obtuse.  Again,  a little  reflection  will  enable  us  to  discover  that 
similar  defects  will  be  exhibited  in  the  lower  diagram  under  these  circum- 
stances, and  not  opposite  defects,  as  was  the  case  when  the  slide  or  eccen- 
tric rod  was  at  fault. 

This  curve  was  obtained  by  inserting  a piece  of  metal,  half  an  inch  thick,  between  the  stop  on  the 
eccentric  and  that  on  the  shaft. 

It  can  be  readily  ascertained,  by  inspecting  the  diagram,  if  the  stop  on  the  shaft  were  not  sufficiently 
advanced ; for  in  such  a case  all  the  motions  of  the  slide  will  be  later  than  they  would  be  in  a well- 
constructed  engine ; consequently,  all  the  upper  part  of  the  curve  will  be  drawn  towards  the  right,  and 
all  the  lower  part  to  the  left.  And,  as  in  the  former  case,  the  same  distortion  will  be  observable  if  a 
diagram  be  taken  from  the  lower  part  of  the  cylinder.  Moreover,  if  the  defect  be  great,  we  shall  meet 
with  the  hump  in  the  lower  right-hand  corner,  similar  to  that  before  noticed. 

Fig.  2316  was  taken  after  removing  back  the  stop  on  the  shaft  7-16ths  of  an  inch. 

When  the  ports  of  the  cylinder  or  the  steam-pipe  are  too  small,  the  steam  will  not  be  able  to  enter 
or  escape  so  freely  as  it  ought ; the  pressure  at  first  entrance  will  not  be  maintained  for  any  length  of 
time,  and  the  vacuum  will  not  be  formed  rapidly  enough,  the  steam  and  vacuum  lines  will  therefore 
lose  their  horizontality,  as  is  easily  discovered  in  the  diagram  here  given,  which  was  taken  from  one 
of  our  largest  engines,  afterwards  altered  by  shortening  the  gab-lever. 

2316.  2317.  2318. 

^=Y- 

t ] 


When  the  steam  is  throttled  the  upper  line  of  the  diagram  will  rapidly  decline,  as  in  Fig.  2317,  for 
the  same  reason  that  it  would  if  the  steam-pipe  or  the  port  were  too  small,  and  it  will  not  be  so  high 
altogether  as  in  ordinary  cases.  The  vacuum-line,  however,  will  be  better  than  it  would  otherwise  be ; 
for  since  the  quantity  of  steam  admitted  is  not  so  great,  the  speed  of  the  piston  will  be  reduced.  But 
the  exhaust-port  is  of  the  same  size  whether  the  steam  be  throttled  or  not ; and  therefore  there  is  more 
time  for  the  expended  steam  to  rush  through  this  orifice  into  the  condenser,  and  consequently  the 
vacuum-pressure  in  the  c mdenser  and  in  the  cylinder  will  be  more  nearly  equal,  and  better  in  both 
than  when  the  full  power  is  set  on. 

Fig.  2318  represents  three  diagrams  taken  from  the  engine  before  referred  to,  the  steam  being  throt- 
tled to  various  degrees. 

Fig.  2319  will  represent  a diagram  when  the  expansive  geer  alone  is  used.  For  let  AB  represent 
the  whole  length  of  the  cylinder,  and  when  the  piston  has  traversed  the  space  A 0,  let  the  ingress  of 
the  steam  be  suddenly  stopped.  Then,  from  this  epoch,  the  steam-pressure  will  decrease,  and  the  pencil 
begin  to  descend.  Now  if  the  temperature  of  the.steam  be  unaltered,  the  pressure  will  vary  inversely 
as  the  space  it  occupies.  Divide,  therefore,  the  space  C B into  intervals  C J G,  &c.,  each  equal  to 
A C ; and  therefore  when  the  piston  is  at  J,  the  space  A J being  twice  A C,  the  pressure  of  the  steam 
at  J is  half  that  at  C,  at  G it  will  be  one-third,  at  H one-fourth,  &c. ; and  if  lines  be  drawn  through 
C J G,  Arc.,  parallel  to  A D,  and  of  the  length  we  have  just  indicated,  making  CE  = AD,  JL  = half 
A D,  tfec.,  and  through  the  upper  extremities  of  these  lines  a free  curve  be  traced,  it  will  give  us  an  idea 
of  what  we  ought  to  expect.  But  since  the  slide-valve  also  acts,  we  shall  have  the  modification  this 
would  produce  too,  for  the  slide-valve  is  placed  between  the  expansion-valve  and  the  cylinder,  in  most 
engines  ; it  follows,  therefore,  that  the  effective  volume  of  the  steam,  intercepted  by  the  expansion- 
valve,  is  the  whole  of  the  space  between  it  and  the  piston,  and  the  slide-valve  interposes  an  additional 
barrier  when  it  begins  to  cut  off  the  steam.  The  case,  therefore,  is  somewhat  similar  to  what  it  would 
be  if  there  were  two  expansion-valves,  one  nearer  to  the  cylinder  than  the  other,  and  the  outer  one 
let  ins'  first. 


2315. 


2314. 


INDICATORS. 


63 


Fig.  2320  represents  a series  of  diagrams  taken  from  tlie  same  engine.  Here  0 gives  the  full  steam 
without  using  the  expansion-geer,  1 that  produced  by  the  first  grade  of  expansion,  2 that  produced  by 
the  second  grade,  and  so  on.  We  must  here  remark,  that  in  the  interval  that  elapsed  between  taking 
the  diagram  in  Fig.  2317  and  the  series  here  represented,  the  engine  had  been  improved  by  shortening 
the  gab-lever,  and  thus  enlarging  the  aperture  for  steam  and  eduction.  The  effect  will  be  observable 
bv  comparing  the  diagram  S with  that  in  Fig.  2317. 


2321. 


We  must  always  rest  satisfied  that  an  engine  is  in  good  working  condition  when  the  general  features 
of  the  diagram  are  satisfactory ; for  in  the  hands  of  an  inexperienced  person,  the  indicator  may  trace 
an  unfaithful  representation  of  the  condition  of  the  engine.  When  the  piston  is  near  one  end  of  its 
stroke,  if  an  undue  strain  be  brought  on  the  string  it  will  stretch,  and  the  indicator-barrel  remaining 
stationary  while  the  steam  is  entering,  the  pencil  will  have  a vertical  ascending  motion,  such  as  is  rep- 
resented in  Fig.  2322.  On  the  other  hand,  if  the  barrel  come  back  against  its  stop  before  the  opposite 
stroke  is  accomplished,  the  pencil  will  fall  vertically,  as  in  Fig.  2321.  These  two  figures  ought  to  have 
been  precisely  similar,  the  only  cause  of  difference  being  the  accident  of  the  string. 

The  series  of  steps  in  the  right  upper  portion  of  the  diagram  represented  in  Fig.  2323  arises  from  the 
piston  of  the  indicator  being  packed  over-tight,  on  which  account  it  descends  by  a series  of  jerks  as  the 
steam-pressure  relaxes. 


2322.  2324. 


The  steam-line  in  Fig.  2324  does  not  descend  so  rapidly  as  in  the  imaginary  curve  spoken  of  in  the  last 
page,  because  the  expansion-valve  of  the  engine  it  was  taken  from  was  leaky,  and  therefore  did  not  en- 
tirely cut  off  the  steam. 

The  most  accurate  way  of  ascertaining  the  power  of  an  engine  is  by  means  of  the  indicator,  because 
the  diagram  gives  the  pressure  on  the  piston,  and  hence,  knowing  the  number  of  revolutions  and  the 
length  of  stroke,  the  laboring  force  can  be  ascertained.  The  mean  pressure  on  the  piston  is  obtained 
as  follows : Divide  the  diagram  by  a series  of  equidistant  vertical  fines,  as  in  Fig.  2325,  (the  closer  the 
better,)  and,  taking  the  horizontal  line  marked  0 as  the  origin,  draw  a series  of  other  lines  parallel  to  it 
at  distances  >qual  to  the  intervals  corresponding  to  the  scale  of  pounds  on  the  indicator.  This  being 


accomplished,  if  our  object  be  only  to  form  an  estimate  of  the  gross  power,  observe  in  the  middle  of 
each  vertical  space  the  number  of  pounds  included  between  the  steam  and  vacuum  lines  to  tenths,  which 
will  be  best  done  by  taking  the  distance  with  a pair  of  compasses,  and  setting  it  off  on  the  scale  of 
pounds.  Write  these  in  their  proper  columns,  as  in  the  figure,  along  the  diagram,  and  add  them  to- 
gether. Then  divide  the  gross  result  by  the  number  of  columns,  and  we  obtain  the  gross  average 
pressure  on  the  one  side  of  the  piston  during  the  up  and  down  stroke.  From  this  it  is  usual  to  deduct 
from  1 pound  to  1-5  pounds,  according  to  the  size  of  the  engine,  for  friction,  for  small  engines  have  more 
friction  in  proportion  than  a larger ; then  the  result  is  taken  as  the  effective  pressure  per  square  inch, 
acting  uniformly  during  one  whole  revolution.  Take  now  the  diameter  of  the  cylinder  in  inches,  and 
square  it;  then  multiply  the  product  by  "7854,  the  result  is  the  number  of  square  inches  in  the  surface 
of  the  piston.  Multiply  this  again  by  the  pressure  per  square  inch,  as  got  from  the  indicator,  for  the 
whole  pressure  in  pounds  on  the  surface  of  the  piston.  And  if  this  be  multiplied  by  the  length  of  a 
double  stroke,  and  finally  by  the  number  of  revolutions,  we  shall  obtain  the  work  done  by  the  engine 


14 


INDICATORS. 


It  is  usual  to  divide  this  quantity  by  33,000,  (supposing  this  to  be  the  number  of  pounds  a horse  would 
be  able  to  raise  one  foot  a minute,  and  the  quotient  is  then  called  the  horse-power  of  the  engine.  If 
there  be  two  engines,  as  is  usually  the  case  in  steamers,  this  quantity  must  be  doubled. 

Example. — In  the  preceding  diagram,  let  the  number  of  revolutions  be  38,  and  therefore  the  number 
of  single  strokes  76. 

Then,  since  the  diameter  of  steam-cylinder  = 20  inches, 

. ' . Diam.5  = 400 
•7854 

314‘2000  sq.  inches. 

But  pressure  of  steam  = 15 '05  lbs. 

Deduction  for  friction  = T50 

. • . Effective  pressure  per  inch  = 13'55 

314-2 

2710 

5420 

1355 

4005 

Pressure  in  lbs.  on  piston  = 4257-410 

76 

2554446 

2980187 

323563-16 


33|000)647|126-62 

19§  horse-power 

If  it  be  necessary  to  find,  separately,  the  value  to  be  given  to  the  steam  and  vacuum  pressures,  we 
must  get  the  actual  pressure,  and  not  the  difference  of  pressure  between  the  steam  and  vacuum  lines. 
And  therefore  we  might  measure  the  height  of  the  spaces  above  the  atmospheric  line,  and  the  depth 
of  the  vacuum  below  it.  But,  in  regard  to  the  steam-line,  a difficulty  has  to  be  surmounted,  which 
would  not  be  easily  got  over  by  practical  men  unaccustomed  to  analytical  investigations.  It  is  this ; that 
part  of  the  steam-line  is  usually  above  the  atmospheric  line,  and  part  below  it ; and  the  results  of  the 
one  must  be  subtracted  from  the  results  of  the  other.  This  is  more  particularly  to  be  noticed  in  cases 
where  the  engine  is  working  expansively,  and  a great  portion  of  the  steam  line  is  in  consequence  below 
the  atmospheric  line.  The  following  suggestion  will,  however,  get  over  the  difficulty : consider  the  at- 
mospheric line,  as  in  Fig.  2325,  to  be  15  lbs.  (which  is  its  actual  pressure,)  and  reckoning  downwards,  call 


»0 


2326. 


10 

in 

17 

111 

15 

14 

13 

12 

11 

10 


6 

5 

4 

3 

2 

1 

0 


the  lines  below  it  14,  13,  die.,  till  we  come  to  3,  2,  1,  0 : the  line  marked  0 we  will  assume  as  that  line 
from  which  the  pressures  are  measured,  and  both  the  steam  and  vacuum  line  will  be  above  this  new 
zero  line  ; and  the  actual  pressures  of  each  will,  by  these  means,  be  ascertained,  and  not  the  relative 
pressure,  as  compared  with  that  of  the  atmosphere.  In  the  preceding  diagram,  this  second  method  of 
computation  has  been  performed  ; the  numbers  on  the  right-hand  side  beginning  from  the  absolute  zero, 
and  the  figures  along  the  top  and  bottom  of  the  curve  giving  the  steam  and  vacuum  pressures  respec- 
tively. The  mean  of  the  steam-pressure  is  18-85  lbs.,  and  of  the  vacuum  3'81bs.  The  difference  is 
15'06,  as  we  obtained  before. 

To  determine  the  work  done  in  one  single  stroke  of  the  piston,  we  must  suppose  the  piston  to  be  de- 
scending ; then  the  steam-pressure  acts  above  the  piston,  and  the  vacuum-pressure  below  the  piston ; 
that  is  to  say,  the  steam-pressure  must  be  got  from  the  top  diagram,  and  the  vacuum-pressure  from  the 
bottom  diagram ; and  we  must,  therefore,  make  use  of  the  method  proposed  in  the  answer  to  the  last 
question.  Thus,  to  obtain  the  mean  pressure  during  the  down  stroke,  take  the  steam-pressure  from  the 
top  diagram,  and  the  vacuum-pressure  from  the  bottom  diagram,  and  subtract  the  latter  from  the  former. 
Again,  to  obtain  the  pressure  during  the  up  stroke,  take  the  vacuum- pressure  obtained  from  the  top 
diagram,  from  the  steam-pressure  got  from  the  bottom  diagram. 

To  ascertain  by  the  indicator  the  quantity  of  steam  an  engine  uses,  we  have  only  to  fix  on  any  cod 


INDICATORS. 


65 


Tenient  part  of  the  steam-line  between  that  point  where  the  steam  is  cut  off  and  the  opening  is  made  to 
the  condenser ; that  is  to  say,  between  the  points  C and  D in  Fig.  2312.  Observe,  by  counting  the  ver- 
tical spaces,  what  proportion  the  portion  of  the  stroke,  as  far  as  this  point,  bears  to  the  whole  length  of 
the  stroke.  Notice  also  the  pressure  of  the  steam  at  this  point.  Then  we  shall  have  a certain  fraction 
of  the  cylinder  tilled  at  each  stroke  with  steam  of  a given  pressure.  If  now  the  cubic  contents  of  the 
cylinder  be  determined,  and  the  number  of  times  the  cylinder  is  tilled  per  minute,  we  shall  have  the 
quantity  of  steam  of  known  pressure  supplied  to  the  engine  per  minute.  Thus,  suppose  that  in  the 
engine  before  alluded  to  of  the  cylinder  were  tilled  w7ith  steam  of  15  lbs.  pressure  ; then,  since  the 
number  of  cubic  inches  in  the  cylinder  twice  filled  is  15079-6,  the  number  of  revolutions  being  34  at  the 
time  of  experiment,  the  whole  number  of  inches  in  a minute  = 51252-64,  . • . fa  X 512526-4  = 461 273-76, 
and  the  number  of  cubic  inches  of  atmospheric  steam  in  an  hour  = 4C1273'76  X 60  = 27676425-60. 
But  each  inch  of  water  is  supposed  to  form  1711  cubic  inches  of  steam  at  the  atmospheric  pressure,  and 


therefore  the  number  of  cubic  inches  of  water  evaporated 


27676425-6 

lTLl 


= 16,175  ; and  the  number  of 


gallons  (English)  of  water  evaporated 


16175 

277-274 


58  nearly. 


Now,  if  the  theory  be  correct,  this  should  be  the  quantity  of  water  evaporated  from  the  boiler, 
due  allowance  being  made  for  condensation,  Ac.,  in  the  steam-pipe  and  passages.  But  this  is  far  from 
being  the  case,  for  the  number  of  gallons  actually  evaporated  by  the  boiler  was  ascertained  to  be  108 
gallons  in  the  hour.  We  can  do  nothing  more  at  present  than  to  state  the  discrepancy,  and  offer  the 
following  hypothesis  to  account  for  it.  From  the  violence  of  the  ebullition,  the  steam  is  in  all  likelihood 
not  so  dry  as  that  on  which  careful  experiments  are  made,  as  is  frequently  made  manifest  in  boilers 
that  “ prime so  that,  even  in  good  boilers,  it  is  very  possible  for  the  steam  to  contain  much  more 
watery  vapor  than  it  would  if  it  were  not  so  rapidly  consumed.  If  so,  an  inch  of  water  would  not  under 
these  circumstances  form  1711  cubic  inches  of  steam  under  the  atmospheric  pressure,  and  might  per- 
haps form  only  one-half  that  quantity,  which  would  be  requisite  to  give  the  proper  number  of  gallons 
of  evaporated  water.  It  remains  to  be  seen  by  future  experiments  whether  this  be  the  fact ; and  if 
true,  it  will  throw  doubt  on  the  tables  of  relative  volumes  of  steam  and  water  contained  in  most  works 
on  the  steam-engine. 

To  determine  the  friction  of  the  unloaded  engine.— If  we  examine  the  effect  of  any  machine  at  work, 
however  simple,  we  shall  find  a certain  amount  of  power  is  requisite  to  overcome  the  friction  of  the 
engine  itself.  Divest  a common  crane  of  its  chain,  or  any  load  that  may  be  upon  it,  and  it  will  still  be 
found  that  some  force  must  be  applied  to  give  motion  to  the  geering  itself ; the  amount  of  force  de- 
pending on  the  materials  used,  the  mode  of  fitting,  and  the  quantity  of  geer  set  in  motion.  So  it  is 
with  the  steam-engine.  A certain  amount  of  power  is  required  to  overcome  the  friction  of  all  its  parts  ; 
and  in  this  respect  no  two  engines  will  be  found  alike,  so  much  depending  on  the  goodness  of  the  work- 
manship, and  the  nice  adjustment  of  the  different  parts. 

Before  proceeding  with  the  method  of  ascertaining  the  friction  of  an  engine  by  the  indicator,  we  would 
observe,  that  the  greatest  care  and  judgment  are  requisite  in  carrying  out  this  experiment ; there  are 
many  classes  of  engines  in  which  the  experiment  ought  not  to  be  tried,  especially  direct-acting  engines. 
The  way,  however,  to  proceed  is  this ; the  communication  valve  must  first  be  closed,  because  the  engine 
requires  an  exceedingly  small  quantity  of  steam  to  work  it  when  the  paddle-wheels  are  disengaged. 
Then  let  the  blow-valve  be  opened,  to  allow  any  steam  that  may  happen  to  be  in  the  steam-pipe  to 
escape.  In  the  engine  with  which  we  tried  our  experiments,  it  was  found  necessary  to  destroy  the 
vacuum,  befor  getting  the  diagram,  by  opening  the  blow-valve,  to  prevent  the  engine  flying  off  at  too 
great  speed.  The  throttle-valve  must  be  closed,  and  the  paddles  disconnected.  After  slightly  opening 
the  communication  and  throttle  valves,  the  slide  may  be  opened  gradually  and  cautiously,  to  admit  the 
steam  to  the  piston,  and  the  injection  must  be  let  on  as  carefully  as  possible.  Work  the  engine  a few 
strokes  by  hand,  and  then  let  it  be  thrown  into  geer,  and  regulate  the  working  by  the  throttle  and  com- 
munication valves — the  object  being  to  give  the  engine  the  same  number  of  revolutions  without  the 
paddles  as  it  usually  has  with  them — taking  care  to  have  the  condenser  of  the  same  temperature  as  in 
the  ordinary  working  state  of  the  engine.*  The  indicator  having  been  previously  fixed  and  adjusted. 


— 6 
— 6 


* W e would  strongly  advise  the  insertion  of  the  bulb  of  a thermometer  in  the  condenser  of  every  engine  in  addition  to 
(he  barometer-gage.  The  bulb  must  be  entirely  within  the  condenser,  and  the  scale  (at  least  that  part  of  it  which  is 
above  50°  or  GO0)  outside,  in  the  engine-room.  The  thermometer  chosen  for  the  purpose  must  be  graduated  higher  than 
the  temperature  of  the  steam  in  the  boiler,  otherwise  it  will  burst  when  the  engine  is  blown  through.  It  must  be  placed 
in  some  part  acted  on  freely  by  the  steam,  but  free  from  the  splash  of  the  injection  water.  When  the  engine  is  free  from 
air  it  will  then  serve  as  a most  delicate  test  of  the  vacuum.  The  temperature  preserved  should  be  about  100°. 

Vol.  II.— 5 


66 


INDICATORS. 


let  a diagram  be  taken : it  will  be  widely  different  from  that  when  the  load  is  on.  Both  the  steam-line 
and  vacuum-line  will  be  much  below  the  atmospheric  line.  The  diagram  may  then  be  taken  off,  and 
divided  as  in  the  former  case.  Let  the  result  of  this  diagram  be  worked  off  in  the  same  manner  as  the 
common  diagram,  and  the  amount  is  the  work  the  steam  lias  performed,  or  in  other  words,  the  friction 
of  the  unloaded  engine.  This  has  been  accomplished  in  the  diagram,  Fig.  2327. 

This  is  what  is  commonly  subtracted  from  the  gross  result  obtained  under  ordinary  circumstances, 
and  denominated  friction  ; but  it  is  manifest  that  it  is  much  less  than  the  actual  friction  of  the  engine 
when  turning  the  wheels,  for  the  friction  of  every  machine  increases  with  its  load ; and  moreover,  the 
injection  water,  &c.,  raised  by  the  air-pump  increases  likewise,  and  all  this  goes  under  the  head  of  fric- 
tion. The  friction  of  large  engines  is  less  in  proportion  than  that  of  smaller  ones  ; in  large  engines  it 
is  usual  to  allow  1 lb.  on  the  square  inch  of  the  piston  for  friction,  and  in  small  engines  from  1’5  to  2 lbs. ; 
and  in  most  cases  it  would  be  better,  except  as  a matter  of  experiment,  to  trust  to  this  than  to  at- 
tempt the  difficulty  of  ascertaining  it, 

A slide  diagram  is  that  in  which  the  indicator-string  is  connected  with  the  cross-head  of  the  slide, 
and  not  with  that  of  the  piston ; so  that  the  horizontal  motion  of  the  pencil  backwards  and  forwards 
corresponds  to  ascents  and  descents  of  the  slide,  and  vice  versa.  And  this  process  will  give  us  many 
particulars  of  the  slide,  without  the  trouble  of  taking  the  engine  to  pieces  for  measurement.  If  the 
indicator  be  applied  to  the  upper  end  of  the  cylinder,  it  will  give  us  information  of  the  upper  slide-face ; 
and  if  to  the  lower  end,  of  the  lower  slide-face.  As  was  before  stated,  the  string  must  be  connected 
with  some  part  having  the  motion  of  the  slide ; but  generally  it  will  be  necessary  to  reduce  the  motion, 
because  the  stroke  of  the  slide  is  more  than  the  indicator-barrel  will  allow ; in  small  engines  it  may  be 
attached  to  the  cross-head  direct.  As  was  before  remarked,  so  long  as  the  pencil  is  moving  from  left 
to  right,  the  slide  is  rising ; and  when  moving  from  right  to  left,  it  is  falling  ; and  any  rise  or  fall  of  the 
steam-pressure  is  due  to  the  change  of  pressure  in  the  steam,  as  in  the  common  or  piston  diagram. 
Then  the  difference  in  the  two  cases  would  be  this : that  in  the  common  case  we  have  changes  of  pres- 
sure corresponding  to  motions  of  the  steam-piston ; and  in  the  slide  diagram  we  have  changes  of  pres- 
sure corresponding  to  the  motions  of  the  slide  ; and  the  important  thing  to  notice  is,  that  every  sudden 
change  of  pressure  refers  to  some  prominent  epoch  in  the  slide’s  motion  ; and  consequently  we  are  en- 
abled to  trace  successively  on  the  paper,  the  various  positions  of  the  slide  from  its  lowest  point  as  it 
cushions  the  steam,  allows  fresh  ingress,  &c.,  and  finally  arrives  at  its  highest  point. 

The  following  is  a slide  diagram,  obtained  by  connecting  the  string  to  the  slide  cross-head  of  our 
model  engine.  The  whole  length  of  the  figure  is  the  same  as  the  travel  of  the  slide.  If  not,  a plan 
must  be  adopted  to  be  afterwards  explained.  When  the  pencil  is  at  d,  the  slide  is  at  the  lowest  point, 
and  the  vacuum  is  very  good,  as  the  slide  rises  till  the  pencil  comes  to  e ; but  since  we  know  d priori , 


2338. 


A 

1! 

f 

D 

(1 

E 

J 

/' 

F 

G 

/ 

11 

„ 

IT 

L 

-i,  | 

p 


that  the  vacuum  remains  good  in  the  engine  till  the  cushioning  commences,  therefore  when  the  slide  »a3 
risen  from  d to  c,  the  cushioning  commences ; the  cushioning  continues  as  the  slide  rises  till  the  pencil 
arrives  at  f,  when  fresh  steam  enters,  and  after  this  epoch  the  slide  still  rises  till  the  pencil  has  reached 
the  point  h.  As  the  upper  line  is  not  so  marked  in  its  character  as  the  lower  one,  we  shall  not  say  any 
thing  of  the  downward  stroke.  Through  the  points  d cf,  &c.,  draw  the  vertical  lines  Ad,  Bf,  C f D A, 
cutting  the  atmospheric  line  in  A B C D,  and  the  horizontal  line  E H in  E F G H.  Suppose  E H to  be 
the  nozzle  of  the  steam-port,  on  which  the  face  of  the  steam-slide  moves,  (the  cylinder  being  for  conve- 
nience of  illustration  supposed  to  be  lying  horizontally ;)  then,  since  when  the  pencil  comes  to  c,  the 
cushioning  commences,  F must  be  the  upper  edge  of  the  port.  Take  F J equal  to  the  depth  of  the 
port,  (which  we  will  suppose  known.)  Again,  since  when  the  pencil  is  at  d the  slide  is  at  the  lowest, 
therefore  we  must  suppose  it  to  have  started  from  E ; and  consequently,  at  starting,  the  upper  edge  of 
the  slide  was  below  the  lower  edge  of  the  port,  the  space  J E.  When  the  upper  edge  of  the  slide 
arrives  at  G,  fresh  steam  enters ; in  other  words,  the  lower  edge  of  the  port  is  at  J,  and  therefore  the 
depth  of  the  slide-face  is  J G.  Moreover,  since  the  slide  still  rises  through  the  space  H G,  H G will  be 
the  greatest  amount  of  opening  for  steam.  The  successive  positions  here  spoken  of  are  laid  down  in 
the  figures  under  the  line  EH.  F J is  the  depth  of  the  port.  In  I the  slide  is  at  its  lowest;  in  1 1 the 
cushioning  is  commencing  ; in  1 1 1 the  steam  is  about  to  enter ; in  N"  the  slide  is  at  its  highest. 

When  the  travel  of  the  slide  is  greater  or  less  than  the  breadth  of  the  diagram,  let  GE  (Fig.  2329) 
be  the  breadth  of  the  diagram,  as  in  the  last  paragraph ; from  G draw  G P,  making  any  finite  angle 
with  G E,  and  equal  to  the  travel  of  the  slide.  Join  P E,  and  through  F and  H draw  F 0,  H R,  parallel 
to  E P,  and  then  proceed  with  the  line  H P^as  in  the  last  paragraph  with  the  line  HE,  considering  0 
to  be  the  upper  edge  of  the  steam-port,  <fcc. 

It  should  be  observed  here,  that  the  piston  diagram  does  not  necessarily  return  into  itself,  and  form  s 


INDICATORS. 


67 


closed  figure,  as  in  the  preceding  diagrams.  This  only  happens  because  the  indicator-barrel  contains 
the  spring  which,  as  has  been  stated,  draws  back  the  barrel  directly  the  string  relaxes.  But  we  can  by 
a different  arrangement  produce  a figure,  of  some  value,  in  which  the  curve  proceeds  continuously  in 
one  direction,  and  which,  therefore,  we  shall  call  the  “continuous  diagram.”  Let  the  spring  fitted  to 
the  traversing  cylinder,  for  bringing  it  back,  be  taken  out,  and  also  the  stop  that  prevents  the  cylinder 
from  going  too  far ; because  our  object  is  to  let  the  barrel  revolve  freely.  The  clasp,  by  which  the 
paper  is  usually  secured,  must  also  be  taken  off,  and  the  paper  must  be  secured  by  turning  it  over  the 
top  of  the  cylinder,  and  be  folded  in  such  a manner  that  the  pressure  of  the  pencil  will  help  to  keep  it 
down.  Let  now  some  part  of  the  engine  be  selected  where  a double  pulley  may  be  fitted  to  revolve, 
one  groove  of  the  pulley  having  about  the  same  diameter  as  the  pulley  attached  to  the  barrel,  and  the 
other  to  the  diameter  of  the  paddle-shaft.  A string  must  be  passed  round  this  latter  pulley  and  the 
shaft,  and  they  will  revolve  in  the  same  time.  Another  string  must  be  passed  round  the  pulley  of  the 
barrel  and  the  smaller  of  the  two  pulleys  ; and  then  the  indicator-barrel  will  revolve  nearly  in  the  same 
time  as  the  engine  shaft.  And  if  we  suppose  the  shaft  to  be  revolving  uniformly,  which  it  will  be 
nearly,  especially  where  there  are  two  engines,  the  barrel  will  have  a uniform  motion  in  one  direction. 
If  the  pencil  be  put  to  the  paper,  as  in  ordinary  cases,  when  the  indicator-piston  is  at  the  lowest,  it  will 
commence  tracing  its  curve.  It  should  be  allowed  to  remain  for  one  entire  revolution,  and  longer  if 
convenient,  provided  one  line  do  not  interfere  with  the  other  in  going  twice  over  the  paper. 

The  chief  practical  utility  of  these  diagrams  is,  that  they  serve  to  show  the  rate  at  which  the  steam- 
pressure  increases  or  decreases.  It  will  be  observed  by  the  continuous  diagram,  Fig.  2310,  that  the 
steam-pressure  does  not  increase  instantaneously,  as  many  suppose,  and  as  the  common  diagram  would 
lead  us  to  believe.  The  vacuum  commences  at  D and  continues  to  E,  the  cushioning  from  E to  A ; the 
fresh  steam  enters  at  A,  and  causes  the  pencil  to  rise  till  it  reaches  its  highest  at  B. 

If  we  examine  this  diagram  in  page  56  by  any  of  the  previous  tests,  we  shall  find  it  rounded 
off  at  the  corner,  a circumstance  not  easily  accounted  for.  For  in  all  former  cases  we  can  only 
correct  a defect  in  this  corner  at  the  expense  of  the  lower  corner.  As  the  indicator  persisted  in 
giving  this  outline,  and  all  attempts  according  to  the  foregoing  principles  (by  altering  the  set  of  the 
slides,  cfcc.)  failed,  it  was  at  length  proposed  to  examine  the  steam-piston  itself;  and  accordingly, 
steam  was  let  in  at  the  lower  port,  and  the  cock  of  the  grease-cup  opened,  when  it  was  discovered  that 
the  piston  was  not  steam-tight  in  the  cylinder ; and  therefore,  although  when  the  engine  was  working 
the  first  impulse  of  the  steam  sufficed  to  drive  the  pencil  up,  yet  as  soon  as  the  piston  had  got  into 
motion,  the  escape  of  steam  by  leakage  did  not  allow  the  pencil  to  rise  so  rapidly  as  it  otherwise  would 
have  done. 

It  is  evident  that  no  part  of  the  diagram  can  be  below  the  atmospheric  line,  when  an  engine  is  worked 
without  condensation  ; for  the  pressure  can  never  be  less  than  that  of  the  atmosphere.  And  since  the 
steam  has  not  a free  escape  into  the  air,  but  is  obliged  to  force  open  the  foot-valve  and  delivery-valve, 
and  make  its  way  through  the  air-pump  bucket,  the  resistance  it  meets  with  will  cause  the  pressure  to 
be  greater  than  that  of  the  atmosphere.  Engines,  whose  steam-pressure  is  not  considerably  greater 
than  that  of  the  atmosphere,  cannot  be  worked  on  the  high-pressure  principle.  The  nest  diagram  was 
taken  from  an  engine  whose  boiler-pressure  is  I lbs.  In 
high-pressure  engines,  the  diagram  will  be  similar;  be- 
cause the  steam  having  to  escape  by  the  blast-pipe,  is 
pent  up,  and  causes  the  lower  part  of  the  diagram  to  be 
above  the  atmospheric  line.  In  general,  the  steam  and 
vacuum  lines  must  be  worked  out  separately  by  the  plan 
proposed  in  page  57  ; for  it  will  be  observed,  that  the  lines 
intersect  each  other  in  the  diagram.  The  indicator  for  high-pressure  engines  should  be  made  expressly 
for  the  purpose  • the  scale  of  pounds  should  have  a higher  range,  but  need  not  go  below  the  atmos- 
pheric line. 

This  curve  presents  a singular  appearance,  from  the  steam  and  exhaust  line  intersecting.  Since  the 
cushioning  begins  at  the  usual  place,  that  is  to  say,  at  the  same  part  of  the  stroke  as  when  used  as  a 
low-pressure  engine,  the  steam  pent  up  on  the  exhaust  side,  and  commencing  with  a pressure  greater 
than  that  of  the  atmosphere,  soon  surpasses  that  of  the  boiler,  so  that  when  the  port  begins  to  open, 
the  pressure  suddenly  falls.  Again,  when  the  entering  steam  is  cut  off,  the  pressure  gradually  falls, 
and  before  the  end  of  the  stroke  it  is  less  than  that  of  the  eduction ; and  when  opened  again  to  exhaust, 
steam  enters  from  the  condenser,  and  the  loop  of  the  left-hand  corner  is  formed. 

The  Dynamometer,  an  instrument  somewhat  similar  to  the  indicator,  has  been  introduced  into  screw- 
vessels,  for  the  purpose  of  enabling  the  engineer  to  record  the  exact  amount  of  pressure  given  off  by 
screw-shaft,  and,  consequently,  the  force  the  engine,  by  means  of  this  instrument,  is  exerting  to  pro- 
pel the  ship.  It  is  merely  a lever,  or  a combination  of  levers  ; the  shaft  pressing  near  the  fulcrum,  and 
the  farther  end  of  the  lever,  or  combination,  being  attached  to  a Salter’s  spring-balance.  In  the  dia- 
gram, Fig.  2310,  A B is  the  screw-shaft  pressing  as  it  revolves  against  a movable  pin  which  is  contained 
in  the  plomer-block  at  G,  and  can  slide  freely  backwards  and  forwards ; D E is  the  lever,  having  the  ful- 
crum at  D ; the  pin  at  C presses  against  a knife-edge  on  the  lever,  as  is  seen  in  the  figure.  The  rod  E F 
is  connected  with  the  spring  of  a Salter’s  balance,  which  cannot  be  seen  in  the  figure,  but  is  concealed 
from  sight  by  the  cylindrical  barrel  IK;  F is  also  attached  to  the  rod  G H.  This  rod,  as  we  perceive, 
has  several  grooves  in  it,  so  that  the  small  fork  carrying  the  pencil  p may  be  brought  in  contact  with 
more  than  one  part  of  the  barrel  in  succession,  if  desirable. 

The  barrel  is  made  to  revolve  by  means  of  a strap  a,  b,  connecting  it  with  the  screw-shaft ; and  it  will 
be  seen  by  the  figure,  that  there  are  pulleys  of  different  sizes  connected  with  the  bulk-head  at  M,  and 
the  shaft  at  N,  by  which  the  motion  of  the  cylinder  can  be  regulated,  and  be  made  quicker  or  slower  at 
pleasure.  The  curve  will  evidently  be  somewhat  similar  to  the  continuous  indicator  diagram,  consist 
ing  of  a series  of  undulations  according  to  the  force  of  the  steam  and  its  action  on  the  propeller.  A 


68 


INDIGO. 


zero-line  must  be  got,  as  in  the  case  of  the  indicator.  When  the  dynamometer  is  applied  to  large  en 
gines,  the  levers  can  be  relieved  of  the  pressure  of  the  shaft;  and  this  being  accomplished,  the  index  01 
the  spring-balance  will  stand  at  0,  when  the  zero-line  may  be  traced.  The  balance  will  also  give  the 
scale  of  pounds.  After  the  diagram  is  traced,  draw  a series  of  equidistant  lines  at  right  angles  to  the 
zero-line,  as  in  Fig.  2310,  in  the  article  on  the  indicator,  which  represents  a dynamometer  diagram  taken 
on  board  a man-of-war  steam-vessel,  the  dimensions  being  reduced  one-half.  The  distance  between  the 
curve  and  zero-line  must  be  measured  and  compared  with  the  scale  of  pounds  on  the  balance.  Let 
this  be  registered  on  the  diagram  in  its  proper  space.  The  sum  of  all  these  is  then  to  be  taken,  apd 
divided  by  the  number  of  spaces  taken  into  account.  Thus  we  shall  obtain  the  mean  force  of  the  lever 
on  the  spring  of  the  balance ; let  this  be  multiplied  again  by  the  leverage  of  the  dynamometer,  and  the 
result  will  be  the  pressure  of  the  screw-shaft  on  the  dynamometer,  and,  therefore,  on  the  vessel.*  To 
obtain  the  leverage,  if  the  lever  be  compound,  multiply  together  all  the  long  arms,  (measuring  from  the 
fulcrum,)  and  divide  the  product  by  all  the  short  arms  multiplied  together,  (measuring  also  from  the 
fulcrum.) 

The  horse  power  of  an  engine  is  to  be  found  by  the  dynamometer  in  the  following  manner : 

Having  found  the  number  of  pounds  pressure  exerted  by  the  screw-shaft,  multiply  it  by  the  speed 
of  the  ship  in  knots,  and  the  product  by  6080,  (the  number  of  feet  in  a knot;)  then  divide  the  result  by 
60,  (the  number  of  minutes  in  an  hour,)  and  by  33,000,  and  the  quotient  will  be  the  horse-power. 

Or  the  work  may  be  shortened,  thus : 

Multiply  the  number  of  pounds  pressure  by  the  speed  of  the  ship,  as  before,  and  this  product  by 
•00307,  and  the  product  gives  the  horse-power. 

This,  it  will  be  observed,  is  the  effective  horse-power  after  making  allowance  for  friction  and  loss  by 
useless  resistance. 

The  diagram  before  referred  to  will  elucidate  the  process  of  working  out  the  result.  This  was  taken 
simultaneously  with  two  others ; and  the  mean  of  the  three  pressures  was  4P309  lbs.  Multiplying 
by  the  power  of  the  system  of  levers,  the  result  was  80864  pounds,  (the  pressure  exerted  by  the 
screw-shaft.) 

The  speed  of  the  ship  was  9 893  knots. 

Hence  80864  X 9-893  = 79998-7. 

And  79998-  X -00307  = 245  nearly,  the  horse  power  required. 

The  horse-power  by  indicator  at  the  same  time  was  465’6,  showing  a loss  of  220-6  by  friction,  re- 
sistance, ifec. 

INDIGO.  A blue  substance  much  used  as  a dye-stuff.  The  best  indigo  is  obtained  from  an  Asiatic 
and  American  plant,  the  Indigofcra.  The  plant  is  bruised  and  fermented  in  vats  of  water,  during  which 
it  deposits  indigo  in  the  form  of  a blue  powder,  which  is  collected  and  dried,  so  as  to  form  the  cubic 
cakes  in  which  it  usually  occurs  in  commerce.  Indigo  is  quite  insoluble  in  water;  when  heated  it 
yields  a purple  vapor,  which  condenses  in  the  form  of  deep  blue  or  purple  acicular  crystals.  When  in- 
digo is  exposed  to  the  action  of  certain  deoxidizing  agents,  it  becomes  soluble  in  alkaline  solutions,  losing 
its  blue  color  and  forming  a green  solution,  from  which  it  is  precipitated  by  the  acids  white ; but  it  in- 
stantly becomes  blue  by  exposure  to  air.  This  white  indigo  has  been  termed  indigogene,  and  indigo 
appears  to  be  its  oxide.  It  is  best  obtained  by  mixing  3 parts  of  finely  powdered  and  pure  indigo  with 
4 of  green  vitriol,  5 of  slaked  quicklime,  and  100  of  water,  repeatedly  shaking  the  mixture.  In  about 
twenty-four  hours  the  supernatant  liquor,  which  is  transparent,  and  of  a green  color,  is  to  be  decanted 
off,  and  poured  into  dilute  muriatic  acid,  when  the  deoxidized  indigo  is  thrown  down  ; but,  in  order  to 
prevent  its  absorbing  oxygen  and  becoming  blue,  it  must  be  most  carefully  excluded  from  the  contact 
of  air,  which  may  be  effected  by  siphoning  it  off  into  the  acid,  collecting  it  in  vessels  filled  with  hydro- 
gen, and  washing  it  with  water  deprived  of  air  and  holding  in  solution  a little  sulphate  of  ammonia.  In 
this  white  state  indigogene  absorbs  between  11  and  12  per  cent,  of  oxygen  to  become  blue  indigo.  It 
would  appear  from  Dumas’  experiments  that  indigogene  is  a compound  of 

Atoms.  Equivalents. 

Carbon 45  = 270 

Hydrogen 15  — 15 

Nitrogen  3 = 42 

Oxygen 4—32 

1 o 59 

and  that  indigo  consists  of  1 atom  of  indigogene  = 359,  and  2 of  oxygen  = 16.  The  chemical  equiva- 
lent of  indigo,  therefore,  is  375. 

When  indigo  is  dissolved  in  concentrated  sulphuric  acid,  it  forms  a deep  blue  liquid,  known  to  the 
dyers  by  the  name  of  Saxon  blue.  The  great  mart  for  indigo  is  Bengal,  and  the  other  provinces  subject 
to  the  presidency  of  that  name,  from  the  20th  to  the  30th  deg.  of  N.  lat. ; but  it  is  also  cultivated, 
though  not  nearly  to  the  same  extent,  in  the  province  of  Tinnevelly,  under  the  Madras  government  in 
Java ; in  Lueonia,  the  chief  of  the  Philippine  Islands ; and  in  Guatimala  and  the  Caracas,  in  Central 
America.  The  following  remarks,  from  the  Commercial  Dictionary,  will  exhibit  the  history  of  this  now 
indispensable  commodity,  and  the  difficulties  with  which  it  had  to  contend  before  it  obtained  a perma- 
nent footing  in  the  commerce  of  Europe.  “ It  appears  pretty  certain  that  the  culture  of  the  indigo 
plant,  and  the  preparation  of  the  drug,  have  been  practised  in  India  from  a very  remote  epoch.  It  has 
been  questioned,  indeed,  whether  the  indicum  mentioned  by  Pliny  was  indigo ; but,  as  it  would  seem, 


* A doubt  lias  been  expressed  by  some  as  to  whether  this  is  really  the  force  exerted  by  the  shaft  on  the  vessel,  on 
account  of  the  shaft  acting  on  a lever  that  yields  to  its  force  ; but  independently  of  the  fact  that  none  of  the  thrust  can 
he  lost,  it  is  clear  that  the  thrust  at  C is  equal  to  the  thrust  at  D and  that  at  E,  and  thess  are  the  two  forces  acting  on  the 
vessel. 


IRON. 


63 


without  any  good  reason.  Pliny  states  that  it  was  brought  from  India ; that  when  diluted  it  produced 
an  admirable  mixture  of  blue  and  purple  colors,  (in  diluendo  misturam  purpuree  cceruleique  mira.bilen. 
reddil ;)  and  he  gives  tests  by  which  the  genuine  drug  might  be  discriminated  with  sufficient  precision. 
It  is  true  that  Pliny  is  egregiously  mistaken  as  to  the  mode  in  which  the  drug  was  produced ; but  there 
are  many  examples  in  modern  as  well  as  ancient  times  to  prove  that  the  possession  of  an  article  brought 
from  a distance  implies  no  accurate  knowledge  of  its  nature,  or  of  the  processes  followed  in  its  manu- 
facture. Beckmann  (Hist,  of  Inventions,  vol.  iv.,  art.  ‘ Indigo’)  and  Dr.  Bancroft  (Permanent  Colors, 
vol.  i.,  p.  241-252)  have  each  investigated  this  subject  with  great  learning  and  sagacity,  and  agree  in 
the  conclusion  that  the  indicum  of  Pliny  was  real  indigo,  and  not,  as  has  been  supposed,  a drug  pre- 
pared from  the  isatis  or  woad.  At  all  events,  there  can  be  no  question  that  indigo  was  imported  into 
modern  Europe,  by  way  of  Alexandria,  previously  to  the  discovery  of  the  route  to  India  by  the  Cape 
of  Good  Hope.  When  first  introduced,  it  was  customary  to  mix  a little  of  it  with  woad  to  heighten  anti 
improve  the  color  of  the  latter ; but,  by  degrees,  the  quantity  of  indigo  was  increased ; and  woad  was, 
at  last,  entirely  superseded.  It  is  worth  while,  however,  to  remark,  that  indigo  did  not  make  its  way 
into  general  use  without  encountering  much  opposition.” 

In  common  painting  indigo  is  seldom  or  never  used  without  a small  mixture  of  white.  A preparation 
from  the  leaves  of  the  anillo  is  sometimes  fraudulently  substituted  for  indigo,  but  may  be  at  once  de- 
tected by  throwing  a piece  into  the  fire,  as  genuine  indigo  will  not  burn. 

INERTIA.  (See  Force.) 

INVOLUTE  CURVE,  is  that  which  is  traced  out  by  the  end  of  a thread  (while  being  unwound)  that 
is  coiled  round  another  curve.  This  species  of  curve  is  frequently  used  in  the  formation  of  the  teeth  ot 
wheels.  (See  Geering.) 

IRON,  (Sanscr.  ais ; Mod.  Hindost.  lohah  ; Mod.  Pers.  auhun ; Chald.  perzela ; Heb.  barzcl ; Gr. 
s ideron  ; Swed  .je.ru;  Dan  .jern;  Icel  .jam;  Franco-theot.  isar,  isarn  ; M*so-Goth.  ais  ; Germ,  eisen ; 
Ang.  Sa x.  isen,  isern,  iren  ; Low  Germ,  isen;  Fries,  ixsen  ; Dutch,  yzer ; Erse,  jarann  ; Welch,  haiarn ; 
Lat.  ferrum  ; Ital.  ferro  ; Sp.  hierro ; Fr.  fer,  &c.,)  one  of  the  longest  known,  the  most  generally  used, 
and  most  extensively  applicable  of  all  the  metals.  Although  found  native,  as  it  is  called,  it  nowhere 
exists  perfectly  pure  in  nature.  In  the  arts,  it  occurs  under  four  conditions;  1.  as  pure  iron:  2.  crude, 
or  cast  iron  ; 3.  malleable,  or  wrought,  or  bar  iron  ; and  4.  steel.  Its  precipitate,  or  release  from  a chem- 
ical solution  or  combination,  is  always  pulverulent,  and  does  not  present  the  most  important  practical 
characteristics  of  the  metal.  Deposited  in  the  electrotype- way,  it  is  more  coherent,  but  still  friable.  It 
is  difficult  to  be  produced  by  this  method  in  large  plates  : pieces  of  an  inch  square  are  rare.  Seen  by 
reflected  light,  its  surfaces  in  this  condition  are  more  brown  than  gray,  owing  to  its  immediate  oxidation. 
A fresh  fracture  is,  however,  clear  gray.  Its  texture  is  crystalline,  6r,  more  properly,  an  assemblage 
of  crystals  loosely  cohering,  which  appear  cubic.  In  this  state  it  is  not  at  all  malleable.  When  fresh  it 
is  highly  magnetic;  but  this  property  rapidly  diminishes  on  exposure  to  the  air  or  moisture.  Its  den- 
sity is  not  known,  and  can  with  difficulty  be  accurately  ascertained.  When  broken  into  spiculae  and 
approached  to  a wire  no  longer  at  a red-heat,  or  even  to  the  lateral  flame  of  a spirit-lamp,  it  decrepi- 
tates slightly  and  becomes  converted  into  powder  of  the  peroxide.  Its  other  properties  in  this  condition 
have  not  been  thoroughly  examined ; nor  are  they  likely  to  present  much  interest  except  for  merely 
speculative,  and,  perhaps,  for  medicinal  purposes. 

In  the  condition  of  steel,  on  the  other  hand,  all  the  peculiarities  and  habitudes  of  this  metal  are  im- 
portant enough  to  require  a special  detail  and  discussion  in  a separate  article.  (See  Steel.)  Under 
this  one  will  be  considered  what  is  proper  to  it  in  its  two  conditions  of  crude  and  malleable  iron.  The 
means  for  artistically  producing  these  two  different  states,  i.  e.  the  manufacture  of  cast  or  bar  iron,  being 
different,  must  of  course  be  detailed  separately.  In  other  regards  they  will  be  spoken  of  together,  but 
distinctly  wherever  necessary ; and  it  will  be  understood,  that  when  not  otherwise  expressed,  the  term 
iron  means  malleable  iron. 

Physical  properties.  The  color  of  crude  iron  varies  according  to  the  state  of  combination  and  pro- 
portion of  its  chief  foreign  ingredient,  carbon,  from  dark  gray  to  silvery  white ; passing  through  divers 
intermediate  stages  of  gray,  mottled,  bright,  and  white.  It  is  upon  these  indications,  coupled  with  those 
of  texture,  (which  will  be  spoken  of  directly,)  that  the  metal  is  classified  in  commerce.  Dark  gray  iron, 
crystalline,  with  small  facets,  is  supposed  to  denote  a fitness  for  foundry  purposes,  i.  e.  for  being  cast 
into  various  forms ; and  the  denomination  of  such  a whole  class  is  foundry-iron,  or  founders'  pig.  As 
its  color  brightens  and  grows  more  and  more  silvery,  with  a bladed  texture,  it  is  considered  better 
suited  for  conversion  into  malleable  iron ; and  the  whole  class  obtains  the  name  ordinarily  of  forge  pig. 
These  distinctions,  further  than  as  applied  to  classes,  are  extremely  loose  and  uncertain ; and  we  are 
yet  without  positive  knowledge  as  to  either  what  causes  or  is  a permanent  practical  consequence  of 
color  in  crude  iron.  In  malleable  iron  the  distinctions  in  this  respect  are  much  less  marked.  A full  gray 
hue,  with  something  of  a bluish  tint,  is  generally  supposed  to  attach  to  the  best  specimens.  Of  course, 
all  these  remarks  apply  only  to  the  phenomena  of  a fresh  fracture  ; and  the  color  and  lustre  which  may 
be  given  to  surfaces  of  iron  in  either  condition  by  finishing  and  polishing  are,  it  will  be  readily  conceived, 
entirely  artificial,  and  dependent  in  no  small  degree  upon  the  processes  that  may  have  been  re- 
sorted to. 

In  the  same  manner,  it  may  be  presumed,  another  property,  which  is  chiefly  superficial,  is  dependent 
ipon  the  artistical  processes  employed  in  developing  it,  and  this  is  the  adhesion  of  iron,  i.  e.  the  force 
w ith  which  it  attaches  itself  to  a liquid  surface.  This  property  has  not  been  experimentally  examined 
to  any  extent,  though  a research  upon  it  wrnuld  probably  be  fruitful  for  all  questions  touching  the  fric- 
tion of  machinery,  and,  perhaps,  would  also  shed  light  upon  the  internal  structure  of  the  metal.  The 
indefatigable  Guyton-Morveau,  only,  has  made  observation  upon  it  in  the  case  of  iron  and  several  other 
metals,  by  polishing  with  an  equal  amount  of  labor  the  face  of  a disk,  one  inch  French  in  diameter, 
(1'0658  in.  English,)  of  the  metals  respectively,  allowing  each  to  repose  an  equal  time  upon  the  surface 
of  mercury  in  a dish,  and  then  seeing  what  weight  wTas  sufficient  to  overcome  the  adhesion  He  found 


70 


IRON. 


the  weight  necessary  in  several  cases  (abstraction  being  made  of  that  of  the  disks  themselves  respect' 
ively)  to  be  as  under : 


Gold  required  446  gr.  Fr.  = 365p72  gr.  Eng 
Silver  “ 429  “ = 351-78  “ 

Tin  “ 418  “ = 342-76  “ 

Lead  “ 372  “ = 30504 

Bismuth  “ 317  “ = 259'94  “ 


Zinc  required  204  gr.  Fr.  = 167-28  gr.  Eng 
Copper  “ 140  “ = 114-80  “ 

Antimony  “ 126  “ = 103-32  “ 

Iron  “ 115  “ = 94-30  “ 

Cobalt  “ 8 “ = 6’56  “ 


Although  the  adhesion  of  a surface  in  contact  with  the  liquid  in  these  experiments  would  be  in  part  a 
function  of  the  aptitude  of  the  metal  itself  to  amalgamate  with  quicksilver,  yet  these  results  are  nowise 
accordant  with  such  aptitude,  as  far  as  it  can  be  inferred  from  other  observations.  And  it  seems  to  be 
equally  independent  of  the  density  and  cohesion  of  the  solid.  It  is  probably  dependent  in  much  greater 
degree  upon  the  absolute  perfection  and  smoothness  of  surface  which,  in  bodies  worked  upon  with  the 
same  force  and  for  the  same  time,  manifests  itself  according  to  another  property,  that  of  hardness.  In 
ordinary  speech,  and  sometimes  even  in  exacter  phrase,  this  term  hardness  is  used  to  express  the  resist- 
ance of  a substance  to  change  of  form  of  any  kind.  Such  resistance  depends  mainly  upon  cohesion  and 
elasticity,  and  covers,  in  part,  the  characteristics  of  malleability  and  stiffness.  But  hardness , in  its  tech- 
nical sense,  is  resistance  to  removal  or  abrasion  of  substance,  as  in  cutting,  boring,  filing,  and  the  like. 
Any  material  which  will  scratch  a given  substance  is  therefore  harder  than  that  substance.  Kirwan 
was  the  first  to  classify  substances  in  this  respect  after  a decimal  scale,  beginning  with  talc  and  ending 
with  diamond.  The  eight  intermediate  tests  are  uniform  and  easily  accessible  minerals.  Measured  by 
such  a scale,  native  iron  (which  may  be  considered  as  nearly  the  type  of  the  malleable  iron  of  commerce, 
though  it  contains  a notable  proportion  both  of  lead  and  copper,  generally,)  is  ranked  in  hardness  at 
4'5  ; that  is  to  say,  it  scratches  fluor-spar  as  much  as  it  is  itself  scratched  by  phosphate  of  lime.  Crude 
iron  is  harder,  and  most  specimens  of  gray  foundry  pig  are  just  scratched  by  felspar ; it  may,  therefore, 
hold  an  average  rank  on  Kir  wan’s  scale  of  5'8.  But  white  forge  pig  will  generally  cut  glass,  and  may 
therefore  be  ranked  at  7 in  hardness  by  the  same  scale.  It  will  readily  be  understood  that  in  applying 
these  tests,  something  depends  upon  the  shape  and  sharpness  of  the  fragment  used ; a dull  surface  will 
merely  rub  without  scratching ; and  in  the  case  of  white  iron  and  glass,  unless  the  lamellar  crystals  of 
the  former  be  used  with  then-  edges,  the  latter  will  not  be  cut.  It  is  the  same  with  the  diamond,  the 
hardest  known  substance  ; only  its  spherical  edges  cut  glass.  In  drawing  a practical  inference  from  such 
observations,  regard  must  be  had,  too,  to  the  ordinary  texture  of  the  substances,  i.  e.  their  mode  of  ag- 
gregation and  cohesion.  Thus  white  iron,  hardened  steel,  quartz  and  granite,  <fec.,  have  all  the  same 
theoretical  index  of  hardness  ; but  steel,  for  instance,  is  much  more  coherent  than  quartz,  which  is  a 
brittle  substance,  and  still  more  so  granite ; it  is,  therefore,  used  readily  for  working  both.  So  sand- 
stone, which  is  principally  grains  of  silica  held  together  with  a siliceous  cement,  and  therefore  has  an 
index  of  7,  is  yet  ordinarily  worked  with  the  same  tools  that  are  used  for  marble,  whose  index  is  but 
3'5.  But  the  causes  and  modes  of  these  apparent  inconsistencies  readily  manifest  and  reconcile  them- 
selves upon  a little  reflection. 

.So  far  as  metals  are  concerned,  the  following  table  may  be  taken  to  give  what  is  known  in  this  par 
ticular ; the  foregoing  cautions  being  equally  applicable. 


■;  '.he  probable  Order  cf  their  Hardness. 
Iron, 

Cobalt, 

Nickel, 

Crude  Iron,  (gray, ) 
Steel,  (soft,) 

“ (hardened,) 
Manganese, 


Table  of  Metals  v 

Mercury, 

Sodium, 

Potassium. 

Lead, 

Zinc, 

Tin, 

Antimony, 

Gold, 

Silver, 

Cadmium, 

Bismuth, 

Tellurium, 

Copper,  copper  and  zinc,  (brass,) 
Platinum,  copper  and  tin,  (gun-metal,) 
Palladium, 

Iron, 


Titanium, 

Crude  Iron,  (white,) 

Chromium, 

1th  odium, 

Iridium,  Osmium, 

Hardest  steel,  varying  from  white  iron  to  the 
top  of  the  list. 


How  much  hardness  is  dependent  on  texture , has  been  already  mentioned ; and  it  is  owing  to  the 
varying  circumstances  of  this  last  property  that  iron  in  different  conditions  is  found  to  shift  about  so 
much  in  the  list  just  given.  In  practice,  another  property,  that  of  affection  by  heat,  or  specific  heat, 
(which  will  presently  be  mentioned,)  has  also  an  influence;  and  a substance,  hard  at  first,  becomes 
sensibly  warm  by  attrition,  and  finally  yields  to  the  action  of  a material  less  hard  than  itself  at  low 
temperatures,  but  endowed  with  a greater  capacity  for  heat.  It  is  thus  in  one  aspect  that  crude  iron 
under  a red  heat  may  bo  cut  and  sawn  almost  like  wood ; and  in  the  other,  that  a wheel  of  soft  malle- 
able iron,  rapidly  revolving,  may  be  made  to  cut  the  hardest  steel.  W orkmen  have  the  opportunity  of 
appreciating  these  affections  in  manipulations  with  the  cold  chisel. 

The  texture  of  crude  iron  is  in  most  treatises  said  to  be  granular.  It  is  in  fact  crystallized;  as  we 
learn  from  the  chemical  experiments  of  Daniell,  and  the  microscopic  observations  of  Schafhaiitl  and 
Alexander.  According  to  the  last-named,  the  crystals  of  gray  iron  “ belong  to  the  octahedral  system, 
[in  which  the  axes  of  crystallization  are  equal  and  at  right  angles,]  and  present  themselves  under  the 
primary  forms  of  several  of  its  classes.”  “The  maximum  limit  of  these,  when  cubic,  is  not  above  -^soo 


IRON. 


71 


of  an  inch  in  linear  dimension,  and  about  TTinnnr  °f  a grain  in  might.”  Crystals  in  white  iron 
are  smaller,  and  “ most  frequently  occur  in  six-sided  prisms,  sometimes  connected  in  fascicles  by  their 
sides,  at  others  by  their  ends,  in  a sort  of  stellated  or  radiated  arrangement,  'l’he  white  color  of  the 
mass  seems  to  be  mainly  arising  from  these  arrangements  of  particles.”  Malleable  iron  is  supposed  to 
have  a filamentous  structure ; but  metallurgists  are  not  agreed  how  far  this  arises  from  (as  it  is  cer- 
tainly in  some  degree  dependent  on)  the  processes  employed  in  the  manufacture.  The  amount  of  forg 
ing  which  the  bars  have  undergone,  the  degree  of  heat  to  which  they  have  been  subject,  as  well  as  the 
ultimate  size  to  which  they  may  have  been  reduced,  all  affect  the  texture  of  specimens,  whose  othei 
characteristics,  originally  and  subsequently,  are  apparently  the  same.  Nevertheless,  this  property  anil 
that  of  color  are  the  chief  commercial  tests  of  the  quality  of  iron.  It  is  generally  supposed  that  a frac- 
ture more  pointed  than  irregular,  and  a tendency  to  become  filamentous  upon  being  forged  into  bars  of 
an  inch  square  or  under,  are  indications  of  the  two  main  characteristics  of  good  iron,  viz.  strength  and 
stiffness.  But  there  is  as  yet  no  criterion  by  which,  on  simple  inspection,  the  quality  of  the  metal  can 
be  determined,  and  both  the  manufacturer  and  the  consumer  are  compelled  to  rely  (iu  the  absence  oi 
actual  experiment)  upon  the  constancy  of  Nature  in  furnishing  materials,  and  the  uniformity  of  Art  in 
subjecting  them  to  the  same  processes.  The  same  ores  treated  in  the  same  way  ought  to  produce  the 
same  metal ; and  so  they  generally  do. 

Closely  connected  with  texture  is  the  property  of  density.  The  variations  in  this  respect  between 
the  results  of  different  observers  are  to  be  attributed  partly  to  the  difference  of  methods,  partly  to  the 
inaccuracy  of  the  weights  employed,  (a  much  more  influential  cause  of  error  than  is  generally  imagined,) 
and  partly  to  the  variations  of  the  individual  specimens.  Their  limits  are,  however,  sufficiently  close 
to  allow  of  taking  as  a probable  average  (the  density  or  specific  gravity  of  distilled  water  being  called 
1)  the  specific  gravity  of 

Crude  iron,  foundry  or  gray  iron,  7- 
“ forge  pig  or  white  “ 7-5 

Malleable  iron, 7'6 

In  estimating  absolute  weight,  it  is  sufficient  for  practical  purposes  to  consider  a cubic  foot  of  dis- 
tilled water  as  equal  to  1000  ounces  avoirdupois  ; so  that  a cubic  foot  of  iron  in  its  different  conditions 
will  weigh  one  thousand  times  the  indices  of  specific  gravity  given  above,  respectively,  in  avoirdupois 
ounces,  sixteen  of  which  go  to  the  pound.  For  rough  approximations,  iron  in  general  may  be  taken  as 
weighing  one-fourth  of  a pound  to  the  cubic  inch.  So  far  as  crude  iron  is  concerned,  the  specific  gravity 
has  been  recently  considered  in  reports  upon  ordnance  to  the  American  government  to  be  an  index  of 
another  physical  property,  (of  the  greatest  interest  where  cannon  and  guns  are  concerned,)  viz.,  the 
tenacity  or  cohesive  force  of  the  metal.  Of  course,  such  indications  are  not  regarded  as  absolute,  but 
merely  relative ; and  they  have  been  supposed  hitherto  to  apply  only  to  the  best  sort  of  gray  foundry 
iron. 

Upon  this  property  of  tenacity  or  cohesion  of  iron  in  its  different  conditions,  experiments  have  been 
very  numerous  and  varied,  with  results  as  accordant  as  could  be  expected.  They  may  be  found  de- 
tailed more  or  less  fully  in  several  special  treatises;  such  as  of  Barlow,  Duleau,  Karsten,  Navier,  and 
Trcdgold.  The  results  of  those  whose  apparatus  may  be  considered  as  the  most  reliable,  seem  to  show 
that  cohesion  depends  not  only  upon  the  chemical  composition  of  the  metal,  but  also  upon  the  way  in 
which  it  has  been  treated ; the  amount  of  heat,  for  instance,  to  which  it  has  been  subject,  the  extent  of 
forging  it  has  received,  and  also  the  dimensions  which  have  been  given  to  it,  and  the  form  in  which  it 
lias  been  left.  Were  the  theory  of  the  resistance  of  materials  perfect,  the  behavior  of  the  metal  under 
one  position  or  set  of  circumstances  would  determine  for  any  or  all ; but  in  the  absence  of  such  theory, 
it  is  necessary  here  to  give  the  observed  results  in  the  chief  positions  and  circumstances  in  which  the 
resistance  of  iron  is  practically  called  into  play.  These  are  four,  viz. : 1.  Resistance  to  a force  tending 
to  pull  asunder  in  the  direction  of  length ; this  is  usually  termed  absolute  cohesion ; 2.  Resistance  to  a 
force  tending  to  crush  in  the  same  direction;  this  is  termed  relative  cohesion:  8.  Resistance  to  a force 
applied  at  any  angle  with  the  longitudinal  axis  of  the  mass,  or  a transverse  force ; this  is  termed  re- 
spective cohesion : 4.  Resistance  to  a twisting  force,  or  to  torsion.  As  to  resistance  to  impact  or  resili- 
ence, that  will  be  spoken  of  under  the  property  of  elasticity. 

1.  The  absolute  cohesion  of  malleable  iron  may  be  taken  for  square  bars  of  different  sizes  as  under; 
the  resistance  per  square  inch  being  proportioned  to  the  breaking  weight  of  the  respective  sizes. 

In  bars  I inch  square  ; resistance  per  square  inch  = 90,000  lbs. 

“ i “ “ “ =70,000  “ 

“ 1 inch  and  over  “ “ = 56,000  “ 

When  the  bars  are  round  with  the  same  area,  they  will  show  a somewhat  higher  resistance  than  the 
above;  and  w-hen  forged  flat  they  appear  more  resistant  than  when  round.  Iron  wire,  from  the  mode 
of  manufacture,  is  generally  supposed  to  exert  a greater  proportionate  resistance  than  hammered  iron ; 
but  its  average  may  be  taken  as  included  in  the  number  given  above.  * In  fact,  the  increase  of  resist- 
ance inversely  as  the  area  seems  to  progress  with  wire  to  a certain  point,  when  it  changes  sign,  and 
the  proportionate  strength  diminishes  with  the  area.  Thus,  in  Telford’s  experiments, 

a wire  ' inch  in  diameter  gave  a resistance  per  square  inch  of  94,080  lbs. 
and  “ ¥'T  “ “ “ “ 80,192  “ 

Dufours  experiments,  however,  do  not  justify  this  inference.  Annealed  iron  is  hardly  half  as  strong  as 
the  same  wire  unannealed.  All  these  numbers  being  extreme  loads,  it  will  be  readily  understood  that 
the  metal  ought  never  to  be  strained  to  such  a limit.  Up  to  a certain  point,  a bar  or  wire  will  stretch, 
and  when  the  strain  is  taken  off,  return  to  its  former  dimensions ; but  beyond,  although  it  will  continue 
to  stretch,  it  returns  no  more,  the  alteration  and  injury  are  permanent.  As  a general  rule,  it  is  inju- 
dicious to  load  iron  with  more  than  one-third  of  its  breaking  weight.  The  tables  of  Tredgold,  which 
are  extensively  used  and  found  safe  in  practice,  allow  the  strength  of  malleable  iron  in  this  sense  at 


72 


IRON. 


17,800  lbs.  per  square  inch,  -which  it  can  bear  without  permanent  alteration.  This  may  be  taken  foi 
ordinary  use  at  18,000  lbs.  per  square  inch. 

Crude  iron  is  but  rarely  employed  as  a tie ; so  that  a knowledge  of  its  absolute  cohesion  is  compara- 
tively of  little  practical  consequence,  and  there  have  been  proportionably  few  direct  experiments.  The 
mean  of  Tredgold’s  gives  44,620  lbs.  per  square  inch  as  the  breaking  weight.  The  results  of  Muschen 
brock,  Brown,  and  Rennie,  the  former  very  much  in  excess  and  the  latter  in  defect,  do  not  appeal 
reliable.  In  practice,  we  may  take  15,000  lbs.  per  square  inch  as  the  strain  that  gray  crude  iron  will 
bear  in  the  direction  of  its  length  without  permanent  alteration.  It  is,  therefore,  about  one-sixth  weaker 
than  malleable  iron.  White  crude  iron  has  not  been  experimented  upon  in  this  sense ; but  it  is  known, 
from  observations  on  transverse  strains,  to  be  much  weaker  than  gray  iron.  Iron  of  the  second  fusion 
[i.  e.  melted  and  cast  from  a cupola)  is,  in  general,  stronger  than  when  run  from  the  high-furnace.  The 
method  of  casting  (i.  e.  in  vertical  or  horizontal  moulds)  does  not,  as  far  as  observed,  affect  its  absolute 
cohesion. 

The  following  table  gives  the  mean  absolute  cohesion  of  divers  metals  cast  in  pounds  per  square 
inch,  viz. : 


Ratio. 

Cast-steel,  tilted 

135,000  lbs.... 

Crude  iron,  gray 

45,000  “ ... 

...i- 

Gun-metal, (copper  and  tin,)  34,000  “ ... 

...0-756 

Brass,  cast  

20,000  “ ... 

...0-444 

Gold,  cast  

20,000  “ ... 

...0-444 

Tin,  cast  

4,700  lbs.... 

Ratio 

...0-104 

Zinc,  cast 

2,800  “ ... 

...0  062 

Lead,  cast  

1,800  “ ... 

...0-040 

Antimony  cast,  

1,000  “ ... 

...0-022 

And  the  following  the  mean  proportionate  cohesion  of  some  of  them  when  drawn  into  wire ; iron  wire 
being  1,  or  unity. 


Copper 0587 

Platinum 0500 

Silver 0'342 

Gold 0-273 


Gold 0-273 

Zinc 0-200 

Tin  0-064 

Lead  0051 


Iron l'OOO 


2.  In  relative  cohesion,  or  resistance  to  crushing,  the  two  conditions  of  the  metal  appear  to  change 
places ; crude  iron  being  the  strongest.  The  mean  of  many  experiments  of  Karsten  gives  the  resistance 
in  this  sense  of  crude  iron,  gray,  at  168,750  lbs.  per  square  inch. 

“ white,  “ 210,540  “ “ 

The  specimens  were  of  the  first  fusion,  cast  from  a cupola,  and  poured  from  a reverberatory  furnace ; 
the  cupola  castings  were  very  uniformly  the  weakest,  and  those  from  the  air-furnace  the  strongest  of 
the  sets.  Those  moulded  vertically  were  also  at  a mean  2J  per  cent,  stronger  than  those  moulded 
horizontally.  Wrought-iron  has  not  been  extensively  observed  in  this  respect.  The  mean  of  the  ex- 
periments of  Rondelet  gives  70,000  lbs.  per  square  inch  (very  nearly)  as  the  weight  under  which  bars 
fron  ^ to  1 inch  square  began  to  give  way.  Its  texture  appears  to  prevent  it  from  being  crushed,  even 
with  the  weight  that  would  crush  crude  iron ; for  if  the  height  of  the  specimen  be  triple  its  thickness,  it 
will  bend  and  double  up  sooner  than  be  crushed.  The  practical  effect  in  either  case  upon  the  equilib- 
rium of  constructions  is  pretty  nearly  the  same.  We  are  warranted,  then,  in  considering  the  useful  rela- 
tive cohesion  of  wrought-iron  at  one-half  that  of  gray  crude  iron.  The  following  table  exhibits  this 
property  as  supposed  to  be  ascertained  for  some  other  metals,  viz. : 


Crude  iron,  white,  resistance  per  cubic  inch, 

210,000  lbs. 

ratio  l'OOOO 

“ gray. 

170,000  “ 

“ 0-8095 

Copper,  cast, 

117,000  “ 

“ 0-5571 

Malleable  iron,  “ 

85,000  “ 

“ 0-4048 

Copper,  wrought, 

55,000  “ 

“ 0-2620 

Tin,  cast,  “ 

9,000  “ 

“ 00429 

Lead,  cast, 

8,000  “ 

“ 0-0381 

The  last  four  were  not  crumbled  under  the  pressure,  but  flattened;  their  resistance  was  therefore 
entirely  overcome ; although  their  texture  did  not  allow  the  same  phenomena  as  belong  to  the  crystal- 
lized structure  of  the  others. 

3.  Experiments  on  respective  cohesion  of  iron,  i.  e.  its  resistance  to  transverse  strains,  have  been  very 
numerous.  Theoretically,  their  results  should  be  functions  of  the  absolute  cohesion  of  the  substance ; 
but,  partly  from  defect  of  theory,  and  partly  from  inherent  difficulties  and  errors  in  observation,  this  is 
not  exactly  the  case.  As  this  is  the  sort  of  resistance  most  extensively  required  in  practice,  its  deter- 
mination is  of  the  greatest  interest.  In  addition  to  the  variations  arising  from  the  qualities  of  the  metal 
itself,  it  depends  so  much  upon  the  dimensions  and  position  of  the  mass  exposed  to  strain,  upon  the 
ano-le  of  direction  of  the  force  or  weight,  and  upon  the  degree  of  deflection  that  the  equilibrium  of  con- 
struction will  allow,  that  the  statement  of  results  can  hardly  be  niore  condensed  than  the  statistics  ot 
the  experiments  themselves.  To  give  tables  for  practical  use  is  liable  to  the  same  objection  of  taking 
up  undue  space,  and  also  to  the  inconvenience  of  being  limited  in  their  application.  All  that  will  be 
done  here,  then,  is  to  furnish  genel  al  rules  which  may  safely  be  calculated  upon  in  all  cases  for  appor- 
tioning the  weight  to  the  dimensions  of  the  beam  which  is  to  bear  it,  viz. : 


100000 


bd\ 

IF ’ 


for  gray  crude  iron. 


w 

-j] 


bd3  , 

.=  62600-^-;  lor  white 
b d3 

= 135000  — ; for  wrought-iron. 


IRON. 


73 


Practical  Rule. — Divide  the  product  of  the  breadth  of  the  beam  ar.d  the  cube  of  the  depth  by  the 
square  of  the  length,  all  in  inches;  and  multiply  the  quotient  by  100,000  for  the  weight  in  pounds 
v.  hen  gray  iron  is  used.  With  white  iron  multiply  by  62,500  ; and  with  malleable  iron,  by  135,000  foi 
the  load  in  pounds.  These  coefficients  correspond  to  a maximum  deflection  in  the  middle  of  the  beam 
(which  is  assumed  to  be  solid)  of  -gB  of  an  inch  per  foot  in  length ; which  it  is  not  judicious  to  exceed, 
although  it  is  very  often  surpassed.  The  use  of  white  iron  should  be  as  much  as  possible  avoided  in 
resisting  strains  of  this  kind.  It  is  not  only  very  little  more  than  half  as  strong,  but  it  is  also  less  uni 
form  and  more  uncertain.  * 

These  formulae  and  rules  apply  to  instances  where  the  beam  is  supported  at  both  ends,  and  strained 
by  a force  acting  in  the  middle  of  the  length,  as  in  the  case  of  mill-shafts,  &c.  Where  the  load  is  uni- 
formly distributed  over  the  length  of  such  a supported  beam,  the  effect  is  the  same  as  if  five-eighths  ol 
this  load  were  applied  in  the  middle  of  the  length,  and  the  weight  borne  in  this  case  will  be  lT6ff 
times  that  ascertained  by  the  rule  just  given. 

When  the  beam  is  square,  the  formula  and  rules  equally  apply  as  when  it  is  merely  rectangular.  If 
it  be  cylindrical,  supported  at  both  ends  and  loaded  in  the  middle,  divide  the  weight  obtained  by  the 
rule  for  a square  beam  whose  side  equals  the  given  diameter  by  lyA  for  the  load  that  will  produce  the 
same  deflection.  If  the  load  is  to  be  uniformly  distributed  over  the  length  of  a cylindrical  beam,  it  is 
near  enough  in  practice  to  consider  that  its  strength  and  stiffness  will  be  the  same  as  in  a square  beam 
with  sides  equal  to  the  diameter  of  the  cylinder,  and  loaded  with  the  same  weight  in  the  middle  of  it? 
length. 

In  all  these  cases,  the  weight  of  the  beam  itself  must  be  taken  into  the  account  as  part  of  the  load, 
either  uniformly  distributed  or  centered  in  the  proportion  of  5 : 8,  as  the  case  may  require.  To  diminish 
as  far  as  possible  the  useless  load  in  such  instances,  it  is  not  unusual  to  make  the  beam  or  shaft  a hol- 
low cylinder.  The  rule  for  determining  the  dimensions  becomes  complicated ; for  strength  and  stiffness 
do  not  follow  the  same  ratio  of  diameters.  In  general,  it  may  be  remembered  that  when  the  thick- 
ness of  the  metal  is  one-fifth  of  the  diameter,  (which,  if  the  load  is  considerable,  is  not  more  than  a safe 
proportion,)  the  strength  of  the  hollow  cylinder  is  nearly  two-thirds,  and  the  stiffness  one-half  nearly  of 
what  they  would  be  respectively  in  a square  beam  of  the  same  depth,  while  there  is  a saving  of  one- 
half  the  quantity  of  metal. 

4.  The  capacity  to  resist  torsion  is  of  great  importance  in  the  substance  of  which  the  revolving  parts 
of  machinery  are  made ; for  it  is  not  unfrequently  by  a submission  to  torsion  that  both  power  and  dura- 
bility are  secured.  Navier  has  explored  the  theory  of  this  resistance ; but  the  experimental  constants 
which  are  required  to  make  the  theory  of  practical  application  are  unfortunately  deficient.  The  results 
of  the  observations  made  hitherto  are  remarkably  discordant.  The  following  table  gives  the  propor- 
tionate resistance  in  this  respect  of  various  metals. 


Cast-steel, 19  '5  6 

Shear  “ 17'06 

Blister  “ IG‘69 

Crude  iron,  (cast  vertical,) 1063 

Wrought-iron,  (coal,)  10T3 

“ (charcoal,) 9'50 


Crude  iron,  (cast  horizontal,) 9'94 

Hard  gun-metal 5'00 

Fine  brass, 4 69 

Copper,  (cast,) 4-31 

Tin, 144 

Lead,.... TOO 


It  appears  from  this,  that  iron  in  all  its  conditions  exercises  this  resistance  pre-eminently ; and  that 
crude  iron  does  not  differ  in  this  respect  materially  from  wrought-iron.  It  has  been  generally  assumed 
in  metallurgic  treatises  hitherto,  that  resistance  to  torsion  is  in  proportion  to  absolute  cohesion.  The  ex- 
periments, so  far,  do  not  sustain  this,  as  between  malleable  and  crude  iron. 

In  a preceding  paragraph,  a distinction  has  been  made  between  strength  and  stiffness.  Although 
both  are  in  part  functions  of  the  absolute  cohesion,  yet  the  latter  is  a measure  more  particularly  of 
another  physical  property — that  of  elasticity.  It  is  in  virtue  of  its  cohesive  strength  that  a substance 
resists  any  change  of  form  or  position ; it  is  in  proportion  to  its  elasticity  that  such  changes,  when  occur- 
ring, are  not  permanent.  Thus,  up  to  a certain  point,  a bar  or  wire  which  has  been  lengthened  by  a 
strain  will,  when  the  strain  is  removed,  return  to  its  original  length ; or  a beam  that  has  been  deflected 
by  a load  will,  upon  being  relieved  from  the  load,  reassume  its  horizontal  position.  When  this  point  is 
passed,  and  the  extension  or  deflection  remain  permanent  after  the  cause  producing  them  has  ceased  to 
act,  we  say  ordinarily  that  the  piece,  whatever  it  may  be,  has  taken  a set,  and,  technically,  that  its  elas- 
ticity is  overcome  or  destroyed.  Gray  crude  iron  will  allow  an  extension,  within  the  limits  of  its  elas- 
ticity to  recover,  of  -j-^Vo  °t  its  original  length  when  the  strain  is  acting  in  that  direction : it  is  not  safe 
to  allow  for  a greater  deflection  in  masses  which  have  to  bear  a permanent  load,  (such  as  joists,  girders, 
<fcc.,)  than  fff-  of  an  inch  for  each  foot  in  length,  or  say  of  the  length,  in  round  numbers.  White  iron 
is  not  reliable  either  for  extension  or  deflection.  Malleable  iron  will  bear  an  extension  without  injury  of 
i'tVtt  ds  length,  only  its  deflection  ought  not  to  be  allowed  to  surpass  of  its  length.  These  de- 
flections are  of  course  measured  where  they  are  the  greatest,  viz.  in  the  middle  of  the  length. 

There  is  another  manifestation  of  elasticity  in  resistance  to  impact,  or,  as  it  is  technically  termed,  in 
resilience  ; in  virtue  of  which  a s’’Vtance  yields  in  form  or  position  to  the  momentum  of  a sudden  im- 
pulse or  blow,  and  then  returns  to  its  original  state.  This  resistance  is  of  great  importance  in  machinery, 
to  aid  in  determining  what  velocity  the  moving  masses  should  be  allowed  to  have ; for  the  impact  and 
shock  are  the  same  whether  the  substance  in  question  strikes  against  a body  at  rest,  or,  itself  at  rest 
:s  struck  by  a body  in  motion.  In  theory,  resilience  is  a function  of  absolute  cohesion,  and  of  density  as 
(veil  as  of  elasticity  ; and  hence  certain  woods  possess  this  property  in  a higher  degree  than  many 
metals,  and  nearly  as  high  as  iron  itself.  Whalebor  exhibits  it  in  a pre-eminent  degree. 


74 


IRON. 


Table  showing  the  •proportionate  Resilience  or  Resistance  to  Impact  of  divers  Substances. 


Iron,  (crude  or  wrought,) T000 

Gun-metal,  (copper  8 + tin  1,)  cast 0819 

Yellow  Pine,  (American,)  0-740 

Oak,  (English,)  0'724 

Mahogany, 0-630 

Elm,  (English,) O620 

Ash,. 0600 

White  Fir, 0 567 


Iron,  (crude  or  wrought,) . 1 000 

Brass,  (cast,) 0-400 

Beech,  0’326 

Larch 0-315 

Lead,  (cast,) 0-246 

Zinc,  “ 0190 

Tin,  “ 0142 

Whalebone, 3 000 


The  following  comparative  summary  may  be  taken  of  the  chief  practical  resistances  of  iron  and  some 
other  substances  employed  in  constructions  and  in  machinery. 


Crude  iron,  (gray.) 

Brass,  

Gun-metal,  (copper  and  tin,) 

Iron,  (malleable,) 

Lead,  

Marble,  (white,) 

Oak, 

Tin,  

Zinc, 


Strength. 

Extensibility. 

Stiffness. 

. 1-00 

1-00 

1-00 

..  0-44 

0-90 

0-49 

. 0-65 

1-25 

0'54 

. 1-12 

0-80 

1-35 

..  o-io 

2-50 

0-04 

1-00 

0-14 

. 0-25 

2-80 

0-09 

. 0T8 

0-75 

0-25 

..  0-37 

0-50 

0-76 

The  remaining  properties  of  iron  connected  with  its  texture  do  not,  as  yet,  admit  of  being  numerically 
valued  or  proportioned.  Such  is  the  case,  for  instance,  with  malleability,  or  the  capacity  of  being  ex- 
tended in  one  or  more  directions  by  hammering.  White  crude  iron  does  not  display  this  property  at 
all;  gray  iron  possesses  it  generally  in  a slight,  and  sometimes  in  a considerable  degree.  Wrought- 
iron  in  this  respect  is  inferior  to  gold,  silver,  copper,  tin,  cadmium,  platinum,  lead,  and  zinc;  the  order 
of  the  names  here  representing  the  order  of  malleability  in  actual  extent  of  surface  which  can  be  given 
to  a unitary  mass  of  the  same  volume,  by  the  most  suitable  treatment.  All  other  metals  are  inferior 
to  iron  in  this  aspect ; though,  if  the  question  were  as  to  the  extent  of  surface  which  could  be  gained  by 
a continuous  hammering,  its  relations  would  be  altered.  It  tends  to  become  very  brittle  by  forging; 
and,  besides  requiring  the  application  of  great  force  in  the  aggregate,  has  to  be  frequently  softened  by 
heat  during  the  process.  The  harder  the  iron  is  in  its  original  state  as  wrought-iron,  the  more  often 
?neh  softening  has  to  be  resorted  to ; whence  it  may  be  inferred  that,  ceteris  paribus,  the  softer  the  iron 
the  more  malleable  it  should  be.  And  the  same  inference  attaches  in  the  property  of  ductility,  or  capa- 
city for  being  drawn  into  wire.  This  is  in  so  far  different  from  malleability,  that  heat  is  a necessary 
part  of  the  process  if  it  is  carried  to  any  great  degree ; afid  the  order  of  ductility  of  the  several  metals 
varies  from  that  of  their  malleability  accordingly.  Gold,  silver,  and  platinum  are  the  only  metals  more 
ductile  than  iron. 

Magnetism,  or  the  property  of  permanent  polarity,  was  formerly  supposed  to  belong  to  iron  only. 
Later  researches  show  that  this  is  to  be  shared,  though  not  equally,  with  nickel,  cobalt,  and  chromium. 
Occasional  magnetism  may  be  excited  in  most  substances  ; as  is  shown  by  their  influencing  the  oscilla- 
tions of  a freely  suspended  magnetic  needle.  But  this  influence  is  much  weaker  in  all  other  substances 
than  the  four  named.  Silver,  which  stands  the  highest  of  all  the  other  metals,  is  nine  times  feebler  in 
this  respect  than  iron  ; gold  fifteen  times,  and  marble  nearly  twenty  times,  more  weak.  Iron  acquires 
magnetism  by  contact  or  suitable  friction  with  a magnet ; by  being  suitably  rubbed  or  struck  in  a 
proper  position  ; by  exposure  to  refracted  light  of  the  sun  ; and  even  by  being  left  to  stand  in  a nearly 
vertical  position.  The  processes  for  this  purpose  will  be  described  under  the  proper  article.  (See  Mag- 
netism.) It  is  enough  to  say  here,  that  owing  to  the  ease  with  which  it  is  accidentally  developed,  it  is 
extremely  difficult  to  find  in  the  shop  of  a philosophical  instrument-maker,  for  instance,  a tool  or  scrap 
of  iron  which  is  not  in  some  degree  magnetic.  In  all  its  conditions  and  states  it  is  susceptible  of  this 
property,  but  develops  it  differently  in  each.  Thus,  gray  crude  iron  becomes  sooner  and  more  intensely 
magnetic  than  white  iron  ; but  yields  in  both  these  regards  to  wrought-iron  and  to  steel.  Soft  ductile 
iron  is  more  easily  and  more  strongly  magnetizable  than  steel,  but  does  not  retain  its  magnetism  as 
well.  A similar  relation  is  observable  between  untempered  and  tempered  steel.  The  magnetism  of 
iron  may  be  weakened  or  lost  by  methods  similar  to  those  which  originally  impressed  it.  'The  filings 
of  a magnet  are  less  magnetic  than  the  solid  mass.  A heavy,  sudden  blow  or  shock,  against  a hard 
body,  will  sometimes  destroy  magnetism.  Heat  always  diminishes  it ; although  there  are  some  pecu- 
liarities which  have  been  observed  in  this  regard  that  are  difficult  of  explanation.  It  undergoes  dete- 
rioration whenever  similar  poles  of  two  equally  strong  magnets  are  kept  in  prolonged  contact ; and 
finally,  is  always  abated  by  alloying  with  other  substances,  and  may  be  destroyed  entirely  by  increasing 
the  proportion  of  alloy.  Arsenic  is,  in  this  regard,  the  most  active  of  the  metals ; though  an  alloy  of 
two-thirds  arsenic  does  not  entirely  prevent  the  mass  from  being  attracted  by  the  needle.  Mushet, 
however,  affirms  that  twenty-two  per  cent,  of  manganese  effectually  destroys  magnetism  in  an  alloy 
of  iron. 

Malleable  iron  is  an  excellent  conductor  of  electricity ; and  although  in  this  respect  inferior  to  copper 
and  zinc  among  the  easily  oxidized  metals,  and  to  gold,  silver,  and  platinum  among  the  others,  it  is  yet, 
for  economy,  universally  employed  for  lightning-rods.  In  the  Voltaic  pile  it  follows  zinc  in  the  order  ot 
electro-positive  metals. 

Its  electro-magnetic  properties  are  very  remarkable,  in  the  facility  with  which  it  is  converted  into  a 
magnet  of  great  energy  during  the  passage  through  it  of  an  electric  current.  It  is  to  this  that  the  elec 
tro-magnetic  telegraph  owes,  in  part,  :.ts  adaptation  and  success. 


IRON. 


75 


Hitherto  the  properties  of  iron  have  been  considered  as  manifesting  themselves  at  ordinary  tempera- 
tures. It  temains  to  speak  of  the  modifications  and  peculiarities  which  arise  from  its  affection  hy  heat 
Of  all  the  metals,  this  lias  the  greatest  specific  heat ; i.  e.  the  greatest  capacity  for  heat,  or  faculty  of 
resisting  change  of  temperature.  It  bears  a greater  quantity  of  caloric  for  a longer  time,  and  with  less 
alteration  of  its  own  sensible  temperature.  The  index  of  its  specific  heat  has  been  observed  by  Dulong 


and  Petit  as  follows  : 

32°  F.  to  212°  F 0T098 

392°  F 0T150 

572°  F 0T218 

662°  F 0T255 


Supposing  the  capacity  for  heat  to  augment  in  the  same  ratio,  we  would  have  at  the  supposed  epoch 
of  red-heat  an  index  - 0T402,  and  near  the  probable  point  of  fusion  = 0'3282  ; that  of  water  in  equal 

weight  being  P000.  The  specific  heat  varies  according  to  the  condition  of  the  metal,  and  appears  to 
be  in  some  proportion  to  the  quantity  of  carbon  associated  in  each.  Thus  the  specific  heat  of  steel,  as 
observed  by  Regnault,  is  represented  by  the  index  = 0T1848,  and  that  of  white  crude  iron  ~ 0T2983. 
Gray  crude  iron,  as  far  as  may  be  inferred  from  observations  of  refined  iron,  would  have  a lower  index 
than  white  iron,  but  there  are  not  observations  to  settle  this. 

The  expansion  of  iron  by  heat  presents  it  in  a similarly  advantageous  character.  It  expands  less 
than  any  of  the  metals  except  platinum,  palladium,  and  antimony.  The  observations  hitherto  have 
been  made  principally  upon  its  expansion  in  one  direction ; i.  c.  its  linear  expansion,  or  extension.  It  is 
supposed  to  be  accurate  enough  for  practice  to  consider  this  extension  as  equal  in  all  directions,  and  as, 
therefore,  the  one-third  of  the  cubic  expansion.  All  the  experiments  upon  the  extension  of  crude  iron 
have  been  with  metal  of  the  second  fusion,  which  is  almost  always  gray.  It  may  be  presumed  from 
practical  phenomena  on  the  large  scale,  that  white  iron  expands  less  than  gray.  The  mean  of  the  re- 
sults of  Roy,  Lavoisier,  and  Daniell  with  cast-iron,  gives  an  extension  in  length  of  0-0010974249  between 
32°  F.  and  212°  F. ; the  original  length  being  1' at  32°  F.  This  corresponds  to  an  extension  (suffi- 
ciently accurate  for  practical  use)  of  T__2__T  of  the  original  length  at  32°  for  each  degree  of  Fah- 
renheit. The  extension  of  wrought-iron  has  been  more  frequently  and  more  variantly  observed.  The 
results  lie  between  0 000600  of  Bonguer  and  0-001446  of  Hallstrom,  as  the  extension  on  a length  origi- 
nally I-  at  32°  F.  Theoretical  considerations,  as  well  as  an  average  of  the  most  reliable  observations 
determine  this  extension  at  0'0011356  for  180°  between  the  melting  of  ice  and  the  boiling  of  water  ; 
corresponding  to  Yorjrfa  orr  of  the  original  unity  for  1°  F.  The  extension  of  steel  appears  to  be  uni- 
formly higher  than  this,  and  to  vary  according  to  the  temper  of  the  metal  in  that  condition.  (See 
Steel.)  Between  the  limits  given,  the  rate  of  expansion  may  be  taken  as  constant  for  each  degree, 
although  in  strictness  such  is  not  the  fact ; beyond  212°  F.  it  would  not  be  proper  to  rely  upon  such  an 
assumed  constancy  : but  at  these  higher  temperatures  a knowledge  of  the  dilatation  is  chiefly  interest- 
Ag  in  theoretical  science.  Rinman  supposed,  from  some  observations,  that  between  ordinary  summer- 
heat  (say  76°  F.)  and  what  is  called  red-heat,  crude  iron  extended  ^ and  wrought-iron  - [ (T  of  its 
original  length  : but  these  estimates  can  hardly  be  relied  upon.  The  following  table  presents  the  most 
probable  values  in  this  particular,  as  well  as  certain  other  phenomena  : 

Table  showing  the  actual  Extension  of  Wrought-iron  at  various  Temperatures. 


-ee  of  Fahrenheit. 

T_.ength . 

20° 

1- 

91  9. 

1-0011356 

392  

1-0025757  ) 

572 

1-0043253  V 

752 

1-0063894  ) 

932 

1-0087730  \ 

112 

1-0114811  ) 

!S52 

1-0216024  \ 

2192 

-’732 

1-0512815  ) 

2912 

cohesion  destroyed. 

Surface  becomes  straw-colored,  deep  yellow,  crimson, 
violet,  purple,  deep  blue,  bright  blue. 

Surface  becomes  dull,  and  then  bright  red. 


Fusion  perfect. 

In  the  property  of  conducting  heat,  iron  occupies  a low  rank.  The  following  statement  is  warranted 
by  the  observations  of  Dergnetz  : 


Substances.  Conducting  Power. 

Gold 2-6728 

Platinum 2 6223 

Silver 2-6009 

Copper 2-4010 

Zinc 09722 

Iron 1- 


Substances.  Conducting  Power. 

Ikon T 

Tin 0-8121 

Lead  0-4801 

Marble 0-0625 

Porcelain 0-0326 

Brick-clay  0-0302 


These  observations  refer  to  malleable  iron.  Crude  iron,  whose  specific  heat  is  greater  than  its  dilatabilitv 
is  less  than  the  same  properties  of  wrought-iron,  is,  it  may  be  inferred,  a worse  conductor.  Upon  its  power 
of  absorption,  radiation,  and  reflection  of  heat,  in  either  condition,  there  have  been  no  reliable  observations. 

Besides  the  influence  upon  dilatation,  an  effect  seems  to  be  produced  upon  the  cohesive  force  of  iron 
by  temperatures  either  higher  or  lower  than  ordinary.  In  regard  to  low  temperatures,  it  may  be 
assumed,  in  general,  that  they  promote  fragility.  It  is  uniformly  observed  that  iron  is  much  more 
brittle  in  winter  than  in  summer  ; and  this  holds  good  equally  for  all  conditions  of  the  metal.  Cold 
weather  is,  therefore,  unfavorable  for  any  practical  test  of  quality,  (such  as  for  cannon,  chain-cables,  die.;  j 


76 


IRON. 


especially  one  dependent  in  any  way  upon  impact.  On  the  other  hand,  with  temperatures  higher  that 
ordinary,  but  yet  below  the  point  of  boiling  water,  Tredgold  supposes  the  absolute  cohesion  to  be  di 
minished  by  an  elevation  of  1°F.  in  temperature.  Under  temperatures  which . transcend  thr 

boiling  point  of  water,  the  table  given  above  has  already  indicated  the  most  remarkable  phenomenon— 
the  iridescence  or  succession  of  colors  during  the  augmenting  application  of  heat.  To  what  this  effect  is 
owing  is  not  known ; partially,  perhaps,  to  the  color  produced  by  the  contact  of  thin  plates,  and  par- 
tially to  an  oxidation  of  surface.  This  last  cause  is  assured  by  the  permanence  of  the  color  after  the 
heat  has  ceased  to  be  applied.  The  straw  color  is  developed  fully  at  400°  F.,  the  fusing  point  of  tin  ; 
the  deep  yellow  occurs  at  420°  F. ; crimson  follows  at  450°  F.,  where  bismuth  fuses  ; from  that  vio'et, 
purple,  and  deep  blue  succeed,  till  540°  F.,  the  melting  point  of  lead ; this  blue  brightens,  passes  into 
sea-green,  and  at  last  disappears  at  700°  F.,  the  fusing  point  of  zinc.  Beyond  this,  the  epochs  of  tem- 
perature have  no  distinctive  test.  But  if  the  heat  is  continued,  there  occurs  a secondary,  and,  finally, 
just  before  red  heat,  a tertiary  succession  of  the  same  color  and  in  the  same  order,  only  less  vivid  and 
less  lasting.  If  the  metal  be  withdrawn  at  the  close  of  this  tertiary  series,  its  surface  will  be  found 
covered  with  a thin  pellicle  of  oxide,  whose  constitution  has  not  yet  been  examined.  The  practical 
utility  of  these  color-tests  is  principally  found  with  steel,  where  they  serve  as  guides  to  determine  the 
probable  temper  imparted.  The  deep-blue  color  is  also  used  in  the  arts  as  an  ornamental  and  anti- 
oxidable  tint.  Iron,  in  its  different  conditions,  is  not  similarly  affected  in  this  respect.  In  general,  steel 
is  colored  at  a lower  temperature  than  what  has  been  given  as  applicable  to  the  case  of  malleable  iron, 
and  gray  iron  at  a higher  one.  White  iron  has  not  been  as  yet  experimented  on.  But  as  there  is  rea- 
son to  conclude  that  the  colors  occur  in  the  direct  ratio  of  the  hardness  of  the  metal,  white  crude  iron 
may  be  expected  to  surpass  steel.  Of  the  same  bar,  the  harder  and  softer  portions  are  emphatically 
designated  in  this  process.  The  coloring  thus  depending  on  hardness,  its  brilliancy  is  determined  by  the 
state  of  polish  of  the  surface.  And  as  the  hardness  of  the  metal  thus  influences  the  phenomena  of 
colors,  so  it  is  in  its  turn  reacted  on  by  the  heat  which  produces  them.  It  is  on  this  account  that  iron 
which  has  become  hard  in  being  wrought  and  hammered,  is  exposed  to  heat  in  order  to  soften  it,  as  has 
been  noticed  before.  The  degree  of  heat  requisite  is  in  proportion  to  the  hardness  existing  and  to  the 
softness  required  : in  practice,  however,  it  is  generally  a full-red  heat.  Iron,  in  all  its  conditions,  ap- 
pears to  be  permanently  softened  by  being  thus  heated,  whatever  may  have  been  its  character  or 
treatment  before.  The  hardness  and  brittleness  which  may  be  cured  by  this  resort,  must  be  distin- 
guished from  the  same  characteristics  arising  from  a peculiar  chemical  composition.  Thus,  there  is  a 
sort  of  iron  which  becomes  brittle  by  the  application  of  heat.  Metal  of  this  class  is  well  known  under 
the  name  red-short,  or  hot-short,  and  is  met  with  in  all  conditions.  Again,  there  is  a kind  of  iron  pre- 
cisely opposite : brittle  at  ordinary  temperatures,  it  becomes  tenacious  when  hot ; though,  like  the  other,  it 
undergoes  no  permanent  change,  and  the  modified  characteristic  belongs  only  to  the  modified  temperature. 

Sudden  cooling  appears  to  augment  the  effect  of  low  temperature,  and  to  impart  greater  or  less 
hardness  to  the  metal,  according  to  its  previous  quality.  In  the  ease  of  steel,  this  is  of  the  utmost 
interest ; for  on  it  depends  the  whole  business  of  tempering.  In  other  conditions  the  effect  is  less 
maiked,  but  sufficiently  sensible  whenever  the  conducting  power  of  the  cooling  material  is  not  out  of 
proportion  to  the  mass  of  metal  acted  upon.  The  conducting  power  of  the  air  is  never  sufficient,  ordi- 
narily, to  produce  any  of  the  phenomena  of  sudden  cooling  : exposed  to  that,  the  cooling  is  always 
slow,  and,  according  to  its  temperature,  follows,  more  or  less,  th  ? softening  effects  which  have  been 
already  spoken  of,  and  which  are  technically  known  as  annealing.  But  this  will  be  spoken  of  more 
particularly  under  the  metallurgic  treatment  of  iron. 

The  effect  of  sudden  cooling  is  more  manifest  in  temperatures  higher  than  red  heat,  and  especially 
upon  the  metal  in  fusion.  The  observation  of  this  is  more  readily  made  upon  crude  than  wrought-iron ; 
and  the  most  remarkable  effect  is  the  conversion  of  gray  iron  into  white,  which  takes  place  more  or  less* 
completely  in  proportion  (other  things  being  equal)  to  the  mass  operated  upon.  On  the  other  hand, 
white  iron  can  be  converted  into  gray  by  an  opposite  method  of  treatment ; and  this  not  only  on  the 
small  scale,  but  also  in  large.  Indeed,  as  was  said  before,  iron  of  the  second  fusion,  allowed  to  cool 
slowly,  is  almost  uniformly  gray.  But  gray  iron,  cast  in  moulds  of  any  sort  which  conduct  heat  with 
sufficient  rapidity,  (such  as  cast-iron  moulds,)  uniformly  chills,  as  it  is  termed ; i.  e.,  becomes  converted, 
to  a greater  or  less  depth  from  the  surface,  into  white  iron.  Practical  advantage  is  taken  of  this  in  the 
manufacture  of  wheels  for  railroad  cars,  which  are  always  purposely  chilled  to  increase  their  durability. 

It  is  at  temperatures  above  red  heat  that  the  most  important  and  practically  useful  modifications  of 
this  metal  take  place  in  all  its  conditions.  Not  to  refer  any  further  to  steel,  the  welding  of  malleable 
iron  and  the  fusion  of  crude  iron,  by  which  either  of  these  are  made  applicable  to  the  arts  and  wants  oi 
mankind,  occur  at  about  the  same  epoch  of  temperature,  somewhat  further  removed  from  red  heat  than 
this  last  is  from  ordinary  states.  The  table  before  given  has  already  indicated  the  temperature  of  the 
probable  fusion  of  malleable  iron,  which  is  a little  above  that  of  crude  iron.  The  uncertain  indications 
of  Wedgwood’s  pyrometer  for  a long  time  induced  an  erroneous  estimate  of  the  amount  of  heat  required 
for  the  fusion  of  metals  generally,  and  especially  that  of  iron.  Daniell  has  shown,  by  experiment  with 
a much  more  reliable  apparatus  than  that  of  Wedgwood,  that  cast-iron  (so  called)  cannot  require  a 
higher  temperature  for  fusion  than  would  be  expressed  by  2786°  F.;  while  Alexander  has  demonstrated, 
from  the  known  relations  and  properties  of  cohesive  force  and  specific  heat,  that  bar-iron  (whose  utter 
infusibility  was  long  maintained)  must  become  fluid  at  about  2774°  Fahr.  We  are  yet  deficient  in  a 
pyrometer  whose  indications  would  be  uniform  when  applied  in  temperatures  as  high  as  this,  a desid- 
eratum whose  supply  would  contribute  materially  to  the  filling  up  of  /he  theory  of  the  manufacture  ot 
iron.  It  is  probable  that  an  air-thermometer,  whose  tube,  where  it  entered  the  furnace,  is  of  platinum, 
would  afford  the  most  unexceptionable  and  reliable  results. 

The  capacity  for  being  welded,  i.  e.  performing  an  intimate  and  perfect  union  of  two  surfaces,  occurs 
at  the  epoch  of  incipient  fusion.  This  property  is  possessed  by  iron  alone  of  all  the  metals,  except  pla- 
tinum and  palladium.  White  crude  iron,  under  ordinary  treatment,  does  not  show  this  characteristic 


IRON. 


/ i 


at  all.  Gray  iron  is  weldable,  but  in  such  narrow  limits  of  temperature  that  the  operation  has  to  be 
effected  with  great  quickness  in  order  to  succeed.  With  bar-iron  and  steel,  in  sufficient  masses,  welding 
is  of  every-day  application.  If  the  masses  be  very  small,  they  cool  too  quickly  to  be  welded  in  the 
ordinary  way.  Crude  iron  in  fusion  occupies  a less  space  than  when  solid ; in  this  respect  its  anomaly 
(which  is  to  be  traced  to  crystallization)  is  shared  with  antimony,  bismuth,  sulphur,  and  zinc,  among  the 
metals,  all  of  which  shrink  in  melting.  The  same  may  be  observed  c.f  water,  which  is  more  dense  when 
fluid  than  when  crystallized  in  the  shape  of  ice.  If  a mass  of  crude  iron  be  made  hot  and  laid  upon  a 
bath  of  melted  metal,  it  floats ; but  if  it  be  cold,  it  tends  to  sink.  Perhaps  this  may  be  owing  to  die 
repulsive  effect  of  heat.  White  iron,  in  this  respect,  shrinks  less  than  gray.  On  an  average,  good  gray 
foundry  iron  shrinks  rather  more  than  the  ? o^Vo  o °f  *ts  volume  when  cold.  The  general  allowance  of 
the  founders  in  making  their  patterns  is  g of  an  inch  to  the  foot  lineal. 

Exposed  to  heat  at  any  temperature  from  red  heat  upwards,  witli  access  of  air,  iron,  in  all  its  condi- 
tions, is  readily  covered  with  a coating  of  oxide.  Bar-iron  is  thus  oxidated  more  easily  than  crude 
iron ; and  of  this  latter,  gray  iron  forms,  at  the  same  temperature,  a more  friable  oxide  than  white. 
The  following  contrast  may  be  taken  to  exhibit  the  most  important  characteristics  of  the  two  conditions 
of  crude  iron  when  exposed  to  high  temperatures,  viz. : — 


Gray  Iron 

Is  less  easily  oxidated  ; preserves  its  character 
longer,  but  loses  it  (cohesion,  &c.)  more  completely 
at  last;  suffers  these  changes  more  when  protected 
from  the  air ; heated  below  the  fusing-point,  with 
access  of  air,  demands  more  heat  and  more  air  to 
assume  a certain  malleability ; requires  a higher 
temperature  for  fusion ; when  fused  is  more  liquid ; 
expands  more  in  cooling  ; fused  rapidly  and  cooled 
quickly,  tends  to  become  white ; fused  rapidly  and 
cooled  slowly,  retains  its  character  or  becomes 
more  soft. 


White  Iron 

Is  more  easily  oxidated ; loses  its  character  sooner, 
and  becomes  granular,  grayish,  and  steel-like  in 
malleability  and  temper ; suffers  these  changes 
more  when  protected  from  the  air ; heated  below 
the  fusing-point,  with  access  of  air,  becomes  quite 
malleable,  and  may  be  tempered  to  take  an  edge ; 
fuses  at  a lower  temperature ; when  fused  is  less 
liquid  and  more  pasty ; expands  less  in  cooling ; 
fused  rapidly  and  cooled  quickly,  becomes  ex- 
tremely brittle ; fused  rapidly  and  cooled  slowly, 
becomes  gray. 


The  precautions  necessary  in  view  of  these  peculiarities,  as  well  as  the  general  processes,  will  be  de- 
scribed under  the  head  of  Bounding  ; and  what  has  been  said  may  be  considered  as  covering  the  chief 
physical  properties  of  the  metal. 

Chemical  affinities  and  reactions. — These  have  been  observed  for  the  most  part  with  the  iron  of  com- 
merce, which  is  never  entirely  pure,  but  contains  carbon,  silicon,  phosphorus,  sulphur,  arsenic,  chromium, 
titanium,  magnesium,  aluminum,  and  manganese,  in  very  minute  proportions.  Nitrogen  is  sometimes 
met  with ; but  oxygen,  which  was  formerly  considered  a constituent,  has  not  been  recognized  in  the 
later  researches  of  the  most  accurate  chemists.  The  chemical  symbol  of  iron  is  Fe,  and  its  atomic 
weight  339-205,  oxygen  being  taken  as  100.  In  the  system  where  hydrogen  = 1-  the  atomic  weight  of 
iron  is  28-,  as  an  average  round  number. 

With  oxygen,  iron  combines  in  two  proportions,  whose  resulting  compounds  appear  capable  of  fresh 
combinations,  so  that  in  point  of  fact  four  compounds  are  known  to  exist.  The  first  is  the  state  of  pro- 
toxide, which  does  not  exist  naturally  nor  artificially,  except  as  a hydrate.  The  second  in  the  proportion 
of  oxygen  is  the  forge-cinder , formed  on  the  surface  of  the  metal  by  heat,  with  access  of  air,  and  thrown 
off  under  the  hammer  or  squeezer.  The  third  is  the  black  or  magnetic  oxide,  (the  oxidum  ferroso- 
ferricum  of  Berzelius,)  which  exists  also  naturally;  and  the  fourth  is  the  peroxide,  red  oxide,  or  sesqv.i- 
oxide,  the  first  and  last  of  which  epithets  are  used  according  to  different  theories  of  its  constitution.  This 
also  exists  as  a mineral,  under  the  name  of  red  hematite,  and  is  massive,  fibrous,  or  crystallized,  according 
to  circumstances.  Its  hydrate  is  known  to  mineralogists  as  brown  hematite. 

The  following  tabic  contains  all  that  need  be  given  about  these  oxides  : — 


Composition.  Atoms.  Proportionate 

Name.  Iron.  Oxygen.  Iron.  Oxygen.  Iron.  Oxyg.  Index  of  Oxygei 

Protoxide  0-T723  + 02277  100  + 29'48  3 + 6 24 

Forge-cinder 0-7516  + 0-2474  100  + 32-90  3 + 7 27 

Magnetic  oxide  0-7178  + 0-2821  100  + 39'30  3 + 8 82 

Peroxide 0-6934  + 0-3066  100  + 4422  3 + 9 36 


The  three  first  are  attracted  by  the  magnet,  the  last  is  not.  The  colors  which  have  been  before  spoken 
of  as  accompanying  different  degrees  of  the  application  of  heat,  are  also  doubtless  due  to  the  formation 
of  oxides,  whose  constitution,  however,  is  not  known.  The  affinity  of  iron  for  oxygen  appears  to  be  in 
proportion  to  its  own  purity,  and  also,  though  in  a less  degree,  to  the  state  of  its  surface.  So,  in  respect 
to  that  peroxidation  which  is  very  familiar  as  rust,  and  which  tends  to  occur  more  or  less  upon  this 
metal  when  exposed  to  the  action  of  the  air,  (and  especially  damp  air,)  white  iron  is  less  affected  than 
gray,  and  any  crude  or  cast-iron  less  than  the  malleable  metal.  This  difference  of  the  different  condi- 
tions holds  good  in  the  case  of  moisture  alone,  and  in  general  with  most  chemical  agencies. 

Pure  viater,  disengaged  of  air,  does  not  act  upon  iron  at  all  at  ordinary  temperatures.  Above  120° 
Fahr.,  the  water  is  slowly  decomposed,  and  yields  its  oxygen ; at  212°  Falir.,  the  decomposition  is  quite 
sensible ; and  at  a red  heat  it  is  very  rapid,  hydrogen  is  given  off,  and  magnetic  oxide  formed.  At 
intermediate  degrees,  the  action  is  nearly  in  proportion  to  the  temperature.  In  practical  cases,  where 
the  oxidation  of  the  metal  is  an  inconvenience,  (as  in  steam-boilers,  &c.,)  it  may  be  remedied  to  a con- 
siderable extent  by  the  introduction  of  other  metals  having  a greater  affinity  for  oxygen.  Pieces  oi 
zinc,  for  instance,  will  serve  the  purpose  very  well,  to  keep  the  boiler  clean  and  unimpaired.  Impure 
water  acts  in  proportion  to  the  activity  of  the  salts  it  may  happen  to  hold  in  solution,  and  differently 
upon  different  conditions  of  the  metal.  Thus,  sea-water,  which  merely  gives  a coat  of  oxide  to  bar-iron 


IRON. 


(anchors,  chain-cables,  (fee.)  to  a depth  proportionate,  but  in  a diminishing  ratio,  to  the  time  of  immer 
sion,  converts  cast-iron  (cannon,  cannon-balls,  (fee.)  into  a substance  resembling  plumbago,  or  graphite, 
i.  e.  into  carbon,  associated  with  metallic  and  oxygenated  iron.  Such  conversion  appears  to  be  less  with 
white  than  gray  iron. 

Air  and  moisture  together  appear  to  exercise  a more  powerful  agency  in  producing  oxidation  than 
either  separately,  and  as  this  is  precisely  the  joint  influence  to  which  this  metal  is  in  most  practical 
cases  exposed,  there  is  the  more  interest  in  providing  a preservative.  This  is  found  not  only,  as  was 
said  just  now,  in  the  polish  of  the  surface,  but  also  in  the  means  by  which  such  polish  is  produced,  in 
special  coatings  of  substances  which  resist  humidity,  and  also  in  the  protecting  action  of  incipient  oxida- 
tion itself.  Thus,  in  the  first  instance,  a polish  acquired  under  the  use  of  oils  (and  still  more  as  those 
oils  may  be  themselves  unalterable)  is  more  lasting  than  one  obtained  with  water.  One  of  the  best 
preservatives  of  the  second  kind,  is  a solution  of  caoutchouc  in  oil  of  turpentine,  which  is  applied  upon 
the  polished  surface,  and  is  then  removed,  or  rather  brought  down  to  extreme  thinness,  by  a brush 
dipped  in  the  same  oil,  heated.  Among  the  third  sort  has  been  already  mentioned  the  bluing,  which  is 
effected  by  a temperature  of  about  550°  F. ; and  bronzing,  as  it  is  called,  is  of  similar  result.  This  is 
done  by  washing  the  surface,  which  should  be  smooth,  with  acids,  and  mostly  hydrochloric  acid,  ex- 
posing it  for  a suitable  time  to  the  air,  until  it  becomes  thoroughly  covered  with  a uniform  coat  of  oxide, 
and  then  removing  that  rust  with  olive-oil  as  a menstruum,  until  the  surface  ceases  to  soil  white  linen. 
This  is  the  common  resort  for  gun-barrels.  Electric  gilding,  (see  Gilding,)  although  beginning  to  be 
extensively  used  in  the  bright  parts  of  machinery,  which  are  not  subject  to  friction,  does  not  come  prop- 
erly in  the  category  of  the  preservatives  we  have  been  considering. 

The  combination  of  carbon  with  iron  gives  rise,  in  fact,  to  the  different  conditions  of  this  metah  In 
white  iron  and  steel  it  is  chemically  combined  with  the  mass ; in  gray  iron  it  is  partly  combined  in  poly- 
carburets  dispersed  about  the  mass,  and  partly  free,  as  graphite,  (called,  by  the  workmen,  Jcish  ;)  in 
malleable  iron  it  does  not  exist  at  all,  or  only  in  insignificant  proportions.  Karsten  considers  5'3  per 
cent,  as  the  limit  of  saturation,  which  would  give  for  the  atomic  constitution  of  the  percarburet,  one  atom 
of  carbon  to  four  atoms  of  iron.  In  gray  iron  the  whole  quantity  of  carbon  does  not,  at  a maximum, 
exceed  4 per  cent.,  of  which  1 per  cent,  may  be  taken  as  combined,  and  3 per  cent,  to  be  mechanically 
associated  as  graphite.  Although  the  occurrence  of  carbon  is  the  principal  modifier  of  the  condition  of 
this  metal,  it  is  probable  that  the  differences,  so  far  as  crude  iron  is  concerned,  are  owing  to  other  asso- 
ciations also.  Thus,  as  nitrogen  has  been  found  only  in  white  iron,  it  is  likely  that  some  of  its  charac- 
teristics depend  upon  the  formation  of  compounds  of  nitrogen  and  carbon,  and,  ultimately,  of  cyanurets 
of  iron.  It  is  very  much  to  be  desired  that  this  suggestion  could  be  studied  in  the  synthetic  way.  The 
practical  precautions  which  have  to  be  taken  in  consequence  of  the  affinity  of  iron  for  carbon,  will  be 
referred  to  hereafter,  under  the  head  of  Foundry,  and  also  under  the  article  Steel. 

Sulphur  combines  with  iron  in  several  definite  proportions,  both  artificially  and  in  nature.  Until  the 
proportion  reaches  2 atoms  of  sulphur  for  1 atom  of  iron,  (or  53  per  cent,  sulphur  nearly,)  the  compound 
is  attracted  by  the  magnet.  This  proportion  may  be  considered  as  that  of  the  natural  magnetic  pyrites. 
Four  atoms  of  sulphur  to  one  of  iron  constitutes  the  common  iron  pyrites.  Sulphur  promotes  the  fusi- 
bility  of  iron  extremely,  so  much  so  that  a plate  or  bar  of  iron,  kept  only  at  a red  heat,  may  be  pierced 
to  a considerable  depth  (say  an  inch,  or  more)  by  a stick  of  sulphur.  Unfortunately,  the  quality  of  the 
metal  becomes  so  far  impaired  as  not  to  allow  avail  of  this  peculiarity  in  the  arts.  Sulphur  combined 
with  iron  causes  brittleness  at  all  temperatures,  and  especially  what  has  been  before  spoken  of  as  red- 
shortness.  Experiment  has  shown  that  of  sulphur  is  enough  to  produce  the  first  characteristic, 
and  — ^ A__  the  second.  It  is  hence  that  many  ores  cannot  be  advantageously  (and  some  not  at  all) 
applied  in  the  reduction  of  this  metal.  Where  the  proportion  of  sulphur  is  minute,  it  may  be  partly 
volatilized  by  previous  roasting,  and  partly  taken  up  by  excess  of  lime  in  the  flux.  By  this  last  appli- 
cation, the  sulphur  in  the  coke  of  some  of  the  English  furnaces  is  gotten  rid  of.  The  remarkable  action 
of  sulphur  upon  iron-filings,  when  made  with  water  into  a paste,  (which,  after  a while,  develops 
intense  heat,  and  finally  bursts  forth  in  spontaneous  flame,)  belongs  more  properly  to  the  formation  o! 
sulphuric  acid,  but  may  be  mentioned,  once  for  all,  here.  The  influence  of  compounds  of  sulphur  and 
carbon  together  has  not  yet  been  satisfactorily  studied. 

As  sulphur  gives  the  property  of  red-shortness,  so  phosphorus  seems  to  impart  that  of  cold-shortness, 
or  brittleness  at  low  temperatures,  but  not  to  an  equally  prejudicial  extent.  There  is  hardly  any  iron 
in  which  a trace  of  this  substance  cannot  be  found.  With  bar-iron  occurring  in  proportions  as  high  as 
\ per  cent.,  it  only  hardens  the  metal  without  diminishing  tenacity ; at  J per  cent,  the  tenacity  is 
seriously  diminished ; and  over  1 per  cent,  makes  the  iron  of  very  bad  quality  and  very  limited  use. 
Phosphorus  lessens  the  capacity  for  heat  of  the  metal,  and  increases  the  facility  with  which  bar-iron 
can  be  welded.  Crude  iron  it  makes  more  fusible  and  retains  longer  melted,  so  that  in  minute  propor- 
tions it  is  rather  an  advantage  for  castings.  Phosphorus  appears  capable  of  uniting  with  iron  in  all 
proportions,  but  at  a high  temperature  there  is  but  one  definite  compound,  consisting  of  2 atoms  of  iron 
and  1 of  phosphorus,  or  iron  0176  -f-  phosph.  0 224.  The  natural  kingdom  does  not  afford  any  pliosphu- 
ret  of  iron,  but  phosphates  are  widely  extended  and  numerous.  Phosphorus  is  supposed  to  behave  with 
carburets  of  iron  in  a similar  manner  with  sulphur,  but,  like  this  last,  has  not  in  this  respect  been  studied. 

The  effect  of  acids,  of  whatever  kind,  upon  iron,  appears  to  depend  upon  the  presence  and  decompo- 
sition of  water ; and  hence,  in  an  anhydrous  or  concentrated  state,  their  action  is  uniformly  more  feeble 
than  when  dilute.  The  presence  of  carbon,  too,  and  its  state  of  combination,  also  affect,  and  in  their 
proportion  weaken,  the  influence  of  the  acid.  Thus  steel  is  distinguishable  from  iron  by  the  ease  with 
which  it  is  attacked  and  stained  by  nitric  acid,  and  white  iron  is  more  affected  in  this  manner  than  steeL 
Hard  iron,  in  all  conditions,  is  less  easily  attacked  than  soft ; and  upon  this,  as  well  as  the  state  ol 
combined  carbon,  rests  the  art  of  damascening,  or  watering  the  surface  of  iron  and  steel. 

Acetic  acid  acts  readily  upon  iron  and  upon  its  peroxide,  but  slowly  upon  the  protoxide.  The  acetate 
of  iron  thus  produced  is  used  extensively  in  calico-printing,  under  the  name  of  iron  liquor. 


IRON. 


79 


Carbonic  acid,  without  the  presence  of  water,  does  not  act  at  all  on  iron  or  its  oxides,  artificially, 
though  carbonates  of  iron  form  a very  extensive  and  important  class  of  minerals.  The  different  sorts  of 
coloring-matter  known  as  Prussian-blue,  are  carbo-azotic  compounds,  or  hydrocyanates  of  iron,  whose 
practical  use  is  better  understood  than  their  theoretical  composition.  (See  Prussian  Blue.) 

Gallic  acid,  which  is  a compound  of  oxygen,  hydrogen,  and  carbon,  acts  very  feebly  upon  iron  and  its 
protoxide,  or,  perhaps  it  may  be  said,  not  at  all ; but  upon  the  peroxide  it  acts  energetically,  striking 
a deep,  black,  and  permanent  color,  and  constitutes,  in  fact,  the  basis  of  all  ordinary  black  inks. 

Hydrochloric  acid  acts  with  great  readiness  upon  iron  and  its  oxides.  For  all  applications  in  the  arts 
where  the  object  is  to  produce  or  remove  oxidation,  it  is  undoubtedly  the  best,  though  not  the  most 
economical  agent.  Upon  crude  iron  it  is  best  to  be  employed  concentrated. 

Nitric  acid,  highly  concentrated,  has  but  a feeble  action  upon  iron  ; at  its  average  concentration  it 
acts  with  great  energy.  On  account  of  its  peculiar  behavior  towards  carburets  of  iron,  it  generally 
enters  as  an  ingredient  in  etching-liquors.  Thus,  for  making  damascene  designs  upon  cutlery,  Rinman 
recommends  a wash  composed,  by  weight,  of  4 nitric  acid  -f-  '2  sal-ammoniac  (hydrochlorate  of  amm.) 
-f-  1 sulphate  of  copper  -j-  72  water.  Where  the  etching  is  required  to  be  deep,  as,  for  instance,  in 
mosaic  damascening,  where  gold  is  to  be  inlaid,  the  nitric  acid  is  inconvenient,  in  depositing  a salt  diffi- 
cult to  be  cleaned  out. 

Phosphoric  acid  attacks  iron  with  great  avidity,  but  not  its  oxides  at  ordinary  temperatures.  The 
artificial  phosphates  thus  produced  are  without  interest  to  the  arts  as  yet ; the  natural  ones  form  an 
extended  mineral  class. 

Dilute  sulphuric  acid,  as  well  as  sulphurous  acid,  act  upon  iron  at  ordinary  temperatures,  and  with 
energy  as  the  temperature,  and  to  a certain  extent  the  dilution,  increase,  forming,  ultimately,  sulphates 
of  iron.  They  also  combine  with  the  oxides  of  iron  in  various  proportions.  The  crystallized  sulphate 
of  the  protoxide  is  known  in  commerce  as  green  vitriol,  or  copperas.  WThen  this  is  heated  in  close  ves- 
sels it  parts  with  its  water  of  crystallization,  and  upon  continuance  of  the  heat,  after  divers  changes  and 
disengagements,  becomes  converted  into  pure  peroxide  of  iron,  which  is  the  colcothar  of  commerce,  or 
the  crocus  martis  of  the  old  druggists,  and  the  plate-powder  or  ronge  of  the  silversmiths  and  polishers 
of  steel  and  speculum-metal. 

Solutions  of  the  alkalies  or  alkaline  earths  do  not  appear  to  act  upon  iron  or  its  oxides.  On  the  con- 
trary, their  presence  seems  rather  to  retard  the  decomposition  of  water.  At  a red  heat  iron  will  take 
up  about  10  per  cent,  of  ammoniacal  gas,  becoming  white  and  extremely  brittle,  but  less  liable  to  alter- 
ation from  air  or  moisture.  At  the  same  temperature,  potassa  and  soda  are  deoxidized  by  malleable 
iron ; if  crude  iron  be  fused  with  these  alkalies,  it  parts  progressively  with  all  its  carbon,  and  becomes 
bar-iron.  It  has  been  generally  supposed  that  the  metallic  bases  of  the  alkalies  do  not  combine  with 
iron,  or  rather,  are  sublimed  at  the  temperature  required  for  such  alloy.  But  more  recent  observations 
disaffirm  this  supposition.  Potassium  and  sodium,  for  instance,  can  be  combined  synthetically  with 
iron,  and  magnesium  and  calcium  are  often  found,  though  in  minute  proportions,  in  the  crude  iron  of 
commerce.  How  far  they  influence  the  character  and  quality  of  this  metal  is  yet  obscure.  Karsten 
observes  that  of  potassium  causes  the  alloy  to  be  hard,  and  to  be  welded  with  difficulty,  while 
r_>__  of  calcium  is  enough  to  impair  materially  the  qualities  of  iron.  Magnesium  appears  to  be  got  rid 
of  entirely  in  the  processes  of  refining  and  puddling.  Barium  no  otherwise  affects  the  metal  than  by 
embarrassing  the  operations  of  the  liigh-furnace,  when  present  with  the  minerals  there  as  sulphate  of 
baryta. 

The  earths,  so  called,  : which  need  only  be  mentioned  silica  and  alumina,)  exercise,  at  ordinary 
temperatures,  or  even  at  any  temperature  below  fusion,  no  appreciable  chemical  action  upon  iron. 
Associated  with  carbon,  at  this  last  temperature,  they  are  reduced  to  their  metallic  bases,  (either  by  the 
iron  or  by  'the  carbon,)  which  enter  into  combination  with  the  iron,  and  modify  it  more  or  less.  Sili- 
cium  is  found  more  abundantly  in  gray  iron  than  in  white ; its  maximum,  as  yet  observed,  may  be 
stated  at  4£  per  cent.,  including  that  which  is  found  free  in  the  condition  of  silica  in  the  cavities  of  crude 
iron.  Its  average  hardly  exceeds  1 per  cent.  There  is  no  reason  to  suppose  that  this  proportion  affects 
the  quality  of  the  metal ; on  the  contrary,  it  may  be  assumed  not  to  interfere  with,  if  it  does  not  pro- 
mote the  fusibility  and  fitness  for  castings.  The  opinion  among  practical  iron-workers  (which  is  not, 
however,  partaken  of  by  chemists  generally)  is,  that  a certain  small  proportion  of  silicium  augments 
tenacity.  The  operation  of  refining  generally  drives  off  9-10ths  of  the  silicium  contained  in  the  crude 
metal ; but  a proportion  is  often  restored  in  subsequent  processes,  of  which  it  would  be  well  for  man- 
ufacturers to  take  account,  in  view  of  a particular  quality  that  may  be  desired.  Thus  Boussingault 
found  bar-iron,  melted  in  a Hessian  crucible,  to  have  taken  up  more  than  J,-  per  cent,  of  silicium.  Syn- 
thetic experiments  in  the  small  way  warrant  the  belief  that  a smaller  proportion  than  this  hardens  iron 
and  makes  it  less  tenacious.  Karsten  presumes  the  action  in  this  last  respect  of  silicium  to  be  more 
injurious  than  that  of  phosphorus.  Whether,  as  has  been  supposed,  the  conversion  into  steel  is  due  to 
silicious  as  well  as  to  carbonized  combinations,  is  not  yet  understood.  No  higher  than  a trace  of  alumi- 
num has  been  observed  either  in  crude  or  in  malleable  iron.  Such  traces  are  more  distinctly  marked 
in  gray  than  in  white  iron,  and  most  distinct  in  cold-short  iron.  There  can  be  no  doubt  that  this  base 
injures  the  tenacity  of  the  metal.  Stodart  and  Faraday’s  experiments  upon  the  manufacture  of  icootz, 
or  Indian  steel,  (in  which  § per  cent,  of  aluminum  has  been  found,  and  which  is  considered  to  owe  its 
peculiar  properties  to  the  association,)  will  be  spoken  of  under  the  article  Steel. 

Iron  forms  an  alloy  with  most  of  the  other  metals  in  varying  proportions,  dependent  chiefly  upon 
temperature.  With  antimony  it  has  a great  affinity,  and  associated  with  \ per  cent,  of  this  last,  it  be' 
comes  very  brittle,  either  cold  or  hot.  When  united  in  the  proportion  of  single  atoms,  (when  the 
antimony  is  70  per  cent,  of  the  mass,)  the  elements  are  inseparable  by  the  highest  degree  of  heat. 

Arsenic  in  the  proportion  of  lA  per  cent,  has  been  observed  to  destroy  entirely  the  tenacity  of  iron 
On  account  of  the  extreme  volatility  of  this  metal,  it  is  difficult  to  effect  directly  so  high  a combination 
There  is  no  doubt  that  a very  much  smaller  proportion  acts  injuriously. 


80 


IRON. 


Bismuth  does  not  readily  form  an  intimate  union  with  iron.  At  the  temperature  of  fusion  of  this  last 
a great  part  of  the  former  is  volatilized,  and  its  effect  seems  more  felt  in  the  treatment  than  in  the 
quality  produced  ; of  bismuth  do  not  affect  the  strength  or  malleability  of  the  metal. 

Chrome  unites  with  iron  in  all  proportions,  making  alloys  very  hard,  brittle,  crystalline ; more  brilliant 
than  iron,  less  fusible,  much  less  magnetic,  and  much  less  oxidable.  And  these  characters  are  more 
marked  as  the  proportion  of  chrome  increases.  An  alloy  containing  60  per  cent,  of  chrome  is  very 
fragile,  whiter  than  platinum,  and  so  hard  that  it  scratches  glass  as  deeply  as  a diamond.  On  the  other 
hand,  from  1 to  2 per  cent,  of  chrome  hardens  cast-steel,  and  gives  it  the  property  of  damascening 
beautifully,  without  diminishing  its  malleability. 

Cobalt  unites  with  iron  in  all  proportions  and  without  altering  its  properties,  at  least  until  the  quantity 
of  the  former  becomes  considerable. 

Copper  can  hardly  be  said  to  make  a true  alloy  with  iron,  though  when  fused  together  a small  pro- 
portion of  the  former  will  be  taken  up  and  retained  upon  subsequent  fusion.  Of  crude  iron  it  increases 
the  tenacity  when  in  the  proportion  of  1 or  2 per  cent.,  and  it  might,  therefore,  be  advantageously  and 
economically  employed  for  certain  castings.  As  much  as  \ per  cent,  in  bar-iron  injures  its  capacity  for 
being  welded ; a larger  proportion  makes  a metal  brittle  at  a red  heat. 

Gold  may  be  alloyed  in  all  proportions  with  iron,  for  which  it  has  a remarkable  affinity,  and  to  which 
it  imparts  no  new  quality  until  its  own  quantity  becomes  considerable.  When  the  gold  is  from  20  to 
25  per  cent,  of  the  mass,  the  alloy  is  silvery  and  very  hard,  so  much  so  that  cutting  tools  may  be  made 
of  it.  On  the  other  hand,  when  the  iron  is  from  15  to  20  per  cent,  (to  be  classed  more  properly  as  an 
alloy  of  gold)  it  makes  what  the  jewellers  know  as  gray  gold , of  late  much  used  for  little  trinkets,  and 
admired  for  the  beautiful  polish  that  can  be  given  it.  Gold  is  also  used  as  a solder  for  delicate 
steel-work. 

Lead  does  not  form  an  alloy  with  iron  directly,  with  crude  iron  not  at  all,  and  with  bar-iron,  treated 
with  litharge,  in  proportion  not  exceeding  2 per  cent.  This  (and  even  a smaller  proportion)  renders  the 
mass  more  brittle  and  more  fusible.  The  ores  of  lead,  which  are  sometimes  found  associated  with  those 
of  iron,  and  have  to  be  treated  together  in  the  high-fumace,  are  reduced,  but  the  metallic  lead  lies  in  the 
hearth  without  uniting  with  the  iron.  It  is  sometimes  found  there  when  a furnace  is  blown  out,  not  only 
in  this  state,  but  also  as  red-oxide  or  minium , and  as  a crystallized  silicate. 

Manganese,  on  the  contrary,  has  a remarkable  affinity  for  iron,  and  of  all  the  metals  is  found  most 
frequently  in  association  with  it.  In  small  proportions  the  manganese  renders  the  alloy  harder,  without 
impairing  its  tenacity ; the  limit  in  this  respect  is  not  ascertained,  but  it  may  be  safely  assumed  at  1 J 
per  cent.  The  addition  of  manganese  diminishes  the  fusibility  of  iron,  but  increases  its  oxidability. 
Alloys  of  these  metals  almost  always  exhale  an  odor  of  hydrogen  upon  being  breathed  on,  and  this 
greed  of  manganese  for  oxygen  is  one  of  the  means  by  which  the  crude  iron  from  manganesian  iron-ores 
may  be  refined,  so  as  to  part  with  nearly  or  quite  all  of  its  alloy.  The  tendency  of  such  manganesian 
ores  to  yield  a metal  easdy  convertible  into  steel  has  caused  them  to  acquire  the  name  of  steel-ores  with 
some  persons.  But  this  tendency,  as  well  as  the  uniform  liability  of  such  ores  (unless  treated  suitably) 
to  give  a white  iron  in  the  high-furnace,  does  not  appear  to  arise  directly  from  the  manganese,  but  indi- 
rectly only,  from  the  influence  which  this  last  has  upon  the  behavior  of  carbon. 

Molybdenum,  like  tungsten,  unites  with  iron  in  moderate  proportions,  without  altering  its  qualities, 
further  than  augmenting  its  hardness.  An  alloy  of  l-5th  molybdenum  in  iron  is  fusible,  extremely  hard, 
with  small  resistance  to  impact,  but  tenacious  in  other  respects. 

Nickel  behaves  with  iron  very  much  like  cobalt,  especially  in  the  white  color  it  gives,  and  in  the 
facility  and  variety  of  its  combinations.  An  alloy  of  1 atom  of  nickel  to  12  atoms  of  iron,  (which  cor- 
responds to  about  8 J per  cent,  of  the  former,)  is  one  often  met  with  in  nature,  under  the  name  of  meteoric 
iron.  This  is  less  oxidable  and  less  ductile  than  iron  unalloyed,  but  in  other  respects  the  metal  is  of 
good  quality.  Not  to  speak  of  the  sword  of  Alexander,  which  is  said  to  have  been  made  of  an  alloy 
like  this,  nor  of  the  sabres  of  Jehanguire,  fabricated  of  a similar  metal  some  2000  years  later,  the  sword 
presented  to  Bolivar  in  1821  was  forged  of  the  meteoric  iron  of  Santa  Rosa,  near  Santa  Fe  de  Bogota, 
whose  atomic  constitution  is  almost  precisely  what  has  been  given  above. 

Palladium  renders  iron  brittle  when  in  even  moderate  proportions  ; when  the  proportion  is  small,  it 
induces  no  further  alteration  than  increased  hardness.  The  same  affinities  and  effects  belong  to  alloys 
with  rhodium,  iridium,  and  osmium.  A proportion  of  3 per  cent,  of  either  of  these  in  bar-iron  prevents 
rusting,  and  renders  the  alloy  capable  of  being  tempered  like  steel.  It  is  with  steel,  however,  that  the 
alloys  of  all  these  metals  are  the  most  remarkable.  The  same  may  be  said,  too,  of  platinum,  whose 
alloys  with  steel  are  of  great  interest,  and  present  some  remarkable  peculiarities,  but  which  hardly 
unites  directly  with  iron,  except  in  the  presence  of  carbon. 

Silver  does  not  form  a real  alloy  with  iron.  Fused  together,  the  iron  will  take  up  a small  proportion 
of  the  other  ; which,  when  it  is  as  low  as  only,  injures  the  malleability  and  weldability  of  the 

mass.  In  these  effects,  Karsten  ranks  it  as  very  nearly  equivalent  to  sulphur. 

Tantalium  does  not  unite  with  iron  directly;  except  at  a very  high  temperature,  and  in  the  presence 
of  carbon.  So  formed,  it  is  tenacious,  without  ductility,  and  readily  scratches  glass. 

Tin  and  iron  have  a great  affinity  for  each  other ; unite  in  all  proportions,  and  at  last  so  permanently 
as  not  to  be  separated  by  fusion.  The  alloys  in  which  tin  predominates  are  without  the  peculiar  char- 
acters of  this  metal,  while  they  have  gained  none  of  the  properties  of  iron ; and  the  same  may  be  said 
when  the  proportions  are  reversed.  This  does  not  apply  at  all  to  that  superficial  alloy  which  takes 
place  in  what  is  known  as  the  tinning  of  iron,  and  which  is  manifested  both  with  crude  and  malleable 
iron.  The  particulars  of  this  art  will  be  given  under  the  article  Tin-ware. 

The  alloy  of  titanium  will  be  spoken  of  in  connection  with  the  so-called  titaniated  iron-ores. 

Tungsten  behaves  like  molybdenum ; and  its  principal  effect  is  to  increase  the  hardness  of  the  alloy. 
Even  when  the  tungsten  is  37  per  cent,  (which  is  equivalent  to  1 atom  of  tungsten  to  6 of  iron,)  the 
physical  characters  of  the  alloy  are  very  much  those  of  white  iron. 


IRON. 


81 


When  zinc  is  kept  in  fusion  in  iron  vessels,  it  gradually  corrodes  and  dissolves  them ; a proof  of  the 
capacity  of  these  metals  to  form  alloys.  At  the  high  temperature,  however,  required  for  the  fusion  of 
iron,  the  zinc  is  volatilized ; and  so  is  never  found,  even  in  trace,  in  the  metal  from  high-furnaces  where 
iron-ores  containing  zinc  are  used.  It  is  the  opposite  when  the  ores  used  for  the  extraction  of  zinc  con- 
tain iron ; this  last  is  very  hard  to  be  gotten  rid  of,  and  even  in  small  proportions  injures  the  mallea- 
bility and  embarrasses  the  lamination  of  zinc.  There  is  also  a superficial  alloy,  like  that  mentioned  just 
now  in  the  case  of  tin , which  is  produced  when  clean  sheets  of  iron  are  plunged  in  a bath  of  melted 
zinc.  The  preparation  of  this  zincked  iron,  known  in  commerce  as  galvanized  iron , is  a late  application 
of  art,  which  will  be  particularly  described  under  Zinc. 

Iron  is  one  of  the  few  metals  which  do  not  form  an  amalgam  with  mercury  directly.  It  is  possible 
by  the  medium  of  a third  metal,  as  zinc  or  tin,  to  produce  indirectly  amalgams  which  are  of  no  interest 
in  the  arts. 

Mineral  characters  and  geological  occurrence  of  productive  ores  of  iron. — 1.  Native  iron,  bolide, 
meteoric  iron,  d'c. — Although  these  are  not  strictly  ores  of  iron,  yet,  as  they  are  both  workable  and  pro- 
ductive when  they  occur,  it  is  proper  to  include  them  here.  The  means  of  distinguishing  with  certainty 
those  which  are  terrene  from  those  which  are  formed  in,  or  at  least  fall  from,  the  atmosphere,  are  yet 
so  vague,  that  the  two  classes  are  here  counted  together.  The  occurrence  of  nickel  is  generally  held  to 
mark  a meteoric  origin.  The  most  remarkable  specimens  are  those  of  Siberia,  discovered  by  Pallas  ; 
of  Louisiana,  sent  to  New  York  by  Gibbs;  and  of  Buenos  Ayres,  found  by  Rubin  de  Celis.  This  last 
more  than  doubles  the  size  of  any  of  the  others ; weighing  about  fifteen  tons.  Besides  these,  Africa, 
near  the  Cape  of  Good  Hope  ; North  America,  at  Canaan  in  Connecticut,  and  Randolph  County,  North 
Carolina,  and  in  Bedford  County,  Pennsylvania ; South  America,  along  the  eastern  cordillera  of  the 
Andes,  and  in  Brazil,  and  Peru;  Asia,  in  Hindostan;  Europe,  from  Bohemia,  Croatia,  France,  Italy, 
Saxony,  and  Switzerland ; and  the  Esquimaux  settlements  near  Davis’  Straits,  (which  belbng  to  no  con- 
tinent,) have  all  contributed  specimens.  The  color  of  these  varies  from  silvery  to  bluish  white ; their 
hardness  may  be  taken  at  between  4 and  4'5  of  Kirwan’s  scale  ; they  are  all  magnetic.  Their  specific 
gravity  varies  from  5'95  to  P34-,  according  to  the  associations,  which  are  principally,  and  sometimes 
wholly,  nickel,  apparently  in  definite  proportions.  Arsenic,  chrome,  cobalt,  copper,  and  molybdenum 
have  also  been  found  united  with  the  iron,  as  well  as  a small  proportion  of  carbon  in  the  shape  of 
graphite. 

2.  Magnetic  iron-ore,  octahedral  iron-ore,  fer  oxidule,  black  oxide  of  iron,  loadstone,  dec. — This  is  the 
only  ore  of  iron  acted  on  by  the  magnet  without  application  of  heat,  except  the  titaniferous  iron  grains 
of  Brazil.  Its  geological  occurrence  is  in  primary  formations ; and  it  is  apt  to  be  accompanied  with 
quartz,  horublend,  calcareous  and  fluor  spars,  and  asbestos,  which  modify  variously  its  fusibility  and 
workable  properties.  Its  chief  deposits  are  in  Sweden  and  Norway,  and  in  Siberia,  where  it  occurs  in 
bands;  sometimes  it  is  found  in  beds,  as  in  Savoy  and  Piedmont,  Tyrol  and  the  Vosges;  it  forms  the 
mass  of  considerable  mountains,  as  at  Taberg  in  Smoland ; and  is  also  worked,  as  in  Naples,  in  small 
grains  like  sand.  In  the  New  World  it  is  found  also,  as  in  La  Plata,  Brazil,  Mexico,  and  the  United 
States  ; but  generally  not  in  sufficient  extent  to  work.  The  mines  at  Schooley’s  Mountain,  in  New  Jer- 
sey, have  been,  it  is  believed,  abandoned  ; and  the  new  works  for  this  ore  near  Sykesville,  in  Maryland, 
have  not  been  long  enough  in  operation  to  determine  their  reliability.  This  ore  frequently  occurs  in 
crystals,  whose  primary  form  is  the  regular  octahedron,  and  whose  cleavage  is  perfect.  Its  color  is 
black ; its  lustre  generally  metallic ; its  fracture  generally  conchoidal ; its  hardness  5'5  to  6’5 ; its  spe- 
cific gravity  5 at  a mean.  When  pure,  it  is  composed  of  1 atom  of  iron  and  1 J atoms  of  oxygen.  The 
metal  from  this  ore,  known  as  Swedish  iron,  is  of  the  best  quality  in  commerce : and  its  properties, 
although  attributed  sometimes  to  the  methods  of  its  treatment,  are  probably  more  owing  to  the 
materials. 

3.  Specular  oxide,  an  hydrous  peroxide  of  iron,  iron-glance,  red  hematite,  fer  oligiste,  eisenrahm,  dec. — 
This  mineral  is  generally  found  in  primary  formations,  but  occurs  also  among  sedimentary  rocks.  Va- 
rieties of  the  species,  apparently  of  daily  formation,  are  to  be  met  with  amid  the  lava  of  Vesuvius,  and 
in  ancient  and  existing  solfaterras,  as  of  Tolfa  and  Guadaloupe.  The  most  celebrated  deposit  of  it  is  in 
the  island  of  Elba,  where  it  has  been  worked  for  more  than  2000  years,  and  where  the  extent  of  the 
excavations  and  deblais  attests  the  industry  more  than  the  skill  of  the  ancient  miners.  The  Elba  mines 
are  continuations,  probably,  of  the  Tuscan  ores.  At  present  there  are  three  workings  in  a hill  of  about 
three  miles  in  extent,  and  elevated  only  about  600  feet  above  the  sea.  The  rock  in  which  it  occurs  is 
a whitish  talcose  slate,  called  there  bianclietta,  easily  worked,  but,  after  all,  not  very  productive  in 
modern  times;  the  whole  quantity  exported  not  long  since,  being  not  more  than  15,000  tons.  The  ore 
here  is  often  slightly  magnetic,  and  contains,  in  fact,  an  admixture  of  magnetic  oxide,  and  often  titanium. 
The  wash  from  the  actual  workings,  presenting  the  ore  in  the  shape  of  octahedral  grains  like  sand,  is 
also  exported  under  the  name  of  poulette.  The  same  granular  occurrence  is  met  with  at  Framont  in 
the  Vosges,  the  only  point  at  present  in  France  furnishing  specular  oxide.  There  are  some  other  strik- 
ing localities,  such  as  Gellwara  in  Lapland,  and  Sommorostro  in  Biscay,  (where  it  forms  the  mass 
of  large  mountains,)  Norberg  in  Denmark,  and  the  Minas  Gerues  in  Brazil,  where  it  exists  in  very  ex- 
tensive beds.  The  crystals  of  this  ore  are  varied  ; but  the  primary  form  appears  to  be  a rhomboliedron 
nearly  cubic.  Its  color  is  a brilliant  black,  very  often  iridescent,  with  a metallic  lustre.  Its  fracture  is 
sometimes  lamellar,  but  more  generally  irregular.  Thin  laminae  show  a deep  blood-red  color.  Hard- 
Dess,  from  5-5  to  6’5  ; magnetism,  when  it  exists,  attributable  to  admixture  of  magnetic  oxide ; and 
specific  gravity  at  a mean,  5-10.  When  pure,  it  is  entirely  a peroxide  of  iron,  and  consists  of  1 atom  of 
iron  with  14  of  oxygen.  The  metal  from  this  ore  may  be  taken  as  equal  to  that  from  the  former  class  ; 
the  Celtiberian  iron  of  old  time,  and  the  Bilboa  blades  of  more  recent  periods,  were  made  w7ith  it;  and 
in  Sweden  even,  in  many  mines,  it  is  not  separated  from  the  magnetic  ore.  The  micaceous  variety 
crystallizes  in  hexagonal  tables,  which  are  divisible  into  thin  translucent  plates.  Its  powder  is  a bright 
red-  its  specific  gravity  about  5'25.  This  is  found  of  extreme  beauty  near  Northampton  in  Massachu 


IRON. 


85S 


setts.  Red  hematite  occurs  massive,  stalactitic  or  fibrous,  and  mamelonated.  Its  color  is  a dark  red, 
with  very  often  a metallic  lustre  and  aspect.  Hardness,  about  7 ; powder,  which  is  red,  never  mag- 
netic; and  specific  gravity,  at  a mean,  5.  Thomson  gives  the  specific  gravity  of  a specimen  from 
Muirkirk  at  6p305.  It  is  often  mixed  with  oxide  of  manganese,  and  is  then  a reddish-brown,  almost 
black.  Of  this  variety  are  the  deposits  in  Cumberland,  (Eng.,)  so  useful  in  admixture  with  the  ores  ol 
Wales;  and  in  this  also  is  the  principal  mining  about  Lauterberg  and  Altenau  in  the  Hartz.  This  is 
the  bloodstone  of  the  metal-polishers.  The  compact  red  iron-ore  of  Lavoulte,  in  France,  occurs  roassi’-e, 
in  veins  50  to  60  feet  thick.  It  is  also  sometimes  found  in  pseudo-morphous  cubic  crystals-.  Its  color 
is  a brownish-red ; its  fracture  uneven  ; its  specific  gravity  about  4’25.  Red  ochre,  which  is  chiefly  usul 
as  a pigment,  but  also  as  an  ore,  may  be  regarded  as  closely  allied  to  this  last  variety,  in  which  it  is 
principally  distinguishable  by  a softer  texture  and  more  lively  red  color. 

All  these  classes  of  ores,  when  pure,  contain  the  iron  associated  only  with  oxygen.  'The  others 
which  follow  contain  also  water  as  a permanent  additional  element,  in  the  proportion  of  from  10  to  15 
per  cent.  Such  are, 

4.  Hydrated  peroxide  of  iron,  fibrous  and  compact  brown  hematite,  brovm  ochre,  umber,  cetites,  limo- 
nite,  bog-iron  ore,  dec.,  dec. — This  class  is  very  extensive,  and  is  found  as  well  in  primary  formations  as 
in  newer  rocks.  Its  principal  deposits  are  in  the  oolite  series  and  chalk  equivalents.  Bog-ore  is  con- 
sidered of  daily  formation.  It  is  sometimes  found  in  octahedral  and  cubic  crystals,  but  most  generally 
massive.  The  color  of  the  mass  is  in  various  shades  of  brown,  but  its  powder  and  streak  always  yel- 
low. Its  hardness  is  from  4-5  to  5 ; its  specific  gravity,  at  a mean,  4.  It  does  not  act  on  the  magnet. 
Chemically,  it  is  composed  of  1 atom  of  water,  1 of  iron,  and  1 J of  oxygen ; or  otherwise,  1 atom  of 
pure  specular  oxide  with  1 atom  of  water.  From  this  class  (principally,  the  compact  brown  hematite) 
comes  a great  part  of  the  iron  of  France ; the  deposits  about  Whitehaven  in  England,  which  are  of 
enormous  extent,  are  a variety  (the  reniform)  of  it ; the  oolitic  ores,  which  are  small  globules  held  to- 
gether by  a calcareous  or  argillaceous  cement,  cover  a considerable  extent  in  Burgundy  and  Lorraine, 
and  occur  also  in  Carinthia  and  Styria;  the  granular  hydrates,  or  ferriferous  sand,  are  worked  in  Nor- 
mandy and  other  parts  of  France,  in  Switzerland,  in  Silesia,  Bavaria,  and  Poland  ; and,  finally,  the  bog- 
ores  are  profitably  mixed  with  other  ores  in  many  places,  as  in  Silesia  and  Livonia,  and  in  the  coal 
region  of  Maryland,  or  worked  alone  as  in  the  last-named  state.  Phosphate  of  iron,  however,  which 
occurs  frequently  in  this  alluvial  variety,  prejudices  its  unmixed  use.  Brown  ochre  is  principally  used 
as  a pigment ; and  the  cetites,  or  eagle  stones  as  they  are  called,  which  occur  along  the  Rhine,  are  almost 
as  much  used  by  the  French  shepherds  as  amulets,  to  be  hung  around  the  neck  of  a favorite  ram,  as 
for  any  other  purpose.  The  metal  from  this  variety,  however,  as  well  as  from  fhe  whole  class,  is  unex- 
ceptionable whenever  (as  is  the  case  generally,  except  with  the  bog-ores,)  there  is  no  adventitious  im- 
purities or  associations,  in  sufficient  proportion  to  be  injurious.  Ordinarily,  the  associations  are  from 
three  to  ten  per  cent,  of  silica,  alumina,  and  manganese,  in  nearly  equal  quantities  ; amounts  which  in 
nowise  embarrass  the  smelting  or  the  result. 

5.  Carbonate  of  iron,  brown  spar,  argillaceous  iron-ore,  spathose  or  sparry  iron,  spherosiderite,  fir 
spathique,  fer  carbonate  lithoide,  stahlstein,  dec. — Under  these  synonyms  and  varieties  may  be  included 
a class  more  widely  extended  and  more  productive  than  any  other  on  earth.  Two  principal  divisions 
may  be  made  of  it— the  crystalline  or  sparry,  and  the  compact  or  litho'id — the  former  occurring  in  beds 
and  pockets  in  the  primary  rocks,  the  latter  belonging  to  newer  formations,  and  especially  stratified 
among  the  coal-measures.  The  facility  with  which  the  former  can  be  reduced  rendered  it  of  abundant 
introduction  into  the  smelting-houses  of  the  ancients ; it  was  from  this  ore  that  the  Styrian  works  turned 
out  the  metal  so  favorably  known  before  our  era  as  the  Norican  non ; and  the  name  of  steel-ore,  under 
which  it  has  been  designated,  from  the  readiness  with  which  it  yields  a steel  at  the  first  treatment,  is 
not  less  a test  of  its  appreciation.  This  variety  is  both  massive  and  crystallized.  In  the  latter  case,  its 
primary  form  is  an  obtuse  rhombofcedron,  nearly  approaching  the  form  of  calcareous  spar.  Its  deriva- 
tives are  more  complex ; but  not  unfrequently  it  is  converted,  as  in  the  very  large  Cornish  crystals,  into 
regular  six-sided  prisms.  Its  color  is  gray  of  various  shades,  yellowish  and  greenish,  but  sometimes 
almost  red.  Fracture  is  imperfect  chonchoidal,  with  a vitreous  and  somewhat  pearly  lustre.  Thin 
fragments  are  often  translucent.  Its  average  hardness  is  about  4;  its  specific  gravity,  at  a mean,  375. 
It  is  not  magnetic.  Abstraction  made  of  the  impurities,  which  are  generally  carbonates  of  lime  and 
magnesia,  this  mineral  is  composed  of  1 atom  carbonic  acid  and  1 atom  protoxide  of  iron.  The  compact 
or  litho'id  variety  occurs  in  nodules  and  in  regular  veins  or  strata ; this  last  is  especially  the  case  in  the 
coal-meilsures,  with  which  it  is  always  more  or  less  associated.  Its  color  is  a dark  gray,  and  when  the 
allied  carbonaceous  matter  is  abundant,  almost  black.  Its  specific  gravity  is  from  3 to  3’5.  Its  com- 
position is  the  same  essentially  as  that  of  the  other  variety,  but  with  the  uniform  addition  of  notable 
proportions  of  silica  and  alumina,  and  coaly  matter  ; protoxide  of  manganese  is  very  often  found  with 
it  and  in  the  coal-measures,  sulphur  but  in  small  quantities.  The  value  of  this  ore  is  more  in  the  facility 
with  which  it  is  treated  than  the  quantity  or  quality  of  the  metal  produced.  When  in  an  unaltered 
state,  it  rarely  yields  more  than  33  per  cent,  of  metallic  iron;  the  altered  carbonates,  which  occur  most 
generally  in  accidental  beds  among  the  primary  rocks,  may  give  45  per  cent.  MuslieVs  black  band,  as 
it  is  termed,  a seam  of  high  reputation  near  Airdrie,  in  the  Glasgow  coal-field,  returns  about  41  per 
cent.  Even  when  made  with  charcoal,  the  iron  from  this  ore  is  inferior  in  its  physical  properties  to  the 
Swedish,  to  the  Spanish,  and  to  the  Styrian  iron,  and,  in  general,  to  the  metal  produced  from  any  of 
the  preceding  classes ; when  coke  or  coal  is  used  its  inferiority  is,  of  course,  more  strongly  marked. 
Yet  improvements  in  the  methods  of  manufacture  have  gradually  cured  these  natural  disadvantages  to 
an  extent  which,  though  it  still  leaves  something  to  desire,  is  yet  sufficient  for  most  practical  purposes, 
and  may  well  be  balanced  by  the  economy  of  production  and  the  cheapness  of  the  metal  furnished. 
Indeed,  without  the  use  of  coal  and  the  association  of  this  ore  with  the  beds  of  fuel  for  smelting  it,  some 
of  the  most  important  contributions  to  the  civilization  of  the  present  day  would  have  been  either  im- 
possible, or  at  least  unattempted.  From  this  last  variety  comes  now  nearly  the  whole  enormous  prod- 


IRON. 


S3 


net  in  iron  of  Great  Britain ; is  is  being  extensively  used  in  France,  where,  as  in  the  departments  o! 
the  Nord,  Loire,  and  Allier,  it  exists  in  abundance  ; it  returns  a part  of  the  metal  from  the  Hartz  ; it 
was  the  earliest  worked  of  the  iron-ores  of  America  along  the  Atlantic  coast,  when,  as  little  more  than 
a century  since,  it  was  seriously  looked  to  as  an  available  resource  for  the  supply  of  crude  iron  for  the 
English  market,  and,  worked  with  charcoal  at  many  points,  still  continues  to  yield  a profitable  return  ; 
and  finally,  when  foreign  competition  is,  for  an  interval  only,  set  aside  or  guarded  against,  will  enable 
the  bituminous  coal-fields  of  Maryland,  Pennsylvania,  Ohio,  and  Virginia  to  supply  the  entire  consump- 
tion in  iron  of  the  whole  American  continent. 

Such  are  the  principal  classes  of  available  ores  of  iron.  Mineralogists,  and  metallurgists  even,  often 
extend  their  number  to  include  others,  which  should  be,  in  theory,  and  sometimes  may  be  in  practice,  used 
to  advantage.  So  the  silicated  iron-ore  of  Kupferrath,  the  chamoisite  of  the  Valais,  the  garnets  of  Henne- 
berg,  the  titaniated  ore  of  Maryland,  are  actually  smelted  ; while  the  volcanic  basalt  of  France,  Ger- 
many, and  Ireland,  and  the  jasper  of  Piedmont  and  Siberia,  contain  iron  enough  to  render  its  extraction 
hopeful.  So  the  franklinite  of  New  Jersey,  which  contains  46  per  cent,  of  metallic  iron,  might  be  sup- 
posed as  proper  for  the  domain  of  the  iron-master ; but  in  fact,  it  has  only  been  employed,  hitherto,  (as 
twelve  years  ago  for  the  weights  and  measures  of  the  United  States,)  in  the  fabrication  of  brass,  and 
probably  will  ever  continue  to  be  invoked  solely  to  surrender  its  zinc.  As  for  the  other  mineral  combi- 
nations in  which  iron  is  found — the  arseniets,  chromates,  columbates,  phosphates,  and  sulphurets,  &c. — 
they  may  be  omitted  here.  Some  (as,  for  instance,  the  chromates ) are  worked  for  and  applied  to  pur- 
poses in  the  arts  other  than  the  reduction  of  the  iron  they  contain  ; others  (as,  for  instance,  the  phos- 
phates) yield  an  iron  of  such  inferior  quality,  when  treated  alone,  as  not  to  be  of  desirable  employment; 
while  others,  (as  the  sulphurets,  <fcc.,)  even  were  there  no  objection  on  this  last  score,  require  such  ex- 
pensive processes  to  effect  a separation,  as  to  be  quite  useless  as  ores  of  iron.  The  following  table  is 
of  interest,  as  showing  the  normal  proportion  of  metallic  iron  existing  in  the  types  of  the  classes  arid 
varieties  that  have  been  mentioned  : 


Class. 


Variety. 


Iron  per  100  parts. 


1.  Native  or  meteoric  iron 

2.  Magnetic  iron-ore 

S.  Specular  iron-ore 


4.  Brown  hematite 


5.  Carbonate  of  iron 


In  purity  

Mean  of  seven  analyses 

In  purity  

Red  hematite 

Compact  red  iron-ore  ... 

Red  ochre 

Compact 

Fibrous 

CEtites 

Oolitic 

Granular 

Brown  ochre 

Bog-iron  ore 

Sparry  

Lit.hoi'd  ; altered 


94- 

12-40 

67-47 

70- 

67-67 

56-50 

40-53 

59-18 

56-98 

54-97 

44-45 

42-21 

45'85 

29-54 

44-91 

40-79 

33-54 


Metallurgic  treatment  of  iron. — Under  this  head  belong  the  smelting  of  the  ores  to  produce  crude 
iron  ; the  founding  or  remelting  of  that  product  when  required  to  be  in  certain  forms  and  of  metal 
properly  termed  cast-iron ; the  refining  of  crude  or  cast-iron,  and  its  forging,  so  as  to  give  malleable  or 
6ar-iron  ; and,  finally,  the  operation,  by  hand,  upon  comparatively  small  masses  of  bar-iron,  known  as 
smith's  work.  For  the  first  of  these  processes  is  required  a furnace  ; for  the  second,  a foundry.;  for 
the  third,  a forge,  or  rolling-mill ; and  for  the  fourth,  a smithy.  Under  this  last  denomination  will  be 
included  as  well  the  manipulations — which,  from  the  color  of  the  work  turned  out,  (and  perhaps,  also, 
from  the  soiled  externals  of  the  workmen,)  are  ordinarily  termed  Mac/rsmithing — as  the  operations 
with  the  lathe,  die.,  which  are  demanded  in  what  is  technically  termed  a finishing- shop. 

1.  Smelting. — This  is,  both  in  theory  and  in  fact,  a chemical  operation  : depending,  first,  upon  the 
tendency  of  most  earthy  and  metallic  substances  to  melt  by  heat;  next,  upon  the  affinities  of  the  ma- 
terials usually  put  in  furnaces  for  new  combinations,  while  in  a state  of  fusion ; and  then,  upon  the 
excessive  gravity  of  metallic  iron,  which,  in  this  state,  tends  to  make  it  separate  from  and  sink  through 
the  melted  mass.  In  this  last  regard,  it  may  be  said,  that  while  the  specific  gravity  of  all  the  other 
solid  materials  likely  to  come  together  in  smelting  (even  in  a coal  or  coke  furnace)  is  not  much  more 
than  twice  that  of  water,  the  specific  gravity  of  metallic  iron  is  seven  times  as  great,  and  its  gravitating 
tendency  is,  therefore,  at  least  three  times  that  of  any  other  element.  In  charcoal  furnaces,  this  average 
tendency  downwards  is  still  greater.  The  following  paradigm,  in  which  only  the  chief  materials  and 
products  in  smelting  are  shown,  will  serve  t<  illustrate  the  character  of  the  affinities  that  are  exercised 
and  the  recompositions  that  result : 


IRON. 


MATERIALS. 


Gaseous Atmospheric  Air...  \ ^7"en  " 

1 ( JN  itrogen 


Solid 


'Iron  ore - 


Fuel. 


r Oxygen 

Carbon 

Iron  

Silica 

Alumina,  <irc.. 

'Oxygen  

Hydrogen 

Nitrogen  

Carbon........ 

Silica 

[ Alumina,  ifcc. . 

f Oxygen  

Carbon  

Alkaline  Flux 3 Lime  

I Silica 

(_  Alumina,  <fec. . 


Carbonic  Acid. 
Gaseous. 


Crude  Iron.  Furnace  Cinder. 
Solid.  Solid. 


The  success  of  these  results  depends  upon  the  means  employed.  Thus,  it  is  well  known  that,  with 
fuel  enough  and  air  enough,  heat  can  be  generated  sufficient,  both  in  intensity  and  abundance,  to  fuse 
the  most  refractory  and  voluminous  materials.  But  as  both  air  and  fuel  are  costly  in  their  supply,  the 
task  of  the  furnace-manager  is  so  to  admix  his  ores  and  fluxes  as  that  their  simultaneous  fusion  shall 
take  place  at  the  lowest  possible  temperature  ; that  it  shall  be  the  most  perfect,  to  allow  the  utmost 
chance  for  the  entire  separation  and  descent  of  the  melted  metal ; and  that  on  its  continuance,  and  by 
the  presence  of  substances  suitable  for  taking  up  and  neutralizing  all  accidental  or  necessary  impurities, 
either  in  the  ores,  fuel,  or  flux,  there  should  be  the  least  possible  opportunity  for  the  iron,  after  separa- 
tion, to  enter  into  new  and  detrimental  combinations.  All  this  was  expressed  long  ago,  with  great 
practical  terseness  and  almost  sufficiently  comprehensive  caution,  by  Rogur,  the  Welch  founder,  in 
saying  that  “ In  order  to  make  iron,  you  must  first  make  glass.”  It  is  to  produce  this  glassy  cinder 
out  of  all  the  solid  materials  in  the  furnace,  (except  the  irca,)  that  the  founder  aims  ; it  is  by  this  cin- 
der that,  from  hour  to  hour,  he  judges  how  his  furnace  wo-ks.  In  earlier  times,  and  with  many  still, 
this  task  was  matter  of  routine,  or  of  tact,  which  habits  of  observation  had  rendered  almost  intuitive. 
At  the  present  day  such  tact  can  be  guided  and  helped  by  accurate  theory,  which,  upon  a nearly  per- 
fect knowledge  of  how  different  chemical  elements  behave  towards  one  another,  can  calculate  arith- 
metically the  dimensions  of  the  furnace  and  the  proportions  of  ingredients  proper  to  a given  result 
This  will  be  better  understood  after  some  details  upon  the  construction  of  the  furnaces  themselves,  and 
description  of  their  parts. 

Figs.  2331  and  2332  are  respectively  a section  and  ground- 
plan  of  the  hearths,  or  furnaces,  in  use  about  the  middle  of  the 
sixteenth  century,  as  described  by  Agricola.  The  letter  h,  in 
both,  shows  the  hearth  proper  ; t,  the  tuyfere ; and  b,  the  bel- 
lows. This  form  is  not  unlike  the  blacksmith’s  hearth  of  our 
own  times  ; and  has,  in  fact,  been  perpetuated,  with  but  small 
modification,  in  the  Catalan  forges  of  the  present  day,  where 
a malleable  iron  is  produced  from  suitable  ore  by  the  first 
process.  More  refractory  ores  were  treated  in  crucibles  (as  it 
were)  of  a somewhat  different  shape,  a9  under ; where  Fig. 

2333  is  a ground-plan,  and  Fig.  2334  a section  through  x y of  that  plan.  The  same  scale  answers  for 
all  four  figures. 


Both  of  these  constructions  belonged  to  a period  when  iron,  more  or  less  malleable,  (an  object  ol 
earlier  utility  in  the  arts  than  crude  iron,)  was  produced  direct  from  ores  whose  choice  and  value 
depended  then  greatly  upon  such  a property.  And  both  are  of  the  kind  which  the  Germans  call 
ttuck-ofen,  and  the  French  fourneaux  it  masse,  (in  English,  pot  furnaces) — such  as  until  very  recentlv, 
tnd  still,  indeed,  are  used  in  Hungary,  Carinthia,  Styria,  and  along  the  Pyrenees.  Both  furnish  the 
reduced  metal  in  a solid  lump,  loupe , stuck,  or  salamander,  which  has  to  be  lilted  by  main  force  out  of 


IRON. 


the  hearth — the  fires,  of  course,  being  suffered  to  go  down  for  the  purpose.  The  second  kind  appears  to 
have  had,  like  the  modern  stiick-ofen,  a tap-hole  for  cinder  or  slag  to  be  removed.  The  stiick-ofen,  used 
at  present  in  what  was  formerly  the  principality  of  Henneberg,  are  shaped  internally 
like  the  adjoining  Fig.  2335.  They  are  from  seven  to  ten  feet  high,  built  of  sand- 
stone ; but  the  crucible  proper,  c,  is  of  cast-iron.  There  are  two  openings  : one  at  t, 
where  is  the  tuyere  ; the  other  in  front,  for  working — i.  e.,  removing  the  cinder  and 
the  metal.  The  cinder  is  always  running  out ; the  metal  is  kept  in  (it  is  never  very 
liquid)  by  a temporary  wall  of  brick,  which  is  taken  down  when  the  stuck  is  drawn. 

In  older  times,  the  lov.pe,  which  weighs  from  500  to  800  lbs.,  and  which  was  formed 
in  six  or  eight  hours,  was  drawn  every  day.  The  improvement  of  deepening  the  * 
hearth  left  room  for  several  loupes,  which  were  separated  in  the  workings  by  dry 
charges  of  fuel  only,  and  were  removed  every  Saturday  evening.  At  present,  the 
loupes,  separated  as  before,  are  drawn  whenever  the  hearth  becomes  full,  but  with- 
out emptying  the  furnace,  which  continues  in  blast  several  weeks. 

These  Henneberg  furnaces  are  types  of  an  improvement  which  was  beginning  in  the  time  of  Agricola 
and  is  known  in  Germany  as  the  fluss-ofen — in  France,  as  fourneaux  a manche — in  England,  as  tap 
furnaces.  The  aim  of  this  was  to  let  the  metal  run  out  as  well  as  the  cinder;  and  the  method  of 
attaining  the  aim  was  a contraction  of  the  crucible  proper,  whereby  the  heat  became  more  intense  and 
the  metal  more  liquid.  The  stiick-ofen — which,  to  be  sure,  always  yields  an  excellent  quality  of  metal 
— is  very  expensive,  both  in  ore  and  in  fuel : the  low  temperature  it  affords  is  not  sufficient  for  the 
reduction  and  subsequent  combination  of  divers  impurities  (such  as  manganese,  silicium,  <fec.)  in  the  ore, 
so  that  the  iron  is  left  comparatively  pure  ; and  as  the  slag  contains  ordinarily  aoout  40  per  cent,  of 
metallic  iron,  the  metal,  which  sinks  down  on  the  hearth  after  having  been  enveloped  in  this  slag,  be- 
comes also  partially  decarbureted,  and  is,  in  fact,  a mixture  of  crude  iron,  malleable  iron,  and  steel. 
The  fluss-ofen  rendered  the  greater  part  of  it  crude  iron  ; and  is,  therefore,  the  germ  of  the  modern 
high-furnace.  In  its  actual  state,  and  like  the  Henneberg  furnaces,  only  higher,  (from  20  to  35  feet,) 
the  fluss-ofen  continues  in  use  to  this  day  in  various  parts  of  Germany,  and  in  some  places  of  Sweden. 
Tire  Swedish  furnaces  were,  indeed,  until  recently,  all  properly  fluss-ofen.  Since  the  intervention  of 
Berzelius,  they  conform  more  to  the  models  generally  followed  in  other  parts  of  Europe  and  America. 

The  following  figures  will  serve  to  show  the  probable  march  of  improvement,  as  longer  observation, 
and  greater  range  of  materials  that  might  yield  iron,  suggested  the  successive  steps.  For  greater  gen- 


2335. 


eraflty  and  simplicity,  these  figures  show  only  the  cuvette  or  inside  section  of  the  furnace,  which  neces- 
sarily regulates  the  externals.  Thus,  there  is  no  doubt  that  the  earliest  shape  was  the  prism,  or 
cylinder,  shown  at  Fig..  2336,  which  we  know  to  have  been  in  use  in  the  time  of  Agricola.  As  it  would 
soon  be  observed  that,  with  such  a shape,  the  materials  were  too  heavily  pressed  below  to  allow  free 
passage  for  the  blast,  relief  in  this  respect  would  be  sought  by  battering  the  sides  inwards,  as  shown  in 
Fig.  2387  ; while  as,  upon  experience,  it  could  not  fail  to  be  noticed  that,  if  the  materials,  in  descend- 
ing, had  more  room,  they  would  spread  more  easily — on  this  account  the  shape  of  Fig.  2338  might  be 
preferred.  The  suitability  of  one  or  other  of  these  forms  would  be  regulated  by  the  less  or  greater 
fusibility  of  the  materials.  But  for  average  fusibility,  as  well  as  to  combine  the  greatest  advantage  of 
these  two  experimental  principles,  the  form  of  Fig.  2339  would  be  seen  to  be  the  best ; while  a slight 
alteration  of  this,  and  a combination,  in  fact,  of  all  previously  known  forms,  brings  us  to  the  form  of 
Fig.  2340,  which  is  exactly  the  modified  fluss-ofen  of  Henneberg,  before  described.  If  tl  e angles  of 


Fig.  2840  be  rounded  off,  either  designedly  or  by  the  degradations  consequent  upon  its  use,  it  will 
assume  the  form  of  Fig.  2341  which  is  that  of  the  ordinary  fluss-ofen  of  Europe.  Fig.  2342  is  a modi- 
fication of  Fig.  2339,  bringing  the  belly,  or  widest  part  of  the  cuvette,  nearer  to  the  blast,  as  would  be 


86 


IRON. 


found  desirable  for  less  fusible  ores  ; while  for  those  more  refractory,  a general  narrowing,  as  in  Fig. 
2343,  would  be  resorted  to.  Finally,  as  the  use  of  earthy  ores  became  prevalent,  it  was  found  better 
to  bring  the  top  of  the  boshes  (in  German,  biischung,  a talus,  or  slope)  nearer  to  the  tuybre,  and  to  narrow 
the  crucible  below,  as  shown  in  Figs.  234-4  and  2345,  which  are  tire  types  of  the  modern  high-furnace. 
In  both  these  figures,  h shows  tire  crucible,  c r hearth,  and  b the  boshes.  The  slope  of  these  last  is 
more  or  less  steep  according  to  the  fusibility  of  the  materials,  and  their  less  or  greater  fragility  under 
pressure  of  a superincumbent.  In  this  last  regard,  the  height  of  the  furnace-stack  is  an  element  in  the 
calculation ; although,  for  the  generality  intended  to  be  illustrated  by  the  figures,  as  well  as  for  the 
distinction  between  different  kinds  of  furnaces,  the  height  is  immaterial.  It  is  usual  to  call,  now,  every 
thing  above  27  feet  a high-f  urnace ; although,  in  the  method  of  treatment,  as  well  as  in  the  character 
of  metal  produced,  it  may  be,  as  in  parts  of  Germany  and  France,  a fluss-ofen,  and  although  it  may 
have  no  hearth  proper,  as  in  many  places  in  Sweden.  The  different  shape  of  the  in-walls — straight  in 
Fig.  2344,  curved  in  Fig.  2345,  of  either  of  which  many  examples  are  found— arises  more  from  caprice 
than  from  any  logical  conclusion.  The  latter  is  more  retentive  of  heat,  but  more  embarrassing  to  the 
blast ; in  the  latter,  therefore,  the  different  stages  of  the  process  will  be  more  distinctly  marked  than  in 
the  former.  If  the  object  be  to  gather  combustible  gases  at  the  trundle-head,  (as  in  the  method  ot 
Faber-Dufaure,)  the  shape  of  Fig.  2345  is  preferable. 

In  some  localities,  the  furnace  is  built  upon  the  flat,  and  a veritable  bridge  connects  with  the  hill.  In 
places  where  there  are  no  hills — as  in  Staffordshire,  for  instance — a long  ramp  is  constructed,  either  ol 
earth  or  carpentry,  along  whose  inclined  plane  the  materials  are  carried  up  by  suitable  machinery. 

Figs.  2346  and  2347  are  a section,  parallel  to  the  front,  and  a ground-plan  of  a blast-furnace,  which 
may  be  taken  as  a type  for  all,  whatever  may  be  the  materials  employed.  In  these  figures,  h is  the 


crucible,  or  hearth  ; t,  t',  indicate  the  passages  and  tuyeres  (pronounced  tweers)  for  the  blast.  In  F.g 
2346,  b shows  the  boshes , a term  applied  as  well  to  the  space  where  the  letter  is  as  to  the  stones  which 
inclose  it ; s is  the  general  mass  of  masonry,  called  the  stack  ; i are  the  in-walls,  of  refractory  materials, 
(stone  or  fire-brick,)  defining  the  cuvette  ; l is  the  lining,  of  broken  stone,  pounded  cinder,  <tc.,  loosely 
interposed  between  the  in-walls,  to  allow  them  to  expand  without  thrusting  more  than  can  be  helped 
against  the  stack,  and  also  helping  as  non-conductors  of  the  heat ; and  ff  indicate  the  ties,  of  bar-iron, 
which  run  quadrangularly  through  the  mass  of  the  stack  to  secure  it  still  further.  In-walls  are  some- 
times made  double,  with  a void  space  between  them.  It  is  obvious  that,  within  the  limits  of  their  gen- 
eral aim,  the  particular  dispositions  of  these  are  at  discretion.  A chimney,  generally  of  brick-work,  is 
shown  at  c.  On  Fig.  2347,  p p indicate  the  piers,  connected  by  arch- work,  for  supporting  the  stack 
vertically.  These  piers  are  generally  themselves  still  further  pierced  with  low  and  narrow  archways, 
(as  shown  by  the  dotted  fines  on  the  northeast  pier,)  to  allow  of  readier  communication  between  the 
tuyere-arches,  ttt,  where  the  blast-pipes  are.  The  arch  T,  in  front,  where  the  working  is  done,  is 
termed  the  tymp-arch — generally  larger  than  the  tuyere-arches.  This  plan  shows  three  tuyeres,  which 
is  an  establishment  for  a furnace  of  the  largest  class;  yet  very  many  have  but  two,  and  smaller  ones 
are  worked  with  but  one  tuyere. 

Fig.  2348  gives  an  enlarged  view  of  the  disposition  of  the  hearth  ana  boshes.  Here,  besides  the  parts 
alrea'dy  indicated  by  letters  before  used,  s shows  one  of  the  cast-iron  girders,  or  sows,  for  supporting  the 
thrust  of  tire  arch ; y is  the  tymp-stone,  protected  by  a casting  called  the  tymp-plate,  ( tymp , in  Welch, 
means  a delivery,  and  hence  is  applied  to  the  place  where  the  product  of  the  furnace  is  brought  forth,) 
both  from  the  iron  ringards,  or  long  crow-bars,  of  the  workmen,  and  Irorn  the  adhesion  of  the  cindei, 
which  is  very  strong  to  heated  stone  ; and  d is  the  dam- stone,  protected,  for  similar  reasons,  by  a casting 
called  the  dam-plate ; h shows  here  the  hearth-stone,  or  sole,  which  is  a single,  large,  refractory  stone, 
and  ought  to  underlie,  in  part,  the  dam-stone.  This  hearth-stone  ought  to  have  a fall  of  at  least  ^ inch 


IRON. 


87 


2348. 


to  the  foot,  towards  the  front,  to  assist  the  tymp  of  the  metal,  which  comes  out  through  a shoulder  cut 
in  the  lower  face  of  the  dam-stone.  The  cinder  pours  over  the  top  of  this  last,  'llie  place  for  the 
tuybre,  which  was  first  a square  opening  left  in  the  masonry,  is 
generally  filled  up  now  (since  the  use  of  hot  air  especially)  with  a 
double  hollow  cone,  called  a water-tuyere,  made  of  wrought-iron,  of 
Wrought-  iron  with  a mixture  of  copper,  or  of  cast-iron,  and  built  in 
with  fire-clay  on  the  tuyere-shelf.  Fig.  2349  is  intended  to  show  this 
utensil.  The  openings  at  a a are  intended,  the  one  to  admit,  the  other  to 
let  out,  the  water  which  circulates  in  the  tuyfere,  and  preserves  it  from 
the  action  of  the  heat  in  the 
hearth.  2349- 

After  stating  the  general  prin- 
ciple that  the  hearth  and  boshes 
should  be  of  the  most  refractory 
material  possible,  the  choice  of 
that  material,  of  its  position  and 
treatment,  it  is  obvious,  depends, 
within  certain  limits,  upon  cir- 
cumstances. Thus,  they  are  built 
of  sandstone,  dressed  or  undressed  ; of  soapstone  ; of  fire-brick  ; or  of  an  artificial  puzzolana  of  cinder 
and  fire-clay.  The  joints  are  always  laid  in  fire-clay,  worked  up  into  the  consistence  of  mortar. 

Having  now  the  nomenclature  of  the  principal  parts,  some  precautions  as  to  their  dispositions,  and 
some  requisites  as  to  their  proportions,  may  next  be  stated.  The  first  thing  after  a secure,  is  a dry 
foundation,  particularly  in  the  vicinity  of  the  hearth  ; and,  therefore,  too  much  provision  of  drains,  active 
enough  to  take  off  promptly  all  possible  moisture,  can  hardly  be  made.  Under  the  hearth-stone  should 
be  constructed  a false-bottom,  with  pieces  of  brick  or  stone,  so  as  to  avail  of  the  non-conducting  power 
of  air.  But  currents  through  this  are  to  be  avoided.  In  some  places  in  Sweden,  it  is,  to  be  sure,  the 
practice  still  to  provide  means  for  passing  water  under  the  bed  of  the  hearth-stone,  with  the  view  of 
increasing  its  duration.  But  such  a practice  cannot  be  approved  on  any  score. 

The  plan  of  the  hearth  is  square,  oblong,  or  circular,  or  elliptic.  The  two  last  forms  agree  best  with 
theory ; the  others  are  more  convenient  in  construction.  With  three  tuyeres,  an  oblong  hearth  is  neces- 
sary, on  account  of  the  less  resistance  opposite  to  the  third  tuyere  at  the  tymp  : with  two  tuyferes,  it  is 
still  advisable,  because  the  two  nozzles  should  never  be  opposite  exactly,  and  room  for  their  play  is 
desirable,  as  well  as  a better  distribution  of  the  blast.  So  far  as  the  resistance  to  the  blast  is  con- 
cerned, it  will  be  in  equilibrium  by  an  addition  of  § of  the  width  to  make  up  the  length. 

The  jambs  of  the  hearth  are  made  vertical,  or  with  various  degrees  of  batter,  from  -h-,  at  a minimum, 
to  ^ , at  a maximum,  of  the  height ; and  generally  inversely  as  the  height.  This  last  proportion  seems 
unreasonably  great,  and  must  embarrass  the  blast.  But  the  absolute  capacity  of  the  hearth  must  be 
taken  in  as  an  element  for  determining  the  batter;  as  also  the  quality  of  yield  which  is  aimed  at.  To 
make  foundry-iron,  the  batter  should  be  less  than  for  forge-pig.  The  proportions  of  W.  of  the  height 
for  the  former,  and  A for  the  latter,  seem  to  be  warranted  by  the  best  examples. 

The  slope  of  the  boshes,  or  angle  which  a section  of  their  face  makes  with  the  horizon,  varies  from 
55°  to  '70°.  There  are  some  instances  in  the  Harz  of  less  inclination  than  this;  but  it  is  not  recom- 
mendable.  A slope  of  60°  might  be  taken  as  a constant  to  present  the  maximum  advantage  ; for, 
strictly  speaking,  the  pressure  of  the  blast  can  be  regulated  so  as  to  compensate  for  unsuitability  ol 
slope,  iu  any  particular  case,  to  the  materials.  In  respect  to  these  last,  refractory  ores  and  soft  char- 
coal are  best  treated  with  a less  slope  ; but  fusible  ores,  and  coke,  or  charcoal  of  hard  wood,  will  behave 
better  with  steep  boshes.  The  length  of  the  boshes,  which  are  now  always  circular,  corresponds  with 
the  greatest  diameter  of  the  furnace,  or,  as  it  is  technically  called,  the  width . at  the  boshes. 

This  width,  it  is  obvious,  must  be  proportionate  to  the  height  of  the  cuvette,  or,  it  may  be  said,  the 
whole  height  of  the  stack  ; i.  e.,  the  higher  the  furnace,  the  wider  it  may  be  with  the  same  materials. 
But  with  a given  height,  the  width  should  vary  according  to  the  materials,  and  vice  versa.  These  two 
items,  therefore,  will  have  to  be  considered  together  in  this  respect ; and,  along  with  them,  another  of 
the  greatest  importance — the  quantity  and  pressure  of  the  blast  furnished.  And,  after  all,  we  can  only 
deal  in  generalities,  and  not  in  arithmetical  proportions,  which  can  only  be  derived,  for  a given  case, 
with  materials  of  known  composition  and  properties.  The  object  of  the  furnace,  at  all,  is  to  generate 
heat  to  melt  some  of  the  materials,  and  to  melt  them,  also,  at  a proper  place.  This  heat  is  produced 
bv  the  combustion  of  others,  (viz.  the  fuel;)  and  the  amount  of  such  heat  depends  upon  the  quantity 
of  these  last  burnt  in  a given  time ; which  quantity,  again,  depends  upon  the  weight  and  volume  of  air 
furnished  in  the  same  time — i.  e.,  upon  the  amount  of  blast.  The  greater  the  blast,  the  more  fuel  will 
be  burnt,  the  more  heat  generated,  and  the  more  matter  melted  in  a given  time.  Assuming,  then,  the 
blast  as  constant  and  suitable,  the  stack  should  be  of  such  a height  as  that  none  of  it  will  pass  out 
unaltered  at  the  trundle-head.  It  is  manifest  that,  with  a low  furnace,  a part  of  the  air  of  a strong 
blast  will  come  out  at  the  top  without  having  promoted  combustion  at  all,  and,  therefore,  at  a loss 
With  the  blast  constant  and  the  height  suitable  to  that,  the  next  thing  is  to  consider  the  effect  of  the 
width  at  the  boshes.  At  this  point  the  materials  have  attained  their  greatest  extension,  and  are  ready, 
some  for  being  burnt,  some  for  being  melted.  If  this  space  is  too  narrow  the  ores  will  arrive  too  soon 
at  a high  temperature ; fusible  ones  will  liquefy  in  the  upper  part  of  the  furnace,  refractory  ones  will 
fall  in  fragments  into  the  crucible,  not  having  had  opportunity  to  be  properly  cemented  and  reduced. 
It,  on  the  other  hand,  the  width  be  too  great,  the  temperature  will  be  insufficient,  and  even  fusible 
mines  will  descend  unaltered  into  the  crucible.  This  will  be  especially  the  case  with  charcoal  furnaces, 
whose'  fuel,  more  friable,  does  not  afford  the  same  resistance.  So  far  as  fuel  is  concerned,  then,  boshes 
for  charcoal  other  things  being  equal,  must  always  be  less  wide  than  for  coke ; and  even  for  another 


88 


iro:n. 


reason,  that  the  light  charcoal  is  easier  blown  aside  by  a strong  blast,  in  which  case  it  is  burned  against 
the  sides  of  the  stack,  where  its  combustion  is  comparatively  useless.  It  may  be  concluded,  then,  that 
the  width  of  boshes,  with  a given  height  of  stack  and  given  blast,  should  be  less  for  a friable  fuel  and 
for  refractory  ores  than  for  a compact  fuel  and  fusible  ores. 

Upon  the  boshes  rest  the  in-walls , and  their  junction  should  be  effected  to  present  the  least  angle 
possible.  The  materials  of  these,  as  wrell  as  of  the  non-conducting  and  elastic  lining  between  them  and 
the  solid  masonry  of  the  stack,  have  been  already  spoken  of.  Their  horizontal  section  is  always  circular, 
the  vertical  projection  of  their  face  sometimes  a straight,  sometimes  a curved  line.  The  former  is  more 
easy  to  build,  the  latter  more  retentive  of  heat,  and,  with  a mould-board  revolving  round  a central  shaft, 
presents  no  difficulty  in  construction.  In  forming  the  curve  of  this  mould-board,  the  shape  of  a common 
parabola  is  the  most  advantageous  to  be  employed  in  respect  to  the  distribution  of  heat. 

The  width  at  the  trundle-head  depends  upon  the  quantity  of  blast  intended  to  be  furnished,  and  also, 
in  a less  degree,  upon  the  quality  of  the  materials.  If  the  blast  is  very  strong,  it  should  be  less  than 
with  a weak  blast ; it  should  be  large  with  friable  fuel,  and  ores  that  tend  to  stick  together.  The 
widening  below  should  not  be  rapid,  as  if,  for  instance,  the  parabola  before  spoken  of  were  cut  off  near 
its  vertex,  for  the  materials  in  that  case  would  tend  to  distribute  themselves  unequally ; relieved  sud- 
denly from  lateral  pressure,  the  heavier  ores  would  descend  quicker  than  the  charcoal  or  cokes.  The 
general  practice  is  to  make  trundle-heads  narrower  than  theory  wruld  dictate,  under  an  apprehension 
of  loss  of  heat ; their  width  should  not  be  less  than  2-5ths,  and  in  most  cases  might  be  advantageously 
i that  of  the  boshes. 

The  chimney  surmounting  the  trundle-head  is  not  always  adopted ; in  proportion  to  the  size  and 
temperature  of  the  furnace  it  is  more  and  more  necessary.  It  is  built  uniformly  of  brick  upon  a cast- 
iron  bed-plate,  with  mortar  only  enough  to  hold  it  together,  and  further  retained  in  shape  by  ribs  and 
hoops  of  iron.  Its  height  is  from  one-fifth  to  one-fourth  that  of  the  stack,  and  its  inside  top-diameter  is 
generally  wider  by  the  length  of  a brick  than  its  base,  the  outside  face  of  the  wall  being  plumb. 

The  only  remaining  part  of  the  construction  which  has  not  been  mentioned  is  the  stack,  whose  func- 
tion, it  is  apparent,  is  only  that  of  a retaining-wall  to  hold  the  cuvette,  boshes,  &c.,  in  place.  This 
function  it  may  perform  either  by  its  inertia  or  by  its  cohesion.  In  the  first  alternative  it  is  generally 
built  of  stone-masonry,  laid  dry  where  it  approaches  the  lining,  and  mortared  elsewhere;  externally  it 
will  be  square,  the  width  of  the  base  will  be  equal,  or  very  nearly  so,  to  the  height  of  the  whole  stack 
above  the  foundations,  and  the  outside  face  will  be  battered  at  from  2£  to  3 inches  per  foot,  thus  making 
the  width  at  top  about  half  the  width  of  the  base.  These  are,  of  course,  only  average  and  generally 
unobjectionable  proportions.  Besides  this,  in  levels  of  every  4 or  5 feet,  binders  of  bar-iron  are  laid  in 
channels  of  12  or  16  square  inches  of  section  left  in  the  masonry  parallel  to  all  four  sides,  which  binders 
are  held  at  the  ends  by  suitable  holdfasts  that  can  be  tightened  either  with  a key  or  with  a nut. 
When  these  bars  break,  (as  they  not  unfrequently  do,)  they  can  be  drawn  out  of  their  channels  and 
others  substituted.  Besides  these  horizontal  channels,  there  are  vertical  flues  left  in  various  parts  ol 
the  stack  to  promote  the  expulsion  of  moisture,  which  otherwise  would  volatilize  into  steam,  and  accel- 
erate the  cracking  of  the  masonry.  This  tendency  to  crack  in  the  stack  seems  so  confirmed  that  there 
is  hardly  a furnace  of  any  considerable  size  in  the  world  which  does  not  show  it.  Except  for  a certain 
loss  of  heat  these  cracks  do  not  injure  a furnace,  provided  the  in-walls  remain  unhurt.  Finally,  there 
is  a dust-flue  (in  large  furnaces)  communicating  from  the  top  with  the  tymp-arcli. 

2350.  2351. 


When,  as  in  the  second  alternative,  it  is  the  cohesion  of  the  stack  that  is  relied  on  to  retain  the  in 
.•alls,  it  is  generally  built  of  bricks,  circular,  and  tied  with  many  vertical  staves  and  hoops  of  wrought- 
iron.  Such  stacks  are  generally  termed  cupola  blast-furnaces,  but  they  are  never  of  the  largest 


IRON. 


8'j 


dimensions.  The  external  proportions  vary  according  to  the  fancy  of  each  builder.  Fig.  2350  shows 
an  ordinary  furnace  of  this  sort;  Fig.  2351  another,  remarkable  for  appropriateness,  ingenuity,  and 
taste. 

Blast-furnaces  have  universally  a roof,  over  the  ground  adjacent  to  the  front  and  sides,  of  greater  or 
less  extent,  called  the  moulding-house ; and  one,  adjacent  at  the  top  and  approaching  more  or  less  near 
to  the  chimney,  called  the  top-house,  or  bridge-house.  The  necessity  of  these  in  protecting  from  weather 
the  workmen,  materials,  and  metal,  is  obvious.  They  are  also  advantageous  in  proportion  to  their  ex- 
tent, the  spouts  with  which  they  are  furnished,  <fec.,  in  keeping  the  foundation,  (fee.,  of  the  furnace  itself 
dry.  As  far  as  possible,  the  materials  used  in  these  buildings  should  be  iron,  to  avoid  risk  of  fire. 

The  difference  of  materials  in  furnaces  has  been  frequently  spoken  of  already  as  entailing  a difference 
in  dimensions.  The  principal  influence  in  this  respect  is  due  to  the  fuel ; and  hence  there  is  a marked 
difference  in  size  between  charcoal  and  coke  furnaces.  The  necessity  for  this  is  apparent,  when  we 
consider,  that  with  equal  volumes,  the  heating  effect  of  charcoal  is  but  one-half  that  of  coke  ; of  two 
furnaces,  then,  of  the  same  size,  the  one  fed  with  charcoal  can  never  be  raised  to  so  high  a temperature 
as  the  other,  for  even  the  most  obvious  steps  towards  equalizing  them  (viz.  continually  supplying  fresh 
charges  of  charcoal)  have  of  themselves  a cooling  tendency. 

The  following  table  will  show,  at  a glance,  the  comparative  dimensions,  <fec.,  of  these  two  classes  of 
furnaces,  established  upon  what  is  considered  a fair  average  of  each.  The  particulars  under  the  head 
of  anthracite  are  taken  from  what  may  be  regarded  as  the  latest  improvements  for  the  uje  of  that  fuel 


Dimensions. 

Hig 

Charcoal. 

'h-fu  maces,  using 
Coke. 

Anthracite. 

Stack,  height  from  foundation 

35  feet, 

50  feet, 

35  feet. 

width  at  base  

28  “ 

50  “ 

40 

width  at  top 

167-  “ 

25  “ 

33  “ 

Cuvette,  diameter  of  trundle-head 

4 

8 “ 

0 “ 

height  of  conical  in-walls 

257-  “ 

33  “ 

it 

do.  cylindrical  

— 

— 

8 “ 

width  at  boshes  

9i  “ 

15  “ 

12 

angle  of  boshes 

55  degrees, 

65  degrees, 

75  degrees. 

height  of  boshes 

4J  feet, 

10  J feet, 

1 1 feet. 

Crucible,  height  of  hearth 

5 “ 

6*  “ 

5 

mean  of  length  and  breadth  at  top 

24  “ 

5 “ 

6 “ 

do.  do.  at  bottom 

2 tl 

4 “ 

4 

height  of  tuybre  above  hearth-stone 

Approximate  capacity 

Descent  of  charges  in  about  

U “ 

1000  cub.  feet, 
20  hours, 

2 “ 

4500  cub.  feet. 
40  hours. 

If  “ 

These  dimensions  and  proportions  undergo  changes,  necessarily  to  be  accommodated  to  different  ores, 
they  are  often  arbitrarily  modified  besides,  or  follow  a routine  established  at  earlier  periods  of  the  art 
of  smelting.  Thus,  in  South  Germany,  the  old  Jluss-ofen  is  still  substantially  retained ; in  Sweden, 
many  high-furnaces  are  still  erected  without  a crucible,  i.  e.  with  a continued  talus  from  the  top  of  the 
boshes  to  the  hearth-stone  ; in  Wales,  where  the  product  surpasses  that  of  any  other  part  of  the  world, 
the  furnaces  are  lofty  and  vast — some  (but  an  unsuccessful  model,  it  is  said)  attaining  a height  of  70 
and  a width  of  20  feet ; the  English  furnaces  of  Staffordshire  are  lower,  but,  in  proportion,  more  wide  ; 
the  Scottish  are  more  cylinder-like  and  squatter,  still.  In  America,  there  cannot  be  said  to  be  any  pre- 
vailing type  for  charcoal  works ; the  coke  furnaces  are  said  by  Overman  to  be  generally  on  the  model 
of  the  first  successful  one, — that  at  Lonaconing  in  Maryland  : while  the  use  of  anthracite  as  a fuel  has 
yet  received  so  little  extension  as  hardly  to  present  more  than  a few  instances. 

With  these  explanations  of  the  means  made  use  of)  we  can  now  pass  to  the  materials  employed  in 
the  smelting  of  iron,  and  their  respective  preparation. 

1.  Fuel.  This  is  one  of  the  most  important  materials,  both  in  regard  to  quality  andcost.  We  have 
already  seen  that  it  constitutes  the  index  in  a classification  of  furnaces ; and  when  it  is  considered  that 
there  are  many  situations  whose  ores  cannot  be  availed  of  because  of  the  inconvenient  supply  of  fuel, 
the  propriety  of  placing  it  first  in  the  list  of  materials  will  be  apparent.  The  object  in  the  use  of  fuel 
is  principally  to  obtain  heat,  but  it  also  acts  in  the  furnace  upon  the  other  materials  as  a reducing  and 
deoxidizing  agent.  In  both  of  these  aspects,  its  value  is  in  proportion  to  the  carbon  which  it  contains ; 
and  in  the  last  aspect,  it  is  not  mere  flame  or  heat  which  is  wanted  in  the  furnace,  but  the  contact  also 
of  carbonaceous  matter  with  the  materials  to  be  reduced.  Wood,  whose  chemical  constitution  may  be 
taken  in  general  at  50  per  cent,  of  carbon  and  50  per  cent,  of  oxygen  and  hydrogen,  in  proportions  form- 
ing water,  contains  too  little  carbon  in  its  natural  state  to  be  advantageously  employed  in  a furnace. 
Compared  with  coke,  its  calorific  effect  under  equal  volumes  is  but  one-fifth  of  the  latter ; it  therefore 
would  not  raise  the  temperature  sufficiently.  It  has  been  attempted  to  be  applied  in  a baked  or  torri- 
fied  state,  but  not  with  sufficient  success  to  induce  a further  use.  The  presence  of  hydrogen,  which  pro- 
motes inflammability,  and  which,  although  under  some  circumstances  it  acts  as  a deoxidizer,  does  not 
so  act  in  a furnace  further  than  upon  the  combustible  itself,  is  a permanent  obstacle  to  the  employment 
of  all  fuel  in  proportion  as  it  exists.  Hence  raw  coal  is,  in  general,  improper;  turf  and  lignite,  or  brown 
coal,  are  in  the  same  category.  The  last  named  burn  too  much  in  the  attempt  to  carbonize  them ; but 
pressed  and  chaired  turf  is  quite  extensively  used  in  France,  Germany,  and  Russia,  for  the  manufacture 
of  iron.  For  smiths’  work,  it  is  said  to  furnish  a charcoal  of  peculiar  excellence.  In  America,  where 
there  is  so  much  other  fuel  of  a character  as  unquestionable  and  of  supply  more  convenient,  its  consid- 
eration may  as  yet  be  left  out  of  question ; and  all  that  will  be  treated  of  here  is  the  preparation  of 
wood  and  coal,  the  one  by  charring,  the  other  by  coking,  for  the  purposes  of  the  iron-master.  The  gen- 


90 


mo  jn  . 


eral  principles  of  carbonizing  either  fuel  are  the  same : viz.,  the  expulsion,  by  heat,  without  contact  ol 
ah',  of  the  volatile  constituents  of  the  fuel.  These  constituents  go  off  in  part  as  gases,  containing  more 
or  less  carbon,  and,  in  part,  as  new  combinations  which  are  still  liquid  at  a high  temperature ; as,  for 
instance,  acetic  acid,  tar,  &c.  The  distillation  of  wood  or  coal,  with  a view  to  economizing  any  other 
products  than  residual  carbon,  does  not  form  any  part  of  the  business  of  iron-working. 

The  means,  too,  for  carbonizing  either  fuel  for  this  special  metallurgic  use  are  similar,  in  kind,  though 
the  details  of  the  methods  vary  for  both  considerably.  These  details  may,  however,  be  grouped  into 
two  great  classes:  1.  Where  the  carbonization  is  effected  in  a permanent,  air-excluding  oven:  2.  Where 
it  is  done  in  clamps,  or  kilns,  or  heaps.  In  the  general  aspect  of  carbonization,  the  means  employed 
would  have  to  be  antecedently  classed  according  as  use  may  be  made,  first,  of  other  fuel  than  that  to 
be  carbonized,  in  order  to  general  e the  requisite  heat,  or  secondly,  of  a part  of  the  mass  itself,  for  the 
charring  of  the  other  part.  The  type  of  the  first  system  is  seen  generally  in  all  the  apparatus  where 
other  products  than  carbon  are  sought  to  be  collected,  and  where  the  coke  or  charcoal  are  incidental  to 
the  operation  ; as  in  gas  retorts,  or  the  cylinders  for  pyroligneous  acid  or  wood  vinegar.  Although  a 
system  like  these  might,  in  some  localities,  where  fuel  was  abundant  or  in  different  qualities,  be  ad- 
vantageously introduced,  there  is  probably  no  iron  establishment  where  it  is  resorted  to ; and  the  other 
classification,  of  ovens  or  kilns,  remains  as  the  only  one  that  need  be  discussed  here. 

The  relative  advantages  of  these  two  methods  can  only  be  ascertained  by  a comparison  of  their  prod- 
ucts in  quantity  and  quality.  With  respect  to  the  first  element,  quantity,  it  may  be  assumed  (though 
it  is  not  universally  admitted)  that  ovens  produce  a greater  quantity,  by  weight,  of  carbon  from  the 
raw  material.  Hardly  any  collier  can  claim  a yield  of  more  than  20  per  cent,  of  charcoal,  for  instance 
from  heaps ; while  the  best  ovens,  with  perhaps  less  trouble,  though  not  less  expense  in  individual 
cases,  will  give  about  25  per  cent.  Again,  in  the  assemblage  of  cases,  the  expense  for  ovens  is  proba- 
bly less ; being  less  exposed  to  accidents  from  weather,  neglect,  &c.,  which  sometimes  result  in  the 
combustion  of  an  entire  kiln. 

With  respect  to  quality  of  product,  the  evidence  is  less  decisive.  It  would  seem  in  theory  that  the 
oven,  producing  a greater  weight  of  carbon,  ought  also  to  produce  a heavier  material,  per  se.  But  such 
is  not  always,  nor  even  generally,  the  case ; and  where  the  oven  charcoal  or  coke  are  of  the  highest 
specific  gravity,  (and  the  economy  of  a high  specific  gravity  is,  in  general,  undoubted,)  yet  from  some 
cause,  such  as  a peculiar  arrangement  or  disarrangement  of  fibres,  it  is  not  found  to  develop  so  much 
heat  as  that  prepared  in  kilns.  This  point  of  quality,  therefore,  and,  indeed,  the  whole  question  as 
between  ovens  ^and  kilns,  need  a more  profound  and  extensive  investigation.  All  that  will  be  done 
here  is  to  describe  the  most  usual  and  simple  details  of  both  methods-,  first,  for  charcoal,  and  then, 
for  coke. 

Charring  of  wood  is  still  practised  in  Austria  after  methods  which  seem  to  have  originated  under  the 
period  of  Roman  domination,  for  the  manufac- 
ture of  the  celebrated  Norman  iron.  These  may 
be  denominated  charring  in  heaps,  (Germ,  hauf- 
en,)  or  clamps ; and  will  be  understood  from 
the  accompanying  sketches,  of  which  Fig.  2352 
shows  a side-view,  and  Fig.  2353  a ground-plan 
of  the  arrangement.  The  ground  for  this  may 
be  either  levelled  or  sloped.  In  either  case, 
pipes  ate  sometimes,  but  rarely,  laid  in  the  up- 
per parts  of  the  clamp,  to  carry  off  some  of  the 
liquid  products.  The  length  of  the  clamp  (and, 
of  course,  the  number  of  posts)  is  arbitrary — gen- 
erally from  40  to  50  feet ; the  width  depends 
upon  the  length  of  the  logs,  which,  being  ordi- 
narily 4 feet,  and  being  laid  in  a double  row, 
with  a very  small  space,  to  the  casing  of  the 
sides,  will  make  the  width  very  nearly  9 feet 
across,  from  post  to  post.  In  Fig.  2353  the  logs 
are  given  as  if  in  but  one  length,  which  can  very 
well  be  if  the  sticks  are  light.  The  casing  may 
be  of  plank,  slabs,  or  split  cord-wood.  The  ground  is  well  pounded ; and,  if  in  an  old  burning,  with 
charcoal  and  dust.  The  logs  are  then  piled,  beginning  from  the  upper  part,  to  within  a few  inches  o) 
the  top  of  the  casing.  Then  it  is  covered  with  chips,  twigs  and  leaves,  and  finally  with  sand  or  (better) 
dust,  which  material  is  also  filled  in  against  the  casing,  to  protect  it  from  fire.  After  all  this  is  ready, 
fire  is  put  in  at  the  lower  end,  and  some  of  the  dust  is  removed  from  the  upper  end  to  make  a draught. 
Draught-holes  are  also  opened  at  discretion  in  the  sides  of  the  casing.  When  the  smoke  comes  out 
where  the  dust  is  removed,  it  is  necessary  to  throw  it  on  again,  and  open  elsewhere  with  caution.  In 
this  manner  the  fire  is.  led  on  till  the  heat  has  charred  the  whole.  The  peculiar  advantage  of  this 
method  is  supposed  to  be,  that  with  a clamp,  say  of  50  feet,  charcoal  may  be  drawn  from  the  lower 
end  after  the  fire  has  progressed  about  ten  feet,  which  it  will  do,  ordinarily,  in  twenty-four  hours.  This 
is  still  further  helped  by  making  it  on  sloping  ground.  If  well  packed,  a clamp  of  50  feet  by  9 feet,  8 
feet  high  at  the  head,  and  3 feet  at  the  foot,  will  hold  about  15  cords. 

Another  method,  more  extensively  and  commonly  practised,  is  that  of  kilns,  (Germ,  metier ; Fr. 
meules.)  These  kilns  are  of  two  kinds,  standing  and  lying ; the  wood  standing  on  its  end  in  the  one, 
and  lying  on  its  side  in  the  other,  as  shown  in  Figs.  2354  and  2355. 

The  circle,  to  be  levelled  and  pounded  down,  for  a kiln  of  this  sort,  will  be  from  40  to  50  feet  in 
diameter;  the  driest  ground  must  be  selected  for  the  purpose,  and  a place  sheltered  from  winds.  The 
best  period  for  burning,  in  America,  is  from  the  middle  of  May  until  the  middle  of  August ; and  then 


235-2. 


IRON. 


91 


again  in  October  and  November,  during  the  season  known  as  the  Indian  summer.  Wood  which  has 
been  felled,  and  lopped,  and  barked  in  December  and  January,  will  be  sufficiently  seasoned  to  char  in 
the  autumn  following.  After  the  logs  have  been  arranged,  as  in  the  figures,  around  the  three  long 
stakes  of  ten  or  twelve  feet  in  length,  (which  are  to  serve  as  a chimney,)  and  piled  as  evenly  and  com- 
pactly as  possible,  the  whole  pile  must  be  covered  to  keep  out  the  air.  A site  for  a coaling  improve1' 
2355.  2354. 


by  use,  for  the  charcoal  and  loam  get  trodden  and  mixed  together,  forming  the  best  material  for  the  cov- 
ering. On  entirely  new  ground  use  must  be  had  of  sod.  When  covered,  fire  is  applied,  either  through 
the  top  and  suffered  to  fall  through  to  the  centre,  where  provision  has  been  made  of  some  light  wood 
to  catch  readily,  or  through  a horizontal  flue  left  along  the  ground,  which  is  closed  at  its  entrance  as 
soon  as  the  fire  has  taken.  For  the  first  twelve  hours  the  kiln  must  be  closely  watched,  and,  therefore, 
it  is  usual  to  light  at  daybreak.  At  the  end  of  that  period,  or  a little  longer,  according  to  the  kind  of 
wood,  its  state  of  seasoning,  and  the  skill  of  the  collier,  the  fire  will  have  taken  sufficiently,  and  the  top 
may  be  covered  in  with  dust  and  loam.  From  that  time,  it  is  better  that  the  operation  should  proceed 
as  gradually  and  slowly  as  possible.  In  three  or  four  days  the  cover  begins  to  shrink  and  fall  in,  and 
fresh  watchfulness  is  required  to  stop  every  opening  thus  made,  and  even  new  ones  are  made  to  effect 
an  equable  distribution  of  heat.  These  are  points  that  cannot  be  taught  by  talking ; they  are  lessons  of 
experience  and  observation.  When  the  cover  sinks  gradually,  and  the  smoke  grows  less  and  less,  reg- 
ularly, the  work  is  known  to  be  going  on  well.  Expert  colliers  find  indications  of  the  process  in  the 
color  of  the  vapor  and  smoke,  which  varies  at  different  stages.  After  all  smoke  has  ceased,  the  kiln  is 
entirely  and  thickly  covered,  and  left  for  four  or  five  days,  less  or  more  according  to  its  size,  to  cool. 
The  coal  is  begun  to  be  drawn  from  the  foot,  but  cautiously  at  first,  until  it  is  found  to  be  too  cool  to 
re-ignite  upon  admission  of  air.  If  so,  the  drawing  may  be  continued  all  round  for  coal  that  is  wanted, 
peeling  it  off,  as  it  were,  like  an  onion  ; the  whole  contents  may  be  hauled  off  to  store,  or  it  may  be  left 
(covered  up  again)  to  be  resorted  to  when  wanted.  In  proportion  as  the  kiln  is  well  piled,  flues  in 
various  places  are  unnecessary.  It  sometimes  happens  that  the  fire  takes  in  particular  parts,  or  does 
not  take  at  all.  In  this  last  event,  the  advantage  of  a horizontal  firing  flue  is  tested.  A kiln  of  ordi 
nary  size,  of  this  kind,  holds  about  30  cords  ; the  largest  contain  50  cords. 

When  the  circumstances  are  such  as  to  render  it  likely  that'  the  same  charring-ground  will  be  used 
for  a considerable  period,  it  is  worth 
while  to  adapt  to  it  some  permanent 
accessions,  as  indicated  in  Fig.  2356  ; 
which  represents  the  section  of  a 
basin  laid  in  dry  brick,  to  serve  as 
the  ground  of  the  kiln.  This  basin 
has  a pit  at  p,  with  a cast-iron  cover 
c,  to  keep  ashes  out,  and  a gutter,  </, 
communicating  with  the  tank  t,  which 

receives  the  liquid  products  of  carbonization.  With  resinous  wood,  these  products  are  advantageously 
removed  as  soon  as  possible  from  the  charcoal,  and  are  valuable  when  caught.  The  tank  has  a lid,  i, 
which  must  be  laid  over  it  and  luted  when  the  kiln  is  fired. 

Midway  between  ovens  and  kilns  comes  the  shroud  or  abri  of  Foncauld  ; of  which  a side-view  is 
shown  in  Fig.  2351,  and  an  orthographic  one  in  Fig.  2358.  It  consists,  in  fact,  of  a series  of  trapezial 
ladders,  made  of  light  frames,  and  capable  of  enclosing  a circle  at  the  base  of  30  feet,  at  the  top  of  10 


(eet,  with  an  elevation  of  8 or  9 feet.  The  sides  of  these  frames  are  furnished  with  mortises  or  lugs, 
by  which  two  adjoining  strings  can  be  keyed  together  with  wooden  bolts.  The  top  is  a flat  cover  of 


92 


IRON. 


scantling,  with  traps  that  can  be  opened  or  shut  for  the  passage  of  air,  and  also  for  that  of  a conduit 
made  of  three  pieces  of  light  plank,  for  the  condensation  of  gaseous  products.  The  effect  of  these  lad- 
ders is  to  allow  of  a better  packing  (and,  as  it  were,  thatching)  of  the  ordinary  loam  covering  of  kilns. 
Fire  is  applied,  and  air  furnished  at  first  through  the  door  d,  left  in  one  of  the  ladders.  The  charcoal 
furnished  by  this  method  is  said  to  be  of  superior  quality ; its  yield  is  stated  at  24  per  cent,  of  the 
wood,  with  20  per  cent,  besides  in  crude  pyroligneous  acid.  This  yield  of  charcoal  is  about  one-fifth 
more  than  from  the  kilns  that  have  been  described. 

Of  ovens  there  is  a great  variety  of  form  ; but  as  tire  most  of  them  are  embarrassed  with  apparatus 
for  collecting  other  products  besides  charcoal,  they  are  more  connected  with  distillation  than  carbon- 
ization for  the  manufacture  of  iron.  Only  one,  of  the  most  simple  and  economical  form,  and  yet  yielding 
good  results,  will  be  described.  A portion  of  it  is  shown  in  Fig.  2359,  which  is  supposed  to  give  a tol- 
erably clear  idea  of  the  plan.  The  building  from  which  this  is  taken  is  about  50  feet  long,  12  feet  wide 
in  the  clear,  and  12  feet  high,  and  will  hold,  well  packed,  about  60  cords,  a quantity  that  has  been  found 
to  present  the  maximum  of  convenience  and  economy,  c shows  the  chimney-hole  in  the  centre  for  firing, 
ff  flue-holes  foi  the  draught,  of  which  there  are  others  on  top  which  cannot  be  seen.  At  the  ends 
there  is  a small  door  for  charging  and  drawing.  The  stays  are  of  cast-iron  or  wood,  the  horizontal 
binders  on  top  of  bar-iron.  Wooden  scantling  was  first  used  for  both  these,  but  it  is  neither  so  safe  nor 
so  strong.  The  arch  which  is  sprung  for  the  top  is  low,  but  yet,  when  the  fire  is  in,  there  is  considerable 
thrust  against  the  walls.  These  walls  are  1-J  brick,  and  must  be  well  laid  and  joined.  As  the  acetous 
products  in  the  oven  are  apt  to  attack  the  lime,  asphalt,  or  a bituminous  cement  made  of  coal-tar  and 
loam,  is  used  instead  of  ordinary  mortar.  Coal-tar  is  also  advantageously  used  for  coating  the  outside. 
The  wood  is  piled  lying,  as  is  seen  in  the  figure.  Under  the  chimney-hole,  a chimney  (so  to  call  it)  is 
left  in  the  pile,  at  the  bottom  of  which  the  fire  is  placed.  The  wood  may  be  kindled  through  the 
draught-holes  or  at  the  doors,  but  less  economically.  When  the  fire  is  first  started  all  air-holes  are  shut; 
when  it  is  fairly  caught  the  chimney  may  be  filled  up  with  dry  wood,  the  hole  closed,  but  not  tightly, 
and  air-holes  opened  at  the  ends.  This  will  happen  in  seven  or  eight  hours.  The  operation  must  now 
be  watched,  and  by  the  emission  of  smoke  and  vapor  through  the  air-holes,  a judgment  may  be  formed 
as  to  where  they  should  be  shut  and  where  opened.  In  45  to  50  hours  the  whole  oven  will  have  been 
heated ; all  openings  are  then  closed  and  luted,  and  the  concern  left  for  three  or  four  days  to  cool.  On 
the  fourth  or  fifth  day  at  latest  the  coal  should  be  fit  to  be  drawn. 

To  what  has  been  said,  may  be  added  some  generalities  as  to  the  choice  of  wood  and  quality  of  the 
charcoal.  The  denser  woods  are  to  be  preferred,  because,  other  things  equal,  they  afford  a denser  and 
harder  charcoal.  Decayed  or  doted  wood  will  not  yield  a good  article ; and  charcoal  from  green  wood 
is  more  light,  more  friable,  and  less  calorific  than  from  dry,  besides  being  less  economical  in  the  manu- 
facture. The  trees  should  be  felled  when  the  sap  is  down,  i.  e.  in  the  winter,  from  December  to 
February.  Small  timber  is  in  general,  and  young  timber  always,  worse  than  that  which  has  attained 
a larger  and  more  mature  growth.  Yet  very  old  wood  is  not  so  good,  because  there  is  always  more  or 
loss  decomposition  of  the  fibre.  Branches  of  trees  give  less  and  a lighter  charcoal  than  the  boles,  and 
the  best  of  all  is  furnished  by  that  part  of  the  trunk  and  roots  nearest  the  ground.  In  the  ordinary 
felling  of  trees  this  part  is  all  lost.  Hence  it  would  be  better  for  the  purpose  (and  the  land  would  be 
left  in  a better  state)  to  extract  the  trees  at  once  by  the  roots,  as  is  very  easy,  and  then  saw  the  timber 
instead  of  cutting.  Heavy  charcoal  produces  more  heat,  but  its  reducing  effect  is  not  in  every  case  in 
proportion.  There  are  some  mines  with  which  lighter  charcoal  acts  better ; but  that  it  should  be  hard 
is  an  important  characteristic  universally.  Charcoal  just  from  the  kiln  burns  quicker  and  produces 
less  heat  than  that  which  has  been  kept  some  time  in  store,  yet  very  old  charcoal  is  admitted  to  be  less 
valuable  than  what  has  not  passed  over  one  season.  To  what  this  is  owing  is  not  clear,  for  the  affinity 
of  the  material  for  moisture  is  exercised  very  promptly,  and  after  the  first  24  hours,  in  an  ordinary 
atmosphere  and  with  reasonable  precautions,  it  does  not  materially  increase  in  weight.  It  is  better  to 
keep  charcoal  in  store  than  to  leave  it  stored  in  the  kiln.  After  it  has  grown  cool  enough  to  handle, 
the  sooner  it  is  made  quite  cold  the  better;  all  gradual  expulsion  of  heat,  such  as  occurs  in  a kiln,  is  at 
an  expense  of  carbon.  With  ovens  this  caution  is  unnecessary,  for  the  circumstances  there  always 
compel  removal  of  the  charcoal  as  soon  as  manufactured.  The  product  in  charcoal  ranges  from  18  to 
22  per  cent,  in  kilns,  and  from  20  to  25  per  cent,  iu  ovens.  By  volume  a cord  of  wood,  128  cubic  feet, 
well  corded,  ought  to  give,  at  a mean,  40  bushels  of  charcoal.  The  price  depends,  of  course,  upon  the 
value  of  labor  in  every  locality,  and  the  distance  of  hauling.  The  chopping  of  a cord  of  wood  is  equiv- 
alent to  about  one-tliird  of  a day's  labor  in  the  abstract,  and  the  coaling  of  it  in  kilns  or  clamps  after- 
wards to  about  a half  day.  The  computations  of  the  charcoal-burner  are  usually  made  upon  the  100 
bushels  of  charcoal  delivered.  Coaling  in  ovens,  although  in  fact  less  laborious  and  demanding  less 
experience,  requires  more  tact,  and  wages  there  are  generally  higher. 

The  charring  of  coal,  or  coking,  (from  the  German  word  kochen,  to  cook,)  is  the  same  in  principle  as 
that  of  wood,  and  the  processes  are  very  similar,  though  in  some  respects  the  considerations  are  different. 
Thus  the  coker  does  not  fear,  like  the  charcoal-burner,  either  air  or  moisture,  nor  is  he  troubled  with  the 
shrinkage  and  falling  in  of  the  kiln.  On  the  contrary,  for  coke  there  has  to  be  a large  supply  of  air  to 
determine  combustion  at  all ; the  volume  is  in  general  increased  during  the  process,  while  moisture, 
during  the  earlier  stages,  (but  after  the  fire  has  obtained  full  way,)  is  recommended  as  a desulphuret- 
ting  agent.  It  does,  in  fact,  so  act,  but  hardly  to  the  extent  that  is  claimed  for  it  in  theory,  and  some 
times  supposed  in  practice;  for  the  proportions  of  sulphur  remaining  in  the  coke  from  the  same  coal, 
treated  either  way,  do  not  appreciably  differ.  On  the  other  hand,  coke-burning,  subject  to  the  same 
general  category  of  regularity  and  manageability  of  temperature,  and  therefore  when  in  the  pure  air 
liable  to  accidents  from  high  winds,  <fee.,  of  the  same  sort  as  occur  to  charcoal  kilns,  has  to  undergo 
constantly  a greater  per  centage  of  loss  from  combustion.  This  loss  is,  on  the  average,  about  6 per 
’eut.,  so  that  coal  which,  on  analysis,  shows  85  per  cent,  of  carbon  and  earthy  matter,  will  rarely  give 
80  per  cent,  of  coke,  allowance  being  made  for  the  quantity  (from  5 to  10  per  cent.)  converted  into  rtack. 


IRON. 


93 


Coke  is  made  in  heaps , in  clamps,  and  in  ovens.  A suitable  contrivance,  and  much  used  for  heap-coking, 
is  shown  in  Fig.  2360,  the  central  shaft  of  which  is  a cylindrical  or  conical  chimney  loosely  built  of 
brick,  (terminated  in  the  sketch  as  in  Staffordshire, 
with  a cast-iron  chimney-liead,)  against  which  the 
coal  is  piled  conically,  not  tightly,  and  often  with 
regular  flues  and  intervals  left  between  the  masses. 

As  with  wood,  the  heaviest  lumps  are  near  the 
centre,  the  lighter  outside.  Coke-dust  and  slack- 
coal  are  used  as  a cover  and  for  stopping.  Ig- 
nited coal  or  coke  is  thrown  in  the  chimney,  and  fire 
is  sometimes  introduced  by  the  horizontal  flues  be- 
low. After  the  fire  is  started,  similar  precautions  are  required  as  with  charcoal.  The  height  of  the 
chimney  is  from  5 to  6 feet,  the  diameter  of  the  heap  from  14  to  16  feet,  and  it  will  take  from  10  to  12 
tons  of  coal.  As  the  process  advances,  slack-coal  is  thrown  on  in  some  places,  and  openings  with  a 
crow-bar  made  in  others,  according  as  the  coker  wishes  to  direct  the  heat,  and  water  is  injected  plenti- 
fully, both  to  control  the  heat  and  desulphurate  the  fuel,  if  it  is  supposed  to  need  it,  and  finally  to  put 
out  the  fire.  A heap  of  the  size  given  will  be  thoroughly  coked  in  two  and  a half  or  three  days ; it  is 
then  left  four  days  to  cool,  the  whole  operation  requiring  about  a week. 

In  Wales  clamps  are  more  used  for  coking,  which  are  long  piles  6 or  6 feet  wide,  2J  to  3 feet  high, 
and  in  lengths  varying  according  to  the  extent  of  coke-yard,  from  60  to  100  feet  or  more.  One  of  60 
feet  will  be  of  30  to  40  tons.  The  coal  is  piled  as  in  the  other  method,  the  largest  pieces  inside,  loose 
throughout,  and  with  horizontal  flues.  In  place  of  the  chimney,  however,  a stout  stake  is  driven  in  the 
middle  of  the  width  and  at  every  two  yards  of  the  length,  to  serve  as  a guide  in  piling.  When  the  coal 
is  piled  the  stakes  are  pulled  out,  and  the  space  they  leave  becomes  a chimney,  into  which  the  fire  is 
placed  as  before.  Sometimes  the  clamp  is  fired  in  its  whole  length  at  once ; most  usually  it  is  fired  at 
but  one  end,  (regard  being  had  to  the  state  of  the  wind  at  the  time  and  its  probable  permanence,)  and 
even  before  the  piling  at  the  other  is  finished,  so  that  it  is  a common  thing  to  see  coke  drawn  from  one 
end  and  coal  piled  on  the  other  end  of  a clamp  at  the  same  moment.  The  coke  yielded  by  either  of 
these  methods  is  supposed  to  be  better  for  iron-making  than  by  any  other  way ; but  they  are  both 
costly  in  coal  consumed,  the  latter  especially.  Where,  however,  as  in  the  districts  of  its  principal 
employment,  coal  is  abundant  and  cheap,  it  presents  divers  conveniences  which  are  probably  cheaply 
purchased. 

Slack-coal,  i.  e.  coal  beaten  and  comminuted  in  very  small  fragments  or  powder,  (Germ,  schlag,  a 
stamp,  a blow,  and,  by  metonymy,  a crushing,  and  the  thing  crushed,)  of  suitable  quality,  is  also  capable 
of  being  converted  into  good  coke  by  a somewhat  similar  process.  If  the  slack  be  from  very  dry  coals, 
i.  e.  which  do  not  contain  much  bitumen,  it  will  not,  however,  coke  at  all ; if  the  coal  be  too  fat,  i.  e. 
with  too  much  hydrogen,  it  will  run  together  on  the  application  of  heat,  embarrass  the  circulation  of  air, 
and  yield  a small  proportion  of  a very  friable  and  inferior  article,  if  it  does  not  defeat  the  whole  opera- 
tion. Assuming  the  coals  to  be  of  suitable  quality,  it  may  be  treated  by  being  mixed  in  small  quan- 
tities, well  wetted,  in  a kiln  or  clamp  with  larger  coal.  But  the  best  method  is  to  screen  it  first,  and 
thus  separate  all  the  egg  and  nut-sized  lumps  from  the  mere  slack,  or  pure  powder.  This  last  is  mixed 
with  water  abundantly,  and  can  be  beaten  from  within  against  a wooden  mould  or  shroud.  Provision 
must  be  made  by  laying  smooth  and  somewhat  conical  tampers  of  wood  horizontally  and  vertically 
through  the  mass,  for  air-flues.  These  tampers  are  afterwards  drawn  out,  and  some  larger  than  the 
rest,  towards  the  top,  leave  the  means  of  introducing  already  ignited  coal  to  fire  the  mass.  It  is  better 
to  fire  at  the  top  than  below. 

. Fig.  2361  will  give  an  idea  of  the  ar- 
rangements proper  for  this  method,  which, 
preserving  the  main  principle,  are  of  course 
susceptible  of  many  variations  in  detail. 

Thus  they  are  sometimes  made  circular, 
but  the  most  usual  form  is,  as  in  the  figure, 
an  elongated  prism,  50  to  60  feet  in  length, 
from  4 to  8 feet  wide  at  the  base,  and  from 
2^  to  6 feet  at  the  top,  and  3 or  4 feet  high. 

A greater  width,  up  to  15  feet,  has  been 
tried,  but  not  to  advantage.  Of  course  a 
mould  and  cores  of  the  whole  length  are 
not  necessary,  but  after  a portion  has  been 
finished  the  shrouds  and  tampers  can  be  discreetly  moved  further  on  and  the  clamp  extended.  Iron 
rings  are  indicated  at  the  end  of  the  tampers,  through  which  a lever  is  passed  to  assist  in  their  removal. 
The  quantity  and  quality  of  coke  made,  due  care  being  taken  in  the  process,  is  in  proportion  to  the 
quality  of  the  coal,  and  about  80  per  cent,  of  the  quantity  yielded  from  the  same  slack  in  ovens.  A 
clamp  of  the  size  mentioned  will  take  about  ten  days  to  coke  and  cool.  It  is  better,  on  divers  accounts, 
to  leave  it  to  cool,  rather  than  extinguish  it  by  cold  affusions. 

Fig.  2362  is  an  elevation  and  plan  of  two  ovens  of  a series,  especially  applied  to  the  coking  of  slack, 
but  also  capable  of  being  used  as  well  for  lump-coal.  It  is  supposed  that  the  sketch  makes  it  quite 
intelligible,  without  further  description.  Tire  doors  at  each  end  render  the  emptying  of  the  oven  very- 
convenient.  The  average  dimensions  are  about  16  feet  long,  8 feet  wide,  and  4 feet  high  to  the  arch 
The  diameter  of  the  chimney  (which  is  generally  a cylinder  of  a single  brick,  or  refractory  pottery)  is 
ordinarily  16  inches.  The  hearth  and  arches  are  best  made  of  fire-brick.  The  foundation  of  the  heartk 
may  be  of  stone  or  common  brick,  with  a filling  of  a foot  at  least  of  sand  or  furnace-cinder  interposed 
between  it  and  the  floor  of  the  hearth  proper  Such  an  oven  will  hold  from  10  to  12  tons,  and  the 


2300. 


rnmmm&m 


94 


IRON. 


coking,  including  cooling,  is  done  in  from  40  to  50  hours.  It  is  not  well  to  let  it  cool  too  long,  or  to  such 
a degree  that  the  slack  will  not  be  speedily  ignited  on  contact  with  the  hearth.  In  this  respect,  the 
oven,  like  a common  bake-oven,  works  better  for  longer  use.  The  first  yield  of  coke  from  the  cold  oven 
is  inferior  to  what  is  made  afterwards.  There  can  be  no  doubt  of  the  greater  economy  of  ovens  fo* 
slack-coal. 

Another  sort  of  oven  suitable  for  slack-coal  resembles  very  much  the  bank-ovens  for  lump-coal  that 
will  be  spoken  of  presently.  The  ground-plan  is  circular,  the  roof  slightly  arched,  the  only  mortar  used 
fire-clay.  Flues  are  carried  all  round,  communicating  at  generally  three  points  with  the  interior.  There 
is  but  one  door  tor  drawing,  and  the  filling  is  done  through  the  top ; for  greater  convenience  in  whicli, 
they  are  generally  built  against  a bank  or  sloping  ground. 


2363. 


Fig.  2363  shows  an  oven  of  a different  construction,  much  used  in  Silesia,  both  for  coking  and  also  for 
coal-tar.  For  the  former  purpose  alone  the  ash-pit  and  damper  d may  be  dispensed  with,  sufficient 
draught  being  furnished  through  the  flues//,  &c.  The  opening  in  the  section  shows  the  door  through 
which  the  fire  is  introduced,  and  which  is  afterwards  bricked  up.  The  filling  is  done  from  above  through 
the  throat,  whose  cover  c is,  after  firing,  luted  down.  The  flue  for  the  escape  of  the  tar  is  shown  at  t. 

The  oven  in  most  general  use,  both  on  the  Continent  of  Europe,  in  England,  and  in  America,  has  a 
circular  or  ovoid  ground-plan,  with  a low,  arched  roof,  to  allow  for  the  swelling  of  the  coal.  The  draught 
is  regulated  by  a damper  in  the  door,  and  sometimes  by  flues  communicating  with  the  interior ; the 
filling  is  in  part  effected  by  the  door,  and  in  part  through  the  chimney,  the  fire  applied  generally  through 
the  last.  The  backing  of  the  arch  is  filled  up  square,  and,  to  save  masonry,  the  building  is  generally 
made  against  rising  ground,  whence  they  have  the  name  of  bank-ovens. 

Fig.  2364  shows  a section  of  one  of  these  ovens,  for  holding  about  two  tons  of  coal.  In  England  they 
have  generally  more  or  less  of  a chimney, 
and  not  unfrequently  two  more  smaller 
apertures  in  the  same  axial  plane  to  assist 
the  draught.  Also,  there,  the  doors  are 
usually  of  iron,  sliding  vertically  in  a frame 
and  balanced;  in  America,  the  doorway 
is  generally  bricked  up,  and  as  this  is  al- 
ways but  temporary  masonry,  in  such  case 
iron  staples  are  let  in  on  each  side  for  re- 
ceiving a bar  that  may  resist  the  thrust 
from  within  of  the  expanding  coal  against 
the  brick-work.  For  economy  of  building 
and  heat,  several  ovens  are  generally  ranged  in  one  stack. 

One  of  the  most  simple  and  at  the  same  time  serviceable  forms  of  oven  is  that  employed  at.  Newcastle 
and  its  neighborhood,  which  serves  equally  for  lump  or  for  slack  coal.  It  wa9  devised,  indeed,  princi- 
pally in  the  view  of  economizing  the  last.  The  ground-plan  of  these  ovens  is  rectangular,  13  feet  by 
10  or  11  feet,  covered  with  a low  elliptical  arch,  (a  parabolic  one  would  be  better,)  whose  crown  is 
about  five  feet  above  the  hearth,  clear  inside  measurement.  They  have  but  one  door,  sliding  in  a close 
foint,  as  before  mentioned,  about  2 feet  high  and  l-J  wide,  with  a register-door  in  its  centre  of  3 inches 
square  for  admitting  or  shutting  off  the  air.  The  draught  is  further  managed  by  three  chimneys  in  the 
arch,  the  main  one,  of  about  1 foot  square,  in  the  middle,  the  others,  about  4 inches  square,  at  equal 
distances  from  the  central  one.  This  last  has,  as  usual,  a cast-iron  cover;  the  others  are  closed  with  a 
brick.  The  coke  from  these  ovens  is  supposed  to  be  verv  good. 

In  regard  to  the  advantages  of  the  two  methods  of  coking,  in  the  open  air  or  in  ovens,  it  may  be  said 
that  there  is  less  loss  and  less  labor  of  attendance  with  ovens,  but  more  skill  is  required  in  managing 


2364. 


IRON. 


95 


the  temperature.  Thus,  for  instance,  if  the  heat  is  got  up  too  quick,  (as  it  is  very  apt  to  be,)  the  coko 
with  fat  coals  is  spoiled  by  burning  out  too  swoln,  light,  and  friable ; with  dry  coals,  it  burns  up  and 
causes  loss.  Also,  ovens  yield,  on  an  average,  about  10  per  cent,  more  coke,  but  generally  of  less  spe- 
cific gravity  and  more  friable.  Whether  less  care  is  taken  in  the  selection  of  the  coal  for  ovens,  as  is 
probable,  it  is  certain  that  the  almost  universal  experience  of  iron-masters  is  in  favor  of  coke  made  in 
the  open  air  on  the  score  of  useful  effect.  Again,  the  yield  from  ovens  is  more  uniform,  and  less  subject 
to  accidental  discounts.  Besides,  ovens  allow  more  readily  the  use  of  slack  or  refuse  coal,  to  produce 
an  article  of  the  same  value.  The  oven- coke,  then,  charged,  too,  with  the  greater  labor  required  in 
drawing  and  the  higher  average  wages  of  the  cokers,  is  the  cheaper  in  actual  outlay ; but  its  final 
cheapness,  in  which  the  quality  of  the  product  is  an  element,  because  of  the  varying  degrees  of  its  infe- 
riority, which  depend  too  much  upon  the  constitution  of  the  coal  used  in  different  places,  hardly  allow- 
ing a satisfactory  comparison.  Coke  made  in  retorts  is  undoubtedly  the  cheapest  of  all,  but  its  quality 
unfits  it  for  use  in  the  smelting  of  iron. 

So  great  an  effect  has  the  physical  constitution  of  the  coal  upon  the  coke  produced,  that  experience 
shows  the  quantity  of  coke  ranges  in  different  places  from  45  to  90  per  cent,  of  the  original  weight  of 
coal  employed.  About  fths  of  coke  would  be,  most  likely,  a fair  average  of  all  known  results  on  the 
large  scale.  Experiments  made  in  small,  or  calculations  upon  the  chemical  analysis  of  coals,  are  no 
further  admissible  or  of  use,  in  this  respect,  than  to  stimulate  the  manufacturer  to  an  investigation  and 
economization  of  his  actual  results. 

Regard  being  had  to  volume  yielded,  most  coals  expand  in  coking ; some  are  unaltered,  and  some, 
even  where  a large  proportion  of  earthy  matter  is  principally  aluminous,  shrink.  The  resulting  volume 
with  the  swelling  coals  is  nearly,  but  not  quite,  nor  always,  -in  proportion  to  the  loss  of  weight.  Thus, 
Johnson,  in  his  report  to  the  Navy  Department  of  the  United  States,  in  1843,  states,  for  a specimen 
of  coal  from  Allegany  County,  Maryland— 

Loss  in  weight,  per  cent.;  gain  in  bulk,  per  cent. 

The  physical  properties  of  this  coal  are  stated  by  the  same  observer  as  under : — 

Weight  of  a cubic  foot.  Per  centage  of 

Sp.  gi-av.  Calculation.  Experiment.  Volatile  matter.  Carbon.  Earthy  matter. 

1-337  83-3  lbs.  54'3  lbs.  12-67  74-53  10-34 

The  water  and  loss  on  the  analysis  appear  to  have  been  2’46  per  cent.,  and  the  proportions  of  the 
ingredients  in  the  earthy  matter  is  not  stated. 

No  average  increase  of  volume  can  be  taken,  in  the  present  state  of  our  information,  to  be  of  any  prac- 
tical utility  ; for,  1st,  the  result  depends  so  much  upon  the  methods  employed ; and,  2d,  it  is  not  the  ag- 
gregate of  the  volatile  matters  which  determines  the  expansion,  but  chiefly  the  proportion  of  oxygen  and 
hydrogen  to  one  another,  and  also  to  the  earthy  matters  present.  In  regard  to  the  first  point,  Berthier 
has  shown  the  proportions  of  volatile  matters  existing  in  coke  prepared  on  a large  scale  for  blast- 
furnaces, to  vary  from  2-A-  to  18  per  cent.;  in  regard  to  the  last,  while  analysis  alone  could  satisfactorily 
determine  it,  yet  for  the  practical  purposes  of  the  manufacturer  it  may  be  borne  in  mind  that  in  general 
great  lustre,  but  deficient  hardness  and  elasticity,  indicate  the  presence  of  hydrogen,  (the  element  pro- 
moting fusibility,)  while  great  lustre,  with  an  intensely  black  color  and  much  hardness,  show  a predom- 
inance of  oxygen,  associated  with  a large  proportion  of  carbon.  These  last-mentioned  indications, 
assuming  the  earthy  matter  in  constant  proportion,  characterize  the  class  of  dry  coals,  which  may  be, 
with  more  or  less  advantage,  employed  raw  in  the  smelting  of  iron,  In  general,  it  may  be  added,  that 
coals  containing  more  than  20  per  cent,  of  volatile  matter  cannot  be  expected,  prima  facie,  to  be  advan- 
tageously used  in  the  furnace,  either  hot  or  cold  blast,  without  coking. 

From  what  has  been  said,  it  is  obvious  that  the  final  efficiency  of  any  coke  must  depend  on  its  ulti- 
mate constitution.  Thus  the  coke  of  Luxemburg,  just  now  mentioned,  with  its  18  per  cent,  of  volatile 
matter,  is  substantially  but  dry  coals.  The  average  composition  of  good  coke  may  be  repre- 
sented as  of 

Carbon 82  per  cent 

Earthy  matters 15  do. 

Volatile  matters 3 do 

It  is  also  obvious  that  the  earthy  matters  in  coke  answer  no  useful  purpose  in  smelting — they  are  only 
absorbents  of  heat.  In  proportion  to  their  occurrence,  therefore,  they  embarrass  the  operations  of  the 
furnace.  It  is  difficult  to  fix  a limit  to  which  there  will  not  be  individual  exceptions ; but  in  general, 
coke  containing  more  than  15  per  cent,  of  ashes  is  not  fit  for  the  iron-master’s  use.  Karsten  places  the 
excluding  proportion  far  lower  than  this. 

The  absolute  or  relative  efficiency  of  coke,  then,  can  only  be  determined  upon  analysis ; and  external 
characters  by  no  means  give  a conclusive  result,  though  they  are  often  valuable  as  an  approximation. 
Good  coke  may  be  inferred  from  its  not  having  undergone  great  alteration  of  volume , or  change  of  shape ; 
from  its  color , an  iron-gray,  or  more  nearly  that  of  graphite ; from  its  lustre , more  silky  than  metallic; 
from  much  hardness,  elasticity,  and  resistance  to  impact ; from  a uniform  fracture;  from  a texture  more 
fibrous  than  compact,  and  which  imparts  a peculiar  sonorousness  to  a mass  when  struck ; and,  finally 
from  a specific  gravity  which  should,  if  any  thing,  somewhat  exceed  that  of  water. 

These  details  upon  fuel  may  be  concluded  with  the  following  table,  showing  the  probable  consump 
tion  of  fuel  per  100  of  crude  non  produced  with  ores  of  different  sorts 


96 


IRON. 


Denomination. 

Per  centage  of 
Metal  in  Ore. 

Per  centage  of  Fuel  consumed. 

Charcoal. 

Coke. 

Fusible  ores,  (Class  4,  in  part,  and  5,) 

25  @ 30 

66  @ 90 

no®  150 

do.  

30  “ 35 

90  “ 110 

150  “ 180 

do.  

35  “ 40 

110  “ 130 

180  “ 220 

Ores  of  mean  fusibility,  (mixed  mines,) 

30  “ 40 

110  “ 140 

180  “ 240 

do.  do.  

140  “ 180 

240  “ 300 

do.  do.  

50  “ CO 

180  “ 210 

300  “ 360 

Refractory  ores,  (Class  2,  3,  and  part  of  4,) 

30  “ 40 

160  “ 200 

275  “ 350 

do.  do 

40  “ 50 

200  “ 250 

350  “ 400 

do.  do 

50  “ 60 

250  “ 300 

400  “ 500 

Anthracite  lias  been  omitted  in  the  discussion  of  fuels,  mainly  to  save  room,  and  also  because,  in  one 
aspect,  it  may  be  considered  as  coming  under  the  category  of  coals  capable  of  being  used  raw  in  fur 
naces ; whose  employment,  (whether  bituminous  or  anthracite,)  however  interesting  to  particular  dis- 
tricts, has  not  yet  received  actual  extension  enough  to  be  treated  on  the  ground  of  uniform  or  average 
experience.  In  another  aspect,  it  may  be  regarded  as  belonging  to  the  class  of  hard-coked  coals,  whose 
constitution  its  own  very  much  resembles,  as  will  appear  from  the  following  average,  viz. : 

Carbon  88’7  per  cent. 

Earthy  matters  7 A “ 

Volatile  matters 3'9  “ 

It  is  on  the  respective  proportions  of  the  ingredients  in  these  earthy  and  volatile  matters  that  its 
treatment  and  behavior  depend ; the  principles  of  calculation  must  be  precisely  the  same  as  those 
which  govern  in  the  case  of  average  coke,  and  the  results  accordant. 

2.  Ores,  and  thtir  preparation. — The  methods  of  extraction,  or  mining,  practised  for  different  ores, 
according  to  differing  circumstances  of  position  and  association ; of  picking,  (Fr.  triage ,)  washing,  and 
stamping, — processes  used  according  to  circumstances  for  separating  the  ore  proper  from  a more  or 
less  indurated  gangue,  and  cleaning  it, — will  not  be  considered  here ; according  to  the  distribution  prac- 
tised in  extensive  iron-works,  at  least,  the  ores  do  not  come  properly  under  the  hand  of  the  furnace- 
manager  until  the  last  of  these  processes  is  achieved;  and  they  belong,  therefore,  to  the  article  Mining, 
which  see. 

The  roasting  of  the  ore  is  the  beginning  of  the  furnace  processes.  The  objects  of  this  are  to  diminish 
the  aggregation  of  the  mass,  and  thus  leave  more  room  for  other  chemical  affinities  to  act,  and  for  new 
combinations  to  take  place;  to  drive  off  such  impurities  and  admixtures  (water,  carbonic  acid,  and  sul- 
phur, principally)  as  can  be  volatilized  at  a red  heat;  and,  as  some  suppose,  to  present  the  mine  in  a 
higher  state  of  oxidation.  The  methods  followed  should  be  in  subordination  to  these  aims. 

In  point  of  fact,  all  of  them  are  partly  answered  with  many  ores  by  continued  exposure  to  the  at- 
mosphere, under  which  a spontaneous  disintegration  takes  place,  together  with  a partial  absorption  of 
impurities  and  a peroxidation.  But  with  some  ores,  these  effects  are  not  manifested  till  after  a long 
period,  (as,  for  example,  with  magnetic  and  specular  oxides.)  and  with  all  they  are  vastly  accelerated 
by  a due  application  of  heat.  It  may  even  be  said  that  all  ores  are  the  better  for  being  roasted  and 
then  exposed  for  as  long  a time  as  convenient  to  the  macerating  influence  of  the  atmosphere.  The  red 
hematites  of  Lancashire  are  hardly  an  exception  to  this ; for,  though  used  habitually  raw,  it  is  only  for 
intermixture  with  other  ores,  and  in  small  quantity ; while  the  custom,  in  some  districts,  of  only  weath- 
ering the  sparry  carbonates,  which  are  afterwards  used  unmixed,  arises  only  from  the  difficulty  of  so 
managing  the  heat  as  to  roast  and  not  fuse  them. 

This  management  of  temperature  is  more  or  less  necessary  with  all  ores.  Thus,  magnetic  and  red 
oxides,  quartzose  sparry  carbonates,  argillaceous  carbonates  containing  a suitable  proportion  of  silica, 
and  generally  all  the  silieated  ores,  are  easily  vitrifiable.  As  a general  rule,  the  roasting  should  be  as 
prolonged  and  at  as  low  a temperature  as  possible,  with  free  access  of  air  and  moisture. 

The  roasting  may  be  done  in  kilns,  or  chimps,  or  ovens.  The  first  is  the  most  simple  of  all  and  the 
most  extensively  practised.  The  shape  of  the  kiln  is  indifferent;  it  is  sometimes  conical,  sometimes  a 
square  or  rectangular  pyramid.  Its  size  is  equally  indifferent.  The  whole  method  consists  in  inter- 
stratifying  the  or1-  and  fuel,  (in  an  average  proportion  of  about  five  of  the  former  to  one  of  the  latter,) 
from  the  base,  wheu  here  is  a sufficient  accumulation  of  combustible,  and  certain  rudely  made  flues 
or  prolonged  cavities,  to  insure  the  fire  taking  throughout.  The  smaller  pieces  of  ore  are  put  outside 
as  a cover,  and  ashes  and  cinders,  coal,  coke,  or  charcoal  dust,  or  loam,  used  afterwards,  where  neces- 
sary, as  a stopper  or  damper  of  the  fire.  After  piling  and  starting  the  fire,  it  is.  in  good  weather,  only 
looked  at  from  time  to  time.  In  most  of  the  English,  Welch,  and  Scottish  furnaces,  as  well  as  at 
many  in  America,  they  appear  to  overlook  the  importance  of  keeping  a large  stock  of  roasted  mine 
ahead,  so  as  to  give  it  the  further  benefit  of  atmospheric  exposure. 

Clamps  are,  in  principle,  very  much  the  same  with  those  already  described  for  making  charcoal. 
Three  sides  of  a parallelogram,  of  width  and  length  indefinite,  are  built  round  with  a dry  wall  in  stone, 
having  draught-holes  left  at  intervals  of  five  or  six  feet  in  the  base,  and  carried  up  to  about  three  feet 
in  height.  Chimneys  are  built  loosely,  of  brick  or  stone,  along  the  middle  of  the  clamp,  and  corres- 
ponding with  each  one  (or,  sometimes,  two)  of  the  flues.  The  fuel  is  laid,  in  the  beginning,  at  the 
bottom,  and  is  more  or  less  iuterstratifled  with  the  pile  of  ore  according  to  the  greater  or  less  presumed 
fusibility  of  this  last.  Sometimes  there  is  no  interstratification  at  all,  but  fuel  is  supplied  as  wanted  to 
the  draught-holes  in  the  base. 


IRON. 


97 


Tho  ovens  used  are  of  almost  infinite  variety  in  shape  and  dimensions.  Their  general  types  are  a 
cylinder,  an  inverted  cone,  or  a combination  of  an  inverted  and  a right  cone,  and  a truncated  ellipsoid; 
they  vary  from  6 to  18  feet  in  height,  with  an  average  diameter  of  8 feet  at  the  grate  and  of  5 to  10 
feet  at  the  trundle-head.  They  are  like  Ihne-kUus,  either  perpetual  or  periodic;  and,  in  fact,  the  de- 
scription of  a lime-kiln  is  also  that  of  a roasting  oven.  The  temperature  to  be  maintained  in  the  last 
is  lower  than  in  the  other.  Itcvcrberalory  ovens  have  been  tried,  but  unsatisfactorily,  for  the  roasting 
of  ores. 

It  is  to  be  supposed  that  the  larger  the  oven,  the  more  regular  and  economical  will  be  the  work.  For 
refractory  ores,  the  oval  shape  is,  perhaps,  the  best ; while  the  more  simple  cone  or  cylinder  is  better 
suited  to  fusible  ores.  Ores  generally  pass,  with  but  short  (if  any)  interval,  (and  in  so  far  disadvanta- 
geously,)  from  the  ovens.to  the  top-house,  where  they  are  broken  up,  and  immediately  charged  into  the 
furnace. 

This  breaking  is  effected  upon  a stone  or  (better)  a cast-iron  floor,  sometimes  with  a beetle,  one  or 
two  handed ; sometimes  with  iron-shod  stampers,  moved  by  machinery  ; sometimes  the  mine  is  crushed 
between  fluted  cylinders  made  to  revolve.  But  the  best  of  all  methods  is  to  break  by  hand  with  an 
ordinary  stone-hammer. 

The  size  to  which  the  mines  should  be  reduced  before  charging  ought  to  vaiy  directly  with  the  hard- 
ness of  the  ore  and  the  height  of  the  furnace.  From  one  to  three  inches,  average  diameter,  inside,  will 
be  the  limits.  Larger  than  the  one,  they  leave  too  much  to  be  done  in  the  furnace ; smaller  than  the 
other,  they  embarrass  the  blast. 

3.  Fluxes. — The  reducing  effect  of  the  carbon  of  the  fuel  upon  the  metallic  oxides  in  the  high-furnace 
has  been  already  spoken  of,  as  well  as  that  of  the  potassa  and  soda  contained  in  the  earthy  matter  of 
charcoal ; but  these  are  rarely  sufficient,  with  most  mines,  to  cause  at  once  fusion  and  reduction  ; and 
it  becomes  necessary,  then,  to  add  other  matters,  sterile  in  metal,  to  promote  fusion  : these  are  known 
as  Jinxes.  Silica,  indeed,  which  is  a constant  association  in  all  ores  of  iron,  is,  of  itself,  a sufficient  flux 
in  some  cases ; but,  even  in  those,  it  is  more  apt  to  be  in  excess,  when  it  both  embarrasses  the  working 
of  the  furnace  and  impairs  the  quality  of  the  metal.  It  would  be  proper,  then,  to  neutralize  this  excess 
by  the  addition  of  some  other  substance ; and  such  addition  becomes  still  more  proper  when  (the  prac- 
tical problem  in  the  furnace  being  to  effect  fusion  at  the  lowest  possible  temperature ) both  theory  and 
experiment  show  that  it  not  only  cures  such  excess,  but  also  promotes  fusibihty.  In  fact,  we  know 
that  while  of  each  of  the  earthy  bases  most  ordinarily  accessible,  viz.,  silica,  lime,  magnesia,  and  alumina, 
is  almost  (and  one  of  them  entirely)  infusible,  per  se,  yet  in  combination,  two  and  two,  three  and  three, 
and,  still  more,  four  and  four,  they  melt  readily  at  easily  attainable  temperatures.  The  addition,  then, 
of  suitable  proportions  of  these  sterile  matters,  is  the  means  to  economical  fusion  of  the  materials  in  the 
furnace. 

Without  dwelling,  however,  upon  the  theory  of  their  action,  (which  has  been  explored  more  or  less 
profoundly  by  a host  of  chemists  and  metallurgists,  and  has  been  experimentally  examined  by  Achard, 
Alexander,  Berthier,  Descotils,  and  Lampadius,)  and  regarding  only  the  practical  maxims  that  fit  the 
question,  it  may  be  said  that  in  addition  to  the  silica  and  alumina,  always  present  in  the  ores  and  fuel, 
and  to  the  lime,  magnesia,  manganese,  and  potassa,  sometimes  present,  too,  the  positive  flux  most  usu- 
ally added  is  lime,  in  the  form  of  marine  shells,  limestone,  or  chalk.  The  proportion  of  this  addition 
varies  in  almost  every  case  ; but,  at  a mean,  it  may  be  taken,  for  charcoal  furnaces,  at  one-fourteenth  of 
the  other  solid  materials  by  weight;  and  at  one-eighth,  for  coke  furnaces. 

Although  lime  is  the  flux  thus  almost  universally  employed,  it  is  not  always  the  one  that  best  suits 
the  case.  With  an  excess  of  silica,  it  is  the  proper  one.  But  when  the  ores  are  themselves  calcareous 
in  any  considerable  degree,  the  best  addition  is  of  aluminous  or  magnesian  earth,  or  both.  In  some 
cases,  where  the  ores  and  fuel  are  highly  aluminous,  the  addition  required  (though  with  great  caution) 
is  silica,  in  the  shape  of  quartz,  itc.  In  such  cases,  the  best  avail  has  been  taken  of  siliceous  matter 
containing  also  a low  proportion  of  iron.  It  is  thus  that  amphibole,  basalt,  and  garnet  have  been  ap- 
plied. This  is,  in  fact,  the  use  of  a poor  material  instead  of  one  utterly  sterile. 

In  general,  it  may  be  estimated,  that  of  the  whole  solid  materials  introduced  into  the  furnace,  (tire 
metallic  iron  excepted,)  the 

Silica  may  range  from  45  to  60  per  100. 

Lime  “ 20  to  35  “ 

Alumina  “ 12  to  15  “ 

Magnesia  “ 12  to  25  “ 

Oxide  of  manganese  15  to  20  “ 

If  all  four  first  named  are  present  together  at  once,  the  most  fusible  proportions  in  which  they  can 
exist  (without  regard  to  the  fluxing  action  of  metallic  oxides  that  may  be  there  too)  are, 

Silica  35’2  per  100.  j Lime 19T  per  100. 

The  solid  material  of  the  fluxes  should  be,  like  the  ores,  broken  up  into  fragments  of  similar  and  uni 
form  size.  When  oyster-shells  are  used,  it  is  not  necessary  to  treat  them  further  than  by  a slight  pre- 
vious calcination.  They  do  not  always  receive  that. 

The  artificial  fluxes,  (such  as  salt,  potash,  saltpetre,  &c.,)  either  singly  or  in  combination  with  alkaline 
earths,  which  have  been  suggested  at  various  times  in  the  last  twenty  years,  do  not  appear  to  have  met 
with  as  much  practical  success  as  the  theories  of  those  who  recommended  them  seemed  to  warrant.  It 
is  probable  that  this  will  be  always  the  result ; owing  not  so  much  to  mistake  in  the  principle  as  to  a 
difficulty,  inherent  in  the  blast-furnace,  of  applying  these  highly  fusible  and  reducing  agents  just  at  the 
point  where  they  are  wanted. 

4.  Gaseous  material — atmospheric  air. — The  remaining  material  in  blast-furnaces,  besides  those  tha 
have  been  considered,  is  the  atmospheric  air,  which  is  regularly  blown  in  to  keep  up  the  combustion. 

Vol.  II. — 7 


IRON. 


y* 


It  is,  therefore,  in  this  aspect,  one  of  the  most  important  to  be  duly  managed ; and  when  the  enormous 
quantities  of  it  that  are  required  are  taken  into  view,  its  probable  influence  and  collateral  effect  can  be 
still  better  appreciated.  The  following  average  statement  may  be  derived  from  the  practice  in  this 
particular. 

Charcoal  Furnaces.  Coke  Furnaces. 

Solid.  Gaseous,  Solid.  Gaseous. 

Volume  of  materials,  in  cubic  feet,  per  minute  0 295  900'  1'06  3000. 

do.  proportionate I1  3050'  1'  2830- 

Weight  of  materials,  in  lbs.,  per  minute 24-82  15'  102-12  269- 

do.  proportionate 1-  3-022  1-  2'634. 

Taking  the  mean  of  the  proportional  quantities,  it  appears  that,  in  round  numbers,  the  vci'jr.ie  of  the 
air  injected  is  3000  times  larger  than  that  of  all  the  solid  materials  in  any  given  time  ; while  its  weight 
is  three  times  greater  than  theirs.  The  elements  used  above  would  show  also  that  on  the  average  there 
is  consumed  nineteen  tons  of  air  for  one  ton  of  iron  made. 

In  order  to  illustrate  the  means  of  managing  this  vast  supply,  Fig.  2365  (a  sketch,  with  more  atten- 
tion to  distinctness  than  proportion  of  parts) 


-.  ■■■■■  ■ ^ 


shows  the  arrangements  suitable  for  a furnace 
of  the  first  class.  The  power  used  is  assumed 
to  be  steam;  though  the  method  of  its  pro- 
curement and  application  is  not  carried  further 
back  here  than  to  the  steam-cylinder  c,  worked 
horizontally  by  the  same  piston-rod  that  goes 
turough  and  works  the  cylindrical  bellows  b. 

It  is  obvious  that  other  sources  of  power,  or 
other  methods  of  geering,  may,  under  suitable 
circumstances,  be  resorted  to.  From  b,  the 
bellows,  the  air  is  driven  into  r,  the  regulator, 
whence  it  passes  into  a a , the  furnaces  for  heat- 
ing it,  and  then  transmitting  it  along  1 1 into  h, 
the  hearth  or  crucible.  T indicates  the  tymp- 

arch  as  before ; W a retaining  wall  against  the  hill-side,  and  connected  by  an  arched  bridge  above  with 
the  stack ; wdiile  the  blanks  left  in  the  piers  show  the  passage-ways  before  spoken  of,  left  for  more 
convenient  access  between  the  tuyfere  and  tymp-arches.  Such  being  the  general  arrangements,  the 
parts  and  their  requisites  will  be  spoken  of  briefly  in  order. 

Bellows,  or  blowing  machines,  have  been  constructed  of  leather,  of  wood,  of  stone,  and  of  cast-iron. 
The  first  material,  on  account  of  its  expensiveness  and  the  narrow  limits  which  it  imposed  upon  both  the 
volume  and  density  of  the  blast,  is  no  longer  used  except  for  smiths’  fires.  The  second,  whether  made 
with  hinges  or  (as  afterwards)  worked  with  a piston,  left  much  to  be  desired.  The  use  of  the  third,  in 
an  instance  or  two,  can  only  be  justified  by  necessity,  or  applauded  as  a conquest  over  circumstances: 
while  the  last,  in  the  shape  of  a double-acting  cylinder,  furnishes  the  only  satisfactory  and  sound 
means  to  the  end. 

Before  describing  these,  however,  mention  must  be  made  of  a method  on  a totally  different  principle, 
which,  under  variously  modified  forms,  is  still  employed  in  parts  of  Italy  and  the  districts  of  the  Pyrenees. 
This  is  the  trompe  or  water-blast,  of  which  Fig.  2366  shows  the  principle. 

In  this,  a vertical  tube  of  wmod  or  iron, 

cylindrical  or  prismatic,  of  length  and  23CC- 

diameter  suited  to  the  fall  and  quantity 
of  water  intended  to  be  used,  connects 
with  a cistern  below,  made  air-tight  ex- 
cept for  the  opening  t,  to  connect  with  the 
tuyere.  Through  this  tube  a stream  of 
water  is  allowed  to  fall,  drawing  in  the 
air  as  it  descends  through  openings  that 
are  indicated  by  broken  lines  in  the  sides 
of  the  column,  and  breaking  upon  an  altar 
below.  The  air  thus  carried  into  the  cis- 
tern has  no  means  of  escape  except  the 
luyfere  t,  and  its  quantity  and  pressure 
delivered  through  that  depends  upon  the 
absolute  size  of  the  column  of  water,  and 
the  proportions  of  the  various  parts.  Ven- 
turi has  already  satisfactorily  investigated 
the  relations  of  this  machine ; wdiich  will 
not  be  dwelt  on  in  that  aspect  further 
here  than  to  say,  that  although  very  cheap 
and  convenient  in  its  construction,  it  uses 
more  water  for  a given  effect  than  a 
water-wheel  would  do,  and  that  its  effec- 
tiveness is  quite  limited.  Karsten  refuses 
to  admit  that  the  dampness  of  the  blast 
it  affords,  injures  the  quality  of  the  iron ; 
although  it  is  probable  that  most  metallurgists  would  conclude,  in  the  face  of  general  theory  and  expo 
rience,  that  the  good  quality  of  iron  made  by  this  method  exists  in  spite  of  it. 


IRON. 


90 


2367 


The  chain-blower  of  Henschel  is  an  improvement  upon  this  machine.  In  it,  a more  complete  separ- 
ation of  the  air  and  water  is  effected,  by  means  of  an  endless  chain  of  floats  or  pistons,  worked  by  the 
descending  water  itself;  but  its  effect  is  not  such  as  to  take  it  out  of  the  general  category  of  objections. 

Tire  hydraulic  bellows  of  Baader  is,  in  fact,  but  a single-acting  piston  air-pump,  in  which  the  surface 
of  a reservoir  of  water  is  made  to  take  the  place  of  the  otherwise  solid  end  of  the  pump.  It  cannot  be 
made  to  furnish  blast  either  of  large  volume  or  much  density,  and  is  mentioned  here  only  because  it  is 
actually  used  with  satisfactory  effect  in  suitable  cases  ; but  it  can  only  be  recommended  in  districts 
where  water  is  plenty  and  the  labor  of  the  artisan  dear. 

The  oscillating  cylinders  of  D’ Aubuisson  are  an  extremely  ingenious  blowing-machine,  cheap  to  con 
struct,  and  worked  with  little  power  and  at  small  expense.  Although 
not  giving  a blast  of  sufficient  amount  or  density  for  the  smallest  liigh- 
furnace,  except  with  the  most  fusible  materials,  they  answer  very  well  for 
chafery  and  finery  fires.  Fig.  2367,  which  is  a section  of  one  of  the  cylin- 
ders, will  afford  an  illustration  of  their  action.  A diaphragm,  central, 
through  the  entire  length  and  nearly  the  whole  diameter,  is  shown  at  erf; 
v v are  two  valves,  alternately  aspiring  and  expiring.  In  its  normal  posi- 
tion d d is  vertical ; the  barrel  is  filled  half  full  of  water,  through  a bung, 
and  is  then  set  in  oscillation,  through  an  arc  of  90  or  100  degrees,  by  a 
connecting-rod  and  crank  geered  on  near  c.  It  is  manifest,  that  in  differ- 
ent angular  positions  of  the  diaphragm  the  content  of  water  in  the  two 
semi-cylinders  will  come  to  be  unequal,  as  shown  by  the  shaded  lines ; 
and  the  air  will  be  respectively  rarefied  and  condensed  accordingly. 

All  these  methods,  however,  imply  more  or  less  contact  of  the  air  with  water,  and  the  consequent 
immission  of  more  or  less  moisture  with  the  blast ; which  is  objectionable.  But  this  oscillating  method 
leads  to  speak  of  a rotary  method  for  delivering  dry  air — at  least,  air  of  the  ordinary  atmospheric  hu- 
midity only.  This  last  is  the  fan-blast,  in  which  fans,  radiating  from  an  axis,  are  caused  to  revolve 
rapidly  in  an  appropriate  disk,  receiving  the  air  at  the  centre  of  rotation,  and  delivering  it  on  the  cir- 
cumference into  a chest,  with  or  without  a valve.  The  volume  of  air  furnished  by  this  means  is  not, 
without  considerable  expense  in  construction  and  power,  sufficient  for  a high-furnace  of  the  first,  or  even 
of  the  second  class  ; but  the  density  that  can  be  obtained  leaves  nothing  to  desire.  For  cupolas,  re- 
fineries, &.C.,  it  is  very  convenient  and  appropriate.  It  is,  in  practice,  of  two  kinds  : one  acting  impul- 
sively, in  which  the  air  is  aspired  and  at  once  diffused  in  a common  chamber,  whence  it  is  driven  out  by 
the  fan-wheel ; the  other  centrifugally,  in  which  the  fan  itself  is  a hollow  wheel,  receiving  the  air  at 
openings  near  its  axis,  discharging  it  first,  at  openings  in  its  circumference,  into  the  chamber  or  casing, 
and  then  driving  it  out  from  said  chamber  by  fans  fixed  upon  its  own  periphery.  The  chamber  of  the 
outer  casing  is  kept  from  communicating  with  the  external  air,  as  it  is  inspired,  by  a portion  of  the 
internal  revolving  disk,  which  is  made  to  work  air-tight  as  possible  in  the  outer  casing.  Here  is  exactly 
the  embarrassment  of  the  arrangement,  which  imposes  a higher  cost  upon  the  apparatus  in  the  begin- 
ning, and  is  difficult  of  maintenance.  When  it  fails  of  being  maintained,  however,  the  machine  does 
not,  on  that  account,  lose  its  value — it  merely  passes  over  into  the  other  class. 


Fig.  2368  is  a section  of  a horizontal,  double-acting,  blowing-cylinder,  in  cast-iron ; which  may  be  taken 
as  the  type  of  a class  that  fulfils  all  desirable  conditions.  The  details,  it  is  supposed,  sufficiently  ex- 
plain themselves.  There  are  some  advantages  in  a horizontal  cylinder  rather  than  a vertical  one ; 
principally,  it  can  more  readily  secure  a good  foundation,  with  less  waste  room  from  valves,  which,  in 
the  others,  are  more  or  less  necessarily  in  the  sides.  By  carrying  the  piston-rod  through  both  heads, 
the  weight  of  the  piston  is  equalized  upon  the  collars,  and  there  is  left  but  little  risk  of  the  cylinder's 
wearing  out  of  shape. 

The  size  of  the  blowing -cylinder  depends  upon  the  volume  of  blast  wanted.  As  the  length  of  the 
stroke  is  generally  somewhat  limited  by  the  conditions  of  the  other  machinery  which  supplies  the 
moving  power  to  the  piston,  and  as  the  maximum  speed  of  the  stroke,  or  number  of  revolutions  in  a 
given  time,  is,  in  like  manner,  determined  by  general  mechanical  considerations,  it  has  been  found 
necessary,  in  practice,  to  give  these  cylinders  a large  diameter,  disproportionate  to  the  length  of  stroke 


IRON. 


LOO 


'The  blowing-cylinder  at  Dowlais,  for  instance,  (which  is  the  most  extreme  case  that  could  be  cited,)  has 
a stroke  of  10  feet  and  a diameter  of  12  feet. 

To  determine  the  volume  of  blast,  and,  consequently,  the  size  of  cylinder,  the  best  rule  is,  when  the 
constitution  of  the  materials  to  be  used  is  known,  to  allow  air  enough  to  pcroxidate  all  the  materials  in 
the  furnace  at  any  one  moment.  This  will  be  the  outside  limit.  In  ordinary  practice,  the  machinery 
will  be  worked  at  a slower  speed ; and  in  emergencies,  there  will  be  still  a margin  to  go  upon.  In 
calculating  the  supply  of  air,  it  is  to  be  remembered  that  the  best-executed  blowing  machines  do  not 
deliver  into  the  furnace  more  than  J of  their  theoretical  capacity  : it  would  be  even  safer  to  take,  as  an 
average,  J of  such  capacity  for  the  actual  supply. 

If  the  constitution  of  the  materials  is  not  known,  but  the  size  of  the  furnace  is,  and  thence  the  num- 
ber of  charges  that  it  ought  to  bear  in  a turn,  we  have  another  rule  : One  fifth  of  the  weight  in 
pounds  of  fuel  (either  charcoal  or  coke)  charged  during  one  turn  of  twelve  hours , is  the  number  of  cubit 
feet  of  air,  under  the  pressure  of  the  atmosphere , to  be  furnished  in  one  minute. 

This  allows  for  the  average  discount  on  the  working  of  the  machine,  leakage  of  pipes,  &c. ; and  gives, 
therefore,  at  once  the  capacity  of  the  cylinder. 

Regulators  are  of  two  general  classes  : 1st,  of  variable  capacity ; and,  2d,  of  constant  capacity.  Those 
of  the  first  class  are  either  dry,  or  wet,  or  (as  these  last  are  called)  water-regulators.  l)ry  regulators 
are  merely  cylindrical  air-chambers,  in  which  a piston  works  air-tight,  which  is  loaded  to  the  pressure 
desired  at  any  time.  These  cylinders  have,  of  course,  an  inlet  and  an  outlet  pipe  for  the  air,  neither  of 
which  needs  valves  : the  valves  shown  in  the  air-chest  above  the  cylinder,  in  Fig.  2368,  answer  all  the 
purpose  of  isolating  the  air  in  the  regulator  from  that  under  the  piston,  on  the  one  hand,  while,  on  the 
other,  the  blast-pipes  and  tuyeres  are  regarded  but  as  continuations  of  the  regulator.  In  fact,  in  every 
case,  long  and  large  blast-pipes  (although  density  is  lost  in  proportion  to  length)  serve,  in  a measure, 
to  assist  in  uniformity  of  blast.  The  capacity  of  these  dry  regulators  should  be,  in  theory,  twice  the 
capacity  of  the  blowing-cylinder ; in  practice,  they  will  answer  to  be  one  u:id  a half  times  as  large. 

Water-regulators  are  oblong  chests  without  a bottom,  or  receivers,  let  down  in  a tank  containing 
water,  and  balanced  after  the  manner  of  gasometers.  The  weight  of  the  chest,  and  the  additional  load 
put  upon  it,  cause  it  to  sink  ; the  influx  of  the  air,  and  its  elasticity,  cause  it  to  rise,  /is  the  air  be- 
neath the  piston  is  under  much  greater  pressure  than  in  the  regulator,  and  thus  every  stroke  of  the 
piston  causes  a slight  fluctuation,  the  capacity  of  these  regulators  (whose  minimum  is  the  same  as  in 
the  former  kind)  is  generally  governed  by  other  considerations,  and  made  as  great  as  convenient.  The 
adjutages  and  pipes  for  receiving  and  discharging  the  blast  are,  in  practice,  very  much  varied  in  po- 
sition, &c. ; but  the  general  principles  of  their  arrangement  are  too  obvious  to  require  description  here. 
Very  convenient  and  suitable  in  most  regards,  this  kind  of  regulators  is  liable  to  all  the  objections  ac 
cruing  from  access  of  moisture. 

The  second  great  class  comprehends  air-chambers  of  constant  capacity.  These,  which  long  ago  were 
built  under  or  above  ground  in  masonry,  or  for  which  even  subterranean  caverns,  sedulously  rendered 
air-tight,  were  resorted  to,  have,  in  the  most  modern  times,  come  up  again,  (as  in  Wales,)  only  in  a 
material  more  suitable  and  manageable.  Sheet-iron  is  now  most  generally  resorted  to ; strengthened, 
when  thought  necessary,  with  ties.  Their  form  is  generally  cylindrical  or  spherical ; one  of  the  latter 
shape  exists  with  the  enormous  diameter  of  25  J feet.  The  most  convenient  form  appears  to  be  that  of 
a right  cylinder,  of  thin  sheet-iron ; with  a base  solidly  supported,  and  a head,  either  of  cast-iron  or 
sheet-iron,  stiffened  with  wood,  carrying  a safety-valve,  (which  acts  here  also  as  an  equalizer  of  pres- 
sure,) and  admitting  of  an  aperture,  large  enough  for  the  entrance  of  a workman,  and  capable  of  being 
closed  air-tight. 

Of  course,  the  larger  such  a chamber  is,  the  less  will  it  feel  the  pulsations  of  the  piston  ; but  there 
must  be  an  economical  limit  in  this  respect.  In  practice,  the  regulator  is  made  from  nine  to  fifteen 
times  as  large  as  the  blowing-cylinder ; in  theory,  its  least  capacity,  to  furnish  a uniform  discharge, 
should  be  in  the  same  proportion  to  the  blowing-cylinder  as  the  pressure  of  one  atmosphere  is  to  the 
pressure  desired  to  be  maintained.  Thus,  if  the  pressure  be  assumed  at  2 lbs.  per  square  inch,  the  reg- 
ulator must  be  at  least  V5  or  7 J times  the  size  of  the  blowing-cylinder. 

From  the  regulator  the  blast-pipes  were  traced,  in  Fig.  2365,  to  the  hot-air  furnaces ; but  the  consid- 
erations belonging  to  these  will  be  postponed  for  a moment,  and  the  furnace  considered  as  working  (as 
all  did,  in  fact,  until  1827,  the  epoch  of  Mr.  Neilson’s  improvement,  and  as  many  prefer  to  do  still) 
with  cold-blast.  What  remains  to  he  spoken  of  in  advance  is  the  blast-pipes  and  nozzles  ; the  water- 
tuydres,  which  are  indispensable  with  hot  air,  and  advantageous  with  cold-blast,  have  been  already 
mentioned. 

Blast-pipes  are  made  of  sheet  or  cast  iron ; for  first-class  furnaces,  where  the  pressure  is  required  to 
be  considerable,  generally  of  the  last-named  material.  As  they  cannot  be  made  in  one  piece,  they  are 
jointed  either  by  flanges  or  by  a muff,  (what  is  called  the  faucet  aud  spigot  joint,)  as  in  gas  and  water 
pipes.  When  cold  air  is  employed,  the  packing  of  the  joints  is  lead;  with  hot  air,  an  iron  cement  must 
be  used.  This  cement  is  made  of  99  parts  of  iron  filings,  sifted  fine,  and  1 part  of  powdered  sal  am- 
noniac,  intimately  mixed,  dry.  When  used,  as  much  water  is  added  as  will  make  a stiff  paste.  Flow- 
ers of  sulphur,  sometimes  recommended,  in  no  way  contributes  to  the  efficiency  of  the  mixture,  but 
rather  to  the  contrary. 

The  pipes  are  sometimes  laid  under  ground  and  covered  over ; hut  this  mode  is  not  to  be  recom- 
mended ; they  should  be  always  accessible.  If  hot  air  is  ever  expected  to  be  used,  provision  should 
be  made  in  the  laying  for  expansion  and  contraction  by  resting  them  upon  rollers,  (short  pieces  of 
three-inch  iron  pipe  answer  very  well,)  on  a smooth  foundation.  It  is  impossible,  in  the  conditions  of 
application,  to  avoid  flexures  ; but  these  flexures  should,  of  course,  to  save  friction,  be  made  as  gentle 
as  possible. 

When  the  straight  lengths  are  so  great  that  there  appears  to  be  danger  that  the  pipe  will  break,  a 


IRON. 


101 


compensation-joint  is  inserted  ; this  frequently  consists  of  an  end  of 
a pipe  movable  in  a stuffing  box.  The  plan  represented  in  fig, 
2371  is  preferable  to  it.  This  is  a compensation-joint,  consisting  of 
two  round  dishes  of  sheet-iron,  or  copper,  20  or  30  inches  in  diam- 
eter, according  to  the  size  of  the  pipe,  riveted  air-tight  at  their 
periphery,  and  screwed  to  the  two  flanges  of  joining  pipes.  The 
sheet  iron  may  be  from  ^ to  of  an  inch  thick.  The  large  diam- 
eter and  flexibility  of  the  sheet-iron  allow  the  two  pipes  which  arc 
joined  to  it,  to  move  longitudinally,  independent  of  each  other. 
Wooden  blast  pipes  are  sometimes  used,  but  are  useless  where  a dense 
blast  is  to  be  conducted. 

The  capacity  of  the  pipes,  i.  e.  their  diameter,  should,  other  things  being  equal,  be  as  large  as  possible. 
But,  as  other  things  (to  wit,  the  expense)  are  not  equal,  they  should  be  proportioned  to  the  quantity  of 
blast  to  be  delivered.  A reasonable  unit  may  be  taken,  in  allowing  a nine-inch  pipe  to  1000  cubic  feet 
of  blast  per  minute.  Then,  as  the  quantities  vary  with  the  squares  of  the  diameters,  4000  cubic  feet 
per  minute  will  be  accommodated  by  pipes  of  eighteen  inches. 

Whether  the  pipes  are  laid  under  or  on  the  ground,  the  level  of  the  tuybre  will  still  be  above  them ; 
two  elbows,  therefore,  are  necessary  to  bring  the  nozzle  into  the  tuydre.  The  junction  of  these  elbow- 
pieces  should  be  always  with  a ball  and  socket  joint  for  giving  play  tc  the  nozzle.  With  cold-blast, 
this  play  can  be,  and  frequently  is,  attained  upon  fixed  elbows,  by  connecting  the  nozzle  and  the  blast 
pipe  proper  with  a leather  hose  or  bag ; with  hot-blast,  the  leather  is  inadmissible. 

Various  forms,  of  more  or  less  complexity,  are  used  in  and  about  the  termination  of  the  pipes  for 
shutting  off  the  blast  entirely  (as  has  to  be  done  at  every  run-out)  or  partially,  measuring  its  intensity, 
<tc.  Pig.  2372  shows  one  of  the  most  simple  and  satisfactory.  The  ball  and  socket  and  fixed  elbow 


ioints  are  both  seen.  At  v is  a trundle-valve  of  sheet-iron,  elliptical  in  shape,  with  alternately  bevelled 
edges,  and  worked  by  the  winch  above.  When  this  winch  is  parallel  with  the  axis  of  the  pipe,  the 
valve  presents  nothing  but  its  thickness  to  the  blast ; when  it  is  at  right  angles  to  the  axis,  it  shuts  up 
the  pipe  entirely,  and  with  a tightness  proportionate  to  the  accuracy  of  its  fitting.  It  can  be  made  (so 
to  speak)  perfectly  tight.  Some  furnace-managers  have  a plate-collar  fastened  beneath  the  winch, 
divided  angularly  on  its  circumference,  and  read  by  an  index  that  moves  with  the  winch,  to  show  either 
the  absolute  or  relative  quantities  of  blast  in  the  different  positions  of  the  winch-handle.  At  e is  an  eye- 
let, closed  ordinarily  with  a conical  iron  plug,  as  shown.  When  this  plug  is  out  it  allows  the  founder 
to  look  into  the  hearth  and  observe  the  aspect  of  the  tuyere.  With  hot  air,  this  has  to  be  used  dis- 
creetly. Between  the  valve  and  the  elbow,  somewhere  about  m,  is  placed  (with  cold-blast)  the  ma- 
nometer or  pressure- meter  of  the  blast.  Fig.  2373  shows  a section  of  the  pipe  with  the  apparatus  at- 
tached ; which  is  only  a glass  tube,  | inch  bore,  containing  a few  inches  of  quicksilver,  and  open  at  both 
ends.  When  there  is  no  pressure  from  within,  as  when  the  blowing-machine  is  at  rest  or  the  blast  shut 
off,  the  mercury  stands,  of  course,  at  the  same  level  in  the  two  branches  of  the  tube ; when  there  is 
pressure,  the  column  in  the  long  arm  rises,  at  the  rate  of  1 inch  in  height  for  every  lb.  of  pressure. 
The  best  scale  to  put  on  it  is  a piece  of  card,  divided  in  equal  parts,  sliding  up  and  down  by  friction, 
and  capable  at  any  moment,  by  shutting  of  the  valve,  of  proper  adjustment.  With  hot-blast,  the  ma- 
nometer has  to  be  placed  in  the  regulator.  Otherwise  the  actual  density  of  the  air  is  more  accurately 
measured  as  near  as  possible  to  the  nozzle. 

These  nozzles  or  adjutages  are  conical  sheet-iron  tubes,  made  to  fit  as  tight  as  possible  upon  the  cy- 
lindrical blast-pipe,  and  tapering  off  to  an  orifice  from  1 to  5 inches,  in  diameter.  Furnace-managers  do 
not  generally  trouble  themselves  much  about  the  laws  of  pneumatics,  and  hence  we  find  a great  variety 
in  the  shape  and  proportions  of  these  utensils.  Several  of  them  are  provided  of  larger  and  smaller 
orifices,  to  be  used  as  circumstances  require.  Ordinarily  they  are  in  two  joints,  of  which  the  one  fitted 
to  the  blast-pipe  is  the  more  permanent.  The  elliptical  shape  of  the  orifice  sometimes  found,  is  a dis- 
advantage, as  well  as  the  great  length  of  the  cone ; both  lessen  the  discharge  that  would  follow  a shorter 
and  more  acute  cone.  The  following  table  (which  is  strictly  accurate  under  the  conditions  for  which  it 
was  calculated)  is  sufficiently  so  to  be  relied  on  for  giving  the  discharge  of  blast  into  a furnace  in  any 
case  likely  to  occur,  the  pressure  being  that  in  the  regulator,  and  the  diameter  of  nozzle  being  measured 
at  the  extreme  point  of  discharge. 

A table  like  this  is  indispensable  to  a furnace-manager  who  wishes  to  be  cognizant  of  what  is  going 
on  in  the  furnace,  in  connection  with  changes,  accidental  or  designed,  in  the  blast.  Its  application  in 
the  present  shape  is  both  direct  and  inverse,  and  in  either  method  is  very  simple.  Thus,  having  ascer- 
tained the  actual  pressure  of  the  blast  to  be,  say  1-J  lbs.,  while  we  are  using  a nozzle  of  2 inches ; if  we 
wish  to  know  directly  what  is  the  quantity  actually  going  into  the  furnace,  we  enter  the  table,  under 
the  first  column,  and  opposite  to  that  we  find  122'61  cubic  feet,  which  is  the  quantity  that  would  pass 
through  a 1-inch  nozzle.  Then,  as  the  areas  of  circles  are  as  the  squares  of  their  diameters,  the  quantity 


102 


IRON. 


passing  through  a 2-inch  nozzle  will  be  four  times  as  great  as  through  a 1-inch ; therefore  the  quantity 
in  question  will  be  122'61  X 4 = 49044  cubic  feet  per  minute,  through  one  tuyere.  If  the  furnace  has 
two  tuyeres  with  the  same  sized  nozzle,  the  whole  quantity  discharged  in  one  minute  will  be,  then, 
98088  cubic  feet.  We  have,  then,  as  a general  rule,  to  enter  the  first  column  of  the  table  for  the  given 
pressure,  ranging  with  which,  in  the  second,  is  a number  that,  multiplied  by  the  square  of  the  diameter 
of  nozzle  used,  will  give  the  actual  quantity  blown  in  by  the  single  tuyere. 

It  may  be  applied,  again,  inversely,  to  find  the  diameter  of  nozzle  that  will  discharge  any  required 
quantity  per  minute  under  a given  pressure.  Thus,  if  the  question  be,  what  diameter  of  nozzle  will 
keep  up  a pressure  of  1 lb.  on  a discharge  of  800  cubic  feet  per  minute  through  one  tuyere  ? — we  havo 
only  to  divide  800  by  the  number  (10T66)  standing  in  the  second  column  opposite  the  given  pressure; 


the  square  root  of  tire  quotient 


or  2t8j  inches  is  the  diameter  sought. 


Table  shoiving  the  Volume  and  Weight  of  Blast  discharged  under  various  Pressures  and  at  ordinary 

Temperatures. 


Pressure  per 
square  inch. 

Quantity  in  cubic 
feet  per  minute, 
through  a 1-inch 
nozzle. 

Weight  in  lbs. 
per  minute. 

Pressure  per 
square  inch. 

Quantity  in  cubic 
feet  per  minute, 
through  a 1-inch 
nozzle. 

Weight  in  lbs. 
per  minute. 

4 oz.  aVd. 

18-54 

1-43 

2 lbs.  avd. 

139-48 

12.14 

1 “ “ 

26-20 

202 

24 

ti 

146-86 

12-97 

2 “ “ 

36-97 

2-86 

2-J- 

U 

153-70 

13-77 

4 “ “ 

52-07 

4-07 

2| 

it 

160-06 

1455 

6 “ “ 

63-51 

5- 

3 

it 

106-01 

15-30 

8 “or 4 lb. 

73-04 

5-80 

34 

a 

171-61 

16-03 

10  “ av’d. 

81-33 

6-51 

34 

u 

176.88 

16-75 

12  “ “ 

88-74 

7-16 

H 

a 

18T86 

17-46 

14  “ ■' 

95-47 

7-76 

4 

u 

186-58 

18-15 

1 lb.  “ 

101-66 

8-33 

44 

a 

191-07 

18-83 

14  “ “ 

112-78 

9 38 

44 

a 

195-35 

19-50 

14  “ “ 

122-61 

10-36 

4J 

a 

199-43 

20-17 

H “ “ 

13T44 

11-27 

5 

a 

203-32 

20-82 

If,  instead  of  measuring  the  discharge  by  volume,  we  have  occasion  to  know  the  weight  of  the  bloat, 
{he  third  column,  treated  in  the  same  manner,  gives  that  element. 


2374. 


2375. 


The  effects  of  a more  or  less  dense  blast,  i.  e.  of  more  or  less  pressure,  appear  to  take  place  in  two 
ways  principally.  First,  mechanically  upon  the  quantity  of  discharge  in  the  same  time ; and,  secondly, 
chemically  upon  its  constitution,  and  upon  the  materials  in  the  furnace.  The  air,  at  the  instant  of  ex- 
piring, is  of  the  density  it  had  in  the  blast-pipe,  although  it  very  shortly  afterwards  assumes  its  normal 


IRON. 


10? 


volume.  But  as  far  as  the  melted  materials  in  the  hearth  are  concerned,  it  is,  at  the  moment  of  entry 
richer  in  oxygen  in  proportion  to  its  density.  Thus,  under 


Pressure  of  Volume  of  air.  Weight  in  oxygen, 

lib.  100  cubic  feet  give T88  lbs. 

2 “ do.  do 2'  “ 

3 “ do.  do 2T2  “ 


By  increasing  the  pressure , then,  we  support  combustion  more  readily,  and  generate  a rn  intense 
degree  of  heat.  By  augmenting  volume , we  support  combustion  more  extensively,  and  produce  a greater 
quantity  of  heat.  These  considerations  apply  to  and  solve  the  question  often  mooted  among  founders, 
as  to  whether  the  best  effect  is  obtained  by  increasing  the  pillar  of  blast,  (as  they  term  it,)  or  using 
larger  nozzles,  and  thus  furnishing  more  air  under  a constant  pressure.  With  fusible  materials,  suffi- 
cient air  should  be  furnished  under  low  pressure ; with  refractory  ones,  it  is  better  to  increase  pressure 
rather  than  volume. 

The  apparatus  used  for  heating  the  blast  is  very  varied  and  multiform,  the  aim  being  in  all  to  furnish 
the  utmost  extent  of  heating  surface  with  the  greatest  economy.  Instead  of  mentioning  all  the  modifi- 
cations that  have  been  suggested,  or  figuring  the  contortions  that  hot-air  pipes  have  been  made  to 
exhibit,  Figs.  2314  and  23*75  give  vertical  sections,  transverse  and  longitudinal,  and  Fig.  2316  a horizon- 
tal section  of  the  most  convenient  and  best  arrangement,  either  for  separate  furnaces  near  the  tuyeres, 
or  for  ovens  on  the  trundle-head.  In  the  latter  case,  the 
horizontal  flue  shown  in  Fig.  2316  (which  communicates  with 
a vertical  one  in  the  stack  itself,  or  back-wall)  is  replaced 
by  a short  chimney.  So  far  as  outlay  is  concerned,  to  heat 
the  air  at  the  trundle-head  is  the  cheapest,  for  there  is  no 
extra  fuel  required.  But  to  realize  all  the  benefits  of  the 
system  and  the  greatest  absolute  economy,  separate  furnaces 
below  are  much  preferable. 

For  the  dimensions  to  be  given,  in  either  case,  iron-masters 
are  yet  without  any  rule,  not  so  much  from  any  difficulty  in 
investigating  the  principles  that  should  govern,  as  from  want 
of  actual  experimental  knowledge  on  the  rate  of  cooling,  Ac., 
which  prevents  any  general  formula  from  being  applied. 

Calculations  made  upon  the  quantities  and  velocities  of  blast  under  pressures  between  the  ordinary 
limits,  (of  ll  to  2-J  pounds  per  square  inch,)  result  in  18  and  28  square  inches  respectively  of  heating 
sui'face  for  every  cubic  foot  of  air  per  minute.  The  mean  of  these,  or  the  l-6th  of  a square  foot,  may  be 
taken  as  a safe  allowance  (if  the  pressure  does  not  exceed  2-J  pounds)  for  raising  the  temperature  of  the 
air,  at  the  instant  of  leaving  the  oven,  to  half  that  of  the  pipes.  What  will  be  its  temperature  at  the 
nozzle  depends  upon  the  distance  it  has  to  go,  the  thickness  and  size  of  pipes,  <fcc.  With  a higher  pres- 
sure than  2 ^ pounds,  the  heating  surface  ought  to  be  enlarged  directly  in  proportion,  at  least ; for  in  the 
very  fact  of  being  heated  the  air  acquires  a great  increase  of  velocity,  and  therefore  is  exj>osed  so  much 
shorter  time  in  the  heated  pipes. 

There  are  a number  of  interesting  points,  chemical  and  mechanical,  in  the  employment  of  hot-blast, 
for  which  there  is  no  room  here.  All  that  can  be  said  is,  that,  in  general,  with  hot-blast  the  furnace 
works  easier,  carries  a greater  burden,  with,  of  course,  a higher  yield,  and  reduces  materials  too  refrac- 
tory for  cold  air.  A notable  economy  of  fuel  and  flux  follows.  With  regard  to  the  former,  the  saving 
of  fuel,  upon  an  extensive  comparison  of  results,  may  be  stated  for 

Coke-furnaces  at  32  per  cent.,  from  an  average  temperature  of  330°  F. 

Charcoal  do.  20  do.  do.  do.  390°  F. 

Besides  this,  certain  raw  coals  that  would  not  be  admissible  with  cold-blast,  are  capable  of  being  used 
with  hot. 

As  to  the  quality  of  metal  made,  it  is  generally  gray  foundry-iron,  with  a more  uniformly  cubic  crys- 
talline form  than  cold-blast  foundry.  There  is  a general  prejudice  against  it,  as  being  less  strong,  but 
this  opinion  is  more  exaggerated  than  actual  experiments  warrant.  The  following  table  shows  the  pro- 
portionate strength  in  various  aspects,  from  numerous  trials : — 

Resistance  to 

Transverse  or 

Stretching  strain.  Crushing  strain,  oblique  strains.  Impact.  Stiffness. 


Cold-blast  iron 1000  1000  1000  1000  1000 

Hot-blast  iron  913  1033  963  1005  935 


These  statements  upon  the  quality  of  metal  lead  naturally  to  the  next  class  of  considerations,  which 
must  be  taken  up,  viz.,  upon  the  products  of  the  blast-furnace. 

These  products  are,  like  the  materials,  both  solid  and  gaseous.  To  the  former  belong  the  crude  iron 
and  the  furnace-cinder,  as  the  melted  slag  of  earthy  matters  is  termed;  to  the  other  the  various  ele- 
mentary and  compound  gases  which  arise  from  combustion  and  decomposition,  and  pass  olf  at  tire 
trundle-head. 

The  first  solid  product,  the  crude  iron,  has  been  already  sufficiently  treated  of ; the  other,  the  cinder, 
is  reciprocal  with  it,  and  is  one  of  the  important  tests  which  the  founder  has  in  judging  of  the  progress 
of  his  work  and  of  the  issue  that  he  may  reasonably  expect. 

Furnace-cinder,  chemically,  is  chiefly  a silicate  of  lime  in  various  proportions.  In  charcoal  works  it 
is  a bisilioate,  in  coke-furnaces  a single  silicate.  This  appears  from  the  following  statement,  which  rep- 
resents the  average  of  good  cinder,  i.  e.,  when  the  furnace  is  doing  good  work : — 


2370. 


104 


IRON. 


Char-coal  cinder. 

Coke  cinder. 

Silica 

53 

43 

Lime 

22 

35 

Alumina 

14 

Magnesia 

5 

4 

Protoxide  of  iron  

4 

4 

The  charcoal  cinder  is,  in  its  proportions,  a more  fusible  compound  than  the  other ; but  abstract 
fusibility  is  not  so  much  to  be  considered  as  fusibility  at  the  temperature  employed.  Coke-furnaces, 
having  a higher  temperature,  require  a more  refractory  material,  in  order  that  the  cinder  may  answer 
its  proper  uses. 

These  uses,  in  general,  are  to  assist  in  fusion  and  reduction;  with  very  fusible  ores,  to  retard  fusion 
until  the  deoxidation  of  the  metal  has  occurred ; and  after  reduction,  to  protect  the  metal  in  the  hearth 
from  contact  with  the  blast.  In  this  last  aspect,  especially,  the  degree  of  fusibility  of  the  cinder  is  of 
great  practical  importance.  If  it  be  too  thick  and  pasty,  it  embarrasses  the  separation  of  the  metal ; 
if  it  be  too  thin  and  liquid,  the  iron  is  exposed  naked  to  the  blast.  These  properties,  as  they  may  exist 
within  the  furnace,  are  judged  of  by  the  consistency  of  the  cinder  during  its  flow.  If  liquid  enough  to 
flow  readily  over  the  dam-plate,  and  slowly  cooling  afterwards,  it  is  of  the  proper  character;  but  what- 
ever its  liquidity  may  be,  if  it  tends  to  cool  rapidly,  the  presence  of  metallic  associations  is  to  be  inferred. 
Such  association,  as  far  as  iron  is  concerned,  may  be  inferred  also  from  its  color,  which,  with  an  admix- 
ture of  iron  in  notable  proportions,  is  always  brownish  or  black.  The  most  satisfactory  color  for  the 
mass,  on  a fresh  fracture,  is  whitish  gray.  Blue  and  bluish-green  shades  and  streaks  are  almost  always 
to  be  met  with.  The  proper  way  to  judge  of  color,  however,  is  only  upon  a pulverized  specimen.  The 
fracture  of  cinder  is  always  conchoidal,  and  its  specific  gravity,  at  a mean,  2'6.  The  aspect  of  good 
cinder,  from  charcoal  works,  is  glassy  ; from  coke-furnaces,  it  is  more  lithoid,  or  stone-like.  When  cin- 
der becomes  earf/ty-looking,  it  argues  deficiency  of  heat ; and  if  the  furnace  on  the  preceding  cast  has 
given  gray  iron,  more  blast  may  be  put  on  without  fear, — if  white  iron,  the  blast  should  be  augmented 
cautiously.  A cavernous  or  honeycombed  cinder  appears  to  originate  in  the  same  defect  of  heat ; while 
one  like  enamel,  although  by  many  founders  attributed  to  the  same  cause,  arises  more  from  elements  in 
the  materials — chiefly  phosphate  of  lime. 

The  gaseous  products  of  the  furnace  may  be  taken  to  consist,  on  an  average,  of 

Nitrogen 56  Carburetted  hydrogen  2 

Carbonic  acid-. 19  Vapor  of  water 7 

Carbonic  oxide 16 

The  watery  vapor  most  likely  arises  from  the  moisture  of  the  materials  freshly  put  in,  and  is,  therefore, 
hardly  a product.  If  the  fuel  had  all  been  fully  consumed,  the  sole  products  would  be  nitrogen  and 
carbonic  acid.  But  this  full  combustion  has  not  been,  and,  with  the  methods  followed,  cannot  be 
attained. 

These  gases,  as  they  are,  pass  off  at  the  trundle-head  at  a high  temperature ; so  high,  that  the  oxy 
and  hydro  carbon  combine  there  with  the  oxygen  of  the  atmosphere  and  inflame.  This  flame  furnishes, 
among  other  things,  a sign  to  the  founder  of  the  state  of  the  furnace.  If  it  is  small  and  weak,  it  is  pre- 
sumable that  the  blast  does  not  pass  through  sufficiently ; and  the  materials,  which  from  the  moment 
of  charging  ought  to  be  undergoing  a preparation  for  fusion,  are  in  fact  descending  more  or  less  raw. 
The  remedy  for  this  is  not  always  to  increase  the  blast ; on  the  contrary,  a discreet  founder  will  first 
take  into  consideration  the  nature  of  the  materials,  their  friability,  and  liability  to  become  packed  in  the 
cuvette.  Too  little  slope  to  the  boshes,  too,  is  always  more  or  less  involved  in  the  result,  where  the 
materials  are  constant. 

If  the  flame  is,  as  sometimes,  on  one  side,  it  is  a sign  that  the  charges  are  not  descending  equally. 
If  this  is  permanent,  there  is  reason  to  suppose  that  the  in-walls  or  boshes,  or  both,  have  degraded  out 
of  shape.  If  occasional,  it  is  rather  to  be  attributed  to  an  accidental  choking  of  the  furnace,  caused  either 
by  a bad  state  of  materials,  or,  what  is  more  common,  bad  filling.  Of  course,  the  flaring  from  atmos- 
pheric causes  must  not  be  confounded  with  this  phenomenon.  In  a well-going  furnace  and  a calm  at- 
mosphere the  flame  should  rise  cylindrically,  with  life,  and  with  a certain  whistling  cry  the  founder 
likes  to  hear. 

A fame  at  the  tymp  is  a sign  that  the  blast  is  not  going  in  the  right  direction ; in  this  case,  it  is  better 
to  alter  the  charges,  by  putting  on  less  mine,  than  to  change  the  blast. 

The  high  temperature  at  which  the  gases  pass  off  at  the  trundle-head  is  an  unavoidable  consequence 
of  the  process  ; it  is,  nevertheless,  waste-heat.  This  waste-heat  has  been  turned  to  account,  as  already 
mentioned,  in  the  case  of  hot-blast.  It  has  also  been  used  for  burning  lime,  for  carbonizing  wood,  fur 
coking,  and  for  generating  steam.  For  all  these  purposes,  except  the  first  and  last,  it  is  rarely  conve- 
nient to  apply  the  inflamed  gases ; and  as,  in  leading  off  to  a distance  what  is  only  inflammable  air 
there  is  more  or  less  loss  of  heat,  these  applications  have  been  limited.  For  roasting  ores,  it  is  a per 
fectly  appropriate  means. 

M.  Faber  du  Faure,  as  far  back  as  1837,  conceived  and  very  ingeniously  executed  a very  brilliant 
idea  of  leading  off  the  gases,  without  contact  of  air  at  first,  to  suitable  points  where,  by  mixing  it  with 
highly  heated  atmospheric  air,  it  could  be  burnt,  and  the  heat  thus  produced  applied  not  only  to  the 
generation  of  steam,  but  also  to  other  processes  (refining,  puddling,  and  reheating)  in  the  manufacture  of 
the  crude  iron  yielded  from  the  blast-furnace.  The  progress  of  his  experiments  led  to  investigations  upon 
the  actual  constitution  of  the  gases  at  different  points  of  the  stack  ; and  to  the  conclusion  that  the  oxide 
of  carbon  existed  as  a maximum  at  a level  below  the  trundle  head,  about  one-third  of  the  height  of  the 
stack.  About  this  level,  therefore,  one  or  more  flues  are  made  in  the  stack,  through  which  the  gas 
ascends  into  a reservoir  around  the  trundle-head,  whence  conduits  of  masonry  or  metal  take  it  off  into 


IRON. 


105 


in  air-chest ; from  which,  after  mixture  with  a hot-blast,  it  issues  through  a suitable  number  of  nozzles 
or  burners  into  the  hearth  where  it  is  destined  to  be  burned. 

This  discovery  and  application  excited  a good  deal  of  attention  shortly  after  it  was  made  public — in 
this  country,  about  1840,  and  large  expectations  were  formed  as  to  the  revolution  it  was  destined  to 
cause  in  the  manufacture  of  iron.  But,  either  from  some  intrinsic  difficulties,  not  at  first  apparent,  or 
from  bad  management,  its  subsequent  development  has  not  been  so  extensive. 

Faber’s  method,  if  confined  to  gases  existing  at  or  very  near  the  trundle-head,  would  be  perfectly 
unexceptionable ; when,  however,  they  are  drawn  too  low  down  from  the  body  of  the  materials,  there 
is  reason  to  apprehend  that  the  train  of  the  furnace  will  be  disadvantageously  embarrassed.  At  least, 
such  seems  to  be  the  conclusion  of  those  most  practically  conversant  with  smelting.  This  train  is,  as 
we  know,  very  easily,  and  sometimes  unaccountably,  deranged ; and  there  are  few  processes  in  the 
arts,  where  large  masses  are  in  action  at  once,  so  liable  to  the  influence  of  apparently  slight  causes, 
and  so  much  under  the  domain  of  what  may  be  called  the  working.  Before  leaving  the  subject  ol 
smelting,  then,  some  particulars  must  be  mentioned  in  regard  to  the  working  of  the  furnace. 

For  working  a single  coke-furnace  of  the  first  class,  the  following  statement  may  be  taken  of  the 
hands  usually  found  necessary,  with  their  respective  occupations : viz.,  two  keepers,  who  take  turn  and 
turn  about,  every  twelve  hours,  in  the  tymp-arch  and  below ; two  fillers,  who  are  engaged  in  a similar 
manner  about  the  trundle-head  and  top-house  above,  each  with  a boy  to  help ; two  cinder-fillers,  in  turn, 
to  clear  away  cinder  below ; one  cinder-hauler ; one  engineer  and  helper  at  the  blast-engine  ; one  weigher 
of  pigs : all  these  (together,  9 men  and  3 boys)  are  engaged,  day  and  night,  in  and  about  the  stack. 
Besides  these,  for  ore-roasting  are  required  one  man  and  two  boys  ; for  coking,  two  men  and  eight, 
bovs  ; for  breaking  limestone,  two  boys  ; for  hauling  material  from  the  yard,  (which  is  done  on  a rail- 
track,)  a man,  a boy,  and  a horse.  These  4 men  and  13  boys  are  occupied  in  the  yards  adjacent,  where, 
and  about  the  stack,  <fcc.,  there  is  always  miscellaneous  work  enough  for  four  laboring  hands  by  day. 
This  enumeration  excludes  the  furnace-manager  or  founder,  and  underground  agent ; for  the  first  can 
superintend  the  smelting,  as  the  other  can  the  mining,  for  several  furnaces  as  well  as  for  one. 

Of  course,  where  the  furnace  is  smaller,  as  it  is  where  charcoal  is  the  fuel,  there  is  not  so  much  work 
to  be  done,  and,  in  proportion,  fewer  hands  can  do  it ; where  wages  are  high,  more  work  might  perhaps 
be  got  out  of  each  hand,  or  it  may  be  satisfactory  if  done  in  a less  perfect  manner;  but  the  statement 
above  is  from  establishments  where  ultimate  economy  has  been  a principal  object. 

None  of  the  work  that  has  been  mentioned  can  advantageously  be  done  by  contract ; the  fuel  and 
mine  should  always  be  prepared  under  the  sujiervision  of  the  furnace-manager.  But  a plan  used  in 
all  large  works  to  a greater  or  less  extent,  is  to  have  a tariff  of  wages  for  all  the  hands  named  ; which 
is  rated  and  paid  per  ton  of  metal  made,  according  to  its  quality.  It  becomes,  thus,  the  direct  interest 
of  all  hands  that  the  furnace  should  yield  the  most  possible  of  the  best  iron. 

The  number  of  hands  given  above  may  seem  large,  but  in  reality,  there  is  a good  deal  of  work  to  be 
done,  and  that  of  a sort  at  intervals  so  hard,  and  under  such  variations  of  temperature,  that  workmen 
about  furnaces  are  generally  short-lived.  Thus,  the  duty  of  the  keeper,  for  instance,  besides  moulding 
the  pig-bed,  which  is  done  at  spare  times,  and  watching  the  tuyeres,  <fcc.,  which  is  a frequent  duty,  is  to 
do  the  heavy  work  sometimes  required  for  breaking  into  the  furnace  either  at  the  fore-hearth  or  at  the 
tuyeres,  putting  in  grates,  <fcc.  These,  which  are  extraordinary  demands,  are  done  under  the  direction 
of  the  founder ; who  also  himself  bears  a hand  when  necessary,  or  calls  down  the  filler  too.  The  tap- 
ping, which,  when  the  furnace  is  in  regular  train,  occurs  twice  in  the  twenty-four  hours,  (and,  from  old 
habit,  at  6 A.  M.  and  6 P.  M.,)  is  generally  done  by  the  founder,  except  in  extensive  works  of  several 
furnaces. 

As  a general  principle,  a furnace  works  best  when  most  let  alone ; care  having  been  taken  in  the 
selection  and  proportion  of  the  materials  and  blast.  But,  in  the  best  managed,  accidents  will  not 
unfrequently  happen,  the  repairing  of  which  is  a serious  task  upon  the  physical  energies  of  the  workmen. 

The  filler,  with  less  demand  upon  his  reasoning  faculties,  has  not  less  labor  to  perform ; and  its  proper 
execution  is  one  of  the  most  important  items  about  the  furnace.  Upon  regular  and  suitable  filling 
depends  more  than  is  often  supposed.  Various  methods' have  been  proposed  and  tried,  in  this  respect, 
to  promote  a mechanical  accuracy;  some  very  plausible,  but  none  unexceptionable.  The  old,  and  most 
habitual  method,  is  to  fill  by  hand ; the  fuel,  if  coke,  being  upset  from  two  wheelbarrows — if  charcoal, 
thrown  in  from  baskets.  Ore  and  flux  are  generally  filled  from  sheet-iron  trays.  Later,  a more  judi- 
cious practice  has  grown  up  of  weighing  all  charges  instead  of  measuring,  for  which  the  barrows,  bas- 
kets, <fcc.,  served.  Sometimes,  after  being  weighed,  the  materials  are  kept  separate  ; sometimes  they 
are  mixed  and  charged  together.  This  last,  if  well  done,  is  undoubtedly  the  best. 

When  furnaces  are  built  on  a plane,  with  the  yards  around  their  base,  the  labor  of  the  filler  is  some- 
times much  increased.  With  such  furnaces  there  is  often  an  inclined  plane,  along  which  a separate 
engine  generally  winds  up  the  trucks  containing  the  charges ; or  the  blast-engine  is  geered  for  the  same 
purpose.  In  both  cases,  the  different  diameters  of  the  fore  and  hind  wheels  keep  the  platform  of  the 
truck  horizontal.  The  filler  takes  passage  along  with  his  freight.  Sometimes  a vertically  elevating 
machinery  is  employed ; as  the  equilibratro  water  system  of  Staffordshire,  where  the  counterpoise  to 
the  charges  ascending  is  a bucket  filled,  pro  hac  vice,  with  water,  and  discharging  itself  when  it  strikes 
the  ground.  Empty,  it  is  overbalanced  by  the  platform  for  the  baskets ; which,  upon  being  cast  off, 
again  descend  to  be  filled,  &c. 

The  number  of  charges  per  turn,  of  twelve  hours,  varies  with  the  work  that  the  furnace  is  doing  from 
20  to  48.  As  soon  as  made,  each  one  is  scored  by  the  filler  upon  a board  for  the  inspection  of  the 
founder ; who  thus  sees  at  a glance  what  the  furnace  is  bearing,  and  can  direct  accordingly. 

The  business  of  keeping  the  tymp-arch  clear  of  cinder  is,  .with  a first-class  coke-furnace,  no  little  oc- 
cupation of  itself.  It  is  dragged  off  with  long  hooks,  in  large  masses,  to  a suitable  place  in  the  moulding- 
nouse  ; where,  if  necessary,  it  is  quenched  and  broken  up  in  order  to  being  loaded  on  a cart.  Mixed 
with  broken  stone,  or  even  by  itself,  it  forms  one  of  the  best  materials  known  for  road-metal. 


106 


IRON. 


The  breaking  off,  weighing,  and  piling  the  pigs,  sows,  and  runners,  (as  the  different  moulds  in  a pig 
bed  are  called,)  is  another  task  in  a large  furnace.  The  number  of  pieces  in  a day  will  amount  to  about 
£00,  from  50  to  60  lbs.  each. 

The  moulding,  &c.,  of  castings,  which  are  not  unfrequently  made  at  the  blast-furnace,  belong  more 
properly  to  the  next  division  of  the  subject,  that  of  founding. 

II.  Founding , or  casting  crude  iron  in  fusion  into  hollow  moulds,  no  doubt  followed,  historically  the 
working  of  the  metal  in  a more  or  less  malleable  state  ; but,  in  the  chronological  sequence  of  processes, 
it  comes,  as  here,  directly  after  the  production  of  the  crude  iron  itself.  Indeed,  for  some  objects,  this 
crude  iron  answers  very  well  itself,  without  a second  fusion ; but,  in  the  general  business  of  casting, 
particular  qualities  of  metal  are  required  for  particular  objects,  and  certain  characters  are  attainable 
only  by  a mixture  of  different  sorts  of  metal  at  once.  It  is  obvious  that  these  conditions  are  not  attained 
with  a single  or  even  several  blast-furnaces.  Further,  in  the  casting,  care  has  to  be  taken  to  have  the 
metal  entering  the  moulds  of  a suitable  temperature  ; this  would  be  more  difficult  in  metal  that  is  run 
out , as  generally  it  has  to  be,  from  blast-furnaces,  than  in  that  which  is  first  received  in  a ladle,  where 
it  is  kept  till  of  a supposed  suitable  temperature  to  be  poured.  Finally,  it  is  often  neceesary  (as  for 
blowing-cylinders,  &c.)  to  have  a greater  weight  of  metal  than  the  hearth  of  even  a large  blast-furnace 
contains ; resort  must  be  had,  in  such  case,  to  several  separate  furnaces,  whose  united  contents  may 
suffice.  But  wherever  rough  castings,  as  they  may  oe  termed,  viz.,  tram-rails,  railroad  chairs,  hollow- 
ware,  &c.,  are  to  be  made  in  quantity,  where  the  shape  and  dimensions  of  the  moulds  will  allow  uniform 
cooling,  and  where  the  highest  quality  of  metal  need  not  be  possessed,  or  at  least  such  quality  as  is 
attained  by  mixtures,  it  is  the  best  economy  to  put  the  blast-furnace  upon  a proper  train  for  the  purpose, 
and  to  cast  at  once,  either  by  run-outs  or  pourings,  from  it. 

There  are  general  principles  about  moulding  and  casting  which  govern  in  all  metals  and  alloys. 
These  should  have  come  under  a special  article,  Founding  ; but,  in  default  of  that,  will  be  found  under 
Metallurgy.  All  that  will  be  given  here,  will  be  such  principles,  precautions,  and  practice,  as  belong 
particularly  to  iron-founding. 

In  general,  the  metal  suitable  for  castings  is  gray  crude  iron  ; for  certain  cases  where  the  surface  is  of 
no  great  consequence,  (i.  e.,  the  perfection  of  the  casting,)  and  where  the  resistance  is  to  a crushing 
force,  white  iron  may  be  used.  'The  effect  of  a remelting  is  to  consume  the  carbon,  both  free  and  com- 
bined, to  a greater  or  less  degree  ; and  the  aim  is  to  produce  a metal  which  shall  contain  the  least 
quantity  of  free  carbon,  and  at  the  same  time  retain  the  octahedral  crystalline  structure  that  character- 
izes gray  iron.  This  structure,  other  things  being  the  same,  appears  to  be  chiefly  affected  by  the  ca- 
pacity of  the  metal  for  heat,  its  radiation,  and  the  circumstances  under  which  it  cools. 

Iron  may  be  melted  either,  1st,  in  crucibles  or  pots ; 2d,  in  cupolas;  or,  3d,  in  reverberatory  furnaces. 
The  first  are  made  of  sand,  as  the  Hessian  crucibles,  or  of  black-lead,  like  the  blue-pots  of  commerce. 
They  are  of  various  size  ; but  the  largest  will  not  hold  more  than  35  lbs.,  beyond  which  they  become 
unmanageable.  They  are  set  upon  some  refractory  stand  or  shelf,  in  a suitable  oven.  Not  in  contact 
with  air  directly,  the  loss  in  remelting  ought  not  to  be  more  than  five  per  cent.  In  fact,  however,  it  is 
much  greater ; and  experience  seems  to  dictate,  as  the  best  economy,  rather  to  bum  away  a portion  of 
the  iron  than  to  use  a vitrifiable  flux.  Where  the  temperature  is  not  at  command,  it  is  better  to  use  a 
flux,  both  as  an  economy  of  fuel  and  of  metal.  It  is  obvious  that  the  application  of  this  method  is 
limited  to  small  articles.  The  advantage  of  it,  in  such  cases,  is  the  beauty  and  finish  of  surface  it  affords. 

In  the  second  method,  that  of  cupolas,  the  metal  is  in  contact  with  air,  fuel,  and  flux.  There  is, 
therefore,  both  a greater  loss  and  an  inferior  result.  This  loss  may  be  rated,  on  the  average,  at  8 per 
cent.  The  introduction  of  cupolas  followed  upon  the  use  of  the  pots  ; and  they  have  grown  from  the 
little  portable  furnaces  of  France  (about 
the  year  1700) — say  two  feet  in  height, 
in  parts — into  miniature  blast-furnaces, 

10  and  even  15  feet  in  height.  To  show 
that  this  is  no  limit  in  economy,  although 
it  is,  perhaps,  in  the  labor,  may  be  ad- 
duced a case  in  Prussia,  some  years  ago, 
where  a blast-furnace  34  feet  high,  which 
worked  in  hollow-ware,  had  become  so 
encumbered  with  scraps,  that  it  became 
a serious  matter  to  disembarrass  the  es- 
tablishment. For  this,  they  built  inside 
of  the  stack  somewhat  in  section  like  a 
fluss-ofen  before  described,  narrowing 
it  to  22  inches  at  the  trundle-head  ; 4 ^ 
feet  at  the  boshe-s,  which  received  a 
slope  of  45°  ; with  a hearth  15  inches 
in  diameter  at  top,  and  twelve  inches 
below.  AVith  this  was  remelted,  in  21 
weeks,  very  nearly  240  tons  of  metal ; 
the  fuel  (charcoal)  was  34  per  cent,  of 
the  yield,  and  the  loss  of  metal  was  8 
per  cent. 

The  little  furnaces  of  1J  to  2J  feet 
are,  except  for  special  purposes,  very 
much  out  of  use.  Fig.  2377  shows,  however,  a small  swinging  furnace  in  section,  like  those  still  eni 
ployed  in  Sweden.  The  dark  parallel  lines  show  the  barrel-shaped  casing  of  stout  sheet-iron,  or  boiler- 
plate, inside  of  which  the  fire-brick  are  laid.  The  whole  concern  rests,  and  can  be  made  to  swing,  on  its 


IRON. 


107 


journals,  i i,  which  work  in  an  appropriate  gallows-frame,  seen  below  At  l m are  staples,  in  which  iron 
levers  can  be  thrust  to  tilt  the  furnace  over  and  pour  through  the  tap-hole  h,  which  is  furnished  with 
projections  on  which  a clay  lip,  or  runner,  can  bn  moulded.  This  tilting  is  still  further  helped  by  placing 
the  centre  of  motion  an  inch  or  two  below  the  centre  of  gravity  when  the  hearth  is  full.  The  ash-hole, 
for  cleaning  out,  is  shown  at  p , and  1 1 represent  the  two  tuyhres  used.  Over  the  throat  is  fixed  a hood, 
or  mantle,  connected  with  a chimney-flue.  These  cupolas  are  about  8 feet  high  ; the  tuyere,  from  14  to 
1 6 inches  above  the  hearth,  which,  as  shown,  is  made  of  fire-clay,  well  packed  and  beaten  on  the  iron 
bottom.  The  diameter  at  the  bottom  is  18  inches  ; across  at  the  tuyeres,  30  inches  ; at  the  throat,  about 
2 feet : on  the  average  containing  about  1000  lbs.  of  metal. 

Figs.  2378  and  2379  show  a section  and  ground-plan  of  a neat  and  convenient  form  of  cupola.  The 
exterior  is  of  cast-iron  plates,  with  flanges  that  bolt  together  ; the  m-walls  of  fire-brick  ; the  space  bo 
tween  the  casing  and  in-walls  filled  with  coke,  dust,  or  ashes.  Tho  bottom  is  an  annular  plate,  upon 


2378. 


foundation  of  masonry,  which  should  be  well  drained,  as  shown  at  d.  The  hearth  itself  is  made  of  fire- 
clay, sloping  outwards  to  the  lip  in  order  to  make  a clean  run-out.  The  height  of  such  a cupola  is  from 
8 to  10  feet;  the  tymp,  as  it  may  be  called,  (i.  e.,  the  tap,)  is  12  by  16  inches  high.  (This  is  made 
large  purposely,  in  order  to  get  at  the  hearth  for  cleaning  it,  and,  when  the  cupola  is  working  is  stopped 
up.)  The  tuyere  can  be  varied  from  16  to  20  inches  above  the  hearth.  ’ 

The  hearth  in  this  figure  is  represented  as  very  large— the  object  being  to  save  metal  and  repairs, 
rather  than  fuel.  In  general,  a narrow  hearth  saves  fuel ; but  it  is  at  the  expense  of  metals  oxidated 
and  in-walls  worn.  The  comparison  for  ultimate  economy  must  be  made  in  each  case  ; and  the  result 
will  differ  according  to  the  locality.  Where  fuel  is  dear,  the  hearth  may  be  narrowed  to  advantage. 

The  internal  shape  of  cupolas  does  not  appear  to  have  been  much  studied,  if  one  may  jud<re°  from 
their  variety.  These  rules,  however,  may  be  safely  taken  ; that,  with  charcoal,  the  height  should  be 
greater  than  with  coke,  on  account  of  the  greater  friability  of  the  material,  and  the  greater  tendency 
of  the  crude  iron  to  descend  too  soon.  A cupola  for  coke  ought  not  to  be  less  than  6 feet  in  any  case  • 
nor,  with  charcoal,  less  than  9 feet.  The  English  cupolas  for  coke  are  ordinarily  8 feet  hio-h,  and  about 
3 feet  wide,  holding  between  3 and  4 tons.  The  best  form  for  economy  is  that  of  a small  blast-fur- 
nace, proportioned  as  for  refractory  materials. 

According  to  the  size,  the  quantity  of  blast,  under  a mean  pressure  of  14  lbs.,  will  be  from  250  to 
550  cubic  feet  per  minute.  The  fuel  consumed  under  a good  train  will  be,  with  the  best  coke,  about  30 
per  cent. ; with  coke  of  inferior  quality,  50  per  cent. ; and  with  charcoal,  75  per  cent,  of  the  yield, 
which,  in  the  best  cupolas,  is  about  one  ton  per  hour.  If  the  pigs  are  not  very  clean,  no  flux  need  be 
used  ; if  scraps  are  to  be  worked  up,  limestone  (chalk  is  preferred  in  England)  or  oyster-shells  must  be 
added  in  small  quantities.  If  the  average  loss  of  metal,  in  remelting,  is  more  than  8 per  cent.,  it  must 
generally  be  attributed  to  some  error  in  the  building,  or  in  the  management. 

When  a cupola  is  connected  with  a high-furnace,  the  blast  is  generally  taken  off  from  the  blowing- 
engine.  Otherwise,  the  fan-blast,  already  described,  is  the  most  convenient.  It  is  also  well,  in  cupolas 
for  large  work,  to  have  three  or  four  tuyere-holes  at  different  elevations,  to  which  the  nozzles  can  be 
successively  applied  as  the  hearth  fills. 

The  third  method  of  remelting  is  by  reverberatory  furnaces,  where  the  metal,  not  in  contact  with  fuel, 
is  fused  by  the  heat  of  the  flame  that,  from  the  peculiar  shape  of  the  roof,  is  reflected  and  reverberated 
down  upon  the  bottom,  or  sole.  With  a reverberatory  furnace  proper,  there  is  no  blast  or  impulsion  of 
air— it  is  all  aspiration— and  the  necessary  draught  is  created  by  the  height  of  the  chimney.  Figs.  2380 
and  2381  show  a vertical  and  horizontal  section  of  one  of  the  best  forms  of  reverberatory  furnaces ; in 
which  a indicates  the  ash-pit,  with  the  grate-bars  over  it ; cc  the  cliarging-door  for  fuel ; b b the  bridge 
dividing  the  fuel  from  the  metal  to  be  melted ; dd  the  charging-door  for  the  metal ; (both  c and  d are 
balance-doors,  that  slide  vertically,  shut  tightly,  and,  wlien  the  fire  is  to  be  most  intensely  urged,  must 
be  luted ;)  h h the  hearth,  or  sole,  on  the  upper  part  of  which,  near  the  bridge,  the  metal  is  charged, 
and  along  whose  inclined  surface  it,  when  melted,  runs  ; i i the  dam,  whose  function  is  as  well  to  nar- 
row the  chimney-throat,  as  to  retain  the  fused  metal ; k the  chimney ; and  1 1 the  tap,  where  the  metal 


108 


IRON. 


is  run  out  through  the  dam,  and  which  is  stopped  with  clay  till  needed.  This  tap  is  sometimes  placed 
m the  side,  but  disadvantageous^.  The  inner  parts  of  this  furnace  and  chimney  are  built  with  fire- 
brick ; the  sole,  which  needs  frequent  repair,  laid  of  fire-clay,  resting  either  on  massive  or  arched 


masonry,  or  on  castings  ; the  external  parts  of  common  brick,  well  tied  with  iron  bolts  and  plates  ; the 
chimney,  which,  in  the  figure,  is  represented  fragmentary,  should  be,  at  a minimum,  40  feet  in  height, 
and  is  terminated  with  a damper,  as  shown  in  Fig.  2382.  The  flue  in  this  figure  appears  cylindrical 
which  is  the  best  for  the  draught,  al- 
though it  is  generally  made  square.  2382. 

In  no  case  ought  its  section  to  be  less 
than  a square  foot.  The  damper, 
which  is  worked  with  a light  chain  or 
wire,  a9  shown,  should  always  be 
provided  with  a register-scale  below, 
calculated  for  different  degrees  of 
opening  and  draught. 

The  dimensions  of  such  furnaces 
are  at  discretion : some  hold  hardly 
a ton,  others  three  and  four  tons. 

But  the  proportions  of  the  principal 
parts — viz.,  the  fire-grate,  the  heard), 
and  the  chimney — must  be  subject  to 
the  laws  of  Pneumatics  and  Heat,  and  are,  therefore,  not  arbitrary.  The  following  rules,  which  are  far 
from  having  the  generality  and  exactitude  that  would  flow  from  a fully  explored  theory,  may  be  taken 
as  in  accordance  with  the  best  practice : 

1.  The  higher  the  chimney,  the  better  and  more  manageable  the  draught,  other  things  being  equal 
If  the  section  of  the  chimney  be  too  narrow,  the  draught  will  be  choked ; if  too  wide,  it  will  be  weak- 
ened. When  one  stack  is  built  for  several  furnaces,  each  one,  then,  should  have  its  separate  flue. 

2.  The  sections,  respectively,  of  the  narrowest  part  of  the  throat  (about  i,  Fig.  2380)  and  the  widest 
part  of  the  shaft,  (near  k,)  may  vary  between  the  limits  of  2|- : 1 and  3 : 1.  This  variation  can  be 
made  from  time  to  time,  according  to  the  nature  of  the  fuel  and  of  the  metal  to  be  melted,  by  packing 
more  or  less  sand  upon  the  dam. 

3.  With  a given  capacity  of  hearth  and  given  fuel,  the  areas  of  the  throat  and  fire-grate  must  be  in 
constant  proportion.  This  is  easily  ascertained  by  observing  how  the  furnace  works.  If  fusion  takes 
place  the  soonest  near  the  bridge , it  may  certainly  be  concluded  that  the  area  of  the  throat  is  too  small ; 
if  fusion  occurs  sooner  near  the  dam,  the  throat  is  too  large.  The  numerical  ratio  will  vary  according 
to  the  strength  of  the  coal  and  the  length  of  the  hearth  : it  may  be  assumed,  as  a mean,  that  the  ag- 
gregate of  the  open  spaces  between  the  bars  should  be  34  times  the  area  of  the  throat. 

4.  The  absolute  capacity  of  the  furnace  is,  of  course,  determined  in  advance  by  the  work  it  is  in- 
tended to  do.  Its  relative  capacity  should  be  such  as  that  it  goes  on  continually  contracting  itself  the 
further  from  the  grate  ; so  that  there  should  be  an  equal  degree  and  quantity  of  heat  in  every  part. 

5.  The  length  and  width  of  the  hearth,  two  of  the  elements  of  the  capacity,  should  vary  according 
to  the  fuel.  On  an  average,  the  length  may  be  twice  the  width.  With  coal  that  gives  much  flame,  it 
may  be  24  times  the  width  ; with  a dry  coal,  and  especially  anthracite,  it  should  rot  be  more  than  1 4 
times  the  width. 

6.  The  area  of  the  hearth  should  not  be  more  than  34  times  the  area  of  the  grate,  bars  and  all. 

7.  The  height  and  width  of  the  hearth  should  be  such  as  that  a vertical  section  through  its  widest 
part,  near  the  bridge,  should  be  f the  horizontal  section  of  the  grate. 

8.  The  slope  of  the  hearth  need  not  be  more  than  4 inch  to  the  foot,  which  allows  the  iron  to  run  out 
freely.  If  the  inclination  be  great,  there  is  no  chance  for  yet  solid  fragments  to  be  soaked  (as  it  were) 
in  already  melted  metal,  and  thus  be  facilitated  in  their  fusion  ; while  there  is  also  a greater  liability  to 
decarbonization,  and  consequent  formation  of  carcase. 

9.  The  height  of  the  bridge  above  the  hearth  depends  upon  the  fusibility  of  the  iron  to  be  melted. 
If  easily  fusible,  it  may  be  from  8 to  10  inches  in  height ; if  refractory,  not  more  than  4 or  5 inches. 

10.  The  section  of  the  grate  has  been  given  already  in  terms  of  the  other  parts.  The  space  betweer 


IRON. 


109 


the  bars  may  vary  from  05  to  0T5  inch,  according  to  the  size  of  coal.  The  depth  of  ash-pit.  may  he 
lessened  in  proportion  to  the  inflammability  of  the  coal ; but  it  should  always  be  considerable  enough  tc 
avoid  having  the  air  heated  by  transmission  over  fallen  cinders  and  ashes. 

Theoretically,  it  would  hardly  appear  that  a large  reverberatory  furnace  should  give  a less  intense 
heat  than  a small  one  ; practically,  however,  this  is  found  to  be  the  case,  which  may  arise  from  this — 
that  in  proportioning  the  size  of  chimney,  beyond  a certain  limit  there  occurs  the  phenomenon  of  as- 
cending and  descending  currents. 

The  foregoing  rules  apply  to  furnaces  worked  with  coal,  which  is  by  far  the  most  economical  fuel  for 
these  arrangements.  "When  wood  is  used,  which  contains  less  carbon  and  more  oxygen,  there  has  to  be 
a material  alteration  in  the  proportions.  In  a successful  example,  the  area  of  the  grate  was  two-thirds 
that  of  the  hearth,  four  times  the  widest  section  beyond  the  bridge,  and  ten  times  that  of  the  throat. 

Every  time  iron  is  fused  it  becomes  more  refractory,  especially  after  reverberatory  fusion.  Metal  of 
the  first  and  second  fusion  should  not,  therefore,  be  mixed  together;  and,  as  far  as  possible,  only  those 
of  the  same  or  nearly  equal  fusibility.  So  also  the  fragments  ought  to  be  of  the  same  size.  If  any 
difference  is  allowed,  then  the  larger  pieces  ought  to  be  charged  nearest  the  bridge. 

In  charging,  it  is  well  to  get  the  heat  of  the  furnace  well  up  first,  and  afterwards  the  aim  should  be 
to  raise  it  to  the  full  height  as  quickly  as  possible.  A low  temperature  is  only  at  the  expense  of  fuel 
and  metal.  After  the  iron  is  liquefied,  every  care  must  be  taken  to  keep  out  cold  air;  the  fuel  must 
be  charged  quickly,  frequently,  and  in  quantities  that  will  just  maintain  a continued  and  active  com- 
bustion. If  too  much  is  thrown  on  at  once,  the  temperature  fluctuates  ; if  too  little,  it  falls.  From  coe- 
half  to  three-quarters  of  a bushel  of  coal,  every  ten  minutes,  will  keep  a grate  of  average  size  (say  nine 
square  feet)  sufficiently  supplied.  The  best  test  is  the  flame  at  the  top  of  the  chimney : if  it  does  not 
appear  there,  even  with  a chimney  of  sixty  feet,  there  is  a waste  of  metal ; if,  on  the  contrary,  it  shoots 
out  much  above,  there  is  a waste  of  fuel. 

The  average  consumption  of  coal  is  about  60  per  cent,  of  the  yield  ; the  waste  of  metal  about  1 per 
cent.,  with  a good  train.  The  average  effect,  under  equal  volumes  of  coal  to  wood,  is  very  nearly  seven 
\o  one.  Upon  the  experience  in  Russia,  it  takes,  by  weight,  of  seasoned  wood,  150  per  cent,  upon 
the  yield. 

The  time  taken  to  melt  down  a charge  is  very  variable,  according  to  the  fusibility  of  the  metal,  the 
strength  of  the  coal,  the  proportions  of  the  furnace,  and  the  management.  The  average  power  of  fusion 
may  be  rated  as  equivalent  to  one  ton  per  hour,  and  the  furnace  can  be  tapped,  according  to  circum- 
stances, (size,  <fec.,)  every  two  to  four  hours. 

If  the  scope  and  practical  appliance  of  these  three  methods  of  founding  be  compared,  it  may  be 
said  that, 

1.  The  employment  of  crucibles,  very  costly  in  materials,  though  not  in  construction,  is  limited  to 
small  objects,  whose  price  bears  no  comparison  to  the  weight  of  metal  out  of  which  they  are  made. 

2.  Cupolas,  which  are  rather  the  most  expensive  in  construction  and  maintenance,  are  yet  worked 
more  regularly  with  a less  proportionate  expense  for  wages,  and  are  the  most  universally  applicable 
for  all  objects  of  ordinary  demand  ; and, 

3.  Reverberatory  furnaces  are  especially  required  for  castings  of  the  heaviest  sort,  where  the  max- 
imum resistance  of  the  metal  is  demanded. 

In  all,  the  same  general  principles  apply  in  the  management  of  the  metal  before  and  after  fusion. 
Thus,  the  mixture  or  charge  of  different  kinds  of  crude  iron  is  a point  of  great  importance,  both  as 
regards  fusibility,  and  the  properties  of  the  cast-iron  run  out.  Castings  will  hardly  ever  be  made  from 
one  sort  of  pig  only  ; at  least  two,  and  often  six  or  eight  sorts  are  charged  together.  This  is  a matter 
dependent  upon  the  practical  experience  and  judgment  of  the  founder,  for  which  no  written  rules  serve. 

So  also  the  pouring  of  the  iron,  or  conveying  the  melted  metal  to  the  flasks,  is  independent  of  the 
kind  of  furnace  in  which  it  may  have  been  fused,  and  is  determined  by  the  quantity  required  to  be 
poured  at  once,  and  the  character  of  the  casting,  whether  it  is  to  be  open,  or  in  close  moulds.  Very 
large  objects,  with  plane  surfaces,  (such  as  girders,  plates,  <&e.,)  are  generally  cast  open  in  sand-moula^ 
and  the  metal  runs  through  a gutter  (frequently  itself  of  iron)  lined  with  sand,  after  the  same  fashion 
with  the  sow  and  pig  casts  from  the  high-furnace.  But  when  the  surfaces  are  curved  or  re-entering, 
(as  cylinders,  &c.,)  it  is  best  to  pour  from  ladles.  These  ladles  vary  in  size,  and,  of  course,  in  manage- 
ment, according  to  their  purpose.  A hand-ladle,  which  is  wielded  by  one  man,  will  contain  from  50  to 
60  pounds ; a double  hand-ladle,  or  shank,  managed  by  three  or  four  men,  carries  from  200  to  400 
pounds ; ladles  holding  four  or  five  tons  travel  in  a crane.  The  handles  or  pivots  of  all  these  are  placed 
a little  above  the  centre  of  gravity  of  the  ladle  when  charged,  so  that  they  may  be  easily  tilted.  With 
the  smaller  ladles,  accidents,  either  to  the  workmen  or  the  contents,  are  rare ; the  largest  are  now  so 
improved  with  tangent-screws,  worm-wheels,  and  skimmers,  as  to  render  their  management  even  easier 
than  that  of  the  smaller  ones. 

The  whole  business  of  making  patterns  and  moulds  is  the  same  in  principle  for  all  metals,  and  belongs 
to  the  article  Moulding.  Only  such  particulars  will  be  summarily  mentioned  here  in  which  the  casting 
of  iron  differs  more  or  less  from  the  founding  of  other  metals. 

The  patterns  for  iron-castings,  besides  being  made  so  as  to  draw  readily  from  the  mould,  are  made 
larger  than  the  intended  casting,  by  an  average  scale  of  |th  inch  per  foot.  This  is  to  allow  for  the 
contraction  of  the  metal  in  cooling.  In  strictness,  every  particular  mixture  has  its  own  proportionate 
contraction,  and  when  a foundiy  is  running  upon  the  same  mixture  and  article,  the  pattern  is  dressed 
to  suit;  but  the  proportion  which  is  given  is  the  one  generally  adopted.  The  pattern-maker,  in  getting 
the  proportion,  simply  uses  a contraction-rule,  whose  divisions  of  feet  and  inches  are  everywhere  l-96tb 
longer  than  the  true  measurement.  In  this  way  he  works  directly  from  the  measurements  given,  with- 
out any  trouble  of  calculation.  In  making  a pattern  of  wood  from  which  to  cast  an  iron  pattern,  to  be 
used  afterwards,  a double  shrinkage  is  to  be  allowed  for,  and  a double  contraction-rule,  with  divisiptm 
1-4  8tli  in  excess  everywhere,  is  employed. 


110 


IRON. 


Patterns  for  iron-castings  require  to  be  more  carefully  designed  as  to  symmetry  and  equality  of  parts, 
and  distribution  of  material,  than  for  any  other  metal,  partly  because  of  the  heavier  stress  upon  the 
objects  in  use,  and  partly  because  of  the  peculiar  behavior  of  the  metal  itself  in  cooling.  It  is  easy  tc 
see  that  a small  external  stress,  coming  upon  a material  already  strained  by  its  own  shrinkage,  will 
cause  it  to  give  way.  Inattention  to  these  considerations  is  the  frequent  cause  of  breakages  in  the 
wheels  for  railroad  cars.  In  planning  a pattern  other  than  for  simple  prismatic  figures,  regard  should 
always  be  paid  as  to  which  parts  are  to  endure  extension,  and  which  compression.  The  latter  may  be 
made  thin,  and  be  allowed  to  chill ; but  the  parts  to  resist  extension  should  be,  as  far  as  possible,  com- 
pressed in  the  mould,  and  escape  chilling.  For  instance,  a T-shaped  cast-iron  joint  is  a bad  shape  at 
best  for  strength,  but  its  resistance  is  still  less  when  the  vertical  leg  is  downwards.  In  general,  patterns 
for  castings,  if  at  all  complicated,  should  be  regarded  as  systems  of  framing;  and  in  combining  the 
several  parts,  it  should  be  remembered  that  the  strength  of  the  whole  can  never  exceed  the  weakness 
of  the  weakest  part. 

In  taking  impressions  from  these  patterns,  or  moulding  the  object  desired  to  be  produced  in  metal, 
the  processes  are  the  same  for  iron  as  for  other  metals,  regard  being  had  to  the  heavier  masses  required 
of  the  former,  and  also  to  its  different  affection  by  heat.  In  this  last  particular,  moulds  for  cast-iron 
need  not  be  so  dry  as  for  other  metals.  The  sand  employed  is  also  coarser,  and  less  adhesive.  Sand 
for  partings  in  the  mould  is  generally  that  which  is  scraped  off  from  former  castings,  and  which,  having 
been  once  exposed  to  a full  red-heat,  and  mechanically  triturated  in  the  rough  processes  of  scraping, 
has  become  less  sharp.  The  best  facing-sand  is  charcoal  and  coal-dust  in  equal  parts,  ground  fine,  and 
intimately  mixed.  For  small  articles  of  luxury,  the  best  facing  is  graphite. 

Cores,  which  are  prismatic  or  cylindrical  pieces  inserted  in  the  mould,  to  produce  the  holes  and  open- 
ings in  the  casting,  and  in  general  intercept  the  flow  of  the  metal,  may  be  made  of  any  material  which 
does  not  alter  its  shape  or  volume  materially  when  exposed  to  heat.  The  best  for  iron-castings  are 
made  of  sand,  horse-dung,  and  a little  loam.  After  being  shaped  they  are  dried,  and  then  put  in  a 
crucible  and  burned  for  ten  or  twelve  hours,  in  order  to  consume  all  the  vegetable  matter,  and  leave 
them  in  a proper  porous  condition,  both  for  their  own  permanence,  and  also  the  escape  of  air. 

Castings  of  ordinary  objects  are  made  in  iron  moulds  or  in  sand;  very  heavy  objects,  such  as  cyl- 
inders, Ac.,  are  moulded  in  loam.  Of  the  use  of  iron  moulds,  the  running  of  bullets  is  a familiar,  but 
perhaps  the  best  illustration,  though  it  is  ordinarily  exemplified  with  other  metal  than  iron.  This  kind 
of  mould  is  applied  advantageously  to  the  casting  of  heavy  shot  and  shells,  (which  will  be  treated  ot 
more  particularly  under  the  title  Projectiles,)  to  tram-plates  and  chairs  for  railway  bars,  and  to  railway 
wheels.  In  these  last  the  outer  rim  only  is  often  made  of  iron,  and  the  nave  and  spokes  cast  in  sand 
upon  an  iron-core,  the  object  here  being  chiefly  to  chill  the  tire  of  the  wheel.  Another  object,  plough- 
shares,  are  advantageously  cast  in  iron  moulds,  so  also  are  cylinders  for  rolling  metal,  forge-hammers, 
ore-stampers,  Ac.,  and  in  general  all  objects  which  have  a sufficient  mass  of  matter  to  resist  impact  oi 
compression,  and  require  in  use  the  hardest  and  least  wearing  surface. 

Sand-mouldings  (we  do  not  speak  here  of  those  objects,  plates,  joists,  Ac.,  which  may  be  run  open) 
are  made  in  flasks,  which,  for  iron-founders’  use,  are  best  made  themselves  of  iron,  but  in  other  respects 
like  the  wooden  ones  used  in  foundries  generally.  The  bottom  flask  or  drag  has  generally  plain,  flat 
cross-ribs,  to  serve  instead  of  a bottom-board ; the  top  flask  has  deep  cross-ribs  cutting  it  up  into  compart- 
ments five  or  six  inches  wide  and  twenty  to  thirty  inches  long,  with  little  fillets  on  their  sides  to  lock 
in  the  sand  more  effectually ; middle  flasks  have  no  such  compartments  at  all.  Of  these  middle  flasks 
the  iron-founder  makes  frequent  use.  They  constitute  the  three  or  four  part  flasks,  which  are  much 
more  convenient  for  many  objects  than  two-part  flasks  only,  which  might  have  to  be  of  excessive  depth. 
The  cottering,  or  fastening  these  parts  together,  is  easily  effected  by  transverse  wedges  in  the  steady- 
pins  of  the  flasks,  and  the  internal  mass  of  sand  is  retained  firmly,  or  gagged,  by  means  of  lifters,  or 
T -shaped  pieces  of  iron,  with  wedge-shaped  tail,  and  set  head  downwards.  These  gaggers  are  placed 
in  various  parts  of  the  flask,  according  to  the  objects  to  be  moulded,  and  the  discretion  of  the  founder. 

The  following  figures,  showing  the  pattern  and  mould  for  the  top  of  a sliding-rest  for  a lathe,  will 
illustrate  the  application  of  a three-part  flask. 

The  pattern,  Fig.  2383,  might  be  moulded  in  a two-part  flask  of  sufficient  depth  by  making  the 
parting  along  the  dotted  line  a a ; and  indeed  there  are  several  ways  in  which  it  might  be  cast,  but  the 
one  shown  will  be  seen  to  be  the  most  convenient.  The  chamfer  at  c might  also  be  cast,  either  by 
moulding  square  at  first,  and  then  filling  in  sand  and  working  it  to  a gage,  or  by  means  of  a core 
whose  print  is  shown  in  the  dotted  lines  terminating  at  b ; but  the  most  usual  and  the  best  way  is  to 


“383. 


cast  it  square,  and  plane  it  to  the  required  bevel  afterwards.  That  being  the  case,  Fig.  2384  '’hows  the 
flasks  1,  2,  3,  alter  they  are  put  together.  In  working  them,  1 and  2 are  first  set,  nearly  fLled  with 


IRON. 


Ill 


sand,  and  the  pattern  knocked  in  as  shown,  the  -whole  well  rammed,  and  the  parting  made  along  a a. 
The  flask  3 is  then  added,  tilled  and  rammed,  levelled,  covered  with  a board,  and  all  three  turned  over, 
so  that  1 becomes  the  top,  which  is  now  taken  off,  a parting  made  along  the  line  b b,  and  the  runner- 
stick  put  in  to  make  the  runner  or  in-gate,  as  shown  by  the  dotted  lines  near  r.  To  prepare  for  casting 
the  runner-stick  is  taken  out,  flask  1 is  lifted  off,  and  the  part  of  the  pattern  (shown  white)  is  taken  out 
from  the  middle  flask ; the  middle  flask  is  then  removed,  and  the  shaded  part  of  the  pattern  (which  has 
been  fitted  by  pins  or  lugs,  as  shown)  is  taken  out  from  flask  3 or  the  drag.  The  flasks  are  then  united, 
and  the  pouring  made  through  r.  It  is  manifest  that  the  same  system  would  be  pursued  with  a flask 
having  a greater  number  of  parts. 

The  iron-founder  has,  from  the  vast  variety  of  works  which  he  is  called  on  to  execute,  greater  occasion 
than  others  to  use  a variety  of  methods  of  coring.  The  following  figures  will 
illustrate  some  of  these,  and  will  indicate  how  others,  more  complicated  still, 
are  met  and  accomplished.  Thus,  Fig.  85  shows  the  finished  casting  which  is 
desired  to  be  produced,  and  Fig.  2386  tne  pattern,  with  its  core-prints  for  pro- 
ducing it.  The  horizontal  print  a delivers  itself,  but  one  made  like  the  left-hand 
vertical  one  b,  would  tear  up  the  sand  in  the  attempt  to  remove  the  pattern 
from  the  mould.  The  right-hand  print  d,  therefore,  shows  the  proper  shape  and 
length,  reaching  down  to  the  bed  of  the  pattern.  The  circular  opening  has,  in 
the  same  manner,  a tapering  print  of  the  same  length.  These  prints,  if  we  sup- 
pose the  pattern  inverted,  will  leave  a recess,  as  shown  at  d in  Fig.  2387.  Upon  being  drawn,  the 
cores  are  inserted  as  in  Fig.  2388,  (a  section  through  d,)  the  upper  part  of  the  recess  is  made  good  with 
sand  to  the  general  surface,  and  the  mould  is  ready  for  casting. 


238G. 


2388. 


2387. 


2389. 


By  observation  and  practice  moulders  become  exceedingly  expert  in  managing  their  patterns,  drc., 
and  often  display  remarkable  ingenuity  in  the  shifts  and  contrivances  to  which  they  resort  for  eking  out 
or  stopping  off  patterns,  or  for  moulding  additional  parts  for  which  there  is  no  pattern.  Indeed,  as  one 
of  the  heavy  items  of  expense  in  a foundry  is  for  a stock  of  patterns,  it  is  not  unusual,  for  avoiding  this, 
to  see  many  common  articles  of  simple  form,  (grates,  parts  of  stove-plates,  etc.,)  which  are  made  upon 
written  orders,  built  up  with  core-prints  or  slips  of  wood,  and  moulded  almost  entirely  by  hand. 
Wherever  accuracy  is  required,  however,  well-made  patterns  are  indispensable. 

The  objects  which  are  moulded  in  sand  and  cast  in  flasks  are  too  numerous  to  be  mentioned.  They 
comprehend  nearly  all  the  articles  of  cast-iron  in  ordinary  or  domestic  use.  Before  leaving  this  branch, 
another  illustration  of  flask-casting  of  the  last-mentioned  class  of  articles  may  be 
of  interest  to  some  readers,  viz.,  the  manufacture  of  iron  pots.  Fig.  2389  will 
give  an  idea  of  the  implements  in  this  process.  The  pattern  for  the  pot  (which 
is  of  metal,  for  wood  could  not  be  turned  down  well  to  the  thinness  of  these 
vessels)  exists  in  two  hemispheres,  which  fit  and  are  fastened  together  in  the 
oblique  dotted  curve  shown  in  the  figure.  The  moulder  takes  these  and  places 
them  together,  mouth  downwards,  upon  a board  which  has  a bevel-rim  just  fit- 
ting the  mouth  of  the  pot.  On  the  same  board,  he  places  symmetrically  over 
the  pattern  the  flask  a , which  is  in  two  pieces,  as  shown.  Sand  is  rammed  down 
round  the  pattern  till  the  flask  is  full,  when  a parting  is  made  even  with  its  top, 

and  flask  b is  placed  on  and  fastened.  This  is  filled  in  like  manner,  prints  for  ._ 

the  feet  and  a runner-stick  having  been  put  in  at  the  proper  levels.  The  top  of  ViiiiijVyj 
b is  levelled  off,  a board  placed  on  it,  and  the  whole  concern  inverted.  The 
board  that  originally  served  as  the  drag,  and  upon  which  a and  b have  been  built,  is  removed,  the 
interior  of  the  pot  is  seen,  and  the  flask  c is  set  around  its  mouth  upon  a.  The  pot  is  then  filled  with 
sand  and  rammed  to  the  edge  of  c,  when  it  is  all  strickled,  (i.  e.,  levelled  off,)  a drag-board  placed  on  it. 
and  the  whole  reverted  to  its  former  position,  as  seen  in  the  cut.  In  drawing  the  pattern,  b comes  off 
first,  out  of  which  the  core-prints  are  also  taken ; a takes  apart  and  leaves  the  pattern  exposed,  which 
comes  out  in  halves.  The  convex  and  concave  moulds  are  then  dressed  with  tools  and  facing-sand,  the 
flasks  replaced,  the  runner-stick  taken  out,  and  the  whole  is  ready  for  casting.  In  spite  of  the  apparent 
complexity  of  all  this,  it  is  by  no  means  among  the  costlier  or  more  difficult  works  of  the  foundry. 

Articles  that  are  heavy  or  large  have  to  be  moulded  in  loam,  as  it  is  termed ; and  as  such  things  are 
generally  required  to  be  cast  vertically,  while  the  quantity  of  metal  is  too  great  to  be  ladled,  it  is  more 
convenient  to  dig  a pit  for  the  mould  to  which  the  metal  may  be  led  by  gutters,  than  to  raise  the  fur- 
nace foundations  high  enough  to  have  all  the  work  above  ground.  Indeed,  as  works  have  sometimes  to 
be  executed  fifteen  and  even  twenty  feet  high,  this  last  arrangement  would  be  well  nigh  absurd.  So 
far  as  resistance  is  concerned,  pit-moulding  is  advantageous;  and  if  due  provision  be  made  for  the  es- 
rape  of  elastic  gases,  it  is  not  more  objectionable  on  the  score  of  danger  than  large  flasks  above  ground 
The  great  merit  of  this  method  is,  however,  in  dispensing  with  a solid  pattern,  which,  for  such  cylinders, 
for  instance,  as  are  used  in  Cornish  engines,  of  eight  feet  diameter  and  fifteen  feet  stroke,  would  be  an 


112 


IRON. 


enormous  expense.  The  following  figures  will  serve  to  explain  the  general  process  of  loam-moulding. 
Fig.  2390  shows  the  first  stage  of  the  mould  for  a steam  or  blast  cylinder.  The  lowest  lines  represent 
the  bed  of  the  loam-plate,  upon  which  the  inner  wall  is  built.  This  inner  wall,  for  small  works,  such  as 
pipes,  is  called  the  core , for  large  cylinders  it  is  termed  the  nowel.  The  loam-plate  is  of  iron,  cast  rough, 
and  with  projecting  ears  for  lifting  it.  Sometimes  these  plates  are  raised  from  the  ground,  to  allow  of 
a fire  for  drying  the  loam  to  be  made  up  beneath ; or  if  the  work  be  not  too  large,  it  is  set  upon  a 
wheeled  truck,  by  which  it  may  be  rolled  into  the  loam-stove.  Upon  this  truck,  or  on  the  loam-plate, 
or  in  any  convenient  and  steady  manner,  a spindle  a is  fixed,  which  carries  the  templet  b b , whose  dis- 
tance from  the  centre  is  adjusted  exactly  to  the  internal  radius  of  the  intended  cylinder.  An  inner  wall 
of  brick-work  is  then  built,  whose  face  is  plastered  with  soft  loam,  which  loam  is  shaped  and  turned  by 
the  motion  of  the  templet.  When  smooth  it  is  thoroughly  dried,  and  then  brushed  over  with  black- 
wash  of  charcoal  and  coal-dust,  to  be  dried  again,  and  serve  as  a parting  to  prevent  the  adherence  of 
fresh  loam.  This  finishes  the  mould  for  the  inside  of  the  cylinder. 

The  templet  b b is  then  dismounted,  and  another  cc,  Fig.  2391,  cut  in  profile  to  the  external  form  of 
the  cylinder,  with  flanges,  and  bosses,  <fcc.,  is  attached  to  the  spindle  at  a distance  from  the  centre  ex- 
actly corresponding  to  the  radius  of  the  cylinder, plus  its  intended  thickness.  Fresh  loam  is  then  thrown 
on  the  nowel-mould,  in  order  to  form  the  thickness,  which  is  shaped  on  the  outside  by  the  revolutions  of 
the  templet,  carefully  smoothed,  dried,  and  black-washed  as  the  other. 


When  this  is  finished,  a loam-plate  or  ring  is  laid  down  to  carry  the  outer  case  or  cope,  as  shown  in 
Fig.  2392.  This  cope  is  built  up  of  brick  and  loam,  with  an  inner  facing  of  loam  worked  carefully  to 
the  turned  thickness  ; it  is  then  thoroughly  dried,  and  lifted  off  carefully  from  the  nowel.  This  is  done 
by  means  of  a crane.  The  thickness  comes  off  with  the  cope,  generally  broken,  but  it  has  now  answered 
its  purpose.  Any  accidental  damage  to  either  of  the  moulds  is  repaired,  the  faces  are  black-washed 
and  dried  again,  and  the  mould  is  ready  to  be  put  together,  the  position  of  the  cope  having  been  deter- 
mined at  first  either  by  studs,  or  by  marks  upon  the  nowel-plate. 

Ports  at  the  ends  of  the  cylinder  (or  short  flanged  tubes  for  attaching  the  steam  or  blast  pipes)  are 
made  by  working  the  patterns  into  the  cope ; the  cores  are  supported  either  by  grains  (which  are  little 
plates  of  sheet-iron  staid  by  wire,  and  as  wide  as  the  thickness  of  the  metal  at  the  port)  or  by  sand- 
bearings,  the  holes  left  by  which  are  afterwards  plugged  up.  From  the  precariousness  of  the  union  of 
the  melted  metal  with  that  of  the  wire  and  sheets,  the  use  of  grains  is,  when  possible,  to  be  avoided. 
Other  passages  for  steam  or  air,  either  in  the  side  or  around  the  cylinder,  can  be  worked  in  a similar 
manner  upon  the  thickness,  and  be  covered  in  by  the  cope. 

When  all  is  ready  the  mould  is  put  together  in  the  pit,  the  two  plates  bolted  together,  and  the  ex- 
ternal space  in  the  pit  rammed  hard,  to  resist  the  outward  pressure  of  the  melted  metal.  In  very  large 
works  there  are  iron  rings,  larger  than  the  cope,  piled  one  on  another  to  hold  the  sand ; these  rings  are 
steadied  by  numerous  stays  going  to  the  sides  of  the  pit,  which  is  sometimes  itself  walled  up  with  brick, 
or  even  cased  with  iron.  In  such  works  the  core  too  has  to  be  strengthened  by  iron  stays  laid  in  diam- 
eters, and  entering  the  brick-work  of  the  nowel. 

The  metal,  in  pouring,  is  led  in  various  ways  to  the  mould,  according  to  circumstances,  from  the  sow 
or  main  runner.  Sometimes  there  is  a circular  trough  round  the  top  of  the  mould,  and  the  feeding  is 
through  holes  in  the  loam-cake  ; sometimes  the  runners  are  sunk,  and  enter  the  mould  at  about  one- 
third  of  the  height  from  the  bottom  and  tangent  to  the  circumference.  This  is  supposed  to  be  a good 
way  to  keep  the  metal  in  circulation,  and  clear  of  the  scorise  or  sullage.  Sometimes,  to  supply  hydro- 
static pressure  for  condensation,  or  shrinkage  in  cooling,  iron  rings  are  piled  up  to  inclose  a lofty  runner. 
In  the  largest  works  several  such  reservoirs  or  feeds  are  made  in  addition  to  the  runners,  purposely  to 
provide  for  shrinkage.  Sometimes  a piston  has  been  applied  in  the  runners,  when  they  are  not  numer- 
ous ; and  a still  better-intended  process  has  been  proposed — that  of  exhausting  the  air  from  the  mould, 
and  supplying  the  feed  from  below. 

Both  of  these  methods — which  have  never  come  into  general  use — aim  at  accomplishing  perfectly 
what  the  founders  ordinarily  obviate  by  other  contrivances,  viz.,  the  expulsion  of  the  air  from  the  mould. 
If  the  air  or  vapor  in  small  quantities  gets  entangled  in  the  metal,  it  produces,  of  course,  a bad  casting, 
leaving  cavities  in  the  mass  such  as  we  very  often  see.  If  large  quantities,  especially  of  steam,  are 
caught,  the  consequence  is  a greater  or  less  explosion,  sometimes  attended  with  very  disastrous  conse- 
quences. The  Thorncliffe  accident  in  1820  is  still  remembered  in  the  annals  of  founding  as  one  of  the 


IRON. 


113 


saddest  of  such  catastrophes.  Upwards  of  100  persons  were  in  the  cast-house  at  the  time,  to  witness 
tire  pouring  of  a tilt-shaft  of  about  live  tons  in  a vertical  mould.  The  cast  was  nearly  finished  when 
the  explosion  took  place,  and  some  four  tons  of  melted  iron  shot  out  as  from  a petard,  killing  and 
wounding  terribly  about  one-fourth  of  those  present.  There  happened  to  be  a thunder-storm  at  the 
time,  and  as  no  one  knew  of  any  mistake  committed  in  any  of  the  arrangements,  the  accident  was  at- 
tributed to  that  indefinite  agent,  electricity.  It  more  likely  arose  from  a sudden  and  explosive  combi- 
nation of  carburetted  hydrogen,  a gas  which  is  always  formed  in  the  moulds.  The  workmen  are  very 
well  aware  of  this,  and  in  casting,  for  example,  the  thick  cylinders  for  a hydrostatic  press,  which  are  set 
mouth  downwards  generally,  the  air-tube  or  tubes  which  are  made  to  come  up  from  the  core  underneath 
to  the  surface  are  ignited  for  greater  safety,  and  bum  like  perfect  gas-torclies.  In  small  works  this  is 
not  so  manifest,  and  in  these,  by  making  openings  similar  to  and  corresponding  with  the  runners,  the 
metal  flows  through  the  mould,  and  drives  out  the  greater  quantity  of  the  air  and  gas  before  it.  In 
larger  works  the  air-chamber  is  generally  provided  below,  underneath  the  nowel-plate,  by  laying  there 
i mass  of  hay-bands,  with  which  air-tubes,  leading  to  the  surface,  immediately  communicate.  But  the 
i-se  of  this  combustible  matter  cannot  be  recommended  on  the  score  of  security. 

The  temperature  proper  for  pouring  is  slightly  different  for  every  mixture ; it  can  be  judged  of  only 
by  experience : at  least  it  cannot  be  defined  by  any  written  rules  of  universal  application.  The  rate  of 
pouring,  too,  is  in  the  same  category.  In  general,  bad  castings  (i.  e.,  blown  and  spongy)  are  apt  to  be 
made  by  quick  pouring  of  hot  metal,  and  imperfect  ones  by  slow  pouring. 

The  necessity  of  providing  sufficient  resistance  to  all  sides  of  the  mould  during  pouring  has  been 
already  spoken  of.  After  pouring,  however,  the  condition  becomes  inverted,  for  the  metal  is  then 
shrinking  into  itself.  The  pressure  from  without  is  generally  nothing ; but  that  from  within  must  be 
removed,  that  the  cylinder  be  not  strained,  or  scored.  So,  in  two  or  three  hours,  according  to  the  size  of 
the  work,  the  iron  stays  within  the  core  are  knocked  away,  and  the  workmen  go  down  to  break  away 
the  brick-work.  The  excessive  heat  renders  this  the  most  dreadful  of  their  duties. 

Loam-casting,  suitably  modified,  is  applied  to  all  large  works  with  curved  surfaces,  such  as  cylinders 
of  all  sorts,  large  pans,  guns,  pipes  for  water,  gas,  &c.,  dx.  Guns  have  been  cast  with  a core,  like  cyl- 
inders, but  their  imperfections  are  such  as  to  make  it  more  advantageous,  in  spite  of  the  waste  of  metal, 
to  run  them  solid  and  bore  them  out  afterwards.  The  cores  for  pipes  are  usually  made  upon  an  iron 
tube  pierced  with  holes,  wound  round  with  hay-bands,  and  revolved,  while  the  loam  is  being  applied, 
by  a winch  at  the  end,  upon  two  iron  trestles.  A scraper,  fixed  parallel  to  the  axis,  turns  off  the  loam, 
and  brings  the  core  to  its  true  cylindric  shape.  This  arrangement,  which  is  susceptible  of  more  accu- 
racy, is  the  founder's  lathe.  These  cores  are  dried  and  blaekwashed  ; the  thickness  is  laid  on  in  loam, 
and  also  dried  and  blaekwashed  ; and  the  object  is  then  moulded  in  sand  in  an  iron  box  parting  in 
half.  The  core  is  then  taken  out,  the  thickness  removed,  and  the  core  replaced,  and  held  in  place,  if 
necessary,  with  grains.  In  establishments  where  pipes  are  cast  in  large  quantities,  it  is  usual  to  mould 
from  wooden  patterns  in  halves. 

Within  a short  period,  a method  has  been  tried  of  casting  pipes  inside  of  an  iron  pattern,  whicli  is  laid 
with  a slight  slope,  and  caused  to  revolve  while  the  metal  is  fed.  Its  revolutions  inspire  a centrifugal 
tendency  to  the  melted  metal,  which  is  restrained  and  shaped,  as  it  cools,  by  the  pattern.  The  precari- 
ousness of  result,  however,  or  some  other  cause,  appears  to  have  restricted  the  economical  use  of  this 
method. 

The  scope  of  the  iron-founder’s  art  is  exceedingly  comprehensive,  both  as  to  the  forms  he  produces, 
and  the  weight  of  metal  he  has  to  deal  with.  Thus,  castings  are  sometimes  required  of  20  and  even 
30  tons  in  one  piece,  requiring  the  conjoint  operation  of  three  or  four  furnaces  tapped  at  one  time.  On 
the  other  hand,  the  beautiful  Berlin  ornaments  are  cast  in  pieces  of  a few  grains  weight.  The  art  of 
casting  these  ornaments  was  first  developed  in  Prussia,  and  is  supposed  to  depend,  in  some  degree, 
upon  the  quality  of  the  iron  and  of  the  sand  employed.  The  latter,  as  well  as  the  ores  (bog-ores)  out 
of  which  the  former  is  reduced,  is  not  only  fossiliferous,  but  appears  to  be  constituted  entirely  of  the 
remains  of  atiimalculas.  But  there  are  examples  of  successful  castings  of  the  smallest  size  with  mate- 
rials where  this  infusorial  influence  could  not  be  suspected  of  operating. 

The  following  figures  exhibit  one  of  these  Berlin  chains  entirely  of  castings  (many  of  those  on  sale 
will  be  found  to  have  been  connected  with  iron  wire) : its  length  is  4 feet  10  inches,  and  its  whole 
weight  130  grains;  a large  and  small  link  together  weigh  a little  over  8 grains.  Fig.  2393  shows  the 

2393.  2394. 


chain  itself;  Fig.  2394  is  intended  to  explain  the  way  it  was  worked.  The  large  links  a a (Fig.  2393) 
were  first  cast  separately.  Then  a pattern  of  the  chain  with  core-prints  b (Fig.  2394)  was  moulded. 
The  links  a,  smoked  to  prevent  adhesion  of  the  metal,  were  laid  in  the  mould,  and  then  the  sand-cores,  b. 
The  actual  mould  was  about  8 inches  long,  and  a separate  runner  was  made  to  every  one  of  the  small 
links  c c.  Such  things  are  even  greater  wonders  of  art  than  the  larger  works. 

When  castings  are  set  and  cooled,  the  next  thing  is  to  remove  them  from  the  moulds  ; the  runners 
are  snapped  off,  and  all  the  loose  sand  scraped  from  the  casting,  and  the  seams  of  partings  smoothed 
For  common  castings,  very  rough  implements  serve ; for  the  finer  kinds  more  appropriate  tools  are 
required.  To  these,  the  skin  left  from  a sand-mould  is  very  destructive ; and  therefore,  if  they  are 
intended  to  be  wrought,  they  are  generally  first  pickled  with  dilute  sulphuric  acid — by  immersion  it 
Vol.  II. — 8 


114 


IRQ*. 


they  are  small,  and  aspersion  if  large.  The  acid  attacks  the  metal  underneath  ; and  the  crust  that  is 
left  after  a day  or  two  is  easily  removed. 

The  skin  of  castings  from  sand-moulds  is  always  harder  than  from  loam.  This  is  not  so  much  front 
the  siliceous  matter  taken  up  in  the  surface,  as  from  the  effect  of  a different  conduction  of  heat,  and  a 
change  of  crystallization  at  and  near  the  surface,  which  is  known  as  chilling.  These  chilled  castings 
have  been  already  mentioned  : it  only  remains  to  speak  of  the  malleable  iron  castings  which  are  pro- 
duced at  a few  establishments. 

The  malleability,  which  is  in  some  respects  the  reverse  of  chilling,  in  general  follows  the  abstraction 
of  carbon,  and  is  proportionate  to  it ; but  the  metal  so  produced  lias  none  of  the  fibre  which  is  caused 
by  forging  and  laminating.  Like  chilling,  the  change  is  external,  and  penetrates  but  a small  way  ; the 
methods,  therefore,  are  applicable  only  to  light  and  thin  articles.  There  are  many  such  (brads,  bridle- 
nits,  coach-makers’  fastenings  and  furniture,  locks,  snuffers,  stirrup-irons,  (fee.,  and  various  vessels  in 
domestic  use)  which  can  be  cast  more  cheaply  and  conveniently  than  forged  : to  all  these  the  method 
applies. 

It  reposes  both  upon  the  character  of  the  crude  iron  and  upon  processes  subsequent  to  casting.  Gray 
crude  iron  produced  from  refractory  ores,  which  never  can  be  chilled,  is  the  suitable  quality  ; and  arti- 
cles cast  from  this,  which  are  at  first  brittle,  are  enclosed  in  iron  boxes,  in  contact  with  powdered  oxides 
of  iron,  (either  mineral,  as  red  hematite,  or  artificial,  as  forge-cinder,)  with  lime,  or  with  any  absorbents 
of  carbon.  The  cases,  well  closed  and  luted,  are  placed  in  an  oven,  and  left  there,  at  a high  tempera- 
ture, for  a period  varying  from  three  days  to  a week.  The  temperature  is  then  allowed  to  subside, 
and  the  matters  to  cool  gradually  in  the  ovens.  When  pieces  of  these  castings  are  fractured,  the  alter- 
ation of  structure  is  very  apparent. 

III.  Refining,  Forging,  <fcc.,  of  Malleable  Iron. — The  mention  of  malleable  iron  castings  leads 
naturally  to  the  account  of  those  processes  by  which  a malleability  is  imparted,  higher  both  in  kind  and 
degree.  These  processes  apply,  1st,  to  the  production  of  iron  which  can  be  wrought  directly  from  suit- 
able ores  ; as  well  as,  2d,  to  the  refining  and  working  of  crude  iron  which  has  been  otherwise  produced. 
The  fagoting  of  scrap-iron  is  not  sufficiently  distinctive,  either  chemically  or  mechanically,  to  constitute 
a third  class  of  processes. 

1.  Of  malleable  iron  directly  from  ores. — This  product  undoubtedly  preceded  any  other  manufacture 
of  iron.  All  the  workings  of  antiquity  were  of  this  sort,  there  is  reason  to  believe  ; and  what  has  been 
already  said  in  this  article  serves  to  show  the  gradual  advance  of  the  modern  epoch  of  crude  iron.  The 
improvement  in  this  epoch  has  been  the  utilization  of  many  ores  which,  under  the  old  process,  were 
unavailable.  Only  rich  and  fusible  mines — magnetic  oxides,  and  some  of  the  sparry  carbonates  and 
red  hematites,  and  the  like — admit  of  this  treatment.  This  restriction  will  be  justified  in  considering 
the  general  theoretical  aim  of  the  process,  which,  in  so  far  different  from  that  of  the  high-furnace,  em- 
1 'races  a double  task,  and  recurring  decompositions  and  recompositions.  In  the  high-furnace,  our  object 
is  to  drive  off  the  oxygen  from  the  ores  ; which  is  effected  by  preventing  carbon  in  excess  at  a high 
temperature,  while  that  portion  of  excessive  carbon  that  combines  with  the  iron  after  reduction  is  gotten 
rid  of  by  subsequent  separate  treatment.  But  in  the  forge-fire,  one  treatment  must  answer  both  ends ; 
carbon  at  the  lowest  temperature  that  will  answer  must  be  prevented  to  effect  an  imperfect  reduction 
at  first,  till  the  mass  consists,  in  fact,  of  a mixture  of  oxides  and  carburets  of  iron  ; and  while  this  mix- 
ture is  reacting  internally  on  itself,  additional  oxygen  from  a current  of  air  must  be  afforded  to  assist  in 
the  neutralization  of  the  carbon. 

To  this  aim,  the  character  of  the  furnaces  employed  must  conform  ; they  must  be  low,  so  that  the 
reduction  may  not  take  place  too  soon  and  fusion  be  checked  ; they  must  be  wide,  that  the  melting 
carburets  may  offer  a large  surface  to  the  action  of  the  air.  Where  exactly  the  fusion  is  maintained, 
is  not  of  so  much  moment : if  above  the  tuyere,  the  furnace  is  properly  a stuck-ofcn,  which  has  been 
already  described ; if  below  the  tuyfere,  it  is  to  be  termed  a forge-fire,  of  which  the  so-called  Catalan 
forge  may  be  taken  as  the  type.  Whether  one  or  the  other  form  be  used,  there  is  in  either  another 
characteristic  diversity  from  the  processes  of  the  high-furnace,  which  should  not  be  omitted.  In  the 
latter,  the  result  depends  upon  the  chemical  action  of  the  materials ; i.  e.,  upon  the  proportions  of  fuel 
and  mine,  and  the  temperature  which  is  kept  up  ; in  the  former,  the  chemical  reactions  are  chiefly  de- 
pendent upon  the  mechanical  agency  of  the  workman,  whose  business  it  is  to  expose  successively  the 
imperfectly  reduced  masses  to  the  influence  of  the  air.  Thus  the  reduction  and  the  refining  are  both, 
in  a measure,  mechanically  effected ; the  formation  of  too  much  crude  iron  at  once  is  cheeked  by  imme- 
diate admixture  of  oxide,  and  by  a judicious  management  of  the  blast ; and  the  result  depends  upon 
the  skill  with  which  this  is  done,  just  as  in  the  case  mentioned  in  a preceding  part,  where,  to  produce 
crude  metal  of  a particular  quality,  doses  of  suitable  materials  are  injected  into  the  crucible  of  a high- 
furnace. 

So  much  has  been  already  said  upon  the  stiick-ofen,  that  its  application  need  not  be  insisted  on  here, 
further  than  to  remark,  that  their  product  is  never  entirely  malleable  iron,  and  requires  a fresh  reheat- 
ing and  fusion  of  a part.  This  subsequent  process  results  in  the  formation  of  part  malleable  iron  and 
part  steel. 

The  furnaces  used  in  Sweden  and  Norway  for  this  purpose  are  also  properly  stiick-ofen,  and  the  re- 
sult similar.  In  some  places  of  these  countries,  thev  treat  a roasted  ore  with  wood  in  inverted  cone-like 
furnaces,  from  4 to  7 feet  high,  and  from  2J  to  5 feet  diameter  at  the  top. 

The  old  German  method  was  also  so  far  like  that  of  the  stiick-ofen,  in  requiring  actual  fusion ; but 
the  shape  of  the  hearth  was  different,  resembling  the  Catalan  forge-fire,  and  the  original,  apparently,  of 
the  modern  bloomery  fires  of  Pennsylvania.  There  was  also  another  method  used  still  in  Gallicia,  of 
interstratifying  the  ores  with  the  fuel  which  is  broken  fine  and  kept  almost  in  a pasty  state.  The  re- 
duced metal  filtering  slowly  through  this  paste  is  refined  by  the  current  of  air  directed  downwards 
towards  the  bottom  of  the  hearth. 

The  methods, -<fec.,  which  have  been  applied  from  time  immemorial  in  the  Pyrenees,  and  are  called 


IRON. 


115 


the  Catalan  method,  will  convey  a sufficient  idea  of  all  the  others,  which  are  but  modifications.  This  ap- 
pellation comprehends,  in  reality,  the  whole  arrangement  of  water-blasts,  tilt-hammers,  &c. ; but  the 
exposition  will  be  confined  for  the  moment  only  to  the  chemical  part  of  the  process,  or  the  production 
of  metal  ready  to  be  forged.  The  ores  are  generally  roasted  in  furnaces  or  ovens ; but  in  some  instances 
a compact  brown  hematite  has  been  used  raw.  The  results,  compared  with  roasted  mine,  do  not  appear 
advantageous.  When  the  ores  are  tolerably  pure,  they  are  usually  charged  in  the  furnace  within  a 
month  after  roasting ; but  pyritous  or  phosphated  mines  are  macerated,  i.  e.,  exposed  to  the  air,  and  fre 
quently  stirred  and  moistened  with  water  for  a twelvemonth.  Before  charging,  they  are  broken  up  into 
fragments,  like  small  nuts ; red  hematites  are  even  used  in  powder.  According  to  the  character  of  the 
ore,  earthy  matter,  argillaceous  or  calcareous,  is  added,  to  serve  as  a flux.  Throughout  the  Pyrenees, 
the  general  machinery  for  the  blast  is  the  trompe  that  has  been  already  described ; small  forge-fires  are 
sometimes  blown  with  leasher  bellows.  In  this  last  case,  to  maintain  a continuous  blast  and  furnish  a 
suitable  quantity,  two  tuyeres  are  required. 

The  following  figures  indicate  the  construction  of  these  Catalan  forges.  Fig.  2895  is  a ground  plan 
on  a scale  of  1-Soth  of  the  actual  size  of  the  forge-fires  used  in  the  Lower  Pyrenees.  Such  are  properly 
called  Navarrese  furnaces ; and  while  the  general  structure  is  the  same  for  all,  are  intermediate  in  di- 
mensions between  the  Spanish  Catalan,  which  are  smaller,  and  the  Biscaj'an  forges. 


Fig.  2396  is  a vertical  section  through  the  axis  of  the  tuyfere ; and  Fig.  2397  another  section  at  right 
angles  to  the  former.  In  Fig.  2395,  W W represents  the  wall  separating  the  forge-fire  from  the  blast 
machinery,  and  in  which  is  the  embrasure  for  the  tuyere.  The  hearth  is  usually  fined  with  cast  plates, 
and  the  counter,  or  side  opposite  the  tuyfere, 
of  flat  bars.  Sometimes  the  lining  of  these  is 
only  a refractory  sandstone ; but  the  cinder 
slope  (on  the  side  o of  the  tuyfere)  on  which 
the  workman  rests  his  ringers  and  bars,  is 
always  of  cast-iron.  The  aperture  o is  for 
the  discharge  of  cinder  into  the  embrasure 
beneath;  the  tuyere  1 is  a truncated  half- 
cone of  copper,  with  the  orifice  or  eye  circu- 
lar, from  1 1 to  2 inches  in  diameter.  The 
pressure  of  the  blast  varies  from  i lb.  to  1| 
lb.  per  inch. 

The  fewest  men  to  work  one  of  these  fires, 
not  counting  the  hammer-man,  is  three ; the 
greatest  number  employed  in  the  largest 
and  most  active,  is  eight.  In  beginning  to 
work,  the  hearth  has  first  to  be  heated  by 
keeping  it  two-thirds  full  of  ignited  charcoal 
for  4 or  5 hours.  The  fuel  is  then  thrown 
up  against  the  tuyhre  and  beaten  down  into 
an  inclined  plane  towards  the  counter.  Upon 
this  is  thrown  at  once  from,  one-half  to  three- 
fourths  of  the  charge  of  mine ; the  hearth  is 
heaped  up  with  charcoal ; the  cinder-tap  o 
stopped  with  clay ; and  the  blast  gradually 
let  on,  till,  in  about  two  hours,  it  attains  its 
maximum.  The  founder,  during  the  process, 
frequently  wets  the  charcoal  on  top  to  pre- 
vent its  burning  too  fast,  and  to  concentrate 
the  heat ; throws  on,  from  time  to  time,  the 
smaller  fragments  remaining  of  the  charge, 
near  the  tuybre  ; feels  with  a crow-bar  at  the 
bottom  of  the  hearth  for  the  cinder  and  met- 
a.1,  giadually  brings  the  charge  nearer  the  tuyfere;  keeps  the  tuybre  free ; and  about  every  quarter 
our  alter  cinder  has  commenced  to  show  itself,  taps  and  lets  it  off.  This  tapping,  after  the  whole 


116 


IRON. 


blast  is  on,  has  to  be  clone  more  frequently:  sometimes  every  five  minutes;  the  other  part  of  the  work, 
too,  goes  on  with  more  activity.  In  three  hours  the  whole  charge  is  melted  ; a bar  is  thrust  through 
the  charcoal  in  many  places  to  clear  the  metal  which  is  thus  gathered  up  on  the  bottom  of  the  hearth, 
and  worked  and  pressed  with  ringers  into  a sort  of  ball  or  loop.  This  takes  the  greater  part  of  an  hour 
when  the  heat  is  done,  the  charcoal  is  raked  over  against  the  counter ; and  the  loop  thus  cleared  is 
lifted  by  the  bar  to  which  it  adheres,  and,  if  necessary,  with  tongs,  and  carried  to  the  shingling-hammef 
to  be  forged.  In  the  Catalan  forges,  the  weight  of  these  loops  (or  markets)  is  from  100  to  150  lbs  • 
in  the  Navarrese,  from  180  to  250  lbs. ; in  the  Biscayan,  from  280  to  850  lbs. ; and  in  some  of  the  forges 
among  the  Eastern  Pyrenees,  as  much  as  425  lbs.  The  tilt-hammers  employed  weigh  from  600  to 
100  lbs.,  generally  of  cast-iron,  sometimes  of  wrought;  the  helve  and  fixtures  mostly  of  wood.  Besides 
these  are  used  smaller  lift-hammers,  for  working  smaller  bars,  called  martinets.  When  the  loop  is 
placed  under  the  hammer,  it  is  struck  at  first  slowly  to  condense  it  and  drive  out  the  cinder ; it  is  then 
forged  more  rapidly  into  the  shape  of  a prism,  12  to  18  inches  long,  and  6 to  8 inches  square.  This  is 
cut  in  two  by  a chisel  under  the  hammer ; the  pieces  carried  back  to  the  same  fire  as  a special  chafery, 
there  heated  and  successively  forged  again.  When  smaller  bars  are  wanted,  these  pieces  are  again 
cut,  reheated,  and  forged  under  the  martinet. 

The  charge  of  roasted  mine  for  each  heat  is,  with  the  Catalan  fire,  from  325  to  450  lbs. ; with  the 
Navarrese,  from  550  to  650  lbs.;  with  the  Biscayan,  from  750  to  900  lbs.;  and  with  the  largest  fires  of 
the  Eastern  Pyrenees,  an  average  of  1260  lbs.  But  the  economical  result  in  metal  is,  as  might  be 
expected,  against  the  large  charges.  The  smaller  fires  allow  six  and  sometimes  seven  heats  in  the  24 
hours,  and  give  about  90  per  cent,  of  the  metal  found  by  assay  in  the  ore  : the  larger  ones  never  more 
than  four  heats  in  the  same  time,  yielding  about  85  per  cent,  of  the  metal.  In  fuel,  there  is  less  con- 
sumption with  the  large  charges.  In  the  smallest  fires,  the  fuel  used  is,  on  an  average,  five  for  one  of 
mine ; in  the  larger  it  is  about  three. 

The  fuel  used  is  universally  charcoal.  Frequent  experiments  have  been  made  looking  to  the  substi 
tution  of  coke,  both  with  cold  and  hot  blast,  but  hitherto,  and  probably  of  necessity,  always  without 
success. 

2.  Of  malleable  iron  from  pig  or  crude  iron — produced  (a)  with  charcoal  in  open  forge-fires,  bloom 
eries,  <fec. ; (b)  with  coal  in  reverberatory  or  puddling  furnaces ; (c)  with  coke  or  coal  in  a special  fur- 
nace, termed  a finery,  or  run-out  fire,  and  then  in  a puddling-furnace.  The  object  is  the  same  in  all 
these,  viz.,  the  decarburation  of  the  metal,  (as  to  driving  oil'  other  impurities,  that  will  be  spoken  of 
specially  hereafter  ;)  and  the  methods  may  be  distinguished  into  two  classes — first,  where  the  metal  is 
refined  in  contact  with  carbon,  as  in  mode  a ; and,  secondly,  where  it  is  only  in  contact  with  heated  air 
and  inflamed  gases,  as  in  the  reverberatory  furnaces  of  modes  b and  c.  In  theory,  the  latter  method 
should  be  the  best,  so  far  as  quality  of  metal  and  economy  of  material  are  concerned  ; but  in  practice, 
the  former,  though  at  a greater  loss  and  expense,  is  the  most  successful  in  yielding  a good  article. 

In  regard  to  the  quality  of  crude  iron  most  advantageous  for  refining,  different  metallurgists  have 
expressed  different  opinions.  As  this  is  no  place  for  a lengthened  discussion  of  principles,  only  such 
statements  will  he  briefly  made  as  seem  to  accord  the  best  with  experience. 

Gray  iron  demands  a higher  temperature  for  fusion  than  white,  becomes  more  liquid,  and  requires 
more  blast  and  a longer  time  for  conversion.  White  iron  coagulates  more  readily,  and  passes  sooner  to 
the  malleable  state.  Whether  these  differences  arise  solely  or  chiefly  from  the  presence  of  the  free 
carbon  in  the  former,  is  not  the  question : it  is  certain,  however,  that  some  kinds  of  gray  iron  cannot  be 
refined  at  all  without  having  been  first  whitened  by  a special  process.  This  is  especially  the  case  witli 
coke  iron  ; and  the  finery  of  the  English  method  is  an  expedient  for  meeting  this  very  difficulty.  The 
best  qualities  for  easy  refining  are  white  iron,  produced  in  the  high-furnace  by  heavy  burden,  gray  pig, 
which  is  loose  in  its  texture  and  cavernous,  and  broken  castings  from  a cupola  or  crucible.  Next  come 
the  mottled  pig,  the  lamellar  and  loosely  crystallized  white  iron,  and  close-grained  gray  coke  iron 
Last  of  all  to  be  employed,  are  the  compact  crystallized  gray  pigs,  especially  those  made  with  coke  oi 
coal. 

No  flux,  properly  so  called,  is  employed  in  the  fusion  of  refineries  ; but  several  substances  are  occa- 
sionally introduced,  besides  the  air  and  charcoal,  to  act  as  chemical  reagents.  These  are,  for  instance 
the  rich  finery-cinder,  the  forge-cinder,  oxides  of  iron  and  manganese,  sand,  and  water.  Of  the  finery 
cinder,  only  that  is  useful  which  is  formed  after  fusion  is  perfect,  and  while,  in  fact,  the  loop  is  about  to 
be  drawn.  This  cinder  falls  to  the  lower  part  of  the  hearth  : rich  as  they  are,  containing  from  80  to 
90  per  cent,  of  magnetic  oxide,  they  are  not  displaced  by  the  iron,  and  may  be  left  in  the  hearth  after 
the  loop  is  removed.  If  drawn,  which  need  only  be  when  they  have  accumulated  to  a great  degree, 
they  must  be  tapped  for  very  low  down  ; when  tapped,  they  run  and  solidify  slowly,  and  take,  of 
course,  all  forms  readily.  Their  formation  in  the  hearth  is  indicated  by  the  silvery  sparks  in  which 
they  are  thrown  out  by  the  blast ; and  they  are  recognizable  afterwards  by  their  weight  and  semi- 
metallic  lustre.  These  present  to  the  refiner  the  best  reagent  for  coagulating  the  melted  metal  and 
bringing  it  to  nature.  A part  of  these,  also,  are  apt  to  adhere  to  the  loop,  from  which  they  are  broken 
off  and  driven  out  by  the  hammer,  and  are  very  apt  to  be  found  mixed  with  the  forge-cinder. 

The  oxides  of  iron  and  manganese  are  used  mainly  to  save  the  metal  which  is  otherwise  supplied 
from  the  pig  under  treatment  to  form  cinders.  Sand  is  used  sometimes  (and  acting  then  like  a flux) 
to  retain  the  metal  in  fusion ; but  this  is  bad  economy,  both  for  quantity  and  quality.  And  water, 
although  its  principal  effect  may  be  in  saving  fuel,  as  mentioned  a while  ago,  yet  acts  as  an  oxidating 
agent  too. 

When  the  pig  contains  sulphur  or  phosphorus  in  any  appreciable  proportions,  (which  give  red-short 
and  cold-short  iron  respectively,)  carbonate  of  lime,  as  pure  as  possible,  may  be  added ; and  the  more 
comminuted,  the  better.  It  should  be  applied  when  fusion  is  commencing,  and  not  afterwards.  In  the 
Pomeranian  forges  at  Torgelow,  about  ten  per  cent,  of  limestone  is  added  after  fusion  is  complete,  in 
three  different  operations,  each  of  which  implies  a stoppage  of  the  blast  and  a stirring  of  the  pig.  It  is 


IRON. 


117 


very  successful  in  one  respect — that  the  phosphorus,  which  exists  in  the  pig  at  an  average  of  41  per 
cent.,  is  reduced,  in  the  malleable  metal,  to  | per  cent. ; but  it  is  at  a considerable  waste  of  iron  and 
fuel.  Other  alkalies  have  been  tried,  such  as  the  carbonates  of  soda  and  of  potash,  with  and  without 
lime,  but  without  much  encouragement.  In  theory,  carbonate  of  magnesia  would  be  the  best  cor- 
rective. 

(a.)  The  modes  which  are  introduced  under  this  method  are,  in  some  minute  respects,  almost  as  nu- 
merous as  the  localities  where  it  is  applied.  Karsten  has  enumerated  and  described  sixteen  different 
processes,  of  which  eleven  are  effected  by  a single  fusion,  and  five  by  a double  fusion.  But  the  general 
type  of  all  is  the  so-called  German  method , which  is  spread  over  the  whole  of  North  Germany,  widely 
used  in  France,  and,  in  many  respects,  exemplified  in  the  bloomeries  of  the  United  States,  especially  in 
Pennsylvania.  The  hearths  used  for  this  method,  except  the  large  chimneys  under  which  they  are 
set,  and  which  must,  of  course,  have  suitable  foundations,  so  much  resemble  the  Catalan  forges,  as  not 
to  need  a figure.  Only  some  of  the  processes  followed  will  be  spoken  of. 

To  work  advantageously,  the  workman  must  know  the  pig-metal  he  is  using,  for  so  much  is  depend- 
ent on  management.  Generally,  a mixture  is  better  than  any  one  kind.  Forge-pigs  ought  to  be  run 
slender,  both  that  they  may  be  broken  easier,  and  that  they  may  be  proportioned  more  exactly.  The 
fragments  should  not  be  too  large,  to  waste  fuel,  nor  too  small,  to  run  too  quick.  The  quantity  for  one 
heat  will,  of  course,  depend  upon  the  particular  case  : as  an  average,  it  may  be  taken  from  250  to  350 
lbs.  The  best  charcoal  is  that  from  soft  woods,  (for  instance,  the  pinus  alba,  larix,  strobus,  &c.,)  and  it 
should  not  be  broken  into  pieces  smaller  than  one’s  fist.  The  quantity  of  blast  varies  with  the  quality 
of  metal  and  weight  of  fuel  and  charge,  and  also  at  different  times  of  the  operation.  This  last  varia- 
tion, unlike  the  high-furnace,  must  be  under  the  constant  vigilance  and  control  of  the  workman.  It  is 
usual  to  put  more  pressure  on  with  white  than  gray  iron  ; a practice  which  does  not  arise  so  much  from 
the  chemical  condition  requisite  as  from  the  habitual  mechanical  arrangement — of  placing  gray  iron 
nearer  the  tuyere.  With  an  average  charge,  there  will  be  required,  while  the  melting  is  taking  place, 
about  150  cubic  feet  of  air  per  minute ; while  stirring,  about  225  cubic  feet;  and  while  making  the 
loop,  as  much  as  275  cubic  feet  per  minute.  In  cases  where  the  loop  is  made  by  attachment,  as  it  is 
termed,  as  much  as  400  cubic  feet  is  used  per  minute. 

This  word,  loop,  has  been  already  used  here  frequently : it  is  only  the  French  loupe,  (a  wen,  a lump,) 
applicable  to  the  shape  of  the  mass.  The  Germans  call  it  blume,  (a  flower — because  it  resembles  the 
unopened  corol  of  a campanulate  flower,)  from  which  we  get  our  English  word  bloom — applied,  in  our 
language  more  particularly,  to  what  has  been  under  the  hammer  and  has  been  forged.  The  term  loop 
is  more  appropriate  before  forging.  The  French  word  renarditre,  by  which  these  forge-fires  are  called, 
means,  literally,  a blind  ditch  through  which  water  escapes ; and  the  analogy  may  be  supposed  with 
the  filtering  and  disappearance  of  the  melted  metal.  The  name  has  no  relation  to  that  of  the  animal 
(the  fox)  whose  kennel,  or  earth,  it  also  is  applied  to  signify. 

To  prevent  the  charge  from  attaching  itself,  in  fusion,  to  the  cast-iron  sides,  and  especially  the  bot- 
tom of  the  hearth,  an  arrangement  is  usually  made  by  which  water  can  be  applied  to  the  outside  of 
these  to  cool  them.  This  should  be  judiciously  resorted  to,  when  necessary  ; particularly  in  the  case  or 
the  bottom-plate,  to  avoid  breaking  it — which  would  result  not  only  in  its  own  loss,  but  likewise  in  that 
of  the  charge  for  that  heat.  It  is  better  to  dispense  with  water  after  the  fusion  is  complete. 

The  slope  of  the  sides  and  inclination  of  the  bottom,  varying  in  different  forges,  and  strongly  insisted 
on  by  some  metallurgists,  appear  chemically  of  absolute  indifference.  There  is  a mechanical  advan- 
tage, only,  in  the  ease  of  working  and  lifting  the  loop.  But  in  the  direction  and  pressure  of  the  blast, 
and  the  size  of  the  tuyfere,  (or  tue-iron,  as  the  American  workmen  call  it,)  the  chemical  results,  both  as 
to  quantity  and  quality,  are  largely  bound  up.  In  former  times,  there  were  used  two  different  tuyhres, 
i.  e.,  the  blast  was  admitted  through  more  than  one  orifice  : a more  correct  observation  has  reduced 
them,  almost  universally,  to  one  tuyere.  The  nozzle  of  the  tuyhre  is  frequently  of  cast  or  wrought  iron, 
which  can  be  easily  fitted  on  the  copper  pipe.  It  is  usually  semicircular — sometimes  round,  or  oval ; 
and  its  area  will  not  surpass  1£  square  inches.  The  inclination  of  the  tuyere  varies  from  5 to  10  de- 
grees downwards  from  the  horizon.  Were  it  horizontal,  it  would  burn  away  more  fuel,  and  a part  of 
the  blast  would  be  lost.  The  more  depressed  the  tuyhre,  the  longer  the  metal  remains  liquid ; the 
more  horizontal  it  is,  the  sooner  the  metal  passes  to  the  malleable  state.  White  iron,  then,  which  has 
this  last  tendency  in  itself,  requires  a more  depressed  tuyhre  than  gray  non — although  some  (Metallur- 
gists assert  the  contrary.  The  depth  of  the  hearth — i.  e.,  the  distance  between  the  bottom-plate  and 
the  upper  edge  of  the  tuyere — is  manifestly  correlative  with  the  depression  of  the  latter ; and  they 
should  work  together.  A hearth  should  not  be  shallower  than  7 inches,  nor  exceed  10  inches.  When 
the  proportions  are  established,  the  tuyere  is  fixed,  by  cramps  or  otherwise  built  in  as  firmly  as  the 
sides  of  the  hearth,  to  prevent  derangements  that  would  be  sure  to  accrue  upon  its  accidental  dis- 
location. 

After  covering  the  hearth  with  fuel,  (leaving  there,  or  not,  the  cinder  of  a former  heat,)  and  getting 
up  a good  heat,  the  pigs  are  pushed  in  the  hearth  to  about  6 or  8 inches  of  the  tuyere,  (the  grayer  the 
iron,  the  nearer  it  is  placed,)  covered  with  charcoal,  the  blast  put  on,  and  every  thing  done  to  promote 
fusion.  When  they  have  begun  to  melt,  the  workman  sounds  with  his  bar  to  feel  the  consistency  of 
the  fused  mass  ; and  he  judges  by  that  whether  cinder  requires  to  be  let  off,  and  what  is  the  state  of 
crudity  of  the  metal.  When  the  latter  begins  to  be  stiff  and  pasty,  he  draws  the  mass  towards  the 
counter,  and,  clearing  away  the  charcoal  and  cinder  to  expose  its  surface,  lifts  it  out  upon  his  ringer. 
It  generally  breaks  into  several  pieces,  which  he  draws  from  the  fire,  supplies  fresh  fuel,  and  then  re- 
places the  pieces  in  the  inverse  order  of  their  conversion ; i.  e.,  the  most  crude  nearest  the  tuyere. 
They  are  fused  again  as  before,  again  worked  and  lifted.  This  time,  generally,  they  remain  coherent,  and 
the  metal  is  sufficiently  refined.  Sometimes,  however,  a third  fusion  is  necessary.  The  liftings  which 
have  been  made  hitherto,  have  only  been  up  to,  or  a little  above,  the  surface  of  the  melted  cinder ; ac- 
cording as  the  workman  judges  it  necessary  to  have  the  strongly  oxidating  influence  of  the  blast,  or  the 


118 


IRON. 


more  gentle  reaction  of  the  scoriae.  But  in  making  up  the  loop,  it  is  lifted  quite  above  the  tuyfcre,  so 
that  the  air  may  pass  under  and  around  it ; it  is  turned  upside  down,  and  end  for  end,  to  expose  every 
part  of  it,  and  then  redeposited  in  the  hearth,  where  the  cinder  is  drawn  to  one  side.  It  is  covered 
with  fresh  fuel,  the  blast  is  strongly  urged,  and  the  loop  is  kept  at  a temperature  almost  of  fusion, 
completely  to  decarburate  and  purify  it.  This  result  is  judged  of  by  plunging  a ringer  into  the  loop 
after  the  blast  has  been  gradually  diminished  : if  the  thimble,  which  comes  out  upon  the  ringer,  is 
easily  detached  after  cooling,  the  metal  is  refined,  and  the  loop  is  then  taken  out  to  be  shingled. 

The  number  of  workmen  required  is  generally  five,  including  the  hammer-man;  the  time  taken  to 
finish  a loop  from  3 to  4 hours.  But  there  is  always  extra  time  lost  in  preparations,  <fec. ; so  that  a 
better  calculation  would  be  to  say  that  in  the  week  of  six  days,  an  average  forge  will  turn  out  from  4 
to  5 tons  of  large  merchant-bars,  say  2 inches  square ; or  about  3 tons  of  inch -square  bars.  The  aver- 
age waste  will  be  about  27  per  cent,  of  the  crude  iron ; and  the  fuel  used  will  be,  at  a mean,  about  ISO 
for  100  of  bar-iron. 

This  process  is,  perhaps,  the  best  for  the  quality  of  the  bars  produced  ; in  respect  to  quantity,  how- 
ever, waste  and  fuel,  it  is  among  the  least  economical.  In  this  last  regard,  of  all  the  existing  European 
processes,  that  of  Sregen  appears  the  most  advantageous,  the  quantity  of  bar  (of  large  size,  to  be  sure) 
amounting  to  9 and  10  tons  per  week,  the  average  waste  about  20  per  cent.,  and  the  fuel,  weight  for 
weight  of  bar  produced. 

(b.)  This,  which  is  the  method  used  in  Champagne,  and  extensively  in  America,  substitutes  a rever- 
beratory or  air-furnace  for  an  open  forge-fire,  urged  by  a direct  blast ; and,  in  fact,  leaves  the  workman 
to  do  by  manual  labor  what  was  done  partly  in  the  preceding  method  by  chemical  reagents.  From  a 
supposed  analogy  between  the  manipulations  here,  the  behavior  of  the  material,  <fec.,  and  what  was 
familiar  in  the  preparation  of  clay  to  prevent  the  passage  of  water  to  foundations,  &c.,  the  process  re- 
ceived the  name  of  puddling  ; as  the  other  method  is  sometimes  called  boiling.  As  in  this  a higher 
temperature  is  necessary,  (heated  air  being  the  only  reagent,)  a fuel  giving  more  heat  is  required,  and 
therefore  coal  is  used.  The  metal,  however,  was  at  first,  and  is  largely  still,  charcoal  iron  ; prepared 
in  advance,  both  in  form  and  substance,  for  the  final  refining  it  has  to  undergo.  This  preparation  is  a 
conversion  into  white  iron  ; which  is  done  either  at  the  high-furnace  or  by  a second  fusion.  If  the  first 
is  relied  on,  the  crude  iron  should  be  run  into  plates,  or  very  flat  pigs,  to  whiten  it  thoroughly.  The 
Styrian  method  for  this  purpose  is  a curious  one.  The  crude  iron  is  run  at  once  into  an  oval  pit,  or 
basin,  in  sand ; the  cinder  is  cleared  off,  and  water  is  sprinkled  over  the  yet  liquid  metal  to  chill  it. 
In  this  way,  plate  after  plate,  weighing  from  25  to  50  lbs.  each,  is  formed  in  intervals  of  hardly  a minute. 
Only  gray  iron,  from  fusible  materials,  will  chill  in  this  way.  The  plates  thus  made  are  roasted,  i.  e., 
exposed  for  10  or  12  hours  to  a red-heat,  either  in  an  appropriate  oven  or  in  an  open  pile;  by  which 
they  are  slowly  decarburated.  If  this  operation  of  roasting  were  in  any  case  well  performed,  a great 
leal  of  the  carbon  should  be  got  rid  of;  but  the  expense  of  fuel  is  very  considerable. 


The  second  fusion  to  whiten  iron,  is  what  the  French  term  mazeage,  and  the  English  running  out  or 
fining.  This  is  very  much  such  a process  and  in  such  a furnace  as  has  been  described  under  the  former 
method  of  refining,  only  it  is  not  carried  so  far,  and  the  metal,  instead  of  being  lifted  and  looped,  is  run 
into  plates.  The  waste  in  this  operation  is  from  5 to  7 per  cent,  on  the  crude  iron:  mazeage,  proper, 
is  done  with  charcoal. 

The  reverberatory  furnace  used  is  similar  in  form  to  what  has  been  already  figured  under  a former 
section. 

(c.)  The  constant  combination  of  a finery,  where  the  plate-metal  is  produced  with  coke,  and  a rever- 
•'  raiory  furnace,  where  it  is  puddled  with  coal,  constitutes  the  method  practised  in  England  ; and  there, 


IRON. 


119 


as  elsewhere,  is  more  or  less  appropriate  and  even  necessary,  whenever  iron  is  to  be  produced  in  great 
quantity,  and  fossil  fuel  is  of  course  to  be  relied  on. 

Fig.  2398  is  a ground  plan,  on  a scale  of  l-25th  of  the  actual  size,  of  an  English  finely,  blown  with  six 
tuyeres.  In  this  aaaa  indicate  the  places  of  the  cast-iron  columns  on  which  the  chimney  rests;  b b 
<fec.,  are  the  side-plates  of  the  forge ; h is  the  hearth  formed  by  the  water-backs  ioww;  f is  the  front 
plate,  and p the  mould  in  which  the  plates  are  run;  cc  are  troughs  where  the  bars  are  cooled. 

Fig.  2399  is  a half  vertical  section  of  the  same  plan,  drawn  to  the  same  scale,  and  serving  to  explain 
it.  This  last  figure  also  shows  the  attachment  of  the  blast,  which,  to  save  room,  was  left  off  from  the 
other ; as  well  as,  by  the  dotted  lines  in  the  hatched  space  beneath,  the  mode  of  securing  the  sustaining 
columns  in  a mass  of  masonry.  The  right  half-section  would  be  a counterpart  of  this. 

Fig.  2400  is  a longitudinal  section  of  the  air-box  r ; and 
the  dotted  circles  on  its  face  are  the  ports  by  which  the 
blast  is  conducted  to  the  several  tuyeres.  The  lever- 
valve  allows  the  blast  (which  in  these  establishments 
comes  generally  from  the  great  blowing-engines  of  the 
liigh-furnaces)  to  be  regulated  by  the  workman. 

Fig.  2401  is  a section,  still  upon  the  same  scale,  of  the 
plate-mould  p.  The  earlier  fineries  were  blown  only  on 
one  side,  and  with  three  tuyferes ; the  modern  ones,  almost 
universally,  are  blown  with  four  or  six  tuyferes,  with  a 
cross  blast.  The  crude  iron  intended  for  the  finery 
should,  like  that  for  the  fires  already  spoken  of,  be  run 
into  small  pigs.  They  very  frequently,  however,  are 
employed  weighing  from  100  to  120  lbs. 

The  kind  of  coke  to  be  preferred  varies  with  the  quality  of  the  metal.  When  this  last  is  refractory 
the  coke  should  be  heavy  and  compact.  A friable  coke,  and  one  containing  much  earthy  matter,  as 
well  as  oven  coke  generally,  are  objectionable. 

The  sole  or  bottom  of  the  hearth  is  indicated  on  Fig.  2399  by  the  letter  s,  2401.  * 

and  by  a different  species  of  hachures.  This  reposes  upon  fire-brick  or 
refractory  sandstone ; and  is  best  made  of  a layer,  4 or  5 inches  thick,  of  — -■,■■■■.  . . 

broken  quartz,  well  rammed.  At  the  first  heat,  this  layer  is  partially  melted 
and  jjercolated  by  the  metal,  forming  a bottom  exceedingly  hard  and  refrac-  * 

tory.  This  property,  in  expediting  the  work,  compensates  fully  the  waste  of  metal  in  the  beginning. 
From  time  to  time,  however,  it  requires  replacement.  The  most  convenient  way  to  get  it  out  (for  it 
weighs  often  a couple  of  tons)  is,  upon  the  conclusion  of  the  week’s  work,  and  after  the  last  heat,  to 
throw  water  upon  it  while  yet  red-hot.  This  cracks  it  up  and  renders  it  easy  to  be  taken  out ; the 
water-backs  may  then  be  reset,  and  the  bottom  laid  anew.  The  old  bottom,  which  contains  a good 
deal  of  half-refined  iron,  can  be  used  up,  little  by  little,  as  scrap. 

As  the  object  of  this  process  is  to  fuse  tire  metal,  the  tools  and  working  are  only  fitted  to  that  end. 
It  is  rare  that  any  flux  or  reagents  are  added.  Hard  metal  is  heated  sometimes  with  forge-cinder  or 
finery-cinder.  These,  as  well  as  any  thing  else  that  may  be  used,  act  in  nearly  the  same  manner  as 
in  refineries  with  charcoal. 

The  plate-mould,  which  can  be  added  to,  from  its  construction,  at  pleasure,  should  be  so  long  in  pro- 
portion to  the  charge,  (which,  for  a large  hearth,  will  be,  on  an  average,  1^  tons,)  that  the  plates  are 
left  not  more  than  1|-  or  2 inches  thick.  After  the  metal  is  in  the  mould,  water  is  thrown  copiously 
upon  the  cinder  which  has  run  out  with  and  covers  it,  and  which,  by  this,  is  easily  separated.  The 
plate  itself,  after  being  chilled  with  water,  is  broken  up  for  the  next  process. 

Care  must  be  taken,  in  this,  to  strike  a proper  medium  between  doing  too  much  and  doing  too  little. 
If  the  metal  in  the  run-out  sparkles  little,  and,  after  being  cool,  preserves  its  compacity,  it  has  not 
been  fined  enough,  and  the  puddling  will  be  hard  and  long.  If  in  the  run-out  it  disengages,  on  the 
contrary,  a multitude  of  faint  sparks,  so  confluent  as  to  become  a sort  of  flame,  and  emits  a white 
vapor,  it  will  probably  be  found  converted  partly  into  malleable  iron  ; and  the  puddling,  in  this  case, 
will  be  more  difficult  and  wasteful  than  in  the  other. 

These  results  depend,  in  a measure,  upon  the  supply  of  blast — which  should  vary  according  to  the 
quality  of  iron,  and  also  according  to  the  character  of  the  fuel  with  which  it  has  been  produced  in  the 
high-furnace.  With  charcoal  iron,  each  tuyfere  should  furnish  from  200  to  250  cubic  feet  per  minute, 
under  a pressure  of  2 lbs.  per  square  inch.  With  coke  iron,  the  quantity  may  advantageously  be  raised 
to  300  cubic  feet,  and  the  pressure  to  2^-  lbs. 

With  this  supply,  a finery  such  as  described  will  run  out  rather  more  than  a ton  per  hour  ; and  ten 
heats  mav  be  made  a turn  of  twelve  hours.  The  waste  should  not  be  more  than  12  per  cent,  of  crude 
iron  ; and  the  coke  used,  about  30  per  cent,  of  the  weight  of  metal  charged. 

From  the  finery,  the  metal  is  ready  to  be  passed  to  the  puddling- furnace.  This  resembles  so  much, 
in  shape  and  detail,  the  reverberatory  furnaces  before  given,  as  not  to  require  a figure.  Sometimes  it 
is  used  with  a charging-door  on  each  side,  when  it  is  said  to  be  a double  furnace.  In  some  cases,  the 
two  doors  have  been  placed  on  the  same  side  ; but,  as  they  could  not  be  worked  exactly  together,  their 
alternations  tended  to  produce  irregularities  and  waste.  There  is  a furnace  of  this  kind,  however, 
though  with  a different  aim,  which  is  affirmed  to  be  very  convenient  and  economical.  It  is  a two- 
hearthed  arrangement,  which  will  be  made  sufficiently  clear  by  the  sketch,  in  longitudinal  section,  (Fig. 
2402,)  where  g is  opposite  to  the  grate,  p to  the  hearth  for  puddling,  c to  the  cinder-pit,  li  to  the  hearth 
for  heating,  and  d to  the  smoke-flue.  On  the  hearth  h,  the  metal  undergoes  a roasting  and  partial  re- 
fining before  it  is  removed  top.  The  external  fixtures,  the  pulleys  and  counterpoises  for  the  doors,  the 
travelling  stirrup  for  shifting  the  charge,  etc.,  can  be  very  easily  imagined.  That  this  furnace  would 
save  fuel  is  quite  probable,  but,  in  respect  to  other  conditions,  its  efficacy  is  more  problematical. 


120 


IRON. 


These  conditions  for  puddling  would  seem  to  be,  1st,  that  a sufficient  heat  be  obtainable  to  melt  the 
metal  entirely ; 2d,  that  the  heat,  in  whatever  degree  availed  of,  should  be  uniformly  distributed  over 
the  hearth ; 3d,  that  there  should  be  'no  carbon  unconsumed  in  the  flame,  in  contact  or  to  be  combined 


with  the  metal,  which  contains  enough  of  that  impurity  already  ; and,  4th,  that  the  metal  (and  this  is 
more  important  for  fine  metal)  should  not  be  exposed  to  a too  oxidating  effect  of  the  air  which  is 
aspersed  through  the  grate. 

As  yet,  bituminous  coal  is  the  best  fuel  that  can  be  applied  in  a puddling-furnace.  Anthracite  is 
also  used  in  America,  with  better  results  than  have  been  experienced  in  Europe.  Charcoal  and  wood 
also  have  been  tried,  but  do  not  appear  to  diminish  the  waste  or  improve  the  quality  of  the  metal, 
while  the  cost  of  fuel  is  enhanced.  The  hearths  are  supposed,  also,  to  be  more  difficult  to  maintain 
with  these  last. 

This  maintenance  is  one  of  the  points  of  trouble  and  expense  ; and  various  methods  are  resorted  to 
for  the  purpose  in  constructing  the  hearth.  It  is  sometimes  made  of  cast-iron  ; in  which  case  it  is  cov- 
ered with  a layer  of  cinder  1-J  to  2 inches  thick,  well  pounded,  and  melted  down  before  the  metal  is 
charged.  Others  prefer  to  make  it  of  sand,  or  broken  quartz,  from  6 to  8 inches  thick,  well  rammed, 
and  covered  then  with  a thin  coating  (less  than  an  inch)  of  powdered  cinder,  which  is  melted  and 
smoothed  before  charging.  This  method  is  ordinarily  productive  of  more  waste,  for  the  silica  takes  up 
portions  of  the  oxide  which  is  formed  : with  impure  metal,  (containing  phosphorus,  for  instance,)  the 
silica  aids  in  refining  it.  Others,  again,  use  cinder  entirely  for  the  hearth  ; stratifying  it  in  small  frag 
ments  to  a depth  of  5 or  6 inches,  and  then  fusing  it  and  smoothing  down.  In  working  only  fine  metal 
of  good  quality,  the  tendency  of  the  hearth  is  to  thicken  itself  and  change  shape  upwards  ; when  it  is 
of  bad  quality,  (and  still  more  when  crude  iron  is  puddled  by  the  first  operation,)  the  hearth  becomes 
burnt  out,  as  it  were,  and  hollowed  downwards.  Either  change  of  shape  renders  repair  necessary.  Old 
hearths  in  sand  or  cinder,  which  have  been  melted  out  or  broken  up,  can  be  used  advantageously  in 
making  new  ones.  Limestone  hearths  have  also  been  tried,  to  the  improvement  of  certain  kinds  of 
metal,  but  to  the  speedy  destruction  of  the  in-walls. 

Before  charging  the  furnace,  a full  red  heat  is  got  up  inside,  principally  to  save  the  waste  that  would 
follow  the  oxidation  by  a slower  fusion.  Then  the  fine  metal,  broken  up  into  pieces,  which  should  not 
exceed  28  lbs.  apiece,  and  the  smaller  the  better,  is  charged — hot  from  the  smaller  hearth,  if  the  fur- 
nace, Fig.  2402,  is  used — otherwise  cold.  Ordinarily,  the  whole  charge  is  about  400  lbs.  The  register  is 
then  raised,  and  the  heat  urged  for  about  a quarter  of  an  hour,  when  the  mass  becomes  pasty,  as  the 
workman  can  judge  by  feeling  it  with  his  bar.  If  the  metal  is  charged  hot,  this  ordinarily  occurs  in  10 
minutes  ; longer,  if  it  was  put  in  cold.  If  it  gets  too  liquid  in  that  period,  water  is  injected  to  cool  it. 
The  register  is  let  down  when  it  is  at  a proper  viscidity  ; and  the  workman,  introducing  his  ringer, 
works  the  pasty  mass  continually,  to  disengage  the  carbon.  As  this  passes  off,  the  metal  becomes 
more  stiff,  but  it  still  must  be  worked,  as  before,  to  present  the  oxidated  portions  to  those  that  may  yet 
be  carburetted,  and  to  prevent  too  great  oxidation,  or,  as  the  workmen  accurately  term  it,  burning. 
Sometimes  it  becomes  so  thick  as  to  be  incapable  of  being  worked  and  divided  : in  such  case,  the  ex- 
ternal air  must  be  shut  off,  the  register  lifted,  and  its  consistence  destroyed  again  by  fresh  urgency  of 
heat.  If  this  misfortune  does  not  happen,  the  thickened  condition  is  followed  shortly  by  an  apparent 
boiling,  more  or  less  marked,  and  an  escape  of  oxide  of  carbon,  burning  with  a blue  flame.  These  ap- 
pearances gradually  cease,  and  another  epoch  occurs,  in  the  metal’s  becoming  easier  to  work — in  fact, 
short,  or  tending  to  break  apart  in  small  lumps.  The  departure  of  the  last  remaining  portions  of  car- 
bon is  generally  indicated  by  a more  lively  lustre,  which  is  taken  as  an  indication  of  its  having  become 
malleable  iron,  or  come  to  nature.  A continued  puddling  for  four  or  five  minutes  more  increases  its 
shortness,  and  it  becomes  pulverulent  almost — the  particles  of  pure  iron  falling  apart,  because  there  is 
not  heat  enough  to  weld  them. 

To  afford  this  heat  is  the  next  step.  The  temperature,  which,  from  the  first  pastiness  the  metal 
assumed,  has  been  kept  as  constant  as  possible,  is  urged  intensely;  and  the  puddler  judges,  by  his 
own  experience,  of  the  proper  moment  to  commence  rolling  the  matter  into  balls.  If  begun  too  soon, 
it  would  not  be  sufficiently  welded  ; if  postponed  too  long,  the  little  fragments  would  have  become 
independent,  and  would  refuse  to  weld  at  all.  Taking  the  proper  moment,  and  beginning  with  the 
matter  the  nearest  the  fire,  the  puddler  works  it  all  up  into  five  or  six  balls,  (or  even  more,  if  the  charge 
is  very  large,)  which  he  draws  over  towards  the  bridge.  While  making  the  last,  he  rolls  it  all  over  the 
hearth  to  fuck  up  all  stray  metal.  This  balling  is  done  sometimes  by  parting  the  mass  into  as  many 
equal  parts  as  it  may  be  intended  to  make  balls,  and  working  each  separately  ; or,  by  taking  a small 


IRON. 


121 


portion  at  once,  and  augmenting  by  attachment,  (i.  e.,  as  one  would  roll  a snow-ball,)  like  one  of  the 
modes  spoken  of  before  in  refining  with  a forge-fire.  The  result  in  either  case  must  be  the  same  ; and 
the  care  to  have  the  balls  well  rounded  and  uniformly  compact  must  be  equal.  The  balls,  when  fin- 
ished, are  taken  out  with  suitable  tongs  and  carried  to  be  shingled. 

The  operation  of  puddling  crude  iron  directly  does  not  differ  materially,  except  in  time  and  in  the 
occasional  addition  of  cinder,  from  puddling  fine  metal.  The  latter,  if  charged  cold,  will  be  balled  iu 
about  1^  hours ; if  hot,  in  10  or  15  minutes  sooner.  The  former,  cold,  will  require  nearer  2 hours. 
Ordinarily,  six  heats  will  be  made  in  a turn  of  8 hours  with  fine  metal,  and  four  heats  with  pig.  There 
is,  of  course,  more  waste,  in  proportion,  with  pig  than  with  fine  metal.  The  exact  loss  cannot  be  con- 
veniently known,  because  the  balls  go  directly  to  the  hammer,  or  roughing-rolls,  and  a part  of  the 
measured  waste  occurs  there.  This  last,  however,  will  be  tolerably  constant ; and  a fair  estimate  of  the 
waste  of  pig  may  be  made  at  15  per  100.  With  gray  iron,  it  would  be,  probably,  nearly  20  per  100. 
The  loss  on  fine  metal  should  not  exceed  10  per  100.  The  weight  of  fuel  consumed  is  about  equal  to 
that  of  fine  metal  puddled,  and  about  1-J-  to  1 of  pig  puddled.  But  to  compare  the  absolute  economy 
of  the  two  processes  in  this  respect,  allowance  must  be  made  for  the  coke  used  in  the  fineries.  This 
was  before  stated  at  rather  less  than  one-third  of  a ton  of  coke  for  one  ton  of  pig  fined — equivalent  to 
half  a ton  of  raw  coal.  Allowing,  besides,  the  waste,  &c.,  in  making  this  coke,  we  should  probably 
conclude  that,  in  the  item  of  fuel,  puddling  direct  from  the  pig  is  cheaper  than  from  fiue  metal.  In  all 
other  respects,  however,  it  is  dearer ; aud  the  puddled  iron  made  is  rarely  of  such  good  quality. 

The  use  of  anthracite  as  a fuel  for  puddling  was  mentioned  just  now.  In  point  of  fact,  the  furnaces 
in  which  it  is  applicable  hardly  belong  to  the  present  class  of  reverberatory,  or  aspiring ; since,  to 
maintain  a sufficient  combustion,  a fan-blast,  resembling  what  has  been  before  described,  has  to  be 
resorted  to.  Fig.  2403  is  a horizontal  projection  of  the  principal  features  of  one  of  these  anthracite 

2403. 


puddling-furnaces ; in  which  f indicates  the  situation  of  the  blast ; g the  fire-grate,  with  d its  filling- 
door  ; h the  hearth,  with  pp  its  charging-doors,  constituting  a double  furnace  ; and  c the  flue  into  the 
smoke-stack.  The  remaining  details,  fastenings,  &c.,  are  analogous  to  other  puddling-furnaces,  and  can 
easily  be  imagined.  The  ash-pit  is,  of  course,  closed  up,  and  the  blast  passes  into  it  by  one  or  two 
orifices.  The  grate  is  made  to  be  about  twice  as  deep  as  for  bituminous  coal — say  20  inches ; and,  for 
a double  furnace,  is  about  five  feet  long.  The  hearth  is  about  six  feet  in  diameter ; and  the  flue,  to 
reach  the  base  of  the  chimney,  pitches  very  much  downwards.  The  height  of  the  chimney,  which,  for 
bituminous  coal  air-furnaces,  is  about  40  feet,  is,  in  these,  almost  immaterial,  since  the  draught  is  regu- 
lated by  the  fans. 

Among  the  modifications  that  have  been  proposed  in  the  details  of  puddling-furnaces,  may  be  men- 
tioned one  (a  double  one)  planned  by  Mr.  Overman,  the  author  of  one  of  the  most  recent  treatises  on 
the  manufacture  of  iron  ; and  designed  principally  for  economy  of  maintenance  and  repair,  in  cases 
where  fusible  reagents  should  be  used  for  improving  the  iron.  In  this,  the  hearth,  lozenge-shaped,  is 
enclosed  by  water-backs  ; the  sole  is  cast-iron,  supported  on  pedestals,  and  allowing  free  circulation  of 
air  underneath.  It  is  said  by  *3  expert  author  to  have  worked  “ exceedingly  well  in  all  cases  in  which 

inferior  hot  or  cold  short  iron,  from  heavy  burden,  is  puddled But  for  gray  metal  of  small  burden, 

particularly  for  all  coke,  stone-coal,  or  hot-blast  iron,  it  is  of  questionable  utility.  For  white  metal  it  is 
perfectly  useless.”  The  candor  of  this  account  is  an  additional  guaranty  of  its  correctness. 

With  the  puddling  ends  all  the  strictly  chemical  metallurgy  of  iron.  The  remaining  processes  of 
forging,  (whether  they  be  effected  by  impact,  or  under  the  hammer — by  pressure,  as  in  the  squeezer, 
or  by  lamination,  as  in  the  roughing-rolls,)  although  necessary,  to  expel  the  remains  of  oxides  and 
earthy  matters  admixed  with  the  metal,  and  essential  to  the  production  of  fibrous  wrought  iron,  are  yet 
only  mechanical. 

The  hammers  used  at  the  Catalan  forge-fires  are  yet  of  primitive  construction.  A head  of  cast  or 
wrought  iron,  or  both,  weighing  from  600  to  800  lbs.,  is  fixed,  as  well  as  may  be,  upon  a helve  of  beech 
or  oak.  This  helve,  or  log,  is  12  or  15  feet  long,  and  12  to  15  inches  in  diameter;  not  squared  or 
dressed,  further  than  to  stub  off  the  projecting  knots  ; and  fitted  with  trunnions  in  a stout  and  solid 
wooden  frame,  to  allow  of  movement  up  and  down.  This  is  effected  by  tilting  the  end  downwards 
with  cams  placed  upon  the  circumference  of  a water-wheel,  usually  10  or  12  feet  in  diameter,  but  only 
about  one  foot  wide.  This  wheel  makes  from  25  to  30  revolutions  a minute ; and,  there  being  usually 
but  four  cams  upon  it,  the  strokes  of  the  hammer,  at  a maximum,  will  be  not  more  than  120.  The 
lower  face  of  the  hammer  works  upon  an  anvil  of  the  same  surface  and  same  material,  and  weighing 
from  450  to  550  lbs.  The  anvil  is  so  inclined  that  the  striking  faces  shall  be  parallel  when  in  normal 
position.  These  heavier  hammers  are  used  for  shingling  the  loops,  and  even  for  drawing  down  a large- 
sized bar.  For  smaller  work,  and  for  finishing,  lighter  hammers  are  used,  arranged  in  the  same  man- 
ner, but  weighing  from  150  to  180  lbs.,  with  an  anvil  of  120  to  150  lbs.,  and  worked  by  a smallei 
wh«cl,  of  6 to  8 feet,  making  30  to  35  revolutions  per  minute,  with,  ordinarily.  6 cams  ; so  that  the 


122 


IRON. 


strokes  amount  to  180  or  even  200  in  a minute.  The  skill  of  the  hammer-man  is  shown  by  so  man 
aging  the  powerful  implement  at  his  disposal  as  to  condense  the  bloom  uniformly  ; and  his  art,  in  fin 
lsliing  the  bar  to  a uniform  surface. 

The  hammers  of  the  German  forges  were  set  with  wood,  in  a wooden  frame,  like  the  Catalan  ; only  • 
they  are  almost  universally  trip  or  lift  hammers — i.  e.,  the  cam  is  applied  between  the  centre  of  motion 
and  the  anvil.  This  position  has  the  awkwardness  of  sometimes  embarrassing  the  hammer-man,  and 
makes  it  necessary  that  the  helve  be  set  obliquely  in  the  framing.  At  the  present  day,  more  or  less  ot 
the  framing  is  made  of  cast-iron.  The  weight  of  these  hammers  is  from  400  to  450  lbs.  only  ; the  lift, 
i.  e.,  the  vertical  fall  of  the  face,  from  24  to  28  inches  ; the  wheel  generally  lias  5 cams  ; and  the  num- 
ber of  strokes  is  from  90  to  100  per  minute. 

In  the  French  forges  the  arrangement  is  the  same,  except  that  the  heads  are  habitually  heavier, 
weighing  from  650  to  150  lbs. ; the  lift  is  not  more  than  20  inches  ; and  the  stroke  is  slower,  being  from 
*75  to  80  per  minute. 

In  the  forges  of  both  countries,  the  finishing  -hammers  are  tilted , both  for  convenience  of  access  and 
speed.  These  are  of  different  sizes,  according  to  the  work  to  be  done  and  the  quality  of  the  iron.  The 
larger  ones  weigh  from  200  to  300  lbs.,  and  make  from  120  to  150  strokes  per  minute,  with  a fall  of 
18  or  20  inches ; the  smaller  range  from  60  to  100  lbs.  in  weight,  and  make  from  250  to  300  strokes  in 
a minute,  with  a fall  of  not  more  than  12  inches.  To  get  up  this  speed,  the  water-wheel  is  furnished 
with  more  cams,  sometimes  as  many  as  32  in  number.  All,  the  largest  and  smallest,  work  against  a 
sort  of  wooden  spring,  which  checks  their  upward  motion  and  imparts  more  momentum  to  the  down- 
ward fall. 

Fig.  2404  is  a projection,  upon  a scale  of  one-thirtieth,  parallel  to  the  plane  of  the  water-wheel,  of 
(me  of  the  modern  German  hammers,  in  an  iron  frame.  The  faces  of  the  head  and  anvil  are,  in  this,  a 


uniform  plane  ; but  often,  and  especially  for  finishing  hammers,  the  face  is  like  the  letter  T relief 
or  else  a full  cross. 

This  modification  is  borrowed  from  the  English  fashion,  whose  hammers,  besides,  are  altogether  more 
powerful  and  substantial.  Made  of  iron  throughout,  the  hammer-head  and  helve  weigh  from  4 to  7 
tons.  The  lift  is  effected  to  a height  of  about  15  inches,  by  cams,  which  seize  a projecting  lip  in  ad- 
vance of  the  very  head,  and  constitute  a trip-hammer  proper  ; sometimes  by  an  eccentric,  which  works 
against  the  helve  between  the  head  and  the  centre  of  motion.  The  number  of  strokes  is  about  80  or  90 
per  minute.  The  power  is  taken  off  from  a steam-engine,  and  a heavy  fly-wheel  is  necessary  to  equal- 
ize the  motion.  The  anvil  weighs  ordinarily  from  4 to  5 tons.  Fig.  2405  is  a sketch  of  one  of  these 


hammers ; the  dotted  lines  showing  that  part  of  the  arrangement  which  is  below  the  floor-line  and  rests 
upon  the  foundations.  There  are  also  lighter  hammers,  for  special  work,  in  the  English  forges,  which 
weigh  altogether  not  more  than  two  tons,  and  make  from  140  to  180  strokes  a minute. 

With  their  heavy  fly-wheels,  these  hammers  cannot  be  stopped  in  the  same  way  as  the  lighter  ones 
The  usual  mode  is  by  thrusting  a jack,  or  piece  of  iron,  under  the  helve  when  it  is  at  its  highest.  In 
starting  again,  a piece  of  wood  is  dexterously  placed  to  be  caught  by  the  cam,  and  the  jack  is  released 


IRON. 


123 


Overman  has  suggested  a permanent  jack,  (or  jack-ketch,)  to  be  worked  by  a piece  of  wire,  which  is 
undoubtedly  better. 

A very  ingenious  and  useful  application  of  steam  directly  to  a vertical  hammer  has  been  executed 
by  Mr.  Nasmyth.  Its  behavior  is  not  unlike  that  of  a pile-driver  ; only,  it  can  be  worked  with  great 
rapidity,  and  thus,  in  some  cases,  dispenses  with  the  number  of  reheatings  necessary  in  finishing  a bar. 
As  this  machine  is  applicable  to  other  purposes  tliau  the  forging  of  iron,  its  description  will  be  given 
under  a special  article,  Steam-Hammer. 

Tie  squeezers,  which  are  extensively  found  in  English  iron-works,  are  employed  for  the  same  purpose 
as  the  heavy  shingling-hammers,  viz.,  condensing  the  puddle-balls  into  slabs  : they  act,  as  might  be 
supposed  by  the  name,  by  steady  pressure  instead  of  impact.  They  are  supposed  by  some  metal- 
lurgists to  answer  the  end  of  expelling  the  cinder,  <fcc.,  as  well  as  hammers  ; but  this  is  very  doubtful. 
As  applied  to  finishing  bars,  their  use  would  not  be  economical.  The  most  numerous  class  is  of  tilt- 
squeezers — i.  e.,  the  trunnions  are  between  the  power  and  the  squeezing-jaws.  The  power  is  variously 
applied,  by  an  eccentric  or  by  cranks.  Fig.  2406  shows  the  chief  features  of  one  of  the  last  kind,  upon 
a scale  of  one-fortieth  of  the  actual  size.  The  whole  apparatus,  which  is  of  cast-iron,  requires  to  be 
strongly  bolted  down  to  a solid  foundation.  The  dotted  circle  indicates  the  position  of  the  fly-wheel, 
by  which  the  power  is  equalized  on  the  crank ; and  the  shaded  lines  show  the  jaws,  which  are  separate 
plates  of  wrought  or  cast  iron,  bolted  on  the  frame,  and  renewed  when  necessary.  Such  a machine, 
making  from  80  to  90  revolutions  per  minute,  can  squeeze  about  100  tons  per  week.  Its  theoretical 
deficiency  is  the  want  of  parallel  movement ; its  practical  one,  the  enormous  strain  (especially  if  the 
loop  should  be  too  cold)  upon  all  the  blocks  and  journals. 


A different  apparatus  from  this,  and  free  from  some  of  its  defects,  is  Burden’s  patent  eccentric  rotary 
squeezer — the  mode  of  whose  action  will  be  apparent  from  the  projection  in  Fig.  2407,  where  r shows 
a cylinder  with  a roughened  or  serrated  surface,  revolving  vertically  in  an  eccentric  drum  which  is  per- 
manent. The  ball  goes  in  at  a , and  is  dragged  round  with  it,  more  and  more  compressed  in  its  narrow- 
ing path,  until  it  comes  out  at  b.  The  bottom  is  a solid  plate  ; the  top  admits  of  a slight  adjustment. 

This  machine  has  brought  us  round  to  the  method,  much  older,  and  still  practised  in  many  English 
establishments,  of  squeezing  and  condensing  between  horizontal  cylinders,  or  roughing-rolls.  A°suf- 
ficiently  indicative  sketch  of  these  is  given  in  Fig.  2408,  about  one-fiftieth  of  the  actual  size.  The 
securings  and  couplings,  Ac.,  are  omitted.  The  first  of  the  upper  train  on  the  right  is  moriscoed  or 
roughened,  to  catch  and  drag  the  ball.  The  next  one  is  channelled  for  the  same  purpose.  The  sur- 
face-adhesion is  enough  to  that  end  in  the  other  two.  The  collars  on  the  lower  train  are  for  up-setting 
or  keeping  the  slab  in  shape  laterally. 

What  are  called  roughing-rolls  in  America  are  used,  not  instead  of,  but  subsequently  to,  the  hammer 
or  squeezer  ; and  serve  to  forge  the  bloom  into  shape,  rather  than  perfect  its  malleability.  Instead, 
therefore,  of  being  flat,  the  cylinders  have  corresponding  grooves  of  large  size,  making  a square  or 
lozenge-like  section.  In  other  respects,  in  housing,  geering,  <fec.,  they  are  the  same  with  the  English. 

In  proportion  as  the.  bloom  or  slab  becomes  drawn  out  by  any  of  the  condensing  or  flatting  processes 
which  have  been  mentioned,  it  becomes  necessary  to  shear  it  up  into  shorter  lengths,  which  are  reheated 
sepai  ately  oi  in  piles,  to  be  treated  as  before,  lhe  Catalan  forges  use  a chisel  under  the  hammer  for 
this  purpose.  But  rough-bar  is  much  better  severed  by  heavy  shears,  worked 
either  by  a water-wheel  or  steam-engine.  Small  bar  can  be  cut  with  hand- 
shears.  In  general  arrangement,  the  heavy  shears  resemble  the  squeezers — 
cutting-edges  being  substituted  for  the  flattiDg-planes ; and,  like  the  latter, 
they  are  worked  with  a crank  at  the  end  of  a straight  or  bent  shank,  or  with 
an  eccentric  that  tilts  the  edges.  The  shank  and  shear-block  are  all  of  cast- 
iron  ; and  the  leverage,  from  the  trunnions  to  the  crank,  wall  vary  from  4 
to  10  feet,  according  to  the  work  intended.  The  cutting-edges  are  of  steel, 
bolted  ou  to  the  block,  and  lie  either  in  the  same  plane  with  the  shank,  or 
parallel  with  the  trunnions.  The  last  mode  has  been  devised,  as  obviating 
the  defect  belonging  to  all  scissors  arrangement — viz.,  the  varying  ang’le  o^  the  cutting-planes.  As 
suitable  for  thin  work  to  be  cut  evenly,  a sketch  of  this  arrangement  is  given  in  Fig.  2409.  The 
blades,  which  are  shown  by  the  vertically  shaded  lines,  may  be  of  any  length— 15,  or  even  24  inches— 


2109. 


MilElig 


124 


IRON. 


suited  to  the  character  of  the  work  to  be  cut.  The  defect  in  these,  as  in  all  existing  shears,  is 
the  want  of  horizontal  slide  as  they  come  down  vertically — a modification  easier  to  imagine  than 
execute. 

The  reheating  ox  piling  furnaces,  which  have  been  just  now  mentioned  as  necessary  for  restoring  the 
temperature  to  the  slabs  or  bars,  and  enabling  them  to  be  further  worked  on  and  finished,  are,  in  the 
most  complete  establishments,  separate  fires.  In  the  more  primitive  methods,  this  reheating  (which  is 
required  twice  or  thrice)  is  done  in  the  forge-fires  themselves  ; sometimes  it  is  done  in  the  puddling- 
fire,  or  at  the  end  of  the  puddling-furnace.  In  general  character,  these  reheating  ovens  resemble  the 
ordinary  puddling-furnace  ; but  they  require  some  modifications  to  yield  their  best  effect.  The  aim  of 
these  is  to  produce  a welding  heat  uniformly  over  the  hearth  ; and,  at  the  same  time,  at  the  expense  of 
as  little  metal  oxidated  as  possible.  The  last  end  is  answered  by  making  the  grate  larger  in  proportion 
to  the  hearth,  and  charging  more  fuel  in  proportion  to  the  chimney,  so  that  the  air  may  be  more  com- 
pletely deoxidized  by  the  excess  of  carbon.  The  former  is  sought  to  be  satisfied  by  lowering  the 
bridge  and  bringing  down  the  arch  nearer  to  the  ramp,  to  which,  also,  the  hearth  proper  inclines 
little.  Wood  may  be  used  in  one  of  these  furnaces,  but  with  a larger  grate  and  a lower  arch. 

The  remaining  machinery  to  be  spoken 
of  is  the  cylinders  or  rolls  tor  finishing  the 
bars — flat,  square,  round,  or  in  any  fancy 
section.  The  housing  and  coupling  these 
trains  can  be  understood  from  the  rough- 
kig-rolls  just  now  given,  without  a special 
figure.  All  are  arranged  upon  the  same 
principles ; only,  the  lighter  the  work  the 
longer  may  be  the  trains,  and  more  rollers 
in  a train.  The  frames  or  housing  for  the 
rolls  are  made  of  cast-iron,  as  seen  in  sec- 
tion on  Fig.  2410,  which  shows,  on  a scale 
of  one-twelfth,  an  assemblage  of  three  cyl- 
inders in  a train,  suitable  for  finishing  light 
bars.  This  section  also  serves  to  illustrate 
Fig.  2408.  These  frames  should,  of  course, 
be  set  as  solidly  as  possible ; for  instance, 
upon  a cast-iron  bed-plate,  bolted  to  a tim- 
ber foundation  built  in  with  masonry.  This 
seems  better  than  masonry  alone,  because 
of  a certain  elasticity  in  wood.  If  slots  are 
left  in  the  bed-plate,  the  frames  will  be 
found  of  easier  adjustment.  The  bed-plate 
should  be  open  in  the  middle,  leaving  a 
trench  that  may  catch  the  cinder  that  comes 
off  from  the  bars,  as  well  as  the  water  that 
drips  on,  and  that  may  serve  as  a cellar  to 
the  foundations. 

For  rolling  flat  bars,  the  cylinders  are 
grooved  alternately  and  work  reciprocally 
in  each  other ; for  round  or  square  bars, 
however,  half  their  section  is  turned  out  of 
each  cylinder.  The  diameter  in  the  one 
case,  and  a diagonal  in  the  other,  correspond 
with  the  normal  surface  of  the  cylinders 
before  being  turned  out.  In  turning  out 
grooves,  ifcc.,  for  fancy  patterns,  a good  deal 
of  ingenuity  is  sometimes  exercised,  as  will  be  seen  in  the  descriptions  and  figures  under  the  article 
Railroad  Bars. 

The  reciprocal  fitting  of  the  grooves  for  flat  bars  renders  a longitudinal  dislocation  of  the  rolls  impos- 
sible. With  the  others,  such  dislocation  is  ordinarily  sought  to  be  guarded  against  by  strong  screws  in 
the  frames  ; but  it  is  much  better  to  have  a groove  and  collar  turned  in  one  or  both  extremities  of  all 
cylinders.  Vertical  displacement  is  prevented  by  the  head-screw  seen  in  the  figure;  and  a lateral 
adjustment  is,  in  some  cases,  given  by  horizontal  screws  working  through  the  trussing  against  the 
plumber-blocks.  There  is  usually  a play  of  about  a quarter  of  an  inch  allowed  in  the  blocks  and 
couplings,  to  obviate  immediate  fracture  in  case  of  slight  derangement ; and  also  to  throw  the  breakage, 
if  an  accident  does  occur,  upon  these  parts  rather  than  on  the  cylinders,  which  are  the  costly  parts  of 
the  machinery.  It  is  easy  to  see  that  upon  the  truth  of  all  the  movements  depend  freedom  from  acci- 
dent, and  excellence  and  economy  of  work.  It  is,  therefore,  cheapest  to  have  every  thing  made  of  the 
best  material  and  in  the  best  manner. 

In  rolls  for  flat  iron,  the  diameter  of  the  cylinders  is  usually  the  same  ; for  round  and  square  iron, 
the  upper  cylinder  is  often  a little  (say  half  an  inch)  larger  than  the  lower.  If  there  are  more  than 
two  cylinders,  the  same  practice  is  found,  in  some  places,  of  making  their  diameters  regularly  decrease 
(by  say  a quarter  of  an  inch)  from  the  upper  to  the  lower.  In  others,  and  perhaps  in  the  generality  of 
cases,  the  middle  of  the  three  is  the  largest.  . Some  metallurgists,  on  the  contrary,  object  entirely  to 
this  difference  of  diameter,  as  causing  increased  friction  in  the  machinery,  and  straining  the  iron.  This 
objection  is  theoretically  correct.  The  aim  of  the  contrivance  is  to  prevent  the  bar,  as  it  passes  through 
the  rolls,  from  curling  around  the  upper  cylinder  ; if  this  last  be  larger,  it  will  continue  to  bear  on  the 


IRON. 


125 


bar  after  the  resistance  of  the  lower  roll  has  ceased,  and  will,  of  course,  tend  to  force  it  down  upon  the 
apron.  But  this  tendency  to  curl  is  best  corrected  by  having  guards  to  each  groove — i.  e.,  wedges  ot 
wrought-iron,  which  catch  the  bar  a9  it  comes  out. 

The  diameter  of  the  cylinders,  and  their  bearing,  vary  according  to  the  purpose  for  which  they  are 
intended.  Roughing-rolls  for  puddle-balls  are  from  18  to  20  inches  diameter,  and  5 to  6 feet  long  ; for 
piled  iron  or  rough  bars,  from  12  to  14  inches  diameter,  and  5 feet  long.  Finishing-rolls  for  heavy  bar 
will  be  of  the  same  diameter  with  the  last,  but  from  12  to  18  inches  shorter  ; while  for  small  rods  their 
diameter  need  not  be  more  than  8 to  10  inches,  and  their  bearing  about  2-J  feet.  The  weight  of  a pair 
of  roughing-rolls  is  from  4 to  5 tons,  and  of  finishing- rolls  from  1J  to  2 tons. 

In  geering  up  the  rolls,  the  lower  one  is  the  driver,  when  there  are  only  two  ; in  a train  of  three  rolls, 
the  middle  one  drives.  The  velocity  of  rotation  varies  according  to  size  and  purpose,  and  even  accord- 
ing to  the  state  and  quality  of  metal.  Roughing-rolls  should  work  slow  : for  puddle-balls  16  to  18  rev- 
olutions, and  for  piled  iron  22  to  24  revolutions  per  minute,  are  sufficiently  rapid.  For  finishing-rolls, 
this  may  be  increased  to  70  or  80  revolutions  ; while  small  rods  are  rolled  with  120, 150,  and  sometimes 
even  200  revolutions  per  minute.  But  these  high  speeds  are  liable  to  frequent  accidents. 

The  friction  of  the  machine,  and  the  initial  temperature  of  the  material  to  be  rolled,  heat  the  journals 
and  cylinders  very  much.  To  abate  this  a wooden  trough  is  laid  above  the  train,  from  which  water  may 
drip  on  the  machinery  and  metal  under  treatment.  The  effect  is,  to  keep  both  the  cylinders  and  metal 
clean. 

The  size  of  the  grooves,  and  their  proportionate  spacing,  varies  in  different  countries  ; and  the  last 
particular  even  in  different  establisliments.  The  methods  for  it  are  purely  geometrical,  and  present 
nothing  peculiar  in  the  manufacture  of  iron.  The  constant  rule  prevails  here,  as  in  all  lamination, 
viz.,  to  place  the  largest  grooves  and  the  heaviest  work  nearest  to  the  end  at  which  the  power  is 
applied. 

With  a single  pair  of  cylinders  the  bar  always  enters  on  the  same  side.  As  it  comes  out  on  the 
other,  it  is  caught  by  a second  workman,  who,  with  the  aid  of  a travelling-stirrup,  hands  it  over  the 
rolls  to  the  first.  When  the  cylinders  are  triple,  the  rods  enter  alternately  first  on  one  side  and  then 
on  the  other.  The  process  with  the  single  pair  is  time-consuming,  but  it  does  not  seem  likely  to  be 
bettered,  unless  by  having  two  trains  parallel  to  each  other,  which  would  admit  of  the  alternation  of 
entry  as  in  the  triple  rolls.  Such  an  arrangement  would  increase  the  first  cost  of  machinery,  but  the 
work  would  be  done  cheaper  and  better. 

Such  are  the  particulars  which  belong  to  the  finishing  of  ordinary  merchant- bars.  The  processes  by 
which  iron  is  further  prepared  for  special  uses  will  be  detailed  more  appropriately  under  separate 
heads.  Thus,  the  rolling  of  iron  for  railroads — an  enormous  branch  of  trade — will  be  treated  under 
Railroad  Bars  ; the  lamination  of  plates  and  sheets,  together  with  the  further  preparations  for  several 
purposes  that  these  undergo  in  the  mill,  will  come  under  Sheet-Iron  ; the  cutting  up  of  these  in  making 
nails,  hoops,  &c.,  will  be  grouped  under  the  head  Slitting-Mill  ; the  extensive  and  remarkable  appa- 
ratus by  which  this  reluctant  metal  is  shaped  with  chisel' and  drill,  as  if  it  were  only  wood,  will  be 
described  under  the  articles  Lathe  Planing-Machine,  and  Turning  (of  Iron;)  and  as  far  as  relates  to 
the  boring  of  cannon,  under  Ordnance  ; the  methods  followed  in  drawing  it  out  into  Wire,  will  be  ex- 
plained under  that  title  ; and,  finally,  under  Smith-work  will  be  contained  all  that  class  of  operations 
before  indicated,  which  comprehend  all  the  processes  of  hand-forging  and  welding,  (as  for  anchors, 
chains,  horse  shoes,  <fcc.,)  and  of  steeling  and  tempering,  (as  for  cutlery,  <fcc.,)  practised  in  an  art  whose 
exercise  has  originated  the  most  extensive  and  well-known  family  name  in  the  world. 

History. — There  is  room  here  only  for  the  indication  of  epochs  signalized  by  inventions  that  have 
given  fresh  impulses  or  new  directions  to  the  manufacture.  From  the  earliest  times  till  at  least  800 
A.  D.,  the  processes  were  either  primitive,  or,  with  unimportant  modifications,  gave  only  a more  or  less 
malleable  metal  direct  from  the  ores,  which  were  necessarily  those  that  fused  readily.  The  fuel,  origi- 
nally wood,  had  been  changed,  during  this  period,  to  charcoal — though  by  whose  ingenuity,  or  when, 
there  is  no  record.  Some  writers  place  about  the  termination  of  this  era,  which  is  that  of  Charlemagne, 
the  introduction  of  crude  iron.  This  seems  an  antedating  by  at  least  four  centuries. 

•A.  D.  1340.  Earliest  epoch  of  crude  or  cast-iron  ; employed  as  ordnance  by  the  Duke  of  Normandy, 
afterwards  John  II.  of  France. 

1490.  Usual  epoch  of  foundries. 

1550.  Epoch  of  wooden  blowing-machines. 

1612-19.  Fossil-fuel  (pit-coal)  first  used  for  reducing  iron  in  England. 

1640.  Invention  of  trampes , or  water-blasts. 

1645-56.  Epoch  of  foundries  in  America. 

1740.  Pit-coal  and  coke  used  in  high-furnaces. 

1749.  Invention  of  rotary  or  fan-blasts. 

1760.  First  cast-iron  cylinder  blowing-machine. 

1780.  Epoch  of  the  puddling-furnace. 

1784.  Epoch  of  the  rolling-mill. 

1829.  Discovery  of  the  application  of  hot-blast. 

1836.  Application  of  the  waste-gases  from  the  high-furnace. 

1837.  Anthracite  used  as  a fuel  with  hot-blast.  , 

During  the  intervals  between  these  dates,  and  since  the  last,  divers  improvements,  both  in  theory  and 
practice,  have  been  suggested  and  executed,  but  none  of  them  of  palmary  importance. 

Statistics. — The  following  table,  covering  the  last  10  years,  contains  what  is  known  or  can  be  esti- 
mated in  regard  to  Great  Britain  and  the  United  States — the  two  principal  producers  and  consumers  in 
the  world : 


126 


IRON. 


Years. 

Great  Britain  Manu- 
facture. 

UNITED  STATES. 

Manufacture. 

Imported  from  Great  Britain. 

Crude  Iron. 

Bar  Iron. 

1840 

1,396,000  tons. 

286,000  tons. 

5,516  tons. 

32,829  tons. 

1841 

1,200,000  “ 

250,000  “ 

12,268  “ 

63,056  “ 

1842 

1,088,000  “ 

215,000  “ 

18,694  “ 

61,599  “ 

1843 

1,215,000  “ 

350,000  “ 

3,873  “ 

15,758  “ 

1844 

1,210,000  “ 

490,000  “ 

14,944  “ 

37,891  “ 

1845 

1,513,000  “ 

625,000  “ 

27,510  “ 

51,189  “ 

1846 

1,675,000  “ 

765,000  “ 

24,188  “ 

24,109  “ 

1847 

1,840,000  “ 

800,000  “ 

23,377  “ 

32,085  “ 

1848 

1,999,000  “ 

750,000  “ 

51,632  “ 

81,589  “ 

1849 

2,150,000  “ 

600,000  “ 

105,632  “ 

173,457  “ 

Tlie  following  table  may  be  of  interest  as  showing  the  range  and  relation  of  value  and  price  in  th* 
two  countries  for  the  same  period  : 


Years. 

Average  Valuation  in 
U.  S.  Custom-Houses. 

Average  Price  of 
Scotch  Pig  in 
Glasgow. 

Average  Valuation  in 
U.  S.  Custom-Houses. 

Price,  at  beginning  of 
Year,  of  Bar-Iron  in 
Liverpool. 

1 S40 

§21  per  ton. 

§19  per  ton. 

§52  per  ton. 

§43  per  ton. 

1841 

18 

16 

35 

37 

1842 

16 

13 

33 

31 

1843 

12 

10 

32 

25  “ 

1844 

13 

13 

28 

24  “ 

1845 

18 

21  “ 

33 

31 

1846 

20  “ 

17 

47 

43  “ 

1847 

20  “ 

16 

53 

46  “ 

1848 

16  “ 

11 

45 

36 

1849 

13 

10 

35 

28  “ 

Sterling  money  is  here  converted,  purposely,  only  to  the  nearest  dollar. 

Within  the  past  ten  years,  of  other  countries  only  Belgium,  France,  Italy,  and  Prussia  have  extended 
their  manufacture  of  iron ; but  the  statistics  of  these  which  are  accessible  do  not  warrant  a continuous 
statement.  It  may  be  safely  assumed,  however,  that  the  aggregate  production  of  the  world  in  1849  did 
not  fall  short  of  four  millions  of  tons — an  increase  of  60  per  cent,  over  1839.  Such,  and  so  growing, 
is  the  importance  of  this  metal. 

Bibliography. — Among  ancient  authors  need  be  mentioned  only  Aristotle,  Meteorolog.,  lib.  iv.,  and 
He  mirab.  Auscultate  lib. ; Diodore  of  Sicily,  Histor.,  lib.  v. ; Strabo,  Geograph .,  libb.  iv.  v.  x. ; of  the 
Greek  writers  : and  of  Latin,  the  elder  Pliny,  Hist.  Natur.,  lib.  xxxiv.  In  connection  should  be  taken 
Hausmann,  de  arte  Ferri  conficiendi  veterum,  1820.  In  modem  times,  Agricola,  de  re  Mrtallica,  1546  ; 
Reaumur,  Hart  d’adoucir  le  fer  fondu,  etc.,  1722;  Swedenborg,  Regnum  Subterran.,  1734;  Bergman 
de  Analysi  Ferri,  1781  ; and  the  Swede  Rinman,  Forsiik  till  jemets-historie,  1785,  (Researches  into  the 
History  of  Iron,  and  translated  into  German  by  Ivarsten,) — compose  a clas9  who  needed  only  a truer 
chemical  theory  to  direct  and  bind  up  their  observations.  Such  a theory — begun  to  be  exemplified  in 
the  memoir  of  Berthollet,  Vandermonde,  and  Monge,  upon  the  different  states  of  iron,  Hist,  de  I'Acad. 
des  Sciences,  1786 — was  more  elaborated  in  the  four  quartos  of  Hassenfratz,  La  Siderotechnie , 1812; 
and  underwent  a final  establishment  in  Ivarsten’s  Handbuch  der  Eisenhutten  Kunde,  first  published  ^n 
1816,  translated  from  a second  German  edition  under  the  title  of  Metallurgie  de  Fer,  by  Culman,  in 
1830,  and  republished  in  a third  German  edition  in  1844.  Use  has  been  made,  in  both  of  the  last 
editions,  of  the  same  author’s  Metallurg.  Reise  dutch  Baiern,  etc.,  1821.  Other  writers  who  since  then 
have  contributed  facts  or  explanations,  will  be  mentioned  chronologically  : for  instance,  Berzelius,  in 
his  Afhandlingar  i Fysilc,  Kemi,  Ac.,  (a  periodical  begun  in  1806,)  where  there  are  several  important 
announcements,  which  were  subsequently  collected  and  translated  by  Jlerve  under  the  title  of  Chimie 
de  Fer,  1826  ; the  same  Berzelius  in  Manual  of  Chemistry,  [Traite  de  Chimie,  vol.  iii.,)  translated  into 
French  by  Jourdan  ; Manson,  Traite  de  Fer  et  de  I’Acier,  1826  ; Pelouze,  VArt  du  Maitre  de  Forges, 
1827  ; Landrin,  Manuel  Complet  du  Maitre  de  Forges,  1829  ; Berthier,  Essais  par  la  Vote  Seche,  tom. 
ii.,  1834  ; Holland,  Manufactures  in  Metal,  vols.  i.  ii.,  1834  ; Gnenyvean,  Nouveaux  Precedes  pour 
fabriquer  la.Foute  et  le  Fer , 1835  ; Dufrenoy,  De  Beaumont,  Coste,  and  Perionnet,  Voyage  Metallur- 
gique  en  Angleterre,  (2d  edition,)  1837  ; Le  Blanc  and  Walter,  Metallurgie  Pratique  du  Fer,  1835— 3S  ; 
Scrivenor,  History  of  the  Iron  Trade,  1839-41 ; Mushet,  Papers  on  Iron  and  Steel,  (being  a collection 
and  revision  of  papers  published  many  years  before  in  Tillock’s  Philos.  Mag.,)  1840  ; Johnson,  Anthra- 
cite Iron,  1841  ; Alexander,  Progress  and  Present  State  of  the  Manufacture  of  Iron,  1841,  and  an 
edition  of  Rogers’s  Letters  on  Iron- Making,  1844;  Flachat,  Barrault,  and  Petiet,  Traite  de  la  Fabrica- 
tion de  la  Fonte  et  du  Fer,  1846  ; and  Overman,  The  Manufacture  of  Iron  in  all  its  various  Branches . 
1850.  Authors  who  have  treated  of  the  mechanical  resistance  of  this  metal  are,  Duleau,  sur  la  Resist- 
ance du  Fer  forge,  1820;  Tredgold,  Essay  on  Cast-Iron,  Ac.,  (2d  edition,  enlarged,)  1824,  and  with 
additions  by  Hodgkinson,  1842-46  ; Turnbull,  on  Cast-Iron,  1832;  Nuvier,  Memoire  sur  les  Fonts  Sus- 
■pendus,  1830,  and  Resume  des  Lemons,  Ac.,  (2d  edition,)  1833 — in  the  first  volume  of  which  there  is  a 


IRON  BLOOMING  MACHINE. 


127 


copious  collection  of  the  results  of  preceding  experimenters.  Besides  these,  there  are  to  be  consulted 
upon  the  theory  and  practice,  upon  the  minerals,  material,  and  manufacture  of  iron,  papers  in  various 
scientific  journals  which  can  only  be  generally  indicated:  for  example,  in  the  Ann.  de  Chimie  et  de  Phy- 
sique of  Guyton-Morveau,  Arago,  Berthier,  Thenard,  &c. ; in  the  Journal  des  Alines  of  Collet  Descotils, 
Yauquelin,  &c. ; in  the  Annale  des  Mines  of  D’Aubuisson,  Bunsen,  Ebelmen,  Thirria,  &c. ; in  the  An- 
nalen  of  Poggendorff,  of  Mosander,  Rose,  and  Seebeck ; in  the  Archiv.  fur  Bergbau  of  Karsten , of  Berze- 
lius, and  Karsten  ; in  the  Phil.  Transact.,  and  in  the  L.  and  E.  Philosoph.  Mag.  of  Rennie  and  Daniell, 
Ac.  : many  of  which  would  require  examination  and  discussion  in  a complete  modern  treatise  on  iron. 

Improved  Machines  for  the  Manufacture  of  Iron. — Various  machines  have  been  contrived  for  the 
squeezing  out  the  cinder  from  the  puddle  ball ; the  best  is  probably  the  hammer,  and  it  is  generally 
used  in  the  manufacture  of  the  best  iron.  A common  form  of  squeezers  called  the  alligator  is  shown 

2411. 


2413. 


fig.  2406,  an  improvement  over  the  “ Burden’s  Patent  Eccentric  Rotatory  Squeezers,”  illustrated  in  fig. 
2407.  A machine  somewhat  similar  in  its  action,  will  be  found  under  the  head  of  Puddlf.r’s  Balls. 

Figs.  2411,  2412,  and  2413,  illustrate  an  English  machine,  patented  by  Mr.  Jeremiah  Brown,  and  in- 
tended to  serve  the  same  purpose.  The  machine  consists  of  three  large  eccentric  rollers  a,  b,  c,  placed 
horizontally  in  the  strong  holsters  d d,  the  centres  of  the  rollers  being  arranged  in  a triangular  position 
and  the  bottom  roller  c,  nearly  central  between  the  two  top  rollers  a,  b : these  rollers  rotate  in  the  same 
direction  as  shown  by  the  arrows,  and  are  driven  by  a centre  pinion  e,  working  into  three  pinions  of 
equal  stzefff  fixed  on  the  roller  spindles.  In  the  present  machine,  the  driving  power  is  applied  direct 
to  the  bottom  roller,  by  means  of  the  large  wheel  g,  for  the  convenience  of  carrying  the  main  shaft  un- 
der the  floor,  but  it  could  be  applied  to  the  centre  pinion  if  preferred.  The  rollers  are  cast  solid,  with 
their  journals  like  ordinany  rollers,  and  are  driven  in  the  usual  manner  by  coupling  boxes  and  spindles 
li  h.  The  roller  faces  are  sixteen  inches  long,  and  the  bottom  roller  has  strong  flanges  at  each  end  8 
inches  deep,  between  which  the  two  upper  rollers  work ; the  object  of  these  flanges  is  to  upset  or  com- 
press the  ends  of  the  bloom,  as  the  iron  in  the  operation  is  elongated,  and  the  ends  are  forced  against  the 
flanges  which  make  them  square  and 
sound.  The  top  roller  a has  a large 
hollow,  in  which  the  puddled  ball  i is 
placed  by  the  puddler ; and  this  roller  . 
carries  the  ball  round,  and  drops  it  Jj 
into  the  space  between  the  three  ; o 
rollers,  as  shown  in  fig.  2412,  this  ; - 
space  being  at  that  moment  at  its 
largest  capacity.  The  three  project- 
ing points  k k k,  of  the  rollers  imme- 
diately impinge  upon  the  ball,  and 
compress  it  forcibly  on  the  three 
sides,  and,  giving  a rotating  motion 
to  the  ball  at  the  same  time,  they 
have  a very  powerful  kneading  action 
upon  the  iron,  squeezing  out  the  cin- 
der very  effectually,  which  flows 
freely  away,  down  each  side  of  the 
bottom  roller.  The  space  between 
the  rollers  gradually  contracts,  from 

the  eccentric  or  spiral  form  of  the  rollers,  thereby  maintaining  an  increasing  compression  on  the  iron 
on  all  sides  and  the  ends,  until  it  is  liberated  by  the  points  III  simultaneously  passing  the  bloom  m, 
which  falls  down  in  the  direction  of  the  arrow  and  is  discharged  from  the  machine  at  the  same  moment 
that  another  ball  is  dropped  in  at  the  top  of  the  machine.  The  projecting  teeth  on  the  surface  of  the 
rollers  assist  this  action,  by  seizing  hold  of  the  iron  and  kneading  into  it  as  it  rotates  ; and  these  teeth 
gradually  diminish  in  projection,  the  last  portion  of  each  roller  being  plain,  and  the  bloom  is  conse- 
quently turned  out  in  a smooth  compact  form.  The  space  between  the  flanges  of  the  bottom  roller  is 


128 


IRON  ROLLING  MACHINE. 


widened  for  a sliort  distance  beyond  the  point  l,  for  the  purpose  of  allowing  the  bloom  to  drop  out  read* 
ily,  and  admitting  the  fresh  hall. 

A provision  is  made  to  prevent  risk  of  breaking  the  rollers  by  any  unusual  size  of  ball  being  put  in, 
by  means  of  the  two  large  triple-threaded  screws  n re,  which  bear  upon  the  journals  of  one  of  the  top 
rollers  b ; a small  pinion  on  the  head  of  each  of  these  screws  works  into  a large  pinion  fixed  between 
them,  which  has  a horizontal  lever  fixed  to  it,  carrying  a balance  weight  o at  the  end ; this  weight 
causes  a constant  equal  pressure  on  the  roller,  and  in  the  case  of  any  hall  of  extra  size  being  put  into 
the  machine,  the  screws  yield  by  turning  back  and  lifting  the  weight  to  the  extent  that  maybe  required, 
so  that  a large  ball  will  be  worked  with  the  same  pressure  and  in  the  same  effective  manner  as  the 
smaller  sizes.  A continual  supply  of  water  is  run  on  to  all  the  journals  throughout  the  machine,  Which 
prevents  any  possibility  of  the  journals  becoming  hot,  even  when  the  machine  is  in  constant  work. 


IRON  ROLLING  MACHINE — Clay’s  improvement.  We  copy  from  the  inventor’s  specification: 

My  invention  of  certain  improvements  in  machinery,  for  rolling  iron  or  other  metals,  is  designed  la 


IRON  ROLLING  MACHINE. 


129 


produce,  by  the  process  of  rolling,  bars  of  taper  forms,  as  for  instance  wedge-shaped  bars  or  conical 
bars. 

The  tapering  of  metal  bars  I effect  by  allowing  one  of  the  shaping-rollers  to  recede  gradually  frorr 
the  other,  as  the  rolling  operation  goes  on,  and  thus  enlarge  the  space  or  distance  between  the  rollers, 


2416.  2415. 


130 


IRON  ROLLING  MACHINE. 


are  allowed  to  relax  their  resistance  by  a slow  and  gradual  escape  of  the  fluid  from  the  cylinder,  01 
chamber  through  an  adjustable  valve.  The  apparatus  I have  arranged  for  this  purpose  is  shown  in  the 
accompanying  drawings,  in  which  fig.  2414  represents  a vertical  section,  taken  transversely  through  the 
head  of  one  of  the  standards,  wherein  the  bearings  of  the  journals  of  the  rollers  are  mounted,  showing 
the  piston,  its  rod  and  appendages,  with  the  column  of  water  against  which  the  piston  bears,  and  the 
valve,  whereby  a small  quantity  of  the  fluid  may  be  allowed  gradually  to  escape.  Fig.  2415  represents 
a partial  front  view  of  the  rollers,  the  bearings,  and  part  of  the  regulating  apparatus  in  the  head  of  the 
standard,  being  shown  in  section. 

Of  course,  it  will  be  understood  that  two  such  standards  support  the  ends  of  the  rollers.  Fig.  241 G 
is  a horizontal  section,  taken  in  the  line  1,  2,  of  fig.  2414,  showing  the  parts  inverted,  or  as  seen  from 
below  ; and  fig.  2417  is  another  horizontal  section,  taken  on  the  upper  side  in  the  line  3,  4,  of  fig.  2414, 
showing  the  entrance  and  exit  valves  of  the  chamber  of  water,  and  the  means  of  working  or  regulating 
the  exit  valve.  In  the  rolling-mills  usually  employed  for  rolling  bar-iron,  the  rollers  are  generally 
mounted  in  fixed  bearings,  or  bearings  which  during  the  operation  of  rolling,  are  rendered  immovable, 
by  being  maintained  in  their  places  by  strong  screws  or  bolts. 

In  my  improved  machinery,  or  apparatus,  the  ends  of  the  bearing  A,  of  the  upper  roller,  are  let  into 
grooves  in  the  standards,  as  in  ordinary  rolling-mills,  in  such  a manner  as  to  admit  of  their  sliding  up 
and  down  therein,  in  order  that,  by  so  sliding,  the  parallel  distances  between  the  rollers  may  he  allowed 
to  change. 

The  rising  of  the  bearings  with  the  upper  roller  is  regulated  and  governed  by  a piston-rod  a , which 
rests  on  the  top  of  the  bearirigs,  the  upper  end  of  the  piston-rod  being  connected  to  the  solid  piston  b,  of 
the  hydraulic  cylinder,  or  water-chamber  c,  as  shown  in  figs.  2414  and  2415. 

This  cylinder  c,  is  filled  with  water,  or  other  non-elastic  fluid  or  liquid,  and  is  furnished  with  leather 
or  other  suitable  packing,  for  the  purpose  of  preventing  any  leakage  of  the  water. 

The  packing  is  kept  in  its  place  by  a metallic  ring  or  plate  <1,  which  is  firmly  secured  to  the  body  of 
the  cylinder  by  strong  screw-bolts. 

The  cylinder  is  supplied  with  water  from  any  convenient  source,  by  a lateral  tube  p,  shown  in  fig. 
2417,  through  the  rising  feed-valve  e,  the  construction  and  operation  of  which  will  be  clearly  under- 
stood by  referring  to  the  drawing. 

f is  the  exit-valve,  through  which,  when  partially  opened,  the  water  is  allowed  to  escape  from  the 
chamber  c,  on  pressure  being  applied  to  the  lower  end  of  the  rod  a,  by  which  pressure  the  piston  b will 
be  made  to  rise  and  partially  to  expel  the  water,  as  will  be  the  case  when  a bar  of  iron  is  passed  between 
the  shaping  rollers  B B.  The  valve  f is  constructed  in  such  a manner  that  the  opening  for  the  dis- 
charge of  the  water  may  be  regulated  with  the  greatest  exactness  by  merely  advancing  or  receding  the 
plug  g,  worked  by  the  screw  at  its  back  end,  the  effect  of  which  will  be  to  open  or  close  the  valve  to 
any  extent  that  may  be  required. 

There  is  a slight  spring  behind  the  plug  y,  which  is  merely  intended  to  push  it  forward  and  close  the 
aperture  of  the  valve  when  the  upward  pressure  of  the  piston  is  not  in  action,  as  will  be  the  case  when 
the  rolling  operation  is  suspended.  An  additional  valve  h , is  also  made  to  communicate  with  the  exit- 
passage  i.  This  valve,  however,  is  always  kept  closed  by  a strong  spring,  as  shown,  and  will  never  allow 
any  water  to  escape  this  way  from  the  cylinder,  except  when  any  extraordinary  pressure  takes  place,  at 
which  time  the  power  of  the  spring  will  be  overcome,  and,  by  yielding,  prevent  the  machinery  from 
being  too  greatly  strained. 

In  introducing  into  my  improved  machinery  a mass  of  iron  between  the  shaping-rollers,  say  for  the 
purpose  of  producing  a wedge-formed  bar,  having  parallel  edges,  I employ  a pair  of  rollers  of  the  ordi- 
nary kind,  having  the  grooves  and  flanges,  as  shown  in  fig.  2415. 

The  mass  of  iron  being  about  to  be  introduced  between  the  rollers  in  the  first  groove,  I open  the  valve 
/,  by  withdrawing  the  screw  behind  the  plug  g to  such  an  extent  as  will  allow  the  escape  of  water  from 
the  chamber  c in  a small  current,  regulating  the  opening  for  the  intended  discharge  according  to  the 
required  taper  of  the  bar  to  be  formed,  the  required  extent  of  which  opening  will  readily  be  found  by 
the  experience  of  the  workman.  The  operation  of  rolling  now  proceeding,  the  pressure  of  the  metal 
passing  between  the  rollers  will  cause  the  bearings  of  the  upper  roller  to  rise  and  force  up  the  piston- 
rod  a , in  doing  which  the  piston  will  be  made  to  rise  in  the  chamber  c.  But  the  ascent  of  the  piston 
being  resisted  by  the  non-elastic  fluid  in  the  chamber  e,  the  escape  of  water  through  the  valve  /and 
outlet  i must  take  place  to  allow  of  the  ascent  of  the  piston,  and  consequently  the  separation  of  the 
rollers  : according,  therefore,  to  the  rate  of  the  escape  of  water  will  the  taper  or  inclined  shape  of  the 
bar  to  be  produced  be  determined. 

It  will  thus  be  seen  that,  by  my  improved  apparatus,  the  process  of  rolling  metals  is  carried  on  much 
in  the  usual  manner,  except  that,  by  means  of  opening  the  valve  more  or  less,  the  escape  of  the  water 
from  the  chamber  will  allow  the  upper  roller  to  rise,  and  consequently  give  the  requisite  taper  form  to 
the  bar  under  operation,  according  to  the  rapidity  with  which  the  water  is  allowed  to  flow  out  of  the 
chamber.  As  I do  not  intend  to  confine  myself  to  any  particular  forms  of  bars  to  be  produced  by  my 
improved  machinery,  it  is  not  necessary  to  describe  more  precisely  the  shapes  of  the  rollers.  I will  there- 
fore only  add,  that  by  forming  the  grooves  of  the  rollers  in  elliptical  shapes,  as  at  nn,  in  Fig.  4010,  I 
am  enabled,  by  the  gradual  rise  of  one  of  the  rollers,  and  repetitions  of  the  rolling  operation,  to  produce 
bars  of  conical  figures. 

It  is  sometimes  desirable  to  roll  a bar  taper  or  wedge-formed,  for  a portion  of  its  length,  and  level  for 
the  remainder  of  its  length. 

For  this  purpose,  it  will  be  necessary  to  allow  the  upper  roller  to  rise  to  a certain  distance  only,  and 
then  to  stop.  This  I effect  by  means  of  adjusting-screws  k k,  one  over  each  bearing  of  the  rollers,  similar 
to  those  heretofore  used,  except  that  it  is  through  the  axes  of  the  adjusting-screws,  forming  guides,  that 
the  piston-rods  a pass,  as  shown  in  the  drawing  at  Fig.  2414;  and  it  will,  therefore,  be  understood  that 


JACK,  LEVER. 


131 


when,  by  the  escape  of  the  water  from  the  chamber,  the  hearings  of  the  rollers  have  been  allowed  tc 
force  up  the  piston-rod  and  the  piston  a certain  determined  distance,  that  then  the  upper  edge  of  the 
bearing  A,  of  the  top  roller  will  come  into  contact  with  the  under  side  of  the  adjusting-screw  k,  beyond 
which  it  cannot  rise,  and  as  the  hearings  will,  for  a time,  become  fixed,  the  bar  of  iron  under  operation 
will,  for  the  remaining  portion  of  the  process,  be  rolled  parallel. 

The  adjusting-screw  k,  passes  through  a hollow  screw  made  in  a socket  fixed  in  the  frame,  and  the 
screw  can  he  easily  raised  or  lowered,  so  as  to  limit  the  rise  of  the  hearing  A,  by  merely  turning  the 
hand-wheel  l,  attached  to  its  lower  part. 

It  may  he  as  well  to  observe  that  the  standards  or  housings  may  he  of  any  convenient  known  pattern, 
and  that  a lever  or  other  known  balance  may  be  used  with  advantage  to  support  the  roller  in  its  rise  and 
fall.  A portion,  also,  of  the  head  of  the  standard  in  which  the  piston  works  is  made  removable  for  the  pur- 
pose of  getting  at  the  piston  and  packing  when  required,  as  will  be  seen  at  q q,  in  figs.  2415  and  2416. 

JACK.  In  mechanics,  a sort  of  crane  for  raising  heavy  weights.  It  consists,  first,  of  a small  pinion 
wrought  with  a common  winch.  This  pinion  works  in  the  teeth  of  a large  wheel,  on  whose  axis  there 
is  fixed  a small  pinion  with  teeth,  working  in  a rack.  The  turning  of  the  -handle  raises  the  rack,  and  of 
course  any  weight  attached  to  it.  If  the  length  of  the  handle  of  the  winch  be  7 inches,  and  the  pinion 
which  it  drives  contain  4 leaves,  working  in  the  teeth  of  the  large  wheel  having  20  teeth,  then  will  6 
turns  of  the  handle  be  requisite  for  one  of  the  wheel.  But  the  length  of  the  arm  of  the  winch  being  7 
inches,  the  circumference  through  which  the  handle  moves  will  be  about  44  inches,  and  for  one  turn  of 
the  wheel  the  handle  must  pass  through  5 X 44  = 220.  The  wheel  carries  a pinion  of.  say,  3 leaves, 
of  a pitch  of  -j  of  an  inch,  working  the  rack  that  carries  the  weight ; one  turn  of  the  pinion  will,  there- 
fore, raise  the  rack  one  inch,  and  as  the  power  moves  through  220  in  the  same  time,  220  will  be  the 
power  of  the  jack. 

JACK-SCREW.  Figs.  2411,  2412,  and  2413  represent  a plan  of  a jack-screw  for  turning  large  stone, 
used  at  the  United  States  Dry  Dock,  Brooklyn. 


132 


JACK,  TRAVERSING  SCREW. 


' .TACK,  TRAVERSING  SCREW.  Figs.  2415 
and  2416  exhibit  a side  view  and  plan  of  the 
screw  modification.  The  screw-jack  A is  bolted 
to  the  plank  C ; at  the  other  end  of  the  plank  is 
fixed  the  rack  G,  in  which  the  toe  of  the  strut  F 
advances  as  the  screw  B is  elevated ; the  strut 
works  in  a joint  in  the  follower  K : the  position 
2417. 


—{  *L 

^ h 

:d  id 

— - -j i\ 

2416. 

©nnife 

xpnTrm  1 i i 1 1 1 : u mm. 

of  the  strut  when  the  screw  is 
depressed  is  shown  by  the  dotted 
lines.  The  object  of  this  strut 
is  to  relieve  the  screw  of  the  vio- 
lent cross-strain  to  which  the 
apparatus  is  subject,  when  the 
engine  or  carriage  is  pulled  over 
by  the  lever ; which  strain  is 
entirely  transferred  to  the  strut, 
and  the  screw  has  merely  to 
carry  the  load. 

The  operation  of  traversing 
the  jack  is  as  follows : By  hook- 
ing the  link  I upon  the  hook  of  the  lever  E,  the  toe  of  the  lever  being  inserted  into  a ratch  of  the  rack 
II  of  the  lower  plank,  when  a man  bearing  down  the  end  of  the  lever,  drags  the  apparatus  and  engine  or 
carriage  towards  him  with  great  facility ; the  same  lever  is  used  to  turn  the  screw,  and  to  produce  the 
traverse  motion. 


JACK,  TRAVERSING.  Another  form  of  traversing  jack  is  shown  at  fig.  2417,  side  elevation;  fig. 
2418  end  elevation,  and  fig.  2419  section  through  vertical  screw. 

The  lift  of  this  jack  is  effected  by  means  of  a crank,  or  lever,  applied  to  the  axis  a,  which  works  tho 
bevel-geer  b c,  the  latter  geer  being  cut  on  the  projecting  face  of  the  nut  c ; the  revolution  of  this  nut 
lifts  or  lowers  the  vertical  screw,  and  with  it  the  jaw  d ; the  screw-head  moving  freely  in  a socket  of  the 
jaw-head,  permits  the  latter  to  rise  or  fall  without  side  movement. 

2418.  2419. 


The  horizontal  screw  a a , working  into  a nut  in  the  foot  of  the  upper  screw-frame,  effects  the  horizon- 
tal or  traversing  movement  of  the  jack,  the  frame  of  the  lower  screw  serving  as  a bed  or  slide  for  the 
latter  movement.  A ratchet-lever  may  he  used  to  work  either  of  the  screws  instead  of  a crank. 

The  Hydraulic  Jack  (Patent  Portable  Hydraulic  Jack,  R.  Dudgeon,  New  York)  is  the  simplest 


JACQUARD  LOOM. 


and  most  portable  in  comparison  with  the  force  it  is  capable  of  exerting.  This  jack,  or  press,  appeart 
to  the  eye,  when  depressed,  a simple  cylinder,  and  when  elevated,  to  one  cylinder  sliding  within  another. 
It  is  from  two  to  eight  or  more  inches  in  diameter,  according  to  the  power  desired,  with  an  enlarged 
head  (attached  to  the  inner  cylinder,  which  is  the  ram),  having  a socket  for  the  reception  of  the  lever,  by 
which  the  piston  of  the  force  pump  is  worked. 

The  ram,  with  its  head,  contains  just  so  much  water  or  other  fluid  as  is  required  to  fill  the  vacancy 
in  the  cylinder,  caused  by  the  raising  of  the  ram  in  the  act  of  lifting;  and  when  this  is  accomplished 
the  water  is  returned  into  its  original  recess  by  a valve  operated  by  the  lever  that  works  the  pump.  The 
force  pump,  piston  and  valves  are  contained  inside  of  the  ram. 

The  lever  is  detached,  and  may  be  put  on  at  pleasure.  The  joints  in  the  head  maintain  a parallel 
motion  for  the  force  pump  piston,  which  is  the  fulcrum  of  the  lever.  The  ground-lifting  attachment  is 
an  iron  tube  screwed  into  the  lower  side  of  the  head,  and  passing  down  to  the  bottom  of  the  press  out- 
side of  the  cylinder,  on  the  lower  end  of  which  is  a claw  that  supports  the  weight  to  be  raised. 

These  presses  are  light,  portable,  and  of  easy  application.  A press  to  raise  four  tons  not  weighing 
more  than  50  lbs.,  and  one  to  raise  60  tons,  not  more  than  200  lbs.  They  are  all  worked  by  the  labor 
of  one  man  only,  which  is  capable  of  raising  ten  tons  through  a space  of  one  foot  in  one  and  a half  min- 
utes, or  sixty  tons  the  same  distance  in  ten  minutes. 

JACQUARD.  A peculiar  and  most  ingenious  mechanism,  invented  by  M.  Jacquart  of  Lyons,  to  be 
adapted  to  looms  for  superseding  the  employment  of  draw-boys,  in  weaving  figured  goods. 

Fig.  2420  is  a front  elevation  of  this  mechanism,  supposed  to  be  let  down.  Fig.  2421  is  a cross  sec- 
tion, shown  in  its  highest  position.  Fig.  2422  the  same  section,  but  seen  in  its  lower  position. 

A,  is  the  fixed  part  of  the  frame,  supposed  to  form  a part  of  the  ordinary  loom ; there  are  two  up- 
rights of  wood,  with  two  cross-bars  uniting  them  at  their  upper  ends,  and  leaving  an  interval  xy,  be- 
tween them,  to  place  and  work  the  movable  frame  B,  vibrating  round  two  fixed  points  a a,  placed  late- 
rally opposite  each  other,  in  the  middle  of  the  space  x y , fig.  2420. 

C,  is  a piece  of  iron  with  a peculiar  curvature,  seen  in  front,  fig.  2420,  and  in  profile,  figs.  2421  and 
2422.  It  is  fixed  on  one  side  upon  the  upper  cross-bar  of  the  frame  B,  and  on  the  other,  to  the  inter- 
mediate cross-bar  b,  of  the  same  frame,  where  it  shows  an  inclined  curvilinear  space  c,  terminated  below 
by  a semi-circle. 

D,  is  a square  wooden  axis,  movable  upon  itself  round  two  iron  pivots,  fixed  into  its  two  ends ; which 
axis  occupies  the  bottom  of  the  movable  frame  B.  The  four  faces  of  this  square  axis  are  pierced  with 
three  round,  equal,  truly-bored  holes,  arranged  in  a quincunx.  The  teeth  a,  fig.  2424,  are  stuck  into 
each  face,  and  correspond  to  holes  a,  fig.  2427,  made  in  the  cards  which  constitute  the  endless  chain  for 
the  healds ; so  that  in  the  successive  application  of  the  cards  to  each  face  of  the  square  axis,  the  holes 
pierced  in  one  card  may  always  fall  opposite  to  those  pierced  in  the  other. 

The  right-hand  end  of  the  square  axis,  of  which  a section  is  shown  in  double  size,  fig.  2423,  carries 
two  square  plates  of  sheet  iron  d,  kept  parallel  to  each  other  and  a little  apart  by  four  spindles  e,  passed 
opposite  to  the  corners.  This  is  a kind  of  lantern,  in  whose  spindles  the  hooks  of  the  levers  ff  \ turning 
round  fixed  points  g g',  beyond  the  right  hand  upright  A,  catch  hold,  either  above  or  below,  at  the  plea- 
sure of  the  weaver,  according  as  he  merely  pulls  or  lets  go  the  cord  z,  during  the  vibratory  movement 
of  the  frame  B. 

E,  is  a piece  of  wood  shaped  like  a T,  the  stem  of  which,  prolonged  upwards,  passes  freely  through 
the  cross-bar  b,  and  through  the  upper  cross-bar  of  the  frame  B,  which  serve  as  guides  to  it.  The  head 
of  the  T piece  being  applied  successively  against  the  two  spindles  e,  placed  above  in  a horizontal  position, 
first  by  its  weight,  and  then  by  the  spiral  spring  h,  acting  from  above  downwards,  keeps  the  square  axis 
in  its  position,  while  it  permits  it  to  turn  upon  itself  in  the  two  directions.  The  name  press  is  given  to 
the  assemblage  of  all  the  pieces  which  compose  the  movable  frame  B B. 

F,  is  a cross-bar  made  to  move  in  a vertical  direction  by  means  of  the  lever  G,  in  the  notches  or 
grooves  i,  formed  within  the  fixed  uprights  A. 

H,  is  a piece  of  bent  iron,  fixed  by  one  of  its  ends  with  a nut  and  screw,  upon  the  cross-bar  F,  out  of 
the  vertical  plane  of  the  piece  C.  Its  other  end  carries  a friction  roller  J,  which  working  in  the  curvi- 
linear space  c of  the  piece  C,  forces  this,  and  consequently  the  frame  B,  to  recede  from  the  perpendicular 
or  to  return  to  it,  according  as  the  cross  bar  F is  in  the  top  or  bottom  of  its  course,  as  shown  in  fio-s, 
2421  and  2422. 

I,  cheeks  of  sheet  iron  attached  on  either  side  to  the  cross-bar  F,  which  serves  as  a safe  to  a kind  of 
claw  K,  composed  here  of  eight  small  metallic  bars,  seen  in  section  figs.  2421  and  2422,  and  on  a greater 
scale  in  fig.  2424. 

J,  upright  skewers  of  iron  wire,  whose  tops,  bent  down  hookwise,  naturally  place  themselves  over  the 
little  bars  R.  The  bottom  of  these  spindles,  likewise  hooked  in  the  same  direction  as  the  upper  ones, 
embraces  small  wooden  bars  l,  whose  office  is  to  keep  them  in  their  respective  places,  and  to  prevent 
them  from  twirling  round,  so  that  the  uppermost  hooks  may  be  always  directed  towards  the  small  metal- 
lic bars  upon  which  they  impend.  To  these  hooks  from  below  are  attached  strings,  which  after  having 
crossed  a fixed  board,  m n , pierced  with  corresponding  holes  for  this  purpose,  proceed  next  to  be  attached 
to  the  threads  of  the  loops  destined  to  lift  the  warp  threads.  K K,  horizontal  spindles  or  needles,  ar- 
ranged here  in  eight  several  rows,  so  that  each  spindle  corresponds  both  horizontally  and  vertically  to 
each  of  the  holes  pierced  in  the  four  faces  of  the  square  axis  D.  There  are  therefore  as  many  of  these 
spindles  as  there  are  holes  in  one  of  the  faces  of  the  square. 

Fig.  2425  represents  one  of  these  horizontal  spindles,  n is  an  eyelet  through  which  the  correspond- 
ing vertical  skewer  passes.  o another  elongated  eyelet,  through  which  a small  fixed  spindle  passes  tc 
serve  as  a guide,  but  which  does  not  hinder  it  from  moving  lengthwise,  within  the  limits  of  the  length 
of  the  eyelet,  p small  spiral  springs  placed  in  each  hole  of  the  case  q q,  fig.  2424.  They  serve  to  bring 
oack  to  its  primitive  position,  every  corresponding  needle,  as  soon  as  it  ceases  to  press  upon  it. 


13 1 


JACQUARD  LOOM. 


Fig.  2426  represents  the  plan  of  the  upper  row  of  horizontal  needles.  Fig.  2427  is  a fragment  of  tlx 
endless  chain,  formed  with  perforated  cards,  which  are  made  to  circulate  or  travel  by  the  rotation  of  the 
shaft  IX  In  this  movement,  each  of  the  perforated  cards,  whose  position,  form  and  number,  are  deter- 
mined hy  the  operation  of  tying-up  of  the  warp,  comes  to  be  applied  in  succession  against  the  four  faces 
of  the  square  axis  or  drum,  leaving  open  the  corresponding  holes,  and  covering  those  upon  the  face  of 
the  axis,  which  have  no  corresponding  holes  upon  the  card. 


Now  let  us  suppose  that  the  press  B is  let  down  into  the  vertical  position  shown  in  fig.  2422  ; then  tli» 
sard  applied  against  the  left  face  of  the  axis,  leaves  at  rest  or  untouched  the  whole  of  the  horizontal 
spindles  (skewers),  whose  ends  correspond  to  these  holes,  but  pushes  back  those  which  are  opposite  tc 
the  unpierced  part  of  the  card  ; thereby  the  corresponding  upright  skewers,  3,  5,  6,  and  8,  for  example. 


JACQUARD  LOOM. 


13A 


pushed  out  of  the  perpendicular,  unhook  themselves  from  above  the  bars  of  the  claw,  and  remain  ir 
their  place,  when  this  claw  comes  to  be  raised  by  means  of  the  lever  G ; and  the  skewers  1,  2,  4,  and 
7,  which  have  remained  hooked  on,  are  raised  along  with  the  warp  threads  attached  to  them.  Then  by 
the  passage  across  of  a shot  of  the  color,  as  well  as  a shot  of  the  common  weft,  and  a stroke  of  the  lay 
after  shedding  the  warp  and  lowering  the  press  B,  an  element  or  point  in  the  pattern  is  completed. 

The  following  card,  brought  round  by  a quarter  revolution  of  the  axis,  finds  all  the  needles  in  their 
first  position,  lifts  another  series  of  warp  threads ; and  thus  in  succession  for  all  the  other  cards,  which 
compose  a complete  system  of  a figured  pattern. 

If  some  warp  yarn  should  happen  to  break  without  the  weaver  observing  them,  or  should  he  mistake 


his  colored  shuttle  yarns,  which  would  so  far  disfigure  the  pattern,  he  must  undo  his  work.  For  this 
purpose,  he  makes  use  of  the  lower  hooked  lever  f,  whose  purpose  is  to  make  the  chain  of  the  card  go 
backwards,  while  working  the  loom  as  usual,  withdrawing  at  each  stroke  the  shot  both  of  the  ground  and 
of  the  figure.  The  weaver  is  the  more  subject  to  make  mistakes,  as  the  figured  side  of  the  web  is 
downwards,  and  it  is  only  with  the  aid  of  a bit  of  looking-glass  that  he  takes  a peep  of  his  work  from 
time  to  time.  The  upper  surface  exhibits  merely  loose  threads  in  different  points,  according  as  the 
pattern  requires  them  to  lie  upon  the  one  side  or  the  other. 

Thus  it  must  be  evident,  that  such  a number  of  paste-boards  are  to  be  provided  and  mounted  as 
equal  the  number  of  throws  of  the  shuttle  between  the  beginning  and  end  of  any  figure  or  design  which 
is  to  be  woven ; the  piercing  of  each  paste-board  individually,  will  depend  upon  the  arrangement  of  the 
lifting  rods,  and  their  connection  with  the  warp,  which  is  according  to  the  design  and  option  of  the 
workman;  great  care  must  be  taken  that  the  holes  come  exactly  opposite  to  the  ends  of  the  needles  ; 
for  this  purpose  two  large  holes  are  made  at  the  ends  of  the  paste-boards,  which  fall  upon  conical  points, 
by  which  means  they  are  made  to  register  correctly. 

It  will  be  here  seen,  that,  according  to  the  length  of  the  figure,  so  must  be  the  number  of  paste- 
boards, which  may  be  readily  displaced  so  as  to  remount  and  produce  the  figure  in  a few  minutes,  ox' 

2426  2427 


l 

1 ° § o Ogo0  c°  - « fo  n<io§o0°g  °c,  ” S c.<VSj*o°°  8 I1 

t 

L 

I CL  o OC0  D°  0,°*0o  °00  °o  °°n  Q °0l°  rP°  °„  ° rt°°o  V °!°  00°  [f 

}•'&  o ^8^0  0°o°00?0D  rgo  OOtfo  O0<5*  00°o  8 R08o°off  i 

O °°  ° 5°  0>0  0OCP°0OOCOc'Oce  CC00o0  OO^O  S . Q 
o qoO  ooe  Ooooooor.°,.ooo  to  0 o co  o 

S ° o°  o o°0  °o  C°  o0g  © °o  o w 000  °o°  o°oo  r 

remove  it,  or  replace  it,  or  preserve  the  figure  for  future  use.  The  machine,  of  course,  will  be  under- 
stood to  consist  of  many  sets  of  the  lifting  rods  and  needles,  shown  in  the  diagram,  as  will  be  perceived 
by  observing  the  disposition  of  the  holes  in  the  paste-board ; those  holes,  in  order  that  they  may  be  ac- 
curately distributed,  are  to  be  pierced  from  a gauge,  so  that  not  the  slightest  variation  shall  take  place. 

To  form  these  card-slips,  an  ingenious  apparatus  is  employed,  by  which  the  proper  steel  punches  re- 
quired for  the  piercing  of  each  distinct  card,  are  placed  in  their  relative  situations  preparatory  to  the 
operation  of  piercing,  and  also  by  its  means  a card  may  be  punched  with  any  number  of  holes  at  one 
operation.  This  disposition  of  the  punches  is  effected  by  means  of  rods  connected  to  cords  disposed  in 
a frame,  in  the  nature  of  a false  simple,  on  which  the  pattern  of  the  work  is  first  read  in. 

These  improved  pierced  cards,  slips,  or  paste-boards,  apply  to  a weaving  apparatus,  which  is  so  ar- 
ranged that  a figure  to  be  wrought  can  be  extended  to  any  distance  along  the  loom,  and  by  that  means 
the  loom  is  rendered  capable  of  producing  broad  figured  works ; having  the  long  lever  G placed  in  such 
a situation  that  it  affords  power  to  the  foot  of  the  weaver,  and  by  this  means  enables  him  to  draw  the 
heaviest  morintures  and  figured  works,  without  the  assistance  of  a draw-boy. 

The  machinery  for  arranging  the  punches,  consists  of  a frame  with  four  upright  standards  and  cross- 
pieces, which  contains  a series  of  endless  cords  passing  under  a wooden  roller  at  bottom,  and  over  pul- 
leys at  the  top. 

Fig.  2428  represents  a single  endless  cord  1 1,  which  is  here  shown  in  operation,  and  part  of  anothel 
endless  cord  2 2,  shown  stationary.  There  must  be  as  many  endless  cords  in  this  frame  as  needles  in 
the  weaving-loom  a is  the  wooden  cylinder,  revolving  upon  its  axis  at  the  lower  part  of  the  standard ; b i 


136 


JACQUARD  PERFORATING  MACHINE. 


the  two  pulleys  of  the  pulley-frames  above,  over  which  the  indivi- 
dual endless  cord  passes ; c is  a small  transverse  ring.  To  each  of 
these  rings  a weight  is  suspended  by  a single  thread,  for  the  purpose 
of  giving  tension  to  the  endless  cord,  d is  a board  resembling  a com- 
mon comber-bar,  which  is  supported  by  the  cross-bars  of  thestand- 
ard  frame,  and  is  pierced  with  holes,  in  situation  and  number,  cor- 
responding with  the  perpendicular  threads  that  pass  through  them ; 
which  board  keeps  the  threads  distinct  from  each  other. 

At  e the  endless  cord  passes  through  the  eyes  of  wires  resembling 
needles,  which  are  contained  in  a wooden  box  placed  in  front  of  the 
machine,  and  shown  in  this  figure  in  section  only.  These  wires  are 
called  the  punch  projectors  ; they  are  guided  and  supported  by  hori- 
zontal rods  and  vertical  pins,  the  latter  of  which  pass  through  loops 
formed  at  the  hinder  part  of  the  respective  wires.  At  f are  two 
horizontal  rods  extending  the  whole  width  of  the  machine,  for  the 
purpose  of  producing  the  cross  in  the  cords  ; g is  a thick  brass  plate, 
extending  along  in  front  of  the  machine,  and  lying  close  to  the  box 
which  holds  the  punch-projectors ; this  plate  g,  shown  also  in  section, 
is  called  the  punch-holder ; it  contains  the  same  number  of  apertures 
as  there  are  punch-projectors,  and  disposed  so  as  to  correspond  with 
each  other.  In  each  of  these  apertures  there  is  a punch  for  the 
purpose  of  piercing  the  cards,  slips,  or  pasteboards  with  holes ; h is 
a thick  steel  plate  of  the  same  sizeas  h,  and  shown  likewise  in  sec- 
tion, corresponding  also  in  its  number  of  apertures,  and  their  dispo- 
sition, with  the  punch-projectors  and  the  punch-holder.  This  plate 
h , is  called  the  punch-receiver. 

The  object  of  this  machine  is  to  transfer  such  of  the  punches  as  may  be  required  for  piercing  any  in- 
dividual card  from  the  punch-holder  g,  into  the  punch-receiver  h ; when  they  will  be  properly  situated, 
and  ready  for  piercing  the  individual  card  or  slip,  with  such  holes  as  have  been  read  in  upon  the  machine, 
and  are  required  for  permitting  the  warp  threads  to  be  withdrawn  in  the  loom,  when  this  card  is  brought 
against  the  ends  of  the  needles.  The  process  of  transferring  the  patterns  to  the  punches  is  thus  effected. 

The  pattern  is  to  be  read  in  according  to  the  ordinary  mode,  as  in  a false  simple,  upon  the  endless 
cords  below  the  rod  f and  passed  under  the  revolving  wooden  cylinder  a,  to  a sufficient  height  for  a per- 
son in  front  of  the  machine  to  reach  conveniently.  He  there  takes  the  upper  threads  of  the  pattern, 
called  the  beard , and  draws  them  forward  so  as  to  introduce  a stick  behind  the  cords  thus  advanced,  as 
shown  by  dots,  for  the  purpose  of  keeping  them  separate  from  the  cords  which  are  not  intended  to  he 
operated  upon.  All  the  punch-projectors  which  are  connected  with  the  cords  brought  forward,  will  be 
thus  made  to  pass  through  the  corresponding  apertures  of  the  punch-holder  g,  and  by  this  means  will 
project  the  punches  out  of  these  apertures,  into  corresponding  apertures  of  the  punch  receiver  h.  The 
punches  will  now  be  properly  arranged  for  piercing  the  required  holes  on  a card. 

Remove  the  punch-receivers  from  the  front  of  the  machine ; and  having  placed  one  of  the  slips  of 
card  or  pasteboard  between  the  two  folding  plates  of  metal,  completely  pierced  with  holes  corresponding 
to  the  needles  of  the  loom,  lay  the  punch-receiver  upon  those  perforated  plates,  to  which  it  must  be 
made  to  fit  by  mortices  and  blocks,  the  cutting  parts  of  the  punches  being  downwards.  Upon  the  back 
of  the  punch-receiver  is  then  to  be  placed  a plate  or  block,  studded  with  perpendicular  pins  correspond- 
ing to  the  above  described  holes,  into  which  the  pins  will  fall.  The  plates  and  the  blocks  thus  laid  to- 
gether, are  to  be  placed  under  a press,  by  which  means  the  pins  of  the  block  will  be  made  to  pass 
through  the  aperture  of  the  punch-receiver ; and  wherever  the  punch  has  been  deposited  in  the  receiver 
by  the  above  process,  the  said  punches  will  be  forced  through  the  slip  of  pasteboard,  and  pierced  with 
such  holes  as  are  required  for  producing  the  figured  design  in  the  loom. 

Each  card  being  thus  pierced,  the  punch-receiver  is  returned  to  its  place  in  front  of  the  machine,  and 
all  the  punches  forced  back  again  into  the  apertures  of  the  punch-holder  as  at  first.  The  next  set  of 
cords  is  now  drawn  forward  by  ths  next  beard,  as  above  described,  which  sends  ont  the  punch-projectors 
as  before,  and  disposes  the  punches  in  the  punch-receiver,  ready  for  the  operation  of  piercing  the  next 
card.  The  process  being  thus  repeated,  the  whole  pattern  is,  by  a number  of  operations,  transferred  to 
the  punches,  and  afterwards  to  the  cards  or  slips,  as  above  described.  See  Loom. 

JACQUARD  PERFORATING  MACHINE.  Machine  for  perforating  metal  plates,  such  as  are  used 
for  steam-boilers,  &c.  ; and  employed  for  punching  the  plates  of  the  tubular  bridge  at  Conway,  made  at 
the  Globe  Works,  Manchester,  by  Messrs  Roberts,  Fothergibl  & Co. 

Fig.  2420  represents  a sectional  elevation  of  the  machine;  Fig.  2421  an  elevation  of  the  back  of  the 
machine;  Fig.  2422  a plan  view  of  the  apparatus  for  putting  the  punches  out  of  action  without  stopping 
the  fly-wheel ; and  Fig.  2423  a plan  view  of  a few  of  the  jacquard  plates.  Fig.  242G  represents  a front 
elevation  ; Fig.  2427  a side  elevation ; and  Fig.  2428  a horizontal  section,  taken  through  the  dotted  lines 
A 'A1,  in  Figs.  2426  and  2427.  Fig.  2429  is  a detached  view  of  the  traverse  apparatus,  and  Fig.  2430 
a detached  view  of  the  holding-down  or  stripping  apparatus.  A A the  standards.  B the  bed,  through 
which  there  is  an  opening  for  the  punchings,  or  metal  punched  out  of  the  plate,  to  fall  through  ; tliis  bed 
is  inserted  into  the  standards.  C a stretcher-bar,  to  connect  the  top  of  the  standards.  D,  fulcrum  of  the 
levers  q q which  withdraw  the  punches,  and  of  the  lever  w which  traverses  the  plate.  E a fulcrum  shaft, 
to  which  the  levers  jj  and  hlc  are  keyed.  F the  main  or  eccentric  shaft,  working  in  bushes  in  the 
standards.  G a spur-wheel,  keyed  on  the  eccentric-shaft.  1 1 a pinion,  working  into  the  wheel  G.  I the 
fly-wheel  shaft,  on  which  are  the  fast  and  loose  pulleys  K and  L,  the  pinion  H,  and  the  fly-wheel  J. 
M M connecting-rods,  fitted  to  the  eccentric  necks  of  the  shaft  F.  N N caps  of  the  connecting-rods  M M 


JACQUARD  PERFORATING  MACHINE. 


137 


2420. 


0 0 guide-plates  for  the  punch-rams  P P.  Q the  cam-shaft,  R a spur-wheel,  loose  on  the  cam-snail 
and  having  on  one  side  two  projections,  between  which  there  is  an  opening.  R*  a locking-disk  or  plate 


138 


JACQUARD  PERFORATING  MACHINE. 


JACQUARD  PERFORATING  MACHINE. 


139 


keyed  on  the  shaft  Q,  having  upon  it  a spring-catch  38,  which  takes  into  the  opening  between  the  pro 
jectious  on  the  wheel  R.  R and  R*  are  seen  detached  in  Fig.  2425, 24  252:  the  dotted  lines  on  R*  repre- 
sent a weight  to  counterbalance  the  levers  k.  S a toothed-wheel,  keyed  on  the  main-shaft  F.  T the 
punch-ram  depressor,  secured  to  the  connecting-rods  M M by  knuckle-joints  at  the  lower  end  of  the 
connecting-rods.  U a slide-bar,  on  which  the  frame  traverses  which  carries  the  plate  to  be  punched. 
V V two  short  slide-bars,  to  carry  one  side  of  the  traverse-frame.  W a block  of  iron,  fastened  with 
short  wedges  to  the  bed  B to  carry  the  die-plate  X,  into  which  the  dies  d are  inserted,  and  prevented 
from  rising  by  a collar  at  the  lower  end  of  each,  as  seen  ir  Fig.  2430.  Y a square  shaft,  carrying  the 
holding-down  levers  or  stripping-fingers  oo  Z Z levers  on  each  end  of  the  shaft  Y.  a a the  punches  let 
into  the  punch-holders  b b bolted  to  the  rams  P,  as  seen  in  the  detached  view,  Fig.  2424.  c c pieces 
bolted  to  the  bed  B to  carry  the  adjusting  slide-bars  V Y.  d dies  inserted  into  the  holder  X.  ee,  Fig 
2420,  are  the  selecting  slide-bars,  which,  when  allowed  to  pass  through  the  card-plate,  enter  the  card 
roller/,  without  being  pushed  backwards  by  them;  the  card-roller  has  in  this  case  six  sides,  and  the 
belt  of  jacquard-plates,  after  passing  over  it  in  the  usual  manner,  passes  over  a round  roller  suspended 
in  a swing-frame,  at  such  an  angle  as  shall  keep  the  belt  moderately  tight,  whilst  the  roller/ advances 
towards  and  recedes  from  the  selectors  e.  r/g  brackets  projecting  from  the  depressor  T,  and  carried  up 
and  down  with  it.  h h sliding-blocks,  in  which  the  journals  of  the  card-roller  turn.  To  an  upright  cast 
on  each  of  these  blocks,  is  fitted  a rod  of  round  iron,  thus  *,  with  a flat  foot,  long  enough  to  extend  over 
two  of  the  six  pins  in  the  ends  of  the  card-roller,  against  which  the  flat  foot  of  the  rods  is  made  to  press, 
by  spiral-springs  coiled  around  them  in  the  usual  manner  employed  in  the  jacquard-loom,  which  is  gen- 
erally known,  and  need  not  be  further  described,  ii,  Fig.  2420,  are  two  sets  of  guide-blocks,  for  the 
selectors  e,  one  on  each  side  of  the  depressor,  adjustable  laterally  by  set-screws  on  flat  bars,  extending 
across  the  machine ; the  use  of  these  blocks  is  to  carry  the  selecting-bars  e,  which  are  round  at  the  end 
that  enters  the  cards,  and  flat  at  the  other  end,  to  keep  them  in  their  proper  positions ; the  centre  por- 
tion of  each  selecting-bar  is  a solid  piece  of  iron,  projecting  as  much  below  the  round  stem  as  will,  when 
the  selecting-bar  is  driven  backwards  by  a card-plate,  permit  the  depressor  T to  complete  its  downward 
stroke  without  the  selecting-bar  touching  the  ram  P under  it.  jj  are  levers  keyed  on  the  shaft  E,  and 
connected  at  their  lower  end  by  links  to  the  slide-blocks  h h.  k k are  levers  also  keyed  on  the  shaft  E 
and  having  each  a friction-roller  at  its  lower  extremity.  On  the  shaft  Q are  two  cams,  one  of  which 
works  a lever  k on  one  side  of  the  shaft,  and  the  other  cam  works  the  other  lever  k on  the  opposite 
side.  One  of  the  cams,  through  the  medium  of  the  levers  jj,  and  the  links  before  referred  to,  causes  the 
roller/ to  approach  the  selecting-bars  e,  and  the  other  cam  causes  the  roller  to  recede  from  them,  until, 
by  a catch  employed  in  the  ordinary  way  in  the  jacquard-looms,  the  roller  / is  made  to  turn  through 
one-sixth  of  a revolution,  and  is  then  retained  in  that  position  by  the  pressure  of  the  spiral-spring 
and  flat  foot  above  referred  to.  1 1 are  brackets  attached  to  the  depressor  T at  the  back  of  the  ma- 
chine. m a bar  resting  on  the  brackets  1 1,  and  connected  by  rods  with  the  sliding-blocks  h h,  which, 
on  receding,  cause  the  bar  m to  bring  all  the  selecting-bars  e into  the  position  for  depressing  the  rams, 
as  seen  in  Fig.  2430.  tin  are  levers  having  their  fulcra  on  studs  screwed  into  the  standards;  one 
end  of  these  levers  is  connected  by  a rod  p with  the  levers  Z Z ; the  other  end  is  furnished  with  a 
roller  which  is  acted  upon  by  a cam  u on  the  shaft  Q.  oo  are  the  holding-down  levers,  adjustable 
laterally  on  the  shaft  Y,  so  as  to  admit  of  one  of  them  being  placed  on  each  side  of  every  punch. 
pp  are  rods  connecting  the  levers  n and  Z.  By  adjusting  the  length  of  these  rods,  the  levers  oo 

are  made  to  press  upon  plates  of  different  thicknesses,  so  as  to  hold  the  plates  down  while  the 

punches  are  being  withdrawn,  q q levers  turning  on  the  fulcrum-bar  D for  withdrawing  the  punches 
by  means  of  the  cams  r r that  actuate  levers  q q.  sa  broad  but  rather  thin  bar,  extending  through 
the  series  of  punch-rams  P,  shown  by  dotted  lines.  The  punch-rams  P are  made  with  slots,  through 
which  the  bar  s passes,  and  these  slots  must  be  about  two  inches  longer  than  the  width  of  the  bar  s, 
in  order  to  allow  the  punch-rams  to  be  forced  down  when  the  bar  is  at  the  bottom  of  its  stroke. 
1 1 are  links  connecting  the  bar  s with  the  levers  q q.  uu  are  cams  which  depress  the  holding- 
down  levers  oo,  through  the  medium  of  the  levers  n n,  rods  pp,  and  levers  ZZ,  and  hold  down  the 
plate  while  the  punches  are  being  withdrawn,  v a cam  for  the  traversing-rack  5.  w a lever 
turning  on  the  fulcrum-bar  D,  and  worked  by  the  cam  v.  x the  cam  for  lifting  the  rack  5.  y a lever 

turning  on  a stud  in  the  standard,  and  worked  by  the  cam  x for  lifting  the  traversing-rack  5.  z a rod 

connecting  the  lever  y with  the  lever  8.  1 is  a lever  on  the  traverse-shaft  2 ; 3 another  lever  on 

the  shaft  2.  4 a link  connecting  the  lever  3 with  the  rack  5.  6 a rod  connecting  the  lever  w with 

the  lever  1 for  traversing  the  rack  5.  7 a shaft  for  carrying  the  levers  8,  9,  and  10.  11a  link  con- 
necting the  levers  10  and  12.  13  a shaft  carrying  the  levers  12  and  14.  15  and  16  are  links  con- 
necting the  rack  5 with  the  levers  9 and  14.  17  the  upper  or  retaining  rack.  18  a stud  carrying  t lie 

elbow-lover  19,  which  is  provided  with  a handle.  20  another  stud  carrying  the  elbow-lever  21,  which 
is  connected  by  a link  22  with  the  lever  19.  The  rack  17  is  carried  on  studs  in  the  horizontal  arm  of  the 
levers  19  and  21.  23  division-studs  in  the  bar  24  of  the  traversing-frame. 

The  plate  to  be  punched  is  put  into  a traversing-frame  formed  of  two  side-bars  24  and  25,  and  two 
stretcher-bars  secured  by  cottars  to  the  side-bars,  which  are  rabbeted  to  support  the  plate,  and,  when 
required,  furnished  with  clamps  to  hold  the  plate  down.  24  represents  one  of  the  sides  of  the  trav- 
ersing-frame, in  which  there  is  a groove  to  fit  on  the  slide-bar  U ; into  the  outer  side  of  the  bar  24  is 
screwed  a series  of  studs  23,  represented  in  the  engravings  as  being  12  inches  from  centre  to  centre 
apart  from  each  other.  The  side  25  of  the  frame  slides  on  the  bars  V Y.  When  the  plates  to  be 
punched  are  very  long,  rollers  may  be  used  to  carry  the  projecting  ends  of  the  traversing-frame.  In 
Fig.  2428  is  shown  part  of  a frame,  with  a plate  partly  perforated.  The  racks  5 and  17,  Fig.  2429,  are 
drawn  with  three  teeth  in  the  length  of  a foot,  which  will  divide  plates  to  a four-inch  pitch ; but  it  will 
be  obvious,  that  for  a different  pitch  the  racks  must  be  changed,  and  it  may  in  some  cases,  (such  as 
when  the  pitch  required  is  not  an  aliquot  part  of  a foot,)  be  necessary  to  alter  the  distance  between  the 
studs  23.  Fig.  2429  represents  the  traverse  apparatus,  in  the  position  it  will  be  in  when  the  retaining 


1 40 


JACQUARD  PERFORATING  MACHINE. 


JACQUARD  PERFORATING  MACHINE. 


141 


2427. 


G 


1412 


JAPANNING. 


rack  is  down,  and  the  punches  in  the  act  of  passing  through  the  plate,  and  the  traversing-rack  having 
completed  its  return-stroke. 

When  the  punches  are  being  raised,  the  traversing-rack  will  rise  also;  and  by  the  side-piece  26 
(which  is  attached  to  it)  acting  against  the  roller  27,  on  a stud  in  the  rack  17,  will  raise  it  also,  and  set 
the  frame  at  liberty  to  be  advanced  by  the  cam  x,  through  the  mechanical  means  already  described 
In  Fig.  2420  this  traverse  apparatus  is  shown  in  the  position  it  assumes  when  the  plate  is  advancing 
The  spiral-spring  28  acts  on  the  lever  21,  and  forces  the  rack  17  down  on  to  the  pins  23.  For  every 
hole  required  to  be  punched  in  line  with  the  width  of  the  plate  under  operation,  a corresponding 
hole  must  be  made  in  a plate  of  the  jacquard,  and  an  additional  hole,  marked  30,  is  also  made,  int« 
which  the  stopping-bar  31  enters  at  every  stroke  until  the  punching  be  completed,  at  which  time 
the  jacquard-plate  32,  which  is  left  blank,  will  push  all  the  selecting-bars  e beyond  the  rams  P,  and  at 
the  same  time,  by  pushing  the  bar  31,  disengage  the  cam-shaft  Q,  by  the  mechanism  to  be  hereafter 
explained,  at  the  point  where  the  punches  and  the  levers  o are  held  up,  and  thus  will  allow  the  perfo- 
rated plate  to  be  taken  out  of  the  machine,  and  another  plate  to  be  put  into  it.  The  stopping-bar  31  is 
provided  with  a projection  on  its  lower  surface,  which  depresses  the  click-lever  39  when  the  bar  is 
pushed  back;  the  lever  33  is  keyed  on  a shaft  34,  moving  in  bearings  at  the  back  of  the  depressor;  on 
the  other  end  of  the  shaft  34  is  keyed  the  lever  35,  to  the  upper  end  of  which  is  attached  the  link  36, 
connecting  it  with  the  elbow-lever  37  ; the  end  of  the  other  arm  of  this  lever  is  inclined,  for  the  purpose 
of  unlocking  the  plate  R*  and  is  provided  with  a stud,  on  which  is  a latch  38,  the  tail  of  which  comes 
m contact  with  the  incline  on  the  elbow-lever  37,  when  it  is  in  the  position  shown  in  dotted  lines  in  Fig. 
2422  ; and  as  the  wheel  R revolves,  the  latch  becomes  disengaged  from  the  opening  between  the  two 
projections  cast  on  the  said  wheel,  at  which  time  the  cam-shaft  Q ceases  to  revolve.  When  the  stopping- 
bar  31  has  been  pushed  back,  it  depresses  the  lever  39,  and  liberates  the  lever  33  from  behind  the 
projection  on  the  lever  39,  when  the  spring  40  will  pull  the  elbow-lever  37  into  the  position  shown 
in  dotted  lines.  To  the  blocks  h a small  shaft  is  attached,  on  which  are  two  levers,  suspending  by 
links  a plate  of  metal  similar  to  a blank  card-plate,  except  that  the  holes  for  the  guide-pifas  are  cut  at 
the  bottom  edge.  At  each  end  of  the  same  shaft  is  a lever-handle,  held  up  or  down  by  a side-spring  in 
the  ordinary  way.  The  use  of  this  apparatus  is  as  follows ; Should  it  be  required  to  stop  the  machine 
before  the  plate  is  finished,  by  raising  the  lever  here  referred  to,  the  blank  plate  will  come  in  front  ot 
the  roller,  and  will  act  the  part  of  a blank  jacquard-plate,  and  stop  the  machine. 

Flaving  now  described  the  principal  parts  of  the  machine,  we  shall  proceed  to  explain  the  manner  of 
its  working.  The  plate  to  be  punched  having  been  placed  in  the  traversing-frame,  on  the  sides  U and 
V,  is  then  pushed  forward.  In  its  progress,  the  first  pin  of  the  series  23  passes  under  the  inclined  end 
of  the  rack  17,  until  the  first  notch  in  the  rack  falls  upon  the  pin.  The  driving-strap  being  now  on  the 
fast  pulley  K,  the  machine  is  set  to  work  by  pulling  down  the  handle  42,  keyed  on  the  shaft  34,  until 
the  lever  33  is  latched  by  the  click-lever  39  ; the  elbow-lever  37  is  then,  by  the  spiral-spring  40,  brought 
into  the  position  shown  in  Fig.  2422.  The  latch  38  being  now  liberated,  will,  by  the  action  of  the  spring 
41,  Fig.  2420,  drop  into  the  notch  in  the  wheel  R the  first  time  it  comes  round ; the  cam-shaft  Q wall 
now  revolve  at  the  same  speed  as  the  shaft  F,  and  the  jacquard-roller/ will  be  drawn  back  and  made 
to  perform  l-6th  of  a revolution  on  its  centres,  after  which  it  will  be  advanced,  and  the  first  card  of  the 
series  will  remove  those  selecting-bars  for  which  there  are  no  holes  in  the  jacquard-plate ; the  other 
selecting-bars  will  remain  over  their  respective  rams  P,  which  will  then  force  down  the  punches  through 
the  plate,  by  the  descent  of  the  depressor  T.  A little  before  the  punches  have  gone  through  the  plate 
under  operation,  the  levers  o are  made  to  press  upon  it,  and  are  held  there  while  the  punches  are 
being  withdrawn  by  the  bar  s,  which  rises  simultaneously  with  the  depressor  T,  during  one-half  of  its 
ascent. 

Whilst  the  depressor  is  continuing  its  assent  and  descent  through  the  other  half  of  the  stroke,  the 
roller  /'recedes,  and  draws  with  it  the  bar  in,  which  brings  all  the  selectors  again  over  the  punch-rams 
P.  The  roller  f while  receding,  having  performed  another  sixth  of  a revolution,  will,  on  advancing, 
bring  another  of  the  jacquard-plates  against  the  selectors,  and  the  operation  will  be  repeated  until  all 
the  holes  are  punched  in  the  plate  under  operation. 

JAPANNING.  The  art  of  covering  paper,  wood,  or  metal  with  a thick  coat  of  a hard,  brilliant 
varnish : it  originated  in  Japan,  whence  articles  so  prepared  were  first  brought  to  Europe.  The  material, 
if  of  wood  or  papier-machee,  is  first  sized,  polished,  and  varnished ; it  is  then  colored  or  painted  in 
various  devices,  and  afteiwards  covered  with  a highly  transparent  varnish,  or  lacquer,  which  is  ulti- 
mately dried  at  a high  temperature,  and  carefully  polished. 

An  improved  method  of  performing  the  above-mentioned  operation  is  thus  described  by  the  inventor : 

The  articles  which  are  to  be  so  coated,  or  covered,  or  ornamented,  may  be  made  of  wrought-iron,  or 
of  other  malleable  metal  or  metals,  which  will  withstand  a strong  red-heat  without  injury,  such  as  brass 
or  copper,  the  making  of  such  articles  being  performed  by  any  of  the  usual  modes  of  cutting  out  of 
laminated  or  sheet  metal,  and  hammering,  or  stamping,  or  otherwise  forming  to  the  required  shape  for 
any  intended  article,  by  aid  of  all  or  any  of  the  various  modes  of  cutting  out  of  laminated  sheet  metal 
practised  by  the  makers  of  articles  of  malleable  metals,  except  that  the  more  fusible  metals  which  will 
not  withstand  a strong  red-heat,  such  as  tin,  lead,  zinc,  pewter,  or  Britannia  metal,  are  not  fit  to  be  used 
for  making  such  articles  or  any  part  thereof,  and,  therefore,  tinning  and  soldering  with  soft  solder  is  not 
applicable  for  taking  such  coating,  or  for  uniting  together  the  parts  of  the  said  articles ; but  in  case  of 
an  article  which  cannot  conveniently  be  formed  of  one  piece  of  metal,  (and  which  is  to  be  preferred,) 
then  the  several  pieces  or  parts  must  be  united  or  strengthened  by  all  or  any  of  the  well-known 
methods  of  overlapping,  turning  down  the  edges,  wiring,  creasing,  and  hammering  down,  or  by  riveting 
or  dove-tailing,  as  may  be  most  suitable  for  the  article ; and  in  case  of  soldering  being  resorted  to,  it 
must  be  hard  soldering  with  brass  or  spelter,  usually  termed  brazing,  and  by  any  or  all  the  means 
aforesaid  the  articles  are  to  be  made  of  wrought-iron,  or  of  other  malleable  metal  or  metals,  and  in  the 
same  manner  as  if  they  were  intended  to  be  japanned,  painted,  varnished,  lacquered,  or  tinned.  When 


JAPANNING. 


143 


made,  the  articles  are  to  be  subjected  to  a full  red-heat,  by  placing  them  in  an  annealing  oven  or  fur 
nace,  -which  may  be  of  the  same  kind  as  is  commonly  used  for  annealing  articles  of  stamped  metal,  ot 
for  annealing  metal  for  being  stamped ; a number  of  articles  of  the  same  shape  and  size  being  piled  up 
one  upon  another  in  such  furnace  in  order  that  they  may  the  better  keep  their  fcrm,  and  sand  may  be 
interposed  between  the  articles  so  piled  up  for  that  purpose.  Small  articles  may  be  heated  in  a muffle, 
such  as  hereafter  described,  into  which  flame  does  not  enter,  and  after  having  been  kept  to  a full  red- 
heat  for  about  half  an  hour,  the  articles  are  either  withdrawn  from  the  oven  or  furnace  and  allowed  to 
cool,  or  else  the  oven,  or  furnace,  or  muffle,  with  the  articles  therein,  may  be  allowed  to  cool,  and  the 
articles  removed.  By  the  said  heating,  all  liquid  or  greasy  matter  will  have  been  dissipated,  and  the 
surfaces  of  the  articles  will  have  been  oxidated,  and  then  all  oxide  or  scale  is  to  be  removed  from  the 
surfaces  of  the  articles  by  rubbing  them  with  sandstone,  for  the  plain  and  accessible  parts,  and  with 
worn-out  tiles,  scrapers,  or  other  suitable  tools,  for  the  less  accessible  places.  Or  articles  of  such  a 
truly  circular  or  elliptical  form  as  to  admit  of  being  turned  in  a lathe,  may  be  mounted  in  a chuck 
and  turned  ; a broad  flat  tool  being  presented  to  every  part  of  the  revolving  surface  in  succession, 
leaving  the  surface  of  the  metal  smooth  and  even,  without  the  necessity  of  its  being  quite  bright  or 
polished.  The  articles  being  thus  rendered  perfectly  clean,  are  ready  to  receive  the  first  coat  or  covering 
of  partially  vitrifiable  material,  (the  composition  whereof  is  hereafter  described,)  and  which  is  applied 
to  the  surface  of  the  articles  in  a semi-liquid  state,  which  state  results  from  the  materials  having  been 
ground  very  fine  when  in  mixture  with  water,  and  to  the  consistence  of  a thick  cream,  and  then  strained 
through  fine  lawn.  A suitable  quantity  of  such  semi-liquid  is  poured  out  from  a ladle  or  spoon  upon 
the  surface  of  the  article  whilst  it  is  held  over  a large  vessel  containing  such  semi-liquid,  and  by  holding 
the  article  in  the  hands  with  the  surface  inclined,  the  semi-liquid  runs  slowly  and  gradually  along  the 
surface,  so  as  to  spread  itself  out  and  cover  the  same,  the  article  being  turned  about  and  inclined  in 
different  directions  in  succession,  in  order  to  cause  the  semi-liquid  to  run  over  the  surface  until  the 
whole  is  completely  covered  and  with  a coating  of  uniform  thickness,  all  surplus  of  such  semi-liquid 
being  allowed  to  drain  off  therefrom  into  the  basin  or  other  vessel  beneath.  Great  care  must  be  taken, 
however,  to  avoid  air-bubbles,  specks,  or  defective  places  in  the  coating,  and  which  is  only  accomplished 
by  using  precaution  in  the  previous  preparation  of  the  semi-liquid,  or  by  thoroughly  grinding  or  straining 
it,  in  order  to  keep  it  free  from  lumps  and  from  any  coarse  particles,  and  afterwards  avoiding  all  violent 
stirring  or  splashing,  so  as  by  no  means  to  get  air  intermixed  with  it,  but  using  only  a gentle  motion 
when  taking  it  up  with  a ladle  or  spoon ; and  such  a quantity  only  of  the  semi-liquid  at  one  time  as  is 
not  materially  greater  than  sufficient  for  covering  the  surface  of  the  article  to  be  coated.  The  operation 
of  coating  will  be  greatly  facilitated  by  performing  the  same  in  a warm  room,  and  by  making  the  article 
rather  warmer  than  the  semi-liquid  itself,  but  not  so  as  to  feel  hot  to  the  hand;  and  such  warmth  of  the 
room  and  of  the  article  will  dispose  the  covering,  after  it  has  been  spread  over  the  surface  of  the  article 
as  aforesaid,  to  begin  to  dry  upon  that  surface,  and,  in  a short  time,  so  far  as  not  to  run  or  move  thereon, 
after  which  the  drying  is  to  be  completed  by  placing  the  article  in  an  ordinary  japanner’s  stove,  which 
should  be  kept  heated  to  a temperature  of  about  180°  Fahrenheit,  the  article  being  left  therein  until  all 
moisture  is  gradually  dried  away,  or  so  as  to  leave  a dry  whitish  covering,  which  adheres  sufficiently  to 
the  surface  of  the  article  for  keeping  its  place  thereon,  but  which  would,  nevertheless,  be  easily  rubbed 
off  if  handled  roughly,  or  if  only  touched  rudely  by  the  fingers.  The  composition  of  materials  found 
to  be  the  most  suitable  for  the  first  coating  may  be  prepared  as  follows : — 

Take  six  parts  (by  weight)  of  flint-glass, -broken  into  small  fragments,  three  parts  of  the  ordinary 
borax  of  commerce,  one  part  of  red-lead,  and  one  part  of  oxide  of  tin.  These  four  ingredients  being 
brought  into  the  state  of  a coarse  powder,  are  to  be  well  mixed  together,  by  pounding  them  in  an  iron 
mortar,  and  then  the  mixture  is  to  be  fritted  in  the  same  manner  as  is  usually  done  with  the  materials 
for  making  glass,  or  by  subjecting  such  mixture  to  a strong  red-heat  in  a reverberatory  furnace  for  three 
or  four  hours  or  more,  it  being  frequently  stirred  and  turned  over  to  expose  every  part  to  the  flame,  and 
to  more  effectually  mix  the  ingredients,  as  well  as  to  expel  all  volatile  matter ; and  towards  the  latter 
part  of  the  time  the  heat  must  be  increased,  until  a partial  melting  or  semi-vitrification  has  commenced, 
when  the  whole  is  to  be  withdrawn  from  the  furnace  in  a pasty  state,  and  let  fall  into  water  in  order  to 
be  suddenly  cooled,  whereby  it  becomes  cracked,  so  as  to  be  afterwards  easily  broken  into  small  frag- 
ments, or  into  a coarse  description  of  powder,  which  is  called  fritt,  and  which  is  for  the  first  body  or 
coat,  but  which  fritt  is  only  one  of  the  ingredients  in  the  composition  of  such  first  coat.  With  one  part 
(by  weight)  of  the  fritt  described  is  to  be  mixed  two  parts  of  calcined  bone,  ground  to  powder;  and  the 
mixture  of  fritt  and  bone  is  then  to  be  ground  with  water  in  a mill,  called  a porcelain-mill,  such  as  is 
used  for  grinding  the  materials  for  making  porcelain ; and  which  operates  by  trituration  of  the  materials 
with  water  between  chert-stones,  or  other  hard  silicious  stones,  whereof  some  are  fixed  at  the  bottom  of 
a tub  or  vessel  containing  water,  having  the  materials  mixed  therewith  ; and  other  such  stones  rest  by 
their  own  weight  upon  the  said  fixed  stones,  and  are  carried  round  thereon  with  a circular  motion,  com- 
municated by  the  moving  part  of  the  mill,  so  as  to  rub  over  the  fixed  stones  and  grind  the  materials 
between  them,  which  operation  is  continued  until  the  materials  are  reduced  to  a state  of  extremely 
minute  division  in  the  water,  forming  therewith  the  semi-liquid  (of  about  the  consistence  of  cream) 
already  alluded  to,  and  which  is  ready  for  use  so  soon  as  it  has  been  passed  through  appropriate  sieves, 
so  as  to  effectually  separate  any  particles  that  have  escaped  the  operation  of  grinding. 

In  articles  requiring  only  one  side  to  be  coated,  such  as  the  hollow  side  of  a kettle,  or  pot,  or  jug,  or 
such  as  a mug,  or  plate,  or  dish,  or  waiter,  or  tray,  or  basin,  or  cup,  or  bread-basket,  or  cheese-tray,  (to 
all  which,  as  well  as  to  numerous  similar  articles,  this  invention  is  considered  as  being  particularly  ap- 
plicable,) such  hollow  side  may  be  first  coated  with  vitrified  materials  after  the  manner  already 
explained ; after  which,  the  outside  may  be  coated  or  covered  by  any  of  the  ordinary  methods  of 
japanning ; and  in  applying  such  first  coating  of  semi-liquid  to  the  hollow  surface  or  side  of  such  articles 
as  those  stated,  it  is  observed  that,  instead  of  pouring  out  a auantity  thereon,  as  in  other  cases,  the 
vessel  may  be  filled,  or  if  both  sides  have  to  be  coated,  may  be  wholly  immersed,  and  in  the  act  of 


144 


JAPANNING. 


draining  off  the  surplus  the  fingers  of  the  two  hands  should  be  applied  to  the  edges  only  cf  the  article, 
and  at  the  two  opposite  sides  of  its  circumference,  so  that  the  weight  of  such  article  will  balance  itself 
and  render  it  easy  to  turn  it  over  and  about,  so  as  to  drain  in  succession  from  either  side,  extreme  care 
being  requisite  in  all  such  cases  to  insure  a uniformity  of  surface.  When  the  coating  is  so  far  dried  that 
it  will  not  run,  the  article  is  to  be  laid  down  upon  the  points  of  three  small  supports,  made  of  burnt 
earthenware,  and  which  are  made  to  stand  upon  a small  iron  plate  that  serves  to  carry  away  the  article 
which  is  next  introduced  into  the  japanner’s  stove,  where  it  is  dried  more  effectually.  When  the  article 
is  afterwards  removed  from  the  said  stove,  in  order  to  be  introduced  into  the  muffle  for  the  firing  or 
burning  in  of  the  coating,  (and  in  the  manner  hereafter  described,)  it  is  still  to  be  borne  upon  the  same 
three  supports,  the  iron  plate  on  which  they  rest  being  removed  from  the  stove,  and  also  introduced 
into  the  mufHe,  or  with  the  three  supports  and  the  article  upon  it ; and  in  case  of  any  specks  or  deficient 
places  appearing  in  the  coating,  such  places  may  be  mended  by  applying  a portion  of  the  semi-liquid 
thereto  by  aid  of  a brush,  and  in  the  manner  of  painting  or  pencilling,  and  then  returning  the  article  to 
the  stove,  and  drying  the  same,  so  that  every  part  shall  not  only  be  completely  covered,  but  also  effect- 
ually dried  on,  and  before  it  goes  into  the  muffle,  the  ultimate  appearance  of  the  article  depending  very 
materially  upon  the  manner  of  conducting  this  first  part  of  the  process,  and  upon  the  care  with  which 
the  coating  has  been  applied,  and,  upon  the  proper  grinding  and  mixing  of  the  materials,  uniformity  o( 
surface  in  the  first  process  being  considered  absolutely  indispensable,  in  order  to  insure  the  successful 
result  of  such  after-processes  as  have  yet  to  be  detailed.  The  firing  next  described  is  for  the  purpose 
of  so  far  vitrifying  the  materials  and  hardening  the  coating  as  to  fasten  it  on  to  the  surface  of  the 
articles,  and  is  performed  in  a furnace,  of  the  kind  used  by  painters  in  enamel,  being  an  oven  strongly 
heated  by  fire  applied  beneath  it,  and  by  the  flame  therefrom  passing  in  flues  around  it,  and  may  be 
called  a muffle ; but  no  fire,  or  flame,  or  smoke  can  enter  into  the  interior  where  the  articles  are  placed. 
The  articles  are  left  in  the  muffle,  and  subjected  to  the  heat  until  such  time  as  the  earthy  composition 
will  have  undergone  so  much  of  the  commencement  of  fusion  or  partial  vitrification  as  to  render  the 
particles  of  the  coating  firmly  adherent  one  to  the  other,  and  also  to  the  surface  of  the  metal  articles, 
and  which  are  then  to  be  withdrawn  and  laid  on  a flat  iron  bench  to  cool.  When  cold,  such  parts  of 
the  surface  as  have  been  coated  will  be  found  to  present  the  dead  whitish  appearance  of  earthenware, 
which  has  been  once  fired  only,  but  has  not  been  glazed,  being  in  that  state  which  by  potters  is  termed 
“ biscuit.”  The  time  that  the  articles  should  remain  in  the  heated  muffle  will  vary  from  a few  minutes 
to  half  an  hour,  depending  upon  the  size  and  number  of  the  articles,  and  upon  the  heat  of  the  muffle ; 
neither  can  such  time  be  stated  with  precision,  but  the  operator,  it  is  observed,  will  soon  find  out  what 
length  of  time  is  most  suitable  for  any  particular  description  of  article,  and  also  what  heat  should  be 
kept  up  in  order  to  obtain  the  required  result,  by  observing,  so  soon  as  the  article  shall  have  become 
cool,  whether  the  coating  has  been  rendered  sufficiently  hard,  and  has  or  has  not  become  firmly  ad- 
herent. When  cool,  the  newly  formed  coating  is  to  be  wetted,  either  by  passing  over  it  a sponge  that 
has  been  dipped  in  water,  or  else  by  dipping  the  article  itself,  and  a second  coating  is  then  applied  over 
the  first  coat  and  dried  thereon  in  the  japanner’s  stove,  and  then  fired  in  the  muffle  in  the  same  manner 
as  the  first,  only  the  composition  is  to  be  different;  and  the  patentee  goes  on  to  state  that  the  compo- 
sition he  lias  found  to  be  the  most  suitable  for  such  second  coating  is  as  follows : Take  32  parts  (by 
weight)  of  calcined  bone,  ground  to  a fine  powder,  16  parts  of  china-clay,  and  14  parts  of  Cornwall 
stone  in  fine  powder,  and  8 parts  of  carbonate  of  potash ; the  latter  being  dissolved  in  water,  the  other 
ingredients  are  mixed  up  therewith,  so  as  to  make  a thick  paste,  which  is  then  fritted  for  two  or  three 
hours  in  a reverberatory  furnace,  until  it  assumes  the  appearance  of  biscuit-china,  which  is  to  be  reduced 
to  powder;  then -5^- parts  (by  weight)  of  such  powder  are  to  be  mixed  with  16  parts  of  flint-glass 
broken  small,  5-J-  parts  of  calcined  bone  ground,  and  3 parts  of  calcined  flint  ground,  the  said  mixture 
being  afterwards  ground  with  water  in  a porcelain-mill  until  it  is  reduced  to  a semi-liquid  state  about 
the  consistence  of  cream,  and  which  has  to  be  carefully  strained,  as  before,  through  sieves  of  lawn,  when 
it  will  be  ready  for  use  in  the  same  manner  as  already  explained  in  reference  to  the  composition  or 
semi-liquid  employed  for  the  first  coating.  In  firing  the  second  coating  care  must  be  taken  that  the 
articles  are  kept  long  enough  in  the  muffle,  and  that  the  heat  is  sufficient  for  thoroughly  incorporating 
the  second  coat  with  the  first,  also  for  thoroughly  hardening  both  coats.  After  firing  for  the  second 
coat,  the  article,  when  cool,  will  have  a stronger  and  whiter  color,  and  a more  decided  resemblance  to 
articles  of  good  earthenware,  but  still  only  in  the  state  called  “ biscuit,” 

The  articles  having  been  twice  coated  with  composition  as  described,  and  twice  fired,  so  as  to  assume 
at  this  stage  the  external  appearance  of  a good  earthenware  biscuit,  the  patentee  further  states,  that 
should  it  be  desired  to  produce  a very  white  color,  so  as  to  resemble  the  very  finest  earthenware  or 
porcelain,  then  in  lieu  of  the  16  pounds  of  flint-glass,  mentioned  as  forming  part  of  the  last  composition, 
proper  for  the  second  coating,  he  prefers  to  substitute  a like  quantity  of  the  composition  prepared  as 
follows:  Take  four  parts  (by  weight)  of  feldspar  in  powder,  four  parts  of  white  sand,  four  parts  of  car- 
bonate of  potash,  one  part  of  arsenic,  six  parts  of  borax,  one  part  of  oxide  of  tin,  one  part  of  nitre,  and 
one  part  of  whitir.g;  the  mixture  of  these  materials  is  to  be  fritted  either  in  a reverberatory  furnaca 
(as  was  before  described  for  the  materials  of  the  first  coating,)  or  otherwise  such  fritting  may  be  pc? 
formed  in  a crucible  strongly  heated  in  a furnace,  the  heat  in  either  case  being  continued  until  tire 
materials  are  partially  fused,  and  the  appearance  when  cold  will  be  that  of  a whitish  enamel,  which 
being  reduced  to  powder,  such  powder  is  to  be  substituted,  weight  for  weight,  in  place  of  the  16  pounds 
or  parts  of  flint-glass  formerly  mentioned  as  part  of  the  composition  of  materials  for  the  second  coating, 
all  the  other  materials  remaining  the  same.  Excepting  only  for  the  purpose  of  obtaining  whiteness  of 
color,  the  flint-glass  is  in  other  respects  described  as  being  cheaper,  and  yet  equally  good.  After  the 
articles  have  received  the  second  coating,  (of  either  of  the  compositions  described,)  and  have  been  fired 
and  then  cooled,  they  are  to  be  wetted  with  a sponge,  or  by  dipping  them  into  water,  as  was  done  after 
the  first  coating,  and  are  then  ready  for  receiving  the  third  coat  or  glaze,  which  is  also  applied  in  a 
semi-liquid  state,  great  care  being  required  in  draining  off  the  surplus  semi-liquid  glaze,  so  as  to  leave 


JOINT,  CLASP-COUPLING. 


145 


only  a thin  coating  or  covering,  equally  distributed  over  every  part  of  the  second  coating  of  partially 
vitrified  material,  in  order  that  the  article,  after  being  again  exposed  to  the  heat  of  the  muffle,  and 
afterwards  withdrawn,  may  present  the  appearance  of  glazed  earthenware  of  good  quality,  and  which 
will  not  otherwise  be  the  case ; whereas,  with  appropriate  care,  and  when  the  composition  specially 
adapted  for  producing  whiteness  has  been  employed,  it  will  resemble  earthenware,  it  is  stated,  of  the 
very  best  quality.  The  composition  found  to  be  the  most  suitable  for  the  third  coat,  or  glaze,  is  as 
follows:  Take  twelve  parts  (by  weight)  of  feldspar,  in  powder,  four  and  a half  parts  of  china-clay, 
eighteen  parts  of  borax,  three  parts  of  nitre,  one  and  a half  parts  of  carbonate  of  potash,  and  one  and  a 
half  parts  of  oxide  of  tin,  which  materials  being  well  mixed  together,  the  mixture  is  to  be  fritted  either 
in  a crucible  or  in  a reverberatory  furnace,  and  then  the  frit  being  reduced  to  powder,  is  to  be  ground 
with  water  in  a porcelain-mill  to  a semi-liquid  state,  and  strained  through  fine  lawn  in  the  same  manner 
as  described  for  preparing  the  composition  for  the  first  coat.  Or,  instead  of  the  above  composition,  the 
following  may  be  adopted  for  such  third  coat  or  glaze : Take  nine  parts  (by  weight)  of  feldspar,  in 
powder,  two  parts  of  china-clay,  nine  parts  of  borax,  two  parts  of  nitre,  three  parts  of  carbonate  of  soda, 
and  one-quarter  part  of  arsenic ; which  materials  being  mixed  together  the  mixture  is  to  be  fritted,  and 
then  reduced  to  powder,  ground  in  water,  and  strained  as  aforesaid.  In  firing  the  articles  in  the  muffle 
for  the  third  coat  or  glaze,  the  heat  of  the  muffle,  and  the  time  the  articles  are  subjected  to  such  heat, 
must  be  sufficient  to  cause  the  glaze  to  become  thoroughly  vitrified,  and  to  spread  over  the  surface  of 
the  second  coat  so  as  to  become  incorporated  with  that  coat,  and  effectually  glaze  the  surface  thereof, 
as  in  earthenware  of  excellent  quality;  and  in  case  there  are  any  imperfections  in  the  glaze  after  it  has 
been  so  fired,  then,  after  the  articles  are  cold,  another  coating  of  the  same  glaze  may  be  applied  in  a 
semi-liquid  state  and  dried  in  the  japanner’s  stove,  and  then  fired  in  the  muffle  as  was  done  for  the  first 
coating  of  glaze  ; and  so  in  like  manner  a third  coating  or  glaze  may  be  applied  and  fired,  if  found 
requisite. 

JOINT,  CLASP-COUPLINQ— West  & Thompson’s. 
are  two  flanges  joined  each  to  one  of  the  pieces  of 
pipe.  It  will  be  observed  that  the  coupling  parts  of 
these  flanges  are  bevelled,  and  have  no  bolt-holes,  as 
those  in  common  use  all  have.  C is  a piece  of  vulcan- 
ized India-rubber,  or  any  other  packing  that  may  be 
thought  necessary,  although  a pressure  can  be  exerted 
in  bringing  the  flanges  so  close  together  that  the  joint 
is  made  perfectly  tight  without  any  packing,  but  we 
think  that  it  is  all  the  better  to  use  a little  packing. 

B B is  the  clasp.  This  is  divided  into  two  parts,  and 
this  part  is  represented  with  the  flange  resting  on  it.  | 

By  placing  the  concave  part  over  the  bevel  of  the 
flanges,  and  securing  the  two  parts  of  the  clasp  to- 
gether by  bolts  passing  through  E E,  is  all  the  opera- 
tion that  is  required  in  connecting  two  separate  pieces 
of  pipe  together.  Every  mechanic  will  perceive  that 
the  tighter  the  clasp  is  screwed  up,  the  faces  of  the 
flanges  are  brought  closer  together,  and  the  joint  is 
thereby  made  exceedingly  tight.  Experience  has  pro- 
ven this  joint  to  be  excellent  for  pipes  that  are  used 
for  conducting  steam. 

It  will  be  clearly  seen  that  this  improved  coupling  is  applicable  to  vessels  and  other  articles  of 
angular  or  curved  forms,  and  that  whatever  may  be  the  form,  any  desired  and  effective  mode  of  draw- 
ing or  forcing  together  the  segments  of  the  ground  clamp  may  be  substituted  for  screw-bolts  or  the 
conical  rings. 


DD,  Fig.  2431,  are  two  pieces  of  pipe;  A A 


In  coupling  angular  vessels,  or  other  articles,  it  will  be  found  to  be  advantageous  to  make  the  grooved 
clamp  in  as  many  sections  as  there  are  sides  to  the  figure,  and  for  round  couplings  it  will  be  found  suffi- 
cient to  make  it  in  two  parts  for  all  articles  of  moderate  size ; but  when  the  diameter  is  very  considerable 
it  may  be  divided  into  three  or  more  parts. 

This  improved  mode  of  coupling  is  equally  applicable  to  the  securing  of  nozzles,  stop-cocks,  bonnets, 
and  many  other  articles  not  necessary  to  enumerate,  and  particularly  to  cylinder-heads,  in  which  the 
edge  of  the  head  takes  the  place  of  one  of  the  flanges. 

It  will  be  evident  to  any  engineer  or  machinist,  from  the  foregoing,  that  shafts  and  other  solid  bodies 
can  be  coupled  together  in  the  same  manner  as  hollow  conduits  or  vessels,  and  with  equal  advantage, 
and  by  a similar  arrangement  of  parts,  and  therefore  it  is  deemed  unnecessary  to  give  an  example. 

The  flanges,  instead  of  solid  projections  of  the  bodies  to  be  united,  may  be  made  separate,  and 
connected  therewith  in  any  manner  desired,  as  the  mode  of  making  the  flanges  forms  no  part  of  the 
invention.  1 

The  leading  advantages  of  this  mode  of  coupling  over  the  ordinary  double  flange  and  bolts  heretofore 
and  now  generally  used,  are,  a great  reduction  in  the  number  of  screw-bolts  used,  which  occupy  much 
time  in  connecting  and  disconnecting  joints,  particularly  in  the  parts  of  steam-engines,  such  as  cylinder- 
heads,  and  other  parts,  which  require  to  be  frequently  connected  and  disconnected  for  packing  and  other 
purposes,  and  increased  strength  and  more  perfect  and  continuous  support,  as  the  flanges  by  the  im- 
proved plan,  instead  of  being  reduced  in  strength  by  the  numerous  bolt-holes,  are  pressed  together  aud 
supported  all  round  by  the  grooved  segmental  clamp,  and  the  strain  on  the  threads  of  the  screw-bolts, 
instead  of  being  in  the  line  of  the  force  which  tends  to  separate  the  coupling,  as  in  the  old  plan,  is  nearly 
at  a right  angle  therewith,  and  therefore  greatly  relieved.  There  are  other  advantages  which,  however 
it  will  be  unnecessary  to  enumerate. 

Vol.  II. — 10 


146 


JOINTS,  AND  JOINING  TIMBERS. 


JOINT,  PATENT  EXPANSION.  Figs.  2432  and  2433  represent  a patent  expansion-joint,  patented 
by  Z.  R.  Dunham,  of  New  York,  March  20,  1847. 

2433. 


JOINTS,  AND  JOINING  TIMBERS.  As  timber  cannot  always  be  obtained  of  sufficient  length 
for  tie-beams,  or  bridges,  it  is  necessary  to  unite  two  or  more  pieces  together  by  their  ends,  which  is 
called  scarfing,  and  is  differently  performed  by  carpenters.  The  most  common  means  is  lapping,  or 
halving,  or,  as  it  is  sometimes  called,  ship-lapping.  This  is  nothing  more  than 
cutting  away  a part  of  the  thickness  of  one  piece,  and  an  equal  quantity  of  the  , 
other  which  is  to  be  joined  to  it,  so  as  to  suffer  the  diminished  end  of  one  piece  j 
to  overlap  that  of  the  other,  (as  in  Fig.  2434,)  and  then  uniting  them  by  nails  L 
or  wooden  pins,  which  are  called  tree-nails.  This  method  is  applied  to  plates, 
bond  timbers,  and  others,  where  there  is  not  much  longitudinal  compression  or  extension ; where  this 
kind  of  effect  is  to  be  provided  for,  the  upper  as  well  as  the  lower  timbers  should  be  cut  and  let  into 
each  other ; the  under  piece  having  a tenon  formed  at  its  extreme  end,  with  a corresponding  cutting  to 
receive  it  in  the  upper  piece.  That  these  tenons  may  be  enabled  to  pass  each  other,  it  is  necessary  to 
cut  away  a part  of  the  timbers  in  the  middle  of  the  length  of  the  joint,  equal  to  the  length  of  the  two 
tenons,  so  as  to  form  a square  hole,  through  the  middle  of  the  timbers  to  be  joined  together,  and  this  is 
afterwards  closed  up  by  driving  an  oak  key  into  it ; this  also  helps  to  drive  the  tenons  to  their  respect 
ive  mortises,  and  prevents  the  timbers  from  being  pulled  asunder.  The  thickness  of  the  key,  in  ordei 
that  it  may  not  be  compressed,  should  be  equal  to  a third  of  that  of  the  piece  into  which  it  is  inserted 
Another  principle  is  here  shown,  which  is  more  simple,  the  joint  being  cut  obliquely ; to  make  these 
two  pieces  stiff,  the  ends  of  both  should  be  cut  in  an  angular  form.  To  strengthen  these  scarfs,  iron 
straps  and  screw-bolts  are  added ; but  no  joining  can  be  made  so  strong  as  the  timber  itself. 

In  making  joints,  it  must  be  remembered  that  all  timber  is  liable  to  shrink  when  dry,  and  when  wet 
to  expand ; on  this  account,  dovetail  joints  should  be  avoided  as  much  as  possible,  as  they  are  liable  to 
draw  out ; and  all  joints  should  be  made  with  reference  to  their  contraction  and  expansion,  which  some- 
times tends  to  split  off  portions  of  the  framing.  Where  iron  bolts  or  straps  are  introduced,  care  must 
be  taken  that  their  effect  is  not  lost  by  the  changes  that  the  timber  undergoes.  The  areas  of  the  for- 
mer should  never  be  less  than  two-tenths  of  the  area  of  the  section  of  the  beam ; it  must  also  be  recol- 
lected in  making  a joint,  that  when  force  is  applied  to  any  portion,  the  fibres  of  the  timber  will  slide 
upon  each  other. 

Fishing  a beam  is  merely  placing  a piece  of  the  same  scantling  to  one  side  of  the  timber  to  be  united, 
and  bolting  them  or  hooping  them  together.  Separate  pieces  of  timber  are  united  either  by  scarfing, 
Botching,  cogging,  pinning,  wedging,  tenoning,  Ac. 

Scarfing  consists  in  cutting  away  equally  from  the  ends,  but  on  the  opposite  sides,  of  two  pieces  of 


2434. 

BZH 


JOINTS,  AND  JOINING  TIMBERS. 


147 


timber  for  the  purpose  of  connecting  them  lengthwise.  The  usual  method  of  scarfing  bond  and  wall 
plates  is  by  cutting  about  three-fifths  through  each  piece,  on  the  upper  face  of  the  one  and  the  under 
face  of  the  other,  about  6 or  8 inches  from  the  end  transversely,  making  what  is  termed  a kerf;  and 
longitudinally  from' the  end,  from  two-fifths  down,  on  the  same  side,  so  that  the  pieces  lap  together  like 
a half  dovetail.  Fig.  2435  is  a scarf. 


Notching  is  either  square  or  dovetailed,  and  is  made  use  of  for  connecting  the  ends  of  wall-plates  and 
bond-timbers  at  the  angles,  in  letting  joists  down  on  girders,  binders,  purlins,  or  principal  rafters. 

Cogging,  or  cocking,  is  a species  of  notch  extending  on  one  side,  and  having  a narrow  cog  alone  in 
the  bearing  piece,  flush  with  its  upper  face.  It  is  principally  made  use  of  in  tailing  joists  on  wall- 
plates. 

Pinning  consists  in  inserting  cylindrical  pieces  of  wood  or  iron  through  a tenon. 

Wedging  is  the  insertion  of  triangular  prisms,  whose  converging  sides  are  under  an  extremely  acute 
angle,  into  or  by  the  end  of  a tenon,  to  make  it  fill  the  mortise  so  completely  as  to  prevent  its  being 
withdrawn. 

Tenon  and  mortise  of  the  most  simple  kind  is  shown  in  Fig.  2439,  in  which  the  two  timbers  united 
are  at  right  angles  with  each  other.  The  tenon  is  on  that  which  appears  horizontal,  while  the  mortise 
is  cut  in  the  upright  timber.  The  tenon  is  left  one-third  of  the  thickness  of  the  timber,  as  shown  in  the 
upper  part  of  the  figure. 

The  greatest  strain  upon  the  fibres  of  a girder  is  at  the  upper  and  lower  parts,  decreasing  gradually 
towards  the  middle  of  the  depth,  which  is  the  best  situation  to  make  the  mortise.  The  form  to  be  given 
to  the  tenon  requires  consideration.  Some  carpenters  introduce  it  at  the  lowest  part  of  the  girder, 
which  in  a great  degree  destroys  its  stiffness  : being  a sixth  of  the  depth,  it  should  be  placed  at  one- 
third  of  the  depth  from  the  lowest  side.  Horizontal  timbers,  intended  to  bear  great  weights,  should  be 
always  notched  on  their  supports,  in  preference  to  being  framed  in  between  them ; and  this  rule  is 
applicable  to  inclined  timbers,  as  common  rafters  and  braces.  All  the  pressures  to  which  they  are 
subjected  should  be  brought  to  act  in  the  direction  of  their  lengths,  and  the  form  of  the  joint  should  be 
such  as  to  convey  the  pressure  as  much  as  possible  into  the  axes  of  the  timber.  When  subjected  to  a 
strain,  a partial  bearing  is  liable  to  very  serious  disadvantages,  particularly  in  bridges. 

2441. 


"LT 

I 


2439.  2440. 


Where  the  mortise  is  to  be  made  in  the  upright  timber,  and  the  tenon  to  be  cut  on  another  inclined, 
as  in  a brace  to  a partition,  a bevelled  shoulder,  Fig.  2441,  is  cut  on  the  inclined  piece,  and  a sinking 
made  in  the  upright  post  to  receive  it — the  pin  which  secures  it  in  its  mortise  passing  through  the 
tenon. 

The  bevelled  shoulder  adds  greatly  to  the  strength  of  a mortise  and  tenon  joint,  and  should  never  be 
dispensed  with  : it  renders  the  junction  of  the  two  pieces  of  timber  more  exact,  and  makes  the  abut- 
ments of  all  the  fibres  stronger  and  more  capable  of  resistance. 

The  common  method  of  effecting  such  a junction  does  not  occupy  so  much  time  or  labor,  but  is  not 
so  effective  : it  is  usual  to  drive  one  or  two  wooden  pins  through  holes  bored  for  the  purpose  at  right 
angles  through  the  timber  in  which  the  mortise  is  made,  as  well  as  through  that  which  has  the  tenon. 

Boring  the  hole  for  the  pin  requires  to  be  nicely  performed,  in  order  that  it  may  draw  the  tenon  tight 
into  the  mortise  prepared  to  receive  it,  and  make  the  shoulder-butt  close  into  the  joint,  without  running 
the  risk  of  tearing  out  a portion  of  the  tenon  beyond  the  pin.  Square  holes  and  square  pins  are  pre- 
ferred to  round,  as  they  bring  more  of  the  wood  into  action,  and  there  is  less  liability  to  split. 

Foxtail  wedging,  adopted  by  ship-carpenters,  is  made  with  long  wooden  bolts,  which  do  not  pass 
completely  through  the  timbers,  but  take  a very  fast  hold  : they  are  subject  to  be  crippled  in  drawing 
if  they  are  too  nicely  fitted : this  is  remedied  by  placing  a thin  wedge  into  the  hole  previous  to  the 


148 


JOINTS,  AND  JOINING  TIMBERS. 


insertion  of  the  wooden  bolt,  which,  when  driven,  is  split  by  the  wedge,  and  thus  squeezed  tight  to  the 
sides  of  the  hole. 

Bond-timbers  and  wall-plates  require  to  be  carefully  notched  together  at  every  angle  and  return,  and 
scarfed  at  every  longitudinal  joint. 


2443. 


To  make  a good  tie-joint  requires  great  attention  on  the  part  of  the  carpenter ; and,  for  uniting  wall- 
plates,  the.  dovetail  joint,  Fig.  2444,  is  sometimes  adopted.  If  the  effects  that  0444 

shrinking  may  produce  be  taken  into  consideration,  the  more  usual  system  of  1 ’ , 

halving,  Fig.  2443,  is  decidedly  preferable.  Whenever  this  joint  is  employed,  j /(S J 

a stout  pin  of  tough  oak,  or  an  iron  bolt,  should  be  driven  through  to  render  it  ' — I 

secure ; and,  where  there  is  the  slightest  tendency  for  one  piece  to  slide  from  the  other,  iron  straps 
must  he  used. 

Timbers  which  are  laid  upon  the  plates,  and  intended  to  act  as  ties,  should  be  cut  with  a dovetail  and 
let  into  the  timber  it  is  to  secure.  Generally,  where  they  cross  at  right  angles,  halving  or  cutting  away 
the  moiety  of  each  is  adopted,  and  one  is  let  into  the  channel  cut  in  the  other. 

For  joining  two  pieces  of  timber  together,  notching  is  the  most  common  and  simple  method  ; for, 
when  four  angles  are  to  be  formed,  the  surfaces  of  one  piece  are  both  parallel  and  perpendicular  to 
those  of  the  other.  A notch  may  be  cut  out  of  one  piece  (Fig.  2444)  the  breadth  of  the  other,  which 
may  be  let  down  on  the  first ; or  the  two  pieces  may  be  both  notched  to  each  other,  and  then  secured 
by  an  oak  pin  : this  is  the  best  practice  when  each  of  the  timbers  is  equally  exposed  to  a strain  in  any 
direction.  When  one  piece  has  to  support  the  other  transversely,  the  upper  may  have  a notch  cut 
across  it,  to  the  breadth  of  two-thirds  the  thickness  of  the  one  below,  which  must  also  have  a similar 
notch  cut  out  on  each  upper  edge,  leaving  two  thirds  of  the  breadth  of  the  middle  entire,  by  which 
means  the  strength  of  the  supporting  or  lower  piece  is  less  diminished  than  if  a notch  of  less  depth 
were  cut  the  whole  breadth.  Such  joints  are  particularly  adapted  for  purlins,  when  let  down  upon  the 
principal  rafters. 

Lapping  is  performed  in  a variety  of  ways — either  by  simply  halving  the  end  of  each  timber,  or  by 
halving  and  dovetailing,  as  in  Fig.  2445.  I'n  the  latter  case,  the  tim- 
bers act  as  a tie,  and  cannot  be  readily  pulled  asunder. 

In  these  joints  the  greatest  attention  is  required  to  make  the  sev- 
eral parts  abut  completely  on  each  other,  as  the  least  play  or  liability 
to  motion  at  once  destroys  their  efficacy.  The  butting  joints,  being 
slightly  tapered  to  one  side  of  the  beam,  require  very  moderate  blows 
with  a hammer  to  force  them  into  their  place  : if  driven  too  hard,  the 
parts  will  be  liable  to  strain,  and  the  abutments  to  split  off.  It  is  better,  sometimes,  to  leave  the  abut 
ments  open,  and  afterwards  drive  in  a small  wedge,  which,  if  made  of  hard  wood  and  not  likely  to 


compress,  is  an  excellent  substitute.  Iron  has  been  said  to  injure  the  fibres  of  the  timber,  from  its  toe 
great  hardness ; otherwise  it  is  well  adapted  for  the  joggles  and  wedges. 

Two  pieces  of  timber  may  be  united  in  such  a manner  that  they  preserve  the  same  breadth  and 
depth  throughout,  which  is  of  great  importance  in  the  construction  of  beams 
for  bridges  or  roofs  of  considerable  span.  The  length  to  be  given  to  the 
scarf  must  depend  upon  the  force  that  will  cause'  the  fibres  of  the  timber  to 
slide  upon  each  other ; and  that  for  oak,  ash,  or  elm  should  be  six  times 
the  depth  of  the  timber ; in  fir,  twelve  times  : but  where  bolts  are  used  so 
much  is  not  required  in  either  case.  The  simplest  method  for  uniting  the  r 
ends  of  two  timbers  is  by  cutting  away  an  equal  portion  of  each,  and  letting  L 
one  down  upon  the  other.  Fig.  2449. 

Timbers  united  together  by  a number  of  such  cuttings,  afterwards  united  and  bolted  through  or 
hooped  round  with  iron,  aro  capable  of  sustaining  great  resistance : a stirrup-iron  at  each  end 


2449. 


JOINTS,  AND  JOINING  TIMBERS. 


14& 


holds  the  timbers  in  their  places,  and  one  or  more  bolts  are  sufficient  to  prevent  their  being  draws 
asunder. 

The  carpenter  frequently  exercises  great  ingenuity  in  joining  timbers  of  considerable  scantling,  Fig 
2450  ; and,  by  the  introduction  of  iron  or  small  cubes  of  harder 
wood  into  the  joints,  can  prevent  their  being  thrust  or  drawn 
out  of  their  position  either  longitudinally  or  laterally. 

The  scarfing  of  girders  and  beams  have  a great  variety  of 
forms  given  them,  and  are  sometimes  bolted  through,  at  others 
strapped  round  with  strong  hoops  of  iron,  Figs.  2449  to  2454. 

Where  bolts  are  dispensed  with,  it  is  perfectly  clear  that  the 
joint  cannot  have  half  the  strength  of  an  entire  piece.  Where 
the  stress  is  longitudinal,  two  irons  put  on  each  side  will  pre- 
vent the  scarf  that  is  merely  indented  from  pulling  asunder  ; but  such  a provision  will  not  maintain 
the  constant  horizontal  position  of  the  timber. 

When  a scarf  is  forced  to  its  bearings  by  the  introduction  of  keys  or  wedges  driven  tight,  they  some- 
times receive  an  additional  strain,  and  it  is  often  found  advisable  to  omit  them,  and  to  bring  the  joint? 


2452. 


to  a bearing  by  some  other  means  before  the  bolts  are  inserted.  When  keys  are  made  use  of,  they 
should  be  of  very  hard  wood,  having  a curled  grain,  which  resists  the  insertion  of  the  fibres  opposed 
to  it. 

To  prevent  lateral  movement  cogging  is  adopted,  in  addition  to  the  ordinary  method,  and  a small 
tenon  or  cog  is  left  upon  a portion  of  the  scarf,  which  enters  into  a notch  prepared  in  the  piece  which  is 
to  eover  it,  as  shown  in  Figs.  2448  to  2452.  Beams  intended  to  resist  cross-strains  require  to  be  lengthened 
more  frequently  than  any  others,  and,  from  the  nature  of  the  strain,  a different  form  of  scarf  must  be 
made  use  of  from  that  which  is  required  for  a strain  in  the  direction  of  its  length.  When  timber  is 
subjected  to  both  strains,  the  cross-strain  is  that  which  demands  the  greatest  attention.  Where  a floor 
is  supported,  the  scarfing  requires  to  be  further  secured  by  iron  bolts,  made  to  pass  through  a longi- 
tudinal piece  laid  to  cover  the  under  side  of  the  joint. 

Bearing-posts,  when  used  to  support  the  floors  of  a magazine  or  warehouse,  are  generally  formed 
exactly  square.  Some  timber  will  support,  while  that  of  another  quality  will  suspend,  the  most ; 
therefore,  in  the  selection  of  story-posts,  we  must  pay  attention  to  these  peculiarities.  Iron,  however, 
is  generally  used  for  these  purposes,  in  consequence  of  its  horizontal  sectional  area  occupying  less  space 
than  timber  of  the  same  strength. 

When  a tie-beam  is  mortised  through  to  receive  a king  or  queen  post,  and  it  is  necessary  to  provide 
for  the  means  of  holding  it  up,  the  tenon  should  not  be  pinned  through,  as  it  is  not  advisabl^to  depend 
entirely  on  the  pins  for  the  support : the  tenon  should  be  cut  like  a half  dovetail,  or  in  a sloping  direc- 
tion on  one  side,  and  left  straight  on  the  other  : the  mortise-hole  should  be  so  cut  that  the  lower  end  can 
juot  pass.  When  it  is  in  its  place,  a wooden  key  or  wedge  is  driven  tightly  on  the  straight  side,  which 
forces  the  tenon  against  one  side  of  the  mortise-hole,  and  prevents  it  effectually  from  being  drawn  out : 
oak  or  iron  may  be  added,  or  an  iron  strap  may  be  applied. 

Tenons  may  be  wedged  at  the  end  ; but  to  do  this  they  must  be  made  long  enough  to  pass  entirely 


2450. 


through  the  mortise : two  saw-cuts  are  then  made  across  it,  and  the  wedges  are  driven  home.  The 
tenon  sometimes  splits,  but  not  sufficiently  to  injure  its  strength.  When  in  machinery  it  is  not  practi- 
cable to  cut  the  mortise  through,  the  fox-tail  wedging  is  adopted  : the  tenon  is  made  to  fit  the  mortise 


150 


JOINTS..  AND  JOINING  TIMBERS. 


exactly,  the  wedges  are  loosely  put  into  the  saw-cuts,  as  before,  and  the  whole  is  driven  to  its  place. 
When  the  wedges  touch  the  bottom  of  the  mortise,  they  cause  it  to  spread,  and  thus  hold  the  tenon 
firmly  in  its  place. 

Dovetailing  in  some  degree  resembles  mortising  and  tenoning,  and  is  more  adapted  to  uniting 
together  the  angles  of  framework.  The  feet  of  the  rafters  require  the  mortise  and  tenon  to  be  care- 
fully made,  and  the  thrust  is  destroyed  to  a certain  extent  to  obtain  greater  strength.  A portion  of 
the  rafter  is  tenoned  into  the  tie-beam,  and  another  small  part  is  let  into  the  upper  part  of  it : both 
rafter  and  tenon  are  cut  at  right  angles  with  the  inclination  of  the  roof.  In  Fig.  2455,  the  rafter  has 
two  bearing  shoulders  in  its  depth,  one  behind  the  other,  in  addition  to  the  tenon  which  unites  them. 
Struts  and  braces  which  are  loaded  require  but  little  mortising  to  keep  them  from  sliding  out  of  their 
places  : the  more  flat  their  ends  can  be  cut,  the  more  efficient  will  they  be.  The  shrinking  of  timbers 
sometimes  occasions  them  to  become  loose,  particularly  where  there  is  not  much  stress  upon  them. 

King-posts,  queens,  and  principal  rafters,  which  are  subject  to  great  strains,  should  have  iron  straps 
or  ties  when  they  unite  with  the  tie-beam,  as  in  Figs.  2456  and  2457  ; and  an  iron  strap  should  embrace 


2457. 


the  head  of  the  kings  and  queens,  and  unite  with  the  principal  rafters,  the  feet  of  which,  in  large  build- 
ings, sometimes  have  their  abutment  in  a cast-iron  shoe,  which  prevents  the  splitting  off  the  end  of  the 
tie-beam. 

The  ends  of  king  or  queen  posts  may  have  a screw-bolt  passed  into  them,  which  allows  the  nut  to  be 
turned  at  pleasure ; and  thus  the  framing  may  be  tightened  again  when  shrinking  of  the  timbers  ren- 
ders it  necessary.  This,  in  many  instances,  is  preferable  to  the  iron  strap,  and  keys  or  screws  put  in 
the  ordinary  way. 

Whatever  form  we  adopt  for  the  butting-joint,  we  must  be  careful  that  all  parts  bear  alike  ; for,  in 
the  general  compression,  the  greater  surfaces  will  be  less  affected  and  the  smaller  undergo  the  greatest 
change.  When  all  have  come  to  their  bearing,  they  should  exhibit  an  equally  close  joint ; and  as  large 
timbers  are  moved  with  some  difficulty,  the  joint  cannot  be  often  put  to  the  test  of  trying  whether  it 
fits  nicely  : it  must,  therefore,  be  set  out  with  great  precision,  and  worked,  with  regard  to  its  lines,  with 
exactness.  A very  small  portion  of  a tie-beam  left  at  the  end  is  sufficient  to  withstand  the  horizontal 
thrust  of  a principal  rafter,  and  blocks  may  be  used  at  the  ends  where  the  rafters  abut  to  give  additional 
strength. 

Scarfing  a timber  in  a perpendicular  direction. — When  the  top  surface  is  divided  into  nine  squares,  if 
four  are  cut  down,  the  other  five  serve  as  tenons  to  enter  into  as  many  vacant  spaces  left  in  the  piece 
of  timber  placed  upon  it,  as  seen  in  Fig.  2458  ; or  two  may  be  cut  away,  as  in  the  same  figure,  to  re- 
ceive a tenon  left  on  the  upper  piece. 


2453. 


2459. 


Partitions  and  framing  for  the  outside  of  buildings , &c.,  Fig.  2459,  are  a species  of  timber  walls, 
usually  covered  with  lath  and  plaster,  and  formed  of  upright  posts,  mortised  into  a head  and  sill, 
braced  in  different  directions,  and  filled  in  with  quarters.  The  posts  are  placed  at  the  extremities,  as 
well  as  at  the  sides  of  all  doors  and  openings.  When  a partition  dividing  two  or  more  rooms  has  a 
bearing  which  is  perfectly  solid  throughout,  it  is  better  without  braces  : the  posts  or  quarters  have 
only  then  to  be  maintained  in  an  upright  position,  which  is  effected  by  driving  pieces  between  them 
horizontally,  so  as  to  strut  them,  and  prevent  their  bending.  Where  they  rest  upon  joists,  which  are 
liable  to  shrink,  and  yield  to  a weight  placed  upon  them,  the  partition  should  be  trussed  in  a manner 
to  throw  its  load  on  the  parts  able  to  sustain  it.  In  most  houses  we  find  great  neglect  upon  this  sub- 
ject, wliich  occasions  cracking  in  the  cornice,  inability  to  open  and  shut  the  doors,  and  many  other  incon- 
veniences. 

The  thickness  given  to  partitions  which  do  not  exceed  20  feet  in  length,  is  4 inches.  The  posts  are 
then  4 inches  square,  and  the  other  timbers  4 by  3.  When  they  are  of  greater  extent,  they  should  be 
lucrcased  in  thickness.  When  it  is  required  to  make  a doorway  in  the  middle,  the  truss  may  be  formed 


JOINTS,  AND  JOINING  TIMBERS. 


151 


by  the  braces,  tlie  inclination  of  which  should  be  at  an  angle  of  about  40°  with  the  horizon.  When  the 
doors  are  at  the  sides,  the  truss  may  be  formed  over  the  heads.  The  posts  should  all  be  strapped  tc 
the  truss,  and  the  braces  halved  into  the  upright  posts. 

The  weight  of  a square  of  quartered  partition  may  be  estimated  at  from  12  cwt.  to  18  cwt.,  and  every 
precaution  should  be  taken  to  discharge  its  weight  from  the  floor  on  which  it  is  placed,  to  the  walls, 
which  are  its  best  points  of  support.  In  ancient  timber  houses,  mills,  Ac.,  the  fronts  or  external  sides 
are  formed  of  upright  posts,  placed  at  a distance  equal  to  their  scantling  : these  are  mortised  and  ten- 
oned into  a top  and  bottom  plate,  which  serves  also  to  carry  the  floors.  The  posts  at  the  angles  are  of 
a larger  scantling  ; and  into  these,  which  form  openings  for  doors  and  windows,  are  framed  horizontal 
pieces,  which  serve  for  heads  and  sills.  Braces  are  then  introduced,  crossing  each  other,  like  a St. 
Andrew’s  cross.  Above  the  lintholes,  and  beneath  the  sills,  short  quarters  or  punchions  fill  in  the 
space,  and  the  whole  are  mortised,  tenoned,  and  pinned  together.  The  framing  should  be  placed  on 
brickwork,  or  a wall  of  masonry,  so  as  to  be  kept  quite  clear  of  the  ground. 

Floors. — When  the  bearings  are  equal,  if  joists  of  the  same  width,  but  of  different  depths  or  thick- 
nesses, are  used,  their  strength  is  increased  in  proportion  to  the  squares  of  their  vertical  thickness  : 
when  the  joists  are  but  6 inches  deep,  they  are  in  strength  to  those  of  8 inches  in  depth,  as  36  to  64 — 
the  square  of  6 being  36,  and  that  of  8,  64.  The  quantity  of  timber  in  the  one  case  to  that  of  the 
other  is  as  4 to  3 — so  that  one-third  more  timber  gives  a strength  double  that  of  the  other. 

Where  square  oak  joists  are  used,  and  the  bearing  1'2  feet,  their  scantlings  should  be  6 inches,  and 
laid  at  a similar  distance  apart.  Such  a floor  contains  the  same  quantity  of  timber  as  if  entirely  formed 
of  3-inch  plank  : the  strength  of  timber  being  as  the  square  of  its  vertical  thickness,  it  results  that  the 
strength  in  these  two  instances  is  as  2 to  1 : the  floor  composed  of  3-inch  plank  is  only  half  the  strength 
of  the  other ; but  had  the  whole  been  formed  6 inches  thick,  instead  of  with  joists  6 inches  apart,  it 
would  have  been  4 times  as  strong — the  square  of  3 being  9,  and  the  square  of  6,  36. 

Naked  floors  are  divided  into  single-joisted,  double,  and  framed  floors  : and  it  must  be  remarked  that 
unsawn  timbers  are  considerably  stronger  than  planks  or  scantlings  cut  out  of  a round  tree.  When  a 
tree  is  cut  longitudinally,  and  formed  into  two  pieces,  these  will  support  less  than  they  would  do  when 
united  in  the  original  tree,  arising  from  the  circular  concentric  rings  which  compose  the  tree  being  cut 
through,  which  renders  the  timber  more  compressible  on  one  side  than  on  the  other  ; and  as  the  texture 
is  less  close  where  it  has  been  sawn,  it  is  also  more  susceptible  of  change  from  humidity  on  alternation 
of  temperature. 

Joists  whose  width  is  less  than  half  their  vertical  thickness,  are  subject  to  twist  and  bend  if  not 
strutted ; and  for  this  reason  squared  timber  was  usually  employed  by  the  builders  in  the  middle  ages  ; 
and  we  have  numerous  examples  four  or  five  hundred  years  old,  where  the  timber  selected  has  the  pith 
in  the  centre,  and  the  concentric  rings  nearly  entire,  being  in  a sound  and  perfect  condition.  Experience 
also  teaches  us  that  timber,  whether  sawn  or  unsawn,  used  for  a floor  of  16  feet  bearing,  composed  of 
12  joists,  8 inches  square,  placed  at  a distance  of  a foot  apart,  is  much  stronger  than  another  of  24 
joists,  8 by  4,  placed  edgeways,  at  a distance  of  6 inches  apart,  although  there  is  the  same  quantity  of 
timber  in  both  cases. 

Single-joisted  floors  consist  of  one  series  of  joists,  which  ought  to  be  let  down  or  halved  on  to  wall- 
plates  of  a sufficient  strength  and  scantling  to  form  a tie,  as  well  as  a support  to  the  floors.  Each  joist 
should  be  spiked  or  pinned  to  the  timbers  on  which  it  lies.  Wherever  fireplaces  occur,  and  the  joists 
cannot  get  a bearing  on  the  wall,  they  are  let  into  a trimmer  or  piece  of  timber  framed  into  the  two 
nearest  joists  that  have  a bearing:  into  this  the  other  joists  are  mortised.  As  the  trimming  joists  sup- 
port a greater  weight,  they  must  be  made  stronger  than  the  others,  and  should  have  an  eighth  of  ar. 
inch  additional  thickness  given  to  them  for  every  joist  they  carry.  When  the  bearing  exceeds  8 or  9 
feet  the  joists  should  be  strutted,  or  they  will  have  an  inclination  to  turn  sideways  : the  joists  in  use. 
being  generally  thin  and  deep,  require  strutting  on  all  occasions,  and  a rod  of  iron  is  often  passed 
through  them,  which,  being  screwed  up  after  the  strutting-pieces  are  placed,  gives  the  entire  floor  great 
solidity  and  firmness.  The  weight  of  a square  of  single-joisted  floor  varies  from  10  cwt.  to  1 ton,  and 
the  joists  should  never  extend  to  a greater  bearing  than  20  feet  in  ordinary  cases. 


2460.  Mortises  and  Tenons. 


To  find  the  depth  of  a joist,  when  the  length  of  bearing  and  breadth  in  inches  is  given  : divide  the 
square  of  the  length  in  feet  between  the  supports  by  the  breadth  of  the  joist  in  inches,  and  the  cube 
root  of  the  quotient,  multiplied  by  2'2  for  fir  and  2'3  for  oak,  gives  the  depth  in  inches.  A single-joisted 
floor  which  has  the  same  quantity  of  timber  as  a double  floor,  is  considerably  stronger,  particularly  if 
properly  strutted,  than  the  latter.  The  plates,  bedded  on  the  walls,  upon  which  the  joists  are  to  be 
tailed  down,  should  have  their  depth  equal  to  half  that  of  the  joists,  and  their  width  half  as  much 
more.  In  many  instances  the  plates  are  not  bedded  entirely  in  the  wall,  but  have  one-half  resting 
beyond  the  face  on  corbels  let  into  the  wall,  at  a distance  of  6 feet  apart.  To  form  the  entaille  ot 
dovetail,  great  care  should  be  used,  to  prevent  the  joist  from  drawing  out  of  its  place  when  once 
pinned  down. 


152 


KILN. 


Double  floors  are  formed  of  joists,  binders,  and  ceiling-joists.  The  binders  rest  upon  the  plate* 
bedded  on  the  walls,  and  serve  the  purpose  of  supports  to  the  joists  which  are  bridged  on  them,  as  well 
us  to  the  ceiling-joists,  which  are  pulleys  mortised  into  their  sides.  When  the  depth  of  a binding-joist 
is  required,  the  length  and  breadth  being  given,  divide  the  square  of  the  length  in  feet  by  the  breadth 
in  inches,  and  the  cube  root  of  the  quotient,  multiplied  by  342  for  fir,  and  3'53  for  oak,  will  give  the 
depth  in  inches.  When  the  length  and  depth  are  given,  and  the  breadth  is  required,  divide  the  square 
of  the  length  in  feet  by  the  cube  of  the  depth  in  inches,  and  multiply  the  quotient  by  40  for  fir,  and  44 
for  oak,  which  will  give  the  breadth.  The  above  rules  suppose  the  binders  to  be  placed  at  a distance 
of  6 feet  from  each  other. 

Binding-joists  (Fig.  2461)  must  be  framed  into  the  girders,  and  care  must  be  taken  that  the  bearing 
parts  fit  the  mortise  made  for  them  very  accurately  : the  tenon  should  be  one-sixth  of  the  depth,  and 
placed  at  one-third  of  the  depth,  measured  from  the  lower  side.  When  binding-joists  only  are  employed 
to  carry  the  ceiling,  their  scantlings  may  be  found  in  the  same  manner  as  those  of  ceiling-joists,  which 
are  small  timbers,  and  only,  of  a sufficient  thickness  to  nail  the  laths  to.  When  their  length  and  bearing 
are  given,  their  depth  may  be  found  by  dividing  the  length  in  feet  by  the  cube  root  of  the  breadth  in 
inches,  and  multiplying  the  quotient  by  0 64  for  fir,  or  0'67  for  oak,  which  will  give  their  depth  in 
inches.  Ceiling-joists  are  usually  notched  to  the  under  sides  of  the  binding-joists,  and  nailed  to  them  : 
this  is  better  than  mortising,  which  weakens  the  binder,  and  gives  more  labor. 


KALEIDOSCOPE.  This  instrument,  the  invention  of  Dr.  Brewster,  in  its  most  common  form  con- 
sists of  a tin  tube,  containing  two  reflecting  surfaces,  inclined  to  each  other  at  any  angle  which  is  an 
aliquot  part  of  360°.  The  reflecting  surfaces  may  be  two  plates  of  glass,  plain  or  quicksilvered,  or  two 
metallic  surfaces,  from  which  the  light  suffers  total  reflection.  The  inclination  of  the  reflector  that  is  in 
general  most  pleasing  is  18°,  20°,  22-J-0,  or  the  twentieth,  eighteenth,  and  sixteenth  part  of  a circle  ; but 
the  planes  may  be  set  at  any  required  angle,  either  by  a metallic,  a paper,  or  cloth  joint,  or  any  other 
simple  contrivance.  When  the  two  planes  are  put  together,  with  their  straightest  and  smoothest  edge 
in  contact,  they  will  have  the  form  of  a book  opened  at  one  side.  When  the  instrument  is  thus  con- 
structed, it  may  be  covered  up  either  with  paper  or  leather,  or  placed  in  a cylindrical  or  any  other  tube, 
so  that  the  triangular  aperture  may  be  left  completely  open,  and  also  a small  aperture  at  the  opposite 
extremity  of  the  tube.  If  the  eye  be  placed  at  the  aperture,  it  will  perceive  a brilliant  circle  of  light, 
divided  into  as  many  sectors  as  the  number  of  times  that  the  angle  of  the  reflectors  is  contained  in 
360°.  If  this  angle  be  18°,  the  number  of  sectors  will  be  20  ; and  whatever  be  the  form  of  the  aper- 
ture, the  luminous  space  seen  through  the  instrument  will  be  a figure  produced  by  the  arrangement  of 
twenty  of  these  apertures  round  the  joint  as  a centre,  in  consequence  of  the  successive  reflections  be- 
tween the  polished  surfaces.  Hence  it  follows  that  if  any  object,  however  ugly  or  irregular  in  itself,  be 
placed  before  the  aperture,  the  part  of  it  that  can  be  seen  through  the  aperture  will  be  seen  also  in 
e^erv  sector,  and  every  image  of  the  object  will  coalesce  into  a form  mathematically  symmetrical,  and 
highly  pleasing  to  the  eye. 

The  eye-glass  placed  immediately  against  the  end  of  the  mirrors,  as  well  as  another  glass  similarly 
situated  at  the  other  end,  is  of  common  transparent  glass.  The  tube  is  continued  a little  beyond  this 
second  glass,  and  at  its  termination  is  closed  by  a ground  glass,  which  can  be  put  on  and  off.  In  the 
vacant  space  thus  formed,  beads,  pieces  of  colored  glass,  and  other  small  bright  objects  are  put.  The 
changes  produced  in  their  position  by  turning  the  tube  give  rise  to  the  different  figures. 

KEDGE.  A small  anchor  used  to  keep  a ship  steady  and  clear  from  her  bower  anchor  while  she 
rides  in  a harbor  or  river.  They  are  generally  furnished  with  an  iron  stock,  which  is  easily  displaced 
for  the  convenience  of  stowing. 

KEEL.  The  principal  piece  of  timber  in  a ship,  which  is  usually  first  laid  on  the  blocks  in  building. 
It  supports  and  unites  the  whole  fabric — since  the  stem  and  stern  posts,  which  are  elevated  on  its 
ends,  are,  in  some  measure,  a continuation  of  the  keel,  and  serve  to  connect  and  enclose  the  extremities 
of  the  sides  by  transoms,  as  the  keel  forms  and  unites  the  bottom  by  timbers. 

False-lceel  is  a strong,  thick  piece  of  timber  bolted  to  the  bottom  of  the  keel,  which  is  very  useful  in 
preserving  its  lower  side.  In  large  ships  of  war  the  false  keel  is  composed  of  two  pieces,  called  the 
upper  and  lower  false  keels. 

Keel  is  also  a name  given  to  a low,  flat-bottomed  vessel,  used  in  the  river  Tyne  to  bring  the  coals 
down  from  Newcastle  for  loading  the  colliers  : hence  a collier  is  said  to  carry  so  many  keels. 

KEELSON.  A piece  of  timber  forming  the  interior  of  the  keel,  being  laid  upon  the  middle  of  the 
floor-timbers  immediately  over  the  keel,  and  serving  to  bind  and  unite  the  former  to  the  latter  by 
means  of  long  bolts  driven  from  without,  and  clinched  on  the  upper  side  of  the  keelson. 

KILN.  A structure  or  machine  designed  for  drying  substances  by  the  application  of  heat.  Their 
forms  are  as  various  as  the  substances  or  manufactures  for  which  they  are  designed  ; for,  although  it 
may  be  said  that  a certain  kiln  will  answer  several  purposes,  yet  for  one  single  purpose  we  often  find  a 
variety  of  kilns  employed.  The  requisite  qualities  in  a good  kiln  are  cheapness  and  durability  of  con- 
struction, effectiveness  in  producing  the  required  result  with  the  utmost  economy  of  fuel,  a perfect  com- 
mand of  the  temperature,  and  facility  of  working.  Ovens  must  be  regarded  as  of  the  same  class  ot 
apparatus  as  kilns : indeed,  the  terms  kiln  and  oven  are  often  indiscriminately  applied  to  the  same 
structure,  as  may  be  noticed  under  several  articles  in  this  work.  Under  the  head  of  Lime  the  usual 
for  m of  lime-kilns  is  described ; and  under  Coal  and  Iron,  several  forms  of  coke-ovens.  In  this  place 
we  shall  notice  a combination  of  both,  which  was  the  subject  of  a patent  granted  to  Mr.  Charles 
Heathoru  about  seven  years  ago,  since  which  time  it  has  been  in  successful  operation. 

Heo.th.orrC s patent  combination  of  a lime-kiln  with  a coke-oven. — The  object  of  this  invention,  as  ex- 
pressed in  the  specification  of  the  patent,  is  the  preparation  of  quick-lime  and  coke  in  the  same  kiln  at 
one  operation.  The  economy  of  tins  process  must  be  evkWt  from  the  circumstance,  that  the  infiamma- 


KILN. 


153 


ble  part  of  the  coal  which  is  separated  to  form  it  into  coke,  is  the  only  fuel  employed  to  burn  the  lime , 
and  as  the  coke  is  in  many  places  as  valuable  as  the  coal  from  which  it  is  prepared,  the  cost,  if  any,  ol 
making  lime,  must  be  reduced  to  the  most  trifling  amount.  Fig.  2462  presents  a vertical  section  of  the 
lime-shaft  and  coke-ovens  : a a are  the  side  walls,  4 feet  thick,  of  a rectangular  tower,  the  internal 
space  being  filled  with  limestone  from  the  top  to  the  iron  bars  b b at  bottom,  whereon  the  whole  column 
rests.  The  limestone  is  raised  in  a box  d,  or  other  proper  receptacle,  to  the  top  of  the  building,  by 
means  of  a jib  and  crane  e , or  other  tackle,  which  is  fixed  at  the  back  of  the  tower,  together  with  a 
platform  projecting  beyond  the  walls  for  affording  security  and  convenience  for  “ landing”  the  limestone 
when  raised  as  represented,  the  jib  is  swung  round,  and  the  lime-box  tilted,  by  which  the  whole  con- 
tents are  thrown  down  the  shaft.  The  coke-ovens,  of  which  there  may  be  two,  or  a greater  or  lesse 


number,  according  to  the  magnitude  of  the  works,  are  constructed  and  arranged  in  connection  with  tne 
lime-shaft  in  the  same  manner  as  the  two  represented  in  the  diagram  a iff  These  ovens  are  supplied 
with  coal  through  iron  doors  in  the  front  wall,  (not  seen  in  the  section  ;)  the  doors  have  a long  and  nar- 
row horizontal  opening  in  the  upper  part  of  them  to  admit  sufficient  atmospheric  air  to  cause  the  com- 
bustion of  the  bituminous  or  inflammable  part  of  the  coal ; the  flames  proceeding  from  thence  pass  into 
the  lime-shaft  through  a series  of  lateral  flues,  (two  of  which  are  brought  into  view  at  g g,)  and  the  draught 
is  prevented  from  deranging  the  process  in  the  opposite  oven  by  the  interposition  of  the  partition  wall 
h , which  directs  the  course  of  the  heat  and  flames  throughout  the  whole  mass  of  the  lime,  the  lower- 
most and  principal  portion  of  which  attains  a white  heat,  the  upper  a red  heat,  and  the  intervening 
portions  the  intermediate  gradations  of  temperature.  When  the  kiln  is  completely  charged  with  lime, 
the  openings  in  front  and  beneath  the  iron  bars  at  i i are  closed  and  barricaded  by  bricks  and  an  iron- 
cased  door,  which  is  internally  filled  with  sand  to  effectually  exclude  the  air,  and  prevent  the  loss  of 
heat  by  radiation.  Therefore,  when  the  kiln  is  at  work,  no  atmospheric  air  is  admitted  but  through  th« 
narrow  apertures  before  mentioned  in  the  coke-oven  doors.  When  the  calcination  of  the  lime  is  com- 


154 


KILN. 


pleted,  the  barricades  at  i i are  removed,  the  iron  bars  at  b b are  drawn  out,  by  which  the  hme  fall* 
down  and  is  taken  out  by  barrows.  It  sometimes  happens,  however,  that  the  lime  does  not  readily  fall 
having  caked  or  arched  itself  over  the  area  that  encloses  it,  in  which  case  a hooked  iron  rod  is  em- 
ployed to  bring  it  down.  To  facilitate  this  operation  in  every  part  of  the  shaft  where  it  may  be  neces- 
sary, a series  of  five  or  six  apertures,  closed  by  iron  doors,  is  made  at  convenient  distances  from  the 
top  to  near  the  bottom  of  the  shaft : two  of  these  are  brought  into  view  at  k k.  Two  similar  apertures 
are  shown  in  section  in  the  coke  ovens  at  b b,  which  are  for  the  convenience  of  stoking  and  clearing  out 
the  lateral  flues  g g from  any  matter  that  might  obstruct  the  free  passage  of  the  heated  air.  When  the 
coals  have  been  reduced  to  coke,  the  oven  doors  in  front  (not  shown)  are  opened,  and  the  coke  taken 
out  by  a peel  iron,  the  long  handle  of  which  is  supported  upon  a swinging  jib  that  acts  as  a movable 
fulcrum  to  the  lever  or  handle  of  the  peel,  and  facilitates  the  labor  of  taking  out  the  contents  of  the 
oven.  The  operation  of  this  kiln  is  continuous,  the  lime  being  taken  from  the  bottom  whenever  it  is 
sufficiently  burned,  and  fresh  additions  of  raw  limestone  being  constantly  made  at  the  top. 

Kilns  for  drying  corn. — If  air  and  moisture  be  carefully  excluded  from  grain,  it  may  be  kept  unin- 
jured for  an  indefinite  length  of  time.  This  is  proved  by  an  extraordinary  experiment  made  with  some 
Indian  corn  found  in  the  graves  of  the  ancient  Peruvians,  buried  more  than  300  years  ago.  Some  of 
this  corn  being  sown,  it  vegetated  and  came  to  maturity.  We  believe  a similar  fact  is  recorded  respect- 
ing some  grain  found  in  the  ruins  of  Herculaneum.  But  to  preserve  corn,  even  for  a short  period,  it 
should  be  perfectly  dry  when  housed,  and  carefully  protected  from  dampness.  But  it  not  unffequently 
happens,  during  a wet  harvest  season,  that  the  corn  is  necessarily  carried  from  the  field  in  a damp  state ; 
and  as  few  farmers  have  the  means  of  properly  and  speedily  drying  it,  large  quantities  are  irrecoverably 
spoiled  after  all  the  labor  and  cost  of  production.  The  method  of  drying  on  the  perforated  floor  of  a 
kiln  (which  is  usually  resorted  to  where  it  can  be  obtained)  is  a very  tedious,  defective,  and  expensive 
mode,  and  is  attended  with  great  labor,  owing  to  the  grain  requiring  to  be  continually  turned  over  and 
spread  by  a workman,  whose  utmost  care  is  insufficient  to  cause  every  part  to  receive  an  equal  degree 
of  heat.  It  therefore  becomes  a matter  of  considerable  importance  to  devise  a simple,  efficacious,  and 
economical  method  of  drying  grain  under  these  circumstances  ; and  we  think  Mr.  Jones’s  apparatus  for 
this  purpose,  shown  in  the  following  figures,  is  well  adapted  to  the  end  proposed.  Fig.  2463  is  a ver- 
tical section  of  the  apparatus,  which  is  formed  of  two  iron  cylinders  a b , placed  one  within  the  other, 


each  being  closed  at  the  upper  and  lower  end  by  two  concentric  cones,  C D.  The  annular  space  be- 
tween the  cylinders,  as  also  between  the  cones,  is  an  inch  and  a quarter  in  width,  for  the  reception  of 
the  grain,  to  be  dried  by  its  passing  through  the  machine  : both  the  internal  and  external  bodies  are 
perforated  throughout  with  about  2300  holes  to  the  square  foot.  The  kiln  is  supported  on  five  cast-iron 
columns,  or  legs,  three  of  which  are  shown  in  the  section  as  at  E : these  are  attached  to  a strong  iron 
ring  which  surrounds  the  base  of  the  cylinder.  From  the  heads  of  these  columns  descend,  along  the 
sides  of  the  cone,  five  long  bolts,  as  at  G-,  which  are  passed  through  the  same  number  of  legs  in  the 
cast-iron  ring  surrounding  the  neck  of  the  lower  cone.  From  this  ring  proceed  five  stays,  as  at  I,  which 
are  fastened  to  the  middle  of  the  columns  by  a nut  on  each  side.  The  body  is  sustained, “both  exter- 
nally and  internally,  by  iron  hoops,  as  at  K,  and  the  distance  between  the  cylinders  is  preserved  by  a 
number  of  short  stays.  In  the  front  of  the  kiln  a passage  is  cut  out,  as  at  0,  in  which  is  fixed  the  fire- 
place, through  which  are  passages  for  the  heated  air  to  pass  into  the  cylinder.  These  passages,  as  well 
as  the  flues,  which  proceed  circuitously  from  the  fire  to  the  chimney,  are  best  shown  in  the  horizontal 


KILN. 


15< 


section,  Fig.  2464.  And  in  the  vertical  section  of  the  detached  fireplace,  Fig.  2465,  Q is  the  fire-hole, 

S the  ash-hole,  T the  fire-bars,  and  U the  chimney,  which  passes  up  nearly  in  the  middle  of  the  kiln. 
The  wheat  is  admitted  into  the  kiln  from  above  through  a hopper,  and  through  the  tube  W,  and,  falling 
upon  the  apex  of  the  cone,  is  distributed  equally  on  all  sides  between  the  cylinders,  the  little  asperities 
in  which  not  only  slightly  retard  the  descent  of  the  grain,  but  likewise  impart  to  the  particles  a con- 
stant, slow,  rolling  motion,  whereby  every  individual  grain  is  exposed  to  the  same  degree  of  tempera- 
ture ; the  grain  from  thence  converges  into  the  lower  cone,  and  ultimately  escapes  through  the  spout  at 
bottom  into  sacks,  or  on  to  the  ground,  as  may  be  required.  The  passage  of  the  grain  through  the 
machine  may  be  either  accelerated  or  retarded,  according  to  its  peculiar  condition,  by  enlarging  or  con- 
tracting the  aperture  through  which  it  is  discharged.  The  moisture  is  carried  off  by  evaporation 
through  the  perforations  of  the  plates,  with  great  rapidity.  The  kilns 
may,  of  course,  be  made  of  any  dimensions.  One  of  6 feet  internal  di- 
ameter, and  12  feet  in  length,  between  the  apexes  of  the  upper  and  lower 
cones,  has  been  said  to  be  capable  of  perfectly  drying  more  than  100 
quarters  of  wheat  in  24  hours. 

In  Fig.  2466  is  shown  a contrivance  for  drying  grain  which  lias  been 
noticed  in  several  French  papers,  and  announced  as  having  been  success- 
fully adopted  in  one  of  the  departments.  The  apparatus  consists  of  a 
long  spiral  tube  a a like  a distiller’s  worm,  reaching  from  the  basement  to 
the  upper  floor  and  through  the  roof  of  the  granary,  which  forms  a passage 
for  the  heated  air  from  a close  stove  below.  Externally  round  this  tube 
is  placed  another  tube  b b,  winding,  like  the  interior  one,  in  a spiral  direc- 
tion, and  at  about  an  inch  and  a half  from  it.  This  external  tube  receives 
the  corn  from  above,  through  a hopper  c,  and  it  is  punched  throughout 
with  numerous  small  holes,  through  which  the  vapor  escapes,  as  it  is 
formed  by  the  damp  corn  coming  in  contact  with  the  inclosed  heated  chim- 
ney. The  corn,  in  consequence,  becomes  thoroughly  dried  before  being 
discharged  at  the  bottom,  and  that  without  the  intervention  of  any  manual 
labor. 

Hebert’s  patent  kiln  was  devised  for  drying  washed  grain  ; but  as  this 
kiln  is  equally  applicable  to  the  drying  of  malt,  seeds,  and  all  other 
matters  of  a similar  kind  and  form,  and  by  a mode  that  is  as  novel  as  it 
is  efficacious,  we  give  a description  of  it  in  this  place.  In  the  following 
engravings,  Fig.  2467  exhibits  a longitudinal  section  of  the  apparatus, 
and  Fig.  2468  a transverse  section  of  a long  air-trough,  shown  at  e in  Fig. 

2467.  At  a is  shown  one  of  a series  of  five  or  six  common  iron  gas- 
tubes,  placed  side  by  side,  and  curved  in  the  form  represented  to  consti- 
tute a fireplace ; the  space  between  the  tubes  serving  for  the  admission 
of  air  for  combustion,  which  enters  through  the  ash-pit  door  b at  the 
side,  provided  with  an  air  regulator : the  fireplace  is  inclosed  in  front, 
at  c,  by  a common  door  and  frame.  The  heated  air,  and  other  products 
of  combustion  from  the  fuel,  pass  along  the  flue  d to  the  funnel  or  chim- 
ney. The  bottom  and  two  sides  of  the  flue  d are  of  brick,  but  the  top  is 
of  iron,  being  formed  of  the  bottom  of  a long,  shallow  iron  box,  or  air- 
trough,  e ; this  box  has  no  cover  but  one  of  extremely  open-wove  canvas, 
which  forms  a part  of  an  endless  cloth  or  band  fff,  that  is  continually 
made  to  travel  lengthwise  over  the  whole  area  of  the  said  trough — the 
edges  of  the  cloth  gliding  between  grooves  and  over  tie-rods,  (shown  in 
the  cross  section,  Fig.  2468,  where  the  dotted  line  f indicates  the  endless 
cloth,)  that  prevent  the  cloth  from  sagging.  This  cloth  is  made  to  travel 
by  the  revolution  of  three  rollers  or  drums  ej  h i,  to  either  of  which  the 
moving  power  may  be  applied.  The  cloth  is  kept  distended  by  a self- 
acting tightening  roller,  which  is  screwed  against  the  hopper  k ; tliis 
hopper  receives  the  grain  to  be  dried,  and  is  provided  with  a shoe  at  l, 
adapted  to  defiver  a tliin  and  uniform  stratum  of  grain  upon  the  endless  cloth,  while  the  same  is  made 
to  pass  under  it,  and  over  the  trough.  Another  endless  band  m m,  of  a similar  fabric  to  the  other, 
passes  round  the  drums  h i only,  and  is  likewise  provided  with  a self-acting  tightening  roller,  fixable  to 
any  convenient  object.  The  lower  ends  of  the  six  tubes  a of  the  fireplace  before  mentioned  have  an 
open  communication  with  a rotative  blower  o,  by  means  of  a broad  channel  pp  ; and  the  upper  ends 
of  the  tubes  a also  open  into  another  broad  channel  q,  which  conducts  the  air  into  the  long  air-trough  e 
The  operation  of  this  machine  is  as  follows  : A slow  rotation,  derived  from  any  first  mover,  is  to  be 
given  to  either  of  the  drums  g h i,  which  will  cause  the  endless  cloth  f to  glide  gradually  over  the 
top  of  the  air-trough  e ; at  the  same  time  the  blower  o has  been  put  into  action  (by  connection  with 
the  first  mover)  at  a high  velocity,  so  as  to  produce  a rapid  current  of  air,  which  derives  an  increase 
of  temperature  on  passing  under  the  heated  metallic  bottom  of  the  ash-pit ; hence  proceeding  through 
the  tubes  a,  it  acquires  considerable  heat,  which  is  subsequently  moderated  by  an  extensive  diffusion 
in  the  air-trough  e,  before  it  passes  through  the  meshes  of  the  endless  cloth  f above,  carrying  with  it 
the  moisture  from  the  grain  deposited  thereon.  The  course  taken  by  the  endless  cloth  is  shown  by 
arrows  in  the  figure  : upon  its  arriving  at  the  drum  h,  the  other  endless  eloth  m m comes  in  contact 
with  the  grain  on  the  cloth /,  and,  upon  both  the  cloths  passing  round  the  said  drum  /(,  the  corn  be- 
comes inclosed  between  the  two  cloths,  and  is  thus  carried  up  an  inclined  plane  over  the  drum  1,  where 
the  cloths  separate,  and  discharge  (be  grain  back  again  into  the  hopper  k,  to  undergo  a repetition  ol 
the  operation,  should  it  not  be  perfectly  dry.  But  when  the  grain  is  thoroughly  dried,  instead  of  allow-  # 


2466. 


156 


KNEADING. 


mg  it  to  fall  back  into  the  hopper,  a shoot,  or  the  band  of  a creeper,  (not  shown  in  the  drawing,)  is 
brought  under  the  roller  i,  which  conducts  it  to  the  required  place.  A very  little  experience  in  th* 
working  of  this  apparatus  enables  a person  so  to  regulate  its  operations  as  to  complete  the  drying  o 


damp  grain  by  a single  passage  through  it ; such  as  varying  the  velocity  of  the  air-forcer,  the  quantity 
of  fuel  in  the  stove,  the  supply  of  air  through  the  ash-pit,  the  speed  of  the  endless  cloth,  Ac.,  the  means 
of  doing  which  arc  so  well  understood  by  mechanics  as  to  render  a description  of  them  unnecessary  in 
this  place. 

KITE.  This  well-known  juvenile  plaything  has  beer),  applied  to  several  objects  of  utility.  The 
most  important  of  these  is  the  invention  of  Captain  Dansey,  for  effecting  a communication  between  a 
stranded  ship  and  the  shore,  or,  under  other  circumstances,  where  badness  of  weather  renders  the  ordi- 
nary means  impracticable.  The  following  is  an  abbreviated  description  of  the  invention,  extracted  from 
the  forty-first  volume  of  the  Transactions  of  the  Society  of  Arts,  where  the  subject  is  given  more  in 
detail,  with  engraved  illustrations : — A sail  of  light  canvas  or  holland  is  cut  to  the  shape,  and  adapted 
for  the  application  of  the  principles  of  the  common  flying  kite,  and  is  launched  from  the  vessel  or  other 
point  to  windward  of  the  space  over  which  a communication  is  required  ; and  as  soon  as  it  appears  to 
be  at  a sufficient  distance,  a very  simple  and  efficacious  mechanical  apparatus  is  used  to  destroy  its 
poise  and  cause  its  immediate  descent,  the  kite  remaining,  however,  still  attached  to  the  line,  and 
moored  by  a small  anchor  with  which  it  is  equipped.  The  kite,  during  its  flight,  is  attached  to  the  line 
by  two  cords  placed  in  the  usual  manner,  which  preserves  its  poise  in  the  air ; and  to  cause  it  to  de- 
scend, a messenger  is  employed,  made  of  wood,  with  a small  sail  rigged  to  it.  The  line  being  passed 
through  a cylindrical  hole  in  this  messenger,  the  wind  takes  it  rapidly  up  to  the  kite,  where,  striking 
against  a part  of  the  apparatus,  it  releases  the  upper  cord,  and  by  that  means  the  head  of  the  kite  be- 
comes reversed,  and  it  descends  with  rapidity.  In  the  experiments  made  by  Captain  Dansey,  with  the 
view  of  gaining  communication  with  a lee-shore,  under  the  supposition  of  no  assistance  being  there  at 
hand,  a grapnel,  consisting  of  four  spear-shaped  iron  spikes,  was  fixed  to  the  head  of  the  kite,  so  as  to 
moor  it  in  its  fall ; and  in  this  emergency,  the  attempt  of  some  person  to  get  on  shore  along  the  line 
would  be  the  means  resorted  to.  In  those  cases  where  a communication  has  been  gained,  and  the 
maintenance  of  a correspondence  has  been  the  object,  the  person  to  windward  has  attached  a weight  to 
the  messenger — in  some  cases  as  much  as  three  pounds — which,  having  been  carried  up,  has  of  course 
descended  with  the  kite  ; the  person  to  leeward  has  then  furled  the  sail  of  the  messenger,  and  loaded 
it  with  as  much  weight  as  the  kite  could  lift ; then  replacing  the  apparatus,  and  exposing  the  surface 
of  the  kite  to  the  direct  action  of  the  wind,  it  has  rapidly  risen,  the  messenger  running  down  the  line 
to  windward  during  its  ascent.  The  kite  with  which  Captain  Dansey  performed  the  greater  part  of  his 
experiments  extended  1100  yards  of  line,  five-eighths  of  an  inch  in  circumference,  and  would  have 
extended  more  had  it  been  at  hand.  It  also  extended  860  yards  of  line  1}  inches  iu  circumference,  and 
weighing  60  lbs.  The  holland  weighed  8 \ lbs. ; the  spars,  one  of  which  was  armed  at  the  head  with 
iron  spikes,  for  the  purpose  of  mooring  it,  6 J lbs. ; and  the  tail  was  five  times  its  length,  composed  of  8 
lbs.  of  rope  and  14  lbs.  of  elm  plank.  A complete  model  of  the  apparatus  was  deposited  with  the 
society,  who  presented  Captain  Dansey  with  their  gold  Vulcan  medal  for  his  invention  and  communi- 
cation. 

KNEADING-  is  the  process  of  making  the  stiff  paste  of  flour  and  water  for  being  afterwards  baked 
into  bread.  It  is  usually  effected  by  a sort  of  pommelling  action  of  the  hands  and  arms,  and  some- 
times of  the  feet  of  the  bakers.  A variety  of  machines  have  been  at  different  times  proposed  for 
superseding  the  barbarous  process  we  have  just  mentioned  ; they  have,  however,  been  but  very  par- 
tially adopted,  the  bakers  in  general  preferring  to  continue  their  “ good  old-fashioned”  dirty  practice. 
It  is  said  that  at  Geneva  all  the  bakers  of  that  city  are  compelled  by  law  to  send  their  dough  to  be 
kneaded  at  a public  mill  constructed  for  that  purpose.  At  Genoa,  also,  mechanism  is  employed  for 
kneading : the  apparatus  employed  at  this  place  has  been  published  in  several  of  the  journals,  from 
which  it  appears  to  be  so  rude  and  ill-contrived  as  not  to  need  a description  in  this  place. 

1.  The  petrisseur,  or  mechanical  bread-maker,  invented  by  Cavallier  and  Co.  of  Paris,  consists  in  a 
strong  wooden  trough,  nearly  square,  with  its  two  longest  sides  inclined,  so  as  to  reduce  the  area  of  the 
trough  iu  the  direction  of  its  width,  and  adapt  it  to  the  dimensions  of  a cast-iron  roller,  the  axis  of  which 


KNITTING  MACHINE. 


157 


passes  through  the  ends  of  the  trough ; the  bottom  of  the  trough  is  semi-cylindrical,  leaving  a smal. 
space  between  it  and  the  roller,  which  space  is  adjustable  by  levers.  All  along  the  top  of  the  outside 
of  the  roller  is  fixed  a knife-edge,  which,  with  the  roller,  divides  the  trough  into  two  compartments. 
U pon  the  axis  of  the  roller  is  a toothed  wheel,  which  takes  into  a pinion  ; this  pinion  is  turned  by  a 
winch,  and  communicates  thereby  a slower  motion  to  the  roller;  and  the  roller,  by  its  rotation,  forces 
the  materials  or  dough  through  the  narrow  space  before  mentioned  left  between  it  and  the  bottom  o( 
the  trough — the  knife-edge  on  the  top  of  the  roller  preventing  the  dough  from  passing  by  it.  Being 
thus  all  forced  into  one  of  the  compai  tments,  the  motion  of  the  roller  is  reversed  by  turning  the  winch 
the  contrary  way,  which  then  forces  the  dough  back  again  through  the  narrow  space  under  the  roller 
into  the  first  compartment ; in  this  manner  the  working  of  the  dough,  alternately  from  one  compart- 
ment to  the  other,  is  continued  until  completed. 

2.  Another  plan  was  to  make  the  trough  containing  the  dough  revolve  with  a number  of  heavy  ball? 
within  it.  The  trough  in  this  case  is  made  in  the  form  of  a parallelopipedon — the  ends  being  square 
and  each  of  the  sides  a parallelogram,  whose  length  and  breadth  are  to  each  other  as  five  to  one.  One 
side  of  the  trough  constitutes  a lid,  which  is  removed  to  introduce  the  flour  and  water,  and  the  trough 
is  divided  into  as  many  cells  as  there  are  balls  introduced.  The  patentee  states,  that  by  the  rotation 
of  the  trough  the  balls  and  dough  are  elevated  together,  and  by  their  falling  down  the  dough  will  be 
subjected  to  beating,  similar  to  the  operations  of  the  baker’s  hands. 

3.  Instead  of  employing  a revolving  cylinder,  it  is  fixed,  an  agitator  is  made  to  revolve,  having  a 
series  of  rings  angularly  attached  to  an  axis,  extending  the  whole  length  of  the  trough. 

4.  Mr.  Clayton,  a baker  of  Nottingham,  had  a patent  in  1830  for  a machine  somewhat  similar  to  the 
last  mentioned,  inasmuch  as  a set  of  revolving  agitators  are  employed  to  produce  the  kneading  action. 
The  agitators  are  longitudinal  bars,  fixed  to  arms,  which  radiate  from  the  axis,  and  they  are  forced 
through  the  dough  in  their  revolution ; but  the  cylinder  in  which  they  revolve,  and  which  contains  the 
materials,  is  made  to  revolve  at  the  same  time  in  a contrary  direction — the  motion  of  the  latter  being 
imparted  by  a short  hollow  axis,  while  the  axis  of  the  former  is  solid  and  passed  through  the  hollow 
one.  The  solid  axis,  which  is  turned  by  a winch,  has  on  it  a bevelled  pinion,  which,  by  means  of  an 
intermediate  bevelled  wheel,  actuates  another  bevelled  pinion  fixed  on  the  hollow  axis,  and  therefore 
causes  it  to  revolve  in  the  opposite  direction.  These  two  simultaneous  and  contrary  motions  constitute 
the  novelty  claimed  by  the  patentee,  who  states , that  dough-making  machines  similar  to  his  own  have 
all  failed  for  want  of  such  an  arrangement.  This  statement,  coming  from  a baker,  commands  attention  ; 
but  we  cannot  concur  in  its  truth,  since  we  know  that  the  following  plan  of  a kneading-machine  works 
well  without  opposite  simultaneous  motions,  and  without  any  agitators  or  beaters,  which  absorb  a great 
deal  of  power  without  producing  an  adequate  effect. 

6.  Hebert’s  patent  kneading-machine. — In  this  a cylinder  of  from  4 to  5 feet  in  diameter,  and  only 
aoout  18  inches  wide  inside,  is  made  to  revolve  upon  an  axis,  which  is  fixed  by  a pin  during  the  revo- 
lution of  the  cylinder.  The  flour  is  admitted  by  a door  in  the  periphery,  which  closes  air  and  water 
tight ; and  the  water  or  liquor  passes  through  a longitudinal  perforation  in  the  axis,  and  thence  through 
small  holes  among  the  flour,  in  quantities  which  are  regulated  externally  by  a cock.  By  the  rotation  of 
the  cylinder  the  dough  is  made  to  be  continually  ascending  on  one  side  of  it,  whence  it  falls  over  upon 
the  portion  below.  When  the  mixture  becomes  pretty  intimate  and  uniform,  its  adhesive  property 
causes  it  to  stick  to  the  sides  of  the  cylinder,  and  the  dough  would  then  be  carried  round  without  much 
advancing  the  process,  were  it  not  for  another  simple  contrivance.  This  is  a knife-edge,  or  scraper,  18 
inches  long,  which  is  fixed  along  the  top  of  the  cylinder  in  the  inside,  so  as  barely  to  touch  its  surface  : 
the  knife  is  fixed  to  two  flat  arms  extending  from  the  axis,  and  these  arms  have  sharp  edges  so  as  to 
scrape  the  sides  of  the  cylinder ; thus  the  cylinder  is  kept  constantly  clean  from  the  sticking  of  the 
dough,  which,  as  soon  as  it  ascends  to  the  top  of  the  cylinder,  (if  it  does  not  tear  away  of  itself,)  is 
shaved  off  by  the  knife,  and  falls  down  with  great  force  upon  the  bottom  ; and  as  this  effect  is  constant 
during  the  motion  of  the  cylinder,  it  must  be  evident  that  the  process  of  kneading  is  soon  completed 
by  it-  When  that  is  done,  the  door  of  the  cylinder  is  opened,  and  the  contents  discharged  into  a 
recipient  beneath  ; at  which  time  the  scraper  is  caused,  by  a winch  on  the  axis,  to  make  one  revolution 
of  the  now  fixed  cylinder,  which  clears  off'  any  adhering  dough,  and  projects  it  through  the  doorway. 
As  the  dough  in  this  machine  may  be  said  to  knead  itself — there  being  no  arms,  beaters,  or  agitators 
whatever — it  is  calculated  that  the  power  saved  by  it  is  very  considerable  ; while,  from  the  simplicity 
of  its  construction,  the  cost  is  moderate. 

The  patentee  is  at  present  engaged  in  combining  with  this  kneading  machine  an  apparatus  for  pre- 
paring carbonated  water,  highly  charged  with  the  gas,  with  which  he  proposes  to  mix  up  the  flour  to 
form  dough,  for  the  purpose  of  making  the  bread  spongy  or  vesicular,  without  having  recourse  to  the 
fermentative  process  ; the  result  of  which  process,  under  the  most  favorable  circumstances,  he  considers 
to  be  detrimental  to  the  health  of  those  that  eat  the  bread,  (owing  to  the  deposition  of  fermentable 
matter  in  the  stomach,)  while  it  is  destructive  of  a portion  of  the  nutriment  of  the  flour. 

KNITTING  MACHINE,  Improved.  From  the  specification  of  the  inventor,  J.  R.  Ellis,  of  Boston, 
Massachusetts,  patented  June  17,  1851.  Fig.  2469,*  denotes  a front  elevation  of  the  said  improved 
knitting  machine.  Fig.  2477  is  a vertical  and  transverse  section  of  it,  the  same  being  taken  in  such 
manner  as  to  exhibit  the  yarn  guide  or  director,  the  stitch  hook,  and  the  contrivance  for  forcing  the 
work  down  towards  the  roots  of  the  needles,  after  the  formation  of  each  new  loop.  Such  other  figures 
as  may  be  necessary  to  a proper  representation  of  the  various  parts  of  my  improvements,  will  be  hereafter 
referred  to  and  described. 

The  machine  as  improved,  is  not  what  is  usually  termed  a stocking  loom,  but  is  more  properly  named 
a knitting  machine,  for  the  reason  it  forms  each  stitch  of  the  work  in  regular  succession,  and  not  a num- 
ber of  stitches  at  once,  as  does  the  stocking  loom.  It  is  a machine  in  character  like  others  in  use,  al- 


Tho  letters  in  the  cut  are  by  mistake  made  capitals  instead  of  small  letters. 


158 


KNITTING  MACHINE. 


though  it  differs  from  the  same  in  sundry  important  particulars  which  constitute  my  invention,  and 
which  I shall  hereafter  describe. 

In  the  drawings  above  mentioned,  A denotes  the  endless  chain  belt  of  knitting-needles,  which  is  so 
made  that  the  needles  a a a,  d'C.,  instead  of  being  arranged  or  made  to  stand  horizontally,  and  at  right 
angles  to  the  vertical  surface  of  the  belt,  are  made  to  stand  vertically  or  in  the  plane  of  the  belt,  as  see>- 
at  a a a a,  figures  2469  and  2477. 


The  driving  pinion  b,  instead  of  being  arranged  within  the  belt  as  it  has  been  in  other  machines  of 
this  character^  is  disposed  on  the  exterior  surface  of  it,  and  works  against,  or  with  the  projecting  points 
of  the  belt.  That  part  of  the  inner  surface  of  the  belt,  which  is  immediately  adjacent  to  the  pinion,  i 
supported  by,  and  works  round  a stationary  vertical  post  or  guide  c,  (see  fig.  2471,  which  is  a vertical  sec- 
tion of  the  belt  and  its  support)  that  extends  upwards  from  a horizontal  arm  d,  which  projects  from  the 


KNITTING  MACHINE. 


159 


main  frame  B.  The  opposite  end  of  the  endless  belt  is  supported  by  a straining  contrivance  L,  which 
is  similar  to  such  as  are  in  common  use  in  such  machines.  The  work  or  knitting  hands  within  is  the 
endless  belt,  instead  of  without  it,  or  on  the  outside  of  it. 

The  yarn  guide  or  director  is  seen  at  D.  It  consists  of  a curved  arm,  made  to  extend  from  a hori- 
zontal rocker  shaft  f and  to  have  a small  conical  and  split  tube  y,  on  its  outer  end,  through  which  tube 
the  yarn  is  carried  from  the  bobbin  placed  in  any  convenient  position. 


The  stitch  hook  is  seen  at  E.  It  is  arranged  in  rear  of  the  chain  belt  of  needles,  and  is  formed  as 
represented  in  side  view  on  an  enlarged  scale,  fig.  2472,  that  is  to  say,  it  is  made  not  only  with  a hooked 
end,  as  seen  at  h,  but  with  a shoulder  i,  a short  distance  in  rear  of  said  hooked  end,  the  shoulder  per- 
forming the  important  office  of  piercing  or  casting  the  loop  (taken  up  by  the  hook)  over  the  hooked 
point  of  the  needle,  the  same  having  been  effected  in  other  machines  of  this  kind,  by  what  is  usually 
termed  the  “bent  finger.”  By  my  improvement  I am  enabled  to  dispense  with  such  bent  finger,  and  the 
machinery  for  operating  it.  In  order  that  the  stitch  hook  may  not  only  take  up  the  loop,  but  cast  it  over 
the  end  of  the  needle  and  the  yarn  laid  on  the  needle  by  the  yarn  director,  and  this  to  form  or  make  a 
new  stitch,  the  hook  should  have  the  following  movements  imparted  to  it.  First,  it  should  be  made  to 


2 GO 


KNITTING  MACHINE. 


pass  into  the  groove  of  the  needle,  and  under  the  stitch  on  the  needle.  Next,  it  should  be  made  to  rise 
upwards  so  as  to  carry  the  stitch  up  to  the  hooked  end  of  the  needle.  Next,  it  should  be  moved  late- 
rally far  enough  to  be  opposite  the  space  between  the  needle  (first  operated  upon)  and  the  next  needle. 
Next,  it  should  be  moved  forwards  between  the  two  needles  and  so  as  to  cause  the  shoulder  i,  to  press  or 
force,  or  cast  the  stitch  over  the  hooked  end  of  the  needle.  The  stitch  hook  should  next  be  drawn 
backwards,  and  depressed  so  as  to  disengage  it  from  the  stitch.  The  movements  of  the  stitch  hook  may 
be  produced  by  various  kinds  of  combinations  of  mechanism.  No  such  machinery  forms  any  part  of 
my  invention,  and  I lay  claim  to  none  in  particular,  but  employ  such  as  may  be  suitable  : that  adopted 
by  me  is  as  follows,  viz  : 

2478  2477 


The  stitch  hook  E,  is  fastened  to  the  lower  end  of  a bar  o',  which  works  or  slides  freely  up  and  down 
through  a piece  of  metal  b',  and  is  jointed  by  a joint  screw  c',  to  a connecting  rod  d ',  on  whose  upper 
end  is  a strap^/",  passing  around  an  eccentric  g\  fixed  on  the  main  driving  shaft  A',  of  the  machine. 
The  upward  and  downward  movements  of  the  stitch  hook  are  effected  by  such  eccentric  during  its  en- 
tire revolution.  In  order  to  produce  its  forward  and  back  movements,  a lever  i',  working  on  a fulcrum 
Jc\  is  jointed  at  its  lower  end  to  the  rear  end  of  the  piece  of  metal  b'.  The  upper  end  or  arm  of  the  said 
lever  rests  against  a cam  t',  fixed  on  the  driving  shaft  (see  fig.  2473,)  which  denotes  a top  view  of  the 
said  shaft,  and  the  cams  applied  to  it.  See  also  figures  2474  and  2475,  the  former  of  which  is  a side 
view  of  the  said  cam,  and  the  wing  cam  to  be  hereinafter  described,  while  the  latter  is  a top  view  of 
the  same,  made  so  as  to  show  the  form  of  the  wing  cam.  During  the  revolution  of  the  cam  the  lever 
i'  will  be  moved  forwards  and  backwards  by  the  action  of  the  said  cam  and  a spring  m , made  to  bear 
against  the  rear  side  of  the  said  lever.  The  small  wing  cam  n' , placed  on  the  side  of,  or  to  project 
above  the  cam  l',  serves  to  press  the  upper  end  of  the  lever  i laterally,  in  order  to  produce  the  lateral 
motion  of  the  stitch  hook.  A spring  o',  (see  fig.  2473,)  presses  the  end  of  the  lever  i,  against  such 
wing  cam. 

Both  the  stitch  hook  and  the  yarn  guide,  are  arranged  between  the  arms  of  the  presser,  which  presser 
consists  of  two  arms,  k , l,  extended  at  right  angles  from  a horizontal  rocker  shaft  m,  and  long  enough 
to  play  between  the  needles.  These  arms  should  be  made  to  operate  so  as  to  press  the  work  down  to  the 
roots  of  the  needles,  after  the  formation  of  each  stitch;  they  should  next  be  raised  upwards  far  enough 
to  allow  of  the  movement  of  the  chain  belt,  which  having  taken  place,  they  should  be  depressed  so  as 
to  hold  the  work  down  until  the  stitch  hook  has  fairly  hooked  under  or  taken  up  the  stitch  on  the  nee- 
dle, against  which  it  may  be  acting. 

The  presser  should  next  be  elevated  with  the  stitch  hook,  so  as  to  allow  the  work  -to  rise.  While  the 
stitch  hook  is  casting  the  stitch  or  loop  over  the  hook  of  the  needle,  the  presser  should  be  stationary,  but 
as  soon  as  this  has  been  effected,  and  the  hook  has  withdrawn  itself  from  the  stitch,  the  presser  should 
be  depressed  so  as  to  force  the  work  down  to  the  roots  of  the  needles.  Such  movements  may  be  attained 
by  any  suitable  machinery  applied  to  the  rocker  shaft  of  the  presser,  such  mechanism  constituting  no 
part  of  my  invention; — but  that  which  I employ  may  be  thus  described: — Fig.  2476  is  a front  elevation 
of  the  machine  as  it  appears  when  its  front  plate  p',  and  the  endless  chain  A,  are  removed  from  the  re- 


KNIVES. 


16  j 


mainder  of  the  mechanism.  Fig.  2470  is  a vertical  cross  section  of  the  machine;  the  same  being  ta- 
ken looking  towards  the  left  through  the  cam,  which  operates  the  presser. 

From  the  shaft  m of  the  presser,  an  arm  q'  extends  towards  the  front,  and  is  joined  at  its  outer  end 
to  an  upright  and  bent  bar  r',  whose  upper  end  is  forced  upwards  against  the  cam  s',  by  means  of  a 
spring  t' , one  end  of  which  is  attached  to  the  bar  r , and  the  other  to  the  frame  or  box  B,  as  seen  in 
figs.  2476  and  2470.  The  cam  s'  is  fixed  on  the  driving  shaft,  and  during  its  revolution,  it,  in  conjunc- 
tion with  the  spring  t' , produces  the  rocker  motions  of  the  shaft  m , such  as  will  cause  the  presser  to  op- 
erate in  the  manner  required. 

Directly  after  each  movement  of  the  chain  belt,  the  yarn  guide  or  director  D,  should  be  moved  for- 
ward beyond  the  back  needles,  so  as  to  lay  the  yarn  on  that  needle  on  which  the  new  stitch  is  to  be 
made.  After  the  stitch  lias  been  formed,  the  yarn  guide  should  be  retrograded  and  carried  back  of  the 
needles,  in  order  that  the  chain  belt  may  perform  its  next  movement  without  obstruction.  The  mechan- 
ism for  operating  the  yarn  guide  or  director  D,  consists  of  a cam  u',  fixed  on  a driving  shaft,  a slide 
rod  or  bar  v',  (whose  lower  end  is  jointed  or  hinged  to  the  outer  end  of  an  arm  w',  extended  from  the 
shaft  f)  and  a spring  x',  which  forces  the  bar  v'  up  against  the  cam — the  said  cam  being  shown  in  fig. 
2470  by  dotted  lines. 

The  machinery  for  moving  the  chain  belt  forms  no  part  of  my  invention,  except  so  far  as  the  arrange- 
ment of  the  gear  or  pinion  B and  the  joints  x x x,  &c.,  of  the  chain  belt  is  concerned.  On  the  main 
driving  shaft,  there  is  another  cam  a2,  which  operates  against  the  upper  end  of  a lever  b 2,  which  turns 
upon  a fulcrum  e2.  See  fig.  2478,  which  is  a transverse  section  of  the  machine,  taken  through  such  cam, 
and  looking  towards  the  right,  serves  to  show  the  machinery  actuated  by  it.  A spring  d2,  is  used  to 
draw  the  upper  end  of  the  lever  against  the  cam.  The  lower  end  of  the  lever  is  bent  at  right  angles, 
or  horizontally,  and  has  two  impelling  pawls  e2y2,  jointed  to  it,  and  made  to  extend  forwards,  and  re- 
spectively to  act  in  concert  with  two  ratchet  wheels  y2  7i2,  fixed  upon  the  upright  shaft  P,  of  the  pinion  b 
which  works  the  chain  belt.  These  ratchet  wheels  and  pawls  are  seen  in  fig.  2477  and  2479,  the  latter 
figure  being  a horizontal  section  of  the  machine,  taken  just  above  the  pawls,  and  so  as  to  exhibit  them. 
The  teeth  of  one  of  the  ratchet  wheels  are  arranged  in  a direction  opposite  to  those  of  the  other,  in  or- 
der that  when  its  pawl  is  in  action  with  it,  a motion  of  the  shaft  *2,  may  be  produced  in  a direction  the 
reverse  of  that  effected  by  the  movements  of  the  other  pawl  and  its  wheel.  By  the  movement  of  either 
pawl  an  intermittent  rotary  motion  of  the  shaft  P will  take  place. 

The  two  pawls  pass  respectively  through  slots  TP  P,  made  in  a vertical  stationary  plate  m ? ; (see  fig. 
2480,)  which  is  a front  view  of  the  plate  rrP,  and  the  shifting  contrivance  attached  to  it.  Such  shifting 
contrivance  is  a slide  n 3,  which  is  capable  of  being  moved  longitudinally,  and  has  a projection  o2  extend- 
ing down  between  the  two  pawls.  When  the  slide  is  moved  in  one  direction,  it  bears  against  one  of  the 
pawls,  and  throws  it  out  of  action  upon  its  ratchet  wheel,  and  at  the  same  time,  in  consequence  of  the 
two  pawls  being  connected  by  a spring  p2,  it  draws  the  other  pawl  against  the  other  ratchet  wheel, 
thereby  creating  a reverse  motion  of  the  shaft  P.  The  object  of  the  two  pawls  is  to  enable  the  move- 
ment of  the  endless  belt  A to  be  reversed,  so  as  to  cause  the  knitting  to  be  produced  in  an  opposite  di- 
rection ; one  pawl,  however,  is  sufficient  to  produce  the  movement  necessary  to  knit  in  one  direction. 

The  shaft  f which  carries  the  yarn  director  D,  is  made  to  slide  longitudinally  in  its  bearings,  and  is 
connected  into  the  slide  ri1,  by  a lever  <f,  rvhich  turns  upon  a fulcrum  r2,  and  has  its  ends  inserted  in 
notches  made  in  the  slide  rP,  and  the  shaft  f and  this  so  that  the  movement  of  the  slide  in  one  direction 
may  create  a sliding  movement  of  the  shaft,  sufficient  to  move  the  yam  guide  into  the  proper  position 
to  commence  the  knitting  in  the  reverse  direction. 

The  shifting  contrivance  may  be  operated  by  the  attendant,  or  by  any  other  proper  means.  Some 
parts  of  other  mechanism  which  I append  or  attach  to  the  above  described  machine,  and  for  pur-poses 
not  necessary  to  mention,  may  be  seen  in  the  drawings.  As  such  mechanism  forms  no  part  of  my  in- 
vention, I make  no  further  reference  to  it  or  description  of  it. 

On  the  driving  shaft  there  may  be  a fly  wheel  P,  from  which  a crank  s2  may  extend,  and  for  the  pur- 
pose of  enabling  a person  to  put  the  shaft  in  motion — or  the  said  shaft  may  be  revolved  by  a pulley  ap- 
plied to  it,  and  made  to  receive  an  endless  belt  from  any  suitable  driving  drum. 

By  having  the  endless  chain  of  needles  made  and  operated  in  the  above  described  manner,  the  chain 
extends  around  the  work,  instead  of  the  work  encompassing  the  chain,  as  it  does  in  other  well-known 
knitting  machines.  My  improved  arrangement  and  disposition  of  the  work  exposes  all  the  joints  of  the 
links  of  the  chain  so  that  a workman  or  attendant  can  readily  remove  one  or  more  of  the  needles,  with 
much  greater  convenience  than  can  be  done  on  the  said  well-known  machines,  as  in  the  latter  he  would 
be  obliged  to  wholly  or  partially  remove  the  work  from  the  needles  in  order  to  accomplish  the  addition  or 
subtraction  of  one  or  more  of  the  needles,  such  addition  or  subtraction  being  for  the  purpose  of  enabling 
him  to  “ widen  ” or  '•'•narrow’"  the  work.  My  improvement  affords  great  advantages  in  knitting  a heel, 
as  the  same  can  be  effected  in  a much  more  perfect  manner,  without  that  strain  upon  the  work  and  nee- 
dles that  is  incident  to  the  old  and  well-known  machines, 

KNIVES,  ( including  Forks)  Knives  are  well-known  instruments,  made  for  cutting  a great  variety 
of  substances,  and  adapted  by  differences  in  form  to  various  uses  ; but  the  two  principal  sorts  may  be 
classed  under  the  terms  of  pocket-knives  and  table-knives,  with  then-  accompaniments,  forks. 

In  the  making  of  pocket-knife  blades,  one  workman  and  a boy  are  generally  employed  ; the  boy 
attends  to  the  heats,  (that  is,  to  the  rods:  of  steel  in  the  fire,)  which  he  successively  hands  to  the  forger, 
and  takes  back  the  rod  from  which  the  last  blade  was  formed.  One  heat  is  required  to  fashion  the 
blade,  and  a second  to  form  the  tang,  by  which  it  is  fastened  into  the  handle.  The  skill  of  the  forger 
is  displayed  in  forming  it  so  perfectly  by  his  hammer,  as  to  require  but  very  little  to  be  filed  or  ground 
off  in  the  subsequent  operations.  The  springs  for  the  back  of  the  knife,  and  the  scales  which  form  the 
rough  metal  under-handle,  and  to  which  the  other  pieces  are  riveted,  are  made  by  a distinct  class  ol 
workmen.  In  the  forging  of  table-knife  blades,  and  other  blades  of  a similar  or  greater  size,  the  forger 
has  an  assistant,  who,  with  a large  hammer,  strikes  alternately  with  him ; and  the  hammering  of  all 

. Vol.  ii.— n 


162 


KNIFE-SHARPENERS. 


blades  is  continued  after  tlie  steel  has  ceased  to  be  soft,  in  order  to  condense  the  metal  and  render  it 
very  smooth  and  firm.  Table-knife  blades  are  usually  made  with  iron  backs,  which  are  welded  to  the 
steel  by  a subsequent  forging,  to  that  of  forming  the  cutting  edge ; the  thick  piece  that  joins  the  han- 
dle, called  the  shoulder  or  bolster,  as  well  as  the  tang  that  goes  through  the  handle,  is  forged  out  of  the 
iron  immediately  after  the  welding  of  the  steel  blade : dies  and  swages  being  employed  to  perfect  and 
accelerate  the  shaping  of  these  parts.  When  the  forging  is  completed,  the  blades  undergo  the  processes 
of  hardening  and  tempering,  explained  in  article  Tempering.  The  blades  are  then  ground  upon  a wet 
stone,  about  4 feet  in  diameter,  and  9 inches  wide,  which  roughs  out  the  work ; they  are  subsequently 
finished  or  whitened,  as  it  is  termed,  upon  a finer  dry  stone;  and  the  shoulders  or  bolsters  are  ground 
upon  a narrow  stone,  about  3 feet  in  diameter,  which  completes  the  grinding.  The  next  process  is  that 
of  glazing  the  blades,  which  is  effected  upon  a wooden  wheel,  made  up  of  solid  segments,  well  fitted 
and  secured  together,  and  with  the  ends  of  the  fibres  of  the  wood  presented  to  the  periphery  of  the 
circle ; over  this  is  extended  a piece  of  leather,  which  is  charged  with  emery  or  other  powders,  adapted 
to  the  finish  or  nature  of  the  work  required. 

The  cheaper  kind  of  forks  are  made  by  casting  them  from  malleable  pig-metal,  sometimes  denom- 
inated “ run-steel ;”  and  some  of  these,  which  are  well  annealed  and  worked  under  the  hammer,  turn  out 
very  serviceable  and  good.  Those  made  of  wrought-metal,  were  formerly  either  forged,  and  the  prongs 
drawn  out  by  the  hammer,  and  welded  together,  or  they  were  forged  into  one  solid  piece,  and  the 
spaces  between  them  formed  by  cutting  away  the  metal.  These  processes,  however,  were  tedious  and 
expensive,  and  a great  improvement  in  their  manufacture  has  been  introduced.  The  tang,  shoulder, 
and  a thick,  flat  piece,  called  the  blade,  are  forged,  and  the  blade  is  then  submitted  to  the  action  of  a 
pair  of  dies,  contained  in  a powerful  fly  or  stamping-press;  the  dies  being  so  formed  as  to  force  or  cut 
out  the  superfluous  portion  of  the  metal  and  raise  the  curved  swelled  portions  at  the  junction  of  the 
prongs,  termed  the  bosom.  The  forks  after  this  operation  are  filed  up,  ground,  glazed,  and  burnished, 
when  they  are  ready  for  hafting,  which  is  a distinct  business. 

The  instruments  required  for  hafting  knives  and  forks  are  few  and  simple.  The  principal  are,  a small 
polishing-wheel  and  treddle,  mounted  upon  a stand,  a bench  vice,  and  a kind  of  hand  vice  to  fix  in  the 
bench  vice,  termed  a snap-dragon ; it  has  a pair  of  long  projecting  jaws,  adapted  to  hold  a piece  of 
metal  or  other  substance,  with  the  flat  side  uppermost,  in  order  to  be  filed  or  otherwise  worked ; a few 
files,  drills,  drill-box,  and  breast-plate,  burnishers  and  buff's,  emery,  rotten-stone,  <fcc.  The  substances 
used  for  covering  the  handles  are  almost  infinite  ; the  chief  are  bone,  horn,  ivory,  tortoise-shell,  and  wood 
of  every  kind.  The  several  pieces  of  the  handle  being  filed  to  the  shape  intended,  holes  are  drilled 
through  them  for  the  pins  by  which  they  are  afterwards  riveted  together.  The  pinning  is  at  first 
loosely  done,  until  the  blades,  springs,  and  all  the  parts  are  well  adjusted  and  fit  closely ; they  are  then 
firmly  riveted  together.  The  handles  are  afterwards  scraped  and  then  polished,  by  means  of  buffing, 
on  the  wheel. 

KNIFE-SHARPENERS.  This  term  has  been  2469. 

given  to  a variety  of  convenient  modern  instru- 
ments, especially  adapted  to  the  sharpening  of 
knives  at  table,  but  particularly  carvers,  and  are 
intended  as  substitutes  for  the  coipmon ‘steel.  For 
these  instruments  several  patents  have  been  ob- 
tained, and  a considerable  manufacture  of  them  has 
been  established. 

Filton’s  patent  sharpener,  represented  in  Fig. 

2469,  consists  of  two  horizontal  rollers,  placed  par- 
allel to  each  other,  which  revolve  freely  upon  their 
axes,  (represented  by  the  two  black  dots ;)  at  uni- 
form distances,  there  are  fixed  upon  each  roller 
narrow  cylinders  or  rings  of  hard  steel,  the  edges  of  which  are  cut  into  fine  teeth,  and  thus  form  circular 
files ; the  edges  of  the  files  in  the  opposite  rollers  overlap  each  other  a little,  so  that  when  a knife  is 
drawn  longitudinally  between  them,  the  edge  of  the  knife  is  acted  upon  on  both  of  its  sides  at  once. 
The  rollers  turn  round  with  the  slightest  impulse ; consequently,  they  wear  uniformly,  and  will  last  a 
considerable  time.  A good  edge  is  given  to  a knife  by  just  drawing  it  from  heel  to  point  two  or  three 
times  between  the  rollers  ; and  thus  obviates  the  necessity  of  imitating  the  skill  exercised  by  a butcher 
upon  his  steel. 

Westbfs  knife-sharpener,  which  was  patented  in  1828,  is  an  ingenious  instrument;  an  immense  quan- 
tity of  them  have  been  sold,  and  it  is  said,  have  been  the  means  of  greatly  enriching  the  proprietor  of 
the  patent.  Fig.  2470  exhibits  an  end  elevation  of  the  instrument,  and  Fig.  2471  a side  elevation  of  the 
bars,  with  a section  of  the  boxes  a and  h,  to  show  the  interior.  The  same  letters  in  each  figure  have 
reference  to  similar  parts ; a is  a small  oblong  box,  surmounted  by  a smaller  box  h ; in  the  top  of  the 
latter  there  is  a slit  made  throughout  its  length,  and  of  sufficient  width  to  receive  the  square  steel 
bars  c c.  The  box  a has  two  similar  slits.  The  surfaces  of  the  bars  are  draw-filed ; they  pass  through 
the  slit  in  h,  and  alternately  through  both  slits  in  a,  so  as  to  cross  each  other,  as  shown  in  Fig.  2470. 
The  lower  ends  of  these  bars  are  supported  upon  a plate  of  metal  d,  which  can  be  elevated,  so  as  to 
bring  a different  portion  of  the  bars  into  operation,  by  means  of  the  screw  underneath ; ff  are  two 
screws  passing  through  the  holes  in  d,  to  preserve  its  parallel  motion,  and  likewise  to  support  the  bottom 
of  the  box ; h is  a tightening  screw  to  steady  the  bars  c c. 

The  mode  of  operating  with  this  instrument  is  merely  to  place  the  edge  of  the  knife  upon  the  bars, 
so  as  to  bisect  the  angle  formed  by  them,  and  then  draw  the  knife  backward  and  forward.  As  the 
surfaces  of  the  bars  wear  away,  different  sides  can  be  presented,  or  they  can  be  shifted  from  end  to 
end,  so  as  to  present  fresh  surfaces  to  the  knife. 

Church's  paiont  knife-sharpener  consists  of  two  very  flat  truncated  cones,  fixed  with  their  smaller 


LAC. 


163 


surfaces  together,  and  with  several  rectangular  projections  in  the  one,  fitting  into  similar  cavities  in  the 
other.  The  conical  surfaces  of  both  pieces  are  serrated  with  a series  of  very  fine  teeth  extending  an- 
gularly towards  their  centres ; these  are  placed  upon  the  shank  of  the  fork,  between  the  shoulder  and 
the  handle,  with  which  they  correspond  in  diameter  so  nearly  as  to  constitute  an  ornamental  finish  to 
the  small  end  of  the  handle.  In  the  position  and  size  of  these  consist  the  principal  merit  of  the  sharp- 
ener. When  used  for  sharpening  scythes,  or  other  large  cutting  instruments,  the  conical  pieces  are 
made  larger,  and  fitted  on  an  axis  between  two  prongs  of  a forked  apparatus,  with  an  appropriate 
handle. 

2471.  2470. 


Westhy's  second  patent. — The  extraordinary  success  attendant  upon  Mr.  Westby’s  contrivance  for 
sharpening  table-knives  induced  him  to  figure  a second  time  as  a patentee,  “ for  certain  improved  ap- 
paratus to  be  used  for  the  purpose  of  whetting  or  sharpening  the  edges  of  the  blades  of  penknives , 
razors,  and  other  cutting  instruments.”  The  first  improvement  mentioned  in  the  specification  consists 
in  the  application  to  a hone,  or  oil-stone,  of  a guide  to  keep  the  edge  of  the  razor,  or  other  cutting  in- 
strument, at  the  same  angle  with  respect  to  the  surface  of  the  hone,  during  the  operation  of  whetting. 
This  is  effected  in  two  ways : first,  by  placing  over  the  hone  a plate  of  metal  extending  its  whole  length, 
and  adjustable,  at  any  required  distance  parallel  to  its  surface,  by  set-screws ; now,  in  the  operation  ot 
sharpening,  the  back  of  the  instrument  is  kept  resting  upon  the  guide-plate,  while  the  edge  is  applied 
to  the  hone.  The  second  method  consists  in  the  application  of  two  hones  placed  in  an  erect  position, 
with  a space  between  them  for  the  razor,  which  is  to  be  fixed  by  screws  into  a small  horizontal  frame, 
made  to  slide  upon  a circular  rod,  so  that  the  edge  can  be  applied  alternately  to  the  hones ; these  can 
be  elevated  and  depressed  at  pleasure,  so  that,  their  surfaces  may  be  uniformly  worn  while  in  use.  The 
patentee  also  mentions  in  his  specification  a method  of  attaching  to  his  hone  a leather  strap  which  is 
made  double,  and  kept  stretched  by  adjusting  screws  attached  to  the  frame  of  the  hone,  or  else  to  the 
end  of  a rod  extending  lengthwise  between  the  two  folds  of  leather.  This  last  contrivance  does  not 
appear  to  us  to  be  scientifically  adapted  to  the  object  in  view,  as  the  pressure  of  the  edge  of  the  instru- 
ment upon  a strap  of  leather  only  supported  at  its  extremities,  must  produce  a tendency  in  the  leather 
to  wrap  round  the  acute  angle  of  the  edge  of  the  instrument,  and  render  it  obtuse. 


LABURNUM  WOOD  is  in  use  among  turners  • pulleys  and  blocks  are  made  of  it.  Being  a hard 
and  compact  wood,  it  is  capable  of  endurance  when  exposed  to  the  weather,  and  for  various  purposes 
is  extremely  valuable.  When  perfectly  dry,  a cubic  foot  weighs  52  lbs.  11  oz. 

LAC.  A resinous  substance,  the  product  of  an  insect  found  on  several  different  kinds  of  trees  in  the 
East  Indies.  These  insects  pierce  the  small  branches  of  the  trees  on  which  they  feed,  and  the  juice 
that  exudes  from  the  wounds  is  formed  by  them  into  a kind  of  cells  for  their  eggs.  Lac  is  imported 
into  this  country  adhering  to  the  branches  in  small  transparent  grains,  or  in  semi-transparent  flat  cakes. 
The  first,  encrusting  the  branches,  is  called  stick-lac ; the  second  are  the  grains  picked  off  the  branches, 
and  called  seed-lac  ; the  third  is  that  which  has  undergone  a simple  purification,  as  we  shall  presently 
notice.  There  is  a fourth,  called  lump-lac,  made  by  melting  the  seed-lac,  and  forming  it  into  lumps. 
To  purify  the  lac  for  use  the  natives  of  India  put  it  into  long  canvas  bags,  which  they  heat  over  a 
charcoal  fire  until  the  resin  melts ; a portion  of  the  lac  then  exudes  through  the  bags,  which  are  subse- 
quently twisted,  or  wrung  by  means  of  cross  sticks  at  the  ends  of  the  bags,  the  surface  of  the  latter 
being  scraped  at  the  same  time  to  accelerate  the  process.  The  chief  consumption  of  lac  in  this  country 
is  in  the  manufacture  of  sealing-wax  and  varnishes.  It  has  been  a great  desideratum  among  artists  to 
render  shell-la.c  colorless,  as,  with  the  exception  of  its  dark-brown  hue,  it  possesses  all  the  properties 
essential  to  a good  spirit  varnish  in  a higher  degree  than  any  other  known  resin.  The  process  given 
by  Dr.  Hare  leaves  nothing  to  desire,  excepting  on  the  score  of  economy.  Were  the  oxymuriate  of 
potash  to  be  manufactured  in  the  large  wav,  the  two  processes,  that  of  making  the  salt  and  of  bleach- 
ing the  resin,  might  be  advantageously  combined.  “ Dissolve  in  an  iron  kettle  one  part  of  pearlash  in 


164 


LACTOMETER. 


about  eight  parts  of  water  ; add  one  part  of  seed  or  shell  lac,  and  heat  the  whole  to  ebullition  ; when 
the  lac  is  dissolved,  cool  the  solution,  and  impregnate  it  with  chloriue  till  the  lac  is  all  precipitated. 
The  precipitate  is  white,  but  its  color  is  deepened  by  washing  and  consolidation  ; dissolved  in  alcohol, 
lac  bleached  by  the  process  above  mentioned  yields  a varnish  which  is  as  free  from  color  as  any  copal 
varnish.” 

The  following  is  Mr.  Field’s  process : Six  ounces  of  shell-lac,  coarsely  powdered,  are  to  be  dissolved 
by  gentle  heat  in  a pint  of  spirits  of  wine  ; to  this  is  to  be  added  a bleaching  liquor,  made  by  dissolving 
purified  carbonate  of  potash,  and  then  impregnating  it  with  chlorine  gas  till  the  silica  precipitates  and 
the  solution  becomes  slightly  colored.  Of  this  bleaching  liquor  add  one  or  two  ounces  to  the  spirituous 
solution  of  lac,  and  stir  the  whole  well  together  ; effervescence  takes  place,  and  when  this  ceases,  add 
more  to  the  bleaching  liquor,  and  thus  proceed  till  the  color  of  the  mixture  has  become  pale.  A second 
bleaching  liquor  is  now  to  be  added,  made  by  diluting  muriatic  acid  with  thrice  its  bulk  of  water,  and 
dropping  into  it  pulverized  red  lead,  till  the  last  added  portions  do  not  become  white.  Of  this  acid 
bleaching  liquor,  small  quantities  at  a time  are  to  be  added  to  the  half-bleached  lac  solution,  allowing 
the  effervescence,  which  takes  place  on  each  addition,  to  cease  before  a fresh  portion  is  poured  in.  This 
is  to  be  continued  until  the  lac,  now  white,  separates  from  the  liquor.  The  supernatant  fluid  is  now  to 
be  poured  away,  and  the  lac  is  to  be  well  washed  in  repeated  waters,  and  finally  wrung  as  dry  as  pos- 
sible in  a cloth.  The  lac  obtained  in  the  foregoing  process  is  to  be  dissolved  in  a jjint  of  alcohol,  more 
or  less,  according  to  the  required  strength  of  the  varnish  ; and  after  standing  for  some  time  in  a gentle 
heat,  the  clear  liquor,  which  is  the  varnish,  is  to  be  poured  off  from  the  sediment. 

Mr.  Luning’s  process  is  as  follows : — Dissolve  five  ounces  of  shell-lac  in  a quart  of  rectified  spirits  of 
wine  ; boil  for  a few  minutes  with  ten  ounces  of  well-burnt  and  recently  heated  animal  charcoal,  when 
a small  quantity  of  the  solution  should  be  drawn  off  and  filtered  : if  not  colorless,  a little  more  charcoal 
must  be  added.  When  all  color  is  removed,  press  the  liquor  through  silk,  as  linen  absorbs  more  varnish, 
and  afterwards  filter  it  through  fine  blotting-paper.  In  cases  where  the  wax  found  combined  with  the 
lac  is  objectionable,  filter  cold  ; if  the  wax  be  not  injurious,  filter  while  hot.  This  kind  of  varnish 
should  be  used  in  a temperature  of  not  less  than  60°  F. ; it  dries  in  a few  minutes,  and  is  not  after- 
wards liable  to  chill  or  bloom  ; it  is  therefore  particularly  applicable  to  drawings  and  prints  which  have 
been  sized,  and  may  be  advantageously  used  upon  oil  pointings  which  have  been  painted  a sufficient 
time,  as  it  bears  out  color  with  the  purest  effect.  This  quality  prevents  it  from  obscuring  gilding,  and 
renders  it  a valuable  leather  varnish  to  the  bookbinder,  to  whose  use  it  has  already  been  applied  with 
happy  effect,  as  it  does  not  yield  to  the  warmth  of  the  hand,  and  resists  damps,  which  subject  bindings 
to  mildew.  Its  useful  applications  are  very  numerous,  indeed,  to  all  the  purposes  of  the  best  hard 
spirit  varnishes ; it  is  to  be  used  under  the  same  conditions,  and  with  the  same  management.  Common 
seed-lac  varnish  is  usually  made  by  digesting  eight  ounces  of  the  bright,  clear  grained  lac  in  a quart  ot 
spirits  of  wine,  in  a wide-mouthed  bottle,  putting  it  in  a warm  place  for  two  or  three  days,  and  occa- 
sionally shaking  it.  When  dissolved  it  may  be  strained  through  flannel  into  another  bottle  for  use.  In 
India,  lac  is  fashioned  into  rings,  beads,  and  other  trinkets.  Its  coloring  matter,  which  is  soluble  in 
water,  is  employed  as  a dye.  The  resinous  portion  is  mixed  with  about  three  times  its  weight  of  finely 
powdered  sand,  to  form  polishing  stones.  The  lapidaries  mix  powder  of  corundum  with  it  in  a similar 
manner. 

LACE.  A delicate  kind  of  net-work,  composed  of  silk,  flax,  or  cotton  threads,  twisted  or  plaited 
together.  See  Bobbin-work. 

LACQUERING  is  the  application  of  transparent  or  colored  varnishes  to  metals,  to  prevent  their 
becoming  tarnished,  or  to  give  them  a more  agreeable  color.  The  basis  of  them  is  properly  the  lac 
described  in  the  preceding  article  ; but  other  varnishes  made  by  solutions  of  other  resins,  and  colored 
yellow,  also  obtain  the  name  of  lacquer.  Strictly  speaking,  lacquer  is  a solution  of  lac  in  alcohol, 
to  which  is  added  any  coloring  matter  that  may  be  required  to  produce  the  desired  tint ; but  the 
recipes  that  have  been  published  in  various  scientific  journals  contain  apparently  a great  many  useless 
articles. 


| oz.  of  terra  merita, 

2 oz.  of  oriental  saffron, 

3 oz.  of  pounded  glass, 

and 

20  oz.  of  pure  alcohol. 


Lacquer  for  Brass. 

oz.  of  gum  guttre, 

2 oz.  of  gum  sandarac, 

2 oz.  of  gum  elemi, 

1 oz.  of  dragon’s  blood,  of  the  best  quality, 

1 oz.  of  seed-lac, 

Before,  however,  the  reader  ventures  to  meddle  with  so  formidable  a list  of  ingredients  as  the  fore- 
going, we  would  recommend  him  to  make  trial  of  the  following  more  simple  compound: — Take  8 oz. 
of  spirits  of  wine,  and  1 oz.  of  annatto,  well  bruised ; mix  these  in  a bottle  by  themselves ; then  take 
1 oz.  of  gamboge,  and  mix  it  in  like  manner  with  the  same  quantity  of  spirits.  Take  seed-lac  varnish, 
(described  under  the  previous  article  Lac,)  what  quantity  you  please,  and  color  it  to  your  mind  with 
the  above  mixtures.  If  it  be  too  yellow,  add  a little  from  the  annatto  bottle  ; if  it  be  too  red,  add  a 
little  from  the  gamboge  bottle  ; if  the  color  be  too  deep,  add  a little  spirits  of  wine.  In  this  manner 
you  may  color  brass  of  any  desired  tint : the  articles  to  be  lacquered  may  be  gently  heated  over  a 
charcoal  fire,  and  then  be  either  dipped  into  the  lacquer,  or  the  lacquer  may  be  evenly  spread  over 
them  with  a brush. 

LACTOMETER.  An  instrument  for  the  purpose  of  ascertaining  the  different  qualities  of  milk  from 
its  specific  gravity  compared  with  water.  On  this  subject  Dr.  Ure  observes,  that  it  is  not  possible  to 
infer  the  quality  of  milk  from  the  indications  merely  of  a specific  gravity  instrument,  because  both 
cream  and  water  affect  the  specific  gravity  of  milk  alike.  “We  must  first  use  as  a lactometer  a gradu- 
ated glass  tube,  in  which  we  note  the  thickness  of  the  stratum  of  cream  afforded,  after  a proper  inter 
val,  from  a determinate  column  of  new  milk ; we  then  apply  to  the  skimmed  milk  a hydrometric 


LAMPS. 


165 


Thus  the  combination  of 


2472. 


instrument,  from  which  we  learn  the  relative  proportions  of  curd  and  whey, 
the  two  instruments  furnishes  a tolerably  exact  lactometer.” 

Frye's  lactometer. — Fig.  2472,  for  testing  the  quality  of  milk;  made  under  the 
direction  of  the  Board  of  Agriculture  of  the  American  Institute,  in  the  city  of  New 
York,  who  have  strongly  recommended  it  to  public  patronage. 

This  instrument  was  invented  for  the  purpose  of  ascertaining  the  density,  and  fixing  ^ ^ ^ 

the  standard  weight,  of  pure  unadulterated  milk,  as  it  is  produced  in  the  best  grazing  ^j/water."4 
districts  in  the  country,  and  with  a view  of  detecting  the  frauds  practised  by  adulter- 
ating milk  with  water,  so  often  complained  of  by  the  consumer,  in  large  towns  and  milk  and 
cities  throughout  the  Union.  ^ water' 

Directions  for  using  the  instrument. — Fill  the  tin  tube,  which  accompanies  the  in-  % milk  and 
strument,  with  the  milk  to  be  tested  at  a temperature  of  about  60  degrees,  and  sus-  ^ ",Ilter' 
pend  the  lactometer  in  the  milk,  and  if  the  milk  is  proof,  the  instrument  will  sink  to  p ^ 
the  degree  marked  100  on  the  scale,  or  p,  showing  that  the  milk  is  at  par  ; but  if  the  Co.  niiTk/e 
milk  has  been  adulterated  with  water,  or  has  been  taken  from  cows  that  have  been 
fed  on  slops  from  breweries,  and  kept  confined  in  stables  in  warm  weather,  the  instrument 
will,  in  all  such  cases,  sink  below  par,  and  show  the  per  centage  of  adulteration,  which,  in 
some  instances,  will  be  25  per  cent,  below  par ; but  if  the  milk  is  superior,  the  instrument 
will  rise  above  p,  and  show  the  per  centage  above  par,  which,  in  some  instances,  will  be  10 
per  cent.  Each  division  on  the  scale  is  5 per  cent. 

Any  person  can  test  the  correctness  of  the  lactometer  by  mixing  water  with  pure  milk, 
and  note  the  per  centage  of  water  which  they  use,  and  suspend  the  instrument  in  the  mix- 
ture, and  it  will  give  the  proportion  of  water  added. 

To  farmers  the  instrument  has  proved  to  be  very  valuable,  as  a ready  means  of  testing  the  relative 
quality  of  their  cows,  by  inspecting  their  milk,  and  also  showing  the  effects  produced  by  a change  ol 
the  animals’  food,  as  its  quality  will  change  the  density  of  the  milk. 

L ADDER.  A portable  frame,  containing  steps  for  the  feet.  There  are  various  kinds,  most  of  which 
are  too  familiar  to  the  readers  of  this  work  to  need  description.  Ladders  are  very  advantageously  em- 
ployed in  the  raising  of  weights,  by  the  addition  of  a pulley-wheel  at  the  top,  or  suspended  over  them ; 
passing  over  this  pulley  is  a rope,  to  one  end  of  which  is  attached  the  article  to  be  raised. 

Ladders  are  the  universal  means  of  ascent  and  descent  in  mines,  the  distance  between  the  levels 
being  generally  60  feet ; a single  ladder  in  former  times  reached  from  one  to  the  other,  but  the  most 
usual  length  at  present  is  from  4 to  5 fathoms.  In  the  perpendicular  shafts  the  inclination  is  commonly 
such  that  the  ladder  may  nearly  traverse  the  breadth  of  the  shaft;  from  18  to  21  inches  in  the  fathom 
is  the  inclination  which  experience  has  determined  to  be  the  best  calculated  to  facilitate  the  progress  ot 
the  miner,  being  that  which  enables  him  to  stand  upright  on  the  ladder  with  the  leg  clear  from  the 
stave  above,  so  that  the  effort  is  divided  between  the  upper  and  lower  extremities.  The  distance 
between  the  staves  is  generally  12  inches ; in  some  old  ladders  they  were  14  inches  apart,  but  10  inches 
is  found  the  best  for  facilitating  the  climbing,  by  which  one-fourth  of  the  labor  is  estimated  to  be  saved. 
The  staves  are  of  wood,  though  iron  is  in  some  instances  preferred ; in  others  it  becomes  slippery  and 
rough  from  the  corrosive  action  of  water  impregnated  with  copper,  &c.  Each  ladder  usually  terminates 
on  a sollar  or  platform,  which  leads  to  that  below,  which  is  generally  placed  parallel  to  that  above. 

LAMPS.  The  whole  series  of  improvements  made  in  lamps  up  to  the  present  time,  must  be  con- 
sidered as  the  reward  of  no  inconsiderable  expenditure  of  ingenuity  in  the  inventors  themselves,  and  of 
a clear  perception  of  the  working  of  physical  laws,  enabling  them  not  only  to  overcome  the  difficulties 
of  the  subject  itself,  but  also  to  adapt  the  new  contrivances  to  general  use,  and  to  the  management  of 
the  unskilled.  A general  view  of  this  interesting  subject  will  place  clearly  before  us  the  essential  points 
which  it  has  been  the  object  of  the  inventors  to  attain,  sometimes  singly,  sometimes  several  at  once. 
They  are  these : 


(а)  To  select  such  a form  (section)  of  wick  that  the  quantity  of  decomposed  oil,  and  the  simultaneous 
supply  of  air,  may  stand  in  such  relation  to  each  other,  that  the  hydrogen  and  carbon  may  be  con- 
secutively consumed,  and  consequently  no  smoke  produced. 

(б)  To  make  the  distance  between  the  burning  part  of  the  wick  and  the  surface  of  the  oil  as  un- 
changeable as  possible,  in  order  that  as  much  oil  may  be  drawn  up  at  last  as  at  first. 

(c)  To  place  the  reservoir  of  oil  in  such  a position  that  the  shadow  shall  occasion  little  or  no  incon- 
venience. The  use  made  of  the  lamp  must,  of  course,  here  regulate  its  form ; it  is  not,  however,  always 
a fault  when  these  do  not  exactly  correspond.  Thus  the  shadow  thrown  bv  wall  lamps  is  unimportant, 
as  the  lamp  itself  covers  the  shadow : in  like  manner,  the  shadow  of  a common  study  lamp  cannot  be 
considered  as  a fault/being  used  only  by  one  person,  although  its  prevention  is  always  an  improve- 
ment. 


(d)  To  throw  the  light,  radiating  from  the  flame,  by  means  of  collectors  and  reflectors,  from  those 
parts  where  it  is  of  little  service,  in  the  direction  where  it  is  most  required. 

The  requisitions  stated  under  a have  been  complied  with  in  two  ways  : on  the  one  hand,  by  controlling 
the  access  of  air,  (the  quantity  of  air ;)  on  the  other,  by  regulating  the  supply  of  oil,  and  often  by  both 
at  the  same  time.  They  have  reference  to  that  part  of  the  lamp  called  the  burner. 

The  scrupulous  enumeration  of  the  manifold  modifications,  and,  for  the  greater  part,  unimportant 
improvements  in  lamps,  which  have  been  presented  to  the  public  during  the  last  twenty  or  thirty  years, 
would  be  but  a tedious  labor ; and  in  the  following  observations  we  shall  only  lay  before  the  reader 
those  inventions  which  appear  to  indicate  important  progress,  or  form  epochs  in  the  history  of  this 
subject. 

Worms  lamp. — The  Worms’ lamp,  shown  in  Figs.  2473  and  2474,  is  well  known,  and  characterized 
by  the  shape  of  the  wick  t.  The  fibres  of  the  wick,  instead  of  being  collected  into  a round  bundle,  are 
placed  in  small  bundles  side  by  side,  forming  together  a flat  ribbon.  The  effect  of  this  is  obvious.  The 


LAMPS. 


ieo 


edges  of  the  flame  are  at 'no  point  so  distant  that  a nucleus  can  form  in  the  centre,  which,  from  want  of 
air,  will  burn  incompletely  and  smoke.  The  flat  socket  c serves  to  hold  the  wick ; it  is  soldered  in 
the  diameter  of  the  wide  ring  d,  which,  with  its  recurved  edge,  rests  upon  that  of  the  glass  globe  a a. 
An  important  addition  to  its  flat  form  is  its  movability , and  this  is  common  to  all  the  following  kinds 
of  lamps.  The  teeth  of  a wheel  e and  e',  more  distinctly  seen  in  Fig.  2474,  are  somewhat  advanced  into 
the  space  occupied  by  the  wick,  a cut  being  made  in  the  socket,  so  that  they  press  the  wick  in  some 
measure  against  the  back  side.  According  as  the  screws  are  turned  the  wick  is  either  raised  or  lowered, 
and  a larger  or  smaller  portion  of  it  is  engaged  in  the  combustion.  When  the  wick  is  high  a large 
auantity  of  oil  is  decomposed  ; and  when  low  a small  quantity  in  the  same  space  of  time : the  supply 
of  oil  is,  therefore,  easily  regulated. 


2474. 


2473. 


By  means  of  the  stem  a the  oil  vessel  can  be  placed  upon  any  kind  of  foot.  Besides  the  very  un- 
equal, constantly  decreasing  height  of  the  surface  of  the  oil,  another  objection  may  be  raised  to  this 
arrangement,  on  account  of  the  size  and  disadvantageous  direction  of  the  shadow,  the  conical  space 
between  /and  jig  receiving  no  direct  light. 

Study  lamp. — In  the  common  study  lamp,  Fig.  2475,  the  oil  vessel  a is  more  flat,  and  instead  of  being 
situated  below,  is  behind,  and  at  the  side  of  the  flame,  so  that  its  shadow  falls  much  beyond  the  imme- 
diate vicinity  of  the  flame,  and  in  no  way  interferes  with  the  person  in  front  of  the  lamp.  The  greater 
part  of  the  light  passing  upwards,  is  collected  by  the  shade  k,  and  from  every  point  of  its  inner  surface  is 
reflected  downwards  towards  the  opposite  side.  The  inclination  of  the  sides  of  the  conical  shade  is,  there- 
fore, not  unimportant,  and  should  be  at  an  angle  of  about  60°.  The  shade  can  be  turned  on  the  support  m n. 
The  motion  communicated  to  the  wick  d is  not  from  above,  as  in  Figs.  2473  and  2474,  in  which  arrange- 
ment the  pressure  interferes  too  much  with  the  supply  of  oil,  and  the  flame  is  too  much  cooled  by  the 
proximity  of  the  wheels,  but  it  is  from  below.  The  clamp  u.  Fig.  2476,  which  sustains  the  wick,  is  firmly 
connected  with  the  toothed  rod  e.  By  turning  the  wheel  o,  this  and  the  wick  is  raised  up  or  down ; the 
wheel  works  in  the  separate  compartment  g,  as  does  the  toothed  rod  in  descending  into  h,  whilst  the 
clamp,  the  rod  of  wire,  and  the  wick,  by  means  of  a rectangular  appendage  c,  Fig.  2477,  are  all  inclosed 
in  the  space  allotted  to  the  burner.  This  communicates  with  the  oil  vessel  through  the  tube  b ; i is  the 
inclosure  round  the  burner.  The  motiou  of  the  wick,  by  means  of  a toothed  rod  and  wheel,  is,  under 
various  modifications,  common  to  most  lamps.  The  stopper  l , at  the  aperture  for  filling  the  oil  vessel, 
must  be  pierced,  that  the  air  without  may  not  depress  the  oil  in  the  burner. 

The  astral  lamp. — The  astral  lamp,  of  which  a sketch  is  given  in  Fig.  247 8,  was  constructed  by  Bordier- 
Marcet,  with  the  idea  of  making  as  imperceptible  as  possible  the  sinking  of  the  level  of  the  oil,  and  at 
the  same  time  the  diminution  of  the  flame  by  means  of  a very  flat  oil  vessel,  in  which,  therefore,  a 
larger  quantity  of  oil  only  occupies  a very  insignificant  height.  It  is  clear  that  the  annular  flat  oil 
vessel  will  produce  only  a small  unimportant  shadow,  although  this  will  necessarily  be  thrown  on  all 
sides.  At  the  same  time  the  side  nearest  the  flame  a a is  so  inclined  that  it  acts  like  a shade.  Th : 
burner  is  not  peculiar  to  the  astral  lamp,  but  is  the  well-known  invention  of  Ami  Argand,  in  1789,  and 
named  after  him;  it  is  by  far  the  most  important  kind  of  burner  employed  for  illuminating  purposes. 
The  Argand  burner,  with  double  draught,  consists  of  two  metallic  cylinders,  one  within  the  other,  « 
and  d:  the  ring-shaped  space  between  them,  which  is  closed  at  bottom,  contains  the  oil  and  tbo 
lyliudrically  woven  wick  ; the  latter  is  clamped  between  two  rings,  which  are  connected  with  the  screw. 


LAMPS. 


167 


The  inner  cylinder  is  open  at  top  and  bottom.  The  extraordinary  advantages  of  this  arrangement  art 
easily  understood.  It  has  been  already  shown  that  with  entire  (massive)  wicks,  a nucleus  is  formed  in 
the  middle  of  the  candle,  which  illumines  but  little,  and  smokes  from  want  of  air ; with  the  hollow  wick 
a current  of  air  is  directed  exactly  to  that  spot,  so  that  the  flame  is  surrounded  by  two  concentric  cur- 
rents of  the  same  kind.  The  current  produced  in  the  air  by  a freely  burning  hollow-wick  flame,  or  the 
natural  supply  of  air,  is  by  no  means  sufficient  to  produce  the  requisite  amount  of  light.  As  soon  as,  bs 


2476. 


raising  the  wick,  the  size  of  the  flame  is  increased,  a thick  smoke  is  the  result ; and  when  the  wick  is  sc 
regulated  as  to  produce  no  smoke,  then  the  flame  is  weak  and  deficient.  But  Argand  gave  a real  prac- 
tical use  to  his  invention  by  applying  the  happy  idea  of  an  artificial  draught.  The  principle  is  the  same 
as  that  of  chimneys  : a rest  on  the  outside  of  the  burner  supports  a straight  glass  cylinder,  which,  in- 
cluding the  inner  and  outer  draught  of  air,  exerts  a powerful  influence  upon  the  velocity  of  both,  in 
proportion  to  its  height.  With  this  arrangement,  the  point  at  which  smoke  begins  to  be  evolved  cor- 
responds with  a much  higher  intensity  of  flame.  Another  advantage,  not  at  first  anticipated,  is  the 
great  steadiness  caused  by  the  chimney.  When  a draught  of  air  comes  in  contact  with  an  unprotected 
flame  its  force  and  cooling  influence  produce  diminished  combustion,  and  at  the  same  time  flickering  and 
smoke ; in  Argand’s  burner,  on  the  contrary,  the  supply  of  air  to  the  flame  is  become  self-dependent, 
whilst  the  heat  itself  is  made  the  motive  power.  The  cylinder  protects  it  from  any  direct  interruption, 
and  that  arising  from  the  draught  apertures  is  hardly  felt  at  all  in  the  interior.  It  must  not  be  left 
unnoticed  that  the  straight  Argand  cylinders,  whilst  assisting  the  draught,  fall  into  an  opposite 
extreme,  and  supply  too  large  and  injurious  an  amount  of  air.  This  was  remedied,  soon  after 
the  original  invention,  by  Lange,  and  forms  an  important  improvement ; it  consists  in  contract- 
ing the  diameter  of  the  glass  chimney  at  a certain  height  above  the  burner  at  b,  thus  forming 
a shoulder  of  a few  lines  in  width,  as  in  Figs.  2478  and  2479.  The  draught,  moving  in  the 
simple  cylinder,  in  a parallel  direction  to  the  axis  of  the  cylinder,  is  thus  broken  at  the 
shoulder,  and  thrown  into  the  flame  at  a certain  angle.  The  supply  of  air  is,  therefore, 
lessened,  but  the  direction  given  to  it  is  preferable  ; and  that  part  of  the  current,  which,  with- 
out taking  part  in  the  combustion,  cooled  the  flame  in  a useless  manner,  and  passed  along 
the  inner  surface  of  the  cylinder,  is  almost  entirely  removed.  The  glass  chimneys  are,  how- 
ever, applicable  to  all  burners  with  flat,  round,  or  semicircular  wicks. 

Sinumbra  lamp. — When  the  astral  lamp  is  used  as  a hanging  lamp,  the  shadow  of  the  circular  oil 
vessel  i3  thrown  more  towards  the  ceiling ; this  is  not  the  case  when  it  stands  in  an  upright  position, 


2470. 

ff\ 


\ 


By  an  ingenious  modification,  Phillips  has  succeeded  in  his  sinumbra  lamp,  Figs.  2480  and  2481,  (sim 
umbra,)  in  rendering  the  shadow  imperceptible  even  in  the  latter  kind,  and  this  is  done  by  the  peculiai 


168 


LAMPS. 


section  of  the  circular  vessel  o.  Its  three  surfaces  meet  in  the  form  of  a flat  wedge,  the  sharp  edge  of 
which  is  directed  towards  the  flame.  The  position  of  the  flame,  in  relation  to  the  oil  vessel  is  such  that 
Dwo  tangents  drawn  from  the  apex  and  base  of  the  flame  to  the  latter,  meet  a few  inches  behind  it  in  x. 
Beyond  this  the  vessel  can  cast  no  shadow ; but  even  in  this  small  space  it  is  almost  entirely  destroyed 
cy  a vase-shaped  ground-glass  shade,  which,  resting  upon  the  oil  vessel,  surrounds  the  chimney,  and 
scatters  the  light  in  all  directions  around.  The  manner  in  which  the  wick  is  moved  in  the  sinumbra 
burner  is  original,  and  deserves  notice ; there  is  neither  screw  nor  toothed  rod  employed.  The  inner 
cylinder  f is  furnished  on  its  outer  surface  with  a deep,  much  inclined  spiral  groove,  into  which  the 
short  peg  or  appendage  a of  the  wick-holder  e tits.  If,  therefore,  the  latter  is  turned  on  its  axis,  the 
peg  moves  along  the  groove  and  forces  e up  or  down.  From  its  position  in  the  burner,  however,  e 
cannot  be  approached  by  the  fingers,  and  directly  turned ; this  is  effected  by  the  cylinder  d,  whicn, 
throughout  its  whole  length — that  of  the  burner — has  a slit,  into  which  a second  peg  b,  on  the  outer  side 
of  e,  tits.  By  this  arrangement  d can  at  any  time  be  freely  moved  up  or  down,  but  cannot  be  turned 
without  taking  with  it  the  wick-holder,  causing  this  either  to  be  raised  or  depressed.  In  order  that  d 
may  be  moved  easily,  and  without  danger  from  the  flame,  it  is  firmly  connected  with  the  support  for 
the  chimney,  terminating  above  in  a thick  ring,  two  or  three  lines  wide,  which  rests  upon  the  edge  of 
the  cylinder  c , this  being  purposely  made  lower,  and  the  whole  is  thus  brought  up  to  the  full  height  of 
the  burner.  In  this  ring  the  supports  for  the  chimney  are  fixed.  If  these  are  turned  with  the  hand,  d 
is  turned  at  the  same  time,  and  with  it  the  wick-holder,  which  is  thus  moved  up  or  down.  Great 
mobility  characterizes  this  arrangement,  and  no  forcing  or  compression  of  the  ring  holding  the  wick  can 
occur. 

2t82. 


All  the  lamps  as  yet  described  are  subject  to  one  common  evil,  that  of  having  the  oil  vessel,  at  all 
events,  within  a few  lines  of  the  level  of  the  burner ; in  a position,  therefore,  which  throws  the  most 
objectionable  shadow.  A whole  series  e ‘ contrivances  have  consequently  resulted  from  the  efforts  of 
inventors  to  transpose  this  cistern  either  a considerable  distance  above  the  flame — when  its  shadow 
would  fall  upon  the  ceiling  of  the  room — or  to  a position  much  below  the  flame,  when  it  would  fall  at 
the  foot  of  the  lamp.  Both  resources,  however,  when  applied,  give  rise  to  new  and  critical  difficulties ; 
the  former  requires  that  the  supply  of  oil  which  flows  downwards  to  the  burner,  should  be  accurately 
regulated.  The  most  common  and  general  application  of  this  method  is  that  adopted  in  the  standing 
lamp,  Fig.  2482.  The  oil  cistern  A is  a movable  metallic  vessel,  capable  of  being  closed  at  the  bottom 
by  a valve  a,  which  moyes  between  the  regulating  rods  b b.  In  the  upright  position  the  valve  falls 
back  and  leaves  the  aperture  open  for  filling  the  vessel ; if  the  valve  is  then  pulled  up  by  its  rod,  the 
aperture  is  closed,  and  the  bottle  can  be  inverted  and  put  in  its  place  in  the  case  B,  (as  in  the  figure.; 
it  is  no  sooner  there  than  an  alteration  occurs.  The  rod  attached  to  the  valve  is,  namely,  so  long  that 


LAMPS. 


16« 


the  valve  is  raised  as  soon  as  it  touches  the  bottom  of  the  case  d.  The  oil,  therefore,  flows  out  for  a 
few  seconds  until  it  lias  risen  so  high  in  the  case  as  to  stop  the  aperture  of  the  bottle  A.  From  this 
instant  equilibrium  is  established,  and  as  the  mouth  of  A is  on  a level  with  the  height  of  the  burner, 
this  becomes  filled  at  the  same  moment,  connection  having  been  made  by  means  of  the  tube  g.  The 
lamp  has  really  two  oil  cisterns — an  under  one,  which  directly  feeds  the  burner,  and  an  upper  one,  the 
inverted  bottle,  for  the  supply  of  the  lower  as  the  oil  is  gradually  consumed.  As  long  as  the  level  of 
the  oil  in  B remains  unchanged,  and  the  mouth  of  A consequently  closed,  no  air  can  enter  A,  and  the 
whole  stock  of  oil  is  kept  up  by  the  pressure  of  the  atmosphere.  When  the  lamp  has  been  lighted 
some  time,  and  the  oil  sinks  below  the  mouth  of  the  bottle,  a few  air -bubbles  enter  and  take  the  place 
of  an  equal  bulk  of  oil,  which  flowing  out,  raises  the  level  in  B until  the  mouth  is  again  closed.  The 
same  operation  is  repeated  as  long  as  the  oil  is  present  in  A. 

The  other  parts  of  the  lamp  are  easily  understood : f is  the  support  for  the  cylinder,  (the  peculiar 
form  of  which  will  be  explained  below,)  q is  the  vessel  for  the  toothed  rod,  ar.d  e is  an  aperture  in  the 
case  for  the  easy  admission  of  air  into  the  interior. 

On  reflection  it  will  be  immediately  perceived  that  in  all  similar  lamps,  from  the  peculiar  arrange- 
ment of  the  oil  cistern,  the  height  of  the  oil  in  the  burner  will  not  be  always  quite  constant,  but  will 
alternately  sink  and  immediately  rise  again  to  its  former  height,  whilst  in  the  lamps  previously 
described,  the  suction  of  the  wick  is  rendered  more  and  more  difficult  by  the  constant  sinking  of  the 
level  of  the  oil. 

The  principle  in  question  has  been  put  into  practice  with  better  success  by  means  of  a simple  vessel 
without  case,  as  for  instance,  that  represented  in  Fig.  2483.  The  mouth  of  the  movable  oil  bottle  cor- 
responds here  with  the  lower  opening  b of  the  tube  a b,  which  passing  through  the  air-tight  collar  x,  is 
movable  in  the  lid  of  A.  The  oil  consumed  in  the  burner  e is  replaced  from  the  stock  contained  (above 
the  level  n n ) in  A,  the  place  of  which  is  then  occupied  by  air,  which  enters  at  b.  As  soon  as  the  con- 
sumption of  oil  in  eb  ceases,  no  more  air- bubbles  enter,  and  vice  versa.  As  the  level  of  the  oil  in  the 
burner  is  dependent  upon  the  position  of  the  mouth  b , this  can  be  most  accurately  adapted  to  circum- 
stances, a b being  movable.  The  cocks  o and  o'  are  only  used  in  filling  the  vessel. 


This  principle  can  be  applied  in  the  same  manner,  or  in  a much  more  compact  form  to  lamps  with 
circular  oil  vessels,  by  means  of  Caron’s  stop-cock,  Fig.  2484.  The  conical  plug  of  the  cock  is  com- 
pletely hollow,  and  at  a certain  distance  from  the  middle  it  is  supplied  with  a cross  bottom  a,  dividing 
the  space  into  two  unequal  parts.  In  the  upper  part  the  round  lateral  aperture  e is  made  opposite  to  o 
in  the  lower  part ; e'  and  o'  are  the  corresponding  apertures  in  the  case.  In  the  position  represented  in 
the  drawing,  e is  closed,  whilst  o is  in  free  communication  with  the  stock  of  oil  in  the.  circular  vessel  A A. 
This  stock  comprises  the  whole  quantity,  situated  above  the  mouth  m of  the  tube  in  n,  corresponding 
with  the  tube  a b of  Fig.  2483.  The  side  tube  comrftunicating  with  the  burner  also  opens  into  q q.  In 
the  opposite  position  of  the  cock  (by  closing  o)  the  space  A,  and,  in  the  first  instance,  q q is  shut  off 
from  communicating  with  the  burner,  whilst  the  same  space  A can  then  be  filled,  e being  open. 

By  transposing  the  oil  cistern  to  the  foot  of  the  lamp,  by  which  means  all  shadow  is  avoided,  we 
forego  the  important  advantage  which  the  free  flow  (fall)  of  oil  occasions,  and  by  means  of  which  it  can 
easily  be  conducted  to  the  burner ; and,  as  consumption  goes  on,  the  oil  must  then  be  raised.  The 
lamps  made  upon  this  principle  are  interesting  on  account  of  the  ingenious,  but  at  the  same  time  very 
complicates  elevating  apparatus,  which  partly  depends  upon  hydrodynamic,  partly  upon  hydrostatic 
laws,  and  is  partly  also  a mere  mechanical  arrangement. 

Girard's  lamp. — Girard’s  (hydrostatic)  lamp  is  constructed  upon  precisely  the  same  principles  as  the 
air-chamber  of  a fire-engine,  or  resembles  rather  Hero’s  fountain,  Fig.  2485.  In  these  arrangements  it 
is  well  known  that  the  pressure  exerted  in  a vessel  is  transferred  to  any  other  distant  cistern  by  means 
of  compressed  air,  and  is  the  means  of  forcing  a liquid  from  its  previous  position,  for  example,  in  an  up- 
ward direction.  In  Hero’s  fountain  the  primary  pressure  is  produced  by  the  column  of  water  a fed 
from  the  vessel  above  it ; the  air  inclosed  between  c and  the  lower  bulb  is  thus  compressed,  acts  upon 
the  surface  of  the  fluid  in  c,  and  forces  it  to  a corresponding  height  in  d.  All  these  compartments  are 
also  present  in  Girard’s  lamp,  but  are  closely  packed  together  for  the  sake  of  saving  space,  as  is  seen 
by  the  sketch,  Fig.  2486,  where  the  unimportant  parts  are  left  out.  A is  the  reservoir  for  the  forcing 
column  of  oil  in  the  tube  a b.  B the  lower  vessel  with  the  inclosed  air  B',  which  conveys  the  pressure 
received  from  a b through  cd‘  d to  the  vessel  C,  and  in  the  first  instance  to  the  air  C'  contained  in  it. 
As  long,  therefore,  as  there  is  pressure  from  a b,  the  air  C'  will  cause  the  oil  in  C to  rise  in  the  tube  g h 
to  a corresponding  height,  (to  the  burner.)  This  height,  therefore,  depends  upon  the  uniformity  of 
pressure  in  general,  and  ultimately  upon  the  constant  uniformity  of  height  in  the  column  of  oil  a b,  which 
lias  a tendency  every  moment  to  shorten  the  play  of  the  whole,  both  from  above  and  below ; from 
above  by  the  sinking  of  the  oil  in  A,  from  below  by  its  rise  in  B.  To  avoid  the  former,  at  least  for  the 
duration  of  an  evening's  consumption,  the  vessel  A is  furnished  with  a tube  ef  upon  the  same  principle 
as  that  described  in  the  oil  cistern  at  Fig.  2483,  so  that  th  i height  of  the  column  of  oil  exerting  pressure 


170 


LAMPS. 


coincides  with  the  aperture  e,  and  all  the  oil  above  that  must  be  considered  as  a store  for  the  supply  o' 
that  column.  The  latter  is  obviated  by  the  narrow  vessel  v which  surrounds  the  aperture  b,  and  is 
filled  up  to  s s in  a few  moments  by  the  oil  flowing  from  A,  thus  constituting  a basis  of  uniform  height 
for  the  column.  Both  contrivances  are  effective  until  the  oil  in  A sinks  below  e,  and  has  risen  on  the 
outside  of  v above  the  level  s s in  B.  With  the  requisite  height  of  the  lamps  the  pressure  of  the  column 
would  raise  the  oil  to  a greater  height  than  is  desirable.  To  avoid  an  excessive  length  of  burner,  the 
tube  c d' d may  be  curved  like  a siphon,  as  indeed  was  done  by  Girard,  by  which  means  the  oil  in  ef  is 
caused  to  rise  as  much  less  as  d is  below  the  fluid  level  in  C,  therefore  x less.  The  pressure  is  first 
exerted  to  overcome  the  column  of  oil  x,  and  it  is  only  the  excess  that  exerts  an  upward  influence  in  g li\ 
the  result  is,  therefore,  the  same  as  if  the  elevation  in  g li  was  effected,  not  from  the  level  of  the  oil  at 
C,  but  at  g,  for  gh  — ess. 

Future  endeavors  to  bring  the  principle  of  Girard’s  lamp  into  a form  more  suited  to  daily  use  will, 
perhaps,  be  successful ; for  the  limited  application  which  has  been  made  of  it  must  be  ascribed  to  its 
inconvenient  shape.  The  following  points  deserve  particular  notice ; first,  as  is  obvious  enough,  the 
working  of  the  lamp  is  not  independent  of  the  changes  of  temperature  and  pressure  in  the  atmosphere. 
Increasing  pressure  (rise  of  the  barometer)  and  a lower  temperature  will  diminish  the  bulk  of  the  air 
inclosed  in  B and  C,  and  cause  an  augmented  flow  of  oil  from  A towards  B.  A fall  in  the  barometer, 
and  a higher  temperature,  will  produce  an  opposite  effect,  and  cause  the  oil  to  flow  from  the  burner. 
The  effect  of  temperature  is  the  stronger  of  the  two ; but  both  by  proper  means  can  be  rendered  imper- 
ceptible, at  least  for  the  duration  of  an  evening.  Another  and  a greater  objection  arises  from  the  posi- 
tion and  the  shape  of  the  vessel  0,  upon  which,  as  may  be  seen  by  the  sketch,  the  supply  of  the  burner 
is  solely  dependent,  whilst  the  oil  of  A and  B is  only  employed  as  a fluid  pressure.  C cannot  well  be 
made  deeper  without  increasing  immoderately  the  height  of  the  lamp ; there  is,  therefore,  no  other 
means  of  affording  space  for  the  requisite  quantity  of  oil  for  an  evening’s  consumption,  than  by  adding 
to  the  breadth  of  this  vessel.  When  this  is  done,  and  from  its  being  placed  immediately  under  the 
burner,  the  shadow  falling  between  o ?/  and  o z will  very  much  exceed  the  space  occupied  by  the  foot  ot 
the  lamp.  Lastly,  the  necessary  additions  and  apparatus  for  filling  the  lamp  deprive  it  of  that  ease 
and  simplicity  in  the  management  which  daily  use  justly  demands. 


248G. 


2488. 


The  hydrostatic  lamp. — The  doctrine  of  the  equilibrium  of  fluid  pressure  has  found  an  application  in 
the  hydrostatic  lamps.  Two  different  fluids,  brought  into  tubes  which  are  connected  at  the  bottom,  will 
balance  each  other  at  different  heights,  according  to  their  respective  densities.  The  one  fluid  will  form 
a column  as  many  times  lower  as  its  density  exceeds  that  of  the  other  fluid.  A column  of  mercury 
requires  to  be  only  one  inch  in  height  to  balance  a column  of  sulphuric  ether  of  19  inches,  or  a column 
of  oil  of  14  inches. 

After  salt  and  water,  syrup,  honey,  mercury,  had  all  been  tried  as  heavy  liquids,  Thilorier  succeeded 
m 1825,  at  Paris,  in  giving  a decided  pre-eminence  to  his  lamp  by  the  use  of  a solution  of  white  vitriol 
(sulphate  of  zinc)  anil  by  a suitable  apparatus.  When  we  consider  that  the  fluid  producing  the  pressure 
must  not  affect  the  oil  or  the  sides  of  the  vessel,  (tinned  iron,)  that  it  must  not  become  solid  (crystallize)  at 


LAMPS. 


171 


2489. 


a temperature  several  degrees  below  0°  C.,  that  it  must  be  cheap,  and  have  the  proper  density,  we 
shall  then  understand  how  to  appreciate  the  discrimination  which  led  Thilorier  to  employ  a solution  of 
equal  parts,  white  vitriol  and  water.  Such  a solution  is  157  times  denser  than  oil,  so  that  a solution  of 
zinc  10  inches  high  can  support  a column  of  oil  15'7  inches  in  height. 

It  is  obvious  that,  with  the  diminution  of  the  column  of  oil  (the  consumption  of  oil  in  the  burner)  the 
solution  of  zinc  will  sink  to  a corresponding  level,  and  will  only  be  enabled  to  force  the  oil  to  the  origi- 
nal height,  when  it  itself  is  fed  by  a reservoir  of  zinc  solution.  The  cistern  A in  the  section  of  the  lamp, 
Fig.  2487,  is  solely  for  this  purpose.  In  a chamber  B,  in  the  foot  of  the  lamp,  both  the  equally  poised 
columns  terminate,  namely,  the  column  of  oil  in  the  tube  a b,  which  terminates  above  in  the  burner,  and 
the  column  of  zinc  solution  in  e d,  above  which  the  cistern  A is  situated  containing  the  zinc  solution. 
The  flow  is  effected  in  the  manner  described  in  Fig.  2483,  by  means  of  the  tube  o P,  through  which  the 
external  air  enters  bubble  by  bubble,  as  the  solution  in  e d threatens  to  sink.  The  height  of  the  column 
must,  therefore,  be  reckoned  from  P ; B is  completely  filled,  and  by  both  fluids  at  the  same  time,  so  that 
no  air  remains  in  it.  Into  the  lower  solution  of  zinc  (extending  to  nn 
in  the  figure)  the  tube  ed  is  plunged;  into  the  oil  above,  on  the  con- 
trary, the  tube  a b does  not  enter  beyond  the  top  layer  of  the  fluid  in  B. 

From  the  time  of  lighting  and  during  the  combustion,  the  level  nn 
naturally  becomes  higher  and  higher.  At  length  B becomes  quite  filled 
with  solution  of  zinc,  and  oil  must  be  supplied.  This  is  done  by  a 
separate  funnel  through  the  burner,  which  obliges  the  solution  of  zinc  to 
return  to  its  former  position,  an  outlet  being  afforded  for  the  air  in  A. 

The  tube  o P,  Fig.  2488,  (twice  its  proper  size,)  is  intended  for  this 
purpose,  having  a conical  appendage  h accurately  ground  to  fit  into//, 
and  luted  into  the  lid  of  A.  The  position  represented  is  that  for  filling, 
and  this  is  effected  by  the  peg  g,  which  is  fixed  to  o P,  and  only  rests 
on  the  edge  of  //;  when  h is  to  be  closed  the  tube  is  turned  until  g 
falls  into  a perpendicular  cavity.  The  oil  which  overflows  the  burner 
in  filling,  and  at  other  times,  collects  in  the  concave  lid  of  A,  and  passes 
off  by  i i to  a ring-shaped  movable  vessel  q.  This  vessel  is  open  and 
ring-shaped,  to  admit  of  the  passage  of  a b and  e d through  the  middle 
of  it. 

It  must  not  be  supposed,  even  when  every  thing  goes  on  regularly, 
and  the  supply  in  A is  not  exhausted,  that  the  level  of  the  oil  in  the 
burner  always  remains  the  same,  for  the  column  nab  is  constantly 
shortened  by  the  rise  in  n n,  and  more  rapidly  than  is  the  case  with  the 
zinc  column  n P during  the  same  time.  The  inventor  has  succeeded  in 
rendering  this  imperceptible  for  a duration  of  six  hours,  by  making  the 
diameter  of  B very  large  in  proportion  to  that  of  a b.  The  difference  of 
level  does  not  actually  exceed  two  to  three  lines,  whilst  the  oil  in  the 
burners  of  astral  and  sinumbra  lamps  frequently  falls  one  inch. 

Pump  lamps. — The  general  conclusion  may  be  inferred  from  what 
has  been  said,  that  the  different  static  lamps  either  do  not  attain  the 
important  advantages  which  their  construction  was  intended  to  confer, 
or  are  accompanied  with  corresponding  disadvantages.  In  contradis- 
tinction to  these  we  have  the  lamps  with  a mechanical  arrangement  for 
raising  the  oil ; and  as  a pump  is  generally  employed  for  that  purpose, 
they  are  called  pump  lamps. 

The  simplest  example  of  these  is  the  pump  lamp  with  a flat  wick, 
very  much  used  in  the  south  of  France,  although  not  in  this  country ; 
the  motion  of  the  pump  is  produced  by  the  hand,  but  in  a very  imper- 
fect manner.  The  piston  of  the  pump  is  kept  constantly  raised  by  the 
tension  of  a spiral  spring.  As  soon  as  the  piston-rod,  which  is  also  the 
ascending  tube  and  in  firm  connection  with  the  burner,  is  forced  down, 
by  overcoming  the  power  of  the  spring,  the  descending  piston  forces  the 
oil  in  the  cylinder  to  rise  through  the  tube  to  the  burner.  When  the 
stroke  is  ended,  the  elasticity  of  the  spring  brings  the  piston  to  its 
former  position,  and  the  cylinder  becomes  again  filled.  As  candles  re- 
quire snuffing  from  time  to  time,  so  here,  the  pump  must  be  used  at 
6hort  intervals.  In  lamps  of  this  kind,  with  double  draught,  the  burner 
is  fixed,  but  then  there  is  a piston-rod  with  a handle  at  the  side  of  the 
ascending  tube.  The  uniform  working  of  such  a lamp  depends,  there- 
fore, upon  the  care  which  is  taken  to  supply  the  oil  that  is  consumed  by 
repeated  use  of  the  pump.  If  this  is  only  done  at  long  intervals,  the 
flame  will  vary  from  its  utmost  intensity  to  a very  dingy  fight. 

The  numerous  improvements  which  have  here  been  noticed,  with 
reference  to  the  most  successful  and  interesting  inventions,  must  be  con- 
sidered as  important  advances;  but  they  have  nevertheless  left  one 
point  out  of  view,  upon  which  the  most  indispensable  conditions  for 
combining  a perfect,  and  at  all  times,  uniform  evolution  of  fight  depend; 
a point  which  is  indisputably  the  most  difficult  of  all  to  accomplish.  It 
has  been  noticed  how  the  lowering  of  the  oil  level  obstructs  more  and 


more  the  functions  of  the  wick,  and  consequently  diminishes  in  an  «qual  degree  the  brilliancy  of  the 
flame.  The  lamps  with  a supply,  upon  the  principle  of  connected  tubes,  are  subject  to  this  evil  in  its 


172 


LAMPS. 


entire  extent;  those  with  an  inverted  bottle  or  similar  arrangement  are  also  influenced  by  it  within 
certain  limits.  In  the  former  the  brilliancy  rapidly  diminishes ; in  the  latter  it  becomes  lessened,  and 
returns  to  its  original  state  at  regular  intervals. 

Carcel’ s clock-work  or  mechanical  lamp. — Carcel,  in  the  year  1800,  was  the  first  to  carry  out  the  idea 
of  pumping  up  the  oil  from  the  foot  of  the  lamp  to  the  wicK,  by  simple  machinery  like  that  of  clocks, 
and,  moreover,  in  such  quantity  as  to  exceed  the  quantity  consumed  during  the  whole  period  of  burn- 
ing. The  invention  of  his  clock-lamp  is  without  precedent,  with  reference  to  the  uninterrupted  and 
perfect  supply  of  oil  to  the  wick.  Whilst  in  the  other  lamps  the  burner  contains  a stationary  column 
of  oil,  which  either  constantly  decreases  from  above  or  is  reinstated  from  time  to  time,  the  oil  in  Car- 
cel’s  burner  forms  a constant  ascending  current,  which  always  supplies  the  wick  with  as  much  as  it  can 
possibly  require ; and  lastly,  the  unconsumed  portion  flows  back  to  the  foot  over  the  outside  of  the 


Carcel’s  invention  left  only  unimportant  points  connected  with  the  works  and  the  pump  to  his  suc- 
cessors, to  which  the  skill  of  others  has  been  applied.  Figs.  2489  and  2490  present  a section  of  Carcel’* 
lamp  and  its  various  parts,  with  Penot’s  improvements.  The  chief  parts  of  the  lamp  are  arranged  as 
follows : The  case  for  the  works  B and  the  space  A for  the  stock  of  oil,  form  the  foot  of  the  lamp.  The 
stem  of  the  column  contains  only  the  ascending  tube  b , which  separates  above  (over  the  capital)  into  a 
forked  appendage,  (crutch,)  upon  which  rests  the  burner  with  its  two  concentric  tubes  ee  The  burner 


LAMPS. 


17S 


and  the  ascending  tube  form,  therefore,  a space  which  is  connected  with  A by  means  of  tire  pump.  This 
latter  is  a so-called  priest-pump , and  is  more  simply  represented  in  Fig.  2491.  The  space  x is  closed 
at  the  top  by  a piece  of  elastic  cloth  or  leather,  in  the  middle  of  which,  when  [S1  2491. 
it  is  considered  as  a piston,  the  piston-rod  is  fixed.  By  its  upward  and  down- 
ward motion,  an  alternate  expansion  and  contraction  of  x is  effected.  In  the 
first  case  the  valve  s opens,  and  oil  enters  a:  from  rr;  in  the  other  case, 
through  the  valve  s',  oil  passes  from  x,  and  is  raised  in  the  tube  t.  The 
motion  of  the  cloth  or  leather  acts  in  short  in  the  manner  of  the  cheeks  and 
muscles  in  drinking  and  blowing.  To  meet  the  unavoidable  obstructions 
which  would  result  from  the  presence  of  impurities  in  the  oil,  it  is  all  made 
to  pass,  whilst  still  in  A and  before  entering  the  pumps,  through  a metallic 
sieve  with  fine  holes  </,  which  surrounds  the  whole  of  the  front  part,  including 
the  entrances  to  the  valves  below. 

The  quadrangular  box  of  the  pump  contains,  for  preserving  uniformity  of 
action,  three  simple  priest-pumps  ccc,  made  of  gold-beater’s  skin,  which,  during  every  moment  they  are  in 
action,  alter  their  positions  relative  to  each  other.  This  necessary  circumstance  is  self-evident  from  the 
whole  arrangement  of  the  pump.  Each  single  pump  has  two  valves,  an  entrance  valve  (the  under  one  in 
the  figure)  and  an  exit  valve  (the  upper.)  a is  a separate  chamber  for  each  : the  space  for  receiving  the  oil 
above  the  exit  valve,  on  the  contrary,  is  common  to  all.  The  three  short  piston-rods,  if  they  may  be  so 
called,  work  upon  three  crooked  arms  B y x on  the  same  axis,  but  in  different  directions.  One  pump 
must,  therefore,  always  be  forcing,  whilst  the  second  is  sucking,  and  the  other  midway  between  the  two. 
Below,  or  in  the  direction  of  B,  the  chamber  A is  completely  closed,  with  the  exception  of  a stuffing-box, 
through  which  the  crooked  pin  of  the  axle  is  moved.  The  wheel  t passes  under  a box  placed  at  the 
side,  in  which  this  stuffing-box  is  situated.  The  iron  frame  i i serves  to  give  steadiness  to  the  works  in 
B ; the  most  important  parts  of  the  arrangement  may  be  seen  in  Fig.  2490.  Motion  is  obtained  by  the 
spring  wound  up  in  the  case  ooo,  which  is  furnished  with  cogs.  The  cogs  of  o o o first  move  the 
toothed  wheel  t upon  the  same  axis  by  means  of  x.  The  wheel  t catches  the  second  cog  y above,  which 
has  the  same  axis  as  the  piston-rods,  and  thus  the  pumps  are  set  in  motion.  Below,  however,  t moves 
the  endless  screw,  on  the  axis  of  which  is  the  fly-wheel  d for  regulating  the  works,  by  means  of  z,  and 
the  toothed  wheel  u and  v.  At  the  very  bottom,  on  one  side  of  the  foot  of  the  lamp,  is  a small  bolt, 
which,  when  pushed  forward,  catches  the  fly-wheel,  and  either  stops  the  works,  when  in  motion,  or  sets 
them  going  when  it  is  pulled  back,  and  the  whole  has  been  wound  up. 

The  stopping-wheel  W is  used  for  winding  up  the  machine  with  a key. 

The  toothed  rod  g,  with  the  wick-holder,  works  below  the  crutch  of  the  ascending  tube,  in  the 
case  /. 

Experience  has  shown  that  the  whole  arrangement  of  the  works  is  not  so  tender  and  brittle  as  might 
at  first  sight  have  been  supposed. 

The  overflow  of  oil  from  the  burner  makes  it  necessary  to  screw  the  wick  up  somewhat  higher  than 
in  common  lamps  ; and  this  brings  with  it  the  great  advantage  of  the  flame  being  more  raised  above 
the  edge  of  the  burner,  where  less  heat  is  conducted  from  it,  and  it  burns  more  perfectly,  producing  no 
carbonaceous  matter  on  the  wick  and  about  the  edge  of  the  burner,  which,  in  general,  so  materially 
interferes  with  the  regular  flow  of  oil. 

Carcel’s  lamp  would,  without  exaggeration,  have  been  prized  as  much  as  Argand’s  had  been  six- 
teen years  previously,  if  a less  expensive  and  more  suitable  form  for  general  use  could  have  been  given 
to  it. 

At  an  earlier  period,  and  again  more  recently,  the  idea  has  occurred  to  those  versed  in  these 
matters,  to  replace  the  complicated  clock-work,  either  by  the  force  of  a falling  body,  (for  instance,  a 
piston  in  a cylinder,)  or,  at  least,  to  cause  the  tense  spring  to  act  upon  a larger  piston  of  that 
kind.  In  both  cases  the  oil  is  contained  in  a lamp-like  vessel,  resembling  the  cylinder  of  a pump, 
from  whence  it  is  slowly  forced  upwards  by  the  piston  (moved  either  by  gravity,  or  a spring)  to  the 
burner. 

So  far,  all  is  simple  and  easy ; but  the  practical  use  of  the  lamps  has  always  foundered  on  the  diffi- 
culty of  regulating  the  acceleration  of  the  fall,  or  the  diminution  of  the  force  of  the  spring,  to  the 
uniform  demand  of  the  burner.  The  arrangements  of  this  kind  are  all  wanting  in  simplicity,  or  they 
effect  their  purpose  but  imperfectly.  ‘•Generally,  the  ascending  tube  is  contracted  conically  at  a certain 
spot,  into  which  a conical  plug  fits.  The  spring  in  rising  enlarges  the  aperture  at  the  contracted'  spot, 
whilst  the  sinking  piston  lessens  it,  by  forcing  the  plug  either  backwards  or  forwards,  in  proportion  as 
their  motion  is  irregular. 

The  application  of  a phenomenon  for  raising  the  oil  in  lamps,  first  proposed  by  Celarier,  is  worthy  of 
notice,  from  its  novelty  and  simplicity,  and  because  it  may  possibly  be  productive  of  something  else, 
not  from  the  use  actually  made  of  it  at  present,  which  is  by  no  means  established.  It  is  of  very  com- 
mon occurrence,  and  may  easily  be  observed.  Celarier’s  lamp  consists  principally  of  two  vessels,  fixed 
one  above  the  other,  which  are  separated  from  each  other  by  a partition ; the  upper  contains  oil,  the 
lower  air.  In  the  partition,  a narrow  tube  is  placed,  which  opens  into  the  air-chamber  below  by  a 
valve,  and  somewhat  higher  in  the  oil  vessel  with  a simple  aperture.  On  filling  the  lamp,  the  oil  in 
this  tube  rises  to  the  same  height  as  in  the  vessel ; but  as  soon  as  the  valve  is  opened,  the  air  begins 
to  escape  by  the  same  tube  as  that  through  which  the  oil  is  passing,  in  endeavoring  to  fill  the  lower 
vessel.  The  result  is — with  such  a narrow  tube — that  with  the  bubbles  of  air,  drops  of  oil,  or  rather 
little  columns  of  oil,  are  carried  up  much  above  the  level  of  the  oil.  Another  plan,  applied  by  Samuel 
Parker  and  Mallet,  in  which  the  oil  is  warmed  in  a ring-shaped  vessel  above  the  flame,  before  reaching 
the  burner,  promises  theoretically  to  be  of  value,  but  requires  to  be  subjected  to  further  proof. 

Ludersdorff’s  lamp. — In  Berlin,  the  prices  admit  of  using  instead  of  pure  oil  of  turpentine  (that  is,  the 
lighting  material  of  Liidersdorff)  a mixture  of  this  spirit  with  4 parts  of  strong  alcohol,  of  at  least  90 


174 


LAMPS. 


per  cent.  (This  is  the  camphene  in  use  with  us.)  This  strength  is  necessary ; for,  with  a greater  amount 
of  water  the  flame  would  b®  too  much  cooled,  and  the  oil  of  turpentine  be  imperfectly  held  in  solution. 
The  carbon,  originally  amounting  to  88  per  cent.,  or  8 times  the  quantity  of  hydrogen,  is  diminished  by 
this  mixture  (illuminating  spirit)  to  63  per  cent..,  or  three  times  the  hydrogen,  which  is  much  less  than  is 
contained  in  oil  or  tallow.  The  lesser  evolution  of  light,  from  the  same  weight  of  spirit,  is,  however, 
actually  compensated,  although  at  some  cost,  by  the  greater  rapidity  with  which  the  light  is  evolved 
from  the  same  quantity.  Ludersdorft’s  lamp,  Fig.  24914,  is  well  adapted  to  show  the  different  mode 
adopted  in  burning  the  volatile  oils,  from  that  employed  with  the  fats. 

A is  the  vase  for  the  illuminating  spirit,  into  which  the  burner  11  descends  from  above  almost  to  the 
bottom.  It  consists  first  of  a straight,  pretty  wide  metal  tube  a a,  fitting  tightly  into  the  real  burner-tube 
ti  u,  which  surrounds  a loose  cotton  wick  o o,  and  fastens  it  by  the  semicircular  piece  x.  Above  A,  at 


24911. 


a distance  of  about  two  inches,  (the  wick  extending  thus  far,)  the  tube  becomes  narrower,  and  ends  at 
d,  in  the  knob  c,  which  is  the  real  burner ; at  the  base  of  b,  from  ten  to  twelve  holes,  \ line  in  bore,  are 
made  in  a circle  at  equal  distances  from  each  other.  When  the  lamp  is  to  be  used,  common  spirits  ol 
wine  is  ignited  in  the  cup  e e,  to  vaporize  the  illuminating  spirit  in  the  upper  part  of  the  wick.  As 
soon  as  the  vapor  issues  from  the  apertures  b,  it  is  ignited,  and  forms  the  flames/,  which  surround  the 
knob  c.  The  metallic  mass  is  then  sufficient,  on  account  of  its  high  temperature,  to  keep  up  vaporiza- 
tion with  ease,  (even  at  the  distance  of  c from  the  wick,)  and  the  lamp  continues  to  burn  by  itself.  To 
protect  A from  the  action  of  the  burner,  which  gradually  becomes  heated,  the  latter  is  suivounded,  to 
the  depth  of  three  inches,  with  a wide  case  i i,  which  is  attached  to  it  below,  (at  i i,)  so  that  a space 
filled  with  air  surrounds  it  thus  far.  Lamps  of  this  kind  give  a costly  but  brilliant  light,  free  from  all 
the  inconveniences  of  common  wicks. 

The  Liverpool  burner. — The  original  Argand  burner  g,  Fig.  2492,  is  supplied  with  oil  by  the  tube  i. 
At  its  lower  aperture  a wire  b is  fastened,  which  rises  through  the  axis  of  the  burner  to  a few  lines 
above  its  upper  margin,  where  the  projecting  end  is  furnished  with  a screw.  This  is  intended  to  sup- 
port a round  copper  plate  a (in  the  shape  of  a button)  of  equal  diameter  with  the  wick.  It  is  difficult, 
at  first,  to  establish  the  proper  relation  of  distance  between  a and  the  margin  of  the  burner,  but  it  is 
easily  found,  experimentally,  by  screwing  the  plate  backwards  and  forwards.  As  the  result  of  this 
arrangement,  the  internal  draught  is  forced  from  its  original  perpendicular  direction,  and  broken  against 
the  plate  a,  whence  it  is  propelled  at  a sharp  angle,  nearly  horizontally,  against  the  flame,  which  thus 
assumes  a globular,  instead  of  its  ordinary  cylindrical  form,  and  (as  is  shown  in  the  figure)  is  forced  into 
contact  with  the  external  current.  The  form  of  the  flame  makes  it  necessary  to  have  the  peculiar  bulg- 
ing chimney  c,  and  this  is  supported  by  the  case  e of  the  burner.  Complete  combustion,  together  with 


LAMPS. 


175 


intense  brilliancy  and  whiteness,  characterizes  the  flame  • but  there  is  nevertheless  a certain  want  of 
uniformity,  which,  however,  does  not  exist  in  the  nature  of  the  principle,  and  can  be  avoided  by  a 
proper  regulation  of  the  draught. 

The  lamps  constructed  by  Benkler  and  Buhl,  in  Wiesbaden,  since  the  year  1840,  depend  entirely 
upon  the  same  principle,  causing  the  draught  to  impinge  at  an  angle  upon  the  flame.  The  apparent 
novelty  of  the  invention,  the  surprising  brilliancy  and  peculiarity  of  the  flame,  and  partly  the  solid  and 
elegant  workmanship  of  the  lamps  themselves,  led  the  public,  at  least  for  a time,  to  confound  these 
advantages  with  the  more  essential  one,  namely,  the  economical  consumption  of  the  oil,  and  created  in 
a short  time  an  enormous  demand  for  this  invention.  Some  hasty  experiments,  which  were  published, 
tended  very  much  to  augment  this  over-estimation  of  its  value. 

Fig.  2493  is  a sketch  of  the  general  plan  of  Benkler’s  burner.  Fig.  2494  is  the  ground  plan ; and 
Fig.  2495  represents  the  upper  distinct  parts.  The  shoulder  of  the  chimney  is  here  formed  at  the  junc- 
tion of  two  pieces;  a narrower  glass  b,  above  the  flame,  and  a wider  glass  a,  which  is  below  it.  Just 
at  this  junction  is  placed  the  most  important  part  of  the  arrangement,  which  consists  of  a conical 


ascending  brass  ring  d d,  with  an  aperture  of  the  same  diameter  as  the  wick.  This  flat,  open  cone  is 
immovably  fixed  to  the  upper  glass  b,  by  bending  up  its  outer  edge,  Fig.  2495.  The  connection  of  b 
with  a is  effected  by  a so-called  bayonet  joint.  For  this  purpose,  on  the  lower  margin  of  the  plate  d, 
there  are  two  tongues  e,  and  these  correspond  with  two  cuts  in  the  ring  c,  with  which  the  margiu  of  a 
is  encircled.  When,  therefore,  d is  so  placed  upon  a that  the  tongues  and  cuts  correspond,  a simple 
turn  of  d is  sufficient  to  bring  the  tongues  under  the  ring  c,  and  thus  secure  the  whole.  The  apertures 
oo  are  made  around  a,  to  increase  the  draught  from  without.  The  principal  addition,  therefore,  in 
Benkler’s  lamp  is  a sudden  contraction  in  the  chimney  at  a certain  distance  from  the  flame,  the  aper- 
ture being  of  the  same  diameter  as  the  wick,  and  this  is  produced  by  the  insertion  of  a metallic  ring,  or 
cone. 

The  action  of  such  a contrivance  is  easily  understood.  The  external  and  internal  currents  of  air  and 
the  flame  must  pass  through  the  aperture  of  d,  where  a rapid  contraction  results.  The  outer  current  is 
driven  against  the  axis  of  the  flame  at  a sharp  angle,  and  thus  forces  the  flame  itself  into  the  inner  cur- 
rent, so  that  an  intimate  mixture  of  air  is  effected  with  the  products  of  decomposition  of  the  oil.  The 
flame  becomes  narrower,  and  three  times  as  long,  when,  by  keeping  back  all  the  air  which  has  no  part 
in  the  combustion,  and  by  giving  a proper  direction  to  that  which  has,  the  highest  and  whitest  bril- 
liancy, and  considerable  evolution  of  heat,  is  attained.  A perfectly  white  heat  is  produced ; for,  in 
consequence  of  the  well-ordered  combustion,  the  suspended  particles  of  carbon  are  more  intensely  heat- 
ed than  in  any  other  lamp.  Notwithstanding  the  intensity  of  the  heat,  the  chimneys — in  corroboration 
of  what  was  stated  above — stand  well.  A very  short  portion  of  the  flame,  that  which  produces  the 
least  light,  is  naturally  situated  below  the  cone  d ; but  the  longer  portion,  the  essentially  luminous 


2493. 


2494. 


176 


LAMPS. 


part,  is  above,  and  throws  a shadow  from  d downwards,  which  is  perceptible  in  standing  and  hanging 
lamps,  but  is  of  no  moment  in  the  determination  of  the  intensity  of  light,  as  it  only  occurs  in  the  direc- 
tion of  the  edges  of  d.  As  the  cone  d has  no  other  object  than  that  of  producing  a sudden  contraction, 
chimneys  are  now  made  in  one  piece  with  an  inward  bend  in  the  proper  place. 

The  lamps  constructed  by  Benkler  and  Ruhl  are  on  the  principle  just  described,  and  have  been  car- 
ried out  in  this  country  under  the  name  of  Solar  Lamps.  The  main  point  in  the  peculiar  construction 
of  these  lamps,  is  the  manner  in  which  the  air  is  caused  to  impinge  upon  the  flame  by  the  adaptation 
of  a metallic  or  glass  cone,  represented  at  a in  the  figures  below.  The  introduction  of  air  at  this  par- 
ticular part  of  the  flame,  or  at  this  certain  angle,  admits  of  crude  cheap  oil  being  consumed  in  the 
lamps,  which  would  produce  smoke  if  burnt  in  lamps  of  the  ordinary  construction.  The  combustion  of 
this  oil  in  the  ordinary  manner  being  attended  by  an  evolution  of  smoke  and  smell,  indicating  an  im- 
perfect consumption  of  the  constituents  of  the  oil,  gives  rise  to  the  necessity  for  an  increased  supply  of 
oxygen  or  air  to  that  particular  part  of  the  flame  where  these  unconsumed  portions  are  evolved,  to 
produce  the  inodorous  and  invisible  products  which  alone  should  result  from  perfect  combustion.  The 
oil  in  the  solar  lamp  is  contained  in  an  annular  vessel,  similar  to  that  described  at  Fig.  2478,  and  the 
lamps  are  constructed  in  precisely  the  same  manner,  with  the  exception  only  of  the  burner.  The  first 
form  in  which  the  new  burner  was  introduced  is  represented  in  section  at  1,  Fig.  2496,  and  consists  of 
a solid  metallic  box  fixed  upon  the  circular  wick-holder  of  ordinary  construction,  so  that  the  cone  or 


contracted  aperture  a , shall  be  bare  fth  of  an  inch  above  the  top  of  the  wick-holder.  This  relative  posi- 
tion is  observed  in  all  the  burners.  This  form  of  cone  box  was  found  very  inconvenient,  by  becoming 
exceedingly  hot  and  throwing  a considerable  shadow,  it  was  consequently  soon  superseded  by  that 
represented  at  2,  Fig.  2496,  in  which  the  metallic  box  is  very  much  diminished  in  size,  and  the  cone  is 
composed  of  glass,  with  a small  ring  of  metal  round  the  mouth  a.  This  ring  of  metal  is  essential,  as  it 
is  necessary  that  the  aperture  should  be  always  of  the  same  diameter,  and  glass  cones  can  never  be 
made  with  sufficient  nicety  to  present  at  all  times  an  exactly  similar  mouth.  The  solid  box  was  sub- 
sequently replaced  by  the  open  skeleton  cone  holder  represented  at  3,  Fig.  2496,  called  the  screw  cone 
glass-holder,  in  consequence  of  the  tall  thin  chimney  being  screwed  on  to  the  top  of  the  holder.  The 
last  improvement  is  the  plate  cone  glass-holder  represented  at  4,  Fig.  2496,  in  which  the  metallic  cone 
is  replaced  by  a flat  metallic  ring  fixed  upon  a skeleton  support,  the  external  edge  of  which  fits  closely 
to  the  glass  chimney. 

In  the  last  form  of  burner,  little  or  no  external  current  impinges  upon  the  flame  from  the  outer  sides 
of  the  cone  or  its  substitute  ; but  the  flame  is  only  forced  inwards  so  as  to  come  more  completely  into 
contact  with  the  current  of  air  passing  through  the  interior  of  the  burner.  The  solar  lamp  has  been 
extensively  used  in  consequence  of  the  low  price  of  the  oil  which  it  consumes  ; it  requires,  however,  a 
good  deal  of  care  and  cleanliness  in  trimming,  the  wick  must  be  freshly  cut  every  time  the  lamp  is 
used,  and  the  reservoir  should  be  refilled  with  oiL 


LAMPS. 


177 


2497. 


A form  of  pressure  lamp,  called  the  Elliptic  lamp,  in  which  the  constant  flow  of  oil  to 
regulated  in  an  ingenious  manner,  has  been  patented,  and  is  found  to  answer  perfectly, 
crude  vegetable  oils  are  consumed  in  it.  Fig.  2497  represents 
an  entire  section  of  the  lamp.  The  foot  of  the  lamp  forms  at  the 
same  time  the  oil  cistern : it  is  of  a cylindrical  shape,  and  a 
leather  piston  or  valve  B,  is  worked  up  and  down  in  it  by  rack 
and  pinion  seen  at  L.  F is  a spiral  spring  of  strong  iron  wire  fixed 
at  the  top  to  the  solid  stem  of  the  lamp,  and  exerting  a constant 
pressure  on  the  piston,  so  long  as  it  is  in  any  position  above  the 
bottom  of  the  oil  cistern.  The  tube  D,  which  opens  at  the  bot- 
tom in  the  shape  of  an  inverted  funnel,  and  ends  in  a disk  pierced 
with  holes,  supplies  the  oil  to  the  burner  and  passes  in  an  afr- 
tight  manner  through  a stuffing-box  in  the  piston  B,  and  can  thus 
be  moved  with  ease,  the  piston  remaining  stationary.  This  tube 
D,  is  widened  above  on  approaching  the  burner,  and  receives  a 
fine  silver  tube  several  inches  long,  and  one-thirtieth  of  an  inch 
internal  diameter,  which  is  surrounded  by  a cap  of  gauze,  made 
of  copper  wire  tinned,  to  prevent  corrosion.  This  gauze  has  very 
small  meshes,  that  no  solid  particles  mechanically  mixed  with 
the  oil  may  be  carried  up  into  the  silver  tube,  and  thus  impede 
or  altogether  stop  the  passage  of  the  oil.  The  whole  of  the  oil 
must  pass  through  the  silver  tube  before  reaching  the  burner, 
and  the  friction  thus  exerted  against  the  sides  of  the  narrow 
tube  is  the  only  resistance  offered  to  the  oil,  which  would  other- 
wise be  forced  up  all  at  once  to  the  burner  by  the  pressure  of 
the  spiral  spring.  This,  therefore,  is  the  regulator  for  the  supply 
of  oil,  and  must  be  so  proportioned  in  length  and  bore  to  the 
force  of  the  spring,  as  to  admit  of  a constant  excess  of  oil  flowing 
to  the  wick  and  over  the  sides  of  the  burner,  where  it  is  caught 
in  a receptacle  and  carried  back  into  the  oil  vessel  at  the  foot  of 
the  lamp.  The  lamp  is  filled  with  oil  by  slightly  raising  the 
whole  interior  portion  from  L,  and  pouring  oil  through  the  stem 
to  the  cistern  below  ; the  oil  then  rests  in  the  first  instance  on 
the  top  of  the  piston.  The  whole  interior  portion  of  the  lamp  is 
then  wound  up  by  the  key  I K and  the  rack- work  L,  until  the  top 
of  the  cistern  prevents  the  piston  B from  ascending  higher.  The 
tube  D and  the  burner,  <fcc.,  attached  to  it  is  then  pushed  down  by 
the  hand  through  the  stuffing-box  until  it  attains  its  original  po- 
sition. The  oil  which  was  previously  above,  having  passed 

2498. 


the  wick  ia 
even  when 


PlMinu  UAtini'c  / i uS^/jr'  *'‘U"  “***'■' 


during  the  ascent  of  the  piston  between  it  and  the  sides  of  the  cylinder,  is  now  below  the  piston,  and 
the  spring  in  forcing  the  latter  down  will  tend  to  force  the  oil  out  through  the  tube  D to  the  burner. 
The  force  of  the  spring  and  the  resistance  offered  by  the  silver  tube  are  so  proportioned  that  the  sup- 
ply of  oil  shall  last  eight  or  ten  hours. 

The  thick  consistence  of  crude  whale  oil  offers  such  powerful  resistance  to  the  action  of  capillarity 
at  the  ordinary  temperature  of  the  air,  that  the  oil  cannot  be  burned  in  common  lamps,  unless  it  is 
previously  rendered  more  fluid  by  the  aid  of  heat.  To  effect  this  a very  ingenious  form  of  lamp  has 
been  introduced,  called  the  Economic,  or  hot- oil  lamp.  The  oil  reservoir  of  this  lamp,  Fig.  2498,  is 
composed  of  a double  cylinder  surrounding  the  upper  part  of  the  chimney,  which  is  constructed  of 


178 


LAMPS. 


metal  and  slightly  curved  outwards,  so  as  to  reverberate  the  heat  upon  the  oil  vessel,  and  heat  the  oil 
to  a considerable  extent.  The  hot  oil  then  descends  by  the  arm  to  the  burner,  as  shown  in  the  figure. 
The  lower  part  of  the  arm,  which  is  attached  to  the  oil  vessel,  is  furnished  with  a slide  valve  worked 
by  the  trigger,  so  that  the  supply  of  oil  can  be  cut  off  by  raising  the  trigger,  and  the  oil  vessel  entirely 
removed  from  the  lamp  for  the  purpose  of  filling,  &c.  The  oil  is  introduced  by  this  valve,  the  oil  cis- 
tern being  inverted,  and  this  should  be  refilled  each  time  the  lamp  is  used,  care  being  taken  that  no  air 
remains  in  the  vessel,  as  this  would  be  expanded  very  much  by  the  heat,  and  cause  the  oil  to  overflow 
The  flame  is  regulated  by  raising  or  lowering  the  bell-mouthed  glass  chimney,  which  rests  upon  three 
points  below  and  is  moved  by  rack  and  pinion.  The  wick  is  not  movable,  as  is  the  case  in  ordinary 
lamps,  and  a fresh  wick,  which  is  accurately  cut  by  machinery  expressly  for  this  lamp,  must  be  insert- 
ed every  time  the  lamp  is  used.  A paper  or  glass  shade  surrounds  the  whole  of  the  upper  part  of  the 
lamp,  according  as  the  light  is  required  to  be  thrown  downwards  or  uniformly  diffused  through  the 
apartment.  Dr.  Ure  has  reported  the  illuminating  power  of  this  lamp  to  be  superior  to  that  of  Carcel’s 
mechanical  lamp,  and  when  consuming  southern  whale  oil,  it  would  appear  from  his  statements  to 
deserve  the  appellation  of  the  “ Economic”  to  the  full  extent  of  the  word. 


Camphene  lamps. — It  is  only  within  the  last  few  years  that  oil  of  turpentine  or  camphene  has  been 
successfully  introduced  into  general  use  as  a source  of  illumination  ; and  it  is  by  applying  the  principle 
of  the  solar  cone  in  an  extended  manner  that  this  highly  carbonaceous  substance  can  be  completely  and 
conveniently  consumed.  The  pure  oil  is  clear,  colorless,  and  very  mobile ; it  has  a peculiar  smell  and  a 
burning  taste.  Its  specific  gravity  is  0 86  to  0-87.  The  commercial  oil  is  frequently  adulterated  with 
resin,  which  raises  the  specific  gravity,  and  which  increases  in  quantity  when  the  oil  is  exposed,  in  con- 
sequence of  the  absorption  of  oxygen  from  the  air.  When  pure,  the  oil  boils  at  312°,  and  contains  no 
exygen,  but  consists  of:  88-46  carbon. 

11-54  hydrogen. 

100- 

A glance  at  the  composition  of  this  substance,  containing  so  large  an  amount  of  carbon,  shows  that 


LAMPS. 


179 


it  must  be  a powerfully  illuminating  body,  if  proper  modes  "can  be  adopted  of  supplying  a sufficient 
quantity  of  oxygen  or  air  for  the  entire  consumption  of  the  two  combustible  constituents,  and  at  the 
same  time  so  regulating  the  order  of  combustion  that  the  full  amount  of  light  shall  be  obtained  from  it. 

Mr.  Young  was  the  first  who  applied  the  increased  draught  of  air  produced  by  a cone  to  the  flame 
of  oil  of  turpentine.  The  burner  of  Young’s  Yesta  lamp  is  shown  in  Fig.  24-99.  It  is  an  ordinary  Ar- 
gand  burner  with  a Liverpool  button  a,  for  deflecting  the  internal  current  of  air,  which  enters  by  a 
space  left  open  near  the  pinion  handle  and  passes  through  a,  against  the  inner  side  of  the  flame  ; b is 
the  wick  tube  and  c the  space  between  the  latter  and  the  cone,  which  only  rises  in  this  case  to  the 
same  level  as  the  burner.  Through  c a current  of  air  impinges  upon  the  flame  at  that  part  where  it  is 
expanded  by  the  button  d and  the  internal  current  of  air,  and  again  the  air  in  passing  uja  the  innei 
sides  of  the  chimney  is  deflected  inwards  upon  the  flame  by  the  contracted  portion  at  e.  f is  the  pinion- 
handle  for  raising  or  lowering  the  wick.  The  whole  of  the  burner  is  screwed  upon  the  glass  vessel 
containing  the  oil  of  turpentine,  and  completely  insulated  by  a ring  of  wood  or  other  non-conducting 
material.  No  metallic  tube  passes  through  the  spirit  to  supply  ah-  to  the  interior  of  the  flame,  as  it  was 
supposed  that  this  would  become  too  strongly  heated  and  give  rise  to  acrid  and  offensive  fumes  from 
the  volatile  spirit.  Fig.  2499  shows  a plan  of  Young’s  burner.  This  lamp,  when  properly  managed 
aud  supplied  with  pure  camphene,  gives  an  excellent  light,  much  superior  to  that  produced  by  any  oil 
lamp  ; but  if  attention  is  not  paid  to  the  management,  or  the  camphene  is  not  pure,  it  frequently  evolves 
a strong  smell  of  turpentine,  producing  headache  and  other  disagreeable  sensations,  or  large  flakes  of 
soot  escape  unconsumed  and  cover  every  thing  in  the  vicinity.  The  evolution  of  smell  or  soot  is  always 
the  result  of  imperfect  combustion,  and  the  lamp  has  been  modified  in  different  ways  to  avoid  the  pos- 
sibility of  unconsumed  products  being  evolved. 


Seel ion 


The  lamp  which  fulfils  the  conditions  for  the  perfect  combustion  of  camphene  in  the  most  successful 
manner,  is  the  Gem  lamp,  a section  of  which  is  shown  in  Fig.  2500.  It  differs  from  Young’s  lamp,  in 
the  mode  of  deflecting  the  currents  of  air,  and  in  allowing  the  Argand  tube  supplying  the  internal 
current  of  air  to  pass  through  the  reservoir  containing  the  oil  of  turpentine.  In  Fig.  2500,  a is  the  tube 
supplying  the  internal  current  of  air  which  passes  through  the  reservoir  b to  the  burner  d , with  which 
it  is  in  metallic  connection,  and  it  is  not  found  that  the  turpentine  is  heated  by  this  tube  to  more  than 
one  or  two  degrees  above  the  temperature  which  it  attains  in  Young’s  lamp  ; the  temperature  of  the 


180 


LAMPS,  SPIRIT-GAS. 


spirit  in  both  cases  being  from  ten  to  fifteen  degrees  above  the  temperature  of  the  surrounding  air 
and  this  appears  to  be  no  more  than  is  required  for  the  proper  action  of  lamps  of  this  description 
The  button/,  which  deflects  the  inner  current  upon  the  flame,  and  forces  the  flame  to  take  an  outward 
direction  and  come  into  contact  with  the  first  outer  current,  has  the  form  of  an  inverted  cone,  and  the 
deflection  of  the  air  is  consequently  not  so  abrupt.  The  supply  of  air  to  the  inside  and  outside  of  the 
cone  is  regulated  by  a series  of  holes  drilled  in  the  brass  gallery,  and  the  number  and  size  of  these 
holes  are  proportioned  to  the  size  of  the  burner,  or  to  the  quantity  of  air  admitted  through  the  internal 
channel. 

Fig.  2501  shows  a plan  and  section  of  the  gallery.  C is  the  space  occupied  by  the  inner  current  of  air 
deflected  outwards  by  the  button,  A the  first  series  of  holes  admitting  air  to  the  interior  of  the  cone, 
and  B the  series  of  holes  through  which  the  air  passes  to  the  exterior  of  the  cone.  The  circle  A has  32 
holes,  drilled  with  a drill  one-twelfth  of  an  inch  in  diameter ; the  circle  B has  also  32  holes,  drilled  witli 
a drill  one-tenth  of  an  inch,  this  number  and  size  of  the  holes  having  been  found  by  a series  of  experi- 
ments most  advantageous  for  a burner  of  the  dimensions  represented  in  the  drawing.  The  cone  o,  Fig. 
2501,  in  this  lamp,  rises  above  the  level  of  the  wick  tube,  so  that  the  inner  current  of  air  and  the  first 
outer  current  meet  the  flame  below  the  button  at  the  point  represented  by  the  meeting  of  the  two 
arrows.  The  outer  current  of  air,  passing  through  the  holes  in  the  circle  B,  meets  the  flame  at  a 
higher  level,  and  insures  the  complete  combustion  of  any  products  that  may  have  been  uncon- 
sumed after  passing  the  point  where  the  arrows  meet.  The  height  of  the  chimney  will  of  course 
materially  alter  the  draught,  and  an  additional  quantity  of  air  must  be  admitted  if  the  chimney  is 
heightened.  The  proper  quantity  of  air  and  the  direction  of  the  different  currents  to  those  parts  of  the 
flame  where  they  are  most  beneficial,  are  the  objects  aimed  at  in  the  construction  of  this  lamp,  and 
they  appear  to  have  been  attained  more  perfectly  in  the  Gem  lamp,  than  in  any  other  spirit  lamp  yet 
invented.  A Gem  lamp  of  the  larger  form  is  reported  to  give  a light  equal  to  20  wax  candles : the 
light  from  one  of  the  smaller  size  is  equal  to  13  wax  candles. 

LAMPS,  SPIRIT-GAS.  The  lamps  which  we  here  present  are  designed  to  burn  the  gas  of  the  so- 
called  “ spirit-gas,”  which  is  a composition  of  alcohol  and  turpentine  distilled  together.  No  wick  is 
burned,  and  only  in  the  lamp,  Fig.  2502,  is  a wick  used,  and  only  for  capillary  attraction. 

C is  the  reservoir  of  the  fluid.  D is  a brass  tube  extending  into  the  fluid,  and  it  has  a cap  at  the  top, 
perforated  all  around.  F is  the  flame  ignition  points  of  the  gas,  as  it  comes  out  of  the  perforations.  E 
is  the  wick ; the  wick,  by  capillary  attraction,  carries  up  the  fluid  by  heating  the  top  of  the  tube  D 
until  the  fluid  becomes  gaseous,  it  then  rushes  out  through  the  perforations,  and  is  ignited  in  a state  oi 
inflammable  gas,  as  represented  at  F.  Great  numbers  of  this  kind  of  lamp  are  now  manufactured  and 
used  in  this  city. 


2503. 


Figs.  2503  and  2504  is  another  kind  of  lamp  altogether.  It  does  not  use  any  wick  at  all.  Fig.  2503 
is  a front  elevation  of  it,  and  Fig.  2504  is  an  enlarged  section  of  one  of  the  burners.  A is  the  camphene 
reservoir,  which  can  be  filled  at  the  top.  B is  a handle  passing  down  the  centre  of  the  vessel  and  fitted 
to  a conical  valve  at  the  bottom,  where  it  joins  the  top  of  the  central  vertical  tube,  so  that  the  flow  from 
the  reservoir  may  bo  cut  off  at  pleasure.  Two  curved  stems  carry  the  burners,  the  construction  of 
which  is  particularly  represented  in  Fig.  2504.  C on  the  right  is  the  screwed  attaching  branch-pipe. 
The  camphene  enters  by  this  branch  and  passes  through  the  diaphragm,  as  represented  by  the  arrow ; 
thence  upward  by  a sloping  arm  into  the  top  horizontal  passage  D,  which  is  formed  on  the  surface  of  a 
circular  disk  surmounting  the  whole.  It  then  descends  by  the  opposite  arm  to  the  flattened  boss  E,  and 
rises  through  a small  conical  aperture  in  its  centre.  This  aperture  is  fitted  with  a conical  spindle, 
screwed  at  its  lower  end,  and  in  one  piece  with  the  cup  F,  which  answers  as  a nut  for  turning  the 
spindle  to  adjust  the  size  of  the  opening.  The  course  of  the  gaseous  matter  is  then  directed  through  the 
central  chimney  G,  and  is  deflected  by  the  inverted  cone  above  it,  and  it  then  rushes  out  by  a circular 


LATHE. 


181 


ring  of  eight,  ten,  or  more  jets,  like  those  of  Fig.  2502.  The  burner  is  of  brass,  and  the  rest  may 
be  all  cast  in  one  piece,  with  the  exception  of  the  bottom  cup.  By  unscrewing  the  cup  a wire  can  be  intro- 
duced to  remove  any  obstructions  in  the  side  tubes,  but  no  obstructions  are  at  all  likely  to  get  in  them. 
In  lighting  this  lamp  a few  drops  of  alcohol  is  poured  into  the  cup  F and  ignited,  when  the  heat  vola- 
tilises the  campliene  in  the  passages  of  the  burner,  which  can  then  be  ignited,  and  the  heat  resulting 
from  the  ignition  of  the  gases  so  produced,  by  acting  upon  the  inverted  cone  at  H,  keeps  up  a con- 
tinuous stream  of  gas.  For  suspension  lamps,  this  one  has  no  ordinary  qualities  to  commend  it.  It  no 
doubt  requires  attention,  but  the  way  in  which  it  heats  the  fluid,  and  generates  a very  rarified  gas, 
renders  it  capable  of  giving  a very  brilliant  light. 

LATHE  FOR  TURNING  IRREGULAR  FORMS — Blanchard’s.  Fig.  2505.  This  machine  is  repre- 
sented in  the  figure  in  its  most  simple  form,  for  turning  shoe  lasts,  and  is  so  constructed  that,  from  one  as  a 
pattern,  an  exact  facsimile  can  be  formed  from  a rough  block  of  wood.  Both  the  pattern  and  block  are 
fixed  on  the  same  axis,  and  are  made  to  revolve  around  their  common  centre,  in  a swinging  lathe,  by  a 
pulley  and  bolt  on  one  end  of  the  axis,  as  shown  in  the  figure.  On  a sliding-carriage  is  attached  three 
posts,  through  which  are  fixed  pivots,  to  which  are  suspended  the  axles  of  a cutting  and  a friction 
wheel.  The  cutting-wheel,  which  is  about  one  foot  in  diameter,  turns  on  a horizontal  axle,  and  to  its 
periphery  is  fixed  a number  of  crooked  cutters  to  act  like  a gouge  when  the  wheel  is  put  in  motion. 
This  cutting-wheel  is  placed  opposite  the  rough  block.  The  friction-wheel,  which  is  of  the  same  diam- 
eter as  the  cutting- wheel,  is  placed  opposite  the  pattern,  so  as  to  press  against  it  when  in  motion.  These 
two  wheels  are  in  a line  w'th  each  other,  and  are  attached  to  the  same  carriage.  On  the  axle  of  the 
cutting-wheel  is  fixed  a pulley,  around  which  passes  a band  which  puts  the  cutting-wheel  in  motion  by 
a large  drum  revolving  under  it.  A crank  or  first  mover  communicates  motion  to  the  drum,  which  in 
its  turn  transfers  a rapid  motion  to  the  cutting-wheel,  while  a band  which  passes  from  a small  pulley  on 
the  drum-shaft,  puts  in  operation  a feeding  screw-pulley,  which  moves  the  sliding-carriage  horizontally 
from  left  to  right.  Another  pulley  on  the  drum-shaft  gives  a slow  rotary  motion  both  to  the  pattern 
and  the  rough  block,  in  a direction  opposite  to  the  cutting-wheel.  The  friction-wheel  is  turned  by  the 
pattern  resting  against  it. 


During  the  revolution  the  pattern,  being  irregular  in  its  surface,  causes  the  axis  to  approach  and  re- 
cede from  the  wheel.  Thus,  it  will  be  seen,  as  it  presents  its  whole  surface  to  the  friction-wheel,  so  in 
like  manner  the  block  presents  its  surface  to  the  cutting-wheel,  which  being  in  rapid  motion,  cuts  away 
all  that  part  of  the  block  which  is  further  from  the  common  centre  than  the  surface  of  the  pattern,  and 
thus  forms,  from  a rough  block,  an  exact  resemblance  of  the  model. 

Another  application  of  the  same  principle  is  shown  in  Fig.  2506.  This  machine  can  turn  out  a dupli- 
cate or  facsimile  of  any  pattern  whatever,  and  it  is  now  brought  to  such  perfection  that  an  oar-blade, 
a spoke,  a last,  and  an  axe-helve,  are  all  turned  upon  it  with  equal  facility  and  equal  perfection. 

This  is  a front  view,  as  seen  looking  somewhat  down  upon  the  machine.  A is  the  frame.  B is  a 
large  drum.  C is  a driving-pulley.  E>  is  a band  which,  from  the  drum,  passes  over  a pulley  E,  and 
drives  its  rotary  cutter- wheel  F F.  This  cutter-wheel  is  fixed  on  an  axis  in  a small  sliding-frame  which 
moves  from  one  end  to  the  other  of  the  lathe  by  a cord  N winding  upon  a spindle  lying  across  the  ma- 
chine, which  cannot  therefore  bo  seen,  but  which  is  driven  by  the  large  pulley  K,  thus  giving  it  a 
requisite  slow  motion.  H is  the  pattern  axe-helve,  and  G the  rough  material  to  be  cut  exactly  like  H. 
The  pattern  and  rough  material  are  placed  in  the  lathe,  represented  by  the  upright  frame,  and  sustained 
by  spindles.  On  the  back  part  of  the  machine  there  is  a curious  but  beautiful  sliding-rest,  which  is  the 
subject  of  a patent  in  itself.  It  moves  along  after  the  cutter-wheel,  and  has  two  plane  faces  on  which 
the  pattern  and  cut  helve  rest.  The  pattern  and  helve  roll  upon  the  planes,  while  the  rest  has  a rock- 
ing motion  which  accommodates  itself  to  all  the  uneven  turning  of  the  patterns,  &c.,  as  they  revolve. 
For  turning  long  articles,  this  rest  is  a beautiful  and  positively  necessary  part  of  the  machine.  To  turn 
a facsimile  of  any  pattern  it  will  at  once  be  evident  to  every  mechanic,  that  if  a pattern  be  placed  A 


182 


LATHE. 


a lathe,  and  the  material  to  be  turned  be  placed  with  its  axis  of  rotation  similar  to  that  of  the  pattern, 
and  if  a guide  pressing  on  the  pattern  directs  a wheel  with  cutters  to  operate  on  the  rough  material 
over  a surface  like  the  pattern  as  guided,  a perfect  representation  of  the  pattern  will  be  produced  on 
what  was  the  rough  material — simply  by  the  cutters  chipping  away  all  the  rough  material  outside  ol 
the  axis  of  direction — in  other  words,  all  the  wood  on  the  rough  material  outside  of  the  pattern.  This 
is  the  principle  upon  which  this  machine  is  constructed.  The  cutter-frame  slides  from  one  end  to  the 
other  of  the  pattern ; and  the  small  guide  seen  on  the  framo  pressing  on  the  pattern,  makes  the  cutters 
chip  away  all  the  rough  material  outside  of  the  pattern  on  G,  as  tho  cutter-frame  moves  from  end  to 
end  of  the  lathe.  The  cutter-wheel  has  three  motions — a rotary,  a horizontal,  and  an  eccentric  motion 


2306. 


The  pattern  and  rough  material  revolve  in  the  lathe.  This  is  done  by  three  pinions  on  the  right,  moveu 
by  the  pulley  seen  above  K.  The  speed  of  the  spindles  in  the  lathe  is  regulated  by  a very  excellent 
arrangement  of  a small  gang  of  pulleys  and  straps,  seen  on  the  right  at  the  end  of  the  machine.  These 
pulleys  are  operated  by  a lever  L,  and  they  are  so  arranged  that  a slower  motion  is  communicated  to 
the  spindles  when  the  thicker  part  of  the  pattern  is  to  be  turned,  or  such  a part  as  an  oar-blade.  The 
cutter-frame  moves  along  from  one  end  to  the  other  of  the  lathe  upon  a rail,  and  it  is  pressed  out  and 
in  according  to  the  shape  of  the  pattern,  by  the  upper  guide ; and  the  cutter-wheel  being  directed  in  the 
same  manner,  thus  cuts  the  pattern  on  the  rough  material.  The  strap  D is  retained  in  its  proper 
place  by  a grooved  pulley  on  the  cutter-frame,  and  the  whole  kept  firm  and  enug  to  the  work  to  be 
turned. 

LATHE,  SMALL  ENGINE.  Fig.  2507,  side  elevation.  Fig.  2508,  end  elevation. 

S is  the  bed-piece  and  head-stock,  cast  in  one  piece. 

B,  spindle  which  runs  in  gun-metal  boxes. 

C,  cone-pulleys  on  live  spindle. 

D,  upper  cone-pulleys  for  driving  feed-shaft. 

D',  lower  cone-pulley  for  driving  feed-shaft.  It  runs  loose  on  a stud,  and  has  a pinion  on  inner  end 
to  drive  the  two  worms. 

E,  worms — one  right,  the  other  left — which  drive  the  two  worm-wheels  so  as  to  feed  towards  the  right 
or  left,  as  the  operator  may  wish.  On  the  worm-geer  shaft  there  is  a pinion  driving  a geer  on  the  shaft 
above,  which  has  a chain-pinion,  around  which  an  endless  chain  passes,  attached  to  the  rest. 

A is  a hand-wheel  for  moving  rest  by  hand.  There  is  a pinion  on  the  other  end  of  the  hand-wheel 
shaft  geering  into  a rack  K on  the  side  of  the  bed,  as  shown  in  Fig.  2507. 

F is  the  tool-holder. 

J,  top  part  of  the  rest  which  slides  crosswise  of  the  bed  by  means  of  the  crank  and  screw. 

l,  square  spindle,  which  is  moved  by  hand-wheel  Y,  and  screw  inside  of  shell  G.  It  is  held  firm  ia 
its  place  by  the  handle-nut  H. 

a,  thumb  screw  for  raising  rest. 

m,  step-screw. 

b,  thumb-screw  for  adjusting  tool  in  rest. 

This  lathe  will  swing  1 6 inches  over  the  sills  and  7 inches  over  the  rest 


2507 


V 


LATHE. 


183 


•cos 


184 


LATHE. 


LATHE. 


185 


LATHE,  BORING  AND  REAMING.  Figs.  2509  and  2510.  I,  the  main  bed-piece,  supported  by  two 
cast-iron  standards. 

I),  bead-stock,  ■which  carries  the  spindle  and  cone-pulleys  A. 

G,  sliding-frame  that  supports  rest  P.  This  frame  is  traversed  backward  and  forward  by  means  oi 
the  hand-wheel  R,  which  has  a pinion  on  the  other  end  geering  into  the  rack  G on  side  of  the  bed,  (seen 
in  Fig.  2509,)  and  is  held  down  by  the  plates  N,  which  hook  under  the  slides  S,  and  is  secured  bv 
means  of  the  nuts  with  handle  H,  one  on  each  side. 


C510. 


0,  face-plate  on  livo  spindle,  to  which  tha  work  is  fastened  by  bolts  when  drilling  or  reaming. 

F,  tail-stock,  with  a traversing  spindle,  worked  by  the  hand-wheel  M,  which  turns  a screw  inside  o 1 
spindle  in  the  usual  way,  for  pressing  in  the  drill*  or  reamers,  &c. 

L,  hand-wheel  on  a screw  for  setting  thn  tail -stock  so  as  ta  make  a tapering  hole. 

A,  cone-pulleys  on  spindle. 

U,  geer  on  spindle. 

b,  pinion  on  spindle,  playing  into  geer  B. 

B,  geer  on  back  shaft  for  reducing  motion  of  spindle  and  increasing  the  power — same  as  is  common 
in  geered  head-lathes. 

K,  handle  for  throwing  the  back  geer-shaft  out  of  or  into  geer. 

This  machine  will  bore  out  a hole  3 inches  diameter  in  a wheel  3 feet  diameter 
LATHE,  ENGINE.  Figs.  2511,  2512,  2513.  Will  swing  50  inches  in  diameter  over  the  ways,  and 
32  inches  in  diameter  over  the  rest. 

Fig.  2511  is  a side  elevation  of  the  engine. 

Fig.  2512  is  an  end  elevation. 

Fig.  2513  is  a side  elevation  of  the  tail-stock. 

P represents  the  bed-piece  which  supports  the  head  and  tail  stocks  and  rest. 

C is  the  head-stock  in  which  the  live  spindle  runs  ; it  is  made  in  a saddle  form,  and  very  heavy ; 
bolted  to  bed-piece  by  six  bolts. 

B B'  are  the  geers  by  which  the  motion  of  the  spindle  is  reduced  and  the  power  increased. 


186 


LATHE. 


D D'  are  small  cone-pulleys  for  driving  the  long  feed-screw,  which  is  on  the  inside  of  the  bed-piece, 
and  not  shown  in  the  drawing. 

O,  geer  on  end  of  feed-screw,  driven  by  a pinion  on  the  hub  of  the  lower  feed-cone  D'. 

A,  cone-pulleys  on  spindle  of  cast-iron. 

F,  face-plate  with  geer  B attached  to  the  back  side. 

K,  tool-holder,  which  slides  upon  a swivel-post  S,  that  can  be  set  at  any  angle  and  fastened  by  the 
lever  and  screw  It  to  the  block  N,  which  slides  crosswise  of  the  bed-piece  by  means  of  the  crank  and 
screw  with  a balance  bolt  seen  in  Fig.  2511,  and  at  N'  in  Fig.  2512. 


G is  a hand-wheel  for  traversing  the  rest  by  handcraft.  This  wheel  runs  on  a stud,  with  a pinion  on 
its  hub  which  works  into  the  geer  H.  H is  placed  on  the  end  of  a short  shaft  with  a pinion  h on  the 
other  end,  geering  into  the  rack  I attached  to  the  side  of  the  bed. 

T is  the  main  sliding-saddle  or  plate  for  the  rest ; it  is  very  heavy,  and  permanently  fitted  to  the 
slides  and  hooked  down  by  pieces  J,  and  is  well  adapted  to  fastening  on  heavy  work  for  boring,  &c. 

M,  lever  for  changing  the  direction  of  the  feed. 

U,  handle  for  stopping  and  starting  feed. 

L is  the  lower  part  of  tail-stock,  w'hich  is  notched  on  to  the  slides  or  ways  of  the  bed-piece. 

Q,  upper  part  of  the  tail-stock,  which  is  made  to  slide  crosswise  for  tapering  work,  in  the  usual  way 


LATHE. 


1S7 


2512. 


'2511. 


LATHE. 


LATHE. 


LATHE. 


180 


LATHE,  LARGE  BORING  AND  REAMING.  A very  convenient  and  useful  tool  for  boring  and 
reaming  locomotive  and  car  -wheels,  pulleys,  geers,  &c.,  &c.  It  -will  turn  out  a hole  straight  or  tapering, 
and  spline  the  same,  -without  removing  it  from  the  chuck.  It  is  adapted  to  turning  or  drilling  out 
holes,  or  boring,  by  using  the  shell  boring-tool ; all  self-feeding. 

Fig.  2514  is  a side  elevation. 

Fig.  2515,  end  elevation,  looking  towards  the  face-plate. 

A,  cone-pulley  of  cast-iron  which  runs  on  the  live  spindle.  The  spindle  has  strong  journals,  running 
in  gun-metal  boxes. 

A',  geer  on  face-plate. 

B,  geer  on  front  shaft. 

o,  shaft,  thrown  out  of  and  into  geer  by  eccentrics. 

C,  face-plate,  to  which  the  work  is  fastened  by  means  of  bolts. 

D,  upper  cone  for  driving  the  feed  motion. 

D',  lower  cone  on  the  splined  shaft  which  passes  through  the  centre  of  bed-piece,  giving  motion  to 
the  rack  I,  which  can  be  connected  with  the  spindle  J,  by  the  screw  on  top. 


2515. 


F,  head-stock  in  which  the  live  spindle  rests. 

G,  swivel-post  on  which  the  tool-holder  slides, 

g,  bed-piece  on  which  G stands. 

G',  rest,  with  jaws,  for  using  flat  drills  and  reamers,  adjusted  by  the  screw  on  top. 

H,  upper  part  of  tail-stock,  inside  of  which  is  the  feeding  apparatus.  This  piece  rests  upon  a sliding- 
plate  that  is  traversed  crosswise  by  the  screw  L. 

S,  worm  which  geers  into  a segment  on  side  of  tail-stock  for  giving  the  proper  angle  when  a hole  is 
to  be  turned  out  tapering. 

K,  crank,  with  a bevel  pinion  on  the  inside  end  of  its  shaft,  geering  into  a large  bevel-wheel  that  has 
an  internal  screw  cut  through  its  hub  for  fastening  down  tail-stock  to  the  bed. 

M,  stand  cast  on  the  side  of  the  lower  piece  of  tail-stock,  carrying  a shaft  and  pinion  geering  into  a 
rack  on  side  of  bed-piece,  for  the  purpose  of  moving  tail-stock  by  hand. 

M',  pinion,  geering  into  rack. 

N,  rack  on  side  of  bed-piece. 

O,  bed-piece,  cast  with  cross-pieces  and  made  very  strong. 

This  lathe  will  admit  a wheel  5J  feet  in  diameter,  and  is  adapted  to  turning  off  the  rims  of  pulleys, 
»nd  for  surface  turning  generally.  These  engines  (pp.  166  to  172)  are  from  the  Lowell  Machine  Shop 


190 


LATHE. 


LATHE,  FOR  GUN  BORING,  TURNING,  AND  PLANING,  arranged  for  the  Ordnance  Depart 
ment,  U.  S.  Navy  Yard,  Washington,  by  ffi.  M.  Ellis,  Engineer.  Figs.  2516  to  2522. 

Fig.  2519.  c,  rest  for  supporting  the  muzzle  of  the  gun  ■while  boring. 

d,  pulley,  -with  belt  motion  above,  for  drawing  boring-bar. 

When  boring,  the  turning  mandrel  is  taken  out  and  the  boring-bar  put  in  its  place;  the  back  head  ,« 
forced  up  by  feed-screws  in  the  same  manner  as  slide-rest  for  turning. 

Fig.  2518.  C,  planing-head  and  tool-holder,  bolted  on  slide-rest  of  lathe  in  place  of  tool-holder  foe 
turning. 

h,  slide  of  tool-holder. 

i',  cogged  sector  working  in  rack  on  bottom  of  drill  of  tool-holder. 

i,  shifting  crank  to  convey  motion  to  sector. 

E,  ratchet-wheel  on  main  mandril  of  lathe,  to  give  motion  to  gun  on  the  centres  while  planing  be- 
tween the  trunnions. 

D,  eccentric  connection  to  give  motion  to  feed-hand. 

B,  bevel-geer  to  work  planing-head  and  feed-hand. 

A,  pulleys  on  bevel  pinion-shaft. 


Fig.  2516.  Back  (sliding)  head  for  turning  or  boring. 

k,  lever  for  throwing  head  out  of  geer. 

l,  feed-screw. 
n,  gibs. 

Fig.  2520.  h,  lever  for  throwing  slide-rest  out  of  geer. 
f,  feed-screw. 

m,  half-rest  for  feed-screw. 
n n,  gibs  on  slide-rest. 

Fig.  2521.  d,  pulley  for  drawing  boring-bar. 
e,  ratchet-wheel. 

f lever  on  ratchet-wheel,  for  boring. 


Fig.  2517.  c,  planing-head  for  planing  between  trunnions. 
h , tool-holder. 

Fig.  2522.  Standing-head. 
b,  feed-geer,  (same  in  Fig.  2519.) 
t7,  handle  for  changing  feed-geer. 


2518 


LA'flIE. 


191 


■CISC 


LATHE. 


192 


LATHE. 


193 


LATHE,  SMALL  SELF-ACTING  AND  SCREW-CUTTING,  by  Charles  Walton,  Leeds,  Eng 
Fig  2523  is  a general  side  elevation  of  the  lathe,  and 
Fig.  2524  is  a plan  corresponding. 

Fig.  2525  is  an  end  elevation  showing  the  geering. 

Fig.  2526  is  a transverse  section  taken  between  the  fast-head  and  the  slide-rest,  showing  the  lattei 
in  elevation,  as  also  the  arrangement  of  the  geering  for  traversing  the  same. 


Figs.  2527,  2528,  2529,  2530,  show  details  of  the  geering  for  working  the  slide-rest. 

Fig.  2231  is  an  elevation  of  the  top  cone  and  driving  pulleys : these  consist  of  two  sets,  the  smaller 
*et  being  used  for  reversing  the  motion  of  the  saddle  when  the  lathe  is  employed  in  screw-cutting,  and 
the  larger^when  the  tool  is  in  action,  and  a slower  motion  consequently  necessary. 


194 


LATHE. 


Fig.  2532  is  a section  through  the  driving-cone  on  the  lathe-spindle. 

Fig.  2533  is  a front  view  of  the  chuck. 

Fig.  2534  is  a side  elevation  of  the  same  ; and 

Fig.  2535  a vertical  section  in  the  plane  of  the  lathe-spindle. 

These  figures  exhibit  in  full  detail  the  several  parts  of  a very  efficient,  and,  in  many  respects,  conve 
ment  self-acting  and  screw-cutting  lathe. 

The  machine  is  carried  upon  three  standards  marked  A,  and  of  which  the  general  forms  are  shown 
in  Figs.  2525  and  2526.  These  standards  are  planed  on  their  upper  surfaces  to  afford  a solid  rest  for 
the  bed  BB,  the  upper  surface  of  which  is  also  planed.  The  exterior  edges  of  the  bed  are  bevelled  in 
the  usual  way,  as  a means  of  retaining  the  saddle-plate  L L of  the  slide-rest,  as  shown  in  the  cross- 
section,  Fig.  2526.  The  fast-head  C C is  fastened  to  the  bed  by  means  of  bolts : it  carries  the  main 
spindle  D,  upon  which  is  the  driving-cone  a,  a section  of  which,  showing  its  relation  to  the  spur-wheel  e 
and  pinion  b,  is  the  subject  of  Fig.  2532.  The  cone  is  as  usual  loose  upon  the  spindle,  and  cau  be 
attached  at  pleasure  to  the  wheel  e,  which  is  fast  upon  the  spindle,  when  it  is  necessary  to  throw  the 
back-speed  shaft  E out  of  geer.  This  is  effected  by  the  hand-rail  G,  which  connects  the  two  levers 
commanding  the  bearings  of  the  shaft  in  the  two  standards  of  the  fast-head,  a method  commonly 
adopted  when  the  arrangement  of  the  geering  does  not  conveniently  admit  of  the  shaft  being  shifted 
longitudinally.  The  motion  of  the  leading-screw  FT  is  derived  from  the  cone-spindle  through  the  train 
of  wheels  v w x y z,  in  screw-cutting ; and  in  plain  work  the  parallel  motion  of  the  tool  is  obtained 
through  the  train  v a'  e'  c,  and  the  band-pulleys  b'  and  c',  to  the  traverse-spindle  f'f,  which,  by  means 
of  the  worm  <j,  Figs.  2526  and  2530,  and  worm-wheel  i'  communicates  through  the  intervening  spur- 
pinions  r and  s with  the  pinion  t,  Fig.  2527,  geering  with  the  toothed-rack  u,  Figs.  2526  and  2529 
attached  to  the  under  side  of  the  saddle-plate  L of  the  slide-rest.  The  geering  for  reversing  the  motion 
of  the  saddle  consists  of  three  meter- wheels  and  the  clutch-box  k',  arranged  upon  the  traverse-rod  f f' 
The  clutch  k'  communicates  by  means  of  a spanner  fixed  upon  a horizontal  shaft,  passing  through  the 

2531. 


bed  of  the  lathe,  with  the  reversing-lever  V in  front.  By  this  means  the  shaft  communicating  with  the 
train  of  wheels  from  the  cone-spindle  maybe  geered  either  directly  with  the  traverse-rod  /'/',  or 
through  the  intervention  of  the  meter-wheels  at  pleasure.  A weighted  lever  j',  shown  in  Fig.  2526, 
serves  the  purpose  of  throwing  the  worm-wheel  i'  in  or  out  of  geer  with  the  worm  upon  the  traverse- 
rod,  thereby  connecting  or  disconnecting  the  lathe  with  the  saddle  of  the  slide-rest  ns  may  be  required. 
The  slide-rest  can  be  relieved  from  connection  with  the  leading-screw  N by  means  of  the  handle  o at- 
tached in  front  of  the  saddle : by  pressing  this  handle  down,  it  acts  upon  a stud  in  the  plate,  carrying 
the  screw-box  n,  which  is  thereby  opened,  and  the  saddle  relieved. 

The  movable  head-stock  J J is  provided  with  a screw/ for  shifting  it  out  of  the  line  of  the  axis  of 
the  main  spindle,  thereby  adapting  the  lathe  to  conical  turning. 

Action  of  the  lathe. — The  arrangement  of  the  geering  in  the  views  given  of  the  lathe  in  the  plates,  is 
that  adapted  to  screw-cutting.  The  cone  a,  which  is  loose  on  the  spindle,  is  fast  to  the  pinion  b of  13 
teeth;  this  pinion  geers  with  the  wheel  c of  52  teeth  upon  the  back-speed  spindle  E,  which  also  carries 
the  pinion  d of  13  teeth,  geering  with  the  wheel  e of  52  teeth,  fast  upon  the  cone-spindle  D.  According 
to  this  arrangement,  the  ratio  of  the  speed  of  the  driving-cone  to  that  of  the  main  spindle  is  as  16  to  1. 

The  connection  between  the  cone-spindle  and  the  leading-screw  FT  is  accomplished  by  means  of  the 
wheel  v of  40  teeth,  fast  upon  the  driving-cone  spindle ; this  wheel  is  working  into  the  wheel  w of  60 
teeth,  upon  a shifting-stud  attached  by  means  of  a radial  slot-bar  to  the  bracket  0,  bolted  upon  the 
fast-head:  this  latter  wheel  again  is  in  geer  with  the  wheel  x of  90  teeth,  also  upon  a shifting-stud,  and 
carrying  a wheel  y of  45  teeth,  in  geer  with  the  wheel  z of  90  teeth,  fast  upon  the  leading-screw  shaft 
N.  This  train  can,  of  course,  be  varied  at  pleasure  to  suit  the  particular  pitch  of  screw  to  be  cut,  the 
positions  of  the  radial  slot-bars,  carrying  the  studs  of  the  carrier-wheels,  being  at  the  same  time  shifted 
to  allow  the  wheels  to  come  into  geer. 

To  adapt  the  lathe  for  plain  sliding,  the  back-speed  shaft  is  put  out  of  geer  with  the  cone-spindle,  by 
means  of  its  hand-rail  G:  the  wheel  v upon  the  cone-spindle  then  s;e.ers  with  the  wheel  a',  working 


LATHE. 


I fin 


loose  upon  a stud  attached  to  the  head-stock,  and  carrying  the  cone-pulley  b’.  This  last  is  connected  by 
a band  with  the  loose  cone-pulley  o',  working  likewise  upon  a stud  fixed  to  the  standard  A,  and  carry- 
ing a wheel  d',  which  geers  into  the  wheel  e',  fast  upon  the  end  of  the  traverse  rod  /'/',  on  which  are 
the  three  meter-wheels  and  clutch-box  k',  also  the  sliding-worm  which  works  into  the  cone-wheel  i1  upon 
the  shaft  q.  This  shaft  revolves  in  bearings  attached  to  the  saddle,  and  carries  the  pinion  r,  Fig.  2527, 
working  into  the  wheel  s,  keyed  upon  the  same  spindle  which  carries  the  pinion  t,  also  fast.  This  latter 
geers  with  the  rack  u bolted  to  the  under  surface  of  the  saddle.  By  this  arrangement  motion  is  trans- 
ferred from  the  cone  to  the  traverse-rod  /'/',  and  thence  to  the  slide-rest  through  the  geering  attached 
to  the  saddle. 

Literal  references. — A A A the  standards  upon  which  the  lathe  is  supported. 

B B the  bed  or  shears  having  the  upper  ledges  upon  which  the  shifting  head-stock  and  saddle  rest, 
planed. 

C C the  fast-head,  which  is  firmly  bolted  upon  the  bed. 

D the  main  spindle,  which  is  highly  finished  and  case-hardened.  It  revolves  in  conical  collars  of 
hardened  steel,  and  is  further  secured  against  end-long  shift  by  a set-screw  bearing  against  its  outer  end 
through  the  bracket  I. 

E tlie  back-speed  shaft  revolving  in  bearings  inserted  in  the  projecting  lv.gu  F F,  cast  on  the  standards 
of  the  fast-head. 

G hand-rail  for  throwing  the  back-speed  shaft  in  and  out  of  geer  with  the  cone-spindle. 

H the  face-plate  which  is  screwed  upon  the  end  of  the  main  spindle. 

I bracket  bolted  to  the  outer  standard  of  the  fast-head ; see  D. 

J J the  movable  head-stock.  It  is  planed  and  fitted  upon  a saddle  K,  both  the  upper  and  tinder 
surfaces  of  which  are  planed ; on  the  upper  to  allow  the  head-stock  to  slide  upon  it  transversely,  and 
on  the  under  to  allow  of  its  being  travelled  on  the  bed  of  the  lathe. 

L L the  saddle-plate  of  the  slide-rest.  It  is  planed  and  fitted  with  bevelled  pieces  to  retain  it  upon 
the  bed  of  the  lathe,  as  shown  in  Fig.  2526. 

M the  tool-holder  of  the  slide-rest. 

N the  leading-screw,  carried  in  bearings  at  its  two  extremities,  attached  in  front  of  the  lathe. 

0 the  bracket  for  carrying  the  train  of  carrier-wheels  by  which  the  motion  of  the  main  spindle  is 
transmitted  from  the  leading-screw. 

P,  Figs.  2533,  2534,  and  2535,  the  front  plate  of  the  universal  chuck.  And 

Q the  back  plate  of  the  same,  showing  the  spiral  groove  for  expanding  and  contracting  the  clutches 
or  jaws. 

R R R the  clutches  or  jaws  of  the  chuck.  These  are  fixed  upon  separate  soles  through  which  one  of 
the  tails  passes,  while  the  other  passes  over  the  inner  end  of  the  sole  ; these  tails  slide  between  radial 
slots  in  the  front  plate  P,  and  enter  the  spiral  grooves  formed  in  the  face  of  the  back  plate  Q.  When 
the  back  plate  is  turned  upon  its  axis,  which  coincides  with  the  axis  of  the  main  spindle,  the  front  plate 
being  meantime  held  fast,  the  clutches  or  jaws  will  be  guided  simultaneously,  further  from,  or  nearer  to 
the  centre,  and  thereby  be  made  to  clutch  the  work  in  the  usual  way.* 

a the  driving-cone  of  the  lathe ; it  is  loose  upon  the  main  spindle,  and  fast  to 
b the  first  pinion  of  13  teeth ; it  is  fast  to  the  driving-cone  a. 
c wheel  of  52  teeth  on  the  back-speed  shaft  E ; and 
d a pinion  of  13  teeth  on  the  same  shaft. 
e first  wheel  of  52  teeth  on  the  main  spindle  of  the  lathe. 
f screw  for  moving  loose  head-stock  transversely  for  conical  turning. 
g hand-wheel  for  working  the  spindle  of  the  loose  head-stock ; and 
h a handle  for  tightening  the  pinching-screw  of  the  same. 

1 adjustable  check  by  which  the  slide-rest  M is  retained  upon  the  saddle-plate  L. 
j rest-plate  for  the  tool-carrier ; and 

k a screw  for  fixing  the  tool-holder  upon  the  slide-rest. 

I a hand-wheel  and  handle  upon  the  end  of  the  transverse-screw  of  the  side-rest.  This  screw  works 
in  plain  collars  attached  to  the  saddle-plate,  and  in  a nut  attached  to  the  sliding-sole  of  the  rest,  so  that 
the  screw  being  turned  it  carries  the  slide  from  or  towards  the  axis  of  the  lathe. 
m a crank-handle  upon  the  upper  slide-screw,  for  putting  the  tool  in  and  out  of  cut. 
n the  screw-box  for  the  leading-screw.  The  under  part  is  screwed  internally  to  the  same  pitch  as 
the  leading-screw,  and  is  carried  upon  a sliding-sole,  into  which  is  inserted  a stud  passing  through 
a slot  in 

o the  handle  for  connecting  and  disconnecting  the  screw-box  of  the  leading-screw.  It  acts  as  a lever 
of  the  second  kind,  the  stud  of  the  sliding-sole  of  the  nut  passing  through  a slot  in  it,  between  the  ful- 
crum and  the  part  acted  on  by  the  hand. 
p the  crank-handle  for  working  the  saddle-plate  by  hand ; it  is  placed  upon 

q the  transverse-shaft  upon  which  is  the  screw-wheel  i‘,  working  into  the  sliding-worm  g',  carried 
along  the  rod/'/'  by  a fork  Id  attached  to  the  saddle-plate. 
r a spur-pinion  keyed  upon  the  transverse-shaft  q,  and  working  into 

s a small  spur-wheel  keyed  upon  a short  spindle,  attached  by  bearings  on  the  bottom  of  the  saddle 
plate,  and  which  geers  with  the  pinion  r on  the  transverse-shaft  q. 
t a spur-pinion  keyed  on  the  same  spindle  as  s,  and  which  geers  with 
u an  inverted  rack  fast  to  the  bed  of  the  lathe. 


* This  arrangement  has  an  advantage  over  the  mode  of  working  the  clutches  by  separate  screws,  in  their  being  simul- 
taneously expanded  and  contracted  in  respect  of  the  centre ; but  it  frequently  happens  that  it  is  necessary  to  chuck  articles 
which  are  not  cylindrical,  and  in  which  it  is  more  convenient  to  have  the  clutches  movable,  independently  of  one  another. 
As  a familiar  example  may  be  instanced  hall-lap  coupling  ends  of  shafts,  which  are  semi-cylindrical,  and  must  be  made  up 
by  packing  to  the  cylindrical  form  before  they  could  be  caught  in  a chuck  of  this  kind. 


196 


LATHE. 


v the  first  pinion  in  the  trains  of  the  head-geering  of  the  lathe. 

w a carrier-wheel  which  geers  with  the  pinion  v ; it  is  loose  upon  a stud  in  the  stud-plate  0. 
x a second  carrier-wheel  upon  another  stud  in  the  stud -plate  O,  geering  with  the  former. 
y a third  carrier-wheel  on  the  same  stud  as  the  wheel  x,  and  made  fast  to  the  latter, 
z a wheel  keyed  upon  the  end  of  the  leading-screw,  and  geering  with  the  pinion  y. 

It  is  through  this  train  that  the  leading-screw  derives  its  motion  from  the  main  spindle  of  the  lathe. 
a'  a wheel  of  the  back-train  geering  with  the  pinion  v,  on  the  end  of  the  main  spindle ; it  is  keyed 
upon  a pap  of 

b the  upper  cone  of  the  back-train,  carried  upon  a stud  in  the  standards  of  the  fast-head.  It  is  loose 
upon  the  stud,  and  has  the  eye  prolonged  into  a pap  upon  which  the  wheel  a'  is  keyed. 

c'  the  lower  of  the  two  cones  of  the  back-train.  It  is  also  loose  upon  its  stud,  and  is  connected  by 
a band  with  the  upper  speed-cone  b‘. 

d’  a spur-pinion  keyed  upon  the  eye  of  the  speed-cone  c',  which  is  prolonged  for  that  purpose,  and 
which  geers  with 

e'  a spur-wheel  on  the  end  of  the  worm-shaft  f'f,  geering  with  the  pinion  d' . 

f'f  the  traverse-rod  or  worm-shaft ; a grooved  rod  passing  at  the  back  of  the  lathe,  and  having  its 
bearings  at  the  two  extremities.  It  is  also  supported  between  by  the  fork  which  slides  the  worm  g' 
alone;  upon  it,  the  projecting  sides  of  which  are  formed  into  a species  of  double  gallows,  as  shown  in 
Figs.  2526  and  2530. 

g'  worm  or  endless  screw  upon  the  traverse-spindle,  geering  with  the  worm-wheel  V.  It  has  a fixed 
key  in  the  eye  which  slides  in  a groove  in  the  rod  f'f. 

i'  worm-wheel  on  the  end  of  the  transverse-shaft  q,  worked  by  the  worm  g'. 
j'  a weighted  lever  for  disconnecting  the  worm-wheel  i'. 

k'  reversing-geer  upon  the  worm-shaft  f'f,  consisting  of  the  three  meter-wheels  and  clutch-box,  ar- 
ranged in  the  usual  manner,  and  worked  by 

V the  lever  of  the  reversing-geer  k'\  it  acts  by  a spanner  upon  the  clutch-box  lever,  bringing  the 
clutch  into  geer  with  either  of  the  wheels  upon  the  worm-shaft  at  pleasure. 

LATHE,  BACK-GEER  TURNING.  This  is  a good  specimen  of  a back-speed  lathe. 

Fig.  2536  is  a side  elevation  of  the  fast-head  ; Fig.  2537  an  end  elevation  of  the  same  taken  from  the 
back,  and  Fig.  2538  is  a plan  of  the  fast-head.  The  same  letters  are  used  on  each. 


2537. 


b,  the  driving  cone-pulleys,  loose  on  the  spindle  of  the  lathe  and  fast  with  the  pinion  p,  Fig.  2538. 
h,  a spur-wheel,  fast  on  the  back  shaft,  and  i a pinion  also  fastened  on  the  same,  w,  a wheel  fast  on 
the  lathe-spindle,  geering  with  the  pinion  i.  c,  is  the  chuck  or  face-plate  ; this  admits  of  being  taken 
off  the  lathe-spindle  when  not  required.  The  spindle  is  kept  forward  by  a back-centre  pinching-screw. 


Figs.  2541  and  2540,  are  end  and  side  elevations  of  the  shifting-head  of  which  Fig.  2539  is  a plan, 
is  a screw  for  shifting  the  spindle.  A hand-wheel  is  placed  on  the  outer  end  of  it,  which  revolves  in 


LATHE. 


19? 


a gland  embracing  the  ends  of  the  shifting- 
spindle  and  a guide-rod  under  the  screw, 

Fig.  2540 ; by  this  means  it  is  made  to 
move  horizontally,  and  to  carry  the  shift- 
ing-spindle of  the  head  along  with  it.  u is 
an  eye-bolt,  tightened  up  by  the  traveller  r 
on  the  spindle,  to  take  the  strain  off  the 
screw.  When  quicker  speeds  are  wanted, 
the  shaft  carrying  the  wheels  h and  i is 
moved  back  by  taking  out  a pin  seen  under 
h in  Fig.  2537,  and  the  cone  is  made  fast  to 
the  wheel  w by  a latch  in  the  usual  way. 

LATHE,  BORING  AND  TURNING, 
by  Mr.  Kinmonds. 

" Fig.  2542  is  a side  elevation  of  the  ma- 
chine. 

Fig.  2543  is  a general  plan  corresponding. 

Fig.  2644  is  an  end  view  from  the  left. 

Fig.  2545  is  a section  taken  in  front  of 
the  shifting  head-stock. 

The  fixed  head-stock  B B is  provided 
with  four  bearings,  cast  in  each  of  the  two 
standards,  for  the  purpose  of  receiving  the 
cone-spindle  C,  the  second  motion  shafts 
D and  E,  and  the  main  spindle  F,  upon 
which  the  face-plate  G is  fixed.  The  geering  of  the  machine 
is  calculated  to  produce  a series  of  variations  in  the  speed  of 
the  main  spindle  F,  independently  of  any  variation  which  may 
be  effected  by  means  of  the  driving  cone-pulley  a. 

To  effect  this  the  arrangement  of  the  wheels  upon  the 
shafts  D and  E is  such  that  either  of  them  may  be  thrown 
into  geer  with  the  cone-spindle  C,  and  the  internal  wheel  g, 
on  the  back  of  the  face-plate  G.  Thus,  if  the  wheel  e on  the 
shaft  D be  brought  into  geer  with  the  wheel  d,  on  the  cone- 
spindle,  the  pinion  / will  at  the  same  time  be  in  geer  with  the 
internal  wheel  g,  and  a quick  motion  will  be  communicated 
to  the  face-plate ; but  if  the  opposite  shaft  E be  slid  forward 
longitudinally  till  the  wheel  j geers  with  the  pinion  h,  the 
pinion  /'  on  that  shaft  will  be  thrown  into  geer  with  the  in- 
ternal wheel,  and  a slower  motion  will  consequently  be  im- 
parted to  the  face-plate.  Again,  let  both  the  shafts  D and  E 
be  thrown  out  of  action ; the  cone-spindle  0 may  then  be 
directly  connected  with  the  main  spindle  F by  means  of  the 
wheels  b and  c,  the  relative  sizes  of  which  may  be  varied  so 
as  to  produce  any  required  velocity ; this  latter  arrangement 
is  only  employed  for  obtaining  a high  speed,  as  in  the  case  of 
polishing. 

The  loose  head-stock  H is  adjustable  to  any  required  posi- 
tion by  means  of  a crank-handle  fitting  upon  the  square  end 
of  the  spindle  marked  o,  which  communicates  by  a train  of 
toothed  geer  with  the  rack  M,  fixed  upon  the  bed-plate  of  the 
machine,  as  shown  in  Fig.  2546.  The  pinion  which  works 
into  the  rack  is  keyed  upon  the  spindle  p,  carried  in  bearings 
attached  to  the  sole  of  the  head-stock.  On  the  same  spindle 
is  a small  bevel-wheel,  which  geers  with  a pinion  on  the 
lower  end  of  a vertical  spindle,  having  its  bearings  in  the 
interior  of  a hollow  column,  cast  in  the  body  of  the  head- 
stock.  On  the  upper  end  of  this  spindle  is  another  bevel- 
wheel,  which  geers  with  a pinion  on  the  horizontal  spindle  o 


198 


LATHE. 


thereby  completing  the  connection  with  the  fixed  rack  M.  This  arrangement  is  fully  exhibited  in  dotted 
lines  in  Fig.  25 1C. 

The  same  rack  M serves  also  for  moving  the  side-rest  K in  a longitudinal  direction,  by  means  of  a 
pinion  keyed  upon  the  shaft  q,  shown  in  Fig.  2543.  This  shaft  is  carried  in  bearings  attached  to  tl  a 
edge  of  the  sole-plate  of  the  slide  J, 
and  terminates  in  a square , to  which  a 
lever  may  be  applied  to  give  motion 
to  the  shaft.  The  sole-plate  of  the 
slide  is  provided  with  dovetail  grooves 
in  its  under  surface,  to  receive  the  cor- 
respondingly formed  heads  of  two  bolts, 
for  the  purpose  of  attaching  and  fixing 
to  the  saddle-plate  J the  sole  of  the 
bracket  K,  which  carries  the  slide-rest 
L.  To  afford  the  utmost  possible  facility 
for  adjustment,  the  bolt  holes  in  the 
sole  of  the  bracket  K are  slots  of  con- 
siderable length,  and  the  fixing  bolts 
hold  the  two  plates  firmly  together, 
metal  to  metal,  their  surfaces  of  contact 
being  planed  true. 

By  this  arrangement  the  slide  may 
be  made  fast  in  any  position  upon  the 
saddle  plate,  which  in  turn  is  retained 
upon  the  bed-plate  of  the  machine  by 
wedge-pieces  worked  by  means  of  two 
horizontal  eccentric  spindles  v v,  shown 
in  Fig.  2543. 

The  longitudinal  and  transverse  mo- 
tions of  the  tool-holder,  for  the  purposes 
of  traversing  the  work,  and  placing  the 
tool  in  and  out  of  cut,  are  obtained  by 
means  of  the  screws  r and  s,  which  work 
a'  right  angles  to  each  other,  in  the 
usual  manner ; the  tool  is  made  fast  on 
the  tool-holder  by  means  of  the  two 
e.amps  1. t.  In  adjusting  the  slide  pri- 
marily to  the  work  the  sole  K is  re- 
leased from  the  saddle-plate  J by  re- 
laxing the  connecting  bolts ; the  bracket 
K is  then  shifted  to  the  required  dis- 
tance from  the  longitudinal  axis  of  the 
machine,  and  also,  to  a certain  extent, 
in  the  line  of  that  axis  by  sliding  the 
bolts  in  the  dovetail  grooves  of  the 
saddle-plate,  should  that  operation  be 
more  convenient  than  moving  the  latter 
on  the  bed-frame  of  the  machine.  For 
' transverse  adjustment  to  a limited  ex- 
tent, the  screw  s can  be  used ; for  lon- 
gitudinal adjustment,  the  tool-carrier 
may  be  set  in  a similar  manner  by  the 
screw  r. 

Action  of  the  machine. — Supposing 
it  is  required  to  face  a heavy  piece  of 
work  by  this  machine,  it  is  clamped  to 
the  face-plate  by  means  of  bolts  which 
pass  through  radial  slots  formed  in  the 
latter.  The  wheel  c,  upon  the  end  of 
the  main  spindle  F,  is  then  removed, 
and  the  shaft  E is  slid  longitudinally  in 
its  bearings  until  the  wheel  j and  the 
pinion  f,  both  keyed  upon  it,  geer 
respectively  with  the  pinion  h , upon 
the  cone-spindle,  and  the  internal  wheel 
g,  which  is  fast  upon  the  back  of  the 
face-plate.  By  this  arrangement  the 
slowest  motion  of  the  face-plate  is  ob- 
tained. If  a quicker  motion  be  required,  as  when  the  action  of  the  tool  is  near  the  axis  of  the  machine, 
the  shaft  E is  thro  wn  out  of  geer,  (as  shown  in  the  views,  Figs.  2542  and  2543,)  and  the  shaft  D is  moved 
endways  until  the  wheel  e and  piuion  f upon  it  geer  respectively  with  the  wheel  d upon  the  cone- 
spindle,  and  the  internal  wheel  g upon  the  back  of  the  face-plate.  The  speed  is  thus  increased  in  the 
ratio  of  the  number  of  teeth  in  the  wheel  d and  pinion  li ; that  is,  as  51  to  15.  A still  higher  speed, 


LATHE. 


199 


and  indeed  the  highest,  is  obtained  by  arranging  the  geering  of  the  machine  as  it  is  represented  in  the 
engravings.  The  shafts  D and  E,  it  will  be  observed,  are  both  out  of  geer,  (being  retained  in  that 
position  by  the  catches  k lc',)  and  the  wheel  b upon  the  cone-spindle  C is  in  geer  with  the  wheel  c,  upon 
the  end  of  the  main  spindle  F,  so  that  the  speed  of  the  cone  is  transmitted  to  the  face-plate  through  the 
single  pair  of  wheels  b and  c,  which  are  to  each  other  in  the  ratio  of  51  to  (50. 

These  three  speeds,  which  are  independent  of  the  five  speeds  obtained  by  the  cone,  may  be  thus 
compared : — The  numbers  of  teeth  in  the  wheel  j and  pinion  f upon  the  back-shaft  E,  are  respectively 
78  and  13,  and  the  numbers  in  the  pinion  h,  upon  the  cone-spindle,  and  in  the  internal  wheel  g upon  the 
back  of  the  face-plates,  are  15  and  1 19  ; consequently  when  the  shaft  E is  in  geer,  the  ratio  of  the  speed 
between  the  cone-spindle  and  the  face-plate  is  as  78  X 119  : 13  X 15,  or  as  47'6  to  1,  being  the- slowest 
motion  of  which  the  machine  is  capable.  Again,  the  numbers  of  teeth  in  the  wheel  e and  the  pinion  / 
upon  the  shaft  D,  are  respectively  51  and  13  ; and  the  numbers  in  the  wheels  d upon  the  cone-spindle, 
and  the  internal  wheel  g,  being  51  and  119,  therefore  when  the  shaft  D is  in  geer,  the  ratio  of  the  speed 
of  the  cone-spindle  to  that  of  the  face-plate  is  as  119  : 13,  or  as  9T5  to  1.  And  when  both  of  these 
shafts  are  out  of  geer,  and  the  wheel  b upon  the  cone-spindle  is  working  into  the  wheel  c upon  the  mai>" 
spindle,  the  numbers  of  teeth  being  respectively  51  and  66,  the  ratio  of  the  speed  is  1 to  T3  nearly. 


2545. 


The  action  of  the  machine  in  ordinary  parallel  turning  is  the  same  as  in  any  common  lathe.  The 
mode  of  obtaining  a self-acting  longitudinal  motion  of  the  tool-carrier  is  by  a stellar-plate  fixed  upon 
the  end  of  the  screw  r,  and  which  is  worked  by  an  arm  bolted  to  the  face-plate  or  to  the  object  which  is 
being  turned,  so  as  to  come  in  contact  with  the  plate,  and  cause  it  to  advance  one  tooth  at  each 
revolution. 

Application  of  this  lathe  to  the  boring  of  cylinders. — When  the  machine  is  to  be  used  as  a boring- 
mill,  the  slide-rest  and  shifting  head-stock  are  removed,  and  a boring- bar  is  substituted ; one  end  being 
supported  by  a standard  fixed  upon  the  bed-plate. 


Literal  References. 


A A,  the  bed-plate  of  the  machine. 

B B,  the  fixed  head-stock,  bolted  to  the  bed-plate. 

C,  the  driving  cone-spindle. 

D E,  the  second  motion  shafts. 

F,  the  main  spindle  carrying  the  face-plate  G. 

a,  the  driving  cone-pulley  with  five  speeds. 

b,  a wheel  of  51  teeth  working  into 

c,  a wheel  of  66  teeth  on  the  main  spindle. 

d,  a wheel  of  51  teeth  working  into 

e,  an  equal  sized  wheel  on  the  second  motion 
shaft  D. 

//'.pinions  of  13  teeth  on  the  shafts  D and  E, 
working  into 

g,  the  internal  wheel  of  119  teeth  attached  to  the 
face-plate. 

h,  a pinion  of  15  teeth  working  into 

j,  a wheel  of  78  teeth  upon  the  second  motion 
shaft  E. 


k k',  catches  for  retaining  the  shafts  D and  E when 
put  in  or  out  of  geer. 

1 1,  stay-rods  for  strengthening  the  fixed  head- 
stock. 

H,  the  shifting  head-stock. 

jw,  a screw-spindle  with  hand-wheel  for  adjusting 
the  centre  in  the  shifting  head-stock. 

n,  a pinching-screw  for  fixing  the  centre  when  ad- 
justed. 

o,  a spindle  for  moving  the  shifting  head-stock 
longitudinally. 

p,  a transverse  shaft  forming  part  of  the  mechan- 
ism by  which  the  shifting  head-stock  is  moved. 

h'  h',  hooked  bolts  for  filing  the  shifting  head 
stock. 

J,  the  saddle-plate,  forming  a support  for 

Iv,  a bracket  for  carrying  the  slide-rest. 

L,  the  longitudinal  carriage  of  the  slide-rest. 


200 


LATHE. 


M,  the  toothed  rack,  fixed  to  the  bed-plate  for  the 
purpose  of  moving  the  slide-rest  and  shifting 
head-stock. 

q ,  a shaft  carrying  a pinion  which  works  into  the 
rack  M,  for  moving  the  slide-rest  longitudi- 
nally. 


r,  longitudinal  screw  of  the  slide-rest. 

s,  transverse  screw  of  do. 

1 1,  clamps  for  fixing  the  tool  upon  the  slide-rest 
u,  screw  for  fixing  the  slide-rest. 
v v,  screws  for  fixing  the  saddle-plate. 


LATHE,  BORING  MILL  AND  LARGE  TURNING  LATHE.  This  is  an  indispensable  tool  in 
works  where  engines  of  a large  class  are  constructed.  The  plates  exhibit  a side  elevation  and  plan, 
with  the  parts  marked  by  the  same  letters  of  reference. 

A,  the  boring-bar,  having  a recess  in  it  to  receive  the  feeding-screw ; see  Fig.  2547. 

C C and  D D,  brackets  for  carrying  bar. 

B,  bed-plate  for  fixing  the  work  by  T-headed  bolts,  passing  through  the  longitudinal  slots  cast  in  it. 

E,  Fig.  2547,  boring-block,  fitting  accurately  on  the  bar ; it  is  moved  along  it  by  the  feed-screw 

working  into  the  nut  v,  inserted  into  the  boring-block. 

H,  main  spindle  carrying  the  driving  cone-pulleys. 

G,  the  face-plate  for  fixing  the  work  to  be  turned. 

S,  Fig.  2548,  a cylinder  undergoing  the  process  of  boring. 

t,  bars  for  fixing  the  cylinder  to  the  bed-plate. 

y,  a coupling  bolted  to  the  face-plate  for  the  purpose  of  driving  the  boring-bar. 

a,  pinion  fast  to  driving  cone-pulleys  and  to  the  boss  on  the  spindle  H. 

b,  wheel  fast  on  the  shaft  o,  and  geering  with  the  pinion  a. 

c,  pinion  driving  the  wheel  d,  but  which  may  be  slid  along  the  shaft  on  a sunk  feather  towards  g,  so 
as  to  be  clear  of  d when  required. 

g,  wheel  fast  on  the  shaft  o. 

h,  wheel  which  geers  with  the  wheel  g,  when  required. 

c,  wheel  on  the  shaft  p,  which  geers  with  that  marked  b,  on  the  shaft  o. 

k,  internal  wheel  fast  on  the  back  of  the  face-plate  G. 

i,  pinion  fast  on  the  shaft  p,  and  geering  with  the  internal  wheel  Jc,  to  communicate  motion  to  the 
face-plate. 

ss,  planed  rails  for  the  brackets  C and  D,  or  other  supports  that  may  be  used  to  carry  lathe-heads. 

w,  x,  boring-rings  ; the  internal  ring  w is  usually  bored  to  fit  E,  and  allowed  to  remain  on  the  boring- 
block,  the  larger  ones  being  keyed  on  it.  The  ring  x,  suited  to  bore  the  cylinder  s s,  has  24  slots  in  its 
circumference  ; 12  of  these  receive  the  cutters,  which  are  adjusted  and  fixed  by  small  wedges ; some- 
times they  are  bedded  on  paper.  The  other  slots  are  fitted  with  pieces  of  hard  wood  driven  tightly 
into  them  to  form  a general  guiding  surface. 

I,  wheel  loose  on  the  boring-bar,  and  having  external  and  internal  teeth.  The  internal  teeth  geer 
with  those  of  a pinion  on  the  end  of  the  feed-screw ; see  Fig.  2549. 

m,  wheel  fast  on  the  boring-bar,  and  having  the  same  number  of  teeth  as  the  wheel  l,  (64.) 

n,  q , wheels  fast  on  the  small  shaft  u,  and  geering  with  m and  l.  The  wheel  q has  one  tooth  less 
than  n,  (35  and  36,)  so  that  one  turn  of  the  wheels  n and  q advances  the  wheel  l one  tooth  on  the  bar, 
and  (the  internal  wheel  having  the  same  number  of  teeth  as  the  external)  produces  a motion  of  one 
tooth  of  the  screw-pinion.  The  screw  being  -J-  inch  pitch,  and  the  piston  16  teeth,  the  feed  motion  of 

5*  **  *03125  X 64 

the  boring-block  will  be  — = '03125  inch  for  each  turn  of  the  wheels  n and  q,  or = .0571 

b 16  1 35 

inch  during  one  turn  of  the  boring-bar. 

The  following  table  exhibits  the  various  speeds  of  which  the  boring-bar  is  susceptible. 


Turns  per  minute. 

Turns  per  minute. 

1 

•333 

X 3 = 1 

13 

4-839 

o 

•416 

14 

6-049 

3 

•520 

15 

7-561 

4 

•650 

y/  -650  x 3 = 1-4 

16 

9-451 

5 

•812 

y/  -812  X 3 = 1-56 

17 

11-814 

6 

1015 

18 

14-767 

7 

1-269 

19 

18-457 

8 

1-586 

20 

23-079 

9 

1-982 

1-982  X 3 = 5-946 

21 

28-842 

in 

2-478 

22 

36-053 

1 1 

3-077 

23 

45-066 

12 

3-871 

24 

56-333 

The  speeds  increase  as  1 to  1$,  so  that  any  speed  within  the  range  may  be  procured  to  within  § of 

84 

that  required ; that  is,  the  boring  speed  being  7 feet  per  minute,  the  greatest  deviation  will  be  — = 10  J 
inches  per  minute. 

The  cone-pulleys  of  the  machine  are  driven  by  a similar  set  of  cone-pulleys  on  an  intermediate  shaft. 
This  shaft  is  again  driven  from  the  main  shaft  by  pulleys  of  the  following  relative  diameters : 


3 feet. 


I § in. 


| 22i  in.  | 


3 feet.  | 


The  diameters  of  these  pulleys  are  to  each  other  as  the  first  to  the  fifth  speed  of  the  bar,  so  that  the 
smaller  is  to  the  larger  pulley  as  ■J  ZZZ  : i/812  = 1 : T56.  The  increase  of  speed  from  the  largest 


LATHE. 


201 


LATHE. 


202 


f 

I 


i 


LATHE. 


203 


to  the  smallest  pulley  on  the  spindle  H is  as  the  first  to  the  fourth  speed,  and  the  diameters  of  the 
pulleys  are  v/’333  : ^/'650  = 19  : 2GJ. 

The  first  eight  speeds  are  obtained  with  the  wheels  d and  c,  the  second  eight  with  the  wheels  b and 
f,  and  the  third  eight  by  geering  g and  h,  disengaging  e and  c,  and  taking  the  pinion  i out  of  geer  with 
the  large  internal  wheel  on  the  face-plate  by  shifting  the  shaft  p towards  the  shaft  o. 


Driving  Wheels, 


a, .. 

b, .. 

c,  . 
e , .. 

d, .. 
9,-- 
A,. 
i,  .. 
A,., 


Numbers  of  Teeth  in  Wheels. 

Feed  Wheels.  No.  of  Teeth. 

/,  external, 64 

l,  internal, 64 

m 64 

n, 36 

q , 35 

Pinion  on  traverse  ) , „ 

r it 


No.  of  Teeth. 

24 

52 

40 

14 

64 

34 

40 

15 

144 


The  speeds  produced  by  the  wheels  e d and  b c are  to 
each  other  as  the  first  to  the  ninth  speed  of  the  chuck ; 
therefore,  64  X 52  -r-  14  X 40  = 5'94  nearly. 

The  boring  speed  being  about  7 feet  per  minute,  the 
slowest  speed,  viz.,  § of  a revolution  per  minute,  would 

84  X 3 

cut  a cylinder  of  80  inches  diameter = 80.  All 

J ■ 3T416 

the  cylinder  boring  speeds  are  in  the  first  eight  of  the 
table,  the  others  are  for  turning  and  polishing  heavy 
articles,  such  as  large  cylinder  covers. 

Another  modification  of  the  boring-lathe  is  seen  in  the 
vertical  boring-mill  of  J.  P.  Morris  & Co.,  of  Philadelphia. 

A modification  of  the  reaming  and  boring-lathe  may 
be  seen  in  the  vertical  boring-mill  built  in  the  Washing- 
ton Navy  Yard,  under  the  direction  of  Wm.  M.  Ellis.  This 
is  essentially  the  same  as  the  boring-mill  of  J.  P.  Morris 
tk  Co.,  of  Philadelphia. 

Pig.  2551,  elevation  of  the  mill. 

A,  crane  for  lifting  the  work. 

B,  driver  of  boxing-shaft. 

C,  skeleton-frame  to  support  cylinder. 

D,  frame  to  support  upper  end  of  cylinder. 

E,  horizontal  chucking-plate. 

F,  cone  of  pulleys. 

a,  feed-geering  for  boring-head. 

Fig.  2552,  section. 

E,  chucking-plate. 

F,  cone  of  pulleys. 

a,  horizontal  shaft  transferring  mo- 
tion by  bevel-pinion  to  upright  shaft  b, 
which  drives  the  chucking-plate  by  a 
pinion. 

c,  small  shaft  for  feed  motion  to  slide- 
rest. 

d,  grooved  pulleys  for  feed  motion  to 
the  same. 

e,  expansion  connection  with  univer- 
sal joints  at  each  end  to  convey  motion 
of  worm  and  rack  to  upright  man- 
drel  L 

f brace  to  support  counterbalance 
geering  g. 

h,  cone  supporting  counterbalance. 

i.  hexagon  mandrel  counterbalance. 

Fig.  2554.  G,  cast-iron  frame  to  sup- 
port upper  end  of  boring-shaft. 

Fig.  2555  shows  the  stand  or  bed 
indicated  by  letter  C,  Fig.  2551,  on 
which  the  cylinder  rests  which  is  to  be 
bored  out. 

Fig.  2556  shows  a guide,  indicated  by 
D,  Fig.  2551,  which  is  placed  upon  top 
oi  cylinder,  and  serves  as  guide  for  bor- 
ing-bar. The  boring-bar  is  then  con- 
nected to  the  revolving-plate,  as  shown 


: 

! 

ii 

t 

204 


LATHE. 


in  B and  E,  Fig.  2551,  and  turns  with  it.  The  boring-head  which  holds  the  cutters  is  shown  at  G,  and  it 
connected  with  two  screws  nearly  the  whole  length  of  boring-bar,  set  in  grooves  and  moving  with  the  bar 
and  shown  by  dotted  lines,  which  screws  regulate  the  descent  or  feed,  as  it  is  termed,  of  the  boring-head 


On  the  upper  end  of  the  boring-bar  shown  at  a,  Fig.  2552,  is  placed  the  geer  by  which  the  proper  mo- 
tion is  given  to  the  feeding-screws.  On  the  end  of  each  feeding-screw  is  placed  a small  pinion,  which 
peers  into  the  inner  teeth  of  a wheel  which  is  loose  on  the  top  of  boring-bar,  and  of  course  does  not  turn 

2553. 


with  it.  This  wheel  has  teeth  on  the  inner  and  outer  sides  of  its  periphery ; the  outer  teeth  geer  into 
one  of  a set  of  two  wheels  which  turn  together,  and  are  placed  on  a fixed  pivot,  independent  of  the 
boring-bar.  The  upper  wheel  of  this  set  geers  into  the  upper  wheel  a,  which  is  keyed  to  the  boring- 


LATHE. 


205 


bar,  and  of  course  turns  with  it.  The  amount  of  feed,  or  the  advance  of  the  feeding-screw,  is  due  to  the 
difference  of  the  velocities  which  are  given  to  the  wheels  a and  m.  This  difference  of  the  velocities  of 
these  two  wheels  may  be  varied  by  varying  the  diameter  of  the  wheels  a and  m. 


The  geering  shown  above  the  top  of  the  boring-bar  is  for  hoisting  up  the  boring-bar,  when  the  ma- 
cnine  is  to  be  used  for  planing  a flat,  or  taming  a cylindrical  or  conical  surface.  The  machine,  aa 
trranged  for  this  purpose,  is  shown  in  Fig.  2552. 


2558. 


The  cutting-tool  is  attached  to  the  bar  i,  in  which  a rack  is  cut,  into  the  teeth  of  which  a pinion  geers, 
which  pinion  is  moved  by  a perpetual  screw  on  the  bar ; by  this  arrangement  the  vertical  motion  is 
given  to  the  tool.  The  method  of  producing  the  lateral  motion  of  the  tool  by  the  screw  h is  shown  by 
the  figure,  and  does  not  need  explanation. 

Fig.  2557,  H,  cross-bar  and  bearing  for  upper  end  of  shaft  of  chuck-plate. 


20G 


LAP  AND  LEAD  OF  THE  SLIDE -VALVE. 


2559. 


LAP  AND  LEAD  OF  THE  SLIDE-VALVE.  The  slide-valve  is  that  part  of  a steam-engins 
which  causes  the  motion  of  the  piston  to  be  reciprocating.  It  is  made  to  slide  upon  a smooth  surface, 
called  the  cylinder  face,  in  which  there  are  three  openings  to  as  many  pipes  or  passages  : two  for  the 
admission  of  steam  to  the  cylinder,  above  and  below  the  piston,  alternately  ; while  the  use  of  the  third 
is  to  convey  away  the  waste  steam.  The  first  two  are,  therefore,  termed  the  induction  or  steam  ports, 
and  the  remaining  one  the  eduction  or  exhaustion  port. 

The  slide  is  inclosed  in  a steam-tight  case,  called  the  slide-jacket;  and  motion  is  communicated  to 
it  by  means  of  a rod  working  through  a stuffing-box. 

The  steam  from  the  boilet  f.rst  enters  the  jacket,  and  thence  passes  into  the  cylinder,  through  either 
steam  port,  according  to  the  position  of  the  slide,  which  is  so  contrived  that  steam  cannot  pass  from  the 
jacket  to  the  cylinder  through  both  steam  ports  at  the  same  time,  or  through  the  eduction  port  at  any 
time. 

Case  1. — When  a Slide  has  neither  Lead  nor  Lap. — Fig.  2559  represents  the  cylinder  face  for  a “ Mur- 
ray slide”  without  lap ; a and  b being  the  induction  ports,  and  c the  eduction. 

Figs.  2560,  2561,  and  2562,  are  similar  sections  of  the  nosle, 
showing  the  slide  in  its  central  and  two  extreme  positions.  It 
occupies  the  mid-position,  Fig.  2560,  when  the  piston  is  at  either 
extremity  of  its  stroke ; the  extreme  position,  Fig.  2561,  when 
the  piston  is  at  half  stroke  in  its  descent ; and  that  shown  in  Fie. 

2562,  when  the  piston  is  at  half-stroke  in  its  ascent. 

When  a slide  has  no  lap,  the  width  of  its  facing,  at/ and  j, 

Fig.  2560,  equals  that  of  the  steam  ports ; the  lap  being  any 
additional  width  'whereby  those  ports  are  overlapped. 

That  the  waste  steam  may  have  unobstructed  egress,  the  ex- 
haustion port  c must  be  made  of  no  less  width  than  the  steam  ports ; and,  for  the  same  reason,  the  bars 
d and  e should  correspond  with  the  slide  face  at  / and  g.  The  three  ports,  together  with  the  bars  be- 
tween and  beyond  them,  are  therefore  drawn  of  equal  width ; the  total  length  of  the  slide  being  equal 
to  the  distance  between  the  steam  sides  of  the  steam  ports. 

The  distance  through  which  the  slide  moves,  in  passing  from  one  extreme  position  to  the  other,  is 
called  its  travel ; which,  in  this  case,  equals  twice  the  port. 

When  the  motion  of  a slide  is  produced  by  means  of  an  eccentric,  keyed  to  the  crank-shaft  and  re- 
volving with  it,  the  relative  positions  of  the  piston  and  slide  depend  upon  the  relative  positions  of  tha 
crank  and  eccentric. 


ra 

d 

L_l_] 


Demonstration. 


2503. 


Let  ab,  Fig.  2563,  represent  the  crank;  then  b being  the  crank-pin,  and  a the 
centre  of  motion,  the  larger  circle  represents  the  orbit  of  the  crank,  and  its  diame- 
ter b c the  stroke  of  the  piston.  Supposing  the  cylinder  to  be  an  upright  one,  hav- 
ing the  crank-shaft  immediately  above  or  below  it,  the  connection  between  the  pis- 
ton-rod and  crank  being  merely  a connecting-rod,  without  the  intervention  of  a 
beam,  it  is  evident  that  when  the  position  of  the  crank  is  a b,  the  piston  will  be  at 
the  top  of  the  cylinder,  and  at  the  bottom  when  its  position  is  a c.  The  relative  po- 
sitions of  the  crank  and  piston,  at  any  point  of  the  stroke  between  the  two  extremes, 
depend  upon  the  length  of  the  connecting-rod  : for  the  present,  however,  let  us  sup- 
pose the  connecting-rod  to  be  of  infinite  length,  and  therefore  always  acting  upon 
the  crank  in  parallel  lines,  so  that  when  the  crank  is  at  d,  e will  be  the  apparent  position  of  the  piston, 
and /the  same  when  the  crank  is  at  g ; the  piston  being  represented  by  the  sine  of  the  arc  described 
by  the  crank  from  either  of  the  points  b and  c,  in  the  direction  of  the  arrow. 

'The  diameter  h i,  of  the  inner  circle  of  the  figure,  represents  the  travel  of  the  slide,  and  its  radius 
the  eccentricity  of  the  eccentric  ; or,  regarding  the  eccentric  as  a crank,  the  radius  may  be  said  to  rep- 
resent that  crank,  as  a b represents  the  main  crank.  The  travel  of  a slide,  without  lap,  being  equal  to 
twice  the  port,  the  two  steam  ports  are  represented  by  the  spaces  a h and  a i,  but  transposed,  a i being 
the  passage  to  the  top  of  the  cylinder,  and  a h that  to  the  bottom. 

Supposing  the  piston  to  be  at  b,  (the  top  of  the  cylinder,)  the  position  of  the  slide  will  be  that  shown 
in  Fig.  2560,  the  direction  of  its  motion  being  downward,  so  that  the  port  a.  Fig.  2560,  or  a i in  Fig. 
2563,  may  be  gradually  opened  for  the  admission  of  steam  above  the  piston,  until  the  pi:  ton  has 
arrived  at  half-stroke,  when  it  will  be  fully  open,  as  shown  in  Fig.  2561.  The  direction  of  th ) slide’s 
motion  is  then  reversed,  so  that  when  the  piston  has  completed  its  descent,  the  port  b,  Figs  2559  to 
2562,  or  ah  in  the  diagram,  will  begin  to  open  for  the  admission  of  steam  beneath  it,  and  exhaustion 
will  commence  from  above  it  through  the  port  a,  or  a i,  and  exhaustion  port  c,  the  slide  beii  g again 
brought  into  its  central  position,  Fig.  2560. 

Now  the  slide  being  at  half-stroke,  when  the  piston  is  at  either  extremity  of  its  stroke,  if  wo  make 
a b the  position  of  the  crank,  a k will  be  that  of  the  eccentric  ; and  the  axis  of  the  crank  being  likewise 
that  of  the  eccentric,  they  must  necessarily  revolve  in  equal  times,  and  always  at  the  same  distance 
apart ; therefore,  when  the  crank  has  reached  the  point  d (supposing  it  to  move  in  the  direction  of  the 
arrow)  the  eccentric  will  have  advanced  to  I,  and  e d and  l m represent  the  positions  of  the  piston  and 
slide  respectively;  showing,  that  when  the  piston  has  descended  to  e,  the  steam  port  ai , Fig.  2563, 
or  a,  Figs.  2559  to  2562,  will  be  open  to  the  extent  am.  Again,  when  the  crank  is  at  n,  and  the  piston 
consequently  at  half-stroke,  a i will  be  the  position  of  the  eccentric,  the  port  a i being  fully  open,  and 
the  slide  occupying  the  extreme  position  shown  in  Fig.  2561.  The  direction  of  the  slide’s  motion  is  now 
reversed,  and  the  port  is  again  gradually  covered  by  the  slide  face  until  the  positions  of  the  crank  and 
eccentric  are  ac  and  ao,  when  the  piston  will  have  completed  its  descent,  and  the  port  ai  will  be  com- 
pletely closed,  the  slide  being  again  brought  into  its  central  position,  Fig.  2560.  The  opposite  stearr 


LAP  AND  LEAD  OF  THE  SLIDE-VALVE. 


207 


port  a h now  begins  to  open  for  the  admission  of  steam,  and  the  direction  of  the  piston’s  motion  is  re- 
versed ; the  port  continues  to  open  until  the  crank  and  eccentric  reach  the  points  p and  h,  when  the 
piston  will  again  be  at  half-stroke,  and  the  slide  in  its  extreme  position,  Fig.  2562.  Meanwhile,  exhaus- 
tion from  above  the  piston  has  been  taking  place,  to  the  same  extent,  through  the  port  a i.  Finally,  the 
piston  having  completed  its  ascent,  the  slide  again  occupies  its  original  position,  Fig.  2560,  and,  its 
course  being  downward,  steam  is  again  admitted  into  the  cylinder,  through  the  port  a ; the  piston  then 
begins  to  descend,  and,  at  the  same  instant,  exhaustion  ceases  from  above,  and  commences  from  below 
it,  through  the  port  b. 

It  is  sometimes  urged  against  the  use  of  the  eccentric,  as  a means  of  actuating  the  slide,  that  the 
steam  ports  are  opened  and  closed  too  slowly ; but  it  must  be  remembered  that  the  piston  does  not 
move  at  a uniform  velocity,  as  the  crank  does  ; for  example,  while  the  crank  describes  the  arc  b d,  the 
piston  descends  only  from  b to  e,  the  versed  sine  of  that  arc ; and  its  velocity  is  gradually  increased  as 
it  approaches  the  middle  of  its  stroke,  where  it  is  greatest,  being  equal  to  that  of  the  crank.  Again,  as 
the  piston  approaches  the  end  of  its  stroke,  its  velocity  is  diminished  in  the  same  ratio  as  that  in  which 
it  had  previously  increased,  until  the  completion  of  its  stroke,  where  it  remains  stationary  during  the 
small  space  of  time  in  which  the  direction  of  its  motion  is  reversed. 

Now,  it  must  be  obvious  that  less  steam  is  required  to  impel  the  piston  at  a slow  rate  than  at  a rapid 
one  ; and  a glance  at  Fig.  2363  shows  that  the  steam  admitted  into  the  cylinder,  when  the  slide  is  actu- 
ated by  an  eccentric,  is  at  all  times  proportioned  to  the  velocity  of  the  piston,  the  port  being  least  open 
when  the  piston  is  near  the  end  of  its  stroke,  and  fully  open  when  it  is  at  half-stroke. 

When  an  eccentric,  instead  of  being  set,  as  in  the  preceding  case,  so  that  the  steam  port  shall  only 
begin  to  open  when  the  piston  commences  its  stroke,  is  so  placed  that  the  port  shall  be  open  to  some 
extent  prior  to  the  commencement  of  the  stroke,  the  width  of  that  opening  is  termed 

The  Lead. — The  non-use  of  lead  is  disadvantageous,  chiefly  because  at  the  commencement  of  every 
stroke,  the  steam  has  to  contend  with  the  whole  force  of  that  which  had  impelled  the  piston  during  its 
previous  stroke.  But  besides  obviating  that  disadvantage,  the  lead  is  of  essential  service  in  locomotive 
engines,  “where  it  is  found  necessary  to  let  the  steam  on  to  the  opposite  side  of  the  piston  before  the 
end  of  its  stroke,  in  order  to  bring  it  up  gradually  to  a stop,  and  diminish  the  violent  jerk  that  is  caused 
by  its  motion  being  changed  so  very  rapidly  as  five  times  in  a second.  The  steam  let  into  the  end  of 
a cylinder  before  the  piston  arrives  at  it,  acts  as  a spring  cushion  to  assist  in  changing  its  motion ; and 
if  it  were  not  applied,  the  piston  could  not  be  kept  tight  upon  the  piston-rod.” 

Case  2. — When  a slide  has  lead  without  lap. — Let  a b,  Fig.  2564,  represent  the  stroke  of  the  piston  ; 
c d the  travel  of  the  slide  ; and  ef  the  lead;  then,  supposing  the  piston  to  be  at  the  top  of  the  cylinder, 
ea  is  the  position  of  the  crank,  and  eg  that  of  the  eccentric.  Following  the  course 
of  the  crank,  in  the  direction  of  the  arrow,  we  find  tire  port  e d fully  open,  not,  as  in 
the  former  case,  when  the  piston  is  at  half-stroke,  but  when  it  has  descended  to  the 
point  k, — the  arc  a i,  described  by  the  crank,  being  equal  to  the  arc  g d,  described 
by  the  eccentric.  Again,  we  find  the  port  reclosed  when  the  piston  has  descended 
to  i',  at  which  point  exhaustion  commences  from  above  the  piston  through  e d,  and 
steam  enters  belov  it  through  e c,  for  the  return  stroke,  at  the  commencement  of 
which  the  port  e c is  open  to  the  extent  e l (equal  to  cf)  for  the  admission  of  steam, 
while  e d is  open  to  the  same  extent  for  exhaustion. 

It  is  to  be  remarked,  that  the  amount  of  lead  is  necessarily  very  limited  in  prac- 
tice, its  tendency  being  to  arrest  the  progress  of  the  piston  before  the  completion  of  its  stroke.  Tho 
greatest  possible  amount  of  lead  equals  half  the  travel  of  the  slide.  The  eccentric  would  in  that  case 
be  set  diametrically  opposite  to  its  first  position,  which  would  have  the  effect  of  reversing  the  direction 
of  the  piston’s  motion. 

In  the  case  of  a slide  having  lead  without  lap,  the  distance  of  a piston  from  the  end  of  its  stroke, 
when  the  lead  produces  its  effect,  is  proportional  to  the  lead  as  the  versed  sine  of  an  arc  is  to  its  sine, 
supposing  the  radii  of  the  crank  and  eccentric  to  be  equal. 


Demonstration. 

Let  a b,  Fig.  2565,  represent  both  the  travel  of  the  slide  and  the  piston’s  stroke;  2565. 

then  c a and  c b represent  the  steam  ports.  And  let  c d represent  the  lead  ; then  c a 
and  ce  represent  the  crank  and  eccentric,  the  piston  being  at  the  top  of  the  cylinder. 

Now,  steam  will  enter  the  cylinder,  below  the  piston,  when  the  eccentric  is  at  f and 
the  crank  at  g ; for  the  arcs  a eg,  and  c bf  are  equal.  Again,  the  arc  g b is  equal  to 
h e ; therefore,  i g is  equal  to  k e,  and  i b to  k h.  Now,  k e is  the  sine  of  the  arc  li  e, 
and  k h (equal  to  i b)  is  its  versed  sine  : hence 

Rule  I. — To  find  the  distance  of  the  piston  from  the  end  of  its  stroke,  when  the 
lead  produces  its  effect : — Divide  the  lead  by  the  width  of  the  steam  port,  both  in  inches,  and  call  the 
quotient  sine  ; multiply  its  corresponding  versed  sine,  found  in  the  table,  by  half  the  stroke,  and  the 
product  will  be  the  distance  of  the  piston  from  the  end  of  its  stroke,  when  steam  is  admitted  for  the 
return  stroke,  and  exhaustion  commences.  Or, 

Rule  II. — To  find  the  lead,  the  distance  of  the  piston  from  the  end  of  its  stroke  being  given  : — Divide 
the  distance  in  inches  by  half  the  stroke  in  inches,  and  call  the  quotient  versed  sine  ; multiply  its  cor- 
responding sine  by  the  width  of  steam  port,  and  the  product  will  be  the  lead. 

Example  l.--The  stroke  of  a piston  is  48  inches  ; width  of  steam  port  2^  inches ; and  lead  l inch  r 
required  the  distance  of  the  piston  from  the  end  of  its  stroke,  when  exhaustion  commences. 

Here,  -5  ~ 2'5  — -2  = sine  ; and  versed  sine  of  sine  '2  = '0202. 

Then,  -0202  X 24  ;=  -4848  inches. 


208 


LAP  AND  LEAD  OF  THE  SLIDE-VALVE. 


Example  2. — The  stroke  of  a piston  is  48  inches ; width  of  steam  port  25  inches  ; and  distance  o* 
piston  from  the  end  of  its  stroke,  when  exhaustion  commences,  -4848  inches : required  the  lead. 

Here,  -4848  — 24  = -0202  = versed  sine  ; 
and  sine  of  versed  sine  '0202  = -2. 

Then,  -2  X 2 5 = '5  =lead. 

When  the  lead  of  a slide  is  equal  to  the  widtli  of  steam  port  multiplied  by  any  number  in  the  first 
column  of  the  following  table,  the  distance  of  the  piston  from  the  end  of  its  stroke,  when  steam  is 
admitted  on  the  exhaust-side,  will  be  equal  to  half  the  stroke  multiplied  by  the  corresponding  number 
of  the  second  column.  Or,  if  the  distance  of  the  piston  from  the  end  of  its  stroke,  when  steam  is  ad- 
mitted on  the  exhaust-side,  be  equal  to  half  the  stroke  multiplied  by  any  number  in  the  second  column, 
the  width  of  steam  port  multiplied  by  the  corresponding  number  of  the  first  column  equals  the  lead. 


When  the  lead  is  equal  to 
the  width  of  steam  port 
multiplied  by 


0625 

('•0019 

09375 

■0044 

125 

•0078 

1875 

•0176 

21875 

The  distance  of  the  piston 

■0242 

25 

from  the  end  of  its  stroke, 

•0317 

28125 

when  steam  is  admitted  _ 

•0403 

3125 

on  the  exhaust-side, 

•0501 

34375 

equals  half  the  stroke 

•0609 

375 

multiplied  by 

•0730 

40625 

•0862 

4375 

•1008 

46875 

•1166 

5 

T339 

The  Lap. — A slide  is  said  to  have  lap  when  the  width  of  its  face  is  greater  than  that  of  the  steam 
ports,  the  ports  being  thereby  overlapped,  as  in  Fig.  2569. 

It  is  to  be  remarked  that  slides  should  have  some  degree  of  lap  on  both  the  steam  and  exhaustion 
sides  of  the  passage,  because,  although  in  theory  an  aperture  may  be  said  to  be  completely  closed  when 
covered  by  a bar  of  similar  width,  yet,  in  the  construction  of  a slide  without  lap,  we  cannot  insure  such 
accuracy  of  Jit  as  to  preclude  the  possibility  of  steam  entering  or  leaving  both  steam  ports  at  the  san 
time. 

Lap  on  the  steam  side  has  the  effect  of  cutting  off  the  steam  from  the  cylinder,  by  closing  the  pon 
before  the  completion  of  the  stroke,  the  remainder  of  the  stroke  being  effected  by  the  expansion  of  the 
steam  already  admitted. 

Demonstration. 

Case  3. — When  a slide  has  lap  on  the  steam  sick,  without  lead. — Let  ah  and  he,  Fig.  2566,  represent 
the  lap  at  both  ends  of  the  slide ; and  let  a d and  c e represent  the  two  steam  ports ; then  d e will  repre- 
sent the  travel  of  the  slide,  which,  in  this  case,  equals  twice  the  steam  port,  plus  twice  the  lap. 


Supposing  d e also  to  represent  the  stroke  of  the  piston,  and  that  the  piston  is  on  the  top  stroke,  then 
b d and  bf  are  the  respective  positions  of  the  crank  and  eccentric ; for  the  slide,  instead  of  occupying 
its  central  position,  when  the  piston  is  at  the  end  of  its  stroke,  (as  in  Case  1,)  must  be  set  in  advance  of 
that  position  to  the  extent  of  the  lap,  that  steam  may  enter  the  cylinder  when  the  piston  begins  to 
move.  See  Fig.  2567. 

When  the  eccentric  has  advanced  from  f to  e,  the  crank  will  have  reached  the  point  g ; the  piston  is 
therefore  at  a when  the  port  c e is  fully  open,  the  slide  being  then  in  the  position  Fig.  2568.  Again, 
when  the  eccentric  has  reached  the  point  h,  the  port  c e will  be  reclosed.  Fig.  2567,  and  i will  be  the 
position  of  the  piston ; therefore,  the  distance  of  the  piston  from  the  end  of  its  stroke,  when  the  steam  is 
cut  off,  is  proportioned  to  the  whole  stroke,  as  i e is  to  d e. 

When  the  eccentric  arrives  at  k,  the  slide  will  occupy  its  central  position,  Fig.  2569,  and  the  piston 
will  be  at  in,  vjhere  exhaustion  commences  from  above  it ; but  steam  is  not  admitted  below  it,  for  the 
return  stroke,  until  the  eccentric  has  reached  the  point  n,  where  the  port  o d begins  to  open,  the  position 
of  the  slide  at  that  moment  being  that  shown  in  Fig.  2570. 

When  the  eccentric  arrives  at  d,  the  port  will  be  fully  open,  the  slide  being  then  in  its  extreme  posi- 
tion, Fig.  2571 ; and  it  will  be  reclosed  when  the  eccentric  arrives  at  g,  and  the  piston  at  p,  where  the 
steam  is  cut  off,  the  position  of  the  slide  being  again  that  shown  in  Fig.  2570.  Again,  when  the  eccen- 


LAI'  AND  LEAD  OF  THE  SLIDE-VALVE. 


209 


trie  reaches  the  point  r,  exhaustion  ceases  from  above  the  piston,  which  is  then  at  s,  and  commences 
from  below  it,  the  slide  being  then  in  its  central  position,  Fig.  2569,  and  moving  downward.  Finally, 
the  crank  having  arrived  at  d,  and  the  eccentric  at/,  the  piston  will  have  completed  its  ascent,  and  the 
slide  will  occupy  the  position,  Fig.  2567,  as  at  starting. 

The  steam  was  shown  to  be  cut  off  when  the  piston  had  descended  from  d to  i,  the  crank  having 
described  the  arc  dgu,  and  the  eccentric  the  arc fell.  Now,  di  is  the  versed  sine  of  dgu,  and  ec  is 
the  versed  sine  of  half  fe  h ; and  dgu  and  f e h are  equal  arcs.  Hence 

Rule  III. — To  find  at  what  part  of  the  stroke  steam  will  be  cut  off  with  a given  amount  of  lap  : — 
Divide  the  width  of  steam  port,  by  itself,  plus  the  lap,  and  call  the  quotient  versed  sine.  Find  its  cor 
responding  arc  in  degrees  and  minutes,  and  call  it  arc  the  first.  If  arc  the  first  be  less  than  45  degrees, 
multiply  the  versed  sine  of  twice  that  arc  by  half  the  stroke  in  inches,  and  the  product  will  be  the  Jis 
tance  of  the  piston  from  the  commencement  of  its  stroke,  when  the  steam  is  cut  off. 

If  arc  the  first  exceed  45  degrees,  multiply  the  versed  sine  of  the  difference  between  double  that  arc 
and  180  degrees  by  half  the  stroke,  and  the  product  will  be  the  distance  of  the  piston  from  the  end  of 
its  stroke  when  the  steam  is  cut  off. 

Rule  IV. — To  find  the  amount  of  lap  necessary  to  cut  off  the  steam  at  any  given  part  of  the  stroke  : — 

If  it  be  required  to  cut  off  the  steam  before  half-stroke,  divide  the  distance  the  piston  moves  before 
steam  is  cut  off,  by  half  the  stroke,  and  call  the  quotient  versed  sine.  Find  the  arc  of  that  versed  sine, 
and  also  the  versed  sine  of  half  that  arc.  Divide  the  difference  between  the  versed  sine  last  found  and 
unity,  by  the  versed  sine,  and  multiply  the  width  of  steam  port  by  the  quotient ; the  product  will  be 
the  lap. 

If  if  be  required  to  cut  off  the  steam  at  a point  beyond  half-stroke,  divide  the  distance  of  the  piston 
from  the  end  of  its  stroke,  when  steam  is  cut  off,  by  half  the  length  of  stroke  ; call  the  quotient  versed 
sine;  find  its  corresponding  arc,  and  abstract  it  from  180  degrees.  Find  the  versed  sine  of  half  the 
remainder,  and  subtract  it  from  unity.  Divide  the  remainder  by  the  versed  sine,  and  multiply  the 
width  of  the  steam  port  by  the  quotient ; the  product  will  be  the  lap. 

Example  3. — The  stroke  of  a piston  is  36  inches;  width  of  steam  port  1-J-  inch  ; and  lap  6 inches  : 
required  the  point  of  the  stroke  at  which  steam  will  be  cut  off. 

Here  T5  -f-  6 ==7'5  ; and  T5  ~ 7'5  —-2  — versed  sine; 

arc  of  vereed  sine  ’2  = 36°  52',  (arc  the  first ;) 
and  36°  52'  X '2  = 73°  44'  = are  of  versed  sine,  '7198. 

Then  -7198  X 18  ==  12'95  inches  = distance  of  the  piston  from  the  commencement  of  its  stroke  when 
the  steam  is  cut  off. 

Example  4. — The  stroke  of  a piston  is  36  inches ; width  of  steam  port  1 ^ inch  ; and  extent  of  lap  l} 
inch : required  the  point  of  the  stroke  at  which  steam  is  cut  off. 

Here  1'5  -f-  T25  =:  2'75  ; and  1-5  —•  2'75  = '5454  = versed  sine  of  arc  62°  58'  (arc  the  first.) 

Then  62°  58'  X 2 = 125°  56' ; and  180° -125°  56'  = 54°  4'  = arc  of  versed  sine,  -4131;  '4131  X 
18  = 7'43  inches  = distance  of  the  piston  from  the  end  of  its  stroke  when  the  steam  is  cut  off. 

Example  5.— The  stroke  of  a piston  is  36  inches ; width  of  steam  port  T5  inches  ; and  distance  of  the 
piston  from  the  commencement  of  its  stroke,  when  che  steam  is  cut  off,  12'95  inches  : required  the  lap. 
Here  12'95  -fr  18  = -7198  = versed  sine  of  arc  73°  44'  ; 

* 73°  44'  -7-  2 = 36°  52'  = arc  of  versed  sine  -2. 

Then  1 — '2  = -8  ; and  '8  -f • 2 — 4 ; T5  X 4 = 6 inches  = lap. 

The  Lead  and  Lap. — Having  separately  investigated  the  two  cases  of  a slide  having  lead  without 
lap,  and  lap  without  lead,  we  now  proceed  to  consider  the  effect  of  both  in  combination,  together  with 
that  of  lap  on  the  exhaustion  side. 

Demonstration. 

Case  4.—  When  a slide  has  lap  on  both  the  steam  and  exhaustion  sides,  together  with  lead. — Let 
a b and  a c,  Fig.  2572,  represent  the  double  lap  on  the  steam  side;  af 
and  a g,  the  same  on  the  exhaustion  side ; b e and  c,  d the  steam  ports ; 
and  the  line  ed  both  the  travel  of  the  slide  and  stroke  of  the  piston. 

Then,  supposing  c h to  represent  the  lead  of  the  slide,  a i will  be  the  po- 
sition of  the  eccentric  when  that  of  the  crank  is  ae\  the  slide  occupving 
the  position  shown  in  Fig.  2573,  and  the  piston  being  at  the  top  of  its 
downward  stroke. 

When  the  eccentric  reaches  the  point  k,  the  port  c d will  be  fully  closed, 
as  shown  in  Fig.  2574,  and  the  piston  will  have  descended  to  l,  the  arc 
e m being  equal  to  the  arc  i k.  Again,  when  the  eccentric  arrives  at  n, 
the  slide  being  then  brought  into  the  position  Fig.  257  5,  exhaustion  com- 
mences from  above  the  piston,  which  has  descended  to  o ; the  arc  e mp 
being  equal  to  the  arc  i k n.  When  the  eccentric  arrives  at  q,  the  port  b t 
begins  to  open  for  the  admission  of  steam  beneath  the  piston,  (see  Fig. 

2576,)  which  has  then  descended  to  r;  the  arc  eins  being  equal  to  the 
arc  ikq.  When  the  eccentric  has  reached  the  point  i ',  opposite  to  i,  the  port  be  will  be  open  to  the 
extent  of  the  lead  b h',  equal  to  c h,  and  the  piston  will  have  completed  its  descent. 

Steam  continues  to  enter  the  port  b e during  the  ascent  of  the  piston,  until  the  eccentric  reaches  the 
point  k',  when  the  port  b e will  be  reclosed,  Fig.  257  6,  the  direction  of  the  slide’s  motion  being 
downward,  and  the  piston  having  ascended  to  V.  Exhaustion  ceases  from  above  the  piston  when  the 
eccentric  reaches  the  point  t,  the  piston  being  then  at  u,  and  the  slide  again  in  the  position  Fig.  2575. 

Von.  _ II. — 11 


2572. 


■210 


LAP  AND  LEAD  OF  THE  SLIDE-VALVE. 


When  the  eccentric  reaches  (lie  point  n',  opposite  to  n,  exhaustion  commences  below  the  piston,  the 
slide  being  then  in  the  position  Fig.  2577,  and  the  piston  at  o'.  Finally,  when  the  eccentric  reaches 
the  point  q',  and  the  crank  the  point  s',  opposite  to  s,  steam 
begins  to  enter  the  port  ccl  for  the  return  stroke,  at  the  com- 
mencement of  which  the  port  c d will  be  open  to  the  extent 
of  the  lead  c h ; the  crank  and  eccentric  occupying  their  original 
positions  a e and  a i. 

It  is  here  shown  that  four  distinct  circumstances  result  from 
the  use  of  a slide  having  lap  on  both  sides  of  the  port,  with 
lead,  during  a single  stroke  of  the  piston.  These  are — 

First : The  cutting  off  the  steam,  for  the  purpose  of  expan- 
sion. 

Second:  The  cessation  of  exhaustion  on  the  exhaustion  side. 

Third:  The  commencement  of  exhaustion  on  the  steam  side. 

Fourth  : The  readmission  of  steam  for  the  return  stroke. 

With  regard  to  the  first  of  these  results,  we  found  the  steam  port  cd  closed,  when  the  crank  and 
eccentric  had  described  the  equal  arcs  e m and  i dk.  Now,  c d , the  steam  port,  is  the  versed  sine  of  d k ; 
and  h d , the  steam  port  minus  the  lead,  is  the  versed  sine  of  i d.  Hence, 

Rule  V. — To  find  the  point  of  the  stroke  at  which  steam  will  be  cut  off : 

Divide  the  width  of  the  steam  port,  and  also  that  width  minus  the  lead,  by  half  the  slide’s  travel,  and 
call  the  quotients  versed  sines.  Find  their  corresponding  arcs,  and  call  them  arc  the  first,  and  arc  the 
second,  respectively.  'Then,  if  the  sum  of  those  arcs  be  less  than  90  degrees,  multiply  the  versed  sine 
of  their  sum  by  half  the  stroke,  in  inches,  and  the  product  will  be  the  distance  of  the  piston  from  the 
commencement  of  its  stroke,  when  the  steam  is  cut  off. 

If  the  sum  of  arcs  the  first  and  second  exceed  90  degrees,  subtract  it  from  180  degrees;  and  the 
versed  sine  of  the  difference,  multiplied  by  half  the  stroke,  equals  the  distance  of  the  piston  from  the 
end  of  its  stroke,  when  the  steam  is  cut  off. 

Example  8. — The  stroke  of  a piston  is  60  inches ; the  width  of  steam  port  8 inches  ; lap  on  the  steam 
side  2£  inches ; lap  on  the  exhaust  side  £th  inch ; and  lead  -J-  inqb  : required  the  point  of  the  stroke  at 
which  steam  will  be  cut  off. 


2573.  2574.  2575.  2576.  2577. 


Here 


3 

3 + 2-5 


•5454  = versed  sine  of  62°  58'  (arc  the  first;) 


3— -5 

and  = -4545  = versed  sine  of  56°  57'  (arc  the  second.) 

Then  62c  58' + 56°  57'  = 119°  55';  and  180°  — 119°  55'  = 60  5'  = arc  of  versed  sine,  -5012. 
•5012  X 30  = 15-036  inches  = distance  of  the  piston  from  the  end  of  its  stroke  when  the  steam  is  cut  off. 

Exhaustion  was  shown  to  cease,  during  the  ascent  of  the  piston,  when  the  eccentric  had  reached  the 
point  t,  and  the  crank  the  point  x ; the  crank  having  described  the  arc  dk  x,  equal  to  i'  e t described  by 
the  eccentric. 

Now  i'  e is  equal  to  arc  the  second,  (Rule  V. ;)  and  e t is  equal  to  90  degrees  minus  1 1\  or  the  arc  ol 
versed  sine  ef;  and  e f is  half  the  slide’s  travel  minus  the  lap  on  the  exhaust  side.  Hence, 

To  find  the  point  of  the  stroke  at  which  exhaustion  ceases : . 

Divide  half  the  slide’s  travel,  minus  the  exhaustion  lap,  by  half  the  travel,  call  the  quotient  versed 
eine,  and  add  its  corresponding  arc,  calling  it  arc  the  third,  to  arc  the  second.  The  versed  sine  of  the 
difference  between  their  sum  and  180  degrees,  multiplied  by  half  the  stroke,  equals  the  distance  of  the 
piston  from  the  end  of  its  stroke  when  exhaustion  ceases. 

Example  9. — The  several  proportions  being  as  in  the  preceding  example. 

Here  3 + 2-5  = 5 -5  = half  the  slide’s  travel ; 

5'5  — T25 

and  — = '9772  = versed  sine  of  arc  88°  42'  = (arc  the  third.) 

oo  v 

Then  83°  42' + 56°  57'  (arc  the  second)  = 145°  39';  and  180°  — 145°  39  ' = 34°  21'  = arc  ot 
versed  sine,  T743.  T743  X 30  = 5p229  inches  =the  distance  of  the  piston  from  the  end  of  its  stroke 
when  exhaustion  ceases. 

Exhaustion  was  shown  to  commence  from  above  the  piston  when  the  crank  and  eccentric  had  de- 
scribed the  equal  arcs  e k'  p and  idn. 

Now  i d n is  equal  to  1 80  degrees  minus  ni' ; n i'  is  equal  to  n'  i ; and  n' d is  equal  to  arc  the  third. 
Hence, 

To  find  the  distance  of  the  piston  from  the  end  of  its  stroke  when  exhaustion  commences : 

Subtract  arc  the  second  from  arc  the  third,  and  multiply  the  versed  sine  of  their  difference  by  half  the 
stroke.  The  product  will  be  the  distance  required. 

Example  10. — 'The  proportions  being  as  in  the  two  preceding  examples. 

Here  88°  42'  — 56°  57'  =31°  45'=arc  of  versed  sine,  ‘1496;  and  T496  X 30  = 4’488  inches,  the 
distance  required. 

Steam  was  found  to  be  readmitted,  for  the  return  stroke,  when  the  piston  had  reached  the  point  r 
tn  its  descent,  the  crank  and  eccentric  having  described  the  equal  arcs  e k' s and  i d q. 

Now  i dq  is  equal  to  180  degrees  minus  q V ; i'  being  diametrically  opposed  to  i.  And  q V is  equal 
to  i q',  the  difference  between  arcs  the  first  and  second.  Hence, 

To  find  the  distance  of  the  piston  from  the  end  of  its  stroke  when  steam  is  readmitted  for  the  returr 
-troke 


LAP  AND  LEAD  OF  THE  SLIDE-VALVE. 


211 


Multiply  the  versed  sine  of  the  difference  between  arcs  the  first  and  second  by  half  the  stroke,  and 
the  product  will  be  the  distance  required. 

Example  11. — The  proportions  being  as  before. 

Here  62°  58'  — 56°  57' = 6°  1 ' = arc  of  versed  sine  '0055. 

Then  '0055  X 30  = '165  inches  = the  distance  required. 

RuleVI.-^ To  find  the  proportions  of  the  steam  lap  and  lead ; the  points  of  the  stroke  where  steam  is 
cut  oftl  and  readmitted  for  the  return  stroke,  being  known  : 

When  the  steam  is  cut  off  before  half-stroke,  divide  the  portion  of  the  stroke  performed  by  the  piston 
by  half  the  stroke,  and  call  the  quotient  versed  sine.  Likewise,  divide  the  distance  of  the  piston  from 
the  end  of  its  stroke  when  steam  is  readmitted  for  the  return  stroke,  by  half  the  stroke,  and  call  that 
quotient  versed  sine.  Find  their  respective  arcs,  and  also  the  versed  sines  of  half  their  sum  and  hall 
their  difference.  The  width  of  the  steam  port  in  inches,  divided  by  the  versed  sine  of  half  their  sum, 
equals  half  the  travel  of  the  slide  : and  half  the  travel,  minus  the  width  of  port,  equals  the  lap.  The 
difference  of  the  two  versed  sines  last  found,  multiplied  by  half  the  travel  of  the  slide,  equals  the  lead. 

When  the  steam  is  to  be  cut  off  after  half-stroke,  divide  the  distance  of  the  piston  from  the  end  of  its 
stroke  by  half  the  stroke  ; call  the  quotient  versed  sine,  and  subtract  its  corresponding  arc  from  180 
degrees.  Divide  the  distance  the  piston  has  to  move  when  the  steam  is  admitted  for  the  return  stroke, 
by  half  the  stroke  ; call  the  quotient  versed  sine,  and  find  its  corresponding  arc.  Then  proceed  with  the 
two  arcs  thus  found,  as  in  the  former  case. 

Example  12. — The  stroke  of  a piston  is  60  inches  ; the  width  of  steam  port  3 inches  ; distance  of  the 
piston  from  the  end  of  its  stroke  when  steam  is  cut  off  15'036  inches  ; and  when  steam  is  admitted  for 
the  return  stroke  T65  inches:  required  the  lap  and  lead. 

Here  15'036  = 30  = '5012  = versed  sine  of  arc  60°  5' ; 
and  180°  — 60°  5'  = 119°  55'. 

Then  T65  -f-  30  = '0055  = versed  sine  of  6°  1*. 

119°  55' + 6°  1'  = 125°  56';  119°  55'  — 6°  l'  = 113°  54'. 

1 OSO  K Cl 

— = 62°  58'  = arc  of  versed  sine  '5454 ; 

o 


113°  54' 

■ — p = 56°  67'  = arc  of  versed  sine  ’4545. 

3 -i-  '5454  = 5'5  inches  = half  the  slide’s  travel ; 
and  5'5  — 3 = 2'5  = lap. 

'5454  — '4545  = '0909  ; and  '0909  X 5'5  = '5  inches  = lead. 

To  find  the  lap  and  lead  by  construction. 

The  stroke  of  the  piston  ; width  of  steam  port ; and  distances  of  the  piston  from  the  end  of  its  stroke 
when  the  steam  is  cut  off,  and  when  it  is  readmitted  for  the  return  stroke,  being  known : 

Let  the  circle,  Fig.  2578,  represent  the  crank’s  orbit,  and  its  diameter  a b the  stroke  of  the  piston,  to 
some  known  scale.  Make  a c equal  to  the  part  of  (he  stroke  performed 
before  the  steam  is  cut  off;  and  b d equal  to  the  distance,  of  the  piston 
from  the  end  of  its  stroke  when  steam  is  readmitted  for  the  return  stroke. 

Draw  d e and  ef  at  right  angles  to  a b,  and  mark  the  point  g at  the  dis- 
tance be  from/.  Bisect  the  arc  ag,  and  from  the  point  of  bisection,  h, 
draw  the  diameter  h i.  Make  ik  equal  to  b e ; draw  i m and  kl  at  right 
angles  to  a b ; and  draw  * l and  i b indefinitely.  From  the  point  m set  off 
m n equal  to  the  width  of  steam  port,  full  size  ; from  n draw  n o parallel 
to  i m,  and  meeting  i b,  and  also  op  parallel  to  a b,  and  meeting  h i ; then 
will  sp  equal  the  lap,  and  s r the  lead. 

In  all  the  foregoing  cases,  we  have  taken  the  versed  sine  of  the  arc  de- 
scribed by  the  crank,  from  either  extremity  of  the  stroke,  as  the  portion 
of  the  stroke  performed  by  the  piston  ; but,  as  has  been  already  observed, 
the  relative  positions  of  the  piston  and  crauk  depend  upon  the  length  of 
the  connecting-rod,  which  will  be  seen  by  reference  to  Fig.  2579,  where 
A B represents  the  stroke  of  the  piston,  C D the  connecting-rod,  and  D 0 the  crank.  Now,  by  supposing 
a d to  be  the  arc  described  by  the  crank  when  the  piston  has  performed  one-fourth  of  its  stroke,  and 
from  the  length  of  that  arc,  calculating  the  amount  of  lap  re- 
quired to  cut  off  the  steam  at  that  part  of  the  stroke,  we  appear 
to  be  in  error— for,  from  the  oblique  action  of  the  connecting-rod, 
the  piston  would  have  descended  only  to  the  point  c.  But  the 
engine  being  double-acting,  we  have  to  take  into  consideration 
the  position  of  the  crank  when  the  piston  has  performed  one- 
fourth  of  its  stroke  in  the  opposite  direction  from  the  point  B ; 
and  here  we  find,  that  by  supposing  the  crank  to  have  described 
the  arc  b e,  (equal  to  a d,)  instead  of  the  true  arc  b E,  we  cause 
the  steam  to  be  cut  off  when  the  piston  has  reached  the  point/ ; 
and  the  distance  B / being  precisely  as  much  more  than  B F as  A c is  less  than  A C,  the  seeming  error 
is  self-corrective. 


2579. 


212 


LEAD. 


A Table  of  Multipliers  to  find  the  Lap  and  Lead,  when  the  Steam  is  to  be  cut  off  at  \ to  |(/u 

of  the  Stroke. 

The  lap  must  be  equal  to  the  width  of  the  steam  port  multiplied  by  col.  1. 

The  lead  must  be  equal  to  the  width  of  the  steam  port  multiplied  by  col.  2. 


Half-Stroks. 

Five-Eighths 
of  the  Stroke. 

Three-Fourths 
of  the  Stroke. 

Seven-Eighths 
of  the  Stroke. 

1 

2 

i 

2 

1 

2 

i 

2 

Lap 

2-41 

Lead 

*000 

Lap 

1-58 

Lead 

•ooo 

Lap 

1.000 

Lead 

■ooo 

Lap 

•540 

Lead 

•ooo 

3§£ 

•ooooo 

2T6 

•145 

T41 

T24 

•893 

T05 

•477 

•089 

op-g 

•00208 

206 

•198 

T35 

T70 

•851 

T46 

•450 

T23 

3 ,3, 

•00416 

T94 

•268 

1-27 

•231 

•795 

•200 

•413 

T70 

§!| 

■00833 

1-8-1 

•318 

1-21 

•276 

■754 

•240 

■385 

•204 

•01250 

T77 

•358 

TIG 

•312 

■723 

•271 

■363 

■232 

•01666 

1-71 

•391 

112 

■342 

•691 

•299 

■344 

■257 

2 

■02083 

1-65 

•420 

T08 

•368 

•66S 

■322 

•327 

■277 

5 1 ; 
11? 

•02500 

1-60 

■444 

T05 

•391 

•644 

•343 

•313 

■296 

•02916 

1-56 

•467 

T02 

•412 

•623 

•362 

•298 

•313 

•03333 

T48 

•505 

•968 

•449 

•586 

•396 

•273 

■343 

O M- 

— o 

•04166 

1-41 

•540 

•921 

■480 

•554 

•425 

•251 

•370 

•05000 

1'35 

■570 

•881 

■508 

•526 

•451 

•232 

■393 

° g 1 

•05833 

1-30 

■595 

■844 

•532 

500 

•473 

•215 

•414 

8 Z 

Ilf 

•06666 

T25 

•617 

•810 

•554 

■476 

•495 

T98 

•434 

•07500 

1-21 

■638 

■779 

•572 

•454 

•514 

T83 

■452 

•08333 

1.17 

•657 

•751 

•592 

■434 

•532 

T60 

•468 

■09166 

1-13 

•674 

•724 

•607 

•415 

■648 

T56 

•483 

•10000 

Example  of  its  application. — Stroke  36  inches ; width  of  port  2 inches ; steam  to  be  cut  off  at  half- 
stroke ; distance  of  the  piston  from  the  end  of  its  stroke  when  steam  is  readmitted  for  the  return  stroke* 
To  inch. 

1-5 

— = 0833.  Find  that  number,  or  the  one  nearest  to  it,  in  the  right  hand,  or  last  column,  and  take 
out  the  multipliers  on  the  same  line  under  the  head.  Half-stroke. 

Then  2 X T21  = 2’42  inches  = the  lap. 

And  2 X '638  = T276  inches  = the  lead. 

LEAD — A well-known  metal  much  used  in  the  arts.  Lead  unites  with  most  of  the  metals,  has  little 
elasticity,  and  is  the  softest  of  them  all.  Gold  and  silver  are  dissolved  by  it  in  a slight  red  heat,  but 
when  the  heat  is  much  increased  the  lead  separates,  and  rises  to  the  surface  of  the  gold,  combined  with 
all  heterogeneous  matters ; hence  lead  is  made  use  of  in  the  art  of  refining  the  precious  metals.  If  lead 
be  heated  so  as  to  boil  and  smoke,  it  soon  dissolves  pieces  of  copper  thrown  into  it ; the  mixture,  when 
cold,  being  brittle.  The  union  of  these  two  metals  is  remarkably  slight,  for  upon  exposing  the  mass  to 
a heat  no  greater  than  that  in  which  lead  melts,  the  lead  almost  entirely  runs  off  by  itself. 

Among  the  ores  of  lead  some  have  a metallic  aspect ; are  black  in  substance,  as  well  as  when  pulver- 
ized ; others  have  a stony  appearance,  and  are  variously  colored,  with  usually  a vitreous  or  greasy 
lustre.  The  specific  gravity  of  the  latter  ores  is  always  less  than  5.  The  whole  of  them,  excepting  the 
chloride,  become  more  or  less  speedily  black,  with  sulphureted  hydrogen  or  with  hydrosulphurets  ; and 
are  easily  reduced  to  the  metallic  state  upon  charcoal,  with  a flux  of  carbonate  of  soda,  after  they  have 
been  properly  roasted.  They  diffuse  a whitish  or  yellowish  powder  over  the  charcoal,  which,  according 
to  the  manner  in  which  the  flame  of  the  blowpipe  is  directed  upon  it,  becomes  yellow  or  red ; thus 
indicating  the  two  characteristic  colors  of  the  oxides  of  lead. 

The  lead  ores  most  interesting  to  the  arts  are : 

1.  Galena,  sulphuret  of  lead.  This  ore  has  the  metallic  lustre  of  lead,  with  a crystalline  structure 
derivable  from  the  cube.  When  heated  cautiously  at  the  blowpipe  it  is  decomposed,  the  sulphur  flies 
off,  and  the  lead  is  left  alone  in  fusion  ; but  if  the  heat  be  continued,  the  colored  surface  of  the  charcoal 
indicates  the  conversion  of  the  lead  into  its  oxides.  Galena  is  a compound  of  lead  and  sulphur,  in  equiv- 
alent proportions,  and  therefore  consists,  in  100  parts,  of  86|  of  metal,  and  13  j of  sulphur,  with  which 
numbers  the  analysis  of  the  galena  of  Clausthal  by  Westrumb  exactly  agrees.  Its  specific  gravity, 
when  pure,  is  7-56.  Its  color  is  blackish  gray,  without  any  shade  of  red,  and  its  powder  is  black — char- 
acters which  distinguish  it  from  blende,  or  sulphuret  of  zinc. 

2.  The  seleniuret  of  lead  resembles  galena,  but  its  tint  is  bluer.  Its  chemical  characters  are  the  only 
ones  which  can  be  depended  on  for  distinguishing  it.  At  the  blowpipe  it  exhales  a very  perceptible 
smell  of  putrid  radishes.  Nitric  acid  liberates  the  selenium.  When  heated  in  a tube,  oxide  of  selenium 
sf  a carmine  red  rises  along  with  selenic  acid,  white  and  deliquescent.  The  specific  gravity  of  this  ore 
caries  from  6'8  to  7'69. 

3.  Native  minium  or  red  lead  has  an  earthy  aspect,  of  a lively  and  nearly  pure  red  color,  but  some- 
times inclining  to  orange.  It  occurs  pulverulent,  and  also  compact,  with  a fracture  somewhat  lamellar 
When  heated  at  the  blowpipe  upon  charcoal,  it  is  readily  reduced  to  metallic  lead.  Its  specific  gravity 
varies  from  46  to  8'9.  This  ore  is  rare. 


LEAD. 


213 


4.  Plornb-gomme. — This  lead  ore,  as  singular  in  appearance  as  in  composition,  is  of  a dirty  brownish 
yr  orange-yellow,  and  occurs  under  the  form  of  globular  or  gum-like  concretions.  It  has  also  the  lustre 
and  translucency  of  gum,  with  somewhat  of  a pearly  aspect  at  times.  It  is  harder  than  fluor  spar.  It 
oonsists  of  oxide  of  lead,  40  ; alumina,  37  ; water,  18'8  ; foreign  matters  and  loss,  406  ; in  100.  Hith- 
erto it  has  been  found  only  at  Huelgoet,  near  Poullaouen,  in  Brittany,  covering  with  its  tears,  or  small 
concretions,  the  ores  of  white  lead  and  galena  which  compose  the  veins  of  that  lead  mine. 

6.  White  lead , carbonate  of  lead. — This  ore,  in  it's  purest  state,  is  colorless  and  transparent,  like  glass, 
with  an  adamantine  lustre.  It  may  be  recognized  by  the  following  characters : 

Its  specific  gravity  is  from  6 to  6-7  ; it  dissolves  with  more  or  less  ease,  and  with  effervescence,  in 
nitric  acid ; becomes  immediately  black  by  the  action  of  sulphureted  hydrogen,  and  melts  on  charcoal 
before  the  blowpipe  into  a button  of  lead.  According  to  Klaproth,  the  carbonate  of  Leadhills  contains 
82  parts  of  oxide  of  lead,  and  16  of  carbonic  acid,  in  98  parts.  This  mineral  is  tender,  scarcely  scratches 
calc-spar,  and  breaks  easily,  with  a waved  conchoidal  fracture.  It  possesses  the  double  refracting  prop- 
erty in  a very  high  degree ; the  double  image  being  very  visible  on  looking  through  the  flat  faces  of  the 
prismatic  crystals.  Its  crystalline  forms  are  very  numerous,  and  are  referrible  to  the  octahedron,  and 
the  pyramidal  prism. 

6.  Vitreous  lead , or  sulphate  of  lead. — This  mineral  closely'  resembles  carbonate  of  lead;  so  that  the 
external  characters  are  inadequate  to  distinguish  the  two.  But  the  following  are  sufficient.  When 
pure,  it  has  the  same  transparency  and  lustre.  It  does  not  effervesce  with  nitric  acid;  it  is  but  feebly 
blackened  by  sulphureted  hydrogen , it  first  decrepitates  and  then  melts  before  the  blowpipe  into  a 
transparent  glass,  which  becomes  milky  as  it  cools.  By  the  combined  action  of  heat  and  charcoal,  it 
passes  first  into  a red  pulverulent  oxide,  and  then  into  metallic  lead.  It  consists,  according  to  Klaproth, 
of  71  oxide  of  lead,  26  sulphuric  acid,  2 water,  and  1 iron.  That  specimen  was  from  Anglesea;  the 
Wanlockhead  mineraMs  free  from  iron.  The  prevailing  form  of  crystallization  is  the  rectangular  octa- 
hedron, whose  angles  and  edges  are  variously  modified.  The  sulphato-carbonate,  aud  sulphato  tri-car- 
bonate of  lead,  now  called  Leadhillite,  are  rare  minerals  which  belong  to  this  head. 

7.  Phosphate  of  lead. — This,  like  all  the  combinations  of  lead  with  an  acid,  exhibits  no  metallic  lustre, 
but  a variety  of  colors.  Before  the  blowpipe  upon  charcoal,  it  melts  into  a globule  externally  crystal- 
line, which,  by  a continuance  of  the  heat,  with  the  addition  of  iron  and  boracic  acid,  affords  metallic  lead. 
Its  constituents  are  80  oxide  of  lead,  18  phosphoric  acid,  and  T6  muriatic  acid,  according  to  Klaproth's 
analysis  of  the  mineral  from  Wanlockhead.  The  constant  presence  of  muriatic  acid  in  the  various 
specimens  examined  is  a remarkable  circumstance.  The  crystalline  forms  are  derived  from  an  obtuse 
rhomboid.  Phosphate  of  lead  is  a little  harder  than  white  lead ; it  is  easily  scratched,  and  its  powder  is 
always  gray.  Its  specific  gravity  is  6'9.  It  has  a vitreous  lustre,  somewhat  adamantine.  Its  lamellar 
texture  is  not  very  distinct ; its  fracture  is  wavy,  and  it  is  easily  frangible.  The  phosphoric  and  arsenic 
acids  being,  according  to  M.  Mitscherlich,  isomorphous  bodies,  may  replace  each  other  in  chemical  com- 
binations in  every  proportion,  so  that  the  phosphate  of  lead  may  include  any  proportion,  from  the 
smallest  fraction  of  arsenic  acid  to  the  smallest  fraction  of  phosphoric  acid,  thus  graduating  indefinitely 
into  arseniate  of  lead.  The  yellowish  variety  indicates,  for  the  most  part,  the  presence  of  arsenic  acid. 

8.  Muriate  of  lead.  Horn-lead,  or  murio-carbonate. — This  ore  has  a pale  yellow  color,  is  reducible  to 
metallic  lead  by  the  agency  of  soda,  and  is  not  altered  by  the  hydrosulphurets.  At  the  blowpipe  it 
melts  first  into  a pale  yellow  transparent  globule,  with  salt  of  phosphorus  and  oxide  of  copper ; and  it 
manifests  the  presence  of  muriatic  acid  by  a bluish  flame.  It  is  fragile,  tender,  softer  than  carbonate  of 
lead,  and  is  sometimes  almost  colorless,  with  an  adamantine  lustre.  Specific  gravity,  606.  Its  constit- 
uents, according  to  Berzelius,  are  lead,  25'84;  oxide  of  lead,  67'07 ; carbonate  of  lead,  6'25-,  chlorine, 
8'84;  silica,  T46  ; water,  0'54  ; in  100  parts.  The  carbonate  is  an  accidental  ingredient,  not  being  in 
equivalent  proportion.  Klaproth  found  chlorine,  13'67  ; lead,  39'98  ; oxide  of  lead,  22'57  ; carbonate  of 
lead,  23  78. 

9.  Arseniate  of  lead. — Its  color  of  a pretty  pure  yellow,  bordering  slightly  on  the  greenish,  and  its 
property  of  exhaling  by  the  joint  action  of  fire  and  charcoal  a very  distinct  arsenical  odor,  are  the  only 
characters  which  distinguish  this  ore  from  the  phosphate  of  lead.  The  form  of  the  arseniate  of  lead, 
when  it  is  crystallized,  is  a prism  with  six  faces,  of  the  same  dimensions  as  that  of  phosphate  of  lead. 
When  pure,  it  is  reducible  upon  charcoal,  before  the  blowpipe,  into  metallic  lead,  with  the  copious  exha- 
lation of  arsenical  fumes  ; but  only  in  part,  and  leaving  a crystalline  globule,  when  it  contains  any  phos- 
phate of  lead.  The  arseniate  of  lead  is  tender,  friable,  sometimes  even  pulverulent,  and  of  specific  grav- 
ity 5-04.  That  of  Johann-Georgenstadt  consists,  according  to  Rose,  of  oxide  of  lead,  77'5  ; arsenic  acid, 
12-5;  phosphoric  acid,  7'5,  and  muriatic  acid,  T5. 

10.  Red  lead,  or  chromate  of  lead. — This  mineral  is  too  rare  to  require  consideration  in  the  present 
work. 

11.  Plomb  vauquelinite.  Chromate  of  lead  and  copper. 

1 2.  Yellow  lead.  Molgbyate  of  lead. 

1 3.  Tungstate  of  lead. 

Having  thus  enumerated  the  several  species  of  lead  ore,  we  may  remark  that  galena  is  the  only  one 
which  occurs  in  sufficiently  great  masses  to  become  the  object  of  mining  and  metallurgy.  This  mineral 
is  found  in  small  quantity  among  the  crystalline  primitive  rocks,  as  granite.  It  is,  however,  among  the 
oldest  talc-schists  and  clay  slates  that  it  usually  occurs. 

Treatment  of  the  ores  of  lead. — The  mechanical  operations  performed  upon  the  lead  ores,  to  bring  them 
to  the  degree  of  purity  necessary  for  their  metallurgic  treatment,  may  be  divided  into  three  classes, 
whose  objects  are : 

1.  The  sorting  and  cleansing  of  the  ores  ; 

2.  The  grinding ; 

3;  The  washing,  properly  so  called. 

The  apparatus  subservient  to  the  first  objects  are  sieves,  running  buddies,  and  gratings.  The  large 


214 


LEAD. 


sieves  employed  for  sorting  the  ore  at  the  mouth  of  the  mine,  into  coarse  and  fine  pieces,  is  a wire  gauza 
of  iron ; its  meshes  are  square,  and  an  inch  long  in  each  side.  There  is  a lighter  sieve  of  wire  gauze, 
similar  to  the  preceding,  for  washing  the  mud  from  the  ore,  by  agitating  the  fragments  in  a tub  filled 
with  water.  But  instead  of  using  this  sieve,  the  pieces  of  ore  are  sometimes  merely  stirred  about  with 
a shovel,  in  a trough  filled  with  water. 

The  method  of  sorting  and  cleansing  the  ore  consists  in  using  a plane  surface  made  of  slabs  or  planks, 
very  slightly  inclined  forwards,  and  provided  behind  and  on  the  sides  with  upright  ledges,  the  back  one 
having  a notch  to  admit  a stream  of  water.  The  ore  is  merely  stirred  about  with  a shovel,  and  exposed 
on  the  slope  to  the  stream.  For  this  apparatus,  formerly  the  only  one  used,  the  following  has  been  sub- 
stituted, called  the  grate.  It  is  a grid,  composed  of  square  bars  of  iron,  an  inch  thick,  by  from  24  to  32 
inches  long,  placed  horizontally  and  parallelly  to  each  other,  an  inch  apart.  There  is  a wooden  canal 
above  the  grate,  which  conducts  a stream  of  water  over  its  middle  ; and  an  inclined  plane  is  set  beneath 
it,  which  leads  to  a hemispherical  basin,  about  24  inches  in  diameter,  for  collecting  the  metallic  powder 
washed  out  of  the  ore. 

The  apparatus  subservient  to  grinding  the  ore  are : 

1.  The  beater,  formed  of  a cast-iron  plate,  3 inches  square,  with  a socket  in  its  upper  surface,  foi 
receiving  a wooden  handle.  In  some  localities  crushing  cylinders  have  been  substituted  for  the  beater. 

At  the  mines,  the  knocker's  workshop,  or  striking  floor,  is  provided  either  with  a strong  stool,  or  a 
wall  3 feet  high,  beyond  which  there  is  a flat  area  4 feet  broad,  and  a little  raised  behind.  On  this 
area,  bounded,  except  in  front,  by  small  walls,  the  ore  to  be  bruised  is  placed.  On  the  stool,  or  wall, 
a very  hard  stone  slab,  or  cast-iron  plate  is  laid,  7 feet  long,  7 inches  broad,  and  14  inches  thick,  called 
a knok-stone.  The  workmen,  seated  before  it,  break  the  pieces  of  mixed  ore  with  the  beater. 

Crushing  machines  are  in  general  use  in  England,  to  break  the  mingled  ores,  which  they  perform  with 
great  economy  of  time  and  labor.  They  have  been  employed  there  for  nearly  forty  years. 

This  machine  is  composed  of  one  pair  of  fluted  cylinders,  and  of  two  pairs  of  smooth  cylinders,  which 
serve  altogether  for  crushing  the  ore.  The  two  cylinders  of  each  of  the  three  pairs  turn  simultaneously 
in  an  inverse  direction,  by  means  of  two  toothed- wheels  upon  the  shaft  of  every  cylinder,  which  work 
by  pairs  in  one  another.  The  motion  is  given  by  a single  wafer-wheel.  One  of  the  fluted  cylinders  is 
placed  in  the  prolongation  of  the  shaft  of  this  wheel,  which  carries  besides  a cast-iron  toothed-wheel, 
geared  with  the  toothed-wheels  fixed  upon  the  ends  of  two  of  the  smooth  cylinders.  Above  the  fluted 
cylinders,  there  is  a hopper,  which  discharges  down  between  them  the  ore  brought,  forwards  by  the  wag- 
ons. These  wagons  advance  upon  a railway,  stop  above  the  hopper,  and  empty  their  contents  into  it 
through  a trap-hole,  which  opens  outwardly  in  the  middle  of  their  bottom.  Below  the  hopper  there  is  a 
small  bucket  called  a shoe,  into  which  the  ore  is  shaken  down,  and  which  throws  it  without  ceasing  upon 
the  cylinders.  The  sho'e  is  so  regulated  that  too  much  ore  can  never  fall  upon  the  cylinders,  and  ob- 
struct their  movement.  A small  stream  of  water  is  likewise  led  into  the  shoe,  which  spreads  over  the 
cylinders,  and  prevents  them  from  growing  hot.  The  ore,  after  passing  between  the  fluted  rollers,  falls 
upon  inclined  planes,  which  turn  it  over  to  one  or  other  of  the  pairs  of  smooth  rolls. 

These  are  the  essential  parts  of  this  machine ; they  are  made  of  iron,  and  the  smooth  ones  are  case- 
hardened,  or  chilled,  by  being  cast  in  iron  moulds.  The  gudgeons  of  both  kinds  move  in  brass  brushes 
fixed  upon  iron  supports  made  fast  by  bolts  to  the  strong  wood- work  base  of  the  whole  machine.  Each 
of  the  horizontal  bars  has  an  oblong  slot,  at  one  of  whose  ends  is  solidly  fixed  one  of  the  plummer-blocks 
or  bearers  of  one  of  the  cylinders,  and  in  the  rest  of  the  slot  the  plummer-block  of  the  other  cylinder 
slides  ; a construction  which  permits  the  two  cylinders  to  come  into  contact,  or  to  recede  to  such  a dis- 
tance from  each  other  as  circumstances  may  require.  The  movable  cylinder  is  approximated  to  the 
fixed  one  by  means  of  iron  levers,  which  carry  at  their  ends  weights,  and  rest  upon  wedges  susceptible 
of  adjustment.  These  wedges  press  the  iron  bar,  and  make  it  approach  the  movable  cylinder  by 
advancing  the  plummer-block  which  supports  its  axis.  When  matters  are  so  arranged,  should  a very 
large  or  hard  piece  present  itself  to  one  of  the  pairs  of  cylinders,  one  of  the  rollers  would  move  away  and 
let  the  piece  pass  without  doing  injury  to  the  mechanism. 

Besides  the  three  pairs  of  cylinders  which  constitute  essentially  each  crushing  machine,  there  is  some- 
times a fourth,  which  serves  to  crush  the  ore  when  not  in  large  fragments. 

The  stamp-mill  is  employed  in  concurrence  with  the  crushing  cylinders.  It  serves  particularly  to 
pulverize  those  ores  whose  gangue  is  too  hard  to  yield  readily  to  the  rollers,  and  also  those  which  being 
already  pulverized  to  a certain  degree,  require  to  be  ground  still  more  finely.  (See  Stampers.) 

The  sifting  meshes  of  the  sieve  are  made  of  strong  iron  wire,  three-eighths  of  an  inch  square.  This 
sieve  is  suspended  at  the  extremity  of  a forked  lever,  or  brake,  turning  upon  an  axis  by  means  of  two 
upright  arms  about  5 feet  long,  which  are  pierced  with  holes  for  connecting  them  with  bolts  or  pins, 
both  to  the  sieve-frame  and  to  the  ends  of  the  two  branches  of  the  lever.  These  two  arms  are  made 
of  wrought  iron,  but  the  lever  is  made  of  wood,  as  it  receives  the  jolt.  Each  jolt  not  only  makes  the 
fine  parts  pass  through  the  meshes,  but  changes  the  relative  position  of  those  which  remain  on  the  wires, 
bringing  the  purer  and  heavier  pieces  eventually  to  the  bottom.  The  mingled  fragments  of  galena,  and 
the  stony  substances  lie  above  them ; while  the  poor  and  light  pieces  are  at  top.  These  are  first 
scraped  oft)  next  the  mixed  lumps,  and  lastly  the  pure  ore,  which  is  carried  to  the  heap. 

The  poor  ore  is  carried  to  a crushing  machine,  where  it  is  bruised  between  two  cylinders  appropriated 
io  this  purpose ; after  which  it  is  sifted  afresh. 

Washing  apparatus. — For  washing  the  ore  after  sifting  it,  the  machine  already  described  is  employed 

Smelting  of  lead  ores. — The  lead  ores  of  England  were  anciently  smelted  in  very  rude  furnaces,  oi 
iolcs,  urged  by  the  natural  force  of  the  wind,  and  were  therefore  placed  on  the  summits  or  western 
slopes  of  the  highest  hills.  More  recently  these  furnaces  were  replaced  by  blast  hearths,  resembling 
smiths’  forges,  but  larger,  and  were  blown  by  strong  bellows,  moved  by  men  or  water-wheels.  The 
principal  operation  of  smelting  is  at  present  always  executed  there  in  reverberatory  furnaces,  and  in 
furnaces  similar  to  those  known  in  France  by  the  name  of  Scotch  furnaces 


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215 


The  reverberatory  furnaces  called  cupola  are  now  exclusively  used  in  Derbyshire  for  the  smelting  ol 
lead  ores.  In  the  works  where  the  construction  of  these  furnaces  is  most  improved,  they  are  interiorly 
8 feet  long  by  6 wide  in  the  middle,  and  2 feet  high  at  the  centre.  The  lire,  placed  at  one  of  the 
extremities,  is  separated  from  the  body  of  the  furnace  by  a body  of  masonry,  called  the  fire-bridge , 
which  is  two  feet  thick,  leaving  only  from  14  to  18  inches  between  its  upper  surface  and  the  vault. 
From  this,  the  highest  point,  the  vault  gradually  sinks  towards  the  further  end,  where  it  stands  only  6 
inches  above  the  sole.  At  this  extremity  of  the  furnace,  there  are  two  openings  separated  by  a trian- 
gular prism  oi  fire-stone,  which  lead  to  a flue,  a foot  and  a half  wide,  and  10  feet  long,  which  is  recurved 
towards  the  top,  and  runs  into  an  upright  chimney  55  feet  high.  The  above  flue  is  covered  with  stone 
slabs,  carefully  jointed  with  fire-clay,  which  may  be  removed  when  the  deposit  formed  under  them 
(which  is  apt  to  melt)  requires  to  be  cleaned  out.  One  of  the  sides  of  the  furnace  is  called  the  laborers’ 
side.  It  has  a door  for  throwing  coal  upon  the  fire-grate,  besides  three  small  apertures  each  about  6 
inches  square.  These  are  closed  with  movable  plates  of  cast-iron,  which  are  taken  off  when  the  work- 
ing requires  a freer  circulation  of  air,  or  for  the  stirring  up  of  the  materials  upon  the  hearth.  On  the 
opposite  side,  called  the  working  side,  there  are  five  apertures  ; namely,  three  equal  and  opposite  to 
those  just  described,  shutting  in  like  manner  with  cast-iron  plates,  and  beneath  them  two  other  open- 
ings, one  of  which  is  for  running  out  the  lead,  and  another  for  the  scoriae.  The  ash-pit  is  also  on  this 
side,  covered  with  a little  water,  and  so  disposed  as  that  the  grate-bars  may  be  easily  cleared  from  the 
cinder  slag. 

The  hearth  of  the  furnace  is  composed  of  the  reverberatory  furnace  slags,  to  which  a proper  shape  has 
been  given  by  beating  them  with  a strong  iron  rake,  before  their  entire  solidification.  On  the  laborers' 
side,  this  hearth  rises  nearly  to  the  surface  of  the  three  openings,  and  falls  towards  the  working  side,  so 
as  to  be  18  inches  below  the  middle  aperture.  In  this  point,  the  lowest  of  the  furnace,  there  is  a tap- 
hole,  through  which  the  lead  is  run  off  into  a large  iron  boiler,  (lea-pan,)  placed  in  a recess  left  outside 
in  the  masonry.  From  that  lowest  point,  the  sole  gradually  rises  in  all  directions,  forming  thus  an  in- 
side basin,  into  which  the  lead  runs  down  as  it  is  melted.  At  the  usual  level  of  the  metal  bath,  there 
is  on  the  working  side,  at  the  end  furthest  from  the  fire,  an  aperture  for  letting  off  the  slag. 

In  the  middle  of  the  arched  roof  there  is  a small  aperture,  called  the  crown-hole , which  is  covered  up 
during  the  working  with  a thick  cast-iron  plate.  Above  this  aperture  a large  wooden  or  iron  hopper 
stands,  leading  beneath  into  an  iron  cylinder,  through  which  the  contents  of  the  hopper  may  fall  into  the 
furnace  when  a trap  or  valve  is  opened. 

Roasting. — The  ordinary  charge  of  ore  for  one  smelting  operation  is  20  cwts.,  and  it  is  introduced 
through  the  hopper.  An  assistant  placed  at  the  back  doors  spreads  it  equally  over  the  whole  hearth 
with  a rake ; the  furnace  being  meanwhile  heated  only  with  the  declining  fire  of  the  preceding  operation. 
No  regular  fire  is  made  during  the  first  two  hours,  but  a gentle  heat  merely  is  kept  up  by  throwing  one 
or  two  shovelfuls  of  small  coal  upon  the  grate  from  time  to  time.  All  the  doors  are  closed,  and  the 
register  plate  of  the  chimney  is  lowered. 

The  outer  basin  in  front  of  the  furnace  is  at  this  time  filled  with  the  lead  derived  from  a former  pro- 
cess, the  metal  being  covered  with  slags.  A rectangular  slit,  above  the  tap-hole  is  left  open,  and  remains 
so  during  the  whole  time  of  the  operation,  unless  the  lead  should  rise  in  the  interior  basin  above  the 
level  of  that  orifice  ; in  which  case  a little  mound  must  be  raised  before  it. 

The  two  doors  in  front  furthest  from  the  fire  being  opened,  the  head  smelter  throws  in  through  them, 
upon  the  sole  of  the  furnace,  the  slags  swimming  upon  the  bath  of  lead,  and  a little  while  afterwards 
he  opens  the  tap-hole,  and  runs  off  the  metallic  lead  reduced  from  these  slags.  At  the  same  time  his 
assistant  turns  over  the  ore  through  the  back  doors.  These  being  again  closed,  while  the  above  two 
front  doors  are  open,  the  smelter  throws  a shovelful  of  small  coal  or  coke  cinder  upon  the  lead-bath, 
and  works  the  whole  together,  turning  over  the  ore  with  the  paddle  or  iron  oar.  About  three-quarters 
of  an  hour  after  the  commencement  of  the  operation,  he  throws  back  upon  the  sole  of  the  hearth  the 
fresh  slags  which  then  float  upon  the  bath  of  the  outer  basin,  and  which  are  mixed  with  coaly  matter. 
He  next  turns  over  these  slags,  as  well  as  the  ore,  with  the  paddle,  and  shuts  all  the  doors.  At  this 
time  the  smelter  runs  off  the  lead  into  the  pig-moulds. 

The  assistant  now  turns  over  the  ore  once  more  through  the  back  doors.  A little  more  than  an  hour 
after  the  operation  began,  a quantity  of  lead,  proceeding  from  the  slag  last  remelted,  is  run  off  by  the 
tap ; being  usually  in  such  quantity  as  to  fill  one-half  of  the  outer  basin.  Both  the  workmen  then  turn 
over  the  ore  with  the  paddles,  at  the  several  doors  of  the  furnace.  Its  interior  is  at  this  time  of  a dull 
red  heat:  the  roasting  being  carried  on  rather  by  the  combustion  of  the  sulphurous  ingredients,  than  by 
the  action  of  the  small  quantity  of  coal  in  the  grate.  The  smelter,  after  shutting  the  front  doors,  with 
the  exception  of  that  next  the  fire-bridge,  lifts  off  the  fresh  slags  lying  upon  the  surface  of  the  outside 
bath,  drains  them,  and  throws  them  back  into  the  furnace. 

An  hour  and  a half  after  the  commencement,  the  lead  begins  to  ooze  out  in  small  quantities  from  the 
ore  ; but  little  should  be  suffered  to  flow  before  two  hours  have  expired.  About  this  time  the  two 
workmen  open  all  the  doors,  and  turn  over  the  ore,  each  at  his  own  side  of  the  furnace.  An  hour  and 
three-quarters  after  the  beginning,  there  are  few  vapors  in  the  furnace,  its  temperature  being  very 
moderate.  No  more  lead  is  then  seen  to  flow  upon  the  sloping  hearth.  A little  coal  being  thrown  into 
the  grate  to  raise  the  heat  slightly,  the  workmen  turn  over  the  ore,  and  then  close  all  the  doors. 

At  the  end  of  two  hours,  the  first  fire  or  roasting  being  completed,  and  the  doors  shut,  the  register  is 
to  be  lifted  a little,  and  coal  thrown  upon  the  grate  to  give  the  second  fire,  which  lasts  during  25  minutes. 
When  the  doors  are  now  opened  the  inside  of  the  furnace  is  of  a pretty  vivid  red,  and  the  lead  flows 
dowm  from  every  side  towards  the  inner  basin.  The  smelter,  with  his  rake  or  paddle,  pushes  the  slags 
upon  that  basin  back  towards  the  upper  part  of  the  sole,  and  his  assistant  spreads  them  uniformly  over 
the  surface  through  the  back  doors.  The  smelter  next  throws  in,  by  his  middle  door,  a few  shovelfuls 
of  quick -lime  upon  the  lead-bath.  The  assistant  meanwhile,  for  a quarter  of  an  hour,  works  the  ore  and 
the  slags  together  through  the  three  back  doors,  and  then  spreads  them  out,  while  the  smelter  pushes 


216 


LEAD 


the  slags  from  the  surface  of  the  inner  basin  back  to  the  upper  parts  of  the  sole.  The  doors  being  nor* 
left  open  for  a little,  while  the  interior  remains  in  repose,  the  metallic  lead,  which  had  been  pushed  back 
with  the  slags,  flows  down  into  the  basin.  This  occasional  cooling  of  the  furnace  is  thought  to  be  neces- 
sary for  the  better  separation  of  the  products,  especially  of  the  slags,  from  the  lead-bath. 

In  a short  time  the  workmen  resume  their  rakes,  and  turn  over  the  slags  along  with  the  ore.  Three 
hours  after  the  commencement,  a little  more  fuel  is  put  into  the  grate,  merely  to  keep  up  a moderate 
heat  of  the  furnace  during  the  paddling.  After  three  hours  and  ten  minutes,  the  grate  being  charged 
with  fuel  for  the  third  fire,  the  register  is  completely  opened,  the  doors  are  all  shut,  and  the  furnace  is 
left  in  this  state  for  three-quarters  of  an  hour.  In  nearly  four  hours  from  the  commencement,  all  the 
doors  being  opened,  the  assistant  levels  the  surfaces  with  his  rake,  in  order  to  favor  the  descent  of  any 
drops  of  lead ; and  then  spreads  the  slags,  which  are  pushed  back  towards  him  by  the  smelter.  The 
latter  now  throws  in  a fresh  quantity  of  lime,  with  the  view,  not  merely  of  covering  the  lead-bath  and 
preventing  its  oxydizement,  but  of  rendering  the  slags  less  fluid. 

Ten  minutes  after  the  third  tire  is  completed,  the  smelter  puts  a new  charge  of  fuel  in  the  grate,  and 
shuts  the  doors  of  the  furnace  to  give  it  the  fourth  fire.  In  four  hours  and  forty  minutes  from  the  com- 
mencement, this  fire  being  finished,  the  doors  are  opened,  the  smelter  pierces  the  tap-hole  to  discharge 
the  lead  into  the  outer  basin,  and  throws  some  quick-lime  upon  the  slags  in  the  inner  basin.  He  then 
pushes  the  slags  thus  dried  up  towards  the  upper  part  of  the  hearth,  and  his  assistant  rakes  them  out 
by  the  back  doors. 

The  whole  operation  of  a smelting  shift  takes  about  four  hours  and  a half,  or  at  most  five  hours,  in 
which  four  periods  may  be  distinguished. 

1.  The  first  fire  for  roasting  the  ores,  requires  very  moderate  firing,  and  lasts  two  hours. 

2.  The  second  fire,  or  the  smelting,  requires  a higher  heat,  with  shut  doors ; at  the  end  the  slags  are 
dried  up  with  lime,  and  the  furnace  is  also  allowed  to  cool  a little. 

3.  4.  The  last  two  periods,  or  the  third  and  fourth  fires,  are  likewise  two  smeltings  or  foundings,  and 
differ  from  the  first  only  in  requiring  a higher  temperature.  The  heat  is  greatest  in  the  last.  The  form 
and  dimensions  of  the  furnace  are  calculated  to  cause  a uniform  distribution  of  heat  over  the  whole  sur- 
face of  the  hearth.  See  article  Metallurgy. 

The  lead  is  brought  from  the  smelting  works  to  any  place  where  it  is  to  be  manufactured  in  the  form 
of  “ pigs,”  each  of  which  is  an  oblong  mass,  about  three  feet  long,  six  inches  wide,  and  weighing  about 
one  hundred  weight  and  a half.  As  for  the  philosophy  of  the  wTord  “ pig,”  applied  to  the  masses  of 
lead,  we  may  remark  that  it  forms  another  curious  instance  of  the  phraseology  used  in  manufacture. 
It  appears  that  in  the  iron-manufacture,  when  the  metal  flows  from  the  furnace  in  which  it  has  been 
reduced  from  the  ore,  it  passes  into  a large  trough  excavated  in  sand,  and  from  thence  into  smaller  lat- 
eral channels  on  each  side.  This  arrangement  has  been  suggestive  of  a sort  of  simile : for  the  larger 
trough  is  called  by  the  workmen  the  “ sow,”  and  the  smaller  the  “ pigs,”  who  suck  the  metal  from  the 
“ sow  hence  proceeded  the  names  of  “ sow-metal”  and  “ pig-metal and  hence,  in  all  probability,  the 
name  of  “ pig”  is  applied  to  the  saleable  masses  both  of  iron  and  of  lead. 

The  two  principal  articles  into  which  lead  is  manufactured  are  sheet-lead  and  water-pipes ; or  at  least 
they  are  the  only  two  which  need  here  be  noticed,  since  the  comparatively  low  temperature  at  which 
the  metal  fuses,  and  the  ease  with  which  it  is  beaten  into  various  forms,  enable  the  plumber  to  modify 
it  in  various  ways.  The  sheet-lead  here  spoken  of  is  that  with  which  roofs  and  terraces  are  covered, 
and  cisterns  lined.  It  is  sometimes  made,  and  used  formerly  to  be  wholly  made,  by  pouring  the  melted 
metal  on  a flat  surface  of  sand,  in  a stratum  of  any  required  thickness  ; but  the  more  modern  method  is 
that  of  rolling,  or  “milling,”  which  we  proceed  to  describe. 

A furnace  is  provided  consisting  of  a hemispherical  melting-pot,  four  or  five  feet  in  diameter,  and 
nearly  as  much  in  depth,  heated  by  a fire  beneath,  and  covered  with  an  inclosed  cap  or  chimney  reach- 
ing above  the  roof  of  the  building,  for  the  purpose  of  conveying  away  the  deleterious  gases  engendered 
during  the  melting  of  lead.  Into  this  melting-pot  is  put  about  six  tons  (thirteen  thousand  pounds)  of 
lead,  new  and  old,  which  remains  there  till  thoroughly  melted.  During  this  time  all  the  impurities, 
being  lighter  than  the  metal,  rise  to  the  surface.  Immediately  adjoining  the  furnace  is  a cast-iron  frame, 
called  the  “ mould,”  being  a flat  vessel  about  six  or  seven  feet  square,  and  six  inches  deep.  The  bottom 
of  this  mould  is  also  of  iron,  and  the  melted  metal  is  allowed  to  flow  into  it  from  an  opened  valve  near 
the  bottom  of  the  melting-pot.  A shoot  or  trough  conveys  the  metal  from  the  furnace  to  the  mould. 
The  glistening  liquid  mass  soon  flows  out,  to  the  weight  of  about  ten  or  eleven  thousand  pounds,  the 
dross  and  impurities  being  for  the  mast  part  left  behind  in  the  melting-pot.  As,  however,  some  impuri- 
ties or  oxidized  portions  enter  the  moul  1 a subsequent  removal  becomes  necessary ; and  this  is  effected 
by  drawing  the  edge  of  a board  carefully  over  the  surface  of  the  hot  and  liquid  metal,  the  board  urging 
before  it  all  the  floating  impurities,  and  leaving  a surface  very  silvery  and  clear. 

After  some  hours  the  mass  of  lead,  technically  called  a “ plate,”  is  lifted  out  of  the  mould  by  a pow- 
erful crane,  and  placed  upon  the  machine  where  it  is  to  be  rolled  into  the  form  of  sheets.  This  machine 
is  very  peculiar  in  its  action.  It  consists  of  a long  frame  or  bench,  about  a yard  in  height,  seven  or 
eight  feet  wide,  and  probably  seventy  feet  in  length.  At  intervals  of  every  foot  or  two  are  transverse 
rollers,  all  placed  on  the  same  level,  so  that  a heavy  body  may  be  rolled  from  one  end  of  the  frame  to 
the  other  with  great  facility.  About  midway  along  the  frame  is  the  milling  or  rolling  machine,  con- 
sisting mainly  of  two  ponderous  rollers,  between  which  the  lead  is  passed : these  are  made  of  iron,  the 
upper  one  being  fifteen  or  sixteen  inches  in  diameter,  with  a weight  of  three  tons,  the  under  one  being 
the  same.  The  two  rollers  are  placed  at  any  required  distance  apart,  the  one  above  the  other,  and  are 
also  made  to  revolve  in  either  direction.  These  being  the  mechanical  arrangements,  the  process  of 
milling  proceeds  thus  : The  plate  of  lead  is  brought  between  the  rollers,  which  are  opened  so  as  only 
to  receive  the  lead  by  compressing  it;  and  the  rollers  being  made  to  rotate,  the  plate  is  drawn  in  be- 
tween them.  This  process  is  repeated  over  and  over  again,  the  plate  passing  first  from  right  to  left. 
And  then  from  left  to  right,  the  opening  between  the  rollers  being  gradually  reduced  bv  means  of  an 


LEAD. 


217 


index  and  graduated  dial-plate.  The  small  wooden  rollers  facilitate  the  motion  of  the  elongated  lead 
to  and  fro;  and  when  the  length,  obtained  by  reducing  the  thickness,  has  become  inconveniently  great, 
the  piece  is  cut  into  two,  and  each  half  milled  in  a similar  manner.  Thus  the  lead  continues  to  pass 
between  the  rollers  to  the  number  of  seven  or  eight  hundred  times,  having  its  thickness  diminished  and 
its  length  increased  by  regular  degrees.  From  800  to  400  feet  in  length,  with  a width  of  seven  or  eight, 
is  the  average  quantity  of  roofing-lead  produced  by  these  means  from  one  of  the  plates.  The  lead  is 
then  coiled  up  in  a roll,  and  in  that  form  is  sold  to  the  plumber,  who  adapts  it  to  his  various  purposes. 

The  manufacture  of  lead-pipe,  like  that  of  sheet-lead,  combines  the  processes  both  of  casting  and 
elongating,  or  drawing.  Whatever  be  the  required  diameter  and  thickness  of  the  pipe,  it  is  first  cast  in 
a short  piece  of  great  thickness,  and  then  elongated,  by  which  the  thickness  becomes  reduced.  The 
diameter  of  the  cast  piece  is,  internally,  the  same  as  that  of  the  required  pipe,  the  external  diameter 
being  that  which  undergoes  reduction.  The  first  process  is,  therefore,  to  cast  the  short  pieces  of  pipe. 
These  moulds  measure  from  two  to  four  feet  in  height,  and  are  fitted  for  casting  pipe  whose  diameter 
varies  externally  from  two  to  six  inches,  and  internally  from  half  an  inch  to  four  inches.  The  mould 
consists  of  two  semi-cylindrical  halves,  which,  on  being  brought  together,  form  the  external  contour  of 
the  pipe,  while  a spindle  or  steel  core,  running  down  the  centre  of  the  hollow  cavity,  regulates  the  in- 
ternal diameter  of  the  pipe. 

A small  melting-furnace  is  appropriated  for  the  pipe-casting,  the  lead  being  carefully  skimmed  from 
dross  while  melting ; and  when  the  fusion  is  complete  the  melted  metal  is  poured  into  the  mould,  the 
upper  end  of  which  is  open  and  the  lower  end  closed.  The  quantity  of  lead  required  for  each  mould 
varies  from  about  24  to  200  pounds,  according  to  the  thickness  of  the  pipe.  The  metal  being  solidified 
and  sufficiently  cool  for  handling,  the  two  halves  of  the  mould  are  drawn  asunder  and  the  lead  removed, 
the  technical  name  of  the  “ plug”  being  applied  to  the  short  thick  piece  of  pipe  thus  produced. 

Next  ensues  the  very  singular  method  whereby  the  plug  is  elongated  to  the  required  dimensions. 
The  “ drawing-bench”  is  a frame  about  thirty  feet  long  and  three  in  height,  having  in  the  middle  of  its 
length  mechanism  for  producing  the  elongation.  An  endless  chain  is  kept  in  constant  motion  round  two 
wheels  or  rollers,  one  near  the  end  and  the  other  near  the  middle  of  the  draw-bench,  insomuch  that  a 
hook  or  a clasp  connected  with  one  of  the  links  would  be  forcibly  drawn  along  the  bench.  A mandril, 
or  steel  rod,  corresponding  in  size  with  the  internal  diameter  of  the  pipe,  is  inserted  into  one  of  the  short 
pipes  or  plugs,  and  then  so  connected  with  the  endless  chain  as  to  be  drawn  along  the  bench  ; but  in 
its  progress  the  pipe  has  to  pass  through  a hole  in  a steel  plate,  or  die,  rather  smaller  than  the  diameter 
of  the  lead  itself,  by  which  its  external  diameter  becomes  somewhat  reduced  and  its  length  increased. 
Again  and  again  is  the  pipe,  with  its  contained  mandril,  drawn  along  the  frame,  the  die  being  exchanged 
after  each  drawing  and  replaced  by  one  of  smaller  diameter.  In  producing  a two-inch  pipe  no  fewer 
than  sixteen  dies  are  employed,  the  diameters  of  which  descend  in  a regular  series.  The  hole  through 
the  die  is  conical,  that  is,  larger  on  one  side  of  the  die  than  on  the  other,  and  the  lead  enters  the  hole 
at  the  widest  part,  whereby  a process  of  compression  is  undergone  ; but  at  a certain  point  in  the  opera- 
tions a “cutting-die”  is  introduced,  that  is,  one  wherein  the  lead  is  at  once  exposed  to  a cutting  edge, 
the  result  of  which  is  that  a thin  film  is  cut  or  scraped  from  tin?  whole  surface  of  the  pipe.  By  the 
time  that  all  tliis  routine  is  undergone  the  metal  has  become  more  dense  and  compact,  the  temperature 
so  high  as  scarcely  to  be  bearable  by  the  hand,  the  length  greatly  increased,  and  the  external  diameter 
proportionably  diminished.  After  this  the  elongated  pipe  is  removed  from  the  mandril,  and  is  then 
ready  for  disposal  to  the  plumber. 

Lead-pipe  is  also  manufactured  by  forcing  it  through  dies,  and 
the  process,  as  improved  by  Mr.  Corneil,  of  New  York,  is  thus  de- 
scribed by  him  in  the  specifications  of  his  patent : 

My  invention  consists  of  certain  improvements  in  the  arrangement 
and  combination  of  the  machinery  or  apparatus  heretofore  used  for 
similar  purposes,  and  in  the  construction  and  application  of  certain 
additional  machinery  or  apparatus,  and  the  combination  thereof  wi!h 
the  other  apparatus,  as  herein  described. 

My  machine  is  applicable  to  the  manufacture  of  pipes  and  tubes  o f 
lead,  and  such  other  metals  and  their  alloys  as  are  capable  of  being 
squeezed  or  forced  by  means  of  great  pressure  from  a cylinder  or  re- 
ceiver through  or  between  apertures,  dies,  cores,  or  mandrils,  when  in 
a solid  or  semi-fluid  state,  and  is  mainly  referable  in  its  general  con- 
struction and  purposes  to  the  machine  patented  by  Thomas  Burr  in 
Great  Britain,  and  described  in  the  first  volume  of  the  first  series  of 
the  “ London  Journal  of  Arts  and  Sciences.” 

In  my  machine  I use  the  hydraulic  press,  the  lead  cylinder  or  re- 
ceiver, the  columns  or  pillars  connecting  the  hydraulic  press  with  the 
lead  cylinder,  the  movable  ram  for  pressing  the  piston  upon  the  lead 
m the  cylinder  or  receiver,  the  dies  and  cores  to  give  the  pipes  the 
required  form,  and  calibre,  and  dimensions,  and  such  other  parts  of 
the  old  machines  as  may  be  necessary,  substantially  similar  to  the 
machine  of  the  said  Thomas  Burr. 

Fig.  2580  represents  my  invention,  showing  how,  by  different  ar- 
rangements of  the  machinery,  the  power  may  be  applied  to  the 
lead  cylinder,  which  in  this  case  is  movable,  while  the  piston  is  sta- 
tionary. 

This  figure  is  a sectional  view  of  the  hydraulic  press  and  pipe  ma- 
chinery in  which  the  long  movable  core  is  used.  In  the  figure,  A is  the  hydraulic  cylinder,  and  B the 
ram  rising  therefrom.  A cross-head  is  attached  to  the  hydraulic  cylinder  in  the  usual  manner,  and  i» 


2580. 


218 


LENS. 


connected  with  the  upper  cross-head  I,  by  means  of  the  rods  L L,  which  are  secured  at  the  top  and 
bottom  by  the  nuts  M M M M,  turned  on  the  screws  at  the  ends  of  the  rods.  On  the  top  of  the  ram  a 
head-block  C is  placed,  and  there  secured.  A foot-block  D is  attached  to  the  bottom  of  the  lead  cylin- 
der E,  and  the  head-block,  the  foot-block,  and  the  lead  cylinder  are  secured  firmly  together  by  the  bolts 
F F.  By  this  arrangement  the  lead  cylinder  will  be  moved  upwards  and  downwards  by  the  ram  of  the 
hydraulic  press.  To  the  upper  cross-head  I the  hollow  piston  H is  attached,  and  secured  by  means  of 
the  bolts  K K having  screws  and  nuts  at  the  ends.  The  die  P is  placed  in  the  lower  end  of  the  piston, 
which  is  hollowed  throughout,  and  communicates  with  the  aperture  0 made  through  the  upper  cross 
head.  The  long  movable  core  N which  is  used  in  this  case,  is  firmly  secured  to  the  head-block  of  the 
ram,  extending  upwards  through  the  centre  of  the  lead  cylinder,  and  a short  distance  above  it,  to  be 
inserted  through  the  die  in  the  end  of  the  piston.  The  position  of  the  core  is  regulated  by  means  of  the 
set-screws  G G,  four  in  number,  which  move  the  core  laterally,  and  set  it  centrally  in  the  die.  When 
all  the  parts  are  thus  arranged,  the  lead  cylinder  is  raised  up  to  the  lower  end  of  the  piston,  the  end  of 
the  core  passing  through  the  die,  and  being  there  adjusted  centrally  by  the  set-screws,  the  lead  cylinder 
is  charged,  and  the  power  of  the  press  applied. 

The  ram  is  forced  upwards,  carrying  the  lead  cylinder  before  it,  which  passes  over  the  piston.  The 
pipe  is  formed  at  the  point  of  pressure,  as  before,  passing  through  the  hollow  piston  through  the  aper- 
ture O,  and  out  at  the  top  of  the  machine.  The  core  in  this  arrangement  moves  upwards  with  the  lead 
cylinder  through  the  die  and  the  hollow  piston.  A strong  metallic  ring  is  placed  and  firmly  secured  on 
the  lower  cross-head,  encircling  the  ram  B,  to  act  as  a guide  for  the  ram,  keeping  it  steady  and  giving 
it  the  prec  se  direction. 

LENS.  In  optics,  a piece  of  glass,  or  other  transparent  substance,  having  its  two  surfaces  so  formed 
that  the  ray  s of  light  have  their  direction  changed  by  passing  through  it ; so  that  they  either  converge, 
tending  to  a point  beyond  the  lens,  or  diverge,  as  if  they  proceeded  from  a point  before  the  lens ; or 
become  parallel,  after  converging  or  diverging. 

A double  convex  lens,  Fig.  2581,  is  bounded  by  two  convex  spherical  surfaces,  whose  centres  are  on 
opposite  sides  of  the  lens.  It  is  equally  convex  when  the  radii  of  both  surfaces  (that  is,  the  distances 
from  the  centres  to  the  circumferences  of  the  circle  they  belong  to)  are  equal,  and  unequally  convex 
when  their  radii  or  distances  are  unequal. 

A plano-convex  lens,  Fig.  2582,  is  bounded  by  a plane  surface  on  one  side,  and  by  a convex  one  on 
the  other. 

A double  concave  lens,  Fig.  2583,  is  bounded  by  two  concave  spherical  surfaces  whose  centres  are  on 
opposite  sides  of  the  lens. 

A plano-concave  lens,  Fig.  258-1,  is  bounded  by  a plane  surface  on  one  side,  and  a concave  one  on 
the  other. 

A meniscus,  Fig.  2585,  is  bounded  by  a concave  and  a convex  spherical  surface  ; and  these  two  sur- 
faces meet,  if  continued. 


The  focal  distance,  or  distance  of  the  focus  from  the  surface  of  the  lens,  depends  both  upon  the  form 
of  the  lens  and  of  the  refractive  power  of  the  substance  of  which  it  is  made ; in  a glass  lens,  both  sides 
of  which  are  equally  convex,  the  focus  is  situated  nearly  at  the  centre  of  the  sphere  of  which  the  surface 
of  the  lens  forms  a portion ; it  is  at  the  distance,  therefore,  of  the  radius  of  the  sphere.  Fig.  2587. 

Plano-convex  lens  and  rays  converging. — Fig.  2586.  Lenses  that  have  one  side  flat  and  the  otner 
convex,  (plano-convex,)  have  their  focus  at  the  distance  of  the  diameter  of  a sphere,  of  which  the  convex 
surface  of  the  lens  forms  a portion,  as  represented  in  the  figure. 

According  to  some  opticians,  the  greatest  diameter  of  a lens  is  half  an  inch ; if  it  exceed  that  thickness 
they  do  not  call  it  a lens,  but  a lenticular  glass.  Lenses  are  made  either  by  blowing  or  grinding. 
Blown  lenses  are  small  globules  of  glass  melted  in  the  flame  of  a lamp ; ground  lenses  are  reduced  by 
grinding  and  polishing.  A variety  of  simple  apparatus  is  employed  in  the  processes  of  grinding  and 
polishing  lenses,  among  which  the  one  shown  in  Fig.  2588  is  much  used,  a shows  the  edge  of  a circular 
lap  or  slab,  used  for  grinding  flat  glasses  upon ; b a circular  tool  or  block,  upon  the  under  surface  of 
which  the  glasses  to  be  ground  are  cemented;  c is  a reciprocating  bar;  d a box  containing  any  weighty 
matter ; e a long  mortised  aperture  in  the  frame,  through  which  the  bar  c freely  works ; f a crank ; g a 
winch;  h a double  pulley-wheel,  the  axis  of  which  rests  in  the  block  j a single  pulley-wheel.  Now 
on  turning  the  crank  bv  the  winch  g,  the  bar  c gives  to  b an  eccentric  motion ; the  attrition  of  b on  the 
surface  of  the  lap  a being  increased  or  diminished  at  pleasure  by  increasing  or  diminishing  the  load  in 
the  box  d.  It  should  be  noticed  that  the  cord  which  passes  round  the  pulley  h is  crossed  previous  to 
its  embracing  the  periphery  of  the  pulley  i,  consequently  a motion  is  given  to  the  lap  a tire  reverse  of 
that  given  to  b,  which  is  considered  to  produce  the  best  effect  of  grinding.  The  apparatus  described  is 


LEWIS. 


2 IS 


devoted  to  the  producing  of  plane  surfaces  to  optical  glasses ; but  the  apparatus  on  the  other  side  oi 
the  machine  is,  at  the  same  time,  by  similar  arrangements,  employed  in  grinding  concave  or  convex  sur- 
faces. For  this  purpose  a variety  of  laps  and  other  tools  are  so  made  as  to  fit  on  the  bed  l,  which  bed 
is  adjustable  by  four  equidistant  screws.  The  pulley  o is  driven  by  another  band  on  the  pulley  h,  anc 
the  required  pressure  given  by  another  loaded  boxy*.  The  several  tools  used  are  screwed  on  at  m,  and 
are  adapted  for  ready  changing,  that  the  operations  may  be  performed  with  celerity. 

LEV ER.  One  of  the  Mechanical  Powers,  which  see. 

LEWIS.  When  stone  are  to  be  laid  into  masonry,  that  are  too  heavy  for  the  workmen  to  handle 


2591. 


w ithout  resort  to  machinery,  it  becomes  necessary  to  provide  means  for  suspending  them  so  as  to  leave 
the  lower  surface  and  two  of  the  joints  unobstructed.  This  is  usually  done  by  drilling  a hole  in  tha 
upper  surface,  in  which  is  placed  an  iron 
bolt  secured  by  a key.  The  bolt  has  an 
eye  or  ring,  by  which  it  may  be  attached 
to  the  machine  which  is  to  suspend  the 
stone.  This  bolt  and  key  is  called  a 
“ Lewis,”  from  the  name  of  the  inventor. 

The  single  lewis  is  in  the  form  of  Fig. 

2689,  and  is  generally  used  to  suspend 
stone  not  exceeding  600  pounds  weight. 

The  double,  or  chain  lewis,  is  in  the  fomn 
of  Fig.  2590.  This  was  the  form  of  the 
lewis  which  was  chiefly  used  on  the  U.  S. 

Dry  Dock  at  Brooklyn,  for  suspending  stone 
from  600  pounds  to  10,000  pounds;  and 
stone  of  twice  this  weight  were  suspended 
with  two  lewises  of  this  description. 

The  floor  of  this  dock  is  an  inverted  arch, 
and  the  sides  are  made  up  of  alter  courses, 
the  top  surface  of  which  show  as  coping 
stone.  To  suspend  stone  of  this  descrip- 
tion, as  well  as  steps  and  coping,  without 
marring  the  upiper  surface,  has  been  long  a 
desideratum. 

In  Fig.  2591  is  exhibited  a drawing  of 
Lidgewood’s  lever  lewis,  by  means  of  which 
all  this  description  of  stone  were  set  on 
the  dock — some  of  them  weighing  seven 
tons. 

The  mitre  sills  on  the  same  work  were 
enormously  heavy : the  centre  stone  weighed 
nearly  twenty-five  tons,  and  two  others  over 
twenty  tons,  and  several  others  nearly  as 
large.  These  stone  were  suspended  by  a 
frame,  as  shown  in  Fig.  2691. 


LIGHT.  The  cause  of  those  sensations  which  we  refer  to  the  eyes,  or  that  which  produces  the 
sense  of  seeing.  The  phenomena  of  light  and  vision  have  always  been  regarded  as  one  of  the  most 
interesting  branches  of  natural  science ; though  it  is  only  since  the  days  of  Newton  that  they  have  been 
examined  with  such  care  as  to  afford  grounds  for  any  safe  speculation  respecting  the  nature  of  light,  and 
the  mode  of  its  propagation  through  sprace. 

Experiments  of  the  simplest  and  most  familiar  kind  suffice  to  show  that  light  is  propagated  from 


220 


LIGHT. 


luminous  bodies  in  all  directions.  Provided  nothing  intervenes  to  intercept  the  light,  they  arc  seen  it 
all  situations  of  the  eye. 

Another  property  of  light  is,  that  it  requires  time  for  its  propagation.  The  velocity  with  which  it 
passes  from  one  point  to  another  is,  however,  so  great,  that,  with  respect  to  any  terrestrial  distances,  the 
passage  may  be  considered  as  instantaneous.  But  astronomy  furnishes  the  means,  not  only  of  detecting 
its  propagation,  but  of  measuring  its  velocity  with  great  precision.  The  eclipses  and  emersions  ot 
Jupiter’s  satellites  become  visible  about  16  min.  26  sec.  earlier  when  the  earth  is  at  its  least  distance 
from  Jupiter,  than  wThen  it  is  at  its  greatest.  Light,  therefore,  occupies  above  a quarter  of  an  hour  in 
passing  through  the  diameter  of  the  earth's  orbit.  Now  the  sun’s  distance  from  the  earth  being  nearly 
95,000,000  of  miles,  it  follows  that  light  must  travel  through  space  with  the  prodigious,  though  finite, 
velocity  of  192,500,  or  nearly  200,000  miles  in  a second  of  time,  and  consequently  would  pass  round  the 
earth  in  the  eighth  part  of  a second.  Astounding  as  this  conclusion  is,  no  result  of  science  rests  on  more 
certain  evidence.  It  is  also  proved,  by  the  phenomena  of  aberration,  that  the  light  of  the  sun,  planets, 
and  all  the  fixed  stars,  travels  with  one  and  the  same  velocity. 

Theories  of  light. — Two  different  theories  have  long  divided  the  opinion  of  philosophers  respecting  the 
nature  and  propagation  of  light.  One  of  these  consists  in  supposing  it  to  be  composed  of  particles  of 
excessive  minuteness,  projected  from  the  luminous  body  with  a velocity  equal  to  nearly  200,000  miles  in 
a second.  This  hypothesis  was  adopted  by  Newton,  and,  till  recently,  has  been  acquiesced  in  by  the 
greater  number  of  writers  on  optics.  The  other  hypothesis  supposes  light  to  be  produced  by  the  vibra 
tions  or  undulations  of  an  ethereal  fluid  of  great  elasticity,  which  pervades  all  space  and  penetrates  all 
substances,  and  to  which  the  luminous  body  gives  an  impulse  which  is  propagated  with  inconceivable 
rapidity,  in  spherical  superficies,  by  a sort  of  tremor  or  undulation,  as  sound  is  conveyed  through  the 
atmosphere,  or  a wave  along  the  surface  of  water.  Both  of  these  hypotheses  are  rendered  probable  by 
the  great  number  of  phenomena  of  which  they  afford  a mechanical  explanation ; but  they  are  both,  also, 
attended  with  very  great  difficulties.  Other  theories  have  also  been  proposed;  but  they  have  not  met 
with  such  general  attention  from  philosophers  as  to  make  it  necessary  to  explain  them  in  this  place. 

Corpuscular  theory  of  light. — Sir  John  Herschel,  in  his  admirable  Essay  on  Light,  in  the  Encyclopaedia 
Metropolitana,  states  the  principles  of  the  Newtonian  or  Corpuscular  theory  as  follows : 

1.  “That  light  consists  of  particles  of  matter  possessed  of  inertia,  and  endowed  with  attractive  and 
repulsive  forces,  and  projected  or  emitted  from  all  luminous  bodies  with  nearly  the  same  velocity,  about 
200,000  miles  per  second. 

2.  That  these  particles  differ  from  each  other  by  the  intensity  of  the  attractive  and  repulsive  forces 
which  reside  in  them ; and  in  their  relations  to  tire  material  world ; and  also  in  their  actual  masses,  or 
inertia. 

3.  That  these  particles,  impinging  on  the  retina,  stimulate  and  excite  vision : the  particles  whose 
inertia  is  greatest,  producing  the  sensation  of  red ; those  of  the  least  inertia,  of  violet ; and  those  in  which 
it  is  intermediate,  the  intermediate  colors. 

4.  That  the  molecules  of  material  bodies  and  those  of  light  exert  a mutual  action  on  each  other, 
which  consists  in  attraction  ana  repulsion,  according  to  some  law  or  function  of  the  distance  between 
them ; that  this  law  is  such  as  to  admit,  perhaps,  of  several  alternations  or  changes  from  repulsive  to 
attractive  force ; but  that  when  the  distance  is  below  a certain  very  small  limit  it  is  always  attractive 
up  to  actual  contact ; and  that  beyond  this  limit  resides  at  least  one  sphere  of  repulsion.  This  repulsive 
force  is  that  which  causes  the  reflection  of  light  at  the  external*surfaces  of  dense  media ; and  the  interior 
attraction  that  wdiich  produces  the  refraction  and  interior  reflection  of  light. 

5.  That  these  forces  have  different  absolute  values  or  intensities,  not  only  for  all  different  material 
bodies,  but  for  every  different  species  of  the  luminous  molecules,  being  of  a nature  analogous  tc 
chemical  affinities  or  electric  attractions ; and  that  hence  arises  the  different  refrangibilities  of  the  rays 
of  light. 

6.  That  the  motion  of  a particle  of  light,  under  the  influence  of  these  forces  and  its  own  velocity,  is 
regulated  by  the  same  mechanical  laws  which  govern  the  motions  of  ordinary  matter;  and  that  there- 
fore each  particle  describes  a trajectory,  capable  of  strict  calculation  as  soon  as  the  forces  which  act  on 
it  are  assigned. 

7.  That  the  distance  between  the  molecules  of  material  bodies  is  exceedingly  small  in  comparison 
with  the  extent  of  their  spheres  of  attraction  and  repulsion  on  the  particles  of  light. 

8.  That  the  forces  which  produce  the  reflection  and  refraction  of  light  are,  nevertheless,  absolutely 
insensible  at  all  measurable  or  appreciable  distances  from  the  molecules  which  exert  them. 

9.  That  every  luminous  molecule,  during  tire  whole  of  its  progress  through  space,  is  continually 
passing  through  certain  periodically  recurring  states,  called  by  Newton  fits  of  easy  reflection  and  easy 
transmission,  in  virtue  of  which  they  are  more  disposed,  wdien  in  the  former  states  or  phases  of  their 
periods,  to  obey  the  influence  of  the  repulsive  or  reflective  forces  of  the  molecules  of  a medium;  and 
when  in  the  latter,  of  the  attractive.” 

Such  are  the  postulates  on  which  the  corpuscular  theory  of  light  depends.  Most  of  them  may  be 
admitted  without  difficulty;  and  they  afford  data  for  the  application  of  mathematical  reasoning  to  the 
phenomena,  which  may  be  investigated  by  the  same  sort  of  analysis  with  which  mathematicians  are 
already  familiar  in  the  theories  of  heat,  capillary  attraction,  and  other  molecular  forces. 

Undulatory  theory. — The  principles  of  the  undulatory  theory  are  thus  stated  by  Sir  J.  Herschel: 

1.  “ That  an  excessively  rare,  subtle,  and  elastic  medium,  or  ether,  fills  all  space,  and  pervades  all 
material  bodies,  occupying  the  intervals  between  their  molecules ; and  either  by  passing  freely  among 
them,  or  by  its  extreme  rarity,  offering  no  resistance  to  the  motion  of  the  earth,  the  planets,  or  comets, 
in  their  orbits,  appreciable  by  the  most  delicate  astronomical  observations ; and  having  inertia,  but  not 
gravity. 

2.  That  the  molecules  of  the  ether  are  susceptible  of  being  set  in  motion  by  the  agitation  of  the  par- 
ticles of  ponderablo  matter;  and  that  when  any  one  is  thus  set  in  motion  it  communicates  a similai 


LIGHT,  ARTIFICIAL. 


22 1 


motion  to  those  adjacent  to  it ; and  thus  the  motion  is  propagated  further  and  further  in  all  directions, 
according  to  the  same  mechanical  laws  which  regulate  the  propagation  of  undulations  in  other  elastic 
media,  as  air,  water,  or  solids,  according  to  their  respective  constitutions. 

3.  That  in  the  interior  of  refracting  media  the  ether  exists  in  a state  of  less  elasticity,  compared  with 
its  density,  than  in  vacuo,  ( i . e.,  in  space  empty  of  all  other  matter ;)  and  that  the  more  refractive  the 
medium,  the  less,  relatively  speaking,  is  the  elasticity  of  the  ether  in  its  interior. 

4.  That  vibrations  communicated  to  the  ether  in  free  space  are  propagated  through  refractive 
media  by  means  of  the  ether  in  their  interior,  but  with  a velocity  corresponding  to  its  inferior  degree  of 
elasticity. 

5.  That  when  regular  vibratory  motions  of  a proper  kind  are  propagated  through  the  ether,  and, 
passing  through  our  eyes,  reach  and  agitate  the  nerves  of  our  retina,  they  produce  in  us  the  sensation 
of  light,  in  a manner  bearing  a more  or  less  close  analogy  to  that  in  which  the  vibrations  of  the  air  affect 
our  auditory  nerves  with  that  of  sound. 

6.  That  as,  in  the  doctrine  of  sound,  the  frequency  of  the  aerial  pulses,  or  tire  number  of  excursions 
to  and  fro  from  the  point  of  rest  made  by  each  molecule  of  the  air,  determines  the  pitch  or  note ; so,  in 
the  theory  of  light,  the  frequency  of  the  pulses,  or  number  of  impulses  made  on  our  nerves  in  a given 
time  by  the  ethereal  molecules  next  in  contact  with  them,  determines  the  color  of  the  light ; and  that 
as  the  absolute  extent  of  the  motion  to  and  fro  of  the  particles  of  air  determines  the  loudness  of  the 
sound,  so  the  amplitude  or  extent  of  the  excursions  of  the  ethereal  molecules  from  their  points  of  rest 
determines  the  brightness  or  intensity  of  the  light.” 

Whichever  theory  we  adopt  to  explain  the  phenomena  of  light,  we  are  led  to  conclusions  which  strike 
the  mind  with  astonishment.  According  to  the  corpuscular  theory,  the  molecules  of  light  are  supposed 
to  be  endowed  with  attractive  and  repulsive  forces,  to  have  poles,  to  balance  themselves  about  their 
centres  of  gravity,  and  to  possess  other  physical  properties  which  we  can  only  ascribe  to  ponderable 
matter.  In  speaking  of  these  properties  it  is  difficult  to  divest  one’s  self  of  the  idea  of  sensible  magni- 
tude, or  by  any  strain  of  the  imagination  to  conceive  that  particles  to  which  they  belong  can  be  so 
amazingly  small  as  those  of  light  demonstrably  are.  If  a molecule  of  light  weighed  a single  grain,  its 
momentum  (by  reason  of  the  enormous  velocity  with  which  it  moves)  would  be  such  that  its  effect  would 
be  equal  to  that  of  a cannon-ball  of  150  pounds,  projected  with  a velocity  of  1000  feet  per  second.  How 
inconceivably  small  must  they,  therefore,  be,  when  millions  of  molecules,  collected  by  lenses  or  mirrors, 
have  never  been  found  to  produce  the  slightest  effect  on  the  most  delicate  apparatus  contrived  expressly 
for  the  purpose  of  rendering  their  materiality  sensible  ! 

If  the  corpuscular  theory  astonishes  us  by  the  extreme  minuteness  and  prodigious  velocity  of  the 
luminous  molecules,  the  numerical  results  deduced  from  the  undulatory  theory  are  not  less  overwhelm- 
ing. The  extreme  smallness  of  the  amplitude  of  the  vibrations,  and  the  almost  inconceivable,  but  still 
measurable  rapidity  with  which  they  succeed  each  other,  were  computed  by  Dr.  Young,  and  are  ex- 
hibited by  Sir  J.  Iierschel  in  the  following  table : 


1 

Colors. 

Length  of  undu- 
lation in  parts  of 
an  inch. 

Number  of 
undulations 
in  an  inch. 

Number  of  undulations 
per  second. 

Extreme  Red  

0-0000266 

37640 

458,000000,000000 

Red 

00000256 

39180 

477,000000,000000 

Orange 

0-0000240 

41610 

506,000000,000000 

Yellow 

0-0000227 

44000 

535,000000,000000 

Green 

0-0000211 

47460 

577,000000,000000 

Blue 

0-0000196 

51110 

622,000000,000000 

Indigo 

0-0000185 

54070 

658,000000,000000 

Violet 

0 0000174 

57490 

699,000000,000000 

Extreme  Violet 

00000167 

59750 

727,000000,000000 

The  velocity  of  light  being 
assumed  at  192,000  miles 
per  second. 

On  a cursory  view,  it  must  appear  singular  that  two  hypotheses,  founded  on  assumptions  so  essentially 
different,  should  concur  in  affording  the  means  of  explaining  so  great  a number  of  facts  with  equal  pre- 
cision and  almost  equal  facility.  This,  however,  is  the  case  with  respect  to  the  corpuscular  and  undu- 
latory theories  of  light,  from  both  of  which  the  mathematical  laws  to  which  the  phenomena  are  subject 
may  be  deduced,  though  not  in  all  cases  with  the  same  degree  of  facility. 

LIGHT,  ARTIFICIAL.  The  importance  of  obtaining  a brilliant  and  economical  light  for  public  and 
domestic  purposes,  has  exercised  the  ingenuity  and  scientific  research  of  eminent  men  for  a century  past. 
And  although  their  labors  have  resulted  in  discoveries  of  great  value,  the  desideratum  so  steadily 
sought  after  has  not  yet  been  attained. 

The  introduction  of  coal-gas,  in  1798,  by  Mr.  William  Murdock,  engineer  to  Messrs.  Bolton  and  Watt, 
was  an  invention  of  the  highest  order,  and  one  that  has  conferred  most  important  benefits  upon  society. 
The  subsequent  use  of  oil  and  resin,  as  substitutes  for  coal,  to  avoid  the  difficulties  of  purification  re- 
quired by  the  latter,  did  not  result  in  any  improvement  of  economy  or  illuminating  power.  The  dis- 
covery of  the  voltaic  and  oxy-hydrogen  lime  light  was  a brilliant  addition  to  our  stock  of  chemical 
science,  but  neither  of  them  have  yet  been  reduced  to  any  thing  like  a practical  form  suited  to  public  or 
domestic  uses. 


222 


LIME. 


The  requirements  of  the  case  may  be  stated  thus:  1st,  intense  illuminating  power;  2d,  economy 
3d,  portability  ; 4th,  small  radiation  of  heat ; 5th,  perfect  ventilation  ; 6th,  simplicity  in  the  production 
and  steadiness  of  combustion,  so  as  to  insure  uniform  power  of  light. 

To  obtain  an  artificial  light  combining  all  these  requisites,  is  now  one  of  the  most  interesting  problems 
of  this  era  of  useful  inventions,  and  its  solution  will  place  the  discoverer  on  the  same  eminence  with 
Newton,  Watt,  Fulton,  and  Morse.  There  is,  therefore,  no  field  of  research  that  promises  more  sub- 
stantial rewards  to  the  successful  than  the  invention  of  a simple,  economical,  and  powerful  light,  as  the 
want  of  it  is  felt  by  the  whole  civilized  world. 

That  this  subject  has  already  attracted  the  attention  of  both  scientific  and  practical  men  in  this 
country,  as  well  as  abroad,  we  have  abundant  proofs  in  the  frequent  announcement  of  grand  discoveries 
in  the  production  of  artificial  light,  that,  upon  investigation,  prove  to  be  either  new  discoveries  of  old 
chemical  experiments,  by  some  tyro  or  quack,  or  else  are  of  no  value  practically,  owing  to  the  chemical 
or  mechanical  cost  of  production. 

It  is  very  easy  to  assure  the  public  that  water  can  be  made  to  burn,  or  that  a whole  city  is  about  to 
be  completely  illuminated  with  a single  gas-light.  The  demonstration  of  such  wonders  is,  however, 
probably  reserved  for  a future  age.  At  present  we  would  only  direct  the  attention  of  our  ingenious 
countrymen  to  the  simple  fact,  that  this  subject  is  one  of  universal  public  importance,  presenting  a broad 
scope  for  the  exercise  of  their  inventive  faculties. 

LIGHT-HOUSES.  See  Sea-Lights,  under  which  head  the  subject  should  be  treated. 

LIGHTNING  CONDUCTORS  are  pointed  metallic  rods,  fixed  to  the  upper  parts  of  buildings  to 
secure  them  from  strokes  of  lightning.  They  were  invented  and  proposed  by  Dr.  Franklin  for  this 
purpose,  and  they  exhibit  a very  important  and  useful  application  of  modern  discoveries  in  the  science 
of  electricity.  See  Electricity. 

LIFE-BOAT.  A boat  originally  made  at  Shields,  in  1*789,  by  Mr.  Greathead,  for  saving  the  crews  oi 
shipwrecked  vessels.  The  following  are  the  general  principles : The  boat  is  wide  and  shallow ; the 
head  and  stern  are  alike,  for  pulling  in  either  direction,  and  raised,  to  meet  the  waves  ; it  pulls  double- 
banked,  the  oars  being  fir,  for  lightness,  and  fitted  with  thole-pins  and  grummets,  and  is  steered  with  an 
oar.  The  boat  is  cased  round  inside,  on  the  upper  part,  with  cork,  in  order  to  secure  her  buoyancy  with 
as  many  persons  as  she  can  carry,  even  though  full  of  water ; the  cork  likewise  assists  in  maintaining,  or, 
if  overset,  in  recovering,  the  position  of  stable  equilibrium.  The  boat  is  painted  white,  to  be  conspicuous 
in  emerging  from  the  hollow  of  the  sea.  It  is  a curious  fact  that  the  smugglers  paint  their  boats  white 
for  the  contrary  reason,  because  dark-colored  objects  alone  are  discernible  in  dark  nights. 

The  loss  by  fire  constantly  occurring  on  the  western  waters  is  a proof  of  the  necessity  for  greater 
and  more  effective  means  of  saving  life,  than  are  yet  adopted  in  our  mercantile  marine  of  all  classes 
nearly.  That  this  should  be  so  is  doubly  surprising,  when,  in  our  very  midst,  we  have  the  remedy 
in  Francis’s  galvanized  iron  life-boat,  of  which  it  may  be  stated,  they  are  never  leaky.  They  may 
be  thrown  overboard  without  injury,  or  lessening  their  usefulness;  they  right  themselves,  if  swamped  ; 
and,  when  full  of  water,  a thirty-foot  boat  will  sustain  forty  people,  so  long  as  they  can  hold  on  to 
the  beckets,  with  which  each  boat  is  provided.  The  non-inflammable  material  of  their  construction  is 
another  great  safety  on  going  alongside  a burning  wreck ; and  in  a heavy  sea  their  elasticity  and  buoy- 
ancy preserves  them  alongside  a sinking  wreck,  in  circumstances  which  invariably  destroy  a wood-boat 
at  the  time  when  she  is  most  needed.  These  boats  are  manufactured  by  Mr.  Francis,  at  the  Novelty 
Works  of  Stillman,  Allen  & Co.,  on  the  East  River. 

LIME.  Carbonate  of  lime  is  the  substance  forming  the  principal  ingredient  of  all  natural  limestones, 
which  may  be  classified,  from  their  outward  mineralogical  characters,  under  the  following  arrangement: 

Granular  limestone,  with  a decidedly  crystalline  grain : the  different  varieties  of  marble,  (Parian, 
Carrara,)  and  particularly  the  old  mountain  limestone,  belong  to  this  class. 

Compact  limestone  occurs  in  quite  as  great  a variety  of  colored  species  as  the  foregoing,  but  is  never 
so  white.  It  is  found  in  all  geological  formations,  and  is  named  according  to  its  age,  or  from  the  forma- 
tions of  which  it  is  a member  ; w7e  thus  have  transition  limestone,  graywacke  limestone,  carboniferous 
limestone,  mountain  limestone,  shell  limestone,  lias  limestone,  fresh-water  limestone,  &c. 

Limestone  Breccia,  consisting  of  lumps  of  limestone,  cemented  together  by  another  limestone 
mass. 

Limestone  marl,  more  or  less  uniformly  mixed  with  clay,  of  a dense  earthy  fracture.  This  and  the 
foregoing  variety  belong  to  no  particular  member  of  the  stratified  rocks,  exclusively. 

Silicious  limestone  contains  numerous  silicious  minerals,  as  quartz,  hornestene,  chalcedony,  opal,  <Lc. 
This  variety  is  dense,  and  interspersed  often  with  cavities ; it  is  gray,  or  yellowish-white. 

Fetid  limestone  is  characterized  by  the  bitumen  which  it  contains,  and  which  is  rendered  perceptible 
to  the  smell  by  friction.  It  is  generally  dense,  and  exhibits  stratification.  It  is  called  friable  marl 
when  it  occurs  as  a disconnected  earthy  mass,  and  is  of  a dark  color. 

Chalk  is  a dense,  earthy  rock,  imparting  color  when  rubbed,  seldom  other  than  of  a white  color.  It 
is  distinguished  as  being  the  matrix  of  flints. 

Coarse  lime  is  dense,  earthy,  approaching  sandstone  in  appearance,  and  contains  a large  proportion  ol 
quartz-sand  and  clay,  and  is  stratified. 

Calcareous  tufa  consists  of  layers  of  lime  which  are  pretty  free  from  foreign  matters,  and  is  still  in 
the  process  of  formation.  Generally  unstratified.  In  some  parts  it  is  loose,  porous,  and  earthy ; in 
others  dense,  passing  into  a variety  of  dense  limestone. 

Calcareous  tufa  and  Travertin  belong  to  this  class.  Lime  of  similar  origin  is  called  calcareous  sinter 
when  the  stratification  contains  crystalline  particles  (calcareous  spar  or  arragonite)  arranged  like  laj  ers 
of  bark,  one  above  the  other,  often  in  the  form  of  columns. 

[These  formations  are  produced  by  the  solvent  action  of  water  containing  carbonic  acid  upon  car- 
bonate of  lime. 

The  stalactites  and  stalagmites  which  frequently  cover  the  roofs  and  floors  of  certain  caverns,  are  also 


due  to  the  same  cause.  The  water  which  permeates  the  rocks  above  them  dissolves  the  carbonate  of 
lime,  by  reason  of  the  carbonic  acid  which  it  contains.  In  dropping  from  the  roof,  however,  it  remains 
suspended  for  some  time,  and,  losing  a certain  part  of  the  acid,  deposits  also  a portion  of  the  carbonate 
of  lime,  previously  held  in  solution.  The  accumulation  of  these  minute  portions  of  lime  gradually  form 
the  stalactites.  The  same  takes  place  on  the  floors  of  the  caverns,  giving  rise  to  the  formation  of  the 
stalagmites.] 

/ Dolomite  is  characterized  by  a large  amount  of  magnesia ; it  is  generally  granular,  and  seldom  earthy 
or  massive.  It  is  not  distinctly  stratified,  but  sometimes  bituminous. 

The  characters  of  limestone  which  stand  in  connection  with  the  theory  of  the  earth’s  formation,  the 
geological  characters,  therefore,  lead  to  a totally  different  classification.  The  examination  of  a limestone 
in  one  point  of  view  only,  must  therefore  lead  to  a very  imperfect  knowledge  of  its  nature.  The  mere 
study  of  its  chemical  constitution,  would  also  afford  but  a very  partial  means  of  judging  it. 

Many  limestones  exhibit  clear  indications  of  having  been  put  in  motion  in  the  liquid  state.  Limestone 
of  this  kind  must  possess  a high  degree  of  purity,  as,  if  this  were  not  the  case,  (and  clay  or  other  sub- 
stances were  present,)  the  result  of  the  fusion  would  certainly  have  been  different,  and  would  not  have 
ended  in  the  formation  of  crystals  of  pure  carbonate  of  lime. 

Other  limestones,  which  have  been  formed  by  precipitation  from  soluble  salts  of  lime,  are  more  likely 
to  contain  foreign  admixtures,  which  have  been  deposited  by  chemical  or  mechanical  agency.  Thus, 
some  contain  magnesia,  iron,  and  manganese  uniformly  disseminated  through  them ; others  are  mixed 
in  the  same  manner  with  aluminous  or  silicious  particles,  or  these  are  interstratified  with  them. 

Others,  again,  and  a whole  series  of  limestones,  have  obviously  been  formed  with  the  concurrence  of 
the  animal  creation,  and  it  is  of  importance  to  ascertain  what  part  the  living  beings  have  performed  in 
this  general  development.  Thus,  at  the  present  moment,  whole  islands  are  being  raised  up  in  certain 
latitudes  and  oceans,  from  the  calcareous  coverings  of  the  coralline  animals,  just  as  in  former  ages  the 
range  of  the  Jura  and  other  mountains  have  been  produced  from  the  same  agency.  There  are  likewise 
limestones,  as  the  shell  limestones,  which  are  composed  of  masses  of  shells  of  crustaceous  animals.  The 
shells  of  these  animals  have  been  filled  with  lime,  and  cemented  together  so  as  to  form  a more  or  less 
solid  rock.  The  bodies  of  the  animals  have  not,  however,  disappeared  without  leaving  a trace  behind 
them ; for  that  which  is  denominated  bituminous  in  these  rocks,  is  generally  the  residue  of  decomposed 
animal  matter  permeating  the  entire  mass  of  the  stone. 

While  many  limestone  formations  have  been  deposited  from  sea-water,  others  appear  to  have  been 
decidedly  formed  in  fresh  water.  Calcareous  tufa  is  still  being  deposited  in  numerous  places  from 
springs,  the  carbonic  acid  in  which,  under  greater  pressure,  dissolves  lime,  which  is  again  precipitated, 
when  the  carbonic  acid  is  evolved  under  the  lesser  pressure  of  the  atmosphere. 

Pure  burnt  lime  absorbs  water  with  great  avidity,  and  occasions  a great  disengagement  of  heat, 
forming  a dense,  very  soft  paste,  or,  as  it  is  called,  becoming  fat;  the  limestones  containing  magnesia 
are  poorer  in  proportion  as  they  approach  to  the  composition  of  dolomite.  The  oxides  of  manganese 
and  iron  which  are  so  frequently  found  in  the  limestones,  have  probably  been  formed  by  the  action  of 
the  atmosphere  upon  the  protoxides  of  these  metals. 

Besides  the  carbonates,  the  silica  and  alumina  contained  in  the  limestone  rocks  are  also  of  interest. 
They  exist  in  the  most  variable  proportions,  often  combined  in  the  form  of  clay,  sometimes  associated 
with  magnesia,  sometimes  alone.  The  silica  is  often,  but  the  alumina  never  in  excess,  so  that  both  re- 
main undissolved  in-  acids.  Their  presence  is  without  any  perceptible  influence  when  they  are  present 
in  small  quantity ; but  when  their  amount  exceeds  10  per  cent.,  the  limestones  are  slaked  very 
slowly  and  with  difficulty  after  burning,  their  affinity  for  water  is  diminished,  and  they  are  then  appli- 
cable to  very  different  purposes.  Of  these  we  shall  have  occasion  to  speak  under  the  head  of  hydraulic 
lime. 

Lime  burning — Chemical  process. — Carbonate  of  lime  is  not  decomposed  at  a low  red-heat,  but  is 
converted  at  a bright  red-heat  into  carbonic  acid  and  lime.  The  temperature  at  which  the  decompo- 
sition is  effected  is,  however,  influenced  by  circumstances,  or  rather  depends  entirely  upon  the  facility 
afforded  the  carbonic  acid  for  escape  when  it  has  been  expelled  from  the  lime.  If  the  limestones  are 
constantly  surrounded  with  an  atmosphere  of  carbonic  acid,  the  further  evolution  of  carbonic  acid  from 
them  is,  according  to  Faraday,  very  much  impeded ; but  if  the  gaseous  acid  is  removed  as  quickly  as  it 
is  expelled  from  the  lime,  the  process  of  removing  the  future  portions  of  acid  is  much  accelerated.  In 
close  vessels,  the  decomposition  is  stopped  as  soon  as  the  space  not  occupied  by  the  lime  has  become 
filled  with  carbonic  acid. 

It  will  be  proper  to  explain  the  processes  employed  in  burning  lime,  which  must  be  viewed  as  a 
preparation  of  the  limestone  for  its  numerous  applications  in  the  arts.  The  burning  of  lime  is  accom- 
plished in  three  modes : 1.  Without  a kiln ; 2.  By  an  intermittent  kiln ; and  3.  By  a kiln  in  constant 
operation,  or,  as  it  is  called,  a perpetual  kiln. 

1.  Without  a kiln. — In  Wales  and  Belgium  lime  is  burnt  precisely  as  we  burn  charcoal;  the  pile  of 
limestone  and  fuel  mixed  is  covered  with  turf,  making  a heap  of  about  16  feet  in  diameter  at  the  base, 
and  12  feet  at  the  summit,  which  occupies  in  burning  from  six  to  seven  days. 

Intermittent  kiln. — One  of  the  simplest,  but  at  the  same  time  crudest  arrangements,  is  the  following : 
The  kiln  is  perpendicular,  and  constructed  of  the  same  limestone  (in  the  dry  state  and  without  mortar) 
as  that  which  it  is  intended  to  burn.  It  is  placed  at  the  side  of  a steep  hill  or  declivity,  so  that  the 
mouth  is  equally  accessible  for  charging  the  kiln,  as  the  fire-place  for  introducing  the  fuel.  The  shaft 
is  round  throughout,  six  feet  in  diameter  at  the  top,  and  gradually  expands  to  ten  feet  at  about  one-third 
from  the  bottom.  A sudden  contraction  of  the  diameter  is  there  introduced,  forming  a sort  of  projection 
inwards  of  one  foot  in  width,  and  the  size  of  the  kiln  then  diminishes  until  it  acquires  a diameter  of 
about  6]-  feet  at  the  bottom.  A projection  or  ledge  is  carried  in  the  form  of  a ring  all  round  the  interior 
of  the  furnace,  but  not  at  the  same  height  from  the  ground,  inclining  towards  the  stoking-liole.  The 
charging  is  carried  on  upon  a certain  fixed  plan.  The  lime-burner  begins  by  constructing  a pointed 


224 


LIME. 


arch  upon  the  ledge,  with  the  large  pieces  of  limestone  which  are  selected  expressly  for  this  purpose. 
He  forms  in  this  manner  a kind  of  support  or  foundation,  upon  which  the  other  limestones  are  thrown 
in,  at  random,  from  above,  the  largest  first  and  the  smaller  pieces  afterwards,  which  are  also  piled  up 
above  the  mouth  of  the  kiln.  "When  the  charge  has  been  thus  arranged,  a pile  of  wood  is  erected  in  the 
space  below  the  arch,  and  ignited.  The  regulation  of  the  fire  is  by  no  means  an  unimportant  point,  as 
the  possibility  of  completing  the  burning  depends  upon  the  length  of  time  that  the  arch,  which  acts  as 
a support,  will  endure.  The  stones  composing  this  arch  being  unconnected  by  any  cement  and  unhewn, 
and  only  touching  in  a few  places  so  as  to  leave  a free  ingress  for  the  flames,  a slight  shock  will  often 
cause  the  downfall  of  the  whole,  and  put  a stop  to  the  operation.  The  sudden  and  powerful  action  of 
the  fire,  by  expanding  the  stones  very  rapidly,  and  driving  out  the  moisture  with  such  force  as  to  rup- 
ture the  stones,  will  often  produce  a sufficient  shock  to  create  a catastrophe  of  this  kind.  The  art  of 
burning  lime,  therefore,  consists  in  bringing  the  mass  of  limestone  as  gradually  as  possible  to  a red-heat. 
The  first  period  is  called  the  smoking , because  the  gases  evolved  from  the  fuel,  being  too  much  cooled, 
are  imperfectly  burnt,  and  pass  off  in  the  form  of  a thick  smoke.  The  temperature  generally  increases 
in  a kiln  of  this  kind  during  the  first  two-thirds  of  the  time,  until  it  attains  a white-heat,  and  diminishes 
again  in  the  last  third.  The  firing  must,  however,  be  kept  up  until  the  uppermost  stones  have  been 
completely  burnt.  During  the  firing  the  bulk  of  the  stones  is  much  diminished,  aud  the  heap  above  the 
mouth  of  the  furnace  sinks  gradually  down. 

The  evils  of  such  a system  of  burning,  which  involves  an  enormous  waste  of  fuel,  (the  loss  of  time  not 
being  taken  into  consideration,)  are  obvious.  The  furnace  must  be  allowed  to  cool  each  time  it  is  dis- 
charged, and  the  entire  amount  of  heat,  or,  what  is  the  same  thing,  the  whole  of  the  wood  employed  for 
raising  die  very  extensive  sides  of  the  kiln  to  the  temperature  at  which  lime  is  burnt,  must  be  sacrificed. 
It  is  also  evident  that,  in  such  a system  of  burning,  the  lower  half  of  the  limestone  must  be  thoroughly 
caustic,  while  the  upper  portions  are  still  in  the  mild  state.  The  upper  part  is  at  a very  considerable 
distance  from  the  fire,  and  removed  from  the  direct  action  of  the  flames,  is  burnt,  consequently,  at  a 
much  greater  cost  of  fuel  than  would  otherwise  be  necessary.  At  the  same  time  the  lower  layers  in 
the  kiln  are  exposed  to  the  constant  danger  of  becoming  over-burnt,  which  very  much  injures  the  quality 
of  the  lime. 

A great  advantage  is  gained  by  constructing  the  kilns  of  brick-work,  in  a more  solid  manner,  giving 
the  shaft  more  appropriate  dimensions  and  shape,  and  building  the  kilns  in  situations  less  subject  to  be 
obstructed  in  working  by  moisture,  &c. 

These  improvements  have  been  carried  out  in  the  kiln  shown  in  Fig.  2592.  Instead  of  a rudely 
constructed  wall,  an  outer  wall  is  erected  in  these  furnaces,  with  an  internal  one  of  solid  brick-work. 
The  fire  is  placed  upon  the  grate  which  separates  the  ash-pit  a from  the  fireplace  b.  The  grate  is  really 
a permeated  brick  arch. 


The  perpetual  or  draw  kilns  are  constructed  as  follows:  Fig.  2593  represents  a vertical  section  of  a 
common  form  of  perpetual  kiln  constructed  for  a coal-fire ; Fig.  2594  is  a horizontal  section  of  the  same 
through  the  drawing-holes.  The  actual  burning-space  is  a shaft  in  the  form  of  an  inverted  cone,  wide  at 
the  top  and  narrow  at  the  bottom.  There  is  no  separate  hearth,  the  apertures  a a a,  of  which  there  are 
three,  serving  only  for  drawing  out  the  lime.  A layer  of  brushwood  is  first  placed  at  the  bottom  of  the 
kiln,  upon  this  some  coal,  then  a layer  of  limestone,  which  is  again  covered  with  coal,  and  then  another 
layer  of  limestone,  and  so  on  until  the  kiln  is  filled.  The  last  layer  of  stone  is  heaped  up  above  the 
mouth  of  the  kiln,  and  the  progress  of  the  firing  is  judged  of  by  the  manner  in  which  it  sinks  down ; 
the  sinking  in  this  case  being  due,  not  only  to  the  diminution  in  bulk  of  the  stones,  but  also  to  the  con- 
sumption of  the  fuel  As  soon  as  the  uppermost  layer  has  sunk  down  to  the  level  of  the  top  of  the 
kiln,  another  charge  of  coal  and  limestone  is  thrown  upon  it.  In  the  mean  time,  at  intervals  of  one-half 
to  one-quarter  of  an  hour,  the  lime  which  has  sunk  to  the  bottom  of  the  kiln  is  drawn  out  through  the 
holes.  The  lower  the  charges  sink  in  the  kiln  the  more  the  coal  is  consumed,  and  the  less  space  they 
will  occupy ; for  this  reason  the  inverted  conical  form  of  the  kiln  is  the  most  appropriate.  The  intensity 
of  the  fire  can  be  regulated  with  perfect  ease  by  adding  more  or  less  coal  with  each  charge  of  limestone. 
The  draught  may  be  impeded  by  stopping  the  apertures  entirely  or  in  part.  In  a kiln  of  the  above 


LIME. 


225 


2596. 


dimensions,  500  cubic  feet  of  lime  are  drawn  in  twenty-four  hours,  and  the  consumption  of  coal  is  about 
two  tons. 

Fig.  2595  represents  a section,  and  Fig.  2596  a plan  of  one  of  the  most  approved  forms  of  perpetual 
kilns  in  use  in  Prussia,  in  which  one  part  of  wood  and  four  parts  of  peat  are 
used,  ddcldd  are  openings  at  bottom  for  drawing  the  lime  as  it  is  burnt; 
c c c c c fire-furnace  for  the  fuel,  whose  mode  of  connection  with  the  cavity 
where  the  limestone  is  placed  may  be  seen  at  c in  the  vertical  section,  which 
also  shows  at  d the  manner  in  which  the  lime  may  be  drawn.  At  a a is  shown 
a lining  of  fire-brick,  back  of  which  is  a cavity  b b filled  with  cinders,  which 
act  as  a non-conductor  of  heat. 

The  outside  is  built  of  rough  stone.  It  produces  about  250  bushels  of  lime 
daily. 

Scale,  12  feet  to  4 inch. 

Coal  is  a kind  of  fuel  that  is  easily  broken  in  small  pieces,  in  a convenient 
state  for  spreading  about  between  the  layers  of  limestone.  Another  advan- 
tage arising  from  the  use  of  coal  is  the  small  quantity  of  ash  which  it  leaves, 
and  which  is  easily  removed  from  the  kiln  with  the  burnt  lime.  These  remarks  do  not  apply  to  wood 
which  is  reduced  with  difficulty  into  small  pieces,  and  not  being  equally  distributed  amongst  the  lime 
stone,  impedes  the  regular  burning  and  delivery  of  the  lime  ; nor  to  peat,  which  in  general  leaves  so 
large  a proportion  of  ash  as  to  subject  the  kiln  to  the  danger  of  becoming  Stopped.  In  those  cases 
where  a perpetual  process  must  be  combined  with  the  use  of  wood  and  peat  as  fuel,  the  construction  oi 
the  kiln  must  undergo  a suitable  modification.  While  the  kiln  retains  its  character  as  a perpendicular 
or  shaft  furnace,  the  fuel,  instead  of  being  interstratified  with  the  limestone,  is  burnt  on  separate  hearths 
at  the  sides  of  the  shaft,  and  the  flame  is  conducted  into  the  latter,  which,  in  this  case,  contains  nothing 
but  the  material  to  be  burnt.  The  number  of  the  fires,  which  must  always  be  symmetrically  arranged 
round  the  circumference  of  the  shaft,  is  regulated  by  the  size  of  the  kiln,  so  that  kilns  with  three,  four, 
and  five  fires  are  met  with.  The  fuel  consumed  in  furnaces  of  this  construction  must,  of  course,  yield  a 
long  and  lively  flame,  as  from  wood,  peat,  or  coal ; but  for  the  latter,  the  arrangement  is  not  so  econom- 
ical as  the  plan  of  stratification  previously  described. 

Fig.  2591  is  a vertical  section  of  a plain  perpetual  kiln,  built  in  Berkshire,  Mass.  It  is  25  feet  high,  and 
built  of  alternate  layers  of  fire-brick  and  stone.  It  is  four-sided ; consisting  of  a single  chimney  4 feet 
square  on  the  inside,  and  8 feet  on  the  outside,  making  the  walls  2 feet  thick. 

To  the  height  of  7 feet  from  the  bottom  it  is  12  feet  in  one  direction,  for  the 
purpose  of  making  room  for  the  furnaces  d d,  in  which  wood  only  is  burnt,  and 
which  are  2 feet  high  and  20  inches  wide.  For  the  passage  of  the  heat  into 
the  limestone  in  the  chimney  the  bricks  are  laid  up  like  a grate  ; a a are  ash- 
pits beneath  the  fires,  b an  opening  for  clearing  the  lime  from  the  bottom  of 
the  chimney — being  about  18  inches  square.  The  kiln  consumes  from  2 to  24 
cords  of  wood  daily,  and  produces  75  bushels  of  lime,  which  is  drawn  out  at 
intervals  of  8 hours.  Scale,  12  feet  to  a half  inch. 

Consumption  of  fuel. — Notwithstanding  the  great  saving  of  fuel,  which  is 
effected  in  perpetual  kilns,  yet  it  must  be  borne  in  mind,  that  these  kilns  de- 
mand the  entire  attention  of  the  workman,  and  cannot  be  well  attended  to  as 
a casual  occupation,  or  as  a secondary  branch  of  husbandry,  for  instance ; 
it  must  also  be  remembered  that  perpetual  furnaces  are  always  yielding,  that 
is,  they  produce,  in  the  same  time,  a much  larger  amount  of  burnt  lime,  and 
are,  consequently,  only  economical  where  there  is  a large  and  constant  demand 
for  the  produce.  Every  improvement  in  the  construction  of  lime-kilns  would 
be  a great  boon  to  the  public,  for  they  must  be  decidedly  classed  amongst  the 
chief  sources  of  the  waste  of  fuel.  The  best  mode  of  arriving  at  some  sure 
foundation  from  which  to  calculate  the  amount  of  this  waste,  will  no  doubt 
be,  by  ascertaining  the  theoretical  amount  of  fuel  that  is  necessary  to  burn 
a given  weight  of  lime,  and  making  this  result  the  standard  by  which  to  compare  the  real  loss. 
It  may  be  stated  that  1 lb.  of  wood  fuel  is  capable  of  heating  26  lbs.  of  water  100°  C.  If  the  specific 
heat  of  limestone  and  carbonic  acid  is  taken  at  J that  of  water,  and  the  temperature  at  which  lime  is 
rendered  caustic  is  calculated  at  800°  C.,  it  results,  first,  that  1 lb.  of  wood  will  heat  8 X 26  —78  lbs. 
of  lime  to  100°,  and  consequently  =9'75  lbs.  of  limestone  to  800°  ; or  in  other  words  and  round 
numbers,  only  -A.  of  the  weight  of  the  lime  is  requisite.  In  practice  from  4 to  6 times  as  much  is  con- 
sumed. The  limestone,  it  is  true,  does  not  lose  its  carbonic  acid  all  at  once,  as  the  calculation  presup- 
poses, even  when  it  has  acquired  the  proper  heat,  but  the  acid  is  evolved  very  gradually  ; it  is,  conse- 
quently, not  only  necessary  to  heat  the  kiln  for  a single  instant  to  the  proper  temperature,  but  to  keep 
up  that  temperature  for  a considerable  time.  But,  even  if  the  quantity  of  wood  calculated  as  necessary 
be  doubled,  on  account  of  this  latter  .circumstance,  yet  there  still  remains  a loss  of  an  equal  quantity, 
and  it  may  be  positively  asserted,  that  the  quantity  of  wood  consumed  in  the  lime-kilns  is  about  as 
much  again  as  it  should  be.  The  heating  power  of  coal  being  to  that  of  wood  as  60 : 26,  for  every 
10  lbs.  of  lime  burnt  there  should  be  0'43  lbs.  of  coal  consumed.  But,  as  was  stated  above,  for  every 
cubic  foot  of  lime,  from  | to  -J  cubic  foot  of  coal  is  burnt,  which  is  equivalent  to  from  2 4 to  3 lbs.  of 
coal  for  10  lbs.  of  lime,  and  consequently  a very  much  greater  waste. 

Lime  may  be  burnt,  like  bricks,  in  mounds ; but  the  irregular  form  of  the  pieces,  and  the  contraction 
which  ensues,  renders  the  process  difficult,  and  it  is  consequently  seldom  practised. 

Produce. — Chemically,  pure  carbonate  of  lime  loses  44  per  cent,  of  carbonic  acid,  and  yields,  after 
burning,  56  per  cent,  of  caustic  lime.  The  produce  from  the  kilns  upon  a large  scale  is  much  less  when 
the  limestone  is  very  moist,  and  greater  when  it  contains  a large  proportion  of  clay,  which  loses  nothing 
Vol.  II. — 15 


226 


LIME. 


ill  the  kiln.  The  average  amount  of  produce  obtained,  ranges  between  45  and  77  per  cent.,  the  ordinary 
quantity  being  about  54  per  cent.  The  contraction  is  not  so  considerable  as  might  be  expected,  as  th« 
burnt  lime  is  very  porous.  The  specific  gravity  of  limestone  is  diminished  from  J to  ^ by  binning,  and 
its  volume  is  reduced  from  10  to  20  per  cent.  Triest  found,  by  direct  experiment,  the  weight  of  a solid 
cubic  foot  (Hessian)  of  Riidersdorf  limestone  = 93  lbs.,  after  burning  — 48  lbs. ; the  loss  was,  therefore, 

45  lbs.  or  48  per  cent.  100  lbs.  of  fresh  Rodheim  limestone,  to  give  another  example,  occupy  a 
space  =299,  after  burning,  (when  they  ought  to  weigh  60  lbs.)  the  space  which  they  occupy  is  reduced 
to  183  ; the  contraction,  therefore,  amounts  to  12^  per  cent. 

Resides  the  lumps  or  shells  of  lime,  there  is  always  a portion  leaves  the  kiln  in  the  state  of  powder, 
which  is  in  consequence  of  the  stones  splitting  in  the  fire,  or  is  due  to  the  friction  in  charging  and  dis- 
charging the  kiln. 

Action  of  aqueous  vapor  in  the  kiln. — Moist  limestone  is  said  by  old  lime-burners  to  burn  much 
more  easily  than  dry  limestone.  This  fact,  which  is  so  wrell  established  among  them  that  they  prefer 
burning  stones  fresh  from  the  pit,  or  even  moisten  those  which  have  become  dry  in  the  air  with  water 
before  putting  them  into  the  kiln,  is  not  without  a true  foundation,  although  it  is  often  misunderstood  in 
practice. 

When,  on  the  one  hand,  it  cannot  be  denied  that  limestone  is  more  easily  burnt  under  the  influence 
of  a current  of  steam,  yet  on  the  other,  it  is  very  questionable  whether  the  practice  of  burning  moist 
stones  is  really  advantageous.  The  practice  of  bringing  moist  stones  into  the  kiln  is  equivalent  to  the 
exposure  of  limestone  very  much  below  a red-heat  to  the  action  of  a current  of  vapor,  as  far  the  greater 
part  of  the  water  must  be  uselessly  expelled  (with  a proportionate  waste  of  fuel)  before  the  stones 
acquire  a red-heat. 

Burnt  lime. — Lime,  when  burnt,  combines  with  the  free  silica  at  a red-heat,  or  enters  as  a constituent 
into  the  compound  silicate  of  lime  and  alumina  which  is  formed.  It  will  be  obvious  from  these  facts, 
that  the  foreign  substances  must  exercise  considerable  influence  upon  the  quality  of  the  burnt  lime. 
In  the  purer  varieties  of  limestone  that  contain  but  very  little  foreign  matter,  the  influence  is  imper- 
ceptible. As  the  clay  and  silica  are  less  prominent  in  these  instances,  the  action  of  the  magnesia  is 
rendered  still  more  obvious,  and  when  present  to  the  amount  of  10  per  cent.,  affects  the  heating  of  the 
lime,  and  diminishes  its  property  of  slaking  and  forming  a soft  impalpable  paste  ; in  short,  renders  it 
poor.  When  the  amount  of  magnesia  exceede  J,  the  poorness  of  the  lime  is  so  great  as  to  render  it 
useless.  The  nature  of  the  limestones  is  not  solely  dependent  upon  the  foreign  substances  which  they 
contain,  but  also  upon  the  mode  of  regulating  the  furnace ; while  one  portion  of  the  shells  exhibits  the 
proper  amount  of  heat  when  slaked,  other  pieces  will  slake  very  slowly,  and  the  water  will  often  hardly 
act  at  all  upon  them ; they  are  then  said  to  be  dead-burnt. 

To  convert  oyster  and  muscle  shells  into  lime,  requires  a higher  temperature  in  the  kiln  than  ordinary 
limestone,  and  they  have  a great  tendency  to  produce  a badly  slaking  lime.  The  gelatin  in  the  shells 
is  converted  into  charcoal  which  burns  with  difficulty,  and  is  long  retained  in  the  interior  of  the  stones 
while  the  lime  is  burnt.  Now,  if  burnt  lime  is  heated  for  some  time  intimately  mixed  with  charcoal, 
the  basic  carbonate  is  produced — according  to  Fuchs. 

The  slaking. — Burnt  lime  is  of  a whitish-gray  color,  or  often  dirty  white,  seldom  pure  white ; it  is 
much  more  friable  than  fresh  limestone,  but  yet  sufficiently  solid  to  bear  carriage.  The  crystalline 
structure  of  many  varieties  of  lime  is  often  distinguishable  after  burning.  It  is  light  and  excessively 
porous.  In  consequence  of  its  porosity,  burnt  lime  absorbs  water  (about  18  per  cent.)  with  the  greatest 
avidity,  during  which  operation  tire  air  contained  in  the  pores  is  evolved  with  considerable  noise.  In  a 
few  minutes  (but  much  later  with  poor  lime)  the  saturated  lime  is  observed  to  become  hot,  and  from 
that  moment  the  combination  of  lime  and  water  proceeds.  The  lumps  of  lime  fall  to  pieces  with  a 
crackling  sound,  and  the  smaller  pieces  are  reduced  to  powder  with  the  evolution  of  much  steam,  until 
at  last  the  whole  is  converted,  with  a greatly  increased  volume,  into  a soft  uniform  white  powder,  i.  e., 
into  hydrate  of  lime.  For  building,  it  is  customary  to  place  the  lime  in  slaking  tubs,  or  into  flat  boxes 
constructed  of  boards,  with  a spout,  and  to  pour  as  much  water  into  them  as  will  nearly  cover  the  lime. 
During  the  slaking  of  the  lime,  the  excess  of  water  is  heated  to  lively  ebullition,  and  the  workmen  en- 
deavor to  mix  the  lime  and  water  in  a uniform  manner  with  a hoe.  If  the  proportion  of  water  was 
correctly  estimated,  a uniformly  thick  semi-liquid  mass  results.  In  the  formation  of  hydrate  of  lime, 
100  parts  of  pure  lime  combine  with  32  parts  of  water,  or  nearly  J. 

The  conversion  of  liquid  into  solid  water  may  be  viewed  as  the  proximate  cause  of  the  great  evolu- 
tion of  heat  which  accompanies  the  slaking  of  lime,  inasmuch  as  the  water  must  be  contained  in  this 
state  in  the  solid  hydrate  of  lime.  Suppose  3 lbs.  of  lime  to  be  slaked,  these  will  combine  with  1 lb.  of 
water,  for  instance,  and  convert  it  into  the  solid  form.  In  this  process,  a quantity  of  heat  is  liberated 
sufficient  to  bring  079  or  | lbs.  of  water  to  the  boiling  point.  In  practice  the  amount  of  heat  is  much 
greater,  for  a boiling  temperature  is  attained  when  the  lime  is  covered  with  three  times  the  quantity  of 
water.  The  conversion  of  water  from  the  liquid  to  the  solid  state  is,  consequently,  not  the  only  source 
of  the  heat,  the  remainder  must  be  accounted  for  by  the  chemical  action  which  ensues.  As  a proof  of 
this,  the  fact  may  be  adduced  that  lime  heats  with  snow  or  ice.  When  a large  excess  of  water  is  used, 
the  heat  evolved  is  more  diffused  and  less  intense ; it  increases  with  a lesser  quantity,  and  attains  a 
maximum  when  no  more  is  added  than  enters  into  combination  with  the  lime.  The  heat  has  then  been 
observed  to  attain  the  temperature  required  to  ignite  sulphur  and  gunpowder,  or  even  wood.  If  the 
lime  is  moistened  with  water  in  the  dark,  it  becomes  red-hot  and  emits  a lively  luminous  appearance; 
in  this  case,  the  heat  is  concentrated  by  the  surrounding  lime  which  is  not  in  the  act  of  being  slaked. 
The  heat  is  in  general  so  much  the  more  intense  the  more  rapidly  the  lime  is  slaked ; or,  is  in  propor 
tion  to  its  purity  and  the  proper  degree  of  causticity  attained  in  the  kiln.  The  temperature  of  slaking 
must  always  be  attended  to,  as  it  influences  the  quality  of  the  lime,  and  must  be  regulated  by  a cautious 
addition  of  water;  when  no  more  water  is  added  to  the  lime  than  it  can  absorb,  it  does  not  form  a soft, 
jut  a sandy  (coarseR-  crystalline)  powder,  and  is  said  to  have  been  rendered  poor  by  slaking.  The 


LIME. 


builders  have,  therefore,  a good  reason  for  slaking  the  lime  at  once  to  the  form  of  an  impalpable,  and 
not  a coarse  powder.  Rather  more  than  3 parts  of  water  are  required  for  this  purpose.  If  lime  is  only 
speedily  dipped  in  water  in  a basket,  so  that  it  falls  to  powder,  and  is  afterwards  mixed  with  moie 
water,  it  does  not  increase  more  than  to  2£  volumes;  if  allowed  to  fall  to  powder,  exposed  to  the  air, 
and  then  made  into  a paste  with  water,  it  will  only  yield  1'7  volumes. 

Influence  of  the  air. — Exposed  to  the  air,  burnt  lime  is  converted  very  slowly  and  without  any  eleva- 
tion of  temperature  into  a rough,  coarse  powder,  containing  small  angular  pieces ; it  then  effervesces 
vigorously  with  acids. 

As  large  quantities  of  lime  must  be  kept  ready  slaked  for  the  purposes  of  the  builder,  and  it  is  neces- 
sary to  protect  it  from  the  action  of  the  atmosphere  which  would  render  it  useless  as  mortar,  it  is  cus- 
tomary to  preserve  it  in  deep  pits.  The  slaking-tub  is  placed  in  front  of  a pit  into  which  the  slaked 
lime  in  the  semi-liquid  state  is  allowed  to  flow  until  the  pit  is  filled.  The  lime  becomes  fatter  and 
tougher  in  the  pit,  those  pieces  becoming  gradually  slaked  which  resisted  the  first  action  of  the  water. 
The  excess  of  water  collects  on  the  surface  and  can  be  removed  ; the  pit  is  then  covered  with  a layer  of 
sand  two  or  three  inches  in  thickness,  and  the  lime  is  thus  preserved  totally  unchanged.  In  removing 
the  ruins  of  the  castle  of  Landsberg  in  order  to  lay  the  foundations  for  a new  building,  it  is  stated  by 
Jabn,  that  a lime-pit  of  considerable  dimensions  was  found  in  one  of  the  vaults.  The  surface  of  this 
mass  of  lime  was  carbonated  to  the  depth  of  a few  inches,  but  all  below  that  was  in  the  state  of  freshly 
slaked  lime,  only  somewhat  more  dry.  This  lime,  which  was  certainly  more  than  300  years  old,  and 
valued  at  several  hundred  florins,  was  consequently  used  in  constructing  the  new  building. 

Hydraulic  lime.—' Those  varieties  of  lime  which  contain  about  10  per  cent,  of  silica  or  silicates,  as- 
sume different  properties,  and  although  they  are  only  slowly  slaked  after  burning  and  poor,  yet  when 
made  into  a dough  with  water,  they  soon  become  solid,  and  exposed  in  this  state  to  the  constant  action 
of  water,  acquire  a high  degree  of  consistence,  and  are  rendered  hard,  like  stone,  without  being  subse- 
quently loosened  or  eaten  away  by  the  water,  and  are  very  appropriately  called  hydraulic.  As  the 
hydraulic  property  is  solely  due  to  a chemical  process,  it  can  only  be  explained  and  understood  by  ref- 
erence to  the  chemical  nature  of  the  stones.  The  following  are  the  results  of  Bertliier’s  analyses,  witli 
the  exception  of  the  last  number,  which  was  analyzed  by  Kersten  : 


The  fresh  Limestones  contained  in  100  parts  : 


1 

1 

2 

3 

4 

5 

6 

7 

8 

9 

Carb.  of  lime 

90-0 

89-0 

89-0 

89-0 

85-8 

82-5 

80-0 

79-2 

76-5 

“ “ magnesia 

5-0 

3'2 

2-0 

2-0 

0-4 

41 

1*5 

2-5 

3*0 

“ “ protox.  iron... 

— 

— 

— 

— 

6-2 

— 

— 

6-0 

3-0 

“ “ protox.  mang. 

— 

t 

— 

— 

— 

— 

— 

— 

1-5 

Silica 1 

— 

— 

— 

— 

— 

— 

17  0 

f>*5 

11-6 

Alumina I 

— 

— 

— 

— 

— 

— 

1-0 

3-8 

3‘6 

Oxide  of  iron f 

5-0 

7-8 

90 

9-0 

5-4 

13.4 







Carbon j 

— 

— 

— 

— 

— 

— 

— 

2-0 



Water 

— 

— 

— 

— 

— 

— 

l-o 

— 

— 

The  Lime 

obtained  by  burning  the  above  contained  in  100 parts: 

Lime 

87-0 

84-0 

82-0 

82-0 

83-0 

79-3 

70-0 

74-0 

68-3 

Magnesia 

4-0 

2-5 

L5 

1-5 

— 

8-5 

1-0 

2 0 

2-0 

Clay  

9-0 

13'5 

16-5 

16-5 

7-0 

16-7 

29-0 

17-0 

24-0 

Oxide  of  iron 

— 

— 

— 

— 

10-0 

— 

— 

7-0 

5-7  | 

The  first  five  numbers  yield  lime  of  very  moderate,  the  last  four,  of  a very  marked  hydraulic  chai  - 
acter.  It  will  be  seen  by  the  table  below,  that  this  property  increases  with  the  quantity  of  matter  in- 
soluble in  muriatic  acid.  This  substance  consists  chiefly  of  a combination  of  silica  and  alumina,  but  is 
often  composed  nearly  entirely  of  silica  in  the  soluble  modification.  It  becomes  of  great  importance  to 
obtain  a knowledge  of  this  insoluble  portion,  as  upon  it  the  hydraulic  properties  depend.  This  has  con- 
sequently received  more  attention  in  recent  analyses,  as  will  be  seen  by  the  following  examples : 

Burnt  hydraulic  lime  is  (with  few  exceptions)  soluble  in  acids ; and,  in  proof  of  the  presence  of  a 
silicate  that  can  be  decomposed  by  acids,  a thick  jelly  of  silica  is  produced.  This  property  of  yielding 
gelatinous  silica  stands,  therefore,  in  intimate  connection  with  the  property  of  becoming  hard  under 
water.  Unburnt,  pulverized  stones  do  not  harden,  as  is  well  known  ; and  hydraulic  lime,  mixed  with 
water,  acquires  a certain  consistence  much  before  it  becomes  hard.  Moistened  hydraulic  lime  produces, 
m the  first  instance,  a connected,  very  soft,  friable  mass,  which  is  easily  scratched  by  the  nail ; at  a 
much  later  period,  this  mass,  when  covered  with  water,  acquires  a hardness  which  is  quite  equal  to,  and 
often  exceeds  that  of,  the  limestone  itself.  As  a general  fact,  the  time  in  which  different  hydraulic  lime- 
stones become  hard  is  very  variable,  and  the  chemical  action,  which  is  the  cause  of  the  hardening,  is 
consequently  very  unequal.  The  degree  of  hardness  which  they  acquire  is  also  not  the  same  ; those 
that  harden  slowly  are  often  more  compact  than  those  which  harden  in  a shorter  time.  The  time  re- 
quired for  hardening  varies  from  a few  minutes  to  weeks  and  months,  and  bears  some  relation  to  the 
amount  of  the  aluminous  constituent  in  the  lime.  The  more  the  limestones  contain  of  this  ingredient, 
the  more  quickly  they  harden.  The  hardening  and  solidification  of  the  hydraulic  stones  being,  therefore, 
dependent  upon  the  chemical  reaction  of  their  two  ingredients,  the  relative  proportions  of  these  cannot 
be  a matter  of  indifference ; and  as  there  are  varieties  which,  from  the  smaller  quantity  of  the  silicious 
constituents  contained  in  them,  approach  the  ordinary  limestones  in  properties,  so  there  are  others,  iif 


228 


LIME. 


which  this  ingredient  obtains  so  great  a preponderance,  and  in  which  the  amount  of  carbonate  of  lime  ii 
so  small,  that  they  no  longer  exhibit  the  hydraulic  property.  All  mineral  substances  which  possess  the 
property  of  rendering  ordinary  limestone  hydraulic,  are  very  appropriately  called  cements. 


Contains  silicious  clay. 

Moderately  good 
hydraulic  lime. 

Ordinary  hydraulic 
lime. 

Best  hydraulic 
lime. 

Intermediate  lime. 

Bad  intermediate 
cement. 

Ordinary  cement. 

Best  intermediate 
cement. 

Transition  to  Puz- 
zolana. 

Before  burning  (to  100  car-  ) 
bonate  of  lime.)  ) 

12 

20  25 

30 

37 

56 

156 

510 

After  burning  (to  100  caustic  ) 
lime.)  ) 

22 

36  | 44 

53 

65 

100 

273 

900 

This  division  is  of  course  quite  arbitrary,  no  classes  existing  in  nature,  but  only  transitions ; it  is, 
however,  convenient  when  its  true  signification  is  borne  in  mind.  There  must  necessarily  be  numerous 
exceptions,  for  this  reason,  that  the  property  of  hardening  in  one  and  the  same  specimen  of  lime  varies 
with  the  temperature  at  which  it  has  been  burnt ; thus  several  varieties  belonging  to  the  third  class, 
when  imperfectly  burnt  (i.  e.,  when  the  whole  of  their  carbonic  acid  has  not  been  expelled)  yield  an  hy- 
draulic lime  of  the  second  best  quality.  Yicat  has  determined  in  single  cases  the  amount  of  imperfect 
calcination  by  the  amount  of  carbonic  acid  not  expelled  from  the  lime,  and  has  tested  the  property  ol 
hardening  in  these  different  gradations.  Thus  one  variety  of  limestone  in  which  the  carbonic  acid  re 
maining  in  it 


amounted  to 

30  per  cent. 

27  per  cent. 

26  per  cent. 

23  per  cent. 

20  per  cent. 

10  per  cent 

yielded  a mortar 
which  hardened  in 

15  minutes 

12  minutes 

7 minutes 

9 days 

30  days 

9 days. 

whence  it  is  obvious,  that  in  the  course  of  calcination,  and  with  the  increase  in  the  amount  of  caustic 
lime,  a great  diversity  of  relations  between  it  and  the  aluminous  constituent  are  created,  upon  one  of 
which,  or  upon  several  at  once,  the  property  of  rapidly  hardening  is  chiefly  dependent.  Too  much  heat 
in  the  kiln  and  incipient  fusion,  renders  the  lime  very  much  weaker  than  it  should  be  when  the  process 
is  properly  conducted,  and  at  last  disqualifies  it  completely.  It  must  be  noticed  lastly,  that  hydraulic 
lime  never  hardens,  when  it  is  immediately  immersed  in  water,  before  having  acquired  a certain  con- 
sistence. In  this  case,  the  particles  never  agglutinate  properly  together,  but  form  a porous  mass. 

Many  limestones,  particularly  those  which  form  the  boundary  between  the  hydraulic  limestones  and 
the  cements,  possess  the  very  objectionable  property  of  containing  portions  which  slake  at  a subsequent 
period,  when  the  greater  bulk  has  already  solidified  and  become  hard.  The  mortar  then  falls  to  pieces. 
and  is  rendered  perfectly  useless.  It  would  appear  as  if  particles  of  lime  were  in  this  case  so  enveloped, 
as  only  to  become  penetrated  by  the  water  in  the  course  of  the  process  of  hardening. 

Calcination. — Hydraulic  lime  is  burnt  in  a similar  manner  to  ordinary  limestone  ; a much  less  degree 
of  heat,  however,  is  required.  Perpetual  kilns  are  used ; the  burnt  stones  are  reduced  to  powder 
under  stampers  or  ground  in  a mill ; the  powder  is  passed  through  a sieve,  and  is  then  in  a fit  state 
for  use. 

Those  varieties  of  hydraulic  lime  which  slake  easily,  need  not  even  be  reduced  to  powder.  A great 
error  is,  however,  committed  in  exposing  the  hydraulic  lime  (particularly  in  the  state  of  powder)  for 
any  length  of  time,  during  carriage,  or  in  warehouses,  to  the  moisture  in  the  atmosphere ; the  greater 
part  of  its  good  properties  are  thus  gradually  destroyed,  and  it  afterwards  hardens  very  slowly  or  not 
at  all.  It  need  hardly  be  mentioned,  that  a larger  stock  of  hydraulic  lime  should  never  be  made  than 
is  intended  for  immediate  consumption.  With  reference  to  this  point,  Yicat  has  shown,  that  hydraulic 
lime  which  has  once  attracted  moisture,  may  be  made  to  set,  by  renewed  pulverization  and  mixture 
with  water;  but  the  action  is  much  slower,  and  it  is  converted  into  an  article  of  the  worst  quality. 

Theory  of  hardening  or  solidification. — The  solidification  of  hydraulic  lime  is  supposed  to  be  due  to 
the  presence  and  mutual  action  of  the  silica  and  caustic  lime  contained  in  it.  The  final  result  is  derived 
from  two  operations.  During  calcination , the  lime  is  rendered  caustic  by  the  evolution  of  carbonic 
acid,  and  this  caustic  lime  then  reacts  upon  the  silicious  clay,  converting  it  into  a compound  that  is  easily 
decomposed  by  acids.  The  excess  of  caustic  lime,  as  well  as  the  compound  into  which  the  silicious 
clay  has  been  converted,  then  react  upon  each  other,  when  mortar  is  prepared  from  the  ground  burnt 
lime,  in  such  a manner,  that  a solid  stone-like  silicate  is  produced  in  the  humid  way.  The  water  here 
obviously  has  a double  action.  Dry  substances,  like  lime  and  the  silicate  of  alumina,  act  very  little,  or, 
nnder  certain  circumstances,  not  at  all,  upon  each  other,  unless  the  solvent  power  of  water  is  employed 
to  bring  them  into  intimate  contact.  During  solidification,  the  water  will  constantly  transfer  the  lime 
which  it  has  dissolved,  to  the  silicious  particles ; it  will  then  dissolve  fresh  lime,  which  is  again  om 


LIME. 


229 


ployed  in  the  production  of  the  silicate,  and  so  on.  The  process  of  solidification  is  not  so  much  the  con- 
version of  a ready  formed  silicate  into  a hydrate,  as  the  format  ion  of  a hydrated  silicate  in  one  and  the 
same  operation. 

The  action  of  the  day. — The  silica  may  be  replaced,  as  is  indeed  the  case  in  the  greater  number  of 
dydraulic  limestones,  by  different  silicates.  Amongst  these,  the  clays  are  the  most  important. 

The  great  diversity  in  the  nature  of  the  clays  does  not  admit  of  the  supposition  that  their  action  is 
always  the  same,  but  nevertheless  they  all  yield  a substance  with  lime  which  hardens  well,  and  in  some 
cases  affords  excellent  mortar.  All  must  be  previously  burnt,  particularly  potter’s-clay.  In  some 
cases,  it  is  necessary  to  calcine  the  clay  with  lime.  The  common  ferruginous  brick-earth  hardly  binds 
at  all  with  lime  when  only  slightly  burnt,  but  when  strongly  heated,  to  the  point  of  incipient  fusion, 
the  oxide  of  iron  enters  into  combination  with  the  clay,  aDcl  a vei-y  powerful  solidification  then  ensues 
with  lime. 

Artificial  hydraulic  lime. — Artificial  mixtures  of  appropriate  silicates  with  lime,  under  proper  treat- 
ment, possess  the  hydraulic  property  in  quite  as  eminent  a degree  as  the  natural  productions.  Experi- 
ence has  indeed  anticipated  theory  in  this  fact  by  several  centuries.  The  Romans  were  well  acquainted 
with  the  use  of  lime-mortar,  and  applied  it  both  in  the  construction  of  buildings  and  roads ; they  also 
soon  made  the  important  discovery  that  a certain  soft,  porous,  almost  earthy  rock,  containing  pumice- 
stone,  and  resembling  this  in  composition,  and  which  was  found  on  the  coasts  of  the  Bay  of  Bay®  and 
Naples,  particularly  in  the  neighborhood  of  Puteoli,  possessed  the  valuable  property  of  forming  an  hy- 
draulic mortar  with  burnt  lime.  They  called  the  rock  pulvis  Putcolanus ; it  is  described  by  Vitruvius 
and  by  Pliny,  and  was  employed,  mixed  with  an  equal  quantity  of  lime,  for  building  under  water.  The 
pulvis  Puteolanus  was  precisely  the  same  substance  as  is  known  in  the  present  day  under  the  name  of 
Puzzolana.  The  modern  name  of  the  town  Puteoli  is  Puzzuoli. 

2Vass,  or  tarras. — After  entering  Germany,  and  having  taken  possession  of  the  Rhine,  the  Romans 
soon  recognized,  in  the  layers  of  trass,  near  Bonn,  the  well-known  pulvis  Puteolanus,  and  opened  the 
quarries,  whence  this  important  material  is  distributed,  far  and  wide,  even  to  the  present  day.  Both 
Puzzolana  and  trass  are  conglomerates  of  fragments  of  volcanic  rocks,  transposed  by  the  agency  of 
water  from  their  original  sites  ; they'often  contain  fragments  of  basalt,  pumice-stone,  trachyte,  clay-slate, 
&c..  indicating  at  once  the  connection  of  the  one  with  Vesuvius,  and  of  the  other  with  the  volcanoes  of 
Eifel.  The  trass  in  Brohlthal  is  derived  from  the  constituents  of  the  trachyte  rocks  in  the  neighborhood ; 
it  forms  very  thick  beds,  often  filling  entire  valleys,  and  is  in  the  form  of  a friable,  easily  pulverized 
stone,  the  color  of  which  is  generally  light,  passing  from  a yellowish  to  a greenish  hue.  It  is  ground  in 
a number  of  stamping-mills  in  the  neighborhood,  and  exported  in  the  form  of  a fine  powder.  Like  most 
other  volcanic  productions,  as  basalt,  klingstein,  &c.,  trass  is  resolved  into  two  distinct  silicates  by  chem- 
ical agency.  The  one  is  readily  soluble  in  muriatic  acid,  the  other  resists  solution. 

Puzzolana. — Berthier  found  the  Italian  Puzzolana  composed  of  44’5  per  cent,  silica,  15  0 alumina,  8'8 
lime,  4’7  magnesia,  12'0  oxide  of  iron  and  titanium,  1'4  potash,  4T  soda,  and  9’2  water. 

Clay  as  cement. — All  those  substances  which  render  fat,  slaked  lime  hydraulic,  are  called  cements. 
Puzzolana,  trass,  and  all  similar  cements  have  the  advantage  of  requiring  no  preparation  by  burning, 
but  are  capable  of  acting  iii  the  natural  state — of  course  in  fine  powder,  that  they  may  be  properly 
mixed.  All  varieties  of  clay,  to  be  used  for  cements,  must  be  disintegrated  by  burning,  with  or  without 
a certain  proportion  of  lime,  according  to  their  different  characters.  They  then  afford  very  powerful 
cements,  which  property,  however,  is  very  much  influenced  by  the  temperature  to  which  they  have  been 
exposed,  and  the  manner  in  which  they  have  been  burnt.  Treussart  made  some  bricks  from  a clay 
which  is  used  in  Strasburg  for  the  manufacture  of  alum,  and  contains  50  silica,  32’7  alumina,  T6  mag- 
nesia, with  mere  traces  of  oxide  of  iron ; a part  of  these  he  burnt  in  the  alum-furnace,  and  the  others  in 
a lime-kiln.  When  the  burnt  clays  were  made  into  mortar  with  half  their  weight  of  slaked  lime,  a 
great  difference  was  observed  in  the  two  kinds ; that  which  had  been  burnt  in  the  alum-furnace  hard- 
ened in  two  or  three  days,  and  would  withstand  a weight  of  400  pounds  without  being  crushed,  while 
that  from  the  lime-kiln  did  not  harden  for  thirty  days,  and,  placed  in  the  same  circumstances,  broke 
under  a weight  of  fifty  or  sixty  pounds.  A similar  comparison,  instituted  with  two  mortars,  also  com- 
posed of  one  part  slaked  lime  and  two  parts  cement,  the  one  of  which  consisted  of  simple  clay,  the 
other  of  clay  that  had  been  calcined  with  2 per  cent,  of  lime,  led  to  the  same  result  in  favor  of  the  latter 
mortar,  which  hardened  in  17  days,  while  the  former  required  30  days. 

The  excellent  hydraulic  mortar  of  Tournay,  known  under  the  name  of  “ cendree ,”  is  prepared  from 
the  refuse  which  is  left  on  burning  the  lias  limestone.  This  waste,  which  remains  after  removing  the 
lumps  oi  lime,  consists  of  small  fragments  of  lime  and  of  the  ash,  (the  coal  there  used  yielding  a large 
amount  of  ash,)  in  about  the  proportions  of  1 : 3.  The  mixture  is  slaked  in  a small  quantity  of  water, 
and  before  being  used  is  well  beaten  and  worked  about. 

Dr.  Eisner  has  published  the  following  analyses  of  certain  iron  slags  which  are  found  to  afford  excel- 
lent hydraulic  mortar  when  mixed  with  burnt  lime : 


I. 

II. 

Silica 

40*44 

Alumina 

15-38 

Lime 

33-10 

Protoxide  of  manganese 

4-40 

Protoxide  of  iron 

1-25 

1-63 

Potash  

2-07 

Sulphur 

o-7  e 

These  slags  in  the  state  of  fine  powder,  when  treated  with  a small  quantity  of  muriatic  acid,  are 
rapidly  converted  into  a uniform  gelatinous  mass. 

It  is  easy  to  ascertain  whether  a slag  is  suited  for  the  production  of  hydraulic  cement,  by  pouring 


230 


LINK-MOTION. 


over  it,  in  the  state  of  fine  powder,  a small  quantity  of  hydrochloric  acid ; if  it  forms  a gelatinous  mass 
after  a short  time,  it  will  then  yield,  with  lime,  a proper  mixture  for  hydraulic  mortar. 

Roman  cement. — It  is  a remarkable  fact  in  the  history  of  hydraulic  mortars,  which  originates,  as  we 
have  seen,  with  the  Puzzolana  and  trass  employed  by  the  Romans,  that  the  more  the  knowledge  of 
their  uses  has  been  spread,  the  more  substances  have  been  discovered  which  either  act  as  hydraulic 
mortars  themselves,  or  can  be  mixed  as  cements  in  the  preparation  of  artificial  mortar ; so  that  what 
appeared  originally  a privilege  accorded  to  a few  favored  spots  only,  can  now  be  obtained  almost 
everywhere.  A strong  inducement  to  study  the  nature  and  modes  of  occurrence  of  hydraulic  lime  was 
created  by  the  patent  granted  to  Parker  and  Wyatt,  in  London,  in  the  year  1796,  for  what  they  termed 
“ Roman  cement.”  The  material  employed  in  the  manufacture  of  this  cement  are  the  nodules,  of  an 
ovoidal  or  globular  form,  which  are  found  in  the  London  clay,  and  known  by  the  name  of  Septaria. 
They  are  calcined  in  perpetual  lime-kilns  with  coal,  in  which  a very  moderate  and  well-regulated  heat 
is  carefully  preserved.  After  calcination,  the  stones  are  ground  under  heavy  edgestones  to  a very  fine 
powder,  which  is  sifted,  and  then  packed  in  casks  for  sale.  These  nodules  are  found  in  many  localities 
in  this  country. 

Roman  cement  is  one  of  the  most  powerful  hydraulic  mortars,  and  is  exceedingly  valuable,  not  only 
on  account  of  the  rapidity  with  which  it  hardens,  and  this  is  effected  in  a very  few  minutes,  but  because 
when  hardened  in  considerable  masses  it  is  not  liable  to  crack. 

All  artificial  or  natural  hydraulic  limestones  are  soluble  (before  as  well  as  after  calcination)  in  mu- 
riatic acid  with  the  separation  of  silica,  except  when  sand  or  some  similar  substance  has  been  added 
lo  them. 

The  hydraulic  limestones,  when  they  do  not  contain  a sufficient  quantity  of  lime  to  be  capable  of 
slaking  with  water,  must  be  very  finely  pulverized  ; it  is  only  by  this  high  state  of  division  that  a 
proper  action  can  ensue.  A thorough  penetration  of  the  silicious  portion  by  the  lime  is  never  entirely 
effected,  but  a certain  proportion  remains  inclosed  and  removed  from  the  sphere  of  action.  See 
Mortar. 

LINK  MOTION. — Variable  expansion  gear,  now  generally  used  on  locomotives  for  the  movement  cl 
the  steam  valves,  first  invented  by  Mr.  Williams  of  Newcastle.  Williams’  incipient  link  was  a slotted 
straight  bar,  which  connected  the  straps  of  the  fore  and  hack  eccentrics,  formed  with  ears  to  secure  the 
linking  pins.  In  the  slot  of  the  link,  a slide-block  hung  on  the  end  of  a radius  link  from  the  valve  spin- 
dle, was  adjustable  towards  one  end  or  the  other,  to  receive  the  motion  of  the  one  or  the  other  eccentric 
for  fore  or  back  gear ; while  the  link  would  partake  jointly  of  the  two  motions  of  the  eccentrics,  its  hor- 
izontal motion  would  be  smallest  at  the  centre  of  its  length,  and  increase  towards  the  extremities  : thus 
by  shifting  the  block  towards  the  centre,  the  travel  of  the  valve  would  be  reduced,  and  variable  expan- 
sion thereby  obtained. 

The  objections  to  the  special  arrangement  here  proposed  are  obvious  ; the  idea  has  however  been  de- 
tffoped  by  Mr.  Howe,  into  the  more  practicable  arrangement  first  applied  to  the  engines  of  Robert 
'Mephenson  & Co.  in  1843,  and  from  this  time  the  link  has  been  adopted  generally  by  all  other  English 

manufacturers. 

Link  motions  are  all  of  two  classes,  in  which, 
first  the  link  is  suspended  directly  from  a fixed  point 
as  a stationary  link,  fig.  2601 ; secondly,  the  link 
is  movable  vertically,  (fig.  2602,)  carrying  with  it 
of  course,  the  eccentric  rods  which  are  directly  con- 
nected to  it.  In  the  first  class,  therefore,  the  va- 
riable expansion  is  accomplished  by  shifting  the' 
sliding  blocks  in  the  link : in  the  other  class,  the 
link  is  shifted  upon  the  block.  The  link  itself  is 
employed  under  three  general  forms,  distinguished 
as  much  by  structural  characteristics  as  by  pecu- 
liarity of  action.  The  box  link,  the  open  link 
joined  to  the  eccentric-rods  at  the  extremities,  and 
the  open  link  joined  behind.  The  box-link,  fig. 
2598,  is  formed  in  two  halves  or  sides  bolted  to- 
gether at  the  extremities,  enclosing  a rectangular 
recess  for  the  reception  of  the  block  as  shown  in  section.  The  eccentric-rods  are  attached  to  the 
extreme  stud  pins,  forged  on  the  outside  of  the  link,  and  thus  a clear  way  is  obtained  for  the 
blocks  from  one  end  of  the  link  to  the  other ; they  may  be  shifted  even  to  a position  concentric 
with  the  eccentric  rod  ends.  The  two  forms  of  open  fink  are  adopted  with  a view  to  simplify  the 
parts,  the  one  (fig.  2600,)  with  the  extreme  connections,  is  the  form  first  used  by  Stephenson;  by 
its  form  it  does  not  pei-mit  of  the  block  being  placed  concentric  with  the  eccentric  rod  ends,  the  range 
being  so  limited,  it  is  plain  that  the  block  never  can  receive  and  transmit  the  full  throw  of  the  ec- 
centric to  the  valve,  a feature  in  which  the  box-link  has  the  advantage.  With  this  link  the  throw  of 
the  eccentrics  and  therefore  their  diameters,  must  be  greater  than  those  required  by  the  box-link  for  a 
given  maximum  travel  of  valve.  The  third  form  of  link,  (fig.  2599,)  connected  behind,  permits  of  the 
same  freedom  for  the  block  that  is  yielded  by  the  box-link ; the  block  may  be  shifted  to  a position  level 
with  the  point  of  attachment  at  which  it  may  transmit  the  whole  throw  of  the  eccentric.  The  over- 
hung nature  of  this  knuckle-jointed  sort  of  link,  and  its  peculiarly  irregular  movements  in  consequence, 
render  it  a more  ticklish  variety  than  the  others ; as,  however,  it  combines  the  advantage  of  the  box- 
link  in  respect  of  the  transmission  of  the  whole  motion,  with  the  simplicity  of  the  other  link,  it  is  now 
most  commonly  employed,  at  least  in  locomotives,  where  vertical  clearance  is  limited. 

The  first  qualifications  of  expansion  gear  are  to  insure  for  every  variation  of  expansive  action,  a free 
admission  and  free  release  for  the  steam  ; to  render  the  periods  of  admission  equal  for  the  front  and  back 


LINK-MOTION. 


231 


itrokes,  and  to  promote  the  expansive  action  of  the  steam  sufficiently  to  extract  the  most  if  not  the  whok 
of  its  works  for  propulsion,  excepting  a per  centage  required  for  the  purposes  of  the  blast. 


2G00. 


Lead.  In  the  stationary  link-motions,  a constant  lead  throughout  the  forward  and  backward  gear 
is  obtained  by  circling  the  link  to  the  radius  of  the  valve-rod  link,  and  the  same  lead  may  be  for  the 
front  and  back  strokes.  In  the  shifting  link  motion,  the  lead  essentially  varies  with  the  expansion,  the 
greater  the  degree  of  expansion — that  is,  the  less  the  admission  the  greater  also  is  the  lead;  the  lead 
is  thus  least  in  full  gear,  and  attains  its  maximum  in  the  mid  gear ; it  may  however  always  be  made  the 
same  for  the  front  and  back  strokes,  and  thus  equality  is  obtained  by  circling  the  link  to  the  radius  of 
the  eccentric  rod.  Thus  the  conditions  of  constant  lead  and  varying  admission  which  are  incompatible 
with  the  nature  of  the  shifting  link,  motion  are  obtainable  by  the  stationary  link  with  a single  valve. 
The  longer  the  eccentric-rod,  and  the  shorter  the  link,  the  less  is  the  variation  of  lead  in  the  shifting- 
link  motion.  The  shifting-link  motion  may  with  advantage  be  set  with  the  desired  lead  in  half  gear, 
which  is  the  most  ordinary  working  position  of  the  mechanism  ; the  evil  of  varying  lead  is  thus  divided 
and  reduced. 

Linear  Advance.  With  the  stationary  link  the  linear  advance  of  the  eccentrics  is  in  all  cases  less  than 
that  of  the  valve,  and  is  a quality  affected  by  the  length  of  the  eccentric-rods;  these  rods  by  their 
varying  obliquity  increase  the  advance  while  transmitting  it  to  the  link,  and  the  shorter  the  rods  the 
greater  is  the  difference  so  caused.  With  the  shifting-link,  the  linear  advance  of  the  valve  is  in  all  cases 
equal  to  that  of  the  eccentrics  in  full  gear,  independent  altogether  of  the  length  of  the  rods — expressly 
meaning  by  full  gear,  that  the  fore  rod  end  is  brought  into  the  centre  line  of  the  valve  rod ; in  other  po- 
sitions, however,  the  linear  advance  of  the  valve  varies  precisely  with  the  lead,  as  the  lead,  in  fact,  partly 
constitutes  the  advance. 

The  Motion  of  the  Unk.  The  motion  of  the  link  is  composed  of  the  distinct  motions  of  the  ec- 
centrics, and  every  part  of  the  link  is  subject  to  this  compound  influence.  The  motion  of  each 
eccentric  prevails  in  that  half  of  the  link  to  which  it  is  coupled,  and  at  the  centre  the  motion  of  the 
link  is  equally  composed  of  the  two.  The  final  result  of  this  combined  action  is  approximately  the 
same  as  that  available  by  the  action  of  a single  eccentric  of  variable  throw.  Thus  the  object  which 
was  proposed  to  be  obtained  by  the  spiral  and  wedge  reversing  motions  of  Fenton  and  Dodd's  variable 
expansion,  with  (if  possible)  constant  lead,  is  realized  in  the  simplest  manner  by  the  combined  operation 
of  two  eccentrics,  and  with  an  efficiency  and  precision  which  probably  the  original  promoters  of  the 
link  motion  did  not  anticipate.  Horizontal  motion  communicated  to  the  link  by  the  joint  action  of  the 
eccentrics  is  a minimum  at  the  centre  of  its  length,  where  it  is  equal  to  twice  the  linear  advance,  and 
it  increases  towards  the  extremities  various  periods  of  the  block  in  the  link,  or  of  the  link  on  the  block, 
on  the  general  principle  that  admission  varies  with  the  travel  of  the  valve.  The  distribution  derived 
from  the  link  is  affected  by  the  lengoh  of  the  connecting-rod  relative  to  that  of  the  crank ; the  shorter 
the  rod,  the  greater  is  the  front  admission,  and  the  less  is  the  admission  for  the  back  stroke  ; therefore 
the  term  “ link-motion  ” in  so  far  as  it  involves  the  relation  of  the  valve’s  motion  to  that  of  the  piston, 
virtually  includes  the  proportions  of  the  piston  motion.  The  quality  of  the  motion  derived  from  the 
link  is  modified  by  the  positions  of  the  working  centres,  and  most  especially  of  the  centres  of  suspension 
and  connection ; the  centre  of  suspension  is  the  most  influential  of  all  in  regulating  the  admission,  and 
its  transition  horizontally  is  much  more  efficacious  than  a vertical  change  of  place  to  the  same  extent. 
The  periods  of  admission  in  half  gear  are  much  more  sensitive  to  variation  by  mode  of  suspension  and 
connection  than  those  in  full  and  mid  gear.  It  is  expedient  to  set  the  motion  right  for  this  position  as 
regards  the  quality  of  the  admissions,  because  these  differences  for  other  positions  are  then  inconsiderable. 
There  are  certain  neutral  positions  of  the  centre  of  the  suspension,  on  which  the  link  in  vibrating  yields 
equal  admissions,  and  these  may  be  found  for  any  specific  arrangement  by  the  method  of  three  trails. 
These  neutral  positions  may  be  located  either  in  the  centre  line  of  the  link,  vertically  or  horizontally 
in  the  neighborhood  of  the  middle  of  the  link.  As  the  vertical  movement  of  the  body  of  the  link  with  the 
consequent  slip  between  the  link  and  the  block  is  the  least  possible  when  the  suspended  centre  lies  in 
the  centre  line  of  the  link,  increasing  as  the  centre  is  removed  laterally,  the  centre  line  of  the  link  is,  in 
this  respect,  the  most  favorable  locality  for  the  suspension,  though  not  always  practicable  for  equal  admis- 
sions. It  has  been  found  that  the  stationary  and  shifting  links  have  not  the  same  neutral  centres  of  sus- 
pension; that  in  general  the  stationary  link  should  be  hung  by  a centre  in  the  neighborhood  of  the  mid- 
dle of  its  length,  and  the  shifting  link  towards  one  of  the  extremities.  The  periods  of  expansion  and  release 


232 


LITHOGRAPHY. 


increase  as  those  of  admission  are  diminished,  and  when  the  points  of  suppression  are  equally  adjusted 
those  of  release  do  not  considerably  differ.  It  has  been  found  in  short,  that  in  valves  the  admissions  and 
the  expansions  may  be  made  absolutely  identical,  as  in  the  Great  Western  link,  fig.  2601.  An  admission 
of  75  per  cent,  or  three-fourths  of  the  stroke  is  attended  with  a mean  expansion  of  16  percent,  of  expan- 
sion, exhausting  at  80  per  cent.  The  utmost  period  of  expansion  obtained  by  a stationary  link  in  mid 
gear  is  38  per  cent,  for  12  per  cent,  of  admission,  in  which  case  the  steam  is  cut  off  at  less  than  one- 
eighth  of  the  stroke,  and  expanded  into  a volume  of  50  per  cent.,  or  one  half  stroke  4 times  the  initial 
volume  exclusive  of  clearance,  after  which  it  exhausts  during  the  remaining  half  stroke.  With  the 
stationary  link  the  shortest  admission  is  1 1 per  cent.,  or  one-ninth  of  the  stroke,  expanding  into  50  per 
cent.,  or  44  times  the  initial  volume,  before  the  release  takes  place.  With  the  shifting-link,  the  smallest, 
attainable  admission  is  about  17  per  cent.,  or  one-sixth  of  the  stroke ; this  is  about  one-half  more  than 
what  is  obtained  by  the  stationary  link,  the  difference  being  due  to  the  excess  of  lead  yielded  by  the 
shifting.  As  the  release  takes  place  at  half  stroke,  the  shifting-link  cannot  expand  the  steam  above 
three  times  its  initial  volume,  exclusive  of  clearance.  The  average  period  of  admission  in  full  gear 
does  not  exceed  75  per  cent.,  or  three-fourths  of  the  stroke,  according  to  the  examples  before  us.  More 
than  this  should  not  be  required,  nor  indeed  could  it  be  beneficially  employed  at  regular  speed ; the  ad- 
mission may,  however,  be  increased  by  forcing  the  mechanism  of  the  valve  beyond  full  gear ; that  is,  by 
causing  the  block  to  woi’k  in  the  extreme  overhung  parts  of  the  link,  which  must  be  extended  for  the 
purpose  beyond  the  centres  of  connection*  by  .this  expedient  the  throw  of  the  valve  is  increased,  and  it 
is  practicable  with  the  box  and  back  hug  links,  and  may  in  many  cases  be  usefully  employed  when  a 
ready  start  with  a heavy  train  is  required. 

The  open  link  connected  by  its  extremities  in  its  own  centre  line,  is  identical  in  its  motions  with  the 
box-link  : in  the  use  of  that  fink  it  is  imperative  that  the  throw  of  the  eccentric  should  be  greater  than 
that  designed  for  the  valve,  as  in  full  gear  the  block  is  of  necessity  placed  nearer  to  the  centre  of  the 
link  than  the  rod  centres. 

LITHOGRAPHY.  The  art  of  transferring  from  stone  writings  or  drawings  made  thereon,  which  is 
of  quite  modern  invention.  Unlike  other  kinds  of  printing,  this  is  strictly  chemical,  and  is  in  conse- 
quence called,  in  Germany,  chemical  printing.  A drawing  is  made  on  the  stone,  either  with  ink  con- 
taining oleaginous  matter,  or  with  chalk  containing  similar  substances,  but  in  a more  concentrated  and 
indurated  state.  The  drawing  is  then  washed  over  with  water,  which  sinks  into  those  portions  of  the 
stone  that  are  untouched  with  the  grease  of  the  drawing.  A cylindrical  roller,  charged  with  printing- 
ink,  is  then  passed  all  over  the  stone,  and  while  the  drawing  receives  the  ink,  the  rest  of  the  stone  is 
preserved  from  it  by  the  water,  on  account  of  the  greasy  nature  of  the  ink.  This  art  is  said  to  have 
been  invented  by  mere  accident,  by  Alois  Senefelder,  of  Munich. 

The  stones,  and  the  manner  in  which  they  are  prepared  to  receive  the  drawings. — The  stone  most  used 
in  England  is  found  at  Corstan,  near  Bath ; it  is  one  of  the  white  lias  beds,  but  not  of  so  fine  a grain, 
nor  so  close  in  texture  as  the  German  stone,  and  therefore  inferior ; but  it  is  good  for  transfers,  and  does 
tolerably  well  for  ink  drawings  or  writings.  All  calcareous  stones  may  be  used  in  lithography,  be- 
cause they  imbibe  grease  and  moisture ; but  a stone  entirely  calcareous  does  not  answer  well : there 
should  be  a mixture  of  alumina  and  silex.  One  of  the  most  certain  indications  of  lithographic  properties 
is  the  conchoidal  fracture ; all  stones  of  this  kind  will  be  found  good,  if  they  are  also  hard,  have  the 
fineness  of  grain,  and  the  homogeneousness  of  texture  that  are  necessary.  It  is,  however,  said  that  none 
have  yet  been  found  equal  to  those  obtained  froni  the  quarries  of  Solenhofen,  near  Pappenheim,  in 
Bavaria,  and  that  the  lithographers  of  eminence  in  Paris  use  no  other.  In  order  to  sustain  the  pressure 
used  in  taking  impressions,  a stone,  12  inches  square,  ought  not  to  be  less  than  1 j inch  thick,  and  this 
thickness  should  increase  with  the  area  of  the  stone.  The  stones  are  first  sawn  to  a proper  size,  and  are 
then  ground  smooth  and  level  by  rubbing  two  of  them  face  to  face,  with  water  and  sand.  They  must 
be  very  carefully  examined  with  a straight-edge,  to  ascertain  that  they  are  perfectly  level  in  every 
direction.  This  applies  only  to  the  side  which  is  afterwards  to  receive  the  drawing,  as  the  natural  di- 
vision of  the  stone  is  sufficiently  true  for  the  back.  When  the  stones  have  thus  been  ground  perfectly 
level,  they  are  well  washed,  to  free  them  from  any  of  the  coarser  grains  of  sand  which  may  have  been 
used  in  smoothing  them.  They  are  then  placed  on  a board  over  a trough,  and  they  are  again  rubbed 
face  to  face  with  sand  and  water,  but  with  a sand  of  much  finer  texture  than  that  previously  used.  The 
greatest  care  must  be  taken  to  have  the  sand  sufficiently  fine  ; and  for  this  purpose  it  must  be  sifted 
through  a small  close  sieve,  as  a single  grain  of  sand  of  a coarser  texture  than  the  rest  will  scratch  the 
stone,  and  these  scratches  will  afterwards  appear  in  the  impression  taken  from  the  stone.  When  the 
stones  have  been  rendered  sufficiently  fine,  and  their  grain  sufficiently  smooth,  they  must  then  be  care- 
fully washed  and  afterwards  wiped  dry  with  a clean  soft  cloth.  This  is  the  plan  adopted  to  prepare 
the  stones  for  chalk  drawings,  but  to  prepare  them  for  ink  drawings  or  writings  the  following  method  is 
the  best : After  the  process  just  described  has  been  completed,  the  stones  are  well  washed  to  get  rid  of 
the  sand,  and  they  are  then  rubbed  together,  face  to  face,  with  powdered  pumice-stone  and  water. 
After  they  are  made  perfectly  smooth,  they  are  again  washed  and  wiped  dry,  and  are  then  separately 
polished  with  a large  piqpe  of  pumice-stone. 

To  clean  the  stones  after  they  have  been  fully  used,  sand  is  strewed  over  the  surface,  which  is  sprinkled 
with  water  and  rubbed  with  another  stone,  until  the  writing  or  drawing  upon  it  has  completely  disap- 
peared. It  must  then  be  washed  in  aquafortis,  diluted  with  twenty  times  its  bulk  of  water,  and  the 
stone  is  then  prepared  for  a new  drawing  or  writing,  by  being  rubbed  with  fine  sand  or  pumice-stone  as 
before.  The  longer  drawings  remain  on  stones  the  deeper  the  ink  or  the  chalk  penetrates  into  their 
substance,  and  consequently  the  more  of  the  stone  must  be  ground  away  to  remove  them;  this  is  also 
more  necessary  with  iuk  drawings  or  writings  than  with  chalk,  owing  to  the  greater  fluidity  and  conse- 
quent penetrability  of  the  former. 

The  substances  used  by  the  artist  upon  the  stone  are  either  lithographic  ink  or  lithographic  chalk. 


LITHOGRAPHY. 


233 


The  ink  for  making  transfers  should  be  somewhat  less  burned,  and  therefore  softer  than  that  used 
for  writing  or  drawing  directly  upon  the  stone. 

Lithographic  chalk  should  have  all  the  qualities  of  a good  drawing  crayon.  It  should  be  even  in 
texture,  and  carry  a good  point.  The  following  proportions  are  recommended  : 1 J oz.  of  common  soap, 
2 oz.  tallow,  2-J  oz.  virgin  wax,  1 oz.  shelldac.  The  rest  of  the  process  is  the  same  as  in  making  the  ink. 
Less  black  should  be  mixed  with  the  chalk  than  with  the  ink,  its  only  use  being  to  color  the  drawing, 
that  the  artist  may  see  the  lines  he  traces.  When  the  whole  is  well  mixed  it  should  be  poured  into  a 
mould  and  very  strongly  pressed,  to  expel  any  air  that  may  collect  in  bubbles,  which  would  render  it 
spongy. 

Mode  of  drawing. — Previous  to  drawing  or  writing,  the  stone  must  be  well  wiped  with  a clean  dry 
cloth.  The  ink  is  rubbed  with  water,  like  Indian  ink,  and  is  almost  wholly  used  on  the  polished  stone. 
The  chalk  is  used  only  upon  the  grained  stone ; the  polished  surface  of  the  other  would  not  hold  it. 
In  drawing  with  ink,  a gradation  of  tints  is  obtained  either  by  varying  the  thickness  of  the  lines,  or 
their  distances  from  one  another,  as  in  engraving.  The  ink  lines  on  polished  stones,  being  solid  and  un- 
broken throughout,  receive  the  printing  all  over ; and  if  the  lines  be  drawn  as  fine  and  as  uniform  as 
they  are  usually  on  copper,  the  print  from  them  will  be  in  no  respect  inferior ; but  it  requires  a greater 
degree  of  skill  to  execute  as  well  upon  stone  as  is  usually  done  upon  copper  or  steel. 

In  using  chalk,  the  grained  stone  should  be  very  carefully  dusted,  and  the  utmost  attention  be  paid 
to  prevent  any  lodgment  of  the  smallest  particle  of  grease  upon  the  surface ; personal  cleanliness  is 
therefore  absolutely  necessary  to  the  perfection  of  his  work,  especially  in  chalk  drawings.  The  chalk 
is  used  upon  the  stone  precisely  in  the  same  manner  as  crayon  upon  paper ; but  it  is  of  essential  ad- 
vantage in  lithography  to  finish  the  required  strength  of  tint  at  once,  instead  of  going  over  the  work  a 
second  time,  the  stone  being  impaired  in  its  ability  to  receive  the  second  lining  clearly,  by  the  absorp- 
tion of  the  first.  Some  practice  is  requisite  to  use  the  chalk  cleverly,  as  there  has  been  no  chalk  hith- 
erto made  that  will  keep  so  good  a point  as  is  desirable.  There  is  likewise  some  difficulty  experienced 
in  obtaining  the  finer  tints  sound  in  the  impression ; and  in  order  to  obtain  the  lighter  tints  properly,  it 
will  be  necessary  to  put  the  chalk  in  a rest,  as  the  metal-port  crayon  is  too  heavy  to  draw  upon  the 
stone.  A good  lithographer  is  in  the  habit,  before  he  commences  his  subject,  of  pointing  20  or  30 
pieces  of  chalk,  stuck  in  quill-holders,  and  placing  them  beside  the  stone  in  a little  box,  taking  them 
up  successively  as  the  points  become  worn  off,  so  as  to  avoid,  if  possible,  the  cutting  off  chalk  during 
the  work,  which  endangers  the  soiling  of  the  stone.  When  a very  sharp  and  delicate  line  is  required, 
he  sharpens  the  point  of  the  chalk  upon  paper,  by  pushing  it  forward  in  an  inclined  position,  and 
twirling  it  round  at  the  same  time  between  the  fore-finger  and  thumb.  As  the  chalk  softens. by  the 
warmth  of  the  hand,  it  is  quite  necessary  to  have  several  pieces,  to  be  able  to  change  them.  Some 
artists  cut  their  chalk  into  the  wedge  form,  as  being  stronger.  Those  portions  that  break  off  in  drawing 
should  be  carefully  taken  off  the  stone  by  a camel-hair  brush. 

Preparation  of  the  stone  for  printing. — The  drawing  being  finished  on  the  stone,  it  is  sent  to  the 
lithographic  printer,  on  whose  knowledge  of  his  art  depends  the  success  of  the  impressions.  The  first 
process  is  to  etch  the  drawing,  as  it  is  called.  This  is  done  by  placing  the  stone  obliquely  on  one  edge, 
over  a trough,  and  pouring  over  it  very  dilute  nitric  acid.  It  is  poured  on  the  upper  part  of  the  stone, 
and  runs  down  all  over  the  surface.  The  stone  is  then  turned  and  placed  on  the  opposite  edge,  and  the 
etching  water  being  collected  from  the  trough,  is  again  poured  over  it  in  the  same  manner.  The  degree 
of  strength,  which  is  usually  about  one  per  cent,  of  acid,  should  be  such  as  to  produce  a very  slight 
effervescence ; and  it  is  desirable  to  pass  the  etching  water  two  or  three  times  over  the  darkest  parts  of 
the  drawing,  as  they  require  more  etching  than  the  lighter  tints.  Experience  alone  can,  however,  guide 
the  lithographer  in  this  department  of  the  art,  as  different  stones  and  different  compositions  of  chalk 
will  be  differently  acted  upon  by  the  acid,  and  chalk  drawings  require  a weaker  acid  than  the  ink.  The 
stone  is  next  to  be  carefully  washed  by  pouring  clean  rain-water  over  it,  and  afterwards  with  gum- water ; 
and,  when  not  too  wet,  the  roller  charged  with  printing  ink  is  rolled  over  it  in  both  directions,  sideways, 
and  from  top  to  bottom,  till  the  drawing  takes  the  ink.  It  is  then  well  covered  over  with  a solution  of 
gum-arabic  i'n  water,  of  about  the  consistency  of  oil.  This  is  allowed  to  dry,  and  preserves  the  draw- 
ing from  any  alteration,  as  the  lines  cannot  spread,  in  consequence  of  the  pores  of  the  utcne  being  filled 
with  the  gum.  After  the  etching  it  is  desirable  to  leave  the  stone  for  a day,  and  not  more  than  a week, 
before  it  is  printed  from.  The  effect  of  the  etching  is  first  to  take  away  the  alkali  mixed  with  the  chalk 
or  ink,  which  would  make  the  drawing  liable  to  be  affected  by  the  water,  and,  secondly,  to  make  the 
stone  refuse  more  decidedly  to  take  any  grease.  The  gum  assists  in  this  latter  purpose,  and  is  quite 
essential  to  the  perfect  preparation  of  the  surface  of  the  stone. 

Printing. — When  the  intention  is  to  print  from  the  stone,  it  is  placed  upon  the  platen  or  bed  of  the 
press,  and  a proper  sized  scraper  is  adjusted  to  the  surface  of  the  stone.  Rain-water  is  then  sprinkled 
over  the  gum  on  the  stone,  which  being  dissolved  gradually,  and  a wet  sponge  passed  lightly  over  all, 
the  printer  works  the  ink,  which  is  on  the  color-table  placed  beside  him,  with  the  roller  in  all  directions, 
until  it  is  equally  and  thinly  spread  on  the  roller.  The  roller  is  then  passed  over  the  whole  stone,  care 
being  taken  that  the  whole  drawing  receives  a due  portion  of  ink ; and  this  must  be  done  by  giving  the 
roller  an  equal  motion  and  pressure,  which  will  of  course  require  to  be  increased  if  the  drawing  does 
not  receive  the  ink  readily.  When  the  drawing  is  first  used  it  will  not  receive  the  ink  so  readily  as  it 
will  afterwards ; and  it  is  frequently  necessary  to  wet  the  stone,  and  roll  it  several  times,  before  it  will 
take  the  ink  easily.  After  this  takes  place  care  must  be  taken  not  to  wet  the  stone  too  much ; the 
dampness  should  not  be  more  than  is  necessary  to  prevent  the  ink  adhering  to  the  stone  where  there  is 
no  drawing.  After  the  drawing  is  thus  rolled  on,  the  sheet  of  paper  is  placed  on  the  stone,  and  the  im- 
pression taken.  Upon  taking  the  paper  off  the  stone,  the  latter  appears  to  be  quite  dry,  owing  to  the 
paper  having  absorbed  the  moisture  on  the  surface ; it  must  therefore  be  wetted  with  a sponge,  and 
again  rolled  with  ink,  the  roller  having  been  well  worked  on  the  color-table  before  being  applied 
During  the  printing  some  gum  must  always  remain  on  the  stone,  although  it  will  not  be  visible,  other 


234 


LITHOGRAPHY. 


wise  the  ink  will  he  received  on  the  stone  as  well  as  on  the  drawing,  by  which  the  latter  would  1>« 
spoiled;  so  that  if  by  too  much  wetting,  or  by  rubbing  too  hard  with  the  sponge  the  gum  is  entirely 
removed,  some  fresh  gum-water  must  be  laid  on.  If  the  stone  has  in  the  first  instance  been  laid  by  with 
too  small  a quantity  of  gum,  and  the  ink  stains  the  stone  on  being  first  applied  to  it,  gum-water  must 
be  used  to  damp  the  stone,  instead  of  pure  water.  Sometimes,  however,  this  may  arise  from  the 
printing-ink  being  too  thin,  as  will  afterwards  appear.  If  some  spots  on  the  stone  take  the  printing-ink, 
notwithstanding  the  above  precautions,  some  strong  acid  must  be  applied  to  them  with  a brush,  and, 
after  this  is  washed  off,  a little  gum-water  is  dropped  in  the  place.  A steel  point  is  here  frequently 
necessary  to  take  off  the  spots  of  ink.  The  edges  of  the  stone  are  very  apt  to  get  soiled,  and  generally 
require  to  be  washed  with  an  old  sponge  after  rolling  in  ; they  must  also  frequently  have  an  application 
of  acid  and  gum,  and  sometimes  must  be  rubbed  with  pumice-stone.  If  an  ink  is  too  thin,  and  formed 
of  a varnish  not  sufficiently  burned,  it  will  soil  the  stone,  notwithstanding  the  proper  precautions  are 
taken  of  wetting  the  stone,  and  preparing  it  properly  with  acid  and  gum ; and  if,  on  the  other  hand,  the 
ink  is  too  thick,  it  will  tear  the  lighter  tints  of  the  chalk  from  the  stone,  and  thus  destroy  the  drawing. 
The  consideration  of  these  circumstances  leads  at  once  to  the 

Principles  of  the  printing. — The  accidents  just  mentioned  arise  at  the  extreme  points  of  the  scale  at 
which  the  printing-inks  can  be  used,  for  it  is  evident  that  the  only  inks  that  can  be  used  are  those 
-which  are  between  these  points ; that  is,  thicker  than  that  which  soils  the  stone,  and,  at  the  same  time, 
thinner  than  that  which  takes  up  the  drawing.  Lithographers  are  sometimes  unable  to  print  in  very 
hot  weather,  the  reason  of  which  may  be  deduced  from  the  foregoing.  Any  increase  of  temperature 
will  diminish  the  consistency  of  the  printing-ink;  the  stone  will  therefore  soil  with  an  ink  which  could 
be  safely  used  at  a lower  temperature — hence  a stiffer  ink  must  be  used.  Now,  if  the  temperature 
should  increase  so  much  that  the  stone  will  soil  with  any  ink  at  all  less  thick  than  that  which  will  take 
up  the  drawing,  it  is  evident  that  the  printing  must  cease  till  a cooler  temperature  can  be  obtained ; 
for  as  the  drawing-chalk  is  affected  equally  with  the  printing-ink,  the  same  ink  will  tear  up  the  drawing 
at  the  different  degrees  of  temperature.  This,  though  it  sometimes  occurs,  is  a rare  case  ; but  it  shows 
that  it  is  desirable  to  draw  with  a chalk  or  ink  of  less  fatness  in  summer  than  in  winter,  and  also  that  if 
the  printing-room  is  in  winter  artificially  heated,  pains  should  be  taken  to  regulate  the  heat  as  equally 
as  possible. 

Other  difficulties  in  printing,  not  referable  to  the  foregoing  general  principle. — If  the  pressure  of  the 
scraper  be  too  weak,  the  ink  will  not  be  given  off  to  the  paper  in  the  impression,  although  the  drawing 
has  been  properly  charged  with  it.  Defects  will  also  appear  from  the  scraper  being  notched,  or  not 
correctly  adjusted,  or  from  any  unevenness  in  the  leather  or  paper.  After  printing  a considerable  num- 
ber of  impressions,  it  sometimes  happens  that  the  drawing  takes  the  ink  in  dark  spots  in  different  parts. 
This  arises  from  the  printing-ink  becoming  too  strongly  united  with  the  chalk  or  ink  of  the  drawing, 
and  if  the  printing  be  continued,  the  drawing  will  be  spoiled.  The  reason  of  this  is  easily  ascertained. 
The  printing-ink  readily  unites  with  the  drawing,  and  being  of  a thinner  consistency,  it  will,  by  repeated 
applications,  accumulate  on  the  lines  of  the  drawing,  soften  them,  and  make  them  spread.  In  this  case 
it  is  necessary  to  stop  the  printing,  and  let  the  stone  rest  for  a day  or  two,  for  the  drawing  to  recover 
its  proper  degree  of  hardness.  If  the  drawing  should  run  smutty  from  any  of  the  causes  before  enu- 
merated, the  following 

Mixture  for  cleaning  the  drawing  while  printing  must  be  used:  Take  equal  parts  of  water,  spirits  of 
turpentine,  and  oil  of  olives,  and  shake  them  well  together  in  a glass  vial  until  the  mixture  froths ; 
wet  the  stone  and  throw  this  froth  upon  it,  and  rub  it  gently  with  a soft  sponge.  The  printing-ink  will 
be  dissolved,  and  the  whole  drawing  will  also  disappear,  though,  on  a close  examination,  it  can  be  dis- 
tinguished in  faint  white  lines.  On  rolling  it  again  with  printing-ink  the  drawing  will  gradually  re 
appear,  as  clear  as  at  first. 

Bleached  paper  unfit  for  lithographic  printing. — Accidents  sometimes  occur  in  the  printing  from  the 
qualities  of  the  paper.  If  the  paper  lias  been  made  from  rags  which  have  been  bleached  with  oxy- 
muriatic  acid,  the  drawing  will  be  incurably  spoiled  after  thirty  impressions.  Chinese  paper  has  some- 
times a strong  taste  of  alum ; this  is  so  fatal  as  sometimes  to  spoil  the  drawing  after  the  first  impression. 
When  the  stone  is  to  be  laid  by  after  printing,  in  order  that  it  may  be  used  again  at  a future  period, 
the  drawing  should  be  rolled  in  with  a 

Preserving  ink — as  the  printing-inks  would,  when  dry,  become  so  hard  that  the  drawings  would  not 
take  fresh  printing-ink  freety.  The  following  is  the  composition  of  the  printing-ink : Two  parts  of  thick 
varnish  of  linseed  oil,  four  parts  of  tallow,  one  part  of  Venetian  turpentine,  and  one  part  of  wax.  These 
must  be  melted  together,  then  four  parts  of  lamp-black,  very  carefully  and  gradually  mixed  with  it ; 
and  it  must  be  preserved  for  use  in  a close  tin  box. 

Autographic  ink,  or  that  which  is  suitable  for  transferring  on  to  the  stone  the  writings  or  drawings 
which  have  been  executed  on  paper  prepared  for  that  purpose,  should  possess  the  following  properties : 
The  ink  ought  to  be  mellow,  and  somewhat  thicker  than  that  used  immediately  on  stone ; so  that  when 
it  is  dry  on  the  paper,  it  may  still  be  sufficiently  viscous  to  cause  adherence  to  the  stone  by  simple 
pressure.  The  following  is  the  composition:  Dry  soap,  and  white  wax  free  from  tallow,  each  100 
drachms,  mutton  suet,  30  drachms,  shell-lac  and  mastic,  each  50  drachms,  lamp-black,  30  to  35  drachms  ; 
these  materials  are  to  be  melted  together. 

Autographic  paper. — The  operation  by  which  a writing  or  drawing  is  transferred  from  paper  to  stone, 
not  only  affords  the  means  of  abridging  labor,  but  also  of  producing  the  writings  or  drawings  in  the 
same  directions  in  which  they  have  been  traced ; whereas,  when  they  are  executed  immediately  on 
stone,  they  must  be  performed  in  a direction  opposite  to  that  which  they  are  eventually  to  have. 
Thus  it  is  necessary  to  draw  those  objects  on  the  left,  which,  in  the  impression,  are  to  be  on  the  right 
hand.  To  acquire  the  art  of  reversing  subjects  when  writing  or  drawing,  is  both  difficult  and  tedious: 
while,  by  the  aid  of  transparent,  and  of  autographic  paper,  impressions  may  be  readily  obtained  in  the 
same  direction  as  that  in  which  the  writing  or  the  drawing  has  been  made.  In  order  to  make  a transfer 


LITHOGRAPHY. 


on  to  stone  of  a writing,  or  drawing  in  lithographic  ink,  or  in  crayons,  or  an  impression  from  a copper 
plate,  it  is  necessary,  1st,  that  the  drawing  or  transcript  should  be  on  a thin  and  flexible  substance,  such 
as  common  paper ; 2d,  that  it  should  be  capable  of  being  easily  detached  from  this  substance,  and 
transferred  entirely  on  to  the  stone,  by  means  of  pressure.  But  as  the  ink  with  which  a drawing  is 
traced  penetrates  the  paper  to  a certain  depth,  and  adheres  to  it  with  considerable  tenacity,  it  would  be 
difficult  to  detach  them  perfectly  from  each  other,  if,  between  the  paper  and  the  drawing,  some  sub- 
stance was  not  interposed,  which,  by  the  portion  of  water  which  it  is  capable  of  imbibing,  should  so  fai 
lessen  their  adhesion  to  each  other,  that  they  may  be  completely  separated  in  every  point.  It  is  to 
effect  this  that  the  paper  is  prepared,  by  covering  it  with  a size,  which  may  be  written  on  with  facility, 
and  on  which  the  finest  lines  may  be  traced  without  blotting  the  paper.  Various  means  may  be  found 
of  communicating  this  property  to  paper.  The  following  preparation  has  always  been  found  to  succeed, 
and  which,  when  the  operation  is  performed  with  the  necessary  precautions,  admits  of  the  finest  and 
most  delicate  lines  being  perfectly  transferred,  without  leaving  the  faintest  trace  on  the  paper.  For 
this  purpose,  it  is  necessary  to  take  a strong,  unsized  paper,  and  to  spread  over  it  a size  prepared  of 
.the  following  materials  : starch,  120,  gum-arabic,  40,  and  alum,  21  drachms.  A moderately  thick  paste 
is  made  with  the  starch,  by  means  of  heat ; into  this  paste  is  thrown  the  gum-arabic  and  the  alum, 
which  have  been  previously  dissolved  in  water,  and  in  separate  vessels.  The  whole  is  mixed  well  to- 
gether, and  it  is  applied  warm  to  the  sheets  of  paper,  by  means  of  a brush,  or  a large  flat  hair-pencil. 
The  paper  may  be  colored  by  adding  to  the  size  a decoction  of  French  berries,  in  the  proportion  of  ten 
drachms.  After  having  dried  this  autographic  paper,  it  is  put  into  a press,  to  flatten  the  sheets,  and 
they  are  made  smooth  by  placing  them,  two  at  a time,  on  a stone,  and  passing  them  under  the  scraper 
of  the  lithographic  press.  If,  on  trying  this  paper,  it  is  found  to  have  a tendency  to  blot,  this  inconve- 
nience may  be  remedied  by  rubbing  it  with  finely  powdered  sandarac.  Annexed  is  another  recipe, 
which  will  be  found  equally  useful,  and  which  has  the  advantage  of  being  applicable  to  thin  paper, 
which  has  been  sized.  It  requires  only  that  the  paper  be  of  a firm  texture : namely,  gum-tragacanth, 
4 drachms  ; glue,  4 ; Spanish- white,  8 ; and  starch,  4 drachms. 

The  tragacanth  is  put  into  a large  quantity  of  water  to  dissolve,  thirty-six  hours  before  it  is  mixed 
with  the  other  materials  ; the  glue  is  to  be  melted  over  the  fire  in  the  usual  manner.  A paste  is  made 
with  the  starch;  and  after  having,  whilst  warm,  mixed  these  several  ingredients,  the  Spanish-white  is 
to  be  added  to  them,  and  a layer  of  the  sizing  is  to  be  spread  over  the  paper,  as  already  described,  tak- 
ing care  to  agitate  the  mixture  with  the  brush  to  the  bottom  of  the  vessel,  that  the  Spanish-white  may 
be  equally  distributed  throughout  the  liquid.  We  will  hereafter  point  out  the  manner  in  which  it  is 
necessary  to  proceed,  in  order  to  transfer  writings  and  drawings.  There  are  two  autographic  processes 
which  facilitate  and  abridge  this  kind  of  work  when  it  is  desired  to  copy  a fac-simile,  or  a drawing  in 
lines.  The  first  of  these  methods  is  to  trace,  with  autographic  ink,  any  subject  whatever,  on  a trans- 
parent paper,  which  is  free  from  grease  and  from  resin,  like  that  which,  in  commerce,  is  known  by  the 
name  of  papier  vegetal,  and  to  transfer  it  to  stone  ; this  paper  to  be  covered  with  a transparent  size  : 
this  operation  is  difficult  to  execute,  and  requires  much  address,  in  consequence  of  the  great  tendency 
which  this  paper  has  to  cockle  or  wrinkle  when  it  is  wetted.  Great  facilities  will  be  found  from  using 
tissue  paper,  impregnated  with  a fine  white  varnish,  and  afterwards  sized  over.  In  the  second  process, 
transparent  leaves,  formed  of  gelatin,  or  fish  glue,  are  employed,  and  the  design  is  traced  on  them  with 
the  dry  point,  so  as  to  make  an  incision ; these  traces  are  to  be  filled  up  with  autographic  ink,  and  then 
transferred.  We  will  describe,  in  their  jrroper  places,  these  processes,  as  well  as  that  of  transferring  a 
lithographic  or  a copper-plate  engraving. 

Autographic  processes. — To  transfer  a drawing  or  writing  to  stone,  it  is  made  with  ink  on  paper,  both 
prepared  in  the  way  we  have  described.  A crayon  drawing  may,  on  an  emergency,  be  executed  auto- 
graphieally ; but  this  mode  of  procedure  is  too  imperfect  to  admit  of  procuring,  by  its  means,  neat  and 
perfect  proofs  ; besides,  it  is  as  expeditious  to  draw  immediately  on  the  stone. 

In  order  to  write,  or  to  draw  on  autographic  paper,  a little  of  the  ink  of  which  we  have  given  the 
composition  is  diluted  with  water,  taking  care  to  use  only  rain-water,  or  such  as  will  readily  dissolve 
soap.  The  solution  is  facilitated  by  slightly  warming  the  water  in  the  cup  ; and  the  ink  is  dissolved  by 
rubbing  the  end  of  a stick  of  it  in  the  manner  practised  with  Indian  ink.  There  should  be  no  more  dis- 
solved at  a time  than  will  be  used  in  a day,  for  it  does  not  redissolve  so  well,  neither  is  the  ink  so 
good,  particularly  for  delicate  designs,  after  it  has  been  left  to  dry  for  several  days.  This  ink  should 
have  the  consistence  of  rather  thick  cream,  so  that  it  may  form  very  black  lines  upon  the  paper : if  these 
lines  are  brown,  good  impressions  will  not  be  obtained.  A sheet  of  white  paper  is  placed  under  the 
hand  while  writing,  in  order  that  it  may  not  grease  the  autographic  paper. 

The  stone  used  for  autography  should  be  polished  with  pumice-stone,  and  the  impressions  will  be 
neat  in  proportion  as  the  stone  is  well  polished.  Autographic  work  may  be  executed  either  cold  or 
warm ; that  is,  taking  the  stone  at  its  ordinary  temperature,  or  making  it  warm  by  placing  it  near  to 
the  fire,  or  exposing  it  to  the  heat  of  the  sun  : if  the  first  means  of  warming  be  used,  care  must  be  taken 
that  the  fire  be  not  too  hot,  or  it  will  crack  the  stone ; the  temperature  given  to  it  should  be  about  that 
of  an  earthen  vessel  filled  with  lukewarm  water.  The  work  may  be  done,  though  less  perfectly,  with- 
out warming  the  stone.  AVhen  the  stone  is  thus  prepared,  it  is  fixed  in  the  press,  and  the  paper  on  which 
the  writing  is  made  is  applied  to  it.  The  stone  may  be  rubbed  with  a linen  cloth,  slightly  moistened 
with  spirits  of  turpentine  ; and  in  every  case  it  is  necessary  that  it  be  made  perfectly  clean.  The  tur- 
pentine is  left  to  evaporate ; and  from  five  to  eight  minutes  before  the  paper  is  applied,  it  is  wetted 
with  a sponge  and  water  on  the  reverse  side  to  that  on  which  the  writing  is  done,  so  that  the  moisture 
may  penetrate  throughout  every  part.  The  water,  however,  must  not  appear  on  the  paper  when  it  is 
about  to  be  laid  on  the  stone ; but  any  superabundance  which  may  remain  on  it  must  be  removed  by  a 
pressed  sponge.  When  the  paper  is  brought  to  the  proper  state,  it  is  taken  by  both  hands  at  one  of  its 
extremities,  and  placed  lightly  and  gradually  upon  the  stone,  so  that  there  may  be  no  plaits  formed  in 
it,  and  that  it  may  be  equally  applied  over  its  whole  surface.  Care  must  be  taken  so  to  fix  the  scraper 


* 


236 


LITHOGRAPHY. 


Hut  it  may  bear  steadily  on  the  autographic  paper ; for  if  it  removes  it  at  all  it  will  change  the  place 
of  pressure,  and  the  lines  will  be  doubled.  There  should  be  at  hand  five  or  six  sheets  of  very  even 
mackle  paper,  so  that  they  may  be  changed  with  each  impression.  The  paper  on  which  the  writing  oi 
drawing  is  made  being  placed  on  the  stone,  it  is  covered  with  a sheet  of  mackle  paper,  and  subjected 
to  a slight  action  of  the  press ; then  to  a second,  a third,  or  even  to  more,  until  it  is  believed  that  the 
writing  is  perfectly  transferred.  At  each  stroke  of  the  press  the  mackle  paper,  which  has  imbibed 
moisture,  is  withdrawn,  and  a dry  sheet  substituted  in  its  place.  All  these  operations  require  to  be 
performed  with  expedition  and  dexterity,  particularly  when  the  stone  is  warm.  The  next  thing  is  to 
detach  the  autographic  paper,  which  will  be  found  adhering  closely  to  the  stone.  To  effect  this,  it  is 
well  wetted  with  a sponge,  so  that  every  part  of  it  may  be  perfectly  penetrated  by  the  water;  it  may 
then  be  removed  with  facility,  entirely  detached  from  the  writing,  which  will  remain  adhering  strongly 
to  the  stone.  If  this  operation,  which  requires  much  practice,  be  well  performed,  there  will  not  be  found 
the  slightest  trace  of  ink  remaining  on  the  paper.  Should  there  be  any  lines  not  well  marked  on  the 
stone,  they  may  be  retouched  with  a pen ; or,  which  is  better,  with  a hair-pencil  and  ink ; but  when 
this  is  done,  care  must  be  taken  that  the  stone  is  quite  dry.  A part  of  the  sizing  of  the  paper  may  be 
found  dissolved  and  adhering  to  the  stone  ; this  may  be  removed  by  washing  or  slightly  rubbing  it  with 
a wet  sponge.  The  stone  is  then  prepared  with  aquafortis,  and  the  impression  taken. 

Autography  is  not  confined  to  the  transferring  of  writings  or  drawings  done  with  autographic  ink  ; by 
its  means  a transfer  may  be  obtained  from  a sheet  of  ordinary  printed  paper,  and  with  such  exactness, 
that  it  would  be  impossible,  excepting  to  well-practised  eyes,  to  perceive  the  least  difference  between 
that  printed  in  the  usual  way,  and  that  which  was  the  result  of  the  autographic  process.  This  mode  is 
very  useful  when  it  is  desired  to  unite  Oriental  characters,  which  might  not  be  possessed  with  words, 
phrases,  or  lines  composed  in  ordinary  typography.  In  this  way  have  been  executed,  in  the  office  of 
the  Count  M.  C.  de  Lasteyrie,  at  Paris,  (from  whose  papers  on  this  subject,  contained  in  the  Journal  des 
Connaissances  Usuelles,  and  translated  by  the  learned  editor  of  the  Franklin  Journal , our  account  of 
this  art  is  largely  indebted,)  many  pieces,  in  which  the  French  or  the  Latin  language  was  intermixed 
with  words  or  phrases  in  Chinese  or  Arabic.  In  the  same  way  have  also  been  executed  typographic 
maps,  in  which  all  the  details  were  lithographic,  while  the  names  of  places  were  at  first  pruduced  by 
typography,  and  afterwards  by  autography.  This  operation  is  begun  by  composing  and  arranging,  in- 
a typographic  form,  the  words,  the  phrases,  or  the  lines,  as  they  ought  to  stand.  The  autographic  paper 
is  printed  on  by  this  form,  and  the  words  in  the  Oriental  languages  are  afterwards  written  in  the  spaces 
which  have  been  left  for  them ; the  whole  is  transferred  to  a stone,  which  is  prepared  for  the  purpose, 
and  from  which  the  impression  is  taken  in  the  usual  manner.  The  same  mode  is  pursued  in  making 
geographical  maps.  After  having  printed  the  names  on  autographic  paper,  the  other  parts  of  the  map, 
but  without  the  names,  are  drawn  immediately  on  the  stone  ; and  after  having  printed  the  names  on 
white  paper,  the  map  drawn  upon  the  stone  is  printed  on  this  same  paper. 

Maps,  or  line  engravings  on  copper,  where  the  work  is  not  very  close,  may  be  multiplied  in  a similar 
way.  For  this  purpose  the  plate  of  copper  is  covered  over  with  the  autographic  ink,  diluted  to  a con- 
venient consistence.  Instead  of  the  autographic  ink,  a composition  is  sometimes  used,  made  of  one 
ounce  of  wax,  one  ounce  of  suet,  and  three  ounces  of  the  ink  with  which  the  ordinary  impressions  in 
lithography  are  taken.  The  whole  is  warmed  and  mixed  well  together,  and  there  is  a little  olive-oil 
added  to  the  composition,  if  it  is  not  liquid  enough  to  spread  itself  over  the  plate  ; the  plate  ought  to 
be  warmed  as  usual.  After  having  taken  the  impression  in  the  rolling-press  on  a sheet  of  autographic 
paper,  the  transfer  may  be  immediately  made  on  to  the  stone,  after  having  rubbed  it  with  a sponge, 
dipped  in  turpentine.  It  is  necessary  to  give  three,  four,  or  even  more  strokes  of  the  press,  increasing 
the  pressure  at  every  successive  stroke ; the  other  processes,  which  we  have  already  described,  are  like- 
wise to  be  followed.  It  is  well  to  wait  twenty-four  hours  before  preparing  the  stone,  in  order  that  it 
may  be  better  penetrated  by  the  transferring  ink ; it  is  then  gummed  and  washed,  and  is  ready  for  use. 
This  process,  which  has  not  yet  come  much  into  use  amongst  lithographers,  merits  the  attention  of  art- 
ists; for  it  affords  the  means  of  reproducing  and  multiplying  geographical  charts,  and  some  kinds  of 
engravings  indefinitely,  so  that  they  might  be  furnished  at  a quarter  of  their  present  actual  value  ; in 
fact,  all  those  which  are  done  in  lines,  or  those  in  wThich  the  shadows  are  boldly  executed,  are  capable 
of  reproducing  good  impressions  by  means  of  autography.  The  operation  becomes  extremely  difficult 
when  it  is  necessary  to  transfer  fine  line  engravings ; the  lines  of  these  are  so  delicate,  and  so  near  to 
each  other,  that  they  either  do  not  take  well  on  the  stone,  or  are  apt  to  be  crushed  and  confounded 
together  by  the  effect  of  the  pressure.  Much  practice  and  address  are  necessary  to  obtain  tolerable 
impressions;  and  this  part  of  the  art  requires  improvement.  In  the  office  of  M.  de  Lasteyrie,  they  had 
succeeded  in  transferring  to  stone  a small  highly  finished  engraving,  which  had  been  printed  on  common 
half-sized  paper.  After  having  dry-polished  a stone  very  perfectly,  it  was  warmed,  rubbed  with  spirits 
of  turpentine,  and  then  the  engraving  was  applied  to  it.  This  had,  however,  been  previously  dipped 
into  water,  then  covered  on  the  reverse  side  with  turpentine,  passed  again  through  the  water,  so  as  to 
remove  the  superfluous  turpentine,  and  then  wiped  with  unsized  paper.  In  this  state  the  engraving, 
still  damp  with  the  turpentine,  was  applied  to  the  stone  and  submitted  to  pressure,  when  it  afforded 
very  good  impressions ; the  preparation  not  being  applied  until  it  had  remained  on  the  stone  for  twenty- 
four  hours.  The  difficulties  increase,  of  course,  in  proportion  to  the  size  of  the  engravings  which  it  is 
desired  to  transfer  to  the  stone.  Attempts  have  been  made  to  transfer  old  engravings  ; they  have, 
however,  succeeded  but  imperfectly.  It  would  be  rendering  an  essential  service  to  the  att  to  discover 
a mode  of  reproducing  old  engravings  by  means  of  autography  ; the  undertaking  presents  difficulties, 
but  from  the  attempts  made,  success  does  not  seem  improbable. 

Printing  from  two  or  more  stones  with  different  colored  inks. — This  is  managed  by  preparing  a com- 
position of  two  parts  of  wax,  one  of  soap,  and  a little  vermilion.  Melt  them  in  a saucepan,  and  cast 
them  into  sticks ; this  must  be  rubbed  up  with  a little  water  to  the  thickness  of  cream,  and  applied  to 
the  surface  of  a polished  stone.  An  impression  is  taken  in  the  common  wav  from  a drawing,  and  ap- 


LOCKS. 


237 


plied  to  a stone  prepared  in  this  manner,  and  passed  through  the  press,  taking  care  to  mark,  by  means 
of  this  impression,  two  points  in  the  margin  corresponding  on  each  of  the  stones.  The  artist,  haying 
thus  on  the  second  stone  an  impression  from  the  first  drawing  to  guide  him,  scrapes  away  the  parts 
which  he  wishes  to  remain  white  on  the  finished  impression.  The  stone  must  now  be  etched  with  acid 
stronger  than  the  common  etching  water,  having  one  part  of  acid  and  twenty  of  water ; the  whole  is 
then  washed  off  with  turpentine  : this  plan  is  generally  used  in  printing  a middle  tint  from  the  second 
stone  ; the  black  impression  being  given  from  the  first  stone,  a flat  transparent  brownish  tint  is  given 
from  the  second,  and  the  white  lights  are  where  the  paper  is  left  untouched.  The  dots  are  necessary 
to  regulate  the  placing  of  the  paper  on  the  corresponding  parts  of  the  two  stones. 

LOCKS.  From  the  Proceedings  of  the  Institution  of  Mechanical  Engineers.  It  was  conceded  about 
twelve  years  since  in  the  United  States,  by  all  locksmiths,  that  a lock  having  a series  of  tumblers  or 
slides,  such  as  was  used  at  that  time  in  Europe,  and  more  particularly  those  of  Barron  and  Chubb,  was 
secure  against  all  known  means  of  picking,  or  of  forming  a false  key  by  any  knowledge  that  could  1)8 
obtained  through  the  key-hole.  The  only  point  that  seemed  desirable  was  to  make  it  secure  against  the 
maker,  or  any  party  who  might  have  had  possession  of  the  key,  and  from  it  taken  an  impression. 

The  first  step,  therefore,  was  to  construct  the  lock  so  that  the  party  using  it  could  change  its  form  at 
pleasure.  Mr.  Andrews  constructed  a lock  similar  to  that  made  by  Mr.  Chubb,  having  a series  of  tum- 
blers and  a detector ; but  before  placing  the  lock  on  the  door,  the  purchaser  could  arrange  the  tumblers 
in  any  way,  so  that  the  combination  suited  his  convenience ; the  key  being  made  with  a series  of  mov- 
able bits,  was  arranged  in  a corresponding  combination  with  the  tumblers.  In  order  to  make  a change 
in  the  lock  without  taking  it  from  the  door,  each  tumbler  was  so  constructed  that  in  locking  the  lock  the 
tumbler  could  be  raised,  or  drawn  out  with  the  bolt.  A series  of  rings  was  furnished  with  the  key,  cor- 
responding with  the  thickness  of  the  movable  bits  of  the  key ; and  any  one,  or  as  many  more  of  the  bits 
could  be  removed  from  the  key,  and  rings  substituted.  These  bits  being  removed,  and  the  rings  taking 
their  place,  the  corresponding  tumblers  would  not  be  raised  by  the  turning  of  the  key,  and  consequently 
would  be  drawn  out  with  the  bolt,  (becoming,  in  fact,  a portion  of  the  bolt  itself.')  Therefore,  when  a bit 
was  removed  and  a ring  substituted,  so  much  of  the  security  of  the  lock  was  lost  as  depended  on  the 
tumbler  that  was  not  raised ; consequently,  a lock  having  twelve  tumblers,  being  locked  with  a key  with 
alternate  bits  and  rings,  would  evidently  become  a six-tumbler  lock  ; but  should  a tumbler  that  was 
drawn  out  with  the  bolt  be  raised  in  the  attempt  to  pick  or  unlock  it,  or  should  any  one  of  the  acting 
tumblers  be  raised  too  high,  the  detector  would  be  thrown,  and  prevent  the  withdrawing  or  unlocking  of 
the  bolt.  This  lock  was  in  great  repute  in  the  LTnited  States,  and  was  placed  on  the  doors  of  nearly  all 
the  principal  banking  establishments  of  the  country;  a large  reward  was  offered  by  its  maker  to  any 
one  who  could  pick  it ; and  from  its  great  repute  it  consequently  called  out  many  rivals. 

Mr.  Newell  constructed  what  he  termed  his  Permutating  Lock,  which  was  composed  of  a series  of 
first  and  secondary  tumblers,  the  secondary  series  being  operated  upon  by  the  first  series.  Through  the 
secondary  series  there  was  passed  a screw  termed  a clamp-screw,  having  a clamp  overlapping  the  tum- 
blers on  the  inside  of  the  lock ; each  tumbler  in  the  series  having  an  elongated  slot  to  allow  the  screw 
to  pass  through.  On  the  back  side  of  the  lock  was  a small  round  key-hole,  in  which  the  head  of  the 
screw  rested,  forming,  as  it  were,  a receptacle  for  a small  secondary  key  ; so  that  when  the  large  key 
gave  the  necessary  form  to  the  tumblers,  the  party  took  the  small  key  and  operated  on  the  clamp 
screw,  clamping  and  holding  together  the  secondary  series,  retaining  them  in  the  relative  heights  or  dis- 
tances imparted  to  them  by  the  large  key  ; the  door  was  then  closed,  and  the  bolt  projected,  and  the  first 
series  of  tumblers  fell  again  to  their  original  position.  The  objection  to  this  mode  of  constructing  a 
lock  was,  that  it  required  the  insertion  of  the  small  secondary  key ; and  should  the  party  neglect  to  re- 
lease the  clamp-screw  every  time  he  unlocked  the  lock,  the  first  series  of  tumblers  would  be  held  up 
by  the  secondary  series.  Consequently,  an  exact  impression  of  the  lengths  of  the  several  bits  of  the 
key  could  be  obtained  through  the  key-hole  while  the  lock  was  unlocked.  This  lock  and  Mr.  Andrews’ 
were  both  picked  by  Mr.  Newell,  who  demonstrated  that  this  lock  as  well  as  all  others  based  on  the 
tumbler  principle  was  insecure. 

The  first  step  taken  to  make  a secure  lock,  was  to  add  a series  of  complicated  wards  to  the  locks  ; 
but  it  will  be  readily  seen,  that  what  can  be  reached  with  a key,  could  be  reached  by  some  other  instru- 
ment ; and,  although  it  required  an  instrument  of  a different  form,  yet  the  operation  was  just  as  certain 
and  fatal  to  the  security  of  the  lock. 

The  next  step  taken,  and  one  which  was  considered  effectual,  for  a time,  was  the  notching  of  the 
abutting  parts  of  the  first  and  secondary  series  of  tumblers,  or  of  the  stump  face  and  the  ends  of  the 
tumblers.  So  that  if  a pressure  was  put  upon  the  bolt,  the  tumblers  could  not  be  successively  raised 
by  the  picking  instrument,  being  held  fast  by  these  “false  notches.”  This  lock  baffled  the  skill  of  all 
the  country  for  a time,  and  was  considered  perfectly  safe,  until  an  ingenious  engineer  of  the  name  of 
Pettis  picked  this  lock. 

The  Parautoptic  Lock  was  then  invented  by  Mr.  Newell,  retaining  all  that  was  deemed  good  in  the 
locks  previously  made,  and,  at  the  same  time,  guarding  against  all  the  defects  proved  by  actual  experi- 
ment. 

The  annexed  figure  shows  it  locked,  with  the  cover  and  the  detector-plate  removed,  and  the  auxiliary 
tumbler  in  its  place ; A A is  the  bolt ; B B are  the  first  series  of  movable  slides  or  tumblers ; C,  the 
tumbler  springs ; D D the  secondary  series  of  tumblers ; and  E E the  third  or  intermediate  series,  which 
form  the  connections  between  the  first  and  secondary  series  of  tumblers ; F F are  the  separating  plates 
between  the  first  series  of  tumblers;  G,  the  springs,  for  lifting  the  intermediate  slides  or  tumblers  to 
make  them  follow  the  first  series  when  they  are  lifted  by  the  key.  On  each  of  the  secondary  tumblers 
D D,  is  a series  of  notches,  corresponding  in  distance  with  the  difference  in  the  lengths  of  the  movable 
bits  of  the  key ; and  as  the- key  is  turned  in  the  lock  to  lock  it,  each  bit  raises  its  tumbler,  so  that  some 
one  of  these  notches  presents  itself  in  front  of  the  tooth  h,  on  the  dog  or  lever  H H.  As  the  bolt  A is 
projected,  it  carries  with  it  the  secondary  tumblers  D D,  and  presses  the  tooth  h into  the  notches  in  th« 


238 


LOCKS. 


tumblers,  withdrawing  the  tongues  d,  from  between  the  jaws  e e,  of  the  intermediate  tumblers  E E,  and 
allowing  the  first  and  intermediate  tumblers  to  fall  to  their  original  position ; whilst  the  secondary  tum- 
blers D D,  are  held  in  the  position  given  to  them  by  the  key,  by  means  of  the  tooth  k being  pressed 
into  the  several  notches,  as  shown.  Should  an  attempt  he  made  to  unlock  the  bolt  with  any  but  the  true 
key,  the  tongues  d will  abut  against  the  jaws  e e,  preventing  the  bolt  from  being  withdrawn;  and  should 
an  attempt  be  made  to  ascertain  which  tumbler  binds  and  requires  to  be  moved,  the  secondaiy  tumbler 
D T),  that  takes  the  pressure,  being  behind  the  iron  wall  I K,  which  is  fixed  completely  across  the  lock, 
prevents  the  possibility  of  its  being  reached  through  the  key-hole,  and  the  first  tumblers  B B are  quite 
detached  at  the  time,  thereby  making  it  impossible  to  ascertain  the  position  of  the  parts  in  the  inner 
chamber  behind  the  wall  IK.  The  portion  II  of  this  wall  is  fixed  to  the  back  plate  of  the  lock,  and 
the  portion  K K to  the  cover. 


L is  the  drill  pin  on  which  the  keys  fits;  and  MM. is  a revolving  ring  or  curtain,  which  turns  round 
with  the  key,  and  prevents  the  possibility  of  inspecting  the  interior  of  the  lock  through  the  key-hole ; 
and  should  this  ring  be  turned  to  bring  the  opening  upward,  the  detector  plate  is  immediately  carried 
over  the  key-hole  S,  by  the  motion  of  the  pin  P upon  the  auxiliary  tumbler  0 0,  which  is  lifted  by  the 
revolution  of  the  ring  M,  thereby  effectually  closing  the  opening  of  the  key-hole.  As  an  additional 
protection,  the  bolt  is  held  from  being  unlocked  by  the  stud  R bearing  against  the  plate  Q ; also  the 
lever  T T holds  the  bolt  when  locked  until  it  is  released  by  the  tail  of  the  detector-plate  Q pressing  the 
pin  U.  Y is  a dog,  holding  the  bolt  on  the  upper  side  when  locked,  until  it  is  lifted  by  the  tumblers  act- 
ing on  the  pin  W.  X X are  the  separating  plates  between  the  intermediate  tumblers  E E ; Y and  Z are 
the  studs  for  preserving  the  parallel  motion  of  the  different  tumblers. 

There  are  several  features  in  the  construction  of  this  lock  which  are  deserving  of  particular  attention. 
The  most  novel  and  extraordinary  is,  that  the  lock  changes  itself  to  the  key ; in  whatever  form  the 
movable  bits  on  the  key  are  changed,  the  lock  answers  to  that  form,  without  moving  any  part  of  it  from 
the  door. 

The  party  purchasing  the  lock  can  change  it  to  suit  his  convenience.  If  a 6-tumbler  lock,  to  720  ; 
if  7 tumblers,  5,040;  if  8,  40,320;  if  9,  362;880;  if  10,  3,628,800;  and  if  12,  479,001,600.  There- 
fore it  will  be  perceived  that,  by  changing  the  numerical  position  of  the  bits  in  the  key,  the  lock  can  be 
altered,  or  in  fact  alters  itself  to  any  number  of  new  locks,  equal  to  the  permutation  of  the  number  of 
bits  on  the  key.  Two  extra  bits  are  supplied  with  each  key,  which  add  very  greatly  to  the  number  of 
changes.  As  the  key  turns  round,  each  bit  raises  its  tumbler  to  a point  corresponding  with  its  length, 
imparting  to  the  first  and  secondary  series  the  exact  form  of  the  key.  The  secondary  series  of  tumblers 
being  carried  out  with  the  bolt,  and  the  tooth  on  the  lever  or  dog  being  pressed  into  the  several  notches 
on  the  front  face  of  the  secondary  series,  holds  them  in  the  position  given  them  -by  the  key,  while  all 
the  other  portions  of  the  lock  fall  again  to  their  original  position. 

Should  a pressure  be  put  on  the  bolt  to  ascertain  the  obstruction,  it  will  be  readily  seen  that  it  will  be 
brought  to  hear  on  the  third  or  intermediate  tumblers.  To  prevent  the  possibility  of  reaching  these, 
there  is  a wall  of  metal  fixed  across  the  lock,  which  confines  the  operator  wholly  to  the  key-chamber. 
By  detaching  the  portion  of  the  tumbler  that  takes  the  pressure  given  to  the  bolt,  from  the  parts  that 
can  be  reached  through  the  key-hole,  leaving  that  portion  always  at  liberty,  the  possibility  of  ascertain- 
ing what  is  wrong  is  rat  off;  so  that  instead,  as  in  the  former  lock,  having  only  a first  and  secondary 


LOCKS  OF  CANALS. 


239 


series,  Mr.  Newell  here  introduced  a third  or  intermediate  series ; thereby  throwing  the  whole  security 
of  the  lock  into  a chamber  beyond  the  wall  of  metal,  which  is  wholly  inaccessible,  and  forming  as  it 
were  another  lock  without  a key-hole.  These  are  the  principal  features  of  security  in  Mr.  Newell’s  Pa- 
rautoptic  Lock. 

There  is  another  source  of  insecurity  that  has  still  to  be  provided  against ; when  the  first  tumblers 
can  bo  seen  through  the  key-hole,  if  the  under  side  of  them  is  smoked  by  inserting  any  flame,  the  key 
will  leave  a distinct  mark  upon  each  tumbler  the  next  time  it  is  used,  showing  where  it  began  to  touch 
each  tumbler  in  lifting  it.  This  can  be  seen  by  inserting  a small  hinged  mirror  into  the  lock  through  the 
key-hole,  and  the  exact  length  of  each  bit  of  the  key  measured,  from  the  centre-pin  to  the  point  where 
it  touched  the  particular  tumbler,  from  which  a correct  copy  of  the  key  can  be  made.  (An  electric  light 
from  a small  portable  battery,  has  been  employed  for  this  purpose,  to  illumine  the  interior  of  the  lock.) 

The  possibility  of  seeing  the  tumblers  is  entirely  prevented,  by  surrounding  the  inside  of  the  key-hole 
with  a ring  or  revolving  curtain  ; and  when  this  curtain  is  turned,  to  bring  the  opening  opposite  the  tum- 
blers, the  key-hole  is  shut  on  the  outside  by  the  detector  tumbler,  which  tumbler  would  also  detect  all 
attempts  at  mutilating  the  interior  parts  of  the  lock. 

Should  the  lock  be  charged  with  gunpowder  through  the  key-hole,  for  the  purpose  of  blowing  it  from 
the  door,  the  plug  in  the  back  of  the  key-chamber  yields  to  the  force,  leaving  the  lock  uninjured,  whilst 
the  curtain  protects  the  interior  of  the  lock  from  injury,  thereby  effectually  preventing  all  known  means 
of  opening  or  forcing  the  lock. 

LOCKS  OF  CANALS.  A contrivance  by  which  boats  may  pass  from  a lower  to  a higher  level,  or 
the  reverse,  by  the  buoyancy  of  the  water. 

The  least  length  that  can  he  allowed  between  the  locks  should  be  such  that  12  inches  of  depth,  over  and 
above  what  a loaded  boat  will  draw,  will  only  lower  the  water  6 inches  without  the  navigation  being 
interrupted ; and  if  it  be  required  to  draw  the  contents  of  each  lock  from  the  interval  above,  the  dis- 
tance for  the  locks  must  be  so  regulated  that  the  quantity  of  water  expended  by  one  should  not  lower 
that  of  the  upper  interval  more  than  6 inches  at  most : thus  the  distance  should  be  greater  in  propor- 
tion to  the  contents  of  the  chamber  of  the  locks  and  the  width  of  the  canal ; that  is  to  say,  when  the 
chambers  are  large  and  the  canal  is  narrow,  the  distance  between  the  locks  should  be  greater.  Cham- 
bers 110  feet  in  length  between  the  gates,  by  17  feet  in  width,  contain  1870  superficial  feet;  therefore 
11.843  cubic  feet  when  the  fall  is  6 feet  4 inches,  15,859  cubic  feet  when  it  is  8 feet  6 inches,  and  19,635 
cubic  feet  when  10  feet  6 inches.  If  the  canal  be  48  feet  in  width,  at  3 feet  below  the  ordinary  level  of 
the  water,  the  length  of  the  interval  should  be  446  feet,  in  order  that  the  expenditure  of  locks  of  6 feet 
4 inches  of  fall  should  not  lower  the  water  more  than  6 inches  ; this  length  should  be  607  feet  when  the 
locks  are  8 feet  6 inches  of  fall,  and  755  feet  when  they  are  10  feet  6 inches  : the  distance  then  between 
the  lower  gate  of  one  lock,  and  the  upper  gate  of  the  other,  should  be  always  about  624  feet  for  ordi- 
nary canals.  If  two  locks  of  8 feet  6 inches  fall  were  only  distant  160  feet,  the  water  drawn  from  the 
interval,  for  the  purpose  of  mounting  the  boat,  would  lower  it  nearly  26  inches,  and  there  would  not 
remain  sufficient  to  keep  it  afloat;  consequently,  it  would  be  necessary  to  draw  a lockful  from  the 
upper  interval,  and  then  a second,  to  cause  it  to  rise,  whilst  only  one  would  be  required  if  the  locks  were 
at  a sufficient  distance. 

This  example  will  show  the  inconvenience  of  having  locks  too  near  each  other,  which  is  still  further 
increased  when  they  are  contiguous.  It  frequently  happens  that  several  boats  arrive  together  in  the 
same  interval,  particularly  where  the  bargemen  stop  or  sleep,  and  that  ho  water  may  be  lost,  the  inter- 
val where  they  stop  should  be  sufficiently  long  to  admit  more  than  one.  If  circumstances  will  not  per- 
mit this,  a greater  width  must  be  given,  that  the  lockful  which  the  rising  boats  draw  from  the  interval 
should  not  cause  the  water  to  lower  so  considerably  as  to  prevent  their  floating,  or  the  descending  boats 
force  in  such  a quantity  as  to  make  it  run  over  the  gates.  If  the  interval  has  only  the  ordinary  width 
of  48  feet,  it  should  be  6398  feet  in  length,  so  that  ten  rising  boats  could  stop,  if  none  were  descending 
at  the  same  time,  otherwise  a part  of  the  water  must  be  drawn  from  the  other  intervals  to  keep  them 
afloat : if  there  were  as  many  ascending  as  descending  boats,  this  need  not  be  so  great,  but  this  ob- 
servation proves  that  in  forming  a canal  it  is  necessary  to  have  basins  at  those  situations  where  boats 
are  required  to  stop  any  length  of  time. 

Quantity  of  water  expended  by  boats  in  traversing  a canal. — It  was  the  opinion  of  MM.  Gabriel  and 
Abeille,  that  the  passage  of  a boat  through  the  whole  length  of  a canal  always  cost  twice  the  quantity 
of  water  necessary  to  fill  a lock.  Belidor  thought  the  same,  and  it  is  still  the  common  opinion.  M. 
Thommason  has  nevertheless  maintained  that  this  idea  is  erroneous,  and  that  when  one  boat  passes 
several  locks  one  after  another,  the  second  boat  only  expends  two  locksful  in  its  whole  passage ; but 
when  they  pass  alternately,  one  up  and  the  other  down,  that  it  costs  as  many  locksful  as  there  are  locks 
in  the  ascension  of  each  boat.  He  founds  this  assertion  on  two  statements,  one  of  M.  Caligny,  the  other 
of  M.  Regemorte,  asserting  that  the  expenditure  of  the  water  is  the  same,  whether  contiguous  or 
separated  ; but  this  distinction  not  having  been  sufficiently  examined,  a second  error  has  been  com- 
mitted ; but  it  is  undoubted  that  when  locks  are  contiguous,  they  often  expend  more  than  two  locksful ; 
and  it  has  not  been  remarked  that  when  the  locks  are  more  than  640  feet  apart,  they  often  expend  only 
a single  lockful  for  the  whole  journey.  When  locks  are  distant  from  each  other,  and  the  boats  pass 
alternately,  one  up  and  the  other  down,  the  boat  which  passes  after  the  first  frequently  finds  in  mount- 
ing all  the  locks  empty,  and  to  fill  them  it  must  draw  a lockful  from  each  interval  and  one  from  the 
starting  point;  in  descending,  as  it  finds  the  locks  full,  it  does  not  draw  any  from  the  starting  point, 
consequently  it  will  only  expend  a single  lockful  in  its  whole  voyage. 

When  the  locks  are  distant  from  each  other,  and  the  boats  follow,  the  second  boat  will  find  all  the 
locks  full  going  up,  and  to  ascend  it  must  first  empty  all,  and  then  fill  them  with  water  drawn  from  the 
intervals,  and  the  highest  from  the  starting  point ; in  descending,  all  the  locks  will  be  empty,  and  the 
first  lock  will  be  filled  with  water  from  the  starting  point,  which  will  serve  to  fill  all  the  others,  so  that 
'h'.s  boat  will  expend  two  locksful  in  its  journey. 


240 


LOCKS  OF  CANALS. 


When  the  locks  are  so  near  each  other  that  the  water  of  one  taken  into  the  interval  between  the  two 
diminishes  the  depth  of  this  interval  sufficiently  to  impede  the  navigation,  or  when  the  locks  are  contig- 
uous and  the  boats  pass  alternately,  the  second  boat  in  ascending  finds  all  the  locks  empty,  and  as  it 
cannot  draw  water  from  the  intermediate  intervals  from  the  contiguity  of  the  locks,  all  are  filled  with 
water  from  the  starting  point.  Thus  in  ascending  eacli  boat  expends  as  many  locksful  as  there  are  con- 
tiguous chambers ; in  descending,  all  the  locks  being  full,  no  water  need  be  drawn  from  the  starting 
point,  consequently  in  a whole  journey  as  many  locksful  may  be  expended  as  there  are  contiguous  locks 
in  ascending.  When  the  locks  are  contiguous,  and  the  boats  pass  each  other  in  succession,  the  second 
in  ascending  will  find  all  the  locks  full,  and  to  enable  it  to  enter  the  intervals,  it  must  empty  them  suc- 
cessively to  fill  them  with  the  water  from  the  intervals,  except  the  last,  which  it  fills  with  water  from 
the  starting  point;  in  descending,  another  lockful  is  taken  from  the  starting  point,  so  that  in  this  case 
two  locksful  are  taken  from  the  latter. 

Although  the  four  above  cases  contain  the  whole  theory  of  the  working  of  locks,  it  may  be  remarked 
that  if  two  boats  meet  at  the  starting  point,  and  two  others  before  or  after  the  starting  point,  the 
four  will  expend  five  locksful ; if  two  boats  meet  at  the  starting  point,  and  the  two  following  meet  there 
also,  the  four  will  only  expend  four  locksful ; if  the  two  last  boats  that  have  passed  meet  before  or  after 
the  starting  point,  and  the  two  succeeding  meet  also  before  or  after  the  starting  point,  they  then  will  only 
expend  four  locksful,  had  the  first  come  in  an  opposite  direction  to  that  which  had  passed  previously, 
and  five  if  it  had  come  in  the  same  direction ; and  it  has  been  generally  observed,  that  a boat  always 
takes  a lockful  from  the  starting  point  to  ascend,  but  that  it  often  does  not  take  any  to  descend  on  the 
other  side  : consequently,  when  there  are  no  contiguous  locks,  the  boats  will  only  expend  a lockful  for 
their  whole  journey,  when  they  pass  the  starting  point  alternately,  one  going  up,  the  other  down : in 
like  manner,  where  there  are  contiguous  locks,  the  boats  will  expend  in  their  journey  as  many  locksful 
as  there  are  contiguous  locks  in  ascending;  when  one  boat  follows  another,  it  will  expend  two  locksful, 
whether  the  locks  are  contiguous  or  isolated.  It  must  be  remarked  that  the  passage  of  those  boats  only 
can  be  considered  relatively  to  the  locks  which  join  the  starting  point.  When  the  locks  are  not  contig- 
uous, and  their  fall  is  equal,  which  happens  in  the  lower  intervals,  it  has  no  influence  on  the  expenditure 
of  water,  especially  when  the  boats  do  not  stop  any  length  of  time  ; in  giving  640  feet  length  to  each 
interval,  it  is  evident,  when  two  boats  follow  each  other,  they  will  never  be  together  in  the  same  inter- 
val, since,  while  the  second  passes  the  lock,  the  first  will  have  time  to  pass  the  interval  and  enter  the 
following  lock ; thus  two  boats  cannot  meet  in  the  smaller  intervals,  except  when  one  ascends  and  the 
other  descends,  and  in  this  case,  as  one  takes  a lockful  from  the  interval,  while  a second  pours  one  into 
it,  consequently  the  water  does  not  diminish  or  increase  in  it.  It  must  be  observed  that  we  can  never 
have  above  a iockful,  more  or  less,  in  an  interval,  unless  several  boats  remain  in  them  together,  which 
should  be  avoided  when  they  are  small ; further,  when  the  contiguous  locks  are  distant  from  the  start- 
ing point,  it  often  happens  that  the  lockful  is  not  immediately  taken  ; but  when  there  is  no  second 
quantity  of  water  before  the  contiguous  locks,  it  is  always  the  starting  point  which  furnishes  that  of  the 
canal  above  them. 

Form  to  be  given  to  the  chambers  of  locks. — The  most  convenient  is  the  parallelogram,  a little  wider 
than  the  boats  that  require  to  pass,  and  sufficiently  long  to  admit  of  the  gates  being  moved  with  facility. 
The  chambers  of  the  canal  of  Languedoc  are  of  an  oval  form,  to  give  greater  strength  in  resisting  the 
banks  contiguous  to  them ; but  as  this  causes  an  increase  of  expense  in  construction  as  well  as  in  the 
quantity  of  water  necessary  to  fill  it,  it  will  be  useful  to  inquire  if,  in  avoiding  one  inconvenience,  a 
greater  is  not  produced.  The  oval  chambers  of  the  canal  of  Languedoc  contain  an  area  of  3636  feet, 
while  if  the  side  walls  were  parallel,  they  would  only  be  2248  superficial  feet.  Thus  the  expenditure 
of  water  in  the  oval  chamber  exceeds  more  than  a third  that  of  the  parallelogram,  the  proportion  being 
about  5 to  3.  The  inconvenience  is  considerably  increased  by  want  of  water,  which  frequently  occurs 
Another  result  of  the  oval  form  is,  that  the  passage  of  the  lock  is  also  longer  than  in  the  rectangular;  in 
the  same  proportion  the  expense  of  the  timber  platform  is  also  increased.  It  is,  however,  certain  that 
a curved  wall  is  stronger  against  a pressure  of  earth  than  a straight  one,  and  if  the  cost  of  masonry 
requisite  to  give  the  same  strength  to  a straight  wall  is  greater,  the  expense  is  compensated  for  by  the 
diminution  of  the  cost  of  the  timber  platform,  which  is  two-fifths  stronger.  It  is  very  essential  to  pre- 
vent the  filtration  of  water  through  the  side  walls,  and  the  best  method  to  effect  this  is  to  place  on  their 
thickness  a lining  of  beton,  or  of  brick  laid  in  cement,  which  will  be  impervious  to  water;  but  as  this 
will  destroy  the  bond,  a greater  thickness  of  wall  is  requisite ; thus  there  are  many  circumstances  where 
it  might  be  necessary  to  give  to  curved  walls  as  great  a thickness  as  to  straight.  The  thickness  of 
straight  walls  which  support  earth  should  be  a third  of  their  height,  while  those  which  resist  the  thrust 
of  water  should  be  one-half;  if  the  walls  of  the  chambers  of  locks  have  a thickness  relative  only  to  the 
thrust  of  the  earth,  they  may  give  way  when  the  earth  is  put  in  motion,  which  often  occurs  from  a slight 
filtration  behind  the  wall.  Gautliey  has  a rule  for  finding  the  thickness  to  be  given  to  the  wall  of  a 
basin  intended  to  support  water  throughout  its  whole  height,  and  in  the  chambers  of  locks  it  must  be 
remembered  that  the  thrust  of  the  water  against  the  vertical  surface  is  equal  to  the  product  of  these 
surfaces  by  half  the  height  of  the  water.  Call  h the  height  of  the  wall,  x = its  thickness,  supposing  its 
length  to  be  1 metre,  the  acting  power  will  be  1000  X 4 hi2;  supposing  the  cube  metre  of  water  to  weigh 
1000  kilogrammes,  and  the  centre  of  impression  of  this  thrust  being  at  a third  of  the  height  of  the  wall,- 
the  arm  of  the  lever  of  the  acting  power  will  be  equal  to  \ h. 

The  resisting  power  will  be  the  wall  itself=fi  vr  X 2000,  supposing  that  the  cube  metre  of  masonry 
generally  weighs  2000  kilogrammes.  The  arm  of  the  lever  will  be  half  the  thickness  of  the  wall  ^ x, 
consequently  the  momentum  of  the  acting  power  will  be  1000  X | h?  X § h,  and  that  of  the  resisting 
power  2000'  X J h x2 ; and  as  in  the  state  of  equilibrium  these  two  powers  should  be  equal,  we  shall 
have  161  h?  ~ 1000  h x2,  from  whence  we  hove  x — -J  0167  hs  = 0'41  h ; but  as  something  should  always 
be  allowed  above  the  equilibrium,  by  adding  4-,  we  shall  have  x=\h  nearly.  Hence  it  is  evident  that 


LOCKS  OF  CANALS. 


241 


the  thickness  of  a wall  intended  to  support  water  should  be  at  least  equal  to  half  the  height  of  the  water 
which  acts  against  it. 

The  length  and  width  of  chambers  of  locks  must  necessarily  be  regulated  in  conformity  with  the 
boats  used  on  the  canal;  these  are  generally  longer  and  narrower  than  those  on  rivers,  where  the  slial 
lows  which  occasionally  occur  require  flatter  bottoms  to  be  given  them.  With  regard  to  the  length  oi 
the  chambers,  it  should  be  such  as  to  enable  the  gates  at  the  lowest  ends  to  open  and  shut  easily;  ii 
the  rudder  of  the  boat  cannot  be  unshipped,  or  occupies  any  portion  of  the  length  of  the  chamber,  then 
the  chambers  must  be  made  sufficiently  long  to  prevent  them  from  interfering  with  the  opening  of  the 
gate,  on  which  account  the  most  proper  rudders  for  navigable  canals  are  those  like  broad  oars,  which 
can  be  taken  out  while  passing  through  the  locks.  The  height  of  the  water  in  the  intervals  is  regu- 
lated by  the  mean  height  of  the  waters  of  the  river  which  communicate  with  the  canals.  It  is,  however, 
customary  to  allow  the  latter  a sufficient  height  of  water  to  receive  boats  of  the  same  tonnage  as  those 
which  navigate  the  river;  another  advantage  in  giving  an  extra  depth  of  water  to  canals  is  the  greater 
ease  with  which  the  boats  can  be  drawn,  the  weeds  at  the  bottom  causing  less  inconvenience,  and  the 
evaporation  being  of  course  less  than  in  a shallower  body  of  water ; in  summer  also,  when  the  boats  can 
only  carry  half  a load,  two  loads  may  be  put  into  one  boat,  and  the  transport  rendered  less  expensive. 

The  quantity  of  water  expended  by  locks  is  found  to  be  in  direct  proportion  to  the  height  of  the  fall, 
and  the  time  employed  in  going  through  them,  and  the  expense  of  construction  nearly  in  the  same  pro- 
portion ; this  is  greater  as  the  locks  are  least  elevated,  because  they  are  more  in  number,  but  the 
increase  is  not  in  proportion  to  the  number. 

Gates  of  locks  are  composed  of  two  posts  placed  vertically,  and  united  by  horizontal  rails ; the 
former,  being  supported  throughout  their  height,  are  not  subject  to  much  wear,  although  they  are  of 
larger  scantling  than  the  other  timbers  of  the  gate,  which  is  necessary,  as  they  sustain  the  entire  frame- 
work. The  horizontal  rails  resist  the  weight,  and  as  that  weight  is  greater  where  the  rails  are  placed 
below  the  level  of  the  water,  it  would  seem  natural  that  their  dimensions  should  vary  in  proportion  to. 
the  weight.  To  determine  these  dimensions  it  must  be  recollected  that  the  thrust  of  water  against 
vertical  surfaces  is  equal  to  the  weight  of  a prism  of  water  having  its  surfaces  as  a base,  and  its  height 
half  that  of  the  water.  It  must  next  be  considered  that  the  rails  of  the  gate  are  at  least  26  inches 
apart,  and  38  inches  from  centre  to  centre,  so  that,  on  account  of  the  casing  of  plank  in  the  first 
instance,  12  inches  of  height  support  26  inches  of  water,  and  in  the  second  38  inches.  The  weight  sup- 
ported by  each  rail  will  be  found  by  multiplying  their  length,  the  interval  from  one  to  the  other,  the 
height  of  the  water  above  the  centre  of  the  rail,  and  the  whole  by  62  pounds,  the  weight  of  a cube  foot 
of  water;  the  product  of  these  measures  will  be  the  number  of  pounds  which  the  rails  ought  to  support 
throughout  their  whole  length. 

Timbers  from  4 to  5 inches  square  would  be  sufficient  for  small  gates,  and  for  larger  from  8 feet  6 
inches  to  10  feet  6 inches  of  fall;  with  a width  of  17  feet  between  the  hanging-posts,  the  rails  would  be 
sufficiently  strong  if  from  7 to  8 inches  square,  putting  six  rails  in  the  height.  They  are  generally  from 
9 to  10  inches  at  least,  which  is  double  the  strength  required  ; it  is  true  that  the  gates  are  more  durable, 
but  the  weight  is  greater,  which  is  sometimes  injurious  to  the  collar  and  the  masonry  to  which  it  is 
attached,  requiring  more  reparations  than  lighter  gates. 

The  frames  or  styles  of  gates  should  be  at  least  5 inches  in  thickness  more  than  the  rails,  and  the  joint 
covered  by  a fillet,  as  well  as  the  edge  of  the  planks,  which  are  affixed  perpendicularly  to  the  rails,  and 
mortised  into  the  styles,  increasing  the  strength  of  the  rails  and  the  framework  by  their  greater  thick- 
ness. Braces  are  also  introduced  between  the  rails,  which  aid  materially  in  strengthening  them,  and  by 
their  inclined  position  transfer  the  stress  to  the  hanging-post. 

Great  gates  should  always  have  a line  of  braces  placed  diagonally,  and  making  an  angle  with  the 
lower  rail;  all  the  braces  above  should  have  the  same  effect,  and  consequently  the  same  inclination  ; 
those  below  resting  on  the  lower  rail  tend  to  depress  it,  and,  even  when  properly  framed  and  pinned 
into  the  rails,  their  inclination  towards  the  hanging-post  renders  them  insufficient  to  sustain  the  lower 
rail ; but  they  may  be  made  useful  by  giving  them  an  inclination  in  a contrary  direction,  and  uniting 
them  by  pins  to  the  rails. 

Instead  of  inclining  the  braces  below  the  diagonals  on  the  side  of  the  strutt ing-post,  a bar  of  iron  is 
sometimes  placed  diagonally  from  the  collar  to  the  lower  end  of  the  strutting-post,  which  is  an  excellent 
contrivance ; or  the  planks  may  be  placed  diagonally,  inclining  them  from  the  side  of  the  hanging-post, 
and  crossing  them  solidly,  especially  that  of  the  diagonal  above  the  hanging-post,  and  at  the  extremity 
of  the  lower  cross-piece ; or  instead  of  a plank,  a piece  may  be  let  in  in  an  opposite  direction  to  the  cross- 
pieces, which  must  not  be  mortised  into,  or  very  little,  that  it  may  not  be  in  any  way  weakened ; this 
piece  united  carefully  to  the  lower  cross-piece  would  tie  it  to  the  post,  and  give  more  solidity  to  the 
framework ; the  diagonal  position  of  the  planks  gives  them  more  strength  to  resist  the  pressure.  There 
is  a little  loss  of  material,  but,  on  the  other  hand,  plank  of  different  kinds  may  be  used  after  cutting  out 
the  knotty  or  defective  portions. 

Gates  are  opened  by  means  of  large  timbers  fixed  above  the  posts,  forming  a counterpoise  to  the  gate, 
and  preventing  it  from  grinding  the  collars  and  racking  the  framework ; for  this  purpose  the  tail  of  the 
balance-beam  must  be  very  large.  Trees  are  sometimes  used  with  their  butt  ends  not  cut  off,  to  which 
it  is  easy  to  add  any  additional  weight.  The  hanging-posts  often  allow  much  water  to  be  lost,  in  con- 
sequence of  being  obliged  to  give  them  sufficient  play,  and  this  could  scarcely  be  prevented  if  the  pivot 
had  not  a little  motion,  and  the  collar  fitted  exactly ; but  the  weight  of  water  occasions  the  gate  to 
unite  by  pressing  it  considerably  against  the  hanging-post ; still  as  this  is  cut  circularly,  it  only  leans 
against  a small  portion  of  its  surface,  and  the  water  easily  passes,  notwithstanding  the  great  pressure. 
To  remedy  these  defects,  the  posts  should  be  partly  cut  in  a circular  form,  and  partly  bevelled ; the 
latter  leaning  along  its  whole  length  upon  the  rebate  made  to  receive  it,  which  having  a corresponding 
bevel  interrupts  any  filtration ; the  circular  part  should  not  touch  the  masonry,  but  have  sufficient  play 
without  affecting  the  ease  of  the  motion. 

Vol.  II — 16 


242 


LOCKS  OF  CANALS. 


The  gates  of  locks  of  navigable  canals  are  made  in  a right  line,  but  in  great  sea-locks  they  are  curved ; 
Belidor  lias  demonstrated  that  these  latter  are  not  more  solid  than  the  former,  but  this  must  only 
be  understood  when  the  curved  timbers  are  made  out  of  straight  pieces ; for  it  is  undoubted  that,  it 
naturally  curved,  they  are  much  stronger,  and  will  resist  more  pressure  than  straight  pieces,  especially 
when  resting  on  their  two  extremities.  The  collars  embrace  the  whole  heel-post,  which  being  generally 
12J  inches  in  diameter,  produces  considerable  friction,  especially  when  the  balance-beam  does  not  act 
as  a counterpoise ; a large  bolt  may  be  placed  in  the  axis  of  the  post,  and  a smaller  collar  be  substituted 
to  confine  it ; but  this  method  can  only  be  applied  to  chamfered  posts ; round  posts  must  have  a motion 
in  their  collar  to  lean  against  the  hanging-posts,  which  could  not  be  effected  by  an  axis ; the  collars 
must  be  attached  to  iron  anchors  strongly  bedded  into  massive  masonry.  The  pivots  often  get  deranged, 
the  posts,  as  generally  made,  causing  considerable  play ; if  these  were  bevelled,  the  pivots  might  be 
fixed  and  bedded  in  large  stones  cramped  to  those  adjoining,  or  united  with  anchors  to  the  surrounding 
masonry.  Formerly  the  pivots  were  made  of  copper,  but  cast-iron  is  equally  efficient;  they  should  be 
the  same  size  as  the  ends  of  the  posts,  and  terminated  at  the  lower  end  in  a spherical  form.  The  other 
iron  work  of  the  gates  consists  of  squares  laid  on  at  right  angles,  which  must  be  very  strong ; it  is  also 
well  to  lay  on  the  rails  of  each  sluice  a band  or  two  of  iron  to  bolt  them  securely  together. 

Lock-gates  measuring  8 feet  from  the  centre  of  one  heel-post  to  that  of  the  other,  are  in  some  canals 
on  a segment  of  a circle,  the  chord  of  which  is  about  the  sixth  of  the  span,  or  a little  more  : these  pro- 
portions not  only  allow  of  the  gates  being  smaller,  lighter,  and  stronger,  but  also  increase  the  pressure 
of  the  heel-post  against  the  hollow  quoins,  which  renders  them  quite  water-tight.  Where  canals  are 
narrow,  the  paddles  of  both  the  upper  and  lower  gates  are  usually  kept  open  by  an  iron  pin  inserted 
between  the  teeth  of  a rack  and  pinion  which  raises  them : when  the  paddle  is  required  to  be  shut,  the 
pin  is  withdrawn,  and  the  paddle  falls  by  its  own  weight. 

Hollow  quoins,  or  upright  circular  grooves,  are  formed  in  the  side  walls,  at  the  ends  of  the  timber 
sills,  serving  as  the  hinge  for  the  gates ; the  upright  post  that  turns  within  them  is  called  the  heel  of 
the  gate,  and  the  other  the  head.  The  former  are  retained  in  their  position  by  a gudgeon  or  pivot  turn- 
ing in  a cup  let  into  the  foundation  stones  for  the  purpose ; sometimes  the  pivot  is  fixed,  and  the  cup 
revolves  upon  it.  The  upper  part  of  the  post  is  retained  by  an  iron  ring  or  strap  let  into  the  side  wall, 
and  made  very  secure  ; the  hollow  quoins  should  be  worked  with  great  attention  ; they  are  usually  of 
stone  or  brick,  though  cast-iron  has  been  found  well  suited  for  the  purpose. 

Lock-gates  of  large  dimensions  are  now  usually  opened  and  shut  by  machinery,  and  the  boom  or  spar 
attached  to  the  head-post  entirely  dispensed  with  : on  many  canals  a rack-bar  of  wrought-iron  is  con- 
nected with  the  gates,  which  are  furnished  with  rollers  to  run  in  a groove  fitted  into  the  sill,  and  by 
working  a wheel  and  pinion,  they  can  be  opened  and  shut  at  pleasure.  We  ought  not  to  omit  mention 
of  several  gates  formed  like  boats,  upon  the  principle  of  the  camel,  which  rise  and  fall  in  deep  recesses 
prepared  to  receive  them  as  water  is  pumped  out  or  admitted  into  them  : such  boat-gates  are  sometimes 
constructed  with  three  parallel  keels,  which  fit  into  as  many  grooves  in  the  side  walls  of  the  lock ; they 
are  maintained  in  their  position  bv  admitting  the  water,  and  raised  by  pumping  out  their  contents,  after 
which  they  are  floated  away ; for  the  stop-gates  of  docks  such  a contrivance  is  well  adapted,  but  where 
the  navigation  is  regular,  as  on  a canal,  they  are  not  found  to  answer,  from  the  time  requisite  to  open 
and  replace  them.  See  Floating  Gates  of  Dry  Dock. 

The  angle  to  be  given  to  double  lock-gates  has  long  occupied  the  attention  of  engineers,  but  the 
strongest  position  may  be  taken  when  the  angle  at  the  base  is  85°  16'  nearly,  and  the  sally  of  the  gate 
is  or  a trifle  more  than  one-third  of  the  breadth  of  the  lock. 

Valves. — Some  lock-gates  have  their  paddles,  or  valves,  made  to  open  and  shut  by  the  movement  of 
a lever,  the  lower  end  of  which  being  loaded,  keeps  it  always  over  the  aperture  in  the  lower  part  of  the 
gate : when  it  is  required  to  be  moved,  the  upper  part  or  handle  of  the  lever  is  pulled  back,  and  the 
water  forcing  its  passage  through,  keeps  it  open  until  its  weight  overcomes  the  power,  and  it  is  balanced 
back  into  its  original  position. 

The  crank  and  pinion  working  in  a toothed-rack  are  now  generally  applied  to  raise  the  paddle. 

Screws  are  sometimes  used  for  this  purpose,  formed  of  wood,  sliding  up  and  down  in  a rebated  frame, 
fixed  in  the  stone  mouth  of  the  conduit  or  paddle-hole ; the  lateral  pressure  of  the  water  occasions  it  to 
adhere  closely  to  the  frame,  so  that  it  is  not  only  necessary  to  make  it  run  with  the  grain  of  the  wood, 
but  also  to  have  considerable  power  to  move  it : this  is  occasionally  effected  by  means  of  a long  iron 
lever,  with  an  eye  at  one  end  that  spans  the  square  end  of  the  screw,  and  allows  a sufficient  force  to 
be  applied  to  raise  the  paddle. 

There  are  several  applications  of  the  screw,  one  of  which,  as  used  at  the  gates  of  Dunkirk,  is  very 
simple,  and  was  for  a long  time  adopted  throughout  Europe.  To  overcome  the  hydrostatic  pressure  and 
friction  at  the  mouth  of  the  paddle-hole  was  a horizontal  circular  opening,  within  which  was  inserted  an 
open  cylinder  of  wood  or  iron  ground  to  fit  it,  which  could  be  raised  by  a lever;  the  waste  water  of  the 
canal  could  then  escape  over  the  upper  lip  of  the  cylinder  and  afterwards  pass  out  by  the  paddle- 
holes. 

The  following  figures  represent  the  latest  improvements  for  the  valves  or  sluices  of  a lock-gate. 
Fig.  2598  is  an  elevation.  Fig.  2599  a vertical  section  through  G G.  Fig.  2600  a horizontal  section 
through  A A. 

The  object  of  this  improvement  is,  that  while  the  gate  is  kept  close  and  tight  by  the  pressure  of  the 
water  forcing  it  against  its  seat,  the  effort  of  lifting  the  gate  shall  at  the  same  time  relieve  the  segt 
from  the  pressure  of  the  water ; and  this  is  effected  by  means  of  friction-rollers  h h,  which  immediately, 
upon  the  commencement  of  the  lifting  of  the  gate,  act  as  short  inclines,  thus  taking  the  pressure  from 
the  seat,  and  throwing  it  upon  the  friction-rollers  or  wheels,  easing  the  lifting  of  the  gate.  When  the 
gate  is  closed,  the  wheels  have  run  off  the  inclines,  and  the  gate  bears  against  its  seat  with  the  pressure 
slue  the  head  ot  water 


LOCKS  OF  CANALS. 


24? 


Iron  lock-gates. — The  frames  of  those 
at  the  Wet  Dock  at  Montrose  are  of  cast- 
iron,  and  entirely  covered  on  both  sides 
■with  wrought-iron  boiler-plate : where 
they  are  placed  the  entrance  is  55  feet 
wide  in  the  clear,  and  the  centre  of  the 
heel-post  is  1 foot  within  the  face  of  the 
wall,  the  distance  between  their  centres 
being  57  feet : the  height  of  the  gates  is 
22  feet  6 inches;  they  point  10  feet,  and 
their  ribs  have  a curvature  on  the  hollow 
side  of  18  inches.  The  heel-posts  are  21 
inches  in  diameter,  and  in  form  a little 
more  than  a semicircle  ; after  casting  they 
were  turned  in  a lathe : the  thickness  of 
the  metal  is  14  inch;  they  each  fit  into  a 
cast-iron  socket,  and  work  on  an  iron  gud- 
geon 10  inches  in  diameter,  cast  on  a sole- 
plate  4 feet  6 inches  long,  21  inches  wide, 
and  2 inches  thick  ; this  is  dovetailed  and 
riveted  firmly  into  the  stone,  and  after- 
wards so  keyed  as  to  press  the  heel-posts 
into  the  quoins,  which  are  of  Kingoodie 
stone,  polished  as  nearly  to  the  circle  as 
possible,  and  the  stone  and  iron  are  in 
such  close  contact,  that  the  water  is  effect- 
ually prevented  from  passing  throughout 
any  portion  of  their  height. 

The  mitre-posts  are  184  inches  ,in 
breadth,  14  inch  thick : holes  are  cast  in  them  for  the  introduction  of  the  iron  bars,  of  which  there  are 
eleven  to  each  leaf,  2 inches  thick,  16  inches  broad  at  the  ends,  and  18  in  the  middle;  their  cross  ends 
are  18  inches  in  height  and  2 in  thickness,  with  44  inch  screw-bolts  to  each,  which  pass  through  the  heel 
and  mitre  posts.  The  clap  sill  was  cast  in  two  pieces  for  each  leaf;  it  is  8 inches  in  depth  and  1J  inch 
thick  ; the  height  of  the  sill  above  the  platform  is  15  inches.  The  bottom  bar  is  of  oak  12  inches  thick, 
17  inches  broad  at  the  ends,  and  19  in  the  middle ; this  is  bedded  on  felt  to  the  lowermost  cast-iron  bar, 
and  securely  fixed  by  14  inch  bolts.  The  boiler-plates  which  line  both  sides  of  the  gates  are  so  ar- 
ranged that  they  break  joint;  for  6 feet  in  height  their  thickness  is  § of  an  inch — above,  only  they 
overlap  each  other  about  24  inches,  and  were  riveted  on  while  hot,  that  the  rivets  might  completely  fill 
up  the  holes.  The  collars  of  the  heel-posts  are  of  wrought-iron,  4 inches  by  2 inches,  keyed  through  the 


244 


LOCOMOTIVE  ENGINE. 


anchors,  which  are  of  cast-iron,  3}  inches  square ; they  are  dovetailed  into  the  quoins,  and  run  with  lead 
The  roller  segments  or  railways  are  10  inches  in  breadth  by  1 4 inch,  4 inches  in  thickness;  they  arfl 
sunk  into  the  stone,  and  securely  bolted,  and  bedded  with  feltUnd  white  lead. 

The  rollers  are  of  cast-iron  and  conical,  18  inches  in  diameter,  and  5 inches  in  thickness,  with  turned 
steel  axles;  the  roller-boxes  are  qf  cast-iron  II  inch  thick,  moulded  to  the  bevel  of  the  gates,  and  fast- 
ened by  screw-bolts  through  the  flanks  of  the  horizontal  bars : cast-iron  covers  confine  the  roller-blocks, 
which  slide  up  and  down  withinside  the  boxes  by  the  action  of  the  top  screws ; the  roller-bars  are  oi 
wrought-iron,  3 inches  in  diameter,  keyed  into  the  blocks  at  the  bottom,  each  being  steadied  by  three 
plummer-blocks  ; each  bar  near  the  top  has  a coupling,  with  a square  threaded  screw,  and  a brass  nut 
at  the  top,  working  in  a cast-iron  bracket,  which  bears  the  whole  weight  of  the  outer  end  of  the  gate, 
and  is  fastened  by  three  screw-bolts  through  the  flanges  of  the  horizontal  bars.  Each  leaf  has  a sluice, 
3 feet  by  2,  the  frames  of  which  are  7 inches  broad  and  II  inch  thick  ; the  sluice-valves  are  also  II  inch 
thick ; ail  the  screwed  bolts  have  zinc  nuts,  tQ  prevent  the  iron  from  rusting : the  sluice-rods  are  2 
inches  in  diameter,  and  have  a square  threaded  screw,  and  a brass  nut  at  the  top ; these  are  worked  by 
a wheel  and  pinion,  and  bevelled  geer,  with  a crank-handle,  nearly  level  with  the  hand-raiL 

The  gangway  is  42  inches  in  width,  and  is  supported  on  cast-iron  brackets  for  each  leaf;  cast-iron 
ballusters  and  a wrought  rail  is  attached  to  the  convex  side  of  the  gates,  with  movable  iron  stanchions 
and  chains  on  the  other;  in  each  heel-post  is  a pump  with  a brass  chamber  and  boxes,  2 1 inches  in 
diameter,  with  a lead  pipe  down  to  the  bottom. 

The  gates  are  worked  by  four  double-purchase  capstans,  and  geering  with  seven  8-inch  chains.  Tliei? 
weight  is  as  follows : 

Tons.  Cwt. 


Cast-iron  work  in  the  gates 64  14 

Wrought-iron  22  154 

Brass 0 5 

Zinc 0 14 

Cast-iron  in  segments  and  other  fittings  19  0 


107  0 

fit  Woolwich  the  clear  opening  of  the  dock-gates  is  65  feet,  and  the  weight  of  each  of  the  two  iron 
g ites  is  150  tons.  See  Gates  of  Dry  Dock,  Brooklyn  Navy  Yard. 

LOCOMOTIVE  ENGINE, — 1.  A locomotive  engine  is  a steam-engine  with  two  cylinders,  formed 
on  the  high-pressure  principle,  without  a condenser.  The  motion  of  the  pistons  is  caused  by  the  intro- 
cb’Ction  of  steam  into,  and  its  alternate  escape  from,  the  cylinders,  which  is  transmitted  by  means  of  con- 
necting-rods to  an  axle,  furnished  with  two  cranks. 

In  boilers  of  locomotive  engines  the  fire  is  inclosed  in  a box  having  a double  casing,  with  a body  of 
water  between:  The  air  enters  between  the  grate-bars.  The  smoke,  flame,  and  gas,  produced  by  the 

combustion  of  the  fuel  pass  through,  in  their  way  to  the  chimney,  a great  number  of  tubes,  which  are 
situated  in  the  cylindric  part  of  the  boiler,  and  extend  from  the  fire-box  to  the  smoke-box,  and  are  sur- 
rounded by  water.  These  tubes,  being  of  very  small  diameter,  would  not  pass  off  the  flame  and  gas 
with  sufficient  rapidity  if  they  were  not  urged  by  a powerful  draught ; this  is  also  rendered  necessary 
to  overcome  the  friction,  and  the  resistance  offered  by  the  cold  air  within  them. 

2.  Of  tlce  draught.— The  draught  is  employed  to  produce  a fresh  supply  of  air  in  the  fire-grate,  and 
thereby  supply  the  oxygen  necessary  for  the  combustion  of  the  fuel  ; it  is  accomplished  by  allowing  the 
waste  steam  to  escape  at  a tolerably  high  pressure,  after  it  has  fulfilled  its  office  in  the  cylinders.  This 
steam  is  conveyed  from  the  cylinders  to  the  chimney  by  a pipe,  the  upper  end  of  which  is  contracted 
for  the  purpose  of  confining  it,  and  checking  its  too  rapid  escape.  If  passes  off  at  regular  intervals, 
according  to  the  velocity  of  the  engine,  and  the  force  of  each  puff  depends  upon  the  pressure  of  the 
steam.  The  velocity  of  the  steam  in  the  blast-pipe  is  equal  to  that  due  to  the  initial  pressure  of  the 
steam,  whatever  may  be  the  size  of  the  mouth  of  egress ; but  the  pressure  is  at  once  reduced  if  the  size 
of  the  orifice  of  the  blast-pipe  be  considerable.  The  great  speed  with  which  the  steam  escapes  in  the 
chimney  imparts  to  the  air  around  it  a corresponding  velocity  ; and  this  air  can  only  be  replaced  by  a 
current  passing  from  the  grate  through  the  fire  and  tubes. 

We  should  observe  that  the  contraction  of  the  blast-pipe  at  its  upper  extremity,  being  for  the  purpose 
of  checking  the  escape  of  the  steam,  and  prolonging  the  time  of  its  engagement,  a continued  pressure  of 
waste  steam  is  consequently  the  result,  which  should  be  regulated  by  proper  rules  or  laws,  as  it  ought 
not  to  exceed  more  than  is  necessary.  This  pressure  is  therefore  an  obstacle  to  the  progress  of  the 
engine,  in  consequence  of  the  draught  invariably  having  the  effect  of  absorbing  a part  of  the  power  of 
the  engine.  Its  influence,  however,  is  not  felt  when  moving  at  a slow  velocity,  on  account  of  the  inter- 
vals being  longer,  which  gives  more  time  for  the  steam  to  escape ; but  when  the  speed  is  great,  the  pis- 
ton-strokes are  so  rapid  that  the  pressure  of  steam  in  the  blast-pipe  is  almost  continuous.  This  pres- 
sure, consequently,  forms  a resistance  to  the  motion  of  the  piston. 

3.  Of  the  boiler. — The  boiler  is  the  most  important  part  of  the  engine.  There  is  a fire-box  connected 
with  it,  the  bottom  of  which  supports  the  grate-bars,  and  the  four  sides  are  formed  double,  in  such  a 
manner  as  to  allow  of  a space  of  24  to  4 inches  between  them,  which  is  occupied  by  water ; the  fire-box 
is  therefore  surrounded  by  water.  It  is  very  important  to  preserve  a sufficient  width  of  water  space, 
otherwise  the  velocity  of  the  steam  at  this  part  of  the  boiler  would  prevent  the  water  being  replaced 
with  sufficient  rapidity,  the  great  heat  to  which  the  fire-box  is  exposed  producing  steam  of  very  great 
force  the  walls,  also,  from  not  being  sufficiently  cooled  by  the  water,  would  acquire  a high  degree  ol 
temperature,  which  would  likewise  promote  the  formation  of  incrustations — the  space  would  conse- 
quently become  filled  up,  and  the  casing  soon  destroyed  from  the  action  ot  the  fire.  This  serious  incon- 
venience has  occurred  in  boilers  where  the  water-space  has  been  made  2 or  2 4 inches.  The  top  of  thg 


LOCOMOTIVE  ENGINE. 


245 


fire-box  is  strengthened  by  pieces  of  iron,  that  the  force  of  the  steam  may  not  rupture  it ; and  the  whole 
of  the  flat  portions  of  the  boiler,  being  unable  to  resist  the  pressure  of  the  steam  within,  are  also  strongly 
secured  together  by  bolts  to  prevent  their  giving  way  ; but  this  is  unnecessary  with  the  cylindric  portion 
of  the  boiler,  which  resists  the  pressure  without  the  tendency  to  rupture.  This  part  is  traversed  by  100 
to  150  or  more  copper  tubes,  through  which  the  flame  and  the  gas  produced  from  the  fuel  escape 
The  extremities  of  these  tubes  are  secured  to  the  plates  at  each  end  of  the  boiler. 

Considering  the  complication  of  this  casing,  one  can  readily  conceive  the  great  play  of  expansion  and 
contraction  produced  by  the  rise  and  fall  of  the  temperature,  and  how  much  the  action  of  such  powerful 
forces  tends  to  wear  it  out,  and  to  occasion  shocks  which  the  several  surfaces  exposed  to  the  pressure  of 
the  steam  are  unequal  to  withstand,  their  form  being  unfavorable  to  it;  thus,  the  flat  parts  become  the. 
soonest  deranged.  Another  circumstance  which  increases  these  defects  arises  from  the  two  extreme 
parts  of  the  boiler  being  secured  together,  partly  by  the  frame  and  partly  by  the  rails  or  cross-pieces. 
The  latter  are  attached  to  the  lining  of  the  fire-box  at  one  end,  and  to  the  smoke-box  at  the  other,  and 
are  kept  cool  by  the  air,  and  therefore  are  not  subjected  to  those  alternate  changes  which  the  body  of 
the  boiler  undergoes.  As  long  as  they  remain  fixed  in  their  original  position,  they  offer  resistance  to 
the  play  of  the  other  parts  ; but  when  at  length  they  become  unfastened,  they  afford  a passage  of  escape 
to  fhe  water  of  the  boiler.  We  must  conclude,  from  all  these  forces  acting  against  each  other,  that 
locomotive  engines  possess  some  degree  of  elasticity  in  their  several  joinings  and  fastenings,  although 
difficult  to  be  perceived,  and  which,  so  far  from  impeding  their  progress,  actually  renders  it,  after  a 
time,  more  easy  than  before. 

The  surface  of  the  grate  varies.  The  economy  attending  great  fires  arises  from  the  heat  being 
proportionately  much  more  regular  than  with  small  ones.  It  is  possible  that  the  rise  of  temper- 
ature, produced  by  the  burning  of  a large  body  of  fuel,  exerts  an  unfavorable  influence  on  the  flat 
sides  of  the  fire-box,  the  dimensions  of  which  are  so  considerable.  It  is  probable  that  an  increase 
in  the  depth  of  the  grate,  combined  with  the  employment  of  a fuel  so  little  inclined  to  cake 
as  coke,  would  be  found  more  advantageous  than  enlarging  its  surface,  since  the  passage  of  the  air 
through  a great  thickness  of  coke  would  raise  a large  quantity  of  it  to  the  temperature  necessary 
for  its  combustion,  instead  of  passing  through  the  fire  unconsumed,  as  it  does  when  filled  with 
too  large  pieces  or  laid  too  thin.  This  remark  applies  equally  well  to  the  employment  of  anthracite 
coal. 

We  have  only  to  remark,  in  addition  to  our  description  of  the  boilers  of  locomotive  engines,  that  the 
casing  should,  at  the  same  time,  possess  great  strength  and  pliability  ; thus,  where  a very  powerful 
draught  is  created  from  a rapid  succession  oi  puffs  of  high-pressure  steam,  the  heat  of  the  fire  gives  a 
high  temperature  to  the  several  surfaces  of  the  fire-box  and  tubes,  and  steam  of  extraordinary  power 
is  generated ; but  if  the  door  of  the  fire-box  be  opened,  a large  quantity  of  cold  air  is  admitted,  or  if 
the  pumps  be  held  open  too  long,  the  air  introduces  itself  into  the  boiler,  and  instantly  checks  the  gen- 
eration of  steam ; the  pressure  is  consequently  diminished,  and  at  length  becomes  unequal  to  a rapid 
transit  of  the  engine. 

In  locomotive,  as  in  stationary  engines,  the  whole  of  the  parts  in  contact  with  fuel,  flame,  and  hot  air, 
should  be  covered  with  water.  The  most  serious  consequences  occur  if  the  uncovered  portions  are 
allowed  to  become  red-hot,  and  a quantity  of  water  sufficient  to  cover  them  is  suddenly  let  into  the 
boiler ; the  production  of  steam  is  so  rapid,  that  it  becomes  too  considerable  to  be  wholly  carried  off  by 
the  valves,  and  an  explosion  consequently  follows. 

Another  very  essential  point  for  the  preservation  of  boilers  is  to  prevent  the  formation  of  deposits. 
These  arise  from  the  calcareous  matter  disengaged  from  the  water  when  it  is  converted  into  steam,  and 
which  is  not  wholly  carried  away  with  it ; but  an  earthy  matter  is  left,  which  is  constantly  increasing  in 
bulk.  These  incrustations  become  fixed  principally  on  those  parts  where  the  greater  portion  of  the 
steam  is  generated  ; and,  as  they  acquire  thickness,  it  results  that  less  steam  is  produced,  from  their 
being  bad  conductors  of  heat : the  metal  upon  which  they  are  fixed  is  heated  to  a much  higher  degree 
than  the  other  parts,  as  it  is  not  cooled  by  immediate  contact  with  the  water.  This  rise  in  the  tem- 
perature of  the  metal  increases  the  action  of  dilatation,  and  renders  it  less  able  to  resist  the  pressure  ; 
it  also  has  the  effect  of  burning  it ; the  boiler,  therefore,  requires  to  be  often  cleaned. 

This  incrustation  is  the  most  powerful  destroyer  of  locomotive  engines,  and  it  is  of  the  greatest  im- 
portance to  find  some  means  of  getting  rid  of  it. 

When  the  escape  of  steam  from  the  cylinder  is  sufficiently  strong  to  cause  a powerful  draught,  then 
the  power  of  generating  steam  attains  its  maximum ; at  which  instant  the  bulk  of  the  water  in  the 
boiler  rises  artificially  to  the  height  of  two  or  three  inches.  This  is  caused  by  the  rapid  passage  of  the 
particles  of  steam  through  the  water,  which  has  the  effect  of  increasing  its  volume.  As  soon  as  the 
throttle  is  shut,  the  emission  of  steam  is  suspended  and  the  water  takes  its  natural  level ; also  when 
cold  water  is  injected  into  the  boiler,  which,  in  proportion  as  it  is  introduced,  condenses  those  particles 
of  steam  with  which  it.  comes  in  contact  in  the  mass  of  heated  water,  and  thus  restores  the  density  it 
had  lost.  It  results  that  the  level  of  the  water  remains  constantly  at  the  same  mark  as  long  as  it 
continues  to  be  fed,  and  that  the  introduction  of  water  is  only  perceivable  by  tire  reduction  of  the 
pressure. 

Another  fact  equally  important  is  the  disposition  of  all  locomotive  engines,  more  or  less,  to  carry 
away  a quantity  of  water  into  the  cylinders  with  the  steam,  called  primintj.  This  inconvenience  arises 
from  various  causes.  Among  them  may  be  reckoned  particles  filling  the  boiler  so  full  that,  the  water 
rises  up  beneath  the  dome  over  the  steam  entrance,  and  is  conveyed  into  the  steam  entrance-pipe  with 
the  same  velocity  as  the  steam,  and  introducing  greasy  matters,  which,  becoming  mixed  with  the  water, 
give  it  a property  analogous  to  that  of  milk  when  submitted  to  an  ebullition,  and  the  quantity  of  water 
engaged  by  the  steam  in  this  case  is  very  considerable. 

It  may  also  result  from  the  small  diameter  of  the  dome,  its  want  of  height,  or  the  space  reserved  for 
steam  above  the  surface  of  the  water  being  too  small,  or  the  dome  being  placed  over  the  fire-box,  which 


246 


LOCOMOTIVE  ENGINE. 


is  too  often  the  case ; that  is  to  say,  it  is  placed  at  that  part  where  the  evaporation  is  greatest,  and  the 
particles  of  water  are  in  the  strongest  agitation. 

Of  the  draught. — One  of  the  means  employed  in  regulating  the  draught  consists  in  placing  a disk 
valve  at  the  extremity  of  the  blast-pipe,  which  was  the  invention  of  Stephenson.  This  falve  is  open  in 
the  middle,  by  which  it  does  not  offer  any  obstacle  to  the  passage  of  the  steam ; but  it  can  be  made  to 
close  the  passage  whence  the  flame  or  gas  produced  by  the  fuel  issues,  when  required.  This  damper  is 
managed  by  the  engine-driver  by  means  of  a lever-rod. 

This  valve  is  also  useful  for  another  purpose.  Thus,  when  the  men  extinguish  the  fire  of  the  engine 
after  it  has  finished  work,  the  grate  being  done  with  and  removed,  the  air  enters  at  this  part  with  great 
freedom,  the  heat  of  the  engine  maintaining  a very  strong  draught.  Now  the  effect  of  this  passage  of 
cold  air  is  detrimental  to  the  boiler,  for  the  reasons  before  stated ; therefore,  if  Stephenson’s  damper  be 
fitted  in  the  chimney,  and  care  be  taken  to  shut  it  close  on  these  occasions,  the  current  of  air  would  be 
checked,  and  an  excellent  effect  would  result  from  it. 

Of  explosions. — We  have  few  remarks  to  make  on  the  subject  of  explosions  connected  with  locomotive 
engines.  Accidents  of  this  kind  are  wholly  attributable  to  the  wilfulness  of  the  engine-driver,  or  a want 
of  care  on  his  part.  His  first  duty  is  to  notice  that  the  safety-valve  does  not  emit  steam  exceeding  a 
given  pressure. 

It  is  probably  from  these  explosions  being  so  rare,  that  the  cause  of  them  has  been  a question  up  to 
the  present  time ; we  can  give  none  other  than  that  they  are  owing  to  the  imprudence  of  the  engine- 
drivers,  from  their  endeavors  to  raise  the  power  too  high,  and  thus  impeding  the  escape  at  the  safety- 
valves.  Perhaps  this  imprudence  may  be  combined  with  a bad  system  of  closing  and  bolting  the  iron 
plates,  and  defectiveness  in  the  large  interior  iron  bolts  of  the  front  plate.  We  do  not,  however,  mean 
to  affirm  this,  but  only  mention  it  to  our  readers,  inasmuch  as  we  know  that  the  joinings  and 
arrangement  of  the  plates  of  some  boilers  are  much  less  skilfully  contrived  to  resist  internal  pressure 
than  others. 

One  observation  will  be  sufficient  to  prove  to  mechanics  the  uselessness,  generally  speaking,  of  in- 
creasing the  pressure,  and  of  tightening  the  safety-valves.  When  they  thus  increase  the  pressure  of  the 
steam  in  the  boiler,  the  engine  simply  acquires  the  power  of  propelling  a heavier  train,  but  it  has  not 
any  sensible  effect  upon  the  speed.  They  should,  therefore,  remember  that  they  do  not  derive  any  ad- 
vantage from  committing  this  very  great  offence.  As  the  steam  in  the  cylinders  acts  at  a less  pressure 
than  that  in  the  boiler,  of  what  use  is  it  to  increase  the  latter,  when,  by  opening  the  regulator  a little 
more,  sufficient  additional  strength  is  obtained  in  the  cylinders?  The  most  essential  thing  for  the  speed 
is  the  generation  of  a large  quantity  of  steam  at  once,  and  of  the  requisite  force — sufficient  for  the  dis- 
charge of  a great  number  of  strokes,  and  not  steam  generated  under  a greater  pressure  than  there  is  any 
occasion  for. 

Distribution. — The  steam  entrance,  or  the  aperture  by  which  the  steam  is  introduced  into  the  pipes 
of  distribution,  is  situated  in  the  interior  of  the  boiler,  and  opens  at  the  upper  part  of  the  dome  sur- 
mounting it.  The  object  of  the  dome  is  to  carry  the  steam  as  high  as  possible,  that  the  water  held  in 
suspension  may  have  time  to  drain  from  it.  The  pipe  by  which  the  steam  is  introduced  (steam-pipe)  is 
carried  along  to  the  extremity  of  the  boiler,  and  passed  through  into  the  smoke-box,  where  it  is  divided 
into  two,  to  supply  each  of  the  cylinders.  This  pipe  may  be  contracted  in  the  interior,  by  means  of  an 
apparatus  termed  a regulator,  which  is  inserted  for  the  pur  pose  of  regulating  the  transmission  of  steam 
to  the  cylinders ; this  apparatus  will  also  entirely  close  the  passage  of  the  steam-pipe,  if  required.  The 
steam  entrance  is  placed  either  at  the  head  of  the  boiler,  above  the  fire-box,  or,  otherwise,  towards  the 
extremity  near  the  chimney.  In  the  first  case,  where  the  pipe  traverses  the  entire  length  of  the  boiler, 
it  is  attached  to  the  plates  at  each  extremity ; and,  in  order  that  it  may  readily  yield  to  the  action  oi 
expansion,  it  is  furnished  with  a stuffing-box. 

The  joints  of  that  portion  of  the  steam-pipe  within  the  boiler  should  be  made  with  the  greatest  care, 
that  the  water  may  not  gain  admittance  into  the  pipe.  It  is  generally  formed  with  a section  equal  or 
superior  to  that  of  the  steam-ports  in  the  passage  to  the  cylinders,  and  the  same  as  the  apertures  opened 
and  shut  by  the  regulator. 

Throttle-valves  are  constructed  of  various  forms  ; but  that  generally  employed  consists  of  two  separ- 
ate disks,  one  being  made  movable ; and  they  are  cut  in  such  a manner  that  the  open  parts  of  one  will 
either  correspond  with  or  cross  those  of  the  other,  so  that  the  steam  passage  may  be  left  either  open  or 
closed. 

The  movable  disk  is  secured  to  the  fixed  disk  by  the  pressure  of  the  steam,  also  by  a screw  and  a 
spring.  The  spring  is  rendered  necessary  from  the  steam  within  the  steam-pipe  being  sometimes  of 
greater  pressure  than  that  in  the  boiler. 

Other  forms  of  throttle  have  also  been  employed — and  the  principle  of  safety-valves  lias  been  applied 
in  some  cases,  and  in  others  the  principle  of  cocks — again,  that  of  slides ; those  which  present  the  least 
surface-friction,  and  in  which  the  apparatus  is  brought  into  action  upon  the  least  degree  of  force,  are  the 
best,  for  it  is  important  to  counteract  the  effort  required  to  overcome  the  pressure  of  the  steam  by  suita- 
ble contrivances,  as  by  equilibrating  it  by  a pressure  nearly  equal ; the  friction  resulting  from  the  unequal 
expansion  of  the  several  pieces  fixed  and  inclosed  witliin  each  other  should  also  be  reduced  as  much  as 
possible.  Throttles  formed  with  cylindric  surfaces  exposed  to  the  action  of  friction,  possess  this  incon- 
venience in  the  highest  degree.  There  also  appears  to  be  some  ground  for  rejecting  regulators  which 
require  helixes  in  the  interior  of  the  boiler,  upon  which  the  pressure  of  the  steam  would  act. 

Of  the  cylinders,  slide-boxes,  and  slides. — The  steam  passes  along  the  breeches-piece  leading  to  the 
cylinders  through  the  slide-boxes,  from  whence  it  is  distributed  alternately  upon  each  side  of  the  piston. 

The  mode  of  introducing  the  steam  may  be  readily  comprehended : the  bottom  of  each  slide-box  ia 
pierced  by  three  holes  called  ports ; the  two  extreme  ports  convey  tire  steam  into  the  interior  of  the 
cylinders  at  their  extremities.  A sort  of  cover,  called  a slide,  is  placed  over  them,  which  is  subjected 
to  an  alternating  motion  when  at  work,  and  thus  leaves  each  port  alternately  uncovered ; and  as  the 


LOCOMOTIVE  ENGINE. 


2il 


slide-boxes  are  kept  constantly  filled  with  steam,  the  latter  passes  through  these  ports  into  the  cylin 
ders  at  the  moment  of  each  being  uncovered.  It  will  therefore  be  perceived  that  the  system  of  intro 
ducing  steam  is  very  simple.  The  ejection  of  the  steam  from  the  cylinders  remains  to  be  explained 
every  time  that  steam  enters  upon  one  side  of  the  piston,  that  which  has  effected  the  preceding  half- 
stroke  escapes  at  the  third  port,  which  is  pierced  in  the  bottom  of  the  slide-box,  and  is  not  in  commu- 
nication either  with  the  cylinder  or  the  slide-box,  where  the  steam  is  lodged,  but  is  separated  from  these 
and  is  constantly  covered  with  the  movable  slide,  which  covers  and  uncovers  alternately  the  two  othei 
ports;  it  is  furnished  with  a pipe  at  the  extremity  which  leads  into  the  chimney.  Now,  the  movable 
cover  or  slide  being  hollow,  it  results  from  its  alternate  motion  that  when  it  uncovers  one  of  the  steam- 
ports  and  admits  steam  into  the  cylinder,  it  puts  the  other  steam-port  in  communication  with  the  waste 
steam-port  situated  between  them,  by  means  of  the  cavity  beneath  it ; and  the  steam  admitted  into  tne 
cylinder,  at  the  preceding  half-stroke  of  the  piston,  by  the  port  then  uncovered,  enters  the  interior  of  the 
slide,  forces  itself  through  the  waste  steam-port,  and  thence  escapes ; therefore  the  slide-box  constantly 
answers  as  a passage  to  conduct  the  steam  into  the  cylinders,  and  the  cavity  within  the  slide  serves 
only  for  a passage  to  convey  the  steam  away  from  them.  The  true  steam-ports  admit  steam  when 
they  are  uncovered,  and  they  alternately  convey  steam  to  the  waste  steam-port  when  they  are 
covered  by  the  slide ; thus  the  slide  never  leaves  more  than  one  of  the  steam-ports  uncovered  at  a 
time  for  the  passage  of  the  steam,  and  it  covers  the  other  two  at  the  same  time,  to  allow  of  the  waste 
steam  escaping.  The  force  of  the  steam  lodged  in  the  slide-box  is  therefore  employed  upon  the  piston. 
The  waste  steam,  being  put  in  communication  with  the  atmosphere  under  the  slide,  instantly  loses  its 
force.  The  piston  is  then  quickly  carried  along  to  the  other  end  by  the  force  of  the  steam,  and  the 
resistance  it  encounters  on  the  other  side  is  quickly  overcome.  Now  it  is  the  difference  between  these 
two  forces  which  causes  the  engine  to  perform  its  several  functions ; if  these  forces  were  equal,  the 
piston  would  remain  in  equilibrio,  and  without  motion.  In  order  that  this  difference  shall  be  as  great 
as  possible,  the  force  of  the  steam  entering  the  cylinders  should  not  be  less  than  that  which  exists  in  the 
boiler,  or  the  pressure  of  the  steam  that  passes  out  of  the  cylinders  greater  than  the  pressure  of  the 
atmosphere  into  which  it  escapes;  but  this  desideratum  is  difficult  to  be  attained.  The  pistons  of  loco- 
motive engines  being  impelled  with  great  velocity,  the  steam  is  necessarily  carried  into  the  ports  of  in- 
troduction with  a velocity  which  is  in  inverse  proportion  to  the  section  of  the  uncovered  part  (of  the 
port)  with  the  area  of  the  cylinders.  This  velocity  is  further  affected  by  the  irregularity  attending  the 
conversion  of  a rectilinear  motion  into  a circular  one.  The  latter  is  accomplished  by  means  of  a crank- 
arm,  which  follows  every  movement  regularly,  and  transmits  the  motion  to  a rectilinear  horizontal  rod, 
the  velocity  of  which  is  represented  by  0293  for  the  quarter  of  the  revolution  which  approaches  nearest 
to  the  vertical,  and  by  O'T 07  for  the  quarter  nearest  the  horizontal.  Thus,  the  total  speed  of  the  piston 
is  composed  of  a minimum  and  of  a maximum ; the  minimum  takes  place  when  the  crank-arm  passes 
above  and  below  the  horizon — the  maximum,  wdien  it  performs  the  quarter  of  the  circle  of  the  passage 
from  one  side  to  the  other  of  the  vertical ; in  other  words,  the  more  the  direction  of  the  movement  of  a 
crank-arm  approaches  to  a parallel  with  the  rectilinear  rod  which  it  works,  the  greater  is  the  speed 
transmitted  to  the  rod ; and  the  more  it  moves  from  a parallel,  and  approaches  the  rod  by  a perpen- 
dicular movement,  the  slower  is  the  motion  imparted  to  the  rod. 

When  the  engine  works  at  its  greatest  speed,  or  at  about  38  miles  an  hour,  or  1093  yards  per  minute, 
the  size  of  the  wheels  being  5 feet  3 inches,  and  their  circumference  16  feet  6 inches,  the  number  of 
strokes  of  each  of  the  pistons  is  about  200  per  minute,  and  of  their  movements  400,  the  length  of  eacli 
being  about  1 foot  6 inches,  which  gives  the  piston  a velocity  of  192  yards  per  minute,  or  10  feet  per 
second,  instead  of  about  one  yard,  which  is  the  velocity  given  to  the  pistons  of  stationary  engines.  The 
dimensions  of  the  ports  are  generally  l-10th  the  area  of  the  piston ; the  velocity  of  the  steam  in  the 
ports  would  be  about  100  feet  per  second,  if  they  were  always  entirely  open  when  the  piston  was 
moving,  which  is  not  the  case,  the  aperture  being  only  fully  open  during  the  middle  of  its  course,  and 
at  a point  where  the  piston  has  a speed  once  and  a half  as  fast  as  its  mean  velocity ; the  velocity  of  the 
steam  through  the  ports  would  therefore  be  about  165  feet.  Taking  the  contractions,  also,  into  account, 
reduces  the  openings  to  two-thirds ; we  thus  find  that  the  steam  has  a mean  velocity  of  200  to  250  feet 
per  second  at  the  ports.  This  velocity,  although  very  considerable,  does  not,  however,  produce  the 
injurious  effect  that  was  at  first  imagined.  The  velocity  of  the  waste  steam,  in  passing  into  the  void, 
is  upwards  of  1970  feet  per  second,  and  its  velocity  upon  escaping  into  the  atmosphere  is  about  1400 
feet,  when  the  absolute  pressure  of  the  steam  is  about  two  atmospheres. 

This  velocity  is  more  than  870  feet  for  an  effective  pressure  of  a quarter  of  an  atmosphere,  or  an  ab- 
solute pressure  of  1 at  : 25 ; indeed,  the  generating  pressure  of  a velocity  of  escapement  equal  to  290 
feet  does  not  exceed  l-50th  part  of  the  atmosphere  alone. 

The  resistance  arising  from  the  steam-ports  is,  then,  perfectly  unaffected  at  high  velocities,  but  if  the 
latter  were  even  considerable,  it  would  not  have  a troublesome  effect ; indeed,  with  a speed  of  37  miles 
an  hour,  the  boiler  cannot  furnish  the  cylinders  with  any  other  than  steam  of  reduced  pressure ; there- 
fore, of  what  consequence  is  it  that  this  reduction  should  be  partly  caused  by  the  ports,  instead  of  being 
wholly  effected  by  the  regulator  ? 

Hut  although  we  have  no  loss  of  force  arising  from  the  steam-ports,  this  is  not  the  case  with  the  waste 
steam-ports.  The  force  which  the  steam  exerts  in  its  escape  always  diminishes  the  useful  pressure — ■ 
and  it  is  very  considerable,  since  the  velocity  is  of  necessity  very  great,  in  order  that  the  cylinders  may 
be  instantly  cleared.  It  is,  therefore,  necessary  that  the  velocity  of  250  feet,  although  sufficient  when 
continued  throughout  the  stroke,  should  be  considerably  increased,  in  order  that  it  may  be  enabled  to 
free  one  side  of  the  cylinder  instantly. 

In  the  next  place,  the  steam,  after  passing  out  of  each  of  the  cylinders,  again  unites  in  a pipe,  which 
»s  contracted  at  the  upper  extremity,  and  presents  another  impediment  to  its  passage.  This  peculiarly 
formed  pipe  is  employed  for  the  purpose  of  creating  a draught.  But  the  resistance  which  it  produces 
/s  naturally  detrimental  to  the  moving-power,  which  may  be  accounted  for  as  follows  : Suppose  that, 


248 


LOCOMOTIVE  ENGINE. 


with  a speed  of  39  miles,  the  cylinders  are  filled  with  steam  of  3 at  : 75,  which  is  successively  held  and 
dispersed.  In  calculating  the  volume  of  this  steam,  with  successive  stops,  we  should  find  that  it  is 
nearly  double  that  of  the  cylinder.  Taking  the  total  volume  of  steam  supplied,  having  the  section  ol 
the  blast-pipe,  (whose  conical  shape  does  not  present  much  contraction,)  we  arrive  at  this  result:  that, 
supposing  the  escapement  to  be  incessant,  the  steam  would  have  a mean  velocity  of  820  feet,  corre 
sponding  to  a generating  pressure  of  a quarter  of  an  atmosphere.  This  result  shows  that  this  great 
velocity  of  escape  absorbs  a considerable  portion  of  the  power  of  the  engine  ; and  if  we  remember  that, 
at  these  same  velocities,  the  motive  steam  must  necessarily  diminish  the  pressure,  also  that  the  air  op- 
erates upon  and  at  length  overcomes  it,  we  can  easily  conceive  that  there  are  certain  limits  to  the 
velocity  which  cannot  be  exceeded  with  certain  engines,  even  when  running  without  a load.  These 
limits,  which  were  originally  from  about  39  to  44  miles  an  hour,  have  been  increased,  with  engines  made 
more  recently,  to  nearly  53,  or  even  upwards  of  60  miles  an  hour. 

Eccentrics. — The  two  pistons  are  each  attached  by  fixed  rods,  to  guide  them  in  their  rectilinear 
strokes,  and  by  movable  rods,  called  connecting-rods,  to  an  axle  furnished  with  two  cranks,  set  square 
with  each  other ; this  axle  is  mounted  upon  two  wheels,  which  are  termed  the  driving-wheels,  and  re- 
ceive a rotative  movement  direct  from  the  pistons. 

The  readiest  plan  of  distributing  the  steam,  at  the  commencement  of  the  action  of  the  piston,  consists 
in  employing  the  rotative  motion  of  the  axle  to  conduct  two  eccentrics  at  the  same  time  with  the  wheels, 
which,  by  their  alternating  motion,  open  and  close  the  slides.  The  eccentrics  are  placed  on  the  axles 
of  the  driving-wheels  in  such  a manner  as  to  disengage  the  slides  from  those  ports  whereby  the  steam 
is  introduced  into  the  cylinders,  and  to  cover  those  reserved  for  its  escape,  at  the  commencement  of  the 
stroke  of  the  piston  ; to  accomplish  which,  each  eccentric  is  mounted  upon  the  axle  of  the  wheels  square 
with  the  crank  of  the  cylinder,  the  slide  of  which  it  conducts.  In  order  to  understand  perfectly  what 
then  transpires,  it  is  necessary  to  bear  in  mind  that,  when  a crank  transmits  motion  to  a horizontal  rod. 
it.  impresses  the  rod  with  a rapid  motion  when  it  passes  in  a vertical,  and  with  a slow  one  when  i' 
passes  in  a horizontal  direction. 

In  accordance  with  this  general  law,  when  two  crank-arms  are  mounted  on  the  same  axle,  and  trans- 
mit their  motion  to  two  rectilinear  rods,  the  motion  of  each  will  be  different,  notwithstanding  the  cranks 
are  both  animated  with  the  same  velocity. 

Now,  the  slow  movement  occurs  precisely  at  the  commencement  and  at  the  termination  of  each  half- 
stroke of  the  piston,  since  the  crank-arm  crosses  the  horizontal  at  this  particular  period.  Therefore,  il 
the  eccentric  be  mounted  square  with  the  crank,  the  instant  that  it  crosses  in  a vertical  direction,  and 
transmits  the  greatest  amount  of  velocity  to  the  slide,  the  crank  wall  be  in  a horizontal  position,  and  the 
piston  will  be  taking  its  slowest  movement.  The  steam  is  introduced  and  let  off  uniformly  every  time 
the  crank-arm  is  in  a horizontal’  position — that  is  to  say,  every  time  the  piston  has  finished  one  stroke 
and  is  commencing  another — and  it  is  performed  with  great  precision,  depending  upon  the  uniform  ac- 
tion of  the  slide.  It  may  be  further  observed,  in  the  case  of  one  crank  being  placed  on  the  same  axle 
with  another,  when  one  is  passing  from  one  side  to  the  other,  in  making  a semi-revolution,  the  other  is 
passing  from  the  top  to  the  bottom  ; or  if  each  of  these  cranks  transmits  a rectilinear  motion  to  a rod, 
the  rod  conducted  by  the  first  crank  conveys  a certain  motion  in  one  direction,  and  that  conducted  by 
the  other  conveys  the  same  amount  of  motion,  but  distributed  in  the  opposite  direction.  The  results  of 
this  uniform  principle  in  the  construction  of  locomotive  engines  are  as  follow : At  the  instant  one  of  the 
cranks  is  in  a horizontal  position,  and  the  piston  at  the  commencement  of  its  stroke,  during  the  first  half 
(of  this  stroke)  the  slide  moved  by  the  eccentric,  which  is  in  a vertical  position,  conveys  a motion 
which  has  the  effect  of  uncovering  one  of  the  ports,  and  by  the  time  the  eccentric  arrives  at  the  horizon 
it  becomes  wholly  uncovered.  Jn  the  second  half  of  the  course  of  the  crank,  the  slide  returns  to  its 
original  position,  and  the  port  becomes  again  covered.  The  slide  is,  therefore,  always  ready  to  uncover 
the  opposite  port  at  the  commencement  of  the  following  stroke. 

It  further  results,  when  the  crank  is  horizontal,  that  the  two  steam-ports  are  shut,  the  eccentric  being 
then  in  a vertical  position. 

Such  is  the  principle  of  the  distribution  of  steam.  We  shall  not  enter  into  the  particulars  of  the 
several  plans  for  effecting  it  at  present,  but  their  details,  which  do  not  differ  essentially  from  each  other, 
will  be  found  in  their  proper  place.  The  return  motions,  from  the  eccentrics  to  the  slides,  are  con- 
structed of  slight  rods,  and  are  therefore  readily  shifted ; yet,  as  the  slides  are  drawn  backwards  and 
forwards  under  the  pressure  of  the  steam  they  are  subjected  to  considerable  friction,  the  rods  are  liable 
to  be  strained,  and  frequently  become  deranged  by  the  eccentrics,  also  from  the  play  of  the  points  of 
the  levers,  and  the  several  turning-joints  being  so  very  elastic.  These  circumstances  of  derangement 
have  an  important  influence,  by  retarding  the  slide  slightly,  which  has  a powerful  effect  upon  the  regu- 
larity of  the  distribution ; and  since  the  course  of  the  eccentric  is  similar  to  that  of  the  slide,  the  deten- 
tion of  the  action  and  the  loss  of  speed  occurring  in  the  return  movement  from  the  above  causes,  show 
the  necessity  of  the  engine-nfan  devoting  the  greatest  attention  to  this  point,  and  avoiding  the  evil  as 
much  as  possible.  The  distribution  of  steam  may  be  suspended  whenever  required,  by  means  of  hand- 
geer  and  reversing-handles,  which  detach  the  rods  of  the  eccentrics  from  the  levers  which  conduct  the 
slides ; the  same  levers  are  also  employed  to  reverse  the  movement  of  the  slides  at  the  time  of  running, 
and  in  such  a manner  as  to  render  it  opposite  to  the  direction  the  engine  is  running  in. 

This  reversing  the  distribution  of  the  steam  is  employed  to  stop  the  engine  where  other  means  are 
found  insufficient,  in  which  case  the  steam-ports  on  that  side  where  the  piston  is  returning  become  in- 
stantly uncovered,  and  the  steam  fills  the  whole  cylinder,  and  thus  opposes  the  progress  of  the  piston ; 
the  latter  returns  the  steam  again  to  the  boiler  if  it  should  not  be  arrested.  At  the  same  instant  the 
waste  steam-port  is  covered  by  the  slide,  and  consequently  put  in  communication  with  the  air,  which 
enters  by  the  blast-pipe  and  fills  the  cylinders,  being  drawn  in  by  the  action  of  the  piston.  Tims,  the 
advance  of  the  engine  against  the  steam  has  the  effect  of  conveying  the  air  into  the  boiler,  and  the 
safety-valves  consequently  emit  steam  mixed  with  air. 


LOCOMOTIVE  ENGINE. 


24C 


Of  the  feeding  of  the  boiler. — Having  described  the  means  of  generating  steam,  and  of  distributing 
it  in  the  cylinders,  we  shall  now  consider  those  for  renewing  the  water  in  the  boiler  in  sufficient  quantity, 
as  it  becomes  absorbed  by  the  work  of  the  engine.  There  are  two  pumps  employed  in  effecting  this, 
which  arc  on  the  lift-and-force  principle ; the  pistons  consist  of  plungers,  similar  to  those  employed  in 
ordinary  stationary  engines.  They  transmit  the  water  from  the  tender  to  the  boiler.  One  of  these 
pumps  can  deliver  a volume  of  water  in  the  course  of  about  twenty  minutes  sufficient  to  supply  the 
boiler  for  one  hour’s  run.  The  quantity  of  water  furnished  by  the  pumps  may  be  properly  regulated, 
and  the  delivery  of  the  same  rendered  continuous,  but  the  latter  is  only  accomplished  in  new  engines , 
the  boilers  of  the  other  engines  are  sure  to  be  momentarily  chilled,  either  in  the  operation  of  feeding 
with  water,  or  in  replenishing  the  fire  with  fuel ; but  the  fires  of  new  engines  are  not  so  liable 
to  this. 

Of  the  machinery  and  its  disposal.  We  shall  conclude  our  general  observations  on  locomotive 
engines  by  referring  to  the  disposal  of  the  machinery  connected  with  them.  The  power  of  the  engine 
originates  in  the  cylinders,  the  force  produced  within  them  proceeding  through  the  smoke-box  in  which 
they  are  inclosed.  This  force  or  power  acts  in  two  ways,  dependent  upon  the  steam  being  on  one  side 
or  the  other  of  the  pistons,  and  imparts  to  the  rods  an  effort  of  traction  or  of  pressure  accordingly.  The 
whole  of  this  force  is  exerted  upon  the  cranked  axle,  wherefore  it  becomes  highly  necessary  that  this 
axle  should  be  attached  to  the  cylinder-box  by  very  strong  framing ; the  boiler  is  for  this  purpose  placed 
on  a frame,  with  which  it  is  connected  by  stays  secured  by  strong  bolts.  There  are  many  engines 
which,  after  a few  months’  work,  manifest  a sensible  play,  to  an  experienced  eye,  between  the  cylinder- 
box  and  the  supports  of  connection  between  the  boiler  and  the  frame,  from  this  reason.  The  carriages, 
or  grease-boxes,  which  receive  the  gudgeons  at  the  extremity  of  the  axles,  and  thus  support  the  entire 
weight  of  the  engines,  are  situated  beneath  this  frame,  the  gudgeons  turning  freely  in  them. 

If  these  carriages  were  the  only  points  of  resistance  to  the  cylinders,  it  is  probable  that  not  only  the 
supports  of  the  boiler  on  the  frame  would  soon  give  way,  but  the  axletree,  being  only  secured  at  its 
extremities,  would  also  be  subjected  to  these  vibrations,  and  the  greater  part  of  it  so  powerfully  forced 
in  each  direction,  horizontally,  by  the  cranks,  that  they  would  be  soon  broken.  It  is  to  obviate  this  that 
the  cylinder-box  is  attached  to  the  cranked  axle  by  four,  or  at  least  three  iron  rails.  These  rails  are 
strongly  fastened  to  the  cylinder-box,  and  each  carries  a copper  collar,  in  which  the  cranked  axle  is  in- 
closed. This  collar  is  capable  of  moving  in  a vertical  direction,  whereby  it  is  enabled  to  accommodate 
itself  to  the  play  of  the  springs  and  countersprings,  which  frequently  have  the  effect  of  separating  the 
axletree  from  the  boiler ; but  the  collar  is  always  secured  horizontally,  being  that  in  which  the  cranked 
axle  offers  the  greatest  resistance,  by  means  of  suspended  wedges,  which  operate  similarly  to  keys,  and 
tighten  the  carriages  against  the  axletree.  The  cranked  axle  is  secured  in  this  manner  at  five  or  six 
places  respectively,  and  further  attached  to  the  cylinder-box.  The  attention  of  the  engine-driver  should 
be  directed  to  these  rails  of  attachment,  and  he  should  constantly  notice  that  they  fulfil  their  office 
properly ; and  in  furtherance  of  which  he  should  tighten  them,  by  heightening  the  wedges  as  the  car- 
riage of  the  axletree  becomes  worn. 

The  three  principal  rails  or  cross-pieces  which  we  have  noticed,  are  attached  just  at  their  extremities, 
next  the  axletree,  to  lugs  fastened  to  the  fire-box.  It  is  of  consequence  that  these  joints  should  not  be 
made  too  stiff,  and  that  a little  play  be  allowed  for  their  extension  in  cooling,  for  the  reasons  before 
stated,  viz.,  that  these  rails  are  not  subjected  to  the  same  degree  of  elongation  from  the  effects  of  ex- 
pansion as  the  body  of  the  boiler ; and,  upon  this  occurring,  the  boiler  is  forced  upon  the  rails,  and  the 
joints  connecting  them  with  the  fire-box  consequently  become  deranged,  and  give  passage  to  the  water 
situated  within  the  double  casing  surrounding  the  fire-box. 

We  have  now  to  observe,  that  the  necessity  of  reducing  the  weight  of  locomotive  engines  has  led  to 
the  almost  exclusive  employment  of  iron  in  their  construction,  from  which  it  results  that  the  whole  of 
the  several  pieces  in  friction  against  each  other,  from  the  effects  of  rotative  or  rectilinear  movement  and 
the  sliding  of  one  surface  upon  another,  are  proportionately  weaker  than  those  of  ordinary  stationary 
engines,  the  castings  included,  viz.,  the  axeltrees,  the  beams,  the  connecting-rods,  the  guides,  the  eccen- 
trics, &c.,  and  formed  of  smaller  proportions.  Now,  there  is  a very  important  fact  connected  with 
engines,  viz.,  the  circumstance  that  the  friction  does  not  depend  solely  on  the  pressure,  but  on  the  de- 
gree of  fitness  of  the  metal  to  support  the  pressure  without  alteration.  Thus  when  the  state  of  the 
carriages  becomes  altered,  the  friction  acquires  immense  influence;  the  bodies  become  heated  and 
reduced  from  the  filing,  arising  from  the  grip  they  have  of  each  other ; they  also  sometimes  become 
melted.  The  rubbing  surfaces  are  therefore  kept  constantly  oiled,  to  prevent  any  alteration  taking 
place ; and  this  is  more  especially  necessary  with  locomotive  engines,  as  these  surfaces  are  generally 
reduced  almost  to  the  minimum  limits  commensurate  with  the  amount  of  pressure  which  they  have  to 
support.  The  least  negligence  on  this  point  is  consequently  attended  with  serious  consequences ; the 
first,  from  its  increasing  the  resistance  of  the  engine  considerably,  and  qften  stopping  its  progress ; 
secondly,  from  its  increasing  the  wear  of  the  carriages  ; and,  thirdly,  from  its  causing  the  rupture  of  the 
pieces  in  consequence  of  their  becoming  heated,  and  the  strains  to  which  they  are  subjected.  If  the 
carriages  become  heated  in  the  smallest  degree,  they  are  subjected  to  great  pressure,  and  the  relative 
hardness  of  the  metals  in  contact  is  instantly  changed,  and  the  adherence  between  their  surfaces  in- 
creased, so  that  they  become  full  of  holes  and  impaired,  and  oil  will  never  restore  the  delicate  finish 
which  is  thus  destroyed. 

A constant  attention  to  the  greasing,  therefore,  constitutes  one  of  the  surest  means  of  preservation, 
and  of  insuring  good  work  in  the.  locomotive.  Another  circumstance  no  less  necessary,  is  the  mainte- 
aance  of  the  whole  of  the  several  pieces  in  a condition  as  near  their  original  form  and  mounting  as  pos- 
sible. An  engine  is  composed  of  so  many  pieces,  and  is  subjected  to  such  strong  vibrations  under  the 
influence  oi  shocks,  and  from  the  sudden  and  incessant  strains  that  it  is  subjected  to,  that  it  yields  in  a 
certain  degree  at  its  joinings.  The  engine-driver  should  direct  his  attention  to  the  prevention  of  this 
movement,  and  he  should  not  allow  of  any  more  play  in  the  carriages  than  is  necessary  ; lie  should  re- 


1150 


LOCOMOTIVE  ENGINE. 


place  those  pieces  which  become  worn,  and  tighten  those  mountings  as  they  become  loosened.  Ti  e 
several  joinings  are,  moreover,  disposed  in  such  a manner  as  to  counteract  the  difficulties  connected  with 
• them,  and  exhibited  with  all  the  pieces  thrown  in  friction  with  each  other. 

Respecting  the  frames  of  locomotive  engines,  we  may  remark,  that  the  plan  of  arrangement  has  been 
a subject  of  much  controversy,  whether  they  should  be  placed  on  the  outside  or  on  the  inside  of  the 
wheels.  If  a perfectly  rigid  shaft  were  urged  in  a rotative  direction  by  a rectilinear  force,  it  would 
revolve  with  a degree  of  firmness  proportionate  to  the  distance  its  carriages  were  placed  apart.  If  a 
cranked  axle  be  supported  by  carriages  situated  near  its  centre,  and  impelled  by  forces  acting  ir. 
eontrary  directions,  as  those  transmitted  to  it  from  the  cylinders,  it  would  cease  to  be  perpendicular  to 
the  movement  of  the  pistons,  upon  the  carriages  becoming  the  least  worn,  and  would  form  an  angle 
proportionably  large,  accordingly  as  the  carriages  were  placed  near  the  centre.  The  flanges  surround- 
ing the  wheels  would  therefore  knock  against  the  rails,  and  the  engine  undergo  violent  lateral  move- 
ments from  its  direct  course,  which  would  be  dangerous,  on  account  of  the  gre&t  velocity.  A like  effect 
occurs  when  the  cranks  are  placed  at  the  extremities  of  the  axle,  instead  of  near  the  middle  of  it,  as  in 
the  case  of  engines  having  the  cylinders  placed  on  the  outside.  The  wear  of  the  carriages,  also,  has 
the  effect  of  increasing  the  force  of  the  lateral  movements  considerably. 

Of  locomotives  employed  in  conveying  freight. — It  is  customary,  in  the  conveyance  of  freight,  to 
employ  engines  with  their  driving-wheels  coupled  to  the  fore  ones,  which  is  effected  by  connecting- 
rods  ; in  which  case  the  fore-wheels  are  of  equal  diameter  with  the  driving-wheels.  This  coupling 
possesses  no  other  advantage  than  that  of  increasing  the  power  of  adhesion,  by  allowing  the  fore- 
wheels  to  partake  of  the  weight  carried  by  the  others. 

Of  the  tender. — A sort  of  wagon  is  attached  at  the  extremity  of  a locomotive  engine  when  in 
motion,  which  is  called  a tender,  and  which  is  generally  mounted  on  four  wheels,  and  sometimes  on 
six.  It  contains  water  and  fuel  sufficient  to  feed  the  boiler  and  grate  during  a run  of  about  twenty- 
five  miles  as  a maximum,  and  about  fifteen  miles  as  a minimum.  In  order  to  supply  trips  exceeding 
these  limits,  reservoirs  of  water  and  depots  of  fuel  are  arranged  at  convenient  distances  on  the  line, 
which  enables  them  to  extend  their  run  to  distances  which  are  only  limited  by  the  strength  of  the  en- 
gines. 

The  tender  is  joined  to  the  engine  which  it  accompanies  by  a bolt,  which  is  adjusted  to  fit  into  a 
staple.  This  bolt  should  be  capable  of  resisting  the  entire  power  of  the  engine.  The  reservoir  of 
water  communicates  with  the  engine  by  the  two  pipes  of  the  feed-pumps  ; the  connection  of  the  barrels 
of  the  pumps  is  made  by  means  of  a flexible  pipe,  denominated  hosing,  whose  nature  is  such  that  it 
can  readily  yield  to  all  lateral  and  vertical  movements  of  both  engine  and  tender ; the  movements  are 
inevitable,  for  reasons  before  stated,  from  the  little  stability  of  the  railway,  the  great  velocity  of  the 
engines,  &c.  The  bolt  admits  of  every  movement,  except  that  of  lengthening. 

Tenders  of  good  construction  should  present  an  appearance  of  lightness  combined  with  solidity  ; the 
joints  of  the  iron  plates  composing  the  reservoir  of  water  should  be  well  stopped  ; the  cocks  of  the  sup- 
ply-pipes to  the  pumps  also  require  to  be  made  perfectly  water-tight,  which  is  a condition  they  do  not 
always  fulfil.  The  fuel  in  the  tender  is  placed  upon  a level  with  that  in  the  fire-grate.  The  wheels 
are  wedged  on  the  axletrees  similar  to  those  attached  to  the  engine,  and  the  weight  of  the  tender  is 
suspended  on  springs,  to  remedy  the  abrupt  motion  of  the  water.  There  is  a hook  at  the  back  of  the 
tender,  which  is  attached  to  a powerful  spring,  to  neutralize  the  effects  of  concussion,  and  for  the  pur- 
poses of  traction,  and  it  converts  all  shocks  occasioned  by  the  jerking  of  the  engines,  which  are  some- 
times very  abrupt,  into  pressures  more  or  less  strong  accordingly. 

Explanation  of  the  principles  which  govern  the  power  of  locomotive  engines. — The  power  of  a loco- 
motive engine  is  not  to  be  estimated  alone  by  the  pressure  of  the  steam  in  the  boiler,  and  the  diameter 
and  length  of  stroke  of  the  piston.  In  passing  between  the  boiler  and  the  cylinder,  the  elastic  force  of 
the  steam  is  diminished,  before  it  reaches  the  cylinder,  by  the  smallness  of  the  apertures  of  the  steam- 
pipes,  through  which  it  has  to  pass.  This  difference  is,  likewise,  more  frequently  produced  by  the 
evaporating  power  of  the  engine  not  being  capable  of  keeping  up  a supply  of  steam  to  the  cylinders, 
of  an  elasticity  equal  to  that  in  the  boiler ; and,  therefore,  the  pressure  upon  the  piston  is  less  than 
that  against  the  steam-valve  of  the  boiler;  and  this  diminution  of  the  elasticity  of  the  steam,  in  the 
cylinders,  as  compared  with  that  in  the  boiler,  will,  in  many  cases,  be  in  the  ratio  of  the  increase  of 
velocity  of  the  engine.  Thus,  suppose  an  engine  capable  of  evaporating  a certain  quantity  of  water 
per  hour,  or  converting  it  into  a certain  bulk  or  quantity  of  steam,  of  the  elasticity  indicated  by  the 
valve  on  the  boiler  ; if  this  production  of  steam  is  sufficient  to  supply  as  many  cylinders  full  of  steam, 
of  the  density  of  that  in  the  boiler,  as  shall  be  equal  to  the  number  of  strokes  per  minute  of  the  piston, 
required  to  produce  the  given  velocity  ; then,  the  elasticity  of  the  steam  in  the  cylinder  will  be  the 
same  as  that  in  the  boiler,  except  that  which  is  required  to  force  the  steam  through  the  steam  passages 
with  the  requisite  velocity ; and,  consequently,  the  pressure  on  the  piston  will  be  nearly  the  same  as 
that  in  the  boiler.  But,  if  the  velocity  of  the  engine  is  such,  that  the  number  of  cylinders  full  of  steam- 
required  is  greater  than  the  evaporation  of  the  boiler  can  supply,  at  the  elasticity  marked  by  the  steam 
valve,  then  the  elasticity  in  the  cylinders  is  correspondingly  diminished.  Thus,  suppose  an  engine 
capable  of  evaporating  50  cubic  feet  of  water  into  steam  per  hour,  and  that  the  pressure  on  the  steam 
valve  is  50  pounds  per  square  inch  ; this  will  supply  a given  number  of  cylinders  full  of  steam  of  that 
elasticity.  Suppose  the  resistance  to  the  motion  of  the  piston  be  equal  to  this  pressure  of  the  steam, 
or  equai  to  the  elasticity  of  50  pounds  per  square  inch  of  the  surface  of  the  piston;  then  the  engine 
will  travel  at  that  rate,  which  the  evaporating  power  of  the  engine  will  supply  it  with  the  requisite 
number  of  cylinders  full  of  steam.  But,  suppose,  the  resistance  upon  the  piston  increased  by  a change 
in  the  gradients  of  the  railway,  then  the  velocity  of  the  engine  will  be  diminished,  until  the  evapora- 
ting power  raises  the  elasticity  of  the  steam  in  the  boiler,  so  as  to  counterbalance  the  increased  resist- 
ance of  the  piston,  and  the  engine  will  consequently  move  more  slowly.  On  the  contrary,  if  the 
resistance  be  diminished  by  a change  of  the  gradients  of  the  railway,  then  steam  of  a less  density  will 


LOCOMOTIVE  ENGINE. 


2ol 


be  required,  and,  consequently,  a greater  number  of  cylinders  full  will  be  furnished  by  the  boiler,  and 
the  velocity  of  the  engine  will  be  increased. 

We  see,  therefore,  that  the  only  correct  expression  of  power  of  these  engines,  is  the  evaporating 
power  of  the  boiler,  and  that  the  velocity  with  which  the  engine  will  move,  will  depend  entirely  upon 
the  quantity  of  water  it  can  convert  into  steam  in  a given  time  ; or  the  number  of  cylinders  full  of 
steam,  of  a given  elasticity,  which  the  boiler  can  produce  in  a given  time.  Having  found,  therefore, 
by  experiment,  the  quantity  of  water  which  an  engine,  of  given  dimensions,  can  evaporate  per  hour, 
we  then  find  the  power  which  that  engine  is  capable  of  exerting  upon  the  piston,  and  the  velocity,  or 
number  of  strokes  per  minute,  which  that  evaporation  will  produce,  with  a given  load.  The  volume 
of  steam  which  a cubic  foot  of  water  will  produce,  depends  upon  the  elasticity  ; this  has  been  ascer- 
tained by  various  experimentalists,  and  the  following  Table  will  show  the  result.  The  third  column  is 
the  result  of  Mr.  Pambour's  later  investigations  : 


Relative  volume  of  the  steam  generated  under  different  pressures,  calculated  by  the  proposed  formula. 


Total  pressure 
of  the  steam,  in 
pounds  per  square 
inch. 

Volume  of  the 
steam,  calculated 
by  the  ordinary 
formulae. 

Volume  calcu- 
lated by  the  pro- 
posed formula  for 
high-pressure 
non-conducting 
engines. 

Total  pressure 
of  the  steam,  in 
pounds  per  square 
inch. 

Volume  of  the 
steam,  calculated 
by  the  ordinary 
formulas. 

Volume  calcu- 
lated by  the  pro- 
posed formula  for 
high-pressure 
non-condensing 
engines. 

15 

1669 

“ 

65 

434 

436 

‘20 

1280 

1243 

70 

406 

406 

25 

1042 

1031 

75 

381 

381 

30 

882 

881 

80 

359 

358 

35 

765 

768 

85 

340 

338 

40 

677 

682 

90 

323 

320 

45 

608 

613 

105 

281 

276 

50 

552 

556 

120 

24? 

243 

55 

506 

509 

135 

224 

217 

60 

467 

470 

150 

203 

196 

We  propose  now  to  give  the  formulae  for  calculating  the  powers  and  proportions  of  locomotive  en- 
gines, commencing  with  the  values,  as  ascertained,  of  the  various  causes  of  retardation  in  the  movement 
of  a train  on  a railroad  drawn  by  a locomotive  engine ; and,  combining  these  values,  exhibit  a general 
formula;  for  all  cases  of  the  movement  of  a locomotive,  and  under  all  circumstances. 

1.  Resistance  to  motion  caused  by  the  atmosphere. — The  resistance  against  a body  moving  in  an  indef- 
inite fluid,  at  rest,  is  less  than  the  resistance  experienced  by  the  same  body  placed  at  rest  in  an  indefinite 
fluid  moving  against  it,  which  seems  to  denote  that  a fluid  in  motion  separates  itself  less  easily  than  a 
fluid  at  rest.  The  second  is,  that  a thin  plate  meets  with  a greater  resistance  from  the  air  than  a pris- 
matic body  presenting  in  front  the  same  surface,  and  that  the  resistance  diminishes  according  as  the 
prism  is  longer.  This  circumstance  is  occasioned  thus : The  air  having  glided  over  the  edges  of  a thin 
body,  rushes  immediately  behind  it  with  great  rapidity,  and  carrying  in  its  motion  the  portion  of  fluid 
which  we  have  mentioned  above,  produces  a relative  vacuum  behind  the  opposed  surface.  But  if  the 
moving  body  be  a lengthened  prism,  the  air  in  passing  along  its  sides  loses  a certain  portion  of  its  ac- 
quired velocity,  and,  consequently,  on  reaching  the  hind-face  of  the  prism,  extends  itself  behind  it  with  a 
force  more  and  more  moderated;  whence  results  that  it  produces  there  a partial  vacuum,  or  non- 
pressure, less  considerable  than  in  the  case  of  a simple  surface.  And  as  we  have  seen  that  the  definitive 
resistance  against  a moving  body  is  the  difference  between  the  pressure  of  the  air  in  front  and  the  par- 
tial vacuum  created  behind,  it  follows  that  longer  bodies  definitively  suffer  from  the  air  a less  resistance 
than  bodies  of  inconsiderable  thickness. 

The  experiments  of  M.  Thibault  have  confirmed  those  of  Borda,  on  the  proportionality  of  the  resist- 
ance of  the  air  to  the  square  of  the  velocity,  within  the  limits  of  velocity  that  we  have  to  consider. 
They  have,  moreover,  demonstrated  that  if  two  square  surfaces  be  placed  so  that  one  shall  precisely 
screen  the  other,  and  at  a distance  apart  equal  to  one  of  their  sides,  the  resistance  against  the  screened 
surface  will  be  7-10ths  of  the  resistance  suffered  by  the  surface  in  front.  It  consequently  results  that, 
when  two  surfaces  are  separated  by  a considerable  space  relatively  to  their  extent,  the  resistance  of  the 
air  against  the  second  is  to  be  estimated  nearly  as  if  it  were  isolated  in  the  air ; but  if,  on  the  contrary, 
the  two  surfaces  are  very  near  each  other,  relatively  to  their  extent,  there  is  room  to  think  that  the 
screened  surface  may  be  almost  entirely  protected  against  the  effect  of  the  air,  since  a space  equal  to 
one  side  of  the  surface  would  be  requisite  for  the  air  to  exert  against  it  a resistance  equal  to  two-thirds 
of  the  resistance  against  an  isolated  surface. 

Uniting  the  results,  and  limiting  ourselves  to  the  case  of  a body  moving  in  the  air  at  rest,  we  have, 
to  determine  the  resistance  of  the  air,  the  following  formulas,  in  which  X represents  the  front  surface  of 
a body  traversing  the  air  in  a direction  perpendicular  to  that  surface,  V the  velocity  of  the  motion,  e a 
coefficient  variable  with  the  length  of  the  body,  and,  lastly,  Q the  definitive  resistance  produced  by  the 
air  against  the  body : 

Q ^-0011896  t x V2.  Eesistance  of  the  air  expressed  in  English  pounds,  the  surface  X being  expressed 
in  square  feet,  and  the  velocity  Y in  English  feet  per  second. 

And  in  applying  these  formuke  it  will  be  necessary,  according  to  the  case,  to  give  t ) the  letter  s the 
following  values. 


252 


LOCOMOTIVE  ENGINES. 


For  a thin  surface t = 143 

For  a cube t = 1-17 

For  a prism  of  a length  equal  to  three  times  the  side  of  its  front  surface t = 110 


Of  the  resistance  of  the  air  against  the  wagons,  isolated  or  united  in  trains. — From  what  we  have  just 
seen,  it  will  be  easy  to  estimate  the  resistance  of  the  air  against  a prismatic  body  in  motion,  when  its 
front  surface  and  dimension  in  length  are  known.  But  as  a wagon  does  not  present  a regular  prismatic 
form,  it  becomes  necessary  first  to  consider  how  we  may  find  what  surface  it  really  offers  to  the  shock 
of  the  air. 

The  front  surface  of  a wagon  may  be  directly  measured ; it  consists  of  two  distinct  parts,  the  surface 
of  the  load,  and  that  of  the  wagon  itself.  The  former  of  these  surfaces  necessarily  varies  according  to 
the  nature  of  the  goods  which  form  the  load ; and  the  surface  of  the  wagon,  properly  so  called,  includes 
the  spokes  of  the  wheels,  the  axletrees,  axle-boxes,  springs,  and  hind-wheels  of  the  wagon. 

We  obtain,  as  the  result  of  sufficiently  extended  experiments  for  separate  wagons,  the  value  of  t in 
the  preceding  formulae  to  be  = 1T5. 

As  to  the  trains  of  several  wagons,  we  see  that  for  the  resistance  of  the  wheels,  an  addition  must  be 
made  to  the  transverse  section  of  the  train ; but  as  the  wagons  composing  the  same  train,  though  very 
near  each  other,  are  not  however  in  contact,  it  is  necessary  further  to  seek  upon  what  extent  of  surface 
these  wagons,  thus  united,  still  suffer  the  resistance  of  the  air  during  their  motion. 

From  the  result  of  a number  of  experiments  undertaken  to  determine  this  resistance,  it  was  found 
that  in  order  to  estimate  the  effects  of  the  resistance  of  the  air  against  the  progression  of  a train,  to  take 
as  resisting  surface  that  of  the  wagon  of  greatest  section,  augmented  by  10  square  feet  per  intermediary 
wagon,  and  by  6 square  feet  for  the  first  wagon,  including  of  course  in  this  number  the  engine  itself  and 
its  tender. 

On  railways  of  about  5 feet  width  of  way,  the  surface  of  the  highest  wagon  may,  at  a medium,  be 
reckoned  at  70  to  74  square  feet;  we  may  then  esteem,  in  general,  the  resisting  surface  of  a train  of 
wagons  at  70  square  feet,  plus  as  many  times  10  feet  as  there  are  carriages  in  the  train,  including  the 
engine  and  its  tender. 

If  the  road  has  a wider  way,  or  if  the  carriages  offer  a surface  different  from  that  we  have  just  indi- 
cated, the  carriage  of  greatest  section  must  be  measured,  and  that  measure  used  instead  of  the  number 
70.  If  the  wheels  of  the  wagon  are  more  than  three  feet  in  diameter,  there  will  likewise  be  an  addi- 
tion to  make  to  take  account  of  the  greater  surface  which  they  expose  to  the  shock  of  the  air  during 
the  motion.  This  addition  would  be  about  3 square  feet  per  wagon,  for  wheels  of  5 feet  in  diameter 
instead  of  3.  Finally,  if  the  interval  between  the  wagons,  instead  of  being  as  it  is  at  a medium  on  or- 
dinary railways,  considering  the  different  kinds  of  carriages  and  the  inequalities  of  their  loading,  were 
augmented  by  any  important  quantity,  there  might  also  be  some  addition  to  make  for  the  effect  of  the 
air  against  the  loads  of  the  successive  wagons  ; but  as  our  determination  in  this  respect  gave  something 
less  than  one  square  foot  per  wagon,  and  as  the  interval  between  the  wagons  could  not  be  augmented 
by  any  thing  considerable  without  being  liable  to  inconveniences  in  practice,  we  deem  that  one  square 
foot  per  wagon  may  comprehend  nearly  all  cases. 

• When  the  effective  surface  presented  to  the  shock  of  the  air  shall  be  known  by  the  preceding  calcu- 
lation, it  must  be  substituted  for  the  letter  2 in  the  formulae  given  above,  putting  at  the  same  time 
for  t its  value  suitably  to  the  length  of  the  prism  formed  by  the  train  of  wagons.  According  to  the  va- 
riation of  £ observed  by  Dubuat  for  prisms  of  divers  proportions,  it  will  be  found  that  in  the  case  of  a 
train  of  5 wagons,  we  must  make  £ = 1'07,  and  that  the  case  of  a train  of  25  wagons  would  require 
£ = T04.  In  order  then  not  to  have  to  return  continually  upon  these  considerations  we  will  take  as  a 
medium  t = 1-05,  which  is  suitable  to  a train  of  15  wagons,  and  expressing  at  the  same  time,  in  the 
formula  given  above,  the  velocity  in  miles  per  hour,  we  shall  have,  in  fine,  to  express  the  resistance  of 
the  air  against  a train  of  wagons  in  motion,  the  following  formula : 

Q = -002687  j»’.  Resistance  of  the  air,  in  pounds,  the  effective  surface,  of  the  train  or  the  quantity 
S being  expressed  in  square  feet,  and  the  velocity  of  the  motion  in  miles  per  hour. 

Table  of  the  resistance  of  the  air  against  the  trains. — To  dispense  with  all  calculation  relative  to  the 
resistance  of  the  air,  we  here  subjoin  a table  showing  its  intensity  for  all  velocities  from  5 to  50  miles 
per  hour,  and  for  surfaces  of  from  10  to  100  square  feet.  Were  it  required  to  perform  the  calculation 
for  a velocity  not  contained  in  the  table,  it  would  evidently  suffice  to  seek  the  resistance  corresponding 
to  half  that  velocity  and  to  multiply  the  resistance  found  by  4;  or,  on  the  contrary,  to  seek  the  resist- 
ance corresponding  to  the  double  of  the  given  velocity,  and  to  take  a quarter  of  the  result.  So  the 
resistance  of  the  air  against  a surface  of  100  square  feet,  at  the  velocity  of  50  miles  per  hour,  is  equal 
to  four  times  the  resistance  of  the  air  against  the  same  surface  at  the  velocity  of  25  miles  per  hour. 
As  to  surfaces  greater  than  100  square  feet,  they  must  be  decomposed  into  surfaces  less  than  100  feet, 
and  then  the  table  will  still  give  the  results  required ; for  the  resistance  against  a surface  of  120  square 
feet  is  evidently  nothing  more  than  the  sum  of  the  resistances  against  one  surface  of  100  square  feet  and 
one  of  20  square  feet. 

By  means  of  the  table  in  question  will  be  obtained,  without  calculation,  the  resistance  of  the  air  ex- 
pressed in  pounds,  for  any  velocity  of  the  moving  body ; but  it  is  to  be  observed  that  the  table  supposes 
the  atmosphere  at  perfect  rest.  If,  then,  there  be  a wind  of  some  intensity  favorable  to  the  motion,  or 
contrary  to  it,  account  must  be  taken  thereof.  In  order  to  effect  this,  it  will  suffice  to  observe  that  if 
the  wind  is  favorable,  the  body  will  move  through  the  air  only  with  a velocity  equal  to  the  difference 
between  its  own  absolute  velocity  and  that  of  the  wind ; and  that  if  on  the  contrary  the  wind  is  opjiosed 
to  the  motion,  the  effective  velocity  of  the  body  through  the  air  will  be  equal  to  the  sum  of  its  own  ve- 
locity augmented  by  that  of  the  wind.  In  this  case,  then,  the  velocity  of  the  wind  must  first  be  meas- 
ured, by  abandoning  a light  body  to  its  action,  and  noting  the  time  in  which  it  traverses  a space  pre- 
viously measured  on  the  ground;  or  else  an  anemometer  may  be  used  for  the  purpose.  Then  tha 


LOCOMOTIVE  ENGINE. 


velocity  of  the  wind  must  be  subtracted  from  that  of  the  train  in  motion  or  added  to  it,  according  to  the 
ease ; and  that  difference  or  that  sum  is  the  velocity  to  be  sought  in  the  table,  or  substituted  in  the 
formula,  to  obtain  the  corresponding  resistance  against  the  whole  train. 

If  the  wind,  instead  of  being  precisely  contrary  or  favorable  to  the  motion,  should  exert  its  action  in 
an  oblique  direction,  it  would  tend  to  displace  all  the  wagons  laterally ; and  consequently,  from  the 
conical  form  of  the  wheels,  all  those  on  the  further  side  from  the  wind  would  turn  on  a larger  diameter 
than  those  on  the  side  towards  the  wind.  The  resistance  produced  will  therefore  be  the  same  as  that 
which  would  take  place  on  a curve  on  which  the  effect  of  the  centrifugal  force  were  not  corrected,  and 
tliat  resistance  would  necessarily  be  very  considerable. 


Practical  Table  of  the  resistance  of  the  air  against  the  trains. 


Velocity  of  mo- 
tion in  miles  per 
hour. 

Resistance  of  the 
air  in  pounds  per 
square  foot  of 
surface. 

Resistance  of  the  air  in  pounds;  the  effective  surface  of  the  train, 
in  square  feet,  being: 

20 

30 

40 

50 

60 

70 

80 

90 

100 

Miles. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

5 

•07 

i 

2 

i, 

3 

4 

5 

5 

6 

7 

6 

TO 

2 

3 

4 

5 

6 

7 

8 

9 

10 

7 

T3 

3 

4 

5 

7 

8 

9 

11 

12 

13 

8 

•17 

3 

5 

7 

9 

10 

12 

14 

15 

17 

9 

*22 

4 

7 

9 

11 

13 

15 

17 

20 

22 

10 

•27 

5 

8 

11 

13 

16 

19 

22 

24 

27 

11 

•33 

7 

10 

13 

16 

20 

23 

26 

29 

33 

12 

•39 

8 

12 

15 

19 

23 

27 

31 

35 

39 

13 

*45 

9 

14 

18 

23 

27 

32 

36 

41 

45 

14 

•53 

11 

16 

21 

26 

32 

37 

42 

47 

53 

15 

■60 

12 

18 

24 

30 

36 

42 

48 

54 

60 

ie 

•69 

14 

21 

28 

34 

41 

48 

55 

62 

69 

17 

•78 

16 

23 

31 

39 

47 

54 

62 

70 

78 

18 

■87 

17 

26 

35 

44 

62 

61 

70 

78 

87 

19 

•97 

19 

29 

39 

49 

58 

68 

78 

87 

97 

20 

1-07 

22 

32 

43 

54 

65 

75 

86 

97 

107 

21 

1T9 

24 

36 

47 

59 

71 

83 

95 

107 

119 

22 

1-30 

26 

39 

52 

65 

78 

91 

104 

117 

130 

23 

1-42 

28 

43 

57 

71 

85 

100 

114 

128 

142 

24 

T55 

31 

47 

62 

78 

93 

109 

124 

140 

155 

25 

1-68 

34 

50 

67 

84 

101 

118 

134 

151 

168 

26 

1-82 

36 

55 

73 

91 

109 

127 

146 

164 

182 

27 

1-96 

39 

59 

78 

9S 

118 

137 

157 

176 

196 

28 

2T1 

42 

63 

84 

106 

127 

148 

169 

190 

211 

29 

2-26 

45 

68 

90 

113 

136 

158 

181 

203 

226 

30 

242 

48 

73 

97 

121 

145 

169 

194 

218 

242 

31 

2-58 

52 

77 

103 

129 

155 

181 

206 

232 

258 

32 

2 75 

55 

83 

110 

138 

165 

193 

220 

248 

275 

33 

2-93 

59 

88 

117 

147 

176 

205 

234 

264 

293 

34 

3T1 

62 

93 

124 

156 

187 

218 

249 

280 

311 

35 

3-29 

66 

99 

132 

165 

197 

230 

263 

296 

329 

36 

3-48 

70 

104 

139 

174 

209 

244 

278 

313 

348 

37 

3'68 

74 

110 

147 

184 

221 

258 

294 

331 

368 

38 

3-88 

78 

116 

155 

194 

233 

272 

310 

349 

388 

39 

4-09 

82 

123 

164 

205 

245 

287 

327 

368 

409 

40 

4-30 

86 

129 

172 

215. 

258 

301 

344 

387 

430 

41 

4’52 

90 

136 

181 

226 

271 

316 

362 

407 

452 

42 

4-74 

95 

142 

190 

237 

284 

332 

379 

427 

474 

43 

497 

99 

149 

199 

249 

298 

348 

398 

447 

497 

44 

5-20 

104 

156 

208 

260 

312 

364 

416 

468 

520 

45 

544 

109 

163 

218 

272 

326 

3S1 

435 

489 

544 

46 

569 

114 

171 

228 

285 

341 

398 

455 

512 

669 

47 

594 

119 

178 

238 

297 

356 

416 

475 

535 

594 

48 

6T9 

124 

186 

248 

310 

371 

433 

495 

557 

619 

49 

6 45 

129 

194 

258 

323 

387 

452 

516 

581 

645 

50 

6-72 

134 

202 

269 

336 

403 

470 

538 

605 

672 

Of  the  friction  of  the  cars  of  a train- — From  experiments,  the  mean  friction  of  the  cars  taken  inde- 
pendently of  the  resistance  of  the  air,  amounts  to  of  their  gross  weight,  or  to  5’76  pounds  per  ton ; 
but  to  simplify  the  calculations  we  will  take  it  at  6 pounds  per  ton,  which  makes  Tl^  of  the  weight  ol 
the  cars. 

These  are  the  results  which  ought  to  be  rised  when,  for  the  resistance  of  the  air,  the  determination 
deduced  from  the  most  recent  and  most  exact  experiments  on  the  subject  is  used,  and  when  account  is 


254 


LOCOMOTIVE  ENGINE. 


taken,  as  it  ought  to  be,  of  the  length  of  the  prism  formed  by  the  train  in  motion,  as  well  as  of  the 
effects  of  the  air  against  the  rotation  of  the  wheels  and  the  accessory  parts  of  the  wagons. 

It  appears  from  this  result  that  for  the  mean  velocity  of  trains  it  would  be  indifferent  to  compute  the 
friction  of  the  cars  at  5'7 6 pounds  per  ton,  taking  account  of  the  real  resistance  of  the  air  and  of  its 
effects  against  the  accessory  parts  noticed  above,  or  to  take  the  friction  of  the  wagons  at  7 pounds  per 
ton,  accounting  merely  for  the  resistance  of  the  air  against  the  wagon  of  greatest  section.  On  the  other 
hand,  as  during  the  work  of  the  engines  their  velocity  is  so  much  the  greater  as  the  train  they  draw  is 
less  considerable,  whence  the  resistance  of  the  air  increases  as  the  friction  of  the  train  diminishes,  it  will 
be  found  that  either  of  the  two  preceding  calculations  leads  to  very  nearly  the  same  result,  for  the  total 
resistance  opposed  by  the  moving  train,  and  that  it  is  only  in  cases  of  extreme  velocity  that  the  two 
modes  of  calculation  present  a notable  difference. 

Without  any  important  error,  the  second  of  the  two  modes  of  calculation  may  be  used  ; but  the  first 
is  introduced  with  a view  to  the  exhibition  of  a general  formula. 

It  should  be  premised  that  the  valuation  of  the  friction,  which  we  obtained  above,  ought  to  be  under- 
stood only  of  carriages  similar  to  those  which  were  submitted  to  experiment,  and  subject  to  like  condi- 
tions, viz.,  with  iron  axles,  turning  on  brass  chairs,  and  provided  with  self-acting  grease-boxes ; with  three- 
feet  wheels  and  axle-bearings  If  inches;  with  the  use  of  a well-kept  railway,  and  finally  with  the 
'.csual  proportions  of  about  | between  the  weight  of  the  body  of  the  loaded  carriage  and  the  total  weight 
of  the  wagon.  Were  these  conditions  materially  altered,  a new  determination  of  the  friction  would  be- 
come necessary. 

Of  gravity  on  inclined  planes. — We  have  seen  how  the  resistance  caused  on  a railway  by  the  friction 
of  the  wagons  may  be  valued.  But  it  sometimes  happens  that  this  friction  is  the  smallest  part  of  the 
total  resistance  which  the  engine  has  to  overcome,  in  order  to  effect  the  motion  of  the  train.  This  case 
occurs  when  the  way  is  not  level,  and  the  train  is  obliged  to  ascend  an  acclivity.  The  resistance  then 
caused  is,  as  every  one  knows,  much  greater  than  on  a level  line,  and  in  consequence  it  becomes  neces- 
sary to  take  account  of  it  in  the  calculations. 

When  a body  is  placed  on  an  inclined  plane,  the  weight  vhich  urges  it,  and  which  always  acts  in  a 
vertical  line,  is  decomposed  into  two  forces ; one  perpendicular  to  the  plane,  and  which  measures  the 
pressure  produced  against  the  plane,  by  virtue  of  the  weight  of  the  moving  body,  and  the  other  parallel 
to  the  plane,  and  which  tends  to  make  the  body  slide  or  roll  along  the  declivity.  The  latter  force,  which 
we  will  call  the  gravity  along  the  plane,  would  inevitably  drag  the  body  towards  the  foot  of  the  declivity, 
were  it  not  counteracted  by  a contrary  force.  When  therefore  a train  of  wagons  has  to  ascend  an  in- 
clined plane,  the  moving  power  must  apply  to  it : firstly,  a force  able  to  overcome  the  friction  of  the 
wagons  themselves  ; and  again,  another  force  able  to  overcome  the  gravity  in  the  direction  of  the  plane. 
If,  on  the  contrary,  the  mover  draw  the  train  of  wagons  down  the  plane,  then,  in  order  to  produce  the 
motion,  it  will  evidently  have  to  apply  only  a force  equal  to  the  difference  between  the  friction  proper 
to  the  wagons  and  the  gravity,  since  the  latter  force  then  acts  in  the  same  direction  as  the  mover. 

When  a body  of  a given  weight  is  set  on  a plane  of  a given  inclination,  we  know  that,  in  order  to  ob- 
tain the  gravity  of  the  body  along  the  plane,  its  weight  is  to  be  multiplied  by  the  fraction  which  ex- 
presses practically  the  inclination  of  the  plane.  Thus,  for  instance,  on  a plane  inclined  fg,  that  is  to  say, 
on  a plane  which  rises  1 foot  on  a length  of  89  feet  measured  along  the  acclivity,  the  gravity  of  1 ton, 
or  2240  lbs.,  is 

2240 

= 25-2  lbs. 

89 

Moreover,  when  a train  of  wagons  ascends  an  acclivity,  the  engine  has  not  only  to  surmount  the  grav- 
ity of  the  wagons  of  the  train,  but  likewise  its  own  gravity  and  that  of  the  tender  which  follows  it ; and 
these  forces  do  not  present  themselves  when  the  motion  takes  place  on  a horizontal  line.  It  is  then  on 
the  total  weight  of  the  train,  that  is,  including  engine  and  tender,  that  the  resistance  caused  by  gravity 
on  acclivities  is  to  be  calculated. 

If  it  be  supposed,  for  instance,  that  a train  of  40  tons,  tender  included,  be  drawn  up  a plane  inclined 
■gL,  by  an  engine  weighing  10  tons,  it  is  clear  that  the  definitive  resistance  opposed  to  the  motion  by  the 


train  will  be 

40  X 6 lbs.  = 240  lbs.,  friction  of  the  carriages  at  6 lbs.  per  ton 240  lbs. 

50  X -2.||-  = 1258  lbs.,  gravity  of  the  50  tons  of  the  train  (reduced  to  lbs.)  on  a plane 

inclined  fg,  to  be  added 1258 

Total  resistance  arising  from  friction  and  gravity  1498  lbs. 


If,  on  the  contrary,  the  same  train  had  to  descend  a plane  inclined  j-TVo>  the  resistance  it  would  then 
offer  would  be 


40  X 6 lbs.  - 240  lbs.,  friction  of  the  wagons 240  lbs. 

50  X ffjyg  = 112  lbs.,  gravity  of  the  train  to  be  deducted 112 

Definitive  resistance  arising  from  friction  and  gravity 128  lbs. 


In  general,  let  M be  the  weight  of  the  train,  in  tons  gross  and  including  the  tender ; let  m be  the 
weight  of  the  engine,  expressed  also  in  tons  ; k the  friction  of  the  wagons  per  ton,  expressed  in  lbs.,  as 
has  been  explained  ; finally,  let  g be  the  gravity,  in  lbs.,  of  1 ton  on  the  plane  in  question.  It  is  clear 
in  the  first  place,  from  what  has  been  said  above,  that  the  quantity  g will  be  equal  to  2240,  multiplied 

by  the  practical  inclination  of  the  plane  ; so  that  if  — express  that  inclination,  or  the  ratio  of  the  height 

of  the  plane  to  its  length,  we  shall  have,  to  determine  y,  the  equation 

2240 


LOCOMOTIVE  ENGINE. 


25  £ 


This  premised,  the  friction  of  the  wagons  will  have  for  its  value  k M.  Again,  since  g expresses  tho 
gravity  of  1 ton,  it  is  plain  that  g (M  -+-  in)  will  represent,  in  lbs.,  the  gravity  of  the  total  mass,  train 
and  engine,  placed  on  the  inclined  plane. 

Thus,  according  as  the  motion  takes  place  in  ascending  or  in  descending,  the  total  resistance,  in  lbs., 
offered  by  the  train  on  the  inclined  plane,  will  be 

k M + g (M  -f-  in)  — (k  + g)  M + g in, 

an  expression  in  which  the  sign  + belongs  to  the  ascending  motion,  and  the  sign  — to  the  descending 
motion  of  the  train. 

It  will  always  be  easy  then  to  obtain  the  number  of  lbs.,  which  represents  the  resistance  opposed  by 
a train  in  motion  on  a plane  of  a given  inclination. 

Of  the  effects  of  the  blast-pipe. — We  have  just  examined  several  of  the  resistances  which  are  opposed 
to  the  engine  in  its  motion,  viz.,  that  of  the  wagons  along  the  rails,  and  that  of  the  air  against  the  trains. 
But  among  other  resistances  which  the  piston  has  yet  to  overcome,  is  one  arising  from  the  disposition 
of  the  engine  itself,  and  of  which  it  will  be  proper  to  treat  before  proceeding  further. 

The  steam,  after  having  exerted  its  action  in  the  cylinder,  might  escape  into  the  atmosphere  by  a 
large  opening.  It  would  then  be  possible  for  it  entirely  to  dissipate  itself  in  the  air,  during  the  time  the 
piston  takes  to  change  its  direction.  Consequently  the  steam  would  in  nowise  impede  the  retrograde 
motion  of  the  piston,  whatever  might  be  the  velocity  of  the  piston.  But  the  disposition  adopted  is  con- 
trary to  this.  The  steam,  on  leaving  the  cylinder,  has  no  other  issue  towards  the  atmosphere  than  an 
aperture  exceedingly  narrow ; nor  can  it,  by  that  aperture,  escape  totally  within  the  time  of  one  stroke, 
except  by  assuming  a very  considerable  velocity  in  its  motion.  For  this,  the  steam  in  the  cylinder  must 
necessarily  be  at  a pressure  sensibly  greater  than  that  of  the  atmosphere  into  which  it  flows ; and  as 
the  pressure  of  the  steam  while  flowing  acts  in  all  directions,  and  consequently  against  the  piston,  it 
results  that  the  latter,  instead  of  having  simply  to  counteract  the  atmospheric  pressure,  finds  an  addi- 
tional one  to  overcome,  which  is  to  be  added  to  the  divers  resistances  already  measured. 

This  new  cause  of  resistance  might,  as  has  been  said,  be  in  a great  measure  suppressed,  by  enlarging 
sufficiently  the  outlet  of  the  steam.  But  to  do  this  would  be  to  lose  one  of  the  most  active  causes  of 
the  definitive  effect  of  the  engine  ; for  the  object  of  the  disposition  of  which  we  treat  is  to  excite  the  fire 
sufficiently,  and  to  produce,  in  a boiler  of  small  dimensions,  the  very  great  quantity  of  steam  requisite 
for  the  rapid  motion  of  the  engine.  To  this  end,  the  waste  steam  is  conducted  to  the  chimney,  and 
thrown  into  it  by  intermittent  jets,  through  a blast-pipe  or  contracted  tube,  placed  in  the  centre  of  the 
chimney  and  directed  upwards.  The  jet  of  steam,  as  it  rushes  with  force  from  this  aperture,  rapidly 
expels  the  gases  which  occupied  the  chimney.  It  consequently  leaves  behind  it  a vacuum  ; and  this  is 
immediately  filled  by  a mass  of  air  rushing  through  the  fire-grate  into  the  space  where  the  vacuum  has 
been  made.  At  every  aspiration  thus  produced,  the  fuel  contained  in  the  fire-box  grows  white  with 
incandescence.  The  effect  then  is  similar  to  that  of  a bellows  continually  urging  the  fire  ; and  the  arti- 
ficial current  created  in  the  fire-box  by  this  means  is  of  such  efficacy  for  the  vaporization,  that  were  the 
blast-pipe  suppressed,  the  engine  would  become  almost  useless,  which  proves  that  the  current  of  air 
attributable  to  the  ordinary  draught  of  the  chimney  is  in  comparison  but  very  trifling. 

Omitting  the  experiments  and  calculations  from  which  it  is  derived,  we  obtain  as  the  value  of  the 
resistance  against  the  piston  caused  by  the  action  of  the  blast-pipe,  the  formula 

S' 

•0113  v — ; 
o 

in  which  v is  the  velocity  of  the  engine  in  miles  per  hour : S'  the  total  vaporization  of  the  boiler  in  cubic 
feet  of  water  per  hour  ; o the  area  of  the  orifice  of  the  blast-pipe  expressed  in  square  inches  ; and  the 
result  of  the  calculation  will  give  the  pressure  in  the  blast-pipe  expressed  in  pounds  per  square  inch. 
The  pressure  per  square  foot  will  be  144  times  as  much. 

With  respect  to  the  quantity  represented  here  by  S',  the  experiment  from  which  we  deduced  the 
formula  shows,  that  the  vaporization  signified  is  tne  total  vaporization  effected  in  the  boiler,  that  is  to 
say,  the  vaporization  counted  before  deduction  of  the  water  carried  away  in  a liquid  state  with  the  steam. 

Making  in  the  preceding  formula 

•0113  S =r/, 
o 


the  pressure  in  the  blast-pipe  may  be  represented  by  the  expression  p'  v,  m which  p'  will  be  the  ratio 
of  the  vaporization  to  the  orifice  of  the  blast-pipe,  multiplied  by  a constant  coefficient. 

Now,  for  engines  which  vaporize  as  much  as  60  cubic  feet  of  water  per  hour,  practice  has  established 
the  use  of  a blast-pipe  of  2'23  inches  diameter,  or  3’96  square  inches  of  area,  which  gives  for  the  value 


of  the  ratio 


60 

3'96 


= 15-2. 


In  constructing  engines  of  a greater  vaporizing  power,  it  would  be  natural  to  increase  the  area  of  the 
blast-pipe  in  proportion  to  the  quantity  of  steam  to  which  it  is  to  give  issue.  There  is  room  therefore 
to  think  that  the  proportion  thus  established  between  the  production  of  steam  and  the  area  of  the  blast- 
s' 

pipe,  will  not  be  notably  changed  by  the  different  engine-makers.  Consequently  the  ratio  — may  be 

regarded  approximatively  as  a constant  quantity,  given  by  the  above  proportion. 

Then  the  preceding  formula  will  be  reduced  simply  to  the  expression  T75  v,  which  will  be 
useful  especially  in  valuing  the  pressure  due  to  the  blast-pipe  in  engines  whose  vaporization  is 


‘256 


LOCOMOTIVE  ENGINE. 


unknown.  In  this  formula,  v is  the  velocity  of  the  engine,  in  miles  per  hour,  and  the  result  is  the 
pressure  in  the  blast-pipe,  expressed  in  pounds  per  square  inch.  As  the  pressure  per  square  foot  is  144 
times  as  much,  it  follows  that  if  we  require  the  pressure  expressed  in  that  manner,  we  shall  obtain  its 
value  by  the  formula  25'2  v. 

We  shall  then  represent  generally  the  pressure  in  the  blast  pipe  under  the  form  p'  v\  and  for 
the  most  ordinary  cases,  it  will  suffice  to  give  to  p‘,  in  this  expression,  one  of  the  constant  values 
above  mentioned,  according  to  the  measures  employed.  But  if  the  engine  in  question  should  differ  too 
considerably  from  the  proportions  which  we  have  just  indicated  with  reference  to  the  area  of  the  blast- 
pipe,  it  would  be  necessary  to  substitute  for  that  approximate  value  of  pi’,  its  value  function  of  S'  and  o. 

In  line,  to  dispense  with  all  calculation  on  this  head,  we  here  subjoin  a table,  in  which  will  be  found, 
on  inspection,  the  pressures  in  the  blast-pipe  for  given  circumstances,  and  we  continue  that  table  beyond 
the  actual  effects  of  locomotive  engines.  It  will  there  be  recognized  how,  by  augmenting  the  orifice  of 
the  blast-pipe,  the  resistance  against  the  piston,  arising  from  that  cause,  may  be  diminished  at  pleasure  ; 
and  it  may  probably  be  found,  in  consequence,  that  in  the  regular  work  of  locomotives,  it  might  be  use- 
ful to  adopt  a blast-pipe  with  a variable  orifice,  such  as  was  employed  temporarily  in  the  experiments 
from  which  these  values  were  deduced.  Then,  by  contracting  the  orifice  of  efflux  of  the  steam  only 
just  as  much  as  is  necessary,  there  will  be  no  more  resistance  against  the  piston  than  what  is  indispen- 
sable for  the  proper  action  of  the  engine. 


Practical  Table  of  the  pressures  against  the  piston,  due  to  the  action  of  the  blast-pipe. 


Diumeter  of 
the  blast-pipe. 

Velocity 
of  the 
engine,  in 
miles  per 
hour. 

Effective  pressure  against  the  piston,  in  lbs.  per  square  inch,  the  vaporization 
of  the  boiler,  in  cubic  feet  of  water  per  hour,  being: 

30 

40 

50 

00 

70 

80 

90 

100 

miles. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

2 inches. 

5 

0*5 

0-7 

0-9 

11 

1-3 

„ 

10 

IT 

1-4 

1-8 

2*2 

2'5 

>» 

15 

1-G 

2*2 

2-7 

32 

3-8 

„ 

20 

2*2 

2-9 

3-6 

4-3 

5*0 

f} 

* 

25 

2-7 

3-6 

45 

51 

6'3 

» 

30 

3-2 

4-3 

51 

65 

7-6 

}} 

v 

35 

3-8 

5-0 

63 

7-0 

8-8 

n 

40 

4-3 

5-8 

7-2 

8-6 

101 

’< 

„ 

» 

2 1 inches. 

5 

OT 

0'6 

0-7 

0-9 

1-0 

1-1 

V 

10 

0'9 

IT 

11 

1-7 

2-0 

2-3 

15 

1-3 

1-7 

21 

2-6 

30 

31 

20 

1-7 

23 

2-8 

31 

4-0 

4-5 

25 

21 

2-8 

3-G 

4 3 

50 

5-7 

JJ 

30 

2-6 

3T 

4-3 

5*1 

G'O 

6-8 

35 

3-0 

4-0 

5-0 

6-0 

7-0 

80 

40 

31 

4 5 

5-7 

6’8 

8-0 

91 

- 

» 

2A  inches. 

5 

0 3 

0-5 

06 

0-7 

0-8 

09 

1-0 

?> 

10 

0'7 

09 

1-2 

11 

1-6 

1-8 

2-1 

»» 

15 

1-0 

1-4 

1-7 

21 

21 

2-S 

31 

20 

1-4 

1-8 

2-3 

2-8 

3-2 

37 

4-1 

25 

1-7 

2-3 

2'9 

3-5 

4-0 

4*6 

5-2 

„ 

80 

21 

2-8 

35 

41 

4-8 

5*5 

6-2 

35 

21 

3-2 

4-0 

4-8 

56 

61 

7-3 

»> 

40 

2-8 

3-7 

4-6 

5*5 

6-4 

71 

8-3 

>> 

45 

3 1 

41 

5-2 

6-2 

7-3 

8-3 

9-3 

y> 

50 

3-5 

4-tl 

5-8 

6*9 

81 

92 

101 

n 

2J  inches. 

5 

0-3 

01 

0 5 

0-6 

0-7 

0-8 

0-9 

1-0 

10 

0'6 

0-8 

1-0 

11 

1-3 

1*5 

1-7 

1-9 

15 

0-9 

11 

11 

1-7 

2-0 

2-3 

2-6 

2-9 

20 

11 

1-5 

1-9 

23 

2-7 

3-0 

31 

3-8 

25 

1-4 

1-9 

2-4 

29 

33 

3-8 

4-3 

4-8 

30 

1-7 

2-3 

29 

31 

4-0 

4-6 

5-1 

5-7 

35 

2-0 

2-7 

33 

4-0 

4-7 

53 

60 

6-7 

40 

2-3 

3-0 

3-8 

4-6 

53 

61 

68 

7-6 

45 

2-6 

34 

4-3 

51 

6-0 

68 

7-7 

8 6 

50 

2-9 

38 

48 

57 

6-7 

7'6 

8'6 

95 

LOCOMOTIVE  ENGINE. 


257 


1 

Jiameter  of 
the  blast-pipe. 

Velocity 
of  the 
engine,  in 
miles  per 
hour. 

Effective  pressure  against  the  piston,  in  lbs.  per  square  inch,  the  vaporization 
of  ttie  boiler,  in  cubic  feet  of  water  per  hour,  being: 

30 

40 

50 

60 

TO 

80 

90 

100 

miles. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

lbs. 

3 inches. 

5 

0'2 

0-3 

0'4 

0-5 

0-6 

0-6 

0-7 

0-8 

10 

0'5 

0-6 

0-8 

1-0 

IT 

1-3 

14 

1-6 

15 

0-7 

1-0 

1-2 

1-4 

1-7 

1-9 

2-2 

24 

20 

10 

1-3 

1-6 

1-9 

2-2 

2-6 

29 

32 

25 

1'2 

1-6 

2-0 

2-4 

2-8 

3-2 

36 

40 

30 

1-4 

1'9 

2-4 

2-9 

34 

3-8 

4 3 

4-8 

35 

1-7 

2'2 

2-8 

3-4 

3-9 

4-5 

5-0 

66 

40 

1-9 

26 

3-2 

3-8 

4-5 

51 

6-8 

64 

45 

2'2 

2-9 

3-6 

4'3 

5 0 

5-8 

65 

7-2 

60 

2-4 

82 

4-0 

4-8 

5-0 

64 

7-2 

8-0 

55 

2-6 

3-5 

4-4 

5-3 

62 

7-0 

7-9 

8-8 

60 

29 

3-8 

4-8 

5-8 

6-7 

7-7 

86 

96 

3J  inches. 

5 

0-2 

0-3 

0-3 

0-4 

05 

0-5 

0'6 

0-7 

10 

0-4 

05 

0'7 

0-8 

1-0 

IT 

1-2 

14 

15 

06 

08 

10 

1-2 

14 

1-6 

1-8 

20 

20 

0-8 

IT 

1-4 

1-6 

1-9 

22 

24 

2-7 

25 

1-0 

1-4 

1-7 

2T 

24 

2-7 

8T 

34 

30 

1-2 

1-6 

2-0 

2-5 

29 

33 

37 

44 

35 

1-4 

1-9 

24 

2-9 

3-3 

3'8 

4-3 

4-8 

40 

1-6 

2-2 

2-7 

3 3 

38 

44 

4-9 

64 

45 

1-8 

2-4 

3T 

3-7 

4-3 

4-9 

55 

6T 

50 

2-0 

2-7 

3-4 

4T 

4-8 

54 

64 

6-8 

55 

2-2 

3-0 

3-7 

4-5 

62 

60 

6-7 

7'5 

60 

2-4 

3-2 

4-1 

4-9 

5-7 

65 

7-3 

8'2 

3-J-  inches. 

5 

0-2 

0-2 

03 

0-4 

04 

0-5 

05 

06 

10 

0-4 

0*5 

0-6 

0-7 

0-8 

0-9 

IT 

1-2 

15 

05 

0-7 

0'9 

IT 

1-2 

14 

1-6 

1-8 

20 

0-7 

0-9 

1-2 

1-4 

1-6 

1-9 

2T 

23 

25 

0-9 

1-2 

1-5 

1-8 

2T 

24 

2-7 

29 

30 

11 

1-4 

1-7 

24 

25 

28 

32 

35 

36 

1-2 

1-6 

2-0 

25 

2'9 

3-3 

3-7 

4T 

40 

1-4 

1-9 

23 

2-8 

33 

3-8 

4-2 

4-7 

45 

1-6 

2'1 

26 

3-2 

3-7 

4-2 

4-8 

53 

50 

1-8 

2-4 

2-9 

3-5 

41 

4-7 

5-3 

5-9 

55 

1-9 

2-6 

32 

3-9 

4-5 

5-2 

5-8 

6-5 

60 

2-1 

2-8 

3o 

4-2 

49 

56 

64 

7-0 

3|  inches. 

5 

02 

02 

0-3 

0-3 

04 

04 

05 

0-5 

10 

0-3 

04 

0*5 

0'6 

0-7 

08 

09 

1-0 

15 

05 

06 

0-8 

0-9 

IT 

1-2 

14 

1-5 

20 

0-6 

0-8 

10 

1-2 

14 

16 

1-8 

2-0 

25 

0'8 

1-0 

13 

1*5 

1-8 

21 

23 

26 

30 

0-9 

1-2 

1-5 

1-8 

2T 

25 

2-8 

31 

35 

1-1 

1-4 

1-8 

2T 

25 

2-9 

32 

36 

40 

1-2 

1-6 

20 

25 

29 

33 

37 

44 

45 

1-4 

1-8 

2-3 

2-8 

32 

3-7 

41 

46 

50 

1-5 

21 

26 

3T 

3'6 

4T 

4-6 

54 

55 

1-7 

23 

2-8 

34 

39 

45 

61 

5-6 

60 

1-8 

25 

ST 

3'7 

43 

4-9 

55 

64 

4 inches. 

6 

0 1 

0-2 

0-2 

0-3 

03 

04 

04 

05 

10 

03 

0-4 

0-5 

0‘5 

06 

0-7 

0-8 

09 

15 

04 

0-5 

0'7 

0-8 

0-9 

IT 

1-2 

14 

20 

0-5 

0-7 

09 

IT 

1-3 

14 

1-6 

1-8 

25 

0-7 

09 

IT 

1-4 

1-6 

1-8 

2-0 

23 

30 

08 

IT 

1-4 

1-6 

1-9 

22 

24 

2-7 

35 

0-9 

1-3 

1-6 

1-9 

2 2 

25 

2-8 

3-2 

40 

11 

1-4 

1-8 

2-2 

25 

2-9 

3-2 

36 

45 

1-2 

1-6 

20 

24 

28 

3-2 

36 

44 

60 

1-4 

1-8 

23 

2-7 

32 

36 

41 

45 

65 

1-5 

2'0 

25 

30 

35 

4-0 

45 

50 

60 

1-6 

2 2 

2-7 

32 

38 

43 

49 

64 

Vol.  II.— 17 


258 


LOCOMOTIVE  ENGINE. 


Of  the  several  elements  of  the  friction  of  locomotive  engines. — After  having  examined  the  resistance 
offered  by  the  loads  to  be  moved,  it  will  be  proper  also  to  make  known  the  passive  resistance  or  fric- 
tion of  the  movers  which  we  have  to  employ ; for  it  is  only  the  surplus  of  their  power  over  and  above 
what  is  necessary  to  propel  themselves,  that  these  movers  can  apply  to  the  drawing  of  burdens. 

While  a locomotive  engine  is  performing  the  traction  of  a train,  it  evidently  requires : — 1st,  a certain 
force  to  make  the  train  advance,  or  to  overcome  the  resistance  of  all  the  loaded  carriages ; and  2dly, 
another  force  to  propel  itself  by  overcoming  its  own  friction.  It  is  this  second  force,  that  which  causes 
the  engine  to  move,  which  represents  the  friction  of  the  engine ; whereas  the  first  is  the  resistance  of 
the  load , and  the  union  of  the  two  efforts  constitutes  the  total  force  applied  by  the  mover. 

The  friction  of  a locomotive  engine  is  then  the  force  it  expends  to  maintain  itself  in  motion  on  the 
rails.  But  that  force  must  clearly  vary  according  to  the  weight  or  resistance  of  the  load  which  the 
engine  draws.  In  effect,  the  greater  that  weight,  the  greater  also  will  be  the  pressure  it  causes  on  the 
axes  of  rotation,  and  on  the  divers  moving  parts  of  the  apparatus;  and  as  the  friction  is  always  in 
proportion  to  the  pressure,  it  follows  that  the  friction  which  takes  place  at  these  points,  must  augment 
with  the  load.  Hence  the  friction  of  the  engine,  which  is  nothing  more  than  the  force  resulting  from 
the  union  of  these  different  frictions,  must  equally  increase  with  the  load. 

Thus  we  find  a difference  between  the  friction  of  an  engine  unloaded , and  that  of  the  same  engine 
loaded.  The  value  of  the  first  is  found  to  be  15  lbs.  per  ton  of  their  weight,  and  of  the  second,  T37  lbs. 
additional  per  pound  of  traction  in  the  case  of  uncoupled  driving-wheels,  and  '215  lbs.  per  pound  of 
traction  in  the  case  of  engines  with  wheels  coupled. 

It  will  readily  be  conceived,  however,  that  it  must  vary  some  with  the  construction  and  state  of  every 
engine. 

With  reference  to  the  manner  in  which  the  additional  friction  of  engines  ought  to  be  calculated,  we 
have  to  bear  in  mind  that  it  is  to  be  reckoned  on  every  pound  of  the  total  resistance  exerted  against  the 
motion ; that  is  to  say,  the  resistance  caused  by  the  friction  of  the  wagons,  that  of  gravity,  and  that  of 
the  atmosphere,  must  first  be  calculated,  and  on  the  sum  of  these  the  additional  friction  of  the  engine  is  to 
be  taken  at  the  rate  already  indicated. 

Of  the  total  resistance  on  the  piston,  resulting  from  the  divers  partial  resistances  just  enumerated. — 
We  have  just  estimated  successively  the  divers  resistances  which  oppose  the  motion  of  the  engine.  It 
is  necessary  now  to  seek  the  definitive  resistance  which  results  from  them  united,  per  square  inch  or 
per  unit  of  surface  of  the  area  of  the  piston. 

The  resistances  which  we  have  hitherto  considered  are — the  resistance  of  the  air,  the  friction  of  the 
wagons,  the  gravity,  the  friction  of  the  engines,  and  the  resistance  arising  from  the  blast-pipe.  But  we 
must  here  add,  besides,  the  atmospheric  pressure ; for  the  engines  under  consideration  being  high- 
pressure  engines,  it  follows  that  the  opposite  face  of  the  piston  necessarily  supports,  like  every  other 
uody  in  communication  with  the  atmosphere,  a certain  pressure  due  to  the  elasticity  of  the  atmos- 
pheric air. 

Thus,  the  definitive  resistance  exerted  against  the  piston  consists  of  six  resistances,  which  are — the 
friction  of  the  wagons,  the  resistance  of  the  air,  the  gravity  of  the  train,  the  friction  of  the  engine,  the 
atmospheric  pressure,  and  the  pressure  caused  by  the  blast-pipe.  Of  these  six  resistances,  the  last  two 
act  immediately  and  directly  on  the  piston.  'They  must  therefore  be  moved  at  the  velocity  of  the 
piston  itself ; but  it  is  not  so  with  the  other  four.  In  an  engine,  the  pressures  exerted  on  different  points 
by  the  same  force,  are  in  the  inverse  ratio  of  the  velocities  of  those  points.  Here  the  engine  and  its 
train  must  be  moved  at  a velocity  greater  than  that  of  the  piston,  in  the  proportion  of  the  circumference 
of  the  wheel,  to  twice  the  length  of  the  stroke.  The  intensity  of  the  pressure  exerted  by  the  resistance 
of  the  load,  the  air,  the  engine,  and  the  gravity,  is  then  increased  by  its  transmission  to  the  piston,  in  the 
above  ratio  of  the  velocity  of  the  wheel  to  that  of  the  piston. 

Consequently,  if  M express  the  number  of  tons  gross  which  compose  the  total  load,  that  is  to  say, 
including  the  weight  of  the  tender-carriage  of  the  engine,  and  k the  number  of  pounds  requisite  to  draw 
one  ton  on  a railway, 

k M 

will  be  the  resistance,  in  pounds,  resulting  from  the  friction  of  the  wagons  which  carry  the  load.  If  at 
the  same  time  we  call  g the  gravity  of  1 ton  on  the  inclined  plane  to  be  traversed  by  the  engine,  and  if 
m represent  the  weight  of  the  engine,  in  tons, 

g (M  -f  m) 

will  be  the  resistance,  in  pounds,  produced  by  the  gravity  of  the  total  mass,  train  and  engine  ; so  that, 
according  as  the  motion  takes  place  in  ascending  or  in  descending,  the  definitive  resistance  arising  from 
friction  and  gravity  will  be 

k M ±g  (M  + m ) = (k±g)  M ±gm. 

Similarly,  if  we  express  by  u v 2 the  resistance,  in  pounds,  exerted  by  the  air  against  the  train,  at  the 
velocity  v of  the  engine, 

(k±g)ll±gm  + u v 2 

will  be  the  resistance  opposed  to  the  motion  of  the  engine  by  the  friction,  the  gravity,  and  the  shock  of 
the  air. 

If,  again,  F represent  the  friction  of  the  unloaded  engine,  expressed  also  in  pounds,  and  <5  its  additional 
friction,  measured  as  a fraction  of  the  resistance,  as  has  been  already  indicated,  we  see  that 

F -f  <5  [ (k±g)  M ±g  m -f  u v-] 

will  be  the  total  friction  of  the  engine  at  the  moment  when  it  draws  the  resistance 

( k '±$0  M m + u v1. 


LOCOMOTIVE  ENGINE. 


259 


Consequently 

(1  + 0 [ (£±<7)  M±f7  m + u V]  + F 

will  be  the  total  resistance  opposed  to  the  progression,  along  the  rails,  by  the  engine  and  its  train. 

As  this  force  produces  on  the  piston  a resistance  augmented  in  the  ratio  of  the  circumference  of  the 
wheel  to  twice  the  stroke  of  the  piston,  if  D express  the  diameter  of  the  wheel,  l the  length  of  the 
stroke,  and  n the  ratio  of  the  circumference  to  the  diameter, 

0 + s)  [ (^dt#)  <7  m + u Yi  "t"  o i 

will  be  the  resistance  on  the  piston,  caused  by  that  force,  that  is  to  say,  caused  by  the  resistance  of  the 
wagons,  the  gravity,  the  air,  and  the  friction  of  the  engine. 

This  resistance  is  that  which  is  exerted  on  the  totality  of  the  area  of  the  pistons.  But  representing 
by  <1  the  diameter  of  the  cylinders,  d"  will  be  the  area  of  the  two  pistons.  Whence 

(1  + [ {k±cj)  M ±g  m + 

’ 

or,  simplifying, 

(l  + «)  [(*±S0M ±clm  + uP]~  + ^-l, 

will  be  the  same  force,  divided  according  to  the  unit  of  surface  of  the  piston. 

Adding  to  this  the  atmospheric  pressure  p,  and  the  pressure  caused  by  the  blast-pipe  p'  v,  which 
are  already  measured  per  unit  of  surface,  we  shall  have,  in  fine,  for  the  total  resistance  R exerted  on 
the  piston, 

R = (1  + &)  [ (k±ff)  M±y  m -f  u F2]  ~ + 5Z  +p  -fy/  v_ 

In  this  expression,  the  quantity  g represents  the  gravity  on  the  plane  to  be  traversed  by  the  train  ; if 
the  plane  be  horizontal  instead  of  inclined,  we  shall  have  g — o.  The  weights  M and  in  of  the  train  and 
the  engine  are  expressed  in  tons  gross ; the  quantity  k,  which  is  the  friction  of  the  wagons  per  ton,  is 
equal  to  6 lbs.;  the  value  of  S is  T37  or  4,  for  engines  with  uncoupled  wheels;  the  velocity  v of  the 
engine  is  expressed  in  miles  per  hour;  in  fine,  according  as  the  dimensions  D,  l and  d are  expressed  in 
inches  or  in  feet,  and  the  forces  u,  p and  p\  in  pounds  per  square  inch,  or  in  pounds  per  square  foot, 
the  value  R which  will  result  from  the  calculation  will  be  the  resisting  pressure  on  the  piston,  expressed 
likewise  in  pounds  per  square  inch,  or  in  pounds  per  square  foot. 

Applying  this  calculation  to  a train  of  9 wagons  and  a tender,  weighing  60  tons  gross,  and  drawn  at 
the  velocity  of  20  miles  per  hour,  up  a plane  inclined  t^j,,  by  an  engine  with  two  cylinders  of  11  inches 
diameter,  stroke  of  the  piston  16  inches,  propelling  wheels  6 feet,  not  coupled,  weight  8 tons,  friction 
104  lbs.,  blast- pipe  2'25  inches  in  diameter;  and  referring,  for  the  resistance  of  the  air,  to  what  has  been 
said  above,  the  proceeding  will  be  as  follows : 

60  X 6 = 300  lbs.  Friction  of  the  wagons,  in  pounds,  or  value  of  k m. 

2240 

— — X58  = 260  lbs.  Gravity  of  the  total  mass,  train  and  engine,  or  value  of  g (M  -j-  in ). 

194  lbs.  Resistance  of  the  air  against  an  effective  surface  of  180  square  feet,  at  the  ve- 
locity of  20  miles  per  hour  or  value  of  u v1. 

7 54  lbs.  Resistance  of  the  train,  or  ( k + y)  M -f-  gm-\-  u v 2. 

’lo'iXI'IS'l  = 857  lb3.  Resistance  of  the  train,  including  the  additional  friction  which  it  produces  in 
the  engine,  or  (1  -{-  5)  [ ( k + g)~M.-\-gm-{-v,  w2.] 

-f-  104  lbs.  Friction  of  the  unloaded  engine,  or  F. 


961  lbs.  Total  resistance  to  the  progressive  motion  of  the  engine,  or  value  of  the  term 
(l  + i)[(*  + fl')M  + SPm  + ««»H-F. 

On  the  other  hand,  we  have 

3T416  X 60  in.  = 188’5  Circumference  of  the  wheel,  expressed  in  inches,  or  z D. 

2X16  in.  = 32  Double  the  stroke  of  the  piston  expressed  in  inches,  or  2 7 

- = 5'9  Ratio  of  the  velocities  of  the  wheel  and  the  piston,  or  L_- 

Thus, 

961X6  9 = 5670  lbs.  Resistance  produced  on  the  piston,  or  value  of  the  term 


Again, 

3T416X112 


= 1 90  Area  of  tlie  two  pistons,  in  square  inches,  or  4 n d*. 


260 


LOCOMOTIVE  ENGINE. 


Consequently,  we  obtain  in  fine 


5670 

190 


= 29-8  lbs. 


Above-mentioned  resistance,  portioned  per  square  inch  of  the  surface  of  the 
piston. 


-1-  3’5  lbs.  Effective  pressure  per  square  inch,  arising  from  the  blast-pipe,  or  p' v. 
l-t'7  lbs.  Atmospheric  pressure  per  square  inch,  or  p. 


48  0 lbs.  Definitive  resistance,  per  square  inch  of  the  surface  of  the  piston  of  an  engine 
with  two  cylinders  of  11  inches  in  diameter,  <Szc.,  when  drawing  a load  of  50 
tons  under  the  given  circumstances. 

\V  ere  it  desired  to  know  that  resistance  per  square  foot,  it  would  suffice  to  multiply  the  last  result  by 
144,  that  is  to  say,  the  pressure  required  would  be  6912  lbs.  per  square  foot,  which  number  would  have 
been  obtained  directly,  if  instead  of  expressing  the  area  of  the  piston  in  square  inches,  and  the  partial 
pressures  in  pounds  per  square  inch,  these  measures  had  been  referred  to  the  square  foot  as  unit  ol 
surface. 

This  example  shows  what  is  to  be  understood  by  the  different  quantities  contained  in  the  formula,  and 
how  each  of  them  ought  to  be  introduced  into  the  calculation. 

To  know  the  evaporating  power  of  which  a given  engine  is  capable,  it  suffices  to  measure  the  number 
of  square  feet  composing  its  total  heating  surface,  without  distinction  between  the  fire-box  and  the  tubes, 
and  then  to  multiply  that  number  by  the  vaporization  which  each  square  foot  of  surface  is  capable  of  p>ro- 
aucing.  It  is  then  the  latter  quantity  which  we  must  now  seek  to  determine ; but,  as  we  have  seen 
that  the  vaporization  produced  per  unit  of  surface  varies  with  the  velocity  of  the  motion,  it  is  necessary 
to  specify  at  the  same  time  the  velocity  at  which  we  wish  to  measure  the  vaporization. 

We  find  that  in  certain  engines  the  vaporization  per  square  foot  of  heating  surface  was  T98  cubic 
foot,  at  the  velocity  of  1815  miles  per  hour.  On  the  other  hand,  we  know  that  the  vaporization  varies 
in  the  direct  ratio  of  the  fourth  roots  of  the  velocities.  We  may  then  deduce  from  thence,  that  at  the 
velocity  of  20  miles  per  hour,  the  vaporization  of  those  engines  will  be 

/ 20  \ i 

T98  S ^ - i ='203  cubic  foot  of  water  per  square  foot  of  heating  surface. 

Operating  in  the  same  manner  for  the  two  following  series,  we  obtain,  for  the  velocity  of  20  miles  per 
hour,  the  determinations  of  the  following  table  : 


Experiments  on  the  vaporization  of  locomotive  engines,  per  unit  of  total  heating  surface  of  their  boiur. 


Number  of  the  series. 

Average  velocity  of 
the  engine  in  miles 
per  hour. 

Vaporization  per  hour  and  per  sq. 
loot  of  total  heating  surface,  at 
the  preceding  velocity. 

Vaporization  per  hour  and  per  sq. 
foot  of  total  heating  surface,  at 
the  velocity  of  20  miles  per  hour. 

Miles. 

Cubic  foot. 

Cubic  foot. 

2d, 

1 8T5 

•198 

•203 

3d, 

20T3 

•200 

•200 

4th, 

8-99 

•172 

•210 

5th, 

15-26 

•194 

•208 

Mean '205 

Thus,  from  these  experiments,  it  appears  that  at  the  velocity  of  20  miles  per  hour,  the  vaporization 
of  locomotives  may  be  valued  at  "205,  or,  in  round  numbers,  at  '2  cubic  foot  of  water  per  hour,  per 
square  foot  of  total  heating  surface  of  their  boiler ; and  it  appears  also  that  the  different  engines  and 
different  velocities  lead  to  numbers  almost  identical,  which  tends  to  confirm  the  valuation  we  have  just 
obtained. 

This  determination  is,  as  we  have  said,  suitable  to  the  velocity  of  20  miles  per  hour;  but  it  is  easy  to 
deduce  from  it  that  which  would  take  place  at  any  other  velocity,  by  multiplying  by  the  fourth  root  of 
the  ratio  between  the  given  velocity  and  the  velocity  of  20  miles. 

It  must,  however,  be  observed,  with  respect  to  these  determinations,  that  they  are  strictly  suitable 
only  to  boilers  constructed  in  proportions  not  very  different  from  those  used  in  the  experiments ; that 
is  to  say,  according  to  what  has  been  explained  above,  that  the  heating  surface  of  the  fire-box  ought 
not  to  be  under  a tenth  of  the  total  heating  surface  of  the  boiler,  and  the  orifice  of  the  blast-pipe  not 
much  larger  than  we  had  it  in  our  experiments,  according  to  the  adopted  practice.  Were  any  notable 
change  made  in  this  respect,  were  the  fuel  of  an  inferior  quality,  or  the  engine  materially  different  in 
construction  from  what  we  have  described,  there  would  be  grounds  for  a new  determination  of  the 
vaporization. 

In  fine,  we  will  again  add,  that  the  numbers  obtained  above  indicate  rather  the  consumption  of  water 
of  the  boiler,  than  the  real  vaporization  produced ; for  we  shall  presently  see,  that  out  of  the  total  water 
thus  expended  by  the  engine,  there  is  a portion  which  is  drawn  into  the  cylinders,  mixed  with  the  steam, 
but  without  being  itself  vaporized.  Consequently,  to  obtain  the  real  vaporization  of  the  engine,  it  will 
be  necessary  to  take  account  of  this  circumstance,  as  we  shall  do  further  on. 

Of  the  loss  of  steam  which  takes  place  by  the  safety-valves,  during  the  icork  of  locomotive  engines. — 
Among  locomotive  engines  there  are  a great  number  which  are  subject  to  a continual  loss  of  steam  by 
the  safety-valves.  This  effect  arises  from  the  engine  being  designedly  constructed  with  an  excess  of 


LOCOMOTIVE  ENGINE. 


261 


power ; that  is  to  say,  that  according  to  the  production  of  steam  which  takes  place  in  its  boiler,  the 
engine  cftuld  draw  its  regular  load  at  a greater  velocity  than  it  is  allowed  to  do.  The  result  is,  that  tc 
prevent  the  engine  from  acquiring  too  great  a velocity,  it  becomes  necessary  partially  to  close  the  regu- 
lator, that  is,  to  diminish  the  passage  of  the  steam,  till  no  more  enters  the  cylinder  than  the  quantity 
necessary  to  produce  the  desired  velocity.  Then  the  surplus  accumulating  in  the  boiler,  at  last  raises 
the  safety-valve  and  escapes  iuto  the  atmosphere.  When  this  loss  takes  place  only  on  the  regula- 
tor being  somewhat  closed,  it  is  but  a proof,  as  we  have  said,  of  a surplus  of  power  which  the  engine 
holds  in  reserve.  But  if  it  takes  place  more  or  less  under  all  circumstances,  then  it  depends  on  the 
steam-ways  being  too  narrow,  and  is  consequently  a defect  in  the  engine  ; in  either  case,  however,  it  is 
necessary  to  obtain  a valuation  of  this  loss. 

There  is  yet  another  case  in  which  engines  are  subject  to  a loss  of  steam  by  the  valves ; but  this  loss 
is  owing  to  a different  cause  from  the  preceding,  and  exhibits  itself  much  more  abundantly ; it  is  when 
the  engine  ascends  a steep  acclivity,  with  an  apparently  moderate  load,  or  when  it  ascends  a moderate 
inclination,  with  a very  heavy  load.  At  these  moments  the  valves  are  always  seen  to  emit  an  enor 
mous  quantity  of  steam.  The  reason  is  that,  as  soon  as  the  engine  reaches  the  inclined  plane,  its  load 
instantly  becomes  extremely  heavy,  on  account  of  the  surplus  of  traction  required  by  the  gravity  on  the 
plane.  It  has  been  shown,  in  effect,  that  on  a plane  inclined  every  ton  produces,  by  gravity  alone, 
a resistance  equal  to  that  of  3'7  tons  on  a level.  It  happens  therefore,  at  that  moment,  that  the  re- 
sistance of  the  train  may  become  greater  than  the  actual  pressure  of  the  safety-valve.  Consequently 
the  steam,  instead  of  flowing  by  the  cylinder,  driving  back  the  piston,  raises  the  safety-valve,  and 
escapes  into  the  atmosphere.  If  then  the  passage  which  the  steam  thus  opens  for  itself  were  sufficient 
for  its  total  efflux,  no  more  steam  would  pass  through  the  cylinder,  and  the  engine  would  inevita- 
bly stop. 

Moreover,  since,  supposing  even  the  steam  in  the  cylinder  at  the  same  pressure  as  in  the  boiler,  which 
is  the  most  favorable  supposition  we  can  make,  it  still  happens  that  the  volume  of  steam  expended  by 
the  cylinder  is  less  than  the  volume  of  steam  generated  in  the  boiler,  a part  of  the  water  must  have 
been  carried  from  the  boiler  to  the  cylinder,  in  its  liquid  state ; and  the  comparison  between  the  quan- 
tity of  water  consumed  by  the  boiler  and  that  which,  in  the  state  of  vapor,  corresponds  to  the  velocity 
of  the  piston,  shows  that  the  quantity  of  water  really  converted  into  steam,  is  to  the  total  quantity  of 
water  consumed,  in  the  ratio  of  the  numbers 

11827 

15641  — 'b' 

Thus,  in  this  experiment,  we  see  that  -24  of  the  water  expended  by  the  boiler  was  carried  into  the 
cylinders  without  being  reduced  to  steam,  or  that  the  real  vaporization  of  the  engine  was  -76  of  the  total 
water  expended. 

The  results  which  have  just  been  presented  above  show  that  the  quantity  of  water  carried  away  with 
the  steam,  varies  in  different  engines,  and  ought  to  be  determined  for  each  separately ; but  as  in  taking 
the  means  between  the  different  experiments,  that  loss  is  found  to  amount  to  -24  of  the  total  vaporiza- 
tion of  the  boiler,  this  proportion  may  be  adopted  approximatively  for  engines  that  have  not  been 
directly  submitted  to  experiment  in  this  respect ; that  is  to  say,  in  order  to  have  the  effective  vaporiza- 
tion of  a locomotive,  the  total  vaporization  of  which  its  boiler  is  capable  must  be  first  measured ; from 
the  result  must  be  subtracted , if  necessary,  the  loss,  either  accidental  or  permanent,  which  may  be  observed 
at  the  safety-valves,  and  the  remainder  must  be  multiplied  by  the  fraction  -76.  Thus  will  be  obtained 
the  volume  of  water  which  passes  into  the  cylinder,  in  the  real  state  of  steam,  and  produces  the  motion 
of  the  piston. 

We  liave  reason  then  to  think,  from  the  different  experiments  cited  above,  that  with  coke  for  fuel,  and 
with  the  other  circumstances  of  the  work  and  the  construction  of  the  engines,  the  most  advantageous 
ratio  to  establish  between  the  total  heating  surface  and  that  of  the  fire-box  would  be  nearly  that  of  10 
to  1 : since  for  a less  proportion  there  would  be  increase  in  the  expenditure  of  fuel,  without  increase  of 
vaporization  ; and  for  a greater  proportion,  on  the  contrary,  there  would  be  reduction  in  the  vaporization 
of  the  engine  per  unit  of  surface,  which  would  incur  the  necessity  of  a larger  boiler,  and  consequently  of 
a greater  weight,  which  it  is  important  to  avoid. 

In  fine,  to  arrive  at  a general  conclusion  from  the  experiments  which  have  been  made  in  order  to  the 
determination  of  this  question,  it  appears  that,  according  to  the  proportion  of  the  fire-box  to  the  total 
heating  surface,  the  consumption  of  fuel  in  locomotive  engines  varies  from  9'2  to  1T3  and  11'7  pounds 
per  cubic  foot  of  total  water  vaporized  : so  that  it  may,  on  an  average,  be  valued  at  10  7 pounds  of  coke 

per  cubic  foot  of  total  vaporization,  or  its  equivalent  in  other  fuel. 

Fuel. — To  find  the  quantity  of  fuel  necessary  for  the  engine  per  ton  per  mile,  the  load  the  engine  is 
to  draw  must  previously  be  given : in  multiplying  the  given  load  by  the  velocity  the  engine  will  assume 
with  that  load,  the  product  will  immediately  make  known,  in  tons  conveyed  one  mile  per  hour,  the  use- 
ful effect  of  the  engine.  Dividing  then  the  consumption  of  fuel  of  the  engine  per  hour  by  the  useful 
effect  produced  in  the  same  time,  the  quotient  will  give  definitively  the  quantity  of  fuel  which  will  be 
consumed  by  the  engine  per  ton  per  mile  in  drawing  the  given  load. 

The  principal  problems  which  occur  with  respect  to  locomotive  engines  have  reference  in  the  first 
place  to  two  circumstances,  namely:  1.  When  the  engine  is  already  constructed,  and  the  question  is  to 

determine  the  effects  that  it  will  produce ; 2.  When  the  engine  is  as  yet  unbuilt,  and  the  question  is  to 

determine  the  proportions  it  ought  to  have  in  order  to  produce  desired  effects.  At  present  we  consider 
only  the  questions  relative  to  the  first  case. 

When  an  engine  is  already  constructed,  and  all  its  dimensions  may  be  directly  measured,  the  follow 
ing  problems  may  present  themselves: 

1.  To  determine  the  velocity  the  engine  will  assume  with  a fixed  load  ; 

2.  To  determine  the  load  it  will  draw  at  a desired  velocity; 


“262 


LOCOMOTIVE  ENGINE. 


3.  To  determine  the  useful  effect  it  will  produce  at  a desired  velocity,  or  with  a fixed  load. 

And  this  last  problem  may  itself  be  expressed  under  ten  different  forms — namely,  to  find  successively 

The  useful  effect  of  the  engine  in  tons  drawn  one  mile ; 

The  useful  effect  expressed  in  horse-power ; 

The  quantity  of  fuel  necessary  per  ton  per  mile ; 

The  quantity  of  water  necessary  per  ton  per  mile  ; 

The  useful  effect  produced  per  pound  of  fuel  consumed  ; 

The  useful  effect  produced  per  cubic  foot  of  water  vaporized  ; 

The  consumption  of  fuel  which  produces  one-horse  power  ; 

The  consumption  of  water  which  produces  one-horse  power  ; 

The  horse-power  produced  per  pound  of  fuel ; 

The  horse-power  produced  per  cubic  foot  of  water  vaporized. 

Moreover,  as  two  cases  are  necessarily  to  be  distinguished  in  the  work  of  the  engines,  namely,  the 
case  in  which  they  work  with  a load  or  velocity  indefinite,  and  that  in  which  they  work  with  the  load 
or  velocity  which  produces  the  maximum  of  usef  ul  effect,  there  will  yet  occur  in  tins  respect  a new  series 
of  questions,  namely : 

1.  To  determine  the  velocity  at  which  the  engine  will  produce  its  maximum  of  useful  effect ; 

2.  To  determine  the  load  corresponding  to  the  production  of  the  maximum  of  useful  effect ; 

3.  To  determine  the  maximum  of  useful  effect  that  the  engine  can  produce. 

And  this  last  problem  may  be  expressed  under  the  ten  different  forms  which  we  have  indicated 
above. 

Of  the  velocity  of  the  engine  with  a given  load. — Suppose,  in  effect,  that  a load  of  50  tons  gross,  tender 
included,  be  drawn  up  a plane  inclined  by  an  engine  with  2 cylinders  11  inches  hi  diameter,  stroke 
of  the  piston  16  inches,  wheels  5 feet,  friction  103  pounds,  total  pressure  of  the  steam  in  the  boiler  65 
pounds,  or  effective  pressure  50  pounds  per  square  inch,  and,  finally,  vaporizing  pjower  60  cubic  feet  of 
water  per  hour,  or  1 cubic  foot  per  minute. 

The  total  resistance  opposed  by  that  load  to  the  motion  of  the  piston  is  48  pounds  per  square  inch, 
when  the  velocity  is  20  miles  per  hour.  If,  then,  we  admit  that  the  engine  will  come  near  enough  to 
that  velocity,  for  the  valuation  which  we  have  made  of  the  resistance  of  the  air  and  the  pressure  caused 
by  the  blast-pipe,  in  the  calculation,  not  to  be  very  far  from  the  truth,  we  must  conclude  that,  during 
the  uniform  or  permanent  motion  of  the  engine  with  that  load,  the  pressure  of  the  steam,  during  its 
action  in  the  cylinder,  will  likewise  be  48  pounds  per  square  inch. 

Now,  the  quantity  of  water  consumed  by  the  boiler  amounts  to  60  cubic  feet  of  water  per  hour,  and 
we  have  shown  in  treating  of  the  vaporization  that  out  of  that  mass  of  water  75-lOOths  only,  on  an  av- 
erage, are  really  converted  into  steam,  and  that  the  rest  is  merely  carried  away  with  the  steam  into  the 
cylinders,  but  in  a liquid  state.  The  effective  vaporization  of  the  engine  is,  then,  firstly, 

•75  X 60  = 45  cubic  feet  per  hour,  or 
•75  cubic  foot  per  minute. 

This  water  is  first  transformed,  in  the  boiler,  into  steam  at  the  total  pressure  of  65  pounds  per  square 
inch  ; but  on  passing  into  the  cylinders  it  acquires  the  pressure  of  48  pounds  per  square  inch,  and  we 
know  that,  in  this  change,  the  steam  remains  always  at  the  maximum  density  for  its  temperature.  Its 
volume  may  then  be  determined  by  the  table,  which  we  have  already  given,  on  the  volume  of  the  steam 
formed  under  different  pressures.  According  to  this  table,  the  volume  of  the  steam  formed  under  the 
total  pressure  of  48  pounds  per  square  inch,  is  573  times  that  of  the  water  which  produced  it.  Hence 
the  quantity  of  water  effectively  vaporized  per  minute  in  the  boiler,  will  form,  during  its  passage  through 
the  cylinders,  a volume  of  steam  expressed  by 

573  X ’75  =430  cubic  feet. 

On  the  other  hand,  the  area  of  each  cylinder  is  95  square  inches,  or  in  square  feet  that  area  is  repre- 
sented by  '66  square  foot;  and  the  stroke  of  the  piston  is  16  niches,  or  T33  foot.  Whence  the  capacity 
of  each  cylinder  traversed  by  the  piston  is 

•88  cubic  foot. 

But  besides  the  portion  traversed  by  the  piston  there  still  exists,  at  each  end  of  each  cylinder,  a vacant 
space  called  the  clearance  of  the  cylinder,  which  is  necessarily  filled  with  steam  at  each  stroke.  The 
capacity  of  this  vacant  space,  represented  by  an  equivalent  portion  of  the  cylinder,  and  steam-ways 
included,  is  usually  l-20th  of  the  part  of  the  cylinder  traversed  by  the  piston.  The  real  capacity,  there- 
fore, which  is  filled  with  steam  at  each  stroke  of  the  piston,  is 

•88  X — '924  cubic  foot. 

Consequently  the  number  of  strokes  of  the  piston  which  the  engine  will  give  per  minute,  by  reason  of 
its  effective  vaporization,  will  necessarily  be 

430 

■ = 46o. 

•924 

Now,  each  time  the  wheel  makes  one  revolution  the  engine  gives  two  strokes  of  the  piston  in  each  of 
its  two  cylinders ; and  the  diameter  of  the  wheel  is  5 feet,  which  makes  1 5‘7 1 feet  in  circumference. 
Therefore,  at  every  four  strokes  of  the  piston  the  engine  advances  15’7l  feet;  that  is  to  say,  its  velocity, 
in  feet  per  minute,  will  be 

— X 15-71  = 1822  feet. 

4 

Finally,  as  one  mile  contains  5280  feet,  and  one  hour  contains  60  minutes,  the  definitive  velocity  of  tie 
engine,  in  miles  per  hour,  will  be 


LOCOMOTIVE  ENGINE. 


20: 


X 1822  = 20'7l  miles. 

5280 

Thus  we  see  that  the  above  vaporization  will  necessarily  produce  a velocity  of  20'7  miles  per  hour 
for  the  engine  ; that  is  to  say,  a locomotive  engine  with  the  given  proportions  may,  if  in  good  order,  and 
with  a well-stocked  fire,  draw  a load  of  50  tons  gross,  tender  included,  up  a plane  inclined  at  the 
velocity  of  20'7  miles  per  hour. 

With  regard  to  the  velocity  which  we  have  just  obtained,  we  must  add  that  if  the  engine  suffers  be- 
sides a loss  of  steam  by  the  safety-valve,  which  takes  place  in  a great  number  of  locomotive  engines, 
there  will  then  be  a corresponding  loss  on  the  effective  vaporization ; and  consequently  the  definitive 
velocity  of  the  engine  will  be  reduced  in  a corresponding  proportion.  For  instance,  if  the  engine 
be  liable  to  a loss  of  -05  of  its  vaporization  in  full  activity,  its  definitive  velocity,  in  the  case  above 
mentioned,  will  become 

•95  X 20'71  = 19'67  miles  per  hour. 

The  calculation  will  be  performed  in  the  same  manner  for  every  other  load  and  for  every  other  engine. 
Thus,  in  general, 

M,  Representing  the  number  of  tons  of  the  load,  tender  included ; 
in,  The  weight  of  the  engine,  in  tons ; 

g,  The  gravity,  in  pounds,  of  one  ton  on  the  plane  the  engine  has  to  traverse ; this  gravity  being  null 
for  the  case  of  a horizontal  plane ; 

k,  The  friction  of  the  wagons  per  ton,  expressed  in  pounds ; 
v,  The  velocity  of  the  engine,  in  miles  per  hour ; 

u v2,  The  resistance  of  the  air  against  the  train,  at  the  velocity  v,  resistance  expressed  in  pounds ; 
p'  v,  The  pressure  against  the  piston,  arising  from  the  action  of  the  blast-pipe,  expressed  in  pounds  per 
square  foot ; 

F,  The  friction  of  the  engine,  in  pounds  ; 

6,  Its  additional  friction,  measured  as  a fraction  of  the  resistance ; 

D,  The  diameter  of  the  propelling  wheels  of  the  engine,  in  feet; 
d,  The  diameter  of  the  cylinder,  in  feet ; 

l,  The  length  of  the  stroke  of  the  piston,  in  feet ; 

c,  The  clearance  of  the  cylinder,  represented  by  an  equivalent  portion  of  the  stroke  of  the  piston, 
and  consequently  in  feet ; 

P,  The  total  or  absolute  pressure  of  the  steam  in  the  boiler,  in  pounds  per  square  foot ; 
p,  The  atmospheric  pressure,  expressed  in  pounds  per  square  foot ; finally, 

S,  The  effective  vaporization  of  the  engine,  in  cubic  feet  of  water  per  hour,  at  the  velocity  known  or 
unknown  of  the  motion ; 

R = (l  + ^)  [(k±gW±gm  + uvi]^l  + J^l  + p-{-p'v, 

will  be  the  pressure  of  the  steam  per  unit  of  surface  in  the  cylinder. 

On  the  other  hand,  if  we  express  by  n the  relative  volume  of  the  steam  generated  under  the  pressure 
R,  a relative  volume  which  will  be  found  in  the  tables  given,  p.  230,  since  S is  the  volume  of  water 
vaporized  per  hour  in  the  engine,  it  follows  that 

will  be  the  corresponding  volume  of  the  steam  under  the  pressure  R ; that  is  to  say,  during  its  action  in 
the  cylinders. 

But,  expressing  by  w the  ratio  of  the  circumference  to  the  diameter,  the  capacity  of  each  cylinder 
which  is  traversed  by  the  piston,  has  for  its  measure 

indH- 

and  the  clearance  of  the  cylinder  offers,  besides,  a capacity  of 

I ir  d ‘ c. 

Therefore  the  totality  of  the  space  filled  with  steam  at  each  stroke,  in  each  cylinder,  has  for  its 
expression 

\itd2{lffc). 

Consequently  the  number  of  strokes  of  the  piston  corresponding  to  the  volume  of  steam  expended  ^ S, 
will  be  n S 

\ it  d“  (l  -f-  c) 

But,  while  each  piston  performs  2 strokes,  that  is,  at  every  expenditure  of  4 cylinders-full  of  steam, 
the  engine  advances  1 turn  of  the  wheel,  that  is  to  say,  a space  represented  by 


Therefore  the  velocity  of  the  engine,  in  feet  per  hour,  will  be  expressed  by  the  above  number  of  strokes, 
divided  by  4 and  multiplied  by  it  D ; that  is  to  say,  the  velocity  will  be 


D 

/ -j-  c 


And  finally,  as  1 mile  contains  5280  feet,  the  velocity  of  the  engine  expressed  in  miles  per  hour,  will  be 


1 D 

528o"  d2'  l-\-c 


(1) 


i'his  expression  will  make  known  the  velocity  required,  on  substituting,  for  each  of  the  letters,  the  valut 
suitable  to  it  in  the  engine  considered. 


264 


LOCOMOTIVE  ENGINE. 


As  it  has  been  shown  that  the  relative  volume  of  the  steam  under  the  pressure  R,  may  be  ex- 
pressed by 

1 

n + q R 


it  is  plain  that,  instead  of  seeking  the  relative  volume  n in  the  table  which  we  have  given,  its  value  may 
be  represented  by  the  expression 


1 


n + yR 


n + y 


1 

( + <0  [(i-±y)M±ym+M»!]^+^+])+y!)  j- 


and  consequently  the  preceding  expression  of  the  velocity  of  the  engine  may  equally  be  written  under 
the  form 


i 2 _j_  s 

o-80  q l + c ^^.3)  [(£±S,)M±y»i  + Mif']  + F + 3"  +.P 


(1  bis) 


Such  then  will  be  the  general  expression  of  the  velocity  of  the  engine,  in  miles  per  hour ; an  expression 
in  which  all  is  known  from  measures  taken  on  the  engine,  even  the  vaporization  S,  which  results  from 
the  extent  of  heating  surface. 

Making  use  of  this  formula  to  find  the  velocities  corresponding  to  divers  loads  of  the  engine,  or  to 
divers  values  of  M,  attention  must  be  paid  never  to  suppose,  for  M,  a load  capable  of  producing  on  the 
piston  a resistance  greater  than  the  pressure  of  the  steam  in  the  boiler,  because  it  is  evident  that  the 
resistance  would  then  exceed  the  power,  and  the  motion  could  not  take  place.  Nor  can  M be  supposed 
of  a value  less  than  the  weight  of  the  tender,  which  is  the  minimum  load  an  engine  can  have  to  draw. 
Beyond  these  two  limits  the  solutions  given  by  the  formula  would  evidently  cease  to  suit  the  problem. 

Practical  formulae  for  calcxilating  the  effects  of  locomotive  engines,  and  examples  of  their  application. — 
We  have  hitherto  presented  the  formula  proper  for  calculating  the  effects  of  the  engines,  under  a 
form  completely  algebraical,  that  is  to  say,  leaving  in  them  all  the  quantities  represented  by  letters, 
without  excepting  the  constant  quantities  whose  values  have  been  already  determined  in  former  pages. 
But  we  now  purpose  to  reduce  these  formula  to  their  most  simple  practical  form ; in  order  to  effect 
which,  it  will  be  proper  to  replace  in  them,  as  far  as  may  be,  the  letters,  by  the  numerical  values  which 
they  represent. 

The  letters  which  have  a constant  value  in  all  cases  and  for  all  the'  engines  are — 

Friction  of  the  wagons,  which  we  have  found  equal  to  6 lbs.  per  ton ; 

p,  Atmospheric  pressure,  the  value  of'which  is  2118  lbs.  per  square  foot; 

n,  Constant  quantity  relative  to  the  volume  of  the  steam,  its  value  being  '0001421,  when  the  pressure 
is  measured  in  pounds  per  square  foot ; 

q,  Factor  relative  to  the  volume  of  the  steam,  equal  to  '00000028  when  the  pressure  is  expressed  in 

pounds  per  square  foot ; 

c,  Clearance  of  the  cylinder,  which  may  be  taken  generally  at  — of  the  useful  stroke  of  the  piston,  which 


gives 


l _ 20 
1+c-Ti 


These  values  being  constant  for  all  engines,  may  be  introduced  permanently  into  the  equations.  Sub- 
stituting them  therefore  for  the  respective  letters,  and  effecting  the  calculation  as  much  as  possible,  we 
obtain  the  following  formulae,  which  are  quite  prepared  for  practical  applications. 

In  order  to  avoid  recurring  to  another  page  of  the  wTork,  we  will  first  repeat  here  the  signification  oi 
all  the  letters  which  subsist  in  these  formute. 


M,  Load  of  the  engine,  in  tons  gross,  tender  included ; 
m,  Weight  of  the  engine,  in  tons ; 

C,  Weight  of  the  tender,  in  tons ; 

<7,  Gravity,  in  pounds,  of  1 ton  placed  on  the  inclined  plane  to  be  traversed  by  the  engine.  If  the  in- 
1 2240 

clination  of  the  plane  be  — > that  gravity*(vill  have  for  its  value,  in  pounds, ; and  if  the  plane 

be  horizontal,  the  gravity  will  be  equal  to  zero; 
v,  Velocity  of  the  engine,  expressed  in  miles  per  hour; 

« jj2,  Resistance  of  the  air  against  the  train,  at  the  velocity  v,  a resistance  expressed  in  pounds ; 
p'  v,  Pressure  owing  to  the  blast-pipe,  expressed  in  pounds  per  square  foot ; 

F,  Friction  of  the  engine,  in  pounds ; 

<?,  Additional  friction  of  the  engine,  measured  as  a fraction  of  the  resistance,  namely:  T4  for  engines 
with  uncoupled  wheels,  and  '22  for  those  with  coupled  wheels; 

D,  Diameter  of  the  propelling  wheels,  in  feet ; 
d.  Diameter  of  the  cylinder,  in  feet ; 

i.  Stroke  of  the  piston,  in  feet ; 

P,  Total  or  absolute  pressure  of  the  steam  in  the  boiler,  in  pounds  per  square  foot ; 

S,  Effective  vaporization  of  the  engine,  in  cubic  feet  of  water,  per  hour.  It  varies  according  to  the 
engines,  but  may,  on  an  average,  be  valued  at  '75  of  the  total  or  gross  vaporization,  when  there 
is  no  blowing  of  steam  at  the  valves; 

S',  Total  vaporization  of  the  boiler,  at  the  velocity  of  the  motion,  in  cubic  feet  of  water  per  hour1 

N,  Consumption  of  coke  in  the  fire-box,  in  pounds  per  hour. 


LOCOMOTIVE  ENGINE. 


265 


PRACTICAL  FORMULAS  FOR  CALCULATING  THE  EFFECTS  OF  LOCOMOTIVE  ENGINES. 

General  case. 

784  S 

v — fffl 

(1  + i)  [(6±5')M±i”«  + “i'2]  + F + — (2736  +p'v) 

Velocity  of  tlie  engine,  in  miles  per  hour. 

M=p5)W)t,84»_T(a,3,!+'>'’)-F]-«S5(“'’±!'”)  = 

Load  of  the  engine,  in  tons  gross,  tender  included. 

u.  E =M»  = 

Useful  effect,  in  tons  gross,  drawn  1 mile  per  hour,  tender  included. 

u‘KinHP ~ 62-5  ~ 

Useful  effect,  in  horse-power. 

N 

Q.  co.  pr.  t.  pr.  M = vj jr  — 

1 r My  — (J  v 

Quantity  of  coke  in  pounds,  per  ton  gross  drawn  1 mile,  tender  not  included. 

S' 

Q.  wa.  pr.  t.  pr.  m = rj — = 

1 r My  — Cy 

Quantity  of  water,  in  cubic  feet,  per  ton  gross  drawn  1 mile,  tender  not  included. 

My 

u.  E.  1 lb.  co = — = 

N 

Useful  effect  produced  per  pound  of  coke,  in  tons  gross  drawn  1 mile,  tender  included. 

_ My 

u.  E.  1 ft.  wa = -t—  = 

Jo 

Useful  effect  produced  per  cubic  foot  of  total  vaporization,  in  tons  gross  drawn  1 mile,  tender  ircluded 

Q.  co.  fr.  1HP =<^^  = 

Mv 

Quantity  of  coke  in  pounds,  w hich  produces  the  effect  of  1 horse. 

Q.  wa.  fr.  1 HP = 

Mv 

Quantity  of  water,  in  cubic  feet,  which  produces  the  effect  of  1 horse. 

u.  E.  1 lb.  co.  in  H P = — = 

62o  N 

Useful  effect,  in  horse-power,  produced  per  pound  of  coke. 

u.  E.  1 ft.  wa.  in  H P = - M V , = 

62'5  S’ 

Useful  effect,  in  horse-power,  produced  per  cubic  foot  of  total  vaporization. 

Case  of  maximum  useful  effect. 

1-804  D S _ 

V ~ 1-421+ -0023  P 7 + 

Velocity  of  maximum  useful  effect,  in  miles  per  hour. 

M' = (i  + s)[Lg)i>  (p - 2118 -P' ^ ^ m)  = 

Maximum  load  of  the  engine,  in  tons  gross,  tender  included. 

M.  u.  E =Wv’  = 

Maximum  useful  effect,  in  tons  gross  drawn  1 mile  per  hour,  tender  included. 


That  there  may  be  no  misunderstanding  as  to  the  manner  of  expressing  the  divers  quantities  contained 
in  the  formula!,  nor  on  the  manner  of  performing  the  calculation,  we  will  here  give  an  example  or  twro 
with  some  detail. 

Suppose  a locomotive  of  65  cubic  feet  of  total  vaporization,  at  the  velocity  of  20  miles  per  hour ; 
with  cylinders  11  inches  or  -917  foot  in  diameter,  stroke  of  the  piston  16  inches  or  P33  foot,  wheels  5 
feet  in  diameter,  not  coupled,  friction  103  lbs.,  weight  8 tons,  blast-pipe  2'33  inches  in  diameter,  total  or 
absolute  pressure  in  the  boiler  65  lbs.  per  square  inch,  and  consumption  of  coke  per  hour  598  lbs.  Sup- 
pose this  engine  employed  on  a level  railway,  of  about  5 feet  of  width  of  way,  and  let  it  be  required  tc 


266 


LOCOMOTIVE  ENGINE. 


know  what  velocity  it  will  attain  with  a train  of  10  wagons  weighing  56  tons,  tender  included,  which 
is  the  same  as  5t)  tons  without  tender. 

1st.  As  the  motion  takes  place  on  a horizontal  plane,  we  have  <7  = 0;  and  since  the  wheels  of  the 
engine  are  not  coupled,  we  have  <3  =-14  ==■}.  Moreover,  from  the  ratio  which  we  have  found  between 
the  total  and  the  effective  vaporization  of  the  engine,  the  value  of  the  latter,  at  20  miles  per  hour,  is 
S = -75  X65  = 48-75  cubic  feet  of  water  per  hour ; 

*nd  in  fine,  from  the  proportions  of  the  engine,  we  have 


<IH  — 2 1-33 

— = •917  X— = '2237. 
U 5 


This  done,  to  find  what  velocity  the  engine  will  acquire  in  drawing  the  train  of  06  tons,  we  will  first 
suppose  that  it  may  be,  approximative^,  23  miles  per  hour,  and  we  shall  then  have,  for  the  pressure  in 
the  blast-pipe,  4 lbs.  per  square  inch,  or  p'  v — 576  lbs.  per  square  foot.  As  the  effective  surface  pre- 
sented to  the  shock  of  the  air,  valued  according  to  the  mode  already  explained,  is  S = 70  — f-  10X12  = 190 
square  feet,  the  resistance  of  the  air  at  the  velocity  of  23  miles  per  hour,  will  be  u v2  = 270. 

Thus  the  value  of  v,  taken  without  supposing  that  the  vaporization  changes  with  the  velocity,  will  be 

784X48-75  n)00 

v = = 24*88. 

1-14(6X56  + 270) + 103 + *2237  (2736  + 576) 

This  first  essay  of  calculation  gives  then  24-88  miles  per  hour,  for  the  velocity  of  the  engine,  and  we 
conclude  from  it  that  the  two  terms  u v 2 and  p'  v which  we  have  calculated  on  the  supposition  of  v = 23, 
have  not  been  valued  in  a manner  sufficiently  exact,  but  that  the  true  velocity  is  comprised  between 
24'88  and  23  miles. 

Trial  then  might  be  made  of  v = 24,  and  this  value  would  be  found  to  satisfy  the  problem,  when  the 
variation  which  the  vaporization  undergoes  with  the  velocity  of  the  motion  is  neglected.  Thus  approx- 
imatively  we  might  hold  to  this  result ; but  if  it  be  desired  to  calculate  with  greater  accuracy,  it  will  be 
proper  to  introduce  the  increase  of  vaporization  due  to  the  velocity. 

For  this  purpose,  as  the  increase  of  vaporization  will  have  the  effect  of  increasing  the  result  of  the 
calculation,  we  will  try  a number  greater  than  24,  as  v = 25,  for  instance.  Supposing  then  this  datum 
for  the  valuation  of  the  variable  quantities,  we  shall  have 

S = 5T55, 
p'  v = 630, 
u i'2  = 3 1 9 ; 

and  resolving  the  equation  with  these  values  we  find 

v = 25-19. 


Consequently,  in  fine,  taking  a mean  between  25  and  25-19,  we  have,  for  the  definitive  velocity  sought, 

v = 25'10  miles  per  hour. 

Such  then  will  be  the  velocity  which  the  engine  will  assume,  when  drawing  on  a level  a train  of  56 
tons,  tender  included. 

2d.  To  continue  this  example  of  the  application  of  the  formulae,  let  it  be  required  to  find  what  will  be 
the  velocity  of  the  maximum  useful  effect  of  the  engine. 

In  order  to  effect  this,  we  will  replace  in  the  equation  proper  to  that  problem,  the  pressure  P in  the 
boiler  by  its  value  P = 65  X 144  = 9360  lbs.  per  square  foot ; and  supposing  first  that  the  vaporization 
of  the  engine  will  undergo  no  change  notwithstanding  the  reduction  of  velocity,  we  obtain  the  result 

, 1-804  X 48-75  1 

v'= ; = 17T3. 

1-421  + -0023  X 9360  '2237 

This  would  then  be  the  velocity  sought,  if  the  vaporization  of  the  engine  were  invariable ; but  as  the 
diminution  of  velocity  will  lower  the  vaporization,  which  is  such  as  we  have  supposed  it,  only  at  the 
velocity  of  20  miles  per  hour,  we  will  try  whether  the  velocity  of  16  miles  will  suit  the  formula.  Then 
the  effective  vaporization  of  the  engine,  reduced  in  the  proportion  of  the  fourth  roots  of  the  velocities, 
will  become  46-10  cubic  feet  of  water  per  hour,  and  the  formula  resolved  according  to  this  supposition, 
will  give 

v’  = 16'20  miles  per  hour. 


This  is  therefore  the  velocity  suitable  to  the  production  of  the  maximum  useful  effect  required. 

3d.  In  fine,  to  obtain  the  load  corresponding  to  the  maximum  of  useful  effect,  we  recur  to  the  proper 
equation,  which  is 

,r,  dH  1 , , F W2 

M'  = — • . (P  — 2118—  p’v’)  — 


D 6 (1  + <S) ' 


6 (1  +<5) 


and  first  calculating  in  this  all  the  terms,  except  the  last,  we  have  as  a result  208'46. 

It  remains  then  to  subtract  from  this  number  the  value  of  — ■ V—  > to  conclude  from  it  definitively  the 

11 

required  value  of  the  load.  As  the  value  of  the  term  — depends  on  the  number  of  carriages  in  the 


train,  which  will  itself  be  known  only  by  the  definitive  solution  of  the  problem,  we  will  again  in  this 
place  follow  the  method  of  approximations.  Supposing  the  load  to  be  of  about  1 60  tons,  the  train  will 
consist  of  31  carriages  besides  the  tender ; thus  the  effective  surface  offered  to  the  shock  of  the  air,  will  be 


2 = 70  + 33  X 10  = 400  square  feet. 


LOCOMOTIVE  ENGINE. 


267 


Consequently  the  resistance  of  the  air,  at  the  velocity  found,  of  16-20  miles  per  hour,  will  he  u v'2  = 28? 
lbs.,  which  gives 


substituting  then  this  valuation  in  the  formula,  we  obtain  the  result 

M'  = 208-46  — 47-00  = 161-46. 

Consequently  the  load  of  161-6  tons,  forming  a train  of  31  carriages,  besides  the  tender,  will  be  tha 
maximum  load  required. 

4th.  In  fine,  if  it  be  desired  to  know  the  maximum  velocity  the  engine  is  capable  of  attaining,  when 
followed  by  its  tender  only,  and  without  drawing  any  train,  the  proceeding  will  be  as  in  the  first  case ; 
but  supposing  the  load  to  be  of  6 tons  only,  and  taking  account  of  the  increase  of  vaporization,  accord- 
ing to  the  velocity,  the  result  will  be 

v = 35  03  miles  per  hour. 

In  this  last  case,  the  useful  effect  of  the  engine,  tender  not  included , will  be  null. 

From  these  detailed  examples  is  seen  how  the  calculation  is  to  be  performed  in  all  the  cases ; but  it 
must  be  remarked,  that  with  the  use  of  logarithms,  these  different  trials  present  no  sort  of  difficulty,  and 
that  those  who  have  once  got  the  habit  of  these  researches,  guess  immediately  and  at  a glance,  what 
numbers  they  ought  to  employ  in  the  approximations,  so  that  the  apparent  length  of  the  calculation 
entirely  disappears. 

Collecting  the  results  which  we  have  just  obtained,  calculating  moreover  the  useful  effect  of  the 
engine,  and  expressing  it  under  the  different  forms  already  indicated,  we  form  the  following  Table : 


Effects  of  a locomotive  of  65  cubic  feet  of  vaporization , with  a load  of  56  tons  gross,  on  a level,  tender 

included. 


M = 56  tons  gross,  tender  included,  (10  carriag-js  and  the  tender ;) 

v = 2510  miles  per  hour; 

u.  E = 141 1 tons  gross  drawn  1 mile  per  hour,  tender  included ; 

u.  E.  in  H P =23  horses  ; 

Q.  co.  pr.  t.  pr.  m = -47  lb.  per  ton  gross  per  mile,  tender  not  included ; 

Q.  wa.  pr.  t.  pr.  m.  ...  = -052  cubic  foot  per  ton  gross  per  mile,  tender  not.  included ; 

u.  E.  1 lb.  co = 2-36  tons  gross  drawn  1 mile,  tender  included ; 

u.  E.  1 ft,  wa = 2T70  tons  gross  drawn  1 mile,  tender  included- 

Q.  co.  fr.  1 HP = 26-50  lbs. ; 

Q.  wa.  fr.  1 H P = 2-880  cubic  feet ; 

u.  E.  1 lb.  co.  in  H P.  = -038  horse  ; 
u.  E.  1 ft.  wa.  in  H P.  = -347  horse. 

Maxima  effects  of  the  same  engine. 

M' = 161-5  tons  gross,  tender  included,  (31  carriages  and  tender;) 

v‘  = 16-20  miles  per  hour ; 

u.  E =2616  tons  gross  drawn  1 mile  per  hour,  tender  included ; 

u.  E.  in  H P =42  horses ; 

Q.  co.  pr.  t.  pr.  m.  ...  = -24  lb.  per  ton  gross  per  mile,  tender  not  included ; 

Q.  wa.  pr.  t.  pr.  m.  ...  = -026  cubic  foot  per  ton  gross  per  mile,  tender  not  included ; 

u.  E.  1 lb.  co = 4'38  tons  gross  drawn  1 mile,  tender  included ; 

u.  E.  1 ft.  wa = 40-25  tons  gross  drawn  1 mile,  tender  included  ; 

Q.  co.  fr.  1 H P = 14-29  lbs. 

Q.  wa.  fr.  1 HP = 1-553  cubic  foot; 

u.  E.  1 lb.  co.  in  H P.  = -070  horse  ; 
u.  E.  1 ft.  wa.  in  H P.  = -644  horse. 


To  give  a second  example  of  this  calculation,  we  will  suppose  the  railway  to  have  7 feet  of  width  of 
way,  and  seek  what  will  be  the  velocity  of  the  engines  of  medium  force,  in  use  on  such  a line,  under 
the  same  circumstances  as  we  have  just  examined  relatively  to  a railway  of  about  5 feet  of  width  of  way. 

We  will  suppose  then  a locomotive  of  120  cubic  feet  of  vaporization,  at  the  velocity  of  25  miles  per 
hour,  with  the  following  proportions  : cylinders,  14  inches  or  117  foot  in  diameter ; stroke  of  the  piston, 
16  inches  or  1-33  foot;  wheels,  8 feet  in  diameter,  not  coupled;  weight,  18  tons;  friction,  270  lbs.; 
blast-pipe,  3-14  inches  in  diameter ; total  or  absolute  pressure  in  the  boiler,  80  lbs.  per  square  inch ; and 
consumption  of  coke  in  the  same  time,  1050  lbs.  or  8"75  lbs.  per  cubic  foot  of  water  vaporized.  More- 
over, by  reason  of  the  width  of  the  way,  we  will  take  the  surface  of  the  largest  wagon  of  the  train  at 
100  square  feet,  the  average  surface  of  a wagon  at  56  square  feet,  and  the  weight  of  the  tender  at  10 
tons. 

. Seeking  then  by  the  same  calculation  as  before,  what  effects  this  engine  is  capable  of  producing,  first 
m drawing  a train  of  60  tons  gross,  tender  included,  which  makes  50  tons  without  the  tender  and  after 
wards  in  drawing  its  maximum  load,  we  obtain  the  following  results : 


268 


LOCOMOTIVE  ENGINE. 


Effects  of  a locomotive  of  120  cubic  feet  of  vaporization,  with  a load  of  60  tons  gross,  tender  included 


M = 60  tons  gross,  tender  included,  (7  carriages  and  the  tender ;) 

v = 34'75  miles  per  hour; 

u.  E = 2085  tons  gross  drawn  1 mile  per  hour,  tender  included ; 

u.  E.  in  H P =33  horses; 

Q.  co.  pr.  t.  pr.  m.  ...  = '60  lb.  per  ton  gross  per  mile,  tender  not  included ; 

Q.  wa.  pr.  t.  pr.  m.  ...  = -069  cubic  foot  per  ton  gross  per  mile,  tender  not  included ; 

u.  E.  1 lb.  co = 1-99  ton  gross  drawn  1 mile,  tender  included ; 

u.  E.  1 ft.  wa = 17  38  tons  gross  drawn  1 mile,  tender  included; 

Q.  co.  fr.  1 H P = 31'48  lbs. ; 

Q.  wa.  fr.  1 H P = 3 597  cubic  feet; 

u.  E.  1 lb.  co.  in  H P.  = '032  horse  ; 
u.  E.  1 ft.  wa.  in  H P.  = -278  horse. 

Maxima  effects  of  the  same  engine. 

M' = 147  tons  gross,  tender  included,  (20  carriages  and  the  tender 

v' = 25  55  miles  per  hour; 

u.  E = 3756  tons  gross  drawn  1 mile  per  hour,  tender  included ; 

u.  E.  in  H P =60  horses  ; 

Q.  co.  pr.  t.  pr.  m.  ...  = -30  lb.  per  ton  gross  per  mile,  tender  not  included ; 

Q.  wa.  pr.  t.  pr.  m.  ...  = -034  cubic  foot  per  ton  gross  per  mile,  tender  not  included; 

u.  E.  1 lb.  co = 3'58  tons  gross  drawn  1 mile,  tender  included ; 

u.  E.  1 ft.  wa = 31'30  tons  gross  drawn  1 mile,  tender  included; 

Q.  co.  fr.  1 II  P = 17'47  lbs. ; 

Q.  wa.  fr.  1 H P = 1997  cubic  foot; 

u.  E.  1 lb.  co.  in  H P.  = -057  horse ; 
u.  E.  1 ft.  wa.  in  H P.  = -501  horse. 


The  velocity  of  the  same  engine,  drawing  its  tender  alone,  would  be  43'28  miles  per  hour ; which 
would  be  the  maximum  of  velocity  that  this  engine  could  attain. 

It  is  visible,  in  these  examples,  that  the  above  formulae  present  no  difficulty,  and  that  it  is  merely 
necessary  to  preserve  in  them  the  homogeneity  of  the  measures  employed. 

Practical  formulae,  to  determine  the  proportions  of  locomotive  engines,  according  to  given  conditions.— 
We  will  here  give,  in  their  numerical  form,  all  the  formulae  which  are  essential  for  determining  the  pro- 
portions of  the  engines,  according  to  given  conditions.  For  the  signification  of  the  signs  employed,  wi 
refer  to  page  243  of  this  volume. 


PRACTICAL  FORMULA  TO  DETERMINE  THE  PROPORTIONS  OF  LOCOMOTIVE  ENGINES,  NECESSARY  TO  PRODUCE 

GIVEN  EFFECTS. 


.G  +l)v 
784 


[(6  ± g)  M db  g rn  + u v1  + — ^ ^ (2736  + p'  p)”J  = 


^ [lira*  7 -1 (6  ± g)  M T V m - 11 u*' - IT^]  =■ 


Total  vaporization  of  the  boiler,  in  cubic  feet  of  water  per  hour. 

d==°._i±A 

l 2736  + P 
Square  of  the  diameter  of  the  cylinder,  in  feet. 

, D 1 +5  r ^ S ^ , FT 

d?  2736  +p'v  Ll  + a v v y 1-HJ 


Stroke  of  the  piston,  in  feet. 


D: 


cPl 


2736  + />'  v 


'1  + 6 784  S 


Diameter  of  the  wheel,  in  feet. 


1 -J-  <5  v 


— (6  m - 


i + a 


S = -i-.^.v  (618  + P)  = 

784  D 


Total  vaporization  of  the  boiler,  in  cubic  feet  of  water  per  hour. 

P = (1  + i)jr/[(6±flr)M±flr«  + «*,I+  j-^J+2118+pV. 

Total  or  absolute  pressure  of  the  steam  in  the  boiler,  in  pounds  per  square  foot. 

P =784  — .-,  — 618  = 
d 3 1 v' 

Total  or  absolute  pressure  of  the  steam  in  the  boiler,  in  pounds  per  square  foot 

1 


d2  = 784?.^. 


Square  of  the  diameter  of  the  cylinder,  in  feet. 


I v'  618 + P 


LOCOMOTIVE  ENGINE. 


269 


,=mE  s i _ 

784cf2  V*618  + P 

Stroke  of  the  piston,  in  feet 

d=4-^-I'(618+f)= 

Diameter  of  the  wheel,  in  feet. 


r)  (6  ±<7)M' ±gm  + uvrl  -f 

d * = 7 ' P — 2118—  p'v' 

Square  of  the  diameter  of  the  cylinder,  in  feet. 

D (6±'7)M ' ±gm  + uv'*  + 

1 = (1  + i)  • P — 2118  — pV 

Stroke  of  the  piston,  in  feet. 


F 

r+i  _ 


F 

1+1 


(PI  P — 2118 — p’v' 

(6  ±<j)W  ±gm  + uvn  + — - 

1 T o 

Diameter  of  the  wheel,  in  feet. 


Of  adhesion. — It  has  been  observed,  in  the  description  of  the  engine,  that  the  effort  of  the  steam 
being  applied  to  the  wheel,  the  engine  is  precisely  in  the  case  of  a carriage  which  is  made  to  advance 
by  pushing  at  the  spokes.  Tims,  as  in  this  action  the  only  fulcrum  of  the  mover  is  the  adhesion  of  the 
wheel  to  the  rails,  if  that  adhesion  were  insufficient,  the  force  of  the  steam  would  indeed  make  the 
wheels  turn  ; but  these,  sliding  on  the  rails  instead  of  adhering  to  them,  would  turn  without  advancing, 
and  the  engine  would  remain  on  the  same  spot. 

The  heavier  the  train  to  be  drawn,  the  more  force  the  engine  must  employ,  and  the  more  resistance 
it  must  consequently  meet  with  at  the  point  on  which  it  strains  to  effect  the  motion.  It  might  then  be 
feared  that  with  trains  of  considerable  weight,  the  engines  would  be  unable  to  advance ; not  that  force 
would  be  wanting  in  the  mover  itself,  but  in  the  fulcrum  of  the  mover. 

Adhesion  being  indispensable  to  the  creation  of  the  progressive  motion,  two  conditions  are  requisite 
for  an  engine  to  be  capable  of  drawing  a given  load : 1st,  the  dimensions  and  proportions  of  the  engine 
and  its  boiler  must  enable  it  to  produce,  by  means  of  the  steam,  the  necessary  pressure  on  the  piston, 
which  constitutes  the  force  apjffied  by  the  engine  ; and  2d,  the  weight  of  the  engine  must  be  such  as 
to  cause  a sufficient  adhesion  to  the  rails.  These  two  conditions  of  force  and  weight  should  accord  to- 
gether; for,  were  there  a great  force  of  steam  and  a slight  adhesion,  the  latter  would  limit  the  effect  of 
the  engine,  and  steam  would  be  lost;  and  were  there  too  much  adhesive  weight  for  the  power  of  the 
engine,  that  weight  would,  during  the  motion,  become  a useless  burden,  since  the  limit  of  the  load  would 
then  be  marked  by  the  pressure  of  the  steam. 

It  is  necessary  therefore,  after  having  determined  the  dimensions  of  the  engines  from  the  conditions 
which  they  are  to  fulfil,  as  has  been  done  in  the  preceding  pages,  to  seek  what  ought  to  be  their  weight 
so  as  to  enable  them  to  draw  the  greatest  load  intended  to  be  imposed  on  them  during  their  work. 
The  enormous  weight  now  given  to  locomotive  engines,  generally  causes  this  condition  to  be  fulfilled  of 
itself.  Six-wheel  engines  however  require,  in  this  respect,  more  attention  than  four-wheel  engines,  be- 
cause it  often  happens,  on  an  uneven  railway,  that  a six-wheel  engine  is  wholly  supported  on  its  four 
extreme  wheels,  whereas  the  middle  ones,  which  are  the  propelling  wheels,  being  accidentally  situated 
immediately  above  a low  part  of  the  railway,  scarcely  touch  the  rail,  and  therefore  have  but  a slight 
adhesion.  In  the  best  state  of  the  rails  the  adhesion  which  is  the  limit  of  the  traction  of  an  engine,  may 
be  taken  at  j;  of  the  weight  on  the  driver,  and  it  is  never  less  than  in  the  worst  state  of  the  rails, 
when  they  are  greasy  and  dirty  from  the  effect  of  wet  weather. 

For  the  preceding  calculations  and  formula}  W’e  are  indebted  to  M.  Pambour,  whose  works  on  the 
steam-engine,  both  locomotive  and  stationary,  should  be  in  the  hands  of  every  engineer  and  machinist, 
and  to  which  we  refer  for  a more  complete  elucidation  of  the  laws  which  govern  the  motion  of  this  won- 
derful machine. 

Locomotive  engine  and  tender. — The  example  which  we  have  chosen  for  detailed  illustration  is  the 
form  of  locomotive  engine  and  tender  at  present  constructed  by  Messrs.  Hawthorn,  of  Newcastle,  Eng- 
land, a firm  whose  success  and  extensive  employment  in  this  branch  of  the  trade  is  a sufficient  guarantee 
for  the  excellence  of  their  arrangements.  In  these  figures  are  embodied  all  the  most  recent  improve- 
ments which  Messrs.  Hawthorn  have  introduced  into  their  engine,  including  their  patent  auxiliary  ex- 
pansion-frame, and  the  mechanism  by  which  it  is  moved. 

The  engine  is  made,  according  to  the  method  generally  adopted  by  Messrs.  Hawthorn,  with  a cranked 
axle  and  outside  bearings  ; it  is  furnished  with  six  wheels,  (designated  a six-wheeled  engine  ;)  the  driv- 
ing and  fore  wheels,  which  are  five  feet  in  diameter,  are  coupled  together,  and  the  hind-wheels,  three 
feet  diameter,  are  placed  immediately  below  the  fire-box.  By  this  arrangement  the  greatest  safety  is 
insured,  and  particularly  at  high  speeds ; the  same  amount  of  stability  being  given  to  the  engine  as  if 
the  hind-wheels  were  placed  behind  the  fire-box,  with  this  additional  advantage,  that  the  length  of 
coupling  between  the  wheels  may  by  the  present  disposition,  be  regulated  to  any  convenient  distance. 
An  engine  of  this  description  will  be  found  exceedingly  useful  for  general  purposes,  being  adapted  both 
for  merchandise  and  for  mixed  or  passenger  trains  at  ordinary  speeds ; while  for  express  or  special 


•270 


LOCOMOTIVE  ENGINE. 


trains,  where  a high  rate  of  speed  is  required,  railway  travelling  would  be  rendered  comparatively  safe 
by  employing  engines  specially  made  and  adapted  f<*  such  purposes.  J 

Enumeration  of  the  figures— Fig.  2601,  a longitudinal  elevation  of  the  locomotive  engine 
rig.  2602,  a general  plan  of  the  same.  ° 


Fig.  2603,  a longitudinal  elevation  of  the  tender,  showing  the  mode  of  its  connection  with  tile 
engine. 

Fig.  2604,  a general  plan  of  the  tender,  in  which  are  seen  the  cocks  for  regulating  the  supply  of  wates 
to  the  boiler,  and  the  hand-wheel  for  working  the  brake  apparatus. 

The  following  four  figures  are  sectional  views. 


LOCOMOTIVE  ENGINE. 


271 


Fig.  2605,  a longitudinal  section  of  the  engine,  showing  the  internal  arrangements  of  the  boiler,  and 
the  working  parts  of  the  engine. 

Fig.  2606,  a sectional  plan  of  the  engine,  with  the  cylindrical  part  of  the  boiler  removed,  for  the 
purpose  of  exhibiting  the  general  arrangement  of  the  working  parts,  and  the  construction  of  the 
fire-box. 

Fig.  2607,  a longitudinal  section  of  the  tender. 

Fig.  2608,  a plan  of  the  tender  with  the  tank  removed,  showing  the  construction  of  the  framing,  drag- 
snrinP,  brake-geer,  &c. 


The  following  figures  represent  end  elevations  and  transverse  sections  of  the  engine 
Fig.  2609,  an  elevation  of  the  engine  as  seen  at  the  fire-box  end. 

Fig.  2610,  a transverse  section  through  the  fire-box. 

Fig.  2611,  an  elevation  of  the  engine  as  seen  at  the  smoke-box  end. 

• a fransverse  section  through  the  smoke-box.  In  this  view  the  cylinder  to  the  right  is  sec 

tinned  through  the  steam-passage,  while  that  to  the  right  is  supposed  to  be  cut  through  the  discharge 
port  and  blast-pipe. 


272 


LOCOMOTIVE  ENGINE. 


The  following  figures  represent  detailed  views,  drawn  to  a larger  scale,  of  such  parts  of  the  engine 
and  tender  as  could  not  be  fully  shown  in  combination : 

Fig.  2613,  a transverse  section  of  the  steam  regulator  and  chest;  Fig.  2614,  a longitudinal  section  of 
the  same. 

Fig.  2616,  a plan  of  the  piston,  with  the  cover  removed  to  show  the  packing. 

Fig.  2616,  a section  of  the  piston  through  the  lines  12  3. 

Fig.  2617,  a plan  of  the  same,  complete,  with  the  cover  and  guards. 

Fig.  2618,  a plan  of  the  piston-rod  cross-head,  with  slide-blocks  and  projecting  arm  for  workmg  the 
feed-pump. 


Fig.  2619,  a side  view  of  the  same. 

Fig.  2620,  an  end  view  of  the  same. 

Fig.  2621,  an  elevation  of  the  backward  eccentric. 

Fig.  2622,  a plan  of  the  same,  showing  the  stud  for  working  the  espansion-geer. 

Fig.  2623,  a side  view  of  the  reversing  or  coupling  link. 

Fig.  2624,  an  edge  view  of  the  same,  showing  the  stud  by  which  the  valve  is  shifted  into  forward 
er  back  geer. 

Fig.  2625,  an  elevation  of  the  front  end  of  the  eccentric-rod. 

Fig.  2626,  a plan  of  the  same. 

Fig.  2627,  a longitudinal  section  of  the  feed  pump,  with  the  plunger,  valves,  <fcc. 

Fig.  262S,  an  end  view  of  the  same. 


LOCOMOTIVE  ENGINE. 


273 


Fig.  2629;  a plan  of  the  double  safety-valve,  with  the  seat ; Fig.  2630,  a longitudinal  section  n( 

the  same.  _ . 

Fig.  2631,  an  edge  view  of  the  driving-wheel,  half  in  section,  to  show  the  mode  of  faxing  the  arms, 
tyre,  (fee.  In  this  view  is  also  given  part  of  the  cranked  axle,  to  show  the  lelative  positions  of  the  cianl, 
wheel,  bearing,  die. 


261  IS, 


Fig.  2632,  a transverse  section  of  the  driving-wheel  axle-box,  and  of  part  of  the  outer  spring  Fig 
2633,  a longitudinal  section  of  the  same. 

Fig.  2634,  a section  of  the  suspending  link  for  adjusting  the  weight  of  the  engine  on  the  springs  • Fig 
2635,  a side  elevation  of  the  same. 

2609.  2610.  2611. 


Stora'Affeigr 


Fig.  2636,  a general  elevation  of  the  tender  brake-geer;  Fig.  2637,  a plan  of  the  brake-lever  and 
oothed  sector  ; Fig.  2638,  the  screw  and  link-nut  for  the  tender  brake. 

Description  of  the  engine. — The  fire-box. — The  first  part  of  the  engine  which  claims  our  attention  is 
the  fire-box.  The  form  of  fire-box  which  Messrs.  Hawthorn  have  adopted  is  clearly  shown  in  the  end 
elevation,  Fig.  2609,  aud  transverse  section,  Fig.  2610.  It  consists  of  two  parts : the  external  fire-box  A, 
which  in  reality  forms  part  of  the  boiler,  being  filled  with  water  to  about  fifteen  inches  from  the  top ; 
and  the  internal  fire-box  B,  placed  within  the  other,  and  which  contains  the  fuel  for  generating  steam. 
The  internal  fire-box  is  made  of  copper,  and  tapered  slightly  towards  the  top,  for  the  purpose  of  allow- 
ing the  globules  of  steam  which  are  formed  on  its  sides  to  ascend  more  freely.  To  resist  the  downward 
pressure  of  the  steam,  the  roof  is  strengthened  by  the  strong  malleable-iron  stays  C C bolted  across,  and 
having  a bearing  against  its  sides,  wlule  both  external  and  internal  fire-boxes  are  secured  against  the 
lateral  strain  by  having  numerous  iron  stay-bolts  aaa  screwed  through  both  boxes,  and  riveted  at  each 
end.  The  fire-door  b affords  access  to  the  internal  fire-box  for  the  admission  of  coke.  It  is  of  an  oval 
form,  and  the  latch  is  provided  with  a chain  for  the  greater  convenience  of  opening  and  shutting.  The 
space  between  the  two  fire-boxes  at  that  part  where  the  fire-door  is  situated  is  filled  by  an  oval-shaped 
frame,  securely  riveted  through  both,  and  the  fire-door  itself  is  furnished  with  a plate  of  iron  riveted  to 
the  inside  at  some  little  distance  from  it,  to  save  it  from  warping  by  the  intensity  of  the  heat  within. 
The  fire-bars  cc  distinctly  shown  in  the  section  Fig.  2605,  and  in  the  plan  Fig.  2606,  are  ranged  parallel 
Vol.  II — 18 


274 


LOCOMOTIVE  ENGINE. 


to  each  other  on  a wrought-iron  frame  fixed  to  the  under  side  of  the  fire-box,  and  a portion  of  them 
marked  d in  the  plan,  is  so  arranged  as  to  admit  of  their  falling  at  one  end  on  the  removal  of  the  pin 
which  supports  them.  In  this  case  the  burning  fuel  drops  into  the  ash-box  D fixed  below  to  receive  it, 
and  the  combustion  almost  immediately  ceases. 

The  boiler. — As  before  remarked,  the  external  fire-box  A forms  part  of  the  boiler,  communicating 
freely  with  it,  and  being,  like  it,  filled  with  water  to  the  proper  height  when  the  engine  is  in  operation. 
The  boiler,  properly  so  called,  is  marked  E in  the  figures,  and  in  the  specimen  now  under  notice  consists 
of  a cylinder  11  feet  6 inches  in  length,  and  3 feet  6§  inches  in  diameter  outside.  It  is  traversed 
throughout  its  length  by  107  brass  tubes  eec,  2J  inches  outside  diameter,  of  No.  13  and  14  wire  gage. 

2612.  2614. 


These  tubes  are  inserted  into  the  front  plate  of  the  internal  fire-box,  (called  the  tube-plate ,)  which  is 
made  of  a sheet  of  copper  considerably  thicker  than  the  other  plates  of  which  the  fire-box  is  composed, 
so  as  to  afford  a better  bearing  for  the  fixing  of  the  tubes.  At  the  front  extremity  of  the  boiler,  they 
pass  through  a similar  plate  of  iron,  which  forms  the  partition  between  the  boiler  and  the  smoke-box 
Into  these  plates  the  tubes  are  secured  at  both  ends  by  riveting,  and  subsequently  by  strong  steel  fer- 
rules accurately  turned,  and  driven  firmly  into  the  interior  of  the  tubes,  so  as  to  render  them  perfectly 
tight  and  free  from  leakage.  The  cylindrical  form  of  the  boiler  renders  lateral  staying  unnecessary,  and 
the  tubes  themselves,  at  that  part  where  they  are  situated,  secure  it  against  the  pressure  in  a longitu- 
dinal direction ; but  for  further  safety,  three  strong  malleable-iron  stay-bolts  fff  traverse  the  whole 
length  of  the  boiler,  and  are  secured  to  it  by  round  pins  passing  through  brackets  riveted  to  the  front 
tube-plate,  and  to  the  back  plate  of  the  external  fire-box.  The  whole  boiler  is  covered  externally  with 
a coating  of  thick  felt  and  with  strips  of  wood,  called  the  lagging,  or  clcading,  to  prevent  the  radiation 
of  heat,  as  well  as  to  give  greater  symmetry  of  appearance. 


2619. 


2624.  2623. 


The  smoke-b'ox. — The  tubes  eee  all  open  into  that  part  of  the  boiler  called  the  smoke-box  F,  the  pur- 
pose of  which  is  to  collect  the  gases  evolved  by  the  combustion  of  the  fuel,  and  to  transmit  them  through 
the  chimney  G into  the  air.  In  this  compartment  of  the  boiler  are  also  placed  the  steam  cylinders,  and 
other  very  important  parts  of  the  engine,  to  be  hereafter  described.  The  front  plate  of  the  smoke-box 
is  furnished  with  large  folding-doors  g g , fitted  air-tight  to  it,  and  provided  with  a handle,  by  which  both 
doors  are  simultaneously  shut  and  opened.  These  doors,  which  are  distinctly  shown  in  the  end  eleva- 
tion, Fig.  2611,  and  in  the  section,  Fig.  2605,  serve  to  afford  access  for  the  insertion  and  cleaning  of  the 
tubes,  as  well  as  for  the  examination  and  repair  of  the  parts  of  the  engine  referred  to  above. 

The  safety-valves  and  boiler  mountings. — Although  the  efficient  working  of  the  engine  requires  that 
the  boiler  be  capable  of  generating  steam  of  a high  elastic  force,  it  is  yet  essential  to  safety  that  the 
uteam  pressure  be  confined  within  certain  limits.  In  order  to  insure  this,  the  boiler  is  provided  with 


LOCOMOTIVE  ENGINE. 


I 

275 


two  safety-valves,  li  and  i,  both  placed  in  one  chest,  (Fig.  2629,)  fixed  on  the  summit  of  the  external  fire- 
box,  and  surrounded  by  a polished  brass  chimney  H,  of  a form  symmetrical  with  that  of  the  large  chim- 
ney Gr.  One  of  these  valves,  marked  i,  which  is  of  the  kind  called  the  lever  safety-valve,  can  he  regu- 
lated to  any  required  degree  of  pressure  by  the  engine-driver,  being  furnished  with  a spring-balance,  by 
which  the  amount  of  pressure  is  distinctly  indicated.  The  other  safety-valve  h is  inaccessible,  and  is 
loaded  by  a spiral  spring  and  screws,  to  such  a pressure  as  may  be  considered  safe,  yet  higher  than  the 
engine  is  expected,  under  ordinary  circumstances,  to  require. 


To  indicate  the  height  at  which  the  water  stands  in  the  boiler,  and  to  enable  the  driver  to  keep  it 
always  at  its  proper  level,  a set  of  gage-cocks  and  glass  tube  j,  communicating  with  the  water  inside, 
are  fixed  at  a convenient  situation  near  the  foot-plate.  A graduated  scale  is  fixed  behind  the  glass 
tube,  and  the  required  level  may  thus  be  maintained  with  considerable  accuracy. 

As  a precaution  against  accidents,  and  to  give  notice  of  the  approach  of  the  engine,  a steam  whistle 
k is  attached  to  the  top  of  the  fire-box,  and  communicates  with  the  steam  within  by  a short  pipe,  pro- 
vided with  a stop-cock.  The  internal  construction  of  the  whistle  is  such,  that  when  the  stop-cock  is 
opened,  the  steam  rushing  out  with  great  force  encounters  the  sharp  edges  of  a species  of  inverted  cup, 
thereby  emitting  a shrill  and  very  loud  noise,  which  can  be  heard  at  the  distance  of  several  miles. 


2629.  2632.  2635. 


Behtid,  and  at  the  lowest  extremity  of  the  fire-box,  is  situated  the  blow-off  cock  l,  by  which  the  boiler 
may  be  emptied  of  water  when  required  ; and,  for  the  purpose  of  cleansing  it  of  the  accumulation  of 
sediment  which  is  constantly  being  formed  in  it  when  the  engine  is  in  operation,  it  is  provided  with 
mud-holes  both  at  fire-box  and  smoke-box  ends.  These  mud-holes,  which  are  shown  in  Figs.  2609  i nd 


t 

27  G 


LOCOMOTIVE  ENGINE. 


2612,  are  secured  -when  the  engine  is  at  work,  by  covers  or  doors  bearing  against  the  inside  of  the  boiler 
and  fixed  each  by  a single  bolt  passing  through  a strong  wrought-iron  bridge  bearing  against  the  outside 
The  steam-pipes  and  regulator-valve. — The  steam-chest  or  receiver  I rises  from  the  centre  of  tha 
cylindrical  part  of  the  boiler,  and  is  carried  to  a considerable  height  above  it,  in  order  that  the  mouth 
of  the  steam-pipe  J,  which  opens  into  it,  may  be  removed  to  as  great  a height  as  can  conveniently  be 
obtained,  from  the  surface  of  the  water  in  the  boiler.  The  object  of  thus  raising  the  open  orifice  of  the 
steam-pipe  is  to  prevent  priming,  that  is,  the  ascent  of  water  along  with  the  steam,  and  its  consequent 
flow  through  the  steam-pipe  into  the  cylinders,  where  its  presence  in  any  considerable  quantity  wouid 
produce  the  most  serious  inconveniences,  besides  the  danger  to  which  the  boiler  would  be  exposed  by 
its  rapid  abstraction.  As  a further  precaution  against  priming,  Messrs.  Hawthorn  make  use  of  a simple 
but  very  ingenious  contrivance.  This  consists  of  a species  of  inverted  cone  m,  Fig.  2005,  made  of  sheet- 
iron,  and  riveted  to  the  interior  of  the  steam-chest,  with  an  aperture  in  the  centre  just  wide  enough  tc 
allow  the  free  ascent  of  the  steam  between  it  and  the  steam-pipe,  which  passes  through  it.  The  water 
in  the  boiler  tends  to  prime  chiefly  where  there  is  a surface  of  metal  to  which  it  may  adhere ; conse- 
quently, when,  in  rising  up  the  sides  of  the  steam-chest,  it  encounters  the  inverted  cone  m , its  course  is 
diverted  downwards  and  towards  the  centre,  where  being  unsupported  it  falls  back  into  the  boiler. 
Should  any  priming  occur  round  the  sides  of  the  steam-pipe  itself,  the  water  is,  in  a somewhat  analogous 
way,  diverted  by  the  bell-shaped  mouth  of  the  pipe,  and  returned  into  the  boiler.  The  steam-receiver 
is  surrounded  by  a polished  brass  dome,  which,  besides  being  highly  ornamental  to  the  engine,  serves 
the  very  important  purpose  of  diminishing  the  radiation  of  heat,  by  interposing  a stratum  of  heated  air 
between  the  steam-chest  and  the  external  atmosphere. 


The  steam-pipe  J is  made  of  copper,  and  that  part  of  it  which  is  inclosed  within  the  boiler  is  5J 
inches  internal  diameter.  It  enters  an  orifice  accurately  bored  and  fitted  to  receive  it,  in  the  cast-iron 
regulator-valve  chest  K,  which  is  bolted  steam-tight  to  the  exterior  of  the  front  tube-plate  of  the  boiler. 
The  valve-chest  K incloses  a regulator-valve  n , of  a new  and  improved  form,  which,  as  well  as  the  chest 
itself,  is  shown  on  an  enlarged  scale  in  Figs.  2613,  2614.  It  is  formed  of  cast-iron,  and  has  two  projecting 
faces  accurately  and  smoothly  turned,  and  of  such  form  and  dimensions  as,  when  placed  in  the  position 
shown  in  Fig.  2613,  completely  to  cover  the  orifices  of  the  two  branch  steam-pipes  J J,  whose  faces  are 
bored  truly  cylindrical,  and  of  the  same  diameter  as  that  of  the  faces  of  the  valve.  The  distance  be- 
tween the  contiguous  edges  of  the  two  branch-pipes  is  somewhat  greater  than  the  breadth  of  the  valve 
face,  so  that  when  turned  round  in  either  direction,  the  orifices  of  both  pipes  may  be  fully  opened.  In 
the  centre  of  rotation  of  the  valve  is  an  oblong  hole,  into  which  is  fixed  the  correspondingly  formed  end 
of  a long  rod  o o,  traversing  the  whole  length  of  the  boiler,  and  passing  steam-tight  through  a stuffing- 
box  in  the  back  plate  of  the  fire-box.  A long  lever-handle  p,  is  fixed  to  the  outer  extremity  of  this  rod, 
and  the  engine-driver  is  thereby  enabled,  with  the  greatest  ease  and  precision,  to  regulate  the  supply 
of  steam  to  the  cylinders.  A small  pipe  q,  screwed  into  the  upper  part  of  the  regulator-valve  chest, 
rises  through  the  smoke-box,  and  is  surmounted  by  a cup,  and  provided  with  a stop-cock,  by  which  oil 
may  be  admitted  into  the  interior  of  the  valve-chest,  for  the  lubrication  of  the  working  parts. 

The  two  branch  steam-pipes  J J,  as  will  be  distinctly  seen  by  reference  to  the  transverse  section,  Fig. 
2612,  open  a communication  for  the  admission  of  steam  from  the  regulator-valve  chest  K,  into  the  valve 
casing  or  steam-chest  L L.  They  are  each  3f  inches  internal  diameter,  and  they,  as  well  as  the  dis- 
charge-pipes N N,  are  so  disposed  within  the  smoke-box  as  not  to  obstruct  the  cleaning  or  replacing  of 
’ the  tubes. 

The  cylinders  and  valves. — The  slide-valves,  with  their  expansion-slide  frames,  are  placed  between 
the  cylinders  M M,  in  one  steam-chest  L,  formed  by  the  construction  of  the  cylinders  when  bolted 
together,  as  will  be  seen  by  inspection  of  Fig.  2606.  By  this  arrangement  access  is  afforded  to  both 
valves  by  the  removal  of  only  one  cover,  which  seems  to  be  an  improvement  over  the  other  methods 
row  in  use. 


LOCOMOTIVE  ENGINE. 


2i  i 


The  steam  cylinders  M M are  14  inches  diameter,  with  a stroke  of  21  inches.  They  are  placed  at  a 
slight  angle  in  the  smoke-box,  for  the  purpose  of  being  accommodated  to  the  position  of  the  cranked 
axle.  The  form  and  dimensions  of  the  pistons  P'  P',  and  the  arrangement  of  the  packing-rings  a"  a", 
are  clearly  indicated  in  Pigs.  2615,  2016,  2617.  The  packing  consists  of  two  cast-iron  rings  a"  a", 
turned  slightly  eccentric,  the  thick  sides  in  each  being  set  diametrically  opposite.  At  these  points 
they  are  cut,  and  wedges  b"  b"  fitted  accurately  into  the  openings.  These  wedges  are  pressed  out- 
wards by  two  springs  c"  c",  which  are  adjustable  by  set-sere  ws.  The  whole  is  rendered  compact  and 
secure,  by  the  piston  cover,  d",  which  is  bolted  to  the  body  of  the  piston  by  four  bolts,  guarded  by  the 
pieces  c"  e",  as  shown  in  Fig.  2617. 

The  steam-ports  s s,  which  communicate  between  each  extremity  of  the  cylinders  and  the  slide-valves 
r r,  are  formed  in  the  body  of  the  cylinders,  as  are  also  the  discharge-ports  N N,  to  the  point  where  the 
blast-pipes  are  jointed  to  them.  The  discharge  or  blast  pipes  N N,  ascend  from  each  cylinder  till  they 
reach  the  bottom  of  the  chimney,  where  they  are  formed  into  one  pipe,  in  the  orifice  of  which  is  placed 
a cone  or  tapered  plug  t,  so  disposed  and  connected  by  means  of  a system  of  rods  and  levers  u u,  as  to 
be  capable  of  being  raised  or  depressed  by  the  engine-driver.  By  this  means  the  orifice  of  the  blast- 
pipe  may  be  enlarged  or  contracted  at  pleasure,  thereby  causing  a greater  or  less  draught  to  the  fire. 
By  this  simple  contrivance,  the  engine-driver  is  enabled  to  adapt  the  quantity  of  steam  generated  in 
the  boiler  to  the  exact  amount  required  for  the  supply  of  the  engine,  and  thereby  to  prevent  the  waste 
of  fuel  indicated  by  the  steam  blowing  off  at  the  safety-valve.  For  the  further  regulation  of  the 
draught  when  the  engine  is  at  rest,  it  is  provided  with  a damper  v,  at  the  lower  end  of  the  chimney, 
worked,  like  the  blast  regulator,  by  a system  of  rods  and  levers,  also  marked  v v,  and  terminating  near 
the  foot-plate. 

The  framing  and  connections  of  the  engine. — Having  described  the  internal  arrangements  of  the  en- 
gine, we  now  proceed  to  explain  the  parts  by  which  motion  is  communicated  to  the  wheels.  These  are 
most  fully  and  clearly  delineated,  iu  combination,  in  our  sectional  elevation,  Fig.  2605,  and  in  the  plan, 
Fig.  2606.  Between  the  smoke-box  and  external  fire-box,  are  bolted  the  four  strong  malleable-iron 
beams  OOO,  called  the  imide  framing,  and  which,  besides  imparting  great  strength  and  rigidity  to  the 
whole  structure,  serve  the  purpose  of  giving  fixed  points  of  resistance  for  the  bearings  of  the  working 
parts.  Of  these,  the  first  that  claim  our  attention  are  the  piston-rods  P P.  These  are  made  of  steel, 
turned  truly  cylindrical  and  smooth,  and  of  the  diameter  of  2 J inches ; they  are  fixed  into  the  piston 
with  a cotter  in  the  manner  indicated  in  the  detail,  Figs.  2615,  2616,  and  at  the  opposite  extremity  they  are 
terminated  each  by  a cross-head  Q',  also  attached  to  them  by  a cotter,  Fig.  2618.  On  these  cross-heads 
are  bearings  for  the  small  ends  of  the  connecting-rods  Q Q ; and  concentric,  and  of  the  same  piece  with 
these  bearings,  are  projecting  arms  into  which  the  cast-iron  guide-blocks  ww,  Figs.  2618,  2619,  are  fitted. 
The  guide-blocks  are  formed  with  flanges,  and  are  accurately  fitted  and  ground  into  steel  slide-bars, 
also  marked  w w,  so  as  to  work  smoothly  and  steadily  between  them.  These  latter  are  set  truly  par- 
allel  and  in  the  same  inclined  plane  with  the  centre  of  the  piston-rods,  and  are  firmly  bolted  to  the 
framing-plates  O 0.  By  this  means,  the  piston-rods  are  constrained  to  'move  in  a rectilinear  direction, 
and  secured  against  any  deflection,  or  undue  strain  arising  from  the  continual  change  of  position  of  the 
opposite  ends  of  the  connecting-rods,  in  obedience  to  the  revolution  of  the  cranks  to  which  they  are 
respectively  attached. 

The  feed-pumps  S S,  for  the  supply  of  water  to  the  boiler,  are  also  set  in  the  line  of  the  piston-rods 
and  their  plungers  jrartake  of  their  motion,  being  each  fixed  to  a small  arm  x,  firmly  secured  by  a cot- 
ter to  the  cross-head  Q'.  The  pumps,  the  internal  arrangement  of  which  is  fully  shown  in  the  longi- 
tudinal section,  Fig.  2627,  are  formed  of  cast-iron,  and  are  firmly  fastened  to  the  inside  framing  O,  by 
bolts  passing  through  the  projecting  flanges  f" f".  The  plungers  g"  are  of  brass,  two  inches  in  diam- 
eter, and  at  each  stroke  of  the  engine  draw  the  water  from  the  tender  through  the  feed-pipe  y,  and 
lower  or  suction  valve  h",  forcing  it,  at  the  return  stroke,  through  the  upper  or  delivery  valve  i",  and 
along  the  pipe  z,  into  the  boiler.  The  valves  are  prevented  from  rising  out  of  their  seats  by  the  stops 
j"j",  fixed  into  the  covers  of  their  respective  chests,  and  so  adjusted  as  to  admit  of  their  rising  only  to 
the  proper  height  for  the  due  ingress  and  egress  of  the  water.  At  the  point  where  the  water  is  dis- 
charged into  the  boiler  is  placed  a valve-box  a',  within  which  is  a valve  opening  upwards,  for  the  re- 
tention of  the  water  within  the  boiler.  A small  cock,  called  the  pet-cock,  o,  is  fixed  to  the  outside  of 
‘ be  feed-pump,  and  by  means  of  a long  slender  rod,  the  handle  is  brought  within  reach  of  the  engine- 
iriver,  so  that  he  may  be  enabled  to  ascertain  at  any  time  whether  the  pump  is  working  efficiently. 

The  connecting-rods  Q Q are  jointed,  as  we  have  before  explained,  to  the  cross-heads  of  the  piston- 
rods.  The  coupling  is  effected  in  the  usual  way,  by  means  of  straps,  gibs,  and  cotters,  properly  secured 
against  relaxing  or  falling  out.  The  opposite  ends  are  attached  in  the  same  manner  to  the  cranks  R R, 
upon  the  axle  of  the  driving-wheels.  This  cranked  axle  is  made  of  the  best  forged  iron,  the  cranks  being 
cut  out  of  the  solid  mass,  and  the  one  formed  exactly  at  right  angles  to  the  other.  In  the  earlier  stages 
of  the  locomotive  engine,  it  was  usual  to  provide  bearings  for  the  cranked  axle  upon  each  of  the  frames 
O 0,  but  this  practice  is  now  discontinued,  and  thereby  the  machinery  is  much  simplified,  and  the  fric- 
tion considerably  reduced. 

The  eccentrics  and  valve  geer. — This  engine  is  provided  with  four  eccentrics,  two  for  the  forward, 
and  the  other  two  for  the  backward  geer.  The  form  ar.d  dimensions  of  these  are  shown  upon  an 
enlarged  scale  in  Fig.  2621,  which  gives  a view  of  one  of  the  backward  eccentrics,  but  which,  with 
a slight  difference,  presents  an  accurate  type  of  the  whole  set.  Each  eccentric  is  formed  in  halves, 
for  the  purpose  of  embracing  the  axle,  and  these  are  joined  immovably  together  by  the  two 
round  pins  k"  k",  screwed  into  one  half,  and  secured,  after  passing  through  the  other,  by  cotters 
It  is  fixed  firmly  to  the  axle  by  the  two  pointed  set-screws,  l"  l".  The  forward  eccentrics  for  both 
cylinders  are  fixed  upon  the  axle  a little  in  advance  of  a line  at  right  angles  to  their  respective 
cranks,  for  the  purpose  of  giving  the  required  lead,  and  the  position  of  the  backward  eccentrics 
is  adjusted  upon  the  same  principle,  though  of  course  in  a diametrically  opposite  direction.  The 


278 


LOCOMOTIVE  ENGINE. 


eccentric-rods  m"m",  are  bolted  firmly  to  the  brass  strap  surrounding  the  eccentrics;  and  their  oppo 
site  extremities,  the  form  of  which  is  shown  in  Fig.  2625,  are  connected  together  by  a double  link  e' 
Figs.  2623  and  2624,  so  formed  as  to  admit  of  either  forward  or  backward  eccentric  being  thrown 
into  geer  with  the  valve-spindle,  as  may  be  required.  The  link  which  Messrs.  Hawthorn  employ 
for  coupling  the  ends  of  their  eccentric-rods  is  of  a new  and  improved  construction,  being  so  formed 
as  to  diminish  as  much  as  possible  the  friction  and  wear  upon  the  slide-rod  pin  and  the  eccentric- 
rod  ends.  The  reversing  geer,  or  mechanism  by  which  the  engine-driver  is  enabled  to  propel  the  en- 
gine in  either  direction,  consists  of  a system  of  rods  and  levers  f'f'f,  commencing  with  a stud 
upon  the  lower  extremity  of  the  coupling-link  e‘,  and  terminating  in  a long  handle,  placed  in  a 
convenient  position  near  the  foot-plate.  The  motion  of  the  eccentrics  is  communicated  directly  tc 
the  slide-valves  by  means  of  valve-spindles,  working  through  oblong  guides  at  the  one  extremity,  to 
insure  steadiness,  and  attached  at  their  opposite  ends  to  the  slide-valves  by  nuts  and  jam-nuts,  for 
the  purpose  of  adjustment.  We  may  here  take  occasion  to  remark,  in  anticipation  of  the  subject  upon 
which  we  are  now  about  to  enter,  that  by  Messrs.  Hawthorn’s  arrangement  the  ordinary  slide-valves, 
when  once  properly  adjusted,  never  require  to  be  varied,  to  whatever  extent  the  expansion  geer  may 
be  employed. 

Auxiliary  expansion  slide-frame  and  geering. — On  each  of  the  backward  eccentrics  is  fixed  a stud 
h',  Fig.  2621,  to  which  is  jointed  a rod,  the  other  extremity  of  which  is  connected  with  the  upper  arm 
of  a double  lever,  working  upon  a bearing  fixed  to  one  of  the  framing-beams  0 O.  The  lower  arm  of 
this  lever  is  grooved  throughout  its  length  to  receive  a sliding-pin,  attached  by  a link  to  a system  of 
rods  and  levers,  terminating  in  a long  handle,  working  on  the  same  centre  with  the  reversing  handle. 
The  sliding-pin  is  also  connected  by  the  rod  to  the  hollow  spindle  which  works  through  the  stuffing-box 
of  the  valve-chest  L,  and  incloses  the  spindle  g of  the  ordinary  slide-valve.  It  may  here  be  remarked, 
as  objections  may  be  urged  on  the  ground  of  expense,  that  the  hollow  spindle  is  not  essentially  requisite 
in  this  arrangement  of  valves ; the  spindle  may  be  made  solid,  similar  to  the  rod  of  the  ordinary  slide, 
and  worked  through  a separate  stuffing-box,  either  above  or  on  one  side  of  it ; the  mode  represented  is, 
however,  the  neatest  and  most  compact  arrangement. 

The  expansion  slide-frame  is  worked  by  the  hollow  spindle,  being  attached  to  it  by  means  of  a 
slender  malleable  iron  frame,  embracing  it  on  all  sides,  and  screwed  to  the  end  of  the  hollow  spindle. 
It  is  fitted  to  and  works  upon  the  same  face  as  the  ordinary  slide-valve,  but  is  cf  such  a form  as,  when 
the  frame  is  in  motion,  to  overlap  alternately  the  ends  of  the  latter,  (the  back  of  the  slide-valve  being 
accurately  planed  and  fitted  for  that  purpose,)  according  to  the  amount  of  expansion  required.  This 
can  be  varied  at  pleasure  by  the  mechanism  above  described ; for  when  the  sliding-pin  which  works  in 
the  grooved  arm  is  brought  into  the  centre  of  motion  of  that  lever,  it  is  obvious  that  no  motion  of  the 
slide  frame  will  ensue,  and  in  this  position,  when  it  is  not  required  to  work  expansively,  the  geering  may 
be  secured  so  as  to  obviate  all  unnecessary  wear  and  tear.  If,  however,  the  handle  be  advanced 
into  the  position  represented  in  the  general  elevation,  Fig.  2601,  the  sliding-pin  and  rod  l',  which  is 
attached  to  it,  will  then  be  forced  downwards,  as  shown  in  Fig.  2605,  and  the  slide-frame  will  partake 
of  the  motion  communicated  to  the  lever  i'  by  the  backward  eccentric,  and  the  amount  of  this  travel 
will  obviously  be  in  proportion  to  the  distance  at  which  the  sliding-pin  is  set  from  the  centre  of  motion. 
A graduated  sector  is  placed  at  the  foot-plate  in  view  of  the  engine-driver,  as  shown  in  the  general 
elevation,  for  the  purpose  of  indicating  minutely  the  amount  of  expansion,  or  at  what  part  of  the  stroke 
the  steam  is  cut  off. 

W" e may  remark  that  Messrs.  Hawthorn’s  expansion  geer  appears  to  possess  advantages  over  many 
of  the  other  methods  hitherto  employed.  The  first  and  perhaps  the  most  important  of  these  we  have 
before  adverted  to,  namely,  the  complete  independence  of  the  motion  of  the  ordinary  slide-valve  from 
that  of  the  expansion-frame,  rendering  any  alteration  of  the  latter,  after  it  has  been  once  properly 
adjusted,  unnecessary,  whatever  amount  of  expansion  may  be  employed.  The  admission  and  discharge 
of  the  steam  are  thus,  in  all  cases,  regular,  and  take  place  under  the  most  advantageous  circumstances 
attainable  by  the  ordinary  valve.  Again,  the  movement  communicated  by  the  backward  eccentric  to 
the  expansion-slide  is  so  regulated,  in  relation  to  that  of  the  ordinary  valve,  as  to  produce  a very  pecu- 
liar and  advantageous  effect  in  catting  off  the  steam  quickly.  Thus,  the  expansive  principle  may  be 
employed  to  any  extent,  between  that  due  to  the  cutting  off  of  the  steam  at  g of  the  stroke  of  the  piston, 
to  that  which  would  be  produced  by  the  action  of  the  ordinary  slide  alone,  without  throttling,  or  what 
is  technically  called  wire-drawing  the  steam,  a defect  so  much  complained  of  in  most  of  the  other  modes 
of  expansion  hitherto  in  use.  These  theoretical  advantages  have  been  fully  corroborated  by  the  results 
of  experience.  Messrs.  Hawthorn  have  successfully  applied  their  expansion  geering  to  the  locomotives 
which  they  have  supplied  to  ten  different  railways  in  England,  and  the  saving  of  fuel  effected  by  the 
use  of  it,  in  many  cases,  amounts  to  30  per  cent. 

The  wheels  and  outside  framing. — The  driving-wheels  TT  arc  firmly  fixed  to  the  cranked  axle,  the 
ends  of  which,  produced  beyond  the  bearings,  carry  the  cranks  and  coupling-rods  o o'.  The  other 
extremities  of  these  rods  are  connected  by  cranks  of  exactly  the  same  dimensions  with  the  axle  of  the 
fore-wheels  U U.  By  thus  connecting  the  driving  and  fore  wheels,  the  amount  of  traction,  or  the  sur- 
face upon  the  rails  available  for  the  propulsion  of  the  engine,  is  greatly  increased,  which  renders  this 
species  of  engine  peculiarly  suitable  for  drawing  merchandise  or  other  heavy  trains,  at  moderate  speeds. 
The  hind  or  trailing  wheels  V Y,  are  situated  under  the  fire-box,  and  the  advantages  of  this  disposition 
have  been  already  pointed  out.  The  dimensions  of  all  these  wheels  have  also  been  already  given,  and 
the  mode  of  their  construction  will  be  clearly  understood  by  reference  to  Fig.  2631,  which  shows  both 
external  and  sectional  views  of  one  of  the  driving-wheels,  but  which,  as  far  as  regards  construction,  may 
be  taken  as  a type  of  the  whole.  The  navs  is  of  cast-iron,  moulded  and  poured  round  the  arms,  which 
have  been  previously  prepared  with  a dove-tail  at  their  inner  ends,  for  the  purpose  of  giving  additional 
security.  The  arms  and  rim  are  of  the  best  forged  iron,  and  the  latter  is  accurately  turned  in  the  laths* 


LOCOMOTIVE  ENGINE. 


27h 


after  being  welded  together.  The  tyre,  which  is  also  of  the  best  forged  scrap-iron,  is  bored  internals 
to  a slightly  smaller  diameter  than  the  rim,  and  shrunk  on.  It  is  then  secured  to  the  rim  by  a few 
rivets,  and  the  whole  turned  accurately  to  the  proper  form  and  diameter. 

As  the  whole  weight  of  the  engine  rests  upon  the  wheels,  it  may  be  expected  to  suffer  from  jolting 
in  passing  over  the  irregularities  of  the  rails.  To  obviate  this  as  far  as  possible,  the  springs  p p p and 
q q q are  interposed,  the  former  upon  bearings  in  the  outermost  of  the  internal  framings  0 O,  and  tin- 
latter  under  the  axle-boxes  r r r,  of  the  main  external  bearings.  The  springs  marked  q q',  and  the 
mode  in  which  they  are  attached  to  the  axle-boxes  and  to  the  framing,  are  clearly  represented  in  Figs 
2634  and  2635.  They  are  composed  of  thin  layers  of  steel,  gradually  diminishing  in  length  from  the 
centre  to  the  extremities,  and  bound  together  by  the  connecting-hoop  o",  secured  in  its  place  by  a small 
round  pin  passing  through  it  and  the  steel  plates.  The  connecting-hoop  is  formed  with  a tail  projecting 
upwards  into  the  lower  portion  of  the  axle-box,  where  it  is  fixed  by  a round  pin  p"  passing  through  it. 
The  axle-box  r,  which  is  of  cast-iron,  fitted  with  bearings  composed  of  a metallic  alloy  favorable  for 
Jie  reduction  of  friction,  slides  up  and  down  as  the  springs  bend  with  the  weight  of  the  engine, 
oetween  the  cast-iron  axle-guides  q"  q",  which  are  accurately  planed  and  fitted  to  receive  it,  and 
bolted  firmly  to  the  plates  of  the  external  framing.  The  axle-boxes  are  formed  with  a sort  o; 
reservoir  for  oil  or  tallow,  which  is  constantly  supplied  to  the  rubbing  surfaces  by  two  small  tubes 
and  siphon-wicks.  It  may  here  be  remarked,  that  the  other  rubbing  parts  of  the  engine  are  lubri 
cated  in  the  same  manner.  The  mechanism  by  which  the  springs  are  attached  to  the  external  framing 
is  shown  in  Figs.  2634,  2635.  These  parts  are  called  the  spring-links,  and  consist  of  a species  of 
small  cross-head  r",  fitted  with  round  pins  for  passing  through  the  plates  of  the  external  framing,  and 
with  screwed  studs  attached  by  similar  round  pins  to  the  ends  of  the  springs  q'  q.  The  nut  s"  works 
into  these  screws,  and  by  means  of  it  the  weight  which  it  may  be  thought  expedient  to  throw  upon 
each  spring  may  be  accurately  adjusted. 

The  external  framing  consists  of  two  strong  parallel  beams  W W,  extending  somewhat  beyond  the 
engine  at  both  ends,  and  connected  in  front  by  the  wooden  cross-beam  or  buffer-bar  Z,  and  behind  by  a 
similar  beam,  on  which  rests  the  foot-plate  Y.  These  beams  are  firmly  bound  together  at  the  corners 
by  angular  plates  of  iron  bolted  through  each,  and  the  weight  of  the  boiler  is  supported  upon  them 
by  the  strong  malleable  iron  brackets  or  stays  N N X,  riveted  to  the  boiler,  and  bolted  through 
the  beams  W W.  These  latter  are  formed  each  of  two  parallel  plates  of  iron,  cut  out  into  the 
form  shown  in  the  general  elevation,  with  horns  projecting  downwards  for  the  bearings  of  the 
wheels.  Between  each  pair  of  plates  a beam  of  well-seasoned  oak  is  interposed,  and  the  whole  firmly 
bolted  together. 

To  deaden  the  shocks  to  which  the  engine  is  exposed,  it  is  provided  with  buffers,  s'  s',  fixed  to  and 
projecting  in  front  of  the  buffer-bar  Z.  These  buffers  are  a species  of  elastic  cushions,  formed  of  horse- 
hair, surrounded  by  strong  leather,  and  further  strengthened  by  slender  malleable  iron  hoops.  To 
secure  the  engine  against  the  effects  of  the  wheels  coming  in  contact  with  stones  or  other  obstacles 
which  may  happen  to  be  lying  ou  the  rails,  it  is  furnished  with  strong  malleable  iron  safe-guards  t' t', 
descending  from  the  external  framing  to  within  a short  distance  of  each  rail,  and  so  formed  at  the  points 
as  to  turn  aside  any  object  with  which  they  may  come  into  collision. 

Any  water  which  may  happen  to  accumulate  in  the  cylinders,  whether  from  the  priming  of  the  boiler 
or  the  condensation  of  the  steam,  and  which,  unless  removed  from  time  to  time,  would  be  very  detri- 
mental to  the  working  of  the  engine,  is  let  off  by  means  of  the  pipe  and  stop-cock  xi,  communicating 
with  the  discharge  passage  of  each  cylinder. 

Upon  the  front  of  the  smoke-box,  and  towards  the  top,  is  fixed  a small  bracket  for  supporting  the 
signal-lamp  v\  by  which  notice  is  given  at  night  of  the  approach  of  the  engine  and  train. 

As  a precaution  against  accident  to  the  engine-driver  and  his  assistant,  hand-rails  w'  to'  are  erected 
on  each  side  of  the  foot-plate  Y,  and  these  are  continued  along  the  whole  length  of  the  boiler,  so  that 
they  may  be  enabled  with  comparative  safety  to  walk  round  the  engine,  even  when  it  is  in  rapid  motion. 
The  rods  forming  this  latter  part  of  the  hand-rail  are  made  hollow,  and  thus  afford  a neat  and  compact 
guide  and  protection  for  the  slender  rods  by  which  the  blast  regulator  on  one  side,  and  the  damper  on 
the  other,  are  worked. 

When  the  engine  is  at  rest,  the  steam  which  would  otherwise  escape  at  the  safety-valve  and  be 
thrown  to  waste,  is  made  available  for  the  heating  of  the  water  in  the  tender.  This  is  accomplished  by 
means  of  the  bent  pipe  x',  by  which  a communication  is  made  between  the  steam  within  the  fire-box 
and  the  feed-pipe  y,  and  thereby  a considerable  saving  of  fuel  is  found  to  be  effected. 

The  connection  of  the  engine  and  tender  is  made  by  means  of  the  strong  double  link  or  drag-bar  y'. 
one  end  of  which  is  secured  by  a strong  pin  to  a bracket  fixed  under  the  foot-plate  of  the  engine,  while 
the  other  is  in  a similar  manner  jointed  to  the  drag-springs  of  the  tender. 

_ To  assist  the  engine-driver  in  rising  into  his  place  on  the  foot-plate,  the  foot-steps  z'  z'  depend  on  each 
side  of  it  to  within  an  easy  distance  from  the  ground. 

Having  thus  minutely  described  the  parts  of  which  this  engine  is  composed,  and  explained  their  sev- 
eral uses  as  we  went  along,  we  consider  it  unnecessary  to  occupy  more  space  with  an  account  of  its 
mode  of  action.  This  is  in  every  respect  identical  with  that  of  the  ordinary  high-pressure  engine,  and 
to  those  who  have  followed  us  in  our  previous  descriptions  will  be  perfectly  intelligible. 

Description  of  the  tender. — The  tender  is  an  invariable  concomitant  of  the  locomotive  engine,  and  as 
in  it,  as  well  as  in  the  engine,  there  is  considerable  room  for  the  display  of  tasteful  design  and  judicious 
arrangement,  we  have  thought  that,  we  should  render  our  engravings  more  interesting  and  more 
acceptable  by  giving  representations  of  both.  The  water-tank  A A forms  the  principal  part  of 
the  tender,  and  consists  of  a rectangular  sheet-iron  cistern,  capable  of  contaiuog  1200  gallons  oi 
water  for  the  supply  of  the  boiler.  It  is  made  with  a long  recess  B for  Ihe  reception  of  the 
fuel.  The  floor  a of  this  recess  is  made  with  a slope  downwards  from  the  front  of  the  tender,  bj 


280 


LOCOMOTIVE  ENGINE. 


■which  arrangement  the  fuel  is  prevented  from  being  thrown  out  by  any  jolting  or  shaking  to  which  it 
may  be  subjected. 

Towards  the  back  of  the  tank  it  is  surmounted  by  a pipe  or  opening  C,  by  which  water  is  introduced 
from  the  water-crane  or  other  contrivance  for  that  purpose.  A wooden  cover  is  fitted  over  this  opening 
when  not  in  use.  At  the  same  point  are  fixed  the  wooden  tool-boxes  D D for  containing  spanners  and 
other  implements  which  may  be  required  for  the  engine.  At  the  front  of  the  tank,  and  on  each  side,  are 
situated  the  cocks  b b for  regulating  the  supply  of  water  to  the  suction-pipes  c c communicating  between 
the  feed-pumps  and  the  tender.  These  are  connected  to  the  feed-pipes  y y by  means  of  leather  hose 
screwed  on  to  each  by  the  union-joints  d d,  thus  admitting  of  a considerable  amount  of  vibration  or 
change  of  position  of  the  pipes,  without  breaking  the  connection.  The  tank  is  secured  to  a strong 
wooden  frame  E E,  forming  the  body  of  the  tender,  and  strengthened  by  numerous  cross-beams.  Be- 
yond this  wooden  framing,  and  on  each  side  of  it,  the  external  iron  framing-plates  F E are  fixed  by  bolts 
passing  through  short  cross-beams  of  timber  eee  abutting  against  both.  The  external  framing-plates 
are  made  of  a form  symmetrical  with  those  of  the  engine,  as  seen  in  the  general  elevations,  Figs.  2601 
and  2603,  and  their  purpose  is  to  afford  bearings  for  the  reception  of  the  axle-boxes///,  which  slide  up 
and  down  in  them  in  obedience  to  the  action  of  the  springs  g g g. 

The  tender  is  supported  upon  six  wheels  G G G,  of  the  same  diameter  as  the  trailing  or  hind  wheels 
of  the  engine,  and  constructed  in  the  manner  already  described  in  treating  of  the  latter.  The  brake 
apparatus,  which  is  shown  on  an  enlarged  scale  in  Fig.  2636,  consists  of  a train  of  mechanism  by  which 
a great  amount  of  friction  can  be  simultaneously  produced  upon  the  peripheries  of  the  tender-wheels, 
for  the  purpose  of  reducing  the  momentum  of  the  engine  and  train,  when  it  is  required  to  arrest  the  mo- 
tion of  the  train.  The  hand-wheel  h is  fixed  to  the  upper  extremity  of  the  vertical  spindle  H,  working 
in  a strong  bearing  attached  to  the  tank.  The  lower  portion  of  the  spindle  is  formed  into  a screw,  and 
works  through  the  wrought-iron  nut  I,  on  which  is  forged  a double  link,  jointed  at  its  lower  end  to  the 
brake-lever  i.  The  latter  has  its  centre  of  motion  in  the  short  shaft  J,  which  works  in  strong  bearings 
attached  to  the  wooden  frame,  and  carries  the  double-toothed  sector/  Two  longitudinal  iron  rods  kk 
extend  the  whole  length  of  the  tender,  and  a small  portion  of  each  towards  the  front  extremity  is  formed 
into  a rack,  so  adjusted  as  to  work  into  the  teeth  of  the  sector/  The  rods  k k are  supported  and  guided 
in  their  motion  by  small  rollers  working  in  the  wrought-iron  guides  1 1 1,  and  upon  them  are  bolted  the 
wooden  brake-blocks  m in  in,  by  the  contact  of  which  with  the  exterior  surface  of  the  wheels  the  friction 
is  produced.  By  this  arrangement  it  is  obvious  that  by  screwing  the  vertical  spindle  H into  the  nut  I, 
the  latter  will  be  drawn  upwards,  and  carrying  with  it  the  lever  i,  the  toothed  sector  j will  be  made  to 
revolve  upon  its  axis  J,  and  consequently  the  rods  k k will  be  drawn  each  in  the  opposite  direction  to 
the  other.  Each  wheel  will  therefore  be  forcibly  compressed  between  the  brake-blocks  mm,  and  the 
engine  and  train  be  proportionally  retarded. 

At  the  point  where  the  engine  is  connected  to  the  tender,  the  latter  is  provided  with  a system  of 
springs,  to  deaden  the  effects  of  shocks  from  either  direction.  This  consists  of  two  springs  set  back  to 
back,  and  connected  together  by  a socket  n,  which  receives  the  end  of  the  drag-bar.  The  fore  spring  p 
comes  into  action  when  any  force  is  applied  tending  to  separate  the  engine  from  the  tender,  as  in  start- 
ing a train,  and  the  hinder  spring  o when  the  force  is  applied  in  the  opposite  direction.  Both  springs 
are  supported  upon  pieces  of  thin  iron  bolted  between  the  beams  of  the  wooden  frame,  and  the  extrem- 
ities of  the  spring  o bear  upon  the  two  guide-pins  q q. 

For  further  security,  in  case  of  the  ordinary  connections  failing,  the  safety-chains  r r are  attached  be- 
tween the  engine  and  tender. 

For  the  accommodation  of  the  engine-man  and  fireman,  or  stoker,  the  tender  is  furnished  with  foot- 
steps s s,  placed  at  an  easy  distance  above  the  steps  of  the  engine.  By  these  arrangements,  and  with 
the  assistance  of  the  handles  1 1,  the  foot-plate  is  rendered  easily  accessible. 

At  the  front  of  the  tender  a piece  of  boiler-plate  u is  fixed  by  hinges,  for  the  purpose  of  forming  a 
floor  where  the  engine  and  tender  are  connected.  At  the  other  extremity  of  the  tender  the  buffers  v v, 
similar  in  construction  and  in  situation  to  those  formerly  described,  are  fixed  to  the  cross-beam  of  the 
wooden  framing,  for  the  purpose  of  deadening  the  shocks  produced  by  the  occasional  irregularities  of 
motion  between  the  engine  and  the  train.  The  drag-chain  w,  which  is  firmly  secured  to  the  same  beam, 
forms  the  connecting  link  between  the  tender  and  the  train. 


Literal  References  to  the  Engine. 


A,  the  external  fire-box. 

B,  the  internal  fire-box. 

0 C,  stays  for  strengthening  the  roof  of  the  internal 
fire-box. 

a a a,  stays  between  the  external  and  internal  fire- 
boxes. 

b,  the  fire-door. 
c c,  the  fire-bars. 

i,  the  movable  portion  of  the  fire-bars. 

D,  the  ash-box. 

E,  the  cylindrical  part  of  the  boiler. 
eee,  the  tubes. 

ff  longitudinal  stays  from  the  back  of  the  fire-box 
’ to  the  front  of  the  boiler 

F,  the  smoke-box. 

n g,  the  smoke-box  doors. 


G,  the  chimney. 

H,  a brass  funnel  for  inclosing  the  safety-valves. 

h,  the  spring  safety-valve. 

i,  the  lever  safety-valve  and  spring-balance. 

/ the  water-gage,  and  gage-cocks. 

k,  the  steam-whistle. 

I,  the  blow-off  cock. 

l,  the  steam-receiver. 

in,  the  inverted  cone  for  preventing  priming. 

J J,  the  steam-pipes. 

K,  the  regulator  valve-chest. 

n,  the  regulator  valve. 

o,  a rod  connecting  the  regulator  valve  with 

p,  the  handle  for  working  it. 

q,  the  oil-cup  and  pipe  for  lubricating  the  regulator 
valve. 


LOCOMOTIVE  ENGINE. 


281 


L,  the  steam-chest  of  the  cylinders, 
r r,  the  slide-valves. 

M M,  the  steam-cylinders, 
s s,  the  steam-ports. 

N N,  the  discharge-ports  and  blast-pipes. 
t,  the  blast-regulator. 

u u,  handle,  rods,  and  levers  for  working  the  blast- 
regulator. 

v v,  the  damper,  with  the  handle,  rods,  and  levers 
for  working  it. 

O O,  the  inside  framing  of  the  engine. 

P',  the  steam-piston, 
a"  a",  the  packing-rings  of  the  piston. 
b”  b",  wedges  for  tightening  the  packing. 
c"  c",  springs  bearing  on  the  back  of  the  wedges 
b"b". 

d",  the  piston-cover. 

' e",  guards  for  the  bolts  of  the  piston-cover. 

P P,  the  piston-rods. 

Q'  Q',  cross-heads  for  the  piston-rods. 
w w,  the  cross-head  slides. 

x x , projecting-arms  for  working  the  feed-pumps. 

Q Q,  the  connecting-rods. 

R,  the  cranked  axle. 

S S,  the  feed-pumps. 

f"  f",  flanges  for  bolting  the  feed-pumps  to  the  in- 
side framing. 

g''  g",  the  plungers  of  the  feed-pumps. 
h",  lower  or  suction  valve  of  the  feed-pump. 
i",  upper  or  delivery  valve. 
j"j",  stops  for  regulating  the  lift  of  the  valves. 
yy,  the  feed-pipes  from  the  tender  to  the  feed- 
pumps. 

z z,  branch-pipes  from  the  feed-pumps  to  the  boiler. 
a'  a',  valve-boxes  at  the  boiler. 
b‘  b',  the  pet-cocks  and  their  handles, 
o'  o',  the  forward  eccentrics. 
d' d',  the  backward  eccentrics. 
k"  k",  bolts  for  connecting  the  halves  of  each  ec- 
centric. 

I"  l",  steel  pinching-screws  for  fixing  the  eccentrics 
to  the  axle. 

m"  in",  the  eccentric-rods. 

e'  e' , coupling  links  for  the  ends  of  the  eccentric- 
rods. 

levers,  shafts,  and  rods  for  working  the  re- 
versing-geer. 

Literal  Rcferen 

A,  The  water-tank. 

B,  the  recess  for  containing  the  coke. 
a a,  the  floor  of  the  coke-box. 

C,  the  opening  into  the  tank. 

D D,  the  tool  boxes. 

b b,  the  cocks  for  regulating  the  supply  of  water  to 
the  feed-pumps. 

c c,  water  or  suction  pipes  to  the  engine. 
dd,  union-joints  for  connecting  the  feed-pipes. 

E E,  wooden  frame  of  the  tender. 
e e,  stays  between  the  wooden  and  iron  frames. 

F F,  the  iron  frame  for  receiving  the  axle- 
boxes. 

fff  the  axle-boxes. 
g g g,  the  springs. 

GG6,  the  wheels. 

H,  the  vertical  spindle  and  screw  for  working  the 
brake. 

h,  the  hand-wheel  for  the  brake-screw. 


g'  g',  the  main  steam-valve  spindles. 
h’  h',  studs  on  the  backward  eccentrics  for  working 
the  expansion  slide-frames. 
n"  n ",  connecting-rods  between  the  studs  h'  h' 
and 

V i',  the  grooved  arms  for  the  variable  expansion. 
j’j',  links  between  the  grooved  arms  and  the  lev- 
ers k’  k'. 

k'  k'  k' , levers,  shafts,  and  rods  for  regulating  the 
expansion-geer. 

V l',  connecting-rods  between  the  grooved  arma 
i'  i',  and 

m' m',  the  hollow  spindles  attached  to 
n'  n' , the  expansion  slide-frames. 

T T,  the  driving-wheels. 

o'  o',  the  outside  cranks  and  coupling-rods. 

U U,  the  fore-wheels  coupled  to  the  driving- 
wheels. 

V V,  the  hind- wheels  under  the  fire-box. 

p' p',  springs  for  the  inside  bearings  of  the  cranked 
axle.  . 

q'  q',  springs  for  the  outside  bearings  of  all  the 
axles. 

o"  o ",  connecting-hoop  for  the  outside  springs  o l 
the  cranked  axle. 
r'  r',  the  axle-boxes. 

p" p",  pins  for  attaching  the  springs  to  the  axle- 
boxes. 

q"  q”,  cast-iron  guides  for  the  axle-boxes. 
r"  r" , the  spring-links. 

s''s",  the  nuts  for  adjusting  the  weight  upon  the 
springs. 

W W,  the  external  frame  of  the  engine. 

X X,  stays  from  the  external  frame  to  the 
boiler. 

Y,  the  foot-plate. 

Z,  the  buffer-beam. 
s'  s',  the  buffers. 
t't',  the  safeguards. 

u'  u',  a cock  and  pipe  for  letting  off  water  from  the 
cylinders. 
v',  the  signal-lamp. 
w'w',  the  hand-railing. 

x',  a pipe  from  the  boiler  for  heating  the  water  in 
the  tender. 
y’,  the  drag-bar. 

2'  2',  the  foot-steps. 

•es  to  the  Tender. 

I,  the  nut  and  link  for  connecting  the  screw  witn 

i,  the  brake-lever. 

J,  the  short  shaft  carrying  the  brake-lever,  and 

j,  the  double-toothed  sector,  working  into 

k k,  the  longitudinal  rods  carrying  the  brake- 
blocks. 

1 1,  supports  fitted  with  rollers  for  guiding  the 
rods  kk. 

mm,  the  wooden  brake-blocks. 
n,  socket  for  connecting  the  drag-springs  to  the 
drag-bars. 

op,  the  springs  for  buffing  and  drawing. 
q q,  bearings  for  the  spring  o. 
r r,  the  safety-chains, 
s s,  the  foot-steps. 

1 1,  handles  to  assist  in  rising  to  the  foot-plate. 
u,  a hinged  plate  between  the  engine  and  tender. 
v v,  buffers  for  the  tender. 
w,  drag-chain  of  the  tender. 


Fig.  263V  is  an  elevation  of  a small  American  locomotive  built  by  H.  R.  Dunham  & Co.,  New  York 
The  distinctive  part  of  the  engine  and  of  American  locomotives  in  general,  is  the  forward  truck  consist- 


282 


LOCOMOTIVE  ENGINE 


ing  of  two  sets  of  wheels  on  one  frame,  the  frame  revolving  on  a centre-pin,  which  enables  the  machine 
to  move  more  easily  around  corners ; this  form  of  engine  is  called  the  bogey  in  England. 

The  locomotive  here  shown  is  one  of  the  earlier  kind,  with  inside  connection,  and  hut  one  pair  of 
drivers.  At  present  in  this  country,  engines  with  outside  connections  are  thought  to  be  safer,  steadier 
and  cheaper  than  inside,  and  are  very  generally  adopted.  The  number  of  rb-iving  wheels  is  seldom  lesl 
than  two  pairs.  Fig.  2638  is  the  side  elevation  of  a locomotive  as  built  b;  Rogers,  Ketchum  & Gros 


vner  of  Paterson,  and  may  be  taken  as  the  type  of  the  American  locomotive.  The  earliest  American 
locomotives  were  but  copies  of  the  English  with  slight  adaptations,  for  the  service  required  and  fuel  used, 
but  the  later  engines,  as  will  be  seen,  are  distinctive. 

The  valve- o-eer  now  mostly  used  is  the  link-motion,  for  description  of  which  see  Link-Motion. 

The  coal  locomotives  as  built  by  Ross  & Winans  of  Baltimore,  differ  essentially  from  those  of  othei 


LOCOMOTIVE  ENGINE. 


283 


makers.  The  freight  engines  are  usually  eight-wheeled  engines,  all  connected ; the  fire-hox  is  extremely 
long  and  capacious.  The  fuel  is  let  down  through  a hopper  above  the  fire-hox,  the  tender  being  two- 
storied,  and  the  engineer  is  placed  on  the  top  of  the  engine,  immediately  back  of  the  smoke-stack.  For 
the  results  of  experiments  on  these  engines  on  the  Beading  Bailroad  see  Boiler. 


Coal  engines,  as  bunt  by  Perkins  of  Alexandria,  have  three  pairs  of  connected  drivers  and  a forward 
truck.  The  coal  engines  of  other  makers  are  in  general  appearance  similar  to  the  wood  engine,  til  e dif- 
ference being  almost  entirely  in  the  form  of  the  boiler. 


284 


LOGARITHMS. 


LOGARITHM.  The  logarithm  of  a number  is  the  exponent  of  a power  to  which  another  given  inva- 
riable number  must  be  raised  in  order  to  produce  the  first  number.  Thus,  in  the  common  system  o( 
logarithms,  in  which  the  invariable  number  is  10,  the  logarithm  of  1000  is  3,  because  10  raised  to  the 
third  power  is  1000.  In  general,  if  ax=y,  in  which  equation  a is  a given  invariable  number,  then  x is 
the  logarithm  of  y.  All  absolute  numbers,  whether  positive  or  negative,  whole  or  fractional,  may  be 
produced  by  raising  an  invariable  number  to  suitable  powers.  The  invariable  number  is  called  the  base 
of  the  system  of  logarithms  : it  may  be  any  number  whatever  greater  or  less  than  unity ; but  having 
been  once  chosen,  it  must  remain  the  same  for  the  formation  of  all  numbers  in  the  same  system.  What- 
ever number  may  be  selected  for  the  base,  the  logarithm  of  the  base  is  1,  and  the  logarithm  of  1 is  0. 
In  fact,  if  in  the  equation  a*=y  we  make  a-=l , we  shall  have  a1— a,  whence,  by  the  definition,  log. 
a— 1 ; and  if  we  make  x=0,  we  shall  have  a<l=l,  whence  log.  1=0. 

These  properties  of  logarithms  are  of  very  great  importance  in  facilitating  the  arithmetical  opera- 
tions of  multiplication  and  division.  For  if  a multiplication  is  to  be  effected,  it  is  only  necessary  to 
take  from  the  logarithmic  tables  the  logarithms  of  the  factors,  and  add  them  into  one  sum,  which  gives 
the  logarithm  of  the  required  product ; and  on  finding  in  the  table  the  number  corresponding  to  this 
new  logarithm,  the  product  itself  is  obtained.  Thus  by  means  of  a table  of  logarithms  the  operation 
of  multiplication  is  performed  by  simple  addition.  In  like  manner,  if  one  number  is  to  be  divided  by 
another,  it  is  only  necessary  to  subtract  the  logarithm  of  the  divisor  from  that  of  the  dividend,  and  to 
find  in  the  table  the  number  corresponding  to  this  difference,  which  number  is  the  quotient  required. 
Thus,  the  quotient  of  a division  is  obtained  by  simple  subtraction. 

Logarithms  apply  with  equal  advantage  to  the  formation  of  powers  and  extraction  of  roots.  Let  y 
be  a number  to  be  raised  to  the  power  m,  ( m being  any  number,  whole  or  fractional,  positive  or  negar 
tive.)  As  before,  we  have  y=a* ; and,  on  raising  both  sides  of  the  equation  to  the  power  m,  ym=amx: 
whence,  by  the  definition,  log.  ym=m  x—m  log.  y ; that  is,  the  logarithm  of  the  power  of  a number  is 
equal  to  the  product  of  the  logarithm  of  the  number  by  the  exponent  of  the  power. 


If  in  the  equation  of  log.  ym  = m log.  y we  make  m — -,  we  shall  have  log.  y “ (or  log.  y)  = - log. 

y ; that  is  to  say,  the  logarithm  of  any  root  of  a number  is  equal  to  the  logarithm  of  the  number  divi- 
ded by  the  index  of  the  root. 

From  these  two  last  results  it  is  obvious  that  by  means  of  a table  of  logarithms  numbers  may  be 
raised  to  any  power  by  simple  multiplication,  and  that  the  roots  of  numbers  may  be  extracted  by  sim- 
ple division. 

When  a table  of  logarithms  has  been  calculated  for  any  given  base,  it  is  easy  to  find  by  means  of  it 
any  other  system  of  logarithms  corresponding  to  a different  base.  Thus,  supposing  a system  of  loga- 
rithms has  been  calculated  of  which  the  base  is  a,  or,  which  is  the  same  thing,  that  the  value  of  x has 
been  found  for  every  different  value  of  y in  the  equation  ax—y,  and  that  it  is  required  to  construct 
another  table,  of  which  the  base  is  b,  or  to  find  the  values  of  v corresponding  to  every  different  value 
of  y in  the  equation  b v = y,  we  may  proceed  as  follows  : Taking  the  logarithms  of  both  members  of 
this  last  equation  from  the  table  supposed  already  calculated,  of  which  the  base  is  a,  and  recollecting 

log.  y 

that  log.  bv  — v log.  b,  we  have  v log.  b = log.  y ; whence  v =^  v'  . But  because  bT  = y,  it  follows  that 
v is  the  logarithm  of  y in  the  system  of  which  the  base  is  b ; therefore,  denoting  the  logarithms  in  this 
new  system  by  L,  we  have  L y — ^ p~  jf.  Hence  it  appears  that,  in  order  to  find  the  logarithm  of  any 
given  number  y in  the  new  system,  it  is  only  necessary  to  multiply  its  logarithm  in  the  system  already 


calculated  by  the  constant  number , -.  This  constant  number,  by  means  of  which  we  pass  from  the 

J log.  b J 

one  table  to  the  other,  is  called  the  modulus  of  the  new  table  with  reference  to  the  old. 

The  logarithms  of  the  particular  system  of  which  the  modulus  is  1,  is  called  the  Napierian  system. 
But,  as  has  been  shown,  when  the  logarithms  have  been  found  in  any  one  system,  they  may  be  trans- 
ferred into  those  of  any  other  system  by  means  of  a constant  factor.  In  the  common  system  the  base 
is  10,  and  the  Napierian  logarithm  of  any  number  is  consequently  transformed  into  the  common  loga- 


rithm of  the  same  number  by  multiplying  by  the  modulus 


1 

lTo' 


This  number,  which  is  of  great  im- 


portance in  the  computation  of  the  logarithmic  tables,  is  found  to  be  0'4342944819,  &.C.,  the  Napierian 
logarithm  of  10  being  2'30258509,  &c.  It  may  also  be  remarked  that  this  modulus  0'4342944819  is 
the  ordinary  logarithm  of  the  base  of  the  Napierian  system;  for,  calling  e this  base,  we  shall  have 


e = 10,  whence,  taking  the  ordinary  logarithm  of  both  sides  of  the  equation  L10  Xlog.  e = log.  10  = 1; 
therefore,  log.  e — — — - = 0-4342944819.  On  passing  to  numbers,  we  find  e — 2-7182818284. 


The  Napierian  logarithms  are  sometimes  called  the  natural  logarithms , on  account  of  the  modulus  oi 
the  system  being  unity ; and,  more  frequently,  hyperbolic  logarithms,  because  they  represent  the  area 
of  a rectangular  hyperbola  between  its  asymptotes,  and  on  this  account  are  of  immense  use  in  calcula 
lions  connected  with  the  steam-engine. 

Logarithms  being  of  constant  use  in  calculations,  the  tables  which  have  bean  published  are  very 
numerous.  The  most  complete  are  those  of  Ylacq,  to  ten  decimals  ; but  they  are  very  scarce,  and  can 
with  difficulty  be  procured.  There  is  an  edition  of  them  by  Vega,  in  1797,  also  scarce.  Gardiner’s 
Logarithms,  printed  in  1742,  in  4to,  and  another  edition  of  them  at  Avignon,  in  France,  in  1770.  are  to 
seven  decimals.  Collet’s  Logarithms,  in  8vo,  like  Gardiner’s,  contain  the  logarithmic  sines,  &c.,  loi 


LOOM,  POWER. 


285 


every  10  seconds.  Taylor’s  Logarithms , in  4to,  and  also  Baguay’s , have  them  to  every  second.  Hut- 
ton’s Logarithms,  and  Babbage’s  Logarithms  of  Numbers,  are  well  known.  The  latter  was  carefully 
collated,  and  is  very  accurate  and  convenient.  Hulsse’s  Sammlung  Mathematischer  Tafeln  (8vo.  Leip- 
sig,  1840)  deserves  to  be  mentioned  as  a very  useful  collection.  The  above  (excepting  Vlacq’s  and 
Yega’s)  are  all  to  seven  decimal  figures;  hut  for  many  purposes,  logarithms  to  a less  number  of  deci- 
mals are  sufficiently  accurate.  For  navigation  and  surveying,  tables  to  six  fixgures  are  the  most  con- 
venient, as  they  give,  in  general,  the  trigonometrical  lines  correct  to  single  seconds.  The  best  tables  of 
this  kind  are  Farley’s  Tables  of  Six-figure  Logarithms,  (12mo,  1840.)  For  many  auxiliary  computations 
in  astronomy  it  is  sufficient  to  have  the  logarithms  to  five  places.  The  reprint  of  Lalandc’s  Five-figure 
Table  by  the  Useful  Knowledge  Society  (18mo,  1839)  is  convenient,  and  may  be  relied  on  for  accuracy. 

LOG,  for  steam-vessels.  Fig.  2649  is  a side  view,  and 
Fig.  2650  an  end  view  of  this  instrument.  A is  a small 
wheel,  1 foot  diameter,  having  vanes  set  at  such  an  angle 
that,  when  let  into  the  water,  the  action  upon  their  in- 
clined surfaces  would  cause  the  wheel  to  revolve  once  in 
passing  the  distance  of  two  feet  through  the  water. 

Upon  the  axis  of  the  wheel  is  an  endless  screw  a,  into 
which  works  a small  toothed  wheel,  having  51  teeth. 

The  instrument  should  be  mounted  on  the  low  end  of  a 
stiff  bar  of  wood,  or  other  material,  of  such  length  as 
that  the  top  end  could  be  fastened  by  a joint  or  hinge  b, 
to  the  side  of  a vessel,  in  convenient  proximity  to  a 
cabin  window,  or  to  the  deck.  To  the  low  end  of  the 
rod  or  bar  a small  line  should  be  attached,  c,  the  other 
end  of  which  to  be  secured  on  the  deck  of  the  vessel. 

The  use  of  this  line  would  be  to  withdraw  the  instru- 
ment from  the  water  when  not  required  for  observation, 
and  to  lash  it  horizontally  out  of  the  reach  of  the  waves. 

When  the  line  was  released,  the  instrument  should  be  so 
suspended  as  to  fall  perpendicularly  into  the  water,  and 
the  bar  sufficiently  stiff  to  remain  perpendicular,  and  re- 
sist the  pressure  of  the  water  against  its  front  edges, 
which,  however,  would  be  but  trifling.  The  axis  of  the 
small  toothed  wheel  should  be  inclosed  in  a tube  in 
front  of  the  bar  on  which  the  wheel  is  suspended,  and 
prolonged  to  a short  distance  below  the  hinged  joint ; 
and  upon  the  top  end  of  it  should  be  fixed  an  index  d, 
to  revolve  on  a dial-plate  decimally  divided.  The  wheel 
being  constructed  as  before  described,  this  index  would 
make  one  revolution  round  the  dial-plate  in  the  time 
that  the  vessel  passed  102  feet  through  the  water,  which 
is  about  the  one-sixtieth  part  of  a knot,  or  nautical  mile.  If,  therefore,  an  observer  stood  with  a minute- 
glass,  (or  seconds  watch,)  and  turned  the  glass  the  moment  the  index  was  at  zero  upon  the  dial-plate, 
and  noted  the  number  of  revolutions  and  parts  made  by  the  index  during  the  time  the  sand  was  running 
out,  he  would  have  the  rate  at  which  the  vessel  passed  through  the  water,  in  knots  and  decimals,  per 
hour. 

LOGWOOD.  A hard,  compact  wood,  so  heavy  as  to  sink  in  water,  of  a fine  grain,  capable  of  being 
polished,  and  so  durable  as  to  be  scarcely  susceptible  of  decay.  Its  predominant  color  is  red,  tinged 
with  orange,  yellow,  and  black.  It  yields  its  color  both  to  spirituous  and  watery  menstrua.  Alcohol 
extracts  it  more  readily  and  copiously  than  water.  The  color  of  its  dye  is  a fine  red,  inclined  a little 
to  violet  or  purple,  which  left  to  itself,  becomes  yellowish,  purple,  and  at  length  black.  Acids  turn  it 
yellow,  alkalies  deepen  the  color,  and  give  it  a purple  or  violet  hue.  A blue  color  is  obtained  from 
logwood,  by  mixing  verdigris  with  it  in  the  dye-bath.  The  great  consumption  of  logwood  is  for  blacks, 
to  which  it  gives  a lustre  and  velvety  cast ; it  is  also  extensively  used  as  a red,  purple,  or  black  dye  to 
beech,  and  various  white  woods.  See  Woods,  Varieties  of. 

LOOM,  POWER.  Fig.  2651  is  a front  elevation  of  a power-loom  for  weaving  printing  goods,  as  built 
in  the  Lowell  Machine  Shop,  Lowell,  Mass. 

Fig.  2652  is  the  driving-end,  showing  pulleys,  geers,  shipper,  Ac. 

Fig.  2653  is  a view  of  the  other  end,  showing  the  take-up  motion. 

A denotes  the  cast-iron  ends,  which,  with  the  iron  girts  that  are  bolted  between,  constitute  the  frame- 
work to  which  all  other  parts  are  attached. 

B is  a cast-iron  arch,  which  supports  the  roll  over  which  the  harnesses  hang. 

C C are  the  driving-pulleys,  one  loose,  the  other  fast. 

D,  large  geer  or  cam  shaft,  driven  by  a geer  on  the  crank-shaft. 

E,  cams  for  working  the  harnesses ; F,  cam  for  throwing  shuttle. 

G,  lever  for  taking  up  the  cloth  by  operating  on  the  ratchet-wheel  H.  This  lever  is  worked  by  a 
jrank-motion  attached  to  the  end  of  cam-shaft. 

H,  ratchet-wheel,  operated  by  lever  G. 

I,  emery-roll ; J,  binder-roll;  K,  cloth-roll.  The  cloth,  after  passing  between  the  rolls  I and  J,  windi 
up  on  this  roll.  This  roll  is  driven  from  I by  a belt. 

L,  Fig.  2652,  is  a view  of  the  filling  stop-motion. 

M,  head  on  yarn-beam,  with  a groove  for  a strap. 

N,  strap  and  spring  for  friction  on  yarn-beam. 


286 


LOOM,  POWER. 


# 


O,  lever,  operated  by  cam,  on  cam-shaft. 

P,  lever  attached  to  O,  which  comes  in  contact  with  catch  L,  (when  the  filling  breaks,)  and  throws  tli* 
shipper-handle  Q out  of  the  notch  in  which  it  is  held,  and  stops  the  loom. 

Q,  shipper-handle  for  stopping  and  starting  the  loom. 


R,  piece  attached  to  the  protecting-rod,  that  strikes  a lever  under  the  breast-beam,  (whenever  tha 
shuttle  fails  of  performing  its  duty,)  and  stops  the  loom. 

S,  picker-staff  for  throwing  the  shuttle,  which  receives  its  motion  from  a cam  on  cam-shaft,  commu 
aicated  by  a treadle  and  strap  T. 

T,  strap  for  picker-motion. 


IT,  harness-treadles,  operated  by  the  cams  E E. 

V,  crank-shaft,  which  gives  motion  to  the  lathe  or  sley.  X,  sley  or  lathe,  which  contains  the  reed. 

Y,  harnesses  for  separating  the  warps  while  the  filling  passes  through,  which  are  operated  by  th« 
narness-cam  E alternately. 


LOOM,  COUNTERPANE. 


287 


Z Z are  the  swords  that  support  the  lathe,  and  are  attached  to  the  rocking-shaft  at  the  bottom. 

«fc,  rocking-shaft  on  which  the  lathe  swings. 

a'  is  a geer  attached  to  the  yarn-beam,  used  only  when  dressing  the  yarn.  V , reed,  c',  friction  roll 
for  picker-lever  strap,  d',  picker-levers  or  treadles,  e',  race-rods,  on  which  the  pickers  slide.  /',  pickers, 
made  of  green  hide,  dried  and  pressed,  g',  temples  for  holding  the  cloth  in  its  place  and  keeping  it 
stretched  in  width.  h‘  is  the  cloth,  as  it  passes  over  the  breast-beam  down  between  the  two  rolls  on 
to  the  cloth-roll. 

LOOM,  BIGELOW’S  COUNTERPANE.  This  improvement  consists  principally  in  the  manner  in 
which  the  shuttles  are  thrown;  the  manner  of  raising  and  depressing  the  shuttle-boxes;  and  the  man- 
ner in  which  the  picker  is  relieved  from  the  shuttle. 

We  copy  from  the  specification  of  the  patentee  : 

In  throwing  the  shuttles,  I cause  the  two  picker-staves  to  operate  simultaneously,  so  that  the  shuttle 
may  be  thrown  from  whichever  of  the  boxes  is  presented  to  their  action.  This  I effect  by  the  use  of  one 
picker-treadle  only,  which  is  acted  upon  by  a cam-ball,  in  the  usual  way  of  working  such  treadles. 
From  this  treadle  two  bands  are  extended,  and  pass  around  the  two  picker-pulleys  in  such  manner  that 
when  the  treadle  is  depressed  both  the  picker-staves  will  be  set  in  action  at  the  same  moment.  By  this 
arrangement,  two  or  more  shuttles  may  be  successively  thrown  from  the  same  end  of  the  loom  by  the 
action  of  one  treadle. 

The  shuttle-boxes  are  raised  and  lowered  in  the  following  manner : a shaft  extends  along  under  the 
race-beam,  from  one  shuttle-box  to  the  other,  and  carries  pinions,  which  take  into  racks  attached  to  the 
shuttle-boxes ; it  will  be  manifest,  therefore,  that  by  causing  this  shaft  to  revolve,  the  shuttle-boxes  may 
be  raised.  The  revolving  of  this  shaft  is  effected  by  the  action  of  a spiral  or  other  spring,  one  end  of 
which  is  attached  to  the  frame  of  the  loom  at  its  back,  and  said  spring  extends  forwards  towards  the 
lathe ; from  this  forward  end  a band  attached  to  it  passes  round  guide-pulleys,  the  situation  of  which 
will  be  shown  in  the  accompanying  drawing,  and  also  round  a pulley  upon  the  above-named  shaft,  to 
which  latter  said  band  is  attached.  The  action  of  the  spring,  by  its  drawing  upon  the  band,  will  cause 
the  pinion-shaft  to  revolve,  and  will  consequently  raise  the  shuttle-boxes.  Should  this  spring  be  thrown 
out  of  action,  and  the  band  by  which  the  shuttle-boxes  are  raised  be  relaxed,  they  will  then  descend  by 
their  own  gravity.  To  take  off  the  tension  of  the  spring,  there  is  a cam  upon  the  main  shaft  of  the  loom, 
which  cam,  as  the  shaft  revolves,  depresses  a treadle,  to  the  end  of  which  a band  is  attached,  which 
operates  in  such  a way  as  to  relieve  the  shuttle-boxes  from  the  action  of  the  spring,  and  they  then  de- 
scend. In  relieving  the  picker  from  the  point  of  the  shuttle,  I make  use  of  the  protection-rod  consti- 
tuting a part  of  the  apparatus  employed  in  the  ordinary  power-loom,  for  stopping  the  loom  when  the 
shuttle  does  not  arrive  home  in  the  shuttle-box.  From  the  protection-rod,  which  extends  along  below 
the  shuttle-boxes,  I allow  a small  arm  or  finger  to  descend,  which  finger,  as  the  lathe  comes  up  towards 
the  breast-beam,  strikes  against  a stop  or  pin,  attached,  for  that  purpose,  to  the  frame  of  the  loom,  caus- 
ing the  protection-rod  to  rock  or  revolve  to  a short  distance.  This  gives  motion  to  two  arms  which 
extend  out  from  the  extreme  ends  of  the  protection-rod,  opposite  to  the  outer  ends  of  each  of  the  shuttle- 
boxes  ; from  these  arms  motion  is  communicated  to  a lever  which  works  on  a fulcrum  over  the  outer 
ends  of  each  of  the  shuttle-boxes,  said  arms  being  connected  to  the  levers  by  rods  or  wires.  By  depress- 
ing the  outer  ends  of  these  levers  their  inner  ends  are  raised,  and  to  these  ends  are  appended  rods 
which  carry  pieces  of  wood  or  metal,  which,  when  down,  rest  on  and  embrace  the  picker-rod,  and  in 
that  position  they  serve  to  hold  the  picker  at  a short  distance  from  the  end  of  the  shuttle-box,  and  to 
stop  the  shuttle ; the  picker  is  then  removed  from  the  point  of  the  shuttle  by  the  raising  of  the  lever, 
the  picker  being  made  to  pass  home  to  the  end  of  the  box,  thus  leaving’  the  shuttle  and  shuttle-box  free 
to  be  raised  or  lowered  without  obstruction,  the  picker  being  also  ready  again  to  act  on  a shuttle. 

Having  thus  given  a general  description  of  my  improvements,  I now  proceed  to  exemplify  the  same 
by  references  to  the  accompanying  drawings. 

Fig.  2654  is  a front  view,  in  perspective,  of  my  improved  counterpane  power-loom,  and  Fig.  2655  a back 
view  of  one  end  of  one  of  the  shuttle-boxes,  this  being  drawn  for  the  purpose  of  showing  the  particular 
construction  and  arrangement  of  this  part  of  the  machinery,  which  could  not  be  exhibited  in  the  front 
view.  In  Fig.  2654  the  breast-beam  is  not  represented,  it  being  removed  for  the  purpose  of  showing 
the  lathe,  and  the  parts  connected  therewith,  the  more  distinctly.  The  jacquard  apparatus,  which  is 
employed  to  regulate  the  figure,  and  is  perfectly  well  known,  being  in  general  use,  I also  use  as  hereto- 
fore constructed.  It  is  not  represented  in  the  drawing,  it  not  being  deemed  necessary  to  describe  it ; 
but  I have  fully  shown  those  parts  which  constitute  my  improvements. 

A A are  the  picker-staves,  and  B the  picker-treadle ; D is  the  cam-ball  for  working  this  treadle,  oper- 
ating in  the  usual  manner.  E E are  two  straps  which  are  attached  to  the  picker-treadle  ; these  straps 
pass  over  the  pulleys  F F,  and  are  attached  by  their  outer  ends  to  the  pulleys  G G,  which  carry  the 
staves  A A,  and  these  are  consequently  acted  upon  simultaneously.  The  rods  or  staves  A'  A'  serve  to 
cause  the  pickers  to  pass  home  when  the  pieces  of  wood,  &c.,  above  referred  to,  are  raised  ; these  rods 
are  drawn  towards  the  outer  ends  of  the  shuttle-boxes  by  the  action  of  the  spiral  springs  0 C,  the  use 
of  which  will  more  fully  appear  when  describing  the  parts  shown  in  Fig.  2655. 

The  following  is  the  arrangement  devised  by  me  for  raising  and  depressing  the  shuttle-boxes : a shaft 
H H is  made  to  extend  along  under  the  race-beam,  and  this  shaft  carries  the  pinions  1 1,  which  take  into 
vertical  racks  J J attached  to  the  shuttle-boxes.  I sometimes  use  a single  rack  affixed  at  the  middle  of 
each  box ; but  I prefer  the  placing  of  a rack  and  pinion  at  each  end  of  each  box,  as  shown  in  the  draw 
ing.  There  is  a pulley  L on  the  shaft  H,  and  this  shaft  is  made  to  revolve  by  means  of  a band  K,  one 
end  of  which  is  attached  to  and  laps  around  the  said  pulley.  The  baud  K passes  thence  around  pulleys 
act.',  the  pulley  a being  attached  to  the  frame, and  the  pulley  a'  either  to  the  frame  or  to  the  floor.  The 
spiral  spring  M affixed  to  the  back  of  the  loom  draws  on  the  band  K attached  to  its  fore  end,  so  as  to 
cause  the  pulley  L and  the  shaft  H to  revolve  and  raise  the  shuttle-boxes.  When  the  spiral  spring  M 
is  relieved  from  its  action  on  the  band  K,  the  shuttle-boxes  will  descend  by  their  own  gravity  When 


288 


LOOM,  COUNTERPANE. 


this  is  to  take  place,  the  tension  of  the  spring  is  taken  off  by  the  action  of  the  cam  N,  placed  on  the 
main  shaft  of  the  loom,  which  cam  is  so  formed  as  to  depress  the  treadle  O,  which,  drawing  on  the  part 
P of  the  band  Iv,  takes  off  the  action  of  the  spiral  spring  therefrom,  and  the  shuttle-boxes  descend. 

The  protection-rod  Q Q and  its  appendages,  used  for  stopping  the  loom  when  the  shuttle  does  net 
arrive  home,  are  employed  by  me  iu  the  ordinary  way ; but  I also  make  use  of  this  protection -rod  for 
the  purpose  of  relieving  the  shuttle  from  the  picker,  in  the  following  manner : R is  an  arm  or  finger 
which  is  affixed  to  and  descends  from  the  protection-rod,  and  this,  as  the  lathe  approaches  the  breast- 
beam,  strikes  against  the  stop  S attached  to  the  frame  of  the  loom,  and  causes  a partial  revolution  of 
the  protection-rod.  T T are  arms  on  its  extreme  ends,  which  arms  are  connected  to  two  vibrating  levers 
U U,  by  a rod  z z,  which  work  on  fulcra  on  the  ends  of  the  lathe,  above  the  shuttle-box. 


>:*3 

O 

ci 


Fig.  2655  is  a back  view  of  the  outer  end  of  one  of  the  shuttle-boxes,  showing  the  manner  in  which 
die  lever  U and  its  appendages  operate.  The  piece  of  wood  or  metal  Y which  is  raised  and  lowered 
by  the  action  of  the  lever  U,  and  which  is  represented  as  resting  on  the  picker  W,  will,  when  the  inner 
end  of  the  lever  U is  down,  rest  upon  the  picker-rod  X,  where  it  serves  to  arrest  the  picker  and  stop 
the  shuttle.  When  the  lever  U is  raised,  the  picker  is  thereby  allowed  to  pass  home,  and  is  conse- 
quently removed  from  the  point  of  the  shuttle,  and  this  and  the  shuttle-box  are  left  free  to  be  raised  or 
lowered.  The  ro*d  A'  bears  against  the  pin  b projecting  from  the  picker,  and  serves  to  remove  it  from 


LOOM,  DOUBLE-STROKE. 


289 


the  shuttle  -when  the  piece  Y is  raised.  The  rods  c c support  the  pin  l>,  and  serve  as  guides  to  the  rod 
A';  the  cord  d connects  the  upper  end  of  the  rod  A'  to  the  upper  end  of  the  stave  A,  in  order  that  the 
stave  may  by  its  motion  move  the  rod  also. 

I -will  here  remark,  that  a weight  may  be  substituted  for  the  spiral  or  other  spring  M ; that  the 
shuttle-boxes  may  be  raised  by  springs  placed  immediately  under  them,  and  that  the  tension  of  such 
springs  may  be  taken  off  by  means  analogous  to  those  described ; but  it  will  be  manifest  to  every  com- 
petent machinist  that  any  such  variation  of  the  respective  parts  will  not  substantially  change  the  char- 
acter of  my  invention.  The  manner  of  constructing  and  arranging  the  apparatus  as  set  forth  by  me,  is 
that  which  I have  deemed  the  best  in  practice. 


290 


LOOM,  DOUBLE-STROKE. 


Fig.  2659,  illustration  of  the  movement  which  operates  the  picker-staff. 

Figs.  2660  ami  2661,  shuttle.  Fig.  2658,  elevation  of  the  loom  on  the  side  of  the  warp. 

Figs.  2662  and  2663,  plan  and  section  of  the  brake. 

Fig.  2664,  plan  of  one  of  the  shuttle-boxes. 

A,  warp-beam.  B B1  B2  B3  B4,  frame  of  the  loom,  b b,  supports  of  the  shaft  of  the  drum  C,  fastened 
to  the  uprights  of  the  frame  by  set-screws.  C,  wooden  drum,  dd',  blocks  to  preserve  separate  tha 


threads  of  the  warp.  E E',  harness  for  raising  and  lowering  the  threads  of  the  warp  for  the  passage  oi 
the  shuttle.  F,  breast-beam.  G,  cloth-beam.  H,  spur-wheel  on  the  shaft  of  the  cloth-beam,  f pinion 
working  into  the  wheel  H.  I,  ratchet-wheel,  which  works  with  the  pinion.  J,  bell-crank,  moving  on 
the  centre  n,  and  carrying  the  clicks  g g'  and  the  counterpoise  j.  g,  lay-click,  serving  to  give  motion  to 
the  ratchet-wheel,  g'  g',  stop-clicks,  to  arrest  the  movements  of  the  ratchet-wheel,  i,  pin  on  one  of  the 
swords  of  the  lay,  to  give  motion  to  the  bell-crank  J.  K,  spur-wheel  on  the  shaft  of  the  drum  A,  work 
mg  with  the  pinion  k k pinion  of  12  teeth,  fixed  to  the  shaft  which  carries  the  brake-pulley  L,  Fig 


LOOM,  CARPET-WEAVING. 


291 


265S,  and  also  Figs.  2662  and  2663.  m,  cord,  fastened  at  one  end  to  a spiral  spring,  and  passing  ovei 
the  pulley  M,  supports  the  counterpoises  M',  formed  of  iron  rings.  N N',  needles,  ■which  give  movement 
to  the  harness  of  the  treadles,  one  shorter  than  the  other.  0 O',  two  eccentrics,  cast  in  the  same  piece, 
serving  to  give  motion  to  the  treadles,  and  consequently  to  raise  and  lower  the  harness.  P,  shaft  car- 
rying the  eccentrics  of  the  treadles,  and  also  the  cranks  Z,  which  give  motion  to  the  picker-staff.  P', 
spur-wheel  on  the  shaft  P.  Q,  pinion,  of  half  the  diameter  of  the  wheel  P,  and  giving  motion  to  it. 
Q',  a driving-shaft  of  the  machine.  R R',  fast  and  loose  pulleys  on  the  shaft  Q.  for  the  working  of  the 
machine.  S S',  eccentrics,  by  means  of  which  a double  beat  is  given  to  the  lay  V at  each  revolution  oi 
the  main  shaft.  t 1',  friction-rollers  at  the  ends  of  the  swords  of  the  lay,  to  receive  the  action  of  the 
eccentrics  S S'.  T,  two  swords  of  the  lay.  U,  lay  or  batten,  on  which  traverse  the  shuttles.  V,  shut- 
tles ; X,  picker-staff;  x,  picker  strings,  x,  pickers  of  hide,  serving  to  throw  the  shuttle,  x2,  guide-rods 
to  the  pickers.  Y,  wooden  levers,  sunk  in  the  substance  of  the  cheeks  of  the  lay,  and  turning  on  the 
pin  y.  y y1  y3  y4 yb,  details  of  the  stop-motion  by  which  the  loom  is  thrown  out  of  geer  by  a failure  ol 
the  proper  motion  of  the  shuttle.  Z,  two  cranks  on  the  shaft  P,  giving  motion  to  the  picker-staff  by 
means  of  friction-rollers  z on  the  ends  of  the  crank,  working  upon  inclines  z.  Z2.  two  levers,  connected 
witli  the  axes  of  the  picker-staffs,  and  united  by  means  of  straps  to  a spiral  spring  Z3. 

LOOM,  POWER  CARPET,  for  weaving  two  or  three  ply  ingrain  or  Kidderminster  carpets,  by  E.  B. 
Bigelow.  It  gives  peculiar  interest  to  the  description  of  a valuable  and  meritorious  invention,  to  pre- 
cede it  by  some  account  of  the  life  an  1 character  of  the  inventor.  The  mind  loves  to  contemplate  the 
early  struggles  of  genius,  to  perceive  and  comprehend  its  first  inspirations,  and  step  by  step  to  trace 
the  development  of  its  powers. 

Erastus  B.  Bigelow  was  born  at  West  Boylston,  Massachusetts,  in  April,  1814.  Plis  father  was  a 
cotton  manufacturer,  which  circumstance,  we  have  a right  to  assume,  gave  to  the  son’s  mind  its  first 
tendency  towards  that  peculiar  branch  of  mechanical  pursuits  in  which  he  has  now  attained  an  envia- 
ble and  undisputed  eminence.  His  parents,  however,  designed  him  for  the  medical  profession  ; but 
such  a misdirection  of  faculties  was  not  predestined  by  the  “ Divinity  that  shapes  our  ends.”  Before 
he  had  completed  his  medical  education,  his  father,  in  common  with  many  others  engaged  in  man- 
ufactures at  that  time,  failed  in  business,  and  was  unable  to  complete  the  education  of  his  son.  What 
appeared  at  first  a severe  private  calamity,  has,  -under  a wise  Providence,  resulted  in  great  public 
good. 

Finding  himself  without  means  to  prosecute  his  medical  studies,  young  Bigelow  yielded  to  that  ne- 
cessity which  has  so  often  proved  the  benign  mother  of  early  invention,  and  determined  to  direct  his 
ingenuity  to  the  contrivance  of  some  piece  of  mechanism,  from  which  he  might  obtain  some  pecuniary 
benefit.  Whilst  his  thoughts  were  directed  to  that  object,  he  happened  one  day  to  be  lying  on  a bed 
covered  with  a knotted  counterpane,  a species  of  fabric  in  which  the  figure  on  the  surface  appears  as  if 
made  by  tying  into  knots  the  threads  of  the  woof ; and  as,  some  years  before,  an  attempt  had  been 
made  in  West  Boylston  (where  he  was  still  living)  to  manufacture  such  counterpanes  on  hand-looms, 
and  abandoned  on  account  of  the  great  labor  and  expense  involved,  three  or  four  days  being  required 
to  make  one  counterpane,  it  became  evident  to  his  mind  that  if  he  could  succeed  in  producing  a power- 
loom  for  this  purpose,  it  would  be  highly  valuable  as  a labor-saving  machine,  and  that  he  could  derive 
from  it  the  pecuniary  assistance  for  the  want  of  which  his  medical  studies  had  been  suspended.  It  was 
a bold  undertaking  for  one  wholly  uninitiated  in  the  mysteries  of  the  mechanic  art,  but  his  very  inex- 
perience was  to  him  a great  benefit,  by  concealing  from  his  sight  the  enormous  mechanical  difficulties 
he  would  have  to  encounter,  and  which,  if  then  fully  known,  might  have  deterred  him  from  ever  carry- 
ing his  purpose  into  execution.  We  may  here  notice  this  remarkable  fact,  that  the  most  original  and 
important  inventions  the  world  has  ever  seen,  were  the  productions  of  men  who  had  received  little  or 
no  previous  training  in  the  particular  art  which  they  sought  to  improve.  Jacquard,  the  inventor  of 
the  beautiful  mechanism  which  bears  his  name,  for  weaving  figured  fabrics,  is  the  only  exception 
with  which  we  are  acquainted.  It  would  seem  that  in  pursuing  any  avocation  steadily,  the  mind 
becomes  so  habituated  to  a certain  practical  routine,  as  to  make  it  distrustful  of  any  other ; whilst, 
on  the  other  hand,  a mere  novice,  from  the  fact  of  his  approaching  the  subject  untrammelled  by 
habit  or  prejudice,  will  be  better  fitted  to  detect  existing  errors,  and  suggest  bold  and  original  improve- 
ments. 

But  to  return.  This  new  idea,  forced  by  circumstances  upon  Mr.  Bigelow’s  mind,  he  prosecuted  so 
vigorously,  that  in  the  course  of  one  year  he  hail  an  automatic  loom  for  weaving  knotted  counterpanes 
in  successful  operation,  doing  the  work  in  one-fourth  of  the  time  required  by  the  hand-loom. 

The  loom  was  arranged  with  every  fourth  dent  of  the  reed  adapted  to  slide  vertically  in  the  lathe,  and 
with  a hook  on  the  front  edge.  To  the  lower  end  of  each  of  these  hooked  dents  was  suspended  a wire, 
attached  at  its  lower  end  to  one  end  of  a lever,  and  the  series  of  levers  were  acted  upon  at  the  other 
end  by  tappets,  arranged  in  a helical  line  on  a barrel  or  cylinder,  for  the  purpose  of  depressing  the 
hooked  dents  in  succession  from  one  side  of  the  lathe  to  the  other.  The  levers  and  dents  were  so  weighted 
as  to  remain  in  a depressed  position,  with  the  hooks  below  the  race-beam,  to  permit  the  passage  of  the 
shuttle,  and  when  elevated  they  were  held  up  by  the  pressure  of  a spring  on  each  one.  For  the  pro- 
duction of  the  figure,  the  hooks,  or  rather  that  portion  of  them  required  each  time,  were  operated  every 
fourth  pick  or  throw  of  the  shuttle,  and  after  the  fourth  throw  of  the  shuttle,  the  required  portion  of 
hooked  dents  were  elevated  above  the  weft-thread,  the  upper  part  of  the  hooks  being  curved,  to  admit 
of  its  passing  by  the  weft-thread ; and  then,  when  drawn  down,  each  hook  in  succession  caught  the  weft 
and  drew  it  down  below  the  line  of  the  bottom  warps,  to  form  the  loop,  so  that  when  the  weft-thread 
was  beaten  up  by  the  reed,  and  the  warps  crossed,  each  loop  would  project  to  the  required  distance 
above  the  face  of  the  cloth.  To  insure  the  proper  action  of  the  hooks  on  the  weft-thread,  there  was  a 
plate  imbedded  in  the  race-board,  and  adapted  to  slide  up  and  down,  and  having  a notch  corresponding 
with  each  hooked  dent.  This  plate  was  brought  up  under  the  warps  just  before  the  hooked  dents  were 
denressed,  and  formed  a bed  for  the  hooks  to  draw  the  weft-thread  down.  The  selection  of  the  hooked 


292 


LOOM,  CAE  PET- WEAVING. 


dents  required  to  be  elevated  and  depressed,  for  each  operation  to  determine  the  figure  was  effected  by 
a series  of  needles,  on  the  principle  of  the  jacquard,  and  governed  by  punched  cards ; but  these  nee- 
dles, instead  of  being  used  to  operate  knotted  cards,  were,  at  their  outer  ends,  joined  to  wire  hooks 
connected  with  the  levers  of  the  hooked  dents,  and  when  the  needles  were  acted  upon  by  the  cards, 
the  hooked  wires  of  such  of  the  levers  as  were  to  be  operated  to  lift  the  dents  were  brought 
within  the  range  of  motion  of  a lifting-bar,  which  carried  them  up  where  they  were  held  by  the 
spring  before  described ; the  lifting-bar  was  then  depressed,  and  then,  as  the  tappets  on  the  barrel 
passed  around,  the  lifted  hooked  dents  were  eacli  in  succession  drawn  down  to  form  the  series  of 
loops. 

This  loom  was  so  ingenious,  and  worked  so  well,  that  our  young  inventor  soon  found  capital- 
ists able  and  willing  to  furnish  the  means  necessary  for  the  enterprise,  and  a patent  was  secured 
for  the  invention  in  the  United  States,  on  the  6th  day  of  January,  1838,  and  in  England  the  same 
year. 

He  contracted  with  parties  to  build  three  looms,  they  to  pay  a certain  price  for  the  invention,  but  be- 
fore this  contract  was  fulfilled  on  either  side,  he  visited  New  York,  and  there  saw  for  the  first  time  a 
new  and  different  species  of  counterpanes,  then  just  introduced  from  England,  which,  from  the  superior- 
ity of  the  fabric,  he  perceived  must  soon  supersede  the  knotted  counterpanes.  Although  being  at  that 
time  in  great  pecuniary  want,  and  surrounded  by  all  its  attendant  privations  and  temptations,  instead 
of  proceeding  to  the  enforcement  of  his  contract,  which  would  have  at  once  relieved  his  wants,  he  im- 
mediately returned  to  Boston,  and  communicated  to  the  parties  what  he  had  seen  and  believed,  and 
advised  them  to  abandon  the  enterprise,  as,  in  his  judgment,  the  new  kind  of  fabric  would  be  preferred 
in  the  market,  and  that  he  could  produce  a loom  which  would  weave  it  with  greater  facility  than  the 
knotted  counterpanes  could  be  woven.  His  success  in  his  first  effort  of  invention,  and  the  honesty  of 
purpose  manifested  in  this  his  first  business  transaction,  could  not  fail  to  inspire  a degree  of  confidence 
in  his  ability  and  integrity  which  proved  of  great  advantage  throughout  his  subsequent  life,  in  bringing 
all  his  enterprises  to  a successful  issue. 

He  now  entered  into  an  agreement  with  the  same  parties  to  invent  an  automatic  loom  for  weaving 
this  new  species  of  counterpanes,  which  was  afterwards  produced,  and  patented  on  the  24th  of  April, 
1840,  and  put  in  successful  operation.  There  are  now  36  of  these  looms  in  operation  at  Clinton,  Massa- 
chusetts, which  supply  the  principal  demands  of  our  markets. 

Before  he  had  completed  the  counterpane-loom  above  described,  he  had  incidentally  seen  in  New 
Jersey  the  operation  of  weaving  coach-lace  in  hand-looms,  and  not  having  as  yet  realized  any  pecuniary 
advantage  from  his  efforts,  he  determined,  while  progressing  with  the  new  counterpane-loom,  to  direct 
his  attention  to  the  subject  of  weaving  coach-lace.  With  this  view,  he  made  inquiries  of  persons  en- 
gaged in  vending  this  kind  of  fabric,  as  to  the  extent  of  the  consumption  and  the  cost  of  production,  as 
well  as  the  difficulties  of  weaving  it  by  hand.  The  result  of  his  investigation  determined  him  to  make 
the  attempt,  and,  with  the  pecuniary  assistance  of  an  elder  brother,  he  proceeded  to  the  construction  of  a 
loom  which  was  completely  successful.  So  urgent  were  his  necessities  at  this  time,  and  such  was  the 
ardor  with  which  he  pursued  the  subject,  that  he  labored  day  and  night,  scarcely  taking  time  for  food 
and  rest,  and  in  the  short  space  of  six  weeks  from  the  time  that  he  made  the  inquiries  above  referred 
to,  he  had  the  first  loom  in  operation,  and  in  three  months  after  that,  another  and  more  perfect  one,  and 
the  requisite  capital  under  his  control  for  putting  up  a large  establishment.  This  result,  when  we  con- 
sider the  youth  and  inexperience  of  the  inventor,  and  the  peculiar  difficulties  of  the  subject,  seems  to 
us  to  have  no  parallel  in  the  history  of  inventions. 

The  figure  on  coach-lace  is  produced  by  raising  on  the  surface  of  the  ground-cloth  a pile  similar  to 
the  Brussels  carpet,  formed  by  looping  the  warps  over  fine  wires,  which  are  inserted  under  such  of  the 
warps  as  have  been  selected  by  the  jacquard  to  determine  the  figure.  The  warps  are  then  woven  into 
the  body  of  the  cloth,  to  tie  and  fix  the  loops.  The  wires  are  then  withdrawn  and  re-inserted.  Auto- 
matic pincers,  as  if  instinct  with  life,  grasp  the  end  of  the  wire,  draw  it  out  from  under  the  forward 
loops,  carry  it  back  towards  the  lathe,  where  the  warps  are  spread  apart,  forming  what  is  called  the 
open  shed,  and  there  introduce  and  drop  it,  that  the  shed  may  be  closed  and  opened,  that  by  the  throw 
of  the  shuttle,  the  weft-threads,  which  are  to  tie  and  weave  the  warp-threads  into  the  cloth,  may  be 
beaten  up  by  the  reeds.  The  pincers  then  move  back  to  draw  another  wire  from  under  the  formed 
loops,  and  repeat  the  same  operation,  several  such  wires  being  used  at  the  same  time  in  the  cloth,  to 
prevent  the  loops  from  being  drawn  out  by  the  tension  which  is  given  to  the  warps  to  insure  an  even 
and  regular  surface  to  the  fabric ; but  as  there  are  a number  of  these  wires  woven  into  the  cloth,  nearly 
touching  one  another,  it  became  a matter  of  great  difficulty  to  contrive  a mechanism  winch  would  in- 
sure the  taking  of  only  one  of  these  wires  to  draw  it  out,  and  select  the  piroper  one  at  each  operation. 
The  pincers  could  not  practically  be  made  so  narrow,  and  work  so  accurately,  as  to  insure  this.  This 
difficulty  was  overcome  by  an  ingenious  mechanism  placed  on  the  opposite  side  of  the  loom,  which  at 
each  operation  selects  the  required  wire,  and  pushes  it  out  sufficiently  far  beyond  the  ends  of  the 
others  to  be  gripped  by  the  fingers,  which  then  draw  it  out  to  carry  it  back  and  introduce  it  in  the  open 
shed  of  the  warps. 

Some  notion  can  be  formed  of  the  difficulties  which  this  subject  presented,  by  taking  into  considera- 
tion that  the  mechanism  which  works  the  wires  must  operate  in  connection  with  the  mechanism  which 
weaves  the  cloth,  and  the  jacquard  which  produces  the  figure. 

The  cost  of  weaving  coach-lace  was  very  much  reduced  by  this  invention,  and  there  are  now  in  one 
establishment  in  Clinton,  Massachusetts,  96  of  these  looms  in  successful  operation. 

Soon  after  this  was  in  successful  operation,  Mr.  Bigelow  completed  his  second  counterpane-loom,  to 
which  we  have  before  referred,  and  he  had  then  accomplished  the  first  purpose  which  impelled  him  to 
exercise  his  ingenuity — he  had  acquired  the  means  of  completing  his  medical  studies.  But  by  this 
time  he  had  found  much  greater  attractions  in  the  new  career  which  circumstances  had  opened  before 
him — it  was  one  for  which  nature  had  manifestly  intended  him,  and  therefore  invention  was  an  occuna- 


LOOM,  CARPET  WEAVING. 


298 


tion  no  longer  ancillary,  but  paramount,  and  the  success  with  which  he  has  pursued  it  up  to  this  day  L- 
now  distinctly  marked  upon  the  pages  of  our  industrial  history.* 

The  coachdace  loom  was  merely  the  basis  of  a series  of  improvements  then  contemplated,  but 
which  have  since  been  completed,  and  are  now  in  successful  use ; these  improvements  are  in  looms  foi 
weaving  Brussels  and  tapestry  carpeting.  , 

The  weaving  of  Brussels  and  tapestry  carpets  by  automatic  machinery  was  considered  by  many,  a 
few  years  back,  to  be  a mechanical  impossibility,  and,  indeed,  there  were  few  subjects  that  presented 
such  formidable  difficulties.  After  constant  anti  laborious  exertions,  at  times  snatched  from  other 
pressing  engagements,  Mr.  Bigelow  succeeded  also  in  this  undertaking.  There  are  now  28  Brussels 
looms  in  operation  in  one  establishment  in  Clinton,  producing  carpets  which  are  pronounced  by  the 
ablest  judges  to  be  the  best  Brussels  carpets  manufactured  in  any  part  of  the  world,  and  50  tapestry 
looms  in  the  establishment  of  Messrs.  Higgins  & Co.,  New  York;  and  when  those  now  in  contempla- 
tion shall  have  been  completed,  there  will  be  225  looms  in  operation  on  his  plan,  weaving  each,  on  the 
average,  from  18  to  20  yards  per  day,  while  from  3 to  4 yards  per  day  is  tiie  average  product  of  hand- 
looms. 

The  surface  of  the  carpets  woven  by  these  looms  is  more  perfect  and  regular  than  when  woven  by 
hand,  the  texture  of  the  cloth  more  regular,  and,  what  is  of  the  greatest  importance,  the  figures  are  so 
regularly  measured  that,  when  put  together,  they  make  a perfect  match.  This  perfection  in  the  quality 
of  the  cloth  and  the  regularity  of  the  figure  is  in  part  due  to  improvements  which  will  be  described  in 
connection  with  the  ingrain-loom,  as  they  are  applicable  to  the  weaving  of  all  kinds  of  figured  fabrics 
that  require  regularity  in  the  figure. 

Shortly  after  the  completion  of  his  coach-lace  loom,  Mr.  Bigelow  called  on  Mr.  Alexander  Wright,  the 
agent  of  the  Lowell  Manufacturing  Company,  who  was  not  only  a man  of  great  experience  in  manu- 
factures generally,  but  possessed  an  intimate  knowledge  of  the  manufacture  of  coach-lace.  From  him 
he  obtained  valuable  information,  and  in  the  course  of  their  conversation,  Mr.  Wright  called  his  atten- 
tion to  ingrain  carpets,  and  suggested  to  him  the  importance,  as  well  as  the  difficulty,  of  producing  a 
power-loom  for  weaving  that  kind  of  fabric.  The  hint  was  not  thrown  away,  for  as  soon  as  he  had 
completed  his  second  counterpane-loom,  he  bent  his  mind  to  improving  the  ingrain  manufacture,  and  in 
the  year  1839,  through  the  instrumentality  of  Mr.  Wright,  entered  into  an  agreement  with  the  Lowell 
Manufacturing  Company  to  accomplish  this  purpose,  and  before  the  close  of  that  year  had  completed 
the  first  power-loom  for  weaving  two-ply  ingrain  carpets.  This  loom  produced  from  10  to  12  yards  per 
day — the  hand-loom  produced  only  8 yards  per  day. 

When  his  mind  was  first  turned  to  this  subject,  it  presented  these  leading  difficulties.  The  mere 
weaving  of  the  fabric  by  an  automatic  loom  was  easily  effected,  but  to  invent  a loom  which  should  make 
carpet  fast  enough  to  be  economical,  one  which  should  make  the  figures  match,  and  to  have  a good  and 
regular  selvage  and  a smooth,  even  face,  were  very  serious  practical  difficulties.  The  hand-weaver,  by 
the  exercise  of  his  judgment,  can,  to  a certain  extent,  meet  these  contingencies  ; if  the  weft-thread  is  too 
loose  after  the  shuttle  has  been  thrown,  he  can  give  it  a pull  with  the  fingers  to  make  the  selvage  reg- 
ular; if  he  finds  by  measurement  that  by  reason  of  the  irregularity  of  the  weft-threads  or  the  ingrain- 
ing, the  figure  is  being  produced  too  long  or  too  short,  he  gives  more  or  less  force  to  the  lathe  in  beating- 
up  ; and  if  he  finds  that  the  surface  of  the  cloth  is  getting  rough,  he  regulates  the  tension  of  the  warps. 
In  this  way,  by  observation  and  the  exercise  of  skill  and  judgment,  lie  can  approximate,  and  only  ap- 
proximate, to  the  production  of  a good  and  regular  fabric.  But  to  invent  an  organization  of  matter 
which  should  itself  observe,  and  think,  and  judge,  and  do  it  all  with  more  unerring  accuracy  than  man 
himself- — this  was  a result  almost  absurd  to  contemplate,  but  which  it  was  reserved  for  Mr.  Bigelow 
to  attain. 

In  the  first  loom  produced,  he  approximated  more  nearly  than  the  hand-weaver  to  a perfect  match  in 
the  figure,  and  this  he  effected  by  taking  up  the  woven  cloth  by  a regular  and  positive  motion  which 
was  unerring,  the  same  amount  for  every  throw  of  the  shuttle  and  beat  of  the  lathe,  and  as  the  weft- 
threads  are  not  spun  regularly,  and  the  weaving  in  of  the  warp-threads  and  passing  the  different  colors 
from  the  upper  to  the  lower  ply  or  cloth,  (as  ingrain  carpets  are  composed  of  two  or  three  cloths  woven 
and  connected  together,)  to  produce  the  figures,  requiring  sometimes  more  and  sometimes  less  to  make 
a given  length,  he  determined  to  regulate  the  delivery  of  the  warps  as  required  by  their  tension,  thereby 
throwing  the  irregularities  into  the  thickness,  where  it  cannot  be  noticed,  instead  of  in  the  length,  where 
it  would  destroy  the  match  of  the  figures.  And  lie  accomplished  this  by  suspending  a roller  on  the 
woven  cloth,  between  the  lathe  and  the  rollers  that  take  up  the  woven  cloth,  so  that  when  the  cloth 
was  being  woven  too  short,  which  indicates  a deficient  supply  of  warps,  the  roller  would  be  elevated, 
and  by  its  connection  increase  the  delivery  motion  to  give  out  more  warps  ; and  when  the  cloth  was 
being  woven  too  long,  which  indicated  too  great  a supply  of  warps,  the  roller  was  let  down  to  decrease 
the  delivery  motion,  and  thus  reduce  the  supply  of  warps.  In  this  way  the  roller  was  made  to  act  as 
a measurer  and  feeler  of  the  quantity  of  warp  demanded,  and  to  direct  the  supply.  But  this  contri- 
vance, like  the  mind  of  the  hand-weaver,  only  came  in  play  to  prevent  the  progress  of  an  evil  after  it 
had  been  observed.  If  he  had  applied  this  yielding  roller  to  the  unwcven  warps  to  feel  and  ascertain 
the  demand  of  warp  beforehand,  lie  could  have  prevented  the  evil.  He  did  not  then  perceive  that  this 
could  be  done,  for  the  reason  that  this  roller  must  be  sensitive  to  detect  and  indicate  the  amount,  and 
at  the  time  the  lathe  beats  up  the  weft,  the  warps  must  be  rigid  to  resist  the  beat,  or  else  a good  fabric 
cannot  be  produced.  This  was,  however,  accomplished  by  a subsequent  improvement,  which  will  be 
hereafter  described. 


* In  addition  to  the  establishments  at  Lowell,  Thompsonville,  and  other  places  which  have  been  built  solely  for  the  use 
of  his  improvements,  the  new  town  of  Clinton,  Massachusetts,  (which  we  have  mentioned  before,)  situated  twelve  miles 
north  of  Worcester,  and  now  containing  a population  of  nearly  3000,  is  virtually  the  creation  of  Mr.  Bigelow’s  own  mind, 
it  having  been  built  up  by  business  consequent  upou  his  inventions. 


294 


LOOM,  CARPET-WEAVING. 


A smooth  and  even  surface  for  the  cloth  he  obtained  in  the  following  manner.  We  have  already 
pointed  out  that  the  passage  of  the  warp-threads  from  one  ply  or  cloth  to  the  other,  called  ingraining, 
must  necessarily  be  unequal  and  depending  on  the  figure  to  be  produced,  and  that  in  consequence  of 
this  the  warp-threads  that  are  the  most  ingrained  will  be  taken  up  faster  than  those  less  ingrained,  and 
as  all  the  warps  are  of  necessity  rolled  up  on  the  warp-beam  with  equal  tension,  they  can  only  be  given 
out  equally. 

This  seeming  impossibility  he  did  effectually  overcome  in  the  following  manner.  Each  warp-thread 
in  the  usual  way  passes  through  a loop  called  a mail,  attached  to  a card  suspended  from  the  jacquard, 
and  each  card  has  suspended  to  it  a weight,  all  the  weights  being  equal.  The  two  trap-boards  of  the 
jacquard  move  simultaneously,  one  up  and  the  other  down,  and  in  these  movements  they  catch  or  trap 
such  of  the  cords  (determined  by  the  combination  of  cards)  as  are  required  to  bring  up  the  proper  warp- 
threads  at  each  operation  to  produce  the  figure,  leaving  down  such  of  them  as  are  not  required  at  that 
particular  operation ; and  when  the  two  trap-boards  are  on  a level,  and  all  the  warp-threads  connected 
with  them  in  a horizontal  line,  and  those  not  connected  with  them  hanging  down  with  the  weights  sus- 
pended to  them,  the  lathe  beats  up  the  weft-thread  which  lies  between  the  warps  that  are  in  a horizon- 
tal line,  at  the  same  time  exerting  a force  on  the  weft-threads  previously  thrown,  and  beating  them  up 
more  closely. 

Now,  as  the  warp-threads  are  all  connected  at  one  end  to  the  woven  cloth,  and  at  the  other  with  the 
beam,  it  follows  that  those  which  are  hanging  down  in  a bent  line  with  the  weights  suspended  to  them, 
will  receive  a greater  proportion  of  the  force  of  the  beat  of  the  lathe  than  those  which  are  in  a straight 
line  ; and  as  all  the  warp-threads  in  succession  take  this  hanging-down  position,  and  all  of  them  have 
an  equal  weight,  it  follows  necessarily  that  each  warp-thread  in  succession  receives  the  same  pull  at 
the  time  the  lathe  beats  up,  and  that  therefore  all  tendency  to  irregularity  in  the  length  of  the  warp- 
threads  taken  up  by  the  ingraining  will  not  tend  to  produce  an  irregular  surface,  but,  on  the  contrary, 
the  surface  of  the  cloth  will  be  as  smooth  and  even  as  if  all  the  warp-threads  were  equally  taken  up 
in  the  weaving  of  the  cloth,  and  were  under  a constant  and  equal  tension. 

At  the  same  time  he  accomplished  the  making  of  a good  selvage  by  a mechanism  which  handed  in- 
stead of  throwing  the  shuttle  across — an  arm  carried  the  shuttle  half  way  across,  and  another  there  took 
it  and  carried  it  entirely  across.  By  this  means  any  required  degree  of  tension  could  be  given  to  the 
weft  to  make  a smooth  and  even  selvage.  But  although  it  accomplished  this  desirable  object,  it  failed 
to  work  with  sufficient  velocity,  and  thereupon  Mr.  Bigelow,  nothing  daunted,  renewed  his  efforts,  and 
produced  another  loom  with  the  fly-shuttle,  in  which  he  was  enabled  to  make  a good  selvage  by  a 
mechanism  which  gives  a pull  to  the  weft-thread  after  the  shuttle  has  been  thrown,  and  as  the  lathe 
beats  up.  He  also  introduced  other  improvements,  which  will  be  hereafter  described.  This  loom, 
although  it  produced  about  18  yards  per  day,  did  not  satisfy  the  inventor,  and  he  again  applied  himself 
with  renewed  energy  until  he  made  a third  loom,  which  averages  from  25  to  27  yards  per  day  of  two- 
id  y,  and  from  17  to  18  of  three-ply  carpets.  There  are  now  in  operation  at  Lowell,  Thompgonville,  and 
t’nriffville,  450  of  these  improved  looms. 

This  brings  us  to  our  main  purpose,  the  description  of  the  loom  as  it  is  now  worked,  with  all  the 
improvements  which  have  been  made  in  succession  from  the  commencement  to  the  date  of  the  last 
patent,  the  23d  day  of  October,  1849.  But  before  proceeding  to  the  detailed  description  of  this  loom, 
it  may  bo  well  to  state  that  the  improved  method  of  producing  figures  that  will  match,  which  makes 
part  of  this  loom,  was  invented  in  1844,  and  patented  on  the  10th  of  April,  1845,  in  connection  with  a 
loom  for  weaving  plaids  and  ginghams,  which  has  gone  into  extensive  use  at  Clinton,  there  being  now 
580  of  them  in  one  mill,  and  120  in  another. 

In  addition  to  the  various  important  inventions  which  have  been  enumerated,  many  others  have  been 
made  by  Mr.  Bigelow  connected  with  the  details  of  various  kinds  of  looms,  and  for  drying  and  stretching 
fabrics  and  printing  warps,  some  of  which  have  been,  and  others  are  to  be,  patented  both  in  England 
and  in  this  country,  and  which  are  nearly  all  of  decided  practical  utility.  No  one  man  within  our 
knowledge,  either  in  Europe  or  in  this  country,  has  given  to  the  world  so  large  a number  of  valuable 
inventions  as  Mr.  Bigelow,  and  inventions,  too,  evincing  not  only  great  ingenuity,  but  sound  inductive 
powers  of  the  highest  order. 

This  invention  for  weaving  ingrain  carpets,  taking  it  from  the  commencement,  through  all  its  stages, 
to  the  date  of  the  last  patent,  consists : 

1.  In  operating  the  trap-boards  of  the  jacquard  in  a power-loom  simultaneously,  one  up  and  the  other 
down,  instead  of  moving  them  alternately  as  in  the  hand-jacquard,  whereby  either  the  time  required 
for  the  movements  of  the  jacquard,  or  the  velocity  of  their  motion  is  reduced,  the  former  admitting  of 
more  expeditious  weaving  (if  the  other  operations  be  accelerated  in  the  same  ratio),  and  the  latter  re- 
ducing the  liability  to  wear  and  tear.  But  there  are  other  and  important  advantages  incident  to  tnis 
change,  such  as  balancing  the  weight  of  the  harness,  which  in  a jacquard  is  considerable,  for  that  part 
of  the  harness  suspended  to  the  descending  trap-board  balances  the  corresponding  harness  suspended 
to  the  ascending  trap-board,  thus  equalizing  the  resistance  to  the  moving  power,  and  rendering  the 
operations  easier  and  more  regular.  And  still  another  change  is,  that  the  beat  of  the  lathe  takes  place 
after  the  warps  connected  with  the  two  trap-boards  have  passed  and  are  a little  crossed,  and  whilst  the 
remaining  warps  are  in  their  lowest  position,  that  is,  bent  down  by  the  weights  suspended  to  their  trap- 
cords,  so  that  these,  which  like  the  others  are  held  at  both  ends  and  bent  down,  will  receive  a greater 
portion  of  the  force  of  the  beat  of  the  lathe  ; and  as  all  the  warps  in  turn  take  this  position,  and  each 
warp-thread,  when  in  this  position,  is  held  down  by  the  weights — all  of  them  equal — suspended  to  its 
trap-cord,  it  follows  that  all  the  warp-threads,  as  before  stated,  receive  an  equal  tension  in  beating-up 
the  weft-threads,  no  matter  what  may  be  the  variation  in  their  lengths  between  the  woven  cloth  and 
the  yarn-beam,  occasioned  by  the  irregularity  of  the  ingraining.  The  practical  weaver  will  appreciate 
this  as  one  of  the  most  important  advantages  in  weaving  ingrain  carpets,  for  it  presents  a principle  ot 
'.ompensation  and  self-adaptation  to  the  irregularity  of  the  ingraining  due  to  the  figure  never  before 


LOOM,  CARPET-WEAVING. 


295 


attained,  and  by  which  alone  such  fabrics  have  been  made  with  a regular  and  measured  figure,  having 
a face  or  surface  as  smooth  and  even  as  a plain  fabrie. 

2d.  In  taking  up  the  woven  cloth  by  a regular  and  positive  motion,  which  measures  the  length  of 
cloth  to  be  produced  at  each  beat  of  the  lathe  when  employed  in  connection  or  combination  with  a 
method  of  regulating  the  delivering  out  of  the  warps  by  their  tension  in  proportion  to  the  quantity  re- 
quired, and  taken  up  in  the  process  ef  weaving,  and  also  with  the  holding  of  the  warps  rigid  at  the  time 
the  lathe  beats  up  the  weft  to  prevent  them  from  yielding  to  the  force  of  the  beat.  It  will  be  seen  that 
m this  way  the  irregularities  of  the  ingraining  and  of  the  weft-threads  will  be  thrown  into  the  thickness 
instead  of  the  length  of  the  cloth,  for  as  the  lathe  beats  up  the  weft-threads  to  the  same  distance  each 
time,  and  a given  and  measured  length  of  cloth  is  taken  up,  the  same  length  of  cloth  will  be  woven  ; 
but  if  the  warp-threads  were  free  to  yield  at  the  time  the  lathe  beats  up  instead  of  forcing  up  the  weft- 
threads  to  the  required  position,  the  whole  cloth  and  warp  would  be  forced  forward,  and  produce  what 
is  called  a sleazy  fabric ; and  this,  from  its  loose  texture,  would  soon  accumulate  to  such  an  extent  as 
to  stop  the  further  progress  of  weaving.  But  to  prevent  this,  the  moment  the  lathe  begins  to  beat  up 
the  weft-thread,  the  warps  are  held  firm  to  resist  the  force  of  the  beat,  and  thus  insure  the  carrying  of 
the  weft-thread  up  to  the  required  line.  In  this  way  the  two  opposing  or  antagonistic  conditions — sen- 
sitiveness to  deliver  out  the  quantity  required,  whatever  may  be  the  irregularity  of  the  demand,  and 
non-yielding  to  resist  the  beat  of  the  lathe — are  reconciled  to  produce  the  important  result  of  weaving 
ingrained  fabrics  with  a regular  and  measured  figure ; a result  never  before  attained,  even  with  the 
hand-loom. 

3d.  In  mounting  the  shuttle-boxes  in  independent  frames  at  the  sides  of  the  lathe,  which  in  this  way 
becomes  a mere  guide  to  the  shuttles  as  they  are  thrown  from  one  side  to  the  other.  The  advantages 
of  this  arrangement  are,  first,  the  weight  of  the  lathe  (which  must  have  a considerable  range  of  motion 
and  a high  velocity)  is  greatly  reduced,  and  will  not,  therefore,  require  so  much  power  to  operate  it ; for 
in  weaving  two  and  three  ply  carpets,  particularly  such  as  have  a variety  of  colors,  the  shuttle-boxes 
are  numerous  and  heavy,  and  in  proportion  to  the  number  and  weight  would  be  wasteful  of  power  and 
liable  to  derangement  if  carried  by  the  lathe.  Secondly,  it  affords  a surer,  easier,  and  more  durable 
mode  of  operating  the  shuttle-boxes  to  shift  the  shuttles  for  the  changes  in  the  colors  of  the  pattern , 
and,  lastly,  it  is  very  efficient  in  producing  a good  selvage,  for  the  moment  the  shuttle  is  thrown  the 
weft-thread  is  held  on  a permanent  bed  by  fingers,  so  that  as  the  lathe  beats  it  up,  the  pressure  of  the 
fingers  affords  the  required  friction  to  pull  the  weft-thread  to  make  a tight  and  regular  selvage ; and 
the  shuttle-boxes  being  in  independent  frames,  the  weft-thread  is  not  drawn  out  of  its  position  in  the 
cloth  by  the  back  movement  of  the  lathe,  as  in  the  ordinary  loom.  Thus,  the  weft-threads,  when  once 
beaten  up,  are  retained  in  that  position,  and  their  parallelism  in  the  cloth  is  insured. 

4th.  In  connection  with  the  mounting  of  the  shuttle-boxes  in  independent  frames  by  the  side  of  the 
lathe,  using  one  cam  and  roller  to  work  the  lathe,  and  another  to  hold  it  in  a fixed  position  during  the 
throw  of  the  shuttle,  one  of  the  said  cams  being  on  the  lathe-shaft,  and  the  roller  which  works  in  con- 
nection with  it  on  the  lathe,  and  the  other  cam  on  the  lathe,  and  its  roller  or  wrist  attached  to  the  first 
cam ; one  of  the  cams  being  concentric  to  hold  the  lathe  in  a fixed  position  during  a part  of  the  rotation, 
and  whilst  the  shuttle  is  being  thrown,  with  its  ends  eccentric,  that  the  roller  may  enter  and  leave  it  as 
the  lathe  is  either  gradually  started  or  gradually  arrested,  and  the  other  cam  being  of  any  form  suitable 
for  giving  the  lathe  the  required  varying  motions. 

By  this  means  the  cam  and  roller,  which  operate  the  lathe,  and  which  are,  in  consequence,  exposed 
to  all  the  strain  and  wear  and  tear,  are  not  used  to  hold  the  lathe  in  a fixed  position  during  the  throw 
of  the  shuttle. 

5th.  In  combining  with  a power  or  automatic  loom  four  series  of  shuttle-boxes,  two  on  each  side  in 
separate  frames  at  the  sides  of,  and  independent  of  the  lathe,  the  said  four  series  of  shuttle-boxes 
receiving  motion  from  the  loom  or  from  some  first  mover  in  connection  with,  or  operating  in  unison  with 
the  loom ; one  series  of  these  shuttle-boxes  on  one  side  being  for  the  purpose  of  holding  all  the  shuttles 
of  the  various  colors  required  for  one  ply  of  the  carpet,  and  the  corresponding  series  on  the  other  side 
to  contain  the  shuttles  of  the  various  colors  for  the  other  ply,  so  that  by  the  up  and  down  motions  of 
these  boxes,  the  various  changes  of  colors  can  be  effected,  the  other  two  series  of  shuttle-boxes  being 
merely  to  receive  and  return  the  shuttle  from  and  to  the  first  series.  In  view  of  this,  for  some  patterns 
the  second  or  receiving  shuttle-boxes  may  be  single ; but  for  others  they  are  required  to  be  double,  as 
the  colors  are  required  to  be  alternated. 

6th.  In  combining  with  the  lathe  and  the  shuttle-boxes  in  separate  and  independent  frames  by  the 
sides  thereof,  hinged  guides  to  guide  t]^  shuttles  from  the  one  to  the  other,  and  to  yield  and  thereby 
prevent  breaking  whenever  a shuttle,  ot  any  part  of  it,  fails  to  enter  the  shuttle-boxes. 

7tli.  In  giving  to  the  jacquard,  which  determines  the  figure,  a separate  organization  independent  of 
the  loom  which  forms  the  cloth,  that  the  various  motions  of  the  jacquard  may  be  taken  from  or  given 
hy  a shaft  or  shafts  within  it,  and  simply  deriving  its  or  their  motions  from  some  part  of  the  loom,  or 
from  some  first  mover  corresponding  with  or  regulated  by  the  motion  of  the  loom  or  part  thereof,  that 
the  motions  of  the  jacquard  may  correspond  with  those  of  the  loom.  In  this  way  the  motions  of  the 
jacquard  are  rendered  more  accurate  and  steady,  and  the  weight  of  the  moving  parts  is  greatly  reduced. 

Prior  to  this  invention,  in  all  looms  for  weaving  by  power  in  connection  with  the  jacquard,  all  the 
motions  of  the  jacquard  were  derived  directly  from  some  part  of  the  loom  and  communicated  by  con- 
necting-rods, which  were  necessarily  of  great  length.  The  principal  difficulties  attending  this  old  mode 
of  construction  and  organization  were  the  inaccuracy  of  the  motions  by  reason  of  the  great  length  of  the 
connecting-rods,  the  liability  to  derangement,  and  the  labor  and  difficulty  of  adjusting  the  connections  to 
the  varying  lengths  of  the  cords  of  the  harness  as  they  are  affected  by  atmospheric  changes.  All  of 
which  difficulties  are  avoided  or  greatly  reduced  by  this  separate  organization. 

8 th.  In  making  the  whole  frame  of  the  jacquard  adjustable  at  one  operation  relatively  to  the  frame 
of  the  loom,  that  the  distance  between  the  two  may  be  adjusted  to  the  varying  lengths  of  the  cords  oi 


2665 


296 


LOOM.  CARPET- WEAVING. 


LOOM,  CARPET-WEAVING. 


297 


the  harness,  whereby  the  utmost  nicety  in  the  adjustment  can  be  obtained,  and  at  the  same  time,  in  con- 
nection with  the  separate  organization,  avoiding  the  necessity  of  adjusting  the  connections  when  it  be- 
comes necessary  to  adjust  the  jacquard  to  the  varying  lengths  of  the  cords  of  the  harness,  for  the 
jacquard,  having  a separate  organization,  no  change  becomes  necessary  in  its  own  connections. 


9tn.  In  communicating  the  required  motions  to  the  picker-staffs  and  to  the  apparatus  for  shiftily  the 
shuttle-boxes  hung  in  pendulous  frames  at  the  sides  of  and  independent  of  the  lathe,  from  a shaft  or 
shafts  above,  whereby  is  avoided  the  serious  difficulty  before  experienced  of  communicating  the  motions 


298 


LOOM,  CARPET-WEAVING. 


from  a shaft  or  shafts  below  to  the  picker-staff  and  the  apparatus  for  shifting  the  shuttle-boxes  which 
must  be  attached  to  or  connected  witli  the  shuttle-box  frames  that  vibrate  on  axes  above.  By  this  im 
proved  arrangement  the  motions  are  derived  from  a shaft  or  shafts  coincident  with  or  near  to  the  axis 
of  motion  of  the  pendulous  frames  that  carry  the  shuttle-boxes,  instead  of  being  below,  where  the  frames 
have  the  greatest  motion. 


10th.  In  introducing  in  power-looms  a reversing  motion.  Before  this,  power-looms  were  simply  pro 
vided  with  the  means  of  disconnecting  the  motive  power,  and  arresting  the  momentum  of  the  moving 
parts  to  enable  the  attendant  to  piece  the  threads,  or  to  do  what  might  be  necessary  preparatory  to 
re-starting ; but  as  the  loom  cannot  always  be  stopped  with  the  parts  in  the  positions  required,  the 


LOOM,  CARPET- WEAVING. 


299 


ittendant  has  to  reverse  the  motion  of  the  loom  by  the  application  of  hand-power  to  the  driving-pulley , 
a mode  of  procedure  attended  with  waste  of  time  and  great  inconvenience,  for  the  attendant  must  leave 
L’is  usual  position  to  go  to  the  driving-pulley,  and  in  heavy  looms,  such  as  are  used  for  weaving  carpets, 
much  strength  is  required  to  set  the  machinery  in  motion.  But  by  the  use  of  a reversing  motion,  the 
attendant,  without  leaving  his  place,  and  by  the  simple  motion  of  a lever,  can  operate  the  mechanism 
in  either  direction  and  to  any  extent  desirable  to  bring  the  parts  to  a proper  position  for  piecing  the 
threads,  &c.,  and  re-starting. 

In  the  accompanying  drawings,  Fig.  2G65  is  a plan  of  the  loom  in  the  present  improved  form. 

Fig.  2666,  a plan  of  the  loom  below  the  jacquard. 

Fig.  2667,  a front  elevation  ; Fig.  2668,  a back  elevation. 

Fig.  2669,  an  elevation  of  the  left-hand  side,  without  the  jacquard;  Fig.  2670,  a vertical  section,  with 
the  jacquard ; and  Fig.  2671  another  section. 

In  the  said  drawings,  A represents  the  power-loom,  and  B the  jacquard-frame  resting  on  beams 
C C C'  O',  supported  on  columns  D from  the  main  floor. 

The  pendulous  frames  E E,  which  carry  the  series  of  shuttle-boxes,  are  arranged  on  each  side  of  the 
lathe,  and  independent  thereof,  and  are  hung  on  arbors  F F,  at  the  top,  on  which  they  vibrate.  These 
frames  are  vibrated  back  and  forth  simultaneously,  in  opposite  directions,  at  each  throw  of  the  shuttle, 
so  that  the  first  series  of  shuttle-boxes  on  one  side,  and  the  second  or  receiving  boxes  on  the  other,  shal1 


oe  in  line  with  the  race-beam  of  the  lathe  when  one  shuttle  is  thrown,  and  vice  vena  for  the  next  tnrow 
And  these  motions  are  obtained  from  a cam  A'  on  the  main  cam-shaft  B’  of  the  loom,  which  acts  on  an 
arm  Cs  of  a rock-shaft  D that  extends  across  the  loom.  This  rock-shaft  carries  at  each  end  a cogged 
sector  E , which  engages  a pinion  F'  on  a short  arbor  G'  (one  on  each  side)  which  carries  two  cranks 
U , one  at  each  end,  the  wrists  of  which  are  fitted  to  grooves  I’  I'  in  the  pendulous  frames,  so  that  as  the 


300 


LOOM,  CARPET- WEAVING. 


arbors  G'  G'  are  vibrated  by  the  rotation  and  peculiar  form  of  the  cam  A'  and  the  connections,  the 
pendulous  frames  are  vibrated  in  opposite  directions,  and  there  held  during  the  throw  of  the  shuttle, 
and  then  back  again. 

The  driving-shaft  a of  tire  loom  has  a fast  and  loose  pulley  b c on  one  end,  which  receives  the  driving- 
belt  from  any  first  mover  in  the  usual  way ; and  on  the  other  end  the  said  shaft  has  a bevel-pinion  d. 


which  takes  into  and  drives  a bevel-wheel  c on  the  lower  end  of  a line-shaft  f which  extends  up  to  and 
has  its  upper  bearing  in  a box  g attached  to  one  of  the  beams  C',  the  upper  end  of  the  said  shaft  having 
a bevel-pinion  h,  which  engages  and  carries  a bevel-wheel  i on  one  end  of  a horizontal  shaft  j,  which  has 
its  bearings  in  boxes  attached  to  the  tops  of  the  beams  C.  It  is  from  this  horizontal  shaft  that  all  the 
jacquard  and  shuttle  motions  are  taken. 


LOOM,  CARPET- WEAVING. 


301 


On  this  shaft  j there  is  a cogged  wheel  R which  communicates  motion  to  a cog-wheel  i on  the  jac- 
quard-shaft m,  by  the  medium  of  a connecting  pinion  n,  which  turns  on  a stud-pin  o adjustable  in  a 
sector-mortice  p,  the  curve  of  which  is  struck  'from  the  centre  of  the  shaft  m.  that  the  pitch-line  of  the 
said  connecting  pinion  may  be  always  at  the  same  distance  from  the  axis  of  the  wheel  i,  when  its  stud- 
pin  is  shifted.  By  this  means,  when  the  jacquard-frame  is  adjusted,  the  connecting  pinion  can  also  be 
shifted  and  adjusted  relatively  to  the  pinion  k on  the  shaft  j. 

The  frame  B of  the  jacquard,  as  already  intimated,  instead  of  being  permanently  attached  to  the 
-beams  C'  O',  is  free  to  slide  vertically,  for  the  purpose  of  vertical  adjustment,  to  suit  any  change  in  (lie 
length  of  the  harness.  The  side-pieces  q q of  the  frame  of  the  jacquard  embrace  the  transverse  beams 
C'  C',  and  slide  in  them  accurately,  but  freely. 

The  jacquard-frame  rests  on  two  horizontal  slides  S S,  which  are  adapted  to  slide  on  the  transverse 
beams  (7  C',  the  upper  surfaces  of  each  being  formed  with  two  inclined  planes  1 1,  one  for  each  of  the 
sides  of  the  jacquard-frame  to  rest  on,  so  that  when  these  two  slides  are  moved  to  the  one  side  or  the 
other,  the  entire  jacquard-frame  will  be  elevated  or  depressed  relatively  to  the  loom  below,  the  stud-pin 
of  the  connecting  pinion  n being  at  the  same  time  adjusted  in  its  sector-mortice  to  adjust  the  pitch-line 
of  the  cogged  geering.  The  slides  S S are  operated  simultaneously  by  a hand-wheel  «ona  short  arbor 
v in  front,  which  carries  a worm  w that  engages  the  cogs  of  a wheel  *on  a shaft  y that  carries  two 
pinions  z (only  one  shown  in  the  figures)  that  engage  the  cogs  of  a rack  a on  each  of  the  slides. 

For  the  purpose  of  adjustment,  it  is  only  necessary  to  turn  the  hand-wheel  until  the  jacquard  is 


brought  to  the  required  position,  and  then  to  adjust  the  geering  by  shifting  the  stud-pin  of  the  connecting 
pinion,  the  thread  of  the  worm  on  the  hand-wheel  arbor  and  the  inclination  of  the  wedges  being  suffi- 
cient to  retain  the  parts  in  a permanent  position. 

The  required  motions  of  the  trap-boards  b'  and  c,  and  the  journals  d'  e f g,  are  derived  from  the 
jacquard-shafts  m,  which,  as  described  above,  receive  a continuous  rotary  motion  from  the  driving-shaft 


302 


LOOM,  CARPET- WEAVING. 


of  the  loom  below,  and  the  proportions  of  the  geering,  as  represented  in  the  figures,  should  be  such  as 
to  give  to  the  jacquard-shaft  one  revolution  for  every  two  of  the  lathe-shaft  of  the  loom.  On  each  end 
of  the  jacquard-sliaft  m there  are  two  cams  K K and  i i',  which  are  all  of  the  same  form  as  represented 
in  the  figures.  The  cams  h'  h'  are  placed  on  opposite  ends  of  the  shaft,  and  in  corresponding  positions 
to  work  the  trap-board  b',  and  the  other  two  cams  i'  i are  arranged  in  the  same  manner,  but  on  the 
opposite  side  of  the  axes  of  the  shaft  m,  to  operate  the  other  trap-board  c , as  one  trap-board  descends 
whilst  the  other  ascends ; and  the  form  and  position  of  the  cams  should  be  such  that  one  trap-board 
shall  begin  to  ascend  as  the  other  begins  to  descend.  There  are  four  levers  j'j'k'k'  placed  above  the 
cams  and  operated  by  them,  each  lever  being  hung  on  a fulcrum-pin  at  the  rear  of  the  frame,  and  having 
a roller  m which  bears  on  the  cam.  The  two  levers//  are  connected  with  the  ends  of  the  trap-board 
U by  connecting-rods  in’  m\  that  the  cams  liK  may  communicate  the  required  motions  to  it;  and  the 


other  levers  k’  k'  are  in  like  manner  and  for  the  same  purpose  connected  to  the  other  trap-board  o',  by 
similar  rods  n n.  In  this  way  it  will  be  perceived  that  the  required  alternate  up  and  down  motions 
are  given  to  the  two  trap-boards.  The  same  cams  and  levers  are  employed  for  operating  the  four 
journals  d'  e'  f <j . The  two  journals  are  alternately  elevated  with  the  trap-board  b' , and  the  other  two 
f </  are  in  like  manner  operated  with  the  other  trap-board  c,  which  is  effected  in  the  following  manner : 
To  the  ends  of  the  four  levers/  and  k’  are  jointed  four  rods  o'  o'  o'  o',  (one  to  the  end  of  each,)  the  upper 
ends  of  which  play  in  slots  p p'  p p in  the  top  plate  q of  the  jacquard-frame — these  slots  being  of  such 
length  that  the  rods  can  vibrate  sufficiently  to  pass  from  one  journal  to  the  other.  The  upper  ends  01 
these  rods  are  rounded,  and  enter  sockets  in  the  under  face  of  the  ends  of  the  journals,  so  that  when 
brought  under  either  of  the  journals,  when  the  levers  are  raised  by  the  cams,  the  journals  will  be  ele- 
vated. As  there  are  two  journals  for  each  trap-board,  and  these  are  alternately  elevated  with  the 
sorresponding  trap-board,  the  lifting-rods  must  be  alternately  shifted  from  the  one  to  the  other.  As  the 


LOOM,  CARPET- WEAVING. 


30-3 


rods  are  so  jointed  as  to  incline  outwards,  when  vibrated  they  will  fall,  by  gravity,  against  the  outer 
ends  of  the  slots  p,  which  are  so  located  as  to  hold  the  rods  in  a position  to  catch  under  the  two  outer 
journals  d ang  g. 

In  this  position,  when  either  of  the  trap-boards  are  elevated,  one  of  the  journals  will  be  carried  up 
with  it;  but  when  the  other  journals  are  to  be  lifted,  the  rods  o'  are  to  be  shifted  from  the  outside  jour- 
nals to  the  inside  ones,  and  this  is  effected  by  cams  r r s'  s,  two  on  each  side  of  the  frame,  and  on  one 


and  the  same  shaft  t',  receiving  motion  from  the  shaft  to'  by  two  cog-wheels,  u v.  These  four  cams  are 
all  of  the  same  form  as  represented  in  the  plates,  and  arranged  in  two  sets,  one  of  each  set  being  on 
each  end  of  the  shaft,  and  the  position  of  the  two  sets  relatively  to  each  other  will  depend  upon  the 
form  and  position  of  the  levers  which  they  operate.  On  each  side  of  the  frame  there  are  two  levers, 
in  x,  (the  two  sets  corresponding  in  every  particular,)  that  vibrate  at  y'  on  the  same  arbor,  the  one  w of 
which  bears  by  the  disposition  of  its  weight  on  the  periphery  of  one  of  the  cams  r,  and  the  other  x on 
one  of  the  cams  s'.  The  arm  of  each  of  these  levers  acts  against  one  of  the  rods  o',  so  that  there  is  one 
Buch  lever  and  cam  for  each  rod  o' ; and  as  the  shaft  t’  of  these  cams  makes  but  one  rotation  for  every 


304 


LOOM,  CARPET-WEAVING. 


two  of  the  jacquard-shaft,  the  levers  w'  and  x will  act  upon  the  corresponding  rods  o'  at  every  alternate 
descending  motion  of  each  trap-board. 

The  form  of  the  cams  r'  and  s'  is  such  that  during  one  rotation  of  the  jacquard-shaft  m,  they  elevate 
one  set  of  levers  w w,  to  shift  the  two  corresponding  rods  o'  o'  from  one  journal  to  the  other,  and  during 
the  next  rotation  of  the  jacquard-shaft  they  recede  to  permit  these  rods  to  fall  back,  whilst  the  other 
set  of  levers  x x'  shift  the  other  two  rods  o'  o'  from  one  to  the  other  of  the  other  set  of  journals,  the 
next  rotation  liberating  these  and  shifting  the  first  set.  In  this  way  it  will  be  seen  that  during  one 
operation,  when  the  trap-board  c descends,  the  journal  g descends  with  it,  the  trap-board  b'  at  the  same 
time  being  carried  up  and  down  with  the  journal  e'.  At  the  end  of  this  motion  the  cams  r r throw  out 
the  levers  w w,  which  shift  the  rods  o'  o'  to  the  journal  /';  at  the  next  operation  the  trap-board  c is 


elevated,  and  with  it  the  journal  /',  the  trap-board  b'  at  the  same  time  descending,  and  with  it  the 
journal  e,  and  when  this  has  reached  the  end  of  its  down  motion,  the  rods  o'  o'  continue  the  motion 
down  sufficiently  to  clear  the  sockets  of  the  journals,  and  then  by  their  own  weight  the  rods  fall  back 
to  the  journal  d',  to  be  ready  to  carry  it  up  at  the  next  upward  motion  of  the  trap-board  b' ; and  when 
this  takes  place  the  trap-board  c descends,  and  with  it  the  journal/',  at  the  end  of  the  down  motion  of 
which  the  rods  o'  o'  fall,  to  come  under  the  journal  g\  so  that  at  the  next  upward  motion  of  the  trap- 
board  c,  this  journal  may  be  elevated,  during  which  the  trap-board  b'  descends,  and  with  it  the  journal 
d and  when  this  is  entirely  down,  the  cams  s'  s'  act  upon  the  levers  x x,  which  shift  the  rods  o'  o'  to 
the  journal  e.  Thus  the  journals  d'  and  e are  alternately  carried  up  and  down  with  the  trab-board  b’ 
and  the  other  two  journals/  and  g'  with  the  trap-board  c. 

The  journals  of  the  card-prism  a?  (of  the  usual  construction)  are  hung  in  the  rods  P P,  which  slide 
horizontally  on  the  sides  of  the  jacquard-frame,  and  which  at  the  back  are  jointed  to  two  arms  c2  c 2 in 
a rock-sliaft  d2,  from  which  projects  another  arm  e2,  connected  by  a rod  f2  with  a treadle  g2  that  vibrates 


LOOM,  CARPET-WE AVIN (}. 


305 


on  a fulcrum-pin  at  the  back,  its  front  end  being  provided  with  a weight  h 2 of  sufficient  gravity  to  push 
out  the  prism,  the  levers  being  elevated  to  draw  in  the  prism  by  a cam  i2  on  the  jacquard-shaft  m. 
The  form  of  the  cam  i2,  and  its  position  relatively  to  the  trap-board  cams,  must  be  such  as  to  bring  the 
prism  into  action  while  the  trap-boards  are  at  rest. 

The  straps  k 2 k 2 k 2 k 2 of  the  picker-staffs  /2j2  extend  up  to,  and  are  secured  each  to  a picker-lever  P, 
there  being  two  such  levers  on  each  side,  which  are  jointed  at  their  back  end  to  the  upper  arm  nP  ot 
two  levers  iP  n2  that  vibrate  on  a stud-pin  o2  attached  to  one  of  the  beams  0. 

The  levers  iPiP  constitute  each  two  arms,  at  right  angles  with  the  arm  in 2 the  back  one  carrying  a 
weight/)2  which  must  be  sufficient  to  carry  back  the  picker-lever  P,  and  the  forward  end  carries  a 
roller  q 2 which  bears  up  against  the  periphery  of  a cam-wheel  r2,  so  that  when  the  roller  bears  on  the 
periphery  of  this  wheel,  the  picker-lever  is  pushed  and  held  forward  to  the  full  length  of  its  longitudi- 
nal motion ; but  when,  by  the  rotation  of  the  wheel,  the  roller  is  permitted  to  enter  a depression  in  its 
periphery,  the  picker-lever  is  drawn  back.  As  stated  above,  and  as  represented  in  the  plates,  there 
are  two  picker-levers  on  each  side,  one  for  each  picker-staff,  and,  therefore,  two  inverted  T levers  rn?  n‘, 
and  one  cam-wheel  r2,  for  each  lever  rrP  rP.  The  forward  ends  of  the  picker-levers  P work  between  verti 
cal  guides  s2,  to  prevent  lateral  play,  and  they  are  each  provided  with  a hook  P,  which,  when  the  lever  is 
drawn  back,  hooks  into  the  end  of  the  picker-treadle  u2,  which  is  made  of  sufficient  breadth  to  receive 
and  operate  the  two,  there  being  one  treadle  on  each  side,  and  operated  at  the  proper  periods  of  time 
by  two  cams  v 2 v e,  one  for  each  treadle,  and  placed  on  opposite  ends  of  the  shaft  /',  as  before  described. 

Each  cam  has  two  projections  opposite  to  each  other,  so  as  to  operate  the  treadle  twice  for  each  ro- 
tation, and  the  projections  of  the  two  cams  are  placed  in  the  same  line,  so  that  the  two  treadles  are 
operated  at  the  same  time,  and  the  shaft  makes  one  rotation  for  every  two  beats  of  the  lathe  of  the 
loom ; hence  the  treadles  are  both  worked  once  for  each  beat.  This  simultaneous  working  of  the  trea- 
dles is  rendered  necessary,  because  two  shuttles  have  frequently  to  be  thrown  in  succession  from  the 
same  side.  As  both  treadles  are  operated  for  each  beat  of  the  lathe,  and  there  are  two  picker-staffs 
on  each  side,  at  each  beat  of  the  lathe  one  of  the  picker-levers  P must  be  put  in  connection  with  one  of 
the  treadles,  whilst  the  other  remains  disconnected.  This  is  effected  by  drawing  back  the  picker-lever 
which  is  to  be  operated,  until  its  hook  catches  into  one  of  the  treadles,  and  this  must  be  done  whilst 
the  treadle  is  down,  and  at  rest.  The  manner  in  which  the  picker -treadles  are  drawn  back  to  effect 
the  hooking  on  to  the  treadle  has  already  been  described,  as  also  the  manner  of  pushing  them  forward 
to  carry  their  hooks  beyond  the  range  of  motion  of  the  treadles,  and  it  only  remains  to  explain 
how  the  succession  is  determined.  This  is  done  by  means  of  four  cam-wheels  r2,  which  act  on 
the  four  levers  rP  vP,  as  described  above.  These  cam-wheels  are  formed  with  a series  of  cam-like 
depressions  v?  made  at  equal  distances  around  the  periphery,  into  each  of  which  the  rollers  of  the 
levers  rP  enter;  and  when  this  takes  place,  the  weights  on  the  levers  n 2 draw  the  picker-levers  so  far 
back  that  the  treadles  in  rising  catch  under  the  hooks  and  elevate  the  picker-levers,  and  the  further 
rotation  forces  out  the  rollers  from  the  cam-like  depression  on  to  the  periphery  of  the  circle  of  the 
wheels,  which  forces  the  picker-levers  so  for  forward  as  to  disengage  the  hooks.  There  must  be  as 
many  of  these  cam-like  depressions  in  each  cam-wheel  as  the  number  of  changes  of  shuttle  required 
in  the  kind  of  fabric  to  be  woven ; eight  being  the  number  represented  in  the  plates  for  eight  changes 
of  shuttle.  To  each  of  these  depressions  is  fitted  a block,  which  when  put  in  renders  the  periphery  of 
the  wheel  cylindrical ; and  when  all  are  in,  the  picker-levers  will  not  be  engaged  or  hooked  by  the 
treadle,  and  hence  no  shuttle  will  be  thrown ; and,  therefore,  in  setting  the  loom  for  any  particular 
kind  of  fabric,  the  operator  will  leave  out  of  each  of  the  cam-wheels  as  many  of  these  blocks,  and  in 
the  order  required,  as  may  be  necessary  for  operating  the  picker-staffs  in  the  order  required  for  the 
succession  of  the  shuttles.  The  four  cam-wheels  r'2  are  on  a shaft  x2,  parallel  with,  and  receiving  motion 
from  the  shaft/,  by  a cog-wheel  and  pinion  y"2  z2,  the  shaft  x 2 making  one  rotation  for  four  of  the  shaft 
j.  The  plates  represent  the  back,  or  receiving  shuttle-boxes  c3  c3,  as  consisting  of  two  on  each  side, 
although  for  some  kinds  of  fabrics  but  one  is  required,  in  which  case  they  are  not  required  to  be  oper- 
ated in  the  pendulous  frames.  When  the  two  are  used  on  each  side,  they  are  adapted  to  slide  in  the 
back  of  the  pendulous  frames,  and  are  suspended  each  to  one  end  of  a lever  b3,  by  a connecting-rod  d 3, 
the  rear  end  of  the  said  levers  being  provided  with  a sufficient  weight  e3  to  lift  the  boxes,  in  order  to 
bring  the  lower  box  of  the  series  in  line  with  the  race-beam  of  the  lathe ; and  when  the  upper  box  is 
to  be  let  clown  to  receive  a shuttle,  the  weighted  end  of  the  lever  is  elevated  by  a cam  a3  on  the  end 
of  the  shaft  re2,  before  described  as  carrying  the  cams  to  determine  the  succession  of  the  motions  of  the 
picker-staffs.  The  form  of  the  cams  a?  will  of  course  depend  on  the  pattern  to  be  woven,  and  as  they 
are  on  the  ends  of  the  shaft,  they  can  be  removed  and  other  cams  of  different  forms  substituted.  The 
front  series  of  shuttle-boxes  f3f3  are  represented  as  consisting  of  twelve  shuttle-boxes  on  each  side, 
adapted  to  work  patterns  requiring  twenty-four  shuttles.  As  the  two  series  are  operated  in  like  man- 
ner, it  is  only  necessary  to  describe  one  series. 

These  shuttle-boxes  f3  are  all  connected  together,  and  slide  in  the  front  of  the  pendulous  frame,  and 
are  suspended  to  a chain  a°  that  is  attached  to  and  winds  on  a barrel  b 6 on  the  arbor  F of  the  pendu- 
lous frame;  and  this  arbor  carries  another  barrel,  on  which  winds  another  chain  c6  that  passes  over  a 
guide-pulley,  and  has  a counter-weight  d 6 suspended  to  it  to  counterbalance  the  shuttle-boxes,  the 
weight  being  made  in  sections,  that  it  may  be  regulated  to  suit  the  number  of  shuttles  employed.  As 
the  shuttle-boxes  are  connected  with  the  arbor  F,  it  will  be  obvious  that  then-  weight  will  carry  them 
down,  when  permitted  so  to  do  by  the  turning  of  the  arbor  in  one  direction,  and  that  they  will  be  lifted 
when  the  arbor  is  turned  in  the  reverse  direction.  On  the  inner  end  of  the  said  arbor  there  is  a cog- 
wheel e“,  the  cogs  of  which  engage  a pinion/6  of  one-sixth  its  diameter, which  has  attached  to  its  face  a 
wheel  (/  with  a portion  of  its  periphery  cut  off,  against  which  bears  a stop  IP  on  the  end  of  a rod  sur- 
rounded by  a helical  spring  P,  which  forces  the  stop  against  the  periphery  of  the  wheel  cut  out,  so  that 
when  the  wheel  is  turned,  the  pressure  of  the  stop  shall  have  the  effect  to  stop  the  wheel,  to  aid  in 
bringing  the  parts  to  a state  of  rest  in  the  proper  position,  and  there  hold  them.  The  wheel  e6  has  six 
Vol.  II. — 20 


BOG 


LOOM,  CARPET- WEAVING. 


pins  projecting  from  its  inner  face,  at  equal  distances  apart,  and  so  proportioned  that  the  turning  of  the 
wheel  the  distance  of  one  of  these  pins  shall  shift  the  shuttle-boxes  to  a distance  required  for  one 
change.  There  are  two  rods/5/1,  one  on  each  side  of  the  axis  of  the  wheel  c-°,  and  so  far  apart  that 
when  thrown  out  they  will  not  touch  the  pins  on  the  -wheel.  These  rods  are  jointed  to  a sliding-frame 
ke  above,  adapted  to  work  on  a guide-rod,  and  suspended  to  a lever  p3  that  carries  a roller  /t3  working 
in  a cam-groove  i3  on  the  shaft  f,  which  makes  two  revolutions  to  each  beat  of  the  lathe,  so  that  the 
lever  and  rods  f will  be  carried  up  and  down  every  alternate  beat  of  the  lathe  ; and  there  being  a 
similar  arrangement  on  each  side  of  the  loom,  with  the  cams  placed  on  opposite  sides  of  the  axis,  one 
set  will  be  wrorked  for  each  beat  of  the  lathe.  The  rods  ff  before  described,  are  drawn  together  by 
a helical  spring  l 6 to  bring  their  inner  edges  against  the  pins  of  the  wheel  e6.  Their  inner  edges  are 
formed  each  with  a hook  m°,  so  that  when  drawn  up  the  hooks  catch  under  the  pins  to  turn  the  wheel ; 
and  as  the  two  rods  are  on  opposite  sides  of  the  axis  of  the  wheel,  the  wheel  can  be  turned  in  either 
direction  if  the  appropriate  hook  be  brought  in  the  required  position.  The  manner  in  which  the  rods 
are  drawn  inwards  has  been  pointed  out.  They  are  kept  out  so  that  their  hooks  shall  not  engage  the 
pins  as  they  are  moved  up  and  down  at  each  operation,  by  means  of  weights  ne  n?  (represented  by 
dotted  lines)  suspended  to  cards  o6  o6  attached  to  levers  rf  rf,  which  by  the  force  of  the  weights  are 
made  to  bear  against  the  inner  faces  of  the  said  rods  f,  and  to  overcome  the  tension  of  the  spring 
which  tends  to  draw  them  in.  The  weights  n 6 n 0 are  connected  each  to  one  of  the  cards  (not  repre- 
sented) of  the  jacquard,  so  that  when  either  weight  is  lifted  by  the  jacquard,  the  corresponding  rod  f 
will  be  drawn  inwards  by  its  spring,  and  hence,  when  drawn  up  by  the  rotation  of  the  cam,  as  before 
described,  its  hook  will  catch  under  one  of  the  pins  and  turn  the  wheel,  and  hence  shift  the  shuttle- 
boxes.  As  these  movements  are  very  quick,  and  it  is  important  that  the  shifting  motion  be  accurate, 
the  two  rods  are  bent  in  at  their  lower  ends  to  such  an  extent,  that  when  drawn  up,  with  the  hook  of 
one  turning  the  wheel  at  the  required  extent  of  motion,  the  said  bent  projection  of  the  other  comes  in 
contact  with  another  one  of  the  pins  on  the  wheel,  and  thus  effectually  stops  the  movements.  In  this 
way  it  will  be  seen  that  by  the  punching  of  the  cards  that  operate  the  needles  connected  with  the 
cards  that  control  the  weights  to  disengage  the  hooks,  the  shuttles  can  be  shifted  to  suit  any  variety  of 
changes  of  color  in  the  pattern. 

The  connection  between  the  frames  that  carry  the  hook-rods  ff  and  the  levers  operated  by  the 
cams  to  give  the  shuttle-motions,  is  by  means  of  spring-gripes,  which  hold  by  friction  surface,  so  that 
in  case  of  an  imperfect  throw  of  a shuttle,  or  any  other  impediment,  the  connections  will  yield  instead 
of  breaking.  This  is  effected  in  the  rear  or  receiving  shuttle-boxes  by  the  weighted  lever,  which  is  suffi- 
cient to  move  the  boxes,  but  not  to  strain  the  parts  in  case  of  any  impediment. 

When  a shuttle  enters  either  of  the  boxes,  it  is  arreted  in  part  by  its  point  striking  against  the 
picker,  which  soon  becomes  so  indented  as  to  permit  the  point  of  the  shuttle  to  lodge  therein,  and 
therefore  it  will  be  seen  that  in  this  condition  of  the  parts  the  shuttle-boxes  could  not  be  shifted,  or 
rather  would  be  seriously  impeded,  for  the  shuttle  being  in  the  box  which  is  to  rise,  and  its  point  im- 
bedded in  the  picker,  which  does  not  move  up,  the  parts  would  thus  be  held  or  strained.  To  prevent 
this,  at  the  time  the  shuttle  enters  a box  the  picker  is  forced  inwards  by  a lever  r6,  which  is  afterwards 
drawn  back  to  permit  the  picker  to  be  drawn  back  clear  of  the  point  of  the  shuttle  by  the  spring  of 
the  picker-staff.  There  are  four  such  levers  r4,  one  for  each  series  of  shuttle-boxes  ; they  turn  on  ful- 
crum-pins on  the  pendulous  frames,  and  at  their  lower  ends  carry  wrist-pins  that  work  in  cam-grooves 
on  wheels  s that  turn  on  stud-pins  on  the  lower  ends  of  the  pendulous  frames,  and  from  each  of  these 
wheels  extends  an  arm  f with  a slot  near  the  end,  playing  on  a pin  v?  attached  to  the  floor,  so  that  as 
the  pendulous  frame  vibrates,  the  required  vibratory  motion  shall  be  given  to  the  cam-groove  wheels 
One  such  cam-groove  wheel  answers  for  two  levers,  as  shown  in  the  plates. 

The  warps  pass  from  the  warp-beam  below  the  floor,  and  pass  over  a roller  e1  above  the  warp-beam, 
and  thence  through  the  mails  of  the  trap-cards  in  the  usual  manner  of  mounting  a jacquard  loom.  The 
woven  cloth  from  the  breast-beam  passes  between  two  rollers  f f,  one  of  which  is  weighted  to 
make  pressure  against  the  other,  that  the  cloth  may  be  gripped  between  the  two  with  sufficient  force  to 
prevent  it  from  slipping.  And  thence  the  cloth  is  wourfa'  upon  the  cloth-beam,  (not  represented,)  which 
is  driven  by  a friction-strap  with  sufficient  velocity  to  take  up  the  slack,  the  band  slipping  on  the  pul- 
ley when  the  diameter  of  the  beam  becomes  so  large  as  to  tend  to  wind  on  the  cloth  faster  than  it  is 
carried  forward  by  the  two  rollers  ff,  which  constitute  what  is  called  a positive  take-up  motion,  and 
which  receive  the  same  motion  for  each  beat  of  the  lathe,  that  the  same  length  - of  cloth  may  be  taken 
up  for  each  operation  of  the  loom,  and  thus  measure  the  figure  to  be  produced  on  the  cloth.  As  the 
mechanism  for  giving  this  regular  and  positive  take-up  motion  to  the  rollers  was  not  invented  by  Mr. 
Bigelow,  but  was  previously  well  known  to  weavers,  it  is  deemed  unnecessary  to  give  a description  of 
it  here. 

The  mode  of  operating  the  yarn-beam  is  not  represented,  but  it  will  be  understood  with  sufficient 
clearness  from  the  description  alone. 

On  the  shaft  of  the  yarn-beam  there  is  a cog-wheel  operated  by  a worm  on  a vertical  shaft,  which 
carries  a crown  ratchet-wheel,  the  teeth  of  which  are  engaged  by  a pall,  or  ratchet-hand,  on  the  end  of 
a rod  jointed  to -the  sword  of  the  lathe,  so  that  as  the  lathe  beats  back,  by  the  connections  described, 
the  ratchet-wheel  is  turned  a given  portion  of  a revolution,  which  shall  be  sufficient  to  give  out  the  re- 
quired quantity  of  warp-threads  for  any  one  operation  of  the  loom.  But  as  the  diameter  of  the  beam 
is  constantly  varying,  beginning  with  a large  diameter,  and  gradually  diminishing  as  the  warps  are 
given  out,  and  the  demand  for  warps  is  constantly  varying,  by  reason  of  the  irregularities  of  the  weft- 
threads  and  the  ingraining  of  the  fabric,  the  regular  and  positive  motion  of  the  warp-beam  given  by 
the  mechanism  requires  to  be  varied  to  suit  the  varying  conditions  above  described.  This,  as  before 
intimated,  is  governed  by  the  tension  of  the  warps  between  the  beam  and  the  woven  cloth.  The  roller 
?’  over  which  the  warps  pass  from  the  warp-beam  is  hung  in  the  upper  ends  of  two  levers  f f'  which 
have  their  fulcra  at  W\  and  the  lower  arms  of  these  levers  are  formed  in  sector-racks  i',  the  cogs  oi 


LOOM,  CARPET-WEAVING. 


307 


which  engage  pinions  f on  the  ends  of  a shaft,  and  this  shaft  is  provided  with  an  arm  which  carries  a 
weight  P,  which,  by  the  connections  of  the  pinions  and  sector-racks,  tends  always  to  force  back  the 
roller  e1  to  keep  the  warps  under  the  same,  or  nearly  the  same  tension.  This  weight  is  adjustable  on  the 
arm  by  a set-screw,  to  regulate  the  degree  of  tension,  to  suit  the  quality  of  the  warps  and  the  fabric  to 
be  produced.  From  this  it  will  be  seen  not  only  that  the  warps  will  be  always  kept  under  the  same 
degree  of  tension  during  the  operation  of  weaving,  a condition  very  essential  to  the  production  of  a 
fabric  of  regular  texture,  but  if  the  quantity  of  warps  given  out  by  the  warp-beam  be  greater  than  the 
quantity  taken  up  in  weaving,  the  roller  will  be  carried  back  by  the  weight,  and  that  when  the  quantity 
is  less  than  enough,  the  roller  will  be  drawn  forward.  This  motion  of  the  roller  is  made  use  of  to  reg- 
ulate the  motion  of  the  warp-beam  in  the  following  manner : On  the  shaft  before  described  there  is 
another  arm,  to  which  is  jointed  one  end  of  a connecting-rod,  the  other  end  of  which  is  in  turn  jointed 
to  an  arm  which  turns  on  the  arbor  just  above  the  ratchet-wheel,  and  this  arrli  carries  a plate  that  rests 
on  the  face  of  the  ratchet-wheel,  so  that  when  the  roller  is  carried  back  by  the  action  of  the  weight 
when  the  supply  of  warps  is  too  great,  the  shaft  is  turned  in  one  direction,  which,  by  the  connection  de- 
scribed, carries  the  plate  so  far  over  the  surface  of  the  ratchet-wheel  as  to  cover  all,  or  only  a portion 
of  the  teetli  which  would  otherwise  have  been  engaged  by  the  band,  and  hence  the  let-off  motion  of 
the  warp-beam  is  either  entirely  or  partly  prevented  ; and  when,  on  the  other  hand,  the  roller  is  drawn 
forward  by  the  amount  of  warps  given  being  insufficient,  the  plate  is  drawn  back,  which  permits  the 
band  to  engage  the  teeth  of  the  ratchet,  and  to  operate  the  warp-beam,  to  give  out  the  required  quan- 
tity of  warps.  In  this  way  the  supply  of  warps  is  proportioned  to  the  demand,  and  the  cloth  being 
taken  up  by  a positive  and  measured  quantity  at  each  operation,  it  follows  that  the  irregularities  will 
be  thrown  into  the  thickness  instead  of  the  length  of  the  cloth,  and  hence  the  figures  will  be  produced 
of  a regular  and  measured  length,  whatever  may  be  the  irregularities  of  the  weft-threads  and  the  in- 
graining. 

But  there  is  still  another  condition  which  is  important  to  be  observed.  The  roller  e7  must  be  suffi- 
ciently sensitive  to  yield  to  the  tension  of  the  warps  undgr  the  force  of  the  weight  suspended  to  the 
arm  of  the  shaft  connected  with  the  levers  that  carry  the  roller ; and  hence,  when  the  lathe  beats  up  the 
weft-threads,  it  would  yield  to  the  force  of  the  beat,  particularly  in  weaving  fabrics  of  a close  texture, 
which  motion  would  have  the  effect  to  prevent  the  full  action  of  the  reed,  and  cause  the  cloth  of  loose 
texture  to  lay  up  in  front  of  the  reed,  and  in  a short  time  impede  the  proper  working  of  the  loom.  To 

E revent  this,  the  shaft  carries  a wheel  m1,  and  around  a portion  of  its  circumference  passes  a friction- 
rake,  rp ; that  is,  a metal  strap  jointed  to  the  frame  and  to  a connecting-rod  o’,  attached  to  the  sward 
of  the  lathe,  so  that  when  the  lathe  beats  up,  this  metal  strap  is  drawn  in  contact  with  the  periphery 
of  the  wheel,  and  thus  by  friction  holds  it  firmly  so  that  it  cannot  turn,  by  the  connections  holding  the 
roller  firmly,  that  the  warps  may  be  prevented  from  yielding  to  the  force  of  the  beat  of  the  lathe.  In 
this  way  the  desired  effect  is  produced ; Viz..,  that  of  producing  a close  fabric  of  regular  texture  and 
measured  figure,  with  the  irregularities  thrown  into  the  thickness  instead  of  the  length  of  the  cloth. 

So  soon  as  the  shuttle  has  been  thrown  the  weft-thread  lies  between  the  warps  in  a diagonal  line 
from  the  selvage  on  one  side  to  the  shuttle-box  on  the  other,  and  this  diagonal  line  being  longer  than 
the  breadth  of  the  cloth,  it  is  evident  that  if  the  weft-thread  were  beaten  up  freely,  it  would  become 
loose  and  produce  a bad  selvage.  To  prevent  this,  the  sides  of  the  frame  at  a?  constitute  a bed  on  each 
side,  grooved  to  receive  a series  of  fingers  IP,  jointed  to  the  frame,  and  the  moment  the  shuttle  has 
passed  a cam  cP,  on  the  lathe-shaft,  permits  the  fingers  to  fall  on  to,  and  gripe  the  weft-thread,  so  that 
when  it  is  carried  forward  by  the  reed  it  is  resisted  by  the  pressure  of  the  fingers,  which  gives  the 
required  pull  to  insure  a good  selvage.  The  cam  then  passes  around  to  lift  the  fingers,  that  the  shuttle 
may  pass.  These  fingers  are  made  to  answer  the  purpose  also  of  stopping  the  loom  when  the  weft- 
thread  has  not  been  carried  across ; for  then,  as  the  fingers  descend,  not  being  held  up  by  the  weft- 
thread,  they  enter  the  grooves,  and  the  arm  at  the  back  acts  as  catch-levers  connected  with  the  shipper 
to  stop  the  loom. 

The  manner  of  operating  the  lathe  has  beem  described  with  sufficient  clearness  in  pointing  out  the 
characteristics  of  this  invention,  and  it  is  thereiwe  unnecessary  to  give  a more  detailed  description  of  it. 

The  belt  is  shifted  from  the  loose  to  the  fast  pulley,  and  vice  versa,  by  the  belt  shipper  a4,  and  belt- 
guide  b'\  in  the  usual  way;  but  to  adapt  this  to  the  introduction  of  a reversing  motion,  the  shipper  and 
the  guide  are  differently  arranged.  The  shipper  a4,  and  the  belt-guide  &4,  are  on  opposite  ends  of  a 
shaft  c9,  hung  in  appropriate  boxes,  and  this  shaft  is  hollow,  and  within  it  there  is  an  arbor  cl1,  which 
extends  out  at  each  end.  From  the  rear  end  of  this  inner  arbor  projects  an  arm  e4,  which  carries  a 
wrist-pin/4,  that  fits  and  slides  freely  but  accurately  in  a curved  mortise  y4,  in  one  arm  of  a lever  IP, 
that  turns  on  a fulcrum-pin  i4,  its  other  arm  being  jointed  to  the  connecting-rod  of  the  brake/,  that 
works  against  the  inner  periphery  of  the  fast  pulley  b,  in  the  usual  way  of  arranging  the  brake  for 
arresting  the  operation  of  the  loom  when  the  belt  is  shifted  from  the  fast  to  the  loose  pulley.  When 
the  inner  arbor  d*  is  therefore  connected  with  the  shaft  of  the  shipper,  the  brake  is  operated  to  make 
friction  on  the  fast  pulley  when  the  belt  is  shifted  to  the  loose  pulley,  and  liberated  to  relieve  the  fric- 
tion when  the  belt  is  shifted  to  the  fast  pulley,  the  motion  of  the  shipper  to  shift  the  belt  from  the  one 
to  the  other  of  the  pulleys  being  sufficient  to  move  the  arm  ci,  so  that  its  wrist/4  shall  move  over  a 
distance  equal  to  half  the  length  of  the  curved  mortise  in  the  lever  of  the  brakes,  the  curve  and  the 
length  of  this  mortise  being  such  that  moving  the  wrist-pin  from  either  end  of  the  mortise  to  the  middle 
will  force  the  brake  against  the  pulley  to  make  friction,  and  moving  it  from  the  middle  towards  either 
end  will  remove  the  brake.  As  I employ  the  loose  pulley  for  the  purpose  of  giving  the  reverse  motion, 
it  becomes  necessary  in  the  first  place  to  stop  the  loom,  and  then  to  start  it  in  the  reverse  direction, 
and  therefore  in  shifting  the  belt  from  the  fast  to  the  loose  pulley,  the  brake  at  first  must  be  operated 
to  make  friction  to  arrest  the  parts,  and  then  liberated  whilst  the  mechanism  of  the  reversed  motion  is 
brought  into  action.  This  is  effected  in  the  following  manner : on  the  front  end  of  the  arbor  d',  when 
it  projects  beyond  the  hollow  shipper-shaft,  there  is  an  arm  g*,  which  projects  out  towards  the  middle 


308 


MACHINES. 


of  the  loom,  nearly  in  a horizontal  direction  and  at  a convenient  height  to  be  reached  by  the  attendant's 
foot.  On  this  arm  is  journalled  a treadle  A4,  and  so  connected  with  the  arm  g*,  by  means  of  a helical 
spring  i4,  that  when  no  force  is  applied  to  it,  an  armj4,  which  projects  upward  from  its  inner  end,  is 
held  against  a projection  k 4 of  the  shipper,  so  that  the  arbor  of  the  brake  and  the  shaft  of  the  shipper 
are  kept  in  a locked  condition  by  the  helical  spring  i*  to  be  operated  together ; but  when  pressure  is 
applied  on  the  top  of  the  treadle,  then  the  brake  is  operated  separately  to  remove  the  friction  from  the 
pulley.  When  the  attendant  moves  the  shipper  towards  him,  the  belt  is  shifted  from  the  fast  to  the 
loose  pulley,  the  brake  at  the  same  time  being  drawn  down  to  make  friction  for  arresting  the  momentum 
of  the  moving  parts,  and  then  the  attendant  with  his  foot  forces  down  the  treadle  which  relieves  the 
brake,  thereby  liberating  the  parts  preparatory  to  the  reversing  motion  which  is  brought  into  action  by 
the  same  motion.  From  the  bottom  of  the  treadle  projects  an  arm  l 4,  that  carries  a pin  m 4,  that  plays 
freely  in  a mortise  w4,  in  t"he  end  of  a sliding-rod  o4,  and  the  length  of  this  mortise  is  such  that  the  mo- 
tions given  to  the  arm  Z4  by  the  ordinary  motions  of  the  shipper  will  not  communicate  motion  to  the 
sliding-rod,  but  when  the  treadle  is  borne  down  to  relieve  the  brake  after  the  shifting  of  the  belt  into 
the  loose  pulley,  the  sliding-rod  is  drawn  in  the  direction  of  the  arrow. 

The  sliding-rod  o4  is  jointed  to  the  lower  arm  of  a lever  y>4,  which  turns  on  a fulcrum-pin  q\  its  uppei 
arm  being  forked  and  made  to  embrace  the  collar  r4  of  a wheel  s4,  which  slides  freely  on  the  main  driv- 
ing-shaft a of  the  loom.  When  the  sliding-rod  o4  is  drawn  in  the  direction  of  the  arrow,  it  forces  the 
wheel  s4  against  the  face  of  a friction-plate  u'\  which  is  fast  on  the  main  shaft,  and  this  friction-plate 
has  the  effect  of  locking  it  with  the  main  shaft,  so  that  any  motion  given  to  this  wheel  s4  will  drive  the 
main  shaft.  The  hub  v ' of  the  loose  pulley  carries  a pinion  w*,  which  engages  another  pinion  xi,  on  a 
parallel  shaft  y 4,  the  other  end  of  which  has  a pinion  z4,  which  engages  cogs  on  the  inner  periphery  of 
the  wheel  s4,  so  that  the  motion  of  the  loose  pulley  communicates  a reversed  motion  to  this  wheel,  which 
drives  the  main  shaft  in  the  reversed  direction  whenever  they  are  locked  together  by  the  friction-plate. 

The  moment  the  attendant  removes  his  foot  from  the  treadle,  the  wheel  is  withdrawn  from  the  fric- 
tion-plate by  the  tension  of  a helical  spring  a»,  on  the  slide-rod  o4,  and  the  parts  are  then  in  a condition 
for  starting  the  loom  by  the  shifting  of  the  belt  on  to  the  fast  pulley.* 


MACHINES  are  instruments  employed  to  regulate  motion,  so  as  to  save  either  time  or  force. 

The  maximum  effect  of  machines  is  the  greatest  effect  which  can  be  produced  by  them.  In  all  urn 
chines  that  work  with  a uniform  motion  there  is  a certain  velocity,  and  a certain  load  of  resistance,  that 
yields  the  greatest  effect,  and  which  are  therefore  more  advantageous  than  any  other.  A machine  may 
be  so  heavily  charged  that  the  motion  resulting  from  the  application  of  any  given  power  will  be  but  just 
sufficient  to  overcome  it,  and  if  any  motion  ensue  it  will  be  very  trifling,  and  therefore  the  whole  effect 
very  small.  And  if  the  machine  is  very  lightly  loaded,  it  may  give  great  velocity  to  the  load  ; but 
from  the  smallness  of  its  quantity  the  effect  may  still  be  very  inconsiderable,  consequently  between 
these  two  loads  there  must  be  some  intermediate  one  that  will  render  the  effect  the  greatest  possible. 
This  is  equally  true  in  the  application  of  animal  strength  as  in  machines.! 

1.  The  maximum  effect  of  a machine  is  produced  when  the  weight  or  resistance  to  be  overcome  is 
four-ninths  of  that  which  the  power,  when  fully  exerted,  is  able  to  balance,  or  of  that  resistance  which 
is  necessary  to  reduce  the  machine  to  rest ; and  the  velocity  of  the  part  of  the  machine  to  which  the 
power  is  applied  should  be  one-third  of  the  greatest  velocity  of  the  power. 

2.  The  moving  power  and  the  resistance  being  both  given,  if  the  machine  be  so  constructed  that  the 
velocity  of  the  point  to  which  the  power  is  applied  be  to  the  velocity  of  the  point  to  which  the  resist- 
ance is  applied,  as  four  times  the  resistance  to  nine  times  the  power,  the  machine  will  work  to  the 
greatest  possible  advantage. 

3.  This  is  equally  true  when  applied  to  the  strength  of  animals ; that  is,  a man,  horse,  or  other  animal 

will  do  the  greatest  quantity  of  work,  by  continued  labor,  when  his  strength  is  opposed  to  a resistance 
equal  to  four-ninths  of  his  natural  strength,  and  his  verity  equal  to  one-third  of  his  greatest  velocity 
when  not  impeded.  * 

Now,  according  to  the  best  observations,  the  force  of  a man  at  rest  is,  on  an  average,  about  70  lbs.; 
and  his  greatest  velocity,  when  not  impeded,  is  about  6 feet  per  second,  taken  at  a medium.  Hence 
the  greatest  effect  will  be  produced  when  the  resistance  is  equal  to  about  31  l-9th  pounds,  and  his  uni- 
form motion  2 feet  per  second.  * 

The  strength  of  a horse  at  a dead  pull  is  generally  estimated  at  about  420  pounds,  and  his  greatest 


• The  history  of  the  invention  of  this  machine  is  so  full  of  instruction  to  the  young  mechanic,  and  the  facts  of  the  case 
coming  entirely  within  our  own  knowledge,  we  have  been  induced  to  dwell  upon  them,  although  by  so  doing  we  have  de- 
parted somewhat  from  the  original  plan  of  the  Dictionary,  which  would  confine  all  description  to  the  machines  themselves. 

t These  conditions  are  deduced  from  the  following  empirical  expression,  which  is  adopted  by  Euler  and  other  waiters, 
to  represent  the  law  of  the  moving  power:  Let  1’  = the  power  applied,  (or  weight  which  the  power,  when  fully  exerted,  is 
just  able  to  overcome ;)  B = the  resistance,  or  load,  or  weight  to  be  overcome ; c the  greatest  velocity,  or  that  at  which 
the  power  ceases  to  act;  a = any  other  velocity:  then  the  law  of  the  moving  power  is 


’The  variables  in  this  expression  are  R and  v,  and  the  effect  is  represented  by  the  product  E v ; on  making  which  a max- 
imum, the  rules  of  the  differential  calculus  give  v = i c ; whence  the  formula  becomes  E = |P. 

From  these  expressions  it  follows,  that  when  the  moving  power  and  the  resistance  are  both  given,  if  a machine  be  so 
constructed  that  the  velocity  of  the  part  to  which  the  power  is  applied  is  to  the  velocity  of  the  part  to  which  the  resistance 
is  applied  in  the  ratio  of  9 R to  4 P,  the  effect  of  the  machine  will  be  a maximum,  or  it  will  work  to  the  greatest  possible 
advantage.  The  above  conditions  apply  equally  to  machines  impelled  by  animal  force  and  the  agents  of  nature,  as  running 
water,  steam,  the  force  of  gravity,  &c.  An  animal  exerts  itself  to  the  greatest  advantage,  or  performs  the  greatest  quantity 
of  work  in  the  least  time,  when  it  moves  with  about  one-third  of  the  utmost  speed  with  which  it  is  capable  of  moving. 
4iid  is  loaded  with  four-ninths  of  the  greatest  load  which  it  is  capable  of  putting  in  motion. 


MACHINES. 


309 


rate  of  walking  10  feet  per  second;  therefore  the  greatest  effect  is  produced  when  the  load  = 18G| 
pounds,  and  the  velocity  y,  or  3J  feet  per  second. 

4.  A machine  driven  by  the  impulse  of  a stream  produces  the  greatest  effect  when  the  wheel  move® 
with  one-third  of  the  velocity  of  the  water. 

The  following  may  be  taken  as  a general  arrangement  of  machines : 


Class  I. — Machines  for  overcoming  inertia. 


Machines  for  raising  weights. 

Machines  for  transporting  weights  on  land. 
Machines  for  raising  water. 


Blowing  machines. 

Machinery  for  ascending  and  descending  in  fluida 
Machines  for  navigation,  &c. 


Ploughs. 

Drilling  machines. 
Reaping  machines. 
Threshing  machines. 
Mills. 

Boring  machines. 


Class  II. — Machines  for  overcoming  cohesion. 

Cutting  machines. 

Machines  for  cleaning,  or  removing  impurities. 
Grinding  machines. 

Machines  for  turning. 

Machines  which  act  by  compression. 

Pile  engines,  &c. 


Class  III. — Machines  for  combining  materials. 

Machines  for  weaving  cloths,  carpets,  nets,  stockings.  | Machine  for  combining  materials  in  brewing,  die. 


Class  IY. — Machines  for  measuring  forces. 


Anemometers. 

Torsion  machines. 
Balances  and  steelyards. 
Barometers. 
Thermometers. 
Hygrometers. 


Machines  for  measuring  the  elasticity  and  strength 
of  materials. 

Dynamometers  for  measuring  the  force  of  men, 
animals,  and  other  agents. 

Machines  for  measuring  the  force  of  projectiles. 
Machines  for  measuring  the  force  of  running  water. 


Class  V. — Machines  for  measuring  and  dividing  space. 


Quadrants. 

Circles. 

Theodolites. 

Levels. 

Micrometers. 


Goniometers. 

Dividing  machines. 

Odometers. 

Drawing  and  copying  instruments. 


Class  VI. — Machines  for  measuring  time. 


Machinery. — The  utility  of  machinery,  in  its  application  to  manufactures,  consists  in  the  addition 
sdiich  it  makes  to  human  power,  the  economy  of  human  time,  and  in  the  conversion  of  substances  ap- 
parently worthless  into  valuable  products.  The  forces  derived  from  wind,  from  water,  and  from  steam, 
are  so  many  additions  to  human  power.  The  difference  between  a tool  and  a machine  is  not  capable 
of  very  precise  distinction,  nor  is  it  necessary,  in  a popular  examination  of  them,  to  make  any  distinction. 
A tool  is  usually  a more  simple  machine,  and  generally  used  by  the  hand  ; a machine  is  a complex  tool, 
a collection  of  tools,  and  frequently  put  in  action  by  inanimate  force.  All  machines  are  intended  to 
transmit  power.  Of  the  class  of  mechanical  agents  by  which  motion  is  transmitted — the  lever,  the 
pulley,  the  wedge — it  has  been  demonstrated  that  no  power  is  gained  by  their  use,  however  combined. 
Whatever  force  is  applied  at  one  part  can  only  be  exerted  at  some  other,  diminished  by  friction  and 
other  incidental  causes ; and  whatever  is  gained  in  the  rapidity  of  execution,  is  compensated  by  the 
necessity  of  exerting  additional  force.  These  two  principles  should  be  constantly  borne  in  mind,  and 
teach  us  to  limit  our  attempts  to  things  which  are  possible. 

1.  Accumulating  power. — When  the  work  to  be  done  requires  more  force  for  its  execution  than  can 
be  generated  in  the  time  necessary  for  its  completion,  recourse  must  be  had  to  some  mechanical  method 
of  preserving  and  condensing  a part  of  the  power  exerted  previously  to  the  commencement  of  the  pro- 
cess. This  is  most  frequently  accomplished  by  a fly-wheel,  which  is  a wheel  having  a heavy  rim,  so 
that  the  greater  part  of  the  weight  is  near  the  circumference.  It  requires  great  power,  applied  for  some 
time,  to  set  this  in  rapid  motion ; and  when  moving  with  considerable  velocity,  if  its  force  is  concen- 
trated on  a point,  its  effects  are  exceedingly  powerful. 

2.  Regulating  powers — Uniformity  and  steadiness  in  the  motion  of  the  machinery  are  essential  both  to 
its  success  and  its  duration.  The  governor,  in  the  steam-engine,  is  a contrivance  for  this  purpose.  A 
vane  or  fly,  of  little  weight,  but  large  surface,  is  also  used.  It  revolves  rapidly,  and  soon  acquires  a 
uniform  rate,  which  it  cannot  much  exceed ; because  any  addition  to  its  velocity  produces  a greater  ad- 
dition to  the  resistance  of  the  air.  This  kind  of  fly  is  generally  used  in  small  pieces  of  mechanism,  and, 
unlike  the  heavy  fly,  it  serves  to  destroy  instead  of  to  preserve  force. 

3.  Increase  of  velocity. — Operations  requiring  a trifling  exertion  of  force  may  become  fatiguing  by  the 
rapidity  of  motion  necessary,  or  a degree  of  rapidity  may  be  desirable  beyond  the  power  of  muscular 
action.  Whenever  the  work  itself  is  light,  it  becomes  necessary  to  increase  the  velocity  in  order  to 
economize  time.  Thus,  twisting  the  fibres  of  wool  by  the  fingers  wmuld  be  a most  tedious  operation. 
In  the  common  spinning-wheel,  the  velocity  of  the  foot  is  moderate,  but,  by  a simple  contrivance,  that 
of  the  thread  is  most  rapid. 

4.  Diminution  of  velocity. — This  is  commonly  required  for  the  purpose  of  overcoming  great  resistances 
with  small  power.  Systems  of  pulleys  afford  an  example  of  this. 


310 


MAGNET— MAGNETISM. 


5.  Spreading  the  action  of  a force  exerted  fcr  a fe,v>  minutes  over  a large  time. — This  is  one  of  the  most 
common  and  useful  employments  of  machinery.  The  half-minute  which  we  spend  daily  in  winding  up 
our  watches  is  an  exertion  of  force  which,  by  the  aid  of  a few  wheels,  is  spread  over  24  hours. 

6.  Saving  time  in  natural  operations. — The  process  of  tanning  consists  in  combining  the  tanning  prin- 
ciple with  every  particle  of  the  skin,  which,  by  the  ordinary  process  of  soaking  it  in  a solution  of  the 
tanning  matter,  requires  from  six  months  to  two  years.  By  inclosing  the  solution,  with  the  hide,  in  a 
close  vessel,  and  exhausting  the  air,  the  pores  of  the  hide  being  deprived  of  air,  exert  a capillary  at- 
traction on  the  tan,  which  may  be  aided  by  pressure,  so  that  the  thickest  hides  may  be  tanned  in  six 
weeks.  The  operation  of  bleaching  affords  another  example. 

7.  Exerting  forces  too  large  for  human  power. — When  the  force  of  large  bodies  of  men  or  animals  is 
applied,  it  becomes  difficult  to  concentrate  it  simultaneously  at  a given  point.  The  power  of  steam,  air, 
or  water,  is  employed  to  overcome  resistances  which  would  require  a great  expense  to  surmount  by 
animal  labor.  The  twisting  of  the  largest  cables,  the  rolling,  hammering,  and  cutting  of  large  masses 
of  iron,  the  draining  of  mines,  require  enormous  exertions  of  physical  force,  continued  for  considerable 
periods. 

8.  Executing  operations  too  delicate  for  human  touch. — The  same  power  which  twists  the  stoutest 
cable  and  weaves  the  coarsest  canvas  may  be  employed,  to  more  advantage  than  human  hands,  in 
spinning  the  gossamer  thread  of  the  cotton,  and  entwining  the  meshes  of  the  most  delicate  fabric. 

9.  Registering  operations. — Machinery  affords  a sure  means  of  remedying  the  inattention  of  human 
agents,  by  instruments,  for  instance,  for  counting  the  strokes  of  an  engine,  or  the  number  of  coins  struck 
in  a press. 

10.  Economy  of  materials. — The  precision  with  which  all  operations  are  executed  by  machinery,  and 
the  exact  similarity  of  the  articles  made,  produce  a degree  of  economy  in  the  consumption  of  the  raw 
material  which  is  sometimes  of  great  importance. 

11.  The  identity  of  the  result. — Nothing  is  more  remarkable  than  the  perfect  similarity  of  things  man- 
ufactured by  the  same  tool.  This  result  appears  in  all  the  arts  of  printing : the  impressions  from  the 
same  block,  or  the  same  copper-plate,  have  a similarity  which  no  labor  of  the  hand  could  produce. 

12.  Accuracy  of  the  work. — The  accuracy  with  which  machinery  executes  its  work  is,  perhaps,  one  ol 
its  most  important  advantages.  It  would  hardly  be  possible  for  a very  skilful  workman,  with  files  and 
polishing  substances,  to  form  a perfect  cylinder  out  of  a piece  of  steel.  This  process,  by  the  aid  of  the 
lathe  and  the  sliding-rest,  is  the  every-day  employment  of  hundreds  of  workmen. 

Machines  are  classed  under  different  denominations,  according  to  the  agents  by  which  they  are  put  in 
motion,  the  purposes  they  are  intended  to  effect,  or  the  art  in  which  they  are  employed. 

The  reader  is  referred  to  the  various  machines,  under  their  respective  heads. 

MAGNET — MAGNETISM.  The  magnesian  stone,  or  native  magnet,  abounds  in  various  parts  of 
tne  earth,  especially  in  iron  mines,  where  it  is  found  massive,  frequently  crystallized,  and  occasionally 
m beds  of  considerable  thickness.  Its  constituents  are,  for  the  most  part,  oxygen  and  iron  under  the 
form  of  two  oxides,  the  black  and  red.  In  100  parts,  we  have  about  73  parts  iron  and  27  oxygen : it 
has  been  termed  magnetic  iron  ore.  Its  color  varies  from  a reddish  black  to  a deep  gray.  Native 
magnets  from  Arabia,  China,  and  Bengal  are  commonly  of  a reddish  color,  and  are  powerfully  attractive 
Those  found  in  Germany  and  England  have  the  color  of  unwrouglrt  iron. 

The  specific  gravity  of  magnetic  iron  ore  is  about  4-J-  times  that  of  water,  and  affords,  when  worked, 
excellent  bar-iron. 

This  remarkable  substance  has  not  only  the  power  of  drawing  apparently  towards  itself  small  parti- 
cles of  iron,  but  it  has  also  the  important  property  of  communicating  or  propagating,  as  it  were,  its  own 
attractive  power  through  a series  of  masses,  so  as  to  cause  them  to  hang  one  on  another  in  a sort  of 
linked  chain. 

If  the  magnet  be  suspended  by  a delicate  silk  line  from  some  point  between  the  surfaces  of  attraction, 
so  as  to  admit  of  its  turning  freely  on  that  point,  the  mass  will  rest  only  in  one  position  : this  position 
will  be  such  as  to  place  its  poles  either  in  the  line  of  the  meridian,  or  very  near  it ; one  of  the  surfaces 
of  the  mass  will  have  turned  towards  the  north,  and  the  opposite  surface  towards  the  south,  and,  if 
drawn  aside  from  this  position,  will  continue  to  vibrate  backwards  and  forwards  until  it  again  rests  in 
the  same  position. 

The  attractive  force  of  the  loadstone  or  natural  magnet  cannot  generally  be  considered  as  of  any 
great  amount.  Native  magnets  in  their  rude  state  will  seldom  lift  their  own  weight,  and,  with  some 
rare  exceptions,  their  power  is  limited  to  a few  pounds. 

The  effective  power  of  the  loadstone  may  be  considerably  improved  by  means  of  what  is  termed  an 
armature , which  consists  of  small  pieces  of  very  soft  iron  applied  to  the  opposite  polar  surfaces  of  the 
stone,  and  projecting  a little  below  it  on  each  side.  The  attractive  force  is  thus  transmitted  to  the 
small  projecting  or  artificial  poles  of  iron ; this  is  found  not  only  to  augment  the  power,  but  also  to  en- 
able the  experimentalist  to  bring  both  the  poles  to  bear  upon  any  given  mass  at  the  same  instant. 

The  pieces  intended  for  the  armature  should  be  made  of  very  soft  iron,  and  each  formed  with  a ver- 
tical face  about  gth  to  ^th  of  an  inch  thick,  with  a projecting  solid  foot  below,  as  at  ap  and  l n,  Fig. 
2672 ; the  vertical  face  being  closely  applied  to  the  polar  surfaces,  and  the  mass  allowed  to  rest  on  the 
projecting  feetpw,  forming  the  artificial  poles.  Things  being  thus  arranged,  the  whole  is  bound  firmly 
together  by  a cap  of  silver  or  brass,  or  by  plain  metallic  bands,  as  represented  in  A B and  C D,  Fig.  2673. 
A ling  R is  usually  fixed  in  the  upper  part  of  the  cap  for  the  convenience  of  raising  the  whole  mass, 
and  a transverse  piece  of  soft  iron  K,  termed  a keeper  or  lifter,  furnished  with  a central  hook  G,  is 
placed  across  the  artificial  poles  p n,  so  as  to  unite  them.  This  keeper  is  found  to  preserve  and  increase 
the  attractive  force  of  the  poles,  especially  if  the  magnet  be  suspended  by  its  upper  ling  R,  and  weights 
be  attached  to  the  book  G,  and  by  which  its  power  may  be  roughly  estimated. 

If  the  armed  magnet  be  thus  suspended,  and  a small  scale-pan  attached  to  the  keeper  II,  an  additional 


MAGNET— MAGNETISM. 


311 


weight  may  be  added  daily  for  a considerable  time : the  loadstone  thus  armed  may  be  caused  to  sustain 
from  twenty  to  thirty  times  its  own  weight. 

When  an  armed  loadstone  is  employed  for  particular  experimental  inquiries  or  other  purposes,  the 
keeper  K may  be  removed,  but  it  should  be  replaced  when  the  magnet  is  not  in  use. 

If  we  suspend  a magnet  by  a fine  silk  fibre  over  another  magnet,  or  near  another  magnet  also  sus- 
pended, the  poles  of  these  magnets  will  arrange  themselves  in  such  a way  as  to  bring  the  opposite 
poles  together ; the  similar  poles  are  found  so  powerfully  and  reciprocally  repulsive,  as  not  to  allow 
‘he  masses  to  rest  with  their  similar  poles  in  juxtaposition. 

2C73. 


Pieces  of  common  iron,  which  have  been  for  a great  length  of  time  in  one  fixed  position,  or  under- 
ground, acquire  considerable  polarity — in  fact,  become  magnets.  In  the  “ Memoirs  of  the  Academy  oi 
Sciences”  for  1731,  we  find  an  account  of  a large  bell  at  Marseilles  having  an  axis  of  iron:  this  axis 
rested  on  stone  blocks,  and  threw  off  from  time  to  time  great  quantities  of  rust,  which,  mixing  with  the 
particles  of  stone  and  the  oil  used  to  facilitate  the  motion,  became  conglomerated  into  a hardened  mass : 
this  mass  had  all  the  properties  of  the  native  magnet.  The  bell  is  supposed  to  have  been  in  the  same 
position  for  400  years. 

The  artificial  magnet. — To  make  an  artificial  magnet,  procure  a small  bar  of  steel  about  8 inches  in 
length,  Ith  of  an  inch  wide,  and  Jth  of  an  inch  thick,  or  a piece  of  common  steel  wire  of  about  the  same 
length,  and  from  |th  to  ^th  of  an  inch  in  diameter.  Let  the  steel  be  well  hardened  and  tempered  by 
plunging  it  at  a cherry-red  heat  into  cold  water ; when  cold  and  polished,  apply  each  extremity  in  sue 
cession  to  the  opposite  poles  of  an  armed  magnet,  Fig.  2672,  first  touching  with  gentle  friction  one  ex 
tremity  of  the  bar,  or  one  of  the  poles  and  the  opposite  extremity  on  the  other  pole,  or,  which  is  bettejj 
draw  the  bar  a b,  Fig.  2674,  a few  times,  in  the  direction  of  its  length,  across  the  two  poles  mn  of  the 
magnet  M,  as  represented  in  the  figure,  and  in  such  a way  as  not  to  pass  either  extremity,  a h,  beyond 
or  off  the  opposite  poles  mn;  finally,  bring  the  bar  a b so  as  to  rest  with  its  extremity  a 'b  equally  dis- 
tant from  each  pole  m n ; that  is  to  say,  bring  the  poles  m n at  the  centre  of  the  bar,  or  as  nearly  as 
may  be.  In  this  position  remove  the  bar  from  the  poles.  The  bar  will  now  be  found  attractive  of 
particles  of  iron,  common  steel  needles,  and  other  ferruginous  matter : when  suspended  it  will  arrange 
itself  in  the  direction  of  the  magnetic  meridian,  and  will,  in  fact,  have  all  the  properties  of  the  loadstone, 
including  the  important  property  of  imparting  or  exciting  a magnetic  condition  in  tempered  steel. 

Take  a small  bar  of  steel  which  has  been  rendered  magnetic  by  the  process  just  described,  apply  it 
with  slight  friction  to  a piece  of  hard  steel  wire  or  a similar  bar,  and  in  such  way  that  the  opposite 
extremities  of  each  bar  may  have  contact  attended  by  a slight  degree  of  friction  : this  second  bar  or 
wire  will  be  found  also  to  have  acquired  a similar  magnetic  condition  to  the  first ; and  this  process  may 
be  continued  from  the  second  to  a third  wire  of  steel,  and  so  on  without  limit. 

The  propagation  of  magnetism  from  one  bar  of  steel  to  another,  as  illustrated  in  this  experiment,  en- 
ables the  experimentalist  to  obtain  artificial  magnets  to  any  given  amount ; and  since  the  form  and 
magnitude  of  the  steel  has  not  been  found  to  interfere  with  the  generality  of  the  result,  we  are  further 
enabled  to  obtain  magnets  of  any  required  figure  or  magnitude. 

It  is  to  be  especially  observed  that  the  polarities  excited  in  the  opposite  portions  of  a steel  bar  by 
this  artificial  process  of  magnetizing  are  the  reverse  of  those  of  the  magnetic  poles  to  which  these  por- 
tions have  been  applied.  Thus  in  Fig.  2674,  if  the  extremity  b of  the  steel  a b rest  on  the  north,  or 
positive  pole  n of  the  magnet  M,  the  polarity  induced  in  that  extremity  b will  be  a south  or  negative 
polarity.  Reciprocally,  if  the  extremity  n be  brought  to  rest  on  the  negative  or  south  pole  m,  then  the 
polarity  induced  in  that  point  of  the  steel  will  be  a positive  or  north  polarity. 

Artificial  magnets  may  be  of  any  required  form,  or  of  almost  any  dimensions,  according  to  the  par- 
ticular views  of  the  experimentalist : for  general  purposes  they  are  limited  to  straight  bars,  such  as 
represented  in  Fig.  2675,  or  otherwise  to  bars  bent  into  a curvilinear  form,  resembling  a horse-shoe,  as 
m Fig.  2676  ; the  branches  cp  and  c n bemg  longer,  and  the  extremities  p n nearer  than  in  the  common 
horse-shoe.  Many  such  bars,  either  straight  or  curved,  form,  when  combined,  what  is  termed  a com- 
vound  magnet,  such,  for  example,  as  that  represented  in  Figs.  2677  and  2678.  The  combination  of 
several  compound  magnets  with  projecting  armatures  constitutes  a magnetic  battery  or  machine.  The 
dimensions  well  adapted  to  magnetic  bars,  either  straight  or  curved,  are  such  as  to  give  the  breadth 
about  -A th  or  -Ath  of  the  leng  th,  and  the  thickness  something  less,  or  not  exceeding  one-half  of  the 
breadth.  ° 


•512 


MA  GNEP— MAGNETISM. 


To  magnetize  a bar  of  tempered  steel,  Fig.  2676,  curved  into  the  horse-shoe  form,  fix  the  bar,  Fig 
2679,  on  a flat  board,  with  its  extremities,  p s,  against  a straight  piece  of  soft  iron,  p s,  of  the  same 
thickness  and  width  as  the  bar.  Having  secured  the  whole  in  this  position,  place  a compound  magnet 
M,  or  an  armed  native  magnet,  on  one  of  the  extremities  s,  of  the  curved  bar,  taking  care  that  the  oppo- 
site or  marked  and  unmarked  ends  are  in  contact  with  each  other.  Continue  as  before  to  glide  the 
magnet  M several  times  round  the  whole  series,  and  in  the  same  direction,  s cp,  finally  stopping  in  the 


2675. 


2677. 


2678. 


centre,  c.  Repeat  this  process  on  each  face  of  the  bar,  when  a high  degree  of  power  will  have  become 
developed  ; so  much  so,  that  the  iron  or  keeper  p s cannot  be  directly  pulled  away  without  considerable 
force,  and  in  some  instances  cannot  be  conveniently  removed  except  by  sliding  it  off. 

In  order  to  preserve  effectually  the  magnetism  thus  excited  in  bars  of  steel,  it  is  requisite,  when  not 
in  use,  to  keep  their  opposite  poles  united  by  means  of  pieces  of  soft  iron. 

2080. 


2670. 


Take  a perfectly  straight  and  even  bar  of  steel,  P S,  Fig.  2680,  sufficiently  hard  to  retain.a  magnetic 
state.  It  may  be  7 inches  long,  Jth  of  an  inch  wide,  and  -Ath  of  an  inch  thick.  Drill  a clean  hole 
through  the  centre  of  the  wide  surface,  and  then  pass  an  extremely  fine  drill  also  through  the  centre 
transversely  to  this  hole,  across  the  thickness  of  the  bar,  edgewise,  and  so  accurately  as  to  pass  through 
the  centre  of  gravity  of  the  mass,  or  as  nearly  as  possible  ; proceed  now  to  complete  the  equilibrium  of 
the  bar  upon  a fine  needle  as  an  axis,  and  in  such  a way  as  to  render  it  indifferent  as  to  position  in  a 
vertical  plane  or  nearly  so,  and  that  whether  it  be  placed  with  one  or  the  other  face  uppermost.  Let 
the  bar  be  now  magnetized,  and  then  mounted  on  its  central  axis ; run  the  axis  through  a small  silver 
stirrup  c r,  and  suspend  the  whole  by  a fine  silk  fibre  r t,  attached  to  a fixed  point  t ; the  bar  P S will 
be  observed  gradually  to  assume  a definite  and  oblique  position,  p n,  inclining  in  these  latitudes  its 
north  pole,  P,  nearly  70  degrees  below  the  horizontal  line,  turning  at  the  same  time  into  a plane  devia- 
ting from  the  plane  of  the  meridian  by  a given  angular  quantity,  called  “ the  dip,”  the  lower  extremity 
having  turned  towards  the  north,  and  the  other  extremity  towards  the  south ; and  it  may  be  likewise 
observed,  on  the  principle  already  stated,  that  the  extremities  which  have  thus  turned,  the  one  towards 
the  north  and  the  other  towards  the  south,  will  have  been  derived  from  the  opposite  poles  of  the  load- 
stone or  magnet  by  which  it  has  been  magnetized. 

The  position  of  the  magnetic  centre  and  poles  of  each  surface,  together  with  the  general  magnetic 
condition  of  the  bar,  and  the  reciprocal  attractions,  repulsions,  and  neutralization  of  the  opposite  forces, 
may  be  shown  in  the  following  way. 

Strain  a piece  of  common  drawing-paper  on  an  open  frame,  AC,  Fig.  2681,  and  place  it  over  a hard 
steel  bar  S N,  regularly  and  powerfully  magnetic ; project  on  the  paper  over  the  bar,  through  a small 
muslin  or  lawn  sieve,  some  fine  iron  dust  or  filings ; the  particles  will  arrange  themselves  in  a series  of 


MAGNET— MAGNETISM. 


312 


curved  lines  of  magnetic  force  proceeding  from  homologous  or  similar  points  on  each  side  of  the  middle 
of  the  bar,  some  uniting  about  the  magnetic  centre,  others  standing  out  at  the  extremities  as  if  repelled 
from  the  poles  FT  S,  and  tending  to  turn  at  considerable  distances  into  other  curved  lines  of  force,  to 
unite  their  branches  between  the  opposite  poles.  This  experiment  may  be  rendered  more  decisive  by 
slightly  tapping  the  finger  on  the  paper,  so  as  to  give  the  particles  a little  vibration. 

Oppose  the  dissimilar  poles  S N,  Fig.  2681|,  of  two  powerful  bars  to  each  other  at  about  two  inches 


2681.  2681*. 


distance,  and  project  over  them  fine  iron  filings  as  before ; similar  results  ensue.  Magnetic  lines  of 
force,  both  straight  and  curved,  and  proceeding  from  similar  points  of  each  bar,  will  be  apparent,  uniting 
the  two  poles  by  chains  of  reciprocal  attraction. 

Change  the  position  of  one  of  the  bars,  so  as  to  oppose  two  similar  poles  N iST,  Fig.  2682 ; the  lines  of 
force  will  then  appear  to  be  conflicting  lines ; the  repulsive  forces  will  cause  a straight  line  a 5 to  appear 
on  the  open  space  or  field  between  the  poles,  from  which  the  iron  dust  stands  out  transversely.  At 
this  line,  the  opposed  forces  on  either  side  are  apparently  struggling  with  each  other,  being  exerted  in 
repulsive  directions  from  the  opposed  poles. 


•2682.  2683. 


We  have  in  these  phenomena  satisfactory  visual  evidence  of  the  existence  of  two  distinct  forces — of 
their  reciprocal  attractions  and  repulsions,  and  their  mutual  neutralization. 

A light  magnetic  bar  N S,  Fig.  2683,  or  a small  magnetic  steel  cylinder,  of  great  comparative  length, 
has  been  termed  a magnetic  needle.  When  delicately  poised  on  a central  point  c,  so  as  to  retain  a hori- 
zontal position,  and  move  freely  in  a horizontal  plane,  it  has  been  termed  the  horizontal  needle.  When 
poised  on  a fine  central  axis,  so  as  to  move  freely  in  a vertical  plane,  it  has  been  termed  a vertical  or 
dipping  needle.  If  suspended  as  in  Fig.  2683,  so  as  to  have  motion  in  both  a horizontal  and  vertical 
plane,  it  has  been  termed  the  horizontal  and  vertical  needle. 

Instruments  for  ascertaining  whether  a substance  has  polarity  or  not,  and  for  detecting  the  presence 
and  kind  of  force  in  operation,  have  been  termed  magnetoscopes.  The  most  simple  kind  of  magneto- 
scope is  a small  horizontal  needle,  about  an  inch  in  length,  delicately  suspended  by  a fine  silk  fibre,  or 
otherwise  set  upon  a fine  point  and  agate  centre,  within  a small  wood  or  glass 
case,  as  represented  in  Fig.  2681,  and  so  set  as  to  admit  of  some  degree  of  dip  or  2681. 

depression  of  either  pole,  as  well  as  a perfect  motion  in  a horizontal  plane.  From 
the  attractive  and  repulsive  forces  of  similar  and  dissimilar  poles  it  is  evident, 
from  the  kind  of  effect  produced  on  the  poles  of  the  magnetoscope,  we  may  al- 
ways determine  the  presence  or  kind  of  polarity  acting  on  it.  Thus,  if  such  an  instrument  as  that  just 
described,  be  glided  along  the  surface  of  any  given  substance  without  any  attractive  or  repulsive 
effect  being  apparent,  such  a substance  may  be  considered  as  non-magnetic.  If,  on  the  contrary,  we 
find  both  poles  of  the  instrument  everywhere  attracted  indifferently,  then  we  may  infer  that  the  sub- 
stance is  a magnetic  substance : such  would  be  the  case  with  a piece  of  common  soft  iron.  Should  we 
find  certain  points  attractive  of  one  of  the  poles  of  the  small  needle,  and  repulsive  of  the  other,  then 
we  may  infer  that  not  only  is  the  substance  a magnetic  substance,  but  that  it  has  also  polarity,  or  is  a 
magnet. 

Magnetic  influence  or  induction. — When  a piece  of  soft  iron  is  brought  into  contact  with  a magnetic 
pole,  it  immediately  acquires  an  attractive  power,  as  if  the  magnetism  of  the  pole  had  spread  out  and 
pervaded  the  iron.  In  fact,  if  we  examine  a piece  of  iron  thus  circumstanced  by  means  of  the  magneto- 
scope,  we  find  the  same  polarity  continued  throughout  the  iron ; it  will  everywhere  attract  one  pole  of 
the  magnetoscope,  and  repulse  the  opposite  pole.  If,  however,  we  separate  the  iron  from  the  magnet, 
and  retain  it  at  a short  distance  from  the  magnetic  pole,  then  a new  case  appears  to  arise  : that  portion 
of  the  iron  next  the  magnet  will  have  an  opposite  polarity  to  that  of  the  pole  to  which  it  is  opposed  ; 
the  two  magnetic  elements  resident  in  the  iron  will,  in  fact,  become  separated ; one  of  them  will  be 
sensible  at  the  extremity  next  the  magnet,  and  the  other  at  its  distant  extremity : a result  which  we 


814 


MAGNET— MAGNETISM. 


might  expect  to  follow  from  the  repulsion  of  the  similar  elements  and  the  attraction  of  the  opposite 
elements.  This  separation  of  the  latent  magnetism  of  the  iron  into  its  constituent  elements  has  been 
termed  magnetic  induction.  It  is  altogether  a temporary  state  or  condition  of  the  iron  sustained  by  the 
influence  of  a magnetic  pole,  and  vanishes  so  soon  as  that  influence  is  withdrawn. 

In  the  communication  of  magnetism  by  the  loadstone  to  hardened  steel,  and  from  one  piece  of  steel 
to  another  without  limit,  neither  the  loadstone  nor  the  artificial  magnet  loses  any  of  its  inherent  power  , 
nothing,  therefore,  appears  to  be  communicated ; the  whole  result  is  entirely  a species  of  molecular 
excitation,  or  a calling  into  sensible  activity  certain  forces  already  existiug  in  the  magnetic  substance, 
and  which,  under  ordinary  circumstances,  remain  in  a quiescent  or  neutral  state.  No  means  yet  de- 
vised have  ever  insulated  these  forces  in  such  way  as  to  enable  us  to  obtain  one  of  them  only,  independ- 
ently of  the  other.  We  cannot,  for  example,  produce  a magnetic  bar  having  a single  pole  ; for  although 
we  touch  one  extremity  of  the  bar  only  with  one  pole  of  the  loadstone,  still  two  poles  will  appear  in 
the  bar,  although  the  one  induced  by  the  presence  of  the  other  may  not  be  so  forcible. 

Methods  of  communicating  magnetism  to  steel  bars. — The  first  means  of  imparting  magnetism  to 
steel  was,  as  we  have  already  described,  by  contact  with  the  armed  loadstone  or  other  magnet.  A 
more  efficacious  method,  however,  of  magnetizing  small  needles  or  bars  by  simple  contact,  consists  in 
placing  the  bar  or  needle  between  the  opposite  poles  of  powerful  magnets,  as,  for  example,  in  the  mag- 
netic field  S N,  Fig.  2681,  immediately  between  the  poles  S N. 

We  are  indebted  to  Dr.  Gowan  Knight,  F.R.S.,  a London  physician,  for  the  first  important  step  in  the 
communication  of  magnetism  to  bars  of  steel.  His  method,  as  given  in  the  Philosophical  Transactions 
for  the  years  1746  and  1747,  vol  xliv.,  is  as  follows  : two  powerful  magnetic  bars  M M',  Fig.  2685,  are 
placed  in  the  same  straight  line,  with  their  opposite  poles  N S very  near  each  other ; the  needle  or  bar 
ns  to  be  magnetized  is  laid  flat  on  the  surface  of  the  bars,  immediately  over  the  opening  N S,  between 
them.  If  the  bar  ns  be  a magnetic  needle,  having  a cap  for  suspension,  then  the  cap  is  allowed  to 
rest  between  the  bars:  if  the  surface  be  unimpeded  by  this,  the  bars  M M'  may  be  brought  very  near 
each  other.  Things  being  thus  disposed,  the  bars  M M'  are  gradually  withdrawn  in  opposite  directions, 
and  immediately  under  the  barsm;  the  result  of  which  operation  is,  on  the  principles  already  ex- 
plained, that  each  half  of  the  bar  s n being  acted  on  by  opposite  polarities,  the  two  magnetic  forces  resi- 
dent in  it  become  separated ; the  pole  N of  the  bar  M attracts  all  the  south  polarity  and  repels  the 
north,  whilst  the  pole  S of  the  bar  M'  attracts  all  the  north  polarity  and  repels  the  south : hence  a 
final  and  permanent  magnetic  state  is  imparted  to  the  bar  s n,  the  position  of  the  poles  s n being  the 
reverse  of  the  poles  N S of  the  bars. 

26F6. 


Small  needles  will  become  magnetized  to  saturation  by  one  opei^ition  of  this  kind  performed  on  each 
of  its  surfaces  ; for  larger  bars,  two  or  three,  or  more,  repetitions  are  desirable.  This  method  is  very 
effectual,  especially  for  single  bars,  and  there  is  not,  perhaps,  any  better  for  certain  purposes,  even  at 
the  present  day. 

After  this  method  of  Dr.  Knight’s  had  become  known  and  practised,  M.  Du  Hamel,  member  of  the 
Royal  Academy  of  Sciences  at  Paris,  was  led,  about  the  year  1749,  to  a further  and  still  more  exten- 
sive application  of  it.  Two  bars  N S and  T P,  Fig.  2686,  required  to  be  magnetized,  are  laid  on  a ta- 
ble jrarallel  to  each  other,  and  their  intended  opposite  poles  united  by  pieces  of  soft  iron  N T,  S P,  so 
as  to  form  a closed  rectangular  parallelogram,  as  seen  in  the  figure.  The  opposite  poles  n s of  two 
powerful  magnets  A B,  either  simple  or  compound,  are  then  applied  to  the  centre  C of  one  of  the  bars 
N S,  and  drawn  away  from  each  other  in  opposite  directions  C N,  C S,  being  held  all  the  while  at  an 
inclination  of  about  40°  : this  operation  is  repeated  several  times  ; the  magnets  A B are  now  either 
reversed,  or  their  relative  positions  changed,  by  turning  them  round  ; they  are  then  applied  in  a similar 
way  to  the  other  bar  P T,  so  as  to  bring  the  poles  s n opposite  to  their  former  position : the  same  oper- 
ation is  now  repeated  on  the  bar  T P,  and  this  process  is  to  be  further  repeated  on  each  surface  of  the 
bars  T P,  N S.  M.  Du  Hamel’s  method  is  effective  and  expeditious  ; the  elementary  forces  resident  in 
the  bars  being  by  tire  joint  operation  of  the  magnets  easily  separated,  whilst  the  union  of  the  opposite 
poles  N T and  S P by  soft  iron,  further  tends  to  increase  the  effect,  by  holding  together,  as  it  were,  the 
two  separated  magnetic  elements,  and  thus  allowing  the  exciting  magnets  A B to  operate  with  more 
considerable  effect. 

Bars  of  the  horse-shoe  form  may  be  rendered  magnetic  in  a similar  way,  by  uniting  their  near  ex- 
tremities or  intended  poles  with  soft  iron,  and  then  drawing  the  magnets  away  from  each  other,  com- 
mencing at  the  centre  of  the  curve,  and  terminating  at  each  extremity. 

A high  magnetic  development  may  be  obtained  in  a series  of  straight  bars,  without  the  aid  of  pow- 
erful magnets,  by  a successive  touching  in  combination  one  with  the  other.  We  are  indebted  to  Mr. 
Canton  for  this  process,  which  is  as  follows : 

Having  a set  of  12  bars,  however  slightly  magnetic,  two  of  the  series  S'  ISP,  N S.  Fig.  2687,  are  laid 


MAGNET— MAGNETISM. 


31£ 


with  reverse  poles  parallel  to  each  other,  and  the  rectangle  closed  by  pieces  of  soft  iron  S N',  N S', 
about  one-half  the  length  of  the  bars,  and  of  the  same  breadth,  as  in  the  method  of  Du  Hamel ; the 
remaining  10  bars  are  separated  into  two  combined  systems  A B,  of  5 bars  each,  placed  on  one  of  the 
bars  N'  S',  with  their  remote  and  opposite  poles  C in  contact,  and  their  lower  poles  n s somewhat  open. 
This  arrangement  being  made,  the  bars  S'  N'  and  N S are  rubbed  with  these  systems  in  the  way 
already  described,  and  being  thus  strengthened  by  the  united  powers  of  all  the  rest,  are  now  removed, 

2687. 


c 


and  placed  at  the  back  of  the  others,  as  at  A B,  whilst  the  two  interior  bars  of  each  system  C s,  C n, 
are  withdrawn,  and  subjected  to  the  same  operation  as  the  preceding ; in  this  way  we  continue  to 
“trengthen  each  pair  of  bars  by  the  acquired  power  of  those  last  touched,  until  the  whole  become  mag- 
netized to  saturation.  This  process  is  very  useful  when  powerful  magnets  are  not  at  hand  ; for  how- 
ever weak  may  be  the  magnetic  state  of  the  bars,  even  although  two  of  them  only  be  slightly  mag- 
netic, we  may  from  these  render  the  whole  series  very  powerful. 

The  combined  systems  A B may  be  temporarily  bound  together  by  a little  common  tape,  and  a small 
block  of  wood  placed  between  them,  so  as  to  support  the  whole  in  position  during  the  process  of  mag- 
netizing. 

Besides  these  direct  methods,  we  have  other  processes  for  obtaining  a magnetic  development  in  steel 
and  iron,  of  much  practical  importance.  Marcel,  so  long  since  as  the  year  1722,  observed  that  a bar  of 
iron  acquired  a temporary  magnetic  state  by  position  alone ; and  he  succeeded  in  imparting  magnet- 
ism to  a piece  of  hard  steel  placed  on  an  anvil,  merely  by  rubbing  it  with  the  lower  end  of  a bar  of 
iron  about  33  inches  long,  set  upright  upon  the  steel.  The  temporary  magnetic  state  thus  induced  by 
position  in  the  iron  bar  is  such,  that  the  lower  extremity,  in  these  latitudes,  becomes  a south  pole,  and 
the  upper  extremity  a north  pole ; and  the  forces  are  much  increased  by  placing  the  bar  in  the  direc- 
tion of  the  inclined  needle : in  southern  latitudes  the  reverse  of  this  occurs — the  lower  extremity  is 
then  a north  pole,  and  the  upper  end  a south  pole.  Mr.  Canton,  by  an  ingenious  manipulation  of  this 
kind,  succeeded  in  communicating  a weak  degree  of  magnetism  to  steel  by  means  of  a common  poker 
and  a pair  of  tongs,  and  from  this  magnetized  his  series  of  bars  to  saturation  by  the  process  we  have 
described : the  bar  to  be  rendered  weakly  magnetic  was  attached  to  the  upper  end  of  the  poker  by 
means  of  thread,  and  the  whole  placed  in  the  direction  of  the  dipping  needle ; whilst  in  this  position 
the  bar  was  repeatedly  touched  with  the  closed  extremities  of  the  tongs,  carried  from  one  end  of  the 
bar  to  the  other,  from  below  upward,  the  marked  end  of  the  bar  being  below. 

Another  method  of  developing  magnetism  in  steel  bars,  without  the  aid  of  common  magnets,  consists 
in  subjecting  the  bar  to  sharp  concussion.  This  principle  was  well  known  to  Gilbert  so  long  since  as 
the  year  1570,  who,  in  his  celebrated  work  “De  Magnete,”  represents  a blacksmith  hammering  a steel 
bar  in  the  position  of  the  inclined  needle.  Smiths’  tools,  such  as  drills,  broaches,  &c.,  which  have  under- 
gone pressure  and  motion,  are  generally  magnetic.  When  a steel  jDunch  is  driven  hard  into  iron,  the 
punch  is  not  unfrequently  rendered  magnetic  by  a single  blow. 

In  the  Philosophical  Transactions  for  1738  we  find  an  account,  by  Desaguliers,  of  iron  bars  ren- 
dered magnetic  by  striking  them  sharply  against  the  ground  whilst  in  a vertical  position,  or  otherwise 
striking  them  with  a hammer  when  placed  in  a horizontal  position  at  right  angles  to  the  magnetic 
meridian.  Such  bars  attract  and  repulse  the  poles  of  the  needle.  According  to  Du  Faye,  whose  ex- 
periments are  quoted,  it  is  no  consequence  how  the  bar  is  struck  : all  that  is  required  is  to  impart  to 
the  bar  a vibratory  state  whilst  in  a vertical  position. 

Availing  himself  of  these  facts,  Scoresby,  after  a further  and  critical  examination  of  the  subject, 
succeeded  in  obtaining  magnetic  bars  of  extraordinary  power  by  percussion.  In  the  course  of  these 
inquiries,  a considerable  advantage  was  found  to  arise  by  striking  the  bar  whilst  resting  in  a vertical 
position  upon  a rod  of  iron.  A cylindrical  bar  of  soft  steel,  6 J inches  long,  and  I of  an  inch  diameter, 
resting  on  stone,  and  struck  with  a hammer  weighing  12  ounces,  could  only  be  made  to  lift  about 
grains  ; whereas  when  resting  on  a bar  of  iron,  and  struck  in  a similar  way,  it  lifted  88  grains.  Scores- 
by, in  developing  magnetism  in  this  way  by  percussion,  first  struck  a large  iron  bar  in  a vertical  posi- 
tion, and  then  laid  it  on  the  ground  with  its  acquired  south  pole  towards  the  north ; he  then  proceeded 
to  strike  sharply  with  a hammer  a soft  steel  bar,  30  inches  long  and  an  inch  square,  resting  vertically 
on  the  south  pole  of  the  iron  bar.  A second  similar  bar  was  treated  in  the  same  way ; then,  placing 
one  of  these  steel  bars  vertically,  he  proceeded  to  strike  upon  them,  as  supports,  a series  of  flat  bars 
of  soft  steel,  8 inches  long,  and  \ an  inch  broad,  and  in  a few  minutes  they  had  acquired  a considerable 
lifting  power.  The  series  of  bars  being  now  touched  one  with  the  other,  after  the  manner  of  Canton 
became  very  soon  magnetized  to  saturation;  each  pah  readily  lifted  8 ounces. 


316 


M A GNET — MAGNETISM. 


Dr.  Scoresby  observes  that  large  iron  and  steel  bars  are  not  absolutely  requisite  to  the  success  of  tliii 
process,  common  pokers  answering  the  purpose  very  well. 

The  next  series  of  phenomena  claiming  attention,  arise  out  of  a property  peculiar  to  natural  and 
artificial  magnets,  by  which  they  tend,  when  freely  suspended,  to  arrange  themselves  in  a certain  rela- 
tive position  to  a wire  carrying  a current  of  Voltaic  electricity.  These  phenomena  have  been  hence 
termed  electro-magnetic , and  although  of  sufficient  moment  and  extent  to  come  under  a separate  and 
peculiar  branch  of  physical  science,  yet  so  far  demand  a brief  notice  here,  as  constituting  a very  im- 
portant property  of  the  natural  and  artificial  magnet. 

With  a view  to  a clear  conception  of  these  reciprocal  magnetic  and  Voltaic  actions,  it  is  requisite  to 
understand  that  two  plates  of  zinc  and  copper,  z c,  Fig.  2688,  placed  near  each  other  in  a vessel  of  di- 


2690. 


2609. 


lute  acid,  and  connected  by  a metallic  circuit  c'  S FT  z',  turned  or  directed  in  any  manner,  give  rise,  during 
the  solution  of  the  zinc  in  the  acid,  to  a peculiar  electro-chemical  action,  by  which  a current  of  electricity 
is  supposed  to  flow  from  the  zinc  plate  z in  the  direction  of  the  small  arrow,  through  the  acid  upon  the 
copper  plate  c , and  from  thence  through  the  metallic  circuit  cc'SNz'z  back  again  upon  the  zinc  plate  z. 
A combination  of  this  kind  has  been  termed  a Voltaic  circle,  and  the  metallic  circuit  c'  S IT  z'  the 
uniting  wire. 

This  understood,  let  S IT  be  a perfectly  straight  portion  of  this  circuit,  which,  as  a standard  of  refer- 
ence as  to  position,  we  will  suppose  to  be  in  the  direction  of  the  magnetic  meridian.  Let  p t be  a mag- 
netic needle,  suspended  below  and  parallel  to  FT  S ; then,  directly  we  complete  the  communications  IT 
z'  z — S c'  c with  the  zinc  and  copper  plates  zc,  the  needle  p t varies  from  the  meridian,  and  tends  to 
place  itself  across  the  wire  IT  S,  and  in  such  way  that  whichever  pole  of  the  needle  is  next  the  copper 
plate  c,  that  pole  moves  to  the  right  hand,  or  towards  the  east.  If,  therefore,  the  current  flow  over  the 
needle  from  c to  z , through  the  wire  S IT,  from  south  to  north,  and  the  observer  be  looking  over  the 
wire  in  the  same  direction,  then  the  south  pole  t,  next  the  copper  plate  c,  turns  to  his  right  hand,  or  to  the 
east,  and  the  north  pole  p to  his  left  hand,  or  west.  If  we  suppose  the  position  of  the  plates  c and  z 
to  be  changed,  and  the  direction  of  the  current  reversed,  by  connecting  the  extremity  IT  with  c,  and  the 
extremity  S with  z,  so  as  to  cause  the  current  to  flow  from  north  to  south,  then  these  deflections  are 
also  reversed.  The  south  pole  t now  goes  to  the  left  hand,  and  the  north  pole  p to  the  right  hand — 
that  is  to  say,  the  north  pole  p being  now  next  the  copper  plate,  goes  to  the  right  hand. 

Place  the  ueedle  above,  and  parallel  to  the  wire  S IT,  then  the  reverse  of  all  the  former  deflections 
will  be  obtained  ; whichever  pole  of  the  needle  is  now  next  the  copper  plate,  that  pole  moves  to  the 
left  hand,  or  west  When  the  current,  therefore,  flows  from  south  to  north,  the  south  pole  t,  which  be- 
fore went  to  the  right  hand,  or  east,  now  goes  to  the  left  hand,  or  west,  whilst  the  north  pole  turns  to 
the  right  hand  ; if  we  reverse  the  current,  and  cause  it  to  flow  from  north  to  south,  as  in  the  last  experi 
ment,  then  these  deflections  are  again  reversed ; the  north  pole  of  the  needle,  being  now  next  the  cop 
per  plate  of  the  battery,  goes  to  the  left  hand. 

If  the  needle  be  immediately  in  the  plane  of  the  uniting  wire,  on  either  side  of  it,  no  motion  is  ob- 
tained in  that  plane  ; but  if  it  be  suspended  in  a vertical  plane,  on  a horizontal  axis,  so  as  to  admit  ol 
a deflection  of  Inclination,  then  it  tends  to  place  itself  across  the  wire  as  before.  If  the  needle  be  on 
the  east  side  of  the  uniting  wire,  that  is,  on  the  right  hand,  taking  the  current  and  direction  as  at  first, 
then  the  south  pole,  next  the  copper  side  of  the  battery,  dips  below  the  horizontal  plane,  and  the  north 
pole,  next  the  zinc  plate,  rises.  If  the  current  be  reversed,  the  deflections  are  also  reversed.  If  the 
needle  be  placed  on  the  left  hand,  or  west  side  of  the  uniting  wire,  then  the  south  pole,  next  the  copper 
plate,  rises,  and  the  opposite  north  pole  dips.  By  reversing  the  direction  of  the  current,  these  deflec- 
tions are  again  reversed. 

It  is  apparent,  from  the  successive  directions  of  the  bar  as  it  becomes  placed  above,  at  the  sides,  or 
below  the  wire  S FT,  that  the  force  affecting  the  magnet  is  a force  transverse  to  the  pole  of  the  bar,  by 
which,  if  the  bar  had  complete  freedom  of  motion  in  every  direction,  the  poles  would  actually  turn 
round  the  wire,  but  in  different  directions ; and,  conversely,  supposing  the  bar  fixed,  and  the  wire  S IT 
carrying  the  current  free  to  move,  then  those  parts  of  the  wire  parallel  to  the  magnet  would  rotate 
about  the  magnetic  poles  in  opposite  directions,  in  a similar  way.  If  both  are  supposed  free  to  move 
in  any  direction,  then  the  wire  and  magnet  would  turn  round  each  other,  and  such  is  really  found  to 
happen,  giving  rise  to  a very  important  series  of  electro-magnetic  actions. 


MAGNET— MAGNETISM. 


or 

oi 


Let  a magnetic  bar  M M',  Fig.  2689,  be  bent  so  as  to  produce  a short  oblique  portion  at  the  middle 
of  the  bar,  with  two  vertical  arms  M M' ; poise  it  on  a fine  central  point  c,  and  let  a wire  N S be 
placed  near  and  parallel  to  one  of  the  arms  M.  Then,  supposing  a descending  current  to  flow  from  the 
copper  plate  c,  Fig.  2688,  through  the  wire  in  the  direction  H S,  upon  the  zinc  plate  Z,  the  magnet  M 
revolves  about  the  wire  N S,  upon  the  central  point  c ; and  if  the  north  pole  of  the  bar  be  uppermost, 
the  motion  will  be  direct,  or  from  the  left  hand  to  the  right. 

Conversely,  if  the  magnet  M be  fixed  as  in  Fig.  2690,  and  the  wire  N S be  movable  on  a fine  centre 
o,  then,  on  transmitting  the  current  as  before,  through  the  wire  N S,  it  immediately  revolves  about  the 
pole  P of  the  magnet,  with  a direct  screw  motion,  supposing  the  current  to  descend  the  wife,  and  the 
pole  P to  be  a north  pole.  To  enable  these  motions  to  go  on  without  disturbing  the  progress  of  the 
current  and  the  connections  with  the  Voltaic  plates,  the  movable  parts  dip  into  small  cups  and  cisterns 
containing  mercury,  and  with  which  the  plates  of  the  Voltaic  circle,  Fig.  2688,  communicate,  as  indi- 
cated in  the  figures. 

2691. 


The  tangential  or  transverse  force,  by  which  a magnetic  pole  is  caused  to  revolve  about  a wire  trans- 
mitting a current  of  Voltaic  electricity,  is  equally  apparent  when  the  magnetic  bar  itself  becomes  the 
conjunctive  wire  of  the  battery ; so  that  an  electrical  current  flowing  over  or  through  a magnetic  bar 
from  one  of  its  poles  to  the  equator,  or  from  the  equator  to  either  of  the  poles,  causes  such  a bar  to 
revolve  upon  its  axis,  the  requisite  mechanical  arrangements  for  motion  being  complete. 

Let  a magnetic  bar,  S P,  Fig.  2691,  be  mounted  vertically  between  two  delicate  centres ; the  bar  may 
be  about  18  inches  in  length,  1 inch  wide,  and  of  an  inch  thick.  Let  an  electrical  current  be  caused 
to  flow  from  either  of  the  poles  P S to  the  equator  d,  oj-  from  d to  either  of  the  poles  P ; the  bar  will 
immediately  revolve  upon  its  axis  P S,  the  direction  of  the  motion  being  such,  that  supposing  the  bar 
to  rest  upon  its  north  pole  P,  the  centre  d being  in  communication  with  the  copper  plate  of  the  battery 
C,  and  either  or  both  of  the  poles  P S in  communication  with  the  zinc  plate  Z,  electrical  currents  w’dl 
flow  from  the  equator  d to  tihe  poles,  and  the  bar  will  revolve  from  left  to  right,  as  in  the  motion  of  the 
hands  of  a watch,  or  a common  right-handed  screw.  By  reversing  the  communication  with  the  Voltaic 
plates,  that  is,  placing  the  poles  P S in  connection  with  the  copper  plate,  and  the  centre  d with  the  zinc 
plate,  the  electrical  current  will  flow  from  the  poles  to  the  equator  d.  In  this  case,  the  direction  of  the 
motion  will  be  the  reverse  of  the  former ; it  will  be  from  right  to  left,  or  backward,  as  it  were. 

If  the  position  of  the  magnet  be  changed,  that  is,  if  we  place  it  to  rest  with  its  south  pole  below, 
then,  the  communication  with  the  Voltaic  circle  remaining  as  in  the  first  instance,  we  also  reverse  the 
motion.  If  now  the  communications  be  changed,  as  in  the  last  instance,  we  again  reverse  the  motion, 
and  obtain,  as  at  first,  a motion  from  left  to  right. 

To  facilitate  the  passing  of  the  electrical  current  over  the  magnet,  the  bar  is  supported  between  fine 
centres  P S by  a light  vertical  column  fixed  on  a firm  base  ; a small  ring  or  cistern  of  mercury  d,  also 
supported  from  the  vertical  column,  surrounds  the  equator  of  the  bar ; the  bar  turns  within  this,  and  it 
is  connected  with  the  mercury  in  turning  by  a small  bent  wire  dipping  into  the  cistern ; the  lower 
centre  P turns  upon  an  agate  contained  in  a small  cup  at  P,  connected  with  the  point  Z' ; this  cup  con- 
tains a small  globule  of  mercury,  to  keep  up  the  metallic  connection  with  the  magnet ; there  is  a simi- 
lar globule  in  a small  cavity  at  the  upper  end  of  the  bar  for  the  centre  S ; this  upper  centre  is  sup- 
ported by  a wire  extending  from  the  head  of  the  pillar  Z Zr.  It  is  here  evident,  that  in  connecting  the 
points  C Z or  C Z'  witli  the  plates  of  the  Voltaic  circle,  an  electrical  current  will  flow  between  these 
points  through  C d S Z,  or  C d p Z',  the  direction  depending  on  the  respective  connections  with  the  zinc 
or  copper  plate  of  the  circle. 

A recollection  of  the  relative  direction  of  the  motions  we  have  been  describing  will  be  facilitated  by 
keeping  in  mind  the  following  simple  formula:  a descending  current  moves  a north  pole  to  the  right 
hand,  or  will  give  rise  to  a direct  screw-motion ; from  this  simple  fact  all  other  relative  motions  are 
easily  determined. 

The  reciprocal  action  of  a magnetic  needle  and  uniting  wire,  together  with  the  series  of  deflections 
in  given  directions,  have  led  to  the  invention  of  a very  important  magnetical  instrument,  termed  the 
Electro-magnetic  Multiplier,  or  Galvanometer,  by  which  extremely  small  magnetic  and  electro- magnetic 
forces  may  be  detected  and  measured. 

It  will  be  apparent,  as  already  observed,  that  a current  flowing  both  above  and  below  a needle,  is 


318 


MAGNET— MAGNETISM. 


opposite  directions,  deflects  the  needle  in  the  same  direction ; hence  it  follows  that  if  a magnetic  needle 
p t,  Fig.  2G92,  be  suspended  on  a delicate  centre  c,  within  the  bite  of  a returning  wire  zdc,  and  the 
extremities  zcof  the  wire  connected  with  the  zinc  and  copper  plates  of  the  Voltaic  circle  by  means  of 
two  little  cups  containing  mercury,  then  a current  will  flow  longitudinally  round  the  needle,  both  above 
and  below  it,  and  in  opposite  directions,  that  is  to  say,  in  the  direction  c d above  the  needle,  and  in  the 
direction  d z under  it ; the  effect  of  this  will  be  to  deflect  the  needle  with  twice  the  power  by  which  it 
would  be  deflected  with  a single  current  only,  as  in  Fig.  2688. 

If  we  imagine  the  wire  zdc  to  be  several  times  turned  longitudinally  about  the  needle,  as  in  Fig. 
2693,  then  the  effect  would  be  still  further  increased ; it  would,  in  fact,  become  multiplied  in  proportion 
to  the  number  of  turns  of  the  wire,  which  would  represent  so  many  additional  currents.  It  ii  only 
requisite  to  cover  the  wire  with  silk  thread,  or  some  other  imperfect  or  non-conducting  matter,  so  as 
to  avoid  metallic  communication  between  the  coils,  and  oblige  the  current  to  traverse  the  whole  length 
of  the  wire.  This  is  the  principle  upon  which  the  electro-magnetic  multiplier  rests,  and  the  delicacy  of 
the  effect  is  such  that  the  needle  will  become  deflected  by  the  immersion  of  two  pieces  of  zinc  and 
platinum  wire  less  than  |th  of  an  inch  long,  and  -jL-th  of  an  inch  in  diameter,  in  water  slightly  acidu- 
lated. Fig.  2694  represents  this  instrument  under  one  of  its  most  perfect  and  delicate  forms.  Two 


2694. 


magnetic  needles,  with  their  poles  reversed  to  each  other,  are  fixed  on  a central  rigid  axis,  so  as  to  neu- 
tralize the  directive  power  of  the  needles,  merely  allowing  a sufficient  force  to  bring  the  whole  into  the 
meridian.  This  system  is  suspended  by  two  parallel  threads  of  unspun  silk  r n,  one  of  the  needles 
being  within  a rectangular  coil  of  wire  zdc,  and  the  other  needle  immediately  without  it,  and  over  the 
upper  part  of  the  coil.  The  wire  z c is  covered  with  silk  thread,  so  that  the  coils  may  not  have  metal- 
lic communication,  and  the  extremities  p q are  brought  out  near  each  other,  and  terminate  in  small  cups 
p q,  containing  a little  mercury,  for  the  better  convenience  of  communicating  a current  to  the  coil  from 
any  given  source.  The  coils  are  separated  a little  near  the  centre,  to  allow  the  axis  of  the  astatic  sys- 
tem of  the  two  needles  to  pass  through  them. 

The  slightest  current  transmitted  through  the  coil  from  p to  q , or  q to  p,  causes  the  needles  to  deviate 
from  their  constant  position.  Both  the  needles,  as  is  evident,  will  be  impelled  in  the  same  direction ; 
the  lower  needle  being  in  the  position  just  described,  Figs.  2692  and  2693,  whilst  the  upper  needle,  its 
poles  being  reversed,  is  impelled  in  the  same  direction  by  the  upper  side  of  the  coil. 

The  threads  of  the  double  or  bifilar  suspension  r n,  in  tending  to  cross  each  other  as  the  needles  turn, 
give  rise  to  a reactive  force,  which  may  be  set  against  the  deflective  force  employed  to  measure  it ; for 
this  purpose  a graduated  circle  s s is  fixed  under  or  round  the  upper  needle,  so  that  the  angle  of  deflec- 
tion may  be  accurately  estimated.  If  the  earth’s  directive  force  be  completely  neutralized  by  the  re- 
versed positions  of  the  needles,  then  this  would  be  the  only  force  opposed  to  the  deflective  force  ; i 
not,  then  it  becomes  mixed  with  the  little  directive  power  left  in  the  system,  but  which  is  generally  so 
small  as  not  to  be  of  much  moment. 

The  instrument  is  set  upon  a convenient  stand,  and  may  be  inclosed  within  a glass  shade,  the  bifilar 
suspension  being  sustained  within  a tube  of  glass. 

Steel  magnetized  by  the  electrical  current. — One  of  the  many  important  results  of  these  discoveries  is 
the  means  of  imparting  a high  degree  of  magnetism  to  iron  and  steel,  and  to  so  great  an  extent  as  to 
give  a soft  iron  rod  a lifting  power  of  more  than  a ton. 

We  have  seen  that  the  electrical  and  magnetic  forces  are  so  related  that  the  one  is  exerted  at  right 
angles  to  the  other.  We  derive  from  this  elementary  principle  a means  of  disturbing  the  latent  mag- 
netic forces  resident  in  magnetic  substances,  by  which  these  forces  become  separated,  and  the  body  ren- 
dered magnetic,  precisely  in  the  same  way  as  effected  by  the  contact  of  an  ordinary  magnet. 

Let  a long  piece  of  copper  wire  be  wound  round  a piece  of  glass  tube  of  about  an  inch  or  less  in 
diameter,  and  from  6 to  10  inches  in  length,  so  as  to  produce  a helix  or  spiral,  A B,  Fig.  2695,  and  mount 
this  spiral  between  two  vertical  supports,  as  represented  in  the  figure.  Place  a perfectly  neutral  piece 
of  hard  steel  wire  pn,  of  about  Ath  of  an  inch  in  diameter,  or  a large  sewing  needle  within  the  helix, 
and  connect  the  extremities  AB  with  the  zinc  and  copper  plates  of  the  Voltaic  circle,  the  steel  pn  will 
become  immediately  magnetic ; in  fact,  each  turn  of  the  spiral  causes  electrical  currents  to  flow  in  re- 
verse directions  above  and  below  the  steel.  If  the  coils  of  the  spiral  be  numerous  and  close,  they  maj 


MAGNET— MAGNETISM. 


319 


be  regarded  as  parallel  circles  standing  at  right  angles  to  the  direction  of  the  inclosed  wire,  and  with 
which  toe  axis  of  the  helix  may  be  made  to  coincide.  The  effect  of  a helix  of  this  kind  on  a fine  mag- 
netic needle  placed  within  it  is  so  powerful,  that  with  a strong  Voltaic  current  the  needle  is  frequently 
caught  up  and  retained  on  the  axis  of  the  spiral,  as  if  liberated  from  the  trammels  of  gravity. 

The  kind  of  polarity  given  to  steel  or  iron  thus  circumstanced  will  depend  on  the  direction  of  the 
current  with  reference  to  the  axis  of  the  helix,  and  this  again  will  depend  on  the  connections  with  the 
plates  of  the  Voltaic  circle  and  the  direction  in  which  the  helix  is  turned.  Now,  the  spiral  may  evi- 
dently be  turned  either  direct,  like  the  threads  of  a common  cork-screw,  forming  what  is  termed  a 
right-handed  helix,  or  they  may  be  turned  in  the  reverse  direction,  in  which  case  we  have  a left- 
handed  helix. 

If  we  suppose  the  helix  to  be  a reverse  or  left-handed  helix,  as  in  Fig.  2696,  the  current  flowing  from 
c to  2,  round  a small  cylindrical  steel  needle  or  wire  P N,  and  the  coils  standing  in  the  direction  of  the 
magnetic  meridian  c'  z',  so  that  the  current  may  flow  under  the  wire  in  the  direction  c'  z’,  from  south 
to  north,  as  indicated  by  the  dotted  lines,  and  over  the  needle  in  direction  c',  from  north  to  south,  as 
indicated  by  the  full  lines,  then  the  positive  pole  P will  be  determined  to  the  right  hand,  and  the  ex- 
tremity P,  of  the  wire  next  the  copper  plate  c,  will  be  a north  pole : by  similar  reasons  the  opposite 
extremity  N will  be  a south  pole,  and  next  the  zinc  plate  of  the  battery. 

If  we  take  a direct  or  right-handed  helix  and  an  inclosed  wire  PN,  as  in  Fig.  2697,  and  transmit  the 
current  as  before  from  c to  2,  then  the  reverse  of  all  this  occurs ; the  currents  flow  under  the  wire  from 
north  to  south  in  direction  z'c',  and  over  the  wire  from  south  to  north  in  direction  c'  z'.  Under  these 
conditions  the  positive  pole  P is  determined  to  the  left  hand,  so  that  the  extremity  P of  the  steel  cylin- 
der P N next  the  zinc  plate  becomes  a north  pole,  and,  by  similar  reasoning,  the  opposite  extremity  next 
the  copper  plate  c,  a south  pole.  Supposing  the  current  to  be  reversed  and  to  pass  through  a direct 
helix  from  left  to  right,  the  copper  plate  of  the  battery  being  to  the  left  hand,  and  which  is  the  ordi- 
nary form  of  the  experiment,  the  north  pole  will  be  always  determined  next  the  zinc  plate,  that  is.  to 
the  right  hand 


2GOO. 


Zfi08. 


ft  will  be  useful  to  the  student  to  remember  as  a general  fact,  that  supposing,  Fig.  2695,  the  observer 
to  be  facing  the  north,  N,  and  the  helix  A B placed  transversely  before  him  so  that  its  axis  may  lie 
east  and  west,  then  if  the  current  be  descending  the  coils  of  the  spiral  directly  before  him,  the  north  pole 
is  determined  to  the  light  hand,  and  the  south  pole  to  the  left.  Reciprocally,  if  the  current  be  ascend- 
ing the  cods  of  the  spiral  directly  before  him,  then  the  south  pole  is  determined  to  his  right  hand,  and 
the  north  pole  to  the  left.  Hence,  with  a direct  helix,  the  north  pole  will  be  always  found  next  the 
zinc  plate,  and  with  a left  helix  next  the  copper  plate. 

The  magnetic  power  developed  in  soft  iron  closely  surrounded  by  heliacal  coils  transmitting  electrical 
currents  all  in  the  same  direction  is  so  great,  that  a curved  iron  rod,  during  the  action  of  the  battery 
may  be  caused  to  sustain  an  enormous  weight.  The  usual  form  of  the  experiment  is  as  follows  : 

A cylindrical  bolt  of  soft  iron  P T N,  Fig.  2698,  about  an  inch  or  more  in  diameter,  and  from  80  to  40 
inches  long,  is  bent  into  the  horse-slroe  form,  as  indicated  in  the  figure.  It  is  then  surrounded  by  several 
long  coils  of  copper  wire  zTc,  covered  with  silk  or  other  iusulatiug  thread,  so  as  to  interrupt  all  metal- 
lic communication  or  coil  with  the  other;  one  set  of  coils  is  superposed  on  another,  and  all  the  ends  of 
the  wires  P N on  each  side  united  into  common  terminations  z c,  to  be  connected  wTith  the  battery. 

If,  when  the  currents  are  passing  through  the  coils,  we  apply  a soft  iron  keeper  P N,  and  cross  the 
projecting  poles,  it  will  be  held  fast  with  an  enormous  force,  so  that  several  hundred  weight,  W,  may 
be  suspended  without  breaking  the  contact.  An  electro-magnet  of  this  kind  may  become  ^o  powerful 
as  to  support  upwards  of  2 tons.  1 

. Instruments  for  indicating  the  presence  and  determining  the  polarity  of  magnetic  forces,  and  measur- 
ing their  quantitative  power  under  various  conditions. — Instruments  for  indicating  the  mere  presence  of 
magnetic  force,  and  determining  its  peculiar  polarity,  may  be  termed,  as  before  observed,  magneto- 
scopes ; those  for  its  quantitative  measurement,  under  various  conditions,  may  be  considered  as  mag- 
netometers. J n 


320 


MAGNET— MAGNETISM. 


Magnetoscopes  generally  consist  of  light  bars  or  needles,  either  suspended  by  a delicate  flexible 
thread,  or  attached  to  an  agate  or  metallic  cap,  and  set  on  a fine  central  point.  Of  these  two  forms  of 
suspension,  the  filar  suspension  is  the  most  sensitive.  The  Rev.  A.  Bennet,  F.  R.  S.,  employed  fila 
ments  of  a spider’s  web,  which  proved  so  extremely  delicate,  that  two  small  pieces  of  straw,  placed  at 
right  angles  to  each  other,  in  the  form  of  the  letter  T inverted,  would,  when  thus  suspended  under  a 
closed  receiver,  turn  towards  a person  coming  within  3 feet  of  the  glass,  and  would  move  so  decidedly 
towards  wires  merely  heated  by  the  hand,  as  much  to  resemble  magnetic  attraction.  A fine  and  weakly 
magnetic  steel  wire,  suspended  from  a spider's  thread  of  3 inches  in  length,  would  admit  of  being  twisted 
round  18,000  times,  and  yet  continue  to  point  accurately  in  the  meridian — so  little  was  the  thread  sen 
sible  of  torsion.* 

Magnetometers. — The  quantitative  measurement  of  magnetic  forces  may  be  either  direct  applications 
of  equivalent  weight,  or  any  species  of  equivalent  reactive  power,  as  in  the  reactive  force  of  torsion;  or 
may  consist  of  indirect  determinations  of  force,  through  the  medium  of  certain  relative  effects,  as  in  the 
amount  of  deviation  of  a suspended  magnetic  needle  from  its  line  of  direction  by  the  influence  of  a mag- 
net placed  at  a given  distance  from  the  needle. 

Scale-beam  magnetometer. — The  common  scale-beam,  has  been  occasionally  applied  to  the  measure- 
ment of  magnetic  forces.  A small  cylinder  of  iron  or  a magnet  is  to  be  suspended  from  one  arm  of  the 
beam,  and  counterpoised  by  weights  in  a scale-pan  suspended  on  the  opposite  arm.  The  beam  being 
sustained  on  any  convenient  support  in  the  usual  way,  a second  magnet  or  iron  is  placed  on  the  table, 
immediately  under  this,  and  the  attractive  force  at  any  given  measured  distance  is  estimated  by  addi- 
tional weights  placed  in  the  scale-pan. 

Much  care  is  requisite  in  effecting  this  experiment.  The  beam  should  not  be  allowed  any  very  con- 
siderable play,  but  be  limited  in  its  motions  by  two  vertical  forked  stops,  one  under  each  arm.  If  the 
beam,  with  a given  added  weight  in  the  scale-pan,  be  overset  by  the  attractive  force,  and  rest  on 
the  stop,  we  may  either  increase  the  distance  of  the  attracting  bodies,  or  increase  the  wgjght,  so  as  just 
to  catch  the  instant  of  the  balance  of  the  force.  Or,  supposing  a given  added  weight  in  the  scale-pan, 
we  may  continue  to  approximate  a magnet  towards  the  suspended  iron  or  other  magnet  over  a divided 
scale  of  distance,  and  catch  the  point  at  which  the  beam  turns. 

The  bent  lever,  or  any  self-adjusting  balance,  may  be  also  employed  in  a similar  way  to  the  measure- 
ment of  magnetic  force. 

The  hydrostatic  magnetometer. — This  instrument,  shown  in  its  general  form  in  Fig.  2700,  and  partially 
explained  in  the  following  figures,  is  of  such  convenient  and  universal  application  to  the  measurement 
and  exhibition  of  elementary  magnetic  phenomena  and  forces,  that  a particular  description  of  it  appears 
essential. 

A light  grooved  wheel,  W,  Fig.  2699,  about  two  inches  in  diameter,  being 
accurately  poised  on  a firm  axis,  rn  n,  is  mounted  on  the  smooth  circumfer- 
ences of  two  similar  wheels,  mw,  nw'.  The  extremities  of  the  axis  rn  n are 
turned  down  to  fine  long  pivots,  and  whilst  resting  on  the  friction-wheels  mw, 
nw',  pass  out  at  mn  between  other  small  check-wheels,  two  at  each  extrem- 
ity of  the  axis,  so  that  the  wheel  W cannot  fall  to  either  side  : great  freedom 
of  motion  is  thus  obtained.  These  friction  and  check  wheels  are  set  on  points 
or  pivots  in  light  frames  of  brass,  and  the  whole  is  supported  on  short  pillars 
screwed  to  a horizontal  plate  or  stage,  as  shown  at  A B,  Fig.  2700.  The  stage 
is  sustained  on  a vertical  column,  A E,  fixed  to  an  elliptical  base  of  mahogany, 

E,  supported  on  three  levelling  screws. 

There  is  a short  pin  li,  Fig.  2699,  fixed  in  the  circumference  of  the  wheel 
W,  to  receive  an  index  of  light  reed,  cut  to  a point,  and  movable  over  a gradu- 
ated arc  MN,  placed  behind  the  wheel,  as  represented  in  Fig.  2700:  the 
weight  of  this  index  is  balanced  by  a small  globular  mass  d,  movable  on  a 
screw  in  the  opposite  point  of  the  circumference ; so  that  the  wheel  alone  with 
the  index  would  rest  in  any  position,  or  nearly  so.  The  arc  MN  is  a quad- 
rant divided  into  180  parts : 90  in  the  direction  I M,  and  90  in  the  direction 
I N,  the  centre  0 being  marked  zero.  Two  fine  holes  are  drilled  through  the 
wheel,  one  on  each  side  of  the  point  h,  for  receiving  and  securing  two  silk  lines, 
ww' : these  lines  pass  over  the  circumference  on  opposite  arms  of  the  wheel, 
and  terminate  in  small  hooks,  t and  w.  A cylinder  ot  soft  iron  t,  or  a small 
magnet,  rather  less  than  2 inches  in  length  and  ijth  of  an  inch  in  diameter,  is 
suspended  by  a silk  loop  from  one  of  these  lines,  w‘,  and  a cylindrical  counter- 
poise of  wood,  a u,  weighted  at  u,  and  partly  immersed  in  water,  is  hung  in 
like  manner  from  the  oilier  line,  w.  The  weights,  and  altitude  of  the  water,  and  of  the  vessel  q con- 
taining it,  are  so  adjusted,  that  when  the  whole  system  is  in  equilibrio,  the  index  b o is  at  zero  of  the 
arc  M N.  With  a view  to  a perfect  adjustment  of  the  index,  the  water-vessel  q is  supported  in  a ring 
of  brass  at  the  extremity  of  a rod  q,  movable  in  a tube  k,  Fig.  2700 : this  tube  is  attached  to  a sliding 
piece  b h,  acted  on  by  a milled  head  at  h and  a screw  within  the  cylinder,  which  is  fixed  to  the  stage 
AB,  so  that  the  water-vessel  may  be  easily  raised  or  depressed  by  a small  quantity,  and  thus  the  index 
be  regulated  to  zero  of  the  arc  with  the  greatest  precision ; for  it  is  evident,  by  the  construction  of  the 
instrument,  that  the  position  of  the  index  will  depend  on  the  greater  or  less  immersion  of  the  cylindrical 
counterpoise  a w,  the  weight  of  which  being  once  adjusted  to  a given  line  of  immersion,  and  a given 
position  of  the  wheel  W and  index  O,  any  elevation  or  depression  of  the  water-vessel  q must  necessarily 
move  the  wheel.  The  counterpoise  a u is  about  1-J  inch  in  length  and  full  ’3  of  an  inch  in  diameter : a 
small  ball  of  lead  is  attached  to  its  lowest  part,  in  order  to  give  it  a sufficient  immersion,  and  at  the 


2G99. 


1 7i 


Phil.  Trans,  for  1792,  p.  86. 


MAGNET— MAGNETISM. 


321 


game  time  balance  the  iron  cylinder  t when  the  float  is  about  half  immersed  in  the  water.  With  a view 
to  a imal  regulation  of  the  weight,  a small  hemispherical  cup  a is  fixed  on  the  head  of  the  counterpoise 
for  the  reception  of  any  further  small  weights  required.  This  counterpoise  is  accurately  turned  out  ot 
fine-grained  mahogany,  and  is  freed  from  grease  or  varnish  of  any  kind,  so  as  to  admit  of  its  becoming 
easily  wetted  in  the  water. 

The  column  A E supporting  the  stage  A B consists  of  two  tubes  of  brass,  one,  G,  movable  within 
the  other,  E C,  so  that  by  a rack  on  the  sliding-tube  G,  and  a pinion  on  the  fixed  tube  at  C,  the  whole 
of  the  parts  just  described  may  be  raised  or  lowered  through  given  distances,  as  shown  by  a divided 
scale  G,  adjustabledo  any  point  by  means  of  a slide  and  groove  in  the  movable  tube  G.  The  brass 
tubes  composing  the  column  are  each  about  a foot  in  length  and  an  inch  in  diameter. 


o 


It  will  be  immediately  perceived,  from  the  general  construction  of  this  instrument,  that  if  any  force 
cause  the  cylinder  t to  descend,  then  the  index  h o will  move  forward  in  the  direction  0 N,  until  such  a 
portion  of  the  counterpoise  a u rises  out  of  the  water  as  is  sufficient  to  furnish,  in  the  fluid  it  ceases  to 
displace,  an  equal  and  contrary  force.  In  like  manner,  if  any  force  cause  the  cylinder  t to  ascend,  then 
we  have  the  reverse  of  this — the  counterpoise  obtains  an  equivalent  increased  emersion,  and  the  index 
moves  in  the  opposite  direction,  0 M.  Thus  if  we  place  a weight  of  1 grain,  for  example,  on  the  iron 
cylinder  t,  the  index  will  indicate,  in  the  direction  01,  a given  number  of  degrees  equal  to  a force  of  1 
grain.  If  we  double  this  weight,  we  obtain  a force  of  2 grains,  and  so  on.  The  converse  of  this  arises 
on  placing  the  weights  in  the  cup  of  the  counterpoise  a u.  We  may  thus  reduce  the  indications  to  a 
known  standard  of  weight.  It  is  further  evident,  that,  whether  we  operate  on  the  system  by  gravity 
or  by  the  attractive  or  repulsive  force  of  a magnet,  the  indications  of  force  are  equally  true. 

If  the  instrument  be  well  constructed,  and  the  counterpoise  freely  wetted  in  the  water,  the  march  of 
the  index  in  either  of  the  directions  0 IST  or  0 M will  correspond  to  the  added  weights.  Thus,  if  1 grain 
Vol.  II. — 21 


MAGNET— MAGNETISM. 


322 


gives  3 degrees,  2 grains  will  give  6 degrees,  and  so  on.  And  thus  we  obtain  a continual  and  knowt 
measure  of  the  force  we  seek  to  examine,  within  a given  range  of  degrees  of  the  arc,  which  will  be 
more  or  less  extensive  according  to  the  dimensions  of  the  cylindrical  counterpoise,  the  intensity  of  the 
force,  and  the  rate  of  its  increase.  When  we  require  to  examine  very  powerful  forces,  or  forces  operat- 
ing on  the  suspended  iron  t at  small  distances,  it  is  requisite  to  increase  the  size  of  the  counterpoise 
lloat,  the  indications  of  which  we  may  always  find  the  value  of  in  grains,  as  before. 

Previously  to  suspending  the  cylindrical  counterpoise  a u,  the  iron  cylinder  t should  be  placed  in 
equilibrio  on  the  wheel  W,  with  an  equal  and  opposite  weight,  as  previously  determined  by  an  accurate 
scale-beam,  in  order  to  observe  if,  when  loaded  with  the  whole,  the  wheel  W and  index  are  indifferent 
as  to  position  on  any  part  of  the  arc,  or  nearly  so.  The  instrument  will  be  sufficiently  delicate,  if,  when 
loaded  in  this  way  with  350  grains,  it  is  set  in  motion  by  something  more  than  J a grain  added  to  either 
side. 

In  order  to  retain  the  wheel  W,  Figs.  2699  and  2700,  in  its  position  at  the  time  of  removing  either  of 
the  suspended  bodies,  a small  brass  prong  is  inserted  at  h into  the  arms  of  the  circular  segment  M N,  so 
as  to  inclose  the  pin  h carrying  the  index : the  wheel  is  thus  prevented  from  falling  to  either  side. 

The  forces  requiring  to  be  measured  are  brought  to  operate  on  the  suspended  cylinder  t through  the 
medium  of  induction  on  soft  iron,  or  by  a magnetic  bar  placed  immediately  under  it,  either  vertically 
or  horizontally.  In  the  vertical  arrangement,  shown  in  Fig.  2700,  the  magnet  or  bon  is  fixed  against  a 
graduated  scale  S,  by  which  the  distance  between  the  attracting  surfaces  or  bodies  is  estimated.  This 
scale,  together  with  the  magnet  H,  is  secured  by  light  bands  s,  .of  brass,  united  by  a rod  D K.  The 
lower  band  and  rod  D are  both  fixed  to  a stage  D,  movable  between  guide-pieces,  and  acted  on  through 
a nut  at  q by  a vertical  screw  P q,  about  6 inches  in  length  and  |ths  of  an  inch  in  diameter  ; so  that  the 
whole  may  be  raised  or  depressed,  and  hence  the  suspended  cylinder  and  magnet  placed  at  any  re- 
quired distance  apart.  The  regulation  of  tliis  important  element  in  the  operation  of  magnetic  forces  is 
hence  provided  for  in  two  ways,  viz.,  by  the  rack  at  G and  the  milled  head  at  P,  either  of  which  may 
be  employed,  as  found  most  convenient.  The  scale  S is  of  boxwood,  1 foot  in  length,  fths  of  an  inch 
wide,  and  ^th  of  an  inch  thick : it  is  divided  into  inches,  subdivided  into  tenths  and  twentieths  of  an 
inch.  About  6 inches  of  the  upper  part  is  divided  in  this  way,  viz.,  3 inches  on  each  side  of  a central 
division  which  is  marked  zero ; the  rest  of  the  piece  extends  to  the  stage  D.  The  magnetic  bar  H is 
tied  to  the  scale  by  compressing  screws  and  simple  brass  bands,  either  fixed,  as  at  D and  K,  or  mov- 
able, as  at  H.  This  adjusting  apparatus  is  secured  to  a stout  brass  plate  It,  fitted  by  a dovetail  into  a 
sliding  piece  v,  forming  part  of  the  mahogany  stand  E,  so  that  it  may  be  removed  at  pleasure.  The 
brass  bands  and  frames  at  D PI  K are  sufficiently  capacious  to  inclose  two  bars  together  if  required,  the 
superabundant  space  being  filled  when  only  one  magnet  is  employed,  either  by  a bar  of  wood  or  small 
wedge  pieces  in  the  brass  frame*. 


When  we  require  to  examine  the  forces  in  different  points  of  a moderate-sized  magnetic  bar,  the  bar 
is  laid  in  a small  frame  piece  T Y,  Fig.  2701,  temporarily  fixed  by  a compressing  screw  to  the  divided 
scale  S,  in  the  way  already  described,  the  force  on  the  suspended  cylinder  t being  caused  to  operate 
through  a small  cylinder  of  soft  iron  d,  accurately  fitted  to  the  surface  of  the  bar ; and  thus,  by  sliding 
the  bar  along  in  the  holding-frame,  we  may  get,  approximatively,  by  induction  on  the  iron  d,  the  force 
of  any  point  in  the  bar. 

When  the  bar  is  of  considerable  magnitude  and  weight,  or  we  require  to  examine  inductive  forces, 
the  magnets  may  be  placed  on  a narrow  table,  ab,  Fig.  2702,  supported  on  a central  square  pillar  P, 
fitted  to  the  frame-pieces,  K P,  of  the  adjusting  apparatus  already  described,  so  that  the  whole  may 
be  raised  or  depressed  through  any  given  distance.  In  this  case  the  divided  scale  S,  which  measures 
the  distance  a between  the  attracting  or  repelling  surfaces,  is  a detached  piece  fixed  against  one  of  the 
perpendicular  sides  of  a right-angled  triangle,  so  as  to  be  anywhere  placed  upright  on  the  bar : the 


MANOMETER. 


323 


table  a b also  has  a divided  scale  movable  in  a wide  groove  through  its  centre,  by  which  any  dis- 
tance s between  magnetic  masses  may  be  also  shown.  When  the  bars  are  very  ponderous,  two  sup- 
ports are  required,  one  at  each  end  of  the  table  a b. 

Inductive  forces  are  examined  vertically  by  fixing  the  masses  by  compressing  bands  against  the 
scale  S,  Fig.  2702,  and  of  which  we  may  have,  if  requisite,  two  or  three  in  succession. 

These  arrangements  put  us  in  a position  to  note  readily  and  simultaneously  all  relative  distances  and 
forces  under  a great  variety  of  magnetic  and  apparently  complicated  conditions. 

We  have  been  somewhat  prolix  in  our  description  of  this  instrument,  but  not  unnecessarily  so. 
There  is  scarcely  any  elementary  experiment  in  magnetism  which  it  does  not  completely  and  satisfac- 
torily illustrate,  besides  furnishing  quantitative  measures  of  great  importance  to  the  mathematical  in- 
quirer into  the  laws  and  operations  of  magnetic  force.  See  Electro-Metallurgy. 

MAHOGANY.  The  beautiful  reddish-brown  colored  wood,  of  which  household  furniture  is  now 
chiefly  made.  It  is  a native  of  the  warmest  parts  of  America  and  the  West  Indies.  It  thrives  in  most 
soils  in  the  tropical  climates,  but  varies  in  texture  and  grain  according  to  the  nature  of  the  soil.  On 
rocks  it  is  of  a smaller  size,  but  very  hard  and  weighty,  of  a close  grain,  and  beautifully  shaded ; while 
the  produce  of  the  low  and  richer  lands  is  observed  to  be  more  light  and  porous,  of  a paler  color,  and 
open  grain ; and  that  of  mixed  soils  to  hold  a medium  between  both.  The  tree  grows  very  tall  and 
straight,  and  is  usually  four  feet  in  diameter.  On  account  of  the  difficulty  of  transporting  the  mahogany 
timber  from  the  forests,  when  the  tree  is  of  great  thickness  they  cut  it  into  short  logs,  otherwise  the 
great  weight  and  bulk  would  be  unmanageable  with  the  restricted  means  available  on  the  spot ; and 
with  the  view  of  equalizing  the  burden  or  draft  of  the  cattle,  (oxen,)  the  logs  are  long  in  proportion  to 
their  diminished  thickness.  The  largest  log  ever  cut  in  Honduras  was  of  the  following  dimensions : 
length  17  feet,  breadth  57  inches,  depth  64  inches;  measuring  5421  feet  of  plank,  of  one  inch  in  thick- 
ness, and  weighing  upwards  of  15  tons. 

MANOMETER.  An  instrument  for  measuring  the  rarefaction  and  condensation  of  elastic  fluids,  but 
especially  that  of  the  atmosphere.  It  differs  from  the  barometer,  which  shows  only  the  weight  of  the 
superincumbent  column  of  air ; whereas  the  manometer  shows  the  density,  which  depends  on  the  com- 
bined effect  of  weight  and  the  action  of  heat.  It  is  sometimes  called  manoscope.  Among  the  various 
contrivances  of  this  kind  may  be  mentioned  that  of  the  Hon.  Robert  Boyle,  which  he  calls  a statical 
barometer,  which  consists  of  a bubble  of  thin  glass,  about  the  size  of  an  orange,  which,  being  counter- 
poised in  an  accurate  pair  of  scales,  rises  and  sinks  with  the  alterations  of  the  atmosphere.  This  instru- 
ment, however,  does  not  show  the  cause  of  the  difference  of  density  in  the  atmosphere,  whether  it  be 
from  a change  of  its  own  weight,  or  its  temperature,  or  both.  The  manometer  constructed  by  Mr. 
Ramsden,  and  used  by  Capt.  Phipps  in  his  voyage  to  the  North  Pole,  was  composed  of  a tube  of  small 
bore,  with  a ball  at  the  end ; the  barometer  being  2'97,  a small  quantity  of  quicksilver  was  put  into  the 
tube,  to  take  off  the  communication  between  the  external  air  and  that  confined  in  the  ball,  and  the  part 
of  the  tube  below  this  quicksilver.  A scale  is  placed  on  the  side  of  the  tube,  which  marks  the  degrees 
of  dilatation  arising  from  the  increase  of  heat  in  this  state  of  the  weight  of  the  air,  and  has  the  same 
graduation  as  that  of  Fahrenheit’s  thermometer,  the  point  of  freezing  being  marked  32°.  In  this  state, 
therefore,  it  will  show  the  degrees  of  heat  in  the  same  manner  as  a thermometer.  But  if  the  air  be- 
comes lighter,  the  bubble  inclosed  in  the  ball  being  less  compressed,  will  dilate  itself,  and  take  up  a 
space  as  much  larger  as  the  compressing  force  is  less ; therefore  the  changes  arising  from  the  increase  of 
heat  will  be  proportionably  larger,  and  the  instrument  will  show  the  differences  in  the  density  of  the  air, 
arising  from  the  changes  in  its  weight  and  heat.  Mr.  Ramsden  found  that  a heat  equal  to  that  of  boil- 
ing water  increased  the  magnitude  of  the  air  from  what  it  was  at  the  freezing  point  by  A1/-  of  the 
whole.  Hence  it  follows,  that  the  ball  and  part  of  the  tube  below  the  beginning  of  the  scale,  is  of  a 
magnitude  equal  to  almost  414  degrees  of  the  scale.  If  the  height  of  both  the  manometer  and  ther- 
mometer be  given,  the  height  of  the  barometer  may  be  determined  also. 

When  used  for  measuring  pressure  above  that  of  the  atmosphere,  the  instrument  (as  usually  con- 
structed) is  in  all  respects  the  same,  except  that  the  tube  is  not  filled  with  mercury,  but  inverted,  while 
full  of  atmospheric  air,  into  a reservoir  of  mercury,  and  the  scale  is  differently  marked.  When  the 
pressure  on  the  surface  of  the  mercury  in  the  reservoir  is  that  of  the  atmosphere,  the  mercury  will  rise 
in  the  tube  nearly  to  the  level  of  that  surface,  (but  slightly  lower,  owing  to  the  resistance  of  the  air  ir, 
the  glass  tube.)  As  soon,  however,  as  the  pressure  communicated  exceeds  that  of  the  atmosphere,  the 
mercury  will  be  forced  up  into  the  tube,  and  the  inclosed  air  condensed,  until  its  elastic  resistance  is  just 
equal  to  the  pressure.  The  height  of  the  mercurial  column  will  of  course  vary  with  any  variation  of 
pressure,  and  thereby  indicate  the  degree  of  pressure  at  every  moment  by  means  of  the  scale,  which  is 
divided,  according  to  Mariotte’s  law,  into  atmospheres,  pounds,  or  the  like. 

The  high  degree  of  pressure  to  which  the  last-described  form  of  manometer  may  be  subjected  without 
error  from  friction  or  loss  of  mercury,  the  permanent  elasticity,  and  the  every-where  existing  and  ex- 
actly defined  qualities  of  the  material  of  resistance,  (atmospheric  air,  or  other  fluids  of  the  same  nature,) 
its  comparatively  small  dimensions  and  convenient  form,  make  it  a very  desirable  instrument  for  meas- 
uring the  pressure  of  steam.  As  usually  constructed,  however,  it  has  defects,  which  have  prevented  its 
general  use  as  a steam-gage.  Among  these  defects  were  the  coating  and  consequent  opacity  of  the 
glass  tube,  by  the  deposition  of  an  oxide  of  mercury  when  acted  on  by  the  inclosed  atmospheric  air ; 
the  expansion  and  partial  loss  of  air  from  within  the  tube  whenever  any  partial  vacuum  was  produced 
in  the  boiler,  and  so  allowing  the  mercury  to  rise  higher  in  the  tube  with  the  same  pressure ; its  oscil- 
lation, especially  when  there  is  a varying  pressure,  as  in  engines  working  expansively ; the  almost 
constant  tendency  of  the  condensed  steam  to  insinuate  itself  between  the  mercury  and  the  glass, 
and  to  find  its  way  into  the  tube  above  the  mercury ; and  the  great  inequality  in  the  divisions  ot 
the  scale,  arising  from  the  peculiarities  of  the  law  that  governs  the  volume  of  aeriform  fluids  under 
pressure. 

The  improvements  by  which  these  defects  have  been  remedied,  at  the  same  time  rendering  it  mor« 


324 


MANOMETER. 


2704. 


cell 


2703. 


2700. 


serviceable  for  determining  pressures  less  than  that  of  the  atmosphere,  have  recently  been  made  tht 
subject  of  a patent  to  Mr.  Paul  Stillman,  of  Few  York. 

Fig.  2703  is  the  usual  form  of  the  patent  manometer  for  showing  a pressure  up  to  eight  atmospheres 
Fig.  270-1  represents  the  form  of  one  for  showing  a pressure  up  to  twenty  atmospheres. 

Fig.  2705  is  the  form  used  for  showing  less  than  one  atmosphere.  The  arrangement  of 
the  glass  tube  is  quite  similar  in  all  the  forms  usually  given  to  the  instrument. 

Fig.  2706  is  a longitudinal  section  through  the  centre  of  the  glass  tube,  in  which  A is 
the  tube ; B is  an  iron  piece  in  which  the  tube  is  firmly  secured  by  means  of  the  stuffing- 
box  G.  It  is  screwed  at  one  end  to  receive  the  brass  case  C,  and  in  the  middle  to  confine 
it  in  the  reservoir  of  mercury  into  which  the  lower  end  of  the  tube  is  to  be  immersed. 

D D are  scales  divided  into  atmospheres,  pounds,  or  inches  of  pressure,  as  desired.  E E 
are  blocks  to  secure  the  scales  in  their  proper  places.  F is  a gland  which  protects  the 
lower  end  of  the  tube,  and  compresses  the  packing  in  the  stuffing-box  G.  H is  a cap  or 
plug  loosely  screwed  into  the  gland  to  facilitate  the  operation  of  charging  the  tube,  and 
also,  by  admitting  the  mercury  into  the  tube  only  through  the  interstices  of  the  screw, 
prevent  its  oscillation,  and  at  the  same  time  allow 
the  orifice  to  be  made  the  full  size  of  the  tube 
whenever  it  may  be  necessary  to  clean  the  tube. 

In  Fig.  2703  the  reservoir  for  mercury  is  a deep 
" with  an  iron  tube  communicating  from  the 


cock  at  the  bottom  to  the  middle  of  the  chamber  above  the  surface  of  the  mercury.  In  Fig.  2701  it  is 
divided,  the  glass  tube  being  inserted  into  a cell  of  greater  depth,  while  the  reservoir  of  mercury  is  in 
the  bulb,  to  which  a sufficient  elevation  is  given  to  compress  the  gas  within  the  tube  to  two  or  three 
times  the  density  of  the  atmosphere,  according  to  the  density  of  the  steam  of  which  it  is  to  serve  as  the 
gage.  In  this,  as  in  the  other  form,  an  iron  tube  communicates  the  pressure  from  the  cock  below  to 
the  surface  of  the  mercury  in  the  bulb  above.  The  subdivisions  of  the  scale  are  by  this  means  much 
more  uniform  and  distinct  than  when  used  at  atmospheric  pressure  only. 

In  all  cases,  the  mercury  should  be  seen  above  the  junction  of  the  tube  with  the  tube-holder,  so  as  to 
indicate  the  initial  pressure,  or  0.  In  Fig.  2703  it  is  brought  up  by  partially  exhausting  the  tube  at  the 
time  it  is  erected.  In  Fig.  2704  it  is  forced  up  by  the  superincumbent  weight  of  the  mercury  in  the 
bulb.  The  oxidation  of  the  mercury  within  the  tube  is  prevented  in  the  latter  form  of  the  instrument 
by  charging  the  tube  with  nitrogen  or  hydrogen  gas ; but  in  the  former,  on  account  of  the  difficulty  of 
preventing  the  admixture  of  atmospheric  air,  while  exhausting  a portion  of  the  contents  of  the  tube,  for 
the  purpose  above  referred  to,  atmospheric  air  only  is  used,  and  a drop  or  two  of  naphtha  or  other 
fluid  answering  the  end,  is  introduced  within  the  tube,  on  the  surface  of  the  mercury,  to  prevent  the 
oxidation. 

When  designed  to  show  a pressure  less  than  atmospheric,  but  not  less  than  that  shown  by  two  inches 
of  mercury,  the  tube  is  to  be  perfectly  filled  with  mercury,  and  inverted  in  the  reservoir,  and  the  press- 
ure will  be  determined  by  the  number  of  inches  sustained  above  the  level  of  the  mercury  in  the  reser- 
voir below ; but  if  it  is  to  be  used  for  a pressure  less  than  the  weight  of  two  inches  of  mercury — that 
being  the  distance  from  the  lowest  visible  part  of  the  glass  tube  to  the  surface  of  the  mercury  in  the 
reservoir — it  will  be  necessary  to  use  the  bulb  shown  in  Fig.  2704,  but  with  such  an  elevation  only  as 


MARBLE-SAWING  MACHINERY. 


325 


will  brine  the  surface  of  the  mercury  in  it  to  a height  equal  to  the  lowest  visible  part  of  the  glass  tube  ; 
or  it  may  be  done  equally  well  by  using  the  form  shown  in  Fig.  2104:,  if  a scale  is  properly  made  for 
the  purpose,  and  the  bulb  elevated  so  as  to  compress  the  air  so  high  in  the  tube  as  to  allow  the  mercury 
to  have  sufficient  fall  without  going  out  of  sight,  when  the  pressure  of  the  atmosphere  is  removed  from 
the  surface  of  the  mercury  in  the  bulb  above. 

It  will  be  seen  that  either  of  these  arrangements  would  resist  the  tendency  of  such  partial  vacuum  as 
is  generally  formed  in  steam-boilers,  when  they  are  allowed  to  cool  down,  from  disturbing  the  quantity 
of  air  within  the  tube  of  the  manometer. 

If  the  initial  quantity  of  air  or  gas  in.  the  tube  be  deranged  by  a change  of  temperature,  or  by  any 
other  cause,  it  becomes  necessary  to  know  the  extent  of  the  variation  occasioned  thereby.  To  ascertain 
this,  (if  inexpedient  to  correct  it  at  once,)  a simple  arrangement  is  adopted,  viz.,  1st,  to  remove  the  press- 
ure by  closing  the  stop-cock  and  opening  the  small  waste-cock  between  it  and  the  reservoii  this  will 
allow  the  mercury  to  fall  to  a place  in  which  it  will  be  at  equilibrium  with  the  atmosphere ; 2d,  to  note 
the  point  to  which  it  descends.  The  variation  from  the  original  place  of  0 will  be,  in  addition  to  the 
pounds  shown  on  the  scale-plate,  such  part  of  the  whole  as  the  variation  from  0 bears  to  the  whole 
length  of  the  tube  above  0.  To  determine  this  proportion,  a series  of  decimals  is  placed  on  the  scale  at 
fixed  distances,  and  the  one  of  these  nearest  to  where  the  base  of  the  column  of  air  within  the  tube  rests, 
is  to  be  used  as  a multiplier,  by  which  the  pressure  of  steam  indicated  on  the  scale  is  to  be  multiplied. 
Their  product,  less  the  pounds  of  variation  shown  on  the  scale,  will  be  the  true  pressure.  Thus,  for 
example,  if  the  mercury  in  the  tube  falls  until  the  base  of  the  column  of  air  rests  at  the  decimal  *96, 
which  would  be  near  to  the  place  due  to  1 pound  pressure,  and  if,  on  opening  the.  communication  to  the 
boiler  again,  it  should  rise  to  130  pounds,  this  apparent  pressure  of  130  pounds  is  to  be  multiplied  by 
•96,  and  deduct  from  their  product  the  1 pound,  thus  giving  as  the  true  pressure  123'8  pounds,  showing 
a variation  of  6'2  pounds.  See  Gage,  Indicator. 

MANGLE,  house.  Figs.  2T0T  and  2108  exhibit  a house  mangle  for  swathing  cloth,  the  action  of 
which  is  obvious.  2708. 


MAPLE-WOOD,  is  found  growing  in  mountain  districts,  is  indigenous  to  the  United  States,  and  val- 
uable for  its  lightness ; and  not  being  subject  to  warp  or  split,  it  will  take  any  color,  and  a fine  polish. 
When  green,  it  weighs  61  lbs.  9 oz.  a cubic  foot;  and  when  dry,  51  lbs.  15  oz. 

The  bird’s-eye  maple , from  the  beauty  of  its  grain  and  the  shades  of  its  spots,  is  much  employed  for 
veneering ; by  sawing  the  timber  nearly  parallel  with  the  concentric  rings,  the  effect  of  its  marking  or 
pencilling  is  much  improved.  In  this  country  wheelwrights  employ  it,  after  giving  it  a seasoning  for 
two  or  three  years ; and  when  constantly  under  water  it  will  not  readily  perish. 

MARBLE-SAWING  AND  POLISHING  MACHINERY,  worked  by  steam-power.  Marble  has.  of 
late  years  been  extensively  worked  by  machinery  driven  by  steam-power ; the  processes  are  closely 
analogous  in  principle  to  those  pursued  by  hand,  but  with  various  modifications  of  the  apparatus,  and 
it  is  proposed  to  explain  briefly  some  of  the  peculiarities  of  the  machine  processes. 

In  the  simplest  application  of  machinery  to  sawing  marble,  as  for  making  one  or  two  cuts  in  a large 
block,  the  construction  of  the  ordinary  stone-saw  is  closely  followed,  but  the  frame  is  made  much 
stronger,  of  squared  timber  firmly  bolted  together,  and  stayed  with  chains ; to  constitute  three  sides  of 
a rectangular  frame,  the  place  of  the  pole  and  tightening  chain  of  the  saw  is  occupied  by  two  fixed 
beams,  and  the  saw  is  held  and  stretched  by  means  of  two  clamps  with  screws  passing  through  the  ends 
of  the  frame,  and  tightened  by  nuts  on  the  outside.  The  saw-frame  works  between  vertical  guide-posts 
to  keep  it  upright,  and  it  is  reciprocated  horizontally  by  a connecting-rod  fixed  to  a crank  driven  by  the 
engine.  The  connecting-rod  is  attached  to  the  frame  by  a loop,  which  can  be  placed  at  various  heights, 
so  as  always  to  keep  the  stroke  of  the  connecting-rod  nearly  horizontal,  notwithstanding  the  gradual 
descent  of  the  saw  in  the  cut. 

These  saw-frames  are  sometimes  made  as  large  as  16  feet  long  and  10  feet  high,  for  cutting  huge 
blocks  of  marble ; and  to  prevent  the  great  weight  of  these  frames  from  pressing  on  the  cut,  they  are 
suspended  at  each  end  by  chains  or  slings  which  vibrate  with  the  saw,  and  are  connected  with  a coun- 
terpoise weight,  that  is  adjusted  to  allow  of  the  necessary  pressure  for  tire  cutting,  which  is  effected 


826 


MARBLE-SAWING  MACHINERY. 


■with  sand  and  water  supplied  in  the  same  manner  as  for  the  stone-saw  used  by  hand,  but  the  introduo 
tion  of  the  guide  principle  renders  the  chasing  of  the  stone  for  the  entry  of  the  saw  unnecessary.  In 
some  cases  smaller  saws  ot  similar  construction  are  used  for  cutting  thick  slabs  into  narrow  slips,  and 
sometimes  several  cuts  are  made  at  once  by  an  equal  number  of  saw-blades,  arranged  in  a rectangula” 
frame  that  is  suspended  horizontally  by  vibrating  slings,  and  works  between  vertical  guide-posts. 

In  the  horizontal  sawing  machine  for  marble  patented  by  Mr.  James  Tulloeh,  in  1824,  the  entire  ar 
rangements  are  combined  in  a very  effective  manner,  for  cutting  a block  of  marble  into  a number  ol 
parallel  slabs,  of  any  thickness,  at  the  one  operation.  The  iron  frame-work  of  the  machine,  shown  in 
Fig.  2109,  consists  of  four  vertical  posts  strongly  connected  together  at  the  top  and  bottom,  to  form  a 
stationary  frame  from  10  to  14  feet  long,  4 to  5 feet  wide,  and  8 to  12  feet  high,  within  which  the  block 
of  marble  to  be  sawn  is  placed.  The  two  upright  posts  at  each  end  of  the  stationary  frame  have,  on 
their  insides  opposite  to  each  other,  perpendicular  grooves,  within  each  pair  of  which  slides  up  and  down 
a square  vertical  frame  ; to  the  lower  end  of  each  of  these  slides  is  affixed  a spindle  carrying  two  guide- 
pulleys,  or  riggers,  upon  which  the  horizontal  saw-frame  rests,  and  is  reciprocated  backwards  and  for- 
wards. The  saw-frame  is  thus  traversed  within  the  fixed  framing,  and  supported  upon  the  four  guide- 
pulleys  of  the  vertical  slides,  which  latter  are  themselves  suspended  by  chains  coiled  upon  two  small 
drums  placed  overhead.  On  the  same  spindle  with  the  drums  is  a large  wheel,  to  which  a counterpoise 
weight  is  suspended  by  a chain.  The  weight  of  the  counterpoise  is  so  adjusted  as  to  allow  the  saw- 
frame  to  descend  when  left  to  itself,  and  which  thus  supplies  the  necessary  pressure  for  causing  the 
penetration  of  the  saws. 


The  saw-frame  is  made  rectangular,  and  from  two  to  three  feet  longer  than  the  distance  between  the 
vertical  slides,  in  order  to  permit  of  the  horizontal  traverse  of  the  saws,  which  is  from  18  to  20  inches. 
To  allow  of  the  blades  being  fixed  in  the  frame  with  the  power  of  separate  adjustment,  every  blade  is 
secured  by  rivets  in  a clamp  or  buckle  at  each  end.  The  one  extremity  of  the  buckle  embraces  the  saw, 
the  other  is  made  as  a hook ; the  buckle  at  one  end  of  the  saw  is  hooked  upon  a horizontal  bar  fixed 
across  the  end  of  the  saw-frame,  and  the  opposite  end  of  the  frame  has  a groove  extending  its  entire 
width,  through  which  a separate  hook,  provided  with  a vertical  tightening  wedge,  is  inserted  for  every 
saw,  which  thus  admits  of  being  replaced  without  deranging  the  position  of  the  neighboring  blades. 

The  distances  between  the  saws,  and  their  parallelism  with  the  sides  of  the  frame,  are  adjusted  by 
means  of  iron  blocks  made  of  the  exact  thickness  required  in  the  slabs  of  marble ; the  blocks  and  blades 
are  placed  alternately,  and  every  blade  is  separately  strained  by  its  tightening  wedge  until  it  is  suffi- 
ciently tense ; the  blocks  are  sustained  between  two  transverse  bars,  called  gage-bars,  and  are  adowed 
to  remain  between  the  blades  to  give  them  additional  firmness. 

The  traverse  of  the  saw-frame  is  given  by  a jointed  connecting-rod,  attached  by  an  adjustable  loop  to 
a long  vibrating  pendulum,  that  is  put  in  motion  by  a pair  of  connecting-rods,  placed  one  over  the  other, 
and  leading  from  two  cranks  driven  by  the  engine.  a11  three  connecting-rods  admit  of  vertical  adjust- 


MARBLE-SAWING  MACHINERY. 


327 


ment  on  the  pendulum.  The  connecting-rod  of  the  saw-frame  is  placed  intermediately  between  the 
other  two,  but  its  exact  position  is  regulated  by  the  height  at  which  the  saws  are  working,  as  it  is  sus- 
pended by  a chain  and  counterpoise  weight,  which  allow  it  to  descend  gradually  downwards  on  the 
pendulum  with  the  progress  of  the  cut,  so  as  always  to  keep  the  connecting-rod  nearly  horizontal. 

In  the  London  Marble  Works  four  of  these  sawing-machines  of  different  sizes  are  grouped  together, 
with  the  driving-shaft  and  pendulums  in  the  middle,  and  so  arranged  that  each  pair  of  saw-frames 
reciprocate  in  opposite  directions  at  the  same  time,  in  order  to  balance  the  weight,  and  reduce  the 
vibration. 

Another  mode  of  traversing  the  saw-frame  sometimes  adopted,  is  by  means  of  a vertical  frame  than 
is  reciprocated  horizontally  on  slides,  and  the  connecting-rod,  instead  of  being  jointed,  is  fixed  rigidly  to 
the  saw-frame,  and  slides  upon  a vertical  rod.  Various  other  unimportant  modifications  in  the  construe 
tion  of  the  machines  are  also  adopted. 

One  of  the  most  difficult  points  in  the  application  of  these  machines,  was  found  to  be  the  supplying 
of  the  sand  and  water  mechanically  to  the  whole  of  the  cuts  at  the  same  time.  This  is  now  success- 
fully effected  by  the  following  arrangement.  Above  the  block  of  marble  to  be  sawn  is  fixed  a water- 
cistern,  or  trough,  extending  across  the  whole  width  of  the  frame,  and  measuring  about  1 'foot  wide,  and 
1 foot  deep ; about  20  small  cocks  are  arranged  along  each  side  of  the  cistern,  and  a small  but  constant 
stream  from  each  of  the  cocks  is  received  beneath  in  a little  box ; a sloping  channel  leads  from  every 
box  across  the  bottom  of  a trough  filled  with  sand,  which  mingles  with  the  water,  and  flows  out  in 
separate  streams,  that  are  conducted  to  each  of  the  saw-cuts.  In  the  first  construction  of  this  appara- 
tus for  the  feed,  the  sloping  channels  were  led  straight  across  the  bottom  of  the  sand-trough,  but  it  was 
then  found  that  the  water  excavated  little  tunnels  in  the  sand,  through  which  it  flowed  without  carrying 
the  sand  down.  This  difficulty  was  overcome  by  leading  the  channels  across  the  bottom  of  the  trough 
in  a curved  line,  when  viewed  in  plan.  The  form  of  the  channels  is  shown  in  Fig.  2710,  which  repre 
sents  four  channels  cut  across  the  middle  of  their  length,  to  show  2710. 

their  section,  from  which  it  will  be  seen  that  the  channels  are  made 
as  a series  of  Gothic  shaped  tunnels,  supported  only  on  one  side,  and 
open  on  the  other  for  the  admission  of  the  sand  ; the  water  flows 
through  these  tunnels,  and  continually  washing  against  the  convex 
side  of  the  channel,  undermines  the  sand,  which  falls  into  the  water 
and  is  carried  down : to  assist  this  action  the  attendant  occasionally 
stirs  up  the  sand  to  loosen  it.  There  is  a sand-trough  and  set  of 
channels  on  each  side  of  the  water  cistern,  so  that  every  saw-cut  re- 
ceives two  streams  of  sand  and  water  in  the  course  of  its  length. 

The  saws  having  been  adjusted  to  the  proper  distances  for  the  required  slabs,  the  saw-frame  is  raised 
by  means  of  a windlass  and  the  suspended  chains  attached  to  the  vertical  frames,  and  the  block  of 
marble  to  be  sawn  is  mounted  upon  a low  carriage,  and  drawn  into  its  position  beneath  the  saws,  and 
adjusted  by  wedges.  The  saws  are  then  lowered  until  they  rest  upon  the  block,  the  counterpoise 
weights  are  adjusted,  and  the  mixed  sand  and  water  allowed  to  run  upon  the  saw-blades,  which  are  put 
in  motion  by  attaching  the  connecting-rod  to  the  pendulum.  The  sawing  then  proceeds  mechanically 
until  the  block  is  divided  into  slabs,  the  weight  of  the  saw-frame  and  connecting-rod  causing  them 
gradually  to  descend  with  the  progress  of  the  cutting. 

To  allow  the  sand  and  water  to  flow  readily  beneath  the  edges  of  the  saw-blades,  it  is  desirable 
that  the  horizontal  frame  should  be  slightly  lifted  at  the  end  of  each  stroke.  This  is  effected  by  making 
the  lower  edges  of  the  frame,  which  bear  upon  the  guide-pulleys,  straight  for  nearly  the  full  length  of 
the  stroke,  but  with  a short  portion  at  each  end  made  as  an  inclined  plane,  which  on  passing  over  the 
guide-pulleys  lifts  the  frame  just  sufficiently  to  allow  the  feed  to  flow  beneath  the  saws. 

For  cutting  slabs  of  marble  into  narrow  pieces,  such  as  shelves,  and  which  is  effected  by  hand  with 
grub-saws,  a machine  called  a ripping  bed  is  employed,  in  which  as  many  cuts  as  may  be  required  in 
the  one  slab  are  effected  simultaneously,  by  an  equal  number  of  circular  saws  with  smooth  edges,  re- 
volving vertically,  and  fed,  as  usual,  with  sand  and  water.  This  machine  consists  of  a bench  about  12 
or  14  feet  long,  6 or  7 wide,  and  about  2 feet  6 inches  high  ; upon  the  top  of  the  bench  is  fixed  two  rails, 
upon  which  a platform,  mounted  on  pulleys,  is  drawn  slowly  forward  by  a weight.  The  horizontal  axis 
carrying  the  saws  revolves  about  9 inches  above  the  platform,  and  to  insure  the  rotation  of  the  saws, 
the  axis  is  provided  with  a projecting  rjjb  or  feather  extending  its  whole  length.  The  saws  are  made 
as  circular  plates,  about  17  inches  diamener  when  new.  The  saws,  or  cutters,  are  clamped  between  two 
collars  about  6 inches  diameter,  fitted  so  as  to  slide  upon  the  spindle,  and  be  retained  at  any  part  of  its 
length  by  side  screws. 

The  saws  having  been  adjusted  to  the  required  distances  for  the  widths  of  the  slips  to  be  cut,  and 
fixed  by  the  side  screws,  the  slab  of  marble  is  imbedded  in  sand  upon  the  platform,  and  the  edge  of 
every  saw  is  surrounded  on  one  side  with  a small  heap  of  moist  sand.  The  saws  are  then  set  in  mo- 
tion, so  as  to  cut  upwards,  and  the  platform  is  slowly  traversed  under  the  saws  by  the  weight,  which 
keeps  the  slab  of  marble  constantly  pressing  against  the  edges  of  the  revolving  saws,  until  the  slab  is 
entirely  divided  into  slips. 

"When  the  saws  are  new,  they  nearly  reach  the  upper  surface  of  the  platform,  and  a moderate  thick- 
ness of  sand,  just  sufficient  to  form  a bed  for  the  slab  of  marble,  raises  it  high  enough  to  allow  the 
6aws  to  pass  entirely  through  the  thickness  of  the  slab ; but  as  the  saws  are  reduced  in  diameter  by 
wear,  it  becomes  necessary  to  employ  a thicker  layer  of  sand,  or  to  use  a supplementary  platform  to 
raise  the  slab  to  the  proper  height.  To  avoid  this  Inconvenience,  an  improvement  lias  been  recently 
introduced  by  mounting  the  axis  of  the  saws  in  a vertical  slide,  which  is  adjusted  by  a rack  aud  pinion, 
so  as  to  allow  the  edges  of  the  saw  to  penetrate  exactly  to  the  required  depth. 

Circular  pieces  of  marble,  such  as  the  tops  of  round  tables,  and  other  objects,  from  about  6 feet  diam 
eter  to  the  small  circular  dots  sometimes  used  in  tesselated  pavements,  are  sawn  to  the  circular  form 


328 


MARBLE-SAWING  MACHINERY. 


by  means  of  revolving  cylindrical  cutters,  constructed  on  much  the  same  principle  as  the  crown  saws 
for  wood.  The  slab  to  be  sawn  is  placed  horizontally  on  a bench,  and  the  axis  of  the  machine  works 
vertically  above  it  in  cylindrical  bearings,  which  allow  the  spindle  to  slide  through  them,  so  as  to  be 
elevated  or  depressed  according  to  circumstances.  The  spindle  is  suspended  at  the  upper  end  by 
a swing-collar  attached  to  a connecting-rod,  that  is  jointed  to  the  middle  of  a horizontal  lever. 
The  weight  of  the  vertical  rod  and  cutter  supplies  the  pressure  for  the  cutting,  and  the  whole  ii 
raised  for  the  admission  of  the  work  by  a rope  attached  to  the  end  of  the  lever,  and  passed  over 
a pulley. 

For  circles  of  small  diameter,  the  cutters  are  made  as  hollow  cylinders  of  sheet-iron,  of  various 
diameters,  and  each  attached  by  screws  to  a circular  disk  of  cast-iron,”  as  shown  in  section  in  Fig.  2711. 
The  cutter  is  screwed  on  the  lower  end  of  the  spindle,  just  the  same  as  a chuck  on  a lathe  mandrel, 
except  that  the  spindle  is  placed  vertical  instead  of  horizontal.  To  insure  free  access  for  the  sand  and 
water  beneath  the  cutter,  one  or  two  notches,  about  three-quarters  of  an  inch  wide,  are  generally  made 
in  the  lower  edge. 

For  large  circles,  the  apparatus  is  made  strong,  and 
the  vertical  spindle  is  fitted  at  its  lower  extremity  with  a 
circular  plate,  to  which  is  bolted  a wooden  cross,  shown 
in  plan  in  Fig.  2711,  and  in  elevation  in  Fig.  2713;  the 
cross  has  radial  grooves  about  18  inches  long,  near  the 
outer  extremities  of  the  four  arms.  The  cutters  consist 
of  detached  plates  of  iron,  from  G to  18  inches  long,  of 
various  widths,  according  to  the  thickness  of  the  work. 

The  cutters  are  curved  as  segments  of  a cylinder,  of  the 
particular  diameter  they  are  required  to  cut,  and  are  each 
riveted  to  a clamp  that  passes  through  the  radial  groove, 
and  is  retained  by  a wedge.  The  number  and  length  of 
the  cutters  is  solely  a matter  of  convenience,  as  a single  cut- 
ter, when  put  in  rotation,  would  make  a circular  groove, 
and  several  cutters  are  only  employed  in  order  to  expedite 
the  process.  But  eveiy  different  diameter  requires  a 
different  curve  in  the  cutters,  and  which  must  all  be  placed 
at  exactly  the  proper  distance  from  the  centre  of  rotation. 

The  horizontal  bench  upon  which  the  marble  is  laid,  is 
generally  a temporary  structure,  adjusted  to  suit  the 
thickness  of  the  object  to  be  sawm.  Works  of  large  di- 
ameter are  seldom  more  than  one  or  two  inches  thick,  but 
those  of  small  diameter  are  frequently  much  thicker,  and 
sometimes  three  or  four  thin  pieces  are  cemented  upon 
each  other,  and  cut  at  one  operation.  Short  pillars  are 
sometimes  sawn  out  of  an  irregular  block  in  a similar 
manner,  instead  of  being  chipped  and  turned.  And  it 
has  been  proposed  that  long  cylinders,  and  tubes  of  stone, 
should  be  cut  with  cylinders  of  sheet-iron  of  correspond- 
ing length,  put  in  rotation,  and  supplied  with  sand  and  water. 

Marble  works  of  small  and  medium  size,  are  ground  flat  upon  horizontal  revolving  laps,  after  the 
same  general  method  as  that  pursued  by  the  lapidary,  but  with  a proportionate  increase  of  size  in  the 
lap,  which  is  supplied  as  usual  with  sand  and  water.  The  laps  for  marble  works  are  made  as  circular 
plates  of  cast-iron,  from  fi  to  14  feet  diameter,  and  about  3 inches  thick  when  new;  they  are  mounted 
in  various  ways  upon  vertical  spindles,  so  that  their  upper  sides  or  faces  may  be  about  2 feet  6 inches 
above  the  ground.  Across  the  face  of  the  lap,  or,  as  it  is  called,  the  sanding  plate,  one  or  two  strong 
square  bars  of  wood,  faced  with  iron,  are  fixed  so  that  their  lower  sides  may  just  avoid  touching  the 
face  of  the  lap,  and  their  edges  present  perpendicular  faces,  from  5 to  6 inches  high,  at  right  angles  to 
the  face  of  the  lap.  The  wooden  bars  serve  as  stops  to  prevent  the  work  from  being  carried  round  by 
the  lap,  and  also  as  guides  to  insure  the  work  being  ground  square. 

The  piece  of  marble  is  laid  flat  upon  the  lap,  with  the  face  to  be  ground  downwards,  and  the  side  of 
the  work  in  contact  with  the  guide-bar.  Water  is  allowed  toSdrip  upon  the  plate  from  a cistern  fixed 
above,  and  small  quantities  of  sand  are  thrown  on  as  required.  During  the  progress  of  the  work  the 
workman  leans  upon  the  marble,  the  position  of  which  is  shifted  occasionally  to  expose  both  the  work 
and  the  lap  to  an  equal  amount  of  wear,  and  prevent  the  formation  of  ridges,  but  which  is  less  likely 
to  occur  with  iron  laps  used  for  grinding  large  surfaces  of  marble,  than  when  small  objects  are  applied 
upon  lead  laps,  as  by  the  lapidary  and  mechanician. 

The  one  side  of  the  marble  having  been  reduced  to  a flat  surface,  the  work  is  turned  over  to  grind 
the  adjoining  face,  and  the  first  face  is  held  in  contact  with  the  perpendicular  side  of  the  guide-bar,  in 
order  to  present  the  second  face  of  the  work  to  the  lap  exactly  at  right  angles  to  the  first.  When  two 
pieces  of  similar  size  are  to  be  ground  each  on  the  one  face  and  two  edges,  as  for  the  upright  sides  of 
a chimney-piece,  the  two  pieces  of  marble  are  cemented  together  back  to  back  with  plaster  of  Paris, 
(a  process  that  is  called  lining^)  and  the  pair  are  ground  as  one  piece  on  all  four  faces ; in  this  case  the 
flat  sides  are  first  ground  parallel  to  each  other,  or  of  equal  thickness  on  the  two  edges,  and  the  latter 
are  then  ground  square  by  placing  the  sides  in  contact  with  the  guide-bar. 

When  the  lap  is  of  moderate  size,  one  guide-bar  only  is  employed,  and  it  is  fixed  across  the  diameter 
of  the  plate,  whicli  then  allows  of  two  workmen  being  employed  on  the  opposite  sides ; but  large 
grinding  plates  sometimes  have  two  or  three  bars  placed  at  equal  distances  across  the  face,  and  four  or 
six  workmen  may  then  be  employed  at  the  same  time  upon  separate  pieces  of  marble. 


MARBLE-SAWING  MACHINERY. 


329 


The  sand  and  water  are  continually  thrown  from  the  lap  by  the  centrifugal  force,  and  the  large  siz«. 
of  the  works  sometimes  applied  prevents  the  use  of  a rim  standing  up  above  the  level  of  the  lap  te 
catch  the  wet,  as  used  by  lapidaries.  Every  workman,  therefore,  stands  within  a kind  of  trough  like  a 
box,  about  three  feet  high,  without  a top  or  back ; the  troughs  serve  as  a protection  to  the  workmen, 
who  would  otherwise  be  exposed  to  a continued  shower  of  sand  and  water. 

The  surfaces  of  large  slabs  are  in  some  cases  ground  upon  revolving  plates ; in  this  case  the  axis  is 
placed  entirely  beneath  the  surface  of  the  plate,  somewhat  as  in  Fig.  2714,  and  the  slab  is  traversed 
by  two  men  over  the  face  of  the  plate  to  grind  it  equally,  but  the  machine  next  described  is  better 
adapted  for  large  slabs  of  marble  requiring  tolerable  accuracy. 

Large  slabs  of  marble  and  stone  are  ground  very  accurately  in  a machine  patented  by  Mr.  Tulloch 
and  called  a grinding  bed.  In  this  machine,  represented  in  Fig.  2714,  the  slab  to  be  ground  is  placed 


2714. 


horizontally  upon  a moving  bed,  and  the  grinding  is  effected  by  sand  and  water,  by  means  of  t large 
flat  plate  of  iron  resting  upon  the  surface  of  the  slab.  The  two  surfaces  are  traversed  over  each  other 
with  a compound  motion,  partly  eccentric  and  partly  rectilinear,  so  as  continually  to  change  their  rela- 
tive positions.  The  machine  consists  of  a frame  about  9 feet  long,  6 feet  wide,  and  8 feet  high ; about 
2 feet  from  the  ground  is  mounted  a platform,  that  is  very  slowly  reciprocated  horizontally  for  a dis- 
tance of  from  1 to  2 feet,  according  to  the  size  of  the  slab,  by  means  of  a rack  and  pinion  placed  be- 
neath, and  worked  alternately  in  both  directions. 

Above  the  platform  are  fixed  vertically  two  revolving  shafts,  having  at  their  upper  extremities  hori- 
zontal toothed  wheels  of  equal  diameter,  which  are  driven  by  means  of  a central  toothed  wheel  keyed 
on  the  driving-shaft.  The  two  vertical  shafts  are  thus  made  to  revolve  at  equal  velocity,  or  turn  for 
turn,  and  to  their  lower  ends  are  attached  two  equal  cranks,  placed  parallel  to  each  other ; the  extremi- 
ties of  which,  therefore,  describe  equal  circles  in  the  same  direction.  To  these  cranks  the  iron  grinding 
plate  or  runner  is  connected  by  pivots  fitting  two  sockets  placed  upon  the  central  line  of  the  plate. 
The  cranks  are  made  with  radial  grooves,  so  that  the  pivots  can  be  fixed  by  wedges  at  any  distance 
from  the  centre  of  the  cranks.  When  the  machine  is  put  in  motion,  the  grinding  plate  is  thus  swung 
round  bodily  in  a horizontal  circle  of  the  same  diameter  as  the  throw  of  the  cranks,  which  is  usually 
about  12  inches,  and  consequently  every  portion  of  the  surface  of  the  grinding  plate  would  describe  a 
circle  upon  the  surface  of  the  slab  being  ground,  if  the  latter  were  stationary.  But  by  the  slow  recti- 
linear movement  of  the  platform,  the  slab  is  continually  shifted  beneath  the  plate,  so  as  to  place  the 
circles,  or  rather  the  cycloids,  in  a different  position  ; and  it  is  only  after  many  revolutions  of  the  cranks 
that  the  same  points  of  the  surfaces  of  the  grinding  plate  and  slab  are  a second  time  brought  in 
contact. 

The  grinding  plate  is  raised  for  the  admission  of  the  slab  by  means  of  four  chains  suspended  from  a 


330 


MARINE  STEAM-ENGINE. 


double  lever,  and  attached  to  the  arms  of  a cross  secured  to  the  centre  of  the  upper  surface  of  the  plate, 
■which  is  thus  lifted  almost  like  a scale  pan.  For  slabs  that  are  much  thicker  or  thinner  than  usual,  the 
principal  adjustment  is  obtained  by  the  removal  or  addition  of  separate  beds,  or  loose  boards,  laid  upon 
the  platform  to  support  tire  slab  at  the  proper  height.  Slabs  that  are  too  large  to  be  ground  over  the 
whole  surface  at  the  one  operation,  are  shifted  once  or  twice  during  the  grinding,  to  expose  the  surface 
equally  to  the  action  of  the  grinding  plate. 

The  necessary  pressure  for  grinding,  is  given  by  the  weight  of  the  horizontal  plate,  which  is  sup- 
ported almost  entirely  by  the  work,  as  the  pivots  of  the  cranks  merely  enter  the  sockets,  and  allow  the 
plate  to  descend  when  left  to  itself.  For  delicate  works  a counterpoise  weight  is  attached  to  the 
double  lever  so  as  to  regulate  the  pressure  on  the  work. 

The  sand  and  water  are  applied  to  the  grinding  surfaces  in  much  the  same  manner  as  in  the  iron 
runners  used  by  hand,  previously  described.  The  grinding  plate  is  made  on  the  upper  side  with  a 
raised  rim  like  a tray,  and  the  bottom  of  the  tray  is  perforated  with  numerous  holes  about  1J  inch 
diameter  arranged  at  equal  distances  apart.  The  sand  and  water  are  thrown  into  the  tray  at  intervals 
in  small  quantifies,  and  run  through  the  holes  and  between  the  surfaces  of  the  slab  and  grinding  plate, 
which  are  thus  uniformly  supplied  with  the  feed  that  ultimately  makes  its  escape  around  the  edges  of 
the  grinding  plate.  . 

Various  qualities  of  sand  may  be  employed  according  to  the  perfection  of  surface  required,  and  very 
flat  surfaces  are  produced  by  this  machine.  The  grounding  or  smoothing  of  the  best  works  is  effected 
with  a succession  of  fine  emeries,  with  which  the  surfaces  may  be  made  very  smooth,  and  almost 
polished ; but  from  motives  of  economy,  the  grounding  of  ordinary  works  is  more  frequently  completed 
by  hand,  with  grit-stone  and  snake-stone,  before  the  work  is  finally  polished  on  another  machine. 

Eectilinear  mouldings  in  marble  are  wrought  by  machinery  in  a manner  altogether  different  from  the 
hand  process  of  working  mouldings,  in  which,  as  previously  described,  nearly  the  whole  of  the  material 
is  removed  with  chipping  chisels,  and  the  surfaces  of  the  mouldings  are  only  smoothed  by  abrasion.  In 
the  machine  process,  on  the  contrary,  the  whole  of  the  material  is  removed  with  revolving  grinders,  by 
which  the  work  is  reduced  to  the  required  form,  and  left  smooth  at  the  one  operation. 

The  machine  for  working  rectilinear  moulding,  or  as  it  is  called  the  moulding  bed , closely  resembles 
in  its  construction  the  ripping  bed  described  previously,  except  that  the  frame  carrying  the  revolving 
grinders  is  provided  with  the  power  of  vertical  adjustment  by  a screw  placed  beneath,  in  order  to  raise 
the  grinder  to  the  proper  height  to  suit  the  thickness  of  the  marble,  and  that  instead  of  the  grinders 
being  thin  circular  sheets  of  iron,  they  consist  of  solid  cylinders  of  cast-iron  turned  to  the  counterpart 
forms  of  the  required  mouldings.  Indeed  the  ordinary  ripping  bed  is  occasionally  used  for  working 
mouldings  on  large  works,  and  when  it  is  provided  with  the  vertical  adjustment  for  elevating  or 
depressing  the  axis  to  any  required  position,  the  ripping  bed  is  equally  suitable  for  working  mouldings 
but  as  the  latter  are  in  general  only  required  on  slips  of  marble  only  a few  inches  wide,  a narrow  ma- 
chine is  usually  employed  for  the  purpose. 


MARINE  ENGINES,  Steam.  Marine  engines  may  be  divided  into  two  broad  classes,  viz:  beam  01 
lever  engines,  and  direct  acting  engines.  These  may  be  either  condensing  or  non-conaensing  engines , 
the  former,  however,  are  the  most  extensively  used.  With  the  exception  of  small  screw-propellers  and 
tow-boats,  and  steamers  on  the  western  waters,  the  condensing  or  low-pressure  engines  are  almost 


in.  -urn 


MARINE  STEAM  ENGINE. 


331 


•wholly  used  in  this  country.  The  terms  high  and  low  pressure  are  in  general  used  to  designate  respeo 
tively  the  non-condensing  and  condensing  engine,  although  the  terms  are  not  in  truth  sufficiently  distinc* 
tive,  as  the  condensing  engine  may  he,  and  in  connection  with  the  expansion  principle,  frequently  is, 
used  with  what  may  he  called  high  steam.  What  would  he  considered  in  this  country  a low  pressure 
steam,  say  40  lhs.  to  the  inch,  would  be  considered  in  England  as  high-pressure. 

These  two  classes  admit  of  subdivision  into  many  varieties,  hut  may,  for  all  practical  purposes,  he 
confined  to  the  following  system  of  arrangement : 


Beam-engine, 


Side-lever. 


r 


Direct-acting  engine...  - 


Vertical 


Oscillating, 

Rotatory. 


Square  engine. 

Steeple  engine. 

Trunk  engine. 

Gorgon. 

F airbairn. 

Double-cylinder  engine. 


The  Direct-Acting  Engines  differ  from  the  beam-engine  simply  in  the  method  of  taking  the  power 
from  the  piston-rod.  In  the  one  the  head  of  the  piston-rod  is  connected  either  directly  with  the  crank, 
or  by  means  of  a connecting-rod  or  rods ; in  the  other,  the  working-beam  or  great  lever,  vibrating  on 
its  centre,  receives  at  one  end  the  power  from  the  piston-rod  through  the  modifying  action  of  “ parallel 
motion  ” rods,  or  plain  slides,  and  communicates  it  to  the  crank-shaft  by  a connecting  rod  attached  to  its 
other  extremity. 

The  Side-Lever  Engine  is  a modification  of  the 


of  the  marine  engine,  this  form  of  engine  is  ordinarily  understood,  unless  otherwise  specified.  For  al- 
though other  forms  of  engines  may  become  of  as  much  importance  to  steam  navigation,  certain  it  is 
that  at  this  day  no  engine  has  been  found  to  equal  it  in  point  of  general  efficiency.  The  description  of 
engine  called  oscillating  is,  however,  coming  into  favor,  from  other  considerations  to  be  noticed  subse- 
quently. 

I’assing  to  the  varieties  of  the  direct-acting  engine,  already  defined,  we  find  that  the  attempt  to  pro- 
duce engines  more  compact  and  of  less  weight  and  bulk,  has  extended  the  examples  of  this  class  of  en- 
gines into  an  almost  endless  variety  of  modifications.  Scarcely  any  two  are  alike ; and  in  our  classifi- 
cation above,  we  have  retained  only  tnose  whose  features  are  sufficiently  distinctive  to  admit  of  general- 
ization. Some  engineers  regard  those  engines  only  as  direct-acting,  where  the  piston  itself  seizes  the 
crank,  without  the  intervention  of  any  connecting-rods.  Such  are  the  trunk  and  oscillating  engines ; 
but  the  classification  we  have  used  is  simple,  and  sufficiently  minute  for  all  purposes. 

In  the  first  species  of  the  direct-acting  engine,  namely,  the  vertical,  the  paddle-shaft  is  directly  over 
the  axis  of  the  cylinder ; but  the  method  has  the  disadvantage  of  admitting  only  a short  stroke  and  a 
short  connecting-rod,  and  requires  that  the  height  of  the  axis  above  the  bottom  of  the  cylinder  should 
be  at  least  three  times  the  length  of  the  stroke.  Thus  one  of  the  extremes,  too  short  a connecting-rod, 
too  short  a stroke,  or  a paddle-axis  too  high  above  the  floor  of  the  vessel  is  incurred. 

1c  this  country  the  square  engine,  the  first  variety  of  the  vertical  engine,  has  its  cylinder  immedi- 


332 


MARINE  STEAM  ENGINE. 


ately  over  the  axis  and  cranks,  to  which  motion  is  communicated  from  the  cross-head  of  the  piston  bj 
means  of  side-rods,  the  air-pump  being  worked  by  a separate  beam  connected  with  the  cross-head  by  pro- 
per links  ; but  this  is  equally  unsuited  to  sea-going  steamers  on  account  of  the  height  of  the  cylindei 
above  the  paddle-shaft. 

To  obtain  the  object  sought  without  incurring  these  evils,  many  descriptions  of  engine  have  heel 
contrived ; among  others  the  steeple  engine,  so  called,  where  the  piston-rod  is  made  forked,  so  as,  pass- 
ing round  the  shaft,  to  rise  above  it  to  a considerable  height,  from  which  again  descends  the  connecting- 
rod  to  the  crank.  Figs.  2716  to  2721  illustrate  the  principle.  The  top  of  the  piston-rod  carries  a four- 
armed cross-head  h k,  on  each  end  of  which  stands  a pillar  hh ; these  four  pillars  again  unite  in  another 
quadruple  cross-head,  sustained  upright  by  a vertical  guide  ; and  it  is  from  this  summit  that  a connect 
ing-rod  descends  to  the  crank  K. 


After  passing  through  a great  variety  of  phases  the  steeple  engine  appears  to  have  settled  down  mt« 
the  two  following  shapes.  In  figs  2720  and  2721  the  piston-rod  is  seen  united  to  a triangular  frame, 
from  the  apex  of  which  the  connecting-rod  descends  to  the  crank.  In  fig.  2722  this  frame  is  shown  to 
be  square,  and  fig.  2719  is  the  side  view  of  both  varieties.  2723  2724 

Another  method  of  accomplishing  the  direct  connec- 
tion without  encumherirlg  the  deck  is  called  the  trunk 
engine,.  The  axis  is  placed  at  the  height  of  half  the 
stroke,  or  more,  above  the  cylinder,  and  a connecting- 
rod  unites  immediately  the  crank-pin  with  the  centre  of 
the  piston.  In  this  way  the  connecting-rod,  passing 
through  the  top  of  the  cylinder,  would  allow  the  steam 
to  escape  but  for  a large  trunk  or  casing  with  which  it 

is  surrounded,  and  which,  passing  through  a chasm  of  large  area  conceived  to 
be  steam-tight,  rises  and  falls  wTith  the  piston  to  which  it  is  attached.  In  fig. 

2724,  A A is  the  cylinder ; to  its  piston  is  attached  a trunk  B,  which  works 
through  a stuffing  box  in  the  cylinder  cover ; to  the  piston  the  connecting-rod 
c c is  attached.  Fig.  2723  represents  the  top  of  the  cylinder  A A,  with  its 
stuffing-box  and  the  trunk. 

These  engines  were  first  used  for  marine  purposes  with  vertical  cylinders, 
and  were  again  introduced  into  use  by  Penn,  of  Greenwich,  with  horizontal 
cylinders.  The  first  application  of  it  was  to  H.  M.  S.  Encounter,  a vessel  of 
360  hoi'se-power.  The  cylinders  are  horizontal,  and  connected  at  once  to  the 
screw-shaft.  These  engines  make  between  78  and  80  revolutions  per  minute, 
which  was  sufficient  to  propel  the  ship  about  eleven  knots.  They  were  fitted 
with  locomotive  slides,  and  worked  with  two  eccentrics.  The  air-pumps,  like 
the  cylinders,  were  horizontal ; and  indeed  all  the  parts  of  the  engines  were 
ns  low  as  they  possibly  could  be,  for  the  purpose  of  bringing  the  machinery 


below  the  water  line. 

This  form  of  engine  was  used  by  the  Messrs.  Kemble,  for  the  steamers  “ Pioneer  ” and  “ City  of  Pitts 
ourg.”  In  these  the  cylinders  are  again  brought  back  to  the  original  vertical  position,  and  form,  not- 
withstanding, a most  compact  form  of  engine. 

The  Gordon,  Fairbairn,  and  the  double-cylinder  engines  are  English  varieties  of  direct-acting  engines 
extensively  used  abroad,  but  little  used  in  this  country;  they  deserve  a passing  notice,  as  illustrative 
of  the  efforts  made  to  reduce  the  dimensions  of  marine  engines  within  the  least  possible  limit. 


MARINE  STEAM  ENGINE. 


333 


The  principle  of  construction  of  the  Gorgon  engines  will  be  clearly  seen  by  reference  to  fg.  2725,  which 
represents  a section  of  one  of  such  engines ; and  the  several  parts,  for  simplicity  .sake,  are  represented 


omy  bylines.  Here  AB  CD  represent  the  cylinder,  F is  the  centre  of  the  shaft,  directly  over  the 
middle  of  the  cylinder  ; I E is  a section  of  the  piston ; I H the  piston-rod,  working  steam-tight  in  u 
etuffing-box  at  K ; H G is  the  connecting-rod,  and  G F the  crank  It  is  easily  seen  that  as  the  piston  is 


334 


MARINE  STEAM  ENGINE. 


forced  up  and  down  by  tlie  steam,  the  crank  will  be  made  to  revolve,  and  consequently  cause  the  paddle- 
wheel  to  rotate.  The  remaining  parts  of  the  engine  will  be  readily  understood : L is  the  condenser,  M 
the  air-pump,  N the  hot  well,  a and  b are  the  foot-valve  and  delivery-valves  respectively.  There  are  twc 
particulars  deserving  special  notice  in  this  engine,  viz.  : the  slides  for  admitting  the  steam  and  allowing 
it  to  escape,  and  the  parallel  motion,  or  the  means  of  keeping  the  piston-rod  in  its  vertical  line.  It  is 
observable  that  there  are  four  slides,  viz. : A,  B,  C,  and  D,  two  of  which,  A and  C,  are  for  allowing  tlia 
ingress  of  steam,  and  the  other  two,  B and  D,  for  allowing  it  to  escape  to  the  condenser  L.  The  follow- 
ing is  an  outline  of  the  parallel  motion:  II  0 is  a beam  called  the  “rocking-beam,”  one  end  of  which 


2727 


o ; 


/ 


i 


T 


1 


a 


2728 


,tted  to  the  upper  extremity  H,  of  the  piston-rod.  P Q is  a vertical  frame,  called  the  ‘rocking- 
standard  ; ” the  lower  end  of  this  is  connected  with  some  convenient  point  Q,  about  which  it  can  move, 
and  the  upper  end  P will  therefore  describe  a small  circular  arc  about  Q;  but  this  arc  will  be  so  small 
that  it  may  be  practically  looked  upon  as  a straight  line.  T S is  a bridle-rod,  secured  at  one  end  T to 
the  framework  of  the  engine,  and  at  the  other  to  the  rocking-beam.  If,  now,  these  rods  have  the  pro- 
per proportions,  the  motion  of  H will  be  vertical.  The  rocking-beam  is  continued  along  to  0,  and  the 
air-pump  rod  is  fitted  to  it  by  means  of  the  interme- 
diate rod  R 0.  The  air-pump  rod  is  kept  in  a vertical 
line  by  means  of  guides. 

Fig.  2726  represents  an  outline  of  the  Gorgon 
engine. 

The  chief  peculiarity  of  Fairbairn’s  direct-acting 
engines  is  in  the  parallel  motion,  which  is  somewhat 
similar  to  that  of  the  Gorgon  engines. 

The  dotted  lines,  fig.  2727,  represent  the  Gorgon 
engines.  H P 0 is  the  rocking-beam ; H the  point  to 
which  the  piston-rod  and  connecting-rod  are  attached ; 

P the  point  of  attachment  of  the  rocking-standard ; 
then,  to  construct  Fairbairn’s  parallel  motion,  let  the 
rocking-standard  P Q be  inverted,  as  in  the  figure,  so 
as  to  hang  down  from  a point  Q'  in  the  entablature  of 
the  engine.  In  the  Gorgon  engines,  H P is  prolonged 
to  0,  as  before  described,  and  the  air-pump  is  worked 
from  this  extremity ; but  in  Fairbairn’s  engines  the 
radius-gear  S T will  be  produced  to  some  point  O',  and 
O'  T serves  as  the  beam  for  working  the  air-pump. 

The  steam  is  admitted  and  allowed  to  escape  by 
means  of  a slide-valve,  worked  by  an  eccentric. 

The  four  main  parts  of  each  engine,  viz. : the  cyl- 
inder, slide-valves,  condenser,  and  air-pump,  form  a 
square,  and  thus  occupy  little  space. 

Fig.  2728  represents  in  outline  one  of  the  Fair- 
bairn  engines. 

Maudslay's  Double-Cylinder  Engines.  In  the  fore- 
going direct  engines  the  connecting-rod  is  necessarily 
shorter  than  it  would  have  been  if  side-levers  had  been  used  • and  consequently  the  force  exerted  on  the 


MARINE  STEAM  ENGINE. 


335 


2729 


crank  alters  more  suddenly  as  tlie  motion  is  alternated  from  the  up  to  the  down  stroke,  and  vice  versa , 
than  would  have  been  the  case  had  the  connecting-rod  been  longer. 

Now,  in  most  direct  engines  a long  connecting  rod  is  an  impossibility ; for  the  distance  from  the  shaft 

to  the  bottom  of  the  vessel  being  limited,,  the  depth 
of  the  cylinder,  the  radius  of  the  crank,  and  the 
length  of  the  connecting-rod,  must  all  be  accommo- 
dated to  it.  Messrs.  Maudslay  and  Field  proposed 
to  remedy  it  by  adapting  two  cylinders  to  each  en- 
gine, instead  of  one  ; the  cylinders  having  one  con- 
necting-rod between  them.  In  figs.  2729  and  2730 
A and  A2  are  the  two  cylinders  of  one  of  the  en- 
gines ; a a 2 the  piston-rods ; these  rods  are  connected 
together  at  their  upper  extremities  by  the  cross-piece 

2731 


BCD,  called  (from  its  form)  the  T-plate ; the  lower  end  C of  the  T-plate  is  attached  to  the  connecting- 
rod  C E,  which  again  being  connected  with  the  crank  E F communicates  with  the  paddle-shaft  F.  The 
condenser  G is  underneath  the  cylinders.  It  is  clear  that  if  steam  be  admitted  below  both  pistons  at  the 
same  time,  the  pistons,  in  rising,  will  force  up  the  T-plate,  and  with  it  the  connecting-rod,  &c. ; and 

conversely  these  will  again  descend  as  the 
2732  piston  is  forced  down.  Hence  the  working 

HjHHl  ^ ^ ^ J L part  t^ie  engine  can  be  comprehended. 

It  remains  to  be  shown  how  the  steam  is  ad- 
mitted to  both  cylinders  simultaneously. 
Looking  at  the  plan  of  the  figure,  the  cir- 
cle S represents  a slide-valve,  different  in 
form  from  the  common  slide-valve,  inasmuch 
as  it  is  circular  instead  of  being  semicircular ; 
it  has  one  upper  and  lower  face  in  contact 
with  the  ports  of  the  cylinder  A,  and  one  of 
each  in  contact  with  the  cylinder  A2,  so  that 
as  the  valve  is  raised  or  depressed,  the  steam 
is  admitted  above  or  below  both  pistons  at 
the  same  instant  of  time.  FI  is  the  air- 
pump,  the  bucket  of  which  is  worked  oy 
the  beam  K L moving  round  the  centre  I. 

Fig.  2731  is  an  outline  elevation  of  the 
double-cylinder  engine. 

In  the  oscillating  engines  the  connecting- 
rod  is  altogether  dispensed  with,  the  piston- 
rod  being  attached  directly  to  the  crank;  and 
because  the  piston-rod  from  this  mode  of  at- 
tachment, must  either  be  bent  when  motion 
ensues,  or  the  top  of  the  cylinder  must  move 
laterally,  this  is  provided  for  by  allowing  the 
cylinder  itself  to  vibrate  in  a small  arc,  ef- 
fected by  casting  trunnions  on  to  the  cylinder  near  its  middle,  as  an  axis  upon  which  it  oscillates. 


336 


MARINE  STEAM  ENGINE. 


Fig.  2732  will  give  an  idea  of  the  appearance  of  the  oscillating  engine. 

Many  nautical  men,  and  some  engineers,  have  objected  to  oscillating  engines  on  account  of  the  move- 
ment of  the  cylinder,  which,  they  imagined,  would  become  a formidable  evil  in  the  case  of  a vessel  roll- 
ing heavily  at  sea.  These  objectors  do  not  seem  to  have  remarked  that  the  rolling  of  the  cylinder  is 
neither  dependent  upon,  nor  proportionate  to,  the  rolling  of  the  ship,  but  is  regulated  exclusively  by  the 
movement  of  the  piston ; and  it  is  difficult  to  see  why  a mass  of  matter,  in  the  form  of  a cylinder, 
should  be  more  formidable  or  intractable  in  its  movements  than  a similar  quantity  of  matter  in  the 
form  of  a side-lever,  or  in  any  other  shape  whatever.  It  has  also  been  objected  against  the  oscillating 
engine,  that  the  eduction  passages  are  more  tortuous  tnan  in  common  engines,  so  that  the  steam  gets 
out  of  the  cylinder  less  freely.  We  do  not  believe  such  to  be  the  fact,  if  the  comparison  be  made  with 
the  common  ran  of  marine  engine ; and  in  practice,  no  diminution  of  efficacy  from  this  cause  is  appre- 
ciable. All  the  objections  that  have  been  raised  to  the  oscillating  engine  are  hypothetical ; they  are 
anticipations  of  defects  to  he  found  out  in  large  engines  on  the  oscillating  plan,  and  would  probably  be 
plausible  enough  to  carry  some  weight,  were  it  not  the  fact  that  they  have  been  completely  controverted 
by  experience.  The  remark,  indeed,  is  heard  sometimes  even  yet,  that  the  oscillating  method  may  do 
very  well  for  small  engines,  but  is  of  doubtful  efficacy  for  large  ones.  But  the  definition  of  large  en- 
gines has  been  continually  changed,  to  escape  the  contradiction  experience  afforded,  and  that  size  is,  in 
every  case,  decided  to  be  large,  which  just  exceeds  the  size  of  the  oscillating  engine  last  constructed. 
The  grounds  of  this  skepticism,  however,  are  now  being  fast  contracted;  and,  indeed,  experience  has 
now  demolished  every  objection  that  theory  had  raised.  Some  persons  have  apprehended  that  it  would 
be  difficult  in  large  oscillating  engines  to  obtain  sufficient  surface  of  trunnion  to  prevent  the  trunnions 
from  heating;  yet  we  have  never  been  able  to  learn  that  any  heating  of  those  bearings  has  been  found 
to  occur  in  practice,  and  it  appears  probable  that  any  such  disposition  would  be  resisted  by  the  cooling 
effect  of  the  steam  passing  through  them,  which,  though  hot,  is  of  greatly  inferior  temperature  to  that 
of  a hot  bearing.  It  does  not  appear  to  us,  however,  that  the  trunnions  may  not  be  made  with  any 
amount  of  surface  that  is  thought  desirable,  but  we  believe  the  proportion  adopted  by  Messrs.  Penn  have 
been  found  adequate,  and  are  generally  adopted  in  this  country. 

Rotatory  Engines  are  engines  for  obtaining  a motion  round  an  axis  by  the  direct  action  of  the  steam, 
without  involving  the  necessity  of  reciprocation.  Some  of  them  operate  on  the  principle  of  reaction  of 
which  the  engines  of  Avery  and  others  may  be  taken  as  specimens ; others  operate  on  the  principle 
of  impulse;  a third  kind  trusts  to  the  intervention  of  some  liquid  to  produce  the  desired  effect,  as  in 
the  mercury  engine  of  Watt  and  the  wheel  of  Amonton ; while  in  the  fourth  class  the  piston  moves  in  a 
circle  round  the  axis.  It  is  impossible  to  give  any  enumeration  even  of  the  numberless  schemes  for 
rotatory  engines  that  have  at  various  times  been  projected ; but  none  of  them  have  been  applied  with 
any  prospect  of  success  to  the  purposes  of  navigation,  and  in  their  present  state,  need  scarcely  be  ranked 
as  marine  engines. 

MARINE  STEAM-ENGINE,  of  one  hundred  and  forty-five  horse-power.  By  Caird  & Co.,  Greenock 
The  following  figures  illustrate  very  fully  the  form  and  construction  of  marine  engines  made  by  Messrs. 
Caird  & Co.  of  Greenock,  for  the  steam-packets  Actteon  and  Achilles,  and  also  for  the  royal  mail-packet 
Urgent,  still  plying  betwixt  Liverpool  and  Dublin.  The  drawings  were  made  from  the  engines  of  the 
Actteon,  since  lost  on  the  West-India  station  ; but  in  order  to  render  them  more  complete,  and  therefore 
more  acceptable  to  the  engineer,  the  expansion-geer  subsequently  applied  to  the  engines  of  the  Achilles 
has  been  embodied.  It  may  also  be  remarked,  that  by  proportionally  reducing  the  scale  of  the  draw- 
ings, they  will  be  found  to  agree  in  every  respect,  beyond  a few  very  slight  modifications  of  a technical 
kind,  with  the  larger  class  of  engines,  since  constructed  by  the  same  spirited  firm  for  the  W est-India 
mail-packets  Clyde,  Tay,  Tweed,  and  Teviot,  of  225  horse-power  each  engine.  The  figures  may  thus 
be  regarded  as  giving  a general  representation  of  the  form  of  marine  engines  built  by  a firm  to  whose 
engineering  skill  the  profession  is  indebted  for  a design  of  engine  equally  remarkable  for  elegance  of 
appearance  and  compactness  of  arrangement.  In  lightness  of  material  it  is  no  doubt  surpassed  by  the 
recent  introduction  of  malleable-iron  framing,  and  direct-action;  but  in  the  class  to  which  it  belongs, 
known  as  side-lever  engines,  it  exhibits  a massiveness  of  appearance  and  an  economy  of  weight  which, 
in  combination  with  equal  strength,  has  not  hitherto  been  surpassed. 

Enumeration  of  the  figures. — Fig.  27144-  exhibits  a complete  side  elevation  of  the  engine,  showing  the 
general  design  and  arrangement  of  the  framings,  and  the  relative  positions  and  connections  of  the  work- 
ing parts;  the  valve,  expansion,  and  starting  geer,  parallel  motions,  and  situation  of  the  pumps.  In  this 
view  the  side  of  the  vessel  is  supposed  to  be  removed  and  the  engine  seen  in  situ. 

Fig.  2715  is  a plan  of  the  sole-plate  of  the  engine  with  all  the  parts  removed,  but  showing  the  position 
and  provision  for  fixing  the  steam-cylinder  bottom  and  valve  casing,  the  hot-well,  placed  on  the  top  of 
the  condenser,  the  air-pump,  and  the  soles  of  the  main  framing. 

Fig.  2716  is  a general  plan  of  the  engine,  exhibiting  very  fully  the  starting  and  eccentric  geer,  the 
mode  of  working  the  pumps,  the  direction  and  position  of  the  steam-pipe,  and  mode  of  connecting  the 
diagonal  framing  ; also  the  horizontal  relation  of  the  valve  and  expansion  geer. 

General  description. — Sole-plate  and  condenser. — The  sole-plate,  marked  A A,  with  the  condenser  U, 
consists  of  a single  casting,  double-ribbed  on  the  under  side,  to  give  it  additional  strength  and  rigidity. 
For  facility  of  fitting  it  is  provided  with  fitting-strips  on  its  upper  surface  ; these  are  faced  true  to  re- 
ceive the  soles  of  the  maiji  frame  and  cylinder  bottom,  which  are  fitted  upon  it  metal  to  metal,  aud 
consequently  are  likewise-provided  with  corresponding  fitting-strips,  faced  in  the  same  manner.  The 
sole-plate  is  firmly  secured  to  the  keelsons  of  the  vessel  by  sixteen  strong  malleable-iron  bolts  marked 
a in  the  elevation,  and  the  recesses  for  which  are  similarly  designated  in  the  plan  of  the  sole-plate  The 
middle  of  the  plate,  falling  between  the  two  keelsons,  is  depressed  to  allow  the  condenser  and  its  ap- 
pendages to  stand  lower  in  the  vessel  than  they  otherwise  would,  as  shown  in  the  general  section. 

Framing. — The  main  framing  of  the  engine  consists  of  four  strong  fluted  columns,  cast  pair  and  pair 


Pi  rrr 


■ 


X 


j 


i 


MARINE  STEAM-ENGINE. 


337 


with  their  soles  and  entablatures.  The  soles,  as  above  observed,  are  fitted  upon  the  sole-plate  metal  to 
metal,  and  are  secured  to  it  by  bolts  and  keys,  for  which  snugs  are  cast  on  the  sole- plate.  The  entab- 
lature is  completed  by  two  cross-beams  corresponding  in  form  with  the  sides,  into  which  they  are  fit  tec 
and  secured  by  bolts.  The  form  of  their  cross-section  is  shown  in  the  general  section  of  the  engine. 

The  upper  or  crank  framing  consists  likewise  of  four  columns  cast  pair  and  pair  with  their  soles  and 
entablatures ; but  in  this  case  there  are  no  cross  pieces,  the  two  sides  being  simply  braced  together  by 
two  strong  malleable-iron  stays  marked  c.  One  of  these  passes  between  two  strong  lugs  cast  on  the 
back  columns  near  the  top,  and  the  other  between  the  cheeks  of  the  diagonal  framing  marked  0.  The 
crank-framing  rests  on  the  entablature  of  the  main  frame  to  which  it  is  fitted,  and  secured  by  bolts  and 
by  two  centre  keys  in  each  sole,  driven  on  the  right  and  left  of  a dovetail  snug  cast  on  the  entablature 
of  the  lower  frame,  and  which  enters  a similarly  formed  but  larger  recess  in  the  sole  of  the  upper  frame 
— an  arrangement  which  is  clearly  shown  both  in  the  general  elevation  and  section.  This  framing  is 
further  secured  between  the  ship’s  beams  by  the  strong  stays  b b cast  upon  the  entablatures.  These 
stays  usually  abut  against  cast-iron  face-plates,  bolted  upon  the  paddle-beams  at  the  points  of  contact, 
but  they  are  neither  bolted  nor  otherwise  fixed  to  the  facings,  but  are  left  free  to  slide  vertically  upon 
them  in  obedience  to  any  spring  which  the  vessel  may  have  when  under  way,  and  which  is  often  con- 
siderable, especially  in  a rough  sea.  The  crank-framing  is  also  braced  to  the  steam-cylinder  by  the 
diagonal  framing  C C,  consisting  of  two  strong  parallel  struts  cast  upon  the  inner  columns  of  the  crank- 
framing,  from  which  they  spring.  These  struts  terminate  in  rectangular  flanges,  answering  to  similarly 
formed  projections  cast  on  the  cylinder  on  opposite  sides  of  the  valve-casing  at  top ; and  to  these  they 
are  carefully  fitted  metal  to  metal,  and  secured  by  bolts,  as  partially  shown  at  d in  the  elevation 
and  plan. 

The  principal  use  of  the  crank-framing,  and  that  from  which  it  takes  its  name,  is  to  support  the  c>  ank- 
sliaft.  This  is  accomplished  in  each  of  the  engines  by  two  plummer-blocks,  one  on  each  side  of  the 
crank,  secured  by  bolts  and  keys  on  the  entablatures  of  the  frames.  The  soles  of  the  plummer- 
blocks  are  in  this,  as  in  all  highly  finished  engines  of  the  same  class,  likewise  faced  and  fitted  metal 
to  metal. 

Steam-cylinder. — The  steam-cylinder  E is  cast  open,  and  with  broad  and  strong  flanges  at  both  ends. 
It  is  placed  upon  a separate  bottom  piece,  flanged  like  the  cylinder,  to  allow  of  their  being  bolted  to- 
gether. This  bottom  piece  being  truly  faced,  above  and  below,  is  secured  to  the  sole-plate  of  the 
engine  by  strong  bolts,  and  rusted.  The  lower  end  of  the  cylinder  being  truly  faced  is  similarly 
fitted  upon  and  secured  to  the  upper  flange  of  this  bottom  piece,  so  that  the  whole  may  be  perfectly 
steam-tight. 

The  interior  of  the  cylinder  is  bored  as  truly  as  possible  of  a uniform  inside  diameter  of  sixty-two 
inches.  The  cover  d'  which,  as  will  be  observed  from  the  section,  is  cast  hollow,  is  fitted  by  turning 
and  grinding,  into  the  upper  end  to  nearly  the  depth  of  the  steam-port.  On  the  inside  is  a circular  re- 
cess to  receive  the  heads  of  the  bolts  of  the  junk-ring  of  the  piston  ; and  the  exterior  plate  is  expanded 
by  a strong  flange  to  the  same  diameter  as  the  flange  of  the  cylinder,  to  which  it  is  secured  by  bolts. 
In  the  centre  is  formed  the  stuffing-box  through  which  the  piston-rod  ascends. 

The  projecting  corner  pieces  marked  d are  those  to  which  the  diagonal  framing  is  attached ; they 
are  faced  both  on  their  horizontal  and  vertical  surfaces,  so  that  the  corresponding  flanges,  in  which 
the  struts  of  the  framing  terminate,  may  be  fitted  truly  upon  them.  The  projecting  valve  facings 
are  cast  of  a piece  with  the  cylinder.  These  are  carefully  dressed  and  the  whole  surface  of  both  exactly 
reduced  to  the  same  plane ; and  to  complete  them,  a carefully  finished  facing  of  brass,  but  of  less 
breadth,  (two  inches,)  is  applied  steam-tight  round  each  of  the  ports,  and  projects  on  each  side,  by 
runners  of  a length  corresponding  to  the  length  of  the  ledgings  of  the  valves.  The  outlines  of  these 
facings  are  indicated  in  the  view  above  referred  to,  and  the  transverse  form  in  the  general  section  of 
the  engine. 

The  piston. — The  body  of  the  piston  consists  of  a single  hollow  casting,  strengthened  by  radiating 
feathers,  with  a strong  eye  in  the  centre  to  receive  the  piston-rod.  The  under  side  is  a portion  of  a 
sphere  answering  to  the  curvature  of  the  bottom  of  the  cylinder.  The  upper  side  in  like  manner  is 
convex  to  its  junction  with  the  ring,  which  is  horizontal,  and  corresponds  to  a horizontal  part  round 
the  inside  of  the  cover,  within  which  the  cover  is  a segment  of  a hollow  sphere  of  the  same  radius  as 
the  top  of  the  piston.  By  making  these  parts  of  a curvilinear  section,  they  are  better  secured  from 
rupture  by  changes  of  temperature ; and  the  piston  being  symmetrical  in  its  outlines  with  the  cover  and 
bottom,  the  loss  of  steam  due  to  the  clearance  is  reduced  to  a minimum. 

The  under  side  of  the  piston  only  is  cast  of  a diameter  equal  to  that  of  the  cylinder,  the  deficiency  on 
the  upper  side  being  made  up  by  the  junk-ring.  This  ring  is  fitted  steam-tight,  first  by  turning 
and  subsequently  by  grinding.  Packing-rings,  consisting  of  two  thicknesses,  made  up  of  overlapping 
segments,  are  likewise  fitted  into  their  place  between  the  junk-ring  and  the  flange  corresponding  on 
the  under  side  of  the  piston,  and  are  rendered  steam-tight  by  the  same  means.  The  whole  of  these 
thicknesses,  composing  the  edge  of  the  piston,  are  simultaneously  turned  of  a uniform  diameter,  pre- 
cisely equal  to  the  internal  diameter  of  the  cylinder,  in  which  they  are  intended  to  work  steam-tight ; 
but  as  this  condition  would  endure  only  for  a short  period,  however  carefully  and  exactly  the  fitting 
might  be  effected,  were  no  provision  made  for  compensating  the  wear  incident  to  the  continued  motion 
of  the  piston,  and  especially  under  variations  of  temperature,  as  in  starting,  the  packing-rings  are  ren- 
deied  capable  of  adjusting  their  diameter  to  that  of  the  cylinder,  by  springs  placed  behind  them.  The 
springs  employed  in  this  piston  are  of  a U-form,  placed  vertically,  the  strong  side  bearing  upon  the 
piston,  and  the  elastic  side  against  the  adjacent  ends  of  two  of  the  segments.  The  number  of  springs 
and  segments  is  thus  necessarily  equal,  and  so  arranged  that  every  segment  is  supported  at  each  end 
by  a spring.  By  this  means  the  pisten  is  made  to  work  in  the  cylinder  steam-tight,  and  to  accommo- 
date itself  to  any  slight  variations  due  to  the  contraction  and  expansion  of  the  materials;  and  likewise 
to  compensate  for  wear  of  its  own  circumference  and  that  of  the  cylinder. 

Vol.  II.— 22 


338 


MARINE  STEAM-ENGINE. 


The  junk-ring  is  secured  in  its  place  by  bolts  and  nuts ; the  nuts  are  placed  in  recesses  provided 
for  them  in  the  metal  of  the  piston,  and  the  bolts  are  screwed  into  them  from  the  outside.  The  heads 
thus  project  on  the  surface  of  the  ring,  and  would  come  into  contact,  at  the  end  of  the  up-stroke,  with 
the  cylinder  cover,  but  for  a circular  recess  formed  in  it  for  their  reception,  as  before  noticed. 


MARINE  STEAM-ENGINiE. 


339 


eve  and  the  thickness  of  the  rod  thereby  effectually  binding  the  latter  to  the  piston.  For  convenience 
of  inserting  the  key  a recess  is  left  in  the  upper  plate  of  the  piston,  which  is  afterwards  filled,  to  prevent 
the  steam  gaining  admission  to  the  hollow  interior  of  the  piston. 

Piston  cross-head  and  connections. — The  piston-rod,  ascending  through  a packed  stuffing-box,  is 
inserted  .into  an  eye,  bored  a little  smaller  than  its  own  diameter  in  the  cross-head  I,  equidistant 
from  the  two  extremities ; and  is  then  fixed  by  two  gibs  and  cotter  in  the  usual  manner.  The 
cross,  head  has  two  journals  turned  on  each  of  its  ends,  separated  from  each  other  by  ruffs  of  an  inch 


2715. 


2710. 


>c> 


breadth.  By  these  journals  the  radius-bars  KKand  the  side-rods  J J are  connected  with  the  cross- 
...  ' VJe  side-rods  are  fitted  upon  the  exterior  journals,  and  descend  to  the  corresponding  extrem- 

ities of  the  side  levers  M M,  to  which  they  are  also  flexibly  attached.  Their  connection  at  the 
crossdiead  as  will  be  observed  from  the  elevation,  is  by  solid  eyes  formed  in  the  ends  of  the  rods 
and  bushed,  the  brasses  being  retained  in  their  places  by  the  collars  of  the  cross-head,  with  the  assist- 
ance  o a^ey  rearing  against  the  back  of  the  lower  brass  ; but  the  connection  with  flie  side-levers  is 
effected  differently.  Here  the  brasses  are  placed  within  strong  malleable-iron  straps,  bent  at  the  mb’ 


340 


MARINE  STEAM-ENGINE. 


die  of  their  length  till  their  projecting  ends  fit  closely  upon  the  rectangular  ends  of  the  side-rods,  ii 
which  they  are  secured  by  a gib  and  cotter.  This  species  of  connection,  technically  known  as  the  butt- 
end  and  strap , and  universally  adopted  in  like  circumstances,  provides  for  any  slight  wear  of  the  brasses 
for  should  these  become  too  large,  they  can  be  brought  closer  together  by  driving  the  cotter  more 
tightly,  the  holes  through  which  the  gib  and  cotter  pass  being  so  disposed  in  the  strap  and  butt  that 
the  gib  shall  only  be  in  contact  with  the  ears  of  the  strap  and  the  cotter  with  the  butt  on  its  under 
edge.  The  holes  in  both  strap  and  butt  being  thus  of  greater  breadth  than  the  gib  and  cotter  together, 
the  connection  admits  of  adjustment  to  the  extent  of  the  difference,  and  no  further,  for  then  the  edges 
of  the  holes  being  in  the  same  plane,  the  relative  positions  of  the  strap  and  butt  will  not  be  altered  by 
any  subsequent  action  upon  the  cotter. 

The  side-levers  are  divided  at  their  extremities  at  the  point  of  connection  with  the  side-rods  J J and 
the  links  jj,  which  connect  them  with  the  cross-tail.  The  joints  are  completed  by  strong  malleable- 
iron  pins  which  pass  through  the  jaws  of  the  levers,  and  the  bushes  of  the  straps  which  are  placed  be- 
tween them.  These  centre  pins  are  turned  with  a little  taper  on  the  parts  which  pass  through  the 
levers,  and  the  holes  made  for  their  reception  are  accurately  bored  to  the  same  diameter  and  ground. 
The  studs  are  driven  in  tightly  from  the  outside,  and  secured  in  their  places  by  riveting  at  the  opposite 
extremity. 

Both  levers  are  suspended  upon  the  same  axis  called  the  main  centre,  M',  which  passes  through  and 
is  fixed  in  the  sides  of  the  condenser.  It  will  be  observed  that  the  eye  of  the  lever  is  fitted  with  brasses 
which  can  be  tightened  as  they  wear  by  a pair  of  cotter-keys,  parsing  through  the  boss  and  bearing 
against  the  back  of  the  under  brass.  Inside,  and  bearing  against  the  shoulder  of  the  boss,  is  a ring  of 
malleable  iron,  of  sufficient  breadth  to  cover  the  margin  of  the  eye  to  fully  an  inch  beyond  the  circum- 
ference of  the  brasses,  thereby  preventing  the  lever  from  deviating  inwards:  and  to  prevent  it  from 
sliifting  its  position  outwardly,  a plate  of  the  same  external  diameter  is  applied  by  a strong  bolt  screwed 
into  the  end  of  the  main  centre. 

The  side-levers  are  connected  with  the  connecting-rod  1ST  by  means  of  the  cross-tail  O and  links  jj. 
The  connecting-rod  passes  through  an  eye  at  the  middle  of  its  length,  and  is  fixed  by  two  gibs  and  a 
cotter,  in  the  same  way  as  the  piston-rod  is  attached  to  the  cross-head,  wdiile  the  links  are  connected  in 
the  same  manner  as  the  side-rods,  except  that  the  upper  ends  do  not  admit  of  adjustment,  being  simply 
riveted  in  the  eyes.  The  attachment  of  the  connecting-rod  with  the  crank  is  likewise  by  a butt-end  and 
strap,  the  cotter  of  which  is  tightened  and  maintained  in  its  place  by  a screw  and  nuts.  The  crank-shaft  Q 
rests,  as  before  observed,  on  pedestals  fixed  upon  the  entablature  of  the  crank-framing,  and  is  prevented 
from  moving  on  end  by  ruffs  on  the  outsides  of  the  pillows,  and  by  the  shoulders  of  the  crank-brasses 
inside. 

It  may  be  noticed  that  the  piston-rod,  side-rods,  cross-head,  main  centre-shaft,  cross-tail  and  links, 
connecting-rod,  and  crank-shaft  are  all  formed  of  the  best  malleable  iron,  and  turned  and  pared  to  the 
requisite  forms  and  dimensions. 

The  parallelism  of  the  piston-rod  is  maintained  when  the  piston  is  in  motion,  by  the  two  radius  bars 
Iv  K,  by  the  radius  levers//,  fast  upon  the  ends  of  the  shaft  L,  called  the  parallel-motion  shaft,  and  by 
the  parallel  bar  h.  The  ends  of  the  radius  bars  K K,  on  the  cross-head  are  formed  with  solid  eyes, 
fitted  with  brasses,  the  inner  of  which  are  tightened  by  keys,  in  the  same  manner  a9  those  of  the  side- 
rods  which  are  attached  at  the  same  points.  The  eyes  at  the  opposite  ends,  which  work  upon  studs  in 
the  radius  levers  //  are  formed  in  the  same  way,  but  are  smaller,  and  have  the  outer  brasses  adjusta- 
ble by  screwed-pins  g g.  The  length  of  the  bar  thus  admits  of  slight  adjustment  between  its  centres, 
to  compensate  for  errors  of  workmanship  and  wear  of  the  bushes.  The  parallel  bar  h is  also  attached 
by  a solid  eye  and  stud  to  the  lever  /,  and  admits  of  still  more  extensive  adjustment  at  its  lower  end. 
This  bar,  it  will  be  observed,  is  formed  in  two  pieces,  with  the  contiguous  ends  screwed  right  and  left,  and 
embraced  by  a long  nut  similarly  screwed.  By  turning  this  nut  to  the  right  or  left  it  is  obvious  that  the 
upper  and  lower  ends  will  be  made  to  approach  or  recede,  and  the  distance  between  the  centres  be 
thereby  diminished  or  increased.  The  upper  end  of  the  rod  is  formed  with  a solid  eye  bushed,  and  the 
lower  with  a butt-end  and  strap  in  the  usual  way;  it -is  attached  to  the  exterior  side-lever  by  a malleable- 
iron  stud  inserted  into  a rectangular  eye  formed  in  the  latter. 

The  disposition  of  the  flexible  points  of  these  connections  being  such,  that  in  every  position  of  the 
piston  the  angles  of  the  parallelogram  formed  by  the  part  of  the  side-lever  comprehended  between  the 
stud  of  the  rod  h and  the  junction  of  the  side-rod,  opposed  to  the  radius  bar  K,  and  by  the  parallel 
bar  h and  the  side-rod  J,  shall  change  proportionally,  always  preserving  the  same  constant  ratio,  it  fol- 
lows that  the  piston-rod  cross-head  will  move  constantly  in  the  same  place  and  the  parallelism  of  the 
piston  be  thereby  maintained. 

The  parallel-motion  shaft  L is  supported  by  two  plummer-blocks,  resting  on  the  entablatures  of  the 
small  pillar-framing  D.  This  framing,  called  the  parallel-motion  framing,  consists  of  four  columns, 
cast,  like  the  larger  framings,  pair  and  pair,  with  their  soles  and  entablatures,  and  with  provision  on 
the  latter  for  bolting  and  keying  the  pedestals.  The  soles  rest  upon  oblique  flanges  cast  on  the 
.diagonal  framing  C 0,  to  which  they  are  secured  by  bolts  and  keys. 

The  valves  and  valve-geer. — The  valve  casing  F is  cast  of  a semi-cylindrical  form,  corresponding  to 
the  form  of  the  valves,  which  are  of  that  kind  designated,  in  accordance  with  their  outline,  short 
D-slides. 

The  casing  is  fitted  steam-tight  and  bolted  to  the  side  of  the  cylinder  by  projecting  flanges  cast  on 
both  for  that  purpose ; and  also  to  the  sole-plate  over  the  recess  T',  shown  in  the  general  elevation 
The  flat  side,  as  will  be  observed  from  the  general  section,  occupies  only  about  a third  of  the  whole 
length  equidistant  from  both  ends,  and  is  cast  with  projecting  flanges,  which  are  carefully  fitted  steam- 
tight  between  the  ends  of  the  projecting  faces  of  the  cylinder.  These  faces  thus  project  inside,  but 
are  concealed  by  the  circular  part  of  the  casing,  in  which,  it  will  be  observed,  when  the  cover  is  applied, 
there  is  no  communication  with  the  external  atmosphere ; through  the  passages  T it  communicates 


MARINE  STEAM-ENGINE. 


341 


with  the  condenser  U,  and  through  the  steam-ports  with  the  cylinder.  The  steam-pipe  G likewise  opens 
into  it,  and  a communication  is  thereby  effected  with  the  boilers. 

The  valves,  as  already  noticed,  are  of  the  kind  known  as  short  D-slides.  There  are  two  of  these, 
one  to  each  port  of  the  cylinder.  The  backs  are  turned  truly  circular,  and  the  faces  are  planed  and 
ground  to  the  brass  facings  of  the  ports,  so  that  they  may  slide  upon  them  steam-tight,  and  with 
as  little  friction  as  possible.  They  are  kept  tight  against  the  faces,  and  also  rendered  steam-tight  in 
the  casing  by  hemp  packings,  introduced  through  the  packing-porta  cast  in  the  casing.  These  pack- 
ings are  covered  by  the  packing-rings  which  are  pressed  against  them  by  set  pins  acting  in  nuts 
between  the  packing-rings  and  the  port-covers,  as  fully  shown  in  the  general  section.  These  set  pins 
can  be  tightened  at  pleasure  by  a box  key,  inserted  through  holes  formed  in  the  covers,  and  filled  with 
hollow  plugs,  which  can  be  withdrawn  when  necessary. 

The  planes  forming  the  faces  of  the  valves  are  slightly  less  than  double  the  breadth  of  the  port,  but 
the  circular  parts  are  necessarily  much  larger.  The  faces  and  backs  are  connected  by  strong  dia- 
phragms, through  which  pass  the  ends  of  the  rods  which  couple  the  two  valves  together.  These  rods  are 
turned  to  an  exact  length  between  the  ruffs,  against  which  the  contiguous  sides  of  the  diaphragms  bear, 
and  are  kept  fast  in  their  places  by  nuts  upon  their  protruding  ends.  They  are  stiffened  at  the  middle 
of  their  length  by  a cross-stay.  A strong  stud  is  inserted  downwards  in  the  middle  of  the  diaphragm  of 
the  upper  slide,  and  is  retained  in  its  place  by  a nut  on  the  end  projecting  below.  The  upper  end  is 
formed  with  strong  projecting  lugs,  between  which  the  enlarged  square  end  of  the  valve-spindle  is  re- 
ceived, and  retained  by  a strong  square  pin  which  passes  through  the  lugs  of  the  stud  and  the  end  of 
the  spindle,  thereby  forming  an  inflexible  joint  at  the  point  of  connection. 

The  valve-spindle  passing  through  a packed  stuffing-box  in  the  cover  of  the  valve  casing,  is 
attached  by  means  of  a small  cross-head  and  side  links,  to  the  lever  n.  This  lever  is  fast  upon  the 
transverse  shaft  m,  which  has  its  bearings  immediately  under  those  of  the  parallel-motion  shaft  in  the 
framing  D.  On  the  opposite  end  of  the  lever  n , is  fixed  a weight  q,  sufficiently  heavy  to  counterpoise 
the  weight  of  the  valves..  This  weight  is  connected  with  the  shaft  S,  called  the  starting -shaft , by  two 
small  levers  s s.  These  levers  are  fast  upon  the  shaft  S,  but  are  flexibly  connected  to  the  axis  of  the 
weight  q,  by  two  short  connecting-rods  jointed  to  each.  The  shaft  S is  carried  on  pedestals  fixed  upon 
the  cheeks  of  the  diagonal  framing  0 C,  and  has  a short  lever  crank  keyed  upon  the  end  projecting  to 
the  inside  of  the  engine.  A long  lever  is  fitted  to  this  fixed  piece  by  a hollow  boss  which  passes  upon 
the  tail,  but,  being  required  only  occasionally,  it  is  not  fixed,  that  it  may  be  removed  when  not  in  use, 
and  for  that  reason  it  is  not  shown  in  the  drawings ; but  supposing  it  applied,  it  is  plain  that  by  moving 
it  towards  the  right  and  carrying  the  shaft  S with  it  in  the  same  direction,  the  balance  weight  q will  be 
elevated  and  the  valves  depressed.  The  reverse  action  will  produce  the  reverse  effect  by  again  lower- 
ing the  weight  and  raising  the  valves.  Now,  observing  in  the  section  that  the  lower  steam-port  of  the 
cylinder  is  open  to  communication  with  the  condenser,  and  that  the  upper  port  communicates  only  with 
the  interior  of  the  casing,  if  the  weight  q be  raised  until  the  valves  descend  through  a space  equal  to  the 
breadth  of  the  faces,  it  is  clear  that  the  conditions  will  be  reversed,  and  that  the  upper  port  will  be 
opened  to  communication  with  the  condenser,  through  the  passage  T,  and  that  the  lower  passage  will  be 
shut,  and  the  lower  port  will  communicate  with  the  interior  of  the  casing. 

Upon  one  end  of  the  traverse-shaft  m,  is  a crank-arm,  upon  the  pin  of  which  a gab  formed  in  the 
end  of  the  compound  rod  1 1,  called  the  eccentric  rod,  rests.  This  rod,  which  consists  of  two  bars  of 
malleable  iron  stiffened  by  diagonal  braces,  is  attached  at  its  base  to  the  two  opposite  lugs  of  the 
eccentric  ring  R,  which  works  freely  upon  the  eccentric  embraced  by  it,  and  which  revolves  with  the 
crank-shaft  of  the  engine ; consequently,  supposing  the  crank  to  revolve,  the  rod  1 1 will  at  the  same 
time  receive  an  alternating  rectilineal  motion,  which  being  transferred  to  the  crank-lever  of  the 
traverse-shaft  m,  will  cause  the  ends  of  the  lever  n alternately  to  ascend  and  descend.  But  the  valve- 
spindles  being  attached  to  this  lever,  its  motion  will  be  transferred  to  the  valves,  which  will  thus  be 
made  alternately  to  ascend  and  descend  in  the  same  manner  as  when  a lever  is  applied  by  manual 
strength  to  the  shaft  S.  This  is  the  action  necessary  to  maintain  the  motion  of  the  engine,  as  will  be 
explained. 

As  in  the  case  of  the  piston-rod,  the  parallelism  of  the  valve-spindle  is  maintained  by  means  of  the 
links  o o,  arranged  as  in  the  common  parallel  motion  of  stationary  engines.  The  radius  rods  are  at- 
tached to  opposite  sides  of  a small  framing  consisting  of  two  columns,  fixed  on  the  cover  of  the  valve 
casing,  and  having  their  entablature  p of  a semicircular  form  to  allow  the  cotters  of  the  cross-head 
links  to  pass  when  the  engine  is  in  action. 

The  condenser  and  its  appendages.— The  condenser  U and  the  lower  exhaust  passage  T'  T'  are  cast 
of  a piece  with  the  sole-plate.  Two  strong  eyes  are  cast  in  the  sides  of  the  condenser  to  receive  the 
main  centre-shaft  M',  which  passes  completely  through  it.  In  the  top  is  an  opening  for  the  upper 
exhaust  passage  TT,  the  vertical  part  of  which  is  cast  of  a piece  with  the  hot-well  X.  This  also  rests 
upon  the  condenser,  but  is  separated  from  the  interior  by  an  inflected  partition. 

The  cold  water  for  effecting  the  condensation  of  the  steam  which  passes  into  the  condenser  by 
the  exhaust  ports,  when  the  engine  is  in  action,  is  admitted  by  an  injection-pipe.  This  pipe  passes 
through  the  side  of  the  vessel  and  communicates  with  the  water  without;  but  in  order  to  regulate  the 
supply  a valve  is  placed  in  the  pipe,  close  upon  the  condenser;  its  position  is  marked  by  v in  the  plan 
of  the  sole-plate.  The  face  upon  which  the  slide  works  is  formed  on  the  side  of  the  condenser  at  v,  over 
which  the  casing  is  fixed.  The  mode  of  working  the  valve  is  by  a small  brass  spindle  which  rises 
through  a packed  stuffing-box  in  the  cover  of  the  casing;  this  is  attached  to  a long  lever  passing  to  the 
opposite  side  of  the  engine,  and  which  can  be  more  or  less  depressed  at  pleasure,  to  allow  of  a larger 
or  smaller  supply  of  injection. 

The  part  of  the  pipe  within  the  condenser,  passes  completely  across,  and  is  perforated  with  numer- 
ous small  holes  to  diffuse  the  water  more  completely  in  the  body  of  the  condenser,  and  thereby  render 
i more  effective.  To  prevent  the  water  from  passing  into  the  lower  exhaust,  passage.  a shelf  is 


342 


MARINE  STEAM-ENGINE. 


attached  over  the  opening,  which,  throwing  the  water  over  the  edge  of  the  partition  into  the  body  of 
the  condenser,  prevents  it  from  accumulating  in  the  passage,  and  at  the  same  time  renders  the  water  o. 
more  avail  than  if  it  had  been  allowed  to  strike  against  the  side  of  the  condenser. 

The  air-pumps  and  valves. — The  condenser  communicates  at  bottom  by  a valve,  called  the  foot- 
valve,  with  the  air-pump  V,  the  barrel  of  which  is  44  inches,  clear  of  the  sole-plate,  thereby  leaving 
space  for  a body  of  water  to  enter  it  from  below.  The  barrel  of  the  pump  is  bored  and  lined  with  a 
thin  cylinder  of  brass  turned  to  fit  within  it.  A strong  flange  is  cast  round  it  at  11  inches  from  its 
lower  end,  which  is  fitted  water-tight,  and  bolted  to  the  margin  of  a circular  opening  cast  in  the  upper 
division  of  the  sole-plate,  for  the  reception  of  the  lower  end  of  the  barrel,  as  shown  in  the  section,  and 
also  in  the  plan  of  the  sole-plate. 

The  bucket  consists  of  a ring  connected  to  the  eye  at  the  centre,  into  which  the  rod  is  fitted  by  four 
arms.  The  under  side  of  the  ring  has  a flange  cast  upon  it  of  one  inch  breadth,  between  which  and 
the  projecting  ledge  of  the  junk-ring,  bolted  on  the  upper  side,  a packing  of  hemp  is  retained.  But 
before  applying  this  packing,  both  the  flange  and  the  junk-ring  are  turned  to  work  easily  in  the  barrel. 
The  pump-rod  is  sheathed  also  with  brass,  to  prevent  corrosion  by  contact  with  the  water.  To  apply 
this  sheathing,  the  rod,  which  consists  of  malleable  iron,  is  first  roughly  turned ; it  is  then  thoroughly 
cleaned  and  taken  to  the  brass  foundry,  where  the  covering  of  brass  is  cast  upon  it,  of  somewhat  more 
than  the  required  thickness.  It  is  again  put  into  the  lathe  and  turned  to  the  requisite  diameter.  The 
rod,  which  thus  possesses  all  the  advantages  of  strength  and  diminished  liability  to  corrosion,  is  retained 
in  the  tapered  eye  of  the  bucket  by  a cotter,  and  passes  through  a packed  stuffing-box  in  the  cover  of 
the  pump.  The  bucket-valve  is  of  that  kind  technically  known  as  the  pot-lid  valve,  in  contradistinc- 
tion to  the  butter-fly  valve,  which  consists  of  two  hinged  flaps.  The  pot-lid  valve  consists  of  a circular 
plate,  which  slides  vertically  on  the  pump-rod  by  means  of  a bored  eye  at  its  centre ; the  plate  is 
strengthened  by  ribs  radiating  from  the  eye,  and  terminating  in  a narrow  ring  on  its  circumference, 
which  is  faced,  and  fits  water-tight  upon  the  similarly  faced  edge  of  a ring  projecting  round  the  plane 
of  the  bucket. 

To  understand  the  action  of  this  valve  it  is  only  necessary  to  conceive  the  under  part  of  the  barrel 
to  be  filled  with  water,  and  the  bucket  to  be  forced  to  descend  in  it ; it  is  then  obvious  that  the 
water  passing  between  the  arms  will  meet  the  under  surface  of  the  valve,  and  prevent  it  descending 
with  the  bucket ; for  being  inelastic,  and  also  being  prevented  from  returning  into  the  condenser  by  the 
foot-valve,  it  must  force  a passage  at  the  least  resisting  point ; but  the  only  resistance  which  the 
valve  offers  being  its  own  weight,  the  water  will  bear  it  up  and  force  a passage  at  its  circumference, 
over  the  ring  of  the  bucket,  and  will  continue  to  ascend  relatively  in  the  barrel  so  long  as  the  bucket 
continues  to  descend ; but  when  the  bucket  has  attained  the  lowest  point  of  the  stroke  and  begins  to 
return,  then  the  valve,  being  of  greater  specific  gravity  than  the  water,  will  shut  by  its  own  weight, 
and  will  carry  whatever  water  is  above  it  to  the  height  of  its  own  ascent.  The  water  thus  carried  up  is 
ejected  by  the  valve  called  the  discharge-valve,  into  the  hot-well  X,  so  called  because  the  water  thus 
thrown  into  it  by  the  air-pump,  being  that  employed  in  condensation,  has  its  temperature  proportionally 
increased. 

It  may  be  observed  that  the  bucket  and  valve  are  of  brass,  as  are  also  spindles  which  form  their  axes. 
The  box-framings  of  these  valves  are  formed  of  cast-iron,  faced  with  brass,  and  fitted  water-tight  into 
their  seats,  where  they  are  each  retained  by  two  long  copper  keys,  one  at  each  side,  inserted  from  above 
before  the  covers  are  put  on.  The  covers  are  likewise  fitted  water-tight  and  bolted  down. 

The  valves  are  prevented  from  opening  beyond  the  requisite  distance,  by  projecting  bridges  situated 
before  them,  as  shown  in  the  section. 

The  hot-well. — -The  hot-well,  as  already  observed,  is  situated  above  the  condenser.  The  part  marked 
X,  with  the  vertical  part  of  T,  of  the  upper  exhaust  passage,  is  formed  of  a single  casting,  fitted  water- 
tight to  the  top  of  the  condenser.  In  one  side  of  the  well,  as  shown  in  the  section,  is  a rectangular 
recess  covered  b/  a door,  through  which  admission  can  be  obtained  to  the  interior ; and  in  the  side  ad- 
jacent to  that  of  the  vessel,  as  shown  in  the  elevation,  is  a circular  opening  to  which  the  discharge-pipe 
Y is  bolted.  Through  this  latter  the  excess  of  water  beyond  that  required  for  supplying  the  boilers,  is 
discharged  into  the  sea.  The  pipe  consists  of  a single  length  outside  of  the  condenser,  to  which  it  is 
fitted  by  an  expansion  joint,  to  compensate  for  the  spring  of  the  vessel  wdien  at  sea ; and  has  also  a 
valve  in  it  capable  of  opening  outwards,  but  which  being  shut  resists  the  pressure  of  the  water 
inwards. 

An  air-vessel  Z is  placed  over  the  hot-well  and  fitted  to  it  air  and  water  tight.  The  object  of  this 
vessel  is  to  create  an  elastic  pressure  by  means  of  the  air  contained  within  it,  to  assist  in  ejecting  the 
water  through  the  di«charge-valve  should  the  hot-well  from  any  cause  become  surcharged.  The  pressure 
thus  brought  into  action  by  continuing  to  increase  with  the  exigency  of  the  case  will,  under  all  ordinary 
circumstances,  prevent  accumulation  of  water  in  the  well  to  any  detrimental  extent. 

Feed  and  bilge  pumvs. — The  same  cross-head  u by  which  the  air-pump  is  worked,  serves  also  to  work 
two  other  pumps  of  smaller  dimensions.  These  are  the  feed-pump,  by  which  water  is  supplied  from 
the  hot-well  to  the  boilers,  and  the  bilge-pump,  by  which  leakage  water  is  withdrawn  from  the  hold 
of  the  vessel.  These  are  very  nearly  identical  in  construction  with  the  bilge-pump.  The  barrel  is 
formed  of  cast-iron,  but  the  plunger,  which  is  made  hollow  for  the  sake  of  lightness,  is  formed  of  brass. 
It  is  connected  to  the  cross-head  by  a cotter,  a portion  of  the  end  being  made  solid  for  that  purpose. 

This  pump  communicates  with  the  hot-well  by  a pipe  projecting  from  the  side  of  the  barrel,  a portion 
of  which  is  shown  in  the  general  elevation,  where  it  is  marked  W.  The  feed-box  is  bolted  upon  the  side 
of  the  part  of  the  hot-well  formed  in  the  condenser,  at  the  position  marked  w'  in  the  plan  of  the  sole- 
plate,  by  square  flanges  upon  the  face.  In  the  side  of  the  hot-well  are  two  square  holes  corresponding 
to  the  two  openings  in  the  feed-box,  and  these  being  made  to  coincide,  the  pipe  from  the  feed- 
pump is  attached  to  the  lower  of  the  two  circular  openings  in  front  of  the  box  corresponding  to  the 
lower  of  the  square  openings,  and  the  upper  communicates  by  a copper  pipe  with  the  boilers.  This 


MARINE  STEAM-ENGINE. 


343 


connection  being  effected,  and  a clack-valve,  opening  towards  the  pump,  being  placed  in  the  lower 
division  of  the  box,  and  a similar  valve,  opening  reversely,  being  placed  in  the  upper  division,  if  the 
plunger  be  made  to  ascend  in  the  barrel  of  the  pump,  leaving  a corresponding  space  unoccupied,  the 
water  will  flow  from  the  hot-well,  by  its  own  gravity,  into  the  pump  ; but  on  the  plunger  beginning  to 
descend  the  valve  in  that  division  of  the  feed-box  will  be  closed  by  the  pressure  of  the  water  tending 
to  return  to  the  hot-well,  and  consequently  will  be  forced  through  the  upper  valve,  and  along  the  feed- 
pipe, to  the  boilers.  But  if  more  water  be  drawn  by  the  pump  than  is  required  for  the  boilers,  it  is 
simply  ejected  through  the  valve  in  the  upper  division  of  the  box,  and  thus  returned  to  tire  well.  The 
pressure  of  water  in  the  box  is  maintained  by  a loaded  conical  valve  placed  on  the  top : this  can  be 
adjusted  at  pleasure  to  suit  the  pressure  of  steam  in  the  boilers. 

Instead  of  being  guided  by  parallel-motion  bars,  the  pump  cross-head  is  restricted  in  its  vertical 
path  by  two  guide-rods  vv  attached  to  the  flanges  of  the  feed  and  bilge  pumps  at  their  lower  ends,  and 
to  the  diagonal  framing  above  ; these  pass  through  bushed  eyes  in  the  cross-head  which  is  thus  confined 
at  the  same  time  that  it  slides  freely  upon  the  rods  in  its  alternating  ascent  and  descent. 

The  cross-head  is  connected  to  the  side-levers  by  the  rods  1 t,  which  are  formed  with  solid  bushed  eyes 
at  their  upper  ends,  and  with  butts  and  straps  at  their  lower  extremities. 

Shifting-valve. — The  bottom  of  the  air-pump  well  communicates  by  a pipe  with  a small  conical  valve, 
which  is  technically  called  the  snifting-valve.  This  valve  is  kept  shut  by  a screwed  pin  passing  through 
a malleable  iron  bridge  made  fast  upon  the  mouth  of  the  pipe.  To  the  side  of  this  pipe,  above  the 
valve,  is  cast  a small  return  branch,  by  which  the  water  passing  through  the  valve  is  carried  off. 

The  use  of  this  valve  is  to  admit  of  the  escape  of  the  air  within  the  condenser,  air-pump,  and  steam- 
passages,  on  starting  the  engine,  and  before  these  have  been  filled  with  steam.  When  about  to  start, 
the  pin  is  simply  unscrewed  by  hand,  to  permit  the  valve  to  rise  and  allow  the  air  and  water  to  escape, 
and  give  place  to  the  steam,  which  now  flows  onwards  from  the  valve-casing,  occupying  all  the  passages 
and  condenser,  and  finally  begins  to  issue  by  the  valve  itself. 

Blow-through  valve. — This  valve  is  situated  at  the  position  marked  u'  in  the  plan  of  the  sole-plate. 
It  is  placed  in  a chest  fixed  upon  the  steam-valve  casing  at  the  lower  end,  and  has  two  openings, 
one  above  and  the  other  below  the  packing  port.  The  valve  itself  is  placed  between  these  two 
apertures. 

This  valve  is  used  simultaneously  with  the  snifting-valve,  to  allow  the  steam  to  fill  the  passages  and 
condenser,  when  preparing  to  start  the  engine,  and  thereby  to  displace  the  air  and  water  which  may  be 
lodged  in  them,  through  the  snifting-valve. 

Priming-valves. — These  are  two  small  valves,  situated  in  the  steam-ports  of  the  cylinder,  and  are 
called  priming-valves  from  their  being  intended  to  discharge  any  water  carried  over  into  the  cylinder 
with  the  steam,  and  which  is  technically  termed  priming.  These  valves  are  kept  shut  by  springs  acting 
against  them  externally,  and  of  such  strength  as  to  resist  the  ordinary  pressure  of  the  steam ; but  should 
water  lodge  in  the  passages,  owing  to  its  non-elastic  properties,  it  will  be  ejected  through  the  valves  by 
the  action  of  the  piston  tending  to  compress  it. 

Expansion  geer. — The  expansion  geer  consists  of  an  apparatus  by  which  the  amount  of  steam 
admitted  during  a stroke  of  the  piston  can  be  diminished  at  pleasure,  when  it  is  not  required  to  work 
the  engines  to  full  power.  The  first  part  of  the  apparatus  consists  of  a cam  with  five  faces  fixed  on 
the  crank-shaft,  as  shown  in  the  elevation  and  plan  of  the  engine.  These  faces  are  of  different  lengths, 
giving  five  different  degrees  of  expansive  action.  They  are  so  formed  that  the  friction  roller  on  the 
end  of  the  lever  w,  and  bearing  against  any  one  of  them,  is  thrown  forward  through  the  same  space  ; 
but  the  time  of  action  varying  as  the  length  of  the  face,  the  effect  will  depend  upon  the  particular  face 
in  contact  with  the  roller ; and  this,  according  to  its  distance  from  the  frame,  may  be  made  to  bear 
against  either  one  or  other  of  the  faces.  The  position  of  the  roller,  and  consequently  of  the  lever  to 
which  it  is  attached,  is  regulated  by  a screw  and  nut ; the  last  is  formed  in  the  back  lever  x,  which  is 
forged  of  a piece  with  the  weighted  lever,  and  has  a long  hollow  boss  working  on  a stud  fixed  in  the 
framing.  The  screw  has  a handle  upon  the  projecting  end,  which  being  turned  causes  the  lever  w to 
advance  or  recede  upon  the  boss  of  the  double  lever  on  which  it  slides  by  a sunk  key.  The  roller  is 
kept  against  the  face  of  the  cam  by  the  action  of  the  weighted  lever ; the  weight  tending  to  de- 
scend and  carry  the  lever  with  it,  causes  the  opposite  lever  to  press  upwards  against  the  face  of 
the  cam. 

The  lever  x is  connected  by  a joint  with  an  adjustable  rod,  carried  forward  to  the  lever  y,  which  is 
fast  upon  a cross-shaft  supported  by  two  small  columns  on  the  flange  of  the  expansion  chest,  marked  Gr- 
in the  elevation.  On  the  same  shaft  is  keyed  the  double-ended  lever  y',  one  end  of  which  is  connected, 
by  flexible  links,  with  the  spindle  of  the  expansion-valve,  which  is  of  the  kind  known  by  the  name  of 
equilibrium  valves.  The  opposite  end  of  the  lever  y'  communicates  by  a rod  2 with  an  arrangement 
cl  levers  attached  to  the  side  of  the  condenser,  by  which  the  apparatus  can  be  thrown  into  geer  and 
disengaged  at  pleasure.  Thus  the  end  of  the  crank  lever  z'  being  moved  to  the  right,  the  rod  2 will 
be  drawn  down,  and  with  it  the  end  of  the  horizontal  lever  y'  to  which  it  is  attached ; but  the  lever  y' 
being  fast  upon  the  same  axis  as  the  vertical  lever  y,  this  lever  will  be  thrown  back,  and  at  the  same 
time  the  lever  x,  with  which  it  communicates ; and  again  the  lever  x being  fast  upon  the  same  axis  as 
the  lever  w,  this  last  will  be  projected  forward,  and  the  roller  thrown  out  of  contact  with  the  cam,  and 
the  engine  will  receive  the  full  supply  of  steam. 

Action  of  the  engine. — To  bring  the  engine  into  action,  the  steam  is  allowed  free  admission  into  the 
valve-casing  by  the  steam-pipe  G G,  leading  from  the  steam-chest  over  the  boilers.  To  prevent  the  pipe 
being  injured  by  expansion,  arising  from  the  variations  of  temperature  to  which  it  is  liable,  it  is  pro- 
vided with  expansion-joints  which  allow  the  ends  to  slide  upon  each  other,  and  thereby  maintain  the 
same  aggregate  length  between  the  two  extremities.  It  has  also  a valve,  called  the  throttle-valve, 
placed  in  it  to  regulate  the  supply  of  steam,  and  to  cut  off  the  communication  between  the  boilers  and 
the  casing  when  necessary.  The  valve  is  placed  close  to  the  junction  of  the  pipe  with  the  casing;  it  is 


344 


MARINE  STEAM-ENGINE, 


simply  a disk  of  the  same  diameter  as  the  inside  of  the  pipe,  -with  a rectangular  eye  cast  in  it  to  receive 
the  spindle  upon  which  it  works. 

The  steam-ports  of  the  cylinder  being  both  shut  by  the  valves,  and  the  blow-through  and  snifting- 
valves  open,  the  steam  is  allowed  to  pass  into  the  valve-casing  by  opening  the  throttle-valve,  partially 
at  first,  which  fills  the  steam-passages  and  condenser,  driving  the  air  and  water  before  it.  When  this 
has  been  accomplished,  and  steam  alone  issues  by  the  snifting-valve,  the  blow-through  valve  is  closed, 
and  the  injection-valve  is  opened ; the  cold  water  now  rushing  into  the  condenser  effects  the  conden- 
sation of  the  steam  with  which  it  was  filled,  and  creates  the  desired  vacuum.  The  eccentric-rod  l being 
out  of  geer  with  the  crank  upon  the  traverse-shaft  m,  and  a long  lever,  as  before  described,  being  applied 
to  the  starting-shaft  S,  the  steam-valves  are  raised  until  the  under  port  communicates  by  the  passage 
with  the  condenser,  and  the  upper  port  with  the  interior  of  the  valve-casing,  now  full  of  steam, 
which,  in  consequence  of  this  disposition,  will  flow  into  the  cylinder  above  the  piston  and  force  it  to  de- 
scend. The  next  operation  is  to  reverse  the  pressure  upon  the  starting-lever  and  thereby  to  reverse  the 
position  of  the  valves,  shutting  off  the  communication  of  the  upper  port  with  the  casing,  and  opening  it 
to  the  condenser,  at  the  same  time  that  the  communication  of  the  lower  port  is  cut  off  from  the  con- 
denser and  opened  to  the  interior  of  the  casing.  This  being  done  the  steam  will  flow  from  the  cylinder 
into  the  condenser,  and  encountering  there  a shower  of  cold  water  from  the  injection-pipe,  will  be  con- 
densed, and  a vacuum  thereby  formed  in  the  cylinder  above  the  piston.  By  that  means  the  pressure 
over  the  piston  is  removed,  and  the  steam  flowing  into  the  cylinder  beneath  it,  forces  it  to  ascend  to  the 
top  of  the  cylinder. 

But  the  piston  being  connected  by  the  cross-head  and  side-rods,  with  the  side-levers,  carries  these 
with  it  in  its  ascent  and  descent,  through  an  arc,  whose  chord  is  equal  to  the  length  of  the  stroke  of  the 
piston  ; and  the  side-levers  being  connected  at  their  opposite  ends  by  means  of  the  cross-tail  and  con- 
necting-rod, with  the  crank,  the  motion  of  the  piston  is  thus  transferred  to  the  crank-shaft,  and  through 
it  to  the  paddles,  which  are  fast  upon  its  extremities. 

After  two  or  three  strokes  of  the  piston  the  moving  parts  will  have  acquired  a certain  degree  of  mo- 
mentum, and  this  is  taken  advantage  of  to  render  the  engine  self-acting.  The  crank-shaft  being  in 
motion,  if  the  eccentric-rod  l be  thrown  into  geer  with  the  traverse-shaft,  exactly  the  same  effect  will  be 
produced  upon  the  valves  as  by  the  lever  applied  to  the  starting-shaft  S ; for  by  the  alternating  thrust 
and  pull  of  the  rod,  communicated  to  it  by  the  eccentric  R,  the  crank  of  the  traverse-shaft  will  be  made 
1o  describe  a certain  portion  of  a revolution,  proportional  to  the  eccentricity  of  the  eccentric,  and  the 
valve  lever  n being  fast  upon  that  shaft,  the  valves  must  consequently  ascend  and  descend  regularly 
with  the  revolutions  of  the  crank-shaft ; and  these  revolutions  are  performed  uniformly  with  the  alter- 
nating ascent  and  descent  of  the  piston. 

The  water  is  drawn  out  of  the  condenser  by  means  of  the  air-pump  with  the  same  regularity ; for  the 
air-pump  cross-head  being  worked  by  the  side-levers,  it  will  move  simultaneously  with  them ; the  feed- 
pump being  also  attached  to  the  same  cross-head,  the  boilers  will  be  furnished  with  water  in  proportion 
to  the  speed  of  the  engine,  and  consequently  in  proportion  to  the  quantity  of  steam  used. 


Literal  references. 


A,  the  sole-plate  of  the  engine. 

a a a,  holding-down  bolts  by  which  the  sole-plate  is 
fixed  to  the  keelsons. 

B,  the  crank  framing. 

b b.  spring-stays  of  the  crank  framing  which  work 
between  face-plates  on  the  paddle-beams. 

C,  the  diagonal  framing. 

cc,  stay-rods  connecting  the  framings  of  both  en- 
gines. 

I),  the  parallel-motion  framing. 

d d , flanges  by  which  the  diagonal  framing  is  bolted 
to  the  cylinder. 

E,  the  steam-cylinder. 

F,  the  steam-valve  casing. 

G,  the  steam-pipe  and  expansion -valve  chest. 

H,  the  steam-piston  rod. 

I,  the  cylinder  cross-head. 

J J,  the  cylinder  side-rods. 

K K,  the  radius-bars  of  the  piston-rod  parallel 
motion. 

ff  the  radius  levers  of  the  parallel  motion. 

e/ g,  pinching-screws  for  adjusting  the  ends  of  the 
radius-bars. 

L,  the  parallel-motion  shaft. 

h,  the  parallel-motion  side-rod  attached  to  the  lever 
f and  to 

M M,  the  great  side-levers  of  the  engine. 

M',  the  main  centre. 

i i,  bosses  at  the  centres  of  the  side-levers,  through 
which  pass  the  keys  for  tightening  the  bearings. 

X,  the  connecting-rod. 

0,  the  cross-tail  of  the  connecting-rod. 


j,  the  cross-tail  links. 

P P,  the  cranks. 

Q Q,  the  crank  or  paddle  shaft. 

R,  the  eccentric  for  working  the  valves. 

l,  the  eccentric-rod. 

m,  the  traverse  or  valve  shaft. 

n,  the  valve-lever. 

o,  small  parallel-motion  for  the  valve-spindle. 

p,  a small  framing  to  which  are  attached  the 
ends  of  the  radius-bars  of  the  valve  parallel- 
motion. 

q,  the  back  balance  or  counter  weight  of  the 
valve. 

r,  the  back  balance  or  counter  weight  of  the  ec- 
centric. 

s s,  levers  by  which  the  valve  counter  weight  is 
attached  to 

S,  the  starting-shaft. 

T and  T',  the  upper  and  lower  exhaust  passages. 

U,  the  condenser,  cast  of  a piece  with  the  sole-plate. 

V,  the  air-pump  cylinder,  lined  with  brass. 

1 1,  the  air-pump  side-rods. 

u,  the  air-pump  cross-head. 

v,  guides  for  the  air-pump  cross-head. 

W,  the  feed-pump. 

X,  the  hot-well. 

Y,  the  discharge-pipe. 

Z,  the  air-vessel. 

u’,  (in  plan  of  sole-plate)  the  part  of  the  sole-plate 
to  which  the  blow-through  valve  is  bolted. 
v',  (in  plan  of  sole-plate)  a projection  on  the  conden- 
ser, to  which  the  expansion-valve  casing  is  bolted 


MARINE  STEAM-ENGINE. 


345 


•o',  (in  plan  of  sole-plate)  the  part  of  the  hot-well 
to  which  the  feed-chest  is  bolted. 
w,  the  movable  lever  of  the  expansion-geer. 


x,  the  fixed  lever  of  the  expansion-geer. 
y y'  y\  additional  levers  for  working  the  expansion- 
valve. 


American  Marine  Steam-Engine. — Section  and  details  of  the  engine  of  the  United  States  Mail 
Steamer  Pacific,  built  at  the  Aliaire  Works  city  of  New  York,  after  the  design  of  C.  W.  Copeland,  Esq 

Details. 


Fig.  2717,  longitudinal  section  of  engine. 

Fig.  2718  shows  a plan  of  the  bed  plate. 

Fig.  2719,  a longitudinal  projection. 

Fig.  2720,  a transverse  section,  vertically  of  the 
bed-plate  and  condenser  through  the  centre  of 
the  side-lever  shaft  bearing. 

Fig.  2721,  transverse  section  of  bed-plate  through 
the  centre  of  the  sockets,  for  the  support  of  the 
pillow-block  columns. 

Fig.  2722  shows  a vertical  elevation  of  steam  cyl- 
inder. 

Fig.  2723,  plan. 

Fig.  2724,  a vertical  elevation  of  the  air-pump. 

Fig.  2725,  plan. 

Fig.  2726  shows  a longitudinal  projection  of  side- 
lever. 

Fig.  2727,  plan. 

Fig.  2728,  a vertical  section  through  steam  piston. 
Fig.  2729,  sectional  plan. 

Fig.  2730,  side  elevation  of  outboard  pillow-blocks. 
Fig.  2731,  plan. 

Fig.  2732,  plan  of  reservoir. 

Fig.  2733,  end  projection. 

Fig.  2734,  side  elevation. 

Fig.  2735,  vertical  section  through  man-hole  open- 
ing- 

Fig.  2736,  longitudinal  projection  of  main  pillow- 
block. 

Fig.  2737,  plan. 

Fig.  2738,  section  through  socket  for  column. 

Fig.  2739,  vertical  projection  of  air  column. 

Fig.  2740,  plan. 

Fig.  2741,  front  view  of  upper  steam-chest. 

Fig.  2742,  end  view  of  upper  steam-chest. 

Fig.  2743,  front  view  of  lower  steam-chest,  with 
side-pipes  attached  to  upper  chest. 

Fig.  2744,  end  view  of  lower  steam-chests. 

Fig.  2745,  vertical  section  through  air-pump  cover. 
Fig.  2746,  plan. 

Fig.  2747,  vertical  section  through  air-pump  bucket 
and  valve. 

Fig.  2748,  plan. 

Fig.  2749,  vertical  section  of  cylinder  top  and  false 
cover. 

Fig.  2750,  plan. 

Fig.  2751,  side  view  of  cut-off  eccentric. 

Fig.  2752,  end  view. 

Fig.  2753,.  side  view  of  steam  eccentric. 

Fig.  2754,  end  view. 

Fig.  2755,  vertical  elevation  of  force-pump. 

Fig.  2756,  vertical  section. 

Fig.  2757,  plan. 

Fig.  2758,  vertical  elevation  of  bilge-pump. 

Fig.  2759,  plan. 


Fig.  2760,  elevation  of  force-pump  plunger. 

Fig.  2761,  side  projection  of  force-pump  chest. 

Fig.  2762,  plan. 

Fig.  2763,  front  view  of  bonnet  to  close  over  opening 
to  adjust  valves. 

Fig.  2764,  end  view. 

Fig.  2765  plan  of  bilge-pump  chest. 

Fig.  2766,  longitudinal  projection. 

Fig.  2767,  end  elevation. 

Fig.  2768,  plan  of  bonnet. 

Fig.  2769,  end  view  of  bonnet. 

Fig.  2770,  plan  of  bilge-pump  plunger. 

Fig.  2771,  vertical  section. 

Fig.  2772,  side  view  of  centre-bearing  for  water- 
wheel shaft. 

Fig.  2773,  plan. 

Fig.  2774,  water-wheel  shaft. 

Fig.  2775,  centre  water-wheel  shaft. 

Fig.  2776,  side  view  of  driven  crank. 

Fig.  2777,  plan. 

Fig.  2778,  side  view  of  driving-crank. 

Fig.  2779,  plan. 

Fig.  2780,  parallel-motion  shaft. 

Fig.  2781,  end  view  of  parallel-motion  arm. 

Fig.  2782,  plan. 

Fig.  2783,  side  view  and  plan  of  air-pump  rods. 
Fig.  2784,  side  view  and  plan  of  radius  rods  for 
parallel  motion. 

Fig.  2785,  side  view  and  plan  of  parallel-motion 
connecting-rod. 

Fig.  2786,  pillow-block  columns. 

Fig.  2787,  side  elevation  of  bush  for  driven  crank. 
Fig.  2788,  plan. 

Fig.  2789,  vertical  elevation  of  cross-tail,  with  side- 
lever  links  attached. 

Fig.  2790,  plan  of  cross-tail. 

Fig.  2791,  end  view  of  side-lever  links. 

Fig.  2792,  plan. 

Fig.  2793,  vertical  projection  of  cylinder  cross-head. 
Fig.  2794,  plan. 

Fig.  2795,  piston-rod. 

Fig.  2796,  side  view  of  side-lever  shaft,  with  washers 
on  the  ends. 

Fig.  2797,  end  view. 

Fig.  2798,  side  view  and  plan  of  main  connecting- 
rod. 

Fig.  2799,  side  view  and  plan  of  cylinder  side- 
links. 

Fig.  2800,  side  view  and  plan  of  cut-off  eccentric- 
rod. 

Fig.  2801,  side  view  and  plan  of  steam  eccentric- 
rod. 

Fig.  2802,  vertical  elevation  of  air-pump  cross-head. 
Fig.  2803,  plan. 


Literal  References  to  Fig.  2717. 


A,  the  bed-plate,  upon  which  the  engine  stands. 

B,  the  cylinder  bottom,  cast  upon  the  bed-plate,  in 
which  is  the  lower  steam  opening. 

C,  cylinder. 

D,  steam  piston. 

E,  piston-rod. 


F,  cylinder  cross-head,  attached  to  the  piston-rod, 
and  also  to  the  side  levers,  by  two  side-rods. 

G,  cylinder  side-rods. 

H H,  upper  and  lower  steam-chests,  in  which  are 
fitted  valves  for  the  induction  and  eduction  of 
steam  to  and  from  the  cylinder. 


346 


MARINE  STEAM-ENGINE. 


1 1,  steam-valves. 

J J,  valve-stems,  on  which  are  keyed  the  steam- 
valves. 

K,  parallel-motion  shaft  and  standard. 

L,  lifting-rods,  for  lifting  steam  and  exhaust  valves, 
worked  from  an  eccentric  on  the  water-wheel 
shaft. 

M it,  steam-toes,  keyed  to  the  lifting-rod. 

N N,  feet  for  lifting -rod,  attached  to  the  rock- 
shaft. 

O,  steam  and  exhaust  side-pipes. 

P,  foot-valves  and  seats. 

Q,  condenser,  cast  upon  bed-plate. 

R,  side-lever  shaft,  passing  through  and  firmly  keyed 
to  condenser. 


e e,  pillow-block  columns,  keyed  into  sockets  cast 
upon  the  bed-plate. 

/,  pillow-blocks  for  water-wheel  shafts. 

g,  cranks. 

h,  main  connecting-rod,  connecting  cross-tail  and 
crank-pin. 

i,  cross-tail,  attached  to  the  side-levers  by  two 
short  links,  also  the  main  connecting-rod. 

j,  main-braces  from  pillow-blocks  to  cylinder. 

k,  steam-valve  lifters,  keyed  to  the  lifting-rods. 

l,  parallel  bar  for  parallel  motion. 

m,  parallel  motion  connecting-rod 

n,  eccentric-rod. 

o,  guide-rod  for  air-pump  cross-head. 

p,  brace  from  pillow  blocks  to  bed-plate. 


S,  side-levers. 

T,  hot-well. 

U,  injection-pipe. 

V,  connection,  from  exhaust-pipe  to  condenser. 

W,  air-column,  to  receive  the  air  arising  from  the 
waste  water,  thereby  facilitating  its  discharge. 

X,  air-pump. 

Y,  air-pump  piston. 

Z,  air-pump  rod. 

a,  air-pump  cross-head. 

b,  delivery  valves  and  seats. 
d,  force-pump  chest. 


q,  injection-valve. 

r,  centre-bearing  for  rock-shaft. 

s,  brace  from  cylinder  to  bed-plate. 

1 t,  cross-beams  for  pillow-blocks. 

u u,  studs  and  transverse  braces. 

v,  nuts  for  securing  pillow-blocks  to  columns. 

w,  bolts  for  holding  down  pillow-block  caps. 

I x Xy  studs  between  columns  and  bolts,  running  trans- 
j versely  through  each  set. 
y,  braces  from  pillow-blocks  to  bed-plates,  in  the 
centre  of  each  and  between  engines. 

Zy  snifting-valve. 

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MARINE  STEAM-ENGINE. 


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MARINE  STEAM-ENGINE. 


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MARINE  STEAM-ENGINE. 


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Yol.  II. — 23 


354 


MARINE  STEAM  ENGINE. 


Engines  of  the  Golden  Gate.  Plate  II.  is  the  front  elevation,  and  Plate  III.  the  side  elevation  an« 
section  through  air  pumps,  a main  shaft,  b crank-pin,  cccc  cylinder;  d trunnions  on  which  the 
cylinder  oscillates  to  accommodate  itself  to  the  motion  of  the  crank ; e stuffing  box  on  the  cylin- 
der-head. This  is  made  as  long  as  practicable,  to  give  as  much  bearing  as  possible  for  oscillating 
the  cylinder,  f f belt-passage  connecting  the  trunnion  with  gg  side-pipe,  hli  valve-stems,  connect- 
ing with  the  balance  puppet-valves  in  Hi  valve-chests.  The  lower  valve  on  the  right  or  steam  side 
is  concealed  by  j j j j,  air-pump;  the  air-pump  bucket  is  provided  with  India-rubber  valves,  and  is 
worked  by  k,  crank  on  the  intermediate  shaft.  I III,  condenser : there  are  two  condensers  and  two  air- 
pumps  ; they  are  located  between  the  cylinders  and  inclined  towards  each  other,  one  only  being  repre- 
sented. 

The  passage  f f,  together  with  the  side-pipes,  valve-chests,  and  appurtenances,  are  fixed  to  the  cylin- 
der, and  oscillate  with  it,  the  steam  being  received  through  one  trunnion  and  allowed  to  escape  to  the 
condenser  through  the  opposite  one.  m is  an  injection-cock  admitting  the  water  upon  a scattering  plate 
in  the  condenser.  These  are  the  first  oscillating  engines  to  which  balance  puppet-valves  have  ever  been 
applied ; and  the  constructors,  Messrs.  Stillman  & Allen,  deserve  great  credit  for  successfully  carrying 
out  so  decided  an  improvement. 

The  valves  are  worked  by  the  toes  o o in  the  usual  manner.  The  rock-shafts  p p receive  motion  partly 
from  the  movement  of  the  cylinder,  and  partly  from  the  eccentric.  Levers  are  permanently  attached  to 
the  trip-shafts  qq,  the  ends  of  which  work  in  a slotted  piece  curved  to  the  centre  of  the  trunnion.  This 
piece  is  guided,  as  represented  in  the  engraving,  by  vertical  rods  sliding  in  bushes  attached  to  the  fixed 
framing,  and  is  connected  by  a rod  to  the  starting  lever  r,  all  the  levers  for  working  by  hand  being  so 
balanced,  that  the  engineer  with  one  hand  can  work  the  engine  up  to  the  usual  speed.  The  cut-off 
valve  is  placed  outside  the  trunnion,  and  is  a balance  puppet-valve,  worked  by  the  ordinary  cam  motion, 
and  so  arranged  as  to  act  either  as  cut-off  or  throttle,  or  both,  the  levers  being  placed  within  reach  of 
the  engineer  when  working  the  engine. 

The  Golden  Gate  has  four  return  tubular  boilers — two  forward  and  two  aft  of  the  engines.  They  are 
placed  at  the  sides  of  the  ship,  leaving  room  for  the  fire-room  in  the  centre.  The  furnaces  are  conse- 
quently athwart-ships  instead  of  ranging  fore  and  aft  as  usual. 

The  Illeiois,  plying  between  this  city  and  Chagres,  the  John  L.  Stevens,  the  Augusta,  plying  between 
this  city  and  Savannah,  the  Republic,  the  Agnes,  a vessel  constructed  for  the  Spanish  government  in 
1850,  the  Arago  of  the  Havre  line,  the  Adriatic  of  the  Collins  line,  are  among  the  American  examples 
of  paddle-wheel  steamers  fitted  with  oscillating  engines. 

The  Golden  Gate  is  of  the  following  principal  dimensions : Length  on  deck,  265  feet ; beam,  40  feet ; 
depth  of  hold,  22  feet;  tonnage,  2030  tons;  diameter  of  cylinders,  85  inches;  stroke,  9 feet;  average 
revolutions,  18^;  average  pressure  in  boilers  above  atmosphere,  12  lbs. ; cut-off  from  commencement,  3 
feet ; amount  of  fire  surface,  1 2,052  square  feet ; tube  surface,  8396 ; grate  surface,  367 ; calorimeter 
of  tubes,  61f  feet;  paddle-wheels,  diameter  31  feet;  length  of  paddle,  12  feet;  depth,  24  inches;  num- 
ber of  paddles  in  each  wheel,  30. 

Sorrows ’ Double  Acting  Reversible  Rotary  Steam  Engine. — Arranged  for  working  steam  expansively. 

Plate  IV.  is  a perspective  view  of  two  cylinders  or  engines  fixed  on  one  shaft  for  the  expansive  work- 
ing of  the  steam.  The  cylinders  are  of  equal  diameter  but  of  unequal  length.  The  steam^s  first  ad- 
mitted to  the  smaller;  after  doing  its  work  in  which,  the  greater  part  is  admitted  at  a lower  pressure  to 
the  larger  cylinder.  In  this  respect,  working  the  steam  through  two  engines,  it  somewhat  resembles  the 
well-known  Woolf  engine,  but  with  this  difference,  that  the  steam  is  taken  from  the  first  engine  at  such 
a point  that  it  exerts  no  back  pressure.  This  will  be  understood  by  examining  Plate  V.,  which  repre- 
sents a vertical  and  horizontal  section  of  the  smaller  engine  only.  The  larger  engine  resembles  this, 
except  in  having  but  four  instead  of  eight  pistons,  or  leaves,  and  in  having  no  outlets  for  the  steam  at 
the  top  and  bottom,  as  in  the  smaller. 

c is  a pedestal  of  cast  iron  on  which  the  cylinder  rests,  forming  the  whole  of  the  frame  of  the  engine ; 
a is  the  cylinder,  whose  inner  periphery  is  turned  perfectly  true,  and  whose  ends  are  closed  by  heads  d d, 
in  each  of  widen  heads  is  a groove  h h,  the  form  of  which  is  best  shown  in  fig.  5 by  dotted  lines, 
being  that  of  a circle  with  segments  cut  off  on  opposite  sides,  leaving  only  two-fourths  of  its  circum- 
ference. On  opposite  sides  of  the  cylinder  are  abutments  n n , cast  upon  the  steam-heads  m m ; on  either 
side  of  which  abutments  are  quadrangular  openings  1 1',  u v! , connecting  with  the  double  three-way  cocks 
qq.  To  the  inside  of  the  cylinder  is  fitted  the  steam- wheel  ee  ee  e'e'.  The  ends  of  the  steam-wheel  are 
formed  of  two  plates  ee,  ee,  of  a diameter  equal  to  the  interior  of  the  cylinder,  and  secured  by  bolts  ii, 
to  a ring  e'e'  of  less  diameter,  which  forms  the  bottom  of  the  channel  f,  in  which  the  steam  acts.  Its 
axle  j passes  through  boxes  in  the  cylinder  ends,  packed  with  metallic  packing,  and  lined  with  anti- 
friction rollers.  The  rollers  may,  no  doubt,  be  omitted  in  practice,  as  a refinement  of  little  use,  if  not 
positively  productive  of  derangement.  The  peripheries  of  the  two  plates  ee,  ee,  forming  the  ends  of  the 
steam-wheel,  are  made  to  fit  steam-tight  to  the  interior  of  the  cylinder,  by  means  of  metallic  packing- 
rings  let  into  the  interior  of  their  flanges  as  represented.  The  abutments  n n are  packed  with  metallic 
packing  o to  the  bottom,  and  p to  the  sides  of  the  channel/';  the  packing-pieces  o and  p being  dove- 
tailed together,  so  that  p will  slide  with  o,  but  at  the  same  time  slide  outwards,  independently  of  it  as  they 
wear.  The  steam  acts  in  the  passage  f upon  8 slides  or  leaves  g g,  which  we  will  term  pistons,  which 
revolve  with  the  steam-wheel,  but  are  capable  of  sliding  to  or  from  the  centre  through  slots  in  the  ring 
ee.  It  will  be  seen  that  the  sides  of  the  channel  f are  formed  by  the  plates  ee,  before  described,  so 
that  the  channel  is,  in  fact,  wholly  sunk  in  the  rim  of  the  steam-wheel.  The  pistons  are  made  a little 
wider  than  ‘-he  channel,  and  partially  supported  by  shallow  radial  grooves  on  the  inside  of  the  plates 
ee.  The  p'  it  ms  are  packed  on  their  edges  both  to  the  inner  periphery  of  the  cylinder  and  to  the  grooves 
«i  the  sides  of  the  channel/'.  This  packing  is  shown  on  the  right  hand  of  fig.  2,  Plate  V.,  in  section,  the 
section  being  taken  through  the  centre  of  the  piston,  and  exhibiting  the  end  and  side  packing  dovetailed 


MARINE  STEAM  ENGINE. 


355 


loosely  together  in  the  same  manner  as  already  described  in  the  packing  of  the  abutments.  The  slots 
through  which  the  piston  slides  are  also  packed,  as  represented  in  fig.  1.  All  the  packing  pieces  are 
kept  to  their  work  by  small  helical  springs  at  their  hacks.  From  the  inner  edge  of  each  piston  at  each 
side,  a square  stud  V projects  through  a radial  slot  f ',  in  the  plates  ee,  and  at  the  end  of  each  stud  is  a 
pivot  </,  carrying  a friction-roller.  These  friction-rollers  travel  in  the  grooves  h h,  inside  the  fixed  cyl- 
inder head,  and  during  the  revolution  of  the  wheel  cause  the  pistons  to  alternately  project  and  with- 
draw into  the  wheel.  By  the  form  of  the  groove,  it  will  be  seen  that  each  piston  will  project  across  the 
channel  f during  two-fourths  of  the  revolution,  while  during  the  remaining  two-fourths,  it  will  be  wholly 
or  in  part  withdrawn  into  the  interior  of  the  wheel.  At  the  moment  of  passing  either  abutment  re  re, 
the  outer  edge  of  the  piston  will  coincide  with  the  outer  surface  of  the  ring  e'e',  so  that  the  packing 
pieces  oo  of  the  abutments  have  presented  to  them  by  the  revolution  of  the  steam-wheel  simply  a con- 
tinuous cylindrical  surface. 

The  steam-heads  or  cocks  m m,  through  which  the  steam  is  admitted  to  the  cylinder,  and  which 
supply  the  place  of  valves,  valve-gear,  and  reversing-gear  in  ordinary  engines,  are  of  peculiar  con- 
struction, having  six  ways  or  passages  in  each.  There  are  conical  seats  in  each  to  receive  the  plugs 
q q',  in  which  are  passages  to  correspond  with  the  ways  in  the  steam-heads.  The  steam-pipe  s 
has  two  branches  leading  to  the  two  steam-heads.  Of  the  six  ways  or  passages  in  each  steam-head, 
two  1 1'  are  steam-passages  leading  from  the  cock-seats  into  the  channel  f the  former  above  and  the 
latter  below  the  abutment,  (see  the  right-hand  side  of  fig.  1,  Plate  V.) ; re  re'  are  exhaust  passages  leading 
from  the  cylinder  to  the  cock-seats,  the  former  from  above  and  the  latter  from  below  the  abutments 
(see  left-hand  side  of  fig.  1,  Plate  V.).  In  addition  to  the  four  already  described,  one  r leads  from  the  steam- 
pipe  to  the  cock-seat,  and  the  remaining  one  v,  fig.  2,  Plate  V.  is  a continuation  of  the  cock-seat,  provided 
with  a flange  at  its  extremity  for  connecting  to  the  exhaust-pipe.  The  vertical  section,  fig.  1,  is  taken 
through  the  steam-passages  on  the  right  side,  but  through  the  exhaust-passages  on  the  left.  The  plugs 
q q'  have  each  two  passages,  the  first  k,  fig.  2,  being  for  the  purpose  of  communication  between  the 
steam-pipe  and  either  of  the  passages  1 1',  and  admitting  steam  on  either  the  upper  or  lower  side  of  its 
corresponding  abutment,  the  other  l,  in  a hollow  part  of  the  plug,  being  for  forming  a communication 
between  the  exhaust-passage  v,  and  the  opposite  side  of  the  abutment  to  that  which  is  in  communica- 
tion with  the  steam-pipe.  The  two  plugs  q q'  are  furnished  with  levers  (see  Plate  IV.),  by  which  they  are 
turned  to  admit  the  steam  on  either  side  of  the  abutment,  and  allow  the  escape  of  the  exhaust  from  the 
opposite  side,  and  the  levers  are  connected,  so  that  both  are  reversed  at  the  same  instant.  Whatever  re- 
lation, therefore,  exists  between  the  several  passages  in  one  steam-head  and  cock,  the  opposite  relation 
must  exist  between  the  passages  in  the  other.  In  fig.  1,  Plate  V.,  the  cock  on  the  right-hand  side  of  the  fig- 
ure is  in  such  position,  that  steam  is  admitted  through  the  passage  t above  the  abutment,  the  passage  t' 
being  effectually  closed,  while  in  the  same  cock  the  exhaust  passage  u',  imperfectly  represented  by  dotted 
lines  as  being  more  distant  from  the  eye,  is  open,  and  admits  the  exhaust  steam  to  escape  from  the  lower 
side  of  the  abutment  into  the  hollow  portion  of  the  plug  at  its  further  end.  In  the  other  steam-head, 
the  lower  steam  and  the  upper  exhaust  are  supposed  to  be  open,  the  dotted  steam-passages  1 11  being  o~ 
this  side  nearer  the  eye  than  the  exhaust  passages  re  re',  through  which  this  section  is  taken. 

It  will  be  recollected  that  there  is  no  movement  of  these  cocks,  except  in  reversing,  all  the  passages 
being  full  open,  and  the  steam  exerting  its  full  force  in  every  possible  position  of  the  wheel.  The  arrows 
indicate  the  movements  of  the  steam,  and  also  the  direction  in  which  tire  wheel  revolves,  every  particle 
of  steam  expended  being  effective  in  driving  the  wheel,  without  loss  by  filling  any  cavities  uselessly,  as 
in  the  valve  passages  and  clearance  of  every  variety  of  reciprocating  engine. 

It  now  remains  to  describe  the  provision  for  rendering  available  some  portion  of  the  expansive  power 
of  the  steam.  The  spaces  in  the  channel  f between  each  piston  appear  as  if  filled  with  steam  of  full  pres- 
sure, which  is  carried  along  by  the  revolution  of  the  wheel,  and  discharged  into  the  exhaust  passage  of  the 
opposite  steam-head.  This  would  be  the  case  but  for  the  passages  w w',  midway  between  the  steam- 
heads,  through  which  a large  portion  of  the  steam  thus  confined  expands  itself  into  the  second  or  mate 
engine,  which  is  of  similar  construction,  but  containing  only  four  instead  of  eight  pistons.  The  channel 
in  which  the  steam  works  in  the  second  engine  may  also  be  deeper,  and  any  desired  ratio  may  subsist 
between  the  capacities  of  the  two  engines.  Suppose  the  boiler  pressure  to  be  60  lbs.  per  square  inch, 
and  the  capacity  of  the  second  engine  be  twice  that  of  the  first,  steam  from  the  boiler  at  60  lbs.  above  the 
atmosphere,  or  75  lbs.  total  pressure,  is  expanded  in  passing  the  passage  w into  three  times  its  original 
space,  two  volumes  going  over  into  the  second  engine,  while  one  volume  remains  in  the  first.  The  pres- 
sure will  thus  be  reduced,  according  to  the  law  of  Boyle  and  Marriotte,  to  about  t5  = 25  lbs.  total,  or 
10  lbs.  above  the  atmosphere.  The  additional  force,  therefore,  due  to  the  existence  of  the  second  en- 
gine will  be  that  of  10  lbs.  per  inch  upon  a double  area,  or  one-third  that  of  the  first  engine  [10  x 2 
= 60  x •$■].  If  the  engines  are  condensing,  and  exhaust  into  a perfect  vacuum,  the  power  of  the  second 
engine  will  be  two-thirds  that  of  the  first  [25  x 2 =75  x £].  If  the  second  engine  be  only  equal  in  ca- 
cacity  to  the  first,  the  pressure  on  its  pistons  will  be  half  the  boiler  pressure,  or  37-5  lbs. ; and  the  effect 
of  the  second  will  be  one-half  the  first,  when  both  exhaust  into  a vacuum,  or  a little  more  than  one- 
third  when  exhausting  into  the  atmosphere  [37'5  — 15  = 22'5  lbs.  22-5  > 60  x $■].  Any  one  may  read- 
ily calculate  the  effect  of  any  other  ratio  between  the  cylinders,  or  of  any  other  initial  pressure  than  00 
lbs.  The  inventor  prefers  a second  cylinder  of  about  twice  the  capacity  of' the  first. 

A considerable  advantage  to  be  derived  under  some  circumstances  from  the  existence  of  two  engines, 
is  the  possibility  of  using  both  for  a few  minutes  on  any  extraordinary  occasion,  under  full  pressure,  by 
connecting  each  directly  with  the  boiler.  In  Plate  IV.,  a represents  the  first  and  b the  second  engine. 
Under  ordinary  circumstances,  the  stop-valves  c and  d being  open,  the  steam  from  the  boiler  would  be 
admitted  through  e into  a alone,  after  working  through  which,  a portion  would  pass  over  through  the 
stop-valve  d into  the  cylinder  b.  Should  occasion  require  an  extraordinary  effort,  the  valve  d may  be 
closed  and  e opened,  thus  shutting  the  communication  between  the  engines,  and  opening  each  to  the  full 


356 


MARINE  STEAM  ENGINE. 


pressure  of  steam  from  the  boiler.  Both  might  be  thus  worked  so  long  as  the  boiler  could  generate  a 
sufficient  supply  of  steam. 

Compound  Engines  of  the  Steamship  Thorwaldsen  (Plate  VI.),  constructed  by  Messrs.  Oswald  & 
Co.,  of  Sunderland,  Eng.  The  engines  are  of  the  overhead  cylinder  type  with  an  intermediate  receiver, 
the  cylinders — not  steam  jacketed — 51"  and  86"  in  diam.,  with  a stroke  of  3 ft.  6”.  The  inter- 
mediate receiver  surrounds  the  high-pressure  cylinder,  and  is  of  the  same  capacity.  The  valve-chest 
of  the  high-pressure  cylinder  is  situated  at  the  forward  end  of  the  engines,  that  for  the  low-pressure 
cylinder  between  the  cylinders.  The  valves  of  both  cylinders  are  double-ported,  that  for  the  high- 
pressure  cylinder  being  equilibrated  by  a ring  at  the  back. 


High-pressure  cylinder. 

Feet.  Inches. 

Low-pressure  cylinder. 

Feet.  Inches. 

Length  of  ports, 

. 2 

6 

Length  of  ports, . 

. 5 

0 

Width  of  steam  ports, 

. 0 

3»L 

Width  of  steam  ports, 

. 0 

“ exhaust  ports, 

.-  0 

9 

“ exhaust  ports, 

. 0 

91 

The  maximum  travel  of  the  valves  is  in  each  case  8",  and  each  of  the  valves  has  its  weight  counter- 
balanced by  the  pressure  of  the  steam  acting  on  an  8-inch  piston  working  in  a balance  cylinder. 

Besides  the  stroke  of  main  valves  being  adjustable  by  means  of  the  link  motion,  the  high-pressure 
cylinder  is  fitted  with  a separate  expansion-slide  which  works  on  a face  at  the  side  of  the  main  valve 
chest,  and  which  has  an  adjustable  travel.  Eor  starting  the  engines,  or  moving  them  by  hand,  small 
supplementary  slide-valves  are  provided,  at  the  front  of  the  cylinders,  moved  by  hand-levers.  By 
means  of  one  of  these  slides  steam  can  be  admitted  direct  to  the  low-pressure  cylinder. 

Between  the  exhaust-pipe  and  the  low-pressure  cylinder  a chamber  is  interposed,  fitted  with  an 
injection-pipe,  to  form  a feed-heater  by  which  the  temperature  of  the  feed  is  raised  to  about  160°. 

The  circulating  pump  is  driven  by  a prolongation  upward  of  the  air-pump  rod,  both  pumps  being 
actuated  by  back  levers  connected  to  the  crosshead  of  the  low-pressure  cylinder.  To  the  air-pump 
crosshead  are  also  connected  the  feed  and  bilge  pumps,  these  pumps  having  6^-incli  plungers,  and 
stroke  1 ft.  9".  The  air-pump  is  single-acting,  and  has  a diameter  of  36". 

The  piston-rods  are  each  8"  diam.  below  the  piston,  and  they  are  continued  upward,  working 
through  stuffing-boxes  in  the  top  cylinder-covers.  The  crosshead  gudgeons  are  10J-"  in  diameter  by 
11"  long,  and  the  guide-blocks  are  15"  wide  by  2 ft.  5"  long.  The  connecting-rods  are  7 ft.  9"  long, 
and  the  crank-pins  have  bearings  13|"  long  by  13^-"  diam.  The  diameter  of  the  crank-shaft  is  13^-" 
throughout,  with  4 bearings,  and  each  18  inches  long. 

The  thrust  bearing  has  9 collars  placed  l£"  apart,  these  collars  being  each  thick  and  15"  diam. 
outside.  The  diameter  between  the  collars  is  12".  The  intermediate  shafting  is  12"  in  diam.,  with 
bearings  of  the  same  diameter,  and  12'  long,  while  the  propeller  shaft  is  12J"  diam.,  and  the  lignum- 
vitm  bearings  are  14j"  diam.,  and  2 ft.  7"  and  3 ft.  10"  long  respectively. 

The  propeller  is  16  ft.  6”  in  diameter,  and  from  18  feet  to  22  feet  pitch.  The  boss  is  4 feet  in 
diameter,  and  it  has  four  arms,  each  with  an  area  of  14  square  feet. 

The  engines  are  supplied  with  steam  by  four  boilers,  each  12  ft  3"  diam.  by  10  ft.  6"  long.  Each 
boiler  contains  three  furnaces,  each  3 feet  in  diameter.  The  grates  are  6 ft.  6"  long.  The  boiler- 
tubes  are  of  brass  and  are  3§"  diam.  by  7 ft.  long.  The  chimney  is  8 ft.  in  diameter,  and  the  safety- 
valves,  which  are  eight  in  number,  have  each  a diameter  of  4j".  The  main  steam-pipe  is  13",  the 
waste  steam-pipe  114”.  The  main  feed  and  bilge  pipes  are  4j  inches  in  diameter. 

Marine  Engines , by  Mr.  J.  Hall,  Munich,  for  the  tipper  Danube.  Fig.  2804  is  a side  elevation  of  one 
of  the  engines,  with  boiler  and  paddle-wheel,  as  fitted  in  the  vessel.  Fig.  2805  is  a corresponding  trans- 
verse section  through  the  vessel,  showing  both  engines,  with  various  parts  in  section.  The  view  oi: 
the  right  of  the  centre  line  represents  sections  through  the  paddle-box,  air-pump,  feed-pump,  crank  shaft 
journals,  condenser  passage,  and  the  barrel  of  the  boiler — the  cylinders  not  being  shown.  On  the  left, 
the  air-pump  and  paddle-wheel  are  in  elevation,  the  cylinder  being  in  section  through  its  exhaust  passage, 
as  in  connection  with  the  blast-pipe.  Figure  2806  is  a plan  of  the  combined  engines,  one  being  in  hori- 
zontal section.  The  boiler  and  the  fire-box  A B,  are  constructed  just  as  in  a locomotive.  At  C C are 
two  parallel  frames  of  double  boiler  plate,  filled  in  with  timber,  running  along  the  boiler,  and  riveted 
fast  to  it.  D D are  t-wo  similar  frames,  standing  up  from  the  bottom  of  the  boat ; and  these  four  lines 
of  framing  carry,  at  one  end,  the  four  inner  journals  of  the  paddle-shaft,  and  at  the  other  the  pair  of 
steam  cylinders  E E.  The  steam  is  admitted  in  the  usual  way  by  a regulator  in  the  dome,  through  the 
pipe  F,  to  the  steam-chest  G.  The  expansion-vale  spindle  H,  has  a right  and  left-hand  screw  at  1 1, 
each  screw  having  a plain  cut-off  slide,  commanding  the  steam  ports  J,  leading  into  the  second  steam- 
chest  K,  and  fitted  with  piston-valves  worked  by  the  spindle  L The  cut-off  spindle  H,  is  worked  by 
the  outside  eccentric  M,  the  rod  of  which  is  linked  to  it  direct.  The  variation  in  the  expansion  is  ef- 
fected by  the  light  shaft  N,  passing  alongside  the  engines  to  the  engineer’s  hand,  and  having  a bevel 
pinion  O,  gearing  with  a similar  pinion  P,  on  the  transverse  shaft  Q,  passing  across  between  both  en- 
gines. In  this  way  the  shaft  N,  commands  the  valves  of  both  engines  through  the  two  pairs  of  bevel 
pinions  B R — the  result  of  turning  the  shaft  N to  the  right  or  left  being  to  expand  or  approximate  the 
two  cut-off-slides  by  the  right  and  left  screws,  and  thus  increase  or  diminish  the  degree  of  expansion 
without  affecting  the  lead.  The  cylindrical,  or  piston-valve  chest,  has  three  valves  S T and  U,  on  the 
same  rod  V ; and,  as  represented  in  the  horizontal  section,  the  engine  is  upon  its  bottom  centre,  and 
steam  is  entering  between  the  valves  U and  T ; the  valve  U being  on  the  point  of  opening  to  admit 
steam  to  the  cylinder — the  waste  steam  of  the  previous  stroke  having  escaped  by  the  opening  cast  in 
the  middle  of  the  cylinder,  and  through  similar  recesses  formed  in  the  valve  T,  into  the  blast-pipe  W. 
Mow  it  is  to  be  remembered  that  the  valve  U must  travel  downwards  until  its  port  leading  into  the  cyl* 


MARINE  STEAM  ENGINE. 


357 


inder  is  full  open ; and,  as  the  whole  three  valves  are  on  one  rod,  as  U is  opening  to  admit  steam  to  the 
cylinder,  T is  closing  the  communication  between  the  cylinder  and  the  blast-pipe.  So  soon  as  the  ports’ 


1 

i 

=P 

5 

H 

to  the  blast-pipe — which  are  only  half  the  width  of  the  valve — are  closed,  the  other  valve  S opens,  and 
the  remaining  vapor  escapes  through  the  pipes  X,  cast  on  the  steam-chest,  to  the  pipe  Y,  leading  to  the 
condenser  Z.  As  the  expansion  at  each  stroke  commences  at  the  face  of  the  cut-off  slides,  whatever 
amount  of  steam  may  be  in  the  piston-valve  chest  at  the  time  is  also  expanded;  therefore,  to  diminish 
this  amount  as  much  as  possible,  two  additional  pistons  S'  S',  are  fitted  upon  the  valve-rod,  for  the  pur- 


pose of  displacing  the  steam  which  would  otherwise  collect  at  each  stroke  in  the  valve-chest..  The  air- 
pump  a,  is  of  the  ordinary  construction : it  is  bolted  on  to  the  condenser,  and  is  worked  by  the  same  ec- 
centric which  works  the  expansion  valves.  The  piston  steam-slides,  S T and  U,  are  worked  by  the  back 
and  forward  eccentrics  b b,  through  the  reversing  link  c.  The  backward  eccentric  also  works  the  feed- 
pump d — the  feed  being  taken  from  the  hot  well,  whilst  the  remainder  runs  to  waste  by  the  pipe  e. 

The  steam  is  admitted  to  the  cylinder  when  the  piston  is  on  the  centre,  and  is  allowed  to  escape  tc 


358 


MARINE  STEAM  ENGINE. 


the  eduction-port  or  blast-pipe  when  the  piston  is  lfths  inch  from  the  end  of  its  stroke.  The  valve  S 
opens  to  the  condenser  when  the  piston  has  travelled  lfths  inch  from  the  commencement  of  its  stroka 
— the  full  length  of  stroke  being  30  inches — so  that  the  cylinder  is  open  to  the  condenser  when  the  pu 


At  jf  and  g,  two  cocks  are  placed  upon  the  pipe  Y,  leading  to  the  condenser,  and  these  cocks  are  so 
arranged  that  when  one  is  open  the  other  is  shut.  The  injection-pipe  h,  is  placed  between  the  air- 
pump°and  the  cocks  f and  g,  so  that  by  reversing  the  latter  by  means  of  the  rods  and  levers  k k , the  en- 
gine will  work  with  the  condenser  or  without  it.  When  working  without  the  condenser,  the  cylinder  is 
open  to  the  atmosphere  throughout  the  entire  stroke,  as  in  the  common  high-pressure  engine,  and  under 
such  circumstances,  the  pipe  l is  open  to  the  feed-pump,  for  the  boiler  supply.  The  pipe  m,  leads  to  a 
small  steam  pump  not  seen  in  the  drawing,  and  the  pipe  n , conveys  the  water  from  the  steam  pump  to 
the  boiler.  The  pipe  o is  the  blow-off  pipe. 


PL.m. 


MATCHES. 


359 


MATCHES.  The  contrivances  in  which  sulphur  matches  were  inflamed  by  immersion  in  phospho- 
rus (phosphorous  matches)  were  first  superseded  by  the  so-called  chemical  matches,  which  consisted  of 
sulphur  matches,  with  a coating  of  chlorate  of  potash.  This  salt,  when  brought  into  contact  with  con- 
centrated sulphuric  acid  in  the  cold,  is  decomposed  with  explosion  and  the  production  of  fire,  into  bisul- 
phate of  potash,  perchlorate  of  potash,  and  chlorous  acid,  and  by  the  two  latter  (one  of  which  is  re 
solved  into  chlorine  and  oxygen,  and  the  other  into  chloride  of  potassium  and  oxygen)  inflammable 
matters  of  all  kinds,  as  sulphur,  metallic  sulphurets,  resin,  gum,  &c.,  are  inflamed,  when  within  the  im- 
r icdiate  reach  of  its  action.  The  sulphur  ends  of  the  matches  are  covered  with  a composition  of  chlo- 
rate of  potash,  flowers  of  sulphur,  colophony,  gum,  and  cinnabar,  (as  a coloring  matter:)  on  dipping 
this  into  a bottle  containing  asbestus,  previously  moistened  with  sulphuric  acid,  it  quickly  becomes  in- 
flamed. These  matches  are  now  superseded  by  the  more  simple  lueifer  matches,  which  inflame  with- 
out the  aid  of  acid,  or  any  thing  of  the  kind,  by  mere  friction  ; an  invention,  the  history  of  which,  not- 
withstanding its  novelty,  is  already  lost,  partly  on  account  of  its  simplicity,  and  from  the  rapid  intro- 
duction of  similar  processes. 

Lucifer  matches. — These,  like  the  last,  are  sulphur  matches,  to  which  a separate  inflammable  com- 
pound has  been  added.  The  primary  coating  of  sulphur  cannot  be  dispensed  with,  because  the 
inflammable  composition  burns  much  too  rapidly  to  set  fire  to  the  wood.  The  flame  produced  by  the 
combustible  mixture  is,  therefore,  first  communicated  to  the  sulphur,  and  from  it  to  the  wood.  Thu 
mixture  at  first  contained  chlorate  of  potash  as  an  essential  ingredient,  and  the  production  of  fire  de 
pended  upon  the  power  of  this  substance  of  inflaming  the  sulphur,  phosphorus,  &c.,  with  explosion,  the 
effect  being  produced  even  by  shaking  or  friction.  Thus  phosphorus  was  mixed  with  mucilage,  at  a 
temperature  of  104°  F.,  so  as  to  form  an  emulsion,  to  which  the  chlorate  of  potash  was  then  added. 
The  phosphorus  was  sometimes  replaced  by  sulphuret  of  antimony.  The  operation  of  mixing  the  in- 
gredients in  the  dry  state  is  at  all  times  dangerous.  The  unpleasant  noise  which  occurred  whenever  a 
match  was  inflamed,  and  a certain  amount  of  danger  from  fire,  rendered  it  desirable  to  replace  the  de- 
tonating action  of  the  mixture  by  a slow  combustion,  and  this  has  been  accomplished  in  the  noiseless 
lueifer  matches.  None  of  those  compositions  which  inflame  without  explosion  contain  chlorate  of  pot- 
ash, but  nitre  and  phosphorus  instead  ; the  latter  of  which  burns  at  the  expense  of  the  oxygen  of  the 
former.  The  general  principle  concerned  in  the  action  of  these  matches  is,  that  substances  (as  phos- 
phorus) having  a great  affinity  for  oxygen,  are  mixed  with  a large  amount  of  it,  condensed  into  a small 
space,  (in  the  nitre,)  so  that  the  slightest  cause  is  sufficient  to  effect  their  combination.  The  peroxides 
of  lead  and  manganese,  which  abound  in  oxygen,  are  often  mixed  with  the  nitre  ; they  act  in  the  same 
way  when  they  have  once  attained  a red  heat. 

As  the  thickness  of  the  match,  and  the  quantity  of  the  composition  upon  it,  must  always  bear  a cer- 
tain proportion,  both  because  the  latter  is  expensive,  and  burns  with  a disagreeable  odor,  the  matche  ■: 
require  to  be  cut  by  machinery,  or  planes  constructed  for  the  purpose  ; they  are  thus  obtained  thin,  suf- 
ficiently strong,  perfectly  uniform,  and  of  an  elegant  appearance.  Moist  poplar  w'ood  is  best  suited  for 
this  purpose.  The  round  or  angular  matches  are  dipped  in  bundles  into  melted  sulphur,  and  then 
coated  with  the  inflammable  composition  : sixteen  parts  of  gum-arabic,  9 parts  of  phosphorus,  14  parts 
of  nitre,  and  16  of  finely  divided  peroxide  of  manganese,  form  a good  composition,  which  must  be 
worked  up  with  water  to  avoid  danger.  The  mixture  then  forms  a thick  paste,  into  which  the  matches 
are  separately  dipped  and  then  dried.  Occasionally,  smalt  and  similar  matters  are  added,  to  produce 
certain  colors,  or  to  increase  the  effects  of  friction.  After  repeated  trials,  the  inflammability  of  the 
composition  has  been  gradually  diminished  to  such  an  extent,  that  it  only  inflames  when  strongly 
rubbed  against  rough  surfaces,  but  not  readily  by  pressure  or  shaking,  especially  when  the  matches  are 
preserved  in  closed  boxes ; hence  they  are  much  less  dangerous  than  might  be  anticipated.  The  slow 
combustion  of  the  sulphur,  with  the  emission  of  sulphurous  acid,  forms  a great  objection  to  these 
matches,  as  this  gas  is  injurious  to  respiration.  Matches  have  consequently  been  introduced  into  com- 
merce which  have  been  first  dipped  into  fused  stearine,  instead  of  sulphur ; these,  however,  frequently 
miss  fire. 

According  to  Ure,  the  following  process  answers  well : 


Phosphorus 4 parts. 

Nitre 10  “ 

Fine  glue 6 “ 

Red  ochre,  or  red  lead 5 “ 

Smalt 2 “ 


Convert  the  glue,  with  a little  water,  by  a gentle  heat,  into  a smooth  jelly ; put  it  into  a slightly  warm 
porcelain  mortar  to  liquify ; run  the  phosphorus  down  through  this  gelatine  at  a temperature  of  about 
140°  or  150°  F. ; add  the  nitre,  then  the  red  powder,  and  lastly  the  smalt,  till  the  whole  forms  a uni- 
form paste.  To  make  writing-paper  matches,  which  burn  with  a bright  flame,  and  diffuse  an  agreeable 
odor,  moisten  each  side  of  the  paper  with  tincture  of  benzoin,  dry  it,  cut  it  into  slips,  and  smear  one  oi 
their  ends  with  a little  of  the  above  paste  by  means  of  a hair  pencil.  On  rubbing  the  said  end  after 
it  is  dry  against  a rough  surface,  the  paper  will  take  fire  without  the  intervention  of  sulphur. 

T : form  lueifer  wood  matches,  that  act  without  sulphur,  melt  in  a flat-bottomed  tin  pan  as  much 
white  wax  as  will  stand  one-tenth  of  an  inch  deep  ; take  a bundle  of  wooden  matches  free  from  resin, 
rub  their  ends  against  a red-hot  iron  plate  till  the  wood  be  slightly  charred  ; dip  them  now  in  the 
melted  wax  for  a moment,  shake  them  well  on  taking  them  out,  and  finally  dip  them  separately  in  the 
• above  viscid  paste.  When  dry,  they  will  kindle  readily  by  friction. 

For  the  rapid  manufacture  of  the  wooden  splints  for  lueifer  matches,  a patent  was  granted  to 
Mr.  Reuben  Partridge,  in  March,  1842.  He  employs  a perforated  metallic  plate,  having  a steel 
face,  strengthened  by  a bell-metal  back.  The  size  of  the  perforations  must  depend  on  that  of  the 
desired  splints,  but  they  must  be  as  close  together  as  possible,  that  there  msfy  be  a very  small 


360 


MATERIALS. 


blank  space  between  them,  otherwise  the  plate  would  afford  too  great  resistance  to  the  passage  of  the 
wood.  By  this  construction,  the  whole  area  of  the  block  of  wood  may  be  compressed  laterally  into 
the  countersunk  openings,  and  forced  through  the  holes,  which  are  slightly  countersunk  to  favor  the 
entrance  and  separation  of  the  wooden  fibres.  A convenient  size  of  plate  is  three  inches  broad,  six 
inches  long,  and  one  thick.  The  mode  of  pressing  is  by  fixing  the  back  of  the  plate  against  a firm 
resisting  block  or  bearing,  having  an  aperture  equal  to  the  area  of  the  perforations  in  the  plate,  and 
then  placing  the  end  of  the  piece  or  pieces  of  wood  in  the  direction  of  the  grain  against  the  face  of  the 
plate  within  the  area  of  the  perforated  portion.  A plunger  or  lever,  or  other  suitable  mechanical 
agent,  being  then  applied  to  the  back  or  reverse  end  of  the  piece  of  wood,  it  may  be  forced  through  the 
perforations  in  the  plate,  being  first  split  as  it  advances  by  the  cutting  edges  of  th  holes,  and  after- 
wards compressed  and  driven  through  the  perforations  in  the  plate,  coming  out  on  the  opposite  side  or 
back  of  the  plate  in  the  form  of  a multitude  of  distinct  splints,  agreeably  to  the  shapes  and  dimen- 
sions of  the  perforations. 

MATERIALS,  properties  of,  used  in  the  mechanic  arts.  The  following  tables  show,  in  a condensed 
form,  the  characteristics  of  materials. 


Experiments  on  the  direct  Cohesive  Powers  of  various  Materials. 


Names  of  Materials. 


Cohesive 
powers  re- 
duced to  a sq 
inch  rod. 


Experimenters. 


Quoted  from. 


WOODS. 


Oak 

do 

do.  dry  English  from. 

Beech  

do 

Alder 

Chestnut,  Spanish  - .... . 

Ash,  very  dry,  from  ... 

do 

Elm 

Acacia 

Mahogany 

Walnut 

Teak 


Poplar 

Fir 


do. 

Scotch  Pine... 
Norway  Pine . 

Larch 

Cedar 


lbs. 

17.300 
13,950 

j 12,000  ) 
\ 8,000  j 
17,709 
11,500 
14,186 

13.300 

( 17,850  ) 
j 15,784  j 
12,000 
13,489 
20,582 
8,000 
8,130 
15,000 


from  

i 6.641 

to 

] 4,596 

from  

] 13^448  \ 

to 

1 11,000 

METALS. 

STEEL. 

Cast-steel  previously  tilted 

Cast-steel  not  tilted 

Blistered  steel  reduced  per  hammer 
Sheer  steel  reduced  per  hammer. . 

IRON  WIRE. 


Iron  wire 

do.  l-10th  inch  diameter 
do 


8,506 

7,818 

7,287 

10,224 

4,973 


134,256 

68,110 

133,152 

127,632 


113,077 

93,964 

85,797 


Muschenbroek. 

Rondelet. 

Barlow. 

Muschenbroek. 

Barlow. 

Muschenbroek. 

Rondelet. 

Barlow. 

Muschenbroek. 

do. 

do. 

Barlow. 

Muschenbroek. 

Barlow. 

Muschenbroek. 

Barlow. 

Muschenbroek. 

do. 

Rondelet. 

do. 

Muschenbroek. 


Rennie. 

Brown. 

Rennie. 

do. 


Sickengen. 

Telford. 

Button. 


Introd.  ad  Phil.  Nat. 

L’Art  de  Batir,  iv. 

Essay  on  the  Strength  of  Timber. 

Introd.  ad  Phil.  Nat. 

Essay  on  the  Strength  of  Timber. 
Introd.  ad  Phil.  Nat. 

L’Art  de  Batir,  iv. 

Essay  on  the  Strength  of  Timber. 

Introd.  ad  Phil.  Nat. 
do. 
do. 

Essay  on  the  Strength  of  Timber. 

Introd.  ad  Phil.  Nat 

Essay  on  the  Strength  of  Timber. 

Introd.  ad  Phil.  Nat. 

Essay  on  the  Strength  of  Timber. 

Introd.  ad  Phil.  Nat.  i. 
do. 

L’Art  de  Batir,  iv. 
do. 

Introd.  ad  Phil.  Nat.  i 


Phil.  Trans,  for  1813. 
Barlow’s  Essays,  <tc. 
Phil  Trans,  for  1818. 
do. 


Ann.  de  Chimie,  vol.  25. 
Barlow’s  Essay,  p.  245,  2d  ed. 
(Euvres  de  Gauthey,  ii.  p.  153. 


MALLEABLE  IRON  IN  BARS. 

German  bar,  mark  B R,  highest 

results 

Swedish  bar,  highest  result 

German  bar,  mark  L,  highest  result 

Liege  bar,  highest  result 

Spanish  bar 

Oosement  bar,  highest  result 

Swedish  bar  reduced  per  hammer. 


93,069 

88,972 

85.900 
82,839 

81.901 
76,697 
72,064 


Muschenbroek. 

do. 

do. 

do. 

do. 

do. 

Rennie. 


Introd.  ad  Phil.  Nat.  i.  426. 
do. 
do. 
do. 
do. 
do. 

Phil.  Trans.  1818. 


MATERIALS. 


361 


Names  of  Materials. 

Cohesive 
powers  re- 
duced to  a sq. 
inch  rod. 

Experimenters. 

Quoted  from. 

. i 

Common  round  iron 

lbs. 

66,309 

Telford. 

Barlow’s  Essay,  p.  230. 

German  bar,  marked  L 

69,530 

Muschenbroek. 

Introd.  ad  Phil.  Nat.  i.  426 

Common  Staffordshire  bar 

64,580 

Telford. 

Barlow’s  Essay,  p.  230. 

Common  German  bar 

69,133 

Muschenbroek. 

Introd.  ad  Phil.  Nat.  i.  426. 

Swedish  bar  

68,728 

do. 

do. 

Oosement  bar 

68,728 

do. 

do. 

Welsh  bar 

62,079 

Telford. 

Barlow’s  Essay,  p.  230. 

Bar  of  the  best  quality 

66,000 

Rumford. 

Phil.  Mag.  x.  p.  51. 

A bar  of  Welsh,  one  of  Swedish, 
and  one  faggoted  scrap  iron, 

each  gave  a result  of 

00,413 

Telford. 

Barlow’s  Essay,  p.  229. 

The  Swedish  iron  broke  at  a flaw. 

Liege  bar 

62,369 

Muschenbroek. 

Introd.  ad  Phil.  Nat,  i.  426. 

Staffordshire  bar 

57,288 

Telford. 

Barlow’s  Essay,  p.  229. 

German  bar,  marked  B It 

61,361 

Muschenbroek. 

Introd.  ad  Phil.  Nat.  i.  426. 

Bar  (mean  of  S3  experiments) 

61,041 

Perronnet. 

CEuvres  de  Gauthev,  ii.  154. 

Russian  old  sable,  mark  C C If.... 

64,230 

Brown. 

Barlow’s  Essay,  p.  233. 

English  bar  reduced  per  hammer. 

65,872? 

Rennie. 

Phil.  Trans,  for  1818. 

Welsh  bar  (3  experiments) 

60,288 

Brown. 

Barlow’s  Essay,  p.  233. 

Bar  of  good  quality 

66,000 

Rumford. 

Phil.  Mag.  vol.  x.  p.  51. 

Swedish  bar  (3  experiments) 

67,503 

Brown. 

Barlow’s  Essay,  p.  232. 

CAST-IRON. 

Bar,  specific  gravity  7-80 7 

68,295  ? 

Muschenbroek. 

Introd.  ad  Phil.  Nat.  i.  417. 

do.  cast  vertically 

19,488 

Rennie. 

Phil.  Trans,  for  1818. 

do.  cast  horizontally 

18,656 

do. 

do. 

do.  Welsh  pig 

17,565 

Brown. 

Barlow’s  Essay,  p.  235. 

COPPER. 

Wire 

61,228 

Sickingen. 

Ann.  de  Chimie,  xxv.  9. 

Wrought  copper  reduced  b}'  the 

hammer 

33,792 

Rennie. 

Phil.  Trans,  for  1818. 

Cast,  Barbary,  spec.  grav.  8T82... 

22,570 

Muschenbroek. 

Introd.  ad  Phil.  Nat,  i.  417. 

do.  Japan,  do.  do.  8-726... 

20  272 

do. 

do. 

do 

19,072 

Rennie. 

Phil.  Trans,  for  1818. 

PLATINUM. 

Platinum  wire,  spec.  grav.  20-847 . 
do.  do.  

56,473 

Morveau. 

Ann.  de  Chimie,  xxv.  8. 

62,987 

Sickingen. 

do.  p.  9. 

SILVER. 

Silver  wire 

38,257 

do. 

do. 

Silver  cast,  spec.  grav.  11-091 

40,902 

Muschenbroek. 

Introd.  ad.  Phil.  Nat.  417. 

GOLD. 

Gold  wire 

30,888 

Sickingen. 

Ann.  de  Chimie,  xxv.  9. 

Gold  cast,  spec.  grav.  19-238 

20,450 

Muschenbroek. 

Introd.  ad  Phil.  Nat.  i.  417. 

ZINC. 

Zinc  wire 

22,551 

Morveau. 

Ann.  de  Chimie,  lxxi.  194. 

do.  sheet 

16,600 

Tredgold. 

Phil.  Mag.  vol.  i.  p.  422. 

do.  cast 

TIN. 

Tin  wire 

2,689 

Muschenbroek. 

Introd.  ad  Phil.  Nat,  i.  407. 

7,129 

Morveau. 

Ann.  de  Chimie,  lxxi.  194. 

English  block,  cast 

6,650 

Muschenbroek. 

Introd.  ad  Phil.  Nat.  i.  417. 

English,  spec.  grav.  7'295 

5,322 

do. 

do. 

Cast 

4.736 

Rennie. 

Phil.  Trans,  for  1818. 

Banca  tin  cast,  spec.  grav.  7'2165  . 

3,679 

Muschenbroek. 

Introd.  ad  Phil.  Nat,  i.  417. 

Malacca  tin  cast,  do.  6-1250. 

3,211 

do. 

do. 

LEAD. 

Milled  sheet,  spec.  grav.  11-407  .... 

3,328 

Tredgold. 

Phil.  Mag.  vol.  i.  p.  422. 

A\  ire 

3,146 

Muschenbroek. 

Introd.  ad  Phil.  Nat.  i.  452. 

do.  spec.  grav.  11-282  

2,581 

do. 

do. 

do.  

2,547 

Morveau. 

Ann.  de  Chimie,  lxxi.  194. 

Cast  lead 

1,824 

Rennie. 

Phil.  Trans,  for  181S. 

Cast,  English,  spec. grav.  11-479... 

885 

Muschenbroek. 

Introd.  ad  Phil.  Nat.  L 452. 

3G2 


MATERIALS. 


Names  of  Materials. 

Cohesive 
powers  re- 
duced to  a sq. 
inch  rod. 

Experimenters. 

Quoted  from. 

BISMUTH. 

lbs. 

Bismuth  cast,  spec.  grav.  9-810 

3,250 

Muschenbroek. 

Introd.  ad  Phil.  Fat.  i 4 "2 

do.  spec.  grav.  9-926  

3,008 

do. 

do. 

ANTIMONY. 

Antimony  cast,  spec.  grav.  4-500... 

1,006 

do. 

do. 

ALLOYS. 

Copper  10  tin  1,  sp.  gr.  8'351 

32,093 

Muschenbroek. 

Introd.  ad  Phil.  Nat. 

do.  8 do.  1,  do.  8-392 

36,088 

do. 

do. 

do.  6 do.  1,  do.  8-707 

44,071 

do. 

do. 

do.  4 do.  1,  do.  8-723 

35,739 

do. 

do. 

do.  2 do.  1 

1,017 

do. 

do. 

Gun  metal,  hard 

36,368 

Rennie. 

Phil.  Trans,  for  1818. 

Brass,  fine  yellow 

17,968 

do. 

do. 

Tin,  English,  10  lead  1 

6,904 

Muschenbroek. 

do. 

do.  8 do.  1 

7,922 

do. 

do. 

do.  6 do.  1 

7,997 

do. 

do. 

do.  4 do.  1 

10,607 

do. 

do. 

do.  2 do.  1 

7,470 

do. 

do. 

do.  1 do.  1 

7,074 

do. 

do. 

sp.  gr. 

Tin,  Banca,  10  Antimony  1,  7'359 

11,181 

do. 

do. 

do.  8 do.  1,  7-276 

9,881 

do. 

do. 

do.  6 do.  1,  7-228 

12,632 

do. 

do. 

do.  4 do.  1,  7-192 

13,480 

do. 

do. 

do.  2 do.  1,  7T05 

12,029 

do. 

do. 

do.  1 do.  1,  7-060 

3,184 

do. 

do. 

do.  10  bismuth  1,  7'576 

12,688 

do. 

do. 

do.  4 do.  1,  7’613 

16,692 

do. 

do. 

do.  2 do.  1,  8-076 

14,017 

do. 

do. 

do.  1 do.  1,  8-146 

12,020 

do. 

do. 

do.  1 do.  2,  8'580 

10,013 

do. 

do. 

do.  1 do.  4,  9-009 

7,875 

do. 

do. 

do.  10  zinc,  Ind’n,  1,  7'288 

12,914 

do. 

do. 

do.  2 do.  1,  7-000 

15,025 

do. 

do. 

do.  1 do.  1,  7-321 

15,844 

do. 

do. 

do.  1 do.  2,  7-100 

16,023 

do. 

do. 

do.  1 do.  10,  7‘130 

5,671 

do. 

do. 

Tin,  English,  8 do.  Goslar,  1, 

10,607 

do. 

do. 

do.  4 do.  1, 

10,258 

do. 

do. 

do.  2 do.  1, 

10,964 

do. 

do. 

do.  1 do.  1, 

9,024 

do. 

do. 

do.  1 antimony  1,  7'000 

1,450 

do. 

do. 

do.  3 do.  2, 

3,184 

do. 

do. 

do.  4 do.  1, 

11,343 

do. 

do. 

Lead,  Scotch,  1 bismuth  1 , 1 0*93 1 

7,319 

do. 

do. 

do.  2 do.  1,11-090 

5,840 

do. 

do. 

do.  10  do.  1,10-827 

2,826 

do. 

do. 

Experiments  on  the  Pesistance  of  different  Metals  to  Pressure. 


Size  of  prism. 

Name  of  Metal. 

Crushing 

weight 

Remarks. 

Size  of  base.  Height. 

inch.  inch. 

lMth.  l-4th. 

do.  do. 

do.  do. 

do.  do. 

do.  do. 

Cast  copper. 
Brass. 

Wrought  copper. 

Cast  tin. 

Cast  lead. 

lbs. 

7,318 

10,304 

6,440 

966 

483 

Crumbled  by  pressure. 

( Fine  yellow  brass  reduced  onc-tenth  by  3213 
} lbs,  and  one-half  with  10,304  lbs. 
j Reduced  one-sixteenth  with  3427  lbs.,  one- 
I eighth  with  6440  lbs. 

j Reduced  one-sixteenth  with  552  lbs,  one- third 
l with  960  lbs. 

Reduced  one-half  with  483  lbs. 

MATERIALS. 


3G8 


Experiments  on  the  Resistance  of  Cast-iron  to  Pressure. 


Size  of  prism. 

Specific 

Crushing 

zq  of  base. 

Height. 

gravity. 

weight. 

inch. 

inch. 

lbs. 

1-Stll. 

1-8  th. 

7033 

1,454 

do. 

do. 

do. 

1,416 

do. 

do. 

do. 

1,449 

do. 

2-8ths. 

6977 

1,922 

do. 

do. 

do. 

2,310 

do. 

3-8ths. 

do. 

2,363 

do. 

4-8ths. 

do. 

2,005 

do. 

5-8ths. 

do. 

1,407 

do. 

6-8ths. 

do. 

1,743 

do. 

7-8ths. 

do. 

1,594 

do. 

8-8ths. 

do. 

1,439 

l-4th. 

l-4th. 

do. 

10,561 

do. 

do. 

do. 

9,596 

do. 

do. 

do. 

9,917 

do. 

do. 

do. 

9,020 

do. 

do. 

7013 

12,665 

do. 

do. 

do. 

10,720 

do. 

do. 

do. 

10,605 

do. 

do. 

do. 

8,699 

do. 

do. 

7074 

12,665 

do. 

do. 

do. 

10,950 

do. 

do. 

do. 

11,088 

do. 

do. 

do. 

9,844 

do. 

do. 

do. 

11,096 

do. 

l-2d. 

}H 

9,455 

do. 

do. 

9,374 

do. 

do. 

1 7074  j 

9,938 

do. 

do. 

10,027 

do. 

3-8ths. 

7113 

9,006 

do. 

5-8ths. 

do. 

8,845 

do. 

6-8  ths. 

do. 

8,362 

do. 

7-8ths. 

do. 

6,430 

do. 

8-8ths. 

do. 

6,321 

do. 

3-8ths. 

7074 

9,328 

do. 

5-8ths. 

do. 

8,385 

do. 

6-8ths. 

do. 

7,896 

do. 

7 -8  ths. 

do. 

7,018 

do. 

8-8ths. 

do. 

6,430 

Mean  from 
each  set. 


Remarks. 


lbs. 


| 1,440  | 
[ 2,116 

1,758  | 


| 9,773  | 
10,114  | 
11,136  | 


,414 


f “• 

t 9,982 


These  specimens  were  from  one 
block. 

Iron  from  a block. 


These  specimens  were  from  the 
same  block. 


These  specimens  were  from  the 
same  block  as  the  above. 


These  specimens  were  from  hori- 
zontal castings. 


These  specimens  were  vertical 
castings. 


Horizontal  casting. 
Vertical  casting. 

Horizontal  castings. 
Vertical  castings. 


The  Experimental  Strength  of  various  species  of  Timber  opposed  to  a Transverse  Strain. 


Kinds  of  Wood. 

Specific 

Gravity. 

Length  in 
feet. 

Breadth 

in 

inches. 

Depth  in 
inches. 

Deflec- 
tion at 
the  time 
of  frac- 
ture. 

Break- 

ing 

weight 
in  lbs. 

Value  of 
constant 
strength. 

Authorities. 

Oak,  English,  young  tree 

•863 

2* 

i 

i 

1-87 

482 

2892 

Tredgold. 

l)o.  old  ship  timber 

•872 

2*5 

i 

i 

1-5 

264 

1980 

do. 

Do.  from  old  tree  

•625 

2* 

i 

i 

1-38 

218 

1308 

do. 

Do.  medium  quality 

•748 

2-5 

i 

i 

284 

2130 

Ebbels. 

Do.  green  

•763 

2-5 

i 

i 

219 

1741 

do. 

Do.  do 

1-063 

11*75 

8‘5 

8-5 

3-2 

24812 

1785 

Buffon. 

Beech,  medium  quality 

•690 

2-5 

i 

1 

271 

2031 

Ebbels. 

Alder 

'555 

2-5 

i 

1 

212 

1590 

do. 

Plane  tree 

•648 

2'5 

i 

1 

243 

1821 

do. 

Sycamore  

•590 

2-5 

i 

1 

214 

1605 

do. 

Chestnut  tree 

■875 

2-5 

i 

1 

180 

1350 

do. 

Ash,  from  young  tree 

•811 

2-5 

i 

1 

2-5 

324 

2430 

Tredgold. 

Do.  medium  quality 

•690 

2-5 

i 

1 

254 

1905 

Ebbels. 

Ash 

■753 

2'5 

i 

1 

2-38 

314 

2355 

Tredgold. 

Elm,  common 

•544 

2-5 

i 

1 

216 

1620 

Ebbels. 

Do.  weych,  green 

•763 

2-5 

i 

1 

192 

1440 

do. 

Acacia,  green 

•820 

2-5 

i 

1 

249 

1866 

do. 

Mahogany,  Spanish,  seasoned. 

•862 

2-5 

i 

1 

170 

1275 

Tredgold. 

Do.  Honduras,  seasoned 

•256 

2 5 

i 

1 

255 

1911 

do. 

364 


MATERIALS. 


Exhibiting  the  Experimental  Strength  of  various  Species  of  Timber,  etc. — Cont  inued. 


Kinds  of  Wood. 

Specific 

Gravity. 

Length  in 
feet. 

Breadth 

in 

inches. 

Depth  in 
inches. 

Deflec- 
tion at 
the  time 
of  frac- 
ture. 

Break- 

ing 

weight 
in  lbs. 

Value  of 
constant 
strength. 

Authorities. 

Walnut,  green 

•925 

2-5 

i 

i 

195 

1461 

Ebbels. 

Poplar,  Lombardv 

•375 

2*5 

i 

i 

131 

981 

do. 

Do.  Abele  

•511 

25 

i 

i 

1-5 

228- 

1710 

Tredgold. 

Teak  

•744 

7 

2 

2 

4-00 

820 

2151 

Barlow. 

Willow  

•405 

25 

i 

i 

3 

146 

1095 

Tredgold. 

Birch  

■720 

2-5 

i 

i 

207 

1551 

Ebbels. 

Cedar  of  Libanus,  dry  

•586 

* 2-5 

i 

i 

2-75 

165 

1236 

Tredgold. 

Riga  fir 

•480 

2-5 

i 

i 

1-3 

212 

1590 

do. 

Memel  fir  

•553 

2 5 

i 

i 

1-15 

218 

1635 

do. 

Norway  fir  from  Longsound  ... 

•639 

2 

i 

i 

1-125 

396 

2376 

do. 

Mar  forest  fir  

■715 

7 

2 

2 

55 

360 

945 

Barlow.  i 

Scotch  fir,  English  growth 

•529 

25 

i 

i 

1-75 

233 

1746 

Tredgold. 

Do.  do.  . 

•460 

2-5 

i 

i 

157 

1176 

Ebbels. 

Christiana  white  deal 

•512 

2 

i 

i 

•937 

343 

2058 

Tredgold. 

American  white  spruce 

•465 

2 

i 

i 

1-362 

285 

1710 

Spruce  fir,  British  growth 

•555 

2-5 

i 

i 

186 

1395 

Ebbels. 

American  pine  

•460 

2-0 

i 

i 

1-125 

329 

1974 

TrecVold. 

Larch,  choice  specimen 

•640 

2-5 

i 

i 

3-0 

253 

1896 

do. 

Do.  medium  quality 

•622 

2-5 

i 

i 

223 

1671 

do. 

Do.  very  young  wood 

•396 

2-5 

i 

i 

1-78 

129 

966 

do. 

English  oak.. 

•934 

7 

2 

2 

8-1 

637 

1672 

Barlow. 

Canadian  do 

•872 

7 

2 

2 

60 

673 

1766 

do. 

Dantzic  do 

•756 

7 

2 

2 

4-86 

560 

1457 

do. 

Adriatic  do 

•993 

7 

2 

2 

5-73 

526 

1383 

do. 

Ash  

•760 

7 

2 

2 

8-92 

772 

2026 

do. 

Beech 

■696 

7 

2 

2 

5-73 

593 

1556 

do. 

Pitch  pine  

•660 

7 

2 

2 

6-00 

622 

1632 

do. 

Red  pine 

•657 

7 

2 

2 

5-83 

511 

1341 

do. 

New  England  pine 

■553 

1 

2 

2 

4*66 

420 

1102 

do. 

Of  Experiments  on  the  Stiffness  of  different  Woods. 


Kinds  of  Wood. 

Specific 

Gravity. 

Length  in 
feet. 

Breadth 

in 

inches. 

Depth  in 
inches. 

Deflec- 

tion. 

Weight 
which 
produ- 
ced de- 
flection. 

Value  of  a 
from  a — 
40  bd?Z 

h w 

Authorities. 

Ash,  young  tree,  white  colored 

•811 

2-5 

i 

i 

0*5 

141 

•009 

Tredgold. 

Do.  old  tree,  red  colored 

•753 

2 5 

i 

i 

0*5 

113 

•0113 

do. 

Do.  medium  quality 

•690 

2-5 

i 

i 

0*5 

78-5 

■0163 

Ebbels. 

Ash 

■760 

7 

2 

2 

1-27 

225 

•0105 

Barlow. 

Beech  

•688 

7 

2 

2 

1-025 

150 

•01277 

do. 

Teak  

•744 

7 

2 

2 

1-276 

300 

■0076 

do. 

Elm | 

•540 

2-5 

2 

2 

1-42 

125 

•0212 

do. 

•544 

2-5 

i 

i 

0-5 

99-5 

•0128 

Ebbels. 

Cedar  of  Libanus 

•486 

2-5 

i 

i 

0*5 

36 

•0355 

Tredgold. 

Maple,  common  

Abele  

•625 

2-5 

i 

i 

0*5 

65 

■0197 

do. 

■511 

2-5 

i 

i 

0*5 

84 

•0152 

do. 

Willow  

•405 

2-5 

i 

i 

0-5 

41 

•031 

do. 

Horse  chestnut 

•483 

2-5 

i 

i 

0-5 

79 

•0162 

do. 

Lime  tree  

■483 

2-5 

i 

i 

0-5 

84 

•0152 

do. 

Walnut,  green 

•920 

2-5 

i 

i 

0-5 

62 

•020 

Ebbels. 

Chestnut,  Spanish 

•895 

2-5 

i 

i 

0*5 

68-5 

•0187 

do. 

Acacia 

•820 

2-5 

i 

i 

0-5 

125 

■0102 

do. 

Plane,  dry 

•648 

2*5 

i 

i 

0*5 

995 

■0128 

do. 

Alder,  do 

■555 

2-5 

i 

i 

0*5 

80-5 

•0159 

do. 

Birch,  do 

■720 

2-5 

i 

i 

05 

90-5 

•0141 

do. 

Wycli  elm,  green 

•763 

2-5 

i 

i 

0*5 

92 

•014 

do. 

Lombardy  poplar,  dry 

•374 

2*5 

i 

i 

0*5 

56-5 

•0224 

do. 

Mahogany,  Honduras 

•560 

2-5 

i 

i 

0-5 

118 

•0109 

Tredgold. 

Do.  Spanish  

•853 

2-5 

i 

i 

05 

93 

•0137 

do. 

Sycamore  

•590 

2-5 

i 

i 

0*5 

76 

•0168 

Ebbels. 

Pear,  green 

•792 

2-5 

i 

i 

0*5 

59-5 

•0215 

do. 

Cherry,  do 

•690 

2-5 

i 

i 

0*5 

92-5 

•0138 

do. 

Beech,  dry 

•696 

2 5 

i 

i 

0-5 

97-5 

•0131 

do. 

MATERIALS. 


365 


Of  Experiments  on  the  Stiffness  of  Fir. 


Kinds  of  Fir. 

Specific 

Gravity. 

| 

Length  in 
feet. 

Breadth 

in 

inches. 

Depth  in 
inches. 

Deflec- 
tion in 
inches. 

Weight 
producing 
the  de- 
flection in 
lbs. 

Value  of  a 
from 
40  bd?S 

P w 

Authorities. 

Fir,  Riga,  yellow  medium 

Do.  Norway 

Do.  Riga,  yellow  

iDo.  Memel  medium  

American  pine  

White  spruce,  Christiana  

Do.  Quebec 

Pitch  pine  

Fir,  New  England  

Riga  fir  

Mar  forest,  Scotland 

Larch,  Blair,  Scotland,  dry  .... 

Do.  seasoned  medium  

Do.  very  young  wood 

Scots  fir 

Spruce,  British  

Fir,  (bois-disbrin)  

Do.  do.  

.6398 
j -480 
| -464 
t -553 
\ -544 
l -460 
l -407 
■512 
■465 
•712 
•560 
•765 
•715 
•622 
$ -644 
\ 554 
•396 
•529 
•555 

1-8 

2 

25 

2-5 

2'5 

25 

2 

3 

o 

2 

7 

7 

7 

7 

2'5 

25 

25 

2-5 

25 

2'5 

21-3 

10'65 

2 

1 

1 

1 

1 

1 

1 

1 

1 

1 

2 

2 

2 

2 

1 

1 

1 

1 

1 

1 

10-48 

10-58 

7 

1 

1 

1 

1 

1 

1 

1 

1 

1 

2 

2 

2 

2 

1 

1 

1 

1 

1 

1 

10-48 

10-48 

0-25 

0-5 

0-5 

0-5 

0’5 

0-5 

0-5 

05 

0- 5 
0'5 

1- 33 
■970 
•912 

1‘560 

0'5 

0’5 

0-5 

0'5 

0- 5 
0'5 

1- 02 
0-2245 

103 

261 

123 

116 

143 

145 

237 

69 

261 

180 

150 

150 

150 

125 

93 

101 

112 

45 

89 

93 

4-389 

4-122 

•0015 

•00957 

•0102 

•0110 

•0089 

•0088 

•0105 

•0112 

•00957 

•0130 

•0166 

•0121 

•01137 

•0233 

•0137 

•0126 

■0111 

•0284 

•01437 

•0124 

•0115 

•0220 

Tredgold. 

Do. 

Do. 

Ebbels. 

) | 
> Tredgold.; 

s ° 

( Do. 

Do. 

Do. 

Barlow. 

Do. 

Do. 

Do. 

Tredgold. 

Do. 

Ebbels. 

Tredgold. 

Do. 

Ebbels. 

Girard. 

Do. 

Experiments  on  the  Resistance  of  various  Materials  to  a Crushing  Force. 


Names  of  Materials. 

Specific 

Gravity. 

Crushing 

weight. 

1.  Elm,  cube  of  1 inch 

lbs. 

1284 

2.  American  pine,  do 

1606 

3.  White  deal,  do.  

1928 

4.  English  oak,  do 

3860 

5.  Portland  stone,  2 inches  long 

805 

6.  Statuary  marble,  1 inch  

3216 

7.  Craigleith,  do 

8688 

8.  Chalk,  cube  of  1 J inch  

1127 

9.  Brick,  pale  red,  do  

2085 

1265 

1 0.  Roe-stone,  Gloucestershire,  do 

1449 

11.  Red  brick,  do.  

2168 

1817 

1 2.  Do.  Hammersmith  pavior’s  do 

2254 

13.  Burnt  do.  

3243 

14.  Fire  brick,  do.  

3864 

15.  Derby  grit,  do.  

2316 

7070 

16.  Do.  another  specimen,  do 

2428 

9776 

17.  Killaly  white  freestone,  do 

2423 

10264 

18.  Portland  do 

2428 

102S4 

19.  Craigleith  white  freestone,  do 

2452 

12346 

20.  Yorkshire  paving  with  the  strata,  do.  

2507 

12856 

21.  Do.  do.  against  strata,  do :. 

12856 

22.  White  statuary  marble,  do 

2760 

13632 

23.  Bramlev  Fall  sandstone,  do 

2506 

13632 

24.  Do.  against  strata,  do 

1 3632 

25.  Cornish  granite,  do 

2662 

14302 

26.  Dundee  sandstone,  do 

2530 

14918 

27.  Portland,  a two  inch  cube  

2423 

14918 

28.  Craigleith,  with  the  strata,  1^  inch  cube 

2452 

15860 

29.  Devonshire  red  marble 

16732 

30.  Compact  limestone  

2584 

17354 

31.  Granite  Peterhead 

18636 

32.  Black  compact  limestone  

2598 

19924 

33.  Purbeck 

2599 

2528 

20610 

21254 

34.  Freestone,  very  hard 

35.  Black  Brabant  marble  

2697 

20742 

- 36.  White  Italian  marble  

2726 

21783 

1 37.  Granite,  Aberdeen,  Blue  kind  

2625 

24556 

3G6 


MATERIALS. 


Of  Experiments  on  the  Stiffness  of  Oaf. 


Kinds  of  Oak. 

Specific 

Gravity. 

Length  in 
feet. 

Breadth 

in 

inches. 

Depth  in 
inches. 

Deflec- 
tion in 
inches. 

Weight 
producing 
the  de- 
flection in 
lbs. 

Values  of 
a from 
40  bd?S 
12  W 

Authorities. 

X 

-I 

to 

2-5 

i 

i 

0-5 

127 

•00998 

Tredgold. 

Do. 

Oak  from  young  tree,  King’s 

•863 

2* 

i 

i 

0-5 

237 

•0105 

Oak  from  Beaulieu,  Hants  .... 

•616 

•736 

2*5 

2*5 

i 

i 

1 

1 

0-5 

0-5 

78 

65 

■0164 

•0197 

Do. 

Do. 

•625 

2 

i 

i 

103 

■0240 

Do. 

•688 

o 

i 

1 

233 

•0107 

*0119 

Do. 

•960 

7 

2 

2 

1-275 

270 

Barlow. 

Do. 

•867 

7 

2 

9 

1-07 

225 

•009 

■787 

7 

2 

9 

1-26 

208 

•0105 

Do. 

■948 

7 

2 

9 

150 

•0193 

•763 

1 

1 

0-5 

0*5 

96 

*0133 

•755 

2-5 

1 

1 

148 

•0087 

•008 

12-8 

.3-19 

3-19 

\ 1-06 

268 

| Aubry. 

6-87 

5-3 

5-3 

( 4-25 
•433 

803 

7587 

•0105 

•005 

Do.  do 

23'58 

53 

5-3 

2-7 

706 

•0095 

Do. 

Do. 

8-52 

5-06 

6-22 

0-709 

4146 

■0013 

1606 

10-66 

11-73 

0-67 

•02 1 3 

Do 

Oak 

9 

1 

1 

0-35 

149 

•0117 

Tredgold. 

Do. 

|Do 

9 

1 

1 

0-35 

167 

•0104 

Experiments  on  the  Resistance  of  Seasoned  Oak  Beams  to  Forces  pressing  in  the  direction  of  their  lengths. 


Kind  of  Wood. 

fcO 

►3 

Breadth  in  inch. 

Depth  in  inches. 

Oak  seasoned  . ... ^ 

2.125 

2-126 

2-126 

Do 

4-25 

2T26 

2-126 

Do 

6-375 

2-126 

2-120 

Do 

2-125 

3-18 

ST8 

Do 

4-25 

SIS 

3-18 

Do 

6-375 

3-18 

3-18 

Do 

2.125 

4-25 

4-25 

Do 

4-25 

4-25 

4-25 

Do 

6-375 

4-25 

4-25 

o 

CD 

6 3 
■~3  o 

O £ 

IT-3 

■—  QJ 

'o  ^ 

Proportional 

elasticity. 

Duration  of  the 
experiments  in 
hours. 

’3  o 
p 

3 

•0787 

7,856 

•0006 

4 

15-631 

•03937 

13,525 

•00033 

6 

21-296 

•1181 

14,119 

•00032 

18 

19-993 

•03937 

11,750 

•00042 

8 

21-060 

-0787 

6,298  7 

r - 1 

11-844 

•1574 

6,298  1 

1 27 

12-225 

•1574 

6,298  | 

1 

13565 

•1574 

6,298  J 

l 6 

12-458 

•1574 

3,277 

•00015 

6 

7-244 

•1574 

2,860 

•00018 

7-484 

■2361 

2,750  j 

5 

8-492 

•1574 

2,750  j 

7-878 

•0787 

34,599 

•0007 

27 

50-958 

"03937 

45,168 

•0006 

24 

50-958 

•1574 

20,317 

•0003 

29 

43-639 

■1574 

18,647 

•00031 

5 

36'865 

•19685 

20,578 

•0003 

9 

36-205 

•27559 

21,819 

•00026 

17 

28-182 

•1574 

9,121 

•00028 

7 

26-939 

•19685 

9,713 

•00027 

19 

28-987 

•0787 

11,000 

•00023 

4 

23-929 

■2361 

10,142 

•00025 

18 

33-048 

•1574 

12,746 

•0002 

6 

36-902 

•0787 

61,883 

•00118 

11 

95-262 

•03937 

56,691  ) 

8 

66-112 

•03937 

56,693  J 

23 

105-826 

•0787 

67,467 

•00107 

28 

94-476 

•03937 

57,780 

•00125 

30 

88-442 

•03937 

63,066 

•00027 

8 

100-755 

•0787 

29,695 

•0006 

5 

85-998 

•0787 

50,525 

•00035 

19 

73-238 

•03937 

45,201 

•0004 

19 

96-368 

•1574 

21,589 

•00038 

7 

64-090 

•2361 

17,331 

■00047 

5 

59-373 

•1574 

IS, 517 

•00044 

oo 

54-062 

•2361 

27,599 

■0003 

22 

65-608 

► Lamande. 

- Do. 

Do. 

Do. 

- Do. 

- Do. 

Do. 

■ Do. 


{-  Do. 


MECHANICAL  POWERS. 


3G7 


On  the  Elasticity  of  various  Woods,  as  computed  by  Mr.  Tredgold. 


Kinds  of  Wood. 


English  oak 

Beech  

Alder  

Chestnut,  green 

Ash  

Elm  

Acacia 

Mahogany,  Spanish 


Elasticity 


0'0015 

0-00195 

0-0023 

0-00267 

0-00168 

0-00184 

0-00152 

0-00205 


Kinds  of  Wood. 

Elasticity 
= e. 

0-00161 

0-00118 

00063 

Riga  fir 

0-00152 

Memel  fir 

0-00133 

0-00142 

000157 

0-0019 

MEAN.  A middle  state  between  two  extremes ; thus  we  say,  arithmetical  mean  is  half  the  sum  of 
any  two  quantities  : as  <—z — = arithmetical  mean  between  a and  b. 


Geometrical  mean  is  the  square  root  of  the  product  of  any  two  quantities  ; that  is,  a b is  the  geo- 
metrical mean  between  a and  b. 

MEASURE.  Measure  denotes  any  certain  quantity  with  which  other  homogeneous  quantities  are 
compared. — See  Weights  and  Measures. 

MECHANICAL  POWERS.  Power  is  a compound  of  weight,  multiplied  by  its  velocity  ; it  cannot 
be  increased  by  mechanical  means. 

The  weight  is  the  resistance  to  be  overcome,  the  power  is  the  requisite  force  to  overcome  that  resist- 
ance. When  they  are  equal,  no  motion  can  take  place. 

The  powers  are  three  in  number,  viz.,  Lever,  Inclined  Plane,  and  Pulley. 

Note. — The  wheel  and  axle  is  a continual  or  revolving  lever,  the  wedge  is  a double  inclined  plane, 
and  the  screw  is  a revolving  inclined  plane. 


Lever. — When  trie  f ulcrum  (or  support)  of  the  lever  is  between  the  weight  and  the  power. 

Rule. — Divide  the  weight  to  be  raised  by  the  power,  and  the  quotient  is  the  difference  of  leverage, 
or  the  distance  from  the  fulcrum  at  which  the  power  supports  the  weight. 

Or,  multiply  the  weight  by  its  distance  from  the  fulcrum,  and  the  power  by  its  distance  from  the 
same  point,  and  the  weight  and  power  will  be  to  each  other  as  their  products. 

Example. — A weight  of  1600  lbs.  is  to  be  raised  by  a force  of  80  lbs. ; required  the  length  of  the 
longest  arm  of  the  lever,  the  shortest  being  1 foot. 


1600X1 

80 


= 20  feet,  A ns. 


Proof,  by  second  rule. 

1600X  1 =1600. 

80X20  = 1600. 

Example. — A weight  of  2460  lbs.  is  to  be  raised  with  a lever  7 feet  long  and  300  lbs. ; at  what  part 
of  the  lever  must  the  fulcrum  be  placed  ? 

2460  7X12  84 

7 — 8-2  ; that  is,  the  weight  is  to  the  power  as  8’2  to  1 ; therefore  the  whole  length  - — - — = — = 

300  ’ ’ 13  1 ’ ° 8-2  + 1 9-2 

9-13  inches,  the  distance  of  the  fulcrum  from  the  weight. 

Example. — A weight  of  400  lbs.  is  placed  1 5 inches  from  the  fulcrum  of  a lever  ; what  force  will 
raise  it,  the  length  of  the  other  arm  being  10  feet? 

400x15  rn  IK  < 

= 50  lbs.,  A ns. 

120 


Note. — Pressure  upon  fulcrum  equal  the  sum  of  weight  and  power. 


When  the  fulcrum  is  at  one  extremity  of  the  lever,  and  the  power,  or  the  weight,  at  the  other. 

Ride. — As  the  distance  between  the  power  or  weight  and  fulcrum,  is  to  the  distance  between  the 
weight  or  power  and  fulcrum,  so  is  the  effect  to  the  power,  or  the  power  to  the  effect. 

Example. — What  power  will  raise  1500  lbs.,  the  weight  being  5 feet  from  it,  and  2 feet  from  the 
fulcrum  ? 

5 + 2 = 7 : 2 : : 1500  : 428-5714  + Ans. 

Example. — What  is  the  weight  on  each  support  of  a beam  that  is  30  feet  long,  supported  at  both 
ends,  and  bearing  a weight  of  6000  lbs.  10  feet  from  one  end  ? 

30  : 20  : : 6000  : 4000  lbs.  at  the  end  nearest  the  weight ; and 
30  : 10  : : 6000  : 2000  lbs.  at  the  end  farthest  from  the  weight. 

Note. — Pressure  upon  fulcrum  is  the  difference  of  the  weight  and  the  power. 

The  General  Rule,  therefore,  for  ascertaining  the  relation  of  Power  to  Weight  in  a lever,  whether 
it  be  straight  or  curved,  is,  the  power  multiplied  by  its  distance  from  the  fulcrum,  is  equal  to  the  weight 
multiplied  by  its  distance  from  the  fulcrum. 


368 


MECHANICAL  POWERS. 


Let  P be  called  the  power,  W the  weighty  the  distance  of  P from  the  fulcrum,  and  w the  distance 
of  W from  the  fulcrum  ; then 


and 


P : W : ; w : p,  or  P Xp  = WX»; 


1YX» 


P Xp  _ 


w. 


-='[>■ 


P Xp 

~W~w' 


If  several  weights  or  powers  act  upon  one  or  both  ends  of  the  lever,  the  condition  of  equilibrium  is 
PXp-f  P'Xjo'  + P "Xp",  <fec.,  = WX»  + W'Xai',  Ac. 

In  a system  of  levers,  either  of  similar,  compound,  or  mixed  kinds,  the  condition  is 

P XpXp'Xp"  _w 
wXw'Xw" 

Let  P = 1 lb.,  p and  p'  each  10  feet,  p"  1 foot ; and  if  w and  w'  be  each  1 foot,  and  w"  1 inch,  then 

1X120X120X12  172800 

- = = 1200 ; that  is,  1 lb.  will  balance  1200  lbs.  with  levers  of  the  lengths 

11!  X 1-iXI  1 44 

above  given. 

Note. — The  weights  of  the  levers  in  the  above  formulae  are  not  considered,  the  centre  of  gravity  being 
assumed  to  be  over  the  fulcrums. 

If  the  arms  of  the  lever  be  equally  bent  or  curved,  the  distances  from  the  fulcrum  must  be  measured 
upon  perpendiculars,  drawn  from  the  lines  of  direction  of  the  weight  and  power,  to  a line  running  hori- 
zontally through  the  fulcrum ; and  if  unequally  curved,  measure  the  distances  from  the  fulcrum  upon  a 
line  running  horizontally  through  it  till  it  meets  perpendiculars  falling  from  the  ends  of  the  lever. 

Wheel  and  Axle.— The  power  multiplied  by  the  radius  of  the  wheel  is  equal  to  the  weight  multi- 
plied by  the  radius  of  the  axle. 

As  the  radius  of  the  wheel  is  to  the  radius  of  the  axle,  so  is  the  effect  to  the  power. 

When  a series  of  wheels  and  axles  act  upon  each  other,  either  by  belts  or  teeth,  the  weight  or  velocity 
will  be  to  the  power  or  unity  as  the  product  of  the  radii,  or  circumferences  of  the  wheels,  to  the  product 
of  the  radii,  or  circumferences  of  the  axles. 

Example. — If  the  radii  of  a series  of  wheels  are  9,  6,  9,  10,  and  12,  and  their  pinions  have  each  a 
radius  of  6 inches,  and  the  weight  applied  be  10  lbs.,  what  weight  will  it  raise  ? 

10X9X6X9X10X12  ... 

= 75  lbs.  weight. 

6X6X6X6X6  ° 

Or,  if  the  1st  wheel  make  10  revolutions,  the  last  will  make  75  in  the  same  time. 

To  find  the  power  of  cranes,  &c. 

Rule. — Divide  the  product  of  the  driven  teeth  by  the  product  of  the  drivers,  and  the  quotient  is  the 
relative  velocity,  which,  multiplied  by  the  length  of  the  winch  and  the  force  in  lbs.  and  divided  by  the 
radius  of  the  barrel,  will  give  the  weight  that  can  be  raised. 

Example. — A force  of  18  lbs.  is  applied  to  the  winch  of  a crane,  the  length  being  8 inches ; the  pinion 
Unving  6,  the  wheel  72  teeth,  and  the  barrel  6 inches  diameter. 

-^  = 12X8X18  = 1728-1-3  = 576  lbs.  weight. 


Let  w represent  length  of  winch, 
r “ radius  of  barrel, 

P “ force  applied, 

v “ velocity, 

W “ weight  raised. 


i^=W. 

r 

W r = v w P. 
— = P. 

V w 


Example. — A weight  of  94  tons  is  to  be  raised  360  feet  in  15  minutes,  by  a force  the  velocity  cl 
which  is  220  feet  per  minute  ; what  is  the  power  required  ? 

= 24  feet  per  minute. 

15  1 


24X94 


= 10'2542  tons. 


220 

In  a wheel  and  axle,  where  the  axle  has  two  diameters,  the  condition  of  equilibrium  is 

W : P ::  R : i(r  — r'); 
or,  P X R ==  W X i (r  — r'); 

that  is,  the  weight  is  to  the  power  as  the  lever  by  which  the  power  works,  is  to  half  the  difference  of 
the  radii  of  the  axle  ; 

R representing  radius  of  wheel, 

r “ radius  of  large  axle, 

r'  “ radius  of  less  axle. 

Inclined  Plane. — Rule. — As  the  length  of  the  plane  is  to  its  height,  so  is  the  weight  to  the  power. 


MECHANICAL  POWERS. 


369 


Example. — Required  the  power  necessary  to 
feet  high. 

As  G : 4 : : 


raise  1000  lbs.  up  an  inclined  plane  6 feet  long  and  4 
1000  : GG6-66  Ans. 


Let  W represent  weight, 

h “ height  of  plane, 

l “ length  of  plane, 

P “ power, 

b “ base  of  plane, 

p'  “ pressure  on  plane. 


W X h 

h 

Wx6 


To  find  the  length  of  the  base,  height,  or  length  of  the  plane,  when  any  two  of  them  are  given. 

Rule. — For  the  length  of  the  base,  subtract  the  square  of  the  height  from  the  square  of  the  length  ol 
the  plane,  and  the  square  root  of  the  remainder  will  be  the  length  of  the  base. 

For  the  length  of  the  plane,  add  the  squares  of  the  two  other  dimensions  together,  and  the  square  root 
of  their  sum  will  be  the  length  required. 

For  the  height,  subtract  the  square  of  the  base  from  the  square  of  the  length  of  the  plane,  and  the 
square  root  of  the  remainder  is  the  height  required. 

Example. — The  height  of  an  inclined  plane  is  20  feet,  and  its  length  100  ; what  is  its  base,  and  the 
pressure  of  1000  lbs.  upon  the  plane  ? 


n/'202  — 1002  = 9 6 00  = 97'98  the  base. 

As  100  : 20  : : 1000  : 200  lbs.  necessary  power  to  raise  the  1000  lbs.,  and 


loooxopgs 

100 


: 979'8  the 


pressure  upon  the  plane. 

If  two  bodies  on  two  inclined  planes  sustain  each  other  by  the  aid  of  a cord  over  a pidley,  their  weights 
are  directly  as  the  lengths  of  the  planes. 

Example. — -If  a body  of  50  lbs.  weight,  upon  an  inclined  plane  of  10  feet  rise  in  100,  be  sustained  by 
another  weight  on  an  opposite  plane  of  10  feet  rise  to  90  of  an  inclination,  what  is  the  weight  of  the 
latter  ? 

As  100  : 90  : : 50  : 45,  the  answer. 


When  a body  is  supported  by  two  planes,  and  if  the  weight  be  represented  by  the  sine  of  the  angle 
between  the  two  planes.  The  pressures  upon  them  are  reciprocally  as  the  sines  of  the  inclinations  of 
those  planes  to  the  horizon,  viz. : 

The  weight,  ) ( Sine  of  the  angle  between  the  planes. 

The  pressure  upon  one  plane,  V are  as  ■<  Sine  of  the  angle  of  one  plane. 

The  pressure  upon  the  other  plane,  ) ( Sine  of  the  angle  of  the  other  plane. 

Thus,  if  the  angle  between  the  planes  was  90°,  of  one  pilane  60°,  and  the  other  80° — since  the 

natural  sines  of  90°,  60°,  and  30°  are  1,  "866,  and  ’500 — if  the  body  weighed  100  lbs.,  the  pressure  upon 
the  plane  of  30°  would  be  86'6  lbs.,  and  upon  the  plane  of  60°,  50  lbs.,  =the  centre  of  gravity  being  in 
the  centre  of  the  body. 

When  the  power  does  not  act  parallel  to  the  plane,  draw  a line  perpendicular  to  the  direction  of  the 
power's  action  from  the  end  of  the  base  line,  (at  the  back  of  the  plane,)  and  the  intersection  of  this  line 
on  the  length  will  determine  the  length  and  height  of  the  pilane. 

Note. — When  the  line  of  direction  of  the  power  is  parallel  to  the  plane,  the  power  is  least. 

The  space  wliich  a body  describes  upon  an  inclined  plane,  when  descending  on  the  plane  by  the  force 
of  gravity,  is  to  the  space  it  would  freely  fall  hi  the  same  time,  as  the  height  is  to  the  length  of  the 
plane  ; and  the  spaces  being  the  same,  the  times  will  be  inversely  in  this  proportion. 

Example. — If  a body  be  placed  upon  an  inclined  plane  300  feet  long  and  25  feet  high,  what  space 
will  it  roll  down  in  one  second  by  the  force  of  gravity  alone  ? 

As  300  : 25  : : *16'08  : L33  feet,  Ans. 

If  a body  be  projected  down  an  inclined  plane  with  a given  velocity,  then  the  distance  which  the  body 
will  be  from  the  point  of  projection  in  a given  time  will  be  tXv  -f-  — X160872;  but  if  the  body  be  pro- 
jected upward,  then  the  distance  of  the  body  from  the  point  of  projection  will  be  tXv  — - X 16'08 1‘. 


The  force  which  accelerates  a body  down  an  inclined  plane  is  that  fractional  part  of  the  force  of 
gravity  which  is  represented  by  the  height  of  the  plane  divided  by  its  length. 

Let  h represent  the  height  of  the  plane,  l its  length,  t the  time  in  seconds,  s the  space  which  a body 

will  move  through  in  a given  time,  v the  velocity,  and  i the  angle  of  inclination  ^sin.  i — j^. 

Iv 2 


16’08  hf  tv 

'■ ; , or  — , or -, 

l ’ 2 64-8  h 


64- 3 sin.  i 


or  sin.  ixl6'08  f2. 


32’16 /it  ,64'3/ts  . . ; 

• , or  s/ - , or  sin.  * X 32T6  t,  or  V sm.  i X 64'3  s. 


Vol.  II. — 24 


The  distance  a body  will  freely  fall  in  one  second  by  the  force  of  gravity. 


370 


MECHANICAL  POWERS. 


2s 

t = — , or 


l v 


32-16  K 

h . . 

or  sin.  i 


or 


l s 

loim'/i 


, or 


32-16  t 


, or 


32-16  sin. 

s v 2 

or • 

16-08  tv  64  3 s 


Or  yj ; 

i v 16-08  sin.  4 


The  accelerating  force  on  the  plane  is  to  the  accelerating  force  of  gravity  as  v1  is  to  64-3  Xs. 

If  sin.  i = £,  it  shows  that  the  length  of  the  plane  is  twice  its  height,  or  ^ = 30°. 

If  the  proportion  which  the  length  of  the  plane  bears  to  the  height  be  given,  substitute  these  pro 
portions  for  the  length  and  height  in  the  above  rules,  and  the  conclusions  will  be  equally  true. 


Wedge.—  When  two  bodies  are  forced  from  one  another,  in  a direction  parallel  to  the  bach  of  the  wedge. 
Rule. — As  the  length  of  the  wedge  is  to  half  its  back,  so  is  the  resistance  to  the  force. 

Example. — The  length  of  the  back  of  a double  wedge  is  6 inches,  and  the  length  of  it  through  the 
middle  10  inches ; what  is  the  power  necessary  to  separate  a substance  having  a resistance  of  150  lbs.  ? 

As  10  : 3 : : 150  : 45  lbs.,  Ans. 


When  only  one  of  the  bodies  is  movable. 

Rule. — As  the  length  of  the  wedge  is  to  its  back,  so  is  the  resistance  to  the  power. 

Example. — What  power,  applied  to  the  back  of  a wedge,  will  raise  a weight  of  15,000  lbs.,  the  wedge 
being  6 inches  deep,  and  100  long  on  its  base  ? 

As  100  : 6 : : 15000  : 900  lbs.,*  Ans. 

Note. — As  the  power  of  the  wedge  in  practice  depends  upon  the  split  or  rift  in  the  wood  to  be  cleft, 
or  in  the  body  to  be  raised,  the  above  rules  are  only  theoretical  where  a rift  exists. 


Screw. — As  the  screw  is  an  inclined  plane  wound  round  a cylinder,  the  length  of  the  plane  is  found 
by  adding  the  square  of  the  circumference  of  the  screw  to  the  square  of  the  distance  between  the 
threads,  and  taking  the  square  root  of  the  sum,  and  the  height  is  the  distance  between  the  consecutive 
threads. 


Rule. — As  the  length  of  the  inclined  plane  is  to  the  pitch  or  height  of  it,  so  is  the  weight  to  the 
power. 

When  a wheel  or  capstan  is  applied  to  turn  the  screw,  the  length  of  the  lever  is  the  radius  of  the 
circle  described  by  the  handle  of  the  wheel  or  capstan  bar. 

Let  P represent  power, 

R “ length  of  lever, 

W “ weight, 

l “ length  of  the  inclined  plane, 

p “ pitch  of  screw  or  height  of  plane, 

x “ effect  of  power  at  circumference  of  screw, 

r “ radius  of  screw. 


Then,  by  the  above  rules, 


As  l 

p : 

: W 

P, 

P 

W : 

: P 

i, 

l 

W: 

: p 

P, 

r 

R 

: P 

X, 

W 

l : 

: P 

p. 

P 

X 

: r 

R, 

P 

l : 

: P 

■ w, 

It 

r : 

: x 

P. 

Example. — What  is  the  power  requisite  to  raise  a weight  of  8000  lbs.  by  a screw  of  12  inches  circum 
ference  and  1 inch  pitch  ? 

122  -f-  12  = 145,  and  ^145  = 12  04159. 

Then,  12-0416  : 1 : : 8000  : 664-36  lbs.,  Ans. 

And  if  a lever  of  30  inches  length  was  added  to  the  screw, 

12  -1-  3-1416  = 3-819  2 + SO  = 31-9095,  length  of  lever. 

Then,  as  31-9095X2X3-1416  : 12-0416  : : 664-36  : 399  lbs.,  Ans. 


Or,  let  C represent  the  circumference  described  by  the  power,  and  we  have 

P : W : : p : C, 

C : p : : W : P, 

PXC  =W  Xp; 

When  a hollow  screw  revolves  upon  one  of  less  diameter  and  pitch,  (or  the  differential  screw,)  the 
effect  is  the  same  as  that  of  a single  screw,  in  which  the  distance  between  the  threads  is  equal  to  the 
difference  of  the  distances  between  the  threads  of  the  two  screws. 

If  one  screw  has  20  threads  in  an  inch  pitch,  and  the  other  21,  the  power  is  to  the  weight  as  the 
difference  between  Ar  and  »Y>  or  4"3  o'  = 1 to  420. 

In  a complex  machine,  composed  of  the  screw,  and  wheel,  and  axle,  the  relation  between  the  weight 
»nd  power  is  thus : 

Let  x represent  the  effect  of  the  power  on  the  wheel, 

R “ the  radius  of  the  wheel, 

p “ the  pitch  of  the  screw, 

r “ the  radius  of  the  axle, 

C “ the  circumference  described  by  the  power. 


* Thi9  is  exclusive  of  friction,  which  in  this  machine  is  very  great. 


MECHANICAL  POWERS. 


371 


Then,  by  the  properties  of  the  screw, 
and  of  the  wheel  and  axle, 


PXC  = .r  Xp; 
iXR=Wxr. 


Hence  we  have 

PXCXrXR  = J'Xj)XWXr. 

Omitting  the  common  multiplier,  x, 

PXCXR  = W XpXr; 
or  P : W : : pXr  : CxR, 
andpXr  : CxR  : : P : W. 

Example. — What  weight  can  be  raised  with  a power  of  10  lbs.  applied  to  a crank  32  inches  long, 
turning  an  endless  screw  of  3£  inches  diameter  and  one  inch  pitch,  applied  to  a wheel  and  axle  of  20 
and  5 inches  in  diameter  respectively  ? 

Circumference  of  64  = 201. 

1 : 201  : : 10  : 2010. 

Radii  of  wheel  and  axle,  10  and  2 5. 


2-5  : 10  : : 2010  : 8040  lbs.,  Ans. 

or  2-5X1  : 201  X 10 : : 10  : 8040. 


And  when  a series  of  wheels  and  axles  act  upon  each  other,  the  weight  will  be  to  the  power  as  the 
continued  product  of  the  radii  of  the  wheels  to  the  continued  product  of  the  radii  of  the  axles ; 

thus,  W : P : : R3  : r3 ; 
or,  r3  : R3  : : P : W, 


there  being  three  wheels  and  axles  of  the  same  proportion  to  each  other. 

Example. — If  an  endless  screw,  with  a pitch  of  half  an  inch,  and  a handle  of  20  inches  radius,  bo 
turned  with  a power  of  150  lbs.,  and  geered  to  a toothed  wheel,  the  pinion  of  which  turns  another  wheel, 
and  the  pinion  on  the  second  wheel  turns  a third  wheel,  to  the  pinion  or  barrel  of  which  is  hung  a 
weight,  it  is  required  to  know  what  weight  can  be  sustained  in  that  position,  the  diameter  of  the  wheels 
being  18,  and  the  pinions  2 inches  ? 

pXr*  : CXR3  : : P : AV; 

or  -5X13  : 125-6X93  : : 150; 

which,  when  extended,  gives 

•5  : 91562-4  : : 150  : 21468720  lbs.,  Ans. 

Note. — The  diameter  of  a screw  is  not  a necessary  element  in  determining  the  weight  it  will  support, 
when  the  point  at  which  the  power  is  applied  is  given. 


Pullet. — When  only  one  cord  or  rope  is  used. 

Rule. — Divide  the  weight  to  be  raised  by  the  number  of  parts  of  the  rope  engaged  in  supporting  the 
lower  or  movable  block. 

Example. — What  power  is  required  to  raise  600  lbs.,  when  the  lower  block  contains  six  sheaves  and 
the  end  of  the  rope  is  fastened  to  the  upper  block,  and  what  power  when  fastened  to  the  lower  block  ? 

600 

= 50  lbs.,  1 st  Ans. 

6X2 

— — =46-15  lbs.,  2d  Ans. 

6 X 2-|-l 

or  W = n X P, 

n signifying  the  number  of  parts  of  the  rope  which  sustain  the  lower  block. 


When  more  than  one  rope  is  used. 

In  a Spanish  burton,  where  there  are  two  ropes,  two  movable  pulleys,  and  one  fixed  and  one  sta- 
tionary pulley,  with  the  ends  of  one  rope  fastened  to  the  support  and  upper  movable  pulley,  and  the 
ends  of  the  other  fastened  to  the  lower  block  and  the  power,  the  weight  is  to  the  power  as  5 to  1. 

And  in  one  where  the  ends  of  one  rope  are  fastened  to  the  support  and  the  power,  and  the  ends  of 
the  other  to  the  lower  and  upper  blocks,  the  weight  is  to  the  power  as  4 to  1. 

In  a system  of  pulleys,  with  any  number  of  ropes,  the  ends  being  fastened  to  the  support, 

AV  = 2"  X P, 

n expressing  the  number  of  ropes. 

Example. — What  weight  will  a power  of  1 lb.  sustain  in  a system  of  4 movable  pulleys  and  4 ropes  ? 

1X2X2X2X2  = 16  lbs.,  Ans. 

When  fixed  pulleys  are  used  in  the  place  of  hooks,  to  attach  the  ends  of  the  rope  to  the  support, 

W = 3"xP. 

Example. — What  weight  will  a power  of  5 lbs.  sustain  with  4 movable  and  4 fixed  pulleys,  and  4 ropes  ? 
5X3X3X3X3  = 405  lbs.,  Ans. 

When  the  ends  of  the  rope,  or  the  fixed  pulleys,  are  fastened  to  the  weight, 

W = (2»— 1)XP, 
and  W =(3"  — 1)XP, 
which  would  give,  in  the  above  examples, 

1X2X2X2X2=  16  — 1=  15  lbs., 

5X3X3X3X3=405  — 1=404  lbs. 


372 


MECHANICAL  POWER  OF  STEAM. 


MECHANICAL  POWER  OF  STEAM.  Under  the  head  of  Crank,  in  the  first  volume  of  this  Dic- 
tionary, reference  is  made  to  this  article  for  an  elucidation  of  the  theory  of  its  movement,  as  also  for 
an  explanation  of  the  mechanical  laws  of  steam.  These  last  should  be  sought  under  their  proper  head 
“ Steam,”  while  the  theory  of  the  crank  will  be  explained  in  this  place,  as  reference  has  been  made  to 
it  under  this  head. 

If  we  consider  the  rotatory  engine  with  revolving  piston  apart  from  the  practical  objections  against 
its  application,  it  is  a perfect  engine,  and  is  capable  of  giving  out  all  the  effect  of  the  steam.  An  im- 
pression has,  however,  widely  prevailed  that  this  is  not  the  case  with  the  common  reciprocating  engine 
with  its  connecting-rod  and  crank.  Several  scientific  writers  on  the  steam-engine  have  pointed  out  the 
error  of  this  conviction,  so  that  all  the  better-informed  class  of  engineers  are  well  aware  that  the  crank, 
like  all  other  pieces  of  machinery,  fully  transmits  the  power  which  is  communicated  to  it.  There  are 
others,  however,  who  cannot  understand  this : they  cannot  set  out  from  the  great  fundamental  principle 
of  virtual  velocities,  and  satisfy  themselves  with  asserting  the  truth  as  a simple  and  inevitable  deduc- 
tion from  it.  They  are  continually  asking  the  question,  “ How  is  it  that,  in  the  common  crank,  we  are 
able  to  show  that,  at  two  given  points  in  its  revolution,  the  position  is  such  that  an  infinite  power  would 
produce  no  effect  at  all ; that  there  are  only  two  positions  in  which  the  force  and  effect  are  equal ; and 
that,  at  every  other  position,  the  effective  pressure  given  out  by  the  connecting-rod  to  the  crank  is  less 
than  the  original  pressure  of  the  steam  on  the  piston — the  remainder  of  the  pressure  of  the  steam  pro- 
ducing only  a useless  pressure  on  the  cranks — how  then  can  the  crank  be  conceived  to  transmit  the 
whole  mechanical  effect  of  the  steam  ?”  In  the  present  remarks  we  intend  to  give  an  answer  to  this 
question.  We  intend  to  examine,  at  considerable  length,  the  action  of  the  crank,  and  to  show  that  the 
great  fact  upon  which  the  whole  science  of  mechanics  has  rested  ever  since  the  time  of  Galileo,  still 
obtains  in  all  its  generality  in  this  particular  case.  For  the  purpose  of  clearly  elucidating  the  subject 
we  intend  to  consider  it  at  first  in  a very  simple  and  practical  manner,  and  then  to  examine  it  in  a more 
theoretical  point  of  view. 

Before  proceeding  further  it  is  necessary  to  have  a clear  conception  of  the  meaning  of  the  term 
“ power.”  It  is  obvious  that  it  must  be  different  from  the  term  “ force”  or  “ pressure  for,  if  its  mean- 
ing were  the  same,  it  would  be  absurd  to  say  that  the  crank  always  transmits  the  whole  “ power,”  since 
in  some  position^  it  does  not  transmit  any  of  the  pressure  of  the  steam  at  all.  The  term  “ power,”  as 
generally  used  by  writers  on  the  steam-engine,  means  the  mechanical  power  of  the  steam,  or  its  me- 
chanical effect.  In  estimating  the  mechanical  effect  we  have  to  consider  two  things : 1st,  the  load  or 
force  raised,  and  2d,  the  distance  through  which  it  is  raised;  and  the  mechanical  effects  are  considered 
to  be  equal  when  the  product  of  these  two  are  equal.  For  example,  suppose  two  different  machines 
constructed  in  such  a manner  that  in  the  one  1 lb.  of  steam  is  made  to  raise  10  tons  through  8 feet,  and 
that  in  the  other  1 lb.  of  steam  is  made  to  raise  15  tons  through  6 feet;  we  say  that  the  mechanical 
effect  of  the  steam  is  the  same  in  these  two  machines,  because  10X8=15X6.  This  principle  may  be 
expressed  in  the  form  of  a rule  : — “ Mechanical  effects  are  equal  when  the  weights  raised  are  inversely 
proportional  to  the  distances  through  which  they  are  raised.”  This  law  is  useful  for  comparing  the 
mechanical  effects  of  different  machines  ; our  purpose,  at  present,  however,  is  to  compare  the  mechani- 
cal effects  of  different  parts  of  the  same  machine.  It  will  not  be  difficult  so  to  modify  this  law  as  to 
suit  our  purposes.  When  it  is  different  machines  that  we  are  comparing,  the  time  for  developing  the 
mechanical  effects  may  be  different,  but  in  the  same  machine  the  time  must  necessarily  be  the  same. 
From  this  equality  of  time  we  infer  that  the  spaces  through  which  the  load  is  moved  are  directly  pro- 
portional to  the  uniform  velocity  with  which  they  are  described.  Hence  the  law  may  be  expressed  as 
follows:  “The  mechanical  effects  of  the  different  parts  of  the  same  machine  are  equal  when  the 
weights  or  pressures  raised  are  inversely  proportional  to  the  velocities  with  which  they  are  raised.  ’ 
The  product  of  a weight  or  pressure  into  its  velocity  is  called  the  “momentum  of  the  weight  or  pres- 
sure.” After  this  definition,  our  rule  may  be  expressed  as  follows:  “Mechanical  effects  of  the  differ- 
ent parts  of  the  same  machine  are  equal  when  the  momenta  are  equal.”  A dopting  the  principle  that 
the  momentum  measures  the  mechanical  effect,  or,  as  it  is  usually  called,  the  power,  it  is  a recognized 
principle,  proved  by  all  writers  on  mechanics,  that  however  complicated  machinery  may  be,  still,  making 
allowance  for  the  resistances  arising  from  friction,  the  mechanical  effect  remains  the  same.  Our  inten- 
tion at  present  is  only  to  show  that  it  obtains  in  the  particular  case 
of  the  crank.  The  crank-pin  moves  through  a greater  space  than 
the  piston  ; and  when  the  piston  is  moving  very  slowly  the  crank- 
pin  is  moving  very  quickly,  so  that  the  ultimate  effect  is  the  same 
at  every  moment.  By  multiplying  the  pressure  into  the  velocity, 
it  will  be  found  that  the  same  quantity  of  steam  produces  the 
same  amount  of  power  at  every  part  of  the  stroke. 

Suppose  the  velocity  of  the  piston  to  be  uniform,  then  the  mo- 
tion of  the  extremity  of  the  connecting-rod  will  be  uniform  also. 

The  extremity  of  the  crank  always  moves  irregularly,  but  as  it 
moves  over  a greater  space  than  the  extremity  of  the  connecting- 
rod,  its  mean  velocity  must  be  greater.  The  proportion  is  obviously 
as  follows  : 

Velocity  of  piston  : mean  velocity  of  extremity  of  crank  : : twice 
the  length  of  stroke  : circumference  which  the  extremity  of  the 
crank  describes. 

Let  l denote  the  length  of  stroke,  and  n the  ratio  of  the  circum- 
ference of  a circle  to  its  diameter ; then  we  have  the  proportion, 

Velocity  of  piston  : mean  velocity  of  extremity  of  crank  : : 2 
l : 7t  l : : 2 : “,  and,  therefore,  mean  velocity  of  extremity  of  crank 
= 7r  x velocity  of  piston  — 2.  Since  the  mean  velocity  of  the 


MECHANICAL  POWER  OF  STEAM. 


37 


crank  is  greater  than  that  of  the  piston,  then,  according  to  our  law,  in  order  to  produce  the  same  mechan- 
ical effect,  the  mean  effective  pressure  must  be  less,  and  that  in  the  same  proportion.  We  may  approxi- 
mate to  the  mean  effective  pressure  by  calculating  it  for  a great  many  equidistant  positions,  and  taking 
the  average.  Thus  let  Fig.  2804  represent  the  circle  which  the  extremity  of  the  crank  describes.  Di- 
vide it  into  20  equal  parts.  Suppose  the  connecting-rod  to  remain  always  in  a parallel  direction,  and 
the  constant  pressure  in  it  to  be  100.  The  effective  pressure  at  any  point  P will  be  100  sin.  POE. 
From  this  we  have  the  following  table  : 


Points  in  the  Figure. 

Pressure  in  the  Direction  of  Revolution. 

At  0 and  at 

20 

100 

X 

sin. 

0°  = 

000 

1 

19 

100 

X 

sin. 

18°  = 

30-90 

2 

18 

100 

X 

sin. 

36°  = 

58-78 

3 

17. 

100 

X 

sin. 

54°  = 

80-90 

4 

16 

100 

X 

sin. 

72°  = 

95-11 

5 

15 

100 

X 

sin. 

90°  = 

100-00 

6 

14 

100 

X 

sin. 

108°  = 

95-11 

7 

13 

100 

X 

sin. 

126°  = 

8090 

8 

12 

100 

X 

sin. 

141°  = 

58-78 

9 

11 

100 

X 

sin. 

162°  = 

30-90 

10 

10 

100 

X 

sin. 

180°  = 

o-oo 

Mear 

pressure  6ST1 

From  this  we  learn  that  the  mean  effective  pressure  is  to  the  pressure  at  piston  in  the  proportion  of 
about  63  to  100.  This  is  very  nearly  the  same  proportion  as  2 to  it  ; for  110  -f-  03  = 1'6  nearly,  and 
■n--h  2 = l-7.  Hence  we  have  the  proportion,  pressure  at  piston  : mean  effective  pressure  at  extremity 
of  crank  : : mean  velocity  of  extremity  of  crank  : velocity  of  piston.  This  shows,  according  to  our  law, 
that  the  mechanical  effect  of  the  pressure  at  the  piston  is  wholly  transmitted  to  the  crank. 

We  have  said  not  only  that  the  mechanical  effect  is  the  same  ultimately,  but  that  it  is  the  same 
momentarily ; that  is  to  say,  that  the  product  of  the  effective  force  at  any  point,  and  the  velocity  at 
that  point,  is  constantly  equal  to  the  product  of  the  pressure  at  the  piston,  and  its  velocity  at  the  cor- 
responding position.  It  is  more  difficult  to  illustrate  this  in  the  same  manner,  on  account  of  the  diffi- 
culty of  calculating  the  relative  velocity  of  the  crank  and  piston.  It  is  very  easy  to  show,  however, 
that  at  what  is  called  the  “position  of  the  centres”  no  loss  of  power  can  really  take  place.  This  hap- 
pens for  this  very  plain  reason,  that  there  is  no  power  exerted  at  that  time.  It  ought  to  be  remem- 
bered that  at  that  time  the  communication  which  supplies  the  steam  from  the  boiler  is  cut  off.  The 
steam  on  one  side  having  done  its  work,  only  waits  to  be  released  from  its  chamber,  and  escapes  at  the 
opening  of  the  eduction  valve,  and  at  the  same  instant  is  in  the  act  of  being  permitted  to  enter  on  the 
opposite  side  for  reversing  the  motion.  Hence  at  these  points  all  application  of  force  has  ceased,  and 
arrangements  are  making  for  reversing  the  motion ; besides  which,  when  the  engine  is  on  the  centre, 
the  piston  has  not  any  motion. 

With  regard  to  the  remaining  points  of  the  circle,  at  which  it  is  said  power  is  lost,  the  velocity  im- 
parted to  the  crank  is  always  an  exact  equivalent  for  the  force  which  is  apparently  lost.  At  present 
we  wish  only  to  illustrate  this  fact,  for  its  rigid  demonstration  requires  rather  abstract  considerations. 
The  following  table  presents  the  results  of  the  calculations  of  the  power  and  velocity.  The  numbers 
I,  2,  &c.,  refer  to  Fig.  2804. 


Position  of  Crank. 

Pressure  in  Direction  of 
Revolution. 

Velocity  of  Crank  divided 
by  Velocity  of  Piston. 

At  0 and  at  20 

o-oo 

Infinite 

1 

19 

30-90 

3-236 

2 

18 

58-78 

1-701 

3 

17 

80-90 

1-236 

4 

16 

95-11 

1-051 

5 

15 

10000 

1-0OC 

6 

14 

95-11 

1-051 

7 

13 

80-90 

1-236 

8 

12 

58-78 

1-701 

9 

11 

30-90 

3-236 

10 

10 

0-00 

Infinite 

These  are  obtained  on  the  supposition  that  the  force  on  the  piston  and  its  velocity  are  constant,  and 
»lso  that  the  connecting-rod  keeps  always  in  a parallel  direction.  Neither  of  these  suppositions  is  ex- 
actly true  in  practice.  The  same  law  holds,  although  the  pressure  on  the  piston  is  variable,  and  also  its 
velocity,  and  although  the  connecting-rod  takes  different  inclinations.  It  will  be  observed  from  our  table 
that  the  smaller  the  effective  pressure  in  the  direction  of  the  revolution,  the  greater  the  relative  velocity 
The  rigid  demonstration  of  these  facts  requires  for  their  proper  exhibition  the  differential  calculus 
tvhich  in  this  work  would  be  out  of  place. 


374 


MENSURATION. 


MEERSCHAUM.  This  form  of  silicate  of  magnesia  is  employed  in  manufacturing  the  celebrated 
tobacco-pipes  known  under  this  name,  and  its  composition  is  as  follows,  differing  but  little  from  steatite 
or  soapstone ; but,  unlike  the  latter,  may  be  artificially  produced  : 

Madrid.  Natoiia. 

53-80  42-00 

23-80  30-50 

23-80  2-30 

{ K}  «• 

20-00  23-00 

100-05  98-80  99-30 

It  is  found  in  the  native  state  on  the  shores  of  the  inland  seas  of  Europe.  That  found  in  Morocco 
contains,  in  addition  to  the  above  ingredients,  -52  of  potash.  It  is. light  and  soft,  and  is  employed  in  the 
Turkish  dominions  as  fuller’s  earth.  In  Germany  it  is  extensively  used  in  the  manufacture  of  tobacco- 
pipes,  which  are  prepared  for  sale  by  being  soaked  first  in  tallow,  then  in  wax,  and  finally  by  being 
polished  with  shave-grass.  Imitation  meerschaum  pipes  are  sold  in  large  quantities,  and  the  greatest 
caution  is  necessary  to  guard  against  deception.  To  the  connoisseur,  the  best  criterion  is  the  beautiful 
brown  color  which  the  genuine  meerschaum  assumes  after  being  smoked  some  time. 

MENSURATION — Of  Surfaces.  To  find  the  area  of  a four-sided  figure. — Rule. — Multiply  the 
length  by  the  breadth  or  perpendicular  height ; the  product  will  be  the  area. 

To  find  the  area  of  a triangle. — Rule. — Multiply  the  length  of  one  of  the  sides,  by  a perpendicular 
falling  upon  it  from  the  opposite  angle;  half  the  product  will  be  the  area. 

To  find  the  length  of  one  side  of  a right-angled  triangle , when  the  lengths  of  the  other  two  sides  are 
given. — Rule  1. — To  find  the  hypothenuse,  add  together  the  squares  of  the  two  legs,  and  extract  the 
square  root  of  that  sum. 

Rule  2. — To  find  one  of  the  legs,  subtract  the  square  of  the  leg,  of  which  the  length  is  known,  from 
the  square  of  the  hypothenuse,  and  the  square  root  of  the  difference  will  be  the  answer. 

To  find  the  area  of  a regular  polygon. — Rule. — Multiply  the  length  of  a perpendicular,  drawn  from 
twe  centre  to  one  of  the  sides,  (or  the  radius  of  its  inscribed  circle,)  by  the  length  of  one  side,  and  this 
product  again  by  the  number  of  sides ; and  half  the  product  will  be  the  area  of  the  polygon. 

To  find  the  area  of  a trapezium. — Rule  1. — Draw  a diagonal  line  to  divide  the  trapezium  into  two 
triangles ; find  the  areas  of  these  triangles  separately,  and  add  them  together. 

Rule  2. — Divide  the  trapezium  into  two  triangles,  by  a diagonal,  and  let  two  perpendiculars  fall  on 
the  diagonal  from  the  opposite  angles ; then,  the  sum  of  these  perpendiculars  multiplied  by  the  diagonal, 
and  divided  by  2,  will  be  the  area  of  the  trapezium. 

To  find  the  area  of  a trapezoid. — Rule  1. — Multiply  the  sum  of  the  two  parallel  sides  by  the  perpen- 
dicular distance  between  them,  and  half  the  product  will  be  the  area. 

Rule  2. — Draw  a diagonal,  to  divide  the  trapezoid  into  two  triangles ; find  the  areas  of  those  triangles 
separately,  and  add  them  together. 

To  find  the  area  of  an  irregular  polygon. — Rule. — Draw  diagonals,  to  divide  the  figure  into  tra- 
peziums and  triangles  ; find  the  area  of  each  separately,  by  either  of  the  rules  before  given  for  that 
purpose ; and  the  sum  of  the  whole  will  be  the  area  of  the  figure. 

To  find  the  area  of  a long  irregular  figure. — Rule. — Take  the  breadths  in  several  places,  and  at  equal 
distances  from  each  other ; add  all  the  breadths  together,  and  divide  the  sum  by  this  number,  for  the 
mean  breadth ; then  multiply  the  mean  breadth  by  the  length  of  the  figure,  and  the  product  will  be  the 
area. 

To  find  the  circumference  of  a circle  when  the  diameter  is  given  ; or  the  diameter  when  the  circumfer- 
ence is  given. — Rule  1. — Multiply  the  diameter  by  3-1416,  and  the  product  will  le  the  circumference; 
or  divide  the  circumference  by  3-1416,  and  the  quotient  will  be  the  diameter. 

Rule  2. — As  7 is  to  22,  so  is  the  diameter  to  the  circumference ; 

As  22  is  to  7,  so  is  the  circumference  to  the  diameter. 

Rule  3. — As  113  is  to  355,  so  is  the  diameter  to  the  circumference; 

As  355  is  to  113,  so  is  the  circumference  to  the  diameter. 

To  find  the  area  of  a circle.— Rule  1. — Multiply  the  square  of  the  diameter  by  -7854  ; or  the  square 
of  the  circumference  by  "07958;  the  product,  in  either  case,  will  be  the  area. 

Rule  2. — Multiply  the  circumference  by  the  diameter,  and  divide  the  product  by  4. 

Rule  3. — As  14  i%  to  11,  so  is  the  square  of  the  diameter  to  the  area ; 

Or  as  88  is  to  7,  so  is  the  square  of  the  circumference  to  the  area. 

To  find  the  length  of  any  arc  of  a circle. — Rule  1. — From  8 times  the  chord  of  half  the  arc,  subtract 
the  chord  of  the  whole  arc ; one-third  of  the  remainder  will  be  the  length  of  the  arc,  nearly. 

Rule  2. — As  180  is  to  the  number  of  degrees  in  the  arc; 

So  is  3-1416  times  the  radius  to  its  length. 

Or,  as  3 is  to  the  number  of  degrees  in  the  arc ; 

So  is  -05236  times  the  radius  to  its  length. 

To  find  the  area  of  d sector  of  a circle. — Rule  1. — Multiply  the  length  of  the  arc  by  half  the  length  of 
the  radius ; the  product  will  be  the  area. 

Rule  2. — As  360  degrees  is  to  the  number  of  degrees  in  the  arc  of  the  sector ; so  is  the  area  of  the 
circle  to  the  area  of  the  sector. 

To  find  the  area  of  a segment  of  a circle. — Rule  1. — To  the  chord  of  the  whole  arc,  add  the  chord  oi 
naif  the  arc  and  one-third  of  it  more.  Then  multiply  the  sum  by  the  versed  sine,  or  height  of  the  seg- 
ment, and  four-tenths  of  the  product  will  be  the  area  of  the  segment. 


Levant. 

Silica 

60-87 

Magnesia 

27-80 

Lime 

27-80 

Alumina 

) 

Oxide  of  iron 

' 1 -009 

Water 

11-29 

MENSURATION. 


375 


Rule  2. — Divide  the  height,  or  versed  sine,  by  the  diameter  of  the  circle,  and  find  the  quotient  in  the 
column  of  versed  sines,  in  the  table  of  areas  of  segments. 

Then  take  out  the  corresponding  area  in  the  next  column  on  the  right-hand,  and  multiply  it  by  the 
square  of  the  diameter,  for  the  answer. 

To  find  the  area  of  a circular  zone. — Rule  1. — When  the  zone  is  less  than  a semicircle,  to  the  area  of 
the  trapezoid,  formed  by  connecting  the  extremities  of  the  zone  by  straight  lines,  add  the  area  of  the 
circular  segments  beyond  those  lines ; the  sum  is  the  area  of  the  zone. 

Rule  2. — When  the  zone  is  greater  than  a semicircle,  to  the  area  of  the  parallelogram,  formed  in  like 
manner  as  above,  add  the  area  of  the  circular  segments,  at  its  extremities ; the  sum  is  the  area  of  the 
zone. 

To  find  the  area  of  a circular  ring,  or  space,  included  between  two  concentric  circles. — Rule. — Find  the 
areas  of  the  two  circles  separately ; then  the  difference  between  them  will  be  the  area  of  the  ring. 

To  find  the  ofrcumference  of  an  ellipse.-— Rule. — Square  the  two  axes,  and  multiply  the  square  root 
of  half  that  sum  by  3T416  ; the  product  will  be  the  circumference,  nearly. 

To  find  the  area  of  an  ellipse. — Rule. — Multiply  the  transverse  diameter  by  the  conjugate,  and  the 
product  by  "7854. 

To  find  the  area  of  an  elliptic  segment. — Rule. — Divide  the  height  of  the  segment  by  the  axi9  of 
which  it  is  a part,  and  find,  in  the  table  of  segments  of  circles,  a circular  segment  having  the  same 
versed  sine  as  this  quotient.  Then,  multiply  the  segment  thus  found  and  the  two  axes  of  the  ellipse 
continually  together,  and  the  product  will  give  the  area  required. 

When  the  transverse,  the  conjugate,  and  the  abscissa!  are  given , to  find  the  ordinate. — Rule. — Multiply 
the  abscissae  into  each  other,  and  extract  the  square  root  of  the  product ; this  will  give  the  mean 
between  them.  Then,  as  the  transverse  diameter  is  to  the  conjugate  diameter,  so  is  the  mean  to  the 
ordinate  required. 

When  the  transverse,  the  conjugate,  and  the  ordinate  are  given,  to  find  the  abscissce. — Rule. — From 
the  square  of  half  the  conjugate,  take  the  square  of  the  ordinate,  and  extract  the  square  root  of  the 
remainder. 

Then,  as  the  conjugate  diameter  is  to  the  transverse,  so  is  that  square  root  to  half  the  difference  of 
the  two  absciss®. 

Add  this  half  difference  to  half  the  transverse,  for  the  greater  abscissa;  and  subtract  it  for  the  less. 

When  the  transverse,  the  ordinate,  and  the  two  abscissce  are  given,  to  find  the  conjugate. — Rule. — As 
the  square  root  of  the  product  of  the  two  absciss®  is  to  the  ordinate,  so  is  the  transverse  diameter  to 
the  conjugate. 

Note. — In  the  same  manner  the  transverse  diameter  may  be  found  from  the  conjugate,  using  the  two 
absciss®  of  the  conjugate,  and  their  ordinate  perpendicular  to  the  conjugate. 

When  the  conjugate,  the  ordinate,  and  the  abscissce  are  given,  to  find  the  transverse  diameter. — Rule. — 
From  the  square  of  half  the  conjugate  subtract  the  square  of  the  ordinate,  and  extract  the  root  of  the 
remainder.  Add  this  root  to  the  half  conjugate  if  the  less  abscissa  be  given  ; but  subtract  it  when  the 
greater  abscissa  is  given. 

Then,  as  the  square  of  the  ordinate  is  to  the  rectangle  of  the  abscissa  and  conjugate,  so  is  the  reserved 
sum,  or  difference,  to  the  transverse  diameter. 

To  find  the  area  of  a parabola. — Rule. — Multiply  the  base  by  the  height,  and  two-thirds  of  the  pro- 
duct will  be  the  area. 

To  find  the  area  of  a frustum  of  a parabola. — Rule. — Multiply  the  difference  of  the  cubes  of  the  two 
ends  of  the  frustum  by  twice  its  altitude,  and  divide  the  product  by  thrice  the  difference  of  their  squares. 

To  find  the  abscissa  or  ordinate  of  the  parabola. — Rule. — The  absciss®  are  to  each  other  as  the 
squares  of  their  ordinates ; that  is,  as  any  abscissa  is  to  the  square  of  its  ordinate,  so  is  any  other 
abscissa  to  the  square  of  its  ordinate. 

Or,  as  the  square  root  of  any  abscissa  is  to  its  ordinate,  so  is  the  square  root  of  another  abscissa  to  its 
ordinate. 

To  find  the  length  of  a parabolic  curve,  cut  off  by  a double  ordinate. — Rule. — To  the  square  root  of 
the  ordinate,  add  four-thirds  of  the  square  of  the  abscissa  ; the  square  root  of  that  sum,  multiplied  by  2, 
will  give  the  length  of  the  curve,  nearly. 

To  find  the  area  of  a hyperbola. — Rule. — -To  five-sevenths  of  the  abscissa,  add  the  transverse  diame- 
ter ; multiply  the  sum  by  the  abscissa,  and  extract  the  square  root  of  the  product.  Then,  multiply  the 
transverse  diameter  by  the  abscissa,  and  extract  the  square  root  of  that  product. 

Then,  to  21  times  the  first  root  add  4 times  the  second  root ; multiply  the  sum  by  double  the  product 
of  the  conjugate  and  abscissa,  and  divide  by  75  times  the  transverse;  this  will  give  the  area,  nearly. 

To  find  the  length  of  a hyperbolic  curve. — Rule. — To  21  times  the  square  of  the  conjugate  add  9 times 
the  square  of  the  transverse;  also,  to  21  times  the  square  of  the  conjugate  add  19  times  the  square  of 
the  transverse,  and  multiply  each  of  these  sums  by  the  abscissa. 

To  each  of  the  two  products  add  15  times  the  product  of  the  transverse  and  square  of  the  conjugate. 

Then,  as  the  less  sum  is  to  the  greater,  so  is  the  ordinate  to  the  length  of  the  curve,  nearly. 

When  the  transverse,  the  conjugate,  and  the  abscissce  are  given,  to  find  the  ordinate. — Rule. — As  the 
transverse  diameter  is  to  the  conjugate,  so  is  the  square  root  of  the  product  of  the  two  absciss®  to  the 
ordinate  required. 

Note. — In  the  hyperbola,  the  less  abscissa  added  to  the  axis  gives  the  greater : and  the  greater 
abscissa  subtracted  from  the  axis,  gives  the  less. 

When  the  transverse  and  conjugate  diameters,  and  the  ordinate,  are  given,  to  find  the  abscissae. — Rule. — • 
To  the  square  of  half  the  conjugate  add  the  square  of  the  ordinate,  and  extract  the  square  root  of  that 
sum. 

Then,  as  the  conjugate  diameter  is  to  the  transverse,  so  is  the  square  root  +o  half  the  sum  of  (he 
absciss®. 


376 


MENSURATION. 


To  this  half  sum  add  half  the  transverse  diameter  for  the  greater  abscissa,  and  subtract  it  fol 
the  less. 

When  the  transverse  diameter , ordinate , and  abscissa;,  are  given , to  find  the  conjugate. — Rule. — As  the 
square  root  of  the  product  of  the  two  abscissas  is  to  the  ordiuate,  so  is  the  transverse  diameter  to  the 
conjugate. 

When  the  conjugate  diameter,  the  ordinate,  and  the  two  abscissa:,  are  given,  to  find  the  transverse 
diameter. — Rule. — To  the  square  of  half  the  conjugate  add  the  square  of  the  ordinate,  and  extract  the 
square  root  of  that  sum. 

To  this  root  add  the  half  conjugate  when  the  less  abscissa  is  used ; and  subtract  it  when  the  greater 
abscissa  is  used ; reserving  the  sum  or  difference. 

Then,  as  the  square  of  the  ordinate  is  to  the  product  of  the  absciss®  and  conjugate,  so  is  the  reserved 
sum,  or  difference,  to  the  transverse. 

Mensuration  of  Solids. — To  find  the  solidity  of  a cube. — Rule. — Multiply  the  side  of  the  cube  by 
itself,  and  that  product  again  by  the  side ; the  last  product  will  be  the  solidity  of  the  given  cube. 

To  find  the  solidity  of  a parallelopipedon. — Rule. — Multiply  the  length,  breadth,  and  depth  or  alti- 
tude, continually  together,  or,  in  other  words,  multiply  the  length  by  the  breadth,  and  that  product  by 
the  depth  or  altitude,  and  this  will  give  the  required  solidity. 

To  find  the  solidity  of  cylinders  and  prisms. — Rule. — Multiply  the  area  of  the  base  by  the  height  of  the 
cylinder  or  prism,  and  the  product  will  give  the  solid  content. 

To  find  the  convex  surface  of  a cylinder. — Rule. — Multiply  the  circumference  by  the  length  of  the 
cylinder ; the  product  will  be  the  convex  surface  required. 

lb  find  the  convex  surface  of  a right  cone,  or  pyramid. — Rule. — Multiply  the  perimeter,  or  circum- 
ference of  the  base,  by  the  slant  height,  or  length  of  the  side  of  the  cone,  and  half  the  product  will  be 
the  surface. 

To  find  the  convex  surface  of  a frustum  of  a right  cone,  or  pyramid. — Rule. — Multiply  the  sum  of  the 
perimeters  of  the  two  ends  by  the  slant  height  or  side  of  the  frustum,  and  half  the  product  will  be  the 
surface  required. 

To  find  the  solidity  of  a cone,  or  pyramid. — Rule. — Multiply  the  area  of  the  base  by  the  perpendicular 
height,  and  one-third  of  the  product  will  be  the  content. 

To  find  the  solidity  of  the  frustum  of  a cone. — Rule. — Divide  the  difference  of  the  cubes  of  the  diam- 
eters of  the  two  ends  by  the  difference  of  the  diameters ; this  quotient  multiplied  by  ‘7854  and  again  by 
one-third  of  the  height,  will  give  the  solidity. 

To  find  the  solidity  of  the  frustum  of  a pyramid. — Rule. — Add  to  the  areas  of  the  two  ends  of  the 
frustum  the  square  root  of  their  product,  and  this  sum,  multiplied  by  one-third  of  the  height,  will  give 
the  solidity. 

To  find  the  solidity  of  a wedge. — Rule.— To  the  length  of  the  edge  of  the  wedge  add  twice  the  length 
of  the  back ; multiply  this  sum  by  the  height  of  the  wedge,  and  then  by  the  breadth  of  the  back ; one- 
sixth  of  the  product  will  be  the  solid  content. 

To  find  the  solidity  of  a prismoid. — Rule. — Add  into  one  sum  the  areas  of  the  two  ends  and  four 
times  the  middle  section,  parallel  to  them ; then,  this  sum  multiplied  by  one-sixth  of  the  height,  will 
give  the  content. 

Note. — The  length  of  the  middle  section  is  equal  to  half  the  sum  of  the  lengths  of  the  two  ends ; and 
its  breadth  is  equal  to  half  the  sum  of  the  breadths  of  the  two  ends. 

To  find  the  convex  surface  of  a sphere,  or  globe. — Rule. — Multiply  the  diameter  of  the  sphere  by  its 
circumference. 

Or,  multiply  3T416  by  the  square  of  the  diameter;  the  product  will  be  the  convex  surface  required. 

Note. — The  convex  surface  of  any  zone  or  segment  may  be  found,  in  like  manner,  by  multiplying  its 
height  by  the  whole  circumference  of  the  sphere. 

To  find  the  solidity  of  a sphere  or  globe. — Rule. — Multiply  the  cube  of  the  axis  by  '5236  ; the  product 
will  be  the  solidity. 

To  find  the  solidity  of  a spherical  segment. — Rule. — To  three  times  the  square  of  the  radius  of  its 
base  add  the  square  of  its  height;  then,  multiply  the  sum  by  the  height,  and  the  product  by  '5236. 

To  find  the  solidity  of  a spherical  zone  or  frustum. — Rule.— To  the  sum  of  the  squares  of  the  radius 
of  each  end,  add  one-third  of  the  square  of  the  height  of  the  zone ; this  sum,  multiplied  by  the  said 
height,  and  the  product  by  T5708,  will  give  the  solidity. 

To  find  the  solidity  of  a spheroid. — Rule. — Multiply  the  square  of  the  revolving  axis  by  the  fixed  or 
shorter  axis;  the  product,  multiplied  by  '5236,  will  give  the  content. 

To  find  the  solidity  of  a segment  of  a spheroid. — Rule  1. — When  the  base  is  circular  or  parallel  to  the 
revolving  axis,  multiply  the  fixed  axis  by  3,  the  height  of  the  segment  by  2,  and  subtract  the  one  product 
from  the  other ; then  multiply  the  remainder  by  the  square  of  the  height  of  the  segment,  and  the  pro- 
duct by  '5236. 

Then,  as  the  square  of  the  fixed  axis  is  to  the  square  of  the  revolving  axis,  so  is  the  last  product  to 
the  content  of  the  segment. 

Rule  2. — When  the  base  is  perpendicular  to  the  revolving  axis,  multiply  the  revolving  axis  by  3,  and 
the  height  of  the  segment  by  2,  and  subtract  the  one  from  the  other ; then,  multiply  the  remainder  by 
the  square  of  the  height  of  the  segment,  and  the  product  by  '5236. 

Then,  as  the  revolving  axis  is  to  the  fixed  axis,  so  is  the  last  product  to  the  content. 

To  find  the  solidity  of  the  middle  frustum  of  a spheroid. — Rule  1. — When  the  ends  are  crrcuiar,  or 
parallel  to  the  revolving  axis,  to  twice  the  square  of  the  revolving  axis,  add  the  square  of  the  diameter 
of  either  end;  then,  multiply  this  sum  by  the  length  of  the  frustum,  and  the  product  again  by  '2618; 
this  will  give  the  solidity. 

Rule  2. — When  the  ends  are  elliptical,  or  perpendicular  to  the  revolving  axis,  to  twice  the  product  ol 
.lie  transverse  and  conjugate  diameters  of  the  middle  section,  add  the  product  of  the  transverse  and 


METALS  AND  ALLOYS. 


377 


conjugate  of  either  end ; multiply  this  sum  by  the  length  of  the  frustum,  and  the  product  by  '2618  ; this 
will  give  the  solidity. 

To  find  the  surface  of  a circular  spindle. — Rule. — Multiply  the  length  of  the  spindle  by  the  radius  of 
the  revolving  arc.  Multiply  also  the  said  arc  by  the  central  distance,  or  distance  between  the  centre  oi 
the  spindle  and  centre  of  the  revolving  arc.  Subtract  this  last  product  from  the  former ; double  the 
remainder;  multiply  it  by  3-1416,  and  the  product  will  give  the  surface  of  the  spindle. 

Note. — The  same  rule  will  serve  for  any  segment,  or  zone,  cut  off  perpendicularly  to  the  chord  of  the 
revolving  arc ; but,  in  this  case,  the  particular  length  of  the  part,  and  the  part  of  the  arc  which  describes 
it,  must  be  used,  instead  of  the  whole  length  and  whole  arc. 

To  find  the  solidity  of  a circular  spindle. — Rule. — Multiply  the  central  distance,  as  above,  by  half  the 
area  of  the  revolving  segment.  Subtract  the  product  from  one-third  of  the  cube  of  half  the  length  ol 
the  spindle.  Then,  multiply  the  remainder  by  12-5664,  or  4 times  3-1416,  and  the  product  will  be  the 
solidity  required. 

To  find  the  solidity  of  the  frustum , or  zone , of  a circular  spindle. — Rule. — From  the  square  of  half 
the  length  of  the  whole  spindle,  take  one-third  of  the  square  of  half  the  length  of  the  frustum,  and  mul- 
tiply the  remainder  by  the  said  half-length  of  the  frustum.  Multiply  the  central  distance  by  the 
revolving  area,  which  generates  the  frustum.  Subtract  the  last  product  from  the  former ; and  the 
remainder,  multiplied  by  6‘2832,  or  twice  3-1416,  will  give  the  content. 

To  find  the  solidity  of  an  elliptic  spindle. — Rule. — To  the  square  of  the  greatest  diameter,  add  the 
square  of  twice  the  diameter  at  one-fourth  of  its  length ; multiply  the  sum  by  the  length,  and  the  pro- 
duct by  '1309,  and  it  will  give  the  solidity,  very  nearly. 

To  find  the  solidity  of  a frustum  or  segment  of  an  elliptic  spindle. — Rule. — Proceed,  as  in  the  last 
rule,  for  this,  or  any  other  solid,  formed  by  the  revolution  of  a conic  section  about  an  axis,  namely  : 

Add  together  the  squares  of  the  greatest  and  least  diameters,  and  the  square  of  double  the  diameter 
in  the  middle  between  the  two;  multiply  the  sum  by  the  length,  and  the  product  by  -1309,  and  it  will 
give  the  solidity. 

Note. — For  all  such  solids  this  rule  is  exact  when  the  body  is  formed  by  the  conic  section,  or  a part 
of  it,  revolving  about  the  axis  of  the  section  ; and  it  will  always  be  very  near  the  truth,  when  the  figure 
revolves  about  another  line. 

To  find  the  solidity  of  a parabolic  conoid. — Rule. — Multiply  the  square  of  the  diameter  of  the  base 
by  the  altitude,  and  the  product  by  -3927. 

To  find  the  solidity  of  a frustum  of  a paraboloid. — -Rule. — Multiply  the  sum  of  the  squares  of  the 
diameters  of  the  two  ends  by  the  height  of  the  frustum,  and  the  product  by  -3927. 

To  find  the  solidity  of  a parabolic  spindle. — Rule. — Multiply  the  square  of  the  middle  diameter  by 
the  length  of  the  spindle,  and  the  product  by  '41888,  (which  is  eight-fifteenths  of -7854,)  and  it  will  give 
the  content. 

To  find  the  solidity  of  the  middle  frustum  of  a parabolic  spindle. — Rule. — Add  together  8 times  the 
square  of  the  greatest  diameter,  3 times  the  square  of  the  least  diameter,  and  4 times  the  product  of 
these  two  diameters;  multiply  the  sum  by  the  length,  and  the  product  by  '05236,  (which  is  -J  of 
3-1416  ;)  this  will  give  the  solidity. 

To  find  the  convex  surface  of  a cylindrical  ring. — Rule. — To  the  thickness  of  the  ring  add  the  inner 
diameter ; multiply  this  sum  by  the  thickness,  and  the  product  by  9'8696,  (which  is  the  square  of 
3-14159,)  and  it  will  give  the  superficies  required. 

To  find  the  solidity  of  a cylindrical  ring. — Rule. — To  the  thickness  of  the  ring  add  the  inner  diameter  ; 
then  multiply  the  sum  by  the  square  of  the  thickness,  and  the  product  by  2-4674,  (which  is  one-fourth 
of  the  square  of  3-1416,)  and  it  will  give  the  solidity. 

To  find  the  superficies  or  solidity  of  any  regular  body. — Rule  1. — Multiply  the  tabular  surface  by  the 
square  of  the  linear  edge,  and  the  product  will  be  the  superficies. 

Rule  2. — Multiply  the  tabular  solidity  by  the  cube  of  the  linear  edge,  and  the  product  will  be  the 
solidity. 


Table  of  the  Surfaces  and  Solidities  of  the  Regular  Bodies  when  the  linear  edge  is  1. 


No.  of  Sides. 

Names. 

Surfaces. 

Solidities. 

4 

Tetrahedron 

1-73205 

0-11785 

6 

Hexahedron 

6-00000 

1-00000 

8 

Octahedron 

3-46410 

0-47140 

12 

Dodecahedron 

20-64573 

7-66312 

20 

Icosahedron 

8-66025 

2-18169 

METALS  AND  ALLOYS,  employed  in  the  mechanical  and  useful  arts.  Metals  are  elementary 
oodies,  being  all  capable  of  combining  with  oxygen,  and  many  of  them,  during  this  combination,  exhibit 
the  phenomena  of  combustion.  Formerly  only  seven  metals  were  known,  but  modern  discoveries  have 
added  to  the  number  greatly.  Metals  are  distinguished  by  their  great  specific  gravity,  considerable 
tenacity  and  hardness,  opacity,  and  property  of  reflecting  the  greater  part  of  the  light  which  fells  on 
their  surface,  giving  rise  to  what  is  denominated  the  metallic  lustre  or  brilliancy.  Opacity  is  another 
leading  property  of  metals ; even  when  beat  to  the  greatest  possible  thinness,  "they  transmit  scarcely 
any  light;  from  the  union  of  the  two  qualities  density  and  opacity,  arises  that  of  lustre.  By  their 
opacity  and  the  denseness  of  their  texture,  they  reflect  the  greatest  part  of  the  light  that  falls  on  their 
surface.  From  their  density  they  are  susceptible  of  a fine  polish,  by  which  their  lustre  is  increased 


378 


METALS  AND  ALLOYS. 


Tenacity  distinguishes  a number  of  the  metals,  and  is  not  possessed  in  any  great  degree  by  othel 
bodies ; hence  arises  their  malleability  and  ductility.  Some  of  the  metals  are  neither  malleable  not 
ductile.  Both  these  qualities  are  greater  in  combinations  of  the  metals  than  in  the  individual  metals. 
Metals  are  the  best  conductors  of  caloric ; their  expansibilities  are  various,  and  are  probably  nearly  in 
the  order  of  their  fusibilities.  Mercury  melts  at  so  low  a temperature,  that  it  can  be  obtained  in  the 
solid  state  only  at  a very  low  temperature ; others,  as  platina,  can  scarcely  be  melted  by  the  most  in- 
tense heat  which  we  can  excite.  Metals  may  be  volatilized ; at  the  degree  of  600  quicksilver  may  be 
volatilized,  and  zinc  and  arsenic  at  a temperature  not  very  remote  from  this.  Metals  are  the  best  con- 
ductors of  electricity. 

Table  of  the  Properties  of  the  Metals. 


Name. 

When  dis- 
covered. 

By  whom. 

Color. 

Specific 

gravity. 

fcf~ 

o 

o. 

Scale  of 
ductility. 

Scale  of 
malleability. 

Tenacity. 

Ratio  of 
hardness. 

Gold 1 

Pure  yellow. 

19-257 

5237 

1 

i 

08-210 

8 

Silver 

White. 

10-474 

3077 

2 

2 

85  062 

6 

Iron ^. . 

Known  from 

Blue-gray. 

7-788 

17077 

4 

8 

209-659 

3 

Copper  

the  earliest 

Red. 

8-895 

4587 

5 

3 

157-399 

5 

Mercury 

ages. 

White. 

13-508 

30 

None. 

head 

Blue. 

1 1-352 

594 

8 

0 

14 

Tin 

White. 

7-291 

442 

7 

4 

24-200 

12 

Zinc 

1.141 

Paracelsus. 

Bluish-white. 

0001 

700 

6 

7 

12-720 

9 

Bismuth 

1.TJ0 

Agricola. 

Yellowish-white. 

9-822 

470 

7 

Antimony 

XVth  cent. 

B.  Valent. 

Bluish-white. 

6*702 

932 

10 

Arsenic 

1723 

Brandt. 

Gray. 

8-308 

13 

Cobalt 

do. 

Gray-white. 

8-538 

10077 

11 

Platinum 

i?4i 

Wood. 

Bluish-white. 

21-500 

G.  B.  P. 

3 

5 

124-000 

4 

Nickel 

1751 

Cronstedt. 

White. 

8-279 

21877 

9 

9 

Manganese 

1774 

Scheele. 

Gray- white. 

5*850 

do. 

2 

Tungsten 

1781 

D'EIhuyart. 

7*600 

G.  B.  P. 

i 

Tellurium 

1782 

Muller. 

6*115 

Molybdenum 

do. 

Iljelm. 

Gray. 

7*400 

G.  B.  P. 

Titanium 

1781 

G regor. 

Red. 

do. 

Uranium 

1789 

Klaproth. 

Gray. 

9-000 

do. 

Chromium 

1707 

Vauquelin. 

do. 

Columbium 

1802 

Hatchett. 

do. 

Palladium 

1803 

Wollaston. 

Bluish-white. 

li-300 

10 

10 

i 

Rhodium 

do. 

do. 

Grayish- white 

g.  ii.  p. 

Iridium 

do. 

Descot  i Is. 

Osmium 

do. 

Tenant. 

Bluish-black. 

do. 

Cerium 

1804 

Berzelius. 

Gray- white. 

do. 

Potassium "j 

do. 

0-805 

130 

100 

Sodium [ 

do. 

0-972 

194 

100 

Barium 

1807 

Davy. 

Strontium j 

Calcium J 

...  # 

Cadmium 

1818 

Stromeyer. 

White. 

8-004 

ii 

ii 

Lithium 

do. 

Arfvedson. 

Silicium 

1824  1 

Berzelius. 

Zinconium 

....  j 

do. 

Aluminum 

1828  1 

Wohler. 

Glucinum 

do. 

Yttrium 

....  \ 

do. 

Thonium 

1829 

Berzelius. 

Magnesium 

do. 

Bussy. 

Varadium 

1830 

Seftstrom. 

Lantanium 

1840 

Mosander. 

I 

A ntimony * is  of  a silvery  white  color,  brittle  and  crystalline  in  its  ordinary  texture.  It  fuses  at  about 
800°,  or  at  a dull-red  heat,  and  is  volatile  at  a white  heat.  Its  specific  gravity  is  6-7 1 2.  ( Hatchett , 

Phil.  Trans.  1803.  Brande , 849.) 

Antimony  expands  on  cooling;  it  is  scarcely  used  alone,  except  in  combination  with  similar  bars  of 
other  metals  for  producing  thermo-electricity:  but  antimony,  which  in  the  metallic  state  is  frequently 
called  “regulus,”  is  generally  combined  with  a large  portion  of  lead,  and  sometimes  with  tin,  and  other 
metals.  See  Lead  and  Tin. 

“Antimony  and  tin,  mixed  in  equal  proportions,  form  a moderately  hard,  brittle,  and  very  brilliant 
alloy,  capable  of  receiving  an  exquisite  polish,  and  not  easily  tarnished  by  exposure  to  the  air;  it  has 
been  occasionally  manufactured  into  speculums  for  telescopes.  Its  sp.  gr.,  according  to  Gellert,  is  less 
than  the  mean  of  its  constituent  parts.” — Aikin’s  Dictionary. 

Bismuth  is  a brittle  white  metal,  with  a slight  tint  of  red;  its  specific  gravity  is  9'822.  ( Hatchett , 

Phil.  Trans.  1803.)  It  fuses  at  476°,  {Crichton,)  507°,  ( Rudberg ,)  and  always  crystallizes  on  cooling. 
According  to  Chaudet,  pure  bismuth  is  somewhat  flexible.  A cast  bar  of  the  metal  (see  Rennie ) one- 
tenth  of  an  inch  in  diameter,  supports,  according  to  Muschenbroek,  a weight  of  48  pounds.  Bismuth  is 
volatile  at  a high  heat,  and  may  be  distilled  in  close  vessels.  It  transmits  heat  more  slowly  than  most 
other  metals,  perhaps  in  consequence  of  its  texture.  ( Brande , 861.) 


* The  alloys  are  in  general  arranged  under  those  metals  which  constitute  respectively  their  largest  proportional  port** 

but  in  some  lew  instances  under  those  from  which  they  derive  their  peculiar  characters. 


METALS  AND  ALLOTS. 


379 


Bismuth  is  scarcely  used  alone,  but  it  is  employed  for  imparting  fusibility  to  alloys,  thus: 

8 bismuth,  5 lead,  3 tin,  constitute  Newton’s  fusible  alloy,  which  melts  at  212°  F. 

2 bismuth,  1 lead,  1 tin,  Rose’s  fusible  alloy,  which  melts  at  201°  F. 

5 bismuth,  3 lead,  2 tin,  when  combined  melt  at  199°. 

8 bismuth,  5 lead,  4 tin,  1 type-metal,  constitute  the  fusible  alloy  used  on  the  Continent  for  producing 
the  beautiful  casts  of  the  French  medals,  by  the  clicliee  process.  The  metals  should  be  repeatedly 
melted  and  poured  into  drops  until  they  are  well  mixed.  Mr.  Charles  Y.  Walker  substituted  antimony 
for  the  type-metal,  and  strongly  recommends  this  latter  in  preference  to  the  first-named  fusible  alloy 
Electrotype  Manipulation,  Part  II.  p.  9-11,  where  the  clichee  process  is  described. 

1 bismuth  and  2 tin  make  the  alloy  Mr.  Cowper  found  to  be  the  most  suitable  for  rose-engine  and 
eccentric-turned  patterns,  to  be  printed  from  after  the  manner  of  letter-press.  He  recommends  the  thin 
plates  to  be  cast  upon  a cold  surface  of  metal  or  stone,  upon  which  a piece  of  smooth  paper  is  placed, 
and  then  a metal  ring;  the  alloy  should  neither  burr  nor  crumble;  if  proper,  it  turns  soft  and  silky; 
when  too  crystalline,  more  tin  should  be  added. 


2 bismuth,  4 lead,  3 tin, 
1 bismuth,  1 lead,  2 tin, 


constitute  pewterer's  soft  solders. 


All  these  alloys  must  be  cooled  quickly  to  avoid  the  separation  of  the  bismuth ; they  are  rendered 
more  fusible  by  a small  addition  of  mercury. 

Copper,  with  the  exception  of  titanium,  is  the  only  metal  which  has  a red  color  ; it  has  much  lustre, 
is  very  malleable  and  ductile,  and  exhales  a peculiar  smell  when  warmed  or  rubbed.  It  melts  at  a 
bright-red  or  dull-white  heat;  or,  according  to  Daniell,  at  a temperature  intermediate  between  the 
fusing  points  of  silver  and  gold  = 1996°  Fabr.  Its  specific  gravity  varies  from  8‘86  to  8'89 ; the 
former  being  the  least  density  of  cast  copper,  the  latter  the  greatest  of  rolled  or  hammered  copper. 
( Brande , 812) 

Copper  is  used  alone  for  many  important  purposes,  and  very  extensively  for  the  following : namely, 
sheathing  and  bolts  for  ships,  brewing,  distilling,  and  culinary  vessels.  Some  of  the  fire-boxes  for  loco- 
motive engines,  boilers  for  marine  engines,  rollers  for  calico-printing  and  paper-making,  plates  for  the 
use  of  engravers,  <fcc. 

Copper  is  used  in  alloying  gold  and  silver,  for  coin,  plate,  Ac.,  and  it  enters  with  zinc  and  nickel  into 
the  composition  of  German  silver.  Copper  alloyed  with  one-tenth  of  its  weight  of  arsenicis  so  similar  in 
appearance  to  silver,  as  to  have  been  substituted  for  it. 

The  alloys  of  copper,  which  are  very  numerous  and  important,  are  principally  included  under  the 
general  name  Brass.  In  the  more  common  acceptation,  brass  means  the  yellow  alloy  of  copper,  with 
about  half  its  weight  of  zinc  ; this  is  often  called  by  engineers  “ yellow  brass.” 

Copper  alloyed  with  about  one-ninth  its  weight  of  tin,  is  the  metal  of  brass  ordnance,  which  is  very 
generally  called  gun-metal;  similar  alloys  used  for  the  brasses  or  bearings  of  machinery,  are  called  by 
engineers  hard  brass,  and  also  gun-metal ; and  such  alloys,  when  employed  for  statues  and  medals,  are 
called  bronze.  The  further  addition  of  tin  leads  to  bell-metal,  and  speculum-metal,  which  are  named 
after  their  respective  uses  ; and  when  the  proportion  of  copper  is  exceedingly  small,  the  alloy  constitutes 
one  kind  of  pewter. 

Copper,  when  alloyed  with  nearly  half  its  weight  of  lead,  forms  an  inferior  alloy,  resembling  gun 
metal  in  color,  but  very  much  softer  and  cheaper,  lead  being  only  about  one-fourth  the  value  of  tin,  and 
used  in  much  larger  proportion.  This  inferior  alloy  is  called  pot-metal,  and  also  cock-metal,  because  it 
is  used  for  large  vessels  and  measures,  for  the  large  tapis  or  cocks  for  brewers,  dyers,  and  distillers,  and 
those  of  smaller  kinds  for  household  use. 

Generally  the  copper  is  only  alloyed  with  one  of  the  metals,  zinc,  tin,  or  lead  ; occasionally  with  two, 
and  sometimes  with  the  three  in  various  proportions.  In  many  cases  the  new  metals  are  carefully 
weighed  according  to  the  qualities  desired  in  the  alloy,  but  random  mixtures  more  frequently  occur, 
from  the  ordinary  practice  of  filling  the  crucible  in  great  part  with  various  pieces  of  old  metal,  of  un- 
known proportions,  and  adding  a certain  quantity  of  new  metal  to  bring  it  up  to  the  color  and  hardness 
required.  This  is  not  done  solely  from  motives  of  economy,  but  also  from  an  impression  which  appears 
to  be  very  generally  entertained,  that  such  mixtures  are  more  homogeneous  than  those  composed  en- 
tirely of  new  metals,  fused  together  for  the  first  time. 

The  remarks  we  have  to  oiler  on  these  copper  alloys  will  be  arranged  in  the  tabular  form,  in  four 
groups;  and,  to  make  them  as  practical  as  possible,  they  will  be  stated  in  the  terms  commonly  used  in 
the  brass-foundry.  Thus,  when  the  founder  is  asked  the  usual  proportions  of  yellow  brass,  he  will  say, 
6 to  8 oz.  of  zinc,  (to  every  pound  of  copper  being  implied.)  In  speaking  of  gun-metal,  he  would  not 
say,  it  had  one-ninth,  or  11  per  cent,  of  tin,  but  simply  that  it  was  1-J,  2,  or  21  oz.,  (of  tin,)  as  the  case 
might  be ; so  that  the  quantity  and  kind  of  the  alloy,  or  the  addition  to  the  pound  of  copper,  is  usually 
alone  named. 


Alloys  of  copper  and  zinc  only. — The  marginal  numbers  denote  the  ounces  of  zinc  added  to  every 

pound  of  copper. 

£ to  I oz.  Castings  are  seldom  made  of  pure  copper,  as  under  ordinary  circumstances  it  does  not  cast 
soundly:  about  half  an  ounce  of  zinc  is  usually  added,  frequently  in  the  shape  of  4 oz.  of  brass 
to  every  pound  of  copper ; and  by  others  4 oz.  of  brass  are  added  to  every  two  or  three  pounds 
of  copper. 

1 to  II  oz.  Gilding-metal,  for  common  jewelry : it  is  made  by  mixing  4 parts  of  copper  with  1 of  cal- 
amine brass  ; or  sometimes  1 lb.  of  copper  with  6 oz.  of  brass.  The  sheet  gilding-metal  will  be 
found  to  match  pretty  well  in  color  with  the  cast  gun-metal,  which  latter  does  not  ,.<tcnii  of  being 
rolled ; they  may  be  therefore  used  together  when  required. 

8 oz.  Red  sheet-brass,  made  at  Hegermiihl,  or  5^  parts  copper,  1 zinc.  (Urc.) 


380 


METALS  AND  ALLOYS. 


B to  4 oz.  Bath  metal,  pinchbeck,  Mannheim  gold,  similor,  and  alloys  bearing  various  names,  and  re- 
sembling inferior  jeweller’s  gold  greatly  alloyed  with  copper,  are  of  about  this  proportion:  some 
of  them  contain  a little  tin ; now,  however,  they  are  scarcely  used. 

6 oz.  Brass,  that  bears  soldering  well. 

6 oz.  Bristol  brass  is  said  to  be  of  this  proportion. 

8 oz.  Ordinary  brass,  the  general  proportion ; less  fit  for  soldering  than  G oz.,  it  being  more  fusible. 

8 oz.  Emerson’s  patent  brass  was  of  this  proportion,  and  so  is  generally  the  ingot  brass,  made  by  sim 

pie  fusion  of  the  two  metals. 

9 oz.  This  proportion  is  the  one  extreme  of  Muntz’s  patent  sheathing.  See  10§. 

lOf  oz.  Muntz’s  metal,  or  40  zinc  and  60  copper.  “ Any  proportions,”  says  the  patentee,  “ between 
the  extremes  50  zinc  and  50  copper,  and  37  zinc  63  copper,  will  roll  and  work  at  the  red-heat 
but  the  first-r.amed  proportion,  or  40  zinc  to  60  copper,  is  preferred. 

The  metal  is  cast  into  ingots,  heated  to  a red-heat,  and  rolled  and  worked  at  that  heat  into 
ships’  bolts  and  other  fastenings  and  sheathing. 

12  oz.  Spelter-solder  for  copper  and  iron  is  sometimes  made  in  this  proportion;  for  brass  work  the 
metals  are  generally  mixed  in  equal  parts.  See  16  oz. 

12  oz.  Pale-yellow  metal,  fit  for  dipping  in  acids,  is  often  made  in  this  proportion. 

16  oz.  Soft  spelter-solder,  suitable  for  ordinary  brass-work,  is  made  of  equal  parts  of  copper  and  zinc. 
About  14  lbs.  of  each  are  melted  together  and  poured  into  an  ingot-mould  with  cross-ribs,  which 
indents  it  into  little  squares  of  about  2 lbs.  weight ; much  of  the  zinc  is  lost.  These  lumps  are 
afterwards  heated  nearly  to  redness  upon  a charcoal  fire,  and  are  broken  up,  one  at  a time,  with 
great  rapidity  on  an  anvil,  or  in  an  iron  pestle  and  mortar.  The  heat  is  a critical  point ; if  too 
great,  the  solder  is  beaten  into  a cake  or  coarse  lumps  and  becomes  tarnished  ; when  the  heat  is 
proper,  it  is  nicely  granulated,  and  remains  of  a bright-yellow  color ; it  is  afterwards  passed 
through  a sieve.  Of  course,  the  ultimate  proportion  is  less  than  16  oz.  of  zinc. 

16  oz.  Equal  parts  is  the  one  extreme  of  Muntz’s  patent  sheathing.  See  10f. 

16£  oz.  Hamilton  and  Parker’s  patent  mosaic  gold,  which  is  dark-colored  when  first  cast,  but  on  dip- 
ping assumes  a bp&_tiful  golden  tint.  When  cooled  and  broken,  say  the  patentees,  “ all  yellow- 
ness must  cease,  and  the  tinge  vary  from  reddish-fawn  or  salmon  color  to  a light  purple  or  lilac, 
and  from  that  to  whiteness.”  The  proportions  are  stated  as  from  52  to  58  zinc  to  50  of  copper, 
or  16f  to  17  oz.  to  the  pound. 

32  oz.,  or  2 zinc  to  1 copper,  a bluish-white  brittle  alloy,  very  brilliant,  and  so  crystalline  that  it  may 
be  pounded  cold  in  a pestle  and  mortar. 

128  oz.,  or  2 oz.  of  copper  to  every  pound  of  zinc;  a hard  crystalline  metal,  differing  but  little  from 
zinc,  but  more  tenacious ; it  has  been  used  for  laps  or  polishing  disks. 

Remarks  on  the  alloys  of  copper  and  zinc. — These  metals  seem  to  mix  in  all  proportions. 

The  addition  of  zinc  continually  increases  the  fusibility,  but  from  the  extremely  volatile  nature  of  zinc, 
these  alloys  cannot  be  arrived  at  with  very  strict  regard  to  proportion. 

The  red  color  of  copper  slides  into  that  of  yellow  brass  at  about  4 or  5 oz.  to  the  pound,  and  remains 
little  altered  unto  about  8 or  10  oz. ; after  this  it  becomes  whiter,  and  when  32  oz.  of  zinc  are  added  to 
16  of  copper,  the  mixture  has  the  brilliant  silvery  color  of  speculum  metal,  but  with  a bluish  tint. 

These  alloys,  from  about  8 to  16  oz.  to  the  pound  of  copper,  are  extensively  used  for  dipping,  as  in 
an  enormous  variety  of  furniture  work ; in  all  cases  the  metal  is  annealed  before  the  application  of  the 
scouring  or  cleaning  processes,  and  of  the  acids,  bronzes,  and  lackers  subsequently  used. 

The  alloys  with  zinc  retain  their  malleability  and  ductility  well,  unto  about  8 or  10  oz.  to  the  pound  ; 
after  this  the  crystalline  character  slowly  begins  to  jjrevail.  The  alloy  of  2 zinc  and  1 copper,  before 
named,  may  be  crumbled  in  a mortar  when  cold. 

The  ordinary  range  of  good  yellow  brass,  that  files  and  turns  well,  is  from  about  4J  to  9 oz.  to  the 
pound.  With  additional  zinc,  it  is  harder  and  more  crystalline ; with  less,  more  tenacious,  and  it  hangs 
to  the  file  like  copper ; the  range  is  wide,  and  small  differences  are  not  perceived. 

Alloys  of  copper  and  tin  only. — The  marginal  numbers  denote  the  ounces  of  tin  added  to  every 
pound  of  copper. 

Ancient  Copper  and  Tin  Alloys. 


| oz. 

If  oz. 
2 oz. 
2f  oz. 

6 to  8 

1 oz. 
1|  oz. 
1 1 oz. 
U to 

2 oz. 
24  oz. 


3 oz. 
3J  oz. 

4 oz. 


Ancient  bronze  nails  flexible,  or  20  copper,  1 tin, 

Soft  bronze,  or  9 to  1. 

Medium  bronze,  or  8 to  1. 

Hard  bronze,  or  7 to  1 . 

oz.  Ancient  mirrors. 


(Ure.)  ' 

f According  to  Pliny,  as  quoted  by  Wilkinson. 

) Ancient  weapons  and  tools,  by  various  analyses,  or  8 to  15  per  cent 
) tin ; medals  from  8 to  12  per  cent,  tin,  with  2 parts  zinc  added  tc 
(_  each  100,  for  improving  the  bronze  color.  (Ure.) 


Modern  Copper  and  Tin  Alloys. 

Soft  gun-metal,  that  bears  drifting,  or  stretching  from  a perforation. 

A little  harder  alloy,  fit  for  mathematical  instruments ; or  12  copper  and  one  very  pure  grain  tm. 
Still  harder,  fit  for  wheels  to  be  cut  with  teeth. 

2 oz.  Brass  ordnance,  or  8 to  12  per  cent,  tin ; but  the  general  proportion  is  one-ninth  part  of  tin 
Hard  bearings  for  machinery. 

Very  hard  bearings  for  machinery.  By  Muschenbroek’s  tables  it  appears  that  the  proportion 
1 tin  and  6 copper  is  the  most  tenacious  alloy ; it  is  too  brittle  for  general  use,  and  contains 
oz.  to  the  pound  of  copper. 

For  some  other  alloys  used  in  machinery,  see  alloys  of  copper,  zinc,  tin,  and  lead,  p.  354 
Soft  musical  bells. 

Chinese  gongs  and  cymbals,  or  20  per  cent.  tin. 

House  bells. 


METALS  AND  ALLOYS. 


381 


<1  oz.  Large  bells. 

5 oz.  Largest  bells. 

7i  to  8^  oz.  Speculum  metal.  Sometimes  one  ounce  of  brass  is  added  to  every  pound  as  the  means 
of  introducing  a trifling  quantity  of  juic;  at  other  times  small  proportions  of  silver  are  added; 
the  employment  of  arsenic  was  strongly  advocated  by  the  Rev.  John  Edwards.  Lord  Oxman- 
town,  now  the  Earl  of  Rosse,  says,  “ tin  and  copper,  the  materials  employed  by  Newton  in  the 
first  reflecting  telescope,  are  preferable  to  any  other  with  which  I am  acquainted ; the  best 
proportions  being  4 atoms  of  copper  to  1 of  tin,  (Turner’s  numbers;)  in  fact,  126-4  parts  of  cop- 
per to  58’9  of  tin.” — Trans.  Royal  Soc.  1840,  p.  504. 

The  object  agreed  upon  by  all  experimentalists  appears  to  be  the  exact  saturation  of  the  copper  with 
the  tin,  and  the  proportionate  quantities,  differ  very  materially  (in  this  and  all  other  alloys)  according 
to  the  respective  degrees  of  purity  of  the  metals  : for  the  most  perfect  alloys  of  this  group,  Swedish  cop- 
per and  grain  tin  should  be  used. 

Mr.  Ross  says  : “ When  the  alloy  is  perfect,  it  should  be  white,  glassy,  and  flaky.  When  the  copper 
is  in  excess,  it  imparts  a red  tint  easily  detected;  when  the  tin  is  in  excess,  the  fracture  is  granulated, 
and  also  less  white.”  His  practice  is  to  pour  the  melted  tin  into  the  fluid  copper  when  it  is  at  the  low- 
est temperature  that  a mixture  by  stirring  can  be  effected ; then  to  pour  the  mixture  into  an  ingot,  and 
to  complete  the  combination  by  remelting  in  the  most  gradual  manner,  by  putting  the  metal  into  the 
furnace  as  soon  almost  as  the  fire  is  lighted.  Trial  is  made  of  a little  piece  taken  from  the  pot  imme- 
diately prior  to  pouring. 

82  oz.  of  tin  to  1 lb.  of  copper  make  the  alloy  called  by  the  pewterers  “temper,”  which  is  added  ir 
small  quantities  to  tin  for  some  kinds  of  pewter,  called  “ tin  and  temper,”  in  which  the  copper  is  fi\ 
quently  much  less  than  1 per  cent. 

Remarks  on  the  alloys  of  copper  and  tin  only. — These  metals  seem  to  mix  in  all  proportions. 

The  addition  of  tin  continually  increases  the  fusibility,  although  when  it  is  added  cold  it  is  apt  tc 
make  the  copper  pasty,  or  even  to  set  it  in  a solid  lump  in  the  crucible. 

The  red  color  of  the  copper  is  not  greatly  impaired  in  those  proportions  used  by  the  engineer,  namely 
up  to  about  2-J  oz.  to  the  pound ; it  becomes  grayish  white  at  6,  the  limit  suitable  for  bells,  and  quite 
white  at  about  8,  the  speculum  metal ; after  this,  the  alloy  becomes  of  a bluish  cast. 

The  tin  alloy  is  scarcely  malleable  at  2 oz.,  and  soon  becomes  very  hard,  brittle,  and  sonorous ; ano 
when  it  has  ceased  to  serve  for  producing  sound,  it  is  employed  for  reflecting  light. 

The  tough,  tenacious  character  of  copper  under  the  tools  rapidly  gives  way ; alloys  of  1^  cut  easily 
2 J assume  about  the  maximum  hardness  without  being  crystalline ; after  this  they  yield  to  the  file  bj 
crumbling  in  fragments  rather  than  by  ordinary  abrasion  in  shreds,  until  the  tin  very  greatly  predomi 
nates,  as  in  the  pewters : when  the  alloys  become  the  more  flexible,  soft,  malleable,  and  ductile,  the  less 
copper  they  contain. 

Alloys  of  copper  and  lead  only. — The  marginal  numbers  denote  the  ounces  of  lead  added  to  every 
pound  of  copper. 

2 oz.  A red-colored  and  ductile  alloy. 

4 oz.  Less  red  and  ductile ; neither  of  these  is  so  much  used  as  the  following,  as  the  object  is  to  em- 
ploy as  much  lead  as  possible. 

6 oz.  Ordinary  pot-metal,  called  dry  pot-metal,  as  this  quantity  of  lead  will  be  taken  up  without  sep- 

arating on  cooling ; this  is  brittle  when  warmed. 

7 oz.  This  alloy  is  rather  short,  or  disposed  to  break. 

8 oz.  Inferior  pot-metal,  called  wet  pot-metal,  as  the  lead  partly  oozes  out  in  cooling,  especially  when 

the  new  metals  are  mixed ; it  is  therefore  always  usual  to  fill  the  crucible  in  part  with  old 
metal,  and  to  add  new  for  the  remainder.  This  alloy  is  very  brittle  when  slightly  warmed. 
More  lead  can  scarcely  be  used,  as  it  separates  on  cooling. 

Remarks  on  the  alloys  of  copper  and  lead  only. — These  metals  mix  in  all  proportions  until  the  lead 
amounts  to  nearly  half ; after  this  they  separate  in  cooling. 

The  addition  of  lead  greatly  increases  the  fusibility. 

The  red  color  of  the  copper  is  soon  deadened  by  the  lead ; at  about  4 oz.  to  the  pound  the  work 
has  a bluish  leaden  hue  when  first  turned,  but  changes  in  an  hour  or  so  to  that  of  a dull  gun-metal 
character. 

When  the  lead  does  not  exceed  about  4 oz.  the  mixture  is  tolerably  malleable,  but  with  more  lead  ii 
soon  becomes  very  brittle  and  rotten ; the  alloy  is  greatly  inferior  to  gun-metal,  and  is  principally  used 
on  account  of  the  cheapness  of  the  mixture,  and  the  facility  with  which  it  is  turned  and  filed. 

Alloys  of  copper,  zinc,  tin,  and  lead,  d'c. — This  group  refers  principally  to  gun-metal  alloys,  to  which 
more  or  less  zinc  is  added  by  many  engineers  ; the  quantity  of  tin  in  eveiy  pound  of  the  alloy,  which  is 
expressed  by  the  marginal  numbers,  principally  determines  the  hardness. 

Keller’s  statues  at  Versailles  are  found  as  the  mean  of  four  analyses,  to  consist  of 


Copper 91 -40,  or  about  14f  ounces. 

Zinc  5 53  “ 1 “ 

Tin 1-70  “ f “ 

Lead  1-37  “ $ “ 


In  100  parts  or  the  16  ounces. 

li  to  2^  oz.  tin  to  1 lb.  copper  used  for  bronze  medals,  or  8 to  15  per  cent,  tin,  with  the  addition  of  2 
parts  in  each  100  of  zinc,  to  improve  the  color. 

The  modem  so-called  bronze  medals  of  our  mint  are  of  pure  copper,  and  are  afterwards 
bronzed  superficially. 

I \ oz.  tin  4 zinc  to  16  oz.  copper.  Pumps  and  works  requiring  great  tenacity. 


382 


METALS  AND  ALLOYS. 


For  wheels  to  be  cut  into  teeth. 

For  turning-work. 

For  nuts  of  coarse  threads,  and  bearings. 

The  engineer  who  uses  these  five  alloys  recommends  melting  the  copper  alone : the  small 
quantity  of  brass  is  then  melted  in  another  crucible,  and  the  tin  in  a ladle ; the  two  latter  are 
added  to  the  copper  when  it  has  been  removed  from  the  furnace ; the  whole  are  stirred  together 
and  poured  into  the  moulds  without  being  run  into  ingots.  The  real  quantity  of  tin  to  every 
pound  of  copper  is  about  one-eighth  ounce  less  than  the  numbers  stated,  owing  to  the  addition  of 
the  brass,  which  increases  the  proportion  of  copper. 

\l  oz.  tin,  1|  oz.  zinc,  to  1 lb.  of  copper.  This  alloy,  which  is  a tough,  yellow,  brassy  gun-metal,  is  used 
for  general  purposes  by  a celebrated  engineer ; it  is  made  by  mixing  1 £ lb”  tin,  1 £ lb.  zinc,  and 
10  lbs.  of  copper : the  alloy  is  first  run  into  ingots. 

%£  oz.  tin,  £ oz.  zinc,  to  1 lb.  of  copper,  used  for  bearings  to  sustain  great  weights. 

2£  oz.  tin,  2£  oz.  zinc,  to  1 lb.  copper,  were  mixed  by  the  late  Sir  F.  Chantry,  and  a razor  was  made  from 
the  alloy ; it  proved  nearly  as  hard  as  tempered  steel,  and  exceedingly  destructive  to  new  files, 
and  none  others  would  touch  it. 

1 oz.  tin,  2 oz.  zinc,  16  oz.  brass.  Best  hard  white  metal  for  buttons. 

£ oz.  tin,  1£  oz.  zinc,  16  oz.  brass.  Common  ditto.  (Phillips’s  Dictionary.) 

0 lbs.  tin,  6 lbs.  copper,  4 lbs.  brass,  constitute  white  solder.  The  copper  and  brass  are  first  melted 
together,  the  tin  is  added,  and  the  whole  stirred  and  poured  through  birch  twigs  into  water  to 
granulate  it ; it  is  afterwards  dried  and  pulverized  cold  in  an  iron  pestle  and  mortar.  This 
white  solder  was  introduced  as  a substitute  for  silver  solder  in  making  gilt  buttons.  Another 
button  solder  consists  of  10  parts  copper,  8 of  brass,  and  12  of  spelter  or  zinc. 

Remarks  on  alloys  of  copper,  zinc,  tin,  lead,  dec. — Ordinary  yellow  brass,  (copper  and  zinc,)  is 
rendered  very  sensibly  harder,  so  as  not  to  require  to  be  hammered,  by  a small  addition  of  tin,  say  4 
or  £ oz.  to  the  lb.  On  the  other  hand,  by  the  addition  of  £ to  £ oz.  of  lead,  it  becomes  more  malleable 
and  casts  more  sharply.  Brass  becomes  a little  whiter  for  the  tin,  and  redder  for  the  lead.  The  addi- 
tion of  nickel  to  copper  and  zinc  constitutes  the  so-called  German  silver. 

Gun-metal  (copper  and  tin)  very  commonly  receives  a small  addition  of  zinc ; this  makes  the  alloy 
mix  better,  and  to  lean  to  the  character  of  brass  by  increasing  the  malleability  without  materially  re- 
ducing the  hardness.  The  standard  measures  for  the  Exchequer  were  made  of  a tough  alloy  of  this 
kind.  The  zinc,  which  is  sometimes  added  in  the  form  of  brass,  also  improves  the  color  of  the  alloy, 
both  in  the  recent  and  bronzed  states.  Lead,  in  small  quantity,  improves  the  ductility  of  gun-metal, 
but  at  the  expense  of  its  hardness  and  color;  it  is  seldom  added.  Nickel  has  been  proposed  as  an  ad- 
dition to  gun-metal  by  Mr.  Donkin,  and  antimony  by  Dr.  Ure. 

Pot-metal  (copper  and  lead)  is  improved  by  the  addition  of  tin,  and  the  three  metals  will  mix  in 
almost  any  proportions : when  the  tin  predominates,  the  alloy  so  much  the  more  nearly  approaches 
the  condition  of  gun-metaL  Zinc  may  be  added  to  pot-metal  in  very  small  quantity,  but  when  the 
zinc  becomes  a considerable  amount,  the  copper  takes  up  the  zinc,  forming  a kind  of  brass,  and  leaves 
the  lead  at  liberty,  and  which,  in  great  measure,  separates  in  cooling.  Zinc  and  lead  are  also  very  in- 
disposed to  mix  alone,  although  a little  arsenic  assists  their  union  by  “ killing”  the  lead  as  in  shot- 
metal.  Antimony  also  facilitates  the  combination  of  pot-metal;  7 lead,  1 antimony,  and  16  copper 
mixed  perfectly  well  the  first  fusion,  and  the  alloy  was  decidedly  harder  than  4 lead  and  16  copper; 
and  apparently  a better  metal.  “ Lead  and  antimony,  though  in  small  quantity,  have  a remarkable 
effect  in  diminishing  the  elasticity  and  sonorousness  of  the  copper  alloys.” 

Gold  is  of  a deep  and  peculiar  yellow  color.  It  melts  at  a bright-red  heat,  equivalent,  according 
to  Daniell,  to  2016°  of  Fahrenheit’s  scale,  and  when  in  fusion  appears  of  a brilliant  greenish  color.  Its 
specific  gravity  is  19'3.  It  is  so  malleable  that  it  may  be  extended  into  leaves  which  do  not  exceed 
the  one  two  hundred  and  eighty-two  thousandth  of  an  inch  in  thickness,  or  a single  grain  may  be  ex- 
tended over  56  square  inches  of  surface.  This  extensibility  of  the  metal  is  well  illustrated  by  gilt 
buttons,  144  of  which  are  gilt  by  5 grains  of  gold,  and  less  than  even  half  that  quantity  is  adequate  by 
giving  them  a very  thin  coating.  It  is  also  so  ductile  that  a grain  may  be  drawn  out  into  500  feet  of 
wire.  The  pure  acids  have  no  action  upon  gold.  (Brande,  972.) 

Gold,  in  the  pure  or  fine  state,  is  not  employed  in  bulk  for  many  purposes  in  the  arts,  as  it  is  then 
too  soft  to  be  durable.  The  gold  foil  used  by  dentists  for  stopping  decayed  teeth  is  perhaps  as  nearly 
pure  as  the  metal  can  be  obtained  : it  contains  about  six  grains  of  alloy  in  the  pound  troy,  or  the  one- 
thousandth  part.  Every  superficial  inch  of  this  gold  foil  or  leaf  weighs  J of  a grain,  and  is  42  times  as 
thick  as  the  leaf  used  for  gilding. 

The  wire  for  gold  lace  prepared  by  the  refiners  for  gold-lace  manufacturers,  requires  equally  fine 
gold,  as  when  alloyed  it  does  not  so  well  retain  its  brilliancy.  The  gold,  in  the  proportion  of  about  100 
grains  to  the  pound  troy  of  silver,  or  of  140  grains  for  double-gilt  wire,  is  beaten  into  sheets  as  thin  as 
paper  ; it  is  then  burnished  upon  a stout  red-hot  silver  bar,  the  surface  of  which  has  been  scraped  per- 
fectly clean.  When  extended  by  drawing,  the  gold  still  bearing  the  same  relation  as  to  quantity, 
namely,  the  57th  part  of  the  weight,  becomes  of  only  one-third  the  thickness  of  ordinary  gold-leaf  used 
for  gilding.  In  water-gilding,  fine  gold  is  amalgamated  with  mercury,  and  washed  over  the  gilding 
metal,  (copper  and  tin  ;)  the  mercury  attaches  itself  to  the  metal,  and  when  evaporated  by  heat,  it 
leaves  the  gold  behind  in  the  dead  or  frosted  state  : it  is  brightened  with  the  burnisher.  (See  Tech- 
nological Repository,  vol.  ii.,  p.  361  : 1828.)  By  the  electrotype  process,  a still  thinner  covering  of 
pure  gold  may  be  deposited  on  silver,  steel,  and  other  metals.  Mr.  Dent  has  introduced  this  method 
»f  protecting  the  steel  pendulum-springs  of  marine  chronometers  and  other  time-pieces  from  rust. 

Fine  gold  is  also  used  for  soldering  chemical  vessels  made  of  platinum. 

Gold  alloys. — Gold-leaf,  for  gilding,  contains  from  3 to  12  grains  of  alloy  to  the  oz.,  but  generally  i 


l-J  oz.  tin  2 oz.  brass  16 

if  “ 2 “ 16 

2 “ 1£  “ 16 

2*  “ 14  “ 16 


METALS  AND  ALLOYS. 


3 S3 


grains.  The  gold  used  by  respectable  dentists,  for  plates,  is  nearly  pure,  but  necessarily  contains  about 
6 grains  of  copper  in  the  oz.  troy,  or  one-eightieth  part ; others  use  gold  containing  upwards  of  one- 
third  of  alloy:  the  copper  is  then  very  injurious. 

With  copper,  gold  forms  a ductile  alloy  of  a deeper  color,  harder  and  more  fusible  than  pure  gold  : 
this  alloy,  in  the  proportion  of  11  of  gold  to  1 of  copper,  constitutes  standard  gold ; its  density  is  17-157, 
being  a little  below  the  mean,  so  that  the  metals  slightly  expand  on  combining.  One  troy  pound  of 
this  alloy  is  coined  into  46||  sovereigns,  or  20  troy  pounds  into  934  sovereigns  and  a half.  The  pound 
was  formerly  coined  into  44  guineas  and  a half.  The  standard  gold  of  France  consists  of  9 parts  of  gold 
and  1 of  copper.  ( Brande , 979.) 

For  Gold  Plate  the  French  have  three  different  standards : 92  parts  gold,  3 copper  ; also  84  gold,  16 
copper;  and  75  gold,  25  copper. 

In  England,  the  purity  of  gold  is  expressed  by  the  terms  22,  18,  16  carats,  &c.  The  pound  troy  is 
supposed  to  be  divided  into  24  parts,  and  the  gold,  if  it  could  be  obtained  perfectly  pure,  might  be 
called  24  carats  fine. 

The  “ Old  Standard  Gold,”  or  that  of  the  present  currency,  is  called  fine,  there  being  22  parts  of  pure 
gold  to  2 of  copper. 

The  “New  Standard,”  for  watch-cases,  <fec.,  is  18  carats  of  fine  gold,  and  6 of  alloy.  No  gold  of  infe- 
rior quality  to  18  carats,  or  the  “New  Standard,”  can  receive  the  Hall  mark;  and  gold  of  lower  quality 
is  generally  described  by  its  commercial  value,  as  60  or  40  shilling  gold,  tire. 

The  alloy  may  be  entirely  silver,  which  will  give  a green  color,  or  entirely  copper  for  a red  color ; 
but  the  copper  and  silver  are  more  usually  mixed  in  the  one  alloy  according  to  the  taste  and  judgment 
of  the  jeweller. 

The  following  alloys  of  gold  are  transcribed  from  the  memoranda  of  the  proportions  employed  by  a 
practical  jeweller  of  considerable  experience.* 

First  group. — Different  kinds  of  gold  that  are  finished  by  polishing,  burnishing,  &c.,  without  neces- 
sarily requiring  to  be  colored  : 

The  gold  of  22  carats  fine,  or  the  “ Old  Standard,”  is  so  little  used,  on  account  of  its  expense  and 
greater  softness,  that  it  has  been  purposely  omitted. 


18  carats,  or  New  Standard  gold,  of  yellow  tint:* 
15  dwt.  0 grs.  gold. 

2 dwt.  18  grs.  silver. 

2 dwt.  6 grs.  copper. 


20  dwt.  0 grs. 


18  carats,  or  New  Standard  gold,  of  red  tint:* 
15  dwt.  0 grs.  gold. 

1 dwt.  18  grs.  silver. 

3 dwt.  6 grs.  copper. 


20  dwt.  0 grs. 


16  carats,  or  Spring  gold:  this,  when  drawn  or 
rolled  very  hard,  makes  springs  little  inferior  to 
those  of  steel : 

1 oz.  16  dwt.  gold.  or  T12 
6 dwt,  silver.  — -4 

12  dwt.  copper.  — T2 


80s.  gold  of  yellow  tint,  or  the  fine  gold  of  the  jew- 
ellers; 16  carats  nearly  : 

1 oz.  0 dwt.  gold. 

7 dwt.  silver. 

5 dwt,  copper. 

1 oz.  12  dwt. 


60s.  gold  of  red  tint,  or  16  carats  : 
1 oz.  0 dwt.  gold. 

2 dwt.  silver. 

8 dwt.  copper. 

1 oz.  10  dwt. 


40s.  gold,  or  the  old-fashioned  jewellers’  gold,  about 
1 1 carats  fine  ; no  longer  used : 

1 oz.  0 dwt.  gold. 

12  dwt.  silver. 

12  dwt.  copper. 


2 oz.  14  dwt. 


2 -8 


2 oz.  4 dwt. 


Second  group. — Colored  golds ; these  all  require  to  be  submitted  to  the  process  of  wet-coloring, 
which  will  be  explained : they  are  used  in  much  smaller  quantities,  and  require  to  be  very  exactly  pro- 
portioned. 


Full  red  gold  : 

5 dwt.  gold. 

5 dwt.  copper. 


Green  gold : 

5 dwt.  0 grs.  gold. 
21  grs.  silver. 


10  dwt. 


5 dwt.  21  grs. 


Red  gold : 

10  dwt.  gold. 

1 dwt.  silver. 
4 dwt.  copper. 


Gray  gold  : (Platinum  is  also  called  gray  gold  by 
jewellers :) 

3 dwt.  15  grs.  gold. 

1 dwt.  9 grs.  silver. 


15  dwt. 


5 dwt.  0 grs. 


* When  it  is  not  otherwise  expressed,  it  will  be  understood  all  these  alloys  are  made  with  fine  gold,  fine  silver,  and  fine 
sopper,  obtained  direct  from  the  refiners.  And  to  insure  the  standard  gold  passing  the  test  of  the  Hall,  3 or  4 grains  ad- 
ditional of  gold  are  usually  added  to  every  ounce. 


884 


METALS  AND  ALLOYS. 


Blue  gold  ; scarcely  used : 
5 dwt.  gold. 

5 dwt.  steel  filings. 

10  dwt. 


Antique  gold,  of  a fine  greenish  yellow  color ; 
18  dwt.  9 grs.  gold,  or  18'  9 
21  grs.  silver,  — 1'  3 
18  grs.  copper,  — -12 

20  dwt.  0 grs.  20'  0 


Third  group. — Gold  solders:  these  are  generally  made  from  gold  of  the  same  quality  and  value  aa 
they  are  intended  for,  with  a small  addition  of  silver  and  copper,  thus : 


Solder  for  22  carat  gold  : 

1  dwt.  0 grs.  of  22  carat  gold. 
2 grs.  silver. 

1 gr.  copper. 

1 dwt.  3 grs. 


Solder  for  60s.  gold  :# 
1 dwt.  0 grs.  of  60s.  gold. 
10  grs.  silver. 

8 grs.  copper. 


1 dwt.  18  grs. 


Solder  for  18  carat  gold  : 

1 dwt.  0 grs.  of  IS  carat  gold. 
2 grs.  silver. 

1 gr.  copper. 


1 dwt.  3 grs. 


Solder  for  40s.  gold  ; but  middling  silver  solder  is 
more  generally  used : 

1 dwt.  fine  gold. 

1 dwt.  silver. 

2 dwt.  copper. 

4 dwt. 


Dr.  Hermstadt’s  imitation  of  gold,  which  is  stated  not  only  to  resemble  gold  in  color,  but  also  in  spe- 
cific gravity  and  ductility,  consists  of  16  parts  of  platinum,  7 parts  of  copper,  and  1 of  zinc,  put  in  a 
crucible,  covered  with  charcoal  powder,  and  melted  into  a mass. 

Gold  alloyed  with  platinum  is  also  rather  elastic,  but  the  platinum  whitens  the  alloy  more  rapidly 
than  silver. 

Lead  appears  to  have  been  known  in  the  earliest  ages  of  the  world.  Its  color  is  bluish  white  ; it  has 
much  brilliancy,  is  remarkably  flexible  and  soft,  and  leaves  a black  streak  on  paper  : when  handled  it 
exhales  a peculiar  odor.  It  melts  at  about  612°,  and  by  the  united  action  of  heat  and  air,  is  readily 
converted  into  an  oxide.  Its  specific  gravity,  when  pure,  is  11 '445  ; but  the  lead  of  commerce  seldom 
exceeds  11'35.  ( Brande , 833.) 

Lead  is  used  in  a state  of  comparative  purity  for  roofs,  cisterns,  pipes,  vessels  for  sulphuric  acid,  <Szc. 
Ships  were  sheathed  with  lead  and  with  wood  from  before  the  Christian  era  to  1450,  after  which  wood 
was  more  commonly  employed,  and  in  1790  to  1800  copper  sheathing  became  general;  of  late  years, 
lead  with  a little  antimony  has  likewise  been  used,  also  Muntz’s  sheathing,  an  alloy  of  copper  ana  zinc 
and  galvanized  sheet-iron.  The  most  important  alloys  are  those  employed  for  printers’  type,  namely, 
about 

3 lead,  1 antimony,  for  the  smallest,  hardest,  and  most  brittle  types. 

4 lead,  1 antimony,  for  small,  hard,  brittle  types. 

5 lead,  1 antimony,  for  types  of  medium  size. 

6 lead,  1 antimony,  for  large  types. 

7 lead,  1 antimony,  for  the  largest  and  softest  types. 

The  small  types  generally  contain  from  4 to  6 per  cent,  of  tin,  and  sometimes  also  1 to  2 per  cent, 
of  copper  ; but  as  old  metal  is  always  used  with  the  new,  the  proportions  are  not  exactly  known. 

Stereotype  plates  contain  about  4 to  8 parts  of  lead  to  one  of  antimony. 

Baron  Wetterstedt’s  patent  sheathing  for  ships  consists  of  lead  with  from  2 to  8 per  cent,  of  anti- 
mony ; about  3 per  cent,  is  the  usual  quantity.  The  alloy  is  rolled  into  sheets. 

Similar  alloys,  and  those  of  lead  and  tin  in  various  preparations,  are  much  used  for  emery-wheels  and 
grinding-tools  of  various  forms  by  the  lapidary,  engineer,  and  others.  The  latter  also  employs  these 
readily  fused  alloys  for  temporary  bearings,  guides,  screw-nuts,  &c. 

Organ-pipes  consist  of  lead  alloyed  with  about  half  its  quantity  of  tin  to  harden  it.  The  mottled  or 
crystalline  appearance  so  much  admired  shows  an  abundance  of  tin. 

Shot-metal  is  said  to  consist  of  40  lbs.  of  arsenic  to  one  ton  of  lead. 

In  casting  sheet-lead,  the  metal  was  poured  from  a swing-trough  upon  a long  and  nearly  horizontal 
table,  covered  with  a thin  layer  of  coarse  damp  sand,  previously  levelled  with  a metal  rule  or  strike. 
The  thickness  of  the  fluid  metal  was  determined  by  running  the  strike  along  the  table  before  the  lead 
cooled,  the  excess  being  thus  swept  into  a spill-trough  at  the  lower  end  of  the  table ; but  the  sheet-lead 
now  more  commonly  used  is  cast  in  a thick  slab,  and  reduced  between  laminating  rollers  ; it  is  known 
as  “ milled  lead.” 

The  metal  for  organ-pipes  is  prepared  by  allowing  the  metal  to  escape  through  a slit  in  the  trough, 
as  it  is  slid  along  a horizontal  table,  so  as  to  leave  a trail  of  metal  behind  it ; the  thickness  of  the  metal 
is  regulated  by  the  width  of  the  slit  through  which  it  runs,  and  the  rapidity  of  the  traverse  ; a piece  of 
cloth  or  ticken  is  stretched  upon  the  casting-table.  The  metal  is  planed  to  thickness,  bent  up,  and 
soldered  into  the  pipes. 

Lead  pipes  are  cast  as  hollow  cylinders  and  drawn  out  upon  triblets ; they  are  also  cast  of  indefinite 


* By  others,  4 grains  of  brass  are  added  to  the  solder ; it  then  fuses  beautifully  and  is  of  good  color.  Zinc  is  sometimes 
added  to  other  gold  solders  to  increase  their  fusibility  ; the  zinc  (or  brass,  when  used)  should  be  added  at  the  last  mo- 
ment, to  lessen  the  volatilization  of  the  zinc. 


METALS  AND  ALLOYS. 


385 


length  without  drawing.  A patent  was  taken  out  for  casting  a sheath  of  tin  within  the  lead,  but  it  has 
been  abandoned. 

Lead  shot  are  cast  by  letting  the  metal  run  through  a narrow  slit,  into  a species  of  colander  at  the 
top  of  a lofty  tower ; the  metal  escapes  in  drops,  which,  for  the  most  part,  assume  the  spherical  form 
before  they  reach  the  tank  of  water  into  which  they' fall  at  the  foot  of  the  tower,  and  this  prevents  their 
being  bruised.  The  more  lofty  the  tower,  the  larger  the  shot  that  can  be  produced ; the  good  and  bad 
shot  are  separated  by  throwing  small  quantities  at  a time  upon  a smooth  board  nearly  horizontal,  which 
is  slightly  wriggled  ; the  true  or  round  shot  run  to  the  bottom,  the  imperfect  ones  stop  by  the  way,  and 
are  thrown  aside  to  be  remelted ; the  shot  are  afterwards  riddled  or  sifted  for  size,  and  churned  in  a 
barrel  with  black-lead. 

Mr.  Joseph  Manton  took  out  a patent  for  amalgamating  the  stirface  of  leaden  shot  with  mercury. 
One  pound  of  mercury  was  added  to  every  cwt.  of  shot;  they  were  churned  together  in  a revolving 
barrel  nearly  full  of  water,  until  the  shot  assumed  a silvery  coat.  These  shot  were  stated  to  foul  the 
barrel  of  the  gun  in  a less  degree  than  others,  and  also  to  be  less  injurious  to  the  game  after  it  had 
been  killed. 

Mercury  is  a brilliant  white  metal,  having  much  of  the  color  of  silver,  whence  the  terms  hydrargyrum 
argentum  vivutn , and  quicksilver.  It  lias  been  known  from  very  remote  ages.  It  is  liquid  at  all  com- 
mon temperatures ; solid  and  malleable  at  — 40°  F.,  and  contracts  considerably  at  the  moment  of 
congelation.  It  boils  and  becomes  vapor  at  about  670°.  Its  specific  gravity  at  60°  is  13'5.  In  the  solid 
state  its  density  exceeds  14.  The  specific  gravity  of  mercurial  vapor  is  6'976.  (Dumas,  Ann.  de  Ch.  et 
Ph.  xxxiii.,  Brande , 928.) 

Mercury  is  used  in  the  fluid  state  for  a variety  of  philosophical  instruments,  and  for  pressure  gages 
for  steam-engines,  &c.  It  is  sometimes,  though  rarely,  employed  for  rendering  alloys  more  fusible  ; it  is 
used  with  tin-foil  for  silvering  looking-glasses,  and  it  has  been  employed  as  a substitute  for  water  in  hard- 
ening steel.  Mercury  forms  amalgams  with  bismuth,  copper,  gold,  lead,  palladium,  silver,  tin,  and  zinc. 

Mercury  is  commonly  used  for  the  extraction  of  gold  and  silver  from  their  ores  by  amalgamation,  and 
also  in  water-gilding.  See  Gold. 

Nickel  is  a white,  brilliant  metal,  which  acts  upon  the  magnetic  needle,  and  is  itself  capable  of  be- 
coming a magnet.  Its  magnetism  is  more  feeble  than  that  of  iron,  and  vanishes  at  a heat  somewhat 
below  redness,  630°,  (Faraday.)  It  is  ductile  and  malleable.  Its  specific  gravity  varies  from  8'27  to 
8p40  when  fused,  and  after  hammering  from  8'69  to  9.  It  is  not  oxidized  by  exposure  to  air  at  common 
temperatures,  but  when  heated  in  the  air  it  acquires  various  tints,  like  steel ; at  a red  heat  it  becomes 
coated  by  a gray  oxide.  ( Brande , 802.) 

Nickel  is  scarcely  used  in  the  simple  state ; Mr.  Brande  mentions,  however,  that  he  has  seen  a Bava- 
rian coin  that  had  been  struck  in  it ; but  it  is  principally  used  together  with  copper  and  zinc,  in  alloys 
that  are  rendered  the  harder  and  whiter  the  more  nickel  they  contain ; they  are  known  under  the 
names  of  albata,  British  plate,  electrum^  German  silver,  pakfong,  teutanag,  &c. : the  proportions  differ 
much,  according  to  price ; thus  the 

Commonest  are  3 to  4 parts  nickel,  20  copper,  and  16  zinc. 

Best  are  .6  to  6 parts  nickel,  20  copper,  and  8 to  10  zinc. 

About  two-thirds  of  this  metal  is  used  for  articles  resembling  plated  goods,  and  some  of  which  are 
also  plated,  (see  silver ;)  the  remainder  is  employed  for  harness,  furniture,  drawing  and  mathematical 
instruments,  spectacles,  the  tongues  for  accordions,  and  numerous  other  small  works. 

The  white  copper  of  the  Chinese,  which  is  the  same  as  the  German  silver  of  the  present  day,  is  com- 
posed, according  to  the  analysis  of  Dr.  Fyfe,  of 

31'6  parts  of  nickel,  40'4  of  copper,  25  4 of  zinc,  and  2'6  of  iron. 

17'48  “ “ 53  39  “ 13-0  “ Frick’s  Imitative  Silver. 

The  white  copper  manufactured  at  Sutil,  in  the  duchy  of  Saxe  Hildburghausen,  is  said  b}r  Keferstein 
to  consist  of  copper  88'000,  nickel  8.753,  sulphur,  with  a little  antimony,  0'750,silex,  clay,  and  iron,  1-75. 
The  iron  is  considered  to  be  accidentally  introduced  into  these  several  alloys,  along  with  the  nickel,  and 
a minute  quantity  is  not  prejudicial. 

Iron  and  steel  have  been  alloyed  with  nickel ; the  former,  (the  same  as  the  meteoric  iron  which 
always  contains  nickel,)  is  little  disposed  to  rust,  whereas  the  alloy  of  steel  with  nickel  is  worse  in 
that  respect  than  steel  not  alloyed. 

Palladium  is  of  a dull-white  color,  malleable  and  ductile.  Its  specific  gravity  is  about  1 1-3,  or  11'86 
when  laminated.  It  fuses  at  a temperature  above  that  required  for  the  fusion  of  gold.  ( Brande , 998.) 

“ Palladium  is  a soft  metal,  but  its  alloys  are  all  harder  than  the  pure  metal.  With  silver  it  forms 
a very  tough  malleable  alloy,  fit  for  the  graduations  of  mathematical  instruments,  and  for  dental 
surgery,  for  which  it  is  much  used  by  the  French  ; with  silver  and  copper,  palladium  makes  a very 
springy  alloy,  used  for  the  points  of  pencil-cases,  inoculating  lancets,  tooth-picks,  or  any  purpose  where 
elasticity  and  the  property  of  not  tarnishing  are  required ; thus  alloyed  it  takes  a high  polish.  Pure 
palladium  is  not  fusible  at  ordinary  temperatures,  but  at  a high  temperature  it  agglutinates  so  as  to  be 
afterwards  malleable  and  ductile.” — ■ W.  Cock. 

This  useful  metal  was  discovered  by  Dr.  Wollaston,  in  1803,  and  it  has  recently  been  found  in  some 
abundance  in  the  gold  ores  of  the  Minas  Geraes  district ; the  process  now  employed  for  its  separation 
was  discovered  by  Mr.  P.  N.  Johnson.  Palladium  is  calculated  thoroughly  to  fulfil  many  of  the  pur- 
poses to  which  platinum  and  gold  are  applied  in  the  useful  arts,  and  from  its  low  specific  gravity,  it 
may  be  obtained  at  about  half  the  price  of  an  equal  hulk  of  platinum,  and  at  one-eiglith  that  of  gold ; 
and  it  equally  resists  the  action  of  mineral  acids  and  sulphuretted  hydrogen. — London  Journal  of  Sci- 
ence for  1840. 

Palladium  was  used  in  the  construction  of  the  balances  for  the  United  States’  Mint. 

Platinum  is  a white  metal,  extremely  difficult  of  fusion,  and  unaltered  bv  the  joint  action  of  heat 
Vol.  II.— 25 


386 


METALS  AND  ALLOYS. 


and  air.  It  varies  in  density  from  21  to  21-5,  according  to  the  degree  of  mechanical  compression  whici 
it  has  sustained ; it  is  extremely  ductile,  but  cannot  be  beaten  into  such  thin  leaves  as  gold  and  silver 
( Brande , 4th  Ed.  p.  822.) 

The  particles  of  the  generality  of  metals,  when  separated  from  the  foreign  matters  with  which 
they  are  combined,  are  joined  into  solid  masses  by  simple  fusion ; but  platinum  being  nearly  infu- 
sible when  pure,  requires  a very  different  treatment,  which  was  introduced  by  Dr.  Wollaston,  and 
is  now  conducted  in  the  following  manner  by  Messrs.  Johnson  and  Cock,  of  London,  the  celebrated 
metallurgists. 

The  platinum  is  first  dissolved  chemically,  and  it  is  then  thrown  down  in  the  state  of  a precipitate ; 
next  it  is  partly  agglutinated  in  the  crucible  into  a spongy  mass,  and  is  then  compressed  whilst  cold  in 
a rectangular  mould  by  means  of  a powerful  fly-press  or  other  means,  which,  in  operating  upon  500 
ounces,  converts  the  platinum  into  a dense  block  about  5 inches  by  4,  and  2 J inches  thick.  This  block 
is  heated  in  a smith’s  forge,  with  two  tuyeres  meeting  at  an  angle,  at  which  spot  the  platinum  is  placed 
amidst  the  charcoal  fire ; when  it  has  reached  the  welding  point,  or  almost  a blue  heat,  it  receives  one 
blow  under  a heavy  drop,  or  a vertical  hammer,  somewhat  like  a pile-driving  engine ; it  then  requires 
to  be  reheated,  and  it  thus  receives  a fresh  blow  about  every  20  minutes,  and  in  a week  or  ten  days  it 
is  sufficiently  welded  or  consolidated  on  all  sides  to  admit  of  being  forged  into  bars,  and  converted  into 
sheets,  rods,  or  wires  by  the  ordinary  means. 

The  motive  for  operating  upon  so  great  a quantity  is  for  making  the  large  pans  for  concentrating 
sulphuric  acid,  in  only  two  or  three  pieces,  which  are  soldered  together  with  line  gold.  In  France, 
2,000  ounces  are  sometimes  welded  into  one  mass,  so  that  the  vessels  may  be  absolutely  entire,  a prac- 
tice which  is  considered  in  this  country  to  be  unnecessarily  costly.  For  small  quantities  the  treatment 
is  the  same,  but  in  place  of  the  drop,  the  ordinary  flatter  and  sledge-hammer  are  used. 

Platinum  is  exceedingly  tough  and  tenacious,  and  “ hangs  to  the  file  worse  than  copper,”  on  which  ac- 
count, when  it  is  used  for  the  graduated  limbs  of  mathematical  instruments,  the  divisions  should  be  cut 
with  a diamond  point,  and  which  is  the  best  instrument  for  fine  graduations  of  all  kinds,  and  for  ruling 
grounds,  or  the  lined  surfaces  for  etching. 

Platinum  is  employed  in  Russia  for  coin.  This  valuable  metal  is  used  in  various  chemical  and  philo- 
sophical apparatus,  in  which  resistance  to  fusion  or  to  the  acids  is  essential. 

The  alloys  of  platinum  are  scarcely  used  in  the  arts ; that  with  a small  quantity  of  copper  is  em- 
ployed in  Paris  for  dental  surgery.  For  alloys  of  platinum  and  steel,  see  Quarterly  Journal  of  the 
Royal  Inst..,  vol  ix.,  p.  328.  The  alloy  of  equal  parts  of  steel  aud  platinum  is  therein  highly  spoken  of 
as  a mirror. 

“Dr.  Yon  Eckart’s  alloy  contains  platinum  2’40,  silver  3'53,  and  copper  1 17 1 . It  is  highly  elastic, 
of  the  same  specific  gravity  as  silver,  and  not  subject  to  tarnish ; it  can  be  drawn  to  the  finest  wire 
from  Jth  of  an  inch  diameter,  without  annealing,  and  does  not  lose  its  elasticity  by  annealing.  It  is 
liighly  sonorous,  and  bears  hammering  red-hot,  rolling  and  polishing.” 

Mr.  Ross  added  to  silver  one-fourth  of  its  weight  of  platinum,  and  he  considers  that  it  took  up  one- 
tenth  its  weight.  The  alloy  became  much  harder  than  silver,  capable  of  resisting  the  tarnishing  influ- 
ences of  sulphur  and  hydrogen,  and  was  fit  for  graduations. 

An  alloy  of  platinum  with  ten  parts  of  arsenic  is  fusible  at  a heat  a little  above  redness,  and  may 
therefore  be  cast  in  moulds.  On  exposing  the  alloy  to  a gradually  increasing  temperature  in  open  ves- 
sels, the  arsenic  is  oxidized  and  expelled,  and  the  platinum  recovers  its  purity  and  infusibility. — Turner's 
Chemistry. 

Tin  also  so  greatly  increases  the  fusibility  of  platinum,  that  it  is  hazardous  to  solder  the  latter  metal 
with  tin  solder,  although  gold  is  so  used. 

Platinum,  as  well  as  gold,  silver,  and  copper,  are  deposited  by  the  electrotype  process  ; and  silver 
plates  thus  platinized  are  employed  in  Smee’s  Galvanic  Battery. 

Rhodium  is  a white  metal,  very  difficult  of  fusion;  its  specific  gravity  is  about  11 : it  is  extremely 
hard.  When  pure,  the  acids  do  not  dissolve  it.  ( Brande , 1001.) 

Rhodium  was  discovered  in  1803,  by  Dr.  Wollaston,  and  has  been  long  employed  for  the  nibs  of 
pens,  which  have  been  also  made  of  ruby,  mounted  on  shafts  of  spring  gold ; these  kinds  have  had  to 
endure  for  the  last  7 or  8 years  the  rivalry  of  “ Hawkins’  everlasting  Pen,”  of  which  latter,  the  author 
from  many  months’  constant  use  can  speak  most  favorably.  “ The  everlasting  pen,”  says  the  inventor, 
“is  made  of  gold,  tipped  with  a natural  alloy,  which  is  as  much  harder  than  rhodium  as  steel  is  harder 
than  lead ; will  endure  longer  than  the  ruby,  yields  ink  as  freely  as  the  quill,  is  as  easily  wiped,  and  if 
left  unwiped  is  not  corroded.”  See  also  Mec.  Mag.,  1840,  p.  554.  Mr.  Hawkins  employs  the  natural 
alloy  of  iridium  and  osmium,  two  scarce  metals,  discovered  by  Tennant  amongst  the  grains  of  platinum ; 
the  alloy  is  not  malleable,  and  is  so  hard  as  to  require  to  be  worked  with  diamond  powder.  The  metals 
rhodium,  iridium,  and  osmium,  are  not  otherwise  employed  in  the  arts  than  for  pens,  although  steel 
has  been  alloyed  with  rhodium.  See  also  the  Quarterly  Journal,  Royal  Inst.,  vol.  ix. 

Silver  is  of  a more  pure  white  than  any  other  metal ; it  has  considerable  brilliancy,  and  takes  a high 
polish.  Its  specific  gravity  varies  between  10’4,  which  is  the  density  of  cast  silver,  and  10’5  to  10'6, 
which  is  the  density  of  rolled  or  stamped  silver.  It  is  so  malleable  and  ductile,  that  it  may  be  ex- 
tended into  leaves  not  exceeding  a ten-thousandth  of  an  inch  in  thickness,  and  drawn  into  wire  much 
finer  than  a human  hair.  Silver  melts  at  a bright-red  heat,  estimated  by  Mr.  Daniell  at  1873°  of  Fah- 
renheit’s scale,  and  when  in  fusion  appears  extremely  brilliant.  ( Brande , 953.) 

Silver  is  but  little  used  in  the  pure  unalloyed  state,  on  account  of  its  extreme  softness,  but  it  is  gen- 
erally alloyed  with  copper  in  about  the  same  proportion  as  in  our  coin,  and  none  of  inferior  value  can 
receive  the  “Hall  mark.”  Diamonds  are  set  in  fine  silver,  and  in  silver  containing  3 to  12  grs.  of  cop- 
per in  the  ounce  ; the  work  is  soldered  with  pure  tin. 

The  sheet, -metal  for  plated  works  is  prepared  by  fitting  together  very  truly,  a short  stout  bar  of  cop- 
per aud  a thinner  plate  of  silver;  when  scraped  perfectly  clean,  they  are  tied  strongly  together  with 


METALS  AND  ALLOYS. 


387 


binding  wire,  and  united  by  partial  fusion  without  the  aid  of  solder.  The  plated  metal  is  then  rolled 
out,  and  the  silver  always  remains  perfectly  united,  and  of  the  same  proportional  thickness  as  at  first 
Additional  silver  may  be  burnished  on  hot,  when  the  surfaces  are  scraped  clean,  as  explained  under 
gold  ; this  is  done  either  to  repair  a defect,  or  to  make  any  part  thicker  for  engraving  upon,  and  the 
uniformity  of  surface  is  restored  with  the  hammer.  In  addition  to  its  use  for  articles  of  luxury,  the 
important  service  of  copper  plated  with  silver  for  the  parabolic  reflectors  of  lighthouses  must  not  be 
overlooked ; these  are  worked  to  the  curve  with  great  perfection  by  the  hammer  alone. 

Plated  spoons,  forks,  harness,  and  many  other  articles,  are  made  of  iron,  copper,  brass,  and  German 
silver,  either  cast  or  stamped  into  shape  ; the  objects  are  then  filed  and  scraped  perfectly  clean  ; and 
fine  silver,  often  little  thicker  than  paper,  is  attached  with  the  aid  of  tin  solder  and  heat ; the  silver  is 
rubbed  close  upon  every  part  with  a burnisher. 

The  electrotype  process  is  also  used,  under  Elkington  & Co.’s  patent,  for  plating  several  of  the  metals 
with  silver,  which  it  does  in  the  most  uniform  and  perfect  manner ; the  silver  added  is  charged  by 
weight  at  about  three  times  the  price  of  the  metal ; the  German  silver,  or  albata,  is  generally  used  for 
the  interior  substance,  as  when  the  silver  is  partially  worn  through,  the  white  alloy  is  not  so  readily 
detected  as  iron  or  copper. 

Silver  alloys. — Mr.  Brande  says,  “ The  alley  with  copper  constitutes  plate  and  coin  ; by  the  addition 
of  a small  proportion  of  copper  to  silver,  the  metal  is  rendered  harder  and  more  sonorous,  while  its 
color  is  scarcely  impaired.  Even  with  equal  weights  of  the  two  metals,  the  compound  is  white ; the 
maximum  of  hardness  is  obtained  when  the  copper  amounts  to  one-fifth  of  the  silver.  The  standard 
silver  of  this  country  consists  of  1 IjA  pure  silver,  and  copper,  or  11T0  silver,  and  0'90  copper.  A 
pound  of  troy,  therefore,  is  composed  of  11  oz.  2 dwts.  pure  silver,  and  18  dwts.  of  copper.  Its  density 
is  10'3  ; its  calculated  density  is  105,  so  that  the  metals  dilate  a little  on  combining.  The  French  silver 
coin  is  constituted  of  9 silver  and  1 copper.”  {Brande.)  The  French  billon  coin  is  1 silver  and  4 
copper.  {Kelly.) 

“For  silver  plate,  the  French  proportions  are  9^-  parts  silver,  ^ copper,  and  for  trinkets,  8 parts  silver, 
2 copper.” 

Silver  solders  are  made  in  the  following  proportions  : 

Hardest  silver  solder,  4 parts  fine  silver,  and  1 part  copper ; this  is  difficult  to  fuse,  but  is  occasion- 
ally employed  for  figures. 

Hard  silver  solder,  3 parts  sterling  silver,  and  1 part  brass  wire,  which  is  added  when  the  silver  is 
melted,  to  avoid  wasting  the  zinc. 

Soft  silver  solder  for  general  use,  2 parts  fine  silver,  and  1 part  brass  wire.  By  some  few,  f part  of 
arsenic  is  added,  to  render  the  solder  more  fusible  and  white,  but  it  becomes  less  malleable ; the  arsenic 
must  be  introduced  at  the  last  moment,  with  care  to  avoid  its  fumes. 

Silver  is  also  soldered  with  tin  solder,  (2  tin,  1 lead,)  and  with  pure  tin. 

Silver  and  mercury  are  used  in  the  plastic  metallic  stopping  for  teeth. 

Tin  has  a silvery-wliite  color,  with  a slight  tint  of  yellow ; it  is  malleable,  though  sparingly  ductile. 
Common  tin-foil,  which  is  obtained  by  beating  out  the  metal,  is  not  more  than  1 -1000th  of  an  inch  in 
thickness,  and  what  is  termed  white  Butch  metal  is  in  much  thinner  leaves.  Its  specific  gravity  fluctu- 
ates from  7-28  to  7 '6,  the  lightest  being  the  purest  metal.  When  bent  it  occasions  a peculiar  crackling 
noise,  arising  from  the  destruction  of  cohesion  amongst  its  particles. 

When  a bar  of  tin  is  rapidly  bent  backwards  and  forwards  several  times  successively,  it  becomes  so 
hot  that  it  cannot  be  held  in  the  hand.  When  rubbed  it  exhales  a peculiar  odor.  It  melts  at  442°, 
and  by  exposure  to  heat  and  air  is  gradually  converted  into  a protoxide.  {Brande.) 

Pure  tin  is  commonly  used  for  dyers’  kettles  ; it  is  also  sometimes  employed  for  the  bearings  of  loco- 
motive carriages  and  other  machinery.  This  metal  is  beaten  into  very  large  sheets,  some  of  which 
measure  200  by  100  inches,  and  are  of  about  the  thickness  of  an  ordinary  card ; the  small-sized  foil  is 
stated  not  to  exceed  one-thousandth  of  an  inch  in  thickness.  The  metal  is  first  laminated  between 
rollers,  and  then  spread  one  sheet  at  a time  upon  a large  iron  surface  or  anvil,  by  the  direct  blows  or 
hammers  with  very  long  handles ; great  skill  is  required  to  avoid  beating  the  sheets  into  holes.  The 
large  sheets  of  tin-foil  are  only  used  for  silvering  looking-glasses  by  amalgamation  with  mercury.  See 
Mr.  Farrow’s  apparatus,  Trans.  Soc.  of  Arts,  vol.  49,  p.  146.  Tin-foil  is  also  used  for  electrical  pur- 
poses. The  amalgam  used  for  electrical  machines,  is  7 tin,  3 zinc,  and  2 mercury. 

Tin  is  drawn  into  wire,  which  is  soft  and  capable  of  being  bent  and  unbent  many  times  without 
breaking  ; it  is  moderately  tenacious,  and  completely  inelastic.  Tin  tube  is  extensively  used  for  gas 
fittings,  and  many  other  purposes ; it  has  been  recently  introduced  in  an  ingenious  manner  for  the 
formation  of  very  cheap  vessels,  for  containing  artists’  and  common  colors,  besides  numerous  other 
solid  substances  and  fluids,  required  to  be  hermetically  sealed,  with  the  power  of  abstracting  small 
quantities. 

Tin  plate  is  an  abbreviation  of  tinned  iron  plate ; the  plates  of  charcoal  iron  are  scoured  bright, 
pickled,  and  immersed  in  a batli  of  melted  tin  covered  with  oil,  or  with  a mixture  of  oil  and  common 
resin ; they  come  out  thoroughly  coated.  Tinned  iron  wire  is  similarly  prepared ; there  are  several 
niceties  in  the  manipulations  of  each  of  these  processes  which  cannot  be  noticed  in  this  place. 

Tin  is  one  of  the  most  cleanly  and  sanatory  of  metals,  and  is  largely  consumed  as  a coating  for  culi- 
nary vessels,  although  the  quantity  taken  up  in  the  tinning  is  exceedingly  small,  and  which  was  noticed 
by  Pliny. 

Tin  imparts  hardness,  whiteness,  and  fusibility  to  many  alloys,  and  is  the  basis  of  different  solders, 
pewters,  Britannia  metal,  and  other  important  alloys,  all  of  which  have  a low  power  of  conducting  heat. 

Pewter  is  principally  tin  ; mostly  lead  is  the  only  addition,  at  other  times  copper,  but  antimony,  zinc, 
<tc.,  are  used  with  the  above,  as  will  be  separately  adverted  to.  The  exact  proportions  are  unknown 
even  to  those  engaged  in  the  manufacture  of  pewter,  as  it  is  found  to  be  the  better  mixed  when  it  con 
tains  a considerable  portion  of  old  metal,  to  which  new  metal  is  added  by  trial. 


388 


METALS  AND  ALLOYS. 


In  order  to  regulate  the  quality  of  pewter  wares,  the  Tenderers’  Company  published  in  1772  “A 
Table  of  the  Assays  of  Metal,  and  of  the  Weights  and  Dimensions  of  the  several  sorts  of  Pewter 
Wares,”  and  they  threatened  with  expulsion  from  their  guild,  any  who  departed  from  the  regulations 
given  in  this  now  scarce  and  disregarded  pamphlet. 

The  assay  is  made  by  casting  a small  button  of  the  metal  to  be  tried  in  a brass  mould,  which  is  sc 
proportioned  that  the  button,  if  pure  tin,  weighs  exactly  182  grains  ; all  the  metals  added  to  the  tin 
being  heavier  than  the  latter  : the  buttons  or  assays  are  the  heavier  the  less  tin  they  contain,  and  at 
page  14  of  the  pamphlet  the  following  scale  is  given : 


Assay  of  pure  tin 182  grains. 

Ditto  of  fine  or  plate  metal  1£  grains  heavier  than  tin,  or 183^  “ 

Ditto  of  trifling  metal  “ “ 1854  “ 

Ditto  of  ley  metal  164  “ “ 198|  “ 


sad  it  may  be  added,  although  an  unauthorized  addition,  that  equal  parts  of  tin  and  lead  are  about 
fifty  grains  heavier  than  tin,  or  232  grains. 

Some  pewters  are  now  made  nearly  as  common  as  the  last  proportion : when  cast  they  are  black, 
shining  and  soft ; when  turned,  dull  and  bluish.  Other  pewters  only  contain  l-5th  or  l-6th  of  lead  ; these 
when  cast  are  white,  without  gloss,  and  hard ; such  are  pronounced  very  good  metal,  and  are  but  little 
darker  than  tin.  The  French  legislature  sanctions  the  employment  of  18  per  cent,  of  lead  with  82  of 
tin,  as  quite  harmless  in  vessels  for  wine  and  vinegar. 

The  finest  pewter,  frequently  called  “tin  and  temper,”  consists  mostly  of  tin,  with  a very  little  cop- 
per, which  makes  it  hard  and  somewhat  sonorous,  but  the  pewter  becomes  brown-colored  when  the 
copper  is  in  excess.  The  copper  is  melted,  and  twice  its  weight  of  tin  is  added  to  it,  and  from  about 
d to  7 lbs.  of  this  alloy,  or  the  “ temper,”  are  added  to  every  block  of  tin  weighing  from  360  to  390 
pounds. 

Antimony  is  said  to  harden  tin  and  to  preserve  a more  silvery  color,  but  is  little  used  in  pewter. 
Zinc  is  employed  to  cleanse  the  metal  rather  than  as  an  ingredient ; some  stir  the  fluid  pewter  with  a 
thin  strip,  half  zinc  and  half  tin  ; others  allow  a small  lump  of  zinc  to  float  on  the  surface  of  the  fluid 
metal  whilst  they  are  casting,  to  lessen  the  oxidation. 

Britannia  metal,  or  white  metal,  is  said  to  consist  of  3^-  cwt.  of  block  tin,  28  lbs.  antimony,  8 lbs.  cop- 
per, and  8 lbs.  brass ; it  is  cast  into  ingots  and  rolled  into  very  thin  sheets.  This  manufacture  was  in 
troduced  in  about  the  year  1770,  by  Jessop  and  Hancock. 

Tin  solders  are  very  much  used  in  the  arts,  and  according  to  Dr.  Turner, 

1 tin  3 lead,  the  coarse  plumber’s  solder,  melts  at  about  500  F. 

2 “ 1 “ the  ordinary  or  fine  tin  solder  “ “ “ 360  F. 

Zinc. — A bluish-white  metal,  with  considerable  lustre,  rather  hard,  of  a specific  gravity  of  about  6 8 
in  its  usual  state,  but,  when  drawn  into  wire,  or  rolled  into  plates,  its  density  is  augmented  to  7 or  7'2. 
In  its  ordinary  state  at  common  temperatures,  it  is  tough,  and  with  difficulty  broken  by  blows  of  the 
hammer.  It  becomes  very  brittle  when  its  temperature  approaches  that  of  fusion,  which  is  about  773°  ; 
but  at  a temperature  a little  above  212°,  and  between  that  and  300°,  it  becomes  ductile  and  malleable, 
and  may  be  rolled  into  thin  leaves,  and  drawn  into  moderately  fine  wire,  which,  however,  possesses  but 
little  tenacity.  When  a mass  of  zinc,  which  has  been  fused,  is  slowly  cooled,  its  fracture  exhibits  a 
lamellar  and  prismatic  crystalline  texture. — Brando,  770. 

Zinc,  which  is  commercially  known  as  spelter,  although  it  is  always  brittle  when  cast,  has  of  late 
years  taken  its  place  amongst  the  malleable  metals ; the  early  stages  of  its  manufacture  into  sheet,  foil, 
and  wire,  are  stated  to  be  conducted  at  a temperature  somewhat  above  that  of  boilrng  water ; and  it 
may  be  afterwards  bent  and  hammered  cold,  but  it  returns  to  its  original  crystalline  texture  when  re-' 
melted.  It  has  been  applied  to  many  of  the  purposes  of  iron,  tinned-iron,  and  copper ; it  is  less  subject 
to  oxidation  from  the  effects  of  the  atmosphere  than  the  iron,  and  much  cheaper,  although  less  tenacious, 
ductile,  or  durable  than  the  copper.  The  sheet  metals  when  bent  lengthways  of  the  sheet,  (or  like  a 
roll  of  cloth,)  are  less  disposed  to  crack  than  if  bent  sideways.  In  this  respect  zinc  and  sheet-iron  are  the 
worst : the  risk  is  lessened  when  they  are  warmed. 

Zinc  is  applied  as  a coating  to  preserve  iron  from  rust. 

Zinc  mixed  with  one-twentieth  its  weight  of  speculum  metal,  may  be  melted  in  an  iron  ladle,  and 
made  to  serve  for  some  of  the  purposes  of  brass,  such  as  common  chucks.  The  alloy  is  sufficient  to 
modify  the  crystalline  character,  but  reserves  the  toughness  of  the  zinc;  it  will  not,  however,  bear  ham- 
mering, either  hot  or  cold.  Four  atoms  of  zinc  and  one  of  tin,  or  133f2  and  57'9,  make  a hard,  malleable, 
aud  less  crystalline  alloy. 

Biddery  ware,  manufactured  at  Bidderv,  a large  city,  60  miles  N.  W.  of  Hyderabad  in  the  East  In- 
dies. and  also  at  Benares,  is  said  by  Dr.  Heyne  to  consist  of  copper,  16  oz. ; lead,  4 oz. ; and  tin,  2 oz., 
melted  together : and  to  every  3 oz.  of  this  alloy,  16  oz.  of  spelter  or  zinc  are  added.  The  metal  is  used 
as  an  inferior  substitute  for  silver,  and  resembles  some  sorts  of  pewter. 

The  foregoing  alloys  are  mostly  derived  from  actual  practice,  and  although  it  has  been  abundantly 
shown  that  alloys  are  most  perfect,  when  mixed  according  to  atomic  proportions,  or  by  multiples 
of  their  chemical  equivalents,  yet  this  excellent  method  is  little  adopted,  owing  to  various  interfer- 
ences. 

For  example,  it  is  in  most  cases  necessary,  from  an  economic  view,  to  mix  some  of  the  old  alloys,  (the 
proportions  of  which  are  uncertain,)  along  with  the  new  metals.  In  most  cases  also  unless  the  fusion 
and  refusion  of  the  alloys  are  conducted  with  considerably  more  care  than  ordinary  practice  ever  attains, 
or  really  demands,  the  loss  by  oxidation  completely  invalidates  any  nice  attempts  at  proportion ; and 


METALS  AND  ALLOYS. 


38P 


wliicli  proportions  can  be  alone  exactly-  arrived  at,  when  the  combined  metals  are  nearly  or  quite 
pure. 

Hardness,  fracture,  and  color  of  alloys. — The-  object  of  this  division  of  our  article  is  to  explain,  in  a 
general  way,  some  of  the  peculiarities  and  differences  amongst  alloys,  in  the  manner  of  a supple- 
ment to  the  list ; prior  to  entering  on  the  means  of  melting  tire  metals,  without  which  process 
alloys  cannot  be  made  : yet  notwithstanding  that  the  list  contains  the  greater  number  of  the  alloys  in 
ordinary  use,  and  many  others,  it  is  merely  a small  fraction  of  those  which  might  be  made,  for,  says  l)r. 
Turner,  “It  is  probable  that  each  metal  is  capable  of  uniting  in  one  or  more  proportions  with  every  other 
metal,  and  on  this  supposition  the  number  of  alloys  would  be  exceedingly  numerous.”* * * § 

It  is  also  stated  by  the  same  distinguished  authority,  that  “Metals  appear  to  unite  with  one  another 
in  every  proportion,  precisely  in  the  same  manner  as  sulphuric  acid  and  water.  Thus  there  is  no  limit 
to  tire  number  of  alloys  of  gold  and  copper.”  The  same  might  be  said  of  many  other  metals,  and  when 
the  alloys  compounded  of  three,  four,  or  more  metals,  are  taken  into  account.,  the  conceivable  number  oi 
alloys  becomes  almost  unlimited.  “It  is  certain,  however,  that  metals,  have  a tendency  to  combine  in 
definite  proportion  ; for  several  atomic  compounds  of  this  kind  occur  native.”  “ It  is  indeed  possible 
that  the  variety  of  proportions  in  alloys  is  rather  apparent  than  real,  arising  from  the  mixture  of  a few 
definite  compounds  with  each  other,  or  with  uncombined  metal ; an  opinion  not  only  suggested  by  the 
mode  in  which  alloys  are  prepared,  but  in  some  measure  supported  by  observation.” •)■ 

It  appears  to  be  scarcely  possible  to  give  any  sufficiently  general  rules  by  which  the  properties  of 
alloys  may  be  safely  inferred  from  those  of  their  constituents  ; for  although,  in  many  cases,  the  working 
qualities  and  appearance  of  an  alloy,  may  be  nearly  a mean  proportional  between  the  nature  and  quan- 
tities of  the  metals  composing  it ; yet  in  other  and  frequent  instances  the  deviations  are  excessive,  as 
will  be  seen  by  several  of  the  examples  referred  to. 

Thus,  when  lead,  a soft  and  malleable  metal,  is  combined  with  antimony,  which  is  hard,  brittle,  and 
crystalline,  in  the  proportions  of  from  twelve  to  fifty  parts  of  lead  to  one  of  antimony,  a flexible  alloy 
is  obtained,  resembling  lead,  but  somewhat  harder,  and  which  is  rolled  into  sheets  for  sheathing  ships. 
Six  parts  of  lead  and  one  of  antimony  are  used  for  the  large  soft  printers’  types,  which  will  bend 
slightly,  but  are  considerably  harder  than  the  foregoing;  and  three  parts  of  lead  and  one  of  antimony 
are  employed  for  the  smallest  types,  that  are  very  hard  and  brittle,  and  will  not  bend  at  all : antimony 
being  the  more  expensive  metal,  is  used  in  the  smallest  quantity  that  will  suffice.];  The  difference  in 
specific  gravity  between  lead  and  antimony  constantly  interferes,  and  unless  the  type  metal  is  fre- 
quently stirred,  the  lead,  from  being  the  heavier  metal,  sinks  to  the  bottom,  and  the  antimony  is  dispro- 
portionally  used  from  the  surface-! 

In  the  above  examples,  the-  differences  arising  from  the  proportions  appear  intelligible  enough,  as 
when  the  soft  lead  prevails,  the  mixture  is  much  like  the  lead ; and  as  the  hard,  brittle  antimony  is 
increased,  the  alloy  becomes  hardened,  and  more  brittle : with  the  proportion  of  four  to  one,  the  frac- 
ture is  neither  reluctant  like  that  of  lead,  nor  foliated  like  antimony,  but  assumes  very  nearly  the  grain 
and  color  of  some  kinds  of  steel  and  cast-iron.  In  like  manner  when  tin  and  lead  are  alloyed,  the  for- 
mer metal  imparts  to  the  mixture  some  of  its  hardness,  whiteness,  and  fusibility,  in  proportion  to  its 
quantity;  as  seen  in  the  various  qualities  of  pewter,  in  which  however  copper,  and  sometimes  zinc  or 
antimony,  are  found. 

The  same  agreement  is  not  always  met  with ; as  nine  parts  of  copper,  wThich  is  red,  and  one  part  of 
tin,  which  is  white,  each  very  malleable  and  ductile  metals,  make  the  tough,  rigid  metal  used  in  brass 
ordnance,  from  which  it  obtains  its  modern  name  of  gun-metal,  but  which  neither  admits  of  rolling  nor 
drawing  into  wire ; the  same  alloy  is  described  by  Pliny  as  the  soft  bronze  of  his  day.  The  continual 
addition  of  the  tin,  the  softer  metal,  produces  a gradual  increase  of  hardness  in  the  mixture ; with  about 
one-sixth  of  tin  the  alloy  assumes  its  maximum  hardness  consistent  with  its  application  to  mechanical 
uses ; with  one-fourth  to  one-third  tin  it  becomes  highly  elastic  and  sonorous,  and  its  brittleness  rather 
than  its  hardness  is  greatly  increased. 

When  the  copper  becomes  two,  and  the  tin  one  part,  the  alloy  is  so  hard  as  not  to  admit  of  being  cut 
with  steel  tools,  but  crumbles  under  their  action ; when  struck  with  a hammer,  or  even  suddenly  warmed, 
it  flies  into  pieces  like  glass,  and  clearly  shows  a structure  highly  crystalline,  instead  of  malleable.  The 
alloy  has  no  trace  of  the  red  color  of  the  copper,  but  it  is  quite  white,  susceptible  of  an  exquisite  polish, 
and  being  little  disposed  to  tarnish  it  is  most  perfectly  adapted  to  the  reflecting  speculums  of  telescopes 
and  other  instruments,  for  which  purpose  it  is  alone  used. 

Copper,  when  combined  in  the  same  'proportions  with  a different  metal,  also  light-colored  and  fusible, 
namely  two  parts  of  copper  with  one  of  zinc,  (which  latter  metal  is  of  a bluisli-wdiiie,  and  crystalline, 
whereas  tin  is  very  ductile,)  makes  an  alloy  of  entirely  opposite  character  to  the  speculum  metal ; 
namely,  the  soft  yellow  brass,  which  becomes  by  hammering  very  elastic  and  ductile,  and  is  very  easily 
cut  and  filed. 

Again,  the  same  proportions,  namely,  two  parts  of  copper  and  one  of  lead,  make  a common  inferior 


* Dr.  Turner’s  Chemistry,  Seventh  Edition,  1841,  p.  558.  + Ibid.,  p.  559. 

t hi  this  alloy  the  antimony  fulfils  another  service  besides  that  of  imparting  hardness:  antimony  somewhat  expands  on 
cooling,  whereas  lead  contracts  very  much,  and  the  antimony  therefore,  within  certain  limits,  compensates  for  this  contrac 
tion,  and  causes  the  alloy  to  retain  the  full  size  of  the  moulds. 

Sometimes  from  motives  of  economy  the  neighboring  parts  of  machinery  are  not  wrought  accurately  to  correspond  one 
with  the  other,  but  lead  is  poured  in  to  fill  up  the  intermediate  space,  and  to  make  contact.  As  around  the  brass  nuts  in 
the  heads  of  some  screw-presses,  in  the  guides  or  followers  for  the  same,  and  some  other  parts  of  either  temporary  or  per- 
manent machinery.  Antimony  is  quite  essential  in  all  these  cases  to  prevent  the  contraction  the  lead  alone  would  sustain, 
and  which  would  defeat  the  intended  object,  as  the  metal  would  otherwise  become  smaller  than  the  space  to  be  tilled. 

§ A little  tin  is  commonly  introduced  into  types,  and  likewise  copper  in  minute  quantity;  iron  and  bismuth  are  also 
spoken  of;  the  last  is  said  to  be  employed  on  account  of  its  well-known  property  of  expanding  in  cooling,  so  as  to  cause  the 
types  to  swell  in  the  mould,  and  copy  the  face  of  the  letter  more  perfectly ; but  although  i find  bismuth  to  have  been  thus 
used,  it  appears  to  be  neither  common  nor  essential  in  printing  types. 


390 


METALS  AND  ALLOYS. 


metal,  called  pot-metal,  or  cock -metal,  from  its  employment  in  those  respective  articles.  This  alloy  is 
much  softer  than  brass,  and  hardly  possesses  malleability ; when,  for  example,  the  beer-tap  is  driven 
into  the  cask,  immediately  after  it  has  been  scalded,  the  blow  occasionally  breaks  it  in  pieces,  from  its 
reduced  cohesion. 

Another  proof  of  the  inferior  attachment  of  the  copper  and  lead,  exists  in  the  fact  that  if  the  moulds 
are  opened  before  the  castings  are  almost  cold  enough  to  be  handled,  the  lead  will  ooze  out,  and  appear 
on  the  surface  in  globules.  This  also  occurs  to  a less  extent  in  gun-metal,  which  should  not,  on  that 
account,  be  too  rapidly  exposed  to  the  air ; or  the  tin  strikes  to  the  surface,  as  it  is  called,  and  makes  it 
particularly  hard  at  those  parts,  from  the  proportional  increase  of  the  tin.  In  casting  large  masses  o( 
gun-metal,  it  frequently  happens  that  little  hard  lumps,  consisting  of  nearly  half  tin,  work  up  to  the 
surface  of  the  runners  or  pouring  places,  during  the  time  the  metal  is  cooling. 

In  brass,  this  separation  scarcely  happens,  and  these  moulds  may  be  opened  whilst  the  castings  are 
rod.-hot,  without  such  occurrence  ; from  which  it  appears  that  the  copper  and  zinc  are  in  more  perfect 
chemical  union,  than  the  alloys  of  copper  with  tin,  and  with  lead. 

Malleability  and  ductility  of  alloys. — The  malleability  and  ductility  of  alloys  are  in  a great  measure 
referable  to  the  degrees  in  which  the  metals  of  which  they  are  respectively  composed  possess  these 
characters. 

Lead  and  tin  are  malleable,  flexible,  ductile,  and  inelastic,  whilst  cold,  but  when  their  temperatures 
much  exceed  about  half  way  towards  their  melting  heats,  they  are  exceedingly  brittle  and  tender, 
owing  to  their  reduced  cohesion. 

The  alloys  of  lead  and  tin  partake  of  the  general  nature  of  these  two  metals ; they  are  flexible  when 
cold,  even  with  certain  additions  of  the  brittle  metals  antimony  and  bismuth,  or  of  the  fluid  metal 
mercury  ; but  they  crumble  with  a small  elevation  of  temperature,  as  these  alloys  melt  at  a lower 
degree  than  either  of  their  components,  to  which  circumstance  we  are  indebted  for  the  tin  solders. 

Zinc,  when  cast  in  thin  cakes,  is  somewhat  brittle  when  cold,  but  its  toughness  is  so  far  increased 
when  it  is  raised  to  about  300°  Fahr.  that  its  manufacture  into  sheets  by  means  of  rollers  is  then  admissi- 
ble ; it  becomes  the  malleable  zinc,  and  retains  the  malleable  and  ductile  character,  in  a moderate 
degree,  even  when  cold,  but  in  bending  rather  thick  plates  it  is  advisable  to  warm  them  to  avoid  frac- 
ture ; when  zinc  is  remelted  it  resumes  its  original  crystalline  condition* 

Zinc  and  lead  will  not  combine  without  the  assistance  of  arsenic,  unless  the  lead  is  in  very  small 
quantity ; the  arsenic  makes  this  and  other  alloys  very  brittle,  and  it  is  besides  dangerous  to  use.  Zinc 
and  tin  make,  as  may  be  supposed,  somewhat  hard  and  brittle  alloys,  but  none  of  the  zinc  alloys,  except 
that  with  copper  to  constitute  brass,  are  much  used. 

Gold,  silver,  and  copper,  which  are  greatly  superior  in  strength  to  the  fusible  metals  above  named, 
may  be  forged  either  when  red-hot  or  cold,  as  soon  as  they  have  been  purified  from  their  earthy  mat- 
ters, and  fused  into  ingots;  and  the  alloys  of  gold,  silver,  and  copper  are  also  malleable,  either  red-hot 
nr  cold.f 

Fine,  or  pure  gold  and  silver,  are  but  little  used  alone ; the  alloy  is  in  many  cases  introduced  less 
with  the  view  of  depreciating  their  value  than  of  adding  to  their  hardness,  tenacity,  and  ductility ; the 
processes  which  tire  most  severely  test  these  qualities,  namely,  drawing  the  finest  wires  and  beating 
gold  and  silver  leaf,  are  not  performed  with  the  pure  metals,  but  gold  is  alloyed  with  copper  for  the 
red  tint,  with  silver  for  the  green,  and  with  both  for  intermediate  shades.  Silver  is  alloyed  with  copper 
only,  and  when  the  quantity  is  small  its  color  suffers  but  slightly  from  the  addition,  although  all  its 
working  qualities  are  greatly  improved,  pure  silver  being  little  used. 

The  alloys  of  similar  metals  having  been  considered,  it  only  remains  to  observe  that  when  dissimilar 
metals  are  combined,  as  those  of  the  two  opposite  groups — namely,  the  fusible  lead,  tin,  or  zinc,  with 
the  less  fusible  copper,  gold,  and  silver — the  malleability  of  the  alloys  when  cold  is  less  than  that  of  the 
superior  metal;  and  when  heated  barely  to  redness,  they  fly  in  pieces  under  the  hammer;  and  there- 
fore, brass,  gun-metal,  Ac.,  when  red-hot,  must  be  treated  with  precaution  and  tenderness.  Muntz’s 
patent  metal,  which  is  a species  of  brass  and  is  rolled  red-hot,  appears  rather  a contradiction  to  this ; 
but  in  all  probability  this  alloy,  like  the  ingots  of  cast-steel,  requires  at  first  a very  nice  attention  to  the 
force  applied.  It  will  be  also  remembered  the  action  of  rollers  is  more  regular  than  that  of  the  ham- 
mer ; and  soon  gives  rise  to  the  fibrous  character,  which,  so  far  as  it  exists  in  metals,  is  the  very  ele- 
ment of  strength  when  it  is  uniformly  distributed  throughout  their  substance.  This  will  be  seen  by  the 
inspection  of  the  relative  degrees  of  cohesion  possessed  by  the  same  metal  when  in  the  conditions  of 
the  casting,  sheet,  or  wire,  and  to  which  quality  or  the  tenacity  of  alloys  we  shall  now  devote  a few 
lines. 

Strength  or  cohesion  of  alloys. — The  strength  or  cohesion  of  the  alloys,  is  in  general  greatly  superior 
to  that  of  any  of  the  metals  of  which  they  are  composed. 

All  nice  attempts  at  proportion,  are,  however,  entirely  futile,  unless  the  metals  are  perfectly  pure ; 
for  example,  it  is  a matter  of  common  observation  that  for  speculums,  a variable  quantity  of  from  seven 
and  a half  to  eight  and  a half  ounces  of  tin  is  required  for  the  exact  saturation  ot  every  pound  of  cop 
per,  and  upon  which  saturation  the  efficiency  of  the  compound  depends ; bells  of  exactly  similar  quality 
sometimes  thus  require  the  dose  of  tin  to  vary  from  three  and  a half  to  five  ounces  to  the  pound  of 
copper,  according  to  the  qualities  of  the  metals. 

Fusibility  of  alloys. — In  concluding  this  slight  view  of  some  of  the  general  characters  of  alloys,  it  re- 
mains to  consider  the  influence  of  heat,  both  as  an  agent  in  their  formation,  and  as  regards  the  degree 
in  which  it  is  required  for  their  after  fusion ; the  lowest  available  temperature  being  the  most  desirable 
hi  every  such  case. 

“ Metals  do  not  combine  with  each  other,”  says  Dr.  Turner,  “in  their  solid  state,  owing  to  the  influence 


* It  is  considered  that  most  of  the  sheet  zinc  contains  a very  little  lead. 
+ Gold  alloyed  with  copper  alone  is  not  very  malleable  when  hot. 


METALS  AND  ALLOTS. 


39 


ct  chemical  affinity  being  counteracted  by  the  force  of  cohesion.  It  is  necessary  to  liquefy  at  least  ona 
of  them,  in  which  case  they  always  unite,  provided  their  mutual  attraction  is  energetic.  Thus,  brass  is 
formed  when  pieces  of  copper  are  put  into  melted  zinc ; and  gold  unites  with  mercury  at  common  tem- 
peratures by  mere  contact.” 

The  agency  of  mercury  in  bringing  about  triple  combinations  of  the  metals,  both  witli  and  without 
heat,  is  also  very  curious  and  extensive.  Thus,  in  water-gilding , the  silver,  copper,  or  gilding  metal, 
when  chemically  clean,  are  rubbed  over  with  an  amalgam  of  gold  containing  about  eight  parts  of 
mercury ; this  immediately  attaches  itself,  and  it  is  only  necessary  to  evaporate  the  mercury,  which 
requires  a very  moderate  heat,  and  the  gold  is  left  behind.  Water-silvering  is  similarly  accom- 
plished. 

Cast-iron,  wrought-iron,  and  steel,  as  well  as  copper  and  many  other  metals,  may  be  tinned  in  a 
similar  manner.  An  amalgam  of  tin  and  mercury  is  made  so  as  to  be  soft  and  just  friable  ; the  metal 
to  be  tinned  is  thoroughly  cleaned  either  by  filing  or  turning,  or  if  only  tarnished  by  exposure,  it  is 
cleaned  with  a piece  of  emery-paper  or  otherwise,  without  oil,  and  then  rubbed  with  a thick  cloth 
moistened  with  a few  drops  of  muriatic  acid.  A little  of  the  amalgam  then  rubbed  on  with  the  same 
rag,  thoroughly  coats  the  cleaned  parts  of  the  metal  by  a process  which  is  described  as  cold-tinning  ; 
other  pieces  of  metal  may  be  attached  to  the  tinned  parts  by  the  ordinary  process  of  tin-soldering. 

In  making  the  tinned-iron  plates,  the  scoured  and  cleaned  iron  plates  are  immersed  in  a bath  of  pure 
melted  tin ; covered  with  pure  tallow,  the  tin  then  unites  with  every  part  of  the  surfaces ; and  in  the 
ordinary  practice  of  tinning  culinary  vessels  of  copper,  pure  tin  is  also  used.  The  two  metals,  however 
must  then  be  raised  to  the  melting  heat  of  tin ; but  the  presence  of  a little  mercury  enables  the  process 
to  be  executed  at  the  atmospheric  temperature,  as  above  explained. 

In  Mr.  Mallett’s  recently  patented  “ processes  for  the  protection  of  iron  from  oxidation  and  corrosion, 
and  for  the  prevention  of  the  fouling  of  ships,”  one  proceeding  consists  in  covering  the  iron  with  zinc. 

The  ribs  or  plates  for  iron  ships  are  immersed  in  a “ cleansing  bath”  of  equal  parts  of  sulphuric  or 
muriatic  acid  and  water,  used  warm  ; the  works  are  then  hammered,  and  scrubbed  with  emery  or  sand, 
to  detach  the  scales  and  to  thoroughly  clean  them ; they  are  then  immersed  in  a “ preparing  bath”  of 
equal  parts  of  saturated  solutions  of  muriate  of  zinc  and  sal-ammoniac,  from  which  the  works  are  trans- 
ferred to  a fluid  “metallic  bath,”  consisting  of  202  parts  of  mercury  and  1292  parts  of  zinc,  both  by 
weight  ;*  to  every  ton  weight  of  which  alloy  is  added  about  one  pound  of  either  potassium  or  sodium, 
(the  metallic  bases  of  potass  and  soda,)  the  latter  being  preferred.  As  soon  as  the  cleaned  iron  works 
have  attained  the  melting  heat  of  the  triple  alloy,  they  are  removed,  having  become  thoroughly  coated 
with  zinc. 

The  affinity  of  this  alloy  for  iron  is,  however,  ^o  intense,  and  the  peculiar  circumstances  of  surface  as 
induced  upon  the  iron  presented  to  it  by  the  preparing  bath  are  such,  that  care  is  requisite  lest  by  too 
long  an  immersion  the  plates  are  not  partially  or  wholly  dissolved.  Indeed,  where  the  articles  to  be 
covered  are  small,  or  their  parts  minute,  such  as  wire,  nails,  or  small  chain,  it  is  necessary  before  im- 
mersing them  to  permit  the  triple  alloy  to  dissolve  or  combine  with  some  wrought-iron,  in  order  that 
its  affinity  for  iron  may  be  partially  satisfied,  and  thus  diminished.  At  the  proper  fusing  temperature 
of  this  alloy,  which  is  about  680°  Fahr.,  it  will  dissolve  a plate  of  wrought-iron  of  an  eighth  of  an  inch 
thick  in  a few  seconds. 

The  palladiumizing  process . — The  articles  to  be  protected  are  to  be  first  cleansed  in  the  same  way 
as  in  the  case  of  zincing ; namely,  by  means  of  the  double  salts  of  zinc  and  ammonia,  or  of  manganese 
and  ammonia ; and  then  to  be  thinly  coated  over  with  palladium,  applied  in  a state  of  amalgam  with 
mercury. 

In  the  opinion  of  eminent  chemists  and  metallurgists,  all  the  metals,  even  the  most  refractory,  which 
nearly  or  quite  refuse  to  melt  in  the  crucible  when  alone,  will  gradually  run  down  when  surrounded  by 
some  of  the  more  fusible  metals  in  the  fluid  state  ; in  a manner  similar  to  the  solution  of  the  metals  in 
mercury,  as  in  the  amalgams,  or  the  solutions  of  solid  salts  in  water.  The  surfaces  of  the  superior  metals 
are,  as  it  were,  dissolved,  washed  down,  or  reduced  to  the  state  of  alloys,  layer  by  layer,  until  the  entire 
mass  is  liquefied. 

Thus  nickel,  although  it  barely  fuses  alone,  enters  into  the  composition  of  German  silver  by  aid  of  the 
copper,  and  whilst  it  gives  whiteness  and  hardness,  it  also  renders  the  mixture  less  fusible.  Platinum 
combines  very  readily  with  zinc,  arsenic,  and  also  with  tin  and  other  metals ; so  much  so,  that  it  is 
dangerous  to  melt  either  of  those  metals  in  a platinum  spoon,  or  to  solder  platinum  with  common  tin 
solder,  which  fuses  at  a very  low  temperature;  although  platinum  is  constantly  soldered  with  fine  gold, 
the  melting  point  of  which  is  very  high  in  the  scale.  Again,  the  circumstances  that  some  of  the  fusible 
bismuth  alloys  melt  below  the  temperature  of  boiling  water,  or  at  less  than  half  the  melting  heat  of  tin, 
their  most  fusible  ingredient,  show  that  the  points  of  fusion  of  alloys,  are  equally  as  difficult  of  explana- 
tion or  generalization  as  many  other  of  the  anomalous  circumstances  concerning  them. 

This  much,  however,  may  be  safely  advanced,  that  the  alloys,  without  exception,  are  more  easily 
fused  than  the  superior  metal  of  which  they  are  composed  ; and  extending  the  same  view  to  the  relative 
quantities  of  the  components,  it  may  be  observed  that  the  hard  solders  for  the  various  metals  and 
alloys  are  in  general  made  of  the  self-same  material  which  they  are  intended  to  join,  but  with  small 
additions  of  the  more  fusible  metals.  The  solder  should  be,  as  nearly  as  practicable,  equal  to  the  metal 
on  which  it  is  employed,  in  hardness,  color,  and  every  property  excejtt  fusibility  ; in  which  it  must  excel 
just  to  an  extent  that,  when  ordinary  care  is  used,  will  avoid  the  risk  of  melting,  at  the  same  time,  both 
the  object  to  be  soldered  and  likewise  the  softer  alloy  or  solder  by  which  it  is  intended  to  unite  its 
parts. 

It  would  appear  as  if  every  example  of  soldering  in  which  a more  fusible  alloy  is  interposed,  were 
also  one  of  superficial  alloying.  Thus,  when  two  pieces  of  iron  are  united  by  copper,  used  as  a solder 


Being  in  the  proportion  of  one  atom  of  mercury  to  forty  atoms  of  zinc. 


392 


METALLURGY. 


it  seems  to  be  a natural  conclusion  that  each  surface  of  the  iron  becomes  alloyed  with  the  copper ; and 
that  the  two  alloyed  surfaces  are  held  together  from  their  particles  having  been  fused  in  contact,  and 
run  into  one  film.  It  is  much  the  same  when  brass  or  spelter  solder  is  used,  except  that  triple  alloys 
are  then  formed  at  the  surfaces  of  the  iron,  and  so  with  most  other  instances  of  soldering. 

And  in  cases  where  metallic  surfaces  are  coated  by  other  metals,  the  latter  being  at  the  time  in  a 
state  of  fusion,  as  in  tinned-iron  plates  and  silvered  copper ; may  it  not  also  be  conceived,  that  between 
the  two  exterior  surfaces  which  are  doubtless  the  simple  metals,  a thin  film  of  an  alloy  compounded  of 
the  two  does  in  reality  exist  ? And  in  those  cases  in  which  the  coating  is  laid  on  by  the  aid  of  mercury, 
and  without  heat,  the  circumstances  are  very  similar,  as  the  fluidity  of  mercury  is  identical  with  the 
ordinary  state  of  fusion  of  other  metals,  although  the  latter  require  higher  temperatures  than  that  of  our 
atmosphere. 

When  portions  of  the  same  metal  are  united  by  partial  fusion,  and  without  solder,  as  in  the  process 
described  as  burning  together,  and  more  recently  known  as  the  “ autogenous ” mode  of  soldering,  no  alloy 
is  formed,  as  the  metals  simply  fuse  together  at  their  surfaces. 

Neither  can  it  be  supposed  that  any  formation  of  alloy  can  occur  where  the  one  metal  is  attached  to 
the  other  by  the  act  of  burnishing  on  with  heat,  as  in  making  gilt  wire,  but  without  a temperature  suf- 
ficient to  fuse  either  of  the  metals.  The  union  in  this  case  is  probably  mechanical,  and  caused  by  the 
respective  particles  or  crystals  of  the  one  metal  being  forced  into  the  pores  of  the  other,  and  becoming 
attached  by  a species  of  entanglement,  similar  to  that  which  may  be  conceived  to  exist  throughout  solid 
bodies.  This  process,  almost  more  than  any  other  in  common  use,  requires  that  the  metals  should  be 
perfectly  or  chemically  clean ; for  which  purpose  they  are  scraped  quite  bright  before  they  are  burn- 
ished together,  so  that  the  junction  may  be  next  approaching  to  that  of  solids  generally. 

And,  lastly,  when  metals  are  deposited  upon  other  metals  by  chemical  or  electrical  means,  the  addi- 
tion frequently  appears  to  be  a detached  sheath,  and  which  is  easily  removed ; indeed,  unless  the  metal 
to  be  coated  is  chemically  clean,  and  that  various  attendant  circumstances  are  favorable,  the  sound  and 
absolute  union  of  the  two  does  not  always  happen,  even  when  carefully  aimed  at. 

METALLURGY.  A word  derived  from  the  Greek,  signifying  the  art  of  working  metals,  or  the  art 
by  which  metals  are  produced  from  their  ores. 

Metals  constitute  a well-known  class  of  substances,  distinguished  by  characteristics  which  every  one 
recognizes.  They  are  considered  as  elementary  matter  by  chemists,  because  chemistry  has  failed,  up 
to  the  present  time,  to  resolve  any  one  of  them  into  more  simple  forms  of  matter ; they  may,  therefore, 
be  regarded  as  an  aggregation  of  elementary  atoms,  held  together  by  the  force  of  cohesion.  Metals  are 
popularly  recognized  as  heavy  matter,  of  great  tenacity ; of  a peculiar  metallic  lustre,  which  it  is  diffi- 
cult to  describe,  but  which  is  easily  recognized.  With  one  exception,  namely,  quicksilver,  all  the  metals 
are  solid  at  ordinary  temperatures ; they  are  all  capable  of  liquefaction,  and  even  volatilization,  at 
higher  temperatures,  the  degree  of  heat  being  a different  one  in  every  instance.  Metals,  as  a class,  are 
characterized  by  a higher  specific  gravity  than  almost  all  other  matter ; they  are  distinguished  by 
opacity,  from  which  rule  only  gold  and  silenium  are  excepted.  The  capacity  of  conducting  heat  and 
electricity  is  possessed  by  metals  to  a high  degree  of  perfection. 

Malleability  is  the  property  of  metals  to  change  their  form  permanently,  under  a certain  pressure. 
The  most  important  considerations  for  our  present  purposes  are,  the  chemical  qualities,  the  fusibility  of 
metals,  their  affinity  for  other  matter,  and  their  affinity  among  themselves. 

Fusibility. — The  degree  of  heat  at  which  metals  assume  the  solid  or  the  fluid  state  is  their  fusibility. 


Mercury  melts  at 39° 

“ boils  “ 600° 

Tin  melts  “ 420° 

Lead  “ “ 600° 

Zinc  “ “ 666° 


Silver  melts  at 1860o 

Gold  “ “ 1983° 

Cast-iron  “ “ 2700° 

Platinum"  “ 4561° 


The  affinity  of  the  metals  for  oxygen  forms  a very  important  item  in  our  investigations.  The  oxides  of 
mercury,  silver,  gold,  platinum  and  the  platinum  metals,  part  with  their  oxygen  by  the  mere  application 
of  heat.  The  following  oxides  of  metals  retain  their  oxygen  at  any  temperature ; they  require  the 
addition  of  carbon  or  hydrogen  in  order  to  expel  their  oxygen  : lead,  copper,  bismuth,  antimony, 
chromium,  arsenic,  nickel,  cobalt,  iron,  tin,  zinc.  Most  of  these  oxides  may  be  deprived  of  their  oxygen 
by  carbon  only,  others  by  carbon  and  hydrogen,  and  some  may  be  reduced  by  hydrogen  only.  Hydrogen 
reduces  all  these  oxides,  but  with  most  of  them  the  point  of  reduction  is  so  low  as  to  leave  the  metal 
in  the  form  of  a fine  powder,  which  oxidizes  as  soon  as  it  is  exposed  to  the  atmosphere.  Iron,  copper, 
nickel,  chromium,  and  other  metals  cannot  be  reduced  by  hydrogen,  on  account  of  the  low  heat  by 
which  the  process  is  accomplished.  Antimony,  arsenic,  tin,  zinc,  lead,  mercury,  and  all  the  alkaline 
metals  may  be  reduced  by  hydrogen.  The  facility  with  which  metals  oxidize  is  also  of  importance 
in  metallurgical  operations.  Lead,  copper,  bismuth,  antimony,  chromium,  and  arsenic  do  not  decompose 
water  at  any  temperature,  but  are  easily  oxidized  by  atmospheric  air.  Nickel,  cobalt,  iron,  tin,  zinc, 
manganese,  decompose  water  easily  at  a red  heat.  All  the  terrifiable  metals,  such  as  aluminum,  and 
we  may  add  silicon,  are  easily  oxidized  at  a higher  heat,  and  their  oxides  readily  reduced  in  the  pres- 
ence of  carbon,  and  of  such  other  metals  as  these  metals  can  combine  with.  The  alkaline  metals 
oxidize  most  readily  under  all  conditions,  and  their  oxides  are  easy  of  reduction  in  the  presence  of  other 
metals,  such  as  lead,  antimony,  and  others  with  which  the  alkaline  metals  may  combine.  Besides  the 
combination  of  the  metals  with  oxygen,  their  union  with  other  matter,  such  as  sulphur,  phosphorus, 
carbon,  Ac.,  is  of  high  interest.  Most  of  the  metals  combine  readily  with  sulphur,  such  as  iron  or 
lead  ; others  are  not  so  easily  disposed  to  enter  into  that  combination,  as  zinc  and  gold.  The  affinity 
of  sulphur  for  the  metals  and  carbon,  and  the  mode  and  conditions  under  which  these  combinations 
may  be  separated,  forms  a very  important  part  of  the  metallurgist’s  knowledge.  Of  the  same  import- 
ance as  the  sulphur  combinations  are  those  of  phosphorus  ; which  combinations  are  in  most  cases  more 


METALLURGY. 


393 


difficult  of  separation  than  all  other  or  similar  compounds.  Of  equal  importance  to  the  smelter  of 
metals,  is  the  relation  of  the  metals  among  themselves  ; it  is  not  so  much  the  nature  and  qualities  of 
these  combinations,  as  the  conditions  under  which  the  metals  combine  and  separate,  which  interest  him. 

The  art  of  smelting  consists  in  the  knowledge  of  the  nature  of  metals,  their  fusibility  and  relation  to 
other  matter.  It  is  not  so  much  the  specific  qualities  of  metals  which  interest  the  metallurgist,  as  the 
mode  of  manufacturing  the  metals  from  their  native  ores.  To  produce  metal  from  ore,  the  first  condi- 
tion is  to  expose  the  ore  to  such  a high  heat  as  will  melt  the  metal.  Gold,  mercury,  and  the  platinum 
metals  may  be  produced  in  this  way  to  a certain  extent.  All  or  most  of  the  metals  in  nature  are 
copibined  with  other  matter,  such  as  oxygen,  sulphur,  phosphorus ; to  remove  the  oxygen,  we  add  to 
the  ore  matter  which  has  a greater  affinity  for  oxygen  than  the  metal,  at  or  near  that  degree  of  heat  by 
which  the  metal  melts:  carbon  is  the  most  generally  in  use, hydrogen  serves  in  some  cases,  and  metals 
in  others.  Metals  and  sulphur,  or  other  matter,  may  be  roasted,  and  the  metal  resolved  into  an  oxide  ; 
but  if  sucli  process  is  not  practicable,  the  sulphuret  or  phosphuret,  <Src.,  is  melted  along  with  another 
metal,  such  as  sulphuret  of  lead  or  copper  with  metallic  iron,  where  always  that  condition  is  complied 
with,  namely,  that  the  newly  formed  metal  is  more  fusible  than  the  newly  formed  sulphuret.  Metallic 
ores  are  in  most  cases  a mechanical  mixture  of  the  metal  in  its  pure  state,  as  gold  ores ; or  a mixture  of 
the  oxide  of  metal  and  other  matter,  such  as  is  the  case  in  clay — iron — stone  : or  the  ores  are  a chemical 
combination  of  one  sulphuret  of  metal  with  other  sulphurets  of  metal,  as  copper-pyrites  in  connection 
with  iron-pyrites,  to  which,  frequently,  silex  or  clay  is  added  in  admixture.  The  prevailing  principle 
in  all  metallurgical  operations  is,  with  but  few  exceptions,  the  transformation  of  all  ores  into  metallic 
oxides,  and  the  reduction  of  these  oxides  by  carbon.  Where  the  metallic  oxides  are  incorporated  with 
matter,  such  as  silex,  alumina,  or  lime,  which  cannot  be  reduced  at  those  temperatures  and  under  those 
conditions  by  which  the  metals  melt  and  are  reduced  themselves,  that  matter  would  prevent  the  agglu- 
tination of  the  metallic  globules,  and  permit  but  a small  portion  of  the  metal  to  separate  from  it,  even  if 
all  other  conditions  of  the  reducing  process  are  fulfilled  ; this  foreign  matter  forms  an  inclosure  to  the  me- 
tallic particles.  This  inclosure  is  to  be  destroyed,  which,  in  many  cases,  can  be  done  by  heat  simply  ; such 
is  the  case  with  some  copper  ores,  where  a certain  portion  of  iron  is  present.  In  other  cases  it  requires 
the  addition  of  such  matter  to  the  ore  which  will  combine  with  the  impurities  of  it,  melt  with  it,  and  lib- 
erate the  metal.  This  latter  part  of  the  science  of  metallurgy  is  the  most  difficult  to  obtain,  and  exerts 
the  most  influence  upon  the  practical  results  of  the  operation.  This  branch  of  our  investigation  it  is  be- 
yond the  limits  of  this  article  to  explore  fully,  we  can  furnish  but  a faint  outline  of  the  principles  involved. 

The  formation  of  fusible  slags  is  accomplished  by  smelting  an  oxide  of  one  metal  together  with  the 
oxide  of  another,  or  these  oxides  together  with  silex.  These  combinations  are  subject  to  the  laws  of 
affinity  developed  by  chemistry.  They  depend  upon  the  quantity  of  the  oxides,  their  degree  of  oxida- 
tion, their  relative  position  in  the  scale  of  affinity,  and  the  conditions  under  which  the  oxides  meet.  The 
most  prevalent  in  these  combinations  are  the  silicates,  or  a vitrification  of  a metallic  oxide  with  silex. 
Either  mixed  to  a silicate,  or  one  mixed  to  the  other,  are  frequently  found  the  carbonates,  chlorides, 
sulphates,  fluates,  and  other  salts,  which  form  in  all  cases  a more  or  less  fusible  slag.  The  nature  of  the 
operation  requires  the  formation  of  a fusible  slag  as  most  advantageous  to  the  process.  In  practice,  this 
principle  is  frequently  modified,  on  account  of  the  quality  of  the  metal  to  be  produced,  or,  more  generally, 
for  reasons  of  economy.  Silex  and  alumina  are  the  most  pervading  admixtures  to  metallic  ores ; these 
are  vitrified  by  all  the  alkalies  and  alkaline  earths,  by  protoxides  of  metals,  and  the  oxides  of  metals. 
The  fusibility  of  these  combinations  is  in  the  following  order : alkalies,  alkaline-earths,  protoxides,  and 
peroxides.  A mixture  of  various  oxides  or  alkalies  is  more  fusible  than  that  of  but  one  alkali  or  oxide, 
with  silex  or  alumina ; the  greater  the  number  of  these  vitrifying  elements,  the  more  fusible  and  homo- 
geneous is  the  slag ; the  greater  the  affinity  between  the  composing  parts  of  a slag,  the  easier  it  melts. 
The  laws  involved  in  this  question  may  be  abstracted  from  chemistry,  always,  however,  with  due 
regard  to  the' temperature  by  which  the  operation  is  performed. 

Preparatory  metallurgical  operations. — Some  metallic  ores  may  be  made  to  yield  their  metal  by 
merely  crushing  and  washing  the  ore — such  are  the  gold  and  platinum  ores.  Other  ores  may  be  smelted 
without  any  preparation  or  addition  of  fluxes ; to  this  class  belong  a large  portion  of  the  copper  ores, 
some  iron  ores,  and  most  of  the  lead  ores.  Some  ores  require  simple  roasting,  others  stamping  and 
roasting,  before  they  are  ready  for  the  smelting  furnace.  Almost  all  the  ores,  to  be  smelted,  require  tlv 
addition  of  fluxes  to  make  the  operation  profitable.  The  manipulations  in  the  smelt-works  avr,  divided 
into  the  preparation  of  fuel,  preparation  of  ore,  and  smelting.  The  first  we  consider  as  too  extended  for 
the  limits  of  this  article,  (see  Iron,)  and  confine  the  subject  to  the  description  of  the  two  latter  pro- 
cesses. Preparation  of  ore  is  again  divided  into  dressing,  roasting,  crushing,  and  washing  of  ore. 

Pressing  of  ore. — An  imperfect  picking  or  sorting  of  ore  is  generally  performed  in  the  mines;  but 
as  a distinct  separation  and  classification  cannot  be  expected  in  this  place,  valuable  ores  are  once  more 
picked  and  cleaned  above-ground  with  greater  care  than  it  could  be  done  in  the  mine.  Iron  ores,  and 
such  ores  which  cannot  bear  such  expense,  are  used  directly  from  the  mine,  without  further  sorting. 
Gold  ores  are  necessarily  assorted  before  they  are  brought  to  the  mill ; the  same  operation  is  performed 
on  silver  ores.  If  there  are  pieces  among  the  ore  which  contain  no  metal  at  all,  they  are  thrown  away  ; 
also  such  as  are  so  poor  as  not  to  pay  the  expenses  of  the  subsequent  operations. 

Stamping  of  ore. — If  the  mixture  of  metallic  ore  and  impurities  is  very  intimate,  and  are  the  impuri- 
ties of  such  a nature  as  to  make  smelting  difficult,  they  are  moved  to  the  stamping-mill,  where  the 
ores  are  crushed,  broken  into  a more  or  less  fine  sand,  and  washed.  Crushing  is  performed  by  ma- 
chinery called  a stamping-mill. 

In  Fig.  2805  a mill  of  this  kind  is  represented  in  plan,  and  in  Fig.  2806  in  elevation.  The  machine 
represented  in  the  engravings  has  been  erected  in  Virginia  during  the  last  year. 

For  the  crushing  of  gold  ore  there  are  30  stampers  connected  with  the  engine,  which  is  of  40  horse- 
power. These  stampers  are  scantlings  of  white-oak  wood,  6 feet  long,  and  6X6  inches  thick.  Each 
wooden  stamper  is  provided  at  its  lower  end  with  a cast-iron  pestle,  (stamper-head,)  weighing  from  2 


394 


METALLURGY. 


to  2i  cwts.  each.  These  stamper-heads  are  made  of  the  finest  and  hardest  kind  of  cast-iron,  such  iro« 
as  chilled  rollers  are  made  of,  and  are  cast  in  heavy  iron  chills,  so  as  to  harden  the  whole  surface  of  the 
head.  These  heads  are  fastened  to  the  wooden  helve  by  a wrought-iron  tang  of  two  inches  square 
iron,  cast  in  into  the  head  and  sunk  into  the  centre  of  the  wood,  where  it  is  secured  by  wrought-iron 


hoops  laid  around  the  lower  end  of  the  helve.  The  SO  stampers  are  divided  into  3 sets  of  5 each ; these 
5 stampers  work  into  one  trough — that  is,  the  whole  length  of  the  trough  is  divided  into  6 compart- 
ments, of  which  each  forms  a set  or  battery.  Each  battery  has  its  own  feeding  apparatus  ; this  is  a 


Into  this  hopper  the  ore  is  carried  as  it  comes 
2807. 


large,  wooden,  fixed  hopper,  as  shown  in  Fig.  2807. 
from  the  hive.  It  discharges  the  ore  in  the  middle 
of  the  battery  or  set  of  five  stampers,  the  middle 
stamper  drawing  as  much  ore  as,  with  the  assist- 
ance of  the  two  stampers  on  each  side,  it  can  crush. 

The  bottom  of  each  trough  is  provided  with  a cast- 
iron  plate;  the  stampers,  however,  never  touch  tliis 
plate.  Upon  this  bed-plate  a bed  of  quartz  is  laid, 
and  kept  so  that  always  from  2 to  4 inches  high  of 
partly  crushed  quartz  is  in  the  bottom  of  each  bat- 
tery. This  bottom  of  rocky  matter  protects  the  iron 
bottom,  the  stampers,  and  the  whole  machinery 
against  premature  destruction.  Each  battery  is  in- 
closed by  a trough  made  of  cast-iron  plates,  reach- 
ing about  7 inches  high  above  the  bottom  plate. 

The  woodwork  to  which  these  plates  are  fastened  is  higher,  and  reaches  up  to  12  or  more  inches.  Each 
battery  is  provided  witli  two  sieves,  or  grates,  shown  by  A ; these  are  made  of  sheet-iron,  or  sheet-cop- 
per, pierced  with  holes,  or  they  are  made  of  brass- wire  gauze,  tweeled,  in  which  wire  and  spaces  are 
each  about  of  an  inch.  Round  holes  punched  in  plates  ought  to  be  or  -Jg  of  an  inch  in  diameter. 
These  sieves  are  8 inches  square,  fastened  vertically  at  each  end  of  the  trough,  about  4 inches  or  3£ 
inches  above  the  bottom.  The  size  and  form  of  the  holes  in  the  sieves  decide  the  size  of  the  grains  of 
sand  made,  for  all  grains  which  cannot  pass  these  holes  are  returned  to  the  stamps. 

Tliis  stamping-machine  crushes  and  washes  the  ore  in  the  mean  time,  each  stamper  receiving  2J 
gallons  of  water  per  minute.  Where  ores  are  stamped  dry,  the  breast-plate  and  sieves  at  each  battery 
can  be  dispensed  with.  The  yield  of  the  machine  is  about  1000  bushels  of  quartz  converted  into  fine 
sand  fit  for  amalgamation  in  12  hours,  each  pestle  making  from  90  to  100  strokes  per  minute,  having 
10  or  11  inches  lift.  The  water  in  the  trough  ought  to  be  always  high  enough  to  prevent  splashing, 
and  loss  of  good  mineral.  There  is  a diversity  of  opinion  respecting  the  construction  of  stamping- 
machines,  many  machines  being  now  built  entirely  of  cast-iron.  We  are  not  aware  that  any  superior 
results  have  been  achieved  by  cast-iron  machines.  It  is  against  the  practice  and  principles  of  mechanics 
to  build  machines  which  work  by  concussion  of  an  almost  inelastic  material  such  as  cast-iron.  Wooden 
machines  of  this  kind  are,  in  the  first  place,  cheaper,  and,  if  well  built,  are  more  durable  and  of  greater 
effect  than  cast-iron  structures. 

Gold  ores  are  stamped  to  liberate  the  metallic  gold  inclosed  by  rocky  matter.  Lead  ores,  copper 
ores,  silver  ores,  &c.,  are  stamped  to  wash  off  the  gangue.  Rocky  matter  is  of  a smaller  specific 
gravity  than  the  metallic  ores  generally  are,  particularly  the  sulphurets.  When  an  ore  is  pulverized, 
and  a current  of  water  passed  through  the  trough  containing  it,  the  sand  and  clay,  limestone,  <fcc , will 
pass  off  readily  in  coarse  grains,  because  its  gravity  is  greatly  diminished  in  water : such  grains  are  car- 
ried off  by  the  slightest  current.  Metallic  substances  more  heavy  than  quartz  or  rocky  matter,  will  not 
move  until  reduced  to  a certain  size,  when  the  particles  will  follow  the  current  by  adhesion,  or  be  so 
inconsiderable  as  to  be  carried  off  by  the  wash  water.  The  current  of  water  issuing  from  the  stamps 
will  carry  the  rocky  matter  further  than  the  metallic  granules,  and  if  the  water  and  sand  from  the 
stamps  is  led  into  a long  wooden  trough,  the  lightest  particles  will  be  found  furthest  off  the  stamps,  and 
the  heaviest  matter  nearest  to  the  mill.  The  size  of  the  grains  is  regulated  in  the  mill,  chif  fly  by  the 
height  of  the  grating  or  sieve  above  the  bottom  of  the  trough  or  stamper-bed ; further  by  the  size  of  the 


METALLURGY. 


895 


holes  in  the  sieve ; by  the  amount  of  water ; by  the  lift  of  the  stamps,  weight  of  stamps,  and  particu- 
larly by  the  kind  of  bottom  used.  If  the  bottom  is  too  hard  or  thin,  the  mill  stamps  coarsely ; and  if  the 
rock  bottom  is  too  thick,  it  stamps  too  fine. 

Other  means  of  grinding  or  crushing  ore  are  millstones,  of  considerable  weight  and  size.  In  Fig. 
2808  a mill  of  this  kind  is  represented.  A vertical  shaft,  to  which  a cross  shaft  and  two  millstones  of 
4 or  5 feet  diameter  are  appended,  revolves  slowly  around  itselt,  making  from  3 to  five  revolutions  per 
minute.  This  shaft  carries  with  it  the  two  head-stones,  which  revolve  around  the  vertical  axis,  and  in 
the  mean  time  around  their  own  axis,  running  upon  a third  millstone,  which  is  laid  horizontal,  and  fixed 
upon  the  floor  of  the  millhouse.  These  stones  are  of  hard  material,  either  of  granite,  gneiss,  trap,  or 
some  other  tenacious  hard  rock.  Such  mills  are  chiefly  used  for  grinding  clay,  fire-clay,  or  kaolin  in  poi 


2808. 


celain  manufactories.  Similar  mills  are  exclusively  employed  in  North  Carolina  for  crushing  gold  ores, 
also  to  some  extent  in  Virginia ; they  are  there  entirely  constructed  of  iron,  or  at  least  the  facing,  or 
grinding  part  of  it  is  made  of  cast-iron ; and  are  here  called  Chilian-mills.  These  mills  show  one  ad- 
vantage to  the  stamper-mills;  that  is,  they  may  be  made  to  grind  the  ore  very  fine ; and  where  that  is 
necessary,  as  it  is  with  many  gold  ores,  these  mills  are  advantageous.  But  there  is  one  serious  draw- 
back to  these  machines : they  require  much  power  in  proportion  to  their  effect,  and  much  room.  A 
strong  mill  of  this  kind  requires  from  4 to  6 horse-power,  with  which  it  will  grind  from  40  to  50  bushels 
of  ore  in  12  hours,  that  is,  ten  bushels  to  a horse-power.  One  horse-power  will  drive  one  stamper  in  a 
stamp-mill,  and  that  stamper  will  crush  at  least  30  bushels  in  the  same  time, — a consideration  which 
is  of  importance  where  wages,  power,  and  time  are  valuable.  Other  crushing  apparatus,  such  as  common 
mills,  in  the  form  of  grist-mills,  crushing  rollers,  and  similar  machinery,  are  not  in  use  in  this  country,  at 
least  not  to  any  extent. 

Washing  of  ores. — Ores  which  contain  a considerable  amount  of  clay,  lime,  sand,  and  other  impurities 
which  may  be  injurious  to  the  smelting  operation,  are  washed  in  an  abundance  of  water,  so  as  to  carry 
off  the  light  particles  and  retain  the  heavy  metallic  matter.  The  simplest  form  of  a washing  apparatus, 
such  as  is  used  for  washing  impure  iron  ores,  is  represented  in  Fig.  2809.  A is  a long  wooden  trough  of 
from  20  to  50  feet  long,  12  inches  wide  in 
the  bottom,  and  6 or  8 inches  high.  This 
trough  is  a little  inclined  to  the  horizon,  so 
as  to  afford  a gentle  current.  At  the  up- 
per end  a strong  current  of  water  is  let 
into  it,  from  a weir  or  an  elevated  reser- 
voir, which  flows  down  the  channel  at  a 
rapid  rate.  At  the  entrance  of  the  water 
a laborer  throws  in,  at  intervals,  a shovel- 
full  of  unclean  ore,  under  the  current  from 
the  spout  of  the  pool.  The  water  in  fall- 
ing upon  the  ore  moves  first  the  small 
and  light  particles,  which  are  carried 
downwards  to  the  valves  B and  C.  The 
light,  floating  particles  are  carried  over 
these  valves,  and  are  discharged  at 
the  end  of  the  trough.  The  heavier  particles  near  the  bottom  are  carried  to  the  valves  and  pass 
through  these,  the  coarse  through  the  opening  B,  and  the  smaller  through  C,  forming  heaps  below, 
from  which  the  remaining  light  impurities  flow  off.  This  apparatus  is  simple,  effective,  and  may 
be  applied  in  all  instances  where  washing  is  to  be  done.  Various  modes  and  machines  are  used 
in  Europe  to  remove  the  earthy  matter  from  the  ore  by  washing.  Complicated  sifting  machines 
are  employed,  the  grilles  or  step-washings  of  Hungary,  percussion-tables,  shaking-tables,  German-chests, 
sleeping-tables,  swing-sieves,  and  a host  of  other  machines,  all  of  which  are  of  no  use  to  us ; these  ma- 
chines work  too  slow,  absorb  too  much  labor,  and  are  not  advantageous  to  our  modes  of  working.  The 
above  wash  apparatus,  properly  modified  in  particular  cases,  is  all-sufficient  for  washing  any  kind  of 
ore,  and  purifying  it  so  far  as  necessary. 

Boasting  of  ores. — This  process  is  sometimes  performed  on  the  ores  when  brought  from  the  mine,  as 


BOG 


METALLURGY. 


is  the  case  with  iron  ore,  or  it  is  performed  after  the  ores  are  crushed,  wdiich  is  the  way  cf  working  sil 
ver  ores  in  North  Carolina.  The  principle  involved  in  this  operation  is  to  drive  off  all  that  volatile  mat- 
ter from  the  ore  which  may  be  dissipated  by  heat ; such  as  water,  carbon,  sulphur,  phosphorus,  chlorine, 
arsenic,  zinc,  &c.  The  consequence  of  this  operation,  if  well  performed,  is  in  all  cases,  with  but  few 
exceptions,  the  oxidation  of  the  remaining  metals  to  their  highest  degree  ; a condition  in  which  the  ores 
are  most  easily  worked,  and  reduced  by  carbon  to  the  metallic  state.  Roasting  is  performed  in  this 
country  almost  exclusively  in  the  open  air;  experiments  made  on  roasting  ovens  met  in  but  few  instan- 
ces with  success.  There  is  no  doubt  but  that  roast  ovens  are  more  economical  in  the  use  of  fuel  than 
heaps  in  the  open  air,  but  the  ovens  require  more  labor ; and  as  fuel  is  cheap  with  us,  labor  high,  the 
reverse  of  what  they  are  in  Europe,  it  appears  to  be  natural  to  follow  those  modes  of  working  which 
tend  to  lessen  cost,  and  do  the  work  in  the  cheapest  way.  In  Fig.  2810  a roast-heap  is  represented  in 
section.  These  heaps  are  often  round,  but  in  most  cases  are  mounds  of  from  25  to  50  and  more  feet 
long.  The  operation  consists  in  spreading  over  an  area  of  a certain  length,  and  from  8 to  20  feet  wide, 
sticks  of  fire-wood,  which  may  be  of  an  indifferent 
kind  and  form.  The  spaces  between  the  sticks  are 
filled  up  by  small  wood,  chips,  or  any  kind  of  fuel, 
providing,  however,  sufficient  spaces  for  the  access 
of  air  from  below.  The  coarser  pieces  of  ore  are 
now  spread  over  this  grating  of  wood,  and  a layer 
of  from  8 to  12  inches  levelled  over  it;  on  this  ore 
fine  charcoal,  braise,  is  spread  about  2 inches  thick. 

Instead  of  fine  charcoal,  mineral  coal  slack  may  be 
used  to  advantage,  or  wood  chips,  or  in  fact  any 
fuel  free  of  injurious  matter,  such  as  sulphur,  phos- 
phorus, &c.  Ore  is  now  piled  again  upon  this  coal,  and  the  operation  of  laying  coal  and  ore  in  succes- 
sive layers  repeated  until  that  height  of  the  heap  is  reached  which  is  calculated  to  be  most  ad- 
vantageous in  this  particular  instance.  One  inch  thick  of  coal  is  generally  considered  sufficient  for  one 
foot  high  of  ore,  exclusive  of  the  foundation  of  wood.  The  ore  is  broken  into  uniform  sizes,  of  from  2 to  3 
inches  thick.  Fire  is  kindled  in  the  lower  parts  of  the  heap,  which  to  conduct  to  advantage  requires 
considerable  skill,  sagacity,  and  industry.  The  chief  object  in  this  operation  being  the  dissipation  of 
volatile  matter,  it  is  evident  that  the  melting  of  any  particles  of  the  ore  is  to  be  prevented,  for  from 
such  melted  ore  no  degree  of  heat  will  separate  the  injurious  matter  effectually.  The  conducting  of 
the  degree  of  heat  in  the  roasting  heap  is  therefore  an  operation  liable  to  injure  the  ore  instead  of  bene- 
fiting it.  Ores  which  melt  readily,  such  as  impure  iron  ores,  silver  and  lead  ores,  pyrites  of  all  kinds, 
require  oore  than  common  watchfulness  to  insure  success  in  the  operation. 

Fi&  2911  represents  the  section  of  a reverberatory  furnace  for  roasting  schliech  of  lead  ore  in  Ger- 
man"; These  ores  contain  much  sulphuret  of  zinc,  and  resemble  our  silver  ores  in  Virginia  and  North 


2810. 


Carolina,  for  which  reasons  we  allude  particularly  to  this  furnace.  Fig.  2812  is  the  diawmg  of  an  ele- 
vation of  that  furnace,  showing  it  to  be  a double  furnace ; and  Fig.  2813  is  the  plan  of  half  the  furnace, 
or  one  single  furnace.  In  these  several  figures,  a is  the  furnace  or  fireplace ; b,  a chimney  leading  to 


METALLURGY. 


397 


the  condensing  chambers  cc,  in  which  the  evaporated  metals,  as  zinc,  arsenic,  Ac.,  are  conducted ; d is 
the  stack  for  the  escape  of  the  burnt  gases  and  smoke  ; e‘  is  the  charging  door ; f the  drying  chamber 
for  expelling  the  water  from  the  ore  ; g is  the  hopper  or  charging  orifice ; h the  hearth  of  the  furnace  ; 
i channels  for  the  escape  of  moisture  from  the  ground ; n n’  are  openings  leading  to  the  condensing 
chambers.  In  each  of  these  furnaces  nearly  half  a ton  of  ore  is  charged  at  a time,  which  takes  from  a 
to  12  hours  work  to  be  roasted;  much  zinc  delays  the  process.  About  two  thirds  of  a cord  of  wood  is 
required  to  perform  one  heat.  If  well  constructed  and  properly  managed,  these  furnaces  work  exceed- 
ingly well,  but  require  a great  deal  of  labor. 

As  remarked  before,  roasting  ovens  are  more  economical  in  the  use  of  fuel  than  heaps  in  the  open 
air  ; this  advantage,  however,  is  balanced  by  our  having  generally  cheap  fuel.  These  ovens  are  liable 
to  do  imperfect  work ; the  access  of  air,  which  is  the  chief  oxidizing  agent,  is  not  so  freely  admitted  as 
in  heaps.  In  ovens  the  advantageous  access  of  watery  vapors  is  out  of  the  question,  which,  as  in  the 
case  of  heaps,  are  derived  from  the  ground  in  such  quantities  and  in  such  conditions  as  to  be  most  advan- 
tageous to  the  operation.  Watery  vapors  afford  in  roasting  the  triple  advantage  of  being  a powerful 
oxidizing  element,  in  the  mean  time  carrying  off  sulphur  in  the  form  of  sulphuretted  hydrogen,  and  assist- 
ing in  keeping  the  heat  more  uniform  than  it  can  be  done  without  these  vapors.  The  roasting  in  heaps 
may  be  more  expensive  in  some  cases ; it  certainly  is  more  correct  in  principle  than  roasting  in  ovens. 

Boasting  in  reverberatory  furnaces  may  be  considered  an  advantageous  operation  where  sulphur, 
arsenic,  and  such  volatile  matter  is  to  be  expelled  which  cannot  well  be  removed  in  the  yard  by  roast- 
ing in  heaps.  These  furnaces  apply  particularly  where  arsenic  is  to  be  driven  off;  but  as  no  arsenical 
ores  are  smelted  in  the  Union,  there  is  little  use  for  reverberatory  roast-ovens.  At  the  copper  smelt- 
works  roasting  is  done  to  a certain  extent  in  the  reverberatory,  but  it  is  not  practised  in  any  other  in- 
stance. This  furnace  suffers  under  the  same  disadvantage  as  the  roast-oven ; the  work  performed  by  it 
is  expensive,  because  of  the  labor  it  requires  to  stir  and  shovel  the  ore. 

Blast  machines  are  auxiliaries  in  metallurgical  operations.  We  refer  to  the  article  on  “Iron"  for  in- 
formation. 

Assay  of  ores  is  a very  important  operation  in  smelt-works.  Assaying  is  not  only  performed  here  to 
ascertain  the  quantity  of  metal  contained  in  the  ore  ; it  is  employed  both  for  that  purpose  and  for  assay- 
ing the  metal  to  inquire  what  kind  of  metals  and  how  much  of  each  is  contained  in  the  samples  pro- 
duced in  the  smelting-furnace.  Assays  of  gold  ores  are  generally  made  by  pounding  the  rock,  convert- 
ing it  into  a very  fine  powder,  and  washing  the  debris  of  rock  away,  which  latter  operation  is. performed 
in  a sheet-iron  pan.  The  remaining  gold,  after  washing,  is  either  taken  up,  amalgamated  by  quicksilver, 
and  the  quicksilver  expelled  by  heat,  or,  if  the  quantity  is  large,  say  one  grain  or  more,  it  is  weighed 
in  its  native  state.  Experienced  gold-washers  will  judge  very  near  correctly  how  much  one  bushel  of 
ore  will  contain  in  gold  by  making  one  or  more  pan-washes. 

Assays  for  ascertaining  the  quantity  of  a certain  kind  of  metal  in  a specimen  of  ore,  are  in  this  in- 
stance chiefly  made  in  the  dry  way.  If  an  ore  is  to  be  assayed  for  its  contents  in  gold  or  silver,  the 
ore  is  finely  powdered,  sieved,  and  mixed  with  its  three  or  fourfold  weight  of  litharge.  This  litharge 
must  be  free  from  any  other  metal  but  lead ; the  common  shop  litharge  is  not  quite  safe  in  this  respect, 
and  in  case  a correct  assay  is  required,  it  is  advisable  to  dry  and  roast  sugar  of  lead  ; the  litharge  de- 
rived from  it  may  be  considered  pure.  The  fine  litharge  and  fine  ore  are  well  mixed,  to  which  a very 
little  carbonate  of  soda  may  be  added.  If  not  much  gold  or  silver  is  expected,  but  little  lead  is  re- 
duced in  this  process,  which  is  regulated  by  the  quantity  of  carbon  mixed  with  it.  In  most  cases,  half 
an  ounce  of  lead  will  contain  all  the  gold  and  silver  in  the  ore  ; one  grain  of  charcoal  produces  SO 
grains  of  lead ; if  we  want,  therefore,  240  grains,  or  one  half  ounce  of  lead,  we  mix  8 grains  of  fine 
charcoal  powder  with  the  above  mixture  of  ore  and  litharge.  The  mixture  is  put  in  a dry  and  warm 
crucible,  covered  by  a little  common  salt,  and  a slab  to  prevent  the  falling  in  of  coal,  and  then  exposed 
to  a rapid  heat  in  an  air-furnace.  One  half  hour’s  heat  will  finish  the  operation  ; the  crucible  is  cooled, 
broken,  and  the  button  of  lead  removed,  washed,  and  cupelled.  This  button  of  lead,  of  half  an  ounce 
weight,  requires  a cupel  of  half  an  ounce;  better  if  one  ounce.  The  cupel  is  a flat  crucible,  made  of 
bone-ashes,  which,  when  the  lead  is  heated  in  it,  and  in  the  mean  time  oxidized,  it  absorbs  the  oxide  of 
lead,  just  as  a sponge  absorbs  water ; but  this  cupel  will  not  absorb  any  metal  in  the  metallic  state. 
Gold  and  silver  have  but  little  affinity  for  oxygen,  and  in  heating  the  alloy  of  lead  and  other  metals, 
all  other  metals  will  be  oxidized  and  absorbed  by  the  cupel,  while  gold  and  silver  remain  in  their  pure 
condition.  When,  in  exposing  the  cupel  in  a muffle,  or  in  a crucible,  to  a white  heat,  all  the  lead  and 
n+ber  metal  is  oxidized  and  absorbed,  a bright  globule  of  gold  or  silver,  or  a mixture  of  both,  remains ; 
m the  latter  case  the  globule  is  analyzed  in  the  humid  way,  to  ascertain  the  quantity  of  either  metal, 
gold  or  silver. 

Aext  to  the  assays  of  gold  or  silver  ores,  are  those  of  copper.  These  ores  are  pounded,  roasted,  and 
mixed  with  from  1 5 to  100  per  cent,  of  black  flux.  Black  flux  is  prepared  in  mixing  the  powders  of 
equal  parts  of  saltpetre  and  crude  tartar  together,  heating  this  mass  gently,  and  stirring  it  with  a red- 
hot  iron  ; the  burnt  powder  is  again  pounded,  sifted,  and  kept  in  a glass-stoppered  bottle  for  occasional 
use.  The  well-pounded  and  roasted  ore  is  intimately  mixed  with  its  flux,  put  into  a crucible,  and  heated 
to  a bright  white  heat  in  the  shortest  time.  The  resulting  button  of  copper  is  broken  out  of  the  cooled 
crucible  and  washed ; it  is  crude  copper,  and  requires  to  be  refined.  This  button  is  pounded  in  case  it 
is  brittle;  if  not,  it  is  melted  in  its  original  form,  along  with  half  its  weight  of  black  flux,  to  which  a 
little  common  salt  or  saltpetre  is  added  ; the  first,  however,  is  preferable.  While  this  crucible  is  melt- 
mg,  another  is  heated,  in  which  a flux  composed  of  black  flux,  common  salt,  and  saltpetre,  is  contained ; 
when  the  copper  is  thoroughly  melted,  and  the  second  crucible  hot,  the  flux  melted,  the  copper  is  cast 
from  the  first  into  the  latter.  By  these  means,  metal  and  flux  is  mixed  without  running  the  risk  of 
losses,  which  inevitably  follow  if  the  crucibles  are  not  shaken,  or  if  they  are  stirred  by  an  iron  rod.  If 
the  copper  after  this  second  assay  is  not  fine,  the  process  of  refining  is  repeated  once  more,  by  which 
time  fine  Conner  is  obtained.  In  Tiis  operation,  some  copper  remains  always  in  the  scoriae ; the  lattei 


398 


METALLURGY. 


may  be  gathered  together  from  all  the  smeltings  and  melted  along  -with  some  black  flux,  -which  will 
produce  a small  button  of  crude  copper ; this  is  added  to  the  first  after  it  is  refined,  or  added  by  ap- 
proximating its  value  in  copper.  This  last  grain  contains  generally  a great  deal  of  iron,  and  looks  like 
iron. 

Other  ores  than  those  mentioned  are  commonly  not  assayed  in  the  smelt-works.  Iron,  lead,  zinc,  etc., 
are  of  too  little  value ; they  canuot  bear  these  expenses.  Tin  we  are  not  yet  smelting,  and  in  so  far 
have  no  need  of  assaying  it. 

Assaying  forms  a very  important  branch  of  the  smelting  establishment.  In  this  country,  owing  to 
the  youth  of  metallurgical  operations,  most  of  the  smelt-works  are  connected  with  the  mines ; from 
this  rule  the  copper  smelt-works  are  only  excepted.  For  these  reasons,  the  assay  necessary  to  ascertain 
the  value  of  ore,  in  order  to  establish  its  price,  is  not  in  extensive  use.  When  smelt-works  shall  be  car- 
ried on  in  their  proper  form,  assaying  of  ore  will  be  more  generally  executed.  At  present  the  assays 
of  ore  are  only  used  to  ascertain  the  value  of  ore  specimens,  by  which  assays,  as  they  allude  but  to  a 
small  and  in  most  cases  a selected  part  of  the  ore,  many  illusory  prices  of  ore  are  furnished,  which  de- 
ceive the  unwary.  All  assays  made  in  the  dry  way  are  incorrect;  they  always  furnish  a smaller 
amount  of  metal  than  the  large  operation  ; if,  however,  the  assays  are  conducted  with  uniform  precision, 
the  loss  in  each  case  will  be  the  same,  and  may  be  represented  by  a per-centage  of  the  whole.  The 
second  feature  of  the  utility  of  the  dry  assay  is  its  affording  indications  of  the  amount  and  nature  of 
the  foreign  admixtures  to  the  ore  : it  furnishes  a guide  to  the  smelter  at  the  furnace.  Experiments  as 
to  the  mode  of  smelting  an  ore  to  the  best  advantage,  can  be  made  in  the  crucible  with  less  expense 
and  greater  facility  than  in  the  smelting  furnace.  A third  advantage  arising  from  the  assay  laboratory 
ts  the  analysis  of  the  manufactured  metal  in  respect  to  its  purity  and  contents  of  precious  metals. 

Assay  in  the  humid  way. — The  chemical  analysis  of  ore,  or  the  assay  in  the  humid  way,  is  not  of 
much  practical  use  to  the  metallurgist.  If  this  assay  is  well  performed,  it  furnishes  an  exact  table  of 
the  contents  of  an  ore,  of  slags,  and  of  metals  ; but  it  requires  more  science  and  experience  than  com- 
monly is  at  the  disposal  of  the  practical  man,  to  make  that  use  of  an  analysis  winch  frequently  is 
expected  from  it.  The  humid  analysis  furnishes  the  facts,  the  elements  for  the  science  of  metallurgy ; 
but  the  application  of  these  facts  is  subject  to  more  difficulties  than  at  a superficial  glance  appear:  it 
is  moreover  a means  of  inducing  young,  speculative  minds  to  a waste  of  time  and  money  which  may  be 
better  employed  than  in  chemical  analysis.  This  department  belongs  to  the  scientific  chemist : it  is  of 
no  use  in  the  smelting-house.  There  is  no  doubt  but  the  humid  analysis  furnishes  the  most  correct  esti- 
mate of  the  contents  of  an  ore,  slag,  and  metal,  but  in  all  instances  it  is  advisable  to  verify  these  results 
by  the  dry  assay,  for  there  are  innumerable  instances  where  the  portions  of  metal  obtained  in  the  analy- 
sis cannot  be  yielded  by  the  ore  in  the  most  perfect  smelting  operations.  The  assay  comes  nearer  to 
the  practical  result  than  the  analysis.  We  cannot  deny  that  the  analysis  furnishes  principles  upon 
which  improvements  are  and  may  be  executed,  but  these  principles  and  facts  are  only  useful  in  the 
hands  of  a scientific  and  experienced  metallurgist. 

The  manufacture  of  metals. — In  this  part  of  our  labors  we  shall  omit  the  allusion  to  iron,  because  a 
valuable  contribution  is  furnished  under  the  proper  head ; we  shall  further  limit  ourselves  to  those 
metals  which  are  actually  manufactured,  or  are  likely  to  be  manufactured  in  the  United  States. 

Gold. — Germ,  gold;  Fr.  Or;  Lat.  Aurum.  Gold  is  found  almost  over  the  whole  globe,  but  in  most 
cases  in  small  quantities  compared  with  other  metals.  At  the  present  time  California  affords  the 
largest  amount  of  this  metal  in  the  world.  Virginia,  North  Carolina,  South  Carolina,  Georgia,  and  Ala- 
bama, in  the  United  States,  afford  gold  in  considerable  quantity.  The  production  of  California  amounted 
in  the  year  1850  to  about  §40,000,000  worth  of  this  metal ; the  other  States  of  the  Union  together  about 
§2,000,000.  Next  to  the  United  States,  the  largest  amount  of  gold  is  furnished  by  Russia,  from  the 
Ural  Mountains.  It  is  found  extensively  in  the  South  American  States,  near  the  Equator,  in  Africa, 
Asia,  and  Europe.  Gold  is  chiefly  found  in  its  native  condition,  in  a metallic  state,  alloyed  with  silver, 
and  sometimes  with  tellurium,  as  is  the  case  in  Virginia  and  North  Carolina.  In  California  it  is  found 
chiefly  in  alluvial  ground,  bedded  upon  rock  in  most  cases ; it  is  also  found  inclosed  in  quartz  rock,  ap- 
parently in  veins  ramifying  the  rocks  of  an  extensive  mountain  range.  This  California  gold  is  ob- 
tained chiefly  in  large  grains,  and  often  in  lumps  of  several  pounds  weight.  In  the  other  States  of  the 
Union  the  gold  is  in  very  minute  fragments,  often  invisible  to  the  eye  if  not  aided  by  a lens,  only  to  be 
detected  by  crushing  and  grinding  the  rock  and  washing  off  the  debris.  This  gold  is  apparently  de- 
rived from  the  decomposition  of  iron  and  copper  pyrites,  chiefly  the  first ; which  assertion  cannot  be  ob- 
jected to,  because  it  is  founded  in  principle  that  almost  all  iron  pyrites  contain  gold,  that  the  gold  ores 
of  that  region  are  rocks  which  are  colored  by  iron,  and  that  this  iron  is  evidently  derived  from  the  de- 
composition of  the  pyrites.  Pyritous  ores  of  this  kind  are  worked  which  contain  no  visible  gold,  or 
which  do  not  yield  gold  at  the  first  crushing  and  washing,  but  which  furnish  gold  in  a succession  of 
amalgamations,  performed  after  regular  intervals  of  exposure  to  the  air  in  a fine  powder.  Gold  is  also 
furnished  by  the  silver  ores  of  North  Carolina  and  Virginia. 

A splendid  yellow  color  and  brilliant  metallic  lustre  characterizes  gold  distinctly  from  other  metals ; 
its  specific  gravity  being  19'3  to  water,  is  another  quality  easily  appreciated  by  the  senses.  It  is  pre- 
eminently ductile,  which  qualifies  it  for  an  extensive  use  in  the  arts.  One  grain  of  gold  may  be  drawn 
into  a wire  500  feet  long ; silver  may  be  coated  with  gold,  of  which  the  thickness  is  only  the  twelve- 
millionth  part  of  an  inch,  and  still  the  microscope  cannot  detect  the  slightest  indication  of  an  interrupt 
tion  of  the  gold  coating.  Pure  gold  requires  more  heat  for  melting  than  either  silver  or  copper,  but  as 
all  native  gold  is  alloyed  with  some  other  metal,  it  may  be  considered  more  fusible  than  those 
metals.  If,  in  cupelling  gold,  the  hot  globule  shines  with  a greenish  light,  we  may  consider  the  gold 
not  much  adulterated ; if  it  contains  10  per  cent.,  or  from  there  to  one-third  of  silver,  the  color  of  the 
gold  is  in  the  hot  cupel  white  as  silver.  Pure  gold  is  not  very  volatile,  and  may  be  exposed  to  a strong 
beat  for  a long  time  without  loss  of  metal ; but  if  gold  is  alloyed  with  volatile  metal,  such  as  lead,  zinc, 
tnd  antimony,  it  is  liable  to  be  carried  off  by  their  vapors.  Gold  has  a considerable  cohesion,  which 


METALLURGY. 


399 


inclines  it  to  crystallization.  Its  crystal  form  is  an  octahedron  ; it  is  often  found  in  fragments  of  crystals 
imbedded  in  quartz,  of  which  fine  specimens  are  found  in  California,  and  also  in  the  gold  region  of  the 
Southern  States.  In  melting  gold  along  with  pure  borax  it  assumes  a -whitish  color,  as  if  adulterated 
with  silver ; in  melting  it  again  with  saltpetre,  or  common  salt,  it  recovers  its  rich  yellow  color. 

The  geological  position  of  gold  is  in  the  primitive  rock.  It  is  found  in  granite,  disseminated  in 
grains  and  spangles  through  the  mass  of  rock.  In  the  United  States  gold  is  chiefly  found  in  the 
stratified  transition  series ; in  California  it  appears  to  be  disseminated  through  this  rock,  imbedded  in 
quartz.  Most  of  the  gold,  the  California  gold  exclusively,  is  found  in  alluvial  soil.  In  the  Southern 
gold  region  this  source  is  much  exhausted,  and  the  gold  is  here  obtained  from  regular,  well-developed 
veins,  running  parallel  with  the  general  direction  of  the  rock  strata,  southwest  by  northeast.  The 
plane  of  inclination  of  these  veins  is  also  parallel  wfith  the  plane  of  inclination  of  the  general  formation. 
It  appears  from  this  that  the  gold-bearing  veins  are  of  a simultaneous  origin  with  the  rock  ; at  least, 
they  have  been  introduced  when  the  rock  was  in  a plastic  condition.  In  Virginia  and  North  Carolina 
the  gold-bearing  veins  are  a ferruginous  talcose  slate,  often  inclined  to  mica  slate.  In  North  Carolina 
this  slate  is  found  to  be  very  hard  in  many  instances,  showing  a compact  solid  mass  of  rock,  apparently 
the  same  slate,  but  having  been  under  the  influence  of  a considerable  heat,  it  is  hardened.  In  Vir- 
ginia this  slate  is  more  soft,  the  fissures  open  more  readily,  and  the  whole  vein  shows  the  appearance 
of  soft  slate.  This  slate  is  impregnated  with  small  quartz  veins,  from  one-eighth  to  one-half  an  inch, 
and  often  two  inches  thick.  Where  these  quartz  veins  are  thin  and  in  great  numbers,  the  ore  is  always 
found  to  be  richest  in  gold.  This  feature  of  the  ore  is  well  developed  throughout  Virginia,  and  at  Gold- 
hill,  North  Carolina.  The  vein-stone  of  the  gold-bearing  veins  is  strongly  impregnated  with  oxide  of 
iron,  showing  evidences  that  this  iron  is  derived  from  pyrites,  because  the  oxide  appears  in  dots  or 
flowers,  and  groups  of  dots.  Many  of  these  veins  have  been  traced  to  that  depth  where  the  pyrites  are 
not  oxidized ; here  they  appear  in  their  perfect  crystal  form,  and  are  profusely  distributed  through  the 
slate.  The  oxidation  of  these  pyrites  appears  to  depend  on  the  penetrability  of  the  rock  by  atmos- 
pheric agents;  where  the  slate  is  soft  we  find  it  oxidized  to  the  depth  of  from  50  to  150  feet;  where 
the  slate  is  hard,  as  is  the  case  at  the  Sawyer  mine,  North  Carolina,  the  oxidation  reaches  hardly  ten 
or  twenty  feet  deep,  and  is  in  many  places,  such  as  bluffs,  not  developed  at  all.  At  the  latter  spots  the 
pyrites  are  in  their  original  form,  untouched  by  oxygen.  Where  the  pyrites  are  not  oxidized  the  ex- 
traction of  gold  is  connected  with  considerable  more  expense  than  it  is  from  soft  slate  and  oxidized 
pyrites.  The  crushing  of  the  hard  slate  is  in  the  first  place  more  expensive ; the  sulphur  of  the  pyrites 
destroys  a large  portion  of  quicksilver  in  amalgamation,  and  the  gold  cannot  be  all  extracted  ; the 
largest  portion  of  it  remains  inclosed  by  the  sulphuret  of  iron,  which  can  only  be  liberated  by  destroy- 
ing that  envelope. 

When  we  consider  the  great  extension  of  the  Southern  gold  formation,  which  is  at  least  500  miles 
long ; the  breadth  of  the  gold-bearing  strata  in  which  the  veins  are  imbedded,  and  which  is  from  5 to 
20  miles  wide;  further  consider  the  depth  of  these  veins,  which  may  be  assumed  to  be  2000  feet,  the 
body  of  gold  ore  in  these  regions  is  certainly  to  be  regarded  as  an  important  source  of  national  wealth. 
There  is,  however,  one  drawback  to  the  rapid  extraction  of  gold  from  these  deposits — the  ores  are  all, 
without  exception,  pyritous  in  greater  depth,  and  to  work  these  sulphurets  to  advantage  no  progress 
has  been  made  up  to  this  time.  Various  experiments  tending  to  accomplish  this  purpose,  and  affording 
means  of  extraction,  have  been  tried,  but  none  of  these  succeeded  so  far  as  to  work  the  poorer  class  of 
ores.  At  Goldhill,  N.  C.,  where  the  ores  yield  from  $1.50  to  $3  of  gold  in  100  pounds  or  one  bushel  of 
ore,  the  pyritous  ores  are  ground,  amalgamated,  and  a certain  portion  of  gold  extracted.  The  crushed 
ore,  now  a fine  sand,  is  exposed  to  the  influence  of  the  atmosphere  for  one  year,  after  which  the  process 
of  grinding  and  amalgamating  is  repeated,  and  another  portion  of  gold,  almost  equal  to  the  first,  is  ex- 
tracted. An  exposure  of  another  year  furnishes  another  crop  of  gold,  which  operation  may  be  repeated 
four  or  five  times  without  extracting  all  the  metal  from  the  sand.  This  way  of  working  is  tedious, 
expensive,  and  will  not  answer  where  the  ores  yield  but  25  cents  to  the  bushel.  The  process  of  roast- 
ing these  ores  by  artificial  fire  is  too  expensive,  and  all  processes  which  require  much  labor  are  out  of 
the  question.  Here  is  a promising  field  for  American  ingenuity  and  industry. 

The  extraction  of  gold  is  performed  in  California,  and  also  in  some  parts  of  the  Southern  States,  simply 
by  washing  the  alluvial  soil,  removing  the  sand,  clay,  and  debris  of  rock ; after  these  operations  the  gold, 
as  specifically  the  heaviest  matter,  will  remain  in  the  vessel  in  which  the  washing  has  been  performed. 
This  washing  may  be  done  to  advantage  in  a tin  pan  or  a sheet-iron  pan.  Such  a pan  is  filled  with 
sand  containing  the  gold  and  immersed  in  water ; in  stirring  it  gently  by  hand  the  clay  and  light  sand 
flow  off,  and,  after  some  of  the  earthy  matter  is  removed,  the  pan  is  shaken  so  as  to  bring  the  heavier 
gold  to  the  bottom  of  it;  the  superstratum  of  sand  is  now  removed,  and  the  gold  found  in  the  bottom 
of  the  pan.  Where  water  is  abundant,  a more  effective  machine  than  the  pan  is  employed.  This 
machine  is  called  a rocker.  It  is  represented  in  Fig.  2814. 

This  is  a machine  made  of  wood,  about  6 feet  long,  26  inches  high,  and  16  inches  wide  in  the  trough. 
A is  a grating  of  flat  iron  bars,  set  edgeways,  leaving  an  open  space  of  about  ^ an  inch  between  each 
bar.  By  B a strong  current  of  water  is  let  upon  this  grating,  which  flows  off  at  the  opposite  end  of  the 
machine.  The  machine  rests  upon  two  gently  curved  frames,  which  admit  of  a rocking  motion  upon 
two  planks  laid  on  the  ground.  This  apparatus  is  set  in  a rocking  motion  by  a boy.  two  wooden 
springs  on  each  side  of  it  limiting  that  motion,  and  forcing  the  rocker  back  at  each  vibration.  The  ma- 
chine represents  in  its  motion  a worn-out  cradle,  which  is  used  beyond  gentle  rocking.  A laborer 
supplies  the  rocker  with  sand  at  B,  by  means  of  a shovel ; the  sand  which  passes  through  the  grating, 
and  also  the  gold,  falls  into  the  trough  C,  in  which  quicksilver  is  kept  in  case  the  gold  is  fine ; it  forms 
here  an  amalgam  of  gold.  The  light  sand  from  O is  swept  off  by  the  water  which  passes  through  the 
grating.  The  cradle  is  more  or  less  inclined  towards  the  discharge  of  the  charges,  according  to  the 
kind  of  material  to  be  washed.  These  operations  are  quite  effective  ; secure,  for  coarse  gold  ; the  fine 
and  floating  gold  is  lost. 


400 


METALLURGY. 


Gold  inclosed  in  rocky  matter  cannot  be  washed  with  success  in  the  foregoing  described  manner  ; the 
rock  must  be  crushed,  and  is,  in  this  operation,  transformed  into  more  or  less  fine  sand.  The  bulk  of  this 
sand  is  removed  by  washing,  and  the  rest,  with  the  gold,  reserved  for  amalgamation.  The  crushing  is 
performed  in  the  stamp-mill,  Fig.  2808 ; the  sand,  including  gold,  conducted  over  hides,  which  retain  the 
gold,  and  the  sand  is  floated  away.  The  gold  and  sand  from  the  hides  are  removed,  when  the  latter  are 
filled,  to  an  amalgamating  machine,  which  combines  the  gold  with  quicksilver,  and  admits  the  sand  to 
flow  off.  Instead  of  hides,  woollen  blankets  are  also  used  for  gathering  the  gold,  and  there  is  a diversity 
of  opinions  as  to  the  merits  of  either.  Blankets,  it  is  contended,  are  more  expensive  than  hides,  but 
they  have  the  advantage  of  working  more  uniform.  Hides  are  cheaper,  but  they  lose  their  hairs  or 
wool  very  soon,  and  are  then  not  fit  to  do  good  work.  Hides  of  short,  curly  wool  are  selected ; these 
are  spread  on  the  ground,  and  over  these  the  water,  sand,  and  gold  are  led  in  a broad  sheet.  In  other 
instances  shaking-tables  are  suspended  at  the  discharge  of  the  stampers,  which  gather  the  gold  and 
some  sand.  Shaking-tables  are  wooden  platforms  of  8 or  10  feet  long,  and  from  3 to  4 feet  wide,  made 
of  2-inch  plank  well  joined  together,  and  the  whole  smoothly  planed.  Around  the  edges  of  the  table 
are  projecting  ribs,  which  prevent  the  water  from  flowing  over  the  edges.  In  suspending  this  table,  a 
little  inclined  to  the  horizontal,  leading  the  sand  and  water  over  it  in  a broad  sheet,  and  applying  a 
gentle  shaking  motion  to  it,  the  gold  will  sink  to  the  bottom  and  move  gently  down  the  plane  ; it  is 
arrested  at  the  lowest  end  of  the  table  by  a projection  on  the  table.  In  either  of  the  above  cases  the 
gold  is  brought  to  the  amalgamating  machine  for  amalgamation. 

Most  of  the  gold-mining  establishments  are  provided  with  Chilian  mills  for  crushing  the  ore.  "We 
furnish  a description  of  it  in  its  simplest  form  in  Fig.  2808,  in  which  form  most  of  these  machines  are 
erected.  Still,  there  are  some  machines  of  this  kind  in  North  Carolina,  which  work  by  four  or  five  run- 
ners or  crushers  in  one  trough. 


2815. 


In  Fig.  2815  is  such  a machine  represented  as  it  is  in  operation  at  Goldhill.  It  i9  a cast-iron  circular 
trough  of  about  16  feet  diameter,  10  inches  wide,  and  6 inches  deep;  the  trough  is  firmly  fixed  upon 
the  floor  of  the  mill.  In  this  trough  five  travellers  or  head-stones  are  moving,  of  3 feet  diameter  and 
6 inches  thick,  rounded  on  the  edge,  made  of  cast-iron.  These  travellers  are  fixed  to  the  revolving- shaft 
in  the  centre,  and  are  moved  by  it.  The  circular  trough  is  supplied  with  coarsely  broken  ore  and  a con- 
stant current  of  water,  which  latter  washes  off  all  the  light  impurities,  and  leaves  the  gold  in  the  trough. 
At  the  close  of  every  day’s  work  the  trough  is  supplied  with  some  quicksilver,  which  is  worked  in  it  for 
or  hour’s  time,  in  which  time  it  absorbs  the  gold,  and  is  then  removed  as  amalgam.  The  water 
from  these  mills  is  generally  conducted  into  other  machines,  in  which  some  of  the  fine  gold  which  passes 
from  the  first  machine  is  gathered.  In  most  cases  a shallow  round  basin,  of  about  4 feet  diameter,  is 
appended,  in  which  a rake  moves  around  with  a vertical  axis,  gently  stirring  the  sediment  which  may 
settle  from  the  passing  water.  It  retains  only  the  heavy  particles.  In  other  instances,  Sullivan 
bowls  (a  small  machine  which  derived  its  name  from  the  inventor,  residing  in  North  Carolina)  are 
appended ; these  gather  the  heavy  parts  which  may  escape  the  previous  machines. 


2816. 


A Sullivan  bowl  is  represented  in  Fig.  2811.  A vertical  wooden  shaft  of  about  18  inches  long  and 
2 inches  square  carries  on  the  lower  part  a shallow  vessel  or  bowl  B,  about  2 inches  deep  and  18  inches 
in  diameter.  This  bowl  is  formed  of  a wooden  bottom  and  sheet-iron  periphery.  This  bowl  receives 
the  water  from  the  other  machines  at  or  near  its  circumference,  and  discharges  at  the  centre.  By  the 
lever  A,  the  machine  is  set  in  a rocking  motion,  caused  by  a crank  connected  with  the  same.  This 
machine  gathers  a great  deal  of  fine  gold,  but  it  is  an  expensive  machine,  because  they  work  but  little 
water,  and  it  requires  many  machines  to  do  the  work  of  a small  establishment. 

The  gold  from  the  various  machines,  mixed  with  some  sand  and  other  impurities,  is  carried  to  the 
Chilian  mill  for  amalgamation,  in  case  there  is  no  other  machine  for  doing  that  work.  This  is  an  im- 
perfect machine  for  amalgamation,  and  causes  losses  in  quicksilver  and  gold.  In  most  cases  separate 


METALLURGY. 


401 


machines  are  used  for  amalgamation ; in  North  Carolina  the  cradle  is  generally  employed.  The  cradle 
is  made  from  the  trunk  of  a tree,  hollowed  out  so  as  to  form  a round  trough,  closed  at  one  end  and  open 
at  the  other,  as  represented  in  Fig.  2810. 

Here  is  a battery  of  5 cradles  represented  : as  many  as  that  are  frequently  connected  and  moved  by  a 
little  boy.  A cradle  is  from  1 0 to  1 2 feet  long,  hollowed  out  of  a trunk  of  at  least  24  inches  diameter.  The 
bottom  part  is  thicker  than  the  sides.  The  first  cradle  in  the  drawing  shows  a section.  We  see  here  three 
or  more  grooves  carved  in  the  bottom  ; in  each  of  these  grooves  from  3 to  4 pounds  of  quicksilver  are  put. 
At  the  farthest  end  sand  is  shovelled  in  and  water  led  upon  it,  the  cradles  being  a little  inclined  towards 
the  discharge.  A gentle  current  of  water  will  have  a tendency  to  wash  sand  and  every  thing  else  down 
the  trough,  the  trough  being,  in  the  mean  time,  in  a rocking  motion,  which  assists  the  water  in  washing 
off  every  thing.  The  quicksilver  in  the  grooves  is  also  in  constant  motion,  by  which  the  heavy  gran- 
ules of  gold  gliding  down  on  the  bottom  are  arrested  by  it,  while  the  lighter  matters,  as  sand,  &c.,  are 
not  attracted,  and  pass  over  the  mercury.  These  machines  are  very  effective,  but  work  slow,  and 
lose  much  of  the  fine  suspended  gold.  Other  amalgamating  machines  have  recently  been  put  in  opera- 
tion ; their  efficacy  is,  however,  not  settled,  and  we  hesitate  to  describe  them  In  North  Carolina  the 
German  barrel  amalgamation  lias  been  introduced  within  a few  months,  but  we  are  not  informed  of  the 
results.  In  Virginia,  amalgamating  machines  of  novel  patterns  have  been  tried,  but  we  are  not  ac- 
quainted with  their  effects. 

All  amalgamating  machines  suffer  under  a common  evil, — they  cannot  work  all  the  water  as  it  issues 
from  the  crushing  machines  to  advantage.  In  all  instances  half  the  golden  contents  of  the  ore  are  lost. 
This  is  owing  partly  to  the  clayish  condition  of  the  ore,  which  clay  incloses  particles  of  gold  and  carries 
it  off,  and  partly  to  the  extreme  division  of  the  gold  in  the  ores  of  these  regions,  particularly  in  North 
Carolina.  This  minute  division  causes  the  gold  to  be  suspended  in  water,  and  in  that  condition  it  is 
carried  away  by  the  current.  A good  amalgamating  apparatus,  which  will  work  the  water  directly 
from  the  crushing  machines,  rub  off  clay  and  other  matter  from  file  particles  of  gold,  so  as  to  make  it 
adhere  to  the  quicksilver,  and  which  does  not  lose  any  quicksilver,  is  still  a desideratum  in  the  Southern 
gold-mining  districts. 

Gold,  gathered  by  quicksilver,  forms  a white  amalgam.  In  the  amalgamating  machines  a surplus  of 
quicksilver  is  used  to  secure  the  fluidity  of  the  mercury ; for  if  it  gets  slimy,  or  still  worse,  plastic,  like 
clay,  it  will  not  absorb  any  more  gold  with  facility.  The  fluid  amalgam  is  pressed  through  a soft 
leather  or  a piece  of  close  canvas,  to  remove  the  superfluous  mercury ; after  which  a solid  amalgam, 
called  quick,  remains  in  the  bag.  The  quicksilver  which  passes  through  the  bag  retains  always  some 
gold  in  solution,  the  quantity  of  which  varies  according  to  the  stuff  through  which  it  has  been  squeezed. 
The  amalgam  thus  obtained  contains  from  30  to  7 0 per  cent,  of  gold,  according  to  the  mode  of  working 
and  the  quality  of  the  ore.  The  quick  from  the  Chilian  mills  generally  contains  but  from  30  to  40  per 
cent,  of  gold,  while  that  from  stampers  contains  seldom  less  than  40,  and  in  most  cases  from  50  to  60 
per  cent,  of  gold.  This  circumstance  appears  to  speak  in  favor  of  the  stamps ; the  difference  in  the 
contents  of  gold,  in  the  amalgam,  is  owing  to  its  division ; the  finer  the  gold  the  less  of  it  the  amalgam 
contains.  The  dry  amalgam  is  distilled  in  an  iron  retort,  lined  with  clay ; a red  heat  will  drive  off 
tlie  mercury,  which  is  condensed  by  leading  it  into  cold  water.  The  gold  remains  in  the  retort  in  the 
form  of  a powder,  which  is  collected,  melted  in  a crucible  along  with  some  saltpetre,  and  cast  into  iron 
moulds,  forming  square  bars  of  about  one  pound  weight  each.  One  pennyweight  of  gold  of  the  Virginia 
mines  is  generally  worth  from  90  to  92  cents.  North  Carolina  gold  contains  more  silver  than  the  first, 
and  a pennyweight  is  seldom  more  than  90,  and  in  the  majority  of  cases,  from  80  to  90  cents  to  the 
pennyweight.  California  gold  ranges  from  75  to  90  cents. 

In  Virginia  and  North  Carolina  gold  ores  are  mined,  crushed,  and  amalgamated,  which  yield  but  the 
150,000th  part  of  gold  to  the  bulk  of  ore,  and  these  ores  are  worked  with  profit.  The  Russel  Mining  Co., 
in  North  Carolina,  which  operates  12  or  more  Chilian  mills,  works  ore  which  yields  10  cents  of  gold  to 
the  bushel,  or  100  pounds  of  ore,  with  profit.  The  Louisa  Mining  Co.,  which  employs  stampers  for 
crushing,  shows  that  ores  which  yield  7 cents  in  the  bushel  may  be  worked,  and  pay  expenses  and 
profit.  There  are  inexhaustible  stores  of  gold  ores  in  the  Southern  States ; it  requires  nothing  but  in- 
dustry to  make  its  production  profitable. 

Silver. — Argent,  Fr. ; silber,  Germ.;  argentum,  Lat.  Native  silver  is  frequently  found ; it  appears 
crystallized,  but  chiefly  in  irregular  concretions,  often  in  the  form  of  fine  hairs.  Generally  it  is  com- 
bined, or  alloyed,  with  gold,  quicksilver,  antimony,  arsenic.  It  appears  as  sulphuret  in  connection  with 
the  sulphurets  of  most  other  metals. 

Pure  silver  is  the  brightest  of  the  metals,  of  a beautiful  white  color  and  rich  lustre.  Its  specific 
gravity  is  1047.  It  is  a little  more  fusible  than  gold,  but  in  practice  we  find  generally  the  reverse, 
which  is  owing  to  the  alloys  of  the  two  metals,  which  have  a more  softening  influence  upon  gold  than 
upon  silver.  Silver  is  exceedingly  malleable,  but  not  so  much  as  gold ; it  crystallizes  very  readily 
when  exposed  for  some  time  to  the  influence  of  heat  in  a melted  state,  but  not  so  when  alloyed  to  other 
metals.  This  latter  quality  of  silver  has  been  made  available  in  practice,  in  refining  lead  for  silver.  If 
silver  bearing  lead  is  exposed  to  a melting  heat,  the  silver  will  not  crystallize  along  with  some  lead. 
Lead  crystallizes  more  readily  in  this  case,  and  these  crystals  may  be  removed  from  the  fluid  mass  by 
an  iron  dipper  pierced  with  small  holes.  The  crystals  of  lead,  thus  freed  from  the  largest  part  of  their 
silver,  are  melted  and  converted  into  pigs  and  sold.  After  repeated  melting  and  crystallization,  the 
remaining  fluid  is  rich  in  silver,  and  is  now  refined  in  the  common  way. 

Silver  ores  are  of  great  variety : there  is  antimonial  silver,  found  in  Mexico  and  Europe ; sulphuret 
of  silver,  almost  everywhere ; also  the  mixtures  of  sulphuret  of  silver,  with  other  metallic  sulphurets  ; 
chloride,  carbonate,  and  tellurate  of  silver  are  curiosities  of  little  practical  value.  Most  of  the  silver, 
and  in  the  United  States  exclusively,  is  derived  from  the  sulphuret  of  lead,  from  galena.  In  the  Union 
we  have  but  one  establishment  which  manufactures  silver  to  some  extent;  it  is  the  Washington  Mining 
Co.,  in  North  Carolina.  As  the  production  of  silver  from  its  ore  is  generally  conducted  on  the  same 
Vol.  II.— 20 


402 


METALLURGY. 


principles,  and  as  the  operation  at  the  Washington  mine  may  be  considered  one  of  the  most  difficult 
cases,  on  account  of  the  composition  of  its  ore,  we  will  describe  the  operation  in  this  instance. 

The  ore  at  this  establishment  consists  chiefly  of  brown  sulphuret  of  zinc,  which  is  largely  mixed  with 
galena,  copper,  and  iron  pyrites ; it  contains  silver,  gold,  and  other  metals.  The  ore  as  it  comes  from 
the  mine  is  broken  into  coarse  fragments,  and  roasted  in  heaps  in  the  open  air,  in  the  manner  described 
before.  The  roasting  is  performed  altogether  by  wood  and  wood  charcoal.  After  the  first  roasting  the 
piles  are  picked  over  for  such  ore  which  is  well  roasted,  and  that  which  is  too  much  roasted.  This  is 
brought  to  the  stampers,  crushed  into  a fine  powder,  and  washed,  so  as  to  carry  off  all  the  oxidized  zinc 
and  quartz.  If  the  ore,  after  its  being  crushed,  is  found  to  be  imperfectly  roasted,  it  is  returned  to  the  yard 
and  once  more  subjected  to  roasting.  That  part  of  the  ore  which  is  rejected  in  the  yard  is  piled  and 
roasted  along  witli  some  fresh  ore-  from  the  mine.  In  this  way  it  may  happen  that  some  of  the  ore  is 
exposed  to  several  heats.  The  roasting  operation  is  not  considered  to  be  finished  until  all  the  sulphuret 
of  zinc  is  destroyed ; that  is,  until  the  zinc  is  deprived  of  its  sulphur  and  converted  into  oxide  of  zinc,  in 
which  form  it  may  be  washed  away  by  the  water  at  the  stamping-mill. 

The  finely  powdered  ore  consists  now  chiefly  of  galena,  or,  in  case  the  roasting  operation  is  well  per- 
formed, of  oxide  of  lead,  oxide  of  iron,  oxide  of  copper,  silver,  and  other  matter.  This  ore  is  brought  to 
the  smelting-furnace,  called  a high-furnace,  and  here  smelted  along  with  some  fluxes  by  charcoal.  In 
Fig.  2818  such  a furnace  is  represented ; it  is  a solid  work  of  masonry,  calculated  to  retain  its  heat  if 
once  thoroughly  heated.  The  fire  is  urged  by  cylinder  bellows,  driven  by  a steam-engine  ; the  air  to 
the  furnace  is  supplied  at  the  tuyere  m.  In  consequence  of  the  alternate  charges  of  coal  and  ore,  the 
basin  or  hearth  g is  regularly  supplied  with  metal,  which  is  removed  at  certain  intervals  of  time,  so  as 
to  afford  room  for  fresh  met|l  and  cinder.  In  this  manner  about  one  ton  of  lead  is  obtained  in  12  hours, 
which  is  removed  and  put  aside  for  refining.  The  composition  of  the  ore,  which  makes  its  perfect 
roasting  difficult,  renders  it  necessary  to  make  large  additions  of  iron  ore  to  the  posts  of  ore.  The  iron 
oxide,  which  is  reduced  in  presence  of  carbon  in  the  furnace,  will  absorb  the  sulphur  from  the  other 
metals  in  case  there  is  any  sulphur  left  after  roasting.  This  circumstance  renders  the  operation  tedious 
and  slow.  It  cannot  be  avoided  but  by  perfect  roasting,  which  may  be  considered  practically  impossi- 
ble in  this  instance.  The  presence  of  zinc  is  what  renders  the  operation  tedious  and  expensive.  If  the 
zinc  is  not  removed  to  a large  extent,  it  will,  in  smelting  the  ore,  carry  off  by  evaporation  much  of  the 
other  metals,  gold  and  silver  not  excepted.  The  sulphurets  of  zinc  and  lead  are  very  fusible  if  in  con- 
tact. In  roasting  the  ore  these  two  sulphurets  will  invariably  melt  together,  which  causes  the  roasting 
process  to  be  either  very  expensive  or  imperfect.  All  experience  with  a similar  ore  in  other  parts  ot 
the  world  are  confirmatory  as  to  this  operation  being  expensive. 


The  lead  from  these  blast-furnaces  is  transferred  to  the  refining-furnace.  Formerly  the  English  re- 
fining-furnace was  used  as  it  is  represented  in  Fig.  2819,  in  a longitudinal  section.  Here  is  a double, 
or  two  furnaces  represented,  which,  as  is  shown,  are  reverberatory  furnaces.  The  fireplace  a throws 
the  flame  over  the  hearth  or  cupel  into  a chimney,  which  is  provided  with  a sliding  door  at  ff  to  shut 
off  the  draft  and  prevent  the  fumes  of  metal  from  escaping  through  the  stack.  The  cupel  is  formed  of 
several  layers  of  bone-ashes,  mixed  with  wood-ashes ; this  mas9  is  rammed  into  an  iron  hoop  when  in  a 
moistened  condition.  The  form  of  this  cupel  is  represented  in  Fig.  2820 ; from  above  it  is  a concave 
egg-shaped  dish,  of  about  5 inches  thick,  the  largest  diameter  being  4 feet,  the  smallest  2 feet.  When 
the  furnace  and  cupel  are  heated,  the  lead,  previously  melted  in  an  iron  pot,  is  cast  into  it ; and  now  the 
Dellows,  which  are  represented  in  Fig.  2821,  are  set  to  work,  a gentle  current  of  air  is  thrown  over  the 
not  surface.  The  action  of  the  blast  is  here  twofold  : it  oxidizes  the  lead  and  forms  litharge  of  it,  and 
drives  by  its  force  the  melted  litharge  to  the  opposite  side  of  the  blast,  or  the  tap-hole,  where  it  flows 
out  and  falls  into  an  iron  basin,  from  whence  it  is  carried  back  to  the  smelting-furnace.  The  level  of 
the  lead  is  in  this  way  gradually  reduced  if  not  kept  up  to  a certain  height ; this  is  done  by  casting  in 
melted  lead,  which  is  always  ready  melted  in  an  iron  pot.  This  process  is  carried  on  until  a certain 
quantity  of  lead  has  been  concentrated  so  far  that  a little  more  than  one  weight  of  lead  is  combined 
with  an  equal  weight  of  silver ; this  rich  lead  is  taken  out  and  refined  in  a properly  prepared  cupel. 
If  sufficient  rich  lead  is  ready  to  make  from  500  to  1000  ounces  of  silver,  it  is  refined  in  a new  cupel, 


METALLURGY. 


403 


I and  the  silver  melted  into  a cake.  The  operation  is  carried  on  as  before,  with  the  only  difference,  that 
no  fresh  lead  is  added. 

J The  Washington  mine  has  more  recently  introduced  the  German  refining-furnace  represented  in  Fig. 
2822,  with  what  success  we  are  not  aware.  This  furnace  is  larger  than  the  above  English  furnace,  the 
cupel  being  at  least  6 feet  diameter.  The  drawing  shows  a section  of  the  furnace,  in  which  the  fire- 
place y,  the  tuyeres  nn,  and  the  door  q,  into  which  the  lead  is  charged,  are  shown.  In  Fig.  2823  is  a 
ground  plan  of  the  furnace  shown.  Here  is  the  flue  x visible,  which  leads  to  the  stack,  and  which  serves 
in  the  mean  time  to  clear  off  from  the  surface  of  the  melted  lead  some  of  the  scum.  The  cupel  of  this 
furnace  is  made  entirely  of  wood-ashes,  which  are  the  refuse  ashes  from  the  soap-works,  and  in  this 
respect  the  furnace  has  an  advantage  over  the  English  furnace.  The  floor  or  hollow  surface  of  it  is  well 
pounded  by  wooden  mallets,  to  make  it  solid  and  smooth.  About  four  tons  of  lead  are  charged  for  one 
heat ; it  is  carefully  laid  upon  the  bottom,  and  at  first  gently  heated,  so  as  not  to  injure  the  fresh  bottom 


and  dome.  When  the  lead  is  melted,  and  all  ebullition  ceases,  the  blast  is  thrown  in  at  the  tuyeres  n n 
by  setting  the  bellows  at  playing  on  the  surface  of  the  melted  metal.  At  first  no  litharge  is  made,  but 
a dirty  froth  of  oxydized  metals  is  raked  off,  to  facilitate  which  formation  of  froth,  fine  charcoal  dust  is 
thrown  on  the  surface.  When  all  the  impurities  of  the  lead  are  removed  in  this  way,  the  formation 
of  litharge  begins,  which  flows  off  at  the  flue  x.  The  separation  of  the  litharge  from  the  lead  must  be 
assisted  by  a hook,  because  the  blast  is  generally  not  strong  enough  to  move  the  fluid  oxide  of  lead  over 
the  large  surface  of  the  molten  mass.  The  cupellation  of  four  tons  of  metal  lasts  from  18  to  20  hours. 
Towards  the  end  of  the  operation  some  silver  is  carried  off  with  the  litharge,  which  portion  of  litharge 
is  therefore  carefully  preserved,  to  be  remelted  by  itself  or  along  with  other  ore.  The  silver  is,  in  this 
operation,  obtained  pure  in  the  first  heat ; it  is  melted  into  the  form  of  a cake  in  a cavity  prepared  for 
its  reception  in  the  centre  of  the  hearth. 

In  all  these  refining  operations  there  is  an  inevitable  loss  of  metal,  disappearing  in  the  form  of  fumes, 
through  the  chimney.  This  loss  is  variable,  and  may  be  modified  by  the  skill  of  the  workman  and 
the  purity  of  the  lead ; it  amounts  on  an  average  to  from  4 to  7 per  cent,  of  the  lead  melted. 


2822. 


2823. 


The  extraction  of  silver  from  its  ores  by  amalgamation  is  not  practised  in  the  United  States;  this 
process  requires  rich  ores  and  cheap  quicksilver.  In  the  old  States  of  the  Union  there  is  no  prospect  of 
seeing  this  process  executed;  but  in  California,  where  rich  silver  ores  and  mercury  ores  abound,  there  may 
be  a probability  of  its  being  executed ; still  it  is  a tedious,  expensive  operation,  which,  at  the  rate  of  wages 
paid  in  the  United  States,  will  not  yield  much  profit.  Amalgamation  is  a process  not  adapted  to  our 
social  condition;  it  is  too  laborious  to  secure  success  in  ordinary  cases  of  common  or  average  ore. 
For  these  reasons  we  do  not  furnish  a description  of  this  operation.  In  our  condition  there  is  no  way  of 
working  silver  ores  profitably  but  by  smelting  the  ore  and  refining  the  lead ; or,  in  some  instances,  the 
new  process  introduced  last  year  into  European  establishments  may  answer  our  purposes. 

Some  of  the  silver  smelt-works  of  Germany  have  been  in  a condition  of  working  poor  ores,  which,  in 
many  instances,  have  not  covered  the  expenses  of  smelting  or  amalgamation,  which  must  be  extreme  cases, 
considering  German  industry  and  perseverance.  A process  has  been  introduced  within  a short  time, 
which  promises  to  advance  the  interest  of  the  metallurgy  of  silver  greatly.  The  operation  is  as  follows . 
Silver  ores  which  may  be  poor  or  contain  more  or  less  silver,  are  coarsely  broken  or  stamped,  and  then 


404 


METALLURGY. 


carried  to  a reverberatory  furnace ; here  the  ore  is  heated  to  redness,  calcined,  and  in  that  state  flora  J 
to  5 per  cent,  of  common  salt  is  added  to  the  ore ; the  whole  kept  in  that  degree  of  heat,  and  stirred  bv 
iron  bars  for  some  hours.  The  object  of  this  operation  is  to  transform  the  silver  contained  in  the  ora 
into  chloride  of  silver,  which  is  so  much  more  easy,  as  silver  has  a predominating  affinity  for  chlorine. 
If  the  operation  of  heating  is  perfected,  the  red-hot  ore  is  drawn  from  the  furnace  and  thrown  hot  into 
a boiling  concentrated  solution  of  common  salt.  The  hot  salt  solution  will  dissolve  the  chloride  of  silver, 
and  it  is  kept  in  solution  so  long  as  that  solution  is  boiling-hot ; it  is  therefore  necessary  to  filtrate  it  in 
this  condition.  To  the  hot  and  filtrated  solution  a little  muriatic  acid  is  added,  and  then  some  coarse 
pieces  of  crude  copper;  which  latter  precipitates  all  the  silver  in  a metallic  state,  in  the  form  of  a fine 
powder  ; this  is  gathered  and  melted  in  a crucible  ; it  is  pure  silver.  This  process  is,  to  all  appearances, 
simple,  and  is  in  fact  so ; but  it  requires  an  expert  chemist  to  execute  the  operation.  If  there  is  only 
copper,  iron,  and  silver  present  in  the  ore,  the  operation  is  simple ; but  if  there  is  gold,  lead,  or  quick- 
silver in  the  ore,  the  case  is  not  so  easily  managed ; for  the  gold  will  not  pass  with  the  silver  into  the 
solution,  and  the  chlorides  of  lead  and  quicksilver,  which  are  soluble  in  the  same  manner  as  chloride  of 
silver,  are  precipitated  by  the  same  means.  The  application  of  this  process  to  our  Southern  ores  is 
difficult,  but  it  may  be  an  extremely  useful  process  in  applying  it  to  the  argentiferous  stamp-work  of 
the  Lake  Superior  copper  ores. 

The  silver  ores  of  the  Southern  gold  region,  such  as  are  smelted  at  the  "Washington  mines,  yield  from 
200  ounces  to  300  ounces  of  silver  in  a ton  of  lead  ; the  ore  itself  contains  on  an  average  8 per  cent,  of 
lead ; the  other  matter  is  zinc,  iron,  copper,  tin,  and  chiefly  sulphur.  The  silver  is  worth  §1.80  the 
ounce,  because  it  is  alloyed  with  a large  portion  of  gold,  which  raises  its  value  to  double  the  value  of 
pure  silver. 

Copper. — Germ.  Kupfer;  Fr.  Cuivre;  Lat.  Cuprum.  Copper  was  known  to  the  ancients  long  before 
iron ; most  of  the  metallic  instruments  of  the  era  preceding  ours  were  made  of  copper,  alloyed  with 
tin  and  other  metals.  The  ancient  nations  on  the  old  continent,  as  well  as  the  inhabitants  of  America 
before  European  invasion,  understood  the  art  of  hardening  copper  as  well  as  we  now  understand 
hardening  steel.  This  art  is  now  lost,  and  we  doubt  its  utility  if  it  were  recovered.  Copper  is  pro- 
fusely distributed  all  over  the  globe;  its  ores  are  found  everywhere.  Native  copper  is  particularly 
found  in  this  country  and  in  Russia.  The  ores  of  copper  are  chiefly  sulphurets,  of  which  the  yellow 
sulphuret,  or  copper  pyrites,  forms  nine-tenths  of  all  the  ore  used  in  the  smelt-works.  Besides  this 
ore,  there  is  the  gray  sulphuret ; there  are  carbonates,  arseniates,  phosphates,  silicates,  oxides  of  cop- 
per, and  others ; all  these  ores  are  of  more  interest  to  the  mineralogist  than  to  the  metallurgist.  The 
bulk  of  ore,  particularly  in  this  country,  are  the  yellow  pyrites ; besides  which,  the  native  copper  forms 
an  important  source  of  metal  to  the  smelter.  The  whole  amount  of  copper  produced  in  the  world  an- 
nually is  about  33,000  tons,  of  which  Europe  produces  25,000  tons  ; the  rest  is  American  copper.  ■* 

In  the  United  States  there  are  four  large  copper  smelt-works,  and  some  smaller.  At  Boston,  New 
York,  Baltimore,  and  Pittsburg  are  smelt-works,  working  on  the  English  plan;  smaller  furnaces  are  in 
Missouri,  Wisconsin,  and  Michigan.  At  present  most  of  the  smelt-works  are  stopped  for  want  of  ore. 
If  all  the  furnaces  in  the  Union  could  be  kept  in  operation,  we  should  produce  more  copper  than  we 
want,  and  have  some  for  export ; for  the  smelt-works  have  a capacity  of  18,000  tons.  The  works  along 
the  Atlantic  coast  depend  chiefly  upon  ores  from  Cuba ; Pittsburg  and  Boston  are  supplied  from  Lake 
Superior.  All  the  States  along  the  Atlantic  coast  furnish  copper  ores,  but  there  must  be  causes  which 
prevent  a regular  supply  to  the  smelt-works.  Our  ores  are  not  particularly  rich,  still  there  are  mines 
in  New  Jersey,  Pennsylvania,  Virginia,  and  all  the  Southern  States,  which  will  pay  handsomely  if  car- 
ried on  properly.  There  is  a deposit  of  native  copper  in  Virginia  which  will  furnish  stamp-work 
equal  to  Lake  Superior.  The  chief  difficulty  in  our  copper-mining  business  is,  that  some  of  these  mines 
have  been  carried  on  by  ignorant  persons  ; in  other  cases,  swindlers  have  abused  the  confidence  of  the 
community.  If  copper-mining  in  either  of  the  Atlantic  States  is  carried  on  with  discrimination,  indus- 
try, and  not  over-sanguine  expectations,  there  is  no  doubt  as  to  its  being  a safe  and  paying  business. 
Many  of  our  copper  mines  would  be,  and  could  be  carried  on  by  farmers,  or  the  owners  of  the  soil,  it 
their  knowledge  of  mining  and  preparation  or  concentration  of  the  ore  were  sufficient  to  make  the  opera- 
tion profitable.  In  these  respects  the  smelt-works  can  assist  a great  deal  in  developing  the  resources  of 
the  country,  if  they  will  furnish  such  instructions  to  the  owners  of  the  mines  as  will  facilitate  their 
operation;  for  it  must  be  presumed  the  smelt- works  are  more  qualified  to  furnish  practical  information 
on  that  subject  than  any  other  person  or  persons  can  do.  Ores  do  not  come  now  on  consignment,  be- 
cause the  owner  of  the  ore  does  not  like  to  run  the  risk  of  a sale  which  appears  to  him  arbitrary.  Our 
Atlantic  smelt-works  have  to  exert  themselves  in  developing  the  sources  of  ore,  and  export  copper,  or 
they  are  to  stop  operations.  Lake  Superior  promises  to  furnish  6000  tons  of  copper  this  year;  this 
will  supply  nearly  the  demand  of  the  Union  ; there  is,  therefore,  little  or  no  choice  for  the  Atlantic 
works,  but  to  smelt  for  export.  Here  are  means,  that  is,  ore  and  fuel,  to  go  into  competition  with  Eu- 
rope : it  requires  some  industry  to  make  these  means  available. 

The  smelting  of  copper  ores  in  all  of  our  smelt-works  is  carried  on  in  furnaces  resembling  the  English 
furnaces  at  Swansea.  The  operation  of  smelting  is  also  similar  to  the  English  process,  all  of  which 
elaborate  descriptions  are  furnished  in  Ure’s  Dictionary  of  Manufactures  and  Mines.  The  operation  ot 
smelting  is  divided  chiefly  into  preparing,  or  washing  and  crushing  of  the  ore,  calcining,  smelting  and 
refining.  The  washing  of  these  ores  is  performed  at  the  mines,  and  also  the  crushing  or  concentration, 
and  does  not  differ  from  similar  operations  performed  on  other  ores.  The  furnaces  used  in  the  various 
operations  at  the  smelt-works  are  all  of  the  reverberatory  kind,  and  fired  by  bituminous  coal,  or  by 
vTood.  Fig.  2824  shows  a calcining-furnace  in  elevation,  Fig.  2825  the  same  furnace  in  section,  and 
Fig.  2827  shows  the  ground-plan  of  the  furnace.  A is  the  fire-place,  B is  the  hearth,  C an  arch  into 
which  the  ore  is  drawn  ; E E are  stationary  hoppers,  or  feeders,  and  b bbb  four  work-doors.  The  ore 
in  this  calcining  operation  is  not  fused  ; it  is  heated  merely  to  such  a degree  of  heat  as  will  evaporate 
sulphur  and  arsenic,  and  oxidize  the  metallic  ores.  These  calcined  ores  are  exposed  to  a second  heat, 


METALLURGY. 


405 


Either  in  the  same  furnace,  or,  as  in  most  cases,  in  a separate  or  smelting-furnace.  Such  a furnace  is 
represented  in  Figs.  2832,  2833,  showing  the  plan  and  section  of  it ; here  A B is  the  hearth,  0 the  fire- 
place, L the  hopper,  and  K M a receiving-pot  filled  with  water,  in  which  the  copper  is  granulated.  In 
the  second  operation,  or  smelting,  some  copper  is  produced  along  with  the  matt  or  slag,  which  is  sep- 
arated and  treated  in  a peculiar  way.  The  matt,  which  contains  but  little  copper,  is  returned  to  the  cal- 
cined ore,  'and  smelted  along  with  it.  In  this  operation  fluxes  are  added  in  case  the  ore  does  not  con- 
tain sufficient  flux  for  smelting.  Iron  forms  the  best  flux,  and  for  these  reasons  : copper  pyrites,  which 
always  contain  more  or  less  iron  pyrites,  are  the  most  profitable  ores  in  the  smelting  operation.  Other 
fluxes  are  the  metallic  oxides  of  manganese,  lead  and  tin,  besides  which,  lime,  fluor-spar,  or  other  fluxes 
are  used. 


The  copper  obtained  in  the  first  smelting  operation  is  impure,  and  classes  not  higher  than  a rich  matt 
er  melted  ore ; its  granules  consist  of  copper,  iron,  sulphur,  &c.  This  matt  or  coarse  metal  is  once 
more  calcined  in  the  calcining-furnace,  and  then  subjected  to  another  smelting,  by  which  operation  a 
more  refined  metal  is  obtained.  The  latter  product  is,  however,  not  yet  fine  copper  ; it  is  matt,  which 
contains  60  per  cent,  of  copper  ; it  is  granulated  and  roasted  as  before,  and  once  more  smelted,  by 
which  a richer  matt  is  obtained.  These  alternate  operations  of  roasting  and  smelting  are  repeated 
from  seven  to  eight  times  before  fine  copper  is  obtained.  The  cause  of  this  delay,  or  repetition  of  cal- 
cining, is  found  in  the  great  affinity  of  copper  for  sulphur  and  arsenic,  which  it  requires  repeated  fire 
and  cooling  to  expel  successfully. 

The  refining  of  copper  is  done  in  the  smelting-furnace,  or  a refining-furnace  kept  for  the  purpose. 
The  melting  of  the  pigs  is  conducted  slowly,  so  as  to  calcine  the  copper,  in  case  any  impurities  are  left 
in  the  fine  copper.  When  the  copper  is  melted,  its  surface  is  covered  by  finely  broken  charcoal,  which 
operation  is  repeated  as  the  charcoal  consumes.  This  refining  process  lasts  for  20  hours,  and  longer, 
for  one  heat  of  from  8 to  9 tons,  after  which  time  the  copper  is  ladled  out  by  means  of  iron  ladles 
coated  with  clay. 

The  Germans,  and  all  other  European  nations,  also  the  new  copper  smelt-works  in  Baltimore, 
smelt  their  copper  ores  in  furnaces  similar  to  those  represented  in  Figs.  2828  to  2831.  The  opera- 
tion is  similar  to  that  of  smelting  lead,  silver,  or  iron  ores.  In  these  furnaces,  which  are  about  15  feet 
high,  and  3 feet  wide,  are  two  tuyeres  C C,  and  a cinder  tap-hole  in  the  line  G II.  The  copper  is  tapped 
into  the  basin  i,  where  it  is  chilled  on  the  surface  and  forms  rosettes,  or  it  is  cast  into  pigs  for  refining. 
The  latter  process  is  performed  in  reverberatory  furnaces,  similar  to  those  described. 

The  native  copper  occurring  at  Lake  Superior,  in  Virginia,  and  elsewhere,  contains  a large  portion  of 
silver,  which  at  present  is  lost;  to  extract  this  silver  by  liquation  is  expensive,  and  injurious  to  the 
quality  of  the  metal ; to  do  it  by  amalgamation  is  expensive,  and  hardly  would  pay  the  trouble.  There 
are,  however,  ores  which  contain  more  than  one  per  cent,  of  silver  to  the  copper,  and  we  may  assume 
the  whole  body  of  copper  contains  the  half  of  one  per  cent.;  this  would  amount,  on  the  6000  tons  of 
Lake  Superior  copper  to-  be  furnished  this  year,  to  at  least  If 60,000  worth  of  silver,  which  silver  is  now 
entirely  lost.  We  recommend  for  the  extraction  of  this  silver  the  process  alluded  to  above. 

Copper  is  one  of  the  most  useful  metals,  particularly  in  its  alloys  with  tin,  zinc,  and  other  metals. 
The  native  metal  is  frequently  found  to  be  crystallized  in  concrete,  irregular  masses,  ramifying  the  rock 
in  which  it  is  found  •,  it  is  also  found  in  grains,  disseminated  through  the  rock.  It  is  less  fusible  than 
silver,  of  a specific  gravity  of  8'94.  It  is  highly  tenacious,  and  its  fracture  fibrous. 

Lead. — Germ.  Blei;  Fr.  Plomb  ; Lat.  Plumbum.  This  metal  is,  like  gold,  silver,  and  copper,  known 
since  time  immemorial.  It  is  one  of  the  metals  the  most  easily  obtained  from  its  ores.  The  chief  ore 
from  which  lead  is  smelted  is  galena  or  sulphuret  of  lead,  which  contains  when  pure  86'66  parts  of 
metal,  and  the  remainder  sulphur.  The  United  States  and  Spain  are  at  present  the  contending  parties 
in  the  lead  market,  and  there  is  a prospect  of  our  final  supremacy.  The  amount  of  lead  manufactured 
throughout  the  world  may  be  about  100,000  tons  annually,  of  which  our  Mississippi  lead  region  fur- 
nished last  year  20,000  tons,  Spain  31,000  tons,  and  England  39,000  tons. 

The  metallurgy  of  lead  is  very  simple,  particularly  in  this  country,  where  an  abundance  of  good 
galena  is  found,  as  in  Missouri,  Iowa,  Illinois,  Arkansas,  Virginia,  California,  and  more  or  less  in  all  the 
States  of  the  Union.  Very  little  or  no  lead  is  smelted  from  other  ores  but  galena.  In  the  Northwest- 
ern States,  Illinois,  Wisconsin,  and  Missouri,  are  the  principal  lead  smelt-works ; the  operation  as  it 
is  conducted  in  these  places  is  very  much  the  same  as  in  other  parts  of  the  Union. 

Lead  is  smelted  in  the  above-named  States  in  reverberatory  furnaces  and  in  blast-furnaces.  Tha 
reverberatory  furnaces  resemble,  those  in  which  copper  is  smelted,  of  which  Figs.  2832,  2833,  si  ow  a 


406 


METALLURGY. 


vertical  and  horizontal  section.  About  one  ton  of  ore,  along  with  one  ton  of  slag  from  the  previous 
heats,  forms  one  charge.  The  whole  is  thoroughly  heated  by  closed  doors  and  suffocated  combustion, 
so  as  to  produce  carbonic  oxide  gas  in  the  furnace,  for  reducing  as  much  lead  from  the  slags  and  ore  as 
possible.  When  in  this  way  most  of  the  lead  is  extracted,  the  doors  of  the  furnace  are  opened,  more 
heat  is  given,  and  the  mass,  ore  and  slags,  thoroughly  melted,  with  the  addition  of  some  pure  quick- 
lime, which  is  occasionally  thrown  into  the  melting  mass,  and  well  stirred  along  with  the  ore.  Most  o! 
the  lead  is  yielded  by  the  ore  in  this  operation,  still  there  is  more  than  25  per  cent,  of  it  lost  in  the 
slags ; these  are  resmelted  in  a blast-furnace.  Reverberatory  furnaces  are  heated  by  dry  wood,  and 
produce  in  24  hours  from  three  to  four  tons  of  metal. 


282s.  283'). 


2832. 


More  general  than  the  foregoing  are  the  blast-furnaces  for  smelting  lead.  These  are  furnaces  resem 
oling  a cupola  in  which  iron  is  smelted,  more  than  any  thing  else ; they  are  generally  built  in  a rough 
manner  in  appearance,  but  the  inside  of  the  furnace  coincides  with  a cupola ; it  is  generally  from  six  to 
eight  feet  high  ; the  blast  is  introduced  by  the  nozzle  h to  the  tuyere  y.  The  lead,  in  gathering  in  the 
bottom  f is  frequently  tapped,  so  as  to  have  but  little  metal  in  the  furnace  at  a time.  The  cinder,  or 
slag,  is  kept  as  high  as  the  tuyere,  and  if  it  reaches  too  high  some  of  it  is  tapped  at  a tap-hole  in  the 
front  of  the  furnace.  One  blast-furnace  will  produce  in  24  hours  about  two  tons  of  lead,  for  which  it 
consumes  6000  lbs.  of  galena,  25  bushels  of  charcoal,  and  about  a quarter  of  a cord  of  wood.  In  this 
operation,  as  in  the  reverberatory,  a great  deal  of  metal  is  lost,  which  in  most  cases  amounts  to  20  per 
cent,  or  more.  The  slags  contain  most  of  this  loss,  still  a large  portion  of  it  is  destroyed  by  evapora- 
tion. The  blast-furnace  has  the  advantage  over  the  reverberatory  so  far  as  regards  economy,  but  it 
does  not  furnish  so  much  metal  in  the  same  time  as  the  latter. 

The  slags  from  the  blast-furnace,  the  reverberatory,  and  the  slags  from  the  old  Scotch  furnaces,  now 
no  longer  in  use,  are  gathered,  broken  into  coarse  lumps  of  about  two  inches,  and  are  then  subjected 
to  another  smelting  in  the  slag-furnace.  The  slag-furnace  is  similar  to  the  above  blast-furnace,  but  it 
is  lower ; its  extreme  height  is  only  four  feet,  and  in  many  instances  it  is  only  three  feet  high.  The  slags 
are  here  smelted  by  charcoal,  with  the  addition  of  some  lime  and  iron  ore,  by  which  about  two-thirds 
of  the  lead  contained  in  the  slags  is  obtained ; one-third  of  the  metal  in  the  slags,  or  10  per  cent,  of  the 
ore,  is  therefore  irrecoverably  lost.  These  furnaces  are  the  same  in  principle  as  that  represented  in  the 
above  drawing ; the  work  in  it  differs  somewhat  from  the  smelting  of  ore.  The  lead  and  slags  flow 
here  continually,  the  first  into  a basin  nearest  the  tap-hole  in  which  it  gathers ; the  latter  flows  from 
this  basin  into  a somewhat  distant  reservoir  of  water,  where  it  is  cooled  and  thrown  away.  A slag- 
furnace  will  smelt  in  24  hours  about  two  tons  of  metal;  this,  however,  depends  upon  the  richness  of 
the  slags  ; it  will  make  more  if  the  slags  are  rich,  and  will  make  less  if  poor. 

The  conditions  of  the  lead  business  are  not  very  encouraging  at  present ; the  profits  are  so  small  that 
the  smelting  of  lead  is  reduced  to  an  occupation  which  hardly  pays  the  trouble  of  carrying  it  on.  If  an 
Illinois  smelter,  who  carries  on  one  furnace,  can  make  ten  dollars  a day,  he  does  very  well.  When  we 
consider  the  risk  of  bad  debts,  accidents,  and  stoppages  for  want  of  ore  or  hands,  we  find  that  the 
smelting  of  lead  pays  worse  than  any  other  trade. 

Zinc. — This  metal  was  known  to  the  ancients,  who  melted  oxide  of  zinc,  called  galmei  by  the  Ger- 
mans, together  with  copper,  and  formed  brass  of  it.  A similar  process  is  performed  with  the  red  oxide 
of  zinc  in  New  Jersey.  The  Chinese  have  known  this  process  longer  than  historical  reports  reach.  The 
most  abundant  ores  of  zinc  are  the  sulpliurets,  blende ; these  are  found  in  Virginia  and  North  Carolina 


METALLURGY. 


407 


m inexhaustible  quantities,  along  with  galena,  silver,  and  the  sulphurets  of  iron  and  copper.  Anothej 
ore  is  the  oxide  of  zinc,  calamine,  which  is  combined  with  carbonic  acid,  or  silex,  or  both  of  these  mat- 
ters. Large  deposits  of  this  kind  of  ore  are  found  in  New  Jersey,  Pennsylvania,  and  some  of  it  along 
the  northwestern  lakes. 

Zinc  is  a brittle  metal,  of  a bluish  white  color  and  considerable  lustre  ; it  is  soon  tarnished  with  an 
insoluble  coating  of  protoxide  of  zinc.  Its  fracture  is  crystalline  and  short,  and  its  malleability  not 
remarkable.  American  zinc,  manufactured  by  the  New  Jersey  Company,  is  remarkable  for  its  tenacity. 
Fine  wires  may  be  drawn  of  it,  which  possess  great  strength,  a beautiful  silvery  lustre,  and  fine  ap- 
pearance. The  specific  gravity  of  zinc  is  6'9  to  7'3  ; it  melts  at  about  700°,  and  soon  burns  with  a 
bluish-white  light,  forming  bright  white  flowers  of  zinc,  a flocculent  matter  resembling  cotton-wool,  or 
snow-flakes — it  is  oxide  of  zinc. 

In  the  United  States  not  much  zinc  is  manufactured  in  its  metallic  state  at  present ; the  low  price 
of  the  European  zinc  will  not  admit  of  working  our  own  ores.  Some  zinc  is  manufactured  in  New 
Jersey,  but  the  quantity  is  small  in  comparison  to  that  imported.  Considerable  use,  however,  is  made 
of  the  red  oxide  for  the  manufacture  of  brass.  An  important  business  could  be  done  in  the  Southern 
States  by  working  the  silver  blende  for  zinc,  and  extracting  the  silver  in  the  mean  time,  either  before  or 
after  the  zinc  is  manufactured  from  it.  The  Silesian  process  of  working  zinc  ore  is  the  best  adapted  for 
working  this  kind  of  ore,  for  which  reason  we  shall  describe  this  operation  in  preference  to  other  pro- 
cesses. 

The  ore,  in  this  operation,  is  roasted  in  a reverberatory  furnace,  similar  to  that  in  which  copper  ores 
are  roasted,  and  which  have  been  represented  before.  After  the  ore  is  well  roasted,  which  operation  is 
tedious  on  sulphurets,  it  is  mixed  with  an  equal  volume  of  culm,  that  is,  bituminous  coal-slack,  and 
some  small  charcoal,  in  case  the  ore  is  fine,  to  make  the  mixture  porous.  The  roasted  ore,  well  mixed 
with  its  ingredients,  is  now  introduced  in  lots  of  50  pounds  of  ore  into  a muffle,  which  is  carefully  made 
of  good  fire-clay,  such  clay  as  fire-bricks  are  made  of- — the  Mt.  Savage,  Maryland,  and  Johnstown,  Pa., 
clay  is,  for  this  purpose,  the  best.  Muffles  are  round  pipes ; they  must  be  slowly  dried,  and  are  then 
baked  in  a particular  furnace.  They  are,  when  red  hot,  inserted  into  the  reducing-furnace,  which  is  a 
reverberatory,  shown  in  section  in  Fig.  2834,  and  in  plan  in  Fig.  2835.  A range  of  muffles  is  laid  on  tlio 


2835. 


hearth,  a , of  the  furnace,  reaching  to  the  fire-bridge,  b,  their  mouth  extending  to  c.  The  muffles  are 
closed  by  a clay  slab  at  the  mouth,  in  which  there  are  two  openings,  one  at  the  bottom  for  the  charge  and 
discharge  of  the  ore,  and  one  at  the  top  for  inserting  an  iron  pipe  which  is  to  conduct  the  vapors  of  the 
distilled  zinc  to  the  condensing  vessel.  The  vapors  of  zinc  are  conducted  into  cold  water,  in  which  it 
condenses  and  forms  grains ; these  are  afterwards  remelted  in  an  iron  pot.  One  reverberatory  contains 
five  muffles,  and  a double  furnace  ten.  To  produce  one  ton  of  metal,  10,  and  from  that  to  12,  tons  of 
bituminous  coal  are  consumed,  and  one  muffle  will  last  for  making  nearly  one  ton  and  a half  of  zinc. 

Zinc  is  a useful  metal,  if  it  can  be  obtained  at  reasonable  prices ; it  is  indispensable  in  the  chemical 
laboratory,  and  is  very  useful  in  architecture  for  roofing  and  for  ornaments.  Its  most  important  appli- 
cation is,  however,  in  combination  with  copper,  as  brass,  of  which  a great  variety  of  shades  of  the  yellow 
color  are  produced. 

. Mercury.' — Syn .,  quicksilver : Germ.,  quecksilber ; Lat.,  hydrargyrum;  has  been  known  from  early 
historical  times.  The  most  important  mines  used  to  be,  and  are  still,  in  Spain  ; besides  which,  mercury 
is  made  in  Idria  and  Western  Germany,  in  Mexico  and  California.  This  subject  is  of  more  import- 
ance to  the  United  States,  since  the  acquisition  of  California,  than  it  was  previous  to  that  time;  not 
only  in  respect  to  the  manufacture  of  the  metal  itself,  but  in  its  relation  to  the  gold  and  silver  ores. 
The  quicksilver  mines  of  California  had  been  worked  before  its  annexation,  but  these  mines  never  at- 
tracted so  much  attention  as  they  have  done  since  that  country  became  a part  of  the  Union.  The  principal 
nines  in  California  are  the  Guadalupe  and  the  New  Almadan  mines,  which  are  some  miles  distant  from 
each  other,  and  not  far  in  the  interior  of  the  country.  The  ore  in  these  places  is  a beautiful  sulphuret, 
cinnabar,  of  a bright,  fiery-red  color,  and  yields  from  60  to  70  per  cent,  of  mercury.  The  successful 
operation  of  these  mines,  and  a reduction  of  the  price  of  quicksilver  in  consequence,  is  an  important- 
object  to  the  silver  mines  of  California,  Mexico,  and,  in  fact,  to  all  the  silver  mines  along  the  Pacific 
coast. 

Ihe  extraction  of  quicksilver  from  its  ores  is  a very  simple  operation;  but,  as  economy  is  desirable  in 
all  operations  of  this  kind,  we  will  describe  the  most  perfect  apparatus  invented  for  this  kind  of  work— 
if  is  that  constructed  by  Dr.  Andrew  Ure  for  a European  establishment  of  this  kind. 


2834. 


408 


METALLURGY. 


Fig.  2836  shows  a section  of  a furnace  parallel  with  the  front  elevation  represented  in  Fig.  2837 
1 a a are  iron  retorts;  the  whole  furnace  contains  9 of  them.  I is  the  fireplace,  designed  either  foi 
coal  or  wood.  The  upper  retort  is  protected  against  the  direct  contact  of  the  flame  by  fire-bricks.  K K 


2836. 


shows  the  flues  for  the  escape  of  the  burnt  gases.  The  whole  arrangement  is  shown  in  Fig.  2838  very 
distinctly.  The  two  ends  of  the  retort,  a,  are  shut  by  two  iron  lids,  secured  by  cross-bars  and  screw- 
bolts,  luted  with  clay.  The  one  end  of  the  retort  is  provided  with  an  iron  pipe  b,  which  leads  into  a long 

2837. 


condenser  e,  and  from  thence  into  the  receiver  D,  e.  The  hole  L is  designed  for  the  introduction  of  an 
iron  wire,  in  case  any  disturbance  should  happen  in  the  pipe  A,  where  dirt  from  the  ore  may  accumulate 
and  obstruct  the  passage  of  the  mercury  vapors.  The  pipe, 
c,  is  always  partly  filled  with  quicksilver,  and  kept  cool  by 
water  contained  in  a trough  which  surrounds  it. 

The  retorts  are  kept  in  constant  ignition,  and  a charge  is 
worked  in  three  hours’  time,  each  charge  consisting  of  5 
cwts.  of  ore.  The  ore  is  finely  broken,  and  mixed  with  a 
portion  of  quicklime  or  porous  magnetic  iron  ore,  and,  if  it 
can  be  had,  with  both  mixed  together.  The  quantity  of 
lime  or  iron  depends  upon  the  quality  of  the  ore ; pure  ore 
requires  more  of  it  than  impure  ore.  The  quantity  of 
quicksilver  made  in  one  retort  per  day  depends  also  on  the 
richness  of  the  ore  : the  California  ore  ought  to  produce  at 
least  600  lbs.  in  24  hours  in  one  retort,  which  will  be  for  9 
retorts  nearly  2 tons  and  a half  per  day.  The  retorts  are 
charged  and  discharged  from  behind,  so  as  to  leave  the  con- 
densing apparatus  undisturbed. 

Tin. — Germ.,  zinn  ; Ft.,  etain  ; Lat.,  stannum.  Tin  has 
been  known  for  ages,  and  was  used  by  the  ancients  long 
before  our  era.  Tin  ore  is  found  chiefly  as  an  oxide  of  tin  : 
it  is,  in  fact,  the  only  available  ore.  England,  Germany,  and  the  East  Indies,  furnish  almost  all  the 
tin  in  market — some  is  brought  from  South  America,  but  it  is  of  an  inferior  quality.  In  the  United 
States  tin  ore  is  found  in  Connecticut,  and  there  is  said  to  be  a good  deposit  in  Missouri ; a small  quan- 
tity is  found  in  the  silver  ores  of  the  Southern  States.  Tin  is  a beautiful  metal,  and,  next  to  silver,  the 
whitest  of  all  the  metals.  Its  specific  gravity  is  7'29.  It  is  a little  harder  than  lead,  and  emits  a pe- 
culiar sound,  tin-cry,  when  bent,  but  the  addition  of  a small  quantity  of  lead  diminishes  the  strength  oi 
that  sound.  Tin  is  more  fusible  than  lead ; it  melts  at  440°.  It  is  very  volatile,  and  burns  in  open 
fire,  forming  oxide  of  tin,  or  putty  of  tin.  The  most  extensive  use  of  tin  is  in  the  manufacture  of  tin 
plate,  for  which  purpose  a very  pure  tin  is  required ; it  is  further  employed  for  making  pewter,  bronze, 
bell-metal,  &c.,  for  which  purpose  it  is  alloyed  with  other  metals,  such  as  lead  and  copper. 

The  metallurgy  of  tin  is  simple,  but  it  requires  experience  to  succeed  well  ic  smelting.  The  ores  are 


MICROMETER. 


400 


first  concentrated  by  stamping  and  washing,  which  is  so  much  the  more  easy  as  tin  ores  are  of  a high 
specific  gravity,  almost  equal  to  galena.  The  roasting  is  invariably  performed  in  a reverberatory  fur- 
nace, which  is  a tedious  operation,  and  requires  from  18  to  20  hours  work  for  one  heat;  if  this  operation 
is  not  well  performed,  much  trouble  and  loss  is  met  with  in  smelting.  Tin  is  the  most  profitably  smelt- 
ed in  a blast-furnace,  such  as  copper  or  silver  ores  are  smelted  in.  In  England,  the  reverberatory  is 
employed  for  smelting  some  kinds  of  ore,  but  the  best  metal  is  made  in  the  first  furnace.  The  charges 
in  the  blast-furnace  consist  in  charcoal  ore,  and  lime,  lead  ore  or  iron  ore  as  fluxes.  In  the  reverbera- 
tory, the  ore  is  charged  along  with  lime,  and  culm,  or  mineral  coal  slack,  as  the  means  of  reduction.  At 
the  tap-hole  of  the  furnace  a receiving  basin  is  moulded,  into  which  the  fluid  metal  is  tapped  at  certain 
intervals,  the  fluid  slag  being  conducted  to  some  other  reservoir  and  gathered,  to  be  smelted  once 
more. 

Tin,  directly  from  the  smelting  furnace,  is  always  impure.  It  contains  all  the  metals  with  which  the 
ores  are  adulterated,  and  it  absorbs,  also,  metals  from  the  flux.  The  metal  is  refined  in  a reverberatory 
furnace  by  eliquation,  which  process  is  based  upon  the  ready  fusibility  of  tin.  In  charging  the  blocks  of 
tin  near  the  fire-bridge,  the  hearth  being  sloped  towards  the  flue,  a gentle  heat  will  melt  the  tin  first  cf 
all  other  metals,  and  it  will  flow  down  the  hearth,  leaving  the  other  metals  in  the  form  of  skeletons  of 
the  original  blocks.  The  pure  metal  is  removed  by  tapping  it  at  the  flue,  and  then  the  heat  increased 
and  the  other  metals  melted  down  : these  are  kept  separate.  The  tin  thus  obtained  is  once  more  sub- 
jected to  refining,  for  which  purpose  it  is  melted  in  an  iron  kettle,  and  stirred  with  sticks  of  green  wood. 
The  steam  emitted  from  that  wood  oxidizes  all  other  metals,  and  purifies  the  tin  from  them ; the  former 
form  a light  scum  on  its  surface,  which  is  removed,  and  the  metal  cast  in  blocks  ; it  is  now  ready  for 
the  market.  The  whole  amount  of  tin  manufactured  in  the  world  may  be  estimated  at  about  10,000 
tons,  of  which  England  furnishes  the  one  half. 

MICROMETER.  An  instrument  applied  to  telescopes  and  microscopes  for  measuring  very  small 
distances,  or  the  diameters  of  objects  which  subtend  very  small  angles.  A great  number  of  contrivances 
of  various  kinds,  and  depending  on  different  principles,  have  been  employed  for  this  purpose  ; but  it 
will  be  sufficient  to  give  a general  description  of  some  of  the  most  useful  or  remarkable  ones. 

Wire  micrometer. — This  instrument,  when  placed  in  the  tube  of  a telescope,  at  the  focus  of  the  object 
glass,  presents  the  appearance  represented  in  Fig.  2839.  A a is  a spider’s  web  line,  or  very  fine  wire 
fixed  to  the  diaphragm ; and  B b and  C c are  similar  wires  stretched  across  two  forks,  each  connected 
with  a milled-headed  screw.  By  means  of  these  screws  the  two  wires,  B b and 
C c,  which  are  exactly  parallel  to  each  other,  are  movable  in  the  direction  per- 
pendicular to  A a-  and  in  order  that  the  wire  A a may  be  placed  in  any  direc- 
tion relatively  to  the  meridian,  there  is  an  adjusting  screw,  which  works  into  an 
interior  toothed  wheel,  and  turns  the  apparatus  round  in  its  own  plane  perpen- 
dicular to  the  axis  of  the  telescope. 

The  method  of  using  the  micrometer  is  as  follows:  Suppose  the  object  to  be 
accomplished  were  the  measurement  of  the  angle  of  position  and  distance  of  two 
very  close  stars  ; the  telescope  being  set  and  kept  on  the  objects,  the  microme- 
ter is  turned  by  its  adjusting  screw  until  the  spider  line  A a coincides  with  the 
line  joining  the  two  stars,  or  threads  them  both  at  the  same  moment.  The 
milled  heads  of  the  screws,  which  carry  the  two  movable  wires,  are  then  turned 
until  B b bisects  one  of  the  two  stars,  and  C c bisects  the  other.  The  observation  is  now  completed,  and 
it  only  remains  to  ascertain  the  position  and  distance  indicated  by  the  micrometer.  For  the  first  of 
these  purposes,  the  circumference  of  the  micrometer  is  divided  into  degrees  and  minutes,  and  read  by 
two  verniers  : this  reading  gives  the  position  of  A a in  respect  of  the  horizontal  and  vertical  planes,  and 
consequently  the  angle  of  position  of  the  two  stars.  To  find  their  distance,  the  head  of  the  screw  which 
carries  one  of  the  movable  wires,  for  instance  C c,  is  turned  until  0 c coincides  with  B b ; and  the  num- 
ber of  revolutions,  and  parts  of  a revolution,  required  to  effect  the  coincidence,  gives  the  distance  of  the 
stars  when  the  value  of  the  scale  of  the  micrometer  is  known  ; that  is  to  say,  when  the  number  of  sec- 
onds of  space  which  correspond  to  one  revolution  of  the  screw  is  known.  The  screws  must  be  made 
with  great  accuracy,  and  their  heads  are  usually  divided  into  60  equal  parts,  representing  seconds. 

The  value  of  the  scale,  or  of  a revolution  of  the  screw,  is  obtained  in  the  following  manner  : Set  the 
two  wires,  B b and  0 c,  apart  to  a certain  number  of  revolutions,  and  place  them  in  the  direction  of  the 
meridian.  Observe  the  transits  of  several  stars  of  known  declination  over  the  wires ; then  multiply 
each  interval  of  seconds  by  15,  and  by  the  cosine  of  the  star’s  declination;  and,  taking  the  mean,  you 
have  the  seconds  of  space  which  correspond  to  a known  number  of  revolutions  of  the  screw. 

Circular  Micrometer. — This  instrument,  which  differs  entirely  from  the  above,  was  first  suggested  by 
Boscovich,  in  the  Leipzic  Acts  for  1140,  and  used  by  Lacaille  in  observing  a comet  in  1742  ; but  seems 
afterwards  to  have  fallen  into  disuse  until  it  was  revived  by  Dr.  Olbers  about  1798.  The  principle  may 
be  explained  as  follows : If  the  field  of  a telescope  be  perfectly  circular,  (which  may  be  effected  by 
means  of  a diaphragm  turned  in  a lathe,)  and  if  its  diameter  be  determined  from  observation,  the  paths 
of  two  celestial  bodies  across  the  field  may  be  considered  as  two  parallel  chords,  which  are  given  in 
terms  of  a circle  of  known  diameter.  The  differences  of  the  times  at  which  two  stars 
arrive  at  the  middle  of  their  paths  will  be  their  ascensional  differences ; and  the  dis- 
tance between  the  chords,  which  is  readily  computed  from  their  lengths,  gives  the 
difference  of  the  declinations  of  the  two  bodies. 

The  most  approved  construction  of  the  annular  micrometer  is  that  of  the  late  Fraun- 
hofer. It  consists  of  a disk  of  parallel  plate  glass,  Fig.  2840,  having  in  its  centre  a 
round  hole  of  about  half  an  inch  in  diameter,  to  the  edges  of  which  a ring  of  steel  is 
cemented,  and  afterwards  truly  turned  in  a lathe.  The  disk  being  mounted  in  a brass 
tube,  so  that  it  may  be  accurately  adjusted  in  the  focus  of  the  eye-piece,  and  applied  to 
a telescope,  the  steel-ring  is  alone  visible,  and  appears  as  if  suspended  in  the  atmosphere,  whence  the  in- 


2840. 


2839. 


I c 


410 


MICROSCOPE. 


stmment  is  called  the  suspended  annular  micrometer.  The  advantage  of  this  construction  consists  in  Lh« 
accuracy  with  which  the  moment  of  ingress  or  egress  is  determined,  from  the  body  being  seen  in  the 
field  of  view  before  it  comes  up  to  the  edge  of  the  steel  ring.  The  annular  micrometer  is  conveniently 
used  for  comparing  the  place  of  a small  star  or  a comet  with  that  of  a known  star  in  nearly  the  same 
parallel  of  declination. 

Divided  object-glass,  or  double-image  micrometer. — This  instrument  is  formed  by  dividing  the  object- 
glass  of  a telescope  or  microscope  into  two  halves,  the  straight  edges  being  ground  smooth,  so  that  they 
may  easily  slide  by  one  another.  A double  image  of  an  object  in  the  field  of  view  is  produced  by  the 
separation  of  the  segments  ; and,  by  bringing  the  opposite  edges  of  the  two  images  into  contact,  a 
measure  of  the  diameter  of  the  object  is  obtained  in  terms  of  the  extent  of  the  separation.  From  its 
being  used  to  measure  the  diameter  of  the  sun,  this  is  usually  called  the  heliometer.  Instead  of  a 
divided  object-glass,  Ramsden  preferred  a divided  lens  in  the  eye-tube,  which  form  of  the  instrument  is 
called  the  dioptric  micrometer.  The  double-image  micrometer  was  suggested  by  Roemer,  about  1678, 
but  first  brought  into  use  by  Bouguer,  about  1748. 

MICROSCOPE.  An  optical  instrument  which  enables  us  to  see  and  examine  objects  which  are  too 
minute  to  be  seen  by  the  naked  eye.  Microscopes  are  single  or  compound,  according  to  the  nature 
of  their  construction ; a single  microscope  being  one  through  which,  whether  it  consists  of  a single 
lens  or  a combination  of  lenses,  the  object  is  viewed  directly;  and  a compound  microscope  one  in  which 
two  or  more  lenses  are  so  arranged  that  an  enlarged  image  of  the  object  formed  by  one  of  them  is 
magnified  by  the  second,  or  by  the  others,  if  there  are  more  than  two,  and  seen  as  if  it  were  the  object 
itself. 

Single  microscope. — This  instrument  is,  for  the  most  part,  simply  a lens  or  sphere  of  any  transparent 
substance,  which  refracts  the  rays  of  light  issuing  from  a small  body  placed  in  its  focus,  and  gives  them 
such  a degree  of  convergency  as  is  necessary  for  distinct  vision.  In  order  that  the  rays  of  light  issuing 
from  the  several  points  of  a very  small  body  may  produce  a sensible  impression  on  the  retina  of  the  eye, 
it  is  necessary  that  the  object  be  brought  very  near  the  eye  ; but  when  this  is  done,  the  rays  coming 
from  its  different  points  are  so  divergent  as  to  produce  only  a confused  image.  Now,  if  a convex  lens 
be  interposed  between  the  object  and  the  eye,  and  so  placed  that  its  distance  from  the  object  is  a little 
less  than  its  focal  distance,  the  diverging  rays  issuing  from  the  object  are  refracted  by  the  lens,  and 
enter  the  eye  placed  behind  it,  either  parallel,  or  so  nearly  parallel  as  to  afford  distinct  vision.  The  ob- 
ject is  then  seen  in  the  direction  of  the  refracted  rays,  and  at  the  distance  at  which  it  could  be  distinctly 
seen  by  the  naked  eye,  and  consequently  magnified  in  the  ratio  of  the  distance  of  distinct  vision  to  the 
focal  distance  of  the  lens.  This  ratio  is  called  the  magnifying  power  of  the  lens  ; hence,  for  single  mi- 
croscopes, the  magnifying  power  is  equal  to  the  distance  at  which  a small  object  can  be  seen  distinctly 
by  the  naked  eye,  divided  by  the  focal  distance  of  the  lens ; and,  as  the  distance  of  distinct  vision  is 
constant,  (at  least  for  the  same  individual,)  the  magnifying  power  is  inversely  as  the  focal  distance.  If 
we  suppose  the  distance  which  limits  distinct  vision,  in  respect  of  minute  objects,  to  be  5 inches  (which 
is  about  the  average  for  good  eyes)  and  the  focal  distance  of  the  lens  to  be  1 inch,  the  object  will  be 
magnified  5 times  in  linear  dimensions,  and  25  times  in  superficial.  If  the  focal  distance  is  one-tenth 
of  an  inch,  the  magnifying  power  will  be  50  in  linear  extent,  and  2500  in  superficial. 

A single  microscope  may  be  obtained  very  easily  by  piercing  a small  circular  hole  in  a slip  of  metal, 
and  introducing  into  it  a drop  of  water,  which  will  assume  a spherical  form  on  each  side  of  the  metal. 
The  substance  commonly  used  for  microscopic  lenses  is  plate  glass ; but  they  are  sometimes  formed  of 
rock  crystal,  which  is  better.  Flint  glass,  by  reason  of  its  great  dispersive  power,  is  unfitted  for  the 
pjurpose.  The  precious  stones,  as  the  garnet,  ruby,  sapphire,  and  diamond,  have  been  proposed ; but  the 
numerous  and  skilful  attempts  of  Mr.  Yarley  and  Mr.  Pritchard  have  proved  that  the  advantages  aris- 
ing from  the  greater  refractive  power  of  those  substances  are  more  than  counterbalanced  by  their  color, 
reflective  power,  double  refraction,  and  heterogeneous  structure.  The  crystalline  lenses  of  minnows  and 
other  small  fishes  give  a very  perfect  image  of  minute  objects. 

When  the  object  to  be  examined  is  of  such  magnitude  as  to  subtend  an  angle  of  some  degrees,  the 
requisite  distinctness  cannot  be  given  to  its  whole  surface  by  an  ordinary  lens,  in  consequence  of  the 
confusion  occasioned  by  the  lateral  rays ; unless,  indeed,  the  rays  are  only  permitted  to  enter  the  lens 
through  a very  small  aperture,  whereby  the  quantity  of  light  is  greatly  diminished.  In  order  to 
remedy  this  inconvenience,  Dr.  Wollaston  contrived  a form  of  lens,  to  which  he  gave  the  name  of 
periscopic  lens.  Its  construction  is  as  follows : two  plano-convex  lenses  or  hemispheres  are  ground  to 
the  same  radius,  and  between  their  plane  surfaces  a thin  plate  of  metal,  with  a circular  aperture,  is 
introduced.  The  aperture  which  appeared  to  give  the  most  distinct  image  was  about  ^ of  the  focal 
length  in  diameter ; and,  when  the  aperture  was  well  centered,  the  visible  field  was  as  much  as  20° 
in  diameter.  A lens  of  this  kind  possesses  the  double  advantage  of  having  a very  short  focal  dis- 
tance, and  very  little  spherical  aberration.  Dr.  Wollaston’s  contrivance  may,  however,  be  improved 
upon  in  various  ways ; for  example,  by  filling  up  the  central  aperture  with  a cement  of  the  same 
refractive  power  as  the  lenses,  whereby  the  loss  of  fight  from  the  double  number  of  surfaces  is  avoided  ; 
or  by  grinding  away  the  equatorial  parts  of  a sphere  of  glass,  so  as  to  leave  a deep  groove  all  round 
it,  in  the  plane  of  a great  circle  perpendicular  to  the  axis  of  vision,  and  filling  the  groove  with  opaque 
matter.  This  last  construction  is  called  the  Coddington  lens,  (from  the  name  of  its  proposer,)  and 
when  executed  in  garnet,  and  used  in  homogeneous  fight,  it  is  considered  by  Sir  David  Brewster 
to  be  the  most  perfect  of  all  lenses,  either  for  single  microscopes,  or  the  object  lenses  of  compound 
ones. 

In  using  a single  lens  as  a magnifier,  it  is  always  necessary  that  the  fight  be  made  to  pass  through 
a very  small  aperture,  in  order  that  the  object  may  be  seen  distinctly  and  without  distortion.  This 
necessity  arises,  both  from  the  spherical  aberration  and  the  chromatic  dispersion  of  the  fight  falling  on 
the  surface  of  the  lens  under  an  angle  of  considerable  obliquity  ; and  the  consequence  is,  that  the 
quantity  of  fight  admitted  to  the  eye  is  so  much  diminished  that  the  object  cannot  clearly  be  seen 


MICROSCOPE. 


411 


To  remedy  tills  inconvenience,  Dr.  Wollaston  proposed  a combination  of  two  lenses,  called,  in  const* 
quence,  a microscopic  doublet,  the  optical  partof  which  may  be  described  as  follows:  M and  N,  Fig. 
2841,  are  two  plano-convex  lenses,  whose  focal  lengths  are  in  the  ratio  of  8 to  1,  or  nearly  so,  and 
placed  one  over  the  other  so  that  their  plane  sides  are  towards  the  object.  The  adjustment  of  the 
distance  between  the  lenses  is  best  accomplished  by  trial ; and  they  must,  accordingly,  be  so  mounted 
that  the  distance  may  be  varied  at  pleasure.  A D is  a diaphragm  or  stop  for  limiting  the  aperture. 
Though  it  does  not  appear  that  the  stop  was  contemplated  by  Dr.  Wollaston,  who  makes  no  allusion 
to  it,  the  performance  of  the  microscope  depends  much  on  its  nice  adjustment.  It  is  obvious  that  as 
each  of  the  pencils  of  light  from  the  extremities  of  the  object  is  rendered  eccentric  by  the  stop,  and 
made  to  pass  through  the  two  lenses  on  opposite  sides  of  the  common  axis,  they  are  affected  by  oppo- 
site errors,  which,  in  some  degree,  serve  to  counteract  each  other.  This  doublet,  when  correctly  made, 
is  infinitely  superior  to  any  single  lens,  and  will  transmit  a pencil  of  from  35°  to  50°  wdthout  any  very 
sensible  errors.  The  original  description  by  Dr.  Wollaston  is  given  in  the  Philosophical  Transactions 
for  1829. 

The  above  construction  has  been  improved  upon  by  substituting  two  plano-convex  lenses  for  N in 
the  doublet,  the  plane  side  of  the  one  being  in  contact  with  the  convex  side  of  the  other,  and  the  stop 
being  retained  between  them  and  the  third.  This  combination  is  called  a triplet ; and  its  advantage 
is,  that  the  errors  of  the  doublet  are  still  further  reduced  by  the  greater  approximation  to  the  object, 
in  consequence  of  which  the  refractions  take  place  nearer  the  axis. 

When  the  magnifying  power  of  the  lens  is  considerable,  and,  consequently,  its  focal  distance  very 
email,  it  requires  to  be  placed  at  the  proper  distance  from  the  object  with  great  precision  ; and,  as  it 
cannot  be  held  in  the  hand  with  sufficient  steadiness  for  any  length  of  time,  it  requires  to  be  mounted 
in  a frame  having  a rack  and  screw,  by  means  of  which  its  distance  from  the  object  can  be  adjusted 
with  accuracy.  Mirrors  for  collecting  the  light  and  throwing  it  upon  the  object  are  also  necessary  for 
many  purposes. 


Compound  microscope. — The  simplest  kind  of  compound  microscope  is  formed  by  the  combination  of 
two  converging  lenses,  whose  axes  are  placed  in  the  same  straight  line.  The  arrangement  of  the 
lenses,  and  the  path  of  the  rays,  will  be  readily  understood  from  the  annexed  diagram,  Fig.  2842. 
M N is  the  object-glass,  which  has  a very  short  focal  distance,  and  P Q the  eye-glass.  A small  object, 
a b,  being  placed  before  the  object-glass,  a little  further  from  it  than  the  focus  or  parallel  rays,  a re- 
versed and  enlarged  image,  a ' b,  will  be  formed  at  some  distance  behind  M 1ST.  The  lens  P Q is  placed 
at  such  a distance  from  M N that  its  principal  focus  is  in  the  line  at  a1  b'  ; consequently  the  rays  of 
light  from  every  point  of  the  image  a'  b'  emerge  nearly  parallel  from  P Q,  and  to  the  eye  at  E the 
image  a ' b'  is  magnified,  as  if  it  were  a real  object,  into  a"  b",  and  appears  at  a distance  equal  to  the 
limits  of  distinct  vision,  which,  as  stated  above,  is  about  6 inches. 

The  magnifying  power  of  this  microscope,  or  the  ratio  of  a"  b"  to  a 6 is  found  as  follows  : In  the  first 
place,  if  we  assume  d to  denote  the  distance  of  the  first  image  a'  b'  from  MN,  and  / the  distance  of 
a b from  M 1ST,  or  the  focal  distance  of  MN,  we  have  this  proportion,  a'  b' : a b : : d :/.  In  the  second 
place,  if  l denote  the  limit  of  distinct  vision,  or  distance  of  the  second  image  a"  b"  from  P Q,  and  f the 
focal  distance  of  P Q,  (or  distance  of  a'  b'  from  P Q,)  we  shall  also  have  a"  b" : a'  b' : : l :/'.  These  two 

proportions,  being  multiplied  together,  give  which,  therefore,  is  the  magnifying  power  of 

a u J f 

the  microscope.  It  thus  appears  that  the  magnifying  power  is  inversely  as  the  product  of  the  focal  dis- 
tances of  the  two  lenses,  and  directly  as  the  distance  between  them.  The  magnifying  power  will  there- 
fore be  increased  by  increasing  the  distance  between  the  object-glass  and  eye-glass ; but  a limit  is 
soon  placed  to  this  increase  by  the  indistinctness  of  the  image,  and,  in  practice,  it  is  not  advisable  to 
make  the  distance  of  a'  b'  from  M N more  than  from  5 to  7 inches.  Suppose  the  focal  distance  of  M N to 
be  \ of  an  inch,  and  the  distance  of  a'  V from  M N to  be  5 inches,  then  a'  b'  will  be  20  times  greater 
than  a b ; and  if  the  focal  distance  of  PQ  be  ^ an  inch,  and  the  distance  of  a"  b"  from  P Q be  5 
inches,  then  a"  b"  will  be  10  times  greater  than  a'  b’,  and  consequently  200  times  greater  than  a b ; 
or  the  magnifying  power  is  200. 

The  great  defects  of  the  microscope,  when  constructed  in  the  manner  now  described,  consist  in  the 
smallness  of  the  field  of  view  and  want  of  achromatism  in  the  object-glass,  in  consequence  of  which 
the  images  a' b'  and  a"  b"  are  fringed  with  the  prismatic  colors.  For  the  sake  of  enlarging  the  field 
of  view,  a third  lens,  larger  than  either  of  the  others,  and  called  the  field-glass,  is  usually  interposed 
between  the  image  a'  b'  and  the  object-glass. 

Reflecting  microscope. — The  principle  of  the  reflecting  microscope  is  very  simple,  and  easily  con- 


412 


MILLSTONE. 


reived.  Suppose  M N,  Fig.  2843,  to  be  a concave  speculum,  and  a small  object  to  be  placed  before  it 
at  /.  A reflected  image  of  the  object  will  be  formed  at  F,  where  the  rays  issuing  from  each  point  of 
the  object  intersect  each  other,  and  magnified  in  the  proportion  of  FM  to  / M.  If  the  image  at  F ia 
viewed  with  the  naked  eye,  the  instrument  is  a single  reflecting  microscope  ; but  if  the  image  is  view- 
ed through  a refracting  lens  P Q,  (or  a combination  of  lenses  forming  an  eye-piece,)  by  which  the  rays 
are  made  to  converge  towards  the  eye  at  E,  it  becomes  a compound  reflecting  microscope. 

The  reflecting  microscope  was  first  proposed  by  Sir  Isaac  Newton  in  the  form  now  described  ; but, 
on  account  of  the  impracticability  of  illuminating  the  object,  it  was  long  disused.  It  has,  however 
been  recently  revived,  under  a modified  form,  by  Professor  Amici,  of  Modena,  who  places  the  object 
outside  the  tube  of  the  microscope,  below  the  line  N F ; and,  in  order  that  an  image  may  be  formed  in 
the  speculum,  the  rays  issuing  from  the  object  fall  upon  a small  plane  mirror  placed  at  / inclined  to 
the  axis  of  the  speculum  in  an  angle  of  45°,  whereby  they  are  thrown  upon  the  speculum  in  the  same 
manner  as  if  the  object  itself  were  placed  at/.  By  this  means  the  object  can  be  illuminated  with  per- 
fect facility.  The  concave  speculum  MN  is  ground  into  an  ellipsoidal  surface  ; the  diagonal  mirror  is 
placed  at  the  nearest  focus/  and  the  image  is  consequently  formed  at  the  other  focus  F.  The  image 
at  F is  viewed  with  a single  or  double  eye-piece,  as  in  other  microscopes. 


2843.  2844. 


Solar  and  oxyliydrogen  microscopes. — The  solar  microscope  is  composed  essentially  of  a mirror  and 
two  converging  lenses.  The  plane  metallic  mirror  C D,  Fig.  2844,  reflects  the  sun’s  rays  upon  the  lens 
MN,  by  which  they  are  concentrated  upon  the  object  ab  placed  in  its  focus.  The  object  being  thus 
strongly  illuminated,  is  placed  before  a second  lens  P Q,  (a  little  before  the  principal  focus,)  by  which 
the  rays  are  rendered  still  more  convergent,  and  produce  a magnified  image  of  the  object  upon  a 
screen  suitably  placed  at  a distance  of  some  fee  behind  the  lens.  The  object  is  here  supposed  to  be 
transparent ; if  opaque,  the  light  must  be  thrown  upon  it  in  such  a manner  as  to  be  reflected  by  it  to 
PQ.  The  mirror  and  lens  MN  are  placed  in  the  hole  of  a window-shutter  in  a darkened  room;  and 
the  mirror  must  be  movable,  in  order  that  the  sun’s  rays  may  always  fall  upon  it  under  a proper  angle 
to  be  reflected  to  the  lenses.  But  the  solar  microscope  is  now  almost  entirely  superseded  by  the 
oxyliydrogen  microscope ; so  called  because  the  illumination,  instead  of  being  produced  by  the  sun’s 
rays,  is  produced  by  burning  a small  piece  of  lime  or  marble  in  a stream  of  oxyliydrogen  gas.  In  this 
case  the  plane  mirror  C D becomes  unnecessary  ; and  instead  of  the  lens  M N a concave  speculum  is 
employed,  in  front  of  which  the  ball  of  lime  is  placed,  and  an  intense  light  thus  thrown  upon  the  ob- 
ject ab,  the  rays  from  which  are  brought  to  foci  upon  the  screen  by  the  lens  P Q.  For  full  details 
respecting  the  management  of  this  apparatus,  which  forms  a very  popular  exhibition,  the  reader  is 
referred  to  Goring  and  Pritchard' s Micographia.  For  descriptions  of  the  various  kinds  of  micro- 
scopes see  Brewster's  Treatise  on  JVeiu  Philosophical  Instruments ; or  Ency.  Brit.,  art.  “ Microscope.” 

MILE.  A long  measure,  equal  to  1160  yards.  See  Weights  and  Measures,  for  miles  of  different 
countries. 

MILL.  The  term  is  most  commonly  applied  to  machines  for  grinding  corn,  but  it  is  likewise  used  in 
a more  loose  sense  to  denote  machines  intended  for  other  purposes,  as  the  grinding  of  bark,  for  felling 
wood,  for  preparing  flax,  cotton,  &c.  See  Water-wheels,  Geering,  and  the  various  processes  of  man- 
ufacture commonly  classed  under  this  head. 

MILLSTONE,  or  Burr-Stone.  This  interesting  form  of  silica,  which  occurs  in  great  masses,  has  a 
texture  essentially  cellular,  the  cells  being  irregular  in  number,  shape,  and  size,  and  are  often  crossed 
by  thin  plates,  or  coarse  fibres  of  silex.  The  burr-stone  has  a straight  fracture,  but  it  is  not  so  brittle 
as  flint,  though  its  hardness  is  nearly  the  same.  It  is  feebly  translucent;  its  colors  are  pale  and  dead, 
of  a whitish,  grayish,  or  yellowish  cast,  sometimes  with  a tinge  of  blue. 

The  burr-stones  usually  occur  in  beds,  which  are  sometimes  continuous,  and  at  others  interrupted 
These  beds  are  placed  amid  deposits  of  sand,  or  argillaceous  and  ferruginous  marls,  which  penetrate 
between  them,  filling  their  fissures  and  honeycomb  cavities.  Burr-stones  constitute  a very  rare  geologi- 
cal formation,  being  found  in  abundance  only  in  the  mineral  basin  of  Paris,  and  a few  adjoining  dis- 
tricts. Its  place  of  superposition  is  well  ascertained  : it  forms  a part  of  the  lacustrine,  or  fresh-water 
formation,  which,  in  the  locality  alluded  to,  lies  above  the  fossil-bone  gypsum,  and  the  stratum  of  sand 
and  marine  sandstone  which  covers  it.  Burr-stone  constitutes,  therefore,  the  uppermost  solid  stratum 
of  the  crust  of  the  globe  ; for  above  it  there  is  nothing  but  alluvial  soil,  or  diluvial  gravel,  sand,  and 
loam. 

Burr-stones  sometimes  contain  no  organic  forms,  at  others  they  seem  as  if  stuffed  full  of  fresh-water 
shells,  or  land  shells  and  vegetables  of  inland  growth.  There  is  no  exception  known  to  this  arrange- 
ment ; but  the  shells  have  assumed  a silicious  nature,  and  their  cavities  are  often  bedecked  with  crys- 
tals of  quartz.  The  best  burr-stones  for  grinding  corn,  have  about  an  equal  proportion  of  solid  matter 
and  of  vacant  space.  The  finest  quarry  of  them  is  upon  the  high  ground  near  La  Ferte-sous-Jouarre 
The  stones  are  quarried  in  the  open  air,  and  are  cut  out  in  cylinders  from  one  to  two  yards  in  diameter, 
by  a series  of  iron  and  wooden  wedges,  gradually  but  equally  inserted.  The  pieces  of  burr-stones  are 
afterwards  cut  in  parallelopipeds,  called  panes,  which  are  bound  with  iron  hoops  into  large  millstones 
These  pieces  are  exported  chiefly  to  this  country  and  England.  Good  millstones  of  a bluish  white 
tolor,  with  a regular  proportion  of  cells,  when  six  feet  and  a half  in  diameter,  fetch  1200  francs  a-piece, 
or  £48  sterling.  A coarse  conglomerate  sandstone  or  breccia  is,  in  some  coses,  used  as  a substitute  for 
burr-stone,  but  it  is  a poor  one. 


MINERAL  KINGDOM. 


413 


MINERAL  KINGDOM,  materials  from,  used  in  the  mechanical  and  ornamental  arts.  The  materials 
from  the  mineral  kingdom  may  be  divided,  so  far  as  regards  these  pages,  into  two  groups  : the  earthy, 
and  the  metallic. 

The  earthy  materials,  when  employed  in  the  mechanical  and  useful  arts,  are  generally  used  in  their 
natural  states. 

The  metallic  minerals  consist  in  general  of  metallic  oxides,  combined  with  a larger  quantity  of  some 
base,  such  as  silex,  clay,  or  sulphur,  which  are  the  most  common  mineralizers ; the  cohesion  of  tire  mass 
has  in  general  to  be  overcome  by  heat,  which  destroys  the  affinity  of  the  component  parts,  and  allows 
of  the  separation  of  the  metals  in  various  ways.  Of  these  processes  the  author  will  have  scarcely  any 
thing  to  say,  but  the  metals  themselves,  when  so  obtained,  will  be  treated  of  at  some  length  here- 
after. 

The  earthy  and  crystalline  mineral  substances  are  less  frequently  worked  by  the, amateur  than  the 
metallic,  and  therefore  they  will  be  noticed  rather  briefly,  and  in  the  order  of  their  hardness,  as  derived 
from  the  folio  whig  table : 

Table  of  Hardness,  etc. 


1.  Talc 

2.  Compact  Gypsum. 

S.  Calcareous  spar.... 

4.  Fluorspar 

5.  Apatite 

6.  Felspar 

1 Silex 

8.  Topaz 

9.  Sapphire 

10.  Diamond 


Lead,  Steatite  or  Soapstone,  Meerschaum 28 

Tin,  Ivory,  Potstone,  Figure-stone,  Cannel-coal,  Jet,  <fcc 90 

( Gold,  Silver,  and  Copper,  when  pure ; soft  Brass,  Serpentine,  Mar- 

'{  files,  Oriental  Alabaster,  &c Il 

Platinum,  Gtm-metal 53 

Soft  Iron 48 

Soft  Steel,  Porphyry,  Glass 52 

Hardened  Steel,  Quartz,  Flint,  Agate,  Granite,  Sandstone,  Sand 20 

Hardest  Steel 6 

Ruby  and  Corundum 1 

Cuts  all  substances 1 


The  above  table  exhibits  the  relative  degrees  of  hardness  of  the  several  substances  in  the  estimation 
of  the  mineralogist ; thus  talc  may  be  scratched  by  gypsum,  gypsum  may  be  scratched  by  calcareou* 
spar,  the  last  by  fluor  spar,  and  so  on  throughout;  in  the  second  column  are  named  some  of  the  miner 
als,  metals,  and  other  substances  of  similar  degrees  of  hardness,  and  the  last  column  contains  the  nura 
ber  of  minerals  which,  in  respect  to  hardness,  are  ranked  under  each  of  the  ten  grades. 

In  the  several  practices  of  working  these  numerous  substances,  structure  must  also  be  taken  into  ac- 
count, or  the  mode  in  which  their  separate  particles  are  combined  ; thus  hardened  steel,  quartz,  granite, 
and  sandstone,  are  each  included  under  the  number  7.  The  particles  of  the  steel,  however,  are  much 
more  firmly  united  than  those  of  the  glassy  crystalline  quartz,  which  is  far  more  brittle ; and  still  more 
so  than  the  aggregations  of  crystals  in  the  granites ; the  last  may  be  wrought  by  sharp-pointed  picks, 
and  chisels  of  hard  steel,  which  crush  and  detach,  rather  than  cut  the  crystals ; and  although  sandstone 
consists  almost  entirely  of  particles  of  silex  cemented  with  silex,  still,  as  the  grains  of  the  sandstone 
are  but  loosely  held  together,  it  may  be  turned  with  considerable  facility  with  the  tools  used  for  turn- 
ing marble,  and  which  is  the  every-day  practice  in  turning  the  grindstone.  Whereas  granite,  which 
contains  from  half  to  three-fifths  felspar,  a substance  softer  than  silex,  and  porphyry,  which  consists  of 
crystals  of  felspar  imbedded  in  a base  of  felspar,  cannot  be  turned  with  steel  tools  at  all. 

Several  mineral  substances  are  formed  by  the  successive  deposition  of  their  component  parts  in  uni- 
form layers,  as  in  mica  and  slate  ; or  in  alternate  depositions,  as  in  the  Yorkshire  flags  or  sandstones. 
Mica  may  in  consequence  be  split  into  leaves  even  so  thin  as  the  one  50,000th  of  an  inch ; it  is  used  by 
the  optician  in  mounting  objects  for  the  microscope,  and  is  often  misnamed  talc ; slate  may  be  split  into 
very  thin  leaves  of  considerable  size,  and  those  sandstones  which  result  from  the  recomposition  of 
granite  are  most  readily  split  through  the  layers  of  minute  scales  of  mica,  which,  being  lighter  than 
the  other  ingredients,  are  deposited  in  separate  layers. 

Many  hard  substances,  as  the  agates,  carnelians,  and  flints,  show  neither  the  crystalline  nor  lamellar 
structure,  and  break  with  a fracture  termed  the  conchoidal,  of  which  the  broken  flakes  of  glass,  flint, 
and  pitch,  may  be  taken  as  familiar  examples*  Hard  crystalline  gems,  on  the  other  hand,  are  formed 
of  laminae,  arranged  in  various  directions,  and  may  be  readily  split  by  the  hammer  and  chisel  through 
their  natural  cleavages  or  joints  ; but  in  most  of  the  earthy  minerals,  grinding  is  resorted  to  for  obtain- 
ing the  ultimate  and  defined  shapes,  the  consideration  of  which  methods  are  for  the  present  deferred. 
Should  none  of  these  processes  be  resorted  to  by  my  readers,  they  will  at  any  rate  serve  to  explain  the 
broad  features  of  the  respective  influence  of  the  mineral  materials  (amongst  others)  upon  tools,  which 
is  undoubtedly  an  important  link  in  our  subject,  and  one  full  of  general  interest  and  variety,  from  the 
diversity  of  the  methods  which  are  pursued  in  such  of  the  useful  ard  ornamental  arts  as  require  these 
natural  mineral  substances,  that  include  both  the  softest  and  hardest  solids  with  which  we  are  ac- 
quainted. 

The  hard  mineral  substances  are  mostly  attached  to  the  lathe  by  resinous  cements,  as  driving  them 
into  hollow  chucks,  like  pieces  of  wood  or  metal,  would  endanger  their  being  broken,  from  their  crys- 
talline nature.  The  soft  cements  consist  of  about  half  a pound  of  resin,  one  ounce  of  wax,  and  any 
fine  powder,  often  the  fine  dust  from  the  stones  that  are  turned ; pounded  brickdust  and  coarse  flour 


* Flint,  when  first  raised,  may  be  split  with  remarkable  precision,  with  the  imperfectly  flat  conchoidal  fracture,  as  may  be 
well  observed  in  gun-flints ; the  perfection  of  the  keen  edges  thus  produced,  exceeds  that  of  any  which  may  be  obtained 
upon  similar  substances  by  art;  when  the  water  is  completely  dried  out  of  the  flint  it  breaks  with  the  ordinary  conchoidal 
tracture. 


414 


MINERAL  KINGDOM. 


are  used,  and  pitch  also  enters  into  the  composition  of  other  kinds.  Shellac,  either  alone  or  mixed 
with  half  its  weight  of  finely  powdered  pumice-stone,  is  sometimes  employed;  and  fine  sealing-wax, 
which  is  principally  shellac,  is  used,  as  well  as  many  other  kinds  of  cement.  The  stone  is  in  general 
warmed  to  the  melting  point  of  the  cement,  but  sometimes  the  latter  is  melted  by  friction  alone. 

Clay. — This  material  is  only  worked  in  the  soft  and  plastic  state.  In  pottery,  it  is  attached  to 
the  potter’s  wheel  or  horizontal  lathe,  by  its  own  adhesiveness  alone,  and  is  turned  by  the  hands  and 
blunt  wooden  tools ; it  is  also  pressed  into  moulds  of  metal  and  plaster  of  Paris,  some  of  wliich  are 
mounted  on  the  lathe  when  the  objects  are  smoothed  within  and  moulded  without.  Lathes  with 
vibrating  mandrels,  or  possessing  the  movement  of  the  rose-engine,  are  likewise  employed  for  the  pro- 
duction of  some  works  in  pottery  and  china.  The  artists  who  model  in  clay,  use  blunt  instruments, 
mostly  of  wood,  which  are  rounded  at  the  ends ; and  all  artisans  cut  or  divide  this  material  with  a 
stretched  pack-thread,  or  a metal  wire.  The  clay  for  superior  pottery  works  and  modelling,  often 
called  pipe-clay,  is  decomposed  felspar — it  is  mostly  obtained  from  Cornwall  and  Devon ; and  the  im- 
portance of  the  Stourbridge,  and  some  other  refractory  clays,  in  the  construction  of  crucibles  and  fire- 
bricks for  a variety  of  other  purposes  in  the  arts,  must  not  be  overlooked. 

Meerschaum — Amber. — These  are  principally  used  for  smoking-pipes.  Previously  to  being  turned, 
the  meerschaum  is  soaked  in  water ; it  is  then  worked  with  ordinary  tools,  and  is  described  “ to  cut 
like  a turnip.”  After  having  been  dried  in  a warm  room,  it  is  polished  with  a few  of  its  own  shavings, 
and  rubbed  with  white  wax,  which  penetrates  its  surface.  Sometimes  the  pipes  are  dipped  into  a 
vessel  containing  melted  wax. 

Jet,  cannel  coal,  Ac. — Jet  is  found  at  Whitby,  Scarborough,  and  Yarmouth,  and  is  also  imported 
from  Turkey,  but  it  is  not  generally  met  in  large  pieces.  It  may  be  turned  with  most  of  the  tools 
for  the  soft  and  hard  woods,  and  worked  with  saws  and  files,  all  used  in  the  ordinary  way.  Jet,  until 
polished,  appears  of  a brown  color,  and  is  manufactured  by  the  lapidary  into  a variety  of  ornaments, 
such  as  necklaces,  ear-rings,  and  crosses. 

Cannel  coal  is  principally  obtained  in  England  from  Yorkshire,  Shropshire,  Derbyshire,  and  Cum- 
berland. It  is  also  found  in  parts  of  Scotland  and  North  Wales.  It  occurs  in  seams,  generally  about 
three  inches,  but  occasionally  one  foot  thick,  amongst  ordinary  coal ; sometimes,  as  at  the  Angel  Bank 
Colliery,  near  Ludlow,  it  constitutes  the  entire  bed.  Compared  with  jet  it  is  much  more  brittle,  also 
heavier,  and  harder  ; it  is  less  brown  when  worked,  less  brilliant,  but  more  durable  when  polished  ; 
neither  of  them  are  at  all  influenced  by  acids  or  moisture,  although  they  temporarily  expand  by  heat. 

Cannel  coal  may  be  thought  to  be  a dirty  and  brittle  material,  but  this  is  only  partially  true ; it  is 
far  better  suited  to  the  lathe  than  might  be  expected,  although  a peculiar  treatment  is  called  for  in 
the  entire  management,  which  commences  with  the  selection  of  pieces  free  from  flaws,  of  a compact 
grain,  and  of  a clean  conchoidal  rather  than  flaky  structure. 

All  the  tools  for  cannel  coal  are  ground  with  two  bevels  exactly  like  the  chisel  for  soft  wood  turn- 
ing, but  they  are  held  horizontally ; a small  gouge,  from  one-quarter  to  three-eighths  of  an  inch  wide, 
also  slightly  bevelled  oft'  from  within,  is  used  for  roughing  out,  or  rather  bringing  the  work  as  near  as 
possible  to  the  shape,  to  save  the  finishing  tools : these  should  be  ground  with  thin  and  very  sharp 
edges,  otherwise  they  burnish  instead  of  scrape  the  work.  The  ordinary  tools  for  ivory  and  hard  wood, 
if  employed,  must  be  held  downwards  at  an  angle  of  about  twenty  degrees.  These  tools  are  some- 
times used  with  a wire  edge  turned  up  in  the  manner  of  a joiner’s  scraper. 

The  plankway  surfaces  turn  the  most  freely,  and  with  shavings  much  like  those  of  wood ; the  edges 
yield  small  chips,  and  at  last  a fine  dust,  but  which  does  not  stick  to  the  hands  in  the  manner  of  com- 
mon coal.  Flat  objects,  such  as  inkstands,  are  worked  with  the  joiner’s  ordinary  tools  and  planes;  but 
with  these  likewise  it  is  also  better  the  edge  should  be  slightly  bevelled  on  the  flat  side  of  the  iron. 
The  edges  of  cannel  coal  are  harder  and  polish  better  than  the  flat  surfaces. 

Alabaster. — This  is  a sulphate  of  lime,  or  compact  gypsum,  which  occurs  in  various  places ; in 
England  the  finest  is  found  near  Derby,  where  the  pure  white  is  employed  for  the  purposes  of  sculp- 
ture, but  the  finest  white  alabaster  is  from  Italy  ; the  variegated  kinds  are  turned  into  vases,  pillars, 
and  other  ornamental  works. 

The  Italian  alabaster,  when  first  raised,  is  semi-transparent  like  spermaceti ; it  is  wrought  in  this 
state.  The  works  are  generally  rendered  of  a more  opaque  white  by  placing  them  in  a vessel  upon 
little  fragments  of  the  stone,  so  that  they  may  be  entirely  surrounded  by  the  cold  water,  which  is 
then  poured  in  and  very  slowly  raised  to  nearly  the  boiling  temperature ; this  should  occupy  two 
hours.  The  vessel  is  then  allowed  to  cool  to  10°  or  80°  Fahr.,  the  object  is  taken  out,  closely 
wrapped  in  a cloth,  and  allowed  to  remain  until  dry.  The  alabaster  at  first  appears  little  altered, 
but  it  gradually  assumes  the  opaque  white  ; for  the  first  six  months  it  is  considered  to  remain  softer 
than  at  first,  but  to  become  ultimately  somewhat  harder  from  the  treatment. 

Alabaster  readily  absorbs  grease  and  dirt  of  any  kind,  but  it  is  cleaned  by  the  Italians  very  dexter- 
ously ; some  use  weak  alkaline  and  acid  solutions.  Soap  and  water  are  not  to  be  recommended,  as 
the  unpolished  parts  absorb  the  oil  of  the  soap. 

There  are  but  few  kinds  of  tools  employed  in  turning  alabaster,  namely,  points  for  roughing  out, 
flat  chisels  for  smoothing,  and  one  or  two  common  firmer  chisels,  ground  convex  and  concave  for  curved 
lines.  The  point  tools  used  in  Derbyshire  are  square,  and  described  under  marble  ; the  Italians  pre- 
fer a triangular  point,  as  an  old  triangular  file  driven  into  a handle  and  ground  off  obtusely  at  the 
?nd.  The  carved  parts  are  done  by  hand  with  small  gouges,  chisels,  and  scorpers  of  various  forms  and 
sizes ; drills,  files,  and  saws  are  also  employed,  and  the  surface,  unless  polished,  is  finished  with  fish- 
skin  and  Dutch  rush. 

The  fibrous  gypsum,  called  from  its  brilliant  appearance  satinstone,  is  much  softer;  it  is  turned  into 
necklaces  and  small  ornaments  by  a sharp,  flat  chisel,  held  obliquely ; a square  point  would  split  off 
the  fibres.  All  the  above  kinds  of  alabaster  or  gypsum  produce,  when  calcined,  the  well-known 
plaster  of  Paris,  a substance  used  for  cementing  together  such  of  the  vases  as  are  made  of  detached 


MINERAL  KINGDOM. 


415 


parts;  plaster  of  Paris  also  renders  other  and  far  more  important  services  in  a variety  of  the  usefu 
and  ornamental  arts. 

Oriental  alabaster  is  a very  different  substance  from  the  above  ; it  is  a stalacrnitic  carbonate  ot 
lime,  compact  or  fibrous,  generally  white,  but  of  all  colors  from  white  to  brown,  and  sometimes  veined 
with  colored  zones ; it  is  of  the  same  hardness  as  marble,  is  used  for  similar  purposes,  and  wrought  by 
the  same  means. 

Slate. — The  common  blue  and  red  slates  consist  of  clay  and  silex  in  about  equal  parts  ; the  largest 
slate  quarries,  perhaps  in  the  world,  are  at  Bangor  in  Wales.  The  blocks,  when  quarried,  are  split 
into  sheets,  sometimes  exceeding  eight  feet  by  four,  by  means  of  long,  wide,  and  thin  chisels,  applied  on 
the  edge,  parallel  with  the  lamina;,  and  struck  with  a mallet  or  hammer.  The  sheets  are  sawn  into 
rectangular  pieces  and  slabs,  by  ordinary  circular  saws  with  teeth,  moved  rather  slowly ; and  these 
are  afterwards  planed  for  billiard-tables,  <fcc.,  in  machines  nearly  resembling  the  engineer’s  planing- 
machiues  for  metal,  but  with  tools  applied  at  about  an  angle  of  thirty  degrees  with  the  perpendicular. 
The  process  of  sawing  slate  appears  rather  crushing  than  cutting,  or  a trial  of  strength  between  the 
tool  and  the  slate,  as  the  latter  is  carried  up  to  the  saw  by  machinery,  and  cannot  recede  from  the  in- 
strument ; the  saw  is  sharpened  about  four  times  a day,  and  is  worn  out  in  about  two  months.  The 
planing  tools  for  common  slabs  are  six  inches  wide,  and  when  made  of  the  best  cast-steel  and  properly 
tempered,  they  last  a day  and  a half  without  being  sharpened  ; the  jambs  for  chimney-pieces  and 
other  mouldings,  not  exceeding  about  six  inches  wide,  are  planed  with  figured  tools  of  the  full  width. 

Slate  is  also  turned  in  the  lathe  with  the  heel  or  hook,  tools  used  for  iron,  and  also  with  ordinary 
tools,  used  witli  or  without  the  slide  rest,  which  are,  however,  rapidly  blunted  when  applied  superfi- 
cially ; it  is  much  tougher  at  the  ends  or  edges  of  the  laminae  than  at  the  flat  sides.  Slate  has  been 
recently  worked  into  chimney-pieces,  and  a variety  of  objects  for  internal  decoration,  which  are 
ornamented  by  a patent  process,  in  the  manner  of  papier  nidche  and  china;  imitations  of  marbles  and 
granite  are  thus  made  at  about  one-third  the  prices  of  marble.  Some  of  the  substances  known  to 
mineralogists  as  slates  are  exceedingly  hard,  and  vary  from  the  hardness  24,  to  that  of  flint  or  7. 
Many  varieties,  including  the  Turkey  oilstones,  are  used  for  sharpening  tools  ; and  this  family  also 
includes  the  touchstones  formerly  used  in  assaying  gold. 

Serpentine,  potstone,  steatite. — These  are  natural  compounds  of  magnesia  and  silica.  They  are 
generally  worked  immediately  on  being  raised,  being  then  much  softer  ; but  with  the  evaporation  of 
their  moisture  they  assume  the  general  hardness  of  marble.  The  serpentine  and  steatite  are  found 
abundantly  in  Cornwall ; serpentine  is  often  called  green  marble,  and  by  the  Italians  Verde  de  prato. 
It  is  much  used  ; but  some  of  the  serpentines  will  not  polish  well. 

Potstone  is  an  inferior  variety  of  serpentine ; in  Germany  it  is  abundantly  turned  into  various 
domestic  articles  in  common  use,  whence  its  name. 

Steatite  is  called  soapstone,  from  its  smooth,  unctuous  feel,  and  when  first  raised  it  may  be  scratched 
with  the  finger-nail ; but  it  becomes  nearly  as  hard  as  the  others.  A variety  of  steatite  is  carved  by 
the  Chinese  into  images  employed  as  household  gods,  and  is  named  figure-stone  : until  lately,  it  was 
supposed  to  be  a preparation  of  rice.  Steatite  enters  into  the  composition  of  porcelain. 

Marbles,  limestones. — The  term  marble  is  applied  by  the  mason  to  any  of  the  materials  that  he 
employs  which  admit  of  being  polished ; but  the  mineralogist  designates  thereby  the  compact  car- 
bonates of  lime  variously  colored.  The  principal  kinds  worked  in  the  ornamental  arts,  are  the  white 
or  statuary  marble  from  Italy,  a variety  of  colored  marbles,  principally  from  Devonshire  and  Derby- 
shire, and  the  black  bituminous  marble  from  Derbyshire,  Wales,  and  various  parts  of  Ireland. 

The  marbles  are  turned  with  a bar  of  the  best  cast-steel,  about  two  feet  long  and  five-eighths  of  an 
inch  square,  drawn  down  at  each  end  to  a taper  point,  about  two  inches  long,  and  tempered  to  a straw- 
color  ; this  point  is  rubbed  on  two  opposite  sides  on  a sandstone,  and  held  to  the  marble  at  an  angle  of 
twenty  or  thirty  degrees : the  tool  soon  gets  dull,  and  must  be  again  rubbed  on  the  sandstone  to 
sharpen  it.  Water  should  drop  on  the  marble,  to  prevent  the  tool  from  becoming  heated  and  losing 
its  temper.  The  point  will  keep  getting  broader  by  constant  grinding,  till  it  forms  a kind  of  chisel  an 
eighth  of  an  inch  wide,  after  which,  it  will  require  drawing  out  again.  For  cutting  in  the  mouldings  a 
more  delicate  point  is  used,  and  these  are  the  only  tools  employed  ; a flat  tool  will  not  turn  marble 
at  all. 

Many  of  the  limestones,  although  chemically  like  the  marbles,  are  less  compact,  and  therefore  do 
not  readily  admit  of  being  polished  ; of  these  may  be  noticed  the  Bathstone  and  other  oolites,  which 
are  aggregations  of  egg-shaped  particles,  like  the  roes  of  fish  ; when  first  raised,  they  may  be  cut  very 
readily  with  an  ordinary  toothed  saw,  and  turned  with  great  freedom.  The  Maltese  stone,  of  which 
many  beautiful  turned  and  carved  works  were  recently  sold  in  London,  belongs  likewise  to  this 
group.  It  is  very  compact,  and  nearly  as  soft  as  chalk,  from  which,  in  fact,  it  scarcely  differs  in  any 
respect,  except  in  its  delicate  brown  cream-color.  The  natives  of  the  island  of  Malta  display  consider- 
able taste  in  the  objects  turned  and  carved  in  this  limestone. 

Fluor  spar  is  a natural  combination  of  lime  and  fluoric  acid,  and  the  workable  variety  is  peculiar 
to  Derbyshire,  where  the  art  of  turning  it  is  carried  to  great  perfection.  The  most  costly  varieties  are 
the  deep  blue  and  purple,  found  only  at  Castleton  in  that  county.  Fluor  being  an  aggregation  of 
crystals,  all  having  a fourfold  cleavage,  is  very  difficult  to  turn,  as  the  lamina;  are  easily  split ; few 
even  of  the  best  workmen  can  turn  it  into  very  thin  hollow  articles.  The  following  is  the  process. 

The  stone  is  first  roughed  out  with  a point  and  mallet,  then  heated  till  it  will  readily  frizzle  yellow 
resin  which  is  applied  all  over  it : this  penetrates  about  one-eighth  of  an  inch,  and  holds  the  crystals 
together.  It  is  next  rough-turned,  and  a little  hollowed ; it  is  again  heated  and  resined,  and  turned 
still  more  into  form ; then  it  is  bound  round  with  a thin  wire,  and  again  resined,  and  so  on  until  it  is 
sufficiently  thin  to  show  the  colors.  It  is  then  resined  for  the  last  time,  and  polished  in  the  same 
manner  as  marble,  but  the  process  is  more  difficult,  and  ultimately  but  very  little  1‘esin  remains  in  the 
surlace  of  the  work.  The  only  tool  used  is  the  steel  point. 


416 


MINERAL  KINGDOM. 


The  blue  color  of  fluor  is  often  so  intense  that  the  works  cannot  be  wrought  thin  enough  to  show  it. 
When  this  is  the  case,  the  stone  is  very  gradually  heated  in  an  oven  until  it  becomes  nearly  red-hot, 
when  the  blue  changes  to  an  amethystine  color.  Great  care  is  required,  for  if  suffered  to  remain  too 
long  the  color  would  entirely  disappear.  The  white  and  lighter  kinds  of  fluor  are  not  worth  one-tenth 
of  the  value  of  *he  blue,  but  are  wrought  in  the  same  manner  for  commoner  works. 

Freestones,  sandstones. — Freestone  is  a term  commonly  applied  by  the  mason  to  such  of  the  sand- 
stones used  for  building  purposes  as  work  freely  under  the  tools  ; namely,  the  stone-saw,  a smooth 
iron  blade,  fed  with  sand  and  water,  and  the  ordinary  picks  and  chisels,  which  are  too  familiar  to  re- 
quire more  than  to  be  named.  The  freestones  are  frequently  turned  into  balustrades,  pedestals,  and 
vases.  The  term  is  used  in  this  country  to  designate  the  sandstones  used  in  building. 

Sandstones,  from  their  relatively  slight  cohesion,  may  be  turned  with  the  point  tool  used  for  marble, 
although,  in  the  workshop,  the  grindstone  is  commonly  turned  with  an  old  file  drawn  down  for  some 
two  or  three  inches  to  about  one-eighth  of  an  inch  square,  and  held  downwards  upon  the  rest  at  the 
angle  of  20  or  30  degrees.  It  is  rolled  over  and  over,  which  continually  produces  a new  point ; the 
stone  is  then  smoothed  with  a flat  piece  of  iron  or  steel,  or  rubbed  with  a broken  lump  of  another 
grindstone. 

Porphyries,  cleans,  granites. — The  division  and  preparation  of  the  softest  of  the  former  materials, 
namely,  clay,  can  be  accomplished  by  the  hands  alone  ; in  others,  as  alabaster  and  slate,  with  the  ordi- 
nary toothed  saws ; and  for  those  of  a harder  nature,  the  stone-saw,  fed  with  sand  and  water,  is  an 
economical  mode  of  dividing  them  with  great  exactness  and  little  waste,  from  their  original  forms 
to  those  in  which  they  are  ultimately  required,  and  which  is  greatly  facilitated  by  the  structure  of 
such  as  occur  in  stratified  beds ; but  the  use  of  the  stoue-saw  may  be  considered  to  cease  with  the 
sandstones. 

Different  and  far  more  troublesome  methods  of  working  are  necessary  with  those  materials  now  to 
be  considered,  that  are  much  harder,  and  in  which  the  existence  of  stratification  is  considered  but 
rarely  and  imperfectly  to  exist ; namely,  in  the  compact  and  cemented  porphyries,  principally  from 
Egypt  and  Sweden.  The  crystalline  granites,  and  some  other  varieties,  appear  to  merge  from  the 
porphyries  to  the  granites,  are  used  for  similar  purposes,  worked  by  the  same  means,  and  ask  for  an 
intermediate  position. 

In  detaching  the  masses  of  granitic  rock  from  their  natural  beds,  the  points  of  least  resistance  are 
first  determined  by  an  experienced  eye,  and  holes  are  sunk  at  those  points,  vertically  or  inclined,  as 
circumstances  may  require  : the  diameters  of  these  holes  vary  according  to  the  mass  and  the  amount 
of  resistance,  and  their  depths  according  to  the  thickness  of  the  blocks  to  be  detached. 

The  holes  are  made  with  an  iron  rod,  terminating  at  foot  in  a chisel-formed  edge  of  hardened  steel ; 
the  tool  is  held  by  one  man,  who  changes  its  position  at  every  blow  received  from  sledge-hammers 
worked  by  other  men  who  stand  around.  When  the  holes  are  thus  made  sufficiently  deep,  they  are 
charged  with  gunpowder,  in  order  to  effect  a separation  of  the  mass  by  blasting  ; the  ordinary  process 
of  tamping  confines  the  powder,  and  the  fuse  communicates  the  blast.  The  art  of  the  quarryman 
consists  in  placing  the  blast  (or  shot)  where  the  smallest  amount  of  powder  will  remove  the  largest 
mass  of  rock  with  the  least  breakage,  simply  dislodging  or  turning  it  over  ready  for  converting. 

In  converting  the  rude  masses  of  granite  to  their  intended  forms,  the  line  of  the  proposed  division 
is  first  marked,  and  holes  from  two  to  three  inches  deep,  and  four  to  six  inches  asunder,  are  bored  upon 
this  line,  by  means  of  an  iron  rod,  terminating  at  each  end  in  chisel-formed  edges  of  hardened  steel, 
with  a bulb  in  the  middle  to  add  weight ; this  tool,  called  a jumper,  is  made  to  fall  on  one  spot.  It 
rebounds,  and  is  partially  twisted  round  to  present  the  edge  continually  in  a different  angular  position. 
In  this  manner  a very  expert  workman  will  bore  about  a hundred  holes  a day.  Every  one  of  the 
holes  is  then  filled  with  two  half-round  pieces  of  iron,  called  feathers,  with  an  iron-pointed  wedge 
between  them ; the  wedges  are  progressively  and  equally  driven  until  the  stone  splits,  and  the 
fissure  will  be  in  general  moderately  flat,  even  should  the  mass  be  four  or  six  feet  thick,  although  in 
such  cases  the  holes  are  sometimes  continued  round  the  ends  also. 

The  scouters,  the  next  class  of  men,  employ  the  jumpers’  feathers  and  wedges  for  removing  any  large 
projections,  by  boring  holes  sideways,  and  thus  casting  off  large  flakes  ; the  spallers  employ  heavy  axe- 
formed  or  mrecMe-hammers,  for  spalling  or  scaling  off  smaller  flakes ; and  the  scablers  use  heavy  pointed 
picks,  and  complete  the  conversion,  so  far  as  it  is  effected  at  the  quarry,  ready  for  the  masons  employed 
in  erecting  the  buildings  for  which  the  blocks  are  used,  who  complete  their  formation  on  the  spot.  All 
these  materials  are  likewise  used  in  the  ornamental  arts. 

Porphyry  is  worked  in  the  lathe  with  remarkable  perfection,  and  many  excellent  specimens  from 
Sweden,  of  vases,  slabs,  pestles,  and  mortars,  and  bearings  intended  for  the  gudgeons  of  heavy 
machinery,  may  be  seen  in  London.  These  objects  are  first  worked  as  nearly  as  possible  to  the  re- 
quired forms  with  the  pick,  are  then  mounted  in  lathes  driven  by  water-power,  and  finished  by  grinding 
them  with  other  lumps  of  porphyry,  supplied  with  emery  and  water;  the  machinery  is  kept  going  day 
and  night,  and  the  gangs  of  men  relieve  one  another  at  certain  intervals. 

Granite  is  incapable  of  being  turned  in  the  lathe ; it  is  therefore  treated  like  porphyry,  that  is, 
shaped  with  heavy  picks,  and  finally  with  smaller  points  used  with  a hammer;  it  is  afterwards  ground 
with  circular  or  reciprocating  motion,  according  to  the  figure,  by  means-  of  iron  plates  fed  with  sharp 
sand,  next  with  emery,  progressively  finer  and  finer,  upon  wooden  rubbers,  the  endways  of  the  grain ; 
and  lastly,  the  polish  is  perfected  with  felt  rubbers  and  crocus.  The  process  is  tedious  and  difficult 
from  the  unequal  hardness  of  the  particles ; in  this  respect  granite  is  inferior  to  porphyry. 

Of  late  years  numerous  vases  and  other  circular  and  ornamental  objects  have  been  admirably  exe- 
cuted in  polished  granites  and  elvans,  which  occur  of  various  colors  and  degrees  of  hardness ; when 
decomposed  they  are  friable,  and  furnish  the  china  stones  extensively  used  as  one  of  the  materials  for 
porcelain  and  china,  and  also  for  making  very  refractory  crucibles. 

Agate,  jasper,  chalcedony,  cornelian,  <tc.,  are  all  composed  of  silex  nearly  pure ; they  break  in  general 


MINERAL  KINGDOM. 


417 


with  a conchoidal  fracture,  and  to  divide  them  into  plates  it  is  necessary  to  resort  to  the  lapidary  pro- 
cess'. They  may  be  slit  with  emery,  but  it  is  far  more  economical  to  employ  diamond  powder,  as  the 
time  then  required  is  only  one-third  of  that  called  for  when  emery  is  used ; these  stones  are  always 
ground  with  emery,,  and  polished  with  rotten-stone. 

Agate  is  used  as  the  bearing  planes  for  the  knife-edges  of  delicate  balances,  for  pestles  and  mortars, 
burnishers  for  gilders,  and  bookbinders,  and  also  for  some  other  purposes  in  the  mechanical  arts ; the 
whole  of  the  stones  in  this  group  are  largely  employed  for  the  purposes  of  jewelry,  the  handles  ol 
knives,  snuff-boxes,  and  a variety  of  ornaments. 

Topaz,  sapphire,  ruby. — These  may  be  split  with  plane  surfaces  through  their  natural  cleavages,  and 
which  method  is  continually  employed ; otherwise,  they  can  be  only  slit  with  the  diamond  powder. 
The  first  and  similar  stones  may  be  smoothed  with  emery,  but  emery  being  in  hardness  only  equal  to 
9,  produces  but  little  effect  upon  topaz,  upon  sapphire  and  ruby  it  is  almost  inert,  and  on  diamond  quite 
so ; the  sapphire  and  ruby,  and  also  diamonds,  are  therefore  always  polished  with  diamond  powder. 

On  account  of  the  peculiar  interest  attached  to  the  mechanical  applications  of  the  hard  gems,  it  is 
proposed  to  depart  a little  from  the  subject  and  order  of  these  pages,  to  advert  to  some  few  of  their 
uses,  which  may  not  be  generally  understood.  The  sapphire,  the  ruby,  and  also  the  diamond,  are  com- 
monly used  for  the  construction  of  certain  parts  of  the  best  time-pieces  and  watches,  such  as  the  pivot- 
holes,  pallets,  and  other  parts  of  the  escapements. 

The  jewelling  consists  mostly  of  two  stones : the  one,  commonly  sapphire  or  ruby,  is  turned  convex 
above  and  concave  beneath,  of  two  different  sweeps,  to  thin  it  away  at  the  part  where  it  is  to  be  pierced 
with  the  hole,  and  which  is  made  a little  smaller  in  the  middle  to  lessen  the  surface  bearing. 

The  other,  which  is  called  the  “ top-stone ,”  or  “ end-stone ,”  is  generally  a ruby,  in  the  form  of  a plano- 
convex lens,  or  else  it  is  a diamond  cut  into  facets ; the  flat  side  of  this  touches  the  end  of  the  pivot. 

Each  stone  is  burnished  into  a brass  or  steel  ring,  like  some  of  the  lenses  of  telescopes,  and  the  two 
stones  (separated  a slight  distance  for  the  retention  of  oil  by  capillary  attraction)  are  inlaid  in  a 
counter-sunk  recess  in  the  side-plate,  or  other  part  of  the  watch,  and  retained  therein  by  two  side- 
screws,  although  unimportant  variations  are  made  by  different  artists  in  the  shapes  and  proportions  of 
the  parts. 

The  delicacy  of  these  jewelled  holes  will  be  imagined,  when  it  is  added  that  in  the  axis  above  referred 
to,  the  pivot  is  the  one  two-hundredth  part  of  an  inch  diameter. 

The  wire  for  making  the  pendulum  springs  for  chronometers  is  sometimes  drawn  through  a pair  oi 
flat  rubies  with  rounded  edges ; the  stones  are  cemented  into  the  ends  of  metal  slides  having  screw 
adjustments.  Sometimes  two  pairs  of  rubies  are  placed  one  before  the  other,  to  constitute  a rectangular 
hole  of  variable  dimensions,  for  equalizing  the  wire  both  in  width  and  thickness. 

Rubies  and  other  gems  are  drilled  with  holes  conical  from  both  sides,  for  drawing  the  slender  silver 
gilt  and  silver  wires  used  in  the  manufacture  of  gold  and  silver  lace ; the  wires  are  afterwards  flattened, 
wound  spirally  upon  silk,  and  then  woven  into  the  lace.  Ruby  holes  are  also  employed  for  rounding 
the  leads  of  ever-pointed  pencils  ; but  for  this  use  they  are  chamfered  from  the  one  side  only,  and  the 
lead  is  pushed  through  from  the  small  side,  the  ruby  is  then  used  as  a cutting  tool ; ■whereas  the  hole 
in  the  draw-plate  is  slightly  rounded  upon  the  ridge,  and  acts  more  as  a burnisher  or  compresser;  the 
action  of  the  wire,  which  is  pulled  through  in  the  direction  of  the  arrow,  tends  to  draw  the  stone  more 
firmly  into  its  seat.  The  finest  holes  of  all  are  made  by  barely  allowing  the  point  of  the  drill  to  pene- 
trate into  the  apex  of  the  conical  hole,  previously  formed  on  the  opposite  side  of  the  ruby. 

All  these  applications  are  adopted  on  account  of  the  very  great  hardness  of  the  stone,  but  they  could 
scarcely  exist  were  there  not  one  substance  still  harder  than  the  ruby  to  serve  for  the  tools  by  which 
these  several  forms  are  wrought,  and  the  brief  consideration  of  which  will  now  be  proceeded  with. 

Diamond. — The  diamond  is  the  hardest  substance  in  nature,  and  in  common  with  some  other  crys- 
talline bodies,  it  is  harder  at  the  natural  angles  and  edges,  and  also  at  the  natural  coat  or  skin  of  the 
stone  than  within,  or  in  its  general  substance.  Its  peculiar  hardness  is  probably  altogether  due  to  its 
highly  crystalline  form,  as  by  analysis  the  diamond,  charcoal,  and  plumbago,  are  found  to  be  nearly 
identical ; the  first  is  absolutely  pure  carbon,  the  others  are  nearly  so. 

The  principal  use  of  the  diamond  is  for  jewelry,  its  preparation  for  which  will  be  touched  upon  in 
the  slightest  possible  manner ; but  from  its  peculiar  hardness  the  diamond  fulfils  some  more  really  im- 
portant although  less  brilliant  services  as  tools,  without  which  several  curious  and  highly  valuable 
processes  must  be  altogether  abandoned,  and  others  accomplished  in  an  inferior  although  more  costly 
manner  by  other  means. 

The  diamond  is  prepared  for  the  purposes  of  jewelry  by  three  distinct  processes,  namely,  splitting, 
cutting,  and  polishing,  which  will  be  adverted  to  in  a very  few  lines.  In  order  to  split  off  the  portions 
not  required,  the  stone  is  fixed  in  a ball  of  cement,  about  as  large  as  a walnut,  the  line  of  division  is 
sawn  a little  way  with  a pointed  diamond  fixed  in  another  ball  of  cement,  and  the  stone  is  afterwards 
split  with  the  blunted  edge  of  a razor  struck  with  a hammer ; the  small  fragments  removed,  when  they 
are  too  small  for  jewelry,  are  called  diamond  bort. 

In  cutting  diamonds,  two  stones  are  operated  upon  at  once ; they  are  cemented  in  the  ends  of  two 
sticks,  which  are  supported  on  the  edges  of  a box  three  or  four  inches  wide,  rested  against  two  pins 
as  fulcra,  and  forcibly  rubbed  against  each  other ; by  which  means  they  abrade  each  other  in  nearly  flat 
planes  and  remove  a fine  dust  called  diamond  powder,  which  falls  through  the  fine  holes  in  the  bottom 
of  the  box,  and  is  there  collected. 

The  diamonds  are  lastly  polished  upon  an  iron  lap  or  skive,  charged  with  diamond  powder,  the  stone 
being  guided  mechanically ; it  is  fixed  by  soft  solder  in  a copper  cup,  or  dop,  attached  by  a stout  copper 
wire  to  the  end  of  the  pincers,  a flat  board  terminating  at  the  other  extremity  in  two  feet,  which  rest 
upon  a fixed  support,  the  whole  forming  a long  and  very  shallow  triangular  stool,  loaded  at  the  end 
near  the  stone.  In  the  last  two  processes  the  stone  is  readjusted  for  producing  every  separate  facet. 
M e will  now  proceed  to  the  applications  of  the  diamond  as  tools. 

Vol.  II. — 27 


418 


MINERAL  KINGDOM. 


The  invaluable  instrument,  the  glazier’s  diamond,  although  employed  for  a consideral  le  period,  was 
for  the  first  time  investigated  scientifically  by  Dr.  Wollaston,  in  1816,  who  pronounced  its  operation  tc 
depend  upon  a peculiarity  of  crystallization  in  the  diamond,  the  facets  of  which  are  frequently  round 
instead  of  flat,  and  therefore  the  edges  are  circular  instead  of  straight.  The  rounded  edge  first  indents 
the  glass,  and  then  slightly  separates  its  particles,  forming-  a shallow  fissure,  with  a splitting  rather 
than  a cutting  action,  none  of  the  material  being  removed. 

The  primitive  form  of  the  diaitiond  is  that  of  a regular  octahedron;  it  is  like  two  square  pyramids 
joined  base  to  base ; the  four  sides  of  the  pyramids  meet  at  the  angle  of  90°,  their  bases  at  the  angle  of 
109°  or  thereabouts.  Many  of  the  diamonds  merge  from  the  form  of  the  octahedron  into  that  of  the 
sphere,  or  a very  long  egg,  in  which  cases  although  a disposition  to  the  development  of  the  six  points, 
each  formed  by  the  meeting  of  four  surfaces,  exists,  they  are  curiously  twisted  and  contorted.  The 
Count  de  Bournon  has  published  upwards  of  one  hundred  forms  of  crystallization  of  the  diamond,  but 
the  irregular  octahedrons  with  round  facets  are  those  proper  for  glaziers’  diamonds. 

The  extreme  point  of  any  diamond  may  be  employed  to  scratch  glass  with  a broad  white  streak,  and 
detach  its  particles  in  a powder,  hut  such  glass  will  break  with  difficulty,  (if  at  all,)  through  such  a 
scratch ; whereas  the  almost  invisible  fissure,  made  when  the  rounded  edge  is  slid  over  the  glass  with 
but  slight  pressure  and  almost  without  causing  any  sound,  is  that  which  produces  the  effective  cut;  and 
the  cut  or  split  thus  commenced  will  be  readily  extended  through  the  entire  thickness  of  the  glass, 
when  the  extremities  of  the  sheet  are  bent  with  the  fingers  or  appropriate  nippers. 

If  we  could  obtain  a diamond  in  the  form  of  a circular  button,  the  edges  of  which  were  turned  to  the 
angle  of  90  or  100  degrees,  it  would  be  the  perfection  of  the  instrument,  as  there  would  be  then  no 
point  to  interfere  with  its  action,  and  any  part  of  its  edge  might  be  used.  But  as  the  natural  diamond, 
unaltered  by  the  artisan,  is  always  employed,  it  must  be  so  applied  upon  the  glass,  that  one  of  its  curved 
edges  bears  upon  the  intended  line  of  division  of  the  glass,  and  with  the  extreme  point  just  out  of  con- 
tact : this,  in  so  small  an  object,  necessarily  confines  the  position  within  very  narrow  limits. 

The  patent  swivel  diamond  insures  the  one  condition,  by  placing  the  edge  of  the  stone  upon  the  line 
of  the  cut,  and  a few  trials  at  different  elevations,  generally  from  70  to  80  degrees,  will  soon  give  the 
other  position.  At  the  commencement  a slight  force  is  applied,  until  the  stone  appears  to  bite  or  hang 
to  the  glass,  it  is  then  drawn  steadily  along,  with  but  little  pressure,  and  the  good  cut  will  be  scarcely 
either  seen  or  heard. 

To  show  that  the  diamond  possesses  nothing  in  itself  that  should  adapt  it  to  cutting  glass,  beyond  its 
peculiar  form  and  hardness,  Dr.  Wollaston  succeeded  with  great  labor  in  giving  the  same  form  to  the 
ruby,  the  spinel  ruby,  topaz,  and  rock  crystal,  with  all  of  which  likewise  he  effected  the  cutting  of  glass, 
but  they  were  of  course  far  less  economical  than  the  natural  angle  of  the  diamond  itself,  which  requires 
no  such  tedious  preparation,  and  lasts  very  much  longer. 

It  must  not  be  supposed,  however,  the  diamond  endures  forever ; the  ordinary  painter  and  glazier 
may  use  one  diamond  throughout  his  lifetime,  by  having  it  reset  to  expose  other  angles ; but  in  some 
glass-works,  where  enormous  quantities  of  this  useful  material  are  cut  up,  the  consumption  of  diamonds 
amounts  to  one  and  two  dozen  or  upwards  every  week,  as  the  sides  from  being  convex,  become  rapidly 
concave,  and  the  principle  is  lost. 

The  following  figures  represent,  say  two  or  three  times  magnified,  the  forms  of  diamonds  that  would 
be  most  proper  for  various  tools ; but  it  will  be  remembered  they  are  only  selected  as  near  to  the 
respective  shapes  as  they  can  be  found,  either  amongst  imperfect  diamonds,  or  from  fragments  split  off 
good  stones  in  the  first  stage  of  their  manufacture  for  jewelry;  these  pieces  are  known  as  diamond 
bort.  The  diamonds  are  mostly  fixed  in  brass  wires,  by  first  drilling  a shallow  hole  for  the  insertion  of 
the  stone,  which  is  imbedded  slightly  below  its  largest  part,  and  the  metal  is  pinched  around  it.  Shel- 
lac is  also  used  for  cementing  them  in,  and  spelter  or  tin  solders  may  be  fused  around  them  with  the 
blow-pipe,  but  pinching  them  in  annealed  brass  is  preferred. 


2845. 

a b c d e f g h i k l 


When  diamond  tools  Larger  than  those  made  of  crystals  or  thin  splinters  are  required,  diamond 
powder  is  applied  upon  metal  plates  and  tools  of  various  forms,  which  serve  as  vehicles,  and  into  which 
the  particles  of  diamond  powder  are  imbedded,  either  by  slight  blows  of  the  hammer,  or  by  simple 
pressure. 

In  the  construction  of  the  jewelled  holes,  and  in  similar  works,  the  rubies  and  sapphires,  although 
sometimes  split,  are  more  commonly  slit  with  a plate  of  iron  three  or  four  inches  diameter,  mounted  on 
a lathe,  and  charged  on  the  edge  with  diamond  powder  and  oil.  When  sliced  they  are  ground  parallel 
one  at  a time  on  a flat  plate  of  copper,  (generally  a penny-piece,)  mounted  on  the  lathe,  and  into  the 
turned  face  of  which  small  fragments  of  diamond  have  been  hammered ; this  is  called  a roughing-milL 
A similar  plate  with  finely  washed  diamond  powder  is  used  for  polishing  them. 

The  rubies  are  afterwards  cemented  with  shellac,  on  the  end  of  a small  brass  chuck,  turned  cylin- 
drical on  their  edges,  and  bevelled  for  burnishing  into  the  metal  rings.  They  are  also  turned  concave 
and  convex  on  their  respective  faces,  the  turning  tool  being  a fragment  or  splinter  of  diamond,  fixed  in 
a brass  wire.  Fig.  a represents  the  flat  view,  and  Fig.  6 the  edge  view  of  such  a tool,  but  of  the 


MINES,  ENGINES  FOR. 


419 


form  more  usually  selected  for  turning  hardened  steel,  namely,  an  egg-shaped  diamond  split  in  two* 
the  circular  end  being  used  with  the  flat  surface  upwards ; the  watch  jeweller  uses  any  splinter  having 
an  angular  corner. 

The  convex  surfaces  of  the  rubies  are  polished  with  conceive  grinders  of  the  same  sweeps ; the  first  of 
copper,  the  next  glass,  and  the  last  pewter,  with  three  sizes  of  diamond  powder,  which  is  obtained  prin- 
cipally from  Holland,  from  the  men  who  cut  diamonds  for  jewelry,  an  art  which  is  more  extensively 
followed  in  that  country  than  elsewhere.  The  watch  jewellers  wash  this  powder  in  oil,  after  the  same 
manner  that  -will  be  hereafter  explained  in  regard  to  emery. 

In  drilling  the  rubies  they  are  chucked  by  their  edges,  and  a splinter  of  diamond,  also  mounted  in  a 
wire,  is  used.  Should  the  drill  be  too  conical,  the  back  part  is  turned  away  with  a diamond  tool  to  re- 
duce it  to  the  shape  of  Fig.  c,  and  from  the  crystalline  nature  of  the  stone,  some  facets  or  angles 
always  exist  to  cause  the  drill  to  cut.  The  holes  in  the  rubies  are  commonly  drilled  out  at  two  pro- 
cesses, or  from  each  side,  and  are  afterwards  polished  with  a conical  steel  wire  fed  with  diamond 
powder.. 

In  producing  either  very  small  or  very  deep  holes,  a fine  steel  wire,  Fig.  d,  is  used,  with  diamond 
powder  applied  upon  the  end  of  the  same,  the  limit  of  fineness  being  the  diameter  to  which  the  steel 
wire  can  be  reduced. 

In  drilling  larger  holes  in  china  and  glass,  triangular  fragments  of  diamond  are  fixed  in  the  cleft  ex- 
tremity of  a steel  wire,  as  in  Figs,  e and  /,  either  with  or  without  shellac.  Another  common  prac- 
tice of  the  glass  and  china  menders,  is  to  select  a tolerably  square  stone,  and  mount  it  as  in  Fig.  g 
in  the  end  of  a taper  tin  tube,  which  wears  away  against  the  side  of  the  hole  so  as  to  become  very 
thin,  and  by  the  pressure  to  embrace  the  stone  by  the  portions  intermediate  between  its  angles. 

The  stone  is,  from  time  to  time,  released  by  the  wearing  away  of  the  metal,  but  these  workmen  are 
dexterous  in  remounting  it;  and  that  the  process  is  neither  difficult  nor  tedious  to  those  accustomed  to 
it,  is  proved  by  the  trifling  sum  charged  for  repairing  articles,  even  when  many  of  the  so-called  rivets 
or  rather  staples  are  cemented  in ; they  employ  the  upright  drill  with  a cross  staff. 

A similar  diamond  drill  mounted  in  brass  was  used  by  Mr.  Ellis,  with  the  ordinary  drill-bow  and 
breast-plate  for  drilling  out  the  hardened  steel  nipple  of  a gun,  which  had  been  broken  short  off  in  the 
barrel ; no  material  difficulty  was  experienced,  although  the  stone  appeared  to  be  so  slenderly  held. 

For  larger  holes,  metal  tubes  such  as  Fig.  h,  fed  with  diamond  powder,  are  used ; they  grind  out 
an  annular  recess,  and  remove  a solid  core  ; copper  and  other  tools  fed  with  emery  or  sand  may  be  thus 
used  for  glass,  marble,  and  various  other  substances.  The  same  mode  lias  been  adopted  for  cutting  out 
stone  water-pipes  from  within  one  another  by  the  aid  of  steam  machinery. 

Fig.  i represents  the  conical  diamond  used  by  engravers  for  the  purpose  of  etching,  either  by 
hand  or  with  the  various  machines  for  ruling  etching  grounds ; for  ruling  medals  and  other  works. 
Conical  diamonds  are  turned  in  a lathe  by  a fragment  of  another  diamond,  the  outside  skin  or  an  angle 
being  used,  but’ the  tool  suffers  almost  as  much  abrasion  as  the  conical  point,  from  their  nearly  equal 
hardness ; therefore  the  process  is  expensive,  although  when  properly  managed  entirely  successful. 

To  conclude  the  notice  of  the  diamond  tools,  Figs,  k and  L show  the  side  and  end  views  of  a 
splinter  suitable  for  cutting  fine  lines  and  divisions  upon  mathematical  instruments.  The  similitude 
between  this  and  the  glazier’s  diamond  will  be  remarked,  but  in  the  present  case  the  splinter  is  selected 
with  a fine  acute  edge,  as  the  natural  angle  would  be  too  obtuse  for  the  purpose. 

Mr.  Ross,  with  a diamond  point  of  this  kind,  was  enabled  to  graduate  ten  circles  upon  platinum, 
each  degree  subdivided  into  four  parts ; at  the  end  of  which  time  the  diamond,  although  apparently 
none  the  worse,  was  accidentally  broken.  A steel  point  would  have  suffered  in  the  graduation  of  only 
one-third  of  a single  circle  upon  platinum,  so  as  to  have  called  for  additional  pressure  with  the  progress 
of  the  work,  which  in  so  delicate  an  operation  is  of  course  highly  objectionable. 

MINES,  ENGINES  FOR.  The  locality  of  a mine  will  determine  the  manner  in  which  it  ought  to 
be  drained.  Where  the  mine  is  situated  on  the  top  or  side  of  a hill,  a shaft  is  led  from  the  bottom  ol 
the  mine  to  the  nearest  valley,  and  the  water  runs  off  in  this  way  without  the  application  of  pumps 
wrought  by  steam-engines.  Where  the  mine  is  situated  in  a level  country  pumping  becomes  neces- 
sary; and  should  the  mine  be  deep,  say  from  100  to  150  fathoms,  very  powerful  steam-engines  are 
required.  Where  the  pumping  requires  great  power,  suppose  of  200  horses,  it  is  better  to  construct 
two  small  engines  than  one  large  one.  Where  a single  engine  is  used  one  set  of  pumps  are  wrought, 
and  the  ascending  motion  of  the  piston  is  employed  to  raise  a weight  equal  to  half  the  pressure  of  the 
water  in  the  pumps.  Where  two  engines  are  used  there  are  commonly  two  sets  of  pumps,  one  set 
wrought  by  a diagonal  spear  attached  to  the  piston  end  of  the  beam,  and  the  other  set  are  wrought  by 
the  other  end.  Steam-engines  for  mines  should  be  simple  in  form  and  proportioned  to  the  work  they 
have  to  perform.  The  pump-shaft  is  divided  into  lifts,  which  should  not  exceed  180  feet  each;  there 
is  a cistern  for  the  reception  of  the  water,  at  the  top  of  each  lift.  Rather  than  make  the  diameter  ol 
the  pump  more  than  sixteen  inches  an  additional  set  should  be  added.  Mining  work  is  irregular, 
more  resistance  having  to  be  overcome  at  one  time  than  another.  Tredgold  gives  it  as  his  opinion 
that  an  engine  does  good  duty  when  it  raises  70,000  lbs.  of  ore  by  the  consumption  of  one  pound  of  coal. 
The  weight  to  be  raised  at  one  draught  varies  from  3 to  7 hundred  weight.  Engines  at  mines  are  some- 
times used  to  break  the  ore  by  means  of  stampers. 

For  a more  complete  treatise  on  mines,  see  lire's  Dictionary  of  Mines.  For  the  engines  used,  see 
article  Pumps  and  Pumping,  as  also  Engines,  in  this  Dictionary. 

MINT.  See  Coining. 

MODULUS.  The  modulus  of  the  elasticity  of  any  substance  is  a column  of  the  same  substance, 
capable  of  producing  a pressure  on  its  base  which  is  to  the  weight  causing  a certain  degree  of  compres- 
sion, as  the  length  of  the  substance  is  to  the  diminution  of  its  length. 

The  modulus  of  elasticity  is  the  measure  of  the  elastic  force  of  any  substance. 

A practical  notion  of  the  modulus  of  elasticity  may  be  readily  obtained.  Let  c be  the  quantity  a bat 


420 


MODULUS. 


of  wood,  iron,  or  other  substance,  an  inch  square  and  a foot  in  length,  would  be  extended  or  diminished 
oy  the  force  /;  and  let  l be  any  other  length  of  a bar  of  equal  base  and  like  substance ; then 
1 : l : : t : A,  or  1 c = A,  the  extension  or  diminution  in  the  length  l. 

The  modulus  of  elasticity  is  found  by  this  analogy  : as  the  diminution  of  the  length  of  any  substance 
is  to  its  length,  so  is  the  force  that  produced  that  diminution  to  tlie  modulus  of  elasticity.  Or,  denoting 
the  weight  of  the  modulus  in  lbs.  for  a base  of  an  inch  square  by  m \ it  is 


And,  if  to  be  the  weight  of  a bar  of  the  substance  one  inch  square  and  one  foot  in  length ; then,  if  M ba 
the  height  of  the  modulus  of  elasticity  in  feet,  we  have 

— M. 


When  a force  is  applied  to  an  elastic  column  of  a rectangular  prismatic  form  in  a direction  parallel 
to  the  axis,  the  parts  nearest  to  the  line  of  direction  of  the  force  exert  a resistance  in  an  opposite  direc- 
tion ; those  particles,  which  are  at  a distance  beyond  the  axis,  equal  to  a third  proportional  to  the 
depth,  and  twelve  times  the  distance  of  the  line  of  direction  of  the  force,  remain  in  their  natural  state ; 
and  the  parts  beyond  them  act  in  the  direction  of  the  force. 

The  weight  of  the  modulus  of  the  elasticity  of  a column  being  in,  a weight  bending  it  in  any  manner 
f the  distance  of  the  line  of  its  application  from  any  point  of  the  axis  D,  and  the  depth  of  the  column  d, 
(H 2 

the  radius  of  curvature  will  be  — — - . 

1-2  D/ 

If  a beam  is  naturally  of  the  form  which  a prismatic  beam  would  acquire,  if  it  were  slightly  bent  by 
a longitudinal  force,  calling  its  depth  d,  its  length  l,  the  circumference  of  a circle  of  which  the  diameter 
is  unity  c , the  weight  of  the  modulus  of  elasticity  m,  the  natural  deviation  from  the  rectilinear  form  a', 
and  a force  applied  at  the  extremities  of  the  axis  f the  total  deviation  from  the  rectilinear  form  will  be 

, d2  c2  A in 

^ d 2 c2  m — 12  l2f 


Scholium  — It  appears  from  this  formula,  that  when  the  other  quantities  remain  unaltered,  a'  varies 
in  proportion  to  A,  and  if  A = O,  the  beam  cannot  be  retained  in  a state  of  inflection,  while  the  denomi- 
nator of  the  fraction  remains  a finite  quantity : but  when  d2  c2  in  = 12  Pf  a'  becomes  infinite,  whatever 
may  be  the  magnitude  of  A,  and  the  force  will  overpower  the  beam,  or  will  at  least  cause  it  to  bend  so 

(f/  c\  ^ 

-f)  * 1 


d2 

8225  -yin, 


which  is  the  force  capable  of  holding  the  beam  in  equilibrium  in  any  inconsiderable  degree  of  curva- 
ture. The  modulus  being  known  for  any  substance,  we  may  determine  at  once  the  weight  which  a 
given  bar  nearly  straight  is  capable  of  supporting.  For  instance,  in  fir  wood,  supposing  its  height 
10,000,000  feet,  a bar  an  inch  square  and  ten  feet  long  may  begin  to  bend  with  the  weight  of  a bar  of 

the  same  thickness,  equal  in  length  to ‘8225  X ^ pm  ^ 10,000,000  feet,  or  571  feet;  that  is,  with 


a weight  of  about  120  pounds  ; neglecting  the  effect  of  the  weight  of  the  bar  itself.  In  the  same  man- 
ner the  strength  of  a bar  of  any  other  substance  may  be  determined,  either  from  direct  experiments  on 

771  I?  I 

its  flexure,  or  from  the  sounds  that  it  produces.  If/=  — , = ’8225  n,  and  — = (’8225  n ) = -907 


y/  n ; whence,  if  we  know  the  force  required  to  crush  a bar  or  column,  we  may  calculate  what  must  be 
the  proportion  of  its  length  to  its  depth,  in  order  that  it  may  begin  to  bend  rather  than  be  crushed. 

The  weight  of  the  modulus  of  the  elasticity  of  a bar  is  to  a weight  acting  at  its  extremity  only,  as 
four  times  the  cube  of  the  length  to  the  product  of  the  square  of  the  depth  and  the  depression. 

If  an  equable  bar  be  fixed  horizontally  at  one  end,  and  bent  by  its  own  weight,  the  depression  at  the 
extremity  will  be  half  the  versed  sine  of  an  equal  arc  in  the  circle  of  curvature  at  the  fixed  point. 

The  height  of  the  modulus  of  the  elasticity  of  a bar,  fixed  at  one  end,  and  depressed  by  its  own  weight, 
is  half  as  much  more  as  the  fourth  power  of  the  length  divided  by  the  product  of  the  square  of  the 
depth  and  the  depression. 

The  depression  of  the  middle  of  a bar  supported  at  both  ends,  produced  by  its  own  weight,  is  five- 
sixths  of  the  versed  sine  of  half  the  equal  arc  in  the  circle  of  least  curvature. 

The  height  of  the  modulus  of  the  elasticity  of  a bar,  supported  at  both  ends,  is  of  the  fourth  power 
of  the  length,  divided  by  the  product  of  the  depression  and  the  square  of  the  depth. 

From  an  experiment  made  by  Mr.  Leslie  on  a bar  in  these  circumstances,  the  height  of  the  modulus 
of  the  elasticity  of  deal  appears  to  be  about  9,328,000  feet.  Chladni’s  observations  on  the  sounds  of  fir 
wood  afford  very  nearly  the  same  result. 

The  modulus  of  elasticity  has  not  yet  been  ascertained  in  reference  to  so  many  subjects  as  could  be 
wished.  Professor  Leslie  exhibits  several,  however,  as  below.  That  of  white  marble  is  2,150,000  feet, 
or  a weight  of  2,520,000  pounds  avoirdupois  on  the  square  inch ; while  that  of  Portland  stone  is  only 
1,570,000  feet,  corresponding  on  the  square  inch  to  the  weight  of  1,530,000  lb. 

White  marble  and  Portland  stone  are  found  to  have,  for  every  square  inch  of  section,  a cohesive 
power  of  1811  lb.  and  857  lb.;  wherefore,  suspended  columns  of  these  stones,  of  the  altitude  of  1542 
and  945  feet,  or  only  the  1394th  and  1789th  part  of  their  respective  measure  of  elasticity,  would  be 
torn  asunder  by  their  own  weight.  . . . 

Of  the  principal  kinds  of  timber  employed  in  building  and  carpentry,  the  annexed  table  will  exhibit 


MORTAR. 


421 


their  respective  modulus  of  elasticity,  and  the  portion  of  some  of  them  'which  limits  their  cohesion,  oi 
which  lengthwise  would  tear  them  asunder. 


3.600.000 

5.100.000 
'7,400,000 
6,000,000 

5.100.000 

6.200.000 
4,350,000 


Teak 

....  6,040,000  feet 

168th. 

Oak 

....  4,150,000  feet 

144th. 

Sycamore 

....  3,860,000  feet.'  

108  th. 

Beech 

....  4,180,000  feet 

107th. 

Ash 

....  4,617,000  feet 

109th. 

Elm  

....  5,680,000  feet 

146th. 

Mernel  fir 

8,292,000  feet 

Christiana  deal 

....  8,118,000  feet 

146th. 

Larch 

....  6,096,000  feet.  

121st. 

feet. 

Steel 9,300,000 

Bar-iron 9,000,000 

Ditto 8,450,000 

Yellow  pine 9,150,000 

Ditto 11,840,000 

Finland  deal 6,000,000 

Mahogany *7, 500, 000 


Rosewood 

Oak,  dry  

Fir  bottom,  25  years  old  . 

Petersburg  deal 

Lancewood  

Willow  

Oak  


Annexed  we  give  a table  of  the  modulus  of  cohesion,  or  the  length  in  feet  of  any  prismatic  substance 
required  to  break  its  cohesion,  or  tear  it  asunder. 


feet. 

27.000 
8,000 
6,700 

79.000 

14.000 
970 
144 
300 

7,300 


Teak 

12,915  lb 

36,049  feet. 

Oak 

11,880  1b 

32,900  feet. 

Sycamore  

9,630  lb 

Beech  

12,225  Hi 

38,940  feet. 

Ash 

14,130  lb 

Elm 

9,720  lb 

39,050  feet. 

Mem  el  fir  

9^540  lb 

Christiana  deal 

12,346  lb 

Larch 

12,240  lb 

42,160  feet. 

feet. 

Tanned  cow’s-skin  10,250 

calf-skin 5,050 

horse-skin  7,000 

cordovan  3,720 

sheep-skin 5,600 

ITntanned  horse-skin  8,900 

Old  harness  of  30  years 5,000 

Hempen  twine  75,000 

Catgut,  some  years  old 23,000 


Garden  matting  

Writing-paper,  foolscap 

Brown  wrapping-paper,  thin 

Bent  grass,  (holcus)  

Whalebone  

Bricks,  (Fenny  Stratford)  — 

(Leighton) 

Ice 

Leicestershire  slate  


MOMENTUM,  in  mechanics,  is  the  same  with  impetus,  or  quantity  of  motion,  and  is  generally  esti- 
mated by  the  product  of  the  velocity  and  mass  of  the  body.  This  is  a subject  whicJi  has  led  to  various 
controversies  between  philosophers,  some  estimating  it  by  the  mass  into  the  velocity,  as  stated  above, 
while  others  maintain  that  it  varies  as  the  mass  into  the  square  of  the  velocity.  But  this  difference 
seems  to  have  arisen  rather  from  a misconception  of  the  term,  than  from  any  other  cause.  Those  who 
maintain  the  former  doctrine,  understanding  momentum  to  signify  the  momentary  impact ; and  the 
latter,  as  the  sum  of  all  the  impulses  till  the  motion  of  the  body  is  destroyed.  See  Force. 

MORTAR.  A mixture  of  slaked  lime  in  the  state  of  paste  with  sand ; it  possesses  the  property, 
when  spread  in  thin  layers  between  bricks,  of  gradually  hardening  to  the  consistence  of  limestone,  and 
thus  cementing  the  bricks  together.  In  order  to  understand  the  principles  upon  which  mortar  is  mixed, 
it  is  necessary  to  become  acquainted  with  certain  facts  which  here  exert  the  greatest  influence. 

Conditions  of  hardening. — Simple  lime,  in  the  state  of  paste,  likewise  hardens,  but  only  to  form  a 
loose  mass  of  too  slight  consistency  to  bind  the  parts  of  a wall  or  building  firmly  together.  It  is  only 
when  the  layer  of  lime  forms  a very  thin  stratum,  as  between  two  polished  stones,  that  a firm  and  solid 
cement  is  produced.  The  lime  must  be  prevented  from  forming  masses  of  any  considerable  thickness, 
as  these  always  possess  a very  slight  degree  of  cohesion.  The  lime  attaches  itself  firmly  only  to  the 
surface  of  the  building-stones,  which  differ  from  it  in  character,  and  this  surface  should  be  extended,  as 
it  were,  by  mixing  a,  granular  powder  with  the  lime.  This  leads  directly  to  the  object  and  use  of  sand 
in  the  mortar,  which  is  only  intended  to  bring  about  more  intimate  contact  between  the  surfaces  of  the 
stones  and  the  lime.  The  shape  of  the  bricks  and  hewn  stones  is  so  irregular,  that  crevices  of  a line  at 
least,  and  in  hewn  stones  often  of  an  inch  in  width,  are  left  between  them  when  laid  one  upon  another. 
Lime  alone  placed  between  the  stones,  would  consequently  be  in  layers  of  a line  to  an  inch  in  thickness, 
and  in  such  masses  would  never  bind.  If,  however,  a sandy  powder  of  any  kind  of  stone  is  mixed  with 
it,  the  mass  of  lime  is  thus  divided  into  a great  number  of  thin  layers,  or,  as  it  were,  fills  up  the  inter- 
stices between  the  sand,  and  finding  everywhere  points  of  attachment,  binds  the  grains  of  sand  together, 
and  extends  this  binding  action  to  the  stones  themselves. 

It  is  further  known  that  even  the  best  mortar,  when  quickly  dried,  as,  for  instance,  on  the  stove,  does 
not  harden,  but  remains  friable  and  porous.  Although,  therefore,  mortar  placed  under  water  remains 


422 


MORTAR, 


porous  and  'will  not  bind,  yet  the  action  of  moisture  is  essential  to  make  it  harden  in  the  air.  Lastly,  th* 
tree  access  of  air  is  also  absolutely  necessary  to  the  setting  of  mortar. 

Proportions  of  mixture. — When  these  facts  are  borne  in  mind,  the  rules  to  be  observed  in  mixing 
mortar  will  be  obvious.  Although  many  kinds  of  stone  in  the  form  of  coarse  sand  are  applicable  for 
making  mortar,  as  limestone,  for  instance,  yet  quartz-sand  is  always  most  easily  obtained;  the  grain  ol 
the  sand,  however,  is  a matter  of  some  importance.  Very  fine  sand  renders  the  mortar  too  dense,  and 
impedes  the  free  access  of  air ; sand  in  grains  of  the  size  of  hay-seed,  particularly  if  it  is  angular  or 
sharp,  is  very  good ; the  interstices  become  too  large  to  be  entirely  filled  with  lime  if  very  coarse  sand 
is  employed.  It  is  then  advantageous,  particularly  when  irregularly  shaped  building-stones  are  used, 
to  mix  two  kinds  of  sand  together,  coarse  and  fine.  Fine  sand  can  only  be  mixed  with  the  lime  when 
the  mortar  is  intended  for  a thin  coating  upon  the  surface  of  walls,  &c.  The  more  irregular  the  sand  is, 
the  better.  The  proper  proportion  of  sand  and  lime  is  a most  important  point  in  preparing  mortar; 
and  the  good  quality  and  solidity  of  the  mortar  are  more  influenced  by  it  than  by  any  thing  else. 
Errors  committed  in  the  mixing  can  never  be  subsequently  corrected. 

As  a general  rule,  the  lime  should  be  sufficiently  fine  to  cement  all  the  grains  of  sand  together,  but 
should  form  at  the  same  time  the  thinnest  possible  stratum  between  them.  The  surfaces  of  the  grains 
of  sand,  or  the  interstices  between  them,  should  therefore  be  only  just  covered  with  the  lime  in  a half- 
liquid state,  and  no  more.  The  rule  might  be  laid  down  in  the  following  terms:  let  as  much  lime  be 
mixed  with  the  sand  as  it  will  take  up  without  having  its  volume  increased.  Practically,  about  3 to  4 
cubic  feet  of  sand  (or  6 times  the  weight)  are  added  to  1 cubic  foot  of  half-liquid  lime,  provided  the  lime 
be  fat,  or  very  fat ; poor  lime,  which  may  be  viewed  as  already  containing  a certain  portion  of  sand,  will 
not  bear  the  addition  of  more  than  2£  cubic  feet  of  sand  to  1 cubic  foot  of  lime.  The  sand  should  be 
pure,  i.  e.,  it  should  not  contain  too  much  iron  or  clay,  and  least  of  all,  bog-earth,  or  vegetable  matter. 

Hardening  or  setting — time  required. — Although  mortar  sets  sufficiently  in  a few  days,  or  weeks,  to 
enable  a wall  to  withstand  pressure  and  the  like,  yet  the  hardening  proceeds  so  slowly  and  gradually, 
that  it  only  attains  its  maximum  (in  which  case  a wall  appears  as  if  constructed  of  one  piece  of  stone) 
after  years,  or  even  centuries.  The  apparent  superiority  of  mortar  in  olden  times  over  that  in  the 
present,  is  solely  attributable  to  the  longer  time  which  has  been  allowed  it  to  harden  and  set,  as  no 
essential  difference  can  be  traced  in  the  mixture  of  the  ingredients.  Although  we  see,  on  the  one  hand, 
that  old  buildings  can  only  be  destroyed  with  the  aid  of  powder,  yet  it  must  not  be  forgotten  on  the 
other,  that  in  some  buildings  the  direct  converse  is  observed,  and  that  the  durable  portions  only  have 
been  enabled  to  withstand  the  ravages  of  time,  while  the  weaker  and  less  durable  parts  have  long  since 
disappeared.  In  the  same  manner,  it  is  probable  that  some  buildings  erected  in  our  own  age  will  stand 
forward  to  posterity  as  patterns  of  solid  architecture,  just  as  those  of  the  middle  ages  and  of  the  ages  of 
Grepce  and  Rome  appear  to  us  at  preseut. 

Cause  of  setting. — The  hardening  of  mortar  upon  exposure  to  the  air  is  not  so  easily  explained  as 
would  at  first  appear.  It  has  even  been  disputed  whether  it  is  the  result  of  mere  physical  (mechan- 
ical) or  only  of  chemical  agencies.  And  it  appears  probable,  when  every  thing  is  taken  into  consider- 
ation, that  the  hardening  cannot  be  attributed  to  any  one  cause  in  particular,  but  to  all  collectively,  and 
in  such  a manner  that  the  formation  of  a silicate  of  lime  and  crystallization  are  the  causes  of  the  durable 
solidity  and  conversion  into  stone,  while  the  absorption  of  carbonic  acid  induces  the  rapid  setting  of 
the  mortar. 

The  hydraulic  mortar  employed  in  building  the  Eddystone  lighthouse  was  mixed  by  Smeaton  from 
equal  proportions  of  lime,  slaked  to  powder,  and  Puzzolana.  Trass  and  Puzzolana  are  generally  mixed 
with  one-half  their  weight  of  lime,  as  was  the  practice  amongst  the  Romans.  It  is  desirable  to  ascer- 
tain the  best  proportions  by  experiment  in  all  cases  where  no  certain  knowdedge  of  the  nature  of  the 
two  substances  can  be  obtained. 

Good  hydraulic  mortar,  whether  made  from  natural  limestone  or  composed  of  lime  and  cement,  should 
not  show  any  tendency  to  crack  when  hardened  under  water,  even  when  no  sand  is  mixed  with  it.  It 
then  forms  a very  dense  and  solid  mass,  which,  in  a short  time,  neither  suffers  water  to  permeate  it,  nor 
is  attacked  by  the  water,  but  acquires  a considerable  degree  of  hardness.  For  this  reason,  it  is  well  to 
use  nothing  but  hydraulic  mortar  for  those  parts  of  walls  which  are  constantly  under  water.  If  the 
mortar  is  not  only  required  to  harden,  but  also  to  bind  well,  a very  important  point  must  never  be  neg- 
lected, and  that  is  to  moisten  the  surfaces  of  the  stones  to  which  the  mortar  is  to  be  applied.  When 
this  is  not  done,  the  surface  of  the  stone  (by  its  power  of  absorbing  moisture)  dries  the  mortar,  and  pre- 
vents proper  adhesion  from  taking  place ; the  joint  then  remains  open  to  a greater  or  lesser  extent. 

It  does  not  by  any  means  follow,  that  because  hydraulic  mortar  is  the  only  durable  material  for 
building  under  water,  it  cannot  consequently  be  used  for  dry  walls.  It  is,  on  the  contrary,  of  the  great- 
est service  wherever  protection  is  required  against  the  infiltration  of  moisture  and  damp ; and  dwellings 
or  buildings  can  often  be  rendered  very  much  less  damp  by  a judicious  application  of  a hydraulic  coat- 
ing ; a layer  of  this  kind,  when  once  hardened,  is  not  calculated,  like  ordinary  mortar,  to  attract  moisture 
and  allow  it  to  pass  through.  The  hydraulic  mortar  must,  of  course,  when  used  for  covering  dry  walls 
or  otherwise,  be  kept  moist  and  watered,  until  it  has  acquired  its  proper  degree  of  hardness.  If  this  is 
not  attended  to,  a soft,  friable,  useless  coating  is  the  certain  result.  If  moisture  enters  from  below,  for 
instance,  between  the  wall  and  the  coating  of  mortar,  it  will  continue  confined  there  in  consequence  of 
the  impenetrability  of  the  latter,  which,  on  the  occurrence  of  a frost,  will  most  certainly  peel  off  and  be 
destroyed.  Care  must  also  be  taken  that  the  mortar  does  not  dry  up  of  itself  immediately  in  the  air,  in 
which  case  it  contracts  and  cracks.  It  is,  therefore,  necessary  to  add  sand  or  some  other  substance  which 
obviates  the  shrinking.  Hydraulic  mortar  will  bear  a very  considerable  quantity  of  sand  without  injury 
to  its  hardness,  even  as  much  as  one  and  a half  times  its  own  weight  and  more.  This  addition,  there- 
fore, is  important  in  an  economical  point  of  view.  The  grain  of  the  sand  employed,  however,  requires 
attention,  as  was  the  case  with  ordinary  mortar  ; sharp,  angular  sand  is  decidedly  preferable  to  blunt, 
taunded  sand,  and  it  is  better  to  use  a mixture  of  coarse  with  fine  sand,  than  that  the  sand  should  be 


MORTAR. 


423 


all  of  the  same  sized  grain.  The  sand  should  likewise  be  as  free  as  possible  from  earthy  particles  and 
dust.  In  mortar  composed  of  lime  and  cement,  the  rule  is,  to  proportion  the  sand  to  the  quantity  ol 
cement  used.  Slaked  lime  will  not  bear  more  than  a certain  quantity  of  these  substances,  which  quan- 
tity must  not  be  exceeded,  the  cement  itself  being  for  the  greater  part  inactive,  and  playing  the  pari 
of  sand. 

Hydraulic  mortar  that  sets  with  sufficient  rapidity,  and  to  which  a proper  proportion  of  sand  has  been 
added,  may  be  employed  for  casting  tolerably  massive  objects,  which  are  not  subject  to  crack  when  dry. 
This  enables  hydraulic  mortar  to  be  employed  for  architectural  ornaments  which  then  combine  great 
sharpness  with  durability,  are  very  light  as  compared  with  similar  figures  of  sandstone,  and  have  the 
great  advantage  of  being  easily  multiplied. 

A similar  application  is  that  for  casting  water-pipes,  on  the  spot  where  they  are  required,  as  pro- 
posed by  Gasparin.  The  mould  employed  is  a linen  hose,  like  those  attached  to  the  fire-engines,  a few 
meters  in  length,  which  is  filled  with  water  and  closed  at  both  ends.  A thick  kind  of  bolster  is  thus 
produced,  over  which  sand  is  sifted,  and  it  is  then  laid  upon  a deposit  of  hydraulic  lime  and  covered, 
by  pouring  over  it  the  same  substance.  When  the  whole  has  hardened,  the  hose  is  drawn  forwards, 
about  the  length  of  one  foot  being  left  inserted  in  the  tube,  and  a fresh  length  is  cast.  Water-courses 
thus  constructed  must,  however,  have  a certain  amount  of  fall,  or  the  sand  cannot  be  washed  out,  and 
will  impede  the  delivery  of  the  water. 

When  hydraulic  lime  is  mixed  with  small  stones,  or  with  shingles  from  the  bed  of  a river,  or  the  sea, 
walls  can  be  directly  constructed  of  it,  and  a mass  is  obtained  which  resembles  the  erections  with  ordi- 
nary mortar,  and  is  called  beton  by  the  French. 

At  Toulon  a mixture  was  used  for  the  construction  of  the  harbor  consisting  of  3 parts  lime,  4 Puzzo- 
lana,  1 smithy  ashes,  2 sand,  and  4 parts  of  rolled  stones  or  shingles. 

The  great  strength  of  walls  constructed  with  hydraulic  mortar  is  most  clearly  shown  by  the  experi- 
ments undertaken  with  a view  to  break  beams  constructed  of  brick-work.  A 25  feet  long  and  2-J-  feet 
wide  beam,  constructed  with  19  layers  of  bricks,  bound  together  by  Roman  cement,  in  which,  here  and 
there,  parallel  strips  of  iron  were  inclosed,  was  capable  of  bearing,  when  supported  at  both  ends,  a 
weight  of  22  tons,  suspended  from  the  middle,  before  it  showed  signs  of  fracture. 

Mr.  Frederick  Ransome  has  lately  taken  a patent  for  preparing  different  articles  with  a kind  of  vitri- 
fied cement.  The  following  is  the  principle  of  his  process  : 

Flints  are  suspended  in  wire  baskets  in  a boiler  of  caustic  alkali,  which  is  heated  to  about  300°  Fahr, 
under  a pressure  of  50  to  80  pounds  per  square  inch.  A solution  is  thus  obtained  of  silicate  of  soda  o 
potash,  (of  a specific  gravity  of  from  about  1'3  to  1'6.) 

This  is  the  cementing  substance,  the  composition  of  which  is  said  to  be 

Silica 20'43 

Soda 2T05 

Water 52-52* 

100-00 

One  part  of  this  liquid  cement  is  ground  up  with  one  part  of  pipe-clay  and  one  part  of  powdered  flint, 
which  are  well  mixed  in  a pug-mill  with  10  parts  of  sand  or  road-drift.  The  mixture  is  pressed  into 
plaster  moulds,  and  is  then  dried  in  the  air  on  flat  surfaces,  to  prevent  warping.  It  can  now  be  handled, 
and  is  stove-dried  previously  to  being  placed  in  a potter’s  kiln,  where  it  is  heated  slowly  for  24  hours, 
and  up  to  a fair  red-heat  for  24  hours  more,  and  then  gradually  cooled  during  5 days. 

This  gradual  annealing  is  essential,  because  the  silicate  of  soda,  during  the  firing,  takes  up  more  silica 
and  alumina  from  the  flint  and  clay,  forming  a true  insoluble  glass,  which  would  crack  if  not  properly 
annealed.  The  stone  is  not  affected  by  boiling  in  nitric  acid,  which  proves  that  an  insoluble  glass  has 
been  formed. 

Sand  and  road-drift  produce  a white  stone  suitable  for  the  face  of  ornaments,  which  are  backed  up 
with  composition  made  of  loam  and  silicate  of  soda. 

According  to  the  quantity  of  silicate  of  soda  used,  the  stone  may  be  either  porous  or  impervious.  It 
sufficient  is  used  to  fill  up  all  the  interstices  between  the  grains  of  sand,  the  stone  will  be  impervious. 
Some  of  Mr.  Ransome’s  stone  has  been  exposed  for  two  years  to  the  weather  without  the  sharp  edges 
being  in  the  slightest  degree  injured ; many  porous  stones  will  stand  weather  and  frost  better  than  im- 
pervious ones,  and  it  is  therefore  still  a question  whether  this  stone  will  resist  the  action  of  air  and  rain 
loaded  with  sulphurous  acid,  as  is  the  case  in  London.  Some  of  the  blocks  of  stone  quarried  at  the 
island  of  Portland  for  St.  Paul’s  Cathedral,  and  left  there,  are  now  quite  perfect,  whilst  the  stones  in  the 
Cathedral  have  become  very  much  decayed. 

Mr.  Ransome  in  his  patent,  22d  October,  1844,  merely  directs  the  stone  to  be  dried  at  212°  Fahr.,  or 
at  a higher  temperature,  and  does  not  say  any  thing  about  baking  it ; he  directs  about  one-sixth  part 
of  the  silicate  to  be  used  in  the  mixture. f It  was  stated  at  the  Institution  of  Civil  Engineers,  that  slabs 
of  7 feet  long  by  9 in.  X 3 in.  had  been  made  perfectly  flat  and  true,  and  that  the  reason  they  did  not 
warp  was,  that  the  particles  of  sand  were  in  contact  with  one  another,  and  the  cement  only  filled  the 
interstices.  If,  on  the  contrary,  too  much  cement  were  used,  the  shrinking  of  the  cement  would  warp 
the  slabs.  Square  blocks  of  this  stone,  we  believe,  may  be  procured  for  3s.  per  cubic  foot  in  favorable 
localities  for  the  materials,  fuel,  (fee.,  but  the  principal  application  for  which  it  is  intended  is  for  orna- 
ments, as  mouldings,  rosettes,  coats  of  arms,  mullions,  (fee. ; for  elaborate  forms  may  be  given  to  it  at 
very  little  more  expense  than  is  required  for  the  simplest  form.  Terra  cotta  has  been  used  for  these 
purposes,  but  it  warps  in  baking,  and  produces  so  many  waste  pieces  that  it  becomes  more  costly  and 
B less  correct  than  stone  worked  by  hand  in  the  usual  manner. 


* Faraday,  however,  states  the  amount  of  water  to  be  75  per  cent, 
t See  Chem.  Gazette,  voi.  iii.  p.  360. 


424 


MORTISING  MACHINE. 


Mr.  Rockwell  has  also  proposed  a plan  for  making  large  masses,  slabs,  and  pipes  from  stone  and 
cement ; but  bis  invention  does  not  apply  to  the  manufacture  of  cubical  blocks. 

He  uses  fragments  of  stone  as  large  as  will  go  freely  into  the  mould,  mixed  with  other  smaller  frag- 
ments, of  various  sizes,  to  fill  up  the  interstices  as  much  as  possible,  the  remaining  space  being  occupied 
by  the  cement,  composed  of  chalk  and  Thames  mud  burnt  together. 

One  part  of  this  cement  is  mixed  with  eight  or  more  parts  of  fragments  of  stone,  and  wetted  with  the 
smallest  quantity  of  water  sufficient  to  moisten  the  whole ; a portion  of  the  mixture  is  then  put  into  the 
mould  to  a depth  of  1 4 inch,  and  rammed  down  by  hammers  or  monkeys  ; another  14  inch  is  then  added 
and  rammed  down,  and  so  on.  The  mould  is  perforated,  and,  although  so  little  water  has  been  used, 
it  oozes  out  at  all  parts,  showing  that  the  effect  of  the  ramming  is  to  bring  the  particles  of  stone  into 
much  closer  contact  than  could  be  done  by  any  simple  pressure.  When  taken  out  of  the  mould,  the 
stone  is  hard  enough  to  ring,  and  is  fit  for  use  in  two  days ; it  becomes  still  harder  by  exposure  to  air 
or  water  for  some  months. 

New  Portland  stone  fragments  cannot  be  used  for  this  conglomerate,  because  they  crush  into  powder 
under  the  hammer ; old  Portland  stone,  which  has  become  hardened  by  exposure,  answers  very  well, 
and  makes  an  artificial  stone  of  greater  specific  gravity  than  Portland  stone  itself.  The  cement  is 
harder  than  the  Portland  stone.  Flaws,  repaired  by  the  mixture  laid  in  with  a trowel,  are  much  softer 
than  the  cement  in  the  body  of  the  stone  which  has  been  consolidated  by  the  ramming.  The  moulds 
are  made  of  metal  and  are  very  expensive,  which  prevents  the  material  being  applied  to  ornamental 
purposes. 

Separate  pieces  of  stone  can  be  joined  by  well  ramming  or  caulking  in  the  composition  between 
them.  For  this  purpose,  of  course,  the  pieces  should  be  firmly  fixed  before  beginning  to  caulk  between 
them.  Mr.  Buckwell  states  that  he  could  execute  entirely  in  his  artificial  stone  the  ordinay  system  of 
sewage,  with  improvements,  at  the  same  cost  as  the  present  mode  of  executing  it  in  bricks.  It  may, 
therefore,  be  doubted  whether  it  would  be  advisable  to  employ  it.  A new  arrangement  of  sewage, 
which  he  proposes,  would  cost  §12  in  his  stone,  for  what  would  cost  §75  in  brick-work;  but  it  does  not 
as  yet  appear  why,  in  one  case  artificial  stone  should  cost  as  much,  and  in  the  other  only  one-sixth  the 
price  of  brick. 

An  illustration  of  the  effect  of  percussion  in  consolidating  materials  may  be  taken  from  the  fact  that 
concrete,  a mixture  of  gravel  and  lime,  sets  harder  and  better  the  greater  the  height  from  which  it  is 
allowed  to  drop  into  its  place : in  building  the  Royal  Exchange,  it  was  shot  in  from  a platform  30  feet 
above  the  foundation.  It  seems  probable  that  concrete  might  be  rendered  still  harder  by  mixing  it 
with  rather  less  water,  and  ramming  it  well  in  its  place.  In  Malta  the  roofs  of  the  houses  consist  of 
flag-stones  placed  in  a nearly  horizontal  position ; over  the  flag-stones  a bed  of  fragments  of  stone  and 
a little  clay  is  laid,  which  is  moistened  with  water,  and  beaten  and  rammed  until  nearly  dry  ; it  is  then 
covered  with  a layer  of  cement,  formed  of  4 parts  of  lime  to  3 of  Puzzolana,  moistened  with  water,  and 
well  beaten  down  until  it  begins  to  dry ; this  again  is  covered  with  a layer  of  dry  stone  fragments  to 
prevent  the  sun  from  cracking  it,  which  being  swept  off  after  a few  days,  a fine  smooth  impervious  roof 
is  obtained. 

Hydraulic  fresco-painting. — In  conclusion,  we  must  notice  a discovery  of  Fuchs  and  Schlotthauer, 
which  was  lately  communicated  to  the  Academy  at  Munich,  and  which  has  reference  to  a new  mode  oi 
fresco-painting.  While  the  fixing  of  the  colors  in  the  antique  as  well  as  in  the  modern  fresco-paintings 
is  due  to  the  hardening  property  of  caustic  lime,  when  exposed  to  the  atmosphere,  the  colored  surface 
upon  this  new  method  is  converted  into  a silicate  of  lime.  The  two  older  methods  stand,  therefore,  in 
the  same  relation  to  the  new  one,  as  ordinary  to 
hydraulic  mortar.  While  fresco-paintings  of  the 
former  kind  are  not  very  durable,  (except  in  cases, 
us  at  Pompeii,  where  their  preservation  is  due  to 
the  entire  exclusion  of  light  and  air,)  and  artists 
have  reason  to  mourn  over  the  destruction  of  the 
greatest  master-pieces ; those  obtained  upon  the 
now  principle  are  capable  not  only  of  withstand- 
ing the  action  of  water,  weak  acids,  and  alkalies, 
but  also  the  great  changes  of  climate  during  a se- 
vere German  winter  without  injury  to  the  freshness 
of  the  coloring ; and  the  colors  are  so  firmly  at- 
tached to  the  ground  that  they  exhibit  no  tendency 
to  separate  from  it  themselves,  nor  can  they  be 
removed  by  mechanical  agency.  The  particulars 
of  the  process  have  not  been  made  known,  but  it 
appears  probable  that  it  is  dependent  upon  the 
siiicification  of  the  lime  mortar,  by  means  of  a 
solution  of  an  alkaline  silicate,  of  which  we  have 
previously  spoken  under  soluble  glass. 

MORTISING  MACHINE.  Fig.  2846  repre- 
sents a mortising  machine  invented  and  patented 
by  A.  Swingle,  formerly  of  Texas,  now  of  Boston. 

A A are  the  legs,  B the  bench ; C is  a set-screw 
for  the  out-and-in  movement  of  the  bench,  and  D 
for  the  lateral,  in  any  kind  of  work.  E is  a hub  to 
be  mortised ; it  is  mounted  on  centres  turned  by 
the  handle  F,  and  there  is  a retaining  ratchet  and  wheel  H on  the  nigh  side.  There  is  a rest  below  the 
hub,  operated  by  a steadying  set-screw  I.  J,  inverted,  is  a hollow  augur,  or  rather  hollow  chisel  withic 


MOTION. 


425 


■which  is  the  augur ; and  the  movement  of  the  latter  is  followed  by  the  box-shaped  chisel,  so  that  the 
result  is  a square  hole  or  mortise.  The  augur  inside  receives  a very  rapid  motion  from  a bevel-wheel, 
geering  into  a pinion  which  drives  the  spindle  K of  the  augur,  a is  a pulley  to  drive  the  wheel  O.  M 
is  a lever,  and  by  flanges  the  spindle  is  made  steady  to  the  back  of  the  frame,  and  works  down  in  guide- 
collars.  When  the  hub,  or  whatever  it  may  be,  is  in  a correct  position,  the  spindle  K of  the  augur  is 
set  in  motion,  and  the  operator  gently  brings  down  the  weighted  lever  M,  cutting  out  the  rectangular 
mortise.  There  is  but  little  work  for  the  outside  chisel  of  the  augur  to  perform. 

The  lever  rests  on  the  top  of  the  spindle,  and  it  (the  spindle)  works  by  feather  and  groove  to  run 
down  through  its  geer-pinion,  to  follow  the  cut  to  the  bottom  of  the  mortise.  These  machines  are  highly 
recommended  by  those  who  have  used  them. 


2847.  2843. 


MORTISING  MACHINE.  Figs.  2841  and  2848  represent  a machine  manufactured  by  W.  R.  A 
A.  Inslee,  Newark,  N.  J.,  and  from  the  simplicity  of  its  plan  it  is  much  less  liable  to  get  out  of  order 
than  others  of  a more  complicate  character. 

The  action  of  the  machine  is  sufficiently  obvious. 

MOTION,  in  mechanics,  is  a change  of  place,  or  it  is  that  affection  of  matter  by  which  it  passes  from 
one  point  of  space  to  another.  Motion  is  of  various  kinds,  as  follows : Absolute  motion  is  the  absolute 
change  of  places  in  a moving  body,  independent  of  any  other  motion  whatever — in  which  general  sense, 
however,  it  never  falls  under  our  observation.  All  those  motions  which  we  consider  as  absolute  are,  in 
fret,  only  relative,  being  referred  to  the  earth,  which  is  itself  in  motion.  By  absolute  motion,  therefore, 
we  must  only  understand  that  which  is  so  with  regard  to  some  fixed  point  upon  the  earth,  this  being  the 
sense  in  which  it  is  delivered  by  writers  on  this  subject.  Accelerated  motion  is  that  which  is  continually 
receiving  constant  accessions  of  velocity.  Angular  motion  is  the  motion  of  a body  as  referred  to  a 
centre,  about  which  it  revolves.  Compound  motion  is  that  which  is  produced  by  two  or  more  powers 
acting  in  different  directions.  Uniform  motion  is  when  the  body  moves  continually  with  the  same  ve- 
locity, passing  over  equal  spaces  in  equal  times.  Natural  motion  is  that  which  is  natural  to  bodies,  or 
that  which  arises  from  the  action  of  gravity.  Relative  motion  is  the  change  of  relative  place  in  one  or 
more  moving  bodies : thus  two  vessels  at  sea  are  in  absolute  motion  (according  to  the  qualified  signifi- 
cation of  this  term)  to  a spectator  standing  on  the  shore,  but  they  are  only  in  relative  motion  with 
regard  to  each  other.  Retarded  motion  is  that  which  suffers  continual  diminution  of  velocity,  the  laws 
of  which  are  the  reverse  of  those  for  accelerated  motion. 


426 


MOTION. 


Table  of  the  Analysis  of  Motion. 


Rectilinear  motion  continued  in 


Circular  motion  continued  in 


Rectilinear 

Circular... 


Continued  ...  Figs.  1,  2,  3,  4,  5. 

Alternate 

( Figs.  6,  7,  8,  9,  10, 
Continued  4 11,  12,  13,  14, 

( 15,  16,  17,  18,  19. 


Alternate  . 


r 

Rectilinear  alternate 


..  Figs.  20,  21,  22,  23,  24. 


Figs.  25,  26,  27,  28,  29, 
30,  31,  32,  33,  34, 

- 35,  36,  37,  38.  39, 

40,  41,  42,  43, 

44,  45. 


Circular 


| Continued . 
Alternate.. 


( Figs.  46,  47,  48,  49,  50, 
4 51,  52,  53,  54,  55, 

( 56,  57,  58. 

f Figs.  59,  60,  61,  62,  63, 
I 64,  65,  66,  67,  68,  69, 
| 70,  71,  72,  73,  74, 

L 75,  76. 


Alternate  rectilinear  motion  con-  * 

1 Rectilinear  alternate 

1 circular  alternate 

j Figs.  77,  78,  79,  80,  81, 

•')  82,83,84,85,86. 

Alternate  circular  motion  con-  j 
tinued  in j 

- Circular  alternate 

Figs.  87,  88,  89,  90,  91. 

Supplement 

j Figs.  92,  93,  94,  95,  96, 
' l 97,  98. 

MOTION. 


427 


428 


MOULDING  MACHINE. 


MOULDING  MACHINE.  This  invention  consists  of  certain  mechanical  arrangements  for  producing 
architectural,  cabinet,  or  other  mouldings.  Our  engraving  represents  an  end  elevation  of  the  machine, 
which,  with  the  aid  of  the  letters  of  reference,  will  be  readily  understood.  A,  is  a cast-iron  bed-piece 
with  V grooves,  and  constructed  in  some  respects  similar  to  planing  machines  now  in  use  for  planing 
iron,  &c.,  having  a driving-screw  placed  in  the  centre  of  the  bed-piece,  so  as  to  give  a slow  alternating 
motion  to  the  travelling-table,  when  power  is  applied  thereto.  The  ordinary  reversing  geer  is  em- 
ployed, the  construction  of  which  is  well  known  ; B is  the  bed  or  traversing-table  which  is  shown  in 
section,  for  the  purpose  of  more  clearly  representing  the  various  arrangements  in  detail,  such  as  the 
mode  of  fastening  the  planks  of  wood  to  the  table  by  the  means  of  lateral  clamps  inserted  in  their 
sides;  JJ  the  position  of  the  driving -screws  together  with  the  inverted  Y rail,  and  standards  KK; 
C is  the  driving-screw,  also  shown  in  section,  and  which  passes  longitudinally  through  the  machine  from 
end  to  end,  in  geer  with  the  bed  or  table  by  a nut,  or  any  other  suitable  means  usually  applied  to  such 
purposes  when  reversing.  There  are  two  vertical  standards,  supporting  in  bearings  the  bridge  E,  with 
the  cutter-bars,  or  mandrils,  attached.  Each  of  these  standards  contains  a spring  of  the  same  pitch, 
geering  into,  and  attached  to  the  bridge,  so  that  by  turning  the  horizontal  bar  F,  both  screws  are  made 


SHEET-METAL  MOULDING  MACHINE. 


429 


2947. 


to  revolve  at  the  same  rate,  and  the  bridge  is  thereby  caused  to  ascend  and  descend  as  may  be  re- 
quired; G is  a horizontal  bar,  which  revolves  rapidly  in  its  bearings  HH,  and  carries  a number  01 
cutters  or  chisels,  each  having  its  cutting  edge  so  shaped  as  to  produce  the  required  mouldings,  or  any 
parts  thereof,  which  can  be  produced  by  revolving  cutters  on  a horizontal  shaft.  Motion  is  communi- 
cated to  this  axis  by  bands  from  an  overhead  power-wheel.  Its  course,  after  leaving  the  power-wheel, 

is  first  directed  down  to  a tightening  pulley,  which  is 
clamped  on  to  a part  of  the  standard  frame  on  one  side, 
having  a vertical  slot  therein  for  the  purpose  of  enabling 
the  operators  at  auy  time  to  obtain  the  requisite  tension ; 
it  then  passes  up  and  over  the  upper  half  of  one  groove 
of  the  cutter-pulley,  down  again  at  the  back,  and  over  the 
driving-pulley  : it  is  then  pressed  in  at  the  starting  point 
to  make  the  endless  band.  1 1 are  the  chisels  or  cutters, 
which  are  mounted  upon  the  horizontal  shaft  G,  which  ad- 
mit of  being  arranged  and  set  up  in  any  convenient  or 
necessary  form  and  number  suitable  to  the  production  of 
compound  mortises  ; each  chisel  being  of  the  most  simple 
form  and  construction,  having  its  cutting  edge  shapied  to 
form  the  numerous  mouldings,  either  simple  or  compound 
by  either  using  them  separately  or  in  conjunction  with  eact 
other,  as  the  case  may  require  ; L L are  bosses  cast  on  the 
standard  on  each  side  and  on  each  end,  on  a level  with 
the  surface  line  of  the  bed  or  table  B.  These  bosses 
are  bored  to  receive  a vertical  rod  through  each,  the 


lower  end  of  which  has  a thread  run  upon  it,  in  geer 
with  a nut  and  a hand-wheel  MM,  whilst  the  upper  end 
forms  a shackle  or  forked  head,  (but  which  is  not  shown  in  the  above  view.)  it  being  readily  understood 
to  constitute  merely  a single  bearing  to  carry  a horizontal  shaft  from  one  side  of  the  machine  to  the  other 
transversely,  on  which  elastic  friction  rollers  are  mounted:  the  object  of  such  bearings  being  that  when 
a different  moulding  is  to  be  substituted  for  the  one  in  the  course  of  formation,  the  shaft  containing  the 
corresponding  shaped  friction  rollers  by  the  mouldings  last  completed  may  easily  be  exchanged  for  that 
of  any  other,  by  removing  it  from  the  forked  head  in  which  it  revolves.  At  the  back  of  the  bridge  E 
a horizontal  and  vertical  slide  is  fixed,  having  a slot  parallel  to  the  bed  of  the  machine,  for  the  purpose 
of  carrying  two  traversing  cutter-heads,  affixed  to  which,  through  the  intervention  of  revolving  man- 
drils, are  the  cutters  which  work  at  any  angle  to  the  bed  or  table,  as  well  as  on  the  same  surface  level, 
as  the  cutters  1 1.  The  cutters  thus  referred  to  receive  their  direct  motion  from  the  power-wheel  over 
head,  independently  of  other  parts  of  the  machine,  by  an  endless  rope  or  chain  passing  round  the 
wheel  mounted  in  the  cutter-heads  in  such  a manner  that  when  this  part  of  the  apparatus  is  not  re- 
quired to  work  in  connection  with  the  other  it  can  be  thrown  out  of  geer  at  any  time,  even  while  tha 
running  mouldings  are  in  action. 


2949. 


2950. 


2948. 


In  connection  with  the  above  the  inventor  uses  the  bevelled  cone-wheels  to  produce  rotary  motion 
to  give  full  effect  to  the  cutting  tools  1 1,  by  the  motion  of  the  vertical  mandril  working  in  a broad  beam 
the  cutter-head,  while  the  work  to  be  cut  is  held  down  nicely  by  vulcanized  India-rubber  rollers.  The 
principal  feature  in  the  invention  is  the  revolving  horizontal  bar,  whereby,  like  borders  made  of  type, 
the  inventor  is  enabled  to  make  compound  and  various  patterns  by  simple  chisels,  by  their  transposition. 

SHEET-METAL  MOULDING  MACHINE, by  Mr.  It.  Roberts,  of  Manchester.  This  machine,  Figs. 
2951-2955,  has  two  shafts  B and  B',  which  project  beyond  one  of  the  side-frames  in  which  the  lower 
shaft  B turns ; the  upper  shaft  B is  mounted  in  a balance  swing-frame,  and  is  connected  by  spur  geer 
with  the  lower  shaft  in  such  a way  that  the  distance  between  the  shafts  may  be  adjusted  to  any  re 


430 


MULE. 


quired  extent,  without  altering  the  depths  of  the  wheels  in  geer.  On  the  projecting  ends  of  thes* 
shafts,  the  rollers  D E are  put,  with  which  the  mouldings  are  to  be  formed  ; the  lower  roller  is  in  one 
piece  only,  but  the  upper  roller  is  made  in  one  or  more  parts  transversely,  as  may  be  best  adapted  to 
form  the  required  mouldings,  as  shown  in 
the  enlarged  figure : the  which  parts, 
when  more  than  one,  are  made  to  ap- 
proach each  other  by  being  slid  along  the 
shaft  B',  which  is  hollow,  by  means  of  a 
screw  F that  acts  within  on  the  back  part 
of  the  top  roller  D by  means  of  a cotter, 
which  passes  through  the  shaft  and  the 
screw,  and  on  the  front  part  by  a nut  f 
which  is  screwed,  from  time  to  time,  by 
hand. 

The  advantage  of  making  the  rollers  in 
two  or  more  parts  is,  that  it  allows  the 
metal  to  be  gradually  compressed  side- 
ways as  well  as  vertically,  and  avoids 
puckering.  The  curved  mouldings  shown 
in  the  engraving  were  made  on  the  first 
machine  of  the  kind  that  was  constructed, 
and  the  straight  mouldings  on  a similar 
machine  subsequently  made.  Almost  any 
degree  of  curvature  can  be  given  to  the 
moulding,  by  means  of  the  third  roller  H, 
which,  with  its  shaft  and  sliding  bearings 
J,  is  lowered  by  the  geering  h,  Fig.  2951,  in  front  of  the  pair  of  rollers  to  produce  the  required  curvature, 

The  engravings  A,  Fig.  2951,  apd  A',  Fig.  2953,  are  representations  of  two  pair  of  rollers  for  form- 
ing simultaneously  the  cap  mould  of  each  of  the  two  brass  domes  for  locomotive  engines  ; the  rollers 
A,  Fig.  2951,  being  for  the  purpose  of  creasing  the  metal,  and  the  rollers  A'  for  finishing  the  two 
cap-moulds,  which  may  be  afterwards  divided  in  the  middle  by  a lathe  or  with  a saw.  Two  mouldings 
are  in  this  case  made  together,  owing  to  the  peculiar  form  of  the  moulding  rendering  it  more  facile  to 
do  so  than  to  make  one  separately. 


Fig.  2950  and  2954  show  two  pair  of  rollers  for  forming  the  “ astragal,”  to  which  the  upper  and  lower 
plates  of  the  chimney  of  a locomotive  are  riveted ; the  rollers  B*  B"  are  used  in  the  order  the  draw- 
ings are  lettered. 

Fig.  2953  shows  a pair  of  rollers  for  forming  the  “ base  mould,”  and  Fig.  2949  for  forming  the  body  of 
the  brass  dome  of  the  locomotive  engine,  one  pair  of  rollers  only  being  used  in  both  these  last  men- 
tioned cases. 

MULE.  A machine  employed  in  spinning  cotton  and  other  fibrous  materials.  For  producing  fine 
threads,  a process  analogous  to  that  performed  with  carded  cotton,  upon  a common  spinning-wheel, 
and  called  stretching , is  resorted  to.  In  tins  operation,  portions  of  yarn,  several  yards  long,  are  forcibly 
stretched  in  the  direction  of  their  length,  with  a view  to  elongate  and  reduce  those  parts  of  the  yarn 
which  have  a greater  diameter  and  are  less  twisted  than  the  other  parts,  so  that  the  size  and  twist  of 
the  thread  may  become  unifprm  throughout.  To  effect  the  process  of  stretching,  the  spindles  are 
mounted  upon  a carriage,  which  is  moved  backwards  or  forwards  across  the  floor,  receding  when  the 
threads  are  to  be  stretched,  and  returning  when  they  are  to  be  wound  up.  The  yarn  produced  by 
mill  spinning  is  more  perfect  than  any  other,  and  is  employed  in  the  fabrication  of  the  finest  articles. 
The  sowing-thread,  spun  by  mules,  is  a combination  of  two,  four,  or  sis  threads.  Threads  have  been 
nroduced  of  such  fineness  that  a pound  of  cotton  has  been  calculated  to  reach  167  miles. 


MULE,  SELF-ACTING. 


431 


MULE,  Mason's  self-acting.  This  machine,  invented  by  J.  W.  Mason,  of  Taunton,  Mass.,  for  spinning 
cotton  and  other  fibrous  substances,  stands  first  in  the  first  class  of  machines. 

Fig.  2956  is  an  elevation  of  the  mule  and  carriage.  Fig.  2957  an  elevation  of  the  other  side.  Fig. 
2959  a plan.  Fig.  2960  an  elevation.  Fig.  2961  a longitudinal  vertical  section,  taken  through  the  line 
X X of  Fig.  2959.  Fig.  2963  a front  elevation.  Fig.  2962  a section  through  the  friction-clutch.  . Fig. 
2958  a separate  view  of  the  scroll  or  volute  cam.  Fig.  2964  a cross  lection  of  the  head.  The  same 
letters  indicate  like  parts  in  all  the  figures. 

A3  represents  a frame  properly  adapted  to  the  operative  parts  of  the  head ; the  carriage  is  not 
represented,  as  it  is  similar  to  those  of  other  mules. 

A A'  A"  three  pulleys  of  equal  diameter,  placed  side  by  side  on  the  main  shaft  B'.  A is  the  first 
fast  pulley  attached  to  and  turning  with  the  shaft  B.  A'  is  the  second  fast  pulley,  carrying  a pinion 
D,  and  turning  freely  on  the  shaft  B.  A"  a loose  pulley  placed  between  the  other  two,  and  turning 
freely  on  the  shaft.  A driving-belt  passes  over  these  pulleys,  and  is  guided  to  either  of  them  by  a 
shipper-lever  C,  that  vibrates  on  a stud-pin  U,  and  connected  with  a weighted  balance-lever  C3  by 
which  the  belt  is  moved  from  one  of  the  pulleys  to  either  of  the  other  two.  At  the  commencement  ol 
the  first  series  of  operations,  the  belt  runs  on  the  first  fast  pulley  A',  to  give  the  first  series  of  motions. 
The  pinion  J,  on  the  shaft  B,  communicates  a positive  and  regular  motion  to  the  shaft  G (which  is  in 
connection  with  the  draw  collars  in  the  usual  manner)  by  means  of  the  first  train  of  wheels  Iv  L I,  and 
from  the  shaft  G by  the  second  train  of  wheels  NOPRSX,  to  the  line  shaft  Y that  drives  the  car- 
riage by  means  of  endless  chains  Z,  connected  with  the  carriage  by  one  of  the  links,  Z3.  There  is  but 
one  of  these  chains  represented  in  the  drawings,  and  the  shaft  is  shown  broken  off,  as  the  connections 
with  the  carriage  present  nothing  new,  and  therefore  need  not  be  represented.  The  spindles  at  the 
same  time  rotate  by  the  usual  band  T,  driven  by  the  pulley  O',  on  the  same  pulley  shaft  B.  This 
completes  the  first  series  of  motions,  namely,  drawing  out  the  carriage,  turning  the  draw  rollers  and 
spindles  to  draw  out,  spin,  and  twist  the  threads.  Near  the  end  of  the  running-out  motion  of  the 
carriage,  the  belt  is  shipped  from  the  first  fast  pulley  A to  the  loose  pulley  A",  which  removes  the 
driving  power  from  these  motions.  The  shifting  of  the  belt  is  thus  effected  : the  weighted  balance-lever 
C3  is  jointed  to  the  shipper-lever  at  2,  above  the  stud-pin  3,  on  which  it  vibrates.  The  lower  end  ot 
this  balance-lever  is  T-shaped,  and  one  of  its  short  arms  is  joined  by  a fink  4,  with  a short  lever  5, 
that  turns  on  the  stud-pin  6.  This  lever  is  also  connected  by  a link  d,  with  another  lever  p,  that 
turns  on  a stud-pin  e,  and  this  last  lever  is  depressed  when  the  belt  is  to  be  shipped  by  means  of  a 
pin  a , on  a vibrating  arm  L',  on  the  shaft  K'  of  the  wheel  that  carries  the  connecting-rod  by  which 
the  carriage  is  run  in.  The  balance-lever  is  by  this  means  carried  a little  beyond  the  vertical  line, 
and  then  carried  entirely  over  by  the  weight  of  the  lever  C3.  On  this  shaft,  K',  and  on  the  opposite 
side  of  the  frame,  there  is  another  arm  M',  provided  with  a pin  g,  which  at  the  same  time  depresses 
another  lever  X',  connected  by  means  of  a jointed  rod  li,  with  an  elbow-lever  7,  that  moves  a 
clutch  M on  the  shaft  G,  by  means  of  which  the  cog-wheel  I is  clutched,  which  liberates  the  draw 
rollers  and  the  second  train  of  wheels  that  communicate  motion  to  the  carriage  from  the  parts  that 
drive  the  spindles.  The  clutch  M is  held  open  until  the  belt  is  again  carried  to  the  first  fast  pulley 
at  the  end  of  the  third  series  of  motions  by  a pin  /,  on  one  arm  of  the  balance-lever  C3,  which  bears 
against  one  side  of  the  arm  of  the  clutch-lever  7,  for  the  lever  X',  that  moves  the  clutch-lever,  is 
provided  with  a helical  c'  attached  to  it  and  the  frame,  for  the  purpose  of  forming  the  clutch  the 
moment  that  the  pin^'  of  the  balance-lever  C3  liberates  the  clutch-lever  7.  The  band  T'  that  carries 
the  spindles,  and  which,  as  we  have  before  stated,  passes  round  and  is  carried  by  the  pulley  O'  on  the 
main  shaft  B,  passes  around  a guide-pulley  R'  at  one  end  of  the  frame,  and  another  S'  at  the  other 
end,  and  also  around  another  pulley  P'  that  runs  freely  on  a shaft  Q'  which  slides  endwise  on  its  bearings 
and  on  the  friction  pulley,  which  is  prevented  from  sliding  endwise  with  the  shaft  by  a collar  8,  so  that 
when  this  shaft  Q'  is  moved  in  one  direction,  the  puliey  P'  is  clutched  to  it  by  the  friction  of  the 
conical  surfaces,  and  when  moved  in  the  reverse  direction  it  is  unclutched  and  turns  freely  on  the 
shaft.  This  clutching  and  unclutching  is  effected  by  an  arm  Z3,  Fig.  2961,  on  the  spindle  U'  of  the 
shipper-lever  C,  which  embraces  a collar  on  the  shaft  Q',  so  that  when  the  shipper  C shifts  the  belt 
from  the  first  fast  pulley  A,  it  at  the  same  time  gives  the  requisite  movement  to  clutch  the  friction- 
clutch  that  connects  the  spindles  with  the  shaft  Q',  which  will  be  carried  by  their  momentum ; and  as 
this  shaft  is  connected  by  the  train  of  wheels  X',  Y',  Z',  and  C",  with  a horizontally  sliding-rack  W',  the 
rack  is  carried  for  a short  distance  in  the  direction  of  the  arrow,  Fig.  2961.  When  the  shipper  trans- 
fers the  belt  from  the  first  fast  to  the  loose  pulley,  a clutch  D2,  Fig.  2964,  on  the  shaft  D1,  is 
shifted  by  the  forked  lever  f which  turns  on  the  stud-pin  10,  and  is  worked  by  a spur  11  on  the 
balance-lever  C3,  which  bears  on  the  end  of  the  volute  spring  12  attached  to  the  lever  /,  the  tension  of 
which  forces  the  sliding  part  of  the  clutch  against  the  permanent  part.  The  sliding  part  of  the  clutch 
is  feathered  to  the  shaft  D',  v\  hich  is  carried  by  a train  of  wheels  C'  B'  and  pinion  D on  the  second 
fast  pulley  A',  driven  by  the  driving-belt  when  it  is  shifted  by  the  shipper  that  carries  it  from  the  first 
fast  pulley  A to  the  loose  pulley  A"  and  then  to  this  : the  time  required  for  this  transfer  of  the  belt 
by  the  motion  of  the  shipper  being  sufficient  for  the  preparative  movement. 

So  far  it  has  been  shown  that  the  second  fast  pulley  carries  the  shaft  D'  of  the  clutch  D”  a part  of  a 
revolution  before  clutching  the  pinion  E'  which  geers  into  the  wheel  F'  that  runs  the  carriage  in,  (as 
will  be  hereinafter  described,)  this  period  of  time  being  required  to  enable  the  momentum  of  the  spin- 
dles to  run  back  the  rack  w'  preparatory  to  the  backing-off  motion.  As  the  rack  w'  is  carried  by  the 
momentum  of  the  spindles  in  the  direction  of  the  arrow  preparatory  to  the  backing-off  motion  it  is 
necessary  gradually  to  arrest  this  motion,  which  is  effected  by  a friction-spring  brake  constructed  and 
connected  with  the  rack  in  the  following  manner.  To  the  end  of  the  rack  is  attached  a chain  m,  which 
passes  over  a pulley  o,  and  then  around  a spin-wheel  p,  attached  to  a ratchet-wheel  H2,  and  with  it 
turning  freely  on  a rock-shaft  n ; and  then  it  passes  over  another  loose  pulley  D3,  and  to  the  end  of  it 
is  susnended  a tension  weight  E2,  which  takes  up  the  slack  of  the  chain.  On  the  said  rock-shaft  n,  and 


432 


MULE.  SELF-ACTING. 


MULE,  SELF-ACTING. 


433 


// 


Vol.  IL—  28 


431 


MULE,  SELF-ACTING, 


MULE,  SELF-ACTING. 


435 


by  the  side  of  the  ratchet-wheel,  there  is  a cam-plate  t,  that  also  turns  freely  on  the  shaft,  and  which  is 
carried  in  one  direction  by  the  ratchet-wheel,  when  the  catch  or  hand  v,  which  is  jointed  to  the  cam- 
plate,  takes  into  the  teeth  of  the  ratchet,  the  two  turning  independently  of  each  other  in  the  reverse 
direction,  or  in  the  same  direction  when  the  catch  or  hand  is  lifted  out  of  the  teeth.  When  the  rack  is 
drawn  by  the  momentum  of  the  spindle  in  the  direction  of  the  arrow,  the  chain  in  attached  thereto 


turns  the  spur  and  ratchet  wheel  in  the  direction  of  the  arrow ; and  the  cam-plate  is  also  turned  in  tne 
same  direction  by  the  catch  or  hand  v.  This  motion  is  gradually  arrested  by  the  enlarged  or  scroll  form 
of  the  cam-plate,  which  forces  out  a friction-arm  b',  one  end  of  which  is  jointed  at  a'  to  an  arm  of  a 
lever  F3,  attached  to  the  rock-shaft  n,  the  other  arm  of  this  lever  being  connected  with  the  friction  b' 
by  a helical  spring  s.  It  will  therefore  be  perceived  that  as  the  friction- arm  is  forced  out  by  the  cam 


29C1. 


436 


MULE,  SELF-ACTING. 


MULE,  SELF-ACTING. 


437 


plate,  the  tension  of  the  spring  increases  the  friction  of  the  brake  on  the  periphery  of  the  cam-plate, 
which  gradually  arrests  the  motion  of  the  parts  in  connection  with  the  rack  W,  and  of  necessity  the 
spindles.  When  these  parts  are  arrested  the  rock-shaft  n is  turned  in  the  opposite  direction,  and  carries 
with  it  the  cam-plates,  ratchet-wheels,  and  spur-wheel  by  the  pressure  of  the  brake,  and  of  necessity 
reverses  the  motion  of  the  rack  and  spindles  to  uncoil  the  threads  from  the  spindles.  At  the  end  ol 
this  motion  the  catch  v of  the  cam-plate  is  liberated  from  the  ratchet-wheel  H2,  by  a spur  x,  of  a lever 
y,  jointed  at  14,  by  the  arm  F3,  of  the  rock-shaft  n,  the  spur  being  forced  on  to  the  back  end  of  the 
catch  by  the  rotation  of  the  rock-shaft ; the  lever  y having  a slot  in  it  which  turns  and  slides  on  a per- 
manent rod  z.  This  reversed  motion  of  the  rock-shaft  n is  effected  by  a crank  motion  in  the  following 
manner,  viz. : The  pinion  D,  on  the  second  fast  pulley  A,  commences  motion  by  the  train  of  wheels  B, 
C,  and  R2,  to  the  wheel  Q2,  in  the  direction  of  the  arrow,  and  this  wheel  carries  a crank-pin  h',  that 
works  in  a slot  /t2,  of  a connecting-rod  O2,  jointed  to  a curved  arm  K2,  that  vibrates  on  a fixed  stud-pin 
15,  and  this  arm  has  a slot  in  it  which  works  a slide  e',  for  the  purpose  of  graduating  the  backing-off 
motion  and  to  this  slide  is  jointed  another  connecting-rod  J2,  the  other  end  of  which  is  jointed  to  the 


arm  I2,  of  the  rock-shaft  n.  At  the  time  that  the  driving-belt  is  shifted  to  the  second  fast  pulley  A', 
which  takes  place  whilst  the  momentum  of  the  spindle  prepares  the  parts  for  the  backing-off  motion, 
the  crank-pin  h'  is  at  h3,  a little  above  a line  passing  from  the  centre  of  the  wheel  to  the  junction  oi 
the  connecting-rod  O2,  and  the  arm  K2,  so  that  the  crank-pin  in  this  wheel  can  move  around  to  the  posi- 
tion represented  in  Fig.  2957  before  it  begins  to  draw  the  connecting-rod  to  give  time  for  completing 
the  preparation  of  the  parts  for  backing-off.  In  rotating  from  h to  7t4,  the  crank-pin  carries  the  connect- 
ing-rod the  required  distance  to  give  the  required  backing-off  motion  to  the  spindles  to  uncoil  the  thread, 
and  at  the  same  time  depresses  the  faller  to  guide  the  threads  to  the  cops  preparatory  to  winding  on 
by  means  of  the  coping-rail  or  former  G2,  one  end  of  which  is  connected  by  a slot  with  a wrist  q , on  an 
arm  F2,  of  the  rock-shaft  n,  the  elevation  of  which,  by  the  backing-off  motion  of  the  rock-shaft  n , depresses 
the  faller.  So  soon  as  the  connecting-rod  O2  has  been  carried  to  the  point  h 4 by  the  crank-pin,  which 
is  the  extent  of  the  backing-off  motion,  the  catch-lever  U2  takes  hold  of  the  pin  13,  on  the  arm  Ks,  and 
there  holds  all  the  parts  of  the  backing-off  operation  until  released  towards  the  end  of  the  running  mo- 
tion of  the  carriage,  the  liberation  of  the  parts'  neing  then  effected  by  means  of  a pin  V on  the  arm  L, 
on  the  shaft  K,  of  the  wheel  F,  which  runs  in  a carriage.  So  long  as  the  backing-off  apparatus  is  held 


438 


MULE,  SELF-ACTING. 


by  the  catch-lever  U2,  the  crank-pin  h'  can  revolve  freely,  the  slot  in  the  connecting-rod  O2  admitting 
of  this.  When  the  backing-off  apparatus  is  liberated  it  falls  back  to  the  position  indicated  in  the  draw- 
ings by  the  weight  of  the  coping-rail  and  the  other  parts  attached  to  the  rock-shaft ; and  to  prevent  ja! 
this  return  motion  of  the  parts  is  eased  off  by  the  connecting-rod  O2  coming  against  the  crank-pin  h,  at 
the  point  /t3,  the  power  required  to  turn  this  train  of  wheels  in  the  reverse  direction  being  sufficient  tc 
ease  off  and  gradually  arrest  the  moving  parts  without  jar.  This  return  motion  of  the  backing-off  ap- 
paratus at  the  same  time  arrests  the  second  fast  pulley  A,  and  the  train  of  wheels  in  connection  with  it 
by  means  of  a brake,/',  connected  by  the  arm  T2,  and  link  S2,  with  the  arm  K2,  of  the  backiDg-off  ap- 
paratus, and  the  train  of  wheels  and  the  connection  of  the  brake  are  so  regulated  as  to  stop  the  crank 
pin  h'  at  the  point  /t3,  where  it  is  required  to  be  when  the  second  series  of  motions  is  commenced.  The 
link  S2,  and  the  connecting-rod  J2,  are  provided  with  adjusting-screws  for  the  proper  adjustment  of  all 
these  parts.  As  the  backing-off  motion  must  be  gradually  decreased  as  the  cop  is  formed  and  increased 
in  length,  the  vibrating  motion  of  the  rock-shaft  is  gradually  shortened  by  means  of  the  slide  e,  in  the 
arm  K2,  to  which  the  connecting-rod  J2  is  jointed.  For  this  purpose  the  slide  is  attached  to  a chain  d, 
which  passes  over  the  upper  end  of  the  arm,  and  is  gradually  wound  up  on  the  arbor  e ",  of  a cog-wheel 
L2,  that  geers  into  a pinion  L',  of  a ratchet-wheel  N2,  which  receives  motion  from  the  arm  K2,  of  the 
backing-off  apparatus  by  a hand  or  catch  M2,  jointed  thereto  at  z.  It  will  be  evident  that  as  the  slide 
is  drawn  up  by  the  chain  towards  the  axis  of  motion  of  the  arm  K2,  the  motion  of  the  connecting-rod  J2 
will  be  diminished,  and  with  it  the  motion  of  the  backing-off  apparatus.  This  completes  the  second 
series  of  motions,  and  the  mule  is  then  in  a condition  to  commence  the  third  series. 

When  the  clutch  D2,  at  the  end  of  the 
backing-off  motion,  clutches  the  pinion  E', 
it  begins  to  turn,  which  communicates  mo- 
tion to  the  cog-wheel  F on  the  shaft  K,  or 
to  the  periphery  of  this  wheel  at  G is  jointed 
a connecting-rod  at  H ; the  other  end  of 
which  at  I is  jointed  to  a horizontal  sliding- 
rack  Y,  that  runs  on  ways  W that  carries 
by  means  of  the  pinion  U the  train  of  wheels 
that  communicate  motion  to  the  carriage. 

The  wheel  F is  carried  but  part  of  a revo- 
lution (nearly  one-half)  in  one  direction  by 
its  connection  with  the  second  driving-pul- 
ley A when  the  clutch  D2  is  closed,  which 
gives  by  the  crank  motion,  in  consequence 
of  the  connection  above  pointed  out,  the 
peculiar  running-in  motion  to  the  carriage, 
as  pointed  out  in  the  description  of  the  gen- 
eral characteristics  of  this  invention ; and  as 
the  carriage  approaches  the  end  of  its  run- 
ning-in motion,  the  pinion  E is  unclutched 
by  the  reversed  action  of  the  shipper-lever 
C3 ; this  reversed  motion  of  the  shipper  and 
its  appendages  being  effected  by  the  pin  e 
on  the  arm  L of  the  shaft  K of  the  wheel  F', 
this  pin  e being  on  the  side  of  the  shaft  K 
opposite  to  the  pin  a which  first  ships  it. 

The  unclutching  the  pinion  E leaves  the 
wheel  F free  to  be  turned  back  by  the  re- 
versed motion  of  the  rack  Y by  the  train 
of  wheels  which  runs  out  the  carriage  in  the 
first  series  of  motions. 

As  the  carriage  is  run  in  by  the  means 
just  described,  the  spindles  must  be  turned 
to  wind  up  the  threads  which  have  been 
spun  during  the  first  series  of  motions,  and  this  is  effected  by  means  of  the  top  sliding-rack  W, 
by  which  the  backing-off  motion  is  given,  and  which  is  placed  on  top  of  the  main  rack  V ; the 
connection  of  this  rack  W with  the  spindles  by  means  of  the  friction-clutch  having  been  described, 
it  is  only  necessary  to  the  manner  in  w'hich  the  winding-on  motion  is  communicated  to  it  by  the  main 
rack  V,  and  the  manner  in  which  this  motion  is  varied  and  regulated  to  correspond  with  the  varying 
size  of  the  cops  as  they  are  formed.  To  the  upper  rack  W,  and  near  one  end  of  it,  is  jointed  a lever 
m,  to  the  short  arm  of  which  is  attached  a chain  l',  which  thence  passes  around  a pulley  k that  turns  on 
a stud-pin  projecting  from  the  side  of  the  main  rack  V,  the  other  end  of  the  said  chain  being  attached 
to  the  smallest  diameter  of  a scroll-cam  n'  connected  with  the  end  of  the  main  rack  V.  From  this 
arrangement  it  will  be  obvious  that  if  the  cam  n be  prevented  from  turning  on  its  axis,  the  motion  of 
the  main  rack  V ■will  carry  the  top  rack  in  the  same  direction,  and  with  the  same  varying  velocity, 
which  would  give  to  the  spindles  a winding-on  motion,  corresponding  to  the  running-in  motion  of  the 
carriage,  such  as  would  be  required  if  the  cops  were  to  be  formed  cylindrical  and  did  not  vary  in  diam- 
eter ; but  such  is  not  the  case,  as  clearly  pointed  out  in  the  general  description.  To  give  the  varying 
motions  required,  and  fully  pointed  out  above,  the  scroll-cam  n'  is  attached  to  and  turns  with  a wheel  v 
on  the  stud-pin  I on  the  main  rack  Y,  and  to  this  wheel  at  vi  is  attached  a chain  x' , which,  after  passing 
around  a portion  of  the  circumference  thereof  is  attached  by  a link  y'  to  a slide  z"  that  travels  on  a 
■crew  a"  that  turns  in  the  arm  V2  of  a rock-frame  Vs,  the  lower  end  of  the  said  arm  being  jointed  tc 


MULE,  SELF-ACTING. 


439 


another  arm  of  equal  length  W2  that  vibrates  on  the  stud-pin  I',  on  which  turn  the  wheel  v'  and  the 
oam  re,  so  that  when  the  slide  z"  is  at  the  lower  end  of  the  arm  V2,  the  end  of  the  chain  x\  which  is 
attached  to  the  slide  during  the  movements  of  the  main  rack,  will  not  communicate  motion  to  the 
wheel  v and  cam  re,  hence  the  motions  of  the  two  racks  Y and  W will  correspond  and  give  to  the 
spindles  the  motion  required  for  winding  the  threads  on  the  naked  spindles,  and  as  the  base  of  the  cope 
is  increased  in  diameter,  the  slide  z"  is  drawn  up  towards  the  axis  of  motion  of  the  arm  V2  to  decrease 
the  motion  of  that  end  of  the  chain  x attached  to  it,  which  will  cause  the  wheel  and  cam  to  turn  on 
then-  axis,  and  thus  give  out  the  chain  l',  thereby  giving  to  the  top  rack  W',  and  consequently  to  the 
spindles,  a gradually  reduced  motion  relatively  to  the  main  rack  to  correspond  with  the  increased  diam- 
eter of  the  base  of  the  cops.  The  motion  required  is  given  to  the  slide  2"  by  the  vibrations  of  the  rock- 
frame  V3,  the  screw  a"  that  operates  the  slide  being  connected  by  a train  of  cog-wheels  b"  e"  z"  h"  i"j" 
with  a horizontal  ratchet-wheel  l"  which  turns  freely  by  the  rocking  motion  of  the  frame  Vs  in  one 
direction,  and  which  therefore  does  not  turn  the  screw,  but  which  is  prevented  from  turning  in  the 
opposite  direction,  during  the  running  motion  of  the  carriage,  by  a catch  or  pawl  r"  to  turn  the  said 
screw.  Whenever  the  tension  of  the  threads  in  winding  on  is  too  great  it  bears  down  the  counter-faller, 
(not  represented  in  the  drawings,)  the  arm  of  which  in  motion  of  the  carriage  strikes  an  arm  S"  of  what 
is  termed  a butterfly,  that  turns  on  a stud-pin  q",  on  which  the  catch  or  hand  r"  of  the  ratchet-wheel  /2 
also  turns,  and  with  which  it  is  connected  by  a spring  «>2,  Fig.  2956,  and  throws  it  into  the  teeth  of  the 
ratchet-wheel ; the  ■wheel  being  thus  held,  the  further  vibration  of  the  rock-frame  turns  the  screw  and 
carries  up  the  slide  to  reduce  the  motion  of  the  spindle,  and  on  the  return  motion  of  the  carriage  the 
hand  or  catch  r"  is  thrown  out  of  the  teeth  of  the  ratchet-wheel  by  the  arm  of  the  counter-faller,  which 
then  comes  in  contact  with  another  arm  f of  the  butterfly,  the  end  of  which  extends  lower  down  than 
the  arm  S2,  and  low  enough  to  be  struck  by  the  arm  of  the  counter-faller  when  it  is  not  under  the  action 
of  the  tension  of  the  threads.  The  catch  or  hand  then  remains  out  until  the  tension  of  the  threads 
again  requires  the  motion  of  the  spindles  to  be  reduced.  The  butterfly  is  connected  with  a hand-latch 
lever  ?re2  that  turns  on  a stud-pin  re2,  by  which  the  attendant  can  throw  the  butterfly  in  and  out  of  play. 
So  soon  as  the  base  of  the  cops  have  been  formed  the  scroll  form  of  the  cam  re'  gives  the  regular  vary- 
ing motions  to  the  spindles  to  wind  the  cone  of  the  cops,  as  fully  pointed  out  in  the  general  description. 

It  has  been  stated  that  in  finishing  the  cops  the  threads  are  wound  on  harder  at  the  point  of  the  cops ; 
this  is  effected  in  the  following  manner : On  the  shaft  e”  which  regulates  the  backing-off  motion,  as  de- 
scribed above,  there  is  a hub  q'  from  which  projects  a crank-arm  t’,  to  the  pin  S'  of  which  is  jointed,  by 
a link  r',  a chain  p',  the  other  end  of  which  is  jointed  by  a link  O'  to  a long  arm  of  the  lever  m,  which 
forms  the  connection  between  the  top  rack  W and  the  chain  l',  which  forms  the  connection  between  the 
top  and  the  main  racks.  This  shaft,  as  heretofore  described,  is  connected  with  the  ratchet-w'heel  N!, 
which  is  operated  by  the  catch  or  hands  M2  of  the  lever  K2  of  the  backing-off  apparatus,  and  the  chain 
p ' is  of  such  length  that  it  is  wound  up  by  the  rotation  of  the  shaft  until  towards  the  completion  of  the 
cops,  at  which  time  it  is  drawn  sufficiently  tight  to  strike  against  a permanent  arm  u'  towards  the  end 
of  the  winding-on  motion,  which  causes  the  lever  m'  to  turn  on  its  axis,  and  by  its  connection  to  draw 
up  the  chain  l,  and  hence  to  increase  the  velocity  of  the  rack  W,  and  therefore  the  rotation  of  the 
spindles,  which  winds  the  threads  on  tighter.  This  operation  gradually  increases  to  the  completion 
of  the  cops. 

On  this  same  shaft  e"  is  placed  the  coping-cam  Y2,  the  periphery  of  which  acts  on  the  lever  X2,  to 
which  the  coping-rail  or  former  G2  is  jointed  at  r',  in  a manner  well  known  to  those  who  are  acquainted 
with  the  construction  of  self-acting  mules,  and  which  therefore  needs  not  to  be  described.  This  com- 
pletes the  whole  series  of  motions ; but  it  will  be  obvious  that  when  one  set  of  cops  have  been  completed 
the  parts  employed  in  giving  the  progressive  movements,  such  as  the  shaft  e'j  that  rotates  the  coping  or 
forming-cam  Y2,  winds  the  chain  which  carries  the  slide  c'  of  the  backing-off  apparatus,  and  the  arm  t' 
that  winds  the  chain  p'  to  increase  the  tension  of  the  threads  in  finishing  the  points  of  the  cop,  and  also 
the  ratchet-wheel  P which  governs  the  motion  of  the  slide  z"  on  the  arm  V2,  by  which  the  winding-on 
motion  of  the  spindles  is  regulated  to  form  the  base  of  the  cops,  are  to  be  turned  back  by  hand  to  their 
original  position  by  the  attendant,  preparatory  to  commencing  a new  set  of  cops. 

I have  thus  described  the  general  plan  of  my  invention,  and  the  manner  of  constructing  and  using  the 
same;  but  before  pointing  out  what  I claim  as  my  invention,  I wish  it  to  be  distinctly  understood  that 
I do  not  limit  myself  to  the  precise  form  and  construction  of  the  various  parts  employed,  or  to  the 
precise  arrangement  described,  as  I consider  all  mechanical  equivalents  as  within  the  limits  of  my 
invention.  What  I claim,  therefore,  as  my  invention,  and  desire  to  secure  by  Letters  Patent,  is, 
1st.  The  disconnecting  of  the  mechanism  employed  in  running  out  the  carriage  and  turning  the  draw- 
rollers  from  the  mechanism  which  gives  the  whirling  or  spinning  motion  to  the  spindles  when  the 
driving-power  is  shifted  from  these  the  first  series  of  motions  to  enable  the  spindles  to  continue  their 
motion  by  inertia,  independent  of  the  other  motions,  by  means  of  the  clutch-box  or  its  equivalent,  which 
forms  the  connection  between  the  three  movements,  constituting  the  first  series  of  motions  whereby  (he 
momentum  of  the  spindles  can  be  employed  for  preparing  the  parts  for  the  backing-off  motion,  substan 
tially  as  described.  2d.  The  method  of  preparing  the  parts  for  the  backing-off  motion  by  means  of  the 
momentum  of  the  spindles,  by  connecting  them  with  the  backing-off  apparatus  by  means  of  the  friction 
clutch  or  any  equivalent  therefor,  substantially  as  described.  8d.  The  backing-off  apparatus,  consisting 
of  the  combination  of  the  top  sliding-rack,  which  communicates  motion  to  the  spindles  ; the  rocking  is 
with  a cam  and  spring-brake,  and  other  appendages,  and  the  connecting-rod  operated  by  the  crank,  al‘ 
substantially  as  described.  4th.  The  method  of  decreasing  the  backing-off  motion  to  correspond  with 
the  increased  length  of  the  cops,  by  means  of  the  slide  in  the  intermediate  arm  of  the  connecting-rod, 
(between  the  two  sections  of  the  connecting-rod,)  by  means  of  which  the  rocking  motion  of  the  rock- 
shaft  is  gradually  decreased,  substantially  as  described,  to  avoid  any  sudden  strain  or  jar  upon  the 
threads.  5th.  The  method  of  communicating  the  winding-on  motion  to  the  spindles  from  the  main  rack, 
which  runs  in  the  carriage  by  combining  the  said  main  rack  with  the  top  sliding-rack,  by  means  of  a 


440 


NAIL-MACHINE. 


chain  and  scroll-cam,  or  their  equivalents ; by  means  of  which  combination,  in  connection  with  the  fora: 
of  the  cam,  the  motions  of  the  spindles  so  correspond  with  that  of  the  carriage  as  to  wind  the  threads 
on  the  conical  form  of  the  cops,  as  described.  6th.  The  method  of  varying  the  winding-on  motion  of 
the  spindles  to  form  the  base  of  the  cops,  by  means  of  the  slide  and  chain  which  vary  the  motions  of 
the  wheel  that  is  attached  to  and  which  rotates  the  scroll-cam,  substantially  as  described,  whether  the 
slide  be  operated  by  the  vibration  of  the  arm  on  which  it  slides,  or  by  any  other  means  substantially 
as  herein  described.  7th.  The  method  of  regulating  the  motion  of  the  slide  that  varies  the  motion  of 
the  scroll -cam  of  the  winding-on  motion,  by  means  of  what  is  termed  the  butterfly  and  its  appendages, 
when  this  is  acted  upon  by  the  counter-faller,  operated  by  the  tension  of  the  threads,  substantially  as 
described.  And  8th.  The  method  of  winding  on  the  threads  tighter  at  the  points  of  tire  cops  when 
finishing  them,  by  means  of  tire  apparatus  which  gives  to  the  top  sliding-rack  an  increased  motion 
towards  the  end  of  the  operation ; the  said  apparatus  consisting  of  a chain,  which  is  connected  with  a 
chain  that  forms  the  connection  betwen  the  main  and  top  racks,  and  which  is  gradually  wound  up  and 
strikes  against  an  arm  towards  the  end  of  the  operations  of  the  mule  to  shorten  the  connection  between 
the  two  racks,  and  thus  increase  the  winding-on  motion  of  the  spindles,  as  described. 


NAIL-MACHINE.  The  manufacture  of  cut  nails  is  entirely  an  American  invention,  and  was  born 


<L 


A 


in  our  country,  and  has  advanced, 
within  its  bosom,  through  all  the 
various  stages  of  infancy  to  man- 
hood ; and  no  doubtwe  shall  soon 
be  able,  by  receiving  proper  en- 
couragement, to  render  them  su- 
perior to  wrought  nails  in  every 
particular. 

The  nail-machine  now  exten- 
sively in  use  in  this  country  for 
all  sizes  of  cut-nails  is  exhibited 
in  the  following  figures,  and  is 
the  machine  in  operation  at  Z.  B. 

Crooker's  Nail  Works,  in  Brook- 
lyn, L.  I. 

Fig.  2965  represents  the  front 
elevation  of  the  machine. 

Figs.  2966  and  2967  side  ele- 
vations. 

Fig.  2968  side  and  end  eleva- 
tions, showing  the  method  of 
turning  the  nail-plate. 

Fig.  2969  a general  plan  of 
the  machine. 

a a,  frame  of  the  machine ; b, 
main-shaft  for  carrying  the  cams, 
driven  by  a belt  over  the  pul- 
ley e,  and  provided  with  a fly- 
wheel d ; c,  guide  which  consists 
of  a metal  tube  through  which  passes  the  nail-rod,  holding  by  means  of  pincers  the  nail-plate  A,  Fig 
i967.  and  enlarged  view  A,  Fig.  2968. 


1 

. / 

1 

Stt81III8 

NAIL-MACHINE. 


441 


In  order  to  give  the  wedge-shape  required  in  the  brad  or  cut-nail,  the  cutter  is  set  oblique  to  the 
direction  of  the  nail-plate,  which  is  reversed  after  each  cut,  by  which  means  each  and  every  nail  has  a 
uniform  taper.  The  reversing  of  the  nail-plate  is  effected  by  means  of  a rocking-shaft  r which  receives 
its  motion  from  the  shaft  through  a geering/,  and  crank  producing  an  alternating  motion  to  the  seg- 
ments v Fi°-s  °967  and  2968,  which  is  communicated  to  the  guide-tube  c,  by  a belt  and  pulley,  the  nail- 
plate  being  fed  to  the  cutter  by  means  of  a weight  m,  as  shown  in  Figs.  2967  and  2968,  the  nail-rod 
with  its  attached  plate  vibrating  freely  within  the  guide-tube  c. 

The  cutter,  having  the  width  of  a 
nail-plate,  is  adjusted  by  screws  to 
the  cutting-block  p ; the  nail-plate  A, 
lying  between  guides,  rests  on  the  iron 
block  k,  and  bearing  by  the  action  of 
the  weight  m against  the  face  of  the 
cutter.  The  vibratory  movement  of 
the  latter  is  effected  by  means  of  the 
crooked  lever  /,  worked  by  an  eccen- 
tric on  the  main-shaft — the  cutter- 
block p,  forming  the  short  arm  of  this 
lever,  has  a short  circular  movement 
about  their  common  centre.  The  le- 
ver b,  cutter-block  p,  and  the  axle 
arms  or  trunnions  upon  which  they 
work  being  all  cast  in  one  piece,  are 
shown  in  Figs.  2965,  2966,  2967,  2969. 

y,  Fig.  2965,  shows  the  lever  of  the 
heading-die,  which  is  worked  by  a 
crank-pin  and  rod  i,  attached  to  a 
wheel  q , on  the  main-shaft. 

To  prevent  the  nail  falling  from  its 
place  before  the  completion  of  the 


stroke,  a small  pair  of  nippers,  operated  by  means  of  a cam  t on  the  main-shaft,  are  placed  below  and 
in  front  of  the  cutter-block  ; these  are  worked  by  the  rods  z. 

The  working  of  the  machine  is  as  follows : 

The  nail-plate  rests  against  the  frame  of  the  cutter,  the  lever  l resting  on  the  point  of  the  cam  or  ec- 
centric ; as  the  latter  revolves,  the  lever  l falls,  lifting  the  edge  of  the  cutter  above  the  cutting-block, 
and  also  above  the  nail-plate ; the  latter,  by  the  action  of  the  weight  m,  is  thrown  forward  under  the 
cutter  to  a stop  the  width  of  the  required  nail ; at  this  point,  by  the  revolution  of  the  eccentric,  the  lever 
l is  raised,  which  lowers  the  edge  of  the  cutter,  shearing  off  a wedge-shaped  strip  of  metal,  having  the 
length  of  the  width  of  the  nail-plate ; this  is  seized  at  the  same  instant  by  the  nippers  below  the  cutter, 
and  immediately  after  the  rod  i,  by  the  action  of  its  crank,  raises  the  lever  y,  of  the  heading-die,  and 
the  nail  is  completed  at  a stroke.  As  the  complete  nail  drops  from  the  opening  nippers  the  nail-plate 
is  advanced  under  the  cutting-shears  for  another  naiL 

The  action  of  this  machine  is  very  perfect,  and  is  suited  for  all  dimensions  of  cut-nails  ; the  machine 
of  course  being  heavier  and  larger  to  suit  the  different  sizes.  See  Spikes. 

NEEDLES.  The  making  of  needles,  although  largely  carried  on  at  Birmingham  and  a few  other 
towns,  is  mainly  conducted  at  Redditch  in  Worcestershire.  We  should  surprise  many  a reader  were 
we  to  enumerate  all  the  processes  incident  to  the  manufacture  of  a needle,  giving  to  each  the  teclmi- 
cal  name  applied  to  it  in  the  factory.  The  number  would  amount  to  somewhere  about  thirty ; but  it 
will  be  more  in  accordance  with  our  object  to  dispense  with  such  an  enumeration,  and  to  present  the 
details  of  manufacture  in  certain  groups,  without  adhering  to  a strictly  technical  arrangement. 

First,  then,  for  the  material.  It  is  scarcely  necessary  to  say  that  needles  are  made  of  steel,  and  that 


442 


NEEDLES. 


tlie  steel  is  brought  into  the  state  of  fine  wire  before  it  can  assume  the  form  of  needles.  The  needle- 
makers  are  not  wire-drawers : they  do  not  prepare  their  own  wire,  but  purchase  it,  in  sizes  varying  with 
the  kind  of  needles  which  they  are  about  to  make,  from  Sheffield  or  Birmingham,  or  some  similar  town. 
We  will  suppose,  therefore,  that  the  wire  is  brought  to  the  needle  factory,  and  is  deposited  in  a store- 
room. This  room  is  kept  warmed  by  hot  air  to  an  equable  temperature,  in  order  that  the  steel  may 
be  preserved  free  from  damp  or  other  sources  of  injury.  Around  the  walls  are  wooden  bars  or  racks, 
on  which  are  hung  the  hoops  of  wire.  Each  hoop  contains,  on  an  average,  about  twelve  or  fourteen 
pounds  of  wire,  the  length  varying  according  to  the  diameter.  Perhaps  it  may  be  convenient  to  take 
some  particular  size  of  needle,  and  make  it  our  standard  of  comparison  during  the  details  of  the  pro- 
cess. The  usual  sizes  of  sewing  needles  are  from  No.  1,  of  which  twenty -two  thicknesses  make  an 
inch,  to  No.  12,  of  which  there  are  a hundred  to  an  inch.  Supposing  that  the  manufacturer  is  about 
to  make  sewing  needles  of  that  size  which  is  known  to  sempstresses  as  No.  0 — then  the  coil  of  wire  is 
about  two  feet  in  diameter  ; it  weighs  about  thirteen  pounds ; the  length  of  wire  is  about  a mile  and 
a quarter ; and  it  will  produce  forty  or  fifty  thousand  needles.  The  manufacturer  has  a gage,  con- 
sisting of  a small  piece  of  steel,  perforated  at  the  edge  with  eighteen  or  twenty  small  slits,  all  of 

different  sizes,  and  each  having  a particular  number  attached  to  it.  By  this  gage  the  diameter  of 

every  coil  of  wire  is  tested,  and  by  the  number  every  diameter  of  wire  is  known. 

A coil  of  wire,  when  about  to  be  operated  on,  is  carried  to  the  cutting-shop,  where  it  is  cut  into 
pieces  equal  to  the  length  of  two  of  the  needles  about  to  be  made.  Fixed  up  against  the  wall 
of  the  shop  is  a ponderous  pair  of  shears  with  the  blades  uppermost.  The  workman  takes  probably 
a hundred  wires  at  once,  grasps  them  between  his  hands,  rests  them  against  a gage  to  determine 
the  length  to  which  they  are  to  be  cut,  places  them  between  the  blades  of  the  shears,  and  cuts 
them  by  pressing  with  his  body  or  thigh  against  one  of  the  handles  of  the  shears.  The  coil  is  thus 
reduced  to  twenty  or  thirty  thousand  pieces,  each  about  three  inches  long  ; and  as  each  piece  had  form- 
ed a portion  of  a curve  two  feet  in  diameter,  it  is  easy  to  see  that  it  must  necessarily  deviate  somewhat 
from  the  straight  line.  This  straightness  must  be  rigorously  given  to  the  wire  before  the  needle-making 
is  commenced ; and  the  mode  by  wliich  it  is  effected  is  one  of  the  most  remarkable  in  the  whole  manu- 
facture. In  the  first  place,  the  wires  are  annealed.  There  are  provided  a number  of  iron  rings,  each 
from  three  or  four  to  six  or  seven  inches  in  diameter,  and  a quarter  or  half  an  inch  in  thickness.  Two 
of  these  rings  are  placed  upright  on  their  edges,  at  a little  distance  apart ; and  within  them  are  placed 
many  thousands  of  wires,  which  are  kept  in  a group  by  resting  on  the  interior  edges  of  the  two  rings. 
In  this  state  they  are  placed  on  a shelf  in  a small  furnace,  and  there  kept  till  red-hot.  On  being 
taken  out,  at  a glowing  heat,  they  are  placed  on  an  iron  plate,  the  wires  being  horizontal,  and  the 
rings  in  which  they  are  inserted  being  vertical.  The  process  of  “rubbing”  (the  technical  name  for  the 
straightening  to  which  we  allude)  then  commences.  The  workman  takes  a long  piece  of  iron  or  steel, 
perhaps  an  inch  in  width,  and,  inserting  it  between  the  two  rings,  rubs  the  needles  backwards  and 
forwards,  causing  each  needle  to  roll  over  its  own  axis,  and  also  over  and  under  those  by  which  it  is 
surrounded.  The  noise  emitted  by  this  process  is  just  that  of  filing : but  no  filing  takes  place  ; for  the 
rubber  is  smooth,  and  the  sound  arises  from  the  rolling  of  one  wire  against  another.  The  rationale  of 
the  process  is  this: — the  action  of  one  wire  on  another  brings  them  all  to  a perfectly  straight  form, 
because  any  convexity  or  curvature  in  one  wire  would  be  pressed  out  by  the  close  contact  of  the 
adjoining  ones. 

Our  needles  have  now  assumed  the  form  of  perfectly  straight  pieces  of  wire,  say  a little  more  than 
three  inches  in  length,  blunt  at  both  ends,  and  dulled  at  the  surface  by  exposure  to  the  fire.  Each  of 
these  pieces  is  to  make  two  needles,  the  two  ends  constituting  the  points  ; and  both  points  are  made 
before  the  piece  of  wire  is  divided  into  two.  The  pointing  immediately  succeeds  the  rubbing,  and 
consists  in  grinding  down  each  end  of  the  wire  till  it  is  perfectly  sharp.  This  is  the  part  of  needle 
making  which  has  attracted  more  attention  than  all  the  rest  put  together.  The  surprising  manipula- 
tion by  which  the  needles  are  applied  to  the  grindstone ; the  rapidity  with  which  the  grinding  is 
effected ; the  large  earnings  of  the  men ; the  ruined  health  and  early  death  which  the  occupation 
brings  upon  them  ; the  efforts  which  have  been  made  to  diminish  the  hurtfulness  of  the  process  ; and 
the  resistance  with  which  these  efforts  have  been  met — all  merit  and  have  received  a large  measure 
of  attention.  Let  us  first  notice  the  process  itself,  and  then  the  peculiar  circumstances  attending  it. 

Some  of  the  needle-pointers  work  at  their  own  homes,  while  some  work  at  the  factories  ; but  the 
process  is  the  same  in  either  case.  The  pointing-room,  generally  situated  as  far  away  as  practicable 
from  the  other  rooms,  contains  small  grindstones,  from  about  eight  inches  to  twenty  inches  in  diam- 
eter, according  to  the  size  of  needle  to  be  pointed.  They  rotate  vertically,  at  a height  of  about  two 
feet  from  the  ground,  and  with  a velocity  frequently  amounting  to  two  thousand  revolutions  per 
minute.  The  stone  is  a particular  kind  of  grit  adapted  for  the  purpose  ; but  sometimes  it  flies  in 
pieces,  from  the  centrifugal  force  engendered  by  the  rapid  rotation,  and  in  such  cases  the  results  are 
often  fearful.  The  workman  sits  on  a stool,  or  horse,  a few  inches  distant  from  the  stone,  and  bends 
over  it  during  his  work.  Over  his  mouth  he  wraps  a large  handkerchief,  and,  as  he  can  perform  his 
work  nearly  as  well  in  the  dark  as  in  the  light,  he  is  sometimes  only  to  be  seen  by  the  vivid  cone  of 
sparks  emanating  from  the  steel  while  grinding.  The  vivid  light  reflected  on  his  pale  face,  coupled 
with  the  consciousness  that  we  are  looking  at  one  who  will  be  an  old  man  at  thirty,  and  who  is  being 
literally  “killed  by  inches”  while  at  work,  renders  the  processes  conducted  in  this  room  such  as  will 
not  soon  be  forgotten. 

The  needle-pointer  takes  fifty  or  a hundred  needles,  or  rather  needle  wires,  in  his  hand  at  once,  and 
holds  them  in  a peculiar  manner.  He  places  the  fingers  and  palm  of  one  hand  diagonally  over  those 
of  the  other,  and  grasps  the  needles  between  them,  all  the  needles  being  parallel.  The  thumb  of  the 
left  hand  comes  over  the  back  of  the  fingers  of  the  right,  and  the  different  knuckles  and  joints  are  so 
arranged  that  every  needle  can  be  made  to  rotate  on  its  own  axis  by  a slight  movement  of  the  hand, 
without  any  one  needle  being  allowed  to  roll  over  the  others.  He  grasps  them  so  that  the  ends  of  the 


NEEDLES. 


443 


wire  (one  end  of  eacli)  project  a small  distance  beyond  the  edge  of  the  hand  and  fingers,  and  these 
ends  he  applies  to  the  grindstone  in  the  proper  position  for  grinding  them  down  to  a point.  It  will 
easily  be  seen  that  if  the  wires  were  held  fixedly  the  ends  would  merely  be  bevelled  off,  in  the  man- 
ner of  a graver,  and  -would  not  give  a symmetrical  point ; but  by  causing  each  wire  to  rotate  while 
actually  in  contact  with  the  grindstone,  the  pointer  works  equally  on  all  sides  of  the  wire,  and  brings 
the  point  in  the  axis  of  the  wire.  At  intervals  of  every  few  seconds  he  adjusts  the  needles  to  a proper 
position,  against  a stone  or  plate,  and  dips  their  ends  in  a little  trough  of  liquid  between  him  and  the 
grindstone.  Each  wire  sends  out  its  own  stream  of  sparks,  which  ascends  diagonally  in  a direction 
opposite  to  that  at  which  the  workman  is  placed.  So  rapid  are  his  movements  that  he  will  point 
seventy  or  a hundred  needles,  forming  one  hand-grasp,  in  half  a minute — thus  getting  through  ten 
thousand  in  an  hour  ! 

The  circumstance  which  renders  this  operation  so  very  destructive  to  health  is,  that  the  particles  of 
steel,  separated  from  the  body  of  the  wire  by  the  friction  of  the  stone,  float  in  the  air  for  a time,  and 
are  then  inhaled  by  the  workman  ; and  the  same  remarks  apply  to  this  destructive  occupation  as  to 
fork-grinding. 

The  reader  will  bear  in  mind  that  the  state  of  our  embryo  needle  is  simply  that  of  a piece  of  dull 
straight  wire,  about  three  inches  long,  (supposing  6’s  to  be  the  size,)  and  pointed  at  both  ends.  The 
next  process  is  one  of  a series  by  which  two  eyes  or  holes  are  pierced  through  the  wire,  near  the  centre 
of  its  length,  to  form  the  eyes  of  the  two  needles  which  are  to  be  fashioned  from  the  piece  of  wire. 
A number  of  very  curious  operations  are  connected  with  this  process,  involving  mechanical  and  manip- 
ulative arrangements  of  great  nicety.  Those  who  are  learned  in  the  qualities  of  needles — as  that  they 
will  not  “ cut  in  the  eye,”  (fee. — will  be  prepared  to  expect  that  much  delicate  workmanship  is  involved 
m the  production  of  the  eyes,  and  they  will  not  be  in  error  in  so  supposing.  Most  of  the  improvements 
which  have  from  time  to  time  been  introduced  in  needle-making  relate  more  or  less  to  the  production 
of  the  eve.  In  the  commoner  kinds  of  needles  many  processes  are  omitted  which  are  essential  to  the 
production  of  the  finer  qualities,  but  it  will  show  the  whole  nature  of  the  operations  better  for  us  to 
take  the  case  of  those  which  involve  all  the  various  processes. 

After  being  examined  when  the  pointer  has  done  his  portion  of  the  work  to  them,  (an  examination 
wliicli  is  undergone  after  every  single  process  throughout  the  manufacture,)  the  wires  are  taken  to  the 
stamping-shop,  where  the  first  germ  of  an  eye  is  given  to  each  half  of  every  wire.  The  stamping- 
machine  consists  of  a heavy  block  of  stone,  supporting  on  its  upper  surface  a bed  of  iron ; and  on  this 
bed  is  placed  the  under  half  of  a die  or  stamp.  Above  this  is  suspended  a hammer,  weighing  about 
thirty  pounds,  which  has  on  its  lower  surface  the  other  half  of  the  die  or  impress.  The  hammer  is 
governed  by  a lever  moved  by  the  foot,  so  that  it  can  be  brought  down  exactly  upon  the  iron  bed. 
The  form  of  the  die  or  stamp  may  be  best  explained  by  stating  the  work  which  it  is  to  perform.  It  is 
to  produce  the  gutter,  or  channel,  in  which  the  eye  of  a needle  is  situated,  and  which  is  to  guide  the 
thread  in  the  process  of  “ threading  a needle.” 

But  besides  the  two  channels  or  gutters,  the  stampers  make  a perforation  partly  through  the  needle, 
as  a means  of  marking  exactly  where  the  eye  is  to  be.  The  device  on  the  two  halves  of  the  die  is 
consequently  a raised  one,  since  it  is  to  produce  depressions  in  the  wire.  The  workman,  holding  in  his 
hand  several  wires,  drops  one  at  a time  on  the  bed-iron  of  the  machine,  adjusts  it  to  the  die,  brings 
down  the  upper  die  upon  it  by  the  action  of  the  foot,  and  allows  it  to  fall  into  a little  dish  when  done. 
This  he  does  with  such  rapidity  that  one  stamper  can  stamp  four  thousand  wires,  equivalent  to  eight 
thousand  needles,  in  an  hour,  although  he  has  to  adjust  each  needle  separately  to  the  die. 

To  tins  process  succeeds  another,  in  which  the  eye  of  the  needle  is  pierced  through.  This  is  effected 
by  boys,  each  of  whom  works  at  a small  hand-press,  and  the  operation  is  at  once  a minute  and  inge- 
nious one.  The  boy  takes  up  a number  of  needles  or  wires,  and  spreads  them  out  like  a fan.  He  lays 
them  flat  on  a small  iron  bed  or  slab,  holding  one  end  of  each  wire  in  his  left  hand,  and  bringing  the 
middle  of  the  wire  to  the  middle  of  the  press.  To  the  upper  arm  of  the  press  are  affixed  two  hard- 
ened steel  points  or  cutters,  being  in  size  and  shape  exactly  corresponding  with  the  eyes  which  they 
are  to  form.  Both  of  these  points  are  to  pass  through  each  wire,  very  nearly  together,  and  at  a small 
distance  on  each  side  of  the  exact  centre  of  the  wire.  The  wire  being  placed  beneath  the  points,  the 
press  is  moved  by  hand,  the  points  descend,  and  two  little  bits  of  steel  are  cut  out  of  the  wire,  thereby 
forming  the  eyes  for  two  needles.  As  each  wire  becomes  thus  pierced,  the  boy  shifts  the  fanlike  array 
of  wires  until  another  one  comes  under  the  piercers,  and  so  on  throughout.  The  press  has  to  be  worked 
by  the  right  hand  for  piercing  each  wire ; and  the  head  of  the  boy  is  held  down  pretty  closely  to  his 
work,  in  order  that  he  may  see  to  eye  the  needles  properly  1 Were  not  the  wires  previously  pre- 
pared by  the  stamper,  it  would  be  impossible  thus  to  guide  the  piercers  to  the  proper  point ; but  this 
being  effected,  patience,  good  eyesight,  and  a steady  hand  effect  the  rest. 

There  are  several  processes  about  this  stage  which  are  effected  by  boys.  Some  of  these  little  la 
borers  take  the  needles  when  they  have  been  eyed,  ar.d  proceed  to  spit  them ; that  is,  to  pass  a 
wire  through  the  eye  of  every  needle.  Two  pieces  of  fine  wire  perhaps  three  or  four  inches  in  length, 
are  prepared,  the  diameter  corresponding  exactly  with  the  size  of  the  needle-eye.  These  two  pieces 
of  wire  are  held  in  the  right  hand,  parallel,  and  at  a distance  apart  equal  to  the  distance  between  the 
two  eyes  in  each  needle  wire.  The  pierced  needles,  being  held  in  the  left  hand,  are  successively 
threaded  upon  the  two  pieces  of  smaller  wire,  till,  by  the  time  the  whole  is  filled,  the  assemblage  has 
something  the  appearance  of  a fine-toothed  comb,  as  shown  in  Fig.  2910.  A workman  then  files  down 
the  bur  or  protuberances  left  on  the  side  of  the  eye  by  the  stamping. 

It  must  be  borne  in  mind  that  throughout  all  these  operations  the  needles  are  double ; that  is,  that 
the  piece  of  wire,  three  inches  in  length,  which  is  to  produce  two  needles  an  inch  and  a half  long  each, 
is  still  whole  and  undivided,  the  two  eyes  being  nearly  close  together  in  the  centre,  and  the  two 
points  being  at  the  ends.  Now,  however,  the  separation  is  to  take  place.  The  filer,  after  he  has 
brought  down  the  protuberances  on  each  wire,  but  before  he  has  laid  the  comb  of  wires  out  of  his  hand. 


444 


NEEDLES. 


bends  and  works  the  comb  between  his  hands  in  a peculiar  way,  until  he  has  broken  the  comb  inti 
two  halves,  each  half  spitted  by  one  of  the  fine  wires.  The  needles  have  arrived  at  something  like  thei* 
destined  shape  and  size:  for  they  are  of  the  proper  length,  and  have  eyes  and  points.  In  Fig.  2971 
we  can  trace  the  wire  through  the  processes  of  change  hitherto  undergone. 


2971. 


In  Fig.  2971,  A is  the  wire  for  two  needles;  B the  same,  pointed  at  one  end  ; C pointed  at  both 
ends  ; D the  stamped  impress  for  the  eyes  ; E the  eyes  pierced  ; F the  needles  just  before  separation  • 
def  Fig.  2972,  enlargements  of  D E F. 

But  although  we  have  now  little  bits  of  steel,  which  might  by  courtesy  be  called  needles,  they  have 
very  many  processes  to  undergo  before  they  are  deemed  finished,  especially  if,  in  accordance  with  our 
previous  supposition,  they  are  of  the  finer  quality.  There  are  very  many  workshops  which  we  have  yet 
to  glance  through,  the  first  of  which  is  that  of  the  soft-straightener.  The  filer  and  his  two  spitters  (who 
together  get  ready  about  four  thousand  needles  in  an  hour)  are  very  likely  to  bend  in  a slight  degree 
the  needles  under  operation ; and,  indeed,  so  are  likewise  the  stampers  and  the  eye-makers.  To  re- 
store the  straightness  of  the  wire  is  the  office  of  the  soft-straightener,  who  is  frequently  a female. 

The  soft-straightener  is  seated  in  front  of  a bench,  near  the  front  edge  of  which  is  placed  a small 
steel  plate.  On  this  plate  the  needles  are  placed,  parallel  or  nearly  so;  the  straightener  employed  is 
a steel  bar,  from  a foot  to  half  a yard  long,  an  inch  or  two  in  width,  and  perhaps  a quarter  of  an  inch 
thick.  It  is  turned  upwards  a little  at  the  two  ends,  so  as  to  be  somewhat  convex  at  the  lower  sur- 
face, and  is  held  by  both  hands  at  the  two  ends.  By  a curious  management  of  this  instrument,  the 
6oft-straightener  separates  each  individual  needle  from  the  group  of  which  it  forms  a part,  and  rolls 
it  over  two  or  three  times  with  the  lower  surface  of  the  instrument,  pressing  it  against  the  iron  plate, 
and  thus  working  out  any  curvatures  or  irregularities  which  may  have  been  given  to  it  by  the  previous 
operations.  So  quickly  is  this  done  that  three  thousand  needles  can  be  thus  straightened  in  an  hour  by 
one  person. 

The  needles  are  by  this  time  pointed,  eyed,  and  straightened ; but  before  they  can  be  brought  to  that 
beautifully  finished  state  with  which  we  are  all  familiar,  it  is  necessary  that  they  should  be  hardened 
and  tempered  by  a peculiar  application  of  heat.  After  being  examined,  to  see  that  the  preceding  pro- 
cesses are  fitly  performed,  the  needles  are  taken  to  a shop  provided  with  ovens  or  furnaces.  They  are 
laid  down  on  a bench,  and  by  means  of  two  trowel-like  instruments,  spread  in  regular  thick  layers  on 
narrow  plates  or  trays  of  iron.  In  this  way  they  are  placed  on  a shelf  or  grating  in  a heated  furnace 
When  the  proper  degree  of  heating  has  been  effected,  the  door  is  opened,  and  the  needles  are  shifted 
from  the  iron  tray  into  a sort  of  colander  or  perforated  vessel  immersed  in  cold  water  or  oil.  When 
they  are  quite  cooled,  the  hardening  is  completed  ; and  if  it  has  been  effected  in  water,  the  needles  are 
simply  dried ; but  if  in  oil,  they  are  well  washed  in  an  alkaline  liquor  to  free  them  from  the  oil.  Then 
ensues  the  tempering  processes.  The  needles  are  placed  on  an  iron  plate,  heated  from  beneath,  and 
moved  about  with  two  little  trowels  until  every  needle  has  been  gradually  brought  to  a certain  desired 
temperature. 

Notwithstanding  the  soft-straightening  which  the  needles  underwent  after  they  were  pointed  and 
eyed,  they  have  become  slightly  distorted  in  shape  by  the  action  of  the  heat  in  the  processes  just  de- 
scribed, and  to  rectify  this  they  undergo  the  operation  of  hammer-straightening.  A number  of  female* 
are  seen  seated  at  a long  bench,  each  with  a tiny  hammer,  giving  a number  of  light  blows  to  th"'  •'c“» 


NEEDLES. 


445 


dies ; the  needles  being  placed  on  a small  steel  block  with  a very  smooth  upper  surface.  This  is  rathei 
a tedious  part  of  the  manufacture,  the  workwoman  not  being  able  to  straighten  more  than  live  hundred 
needles  in  an  hour,  a degree  of  quickness  much  less  than  that  which  we  have  had  hitherto  to  notice. 

We  leave  the  tinkling  hammers,  and  follow  the  needles  to  the  only  part  of  the  manufacture  which  in- 
volves apparatus  other  than  of  a very  small  size.  This  is  the  scouring  process,  performed  by  machines, 
looking  like  mangles,  or,  perhaps  more  correctly,  like  marble  polishing-machines — a square  slab  or  rub- 
ber working  to  and  fro  on  a long  bed,  stone,  or  bench.  The  object  of  this  process  is  to  rub  the  needles 
one  against  another  for  a very  long  period,  till  the  surfaces  of  all  have  become  perfectly  smooth,  clean, 
and  true.  This  is  effected  in  a curious  manner.  A strip  of  very  thick  canvas  is  laid  out  open  on  a 
bench,  and  on  this  a large  heap  of  needles,  amounting  to  perhaps  twenty  or  thirty  thousand,  is  laid,  all 
the  needles  being  parallel  one  with  another,  and  with  the  length  of  the  cloth.  The  needles  are  then 
slightly  coated  with  a mixture  of  emery  and  oil,  and  tied  up  tightly  in  the  canvas,  the  whole  forming  a 
compact  roll  about  two  feet  long  and  two  inches  in  thickness.  Twenty-four  rolls  of  needles  being  thus 
prepared,  comprising  probably  six  hundred  thousand  needles  in  all,  they  are  placed  under  the  rubbers 
of  the  scouring-machines,  tvTo  rolls  to  each  machine.  A steam-engine  or  a water-wheel  then  gives  to 
the  rubbers,  by  connected  mechanism,  a reciprocating  or  backward  and  forward  motion,  pressing  heavily 
on  the  rolls  of  needles,  and  causing  all  the  needles  of  each  bundle  to  roll  one  over  another.  By  this 
action  an  intense  degree  of  friction  is  exerted  among  the  needles,  whereby  each  one  is  rubbed  smooth 
by  those  which  surround  it.  For  eight  hours  uninterruptedly  this  rubbing  or  scouring  is  carried  on ; 
after  which  the  needles  are  taken  out,  washed  in  suds,  placed  in  new  pieces  of  canvas,  touched  with  a 
new  portion  of  emery  and  oil,  and  subjected  to  another  eight  hours’  friction.  Again  and  again  is  this 
repeated,  insomuch  that  for  the  very  finest  needles  the  process  is  performed  five  or  six  times  over,  each 
time  during  eight  hours’  continuance. 

The  needles  are  examined  after  being  scoured,  and  are  placed  in  a small  tin  tray,  wdiere,  by  shaking 
and  vibrating  in  a curious  manner,  they  are  all  brought  into  parallel  arrangement.  From  thence  they 
are  removed  into  flat  paper  trays,  in  long  rows  or  heaps,  and  passed  on  to  the  “ header,”  generally  a 
little  girl,  whose  office  is  to  turn  all  the  heads  one  way  and  all  the  points  the  other.  This  is  one  among 
the  many  simple  but  curious  processes  involved  in  this  very  curious  manufacture,  which  surprise  us  by 
the  rapidity  and  neatness  of  execution.  The  girl  sits  with  her  face  towards  the  window,  and  has  the 
needles  ranged  in  a row  or  layer  before  her,  the  needles  being  parallel  with  the  window.  She  draws 
out  laterally  to  the  right  those  which  have  their  eyes  on  the  right  hand,  into  one  heap ; and  to  the  left 
those  which  have  their  eyes  in  that  direction,  in  another. 

About  this  time  too  the  needles  are  examined  one  by  one,  to  remove  those  which  have  been  broken 
or  injured  in  the  long  process  of  scouring ; for  it  sometimes  happens  that  as  many  as  eight  or  ten  thou- 
sand out  of  fifty  thousand  are  spoiled  during  this  operation.  Most  ladies  are  conversant  with  the  merits 
of  “ drilled-eyed  needles,”  warranted  “not  to  cut  the  thread.”  These  are  produced  by  a modern  improve- 
ment, whereby  the  eye,  produced  by  the  stamping  and  piercing  processes  before  described,  is  drilled 
with  a very  fine  instrument,  by  which  its  margin  becomes  as  perfectly  smooth  and  brilliant  as  any  other 
part  of  the  needle.  To  effect  this  the  needle  is  first  “ blued,”  that  is,  the  head  is  heated  so  as  to  give  it 
the  proper  temper  for  working.  Then  the  eye  is  counter-sunk,  which  consists  in  bevelling  off  the  eye 
by  means  of  a kind  of  triangular  drill,  so  that  there  may  be  no  sharp  edge  between  the  eye  itself  and 
the  cylindrical  shaft  of  the  needle.  Next  comes  the  drilling.  Seated  at  a long  bench  are  a number  of 
men  and  boys,  with  small  drills  working  horizontally  with  great  rapidity.  The  workman  takes  up  a 
few  needles  between  the  finger  and  thumb  of  his  left  hand,  spreads  them  out  like  a fan  with  the  eyes 
uppermost,  brings  them  one  at  a time  opposite  the  point  of  the  drill,  governs  the  handle  or  lever  of  the 
drill  with  his  right  hand,  and  drills  the  eye,  which  is  equivalent  to  making  it  circular,  even,  smooth,  and 
polished.  lie  shifts  the  thumb  and  finger  round,  so  as  to  bring  all  the  needles  in  succession  under  the 
action  of  the  drill ; and  he  thus  gets  through  his  work  with  much  rapidity.  The  preparation  of  the 
drills,  which  are  small  wires  of  polished  steel  three  or  four  inches  long,  is  a matter  of  very  great  nicety, 
and  on  it  depends  much  of  that  beauty  of  production  which  constitutes  the  pride  of  a modern  needle- 
manufacturer. 

The  needles  are  next  applied  to  the  edges  of  little  wheels  revolving  with  great  rapidity,  some  in 
tended  for  what  is  termed  “grinding”  the  needles,  and  some  for  polishing.  The  men  are  seated  on  low 
stools,  each  in  front  of  a revolving  wheel,  which  is  at  a height  of  perhaps  two  feet  from  the  ground 
The  grinding-wheels  are  very  small,  not  above  five  or  six  inches  in  diameter ; they  are  made  of  grit 
stone,  and  are  attached  to  a horizontal  axis.  The  grinding  here  alluded  to  is  not  such  as  might  be  sup 
posed,  relating  to  the  points  of  the  needles,  but  has  reference  simply  to  the  heads,  which  have  not  yet 
had  a rounded  form  given  to  them.  The  workman  takes  up  a layer  or  row  of  needles  between  the  fin 
gers  and  thumbs  of  the  two  hands,  and  applies  the  heads  to 

the  stones  in  such  a manner  as  to  grind  down  any  small  as-  29~3. 

perities  on  the  surface.  As  the  small  grindstones  are  revolving 
three  thousand  times  in  a minute,  it  is  plain  that  the  steel  may 
soon  be  sufficiently  worn  away  by  a slight  contact  with  the 
periphery  of  the  stone. 

The  grinders  and  the  polishers  sit  near  together,  so  that  the 
latter  take  up  the  series  of  operations  as  soon  as  the  former 

have  finished.  The  polishing-wheels  consist  of  wood  coated  I I I 

with  buff  leather,  whose  surface  is  slightly  touched  with  polish- 
ing-paste. Against  these  wheels  the  polishers  hold  the  nee- 
dles, applying  every  part  of  the  cylindrical  surface  in  succes- 

sion ; first  holding  them  by  the  pointed  end,  and  then  by  the  | JJ 

eye  end.  About  a thousand  in  an  hour  can  thus  be  polished 
by  each  man ; and  when  they  leave  his  hands  the  needles  are  finished.  A magnified  representation 


d 


446 


NUT-CUTTING  MACHINE. 


of  the  eye  in  different  states  will  assist  these  details,  a , Fig.  2973,  represents  a needle  with  the  ev t 
and  head  rough ; b,  the  head  filed  and  formed ; c,  the  eye  countersunk ; d represents  a needle  drilled 
and  finished. 

NICKEL.  A white  metal,  ductile,  malleable,  attracted  by  the  magnet,  and  which,  like  iron,  may  be 
rendered  magnetic.  Its  specific  gravity  when  hammered  is  about  9.  It  is  rather  more  fusible  than  pure 
iron ; is  not  altered  by  exposure  to  air  and  moisture  at  common  temperatures,  but  is  slowly  oxidized 
at  a red  heat.  It  is  found  in  all  meteoric  iron  ; but  its  principal  ore  is  a copper-colored  mineral  found 
in  Westphalia,  and  called  kupfernickel,  nickel  being  a term  of  detraction  used  by  the  German  miners, 
who  expected  from  the  color  of  the  ore  to  find  that  it  contained  copper.  The  salifiable  oxide  of  nickel 
consists  of  30  nickel  + 8 oxygen.  Its  salts  are  mostly  of  a grass-green  color,  and  the  ammoniacal  solu- 
tion of  its  oxide  is  deep  blue,  like  that  of  copper.  See  Metals  and  Alloys. 

NONAGON.  A figure  of  nine  angles  and  nine  sides.  The  angle  at  the  centre  of  a nonagon  is  40°, 
the  angle  subtended  by  its  sides  140°,  and  its  area  ■when  the  side  is  1 = GT818242,  consequently  the 
square  of  the  side  X 6T818242  will  give  the  area  of  the  figure. 

NORMAL.  A term  sometimes  used  for  perpendicular.  In  the  geometry  of  curve  lines,  the  normal 
to  a curve  at  any  point  is  a straight  line  perpendicular  to  the  tangent  at  that  point,  and  included  between 
the  curve  and  the  axis  of  the  abscissa. 

NUT-CUTTING  MACHINE — By  A.  Milne,  Glasgow.  This  is  a very  convenient  tool  in  works 


where  the  chief  business  is  the  construction  of  the  more 
finished  quality  of  machinery.  In  these  the  nuts  are  usu- 
ally dressed  to  correspond  with  the  other  parts  of  the  work. 
It  is  not  commonly  employed  by  millwrights,  although  its 
use  would  often  be  a material  saving  of  time  in  the  fitting- 
shop,  and  especially  in  out-door  work,  in  reducing  the  nuts, 
and  consequently  the  number  of  keys  required,  to  a few 
definite  sizes. 

Fig.  2974  is  a side  elevation.  Fig.  2975  an  end  eleva- 
tion. Fig.  2976  a general  plan  of  the  machine. 

a is  the  main-spindle,  having  a spur-wheel  w,  and  the 
cutter  x,  keyed  on  it. 

k,  the  driving-shaft,  carrying  fast  and  loose  pulleys,  and 
having  the  pinion  p keyed  on  it,  and  which  geers  into  the 
wheel  w. 

r,  the  nut-holder : the  nuts  are  screwed  on  a pin  which 
is  tightened  by  a nut  on  the  under  side,  seen  in  Fig.  2974, 
by  a counter-nut;  different  sizes  of  these  mandrel-pins 
or  screws  are  of  course  required  for  different  sizes  of 
nuts. 

b,  a hand-wheel,  upon  the  end  of  a slide-lever  for  carry- 
ing the  nut  across  the  end  of  the  cutter. 

c,  a shaft  carrying  a set  of  grooved  pulleys,  connected 
by  a cord,  with  a corresponding  set  on  the  shaft  k. 

s,  an  endless  screw  on  the  shaft  c,  and  working  into  the 
wheel  h,  on  the  slide-screw,  to  render  the  machine  self- 
acting 


2375. 


OILS. 


447 


rn,  a handle  to  disengage  the  self-acting  feed  when  desired.  The  upper  part  of  the  slide  on  which 
the  nuts  are  fixed  turns  round,  and  is  held  in  the  position  required  by  the  handle  n,  the  end  of  which  is 
pressed,  by  a spring,  into  notches  on  the  rim  of  the  table.  See  Fig.  297  6. 

u , a screw  for  moving  forward  the  head  carrying  the  cutter,  so  as  to  adjust  it  to  the  size  of  nut  to  bo 
cut.  This  operation  is  accomplished  by  hand. 


OCTAGOK  In  geometry,  a plane  figure  contained  by  eight  sides,  and  consequently  having  eight 
angles.  When  the  sides  and  angles  are  equal,  it  is  a regular  octagon.  If  a denote  the  side  of  a regular 
octagon,  the  area  is  a 3 X 2 tan.  67^°  = a"  X 4'828427. 

OCTOHEDRON.  In  geometry,  one  of  the  five  regular  solids,  or  Platonic  bodies,  contained  under 
eight  equal  and  equilateral  triangles.  Let 

A = the  linear  edge  or  side, 

B = the  whole  surface, 

C = the  solid  content, 

R = radius  of  circumscribed  sphere, 
r — radius  of  inscribed  sphere  ; then 
A = rN/6  = RV2  = v/(JBv/3)  = 7|C72), 

B = 12  r V 3 = 4 R V3  = 2 A V3, 

C =4  r V 3 = f R3  = *-  A V 2, 

R = rv/3  = iAv/2=WBv/I  = 7IC, 

r = iR%/3=^Av/6=lv/(Bv/S). 

ODOMETER.  An  instrument  attached  to  the  wheel  of  a carriage,  by  which  the  distance  passed 
over  is  measured. 

OILS.  The  term  oil  is  applied  to  two  dissimilar  and  distinct  organic  products,  which  are  usually 
called  fixed  oils  and  volatile  oils.  The  fixed  or  fat  oils  are  either  of  vegetable  or  animal  origin ; they 
are  compounds  of  carbon,  hydrogen,  and  oxygen;  the  relative  proportions  vary  but  little  in  the  several 
species.  The  following  analyses  of  olive  and  spermaceti  oil  may  be  assumed  as  types  of  the  rest : 

Olive  oil.  Spermaceti  oil. 


Carbon 772  780 

Hydrogen 133  118 

Oxygen 95  102 


1000  1000 

Th q fixed  oils  abound  in  the  fruit  and  seed  of  certain  plants  ; they  are  lighter  than  water,  unctuous, 
and  insipid,  or  nearly  so ; some  of  these  require  a low  temperature  for  their  congelation,  such  as  linseed 
oil ; others,  such  as  olive  oil,  concrete  at  a temperature  higher  than  the  freezing  point  of  water ; some 
are  solid  at  common  temperatures,  such  as  cocoa-nut  oil.  Some  of  these  oils  when  exposed  to  air  absorb 
oxygen,  and  gradually  harden,  forming  a kind  of  varnish ; these  are  called  drying  oils,  and  are  the  basis 
of  paints,  such  as  linseed  oil ; others  become  rancid,  as  almond  oil.  All  these  oils,  like  the  different 
kinds  of  fat,  consist  of  two  proximate  principles,  called  stearine  and  elaine ; the  former  is  the  fatty  por- 
tion, which  first  concretes  on  cooling  the  oil,  and  from  which  the  elaine,  or  oily  portion,  may  be  separ- 
ated by  pressure.  These  oils  cannot  be  volatilized  without  decomposition.  At  a red-heat  they  are 
resolved  into  volatile  and  gaseous  products,  among  which  carburetted  hydrogen,  in  several  of  its  forms, 
predominates ; hence  the  use  of  these  oils,  when  volatilized  and  burned  by  the  aid  of  a wick,  as  sources 
of  artificial  fight.  The  action  of  the  alkali  on  the  fat  oils  is  highly  important,  as  forming  soap. 

The  volatile  oils  are  generally  obtained  by  distilling  the  vegetables  which  afford  them  with  water ; 
they  fluctuate  in  density  a little  on  either  side  of  water : they  are  sparingly  soluble  in  water,  forming 
the  perfumed  or  medicated  waters,  such  as  rose  and  peppermint  water ; they  are  mostly  soluble  in 
alcohol,  forming  essences.  A few  of  them,  such  as  oil  of  turpentine,  of  lemon  peel,  of  copivi  balsam,  &c., 
are  hydro-carbons,  that  is,  consist  of  carbon  and  hydrogen  only ; the  greater  number,  however,  contain 
oxygen  as  one  of  their  ultimate  elements.  They  are  chiefly  used  in  medicine  and  in  perfumery,  and  a 


448 


OILS. 


few  of  them  are  extensively  employed  in  the  arts  as  vehicles  for  colors,  and  in  the  manufacture  of  var 
nislies ; this  is  especially  the  case  with  oil  of  turpentine. 

Linseed,  rape-seed,  poppy-seed,  and  other  oleiferous  seeds  were  formerly  treated  for  the  extraction  ol 
their  oil,  by  pounding  in  hard  wooden  mortars  with  pestles  shod  with  iron,  set  in  motion  by  cams  driven 
by  a shaft  turned  with  horse  or  water  power ; then  the  triturated  seed  was  put  into  woollen  bags  which 
were  wrapped  up  in  hair-cloths,  and  squeezed  between  upright  wedges  in  press-boxes  by  the  impulsion 
of  vertical  rams  driven  also  by  a cam  mechanism.  In  the  best  mills  upon  the  old  construction,  the  cakes 
obtained  by  this  first  wedge-pressure  were  thrown  upon  the  bed  of  an  edge-mill,  ground  anew,  and  sub- 
jected to  a second  pressure,  aided  by  heat  now  as  in  the  first  case.  These  mortars  and  press-boxes 
constitute  what  are  called  Dutch  mills.  They  are  still  in  very  general  use,  and  are  by  many  persons 
supposed  to  be  preferable  to  the  hydraulic  presses. 


2977. 


In  extracting  oil  from  seeds  two  processes  are  required — 1st , trituration  ; 2d,  expression  ; and  the 
steps  are  as  follows  : 

L Bruising  under  revolving  heavy-edge  mill-stones,  in  a circular  bed  or  trough  of  iron,  bedded  on 
granite. 

2.  Heating  of  the  bruised  seeds,  by  the  heat  either  of  a naked  fire  or  of  steam. 

3.  First  pressure  or  crushing  of  the  seeds,  either  by  wedges,  screw,  or  hydraulic  presses. 

4.  Second  crushing  of  the  seed-cakes  of  the  first  pressure. 

5.  Heating  the  bruised  cakes : and  6.  A final  crushing. 

The  seeds  are  now  very  generally  crushed  first  of  all  between  two  iron  cylinders  revolving  in  opposite 
directions,  and  fed  in  from  a hopper  above  them  ; after  which  they  yield  more  completely  to  the  tritu- 
rating action  of  the  edge-stones,  which  are  usually  hooped  round  with  a massive  iron  ring.  A pair  ol 
edge  mill-stones  of  about  V or  Ti  feet  in  diameter,  and  25  or  26  inches  thick,  weighing  from  V to  8 tons, 
can  crush,  in  12  hours,  fro.n  2^-  to  3 tons  of  seeds.  The  edge  mill-stones  serve  not  merely  to  grind  the 


OILS. 


449 


seeds  at  first,  but  to  triturate  the  cakes  after  they  have  been  crushed  in  the  press.  Old  dry  seeds  some- 
times require  to  be  sprinkled  with  a little  water  to  make  the  oil  come  more  freely  away  ; but  this 
practice  requires  great  care. 

The  apparatus  for  heating  the  bruised  seeds  consists  usually  of  cast-iron  or  copper  pans,  with  stirrers 
moved  by  machinery.  Figs.  2977,  2978,  2979,  and  2980  represent  the  heaters  by  naked  fire,  as  mounted 
in  Messrs.  Maudsley  and  Field’s  seed-crushing  mills,  on  the  wedge  or  Dutch  plan. 

Fig.  2977  is  an  elevation  or  side  view  of  the  fireplace  of  a naked  heater. 

Fig.  2978  is  a plan  in  the  line  U U of  Fig.  2977. 

Fig.  2979  is  an  elevation  and  section  parallel  to  the  line  V V of  Fig.  2978. 

Fig.  2980  is  a plan  of  the  furnace,  taken  above  the  grate  of  the  fireplace. 

A,  fireplace  shut  at  top  by  the  cast-iron  plate  B,  called  the  fire-plate.  C,  iron  ring-pan,  resting  on  the 
plate  B,  for  holding  the  seeds,  which  is  kept  in  its  place  by  the  pins  or  bolts  a.  D,  funnels,  britchen, 
into  which,  by  pulling  the  ring-case  c by  the  handles  b b,  the  seeds  are  made  to  fall,  from  which  they 
pass  into  bags  suspended  to  the  hooks  c. 

2981.  2982. 


E,  Fig.  2979,  the  stirrer  which  prevents  the  seeds  from  being  burned  by  continued  contact  with  the 
hot  plate.  It  is  attached  by  a turning-joint  to  the  collar  F,  which  turns  with  the  shaft  G,  and  slides  up 
and  down  upon  it.  H,  a bevel-wheel  in  geer  with  the  bevel-wheel  I,  and  giving  motion  to  the  shaft  G. 
K,  a lever  for  lifting  up  the  agitator  or  stirrer  E.  e,  a catch  for  holding  up  the  lever  K,  when  it  has 
been  raised  to  a proper  height. 

Fig.  2981,  front  elevation  of  the  wedge  seed-crushing  machine,  or  wedge-press. 

Fig.  2982,  section,  in  the  line  XX  of  Fig.  2983. 

A A,  upright  guides,  or  frame-work  of  wood.  B B,  side  guide-rails.  D,  driving  stamper  of  wood 
which  presses  out  the  oil ; C,  spring  stamper,  or  relieving  wedge,  to  permit  the  bag  to  be  taken  out 
when  sufficiently  pressed.  E is  the  lifting-shaft,  having  rollers  b b b b , Fig.  2982,  which  lift  the  stampers 
by  the  cams  a a,  Fig.  2982.  F is  the  shaft  from  the  power-engine,  on  wnich  the  lifters  are  fixed.  G is 
the  cast-iron  press-box,  in  which  the  bags  of  seed  are  placed  for  pressure,  laterally  by  the  force  of  the 
wedge. 

In  Figs.  2981  and  2984,  o is  the  spring,  or  relieving  wedge,  e,  lighter  rail;  d,  lifting-rope  to  ditto; 
ffff  flooring  overhead,  g,  the  back  iron  or  end-plate,  minutely  perforated,  h,  the  horse-hair  bags, 
(called  hairs,)  containing  the  flannel  bag  charged  with  seed ; i,  the  dam-block ; m,  the  spring-wedge. 

Fig.2983 , A,  upright  guides ; 0 and  D,  spring  and  driving  stampers ; E,  lifting-roller ; F,  lifting-shaft, : 
a a,  cams  of  stampers. 

Fig.  2984,  a view  of  one  set  of  the  wedge-boxes,  or  presses,  supposing  the  front  of  them  to  be  removed, 
o,  driving-wedge ; g,  back  iron ; h,  hairs ; i,  dam-block ; k,  speering  or  oblique  block,  between  the  two 
stampers  ; l and  n,  ditto ; rn.  spring-wedge. 

Vol.  II.— 29 


450 


OIL  TEST. 


When  in  the  course  of  a few  minutes  the  bruised  seeds  are  sufficiently  heated  in  the  pans,  the  doubl« 
door  F F is  withdrawn,  and  they  are  received  in  the  bags  below  the  aperture  G.  These  bags  are  made 
of  strong  twilled  woollen  cloth,  woven  on  purpose.  They  are  then  wrapped  in  a hair-cloth,  lined  with 
.eather. 

The  first  pressure  requires  only  a dozen  blows  of  the  stamper,  after  which  the  pouches  are  left  alone 
for  a few  minutes  till  the  oil  has  had  time  to  flow  out ; in  which  interval  the  workmen  prepare  fresh 
bags.  The  former  are  then  unlocked,  by  making  the  stamper  fall  upon  the  loosening  wedge  or  key  to. 


2933. 


The  weight  of  the  stampers  is  usually  from  500  to  600  pounds ; and  the  height  from  which  they  fall 
upon  the  wedges  is  from  16  to  21  inches. 

Such  a mill  as  that  now  described  can  produce  a pressure  of  from  50  to  15  tons  upon  each  cake  of  tho 
following  dimensions:  8 inches  in  the  broader  base,  1 inches  in  the  narrower,  18  inches  in  the  height; 
altogether  nearly  140  square  inches  in  surface,  and  about  £ of  an  inch  thick. 

Adulteration  of  oils. — M.  Heidenreich  has  found  in  the  application  of  a few  drops  of  sulphuric  acid  to 
a film  of  oil,  upon  a glass  plate,  a means  of  ascertaining  its  purity.  The  glass  plate  should  be  laid  upon 
a sheet  of  white  paper,  and  a drop  of  the  acid  let  fall  on  the  middle  of  ten  drops  of  the  oil  to  be  tried. 

With  the  oil  of  rape-seed  and  turnip-seed,  a greenish-blue  ring  is  gradually  formed  at  a certain  dis- 
tance from  the  acid,  and  some  yellowish-brown  bands  proceed  from  the  centre. 

With  oil  of  black  mustard,  in  double  the  above  quantity,  also  a bluish-green  color. 

With  whale  and  cod  oil,  a peculiar  centrifugal  motion,  then  a red  color,  increasing  gradually  in  inten- 
sity ; and  after  some  time  it  becomes  violet  on  the  edges. 

With  oil  of  cameline,  a red  color,  passing  into  bright  yellow. 

Olive-oil,  pale  yellow,  into  yellowish  green. 

Oil  of  poppies  and  sweet  almonds,  canary  yellow,  passing  into  an  opaque  yellow. 

Of  linseed,  a brown  magma,  becoming  black. 

Of  tallow  or  oleine,  a brown  color. 

In  testing  oils,  a sample  of  the  oil  imagined  to  be  present  should  be  placed  alongside  of  the  actual 
oil,  and  both  be  compared  in  their  reactions  with  the  acid.  A good  way  of  approximating  to  the"  knowl- 
edge of  an  oil  is  by  heating  it,  when  its  peculiar  odor  becomes  more  sensible. 

OIL  TEST.  The  most  valuable  quality  in  an  oil  intended  for  the  lubrication  of  machinery  is  perma- 
nent fluidity.  That  oil  which  will  for  the  greatest  length  of  time  remain  fluid  in  contact  with  the  iron 
or  brass  is,  without  doubt,  the  most  useful  for  the  purpose.  Hence  the  necessity  of  including  the  ele- 
ment of  time  in  any  experiment  on  the  comparative  value  of  such  oils. 

Some  idea  may  be  formed  of  the  importance  of  having  the  means  of  arriving  at  correct  conclusions 
on  this  subject,  when  we  know  that  in  some  spinning  establishments  there  are  upwards  of  50,000  spin- 
dles in  motion  at  the  rate  of  4000  or  5000  revolutions  per  minute ! The  slightest  defect  in  the  quality 
of  the  oil  in  such  a case,  by  its  becoming  viscid,  tells  in  the  most  serious  way  upon  the  quantity  of  fuel 
consumed  in  generating  the  power  required  to  maintain  at  this  high  velocity  such  a multitude  of  moving 
parts.  The  slight  increase  of  fluidity  consequent  on  the  rise  of  temperature,  caused  by  the  lighting  of 
the  gas  in  the  rooms  of  a cotton-mill,  makes  a difference  of  several  horses-power  in  the  duty  of  the  en- 
gine of  an  extensive  establishment. 

The  oil  test  we  have  now  to  describe,  and  which  is  an  invention  of  Mr.  Nasmyth’s,  consists  of  a plate 
of  iron  4 inches  wide  by  6 feet  long,  on  the  upper  surface  of  which  six  equal-sized  grooves  are  planed. 
This  plate  is  placed  in  an  inclining  position,  say  1 inch  in  6 feet.  The  mode  of  using  it  is  as  follows  : — 
Suppose  we  have  six  varieties  of  oil  to  test,  and  we  are  desirous  to  know  which  of  them  will,  for  the 
longest  time,  retain  its  fluidity  when  in  contact  with  iron  and  exposed  to  the  action  of  the  air ; all  we 
have  to  do  is  to  pour  out  simultaneously  at  the  upper  end  of  each  inclined  groove  an  equal  quantity  of 
each  of  the  oils  under  examination.  This  is  very  conveniently  and  correctly  done  by  means  of  a row  of 
small  brass  tubes.  The  six  oils  then  make  a fair  start  on  their  race  down  hill ; some  get  ahead  the  first 
day,  and  some  keep  ahead  the  second  and  third  day,  but  on  the  fourth  or  fifth  day  the  truth  begins  to  come 
out ; the  bad  oils,  whatever  good  progress  they  may  have  made  at  the  outset,  come  soon  to  a stand- 
still by  their  gradual  coagulation,  while  the  good  oil  holds  on  its  course ; and  at  the  end  of  eight  or  ten 
days  there  is  no  doubt  left  as  to  which  is  the  best ; it  speaks  for  itself,  having  distanced  its  competitors 
by  a long  way.  Linseed  oil,  which  makes  capital  progress  the  first  day,  is  set  fast  after  having  travelled 
18  inches,  while  second-class  sperm  beats  first-class  sperm  by  14  inches  in  nine  days,  having  traversed 
in  that  time  5 feet  8 inches  down  the  hill.  The  following  table  will  shew  the  state  of  the  oil-race  after 
a nine  days’  run  : 


ORTHOCHRONOGRAPH. 


45] 


Results  of  Oil  Test. 


Description  of  Oil. 

First. 

Second. 

Third. 

Fourth. 

Fifth. 

Sixth. 

Seventh. 

Eighth. 

Ninth. 

ft. 

in. 

in. 

ft. 

in. 

ft. 

in. 

ft. 

in. 

ft. 

in. 

«. 

in. 

ft. 

in. 

ft. 

in. 

Best  sperm  oil  

2 

8i 

4 

2 

4 

5f 

4 

6 

4 

6 

4 

6 

4 

uy 

Stat. 

i 

Common  sperm  oil 

i 

7 

3 

9 

4 

04 

4 

11 

5 

H 

5 

4 

5 

5 

7® 

5 

8 

Galiopoli  oil  

0 

10  J 

1 

24 

1 

6 

1 

64 

i 

n 

i 

84 

1 

9 

1 

94 

i 

94 

Lard  oil 

0 

104 

0 

104 

0 

10J 

0 

104 

0 

114 

Stat. 

Rape  oil  

1 

24 

1 

04 

1 

7 

1 

n 

1 

74 

1 

74 

1 

74 

1 

74 

Stat. 

Linseed  oil 

1 

64 

1 

6 

1 

04 

1 

64 

1 

64 

1 

64 

1 

64 

_st 

at. 

For  nice  machinery  nothing  has  been  found  to  equal  the  best  spermaceti  oil,  and  it  is  a mistaken  econ- 
omy which  applies  inferior  oil  to  good  machinery. 


OMNIBUS  CANE.  Invented  by  S.  W.  Francis  of  New  York,  to  enable  a passenger  at  the  extremity 
of  the  stage  to  pass  up  his  fare  to  the  driver  without  incommoding  others.  The  cane  is  a common  ser- 
viceable stick.  Fig.  2984  represents  the  lower  end  of  the  cane ; m is  the  receptacle  for  the  coin,  here, 
three  cent  pieces,  which  are  put  in  by  removing  the  bottom  d,  and  the  spring  i and  follower  j,  which, 
after  the  insertion  of  say  40  coin,  are  replaced.  At  the  upper  end  of  the  cane  is  a small  stud  6,  which 
on  being  depressed  gives  a longitudinal  motion  to  the  rod  or  wire  a , which  withdraws  h from  the  opening 
c,  gaged  to  the  thickness  of  two  coins,  which  are  thrust  out  by  the  bell-crank  g.  The  small  spiral 
spring,  as  the  stud  is  relieved,  presses  li  against  the  coin  till  taken  out  by  the  driver. 

OPSIOMETER.  An  instrument  for  measuring  the  extent  of  the  limits  of  distinct  vision  in  different 
individuals.  The  principle  of  M.  Lehot’s  contrivance  depends  on  the  appearance  presented  by  a straight 
line  placed  very  near  the  eye,  in  the  direction  of  its  axis ; and  the  principle  is  carried  into  practice  by 
placing  a thread  of  white  silk  on  a narrow  rule  covered  with  black  velvet,  and  furnished  with  a suitable 
apparatus  for  marking  the  exact  points  at  which  the  thread  begins  and  ceases  to-be  distinctly  seen,  when 
held  in  a certain  position  with  respect  to  the  eye. 

ORDINATE.  In  geometry,  a straight . line  drawn  from  any  point  in  a curve  perpendicularly  tc 
another  straight  line,  which  is  called  the  absciss.  The  absciss  and  ordinate  together  are  called  the  co- 
ordinates of  the  point. 

ORDNANCE.  Cannon,  Great  Guns,  Artillery.  The  size  of  field  guns  as  established  in  1827  in 
the  French  service,  are  8 and  12  pounders,  18  calibres  long,  and  weight  of  metal  150  times  that  of  the 
shot.  The  English  field  artillery  is  almost  entirely  9 pounders,  17  calibres  long,  and  weight  of  metal  168 
times  that  of  the  shot.  The  Prussian  service  use  6 and  12  pounders,  18  calibres  long,  and  weight  of 
metal  145  times  that  of  the  shot.  The  common  charge  is  4 of  the  weight  of  the  ball. 

For  battery  and  siege  service,  as  also  in  the  navy,  much  heavier  ordnance  is  used;  from  24  up  to  68 
pounders.  The  Dahlgreen  guns  recently  introduced  into  our  navy  are  very  short  guns,  in  shape  like  a 
bottle  nine-pin,  of  very  large  calibre,  from  9 to  11  inches.  The  English  32  pounder  is  9 feet  long,  and 
weighs*50  cwt. ; the  68  pounder  is  10  feet  10  inches  long,  and  weighs  112  cwt.  The  Paixhan  gun  is  in- 
tended for  the  discharge  of  hollow  shot  or  shell : it  is  chambered ; that  is,  there  is  a chamber,  for  the  recep- 
tion of  the  charge,  of  less  calibre  than  the  bore  of  the  piece.  Howitzers  are  short  pieces,  intended  to  throw 
shell  at  an  elevation  of  from  10°  to  30°,  and  are  fixed  on  carriages.  Mortars  are  still  shorter  pieces  fixed 
to  blocks,  intended  to  throw  shell  at  an  elevation  exceeding  20°,  and  sometimes  even  to  60“ ; they  are 
both  chambered  ordnance.  Howitzers  seldom  exceed  8 inches  in  calibre ; Mortars  are  bored  up  to  13, 
15,  or  even  more  inches  in  diameter.  See  Guns  and  Gunpowder. 

ORTHOCHRONOGRAPH.  This  instrument  has  for  its  object  the  ascertaining  of  correct  time. 
Its  property  is  derived  from  the  intersection  of  a curvilinear  line  at  two  points  by  the  circular  transit 
of  a solar  ray.  The  instrument  consists  of  two  horizontal  circular  plates  parallel  to  each  other.  The 
upper  one  a,  has  an  aperture  for  the  passage  of  a solar  ray ; the  lower  one  b,  has  three  pair  of  semi- 
circular lines,  for  the  purpose  of  making  observations.  The  lower  plate  b,  is  supported  by  a pillar  c, 
resting  on  a tripod,  furnished  with  three  adjusting  screws  d ef.  The  upper  plate  a is  raised  or  lowered 
by  means  of  a rack  g,  working  out  of  the  pillar  c,  by  means  of  a pinion  and  friction  rollers,  acted  upon 
by  the  milled  head  h. 

For  taking  an  observation,  place  the  instrument  upon  any  firm  support,  with  the  letters  N and  S as 
nearly  north  and  south  as  may  be ; but  rigid  accuracy  in  this  respect  is  by  no  means  essential.  By 
means  of  a spirit-level  and  the  adjusting  screws  d e f.  bring  the  plate  b into  a horizontal  position ; then 
raise  or  lower  the  plate  a until  the  sun’s  ray  is  in  contact  with  the  line  on  which  it  is  intended  to  make 


452 


PACKING. 


the  observation,  as  at  A in  the  diagram,  fig.  2986,  or  until  the  ray  appears  within  the  double  line  a» 
at  A,  fig.  2987.  In  either  case,  note  the  hour,  minute,  and  second,  when  the  ray  is  at  A ; leaving  the  in- 
strument undisturbed,  the  sun’s  ray  will  traverse  the  plate  in  the  direction  of  the  arrow  until  it  arrives  at 
the  point  A',  when  the  time  is  again  to  be  accurately  noted.  Add  the  results  of  the  two  observation'’ 


together,  and  divide  by  2 ; the  difference  between  this  result  and  12  hours  will  show  the  error  of  the 
clock  as  compared  with  solar  time,  which  being  corrected  by  the  necessary  equations,  (of  which  very 
complete  tables  are  given  in  the  descriptive  pamphlet  which  accompanies  the  instrument,)  will  give 
either  mean  or  siderial  time,  as  may  be  desired. 

OSCILLATION,  CENTRE  OF.  The  centre  of  oscillation  is  that  point  in  a vibrating  body  into 
which,  if  the  whole  were  concentrated  and  attached  to  the  same  axis  of  motion,  it  would  then  vibrate 
in  the  same  time  the  body  does  in  its  natural  state.  The  centre  of  oscillation  is  situated  in  a right  line 
passing  through  the  centre  of  gravity,  and  perpendicular  to  the  axis  of  motion. 

OYSTER-OPENER,  Picaclt’s.  Amongst  the  extensive  col- 
lections of  the  products  of  industry,  agriculture,  and  manufac- 
tures of  1849,  exhibited  in  Paris,  is  a peculiar  mechanical  con- 
trivance for  opening  oysters,  which  we  have  engraved,  fig.  2988, 
to  show  how  judiciously  mechanical  talent  may  be  exercised  in 
the  improvement  of  articles  of  an  humble  class.  The  instrument, 
which  is  the  invention  of  M.  Picault,  consists  of  two  levers  bent 
semicircularly  at  one  end,  and  hinged  together.  In  the  curved 
portion  of  one  of  these  levers  is  a narrow  recess,  of  a size  suffi- 
cient to  receive  the  edge  of  an  oyster,  as  shown ; and  on  the  other 
lever,  exactly  opposite  to  this  recess,  is  fixed  an  oblique  knife, 
which,  on  drawing  the  two  straight  ends  or  handles  of  the  levers 
together,  enters  the  joint  of  the  shells,  and  divides  them  at  once. 

PACKING,  METALLIC.  Patented  by  Messrs.  Allen  & Noyes 
in  1849.  By  an  examination  of  the  accompanying  drawing,  its 
principle  will  be  easily  understood.  Fig.  2989  a is  the  cylinder 
cover,  b is  a matrix  of  cast-iron,  c c &c.,  a series  of  rings,  and  d 
a piston-rod.  Its  application  is  very  simple : the  bottom  of  the 
inside  of  the  stuffing-box,  instead  of  being  curved  in  the  usual 
way,  is  turned  square  with  the  rod  on  which  the  cast-iron  matrix 
is  fitted  and  ground  on  steam-tight ; the  diameter  of  the  lower 
part  of  the  stuffing-box  and  the  inside  of  the  gland  is  made  some 
what  larger  than  the  rod ; and  the  stuffing-box  the  same  amount 
larger  than  the  outside  of  the  matrix ; the  rings  are  made  of  a com- 
position softer  than  Babbitt’s  metal,  and  are  cast  in  two  pieces,  as 
shown  in  fig.  2990.  It  will  be  observed,  the  upper  ring  in  which  the 
gland  screws  enters  the  matrix  about  an  eighth  of  an  inch,  and  the 
top  is  left  the  same  diameter  as  the  top  of  the  matrix  on  the  inside. 

In  its  operation,  as  the  matrix  is  ground  on  the  cylinder  cover, 
and  the  inside  of  the  rings  made  the  same  diameter  as  the  rod,  it  is 
kept  steam-tight;  the  rod  working  through  the  2990 
rings,  and  being  so  much  the  harder  metal,  keeps 
perfectly  smooth ; the  rings  are  kept  from  being  /'  f X A 

worn  by  any  irregularity  of  motion,  by  the  play  L ' \ 2 

allowed  in  the  stuffing-box  for  the  matrix.  In 
screwing  down  the  gland,  which  must  be  done 
lightly,  as  the  rings  are  conical  and  left  open,  they 
will  all  press  towards  the  rod,  and  in  time  the  up- 
per will  take  the  place  of  the  lower  ring.  In  a 
stuffing-box  of  any  kind,  the  great  desideratum  is 
to  keep  it  tight,  taking  care  not  to  cause  the  packing  to  scratch  the  rod,  as  it  always  does  more  or  less 
in  using  hemp,  nor  to  create  an  unnecessary  amount  of  friction.  This  packing  effectually  accomplishes 
these,  and  gives  the  engineer  little  or  no  trouble. 


PAPER  MACHINES. 


453 


PAPER,  MANUFACTURE  OF.  Till  within  the  last  thirty  years,  the  linen  and  hempen  rags  from 
which  paper  was  made,  were  reduced  to  the  pasty  state  of  comminution  requisite  for  this  manufacture 
by  mashing  them  with  water,  and  setting  the  mixture  to  ferment  for  many  days  in  close  vessels,  where- 
by they  underwent,  in  reality,  a species  of  putrefaction.  It  is  easy  to  see  that  the  organic  structure  of 
the  fibres  would  be  thus  unnecessarily  altered,  nay,  frequently  destroyed.  The  next  method  employed 
was  to  beat  the  rags  into  a pulp  by  stamping-rods,  shod  with  iron,  working  in  strong  oak  mortars,  and 
moved  by  water-wheel  machinery.  So  rude  and  ineffective  was  the  apparatus,  that  forty  pairs  of  stamps 
were  required  to  operate  a night  and  a day,  in  preparing  one  hundred  weight  of  rags.  The  pulp  or 
paste  was  then  diffused  through  water,  and  made  into  paper  by  methods  similar  to  those  still  practised 
in  the  small  hand-mills. 

About  the  middle  of  the  last  century,  the  cylinder  or  engine  mode,  as  it  is  called,  of  comminuting  rags 
into  paper  pulp,  was  invented  in  Holland ; which  was  soon  afterwards  adopted  in  France,  and  at  a later 
period  in  England. 

The  first  step  in  the  paper  manufacture  is  the  sorting  of  the  rags  into  four  or  five  qualities.  At  fhe 
mill  they  are  sorted  again  more  carefully,  and  cut  into  shreds  by  women.  For  this  purpose  a table- 
frame  is  covered  at  top  with  wire-cloth,  containing  about  nine  meshes  to  the  square  inch.  To  this  frame 
a long  steel  blade  is  attached  in  a slanting  position,  against  whose  sharp  edge  the  rags  are  cut  into 
squares  or  fillets,  after  having  their  dust  thoroughly  shaken  out  through  the  wire-cloth.  Each  piece  of 
rag  is  thrown  into  a certain  compartment  of  a box,  according  to  its  fineness ; seven  or  eight  sorts  being 
distinguished. 

The  sorted  rags  are  next  dusted  in  a revolving  cylinder  surrounded  with  wire-cloth,  about  six  feet 
long,  and  four  feet  in  diameter,  having  spokes  about  20  inches  long  attached  at  right  angles  to  its  axis. 
These  prevent  the  rags  from  being  carried  round  with  the  case,  and  beat  them  during  its  rotation ; so 
that  in  half  an  hour,  being  pretty  clean,  they  are  taken  out  by  the  side  door  of  the  cylinder,  and  trans- 
ferred to  the  engine,  to  be  first  washed  and  next  reduced  into  a pulp.  For  fine  paper,  they  should  be 
previously  boiled  for  some  time  in  a caustic  ley,  to  cleanse  and  separate  their  filaments. 

Wrigley’s  rag-machine  is  shown  in  Figs.  2996,  2997,  2998,  and  2999.  Fig.  2996  is  a side  elevation; 
Fig.  2997  a transverse  section,  taken  lengthwise  through  nearly  its  middle ; Fig.  2998  a plan  view  of 


2996. 


the  apparatus  detached  upon  a larger  scale ; and  Fig.  2999  is  an  elevation.  The  vessel  in  which  the 
rags  are  placed  is  shown  at  a a,  and  in  about  the  centre  of  this  vessel  the  beating  or  triturating  roll  b b 
is  placed ; it  is  surrounded  with  the  blades  or  roll-bars  c c,  Fig.  2997.  The  roll  is  mounted  upon  a shaft 
d d,  one  end  of  which  is  placed  in  a pedestal  or  bearing  on  the  further  side  of  the  chamber  a , and  the 
other  in  a bearing  upon  the  arm  or  level  e e*.  Fig.  2996,  which  is  supported  by  its  fulcrum,  at  the  end 
e*,  in  one  of  the  standards//,  and  at  the  other  end  by  a pin  fixed  in  the  connecting-rod  gg.  At  the 


2997. 


upper  end  of  this  connecting-rod  there  is  a cross-piece  or  head  h,  having  turned  pivots  at  each  end,  upon 
which  are  placed  small  rollers  ii,  resting  upon  a horizontal  cam  k k,  which  is  made  to  revolve.  This 
cam  k k,  by  means  of  its  geering,  causes  the  roll  b first  of  all  to  wash  the  rags  a short  time,  then  to  be 
lowered  at  whatever  rate  is  desired  for  breaking  the  fibres;  to  be  maintained  at  the  lowest  point  for 


454 


PAPER  MACHINES. 


the  required  number  of  revolutions  for  beating;  and  to  be  raised  and  retained,  as  required,  for  the  final 
purpose  of  clearing  the  pulp.  The  upper  or  working  edge  of  this  cam  is  to  be  shaped  exactly  according 
to  the  action  required  by  the  engine-roll ; as,  for  instance,  suppose  the  previous  operation  of  washing  to 
be  completed,  and  the  time  required  for  the  operation  of  the  rag  machine  to  be  three  hours,  one  of  which 
is  required  for  lowering  the  roll,  that,  or  the  first  division  of  the  working  surface  of  the  cam  k k,  must 
be  so  sloped  or  inclined  that,  according  to  the  speed  at  which  it  is  driven,  the  rollers  upon  the  cross- 
head shall  be  exactly  that  portion  of  the  time  descending  the  incline  upon  the  cam,  and  consequently 
lowering  the  roll  upon  the  plates  n.  Fig.  2997  ; and  if  the  second  hour  shall  be  required  for  the  roll  to 
beat  up  the  rags,  the  roll  revolving  all  the  time  in  contact  with  the  pdates,  the  second  division  of  the 
cam  k k must  be  so  shaped  (that  is,  made  level)  that  the  roll  shall  be  allowed  to  remain,  during  that 
period,  at  its  lowest  point ; and  if  the  third  portion  of  tire  time,  or  an  hour,  be  required  for  raising  the 
* " again,  either  gradually  or  interruptedly,  then  the  third  division  of  the  cam  k must  be  suitably  shaped 


2999.  2998. 


or  inclined,  so  as  to  cause  the  cross-head  to  lift  the  roll  during  such  interval  or  space  of  time ; the  par- 
ticular shape  of  the  inclined  portions  of  the  cam  depending  on  the  manner  in  which  the  manufacturer 
may  wish  the  roll  to  approach  to  or  recede  from  the  bottom  plates  during  its  descent  and  ascent  respect- 

•'•ely. 

Its  mode  of  connection  and  operation  in  the  rag-engine  is  as  follows  : supposing  that  the  rags  intended 
to  be  beaten  up  are  placed  in  the  vessel  a,  Fig.  2997,  and  motion  is  communicated  from  a steam-engine 
or  other  power,  to  the  further  end  of  the  shaft  d,  the  roll  b will  thus  be  caused  to  revolve,  and  the  rags 
washed,  broken,  and  beaten  up,  as  they  proceed  from  the  front  weir  m,  over  the  bottom  plates  n,  and 
again  wund  by  the  back  weir  n.  There  is  a small  pulley  p,  upon  the  near  end  of  the  shaft  d,  round 
’.vhick  a band  q passes,  ahd  also  round  another  pulley  r,  upon  the  cross-shaft  s;  upon  this  shaft  is  a 
worm  t , geering  into  a worm-wheel  u,  fixed  upon  another  shaft  v,  below  ; upon  the  reverse  end  of  which 
is  a pinion  w,  geering  into  a spur-wheel  x,  upon  the  end  of  a shaft  y ; and  upon  the  centre  of  this  shaft 
y there  is  another  worm  z,  geering  into  a horizontal  worm-wheel  1,  upon  which  the  cam  kk  is  fixed. 
Thus  it  will  be  seen  that  the  requisite  slow  motion  is  communicated  to  the  cam,  which  may  be  made  to 
perform  half  a revolution  in  three  hours  ; or  it  will  be  evident,  that  half  a revolution  of  the  cam  k k 
may  be  performed  in  any  other  time,  according-  to  the  calculation  of  the  geering  employed.  The  shaft 
may  also  be  driven  by  hand,  so  as  to  give  the  required  motion  to  the  cam.  Supposing,  now,  at  the  be- 
ginning of  the  operation,  the  cross-head  bearing  the  lever  and  roll  to  be  at  the  highest  point  upon  the 
cam  k k,  as  its  revolution  commences,  the  roll  will  revolve  for  a short  time  on  the  level  surface  of  the 
cam,  and  will  then  be  lowered  until  the  cam  k k has  arrived  at  that  point  which  governs  the  time  that 
the  roll  remains  at  the  lowest  point,  for  the  purpose  of  beating  the  rags  into  pulp,  and  as  the  cam  k k 
continues  to  revolve,  and  thus  brings  the  opposite  slope  upon  the  third  portion  of  its  working  surface 
into  action  upon  the  cross-head,  the  roll  will  be  raised  in  order  to  clear  the  pulp  from  knots  and  other 
imperfections,  and  thus  complete  the  operation  of  the  engine.  In  order  to  raise  the  cross-head  and  roll 
to  the  height  from  which  it  descended  without  loss  of  time,  or  to  lift  the  cross-head  entirely  from  off  the 
cam  when  requisite,  a lever  2,  or  other  suitable  contrivance  may  be  attached  to  the  apparatus,  also  a 
shaft  may  be  passed  across  the  rag-engine,  and  both  ends  of  the  roll  may  be  raised  instead  of  one  only, 
as  above  described. 

In  the  paper  machine  of  Messrs  Bryan  Donkin  & Co.  in  Bermondsey,  on  Fourdrinier’s  principle,  each 
machine  is  capable  of  making,  under  the  impulsion  of  any  prime  mover,  all  unwatched  by  a human  eye 
and  unguided  by  a human  hand,  from  20  to  50  feet  in  length,  by  5 feet  broad,  of  most  equable  paper  in 
one  minute.  Of  paper  of  average  thickness  it  turns  off  30  feet. 

Fig.  3000,  30  002  is  an  upright  longitudinal  section,  representing  the  machine  in  its  most  complete  state, 
including  the  drying  steam-cylinders,  and  the  compound  channelled  rollers  of  Mr.  Wilkes,  subsequently 
to  be  described  in  detail.  The  longer  figure  shows  it  all  in  train,  when  the  paper  is  to  be  wound  up 
wet  upon  the  reels  E E,  which,  being  movable  round  the  centre  l of  a swing-bar,  are  presented  empty, 
time  about,  to  receive  the  tender  web.  The  shorter  figure  contains  the  steam  or  drying  cylinders,  the 
points  O O of  whose  frame  replace  at  the  points  P P the  wet-reel  frame  F F P. 

A is  the  vat,  or  receiver  of  pulp  from  the  stuff-chest.  B is  the  knot-strainer  of  Ibotson,  to  clear  the 
pulp  before  passing  on  to  the  wire.  G is  the  hog,  or  agitator  in  the  vat.  The  arrows  show  the  course 
of  the  currents  of  the  pulp  in  the  vat.  I is  the  apron,  or  receiver  of  the  water  and  pulp  which  escape 
through  the  endless  wire,  and  which  are  returned  by  a scoop-wheel  into  the  vat.  b is  the  copper  lip  ol 
the  vat,  over  which  the  pulp  flows  to  the  endless  wire,  on  a leathern  apron  extending  from  this  lip  to 
about  nine  inches  over  the  wire,  to  support  the  pulp  and  prevent  its  escaping,  cc  are  the  bars  which 
bear  up  the  small  tube  rollers  that  support  the  wire,  dd  are  ruler-bars  to  support  the  copper  rollers 


PAPER  MACHINES. 


455 


over  which  the  wire  revolves.  K is  the  breast-roller,  round  which  the  endless  wire  turns.  N is  the  point 
where  the  shaking  motion  is  given  to  the  machine.  M is  the  guide-roller,  having  its  pivots  movable 
laterally  to  adjust  the  wire  and  keep  it  parallel.  L is  the  pulp-roller,  or  “ dandy,”  to  press  out  water, 
and  to  set  the  paper,  r is  the  place  of  the  second,  when  it  is  used.  H is  the  first  or  wet  press,  or 
couching  rollers ; the  wire  leaves  the  paper  here,  which  latter  is  couched  upon  the  endless  felt  p ; and 
the  endless  wire  o returns,  passing  round  the  lower  couch-roller.  By  Mr.  Donkin’s  happy  invention  of 
placing  these  rollers  obliquely,  the  water  runs  freely  away,  which  it  did  not  do  when  their  axes  were  in 
a vertical  line,  ee  are  the  deckles,  which  form  the  edges  of  the  sheet  of  paper,  and  prevent  the  pulp 
passing  away  laterally.  They  regulate  the  width  of  the  endless  sheet,  ff  are  the  revolving  deckle- 
straps.  R is  the  deckle-guide,  or  driving-pulley,  g g are  tube-rollers,  over  which  the  wire  passes,  which 
do  not  partake  of  the  shaking  motion ; and  h h are  movable  rollers  for  stretching  the  wire,  or  brass  car- 
riages for  keeping  the  rollers  g g in  a proper  position. 

C is  the  second  press,  or  dry  press,  to  expel  the  water  in  a cold  state.  KK,  die.,  are  the  steam- 
cylinders  for  drying  the  endless  sheet,  i i are  rollers  to  convey  the  paper,  jj  are  rollers  to  conduct 
the  felt,  wliich  serves  to  support  the  paper,  and  prevent  it  wrinkling  or  becoming  cockled.  D D are 
the  hexagonal  expanding  reels  for  the  steam-dried  paper  web,  one  only  being  used  at  a time,  and 
made  to  suit  different  sizes  of  sheets ; l is  their  swing-fulcrum.  F F F F is  the  frame  of  the  machine. 

The  deckle-straps  are  worthy  of  particular  notice  in  this  beautiful  machine.  They  are  composed  of 
many  layers  of  cotton  tape,  each  one  inch  broad,  and  together  one-half  inch  thick,  cemented  with  caout- 
chouc, so  as  to  be  at  once  perfectly  flexible  and  water-tight. 

The  upper  end  of  each  of  the  two  carriages  of  the  roller  L is  of  a forked  shape,  and  the  pivots  of 
the  roller  are  made  to  turn  in  the  cleft  of  the  forked  carriages  in  such  a manner  that  the  roller  may 
be  prevented  from  having  any  lateral  motion,  while  it  possesses  a free  vibratory  motion  upwards  and 
downwards ; the  whole  weight  of  the  roller  L being  borne  by  the  endless  web  of  woven  wire. 

The  greatest  difficulty  formerly  experienced  in  the  paper  manufacture  upon  the  continuous  system 
of  Fourdrinier,  was  to  remove  the  moisture  from  the  pulp  and  condense  it  with  sufficient  rapidity,  so 
as  to  prevent  its  becoming  what  is  called  water-galled , and  to  permit  the  web  to  proceed  directly  to 
the  drying  cylinders.  Hitherto  no  invention  has  answered  so  well  in  practice  to  remove  this  difficulty 
as  the  channelled  and  perforated  pulp-rollers  or  dandies  of  Mr.  John  Wilks,  the  partner  of  Mr.  Donkin. 
Suppose  one  of  these  rollers  (see  L,  Fig.  8000,  and  MM,  Fig.  3005)  is  required  for  a machine  which  is 
to  make  paper  54  inches  wide,  it  must  be  about  60  inches  long,  so  that  its  extremities  (see  Figs..  3001 
and  3002 ) may  extend  over  or  beyond  each  edge  of  the  sheet  upon  which  it  is  laid.  Its  diameter  may 
be  7 inches.  About  8 grooves,  each  l-16th  of  an  inch  wide,  are  made  in  every  inch  of  the  tube;  and 
they  are  cut  to  half  the  thickness  of  the  copper,  with  a rectangularly  shaped  tool.  A succession  o? 
ribs  and  grooves  are  thus  formed  throughout  the  whole  length  of  the  tube.  A similar  succession  is 
then  made  across  the  former,  but  of  24  in  the  inch,  and  on  the  opposite  surface  of  the  metal,  which, 
by  a peculiar  mode  of  management,  had  been  prepared  for  that  purpose.  As  the  latter  grooves  are 
cut  as  deep  as  the  former,  those  on  the  inside  meet  those  on  the  outside,  crossing  each  other  at  right 
angles,  and  thereby  producing  so  many  square  holes;  leaving  a series  of  straight  copper  ribs  on  the  in- 
terior surface  of  the  said  tube,  traversed  by  another  series  of  ribs  coiled  round  them  on  the  outside, 
forming  a cylindrical  sieve  made  of  one  piece  of  metal.  The  rough  edges  of  all  the  ribs  must  be 
rounded  off  with  a smooth  file  into  a semicircular  form. 

Figs.  3002  and  3001,  A A are  portions  of  the  ribbed  copper  tube.  Fig.  3002  shows  the  exterior,  and 
Fig.  3001  the  interior  surface;  bb  and  bb  show  the  plain  part  at  each  of  the  ends,  where  it  is  made 
fast  to  the  brass  rings  by  rivets  or  screws.  C C are  the  rings  with  arms,  and  a centre-piece  in  each, 
for  fixing  the  iron  pivot  or  shaft  B ; one  such  pivot  is  fixed  by  riveting  it  in  each  of  the  centre-pieces 
of  the  rings,  as  shown  at  c,  Fig.  3001  ; so  that  both  the  said  pieces  shall  be  concentric  with  the  rings, 
and  have  one  common  axis  with  each  other  and  with  the  roller.  At  a a a groove  is  turned  in  each  of 
the  pivots,  for  the  purpose  of  suspending  a weight  by  a hook,  in  order  to  increase  the  pressure  upon 
the  paper,  whenever  it  may  be  found  necessary. 

Fig.  3003  is  an  end  view,  showing  the  copper  tube  and  its  internal  ribs  A A,  the  brass  rings  C C, 
arm  D,  centre-piece  E,  and  pivot  B.  Fig.  8004  is  a section  of  the  said  ring,  with  the  arms,  &c. 

The  roller  is  shown  at  L,  Fig.  3000,  as  lying  upon  the  surface  of  the  wire-web.  The  relative  position 
of  that  perforated  roller,  and  the  little  roller  b over  which  it  lies,  is  such  that  the  axis  of  L is  a little 
to  one  side  of  the  axis  of  b,  and  not  in  the  same  vertical  plane,  the  latter  being  about  an  inch  nearer 
the  vat  end.  Hence,  whenever  the  wire-web  is  set  in  progressive  motion,  it  will  cause  the  roller  L to 
revolve  upon  its  surface ; and  as  the  paper  is  progressively  made,  it  will  pass  onwards  with  the  web 
under  the  surface  of  the  roller.  Thus  the  pulpy  layer  of  paper  is  condensed  by  compression  under  the 
ribbed  roller ; while  it  transmits  its  moisture  through  the  perforations,  it  becomes  sufficiently  compact 
to  endure  the  action  of  the  wet-press  rollers  H H,  and  also  acquires  the  appearance  of  parallel  lines, 
as  if  made  by  hand  in  a laid  mould. 

Mr.  Wilks  occasionally  employs  a second  perforated  roller  in  the  same  machine,  which  is  then  placed 
at  the  dotted  lines  i i i. 

The  patentee  has  described  in  the  same  specification  a most  ingenious  modification  of  the  said  roller, 
by  which  he  can  exhaust  the  air  from  a hollowed  portion  of  its  periphery,  and  cause  the  paper  in  its 
passage  over  the  roller  to  undergo  the  sucking  operation  of  the  partial  void,  so  as  to  be  remarkably 
condensed  ; but  he  has  not  been  called  upon  to  apply  this  second  invention,  in  consequence  of  the  per- 
fect success  which  he  has  experienced  in  the  working  of  the  first. 

The  following  is  a more  detailed  illustration  of  Mr.  Wilks’s  improved  roller : 

Fig.  3005  represents  two  parts  of  his  double-cased  exhausting  cylinder.  This  consists  of  two  copper 
tubes,  one  nicely  lining  the  other ; the  inner  being  punched  full  of  round  holes,  as  at  K K,  where  that 
tube  is  shown  uncovered  ; a portion  of  the  inner  surface  of  the  same  tube  is  shown  at  L L.  In  this  figure 
also,  two  portions  of  the  outer  tube  are  shown  at  M M and  N N,  tire  former  being  an  external,  and  the 


456 


PAPER  MACHINES. 


PAPER  MACHINES. 


457 


latter  an  internal  view.  Here  we  see  that  the  external  tube  is  the  ribbed  perforated  one  already  de- 
scribed ; the  holes  in  the  inner  tube  being  made  in  rows  to  correspond  with  the  grooves  in  the  outer. 
The  holes  are  so  distributed  that  every  hole  in  one  row  shall  be  opposite  to  the  middle  of  the  space  left 
between  two  holes  in  the  next  row,  as  will  appear  from  inspection  of  the  figure.  The  diameter  of  cacti 
of  the  punched  holes  somewhat  exceeds  the  width  of  each  rib  in  the  inside  of  the  outer  cylinder,  and 
every  inside  groove  of  this  tube  coincides  with  a row  of  holes  in  the  former,  which  construction  permits 
the  free  transudation  or  percolation  of  the  water  out  of  the  pulp.  At  each  end  of  this  double-case  cyl- 
inder a part  is  left  at  N N plain  without,  and  grooved  merely  in  the  inside  of  the  outer  tube.  The 
smooth  surface  allows  the  brass  ends  to  be  securely  fixed ; the  outer  edge  of  the  brass  ring  fits  tight 
into  the  inside  of  the  end  of  the  cylinders. 

On  the  inside  of  each  of  these  rings  there  are  four  pieces  which  project  towards  the  centre  or  axis  of 
the  cylinder,  two  of  which  pieces  are  shown  at  a a,  Fig.  3005,  in  section,  b b is  a brass  ring  with  four 
arms  cccc,  and  a boss  or  centre-piece  dd.  The  outer  edge  of  the  last-mentioned  ring  is  also  turned 
cylindrical,  and  of  such  a diameter  as  to  fit  the  interior  of  the  former  ring  oo.  The  two  rings  are 
securely  held  together  by  four  screws,  e e is  the  hollow  iron  axle  or  shaft  upon  which  the  cylinder  re- 
volves. Its  outside  is  made  truly  cylindrical,  so  as  to  fit  the  circular  holes  in  the  bosses  d d of  the  rings 
and  arms  at  each  end  of  the  cylinder.  Hence,  if  the  hollow  shaft  be  so  fixed  that  it  will  not  turn,  the 
perforated  cylinder  is  capable  of  having  a rotatory  motion  given  to  it  round  that  shaft.  This  motion  is 
had  recourse  to  when  the  vacuum  apparatus  is  employed.  But  otherwise  the  cylinder  is  made  fast  to 
the  hollow  axle  by  means  of  two  screw-clamps.  To  one  end  of  the  cylinder,  as  at  p,  a toothed  wheel  is 
attached  for  communicating  a rotatory  motion  to  it,  so  that  its  surface  motion  shall  be  the  same  as  that 
of  the  paper  web;  otherwise  a rubbing  motion  might  ensue,  which  would  wear  and  injure  both. 

The  paper  stuff  or  pulp  is  allowed  to  flow  from  the  vat  A,  Fig.  3000,  on  to  the  surface  of  the  endless 
wire-web,  as  this  is  moving  along.  The  fines  o o,  Fig.  3000,  show  the  course  of  the  motion  of  the  web, 
which  operates  as  a sieve,  separating  to  a certain  degree  the  water  from  the  pulp,  yet  leaving  the  latter 
in  a wet  state  till  it  arrives  at  the  first  pair  of  pressing-rollers  II  H,  between  which  the  web  with  its 
sheet  of  paper  is  squeezed.  Thick  paper,  in  passing  through  these  rollers,  was  formerly  often  injured 
by  becoming  water-galled,  from  the  greater  retention  of  water  in  certain  places  than  in  others.  But 
Messrs.  Donkin’s  cylinder,  as  above  described,  has  facilitated  vastly  the  discharge  of  the  water,  and 
enabled  the  manufacturer  to  turn  off  a perfectly  uniform  smooth  paper. 

In  Fig.  3000,  immediately  below  the  perforated  cylinder,  there  is  a wooden  water-trough.  Along  one 
side  of  the  trough  a copper  pipe  is  laid,  of  the  same  length  as  the  cylinder,  and  parallel  to  it ; the  dis- 
tance between  them  being  about  one-fourth  of  an  inch.  The  side  of  the  pipe  facing  the  cylinder  is  per- 
forated with  a fine  of  small  holes,  which  transmit  a great  many  jets  of  water  against  the  surface  of  the 
cylinder,  in  order  to  wash  it  and  keep  it  clean  during  the  whole  continuance  of  the  process. 

The  principle  adopted  by  John  Dickinson  for  making  paper,  is  different  from  that  of  Fourdrinier.  It 
consists  in  causing  a polished  hollow  brass  cylinder,  perforated  with  holes  or  slits,  and  covered  with  wire- 
cloth,  to  revolve  over  and  just  in  contact  with  the  prepared  pulp ; so  that  by  connecting  the  cylinder 
with  a vessel  exhausted  of  its  air,  the  film  of  pulp,  which  adheres  to  the  cylinder  during  its  rotation, 
becomes  gently  pressed,  whereby  the  paper  is  supposed  to  be  rendered  drier,  and  of  more  uniform 
thickness,  than  upon  the  horizontal  hand-moulds  or  travelling  wire-cloth  of  Fourdrinier.  When  sub- 
jected merely  to  agitation,  the  water  is  sucked  inwards  through  the  cylindric  cage,  leaving  the  textile 
filaments  so  completely  interwoven  as,  if  felted  among  each  other,  that  they  will  not  separate  without 
breaking,  and  when  dry  they  will  form  a sheet  of  paper  of  a strength  and  quality  relative  to  the  nature 
and  preparation  of  the  pulp.  The  roll  of  paper  thus  formed  upon  the  hollow  cylinder  is  turned  off  con- 
tinuously upon  a second  solid  one  covered  with  felt,  upon  which  it  is  condensed  by  the  pressure  of  a 
third  revolving  cylinder,  and  is  thence  delivered  to  the  drying  rollers. 

Mr.  Ibotson,  of  Poyle,  paper  manufacturer,  obtained  a patent,  see  B,  Fig.  3000,  which  has  proved  very 
successful  for  a peculiar  construction  of  a sieve  or  strainer.  Instead  of  wire  meshes,  he  uses  a series  of 
bars  of  guii-metal,  laid  in  the  bottom  of  a box  very  closely  together,  so  that  the  upper  surfaces  or  the 
flat  sides  may  be  in  the  same  plane,  the  edge  of  each  bar  being  parallel  with  its  neighbor,  leaving  par- 
allel slits  between  them  of  from  about  l-JOth  to  l-100th  of  an  inch  in  width,  according  to  the  fineness 
or  coarseness  of  the  paper  stuff  to  be  strained.  As  this  stuff  is  known  to  consist  of  an  assemblage  of 
very  fine  flexible  fibres  of  hemp,  flax,  cotton,  &c.,  mixed  with  water,  and  as,  even  in  the  pulp  of  which 
the  best  paper  is  made,  the  length  of  the  said  fibres  considerably  exceeds  the  diameter  of  the  meshes  of 
which  common  strainers  are  formed,  consequently  the  longest  and  most  useful  fibres  were  formerly  lost 
to  the  paper  manufacturer.  Mr.  Ibotson’s  improved  sieve  is  employed  to  strain  the  paper  stuff  pre- 
viously to  its  being  used  in  the  machine  above  described,  (see  its  place  at  B in  the  vat.)  When  the 
strainer  is  at  work,  a quick  vertical  and  lateral  jogging  motion  is  given  to  it,  by  machinery  similar  to 
the  jogging  screens  of  corn-mills. 

Since  the  lateral  shaking  motion  of  the  wire-web  in  the  Fourdrinier  machine,  as  originally  made,  was 
injurious  to  the  fabric  of  the  paper,  by  bringing  its  fibres  more  closely  together  breadthwise  than  length- 
wise, thus  tending  to  produce  long  ribs  or  thick  streaks  in  its  substance,  it  was  proposed  to  give  a rapid 
up-and-down  movement  to  the  travelling  web  of  pulp;  and  this  has  been  introduced  into  Mr.  Donkin's 
machines. 

Mr.  Dickinson  obtained  a patent  for  a method  of  uniting  face  to  face  two  sheets  of  pulp  by  means  of 
machinery,  in  order  to  produce  paper  of  extraordinary  thickness.  Two  vats  are  to  be  supplied  with 
paper  stuff  as  usual ; in  which  two  hollow  barrels  or  drums  are  made  to  revolve  upon  axles  driven  by 
any  first  mover ; an  endless  felt  is  conducted  by  guide-rollers,  and  brought  into  contact  with  the  drums  ; 
the  first  drum  gives  off  the  sheet  of  paper  pulp  from  its  periphery  to  the  felt,  which,  passing  over  a 
pressing-roller  is  conducted  by  the  felt  to  that  part  of  a second  drum  which  is  in  contact  with  another 
pressing-roller.  A similar  sheet  of  paper  pulp  is  now  given  off  from  the  second  drum,  and  it  is  brought 
into  contact  with  the  former  by  the  pressure  of  its  own  roller.  The  two  sheets  of  paper  pulp  thus 


458 


PAPER  MACHINES. 


united  are  carried  forwards  by  the  felt  over  a guide-roller,  and  onwards  to  a pair  of  pressing-rollers 
where,  by  contact,  the  moist  surface  of  the  pulp  are  made  to  adhere,  and  to  constitute  one  double  thick 
sheet  of  paper,  which,  after  passing  over  the  surfaces  of  hollow  drums,  heated  by  steam,  becomes  dry 
and  compact.  The  rotatory  movements  of  the  two  pulp-lifting  drums  must  obviously  be  simultaneous, 
but  that  of  the  pressing-rollers  should  be  a little  faster,  because  the  sheets  extend  by  the  pressure,  and 
they  should  be  drawn  forwards  as  fast  as  they  are  delivered,  otherwise  creases  would  be  formed.  Upon 
this  invention  is  founded  Mr.  Dickinson’s  ingenious  method  of  making  safety-paper  for  post-office  stamps, 
by  introducing  silk  fibres,  <fcc.,  between  the  two  laminae. 

The  following  contrivance  of  the  same  manufacturer  is  a peculiarly  elegant  mechanical  arrangement, 
and  consists  in  causing  the  diluted  paper  pulp  to  pass  between  longitudinal  apertures,  about  the  hun- 
dred-and-fifteenth  part  of  an  inch  wide,  upon  the  surface  of  a revolving  cylinder. 

The  pulp  being  dilated  to  a consistency  suitable  for  the  paper  machine,  is  delivered  into  a vat,  of 
which  the  level  is  regulated  by  a waste-pipe,  so  as  to  keep  it  nearly  full.  From  tiiis  vat  there  is  no 
other  outlet  for. the  pulp  except  through  the  wire-work  periphery  of  the  revolving  cylinder  and  thence 
out  of  each  of  its  ends  into  troughs  placed  alongside,  from  which  it  is  conducted  to  the  machine  destined 
to  convert  it  into  a paper  web. 

The  revolving  cylinder  is  constructed  somewhat  like  a squirrel  cage,  of  circular  rods,  or  an  endless 
spiral  wire,  strengthened  by  transverse  metallic  bars,  and  so  formed  that  the  spaces  between  the  rings 
are  sufficient  to  allow  the  slender  fibres  of  the  pulp  to  pass  through,  but  are  narrow  enough  to  intercept 
the  knots  and  other  coarse  impurities,  which  must  of  course  remain  and  accumulate  in  the  vat.  The 
spaces  between  the  wires  of  the  squirrel  cage  may  vary  from  the  interval  above  stated,  which  is  in- 
tended for  tlie  finest  paper,  to  double  the  distance  for  the  coarser  kinds. 

It  has  been  stated  that  the  pulp  enters  the  revolving  cylinders  solely  through  the  intervals  of  the 
wires  in  the  circumference  of  the  cylinder ; these  wires  or  rods  are  about  three-eighths  of  an  inch  broad 
without,  and  two-eighths  within,  so  that  the  circular  slits  diverge  internally.  The  rods  are  one-quarter 
of  an  inch  thick,  and  are  riveted  to  the  transverse  bars  in  each  quadrant  of  their  involution,  as  well  as 
at  their  ends  to  the  necks  of  the  cylinder. 

During  the  rotation  of  the  cylinder  its  interstices  would  soon  get  clogged  with  the  pulp,  were  not  a 
contrivance  introduced  for  creating  a continual  vertical  agitation  in  the  inside  of  the  cylinder.  This  is 
effected  by  the  up-and-down  motion  of  an  interior  agitator  or  plunger,  nearly  long  enough  to  reach  from 
the  one  end  of  the  cylinder  to  the  other,  made  of  stout  copper,  and  hollow,  but  water-tight.  A metal 
bar  passes  through  it,  to  whose  projecting  arm  at  each  end  a strong  link  is  fixed ; by  these  two  links  it 
is  hung  to  two  levers,  in  such  a way  that  when  the  levers  move  up  and  down  they  raise  and  depress 
the  agitator,  but  they  can  never  make  it  strike  the  sides  of  the  cylinder.  Being  heavier  than  its  own 
talk  of  water,  the  agitator,  after  being  lifted  by  the  levers,  sinks  suddenly  afterwards  by  its  weight 
alone. 

The  agitator’s  range  of  up-and-down  movement  should  be  about  one  inch  and  a quarter,  and  the 
number  of  its  vibrations  about  80  or  100  per  minute ; the  flow  of  the  pulp  through  the  apertures  is  sud- 
denly checked  in  its  descent  and  promoted  in  its  ascent,  with  the  effect  of  counteracting  obstructions 
between  the  ribs  of  the  cylinder. 

The  sieve-cylinder  has  a toothed  wheel  fixed  upon  the  tubular  part  of  one  of  its  ends,  which  works 
between  two  metal  flanches  made  fast  to  the  wooden  side  of  the  vat,  for  the  pjurpose  of  keeping  the 
pulp  away  from  the  wheel ; and  it  is  made  to  revolve  by  a pinion  fixed  on  a spindle,  which,  going  across 
the  vat,  is  secured  by  two  plummer-blocks  on  the  outside  of  the  troughs,  and  has  a rotatory  motion  given 
to  it  by  an  outside  rigger  or  pulley,  by  means  of  a strap  from  the  driving-shaft,  at  the  rate  of  40  or 
50  revolutions  per  minute.  This  spindle  has  also  two  double  eccentrics  fixed  upon  it,  immediately 
under  the  levers,  so  that  in  every  revolution  it  lifts  those  levers  twice,  and  at  the  same  time  lifts  the 
agitator. 

The  diameter  of  the  sieve -cylinder  is  not  very  material,  but  14  inches  have  been  found  a convenient 
size ; its  length  must  be  regulated  according  to  the  magnitude  of  the  machine  which  it  is  destined  to 
supply  with  pulp. 

Metal  flanches  are  firmly  fixed  to  the  sides  of  the  vat,  with  a water-tight  joint,  and  form  the  bearings 
in  which  the  cylinder  works. 

Mr.  Dickinson  obtained  a patent  in  1840  for  a new  mode  of  sizing  paper  continuously,  in  an  air-tight 
vessel,  (partly  exhausted  of  air,)  by  unwinding  a scroll  of  dried  paper  from  a reel,  and  conducting  it 
through  heated  size ; then,  after  pressing  out  the  superfluous  size,  winding  the  paper  on  to  another  reeL 

A longitudinal  section  of  the  apparatus  employed  for  this  purpose  is  represented  in  Fig.  3006,  where 
a is  the  air-tight  vessel ; b,  the  reel  upon 
which  the  paper  to  be  sized  is  wound ; 
whence  it  proceeds  beneath  the  guide- 
roller  c,  and  through  the  warm  size  to 
another  guide-roller  d.  It  thence  as- 
cends between  the  press-rolls  ef,  (by 
whose  revolution  the  paper  is  drawn 
from  the  reel  b,)  and  is  wround  upon  the 
reel  ff.  A float  h is  suspended  from  the 
cross-bar  i of  the  vessel  a,  for  the  pur- 
pose of  diminishing  the  surface  of  size 
exposed  to  evaporation ; and  beneath 
the  bottom  of  the  vessel  is  an  inclosed 
space  j,  into  which  steam  or  hot  water 
is  introduced  for  maintaining  the  tem- 
Derature  of  the  size. 


PAPER  MACHINES. 


459 


PAPER  MACHINES,  regulation  of.  It  is  found  in  practice  to  be  difficult  to  regulate  the  motion  of 
the  Foudrinier,  and  other  machines,  in  common  use,  for  the  manufacture  of  endless  paper.  When  the 
flow  of  pulp  upon  any  machine  is  uniform,  an  acceleration  of  its  motion  will  make  the  paper  thin, 
whilst  a retardation  will  make  it  thick.  Hence  it  is  of  the  utmost  importance,  in  order  to  make  paper 
of  even  weight  and  thickness,  that  when  the  flow  of  the  pulp  is  uniform,  the  machine  shall  move  uni- 
formly at  the  same  speed.  Rut  if.  by  any  contrivance,  the  flow  of  the  pulp  could  be  augmented,  or 
checked,  just  in  the  same  proportion  as  the  machine  moves  slower  or  faster,  it  is  evident  that  the 
necessary  relation  between  its  speed,  and  the  quantity  of  pulp  thrown  on,  might  be  effected  and  main- 
tained. Consequently,  two  modes  of  obtaining  the  requisite  uniformity  in  the  thickness  and  weight  of 
the  endless  sheet  of  paper  suggest  themselves. 

I.  To  regulate  the  speed  of  the  motor  driving  the  machine. 

II.  To  regulate  the  flow  of  pulp  upon  the  machine. 

The  attention  of  constructors  has  usually  been  directed  chiefly  to  the  first  method;  and  hence  we 
find  the  machine-wheels  of  paper-mills  are  very  frequently  tub-wheels,  wasting  a large  amount  of  water, 
but  nevertheless  selected  and  used  on  account  of  the  regularity  of  their  motion.  With  this  object  also  it 
is  almost  invariably  the  practice  here  to  employ  an  independent  wheel  to  drive  the  paper  machine  alone. 

Some  attempts  have  recently  been  made  in  this  country  to  regulate  endless  paper  machines  by  the 
second  method,  and  accordingly  “ pulp  regulators ” have  been  applied  with  considerable  success  in 
several  important  mills. 

It  being,  in  fact,  a desideratum  to  procure  some  unobjectionable  means  of  effecting  the  regulation  re- 
ferred to,  we  have  translated  from  J.  B.  Viollet’s  Journal  des  Usines  an  account  of  a mechanical  con- 
trivance devised  in  France  for  tliis  object. 

Regulator  for  feeding  machines  making  endless  paper,  by  Messrs.  Sandford  and  Varuall,  mechanical 
engineers  of  Paris. — Whatever  care  may  be  taken  to  render  uniform  the  speed  of  the  motors  which 
drive  endless  paper  machines,  and  notwithstanding  we  usually  establish  for  each  of  these  machines  a 
separate  water-wheel,  constructed  of  iron,  in  the  best  provided  works,  it  has  long  been  impossible  to 
obtain  a regularity  of  motion,  and  a harmony  between  the  movement  of  the  endless  cloth  and  the  feed- 
ing on  of  the  pulp,  so  that  the  paper  may  possess  uniformly  the  same  thickness. 

* From  this  resulted  a serious  imperfection,  consisting  of  a marked  inequality  between  the  different 
parts  of  the  long  band  of  paper,  and  consequently,  between  the  sheets  into  which  it  is  cut.  We  con- 
ceived that  this  inequality  was  not  only  a fault,  but  also  that  it  exposed  the  manufacturers  to  disputes 
not  arising  from  any  fault  on  their  part. 

In  fact,  to  cause  the  velocity  of  the  machines,  and  consequently,  the  strength  of  the  paper  to  vary,  it 
was  enough  that  the  resistances  opposed  by  the  materials  were  not  constant,  or  that  the  stream  of  water 
happened  to  be  disturbed. 

It  is  to  avoid  these  difficulties  and  inconveniences  that  Sandford  and  Varrall  have  invented  the 
apparatus  represented  in  Figs.  3007,  3008,  3009,  3010,  3011,  and  3012. 


3007. 


O 


This  apparatus  consists  principally  of  a wheel  R,  provided  with  a.  certain  number  ot  scoops  e,  which 
take  up  the  diluted  pulp,  elevate  it,  and  pour  it  into  a receptacle,  from  which  the  filter  c conducts  it 
into  the  vat  for  working  the  paper  machine.  The  motion  of  the  wheel  R being  connected  both  with 
that  of  the  water-wheel,  and  of  the  endless  cloth,  it  is  easy  to  see  that  if  the  receiver  accelerates,  or 
retards  its  motion,  in  consequence  of  some  variation  in  the  level  or  quantity  of  the  water  above,  the 
rapidity  of  the  revolution  of  the  scoop-wheel  R,  and  the  motion  of  the  endless  cloth  of  the  machine,  will 
each  feel  a proportional  variation.  But  as  the  scoop-wheel  for  each  of  its  revolutions  pours  the  same 
quantity  of  pulp  into  the  filter  c of  the  machine,  it  is  evident  that  the  feeding  on  of  the  pulp  will  aug- 
ment, or  diminish  proportionally  to  the  velocity  of  translation  of  the  endless  cloth,  and  that,  conse- 
quently, the  strength  of  the  paper  ought  to  be  constant,  so  long  as  we  do  not  change  the  ratio  betweeu 
Die  quantity  of  pulp  furnished  and  the  distance  moved  in  a given  time  by  the  metallic  clotli. 


460 


PAPER  MACHINES. 


This  principle  established,  the  following  are  the  details  of  the  ingenious  apparatus  of  Sandford  ana 
\T  arrall. 

R,  as  we  have  said,  is  the  regulating  wheel,  provided  with  scoops  eee\  this  wheel  is  confined  in  a 
drum  B,  which  the  pulp  enters  from  the  reservoirs  A A by  the  large  stop-cocks  r r,  kept  entirely  open, 
so  as  to  maintain  sensibly  in  the  drum  B the  same  level  as  in  the  reservoirs  A A.  It  is  of  little  im- 
portance, moreover,  if  this  level  be  not  rigorously  equal,  nor  even  if  it  varies  notably  in  the  reservoirs 
A A ; for,  provided  the  pulp  arrives  in  sufficient  quantity,  and  we  must  take  care  that  it  be  always  so, 
each  of  the  scoops,  every  time  they  issue  from  the  pulp,  only  withdraws  the  same  quantity  of  material. 

3008.  3010. 


We  easily  conceive  how  advantageous  is  this  property  of  the  apparatus,  since,  notwithstanding  all  the 
variations  of  level  of  the  liquid  pulp  in  the  reservoir,  or  stuff-chest,  it  assures  regularity  in  feeding  on 
the  pulp — a regularity  which  would  often  be  compromised  if  made  dependent  solely  on  this  level. 

It  is  necessary  that  the  relation  which  ex- 
ists between  the  number  of  revolutions  of  the  3009. 

scoop-wheel  R and  the  velocity  of  the  endless 
cloth  may  be  varied,  when  we  wish  to  alter 
the  strength  of  the  paper. 

To  obtain  this  effect,  Sandford  and  Varrall 
have  controlled  the  scoop-wheel  R by  the  two 
parallel  cones  C and  C',  which  carry  the  belt  d\ 
the  cone  C'  receiving  its  motion  from  the  lat- 
eral shaft  established  alongside  the  paper  ma- 
chine, and  on  which  is  all  the  geering  which 
moves  the  endless  cloth,  and  the  other  movable 

parts  of  the  machine.  3012. 


It  is  sufficient  to  move  the  belt  laterally,  (along  the  cones,)  in  order  to  retard  or  accelerate  the  rota, 
tion  of  the  scoop-wheel,  without  altering  the  angular  velocity  of  the  other  movable  parts,  and  thus, 
consequently,  to  change  the  relation  in  question,  and  of  course  the  thickness  of  the  paper  made. 


PAPER  MACHINES. 


461 


PAPER  CUTTING.  The  following  machine  for  cutting  paper  was  contrived  by  J.  Dickinson,  of  Nash 
Mill.  The  paper  is  wound  upon  a cylindrical  roller  a,  Fig.  3013,  mounted  upon  an  axle,  supported  in  an 
iron  frame  or  standard.  From  this  roller  the  paper  in  its  breadth  is  extended  over  a conducting  drum  b, 
also  mounted  upon  an  axle  turning  in  the  frame  or  standard,  and  after  passing  under  a small  guide-roller, 
it  proceeds  through  a pair  of  drawing  or  feeding  rollers  c,  which  carry  it  into  the  cutting  machine. 

Upon  a table  ad,  firmly  fixed  to  the  floor  of  the  building,  there  is  a series  of  chisel-edged  knives  ee  e, 
placed  at  such  distances  apart  as  the  dimensions  of  the  cut  sheets  of  paper  are  intended  to  be.  These 
knives  are  made  fast  to  the  table,  and  against  them  a series  of  circular  cutters  fff,  mounted  in  a 
swinging  frame  g g,  are  intended  to  act.  The  length  of  paper  being  brought  along  the  table  over  the 
edges  of  the  knives,  up  to  a stop  h,  the  cutters  are  then  swung  forwards,  and  by  passing  over  the  paper 
against  the  stationary  knives,  the  length  of  paper  becomes  cut  into  three  separate  sheets. 


The  frame  gg,  which  carries  the  circular  cutters  fff,  hangs  upon  a very  elevated  axle,  in  order  that 
its  pendulous  swing  may  move  the  cutters  as  nearly  in  a horizontal  line  as  possible ; and  it  is  made  to 
vibrate  to  and  fro  by  an  eccentric  or  crank,  fixed  upon  a horizontal  rotary  shaft  extending  over  the  drum 
b,  considerably  above  it,  which  may  be  driven  by  any  convenient  machinery. 

The  workmen  draw  the  paper  from  between  the  rollers  c,  and  bring  it  up  to  the  stop  h,  in  the  inter- 
vals between  the  passing  to  and  fro  of  the  swing-cutters. 

The  following  very  ingenious  appara- 
tus for  cutting  the  paper  web  trans- 
versely into  any  desired  lengths,  was 
made  the  subject  of  a patent  by  Mr.  E. 

N.  Fourdrinier,  in  June,  1831,  and  has 
since  been  performing  its  duty  well  in 
many  establishments. 

Fig.  3014  is  an  elevation,  taken  upon 
one  side  of  the  machine;  and  Fig.  3015 
is  a longitudinal  section,  aaaa  are  four 
reels,  each  covered  with  one  continuous 
sheet  of  paper ; which  reels  are  supported 
upon  bearings  in  the  framework  bbb. 
c c c is  an  endless  web  of  felt  cloth  passed 
over  the  rollers  dddd,  which  is  kept  in 
close  contact  with  the  under  side  of  the 
drum  ee,  seen  best  in  Fig.  3016. 

The  several  parallel  layers  of  paper  to 
be  cut,  being  passed  between  the  drum  e 
and  the  endless  felt  c,  will  be  drawn  off 
their  respective  reels  and  fed  into  the 
machine,  whenever  the  driving-band  is 
slid  from  the  loose  to  the  fast  pulley 
upon  the  end  of  the  main  shaft/.  But 
since  the  progressive  advance  of  the 
paper-webs  must  be  arrested  during  the 
time  of  making  the  cross-cut  through  it, 
the  following  apparatus  becomes  neces- 
sary. A disk  g,  which  carries  the  pin  or 
stud  of  a crank  i,  is  made  fast  to  the  end 
of  the  driving-shaft  /.  This  pin  is  set  in 
an  adjustable  sliding-piece,  which  may  be 
confined  by  a screw  within  the  bevelled 
graduated  groove,  upon  the  face  of  the 
disk  g,  at  variable  distances  from  the 
axis,  whereby  the  eccentricity  of  the 
stud  i,  and  of  course  the  throw  of  the 
crank,  may  be  considerably  varied.  The 
crank-stud  i is  connected  by  its  rody  to  the 
swinging  curvilinear  rack  k,  which  takes 
into  the  toothed  wheel  l that  turns  freely 

upon  the  axle  of  the  feed-drum  ee.  From  that  wheel  the  arms  mm  rise,  and  bear  one  or  more  palls  n, 
which  work  in  the  teeth  of  the  great  ra+chet-wheel  o o,  mounted  upon  the  shaft  of  the  drum  e. 


462 


PARALLEL  MOTIONS. 


The  crank-plate  g being  driven  round  in  the  direction  of  its  arrow,  will  communicate  a see-saw  move- 
ment to  the  toothed  arc  k,  next  to  the  toothed  wheel  l in  geering  with  it,  and  an  oscillatory  motion  tc 
the  arms  m m,  as  also  to  their  surmounting  pall  n. 

In  its  swing  to  the  left  hand,  the  catch  of  the  pall  will  slide  over  the  slope  of  the  teeth  of  the  ratchet- 
wheel  o ; but  in  its  return  to  the  right  hand  it  will  lay  hold  of  these  teeth  and  pull  them,  with  their 
attached  drum,  round  a part  of  a revolution.  The  layers  of  paper  in  close  contact  with  the  under  half  ol 
the  drum  will  be  thus  drawn  forward  at  intervals,  from  the  reels,  by  the  friction  between  its  surface  and 
the  endless  felt,  and  in  lengths  corresponding  to  the  arc  of  vibration  of  the  palh  The  knife  for  cutting 
these  lengths  transversely  is  brought  into  action  at  the  time  when  the  swing  arc  is  making  its  inactive 
stroke,  viz.,  when  it  is  sliding  to  the  left  over  the  slopes  of  the  ratchet-teeth  o.  The  extent  of  this 
vibration  varies  according  to  the  distance  of  the  crank-stud  i from  the  centre/,  of  the  plate  g,  because 
that  distance  regulates  the  extent  of  the  oscillations  of  the  curvilinear  rack,  and  that  of  the  rotation  of 
the  drum  c,  by  which  the  paper  is  fed  forwards  to  the  knife  apparatus.  The  proper  length  of  its  several 
layers  being  by  the  above-described  mechanism  carried  forward  over  the  bed  r of  the  cutting-knife  or 
shears  r v,  whose  under  blade  r is  fixed,  the  wiper  s,  in  its  revolution  with  the  shaft  f lifts  the  tail  of  the 
lever  t,  consequently  depresses  the  transverse  movable  blade  v,  (as  shown  in  Fig.  8015,)  and  slides  the 
slanting  blades  across  each  other  obliquely,  like  a pair  of  scissors,  so  as  to  cause  a clean  cut  across  the 
plies  of  paper.  But  just  before  the  shears  begin  to  operate,  the  transverse  boaid  u descends  to  press 
the  paper  with  its  edge,  and  hold  it  fast  upon  the  bed  r.  During  the  action  of  the  upper  blade  y 
against  the  under  r,  the  fall-board  u is  suspended  by  a cord  passing  across  pulleys  from  the  arm  y of 
the  bell-crank  lever  1 1.  Whenever  the  lifter  cam  s has  passed  away  from  the  tail  of  the  bell-crank  t, 
the  weight  z,  hung  upon  it,  will  cause  the  blade  v,  and  the  pinching-board  w,  to  be  moved  up  out  of  the 
way  of  the  next  length  of  paper,  which  is  regularly  brought  forward  by  the  rotation  of  the  drum  e,  as 
above  described.  The  upper  blade  of  the  shears  is  not  set  parallel  to  the  shaft  of  the  drum,  but 
obliquely  to  it,  and  is,  moreover,  somewhat  curved,  so  as  to  close  its  edge  progressively  upon  that  of  the 
fixed  blade.  The  blade  v may  also  be  set  between  two  guide-pieces,  and  have  the  necessary  motion 
given  to  it  by  levers. 

PARALLEL  MOTIONS.  The  following  figures  exhibit  a variety  of  forms  of  parallel  motions,  such 
as  are  employed  to  maintain  the  rectilineal  direction  of  the  piston-rod  of  a steam-engine,  under  the 
constantly  varying  angular  direction  of  the  beam.  Contrivances  of  this  kind  are  required  in  other  cir- 
cumstances of  the  conversion  of  rotatory  and  alternating  angular  motion  into  rectilineal  motion,  and  the 
converse ; but  the  absolute  necessity  there  is  of  guiding  the  path  of  piston  in  the  steam-engine,  has 
called  forth  more  attention  to  the  principles  and  mechanism  of  parallel  motions  than  would  otherwise, 
in  all  probability,  have  been  awarded  to  the  subject  for  other  purposes.  In  the  first  place,  the  principle 
may  be  briefly  indicated. 


Fig.  3016.  Given  A B D a right  angle : it  can  be  demonstrated  that  if  the  end  A of  the  right  line  A I 
aescend  from  A to  B along  the  line  A B,  while  the  end  D moves  along  the  line  B D produced,  a point  C in 
the  middle  of  the  line  will  describe  the  circle  C G.  Hence,  if  a beam  A D has  one  end  sliding  in  a groove 
at  D,  and  is  connected  or  jointed  at  the  middle  C in  a guide  B C of  half  its  length,  this  guide  also  mov- 
ing on  a joint  at  B,  then  in  every  position  of  the  beam  the  point  C will  describe  the  circle  C G,  and  the 
point  A of  the  beam  will  move  in  a straight  line. 

Fig.  3017.  In  practice,  it  may  be  more  convenient  to  have  the  erl  D of  the  beam  fixed  to  the  ena 


PARALLEL  MOTIONS. 


163 


of  a movable  bar,  as  D N,  of  some  feet  in  length,  than  to  slide  in  a groove  ; for,  though  the  arc  described 
by  the  end  D will  deviate  a little  from  a straight  line,  yet  the  error  produced  thereby  will  be  so  very 
small  that  it  can  have  no  bad  effect,  or  even  be  discovered  in  practice. 

In  the  steam-engine  there  are  various  modes  adopted  by  means  of  jointed  rods,  (fee.,  different  from 
that  described  above,  for  causing  the  piston-rod,  attached  to  the  end  of  the  beam,  to  move  in  a straight 
line,  which,  although  not  mathematically  correct,  are  still  so  very  near  the  truth  as  to  answer  the  pur- 
pose wanted  exceedingly  well ; such  a system  of  jointed  rods  is  generally  termed  by  engineers  a par- 
allel motion. 


Fig.  3018.  In  the  beam  aF,  which  is  shown  in  its  three  positions,  viz.,  at  the  middle  and  the  two 
extremities  of  tho»stroke,  the  versed  sine  a 6 of  the  arc  formed  by  the  extremity  of  the  beam,  is  termed 
the  vibration,  and  a piston-rod  attached  to  the  beam  is  made  to  move  in  a line  bisecting  this  vibration ; 
thus,  if  a piston-rod  were  attached  to  the  beam  aF,  cd  is  the  line  in  which  the  rod  ought  to  move. 

Fig.  3019  is  a general  mode  of  finding  the  length  of  the  radius-rod  G c,  and  shows  the  principle  upon 
which  parallel  motions  formed  by  jointed  rods  are  founded;  «F  is  the  beam,  a c a strap,  one  end  of 
which  is  attached  to  the  beam,  and  the  piston-rod  is  attached  somewhere  about  the  middle,  as  at  b ; 
the  beam  is  then  put  in  its  three  positions,  and  while  the  point  b to  which  the  piston-rod  is  fixed  is  kept 
in  the  straight  line,  bisecting  the  vibration,  thft  positions  of  the  lower  end  c of  the  strap  are  carefully 
marked,  as  at  ccc-,  then  the  centre  G of  the  circle  passing  through  these  points  will  be  the  point  to 
which  the  radius-rod  Gc,  connected  to  the  strap  at  c,  should  be  fixed,  and  the  radiijs  of  the  circle  will 
be  the  length  of  the  rod.  If  the  point  b be  taken  exactly  in  the  middle  of  the  strap,  the  length  of  the 
radius-rod  G c will  be  equal  to  the  portion  of  the  beam  a F. 


3021. 


Fig.  3020  is  another  plan  of  a parallel  motion  sometimes  used  : the  method  of  finding  the  length  of 
the  rod  D c and  position  of  the  point  !>  is  the  very  same  as  that  described  in  Fig.  3019,  viz.,  by  putting 
the  beam  in  its  three  positions,  and  marking  the  places  of  the  points  ccc  of  the  strap,  while  the  point  b 
to  which  the  piston-rod  is  fixed  is  kept  in  the  same  straight  line:  the  radius  D c of  the  circle  passing 
through  the  points  ccc  will  be  the  length  of  the  radius-rod,  and  the  centre  of  the  same  circle  the  point 
to  which  it  should  be  fixed. 

Fig.  3021  is  a method  of  causing  the  piston-rod  to  describe  a straight  line,  often  adopted  in  forcing- 


464 


PARALLEL  MOTIONS. 


pumps : the  lever  F lias  the  centre  of  motion  at  o in  the  up  standard  s,  fixed  upon  the  cover  of  the  pump 
1)  is  a cylindrical  rod,  also  fixed  to  the  top  of  the  pump,  and  set  quite  parallel  to  the  pump-rod  R ; g 
is  a cross  head  attached  to  the  top  of  the  pump-rod,  having  a projecting  arm  h terminating  in  a socket/ 
•which  moves  on  the  rod  D ; the  lever  F is  connected  to  the  cross-head  g by  two  straps,  one  of  which 
is  shown  at  c ; upon  moving  the  lever  F it  will  be  quite  clear  that  the  piston-rod  R must  move  par- 
allel to  D. 

Fig.  3022  is  a drawing  of  a walking-beam  for  a twelve-horse  engine,  with  parallel  motion  attached 
The  point  B to  which  the  inner  strap  is  fixed,  is  very  often  taken  exactly  in  the  centre,  betwixt  A and  c 
and  when  that  is  the  case,  the  length  of  the  radius-rods  is  equal  to  the  same  distance,  or,  in  other  words, 
equal  to  the  fourth  part  of  the  whole  length  of  beam. 

When  the  inner  strap  is  suspended  from  any  other  point  than  in  the  middle  of  the  distance  Ac,  the 
position  of  the  centre  and  length  of  the  rod  ef  would  be  found  as  described  in  Fig.  3019:  keeping  the 
point  a to  which  the  piston-rod  is  attached  always  in  the  same  straight  line  in  which  it  ought  to  move, 
and  carefully  marking  the  points  assumed  by  the  lower  end  of  the  strap/. 

The  point  b to  which  the  air-pump  rod  is  fixed  should  be  exactly  in  the  middle  of  the  strap,  when  the 
beam  is  divided  into  four  equal  parts,  which  will  also  insure  a parallel  motion  for  the  bucket  of  the 
air-pump. 


P 


3024. 


So.:' 


Fig.  3023  is  a mode  of  causing  the  piston-rod  to  describe  a straight  line  by  the  use  of  the  two  friction- 
wheels  W W confined  betwixt  the  guides  G G ; this  plan  is  often  used  in  small  engines,  when  the  crank 
to  which  the  connecting-rod  P is  attached  is  immediately  above  the  cylinder. 

Fig.  3024  is  a plan  of  parallel  motion  usually  employed  in  marine  engines ; the  manner  of  finding  the 
length  and  position  of  the  radius-rod  g is  precisely  the  same  as  in  Fig.  3019 ; this  motion  is,  in  fact,  the 
common  parallel  motion  modified  to  suit  the  circumstan- 
ces in  which  it  is  placed.  The  length  of  the  radius-bar 
ef  is  easily  found  in  practice,  by  supposing  the  piston-rod 
to  move  in  a right  line,  and  finding  three  points  through 
which  a point  in  the  side-rod  A,  assumed  at  pleasure, 
would  pass,  in  the  highest,  middle,  and  lowest  positions 
of  the  piston-rod  ; then  a circular  arc  passing  through 
these  points  will  give  the  radius  and  centre  sought ; and 
the  point  e assumed  in  the  side-rod  will  be  the  point  of 
connection  of  the  radius-bar. 

Now,  in  order  that  the  point  P of  connection  of  the  side- 
rod  and  piston-rod  may  describe  a right  line,  the  point / 
must  describe  an  arc  of  curvature  sufficient  to  neutralize 
the  curvature  which  would  be  transmitted  to  it  by  the 
travel  of  the  side-lever;  to  determine  this  arc///,  it  is 
only  necessary  to  describe  from  the  middle  point  of  the 
stroke,  taken  in  the  straight  line  e«e,  a right  line  egf 
equal  in  length  to  the  length  of  the  radius-bar,  and  per- 
pendicular to  it ; also  the  highest  position  of  the  radius- 
bar  forming  the  same  angle  with  egf  that  the  radius-bar 
forms  with  that  line  in  its  lowest  position ; then  the  three 
points///1  being  thus  found,  a circular  arc  drawn  through 
them  will  determine  the  fixed  centre  g,  and  the  length  of 
the  parallel  bar  g f 

The  length  of  the  side-bar  c from  f to  its  connection 
with  the  side-lever,  must  of  course  be  equal  in  length  to 
the  side-rod  A,  from  ? to  the  point  also  of  its  connection 
with  the  side-lever.  These  rods  will  remain  during  the 
working  of  the  engine  parallel  to  each  other,  and  conse- 
quently the  radius-rod  will  continue  parallel  to  the  axis 

of  the  side-lever  in  all  positions  of  the  stroke.  It  must,  however,  be  remarked,  that  the  parallelism  is 
not  absolutely  correct,  but  is  true  only  within  certain  though  narrow  limits,  giving  an  approximation 
sufficiently  near  for  common  practice. 


PENDULUM. 


465 


Fig.  3025  shows  a form  of  parallel  motion  sometimes  adopted  in  land-engines  of  the  smaller  class 
It  is  susceptible  of  great  accuracy,  and  admits  of  several  modifications. 

In  this  figure  A is  the  cylinder  of  the  engine,  B the  beam,  supported  on  a rocking-bar  having  a mov- 
able centre  at  D.  The  radius-bar  has  its  fixed  centre  at  a attached  to  the  framing  of  the  engine,  and  is 
centred  to  the  beam  at  a point  c equidistant  from  the  main  centre/  and  the  point  of  attachment  to  the 
piston-rod.  Flow,  the  radius-rod  being  equal  to  half  the  radius  of  the  beam,  and  the  radius-bar  having 
a fixed  centre  at  a,  the  point  c of  the  beam  must  of  necessity  describe  the  arc  ccc  during  each  stroke  ol 
the  piston.  Now,  in  describing  this  arc  it  is  plain  that  the  main  centre /of  the  beam  must  describe 
simultaneously  an  arc  about  the  centre  D upon  which  it  is  carried.  But  the  radius  / D being  great  in 
comparison  to  radii/c  and  ac,  the  motion  of  the  main  centre  may  be  supposed,  without  sensible  error, 
to  be  in  a right  line,  as  if  it  were  free  to  slide  in  a horizontal  groove.  But  the  centre  / being  constrained 
to  move  horizontally  through  a given  space  during  a stroke  of  the  piston,  the  end  a of  the  beam  will 
travel  horizontally  through  an  equal  space  in  the  same  direction,  and  will  therefore,  instead  of  describing 
an  arc  about  the  centre  f describe  the  chord  a aa  oi  that  arc,  parallel  to  the  chord  of  the  arc  ccc,  which 
is  the  thing  wanted. 

This  motion  and  its  modifications  are  founded  on  the  principle  that  if  the  arc  of  a semicircle  be  made 
to  slide  against  a fixed  point  p,  Fig.  3026,  while  one  of  its  extremities  x is  constrained  to  move  in  a 
straight  line  xp,  the  other  extremity  y will  describe  another  straight  line  py  at  right  angles  to  the 
first. 


To  exhibit  this  principle  in  a practicable  form,  let  in  n be  a rigid  bar,  having  the  end  n guided  in  a 
horizontal  groove,  in  which  it  can  slide  freely,  as  represented  in  Fig.  3027  ; and  let  p q be  also  a rigid 
bar  jointed  to  the  former  at  q,  and  having  a fixed  centre  at  p.  Let  this  bar  be  half  the  length  of  the 
bar  m n , and  let  mq  — nq\  it  is  then  evident,  from  the  principle  stated  above,  that,  as  the  groove  at  n 
and  the  fixed  centre  at  q control  the  motion  of  the  bar  m n,  the  end  m is  constrained  to  move  in  a straight 
line  mp  r at  right  angles  to  p n,  which  is  the  condition  to  be  fulfilled. 

In  Fig.  3025,  instead  of  the  slot  at  n the  main  centre  is  allowed  to  traverse  a small  arc,  which,  devi- 
ating very  little  from  a right  line,  fulfils  the  condition  with  considerable  exactness.  The  same  principle 
may  be  applied  in  various  ways. 

P ARAMETER.  In  geometry,  a constant  straight  line,  belonging  to  each  of  the  three  conic  sections 
— otherwise  called  the  latus  rectum.  In  the  parabola,  the  parameter  is  a third  proportional  to  the 
absciss  and  its  corresponding  ordinate ; in  the  ellipse  and  hyperbola,  the  parameter  of  a diameter  is  a 
third  proportional  to  that  diameter  and  its  conjugate.  The  term  is  also  used  in  a general  sense,  to  de- 
note the  constant  quantity  which  enters  into  the  equation  of  a curve. 

PENDULUM.  If  any  heavy  body,  suspended  by  an  inflexible  rod  from  a fixed  point,  be  drawn  aside 
from  the  vertical  position,  and  then  let  fall,  it  will  descend  in  the  arc  of  a circle  of  which  the  point  of 
suspension  is  the  centre.  On  reaching  the  vertical  position  it  will  have  acquired  a velocity  equal  to 
that  which  it  would  have  acquired  by  falljng  vertically  through  the  versed  sine  of  the  arc  it  has  de- 
scribed, in  consequence  of  which  it  will  continue  to  move  in  the  same  arc  until  the  whole  velocity  is  de- 
stroyed ; and  if  no  other  force  than  gravity  acted,  this  would  take  place  when  the  body  reached  a height 
on  the  opposite  side  of  the  vertical  equal  to  the  height  from  which  it  fell.  Having  reached  this  height 
it  would  again  descend,  and  so  continue  to  vibrate  forever ; but  in  consequence  of  the  friction  of  the 
axis,  and  the  resistance  of  the  air,  each  successive  excursion  will  be  diminished,  and  the  body  soon  be 
orought  to  rest  in  the  vertical  position.  A body  thus  suspended,  and  caused  to  vibrate,  is  called  a 
pendulum  ; and  the  passage  from  the  greatest  distance  from  the  vertical  on  the  one  side  to  the  greatest 
distance  on  the  other  is  called  an  oscillation. 

In  order  to  investigate  the  circumstances  of  the  motion,  the  body  must  be  regarded  as  a gravitating 
point,  and  the  inflexible  rod  as  devoid  of  weight.  This  is  denominated  the  simple  pendulum,  and  the 
pioblem  to  be  resolved  is  to  determine  the  motion  of  a point  constrained  to  move  in  a circular  arc  in 
virtue  of  the  accelerating  force  of  terrestrial  gravity. 

Von.  II.— 30 


4G6 


PENDULUM. 


According  to  the  theory  of  falling  bodies,  (See  Gravity,)  the  time  t in  'which  a body  falls  through  th« 

2s 

space  s,  by  the  accelerating  force  of  gravity,  is  given  by  the  equation  t — -f — . Let  2 s = /;  then  t ~- 

l .9.1 

J -■  But  the  time  T,  of  the  oscillation  of  a pendulum  whose  length  is  /,  is  T = tta/-;  therefor* 

9 \ 9 

T : t : : t : 1 ; consequently  the  time  of  the  oscillation  of  a pendulum  is  to  the  time  that  a heavy  body 
would  fall  freely  by  the  force  of  gravity  through  half  its  length,  as  the  circumference  of  a circle  to  its 
diameter. 

If  we  suppose  the  time  to  be  expressed  in  seconds,  and  make  T = 1,  we  shall  have  g = t?  1.  Cap- 
tain Kater  found  the  length  of  the  simple  pendulum  at  London  to  be  39-13929  inches,  and  we  know 
that  tt 2 = 9-8696  ; therefore  g = 9-8696  X 39'1 39  = 386-29  inches,  or  g — 32-2  feet.  It  follows,  there- 
fore, that  the  space  tlirough  which  a body  falls  freely  at  London  in  a second  of  time  is  16-1  feet. 

Compound  pendulum. — The  simple  pendulum,  as  above  defined,  is  only  a theoretical  abstraction , 
for  the  oscillating  body  can  neither  be  so  small  that  it  may  be  regarded  as  a mathematical  point,  nor 
can  the  rod  be  entirely  devoid  of  weight.  When  the  body  has  a sensible  magnitude,  and  the  suspend- 
ing-rod  a sensible  magnitude  and  weight  as  they  must  have  in  all  actual  constructions,  the  apparatus  is 
called  a compound  pendulum ; and  instead  of  being  supported  by  a single  point  it  is  supported  by  an 
axis,  or  by  a series  of  points  situated  in  the  same  straight  line.  According  to  this  definition,  any  heavy 
body  oscillating  about  an  axis  of  suspension  is  a compound  pendulum. 

In  every  compound  pendulum  there  is  necessarily  a certain  point  at  which,  if  all  the  matter  of  the 
pendulum  were  collected,  the  oscillations  would  be  performed  in  exactly  the  same  time.  This  point  is 
the  centre  of  oscillation.  (See  Centre  of  Oscillation.)  It  is  situated  in  the  vertical  plane  passing 
through  the  centre  of  gravity  of  the  pendulum,  and  at  a distance  from  the  axis  of  suspension,  (the  axis 
being  always  supposed  horizontal,)  which  is  determined  by  the  following  formula:  Let  dm  be  the  ele- 
ment of  the  mass  of  the  compound  pendulum,  r its  distance  from  the  axis  of  rotation,  and  x the  distance 
of  the  centre  of  oscillation  from  the  same  axis ; then 

x=j^r1dm-r ■ rdm\ 

that  is,  the  distance  of  the  centre  of  oscillation  from  the  axis  of  suspension  is  equal  to  the  moment  oi 
inertia  of  the  oscillating  body  divided  by  its  moment  of  rotation.  This  value  of  x is  the  length  of  the 
isochronous  simple  pendulum,  and  is  what  is  always  to  be  understood  by  the  term  length  of  a pendulum 

The  centre  of  oscillation  possesses  a very  remarkable  property,  which  was  discovered  by  Huygens ; 
namely,  that  if  the  body  be  suspended  from  this  point,  or  a horizontal  axis  passing  through  it  parallel 
to  the  former  axis  of  suspension,  its  oscillations  will  be  performed  in  the  same  time  as  before  ; in  other 
words,  the  axis  of  suspension  and  oscillation  are  interchangeable.  This  property  furnishes  an  easy  prac- 
tical method  of  determining  the  centre  of  oscillation,  and  thence  the  length  of  a compound  pendulum. 

Applications  of  the  pendulum. — The  most  important  application  that  has  been  made  of  the  pendulum 
is  to  the  measurement  of  time. 

Compensation  pendulum. — The  value  of  the  pendulum  as  a regulator  of  time-pieces  depends  on  the 
isoclironism  of  its  oscillations ; which,  in  its  turn,  depends  on  the  invariability  of  the  distance  between 
the  points  of  suspension  and  oscillation.  But,  as  every  known  substance  expands  with  heat  and  con- 
tracts with  cold,  the  length  of  the  pendulum  will  vary  with  every  alteration  of  temperature,  and  the  rate 
of  the  clock  consequently  undergo  a corresponding  change.  To  counteract  this  variation  numerous  con- 
trivances have  been  employed.  The  principle  is,  however,  the  same  in  all ; and  consists  in  combining  two 
substances,  whose  rates  of  expansion  are  unequal,  in  such  a manner  that  the  expansion  of  the  one  counter- 
acts that  of  the  other,  and  keeps  the  centre  of  oscillation  of  the  compound  body  always  at  the  same  dis- 
tance from  the  axis  of  suspension.  A brief  description  of  the  two  compensation  pendulums  in  most 
common  use — the  mercurial  pendulum  and  the  gridiron  pendulum — will  sufficiently  explain  the  means 
by  which  compensation  is  obtained. 

Mercurial  pendulum. — This  was  the  invention  of  Mr.  George  Graham,  a celebrated  watchmaker,  who 
subjected  it  to  the  test  of  experiment  in  the  year  1721.  The  rod  of  the  pendulum  is  made  of  steel,  and 
may  be  either  a flat  bar  or  a cylinder.  The  bob  or  weight  is  formed  by  a cylindrical  glass  vessel,  about 
8 inches  in  length  and  2 inches  in  diameter,  which  is  filled  with  mercury  to  the  depth  of  about  6 J inches. 
The  cylinder  is  supported  and  embraced  by  a stirrup,  formed  also  of  steel,  through  the  top  of  which  the 
lower  extremity  of  the  rod  passes,  and  to  which  it  is  firmly  fixed  by  a nut  and  screw  on  the  end  of  the 
rod.  Now  the  effect  of  an  increase  of  temperature  on  this  apparatus  is  evidently  as  follows : In  the 
first  place,  the  rod  expands,  and  the  distance  between  the  axis  of  suspension  and  the  bottom  of  the  stir- 
rup is  increased.  In  the  second  place,  by  the  expansion  of  the  mercury  in  the  cylinder,  its  column  is 
lengthened,  and  the  distance  of  its  centre  of  gravity  from  the  bottom  of  the  stirrup  consequently  in- 
creased. But,  as  the  expansion  of  mercury  is  about  sixteen  times  greater  than  that  of  steel,  the  height 
of  the  mercurial  column  may  be  so  adjusted  by  trial  that  the  expansion  of  the  rod  and  stirrup  shall  be 
exactly  compensated  by  that  of  the  mercury,  and  the  centre  of  oscillation  of  the  whole  suffer  no  change. 
This  pendulum  is,  perhaps,  the  most  perfect  of  all  compensators ; but,  as  its  adjustments  are  attended 
with  considerable  difficulty,  it  is  seldom  used  excepting  in  astronomical  observatories. 

Gridiron  pendulum. — This  was  contrived  by  Mr.  Harrison,  the  inventor  of  the  chronometer.  It  con- 
sists of  a frame  of  nine  parallel  bars  of  steel  and  brass,  arranged  as  follows  : The  centre  rod,  of  steel,  is 
fixed  at  the  top  to  a cross-bar  connecting  the  two  middle  brass  rods,  but  slides  freely  through  the  twe 
lower  cross-bars,  and  bears  the  bob.  The  remaining  rods  are  fastened  to  the  cross-pieces  at  both  ends, 
and  the  uppermost  cross-piece  is  attached  to  the  axis  of  suspension.  It  is  easy  to  see  that  the  expan- 
sion of  the  steel  rods  tends  to  lengthen  the  pendulum,  while  that  of  the  brass  rods  tends  to  shorten  it ; 
consequently,  if  the  two  expansions  exactly  counteract  each  other,  the  length  of  the  pendulum  will  re- 
main unchanged.  The  relative  lengths  of  the  brass  and  steel  bars  are  determined  by  the  expansions  oi 


PENS,  STEEL. 


467 


til  3 two  metals,  which  are  found  by  experiment  to  be,  in  general,  nearly  as  100  to  61.  If,  then,  the 
lengths  of  all  the  five  steel  bars  added  together  be  100  inches,  the  sum  of  the  lengths  of  the  four  brass 
bars  ought  to  be  61  inches.  When  the  compensation  is  found  on  trial  not  to  be  perfect,  an  adjustment 
is  made  by  shifting  one  or  more  of  the  cross-pieces  higher  on  the  bars. 

Application  of  the  pendulum  to  the  determination  of  the  relative  force  of  gravity  at  different  places. — 
There  are  two  methods  of  determining  the  relative  intensity  of  gravity  by  means  of  the  pendulum.  Ac- 
cording to  the  first,  the  absolute  length  of  the  simple  pendulum  which  makes  a certain  number  of  oscil- 
lations in  a given  time  is  accurately  ascertained  at  each  of  the  places,  and  the  comparative  force  of 

l> 

gravity  is  then  given  by  the  formula  g’  — -^-g.  According  to  the  other  method,  an  invariable  pendu- 


lum is  swung  at  the  different  places,  and  the  number  of  its  oscillations  noted  at  each,  when  the  relative 

N'2 

gravity  is  given  by  the  formula  g'  — — g.  Each  of  these  methods  has  been  followed  in  the  delicate 


experiments  which  have  been  made  for  the  purpose  of  determining  the  figure  of  the  earth ; but  though 
the  results  of  both  appear  to  be  nearly  equal  in  point  of  accuracy,  the  latter  method,  on  account  of  its 
affording  greater  facilities  in  practice,  is  now  generally  adopted.  See  Watchmaking. 

PENS,  STEEL,  manufacture  of  The  manufactory,  at  Birmingham,  of  Messrs.  Hinks,  Wells,  & Co., 
a few  years  ago  consisted  of  a small  house  on  one  side  of  the  street.  Now  the  establishment  has 
become  an  immense  manufactory,  giving  employment  to  664  hands,  consuming  24  tons  of  steel  per 
week,  turning  out  35,000  gross  of  pens  weekly,  or  1,820,000  gross  in  a year. 

The  metal  in  its  crude  state. — This  consists  of  the  best  quality  of  cast-steel,  made  from  Swedish  iron, 
its  granular  structure  dense  and  compact.  It  is  in  sheets  44  feet  long  by  18  inches  wide,  which  sheets 
are  clipped  across  into  lengths  from  If  to 44  inches  wide.  These  strips  are  packed  into  cast  metal  boxes, 
and  placed  on  what  is  technically  called  a muffle,  or  large  stone  oven,  heated  to  a white  heat ; there  the 
process  of  annealing  takes  place.  After  twelve  hours  of  this  roasting,  the  strips  are  placed  in  revolving 
barrels,  where,  by  the  friction  of  metallic  particles,  the  scales  caused  by  the  annealing  and  the  rough 
edges  are  removed.  They  are  now  ready  for  the  rolling-mill.  The  rollers  consist  of  metal  cylinders 
revolving  upon  each  other.  A man  and  boy  attend  at  each.  The  first  introduces  the  strip  of  steel 
between  the  opposing  surfaces,  and  the  boy  pulls  it  out  considerably  attenuated.  From  the  first  pair 
of  rollers  it  passes  through  several  others,  until  it  finally  assumes  the  requisite  tenuity.  Such  is  the 
pressure  employed,  that  the  steel,  in  passing  through,  becomes  hotter  than  it  is  sometimes  convenient 
for  unpractised  hands  to  touch.  The  strip  of]  steel  is  now  precisely  the  thickness  of  a pen,  is  quite  flex- 
ible, and  has  increased  in  length  from  18  inches  to  4-4  feet. 

It  is  now  ready  for  the  “ cutting-out  room,”  where  the  pen  first  begins  to  assume  a form.  Along  this 
room  a number  of  women  are  seated  at  benches,  cutting  out,  by  the  aid  of  hand-presses,  the  future  pen 
from  the  ribbon  of  steel.  This  is  done  with  great  rapidity,  the  average  product  of  a good  hand  being 
200  gross,  or  28,800,  per  day  of  ten  hours.  Two  pens  are  cut  out  of  the  width  of  the  steel — the  broad 
part  to  form  the  tube,  and  the  points  so  cutting  into  each  other  as  to  leave  the  least  possible  amount  of 
waste. 

From  this  room  the  blanks  are  taken  to  be  pierced.  The  flat  blanks  are  placed  separately  on  a 
steel  die,  and,  by  a half-circular  action  of  a lever  turning  an  upright  screw,  a fine  tool  is  pressed 
upon  the  steel,  and  forms  the  delicate  centre  perforation,  and  the  side  slits  which  give  flexibility  to 
the  pen. 

All  this  time  the  metal  is  soft,  bending  in  the  fingers  like  a piece  of  lead.  It  becomes  necessary, 
however,  that  it  should  be„rendered  still  softer.  The  pens  are  consequently  placed  in  the  heated  oven, 
and  a second  time  annealed.  Proceeding  with  these  softened  pens  to  the  “ marking-room upon  each 
side  and  down  the  middle  of  the  room  are  arranged  a multitude  of  young  women  at  work,  each  oi 
whom  raises  a weight  by  the  action  of  the  foot,  and  suddenly  allows  it  to  fall  on  the  pen.  The  rapidity 
of  this  process  is  equal  to  that  of  cutting  out  the  blanks,  each  girl  marking  many  thousands  of  pens  in 
the  day.  When  it  leaves  the  hand  of  this  operator,  the  back  of  the  pen  is  stamped  either  with  the 
name  of  a retail  dealer  at  home  or  abroad,  a national  emblem,  die.,  according  to  the  fashion. 

The  next  process  is  the  raising.  Until  now  the  pen  is  flat;  and  by  being  placed  in  a groove,  and  a 
convex  tool  dropped  upon  it,  forcing  it  into  the  groove,  it  is  bent  into  a tube  of  the  required  shape. 

Upon  the  perfection  of  the  slit  of  course  depends  the  value  of  the  pen.  Those  who  recollect  the  diffi- 
culty experienced  in  getting  a perfect  slit  in  a quill  pen,  can  understand  how  much  less  easy  it  is  to 
prevent  the  gaping  of  a metallic  substance.  The  first  preparatory  process  after  the  pens  leave  the 
raising-room,  is  to  return  them  once  more  to  the  mufHe,  into  which  they  are  placed  in  small  iron  boxes 
with  Uds,  and  heated  to  a white  heat.  They  are  then  drawn  out  and  suddenly  thrown  into  a large  tank 
of  oil,  where,  by  the  chemical  action  of  the  liquid  on  the  steel,  the  pens  attain  a brittleness  that  makes 
them  crumble  to  pieces  when  pressed  between  the  fingers.  After  being  cleaned  from  the  oil  they  are 
tempered,  or  brought  back  to  the  condition  of  softness  and  elasticity  which  they  are  henceforth  to  retain. 
This  is  done  by  placing  them  in  a cylindrical  vessel,  open  at  one  end  and  turned  over  a tire,  somewhat 
after  the  fashion  in  which  coffee  is  roasted.  The  action  of  the  heat  gradually  changes  the  color  of  the 
pens,  first  from  a dull  gray  to  a pale  straw-color,  next  to  a brown  or  bronze,  and  then  to  blue. 

Still  the  pens  are  rough,  and  covered  with  small  metallic  particles.  To  remove  this  roughness,  they 
are  placed  in  large  tin  cans,  with  a small  quantity  of  sawdust,  itc.  These  cans  lie  horizontally  on  a 
wooden  frame,  and  are  made  to  revolve  by  steam-power,  the  pens  rubbing  against  each  other,  and  so 
cleansing  themselves.  From  this  process  of  scouring , they  are  taken  to  the  grinding-room.”  Each 
individual  pen  of  the  262,080,000  which  are  annually  turned  out  of  this  establishment  undergoes  the 
process  of  grinding,  which  employs  one-fourth  of  the  entire  number  of  hands  engaged  in  the  manu- 
factory. W e have  previously  referred  to  the  difficulty  of  getting  a close  slit  in  a quill  pen.  The 
grinding  serves  the  same  purpose  as  the  scraping  the  back  of  the  quill  did,  as,  by  weakening  a certain 


468 


PERCUSSION-CAP  MACHINE. 


part  of  the  metal,  the  point  where  the  slit  is  made  has  a tendency  to  cohere,  and  so  to  form  * 
good  pen.  The  pen  is  simply  caught  up  by  a pair  of  nippers,  and  held  on  a revolving  bob,  and  so 
ground. 

The  pens  are  now  taken  to  the  “ slitting-room.”  This  work  is  very  light,  for  the  pen  is  simply  placed 
on  a press,  and  the  handle  being  pulled,  a sharp  steel  tool  descends,  and  the  pens  are  perfect.  To 
secure  uniformity  of  quality,  the  pens  are  now  looked  over,  by  the  points  being  pressed  against  a small 
piece  of  bone  placed  on  the  thumb,  and  they  are  then  thrown  into  heaps  according  to  their  quality  of 
good,  bad,  or  indifferent.  They  are  next  varnished  with  a solution  of  gum,  and  are  ready  for  atfixin?  to 
cards,  or  boxing,  the  latter  mode  of  packing  being  almost  universally  adopted. 

PERCUSSION.  The  centre  of  percussion  is  that  point  in  a body  revolving  about  an  axis,  at  which, 
if  it  struck  an  immovable  obstacle,  all  its  motion  would  be  destroyed,  or  it  would  not  incline  either  way 

When  an  oscillating  body  vibrates  with  a given  angular  velocity,  and  strikes  an  obstacle,  the  effect 
of  the  impact  will  be  the  greatest  if  it  be  made  at  the  centre  of  percussion. 

For,  in  this  case,  the  obstacle  receives  the  whole  revolving  motion  of  the  body ; whereas,  if  the 
blow  be  struck  in  any  other  point,  a part  of  the  motion  will  be  employed  in  endeavoring  to  continue  the 
rotation. 

If  a body  revolving  on  an  axis  strike  an  immovable  obstacle  at  the  centre  of  percussion,  the  point  of 
suspension  will  not  be  affected  by  the  stroke. 

PERCUSSION-CAP  MACHINE,  by  Richard  M.  Bouton,  of  West  Troy,  New  York.  Fig.  3028  is 
a front  elevation;  Fig.  3029,  a right-hand  profile  elevation;  Fig.  3030,  four  views  of  the  transfer  appa- 
ratus, full  size;  Fig.  3031,  the  star-punch,  with  its  picker,  lower  die,  and  thimble,  all  in  section,  full 
size;  Fig.  3032,  the  forming-punch  and  its  die,  in  section,  full  size. 

This  machine  consists  essentially  of  two  vertical  punches,  of  which  one  cuts  the  star  or  blank,  of 
which  the  capsule  is  formed ; and  the  other  forms  the  capsule  by  compression.  These  punches  are  at 
their  upper  ends  attached  each  to  its  respective  arm  on  the  same  end  of  a double-headed  lever,  and 
consequently  both  move  at  the  same  time ; and  their  operations  are  combined  in  effect  by  mechanism, 
which  transfers  the  star  or  blank  from  its  punch  to  the  forming-punch.  To  enable  other  practical  me- 
chanics to  make  and  use  my  invention,  I will  proceed  to  describe  its  construction  and  operation. 

A A,  Ac.,  is  the  bed-plate,  on  which  are  fixed  the  frame  of  the  machine  and  a pedestal,  (not  shown,) 
which  supports  the  right-hand  end  of  the  branch  arbor  C C,  to  which  the  power  is  applied. 

B B,  Ac.,  the  frame  of  the  machine,  to  which  most  of  the  working  parts  are  attached. 

L L,  main  lever,  or  double-headed  lever,  by  which  the  punches  are  worked.  Its  long  arm  is,  by  a 
connecting-rod  and  crank-pin,  connected  with  the  crank  of  the  crank-arbor,  h h are  the  short  arms  or 
double  head,  to  which  are  attached 

R R',  the  two  runners  which  carry  the  punches.  1 2 3 4 are  the  guides  through  which  the  runners 
work.  These  runners  may  be  operated  by  cams  on  an  arbor  passing  over  their  upper  ends  or  through 
openings  or  offsets  in  the  middle  of  their  lengths.  In  this  case  the  main  lever  and  crank-arbor  can  be 
dispensed  with,  and  power  be  applied  to  the  cam-arbor  direct. 

Iv  K K,  bench  or  shelf,  projecting  from  the  frame,  on  which  are  the  die-beds  F and  F'.  The  right 
hand  half  of  this  bench  is  elevated  higher  than  the  left-hand  half  of  its  length,  in  order  that  the  star- 
die  on  this  part  shall  be  higher  than  the  forming-die  on  the  left-hand  half,  and  that  the  groove  or  way  of 
the  director  d d , Ac.,  which  rests  on  this  part,  may  be  on  a level  with  the  face  of  the  forming-die  V. 

F,  die-bed  of  the  star-punch.  This  is  a square  above  the  bench,  and  has  a round  shank  passing  down 
into  the  bench,  to  which  it  is  fixed  by  a screw  from  below.  The  star-die  U has  a round  hollow  shank 
passing  down  into  this  bed,  and  is  supported  by  a flanch  X,  Fig.  3031,  at  its  upper  end,  resting  on  the 
top  of  the  die-bed.  Within  this  shank  of  the  star-die  is  a conical  steel  tube  or  thimble  vv,  Fig.  3031, 
the  lower  end  of  which  rests  on  the  director  and  transfer  slide,  it  reaching  up  to  the  cutting  part  of  the 
star-die.  Its  internal  diameter  is  exactly  equal  to  the  diameter  of  the  star  or  blank,  which,  falling 
from  the  star-punch  through  it,  is  conducted  to  its  proper  position  on  the  transfer.  The  star-punch, 
with  its  picker,  die,  and  thimble,  are  seen  in  section,  full  size,  in  Fig.  3031. 

F',  die-bed  of  the  forming-punch.  This  is  round  and  has  a shank  passing  down  through  the  bench, 
to  which  it  is  fixed  by  a screw-nut  on  it  below ; through  the  axis  of  this  shank,  and  of  the  forming-die, 
operates  the  elevator  e.  In  a socket  in  this  bed  stands 

V',  the  forming-die ; its  upper  surface  is  on  a level  with  the  way  of  the  director  d T'".  This  die  is  seen 
in  section,  full  size,  in  Fig.  3032,  Y,  as  is  also 

Z Z',  the  forming-punch,  which  is  compound,  having  an  outer  shell  z,  which  planishes  the  flanch  of  the 
capsule,  and  an  internal  or  .centre  punch  Z',  which  forms  the  inside.  This  centre  punch  has  a shank 
passing  up  through  the  axis  of  the  shell  z,  and  is  secured  by  a cross-key  near  the  bottom,  or  by  a coun- 
tersunk nut  at  the  upper  end.  This  arrangement,  by  equalizing  the  thickness  of  the  several  parts, 
allows  a better  temper,  and  consequently  insures  a more  perfect  operation  and  more  durability. 

T T'T',  Fig.  3030,  three  views  of  the  transfer,  full  size.  T,  slide,  with  lower  face  upward ; b,  the  boss 
in  which  the  pin  i of  the  connecting-link  l works.  T'  shows  the  plate  and  link  in  profile,  and  T"  shows  it 
in  working  position  with  the  connecting-link  l attached  to  it,  slides  in  the  way  (groove)  of  the  director 
d T"'.  The  transfer  is  operated  by  the  lever  or  arm  t i applied  to  the  pintle  i.  It  will  be  seen  in  Figs 
3028  and  3029  that  the  director  d T",  Ac.,  with  its  transfer,  pass  through  the  bed  F of  the  star-die;  it 
passes  immediately  below  the  star-die  and  its  thimble,  in  order  that  the  star  may  fall  from  its  punch 
through  the  thimble  upon  the  transfer  slide. 

IT,  Fig.  3031,  the  star-punch.  This  punch,  with  its  picker,  and  the  star-die,  with  its  included 
thimble  are  shown,  full  size,  in  vertical  section,  where  q is  the  picker  with  its  spiral  spring  above 
it,  and  v v the  thimble.  The  office  of  the  picker  is  to  prevent  the  adhesion  of  the  stars  to  the  face  of 
the  punch. 

C C,  crank-arbor,  to  which  the  power  is  applied.  On  this  is  the  collar  and  flanch  D D,  on  which  is 
the  feed-cam  c,  which  operates  the  feed-lever  f,  and  through  the  double  hands  P P,  works  the  ratchets 


PERCUSSION-CAP  MACHINE. 


469 


r r of  the  feed-rollers.  Oil  the  opposite  face  of  this  collar  is  the  cam  c of  the  elevator  lever  E E,  which, 
through  the  rocking-arbor  E'  and  arm  a,  raises  the  elevator  e,  lifting  the  capsule  out  of  the  forming-die ; 
it  is  returned  by  the  spiral  spring  s ss,  Fig.  3028.  E"  is  the  anvil  on  which  the  elevator  rests  while  a 
capsule  is  being  pressed ; it  has  an  adjusting  screw  and  nut. 


G G,  &c.,  cam  lever  of  the  transfer  apparatus.  It  is  fast  on  its  axis  J J,  which  works  in  the  bracket 
II H,  <fcc.,  and  is  operated  by  the  cylinder  cam  I on  the  crank-arbor,  and  returned  by  a spiral  spring  on 
the  axis  J J.  The  lever  1 1 is  free  on  the  axis  J J,  but  is  constrained  to  move  in  concert  with  G,  by 
means  of  a spring,  which  allows  it,  together  with  the  transfer,  to  yield  to  extraordinary  resistance,  while 
the  cam  and  fast  lever  pursue  their  way  thus  preventing  injury  to  the  machine. 


470 


PERCUSSION-CAP  MACHINE. 


u is  the  gage,  a cap  of  steel  over  the  head  of  the  forming-die,  with  semicircular  notch  in  iis  edge 
against  which  the  star  is  driven  by  the  transfer  and  held  concentric  with  the  forming-die  until  seized  bj 
the  forming-punch. 

y y,  the  driver,  a slender  lever  suspended  by  its  upper  end  thrown  forward  by  a spring  y ; its  lower 
pnd  is  bent  forward  over  the  face  of  the  forming-die,  somewhat  in  form  of  a human  foot  and  leg,  Fig 


8029.  It  is  operated  by  a pin  in  the  runner  R'  pressing  against  a tumbler,  and  holding  it  behind  the 
punch  while  a capsule  is  being  formed,  and  releasing  it  instantly  when  the  capsule  is  raised  by  the  ele- 
vator above  the  gage  u. 

n n,  feed-rollers.  There  is  a similar  pair  behind  the  punch  to  continue  the  progress  of  the  ribbon  afte* 


PERCUSSION-CAP  CHARGING  MACHINE 


471 


it  has  passed  the  front  rollers,  m is  a lever  to  open  and  close  the  feed-rollers.  All  these  parts  arc 
attached  to  a movable  plate  K,  covering  the  front  of  the  bench  K,  Ac. 

Operation. — The  material  is  cut  in  ribbons  of  such  width  as  will  admit  of  two  rows  of  blanks  or  star- 
being  cut  from  each  lengthwise;  but  the  machine  may  be  so  constructed  without  departing  from  its 
principles  as  to  work  from  ribbons  of  any  width. 


One  end  of  a ribbon  being  inserted  between  the  feed-rollers  n n,  is  by  them  drawn  in,  while  a row  ot 
stars  is  successively  cut  near  one  edge  throughout  its  length.  When  not  enough  surface  remains  for 
another  star  or  trigger,  (not  shown,)  which  has  ridden  upon  its  surface,  drops  off  at  the  end,  and  by 
mechanical  connections  stops  the  machine.  Each  star,  as  soon  as  cut,  is  projected  by  the  picker  q down 
through  the  thimble  v v,  Fig.  3031,  upon  the  face  of  the  transfer,  which 
at  this  instant  is  holding  a previous  star  against  the  gage  u under  the 
forming-punch  z' ; on  its  return  its  operating  end  passes  beyond  the 
thimble,  which  consequently  sweeps  the  star  deposited  in  it  off  of 
the  transfer  into  the  way  of  the  director,  and  the  next  stroke  of  the 
transfer  drives  it  to  the  forming-die  while  another  star  is  being 
dropped  from  the  star-punch,  so  that  only  one  star  is  in  the  thimble 
at  the  same  time. 

While  the  forming-punch  rises  out  of  its  die,  the  elevator  c raises 
the  capsule  after  it  above  the  gage,  whence  the  driver  y kicks  it  into 
the  mouth  of  a receiving-tube,  (not  shown,)  which  conveys  it  to  the 
reservoir.  The  elevator  now  sinks,  the  driver  retires  behind  the 
punch,  and  all  is  clear  for  another  star. 

The  machine  is  a self-operator,  and  delivers  the  capsules  with  a 
high  finish  and  in  a state  proper  to  receive  the  priming. 

I do  not  claim  as  my  invention  punches  and  dies  for  making  per- 
cussion-caps, as  these  have  been  so  employed  in  various  ways ; but 
what  I do  claim  as  my  invention,  and  desire  to  secure  by  Letters 
Patent,  is  the  combination  and  arrangement  of  the  mechanism  above 
described  for  producing  the  combined  operations  herein  fully  set  forth, 
of  feeding  the  metallic  ribbon  to  the  star-die  U',  punching  the  blank 
from  the  ribbon,  transferring  the  blank  to  the  forming-die  V by  the  transferring  apparatus  TT'T"T" 
punching  the  blank  into  the  forming-die  V and  forming  it  into  a cap,  and  discharging  the  same  from  the 
die  by  the  elevator  e,  and  kicking  the  cap  in  a finished  state  from  the  die-bed  by  the  driver  Y.  All 
of  said  operations  being  performed  successively  at  every  revolution  of  the  crank  and  cam-arbor  c,  to 
which  the  propelling  power  is  applied,  substantially  as  above  described. 

2d.  I also  claim  the  transferring  apparatus  constructed  substantially  as  described,  in  combination 
with  the  punches. 

PERCUSSION  CAPS,  MACHINE  FOR  CHARGING— M.  W.  Fisher’s.  In  Fig.  3033,  the  mag- 
azine.  or  hopper,  in  which  the  fulminating  composition  is  placed,  is  supported  by  the  tremulous  base 
a rising  from  the  platform,  and  projecting  over  the  edge  of  the  horizontal  ratchet-wheel  A,  in  the 
Beties  of  vertical  apertures  near  the  periphery  of  which  the  caps  are  placed  to  receive  then-  charge 


3031.  3032. 


472 


PERCUSSION-CAP  CHARGING  MACHINE. 


The  lower  portion  of  the  magazine  is  funnel-shaped,  and  opens  into  a rectangular  tube  in  which  the 
charge  E is  accurately  fitted,  and  freely  slides  back  and  forth. 

A circular  aperture  is  formied  in  the  under  side  of  the  tube  at  the  distance  of  an  inch  or  two  from 
the  magazine,  exactly  corresponding  in  size  with  the  aperture  at  the  bottom  of  the  magazine,  ana 
with  the  aperture  in  the  charge  E. 

A reciprocating  movement  being  imparted  to  the  charger,  the  aperture  in  the  same,  in  passing  back 
and  forth  under  the  outlet  of  the  magazine,  will  receive  the  charge  of  composition  for  a cap  and  will  dis- 
charge the  same  as  the  charger  is  drawn  back  into  a cap  brought  immediately  under  the  aperture,  by 
the  movement  of  the  wheel  A upon  its  axis,  in  the  manner  hereinafter  set  forth. 

N is  the  main-shaft,  from  which  all  parts  of  the  machine  receive  motion.  Motion  is  imparted  to  tlio 


ratchet-wheel  A and  to  the  charger  E by  means  of  the  vibrating  lever  C,  suspended  by  and  vibrating 
on  the  arm  G'  projecting  from  the  end  of  the  machine,  the  cam  13  on  the  main-shaft,  the  cord  t con- 
nected to  the  upper  end  of  C and  passing  to  the  rear  over  a loose  pulley  on  the  axle  S',  and  sus- 
pending the  weight  T'  at  its  extremity.  A vertical  arm  F rises  from  the  front  end  of  the  charger  E, 
having  a vertical  slot  near  its  upper  end,  through  which  passes  an  adjustable  pin  projecting  from  the 
lever  0 by  which  it  is  operated.  A pivot  at  the  lower  extremity  of  the  lever  C takes  into  an  aper- 
ture in  the  ratchet  D,  which  communicates  motion  to  the  wheel  A.  The  ratchet  D works  in  the 
guiding-box  t , and  is  kept  in  contact  with  the  teeth  on  the  periphery  of  A by  the  spring  s'. 

The  cam  B is  of  such  a form  that  it  will  force  back  the  upper  end  of  the  lever  C,  and  thereby  will 
carry  forwards  the  ratchet  D and  the  charger  E,  and  move  the  periphery  of  the  wheel  A the  distance 


PERCUSSION-CAP  CHARGING  MACHINE. 


473 


of  the  length  of  a tooth,  and  in  that  position  will  retain  them  during  one-half  of  the  revolution  of  the 
main-shaft.  During  the  other  half  of  the  revolution  of  the  main-shaft,  the  periphery  of  the  cam  B 
ceases  to  press  back  the  upper  end  of  C,  and  receding  towards  the  shaft  permits  the  weight  T'  U 
draw  forwards  the  upper  end  of  C and  carry  back  the  ratchet  D and  the  charger  E.  The  charger,  iu 
passing  back  to  its  starting-place,  deposits  a charge  in  a cap,  as  before  described.  In  this  manner  the 
metallic  caps  placed  in  the  series  of  apertures  in  the  ratchet-wheel  A receive  their  respective  charges. 
The  apertures  in  A correspond  in  number  with  the  ratchet-teeth  on  its  periphery,  and  are  so  arranged 
that  each  forward  movement  of  the  ratchet  D will  place  one  of  the  apertures  in  A directly  under  the 
aperture  iu  the  tube,  in  which  the  charger  E traverses  back  and  forth,  as  before  described. 

'file  composition  is  forced  into  the  caps  in  the  following  manner : On  the  opposite  side  of  the  wheel 
A from  the  magazine  two  arms  project  from  the  standard  A",  which  arms  embrace  journals  at  the 
ends  of  a vertical  tube  R.  The  tube  R serves  as  a guide  and  supporter  to  the  shaft  of  the  punch  which 
forces  the  composition  into  the  caps.  The  shaft  is  composed  of  two  cylindrical  parts,  which  rotate  with 
and  play  freely  up  and  down  in  the  tube  R.  The  respective  parts  of  the  shaft  are  connected  to  each 
other  and  to  the  tube  R.  c c are  arms  secured  to  the  inner  ends  of  the  respective  parts  of  the  shaft, 
projecting  out  through  vertical  slots  in  the  sides  of  the  tube.  The  extremities  of  the  arms  c c are 
connected  to  each  other  by  the  screw  bolts  or  rods  b b ; the  blank  portion  of  the  bolts  play  freely  in 
the  apertures  in  the  arm  c through  which  they  pass. 

A stiff  and  powerful  helical  spring  embraces  the  middle  portion  of  the  tube  R,  the  ends  of  which 
bear  against  the  arms  cc  within  the  bolts  b b.  A ring  a loosely  encircles  the  lower  end  of  tube  R;  y 
is  a helical  spring  encircling  the  lower  end  of  the  tube  between  the  lower  supporting  arm  and  the  ring  a, 
which,  acting  against  the  lower  arm  c,  forces  up  the  punch-shaft. 

A rotary  motion  is  imparted  to  the  tube  It  and  the  punch  by  means  of  the  bevel-pinion,  made  fast  to 
the  upper  end  of  R,  and  working  into  a bevel  cog-wheel  0 on  the  main-shaft.  The  punch  is  of  such  a 
shape  as  to  tit  accurately  into  the  caps : the  wheel  A in  depth  exactly  corresponds  with  the  depth  of 
the  caps ; the  wheel  A revolves  upon  a journal  g made  fast  to  the  platform,  and  passing  up  through 
its  centre.  The  edge  of  the  wheel  immediately  under  the  punch  passes  over  and  slightly  rests  upon 
the  surface  of  a metallic  block. 

S is  a cam  on  the  main-shaft,  immediately  over  the  shaft  of  the  punch ; the  cam  S is  of  such  a form 
that  it  will  press  down  and  have  a continuous  action  upon  the  punch  during  about  three-fourths  of  the 
revolution  of  the  main-shaft.  The  cam  S strikes  against  the  upper  end  of  the  punch-shaft,  and  forces 
down  the  same,  pressing  the  punch  with  great  force  into  a cap,  immediately  after  the  cam  B has  acted 
on  the  lever  C,  the  ratchet  D,  the  charger  E,  and  wheel  A,  as  before  described  ; during  the  time  that 
the  punch  is  pressed  upon  the  composition  in  a cap,  four  revolutions,  more  or  less,  are  imparted  to  the 
punch  by  means  of  the  guiding-tube  R,  the  pinion  P,  and  cog-wheel  O,  which  perfects  the  solidification 
of  the  composition,  and  gives  it  the  requisite  adhesion  to  the  caps. 

During  the  action  of  the  punch  the  ratchet  D and  the  charger  E are  drawn  back  by  the  lever  C and 
weight  T',  and  immediately  thereafter  the  form  of  the  cam  S allows  the  sjjring  y,  on  the  lower  portion 
of  R,  to  elevate  the  punch  out  of  the  cap,  and  retain  it  in  an  elevated  position  while  the  cam  B and 
lever  C again  operate  upon  the  ratchet  D,  charger  E,  and  wheel  A,  as  before  described.  It  will  be 
perceived  that  the  pressure  exerted  upon  the  upper  portion  of  the  punch-shaft  is  communicated  to 
the  lower  portion  of  the  same  and  to  the  punch  through  the  medium  of  the  spring.  The  object  of  this 
arrangement  is  to  give  an  elastic  bearing  of  the  punch  upon  the  composition  in  the  cap,  so  that  should 
it  explode  from  any  cause  the  punch  can  yield  and  give  back,  and  no  injury  will  be  done  to  the  ma- 
chine or  attendant. 

The  cam  T,  on  the  main-shaft,  is  placed  immediately  over  and  operates  upon  the  rod  U as  follows . 
the  cam  T is  of  such  a form  as  to  cause  the  rod  U to  descend  simultaneously  with  the  punch,  forcing 
the  gagged  under  surface  of  an  arm  upon  the  flanch  of  the  cap,  which  retains  the  same  and  prevents 
the  cap  from  turning  while  the  punch  is  operating : the  cam  T also  retains  the  arm  upon  the  flanch  of 
the  cap  till  the  punch  is  elevated,  and  then  allows  the  retaining  arm  to  be  elevated  by  the  spring 
encircling  U,  to  allow  motion  to  be  imparted  to  the  wheel. 

The  caps  are  thrown  out  of  the  apertures  in  the  wheel  A after  the  operation  of  charging  before 
described,  by  the  following  described  arrangement  of  parts,  viz. : A cap  horizontal  tilting-lever  is  jointed 
to  a fulcrum  standard,  the  extremity  of  which  farthest  from  its  fulcrum  joint  terminates  in  an  'upright 
punch ; the  opposite  end  of  it  supports  the  vertical  rod  X,  which  passes  up  through  guiding  apertures 
in  arms  projecting  from  the  standard  AT  A spring  y acts  against  the  under  side  of  the  shortest  portion 
of  the  lever  and  sustains  the  rod  X.  W is  a wheel  on  the  main-shaft,  from  the  periphery  of  which 
projects  the  tilting-tooth  e ; as  the  main-shaft  is  revolved  the  tooth  e will  strike  against  the  top  of  the 
rod  X and  cause  it  to  tilt  the  lever  at  the  moment  when  the  wheel  A is  stationary  ; the  tilting  ot 
the  lever  brings  the  punch  against  the  bottom  of  a cap,  and  throws  it  out  of  its  aperture  in  the  wheel ; 
as  the  cap  is  thrown  upwards  the  spring  R'  gives  it  a lateral  direction,  and  conducts  it  into  the  funnel  Q’ 
open  at  the  side,  to  which  a tube  may  be  connected  to  convey  the  caps  to  a drawer,  or  other  suitable 
receptacle. 

The  metallic  caps  may  be  placed  in  the  apertures  in  the  wheel  A by  hand,  or  by  the  arrangement 
of  the  following  described  parts,  viz. : I”  is  a hopper  in  which  the  caps  are  placed  preparatory  to  their 
being  deposited  in  the  apertures  in  A by  machinery  ; the  caps  fall  from  the  vibrating  shoe,  at  the 
base  of  the  hopper,  into  an  inclined  vibrating  groove — the  tubular  portion  of  the  caps  passing  into  the 
groove,  and  the  flanehes  resting  upon  the  sides  of  the  same.  The  periphery  of  the  rotating  brush  H' 
comes  so  nearly  in  contact  with  the  sides  of  the  groove  as  to  prevent  the  caps  from  passing  the  same 
unless  their  tubes  are  inserted  in  the  groove.  The  inclined  groove  is  secured  by  a pivot  at  its  lower 
end,  and  its  upper  end  slides  freely  on  a supporting  bar.  The  shoe  and  the  inclined  groove  are 
vibrated  by  means  of  a connection  with  the  ratchet  teeth  on  the  axle  of  the  brush  H'  by  any  usual  or 
suitable  contrivance.  As  the  groove  is  vibrated,  the  caps  are  carried  down  the  steepest  portion  of  the 


474 


PERPETUAL  MOTION. 


same ; the  feeding-hand  on  the  front  end  of  the  arm  I is  then  placed  upon  them,  and  draws  their 
down  the  groove  until  the  foremost  one  is  caught  between  the  scolloped  edged  wheels  n n,  located  on 
each  side  of  and  projecting  into  the  groove.  The  concavities  in  the  peripheries  of  n n are  arcs  cor- 
responding with  the  tubes  of  the  caps,  and  embrace  nearly  their  entire  circumference  when  the  caps 
are  drawn  between  them.  One  of  the  wheels  n plays  freely  on  its  axis ; the  points  radiating  from  the 
other  wheel  n are  operated  upon  by  a retaining  spring.  The  spring  partially  retains  the  wheel  n,  on 
which  it  acts.  As  the  caps  are  drawn  down  the  groove,  should  the  foremost  one  strike  against  a 
ladiating  point  of  the  loose  wheel  n,  it  will  revolve  the  same  sufficiently  to  bring  the  cap  between 
opposite  concavities  of  both  wheels.  The  elastic  feeding-finger,  connected  to  the  front  end  of  the 
arm  J,  is  so  operated  that  it  is  placed  in  a cap  while  it  (the  cap)  is  retained  between  the  wheels  n n, 
and  draw's  it  forwards  and  deposits  it  in  an  aperture  in  the  wheel  A.  As  the  cap  is  drawn  from 
between  the  wheels  nn  it  causes  a partial  revolution  of  the  wheels  ; the  spring  passes  over  a radiating 
point  in  one  of  the  wheels,  and,  striking  on  the  next  point  in  succession,  retains  the  wheel  in  the 
proper  position  for  the  reception  of  another  cap. 

The  feeding-hand  on  the  front  end  of  the  arm  I has  a soft  face  that  rests  but  slightly  upon  the 
flanches  of  the  caps ; the  front  end  of  the  arm  I,  when  the  hand  is  acting  upon  the  caps,  rests  upon 
the  roller  which  traverses  upon  the  edges  of  the  groove.  The  feeding-finger  passes  through  an  aper- 
ture and  is  secured  to  the  spring-plate  projecting  from  the  under  side  of  the  front  end  of  the  arm  J ; it 
is  steadied  and  kept  in  a vertical  position  by  passing  loosely  through  the  plate  projecting  from  the 
upper  side  of  the  front  end  of  J,  and  to  give  additional  elasticity  to  the  finger  it  is  inclosed  in  a 
helical  spring.  The  arms  I and  J are  jointed  to  and  receive  motion  from  the  upright  vibrating 
levers  I'J' ; the  levers  I' J'  are  jointed  to  and  suspended  by  the  curved  standard  K;  the  standard  K 
rises  from  the  rear  side  of  the  platform,  curves  forwards  over  the  centre  of  wheel  A,  and  descends 
vertically  to  the  top  of  the  axle  g,  to  which  it  is  connected.  To  the  upper  ends  of  the  levers  I'  J'  the 
cords  s s are  connected,  which  pass  to  the  rear  over  loose  pulleys  on  the  axle  S',  and  suspend  the  weights 
LT  U'  at  their  extremities : causing  the  upper  end  of  I'  to  bear  against  the  cam  L,  and  the  upper  end 
of  J'  to  bear  against  the  cam  M on  the  main-shaft. 

II  is  a vertical  vibrating-lever,  placed  in  the  guiding-box  u',  and  working  on  a joint-pin  passing  through 
the  sides  of  the  same. 

Angular  arms/ and  g project  from  the  upper  portion  of  H ; the  angular  extremity  of/  passes  to  the 
right  over  the  arms  I J,  the  extremity  of  g passes  to  the  right  under  the  arms  I J.  G is  a horizontal 
vibrating-lever  jointed  to  the  standard  e'.  The  end  of  G,  to  the  right  of  the  standard  e',  passes  immedi- 
ately in  front  of  the  lower  cord  of  the  lever  H ; the  opposite  end  of  G turns  at  right  angles  to  the  rear, 
and  is  brought  directly  opposite  and  in  contact  with  the  head  of  the  ratchet  D. 

When  the  ratchet  D is  drawn  back  by  the  lever  C,  it  vibrates  the  lever  G,  causing  it  to  throw  back 
the  upper  end  of  H,  and  thereby  to  elevate  the  front  ends  of  the  arms  I J by  the  arm  g at  the  moment 
that  the  arms  I J are  elevated.  The  form  and  position  of  the  cams  L M permit  the  weights  U'  U'  to 
draw  the  upper  ends  of  the  levers  I'J'  to  the  rear,  and  carry  the  arms  I J forwards  ; the  moment  the 
ratchet  D is  carried  forwards  again,  the  arms  I J descend,  placing  the  hand  h upon  the  flanches  of  the 
caps  in  the  groove  P',  and  the  finger  k in  the  cap  held  between  the  concavities  of  the  wheels  n n,  as 
before  described.  As  soon  as  the  arms  I J descend,  the  cams  LM  commence  acting  upon  the  levers 
I'  J'  and  arms  I J,  causing  the  hand  to  carry  forward  the  caps  in  the  groove,  and  the  finger  to  place  a cap 
in  an  aperture  in  the  wheel  A,  as  before  described.  The  moment  after  the  finger  has  deposited  a cap 
in  an  aperture  in  A,  the  arms  I J are  again  elevated  and  carried  to  the  front  in  the  manner  before  de- 
scribed. 

The  rotating  brush  H'  is  driven  by  the  band  passing  around  a pulley  on  the  main-shaft  N.  The 
rotating  brush  in  the  rear  portion  of  the  machine  acts  upon  the  upper  surface  of  the  wheel  A near  its 
periphery,  for  the  purpose  of  removing  any  of  the  percussion  composition  that  may  chance  to  be  deposited 
upon  the  wheel  or  flanches  of  the  caps.  This  brush  is  driven  by  a band  passing  around  a pulley  on  the 
main-shaft. 

PERPETUAL  MOTION.  In  mechanics,  a machine  which,  when  set  in  motion,  would  continue  to 
move  forever,  or,  at  least,  until  destroyed  by  the  friction  of  its  parts,  without  the  aid  of  any  exterior 
cause.  The  discovery  of  the  perpetual  motion  has  always  been  a celebrated  problem  in  mechanics,  on 
which  many  ingenious,  though  in  general  ill-instructed,  persons  have  consumed  their  time  ; but  all  the 
labor  bestowed  on  it  has  proved  abortive.  In  fact,  the  impossibility  of  its  existence  has  been  fully  de 
monstrated  from  the  known  laws  of  matter. 

In  speaking  of  the  perpetual  motion,  it  is  to  be  understood  that  from  among  the  forces  by  which 
motion  may  be  produced  we  are  to  exclude  not  only  air  and  water,  but  other  natural  agents,  as  heat, 
atmospheric  changes,  <tc.  The  only  admissible  agents  are  the  inertia  of  matter,  and  its  attractive 
forces,  which  may  all  be  considered  of  the  same  kind  as  gravitation. 

It  is  an  admitted  principle  in  philosophy  that  action  and  reaction  are  equal,  and  that,  when  motion  is 
communicated  from  one  body  to  another,  the  first  loses  just  as  much  as  is  gained  by  the  second.  But 
every  moving  body  is  continually  retarded  by  two  passive  forces,  the  resistance  of  the  air  and  friction 
In  order,  therefore,  that  motion  may  be  continued  without  diminution,  one  of  two  things  is  necessary — 
either  that  it  be  maintained  by  an  exterior  force,  (in  which  case  it  would  cease  to  be  what  we  under- 
stand by  a perpetual  motion,)  or  that  the  resistance  of  the  air  and  friction  be  annihilated,  which  is 
physically  impossible.  The  motion  cannot  be  perpetuated  till  these  retarding  forces  are  compensated, 
and  they  can  only  be  compensated  by  an  exterior  force ; for  the  force  communicated  to  any  body  can- 
not be  greater  than  the  generating  force,  and  this  is  only  sufficient  to  continue  the  same  quantity  of 
motion  when  there  is  no  resistance.  To  find  the  perpetual  motion  is,  therefore,  a proposition  equivalent 
to  this — to  find  a force  (either  an  attractive  force  like  that  of  gravitation  or  magnetism,  or  an  elastic 
force,  that  of  a spring,  for  example)  greater  than  itself 

But  it  may  be  argued  that,  by  some  arrangement  or  combination  of  mechanical  powers,  a force  may 


PILE-DRIVER. 


475 


oe  gained  equal  to  that  which  is  lost  in  overcoming  friction  and  atmospheric  resistance.  This  motion 
at  first  mention  appears  plausible,  and  is,  in  feet,  that  by  which  most  spectators  have  been  led  astray. 
It  is,  however,  entirely  erroneous ; for  by  no  multiplication  of  forces  or  powers  by  mechanical  agents 
can  the  quantity  of  motion  be  increased.  Whatever  is  gained  in  power  is  lost  in  time ; the  quantity  ol 
motion  transmitted  by  the  machine  remains  unaltered. 

PERSIAN  WHEEL.  In  mechanics,  a contrivance  for  raising  water  to  some  height  above  the  level 
of  a stream.  In  the  rim  of  a wheel  turned  by  the  stream  a number  of  strong  pins  are  fixed,  from 
which  buckets  are  suspended.  As  the  wheel  turns,  the  buckets  on  one  side  go  down  into  the  stream, 
where  they  are  filled,  and  return  up  full  on  the  other  side  till  they  reach  the  top.  Here  an  obstacle  is 
placed  in  such  a position  that  the  buckets  successively  strike  against  it  and  are  overset,  and  the  water 
emptied  into  a trough.  As  the  water  can  never  be  raised  by  this  means  higher  than  the  diameter  of 
the  wheel,  it  is  obvious  that  this  rude  machine  is  capable  of  only  a very  limited  application.  Sometimes 
the  wheel  is  niade  to  raise  the  water  only  to  the  height  of  the  axis.  In  this  case,  instead  of  buckets, 
tlie  spokes  are  made  hollow,  and  bent  into  such  a form  that  when  they  dip  into  the  water  it  runs  into 
them,  and  is  thus  conveyed  to  a box  on  the  axle,  whence  it  is  emptied  into  a cistern.  Such  wheels  are 
in  common  use  on  the  banks  of  the  Nile,  and  elsewhere. 

PHOTOGRAPHY.  Photography,  or  sun-painting,  is  divided,  according  to  the  methods  used  to  pro- 
duce the  picture,  viz. — Daguerreotype,  Calotypc,  Chrysotype,  Cyanotype,  Chromotype,  JSnergiatype,  An- 
thotype,  and  Amphitypc. 

The  principal  instrument  used  in  the  Daguerreotype  process  is  the  camera  obscura,  and  the  images 
from  the  lenses  are  thrown  on  prepared  metal  or  other  surfaces  and  fixed.  The  processes  for  the  reten- 
tion of  the  picture  belong  rather  to  chemical  than  mechanical  science.  This  art  is  frequently  employed 
by  mechanics  and  architects  in  making  copies  of  drawings.  See  Cyclopedia  of  Drawing. 

PHOTOMETER.  An  instrument  for  measuring  the  intensity  of  light,  or  of  illumination. 

PILE-DRIVER — Nasmyth's  patent  steam.  This  is  a machine  of  great  power,  and  one  destined  un- 
doubtedly to  take  a prominent  place  among  the  improvements  of  the  age. 

Fig.  3034  is  a front  elevation  of  the  entire  machine,  shown  in  full  operation  driving  a pile. 

Fig.  3035  is  a corresponding  general  side  elevation. 

Fig.  3036  is  a general  sectional  plan  of  the  machine. 

Fig.  3037  is  a transverse  section  of  the  stage  or  platform,  taken  on  the  line  1 — 2,  in  Fig.  3036. 

Fig.  3038,  an  enlarged  elevation  of  the  steam-chest  and  safety-valve  geer. 

Fig.  3039,  a section  corresponding  to  the  above. 

Fig.  3040  is  an  enlarged  section  of  one  of  the  joints  of  the  flexible  steam-pipes,  for  conveying  steam 
to  the  hammer-cylinder. 

Fig.  3041,  a plan  corresponding  to  the  above. 

Fig.  3042,  a sectional  elevation  of  the  hammer-cylinder  and  pile-case  with  all  their  appendages.  In 
this  view  the  hammer  is  supposed  to  have  just  effected  a blow  upon  the  head  of  the  pile,  and  the  vari- 
ous parts  of  the  valve-geer  are  represented  in  the  positions  they  occupy  at  the  commencement  of  a fresh 
stroke. 

Fig.  3043,  a front  view  of  the  hammer-cylinder  and  pile-case,  witli  their  various  attachments. 

Fig.  3044,  a sectional  elevation  of  the  same  parts  as  are  represented  in  Fig.  3042,  with  the  driving 
apparatus  and  valve-geer  shown  in  the  positions  they  occupy  when  the  hammer  is  about  to  fall. 

Figs.  3045  and  3046,  enlarged  views  of  the  trigger  and  parallel  motion  of  the  valve-geer  detached. 
These  views  are  drawn  to  a scale  of  twice  the  size  of  the  other  figures. 

Fig.  3047  is  a section  of  the  hammer-block  and  hammer. 

Fig.  3048  is  a sectional  plan  of  the  pile-case,  taken  on  the  line  3 — 4,  in  Fig.  3043. 

Fig.  3049,  a sectional  plan  of  the  pile-case  and  hammer-block,  taken  on  the  line  5 — 6,  in  Fig.  3042. 

General  description. — There  are  two  important  features  of  novelty  .which  serve  to  distinguish  the 
datent  Steam  Pile-Driving  Engine  from  all  such  as  had  previously  been  employed  for  the  same  pur- 
pose. These  consist : First,  in  the  direct  manner  in  which  the  steam  is  employed  as  the  agent  by  which 
the  block  of  iron  which  strikes  the  head  of  the  pile  is  raised  to  the  required  height ; and,  Secondly,  in 
the  peculiar  mode  in  which  the  pile,  while  being  driven  into  the  ground,  is  employed  to  support 
that  part  of  the  apparatus  which  is  directly  concerned  in  driving  or  forcing  it  into  the  soil — the  appara- 
tus in  question  being  so  contrived  that,  as  the  pile  penetrates  into  the  ground,  the  superincumbent  ma- 
chinery shall  follow  down  with  it  until  it  has  reached  the  required  depth. 

By  the  peculiar  arrangement  referred  to  under  the  second  head,  we  secure  two  most  important  prac- 
tical advantages : First,  the  piles  are  guided  throughout  their  entire  course  with  the  utmost  accuracy 
and  precision,  so  that  no  one  shall  twist  or  swerve  in  the  slightest  degree  from  the  general  line,  or  from 
the  position  in  which  it  is  set  at  the  commencement  of  the  driving  process,  this  object  being  attained 
without  any  sacrifice  of  power  from  the  friction  of  bands,  or  other  appliances  usually  employed  for  that 
purpose ; and,  Secondly,  the  entire  dead  weight  of  the  driving  apparatus  is  brought  into  effective  action 
to  second  and  follow  up  the  blow  last  inflicted  upon  the  head  of  the  pile.  This  last  peculiarity  of  ac- 
tion constitutes  one  of  the  most  important  features  of  the  machine,  and  has  contributed  very  materially 
to  the  success  which  has  attended  its  use.  During  the  brief  intervals  between  the  blows,  (70  to  80  per 
minute,)  the  pile  is  urged  continuously  downward  by  the  action  of  the  force  here  adverted  to,  so  that  it 
may  be  said  to  be  in  a state  of  constant  motion  from  the  commencement  to  the  termination  of  the  driv- 
ing, and  thus  the  power  which  would  otherwise  be  wasted  in  overcoming  its  inertia  is  profitably  ex- 
pended in  forcing  it  further  into  the  soil. 

The  basis  or  foundation  on  which  the  entire  machine  is  erected,  consists  of  a strong  wooden  stage  oi 
platform  A A,  firmly  framed  together  and  strengthened  by  diagonal  timbers,  and  wrought-iron  corner- 
pieces,  the  whole  being  further  secured  by  the  massive  cast-iron  brackets  B B,  at  each  angle  of  the  plat- 
form, in  which  the  locomotive  wheels  aaaa  are  fitted  to  work  upon  rails  disposed  parallel  and  close 
to  the  line  of  piling  on  which  the  machine  is  destined  to  operate.  The  stage  is  made  of  sufficient  dimen 


476 


PILE-DRIVER. 


sions  and  weight  to  give  the  requisite  stability  and  firmness  to  the  entire  structure,  and  to  afford  room 
for  the  steam-boiler,  the  workmen,  and  all  that  is  necessary  for  the  accomplishment  of  the  proposed 
object.  The  great  vertical  guide-pole  C C,  on  which  the  driving  apparatus  slides,  is  securely  bolted  tc 
one  side  of  the  platform,  the  boiler  being  situated  towards  the  opposite  side,  to  counterbalance  tlic 
weight  of  the  former,  and  to  afford  an  abutment  for  the  diagonal  timber  supports  D D,  firmly  bound  to 
both  by  plates  of  iron  and  numerous  bolts;  the  entire  frame  work  of  the  machine  is  further  secured  by 
the  four  adjustable  tie-rods  or  stays  bbbb,  attached  to  the  four  corners  of  the  stage  and  to  the  top  of 


the  upright.  This  latter  is  surmounted  by  a cast-iron  socket-frame,  supporting  the  brackets  E E,  which 
carry  a chain-pulley,  over  which  works  the  great  chain  c c,  one  end  of  which  is  passed  round  a barrel 
worked  by  a small  steam-engine,  as  will  be  hereafter  described,  while  the  other  end  is  attached  to,  and 
sustains  the  weight  of,  the  pile-driving  apparatus. 

This  consists  of  a steam-cylinder  F,  with  all  the  necessary  appendages  of  piston,  valves,  ifcc.,  as  will 
be  more  particularly  specified  below  ; the  lower  flange  of  the  cylinder  is  firmly  bolted  to  the  pile-cane 


PILE-DRIVER. 


477 


G G,  which  is  a species  of  rectangular  box  of  a square  section,  constructed  of  plates  of  wrought-ircn, 
strongly  framed  together  in  the  manner  indicated  in  the  detail  views.  The  interior  surfaces  of  the  pile- 
case  serve  to  guide  the  hammer-block  in  its  vertical  motion,  and  it  is  itself  guided  along  the  great  up- 
right C 0,  by  the  pieces  del , which  are  fitted  to  embrace  the  projecting  slips  of  iron  c e,  bolted  to  the 
front  of  the  upright  throughout  its  entire  length.  The  lower  end  of  the  pile-case  is  open,  to  admit  the 
head  of  the  pile,  and  is  furnished  with  cast-iron  jaws  or  resting-pieces//  (see  Figs.  3042  and  3044.) 
bolted  to  its  interior  surfaces ; these  are  so  formed  as  to  rest  upon  the  shoulders  ot  the  pile  H,  which, 
if  we  suppose  the  great  chain-barrel  to  be  left  free  to  revolve,  thus  becomes  the  sole  support  for  the 
weight  of  the  whole  mass  of  the  driving  apparatus.  By  these  arrangements  it  will  be  seen  that  as  the 
pile  is,  by  successive  steps,  forced  into  the  ground  by  the  action  of  the  hammer,  (the  chain-barrel  being 
thrown  out  of  geer  with  its  driving  apparatus  during  the  process,)  the  pile-case  with  all  its  appendages, 
weighing  about  three  tons,  is  left  at  perfect  liberty  to  bear  upon  the  shoulders  of  the  pile,  and  follow 
down  along  with  it,  while  at  the  same  time,  and  by  the  same  means,  the  pile  itself  is  guided  into  a 
strictly  vertical  and  true  course. 


3030. 


The  driving  apparatus  consists  simply  of  a modification  of  his  steam-hammer,  the  action  of  the  vari- 
ous parts  being  in  all  respects  identical,  though  the  whole  is  movable,  as  above  described,  instead  of 
being  fixed.  The  steam  necessary  for  its  supply  is  generated  in  a boiler  I,  the  construction  of  which  is 
very  similar  to  that  of  the  ordinary  locomotive  engine  boiler.  The  steam-chest  J surmounts  the  fire- 
box, and  is  made  of  sufficient  height  to  prevent  the  influx  of  water  into  the  steam-pipes,  and  the  entire 
boiler  and  steam-chest  are  covered  externally  with  a coating  of  felt,  and  with  strips  of  wood  to  prevent 
the  radiation  of  heat,  and  to  give  greater  symmetry  of  appearance.  On  the  cover  of  the  steam-chest 
(the  internal  construction  of  which  is  fully  shown  in  Fig.  3039)  is  cast  a small  square  box  g , containing 
suitable  bearings  for  the  safety-valve,  which  is  loaded  by  a weight  and  combination  of  levers  h h li,  and 
for  the  throttle  or  shut-off  valve,  commanded  by  the  lever-handle  and  rod  i i.  The  steam  is  conveyed 
from  the  boiler  to  the  valve-chest  of  the  driving-cylinder,  by  a flexible  steam-pipe  K K,  composed  of 
several  lengths  of  wrought-iron  tube,  connected  together  by  swivel  joints  of  cast-iron  jjj,  the  construc- 
tion of  which  will  be  fully  understood  by  reference  to  Figs.  3040  and  3041.  This  arrangement  admits 
of  the  steam-pipe  accommodating  itself,  without  any  loss  of  steam  from  leakage,  to  every  variety  of 
height  or  distance  at  which  the  driving  cylinder  may  be  from  the  boiler,  from  the  commencement  of 
the  process,  when  the  apparatus  is  sitting  aloft  upon  the  shoulders  of  a tall  pile,  until  it  has  arrived  at 
its  lowest  position,  when  the  pile  has  penetrated  the  soil  to  the  required  depth. 

The  remaining  part  of  the  driving  apparatus  is  identical  in  the  principles  of  its  action,  and  very  sum- 


478 


PILE-DRIVER. 


lar  in  the  details  of  its  construction  to  those  of  the  direct  action  steam-hammer.  For  fuller  informatioc 
on  these  points,  see  Steam-Hammer. 

F is  the  steam-cylinder,  within  which  the  power  necessary  for  raising  the  hammer  to  the  required 
elevation  (three  feet)  is  generated. 

L,  the  steam-valve  chest,  bolted  to  the  lower  side  of  the  cylinder,  within  which  the  valve  k is  fitted 
to  work  upon  a face  cast  with  the  cylinder.  The  steam,  after  having  accomplished  its  work,  is  permit- 
ted to  escape  into  the  atmosphere  by  an  oblong  aperture  l,  formed  in  the  cylinder-face ; and,  to  obviate 
the  risk  of  accident  from  the  piston  rising  too  high,  a number  of  small  round  holes  m m are  formed  near 


3044.  3043.  3042. 


the  top  of  the  cylinder,  so  that  the  steam  may  blow  out  into  the  air  wneu  the  piston  nses  above  their 
edges.  It  may  here  be  remarked  that  the  efficacy  of  the  blows  of  the  hammer,  and  the  security  from 
damage  to  the  parts  of  the  machinery,  are  in  this  case,  as  in  that  of  the  steam  forge-hammer,  materially 
augmented  by  the  recoil  of  the  air  or  steam  inclosed  above  the  piston. 

M,  the  piston, -formed  of  wrouglit-iron,  and  fitted  with  a single  packing-ring. 

N the  piston-rod,  having  a cylindrical  boss  or  enlargement  n , at  its  lower  extremity,  for  the  purpose 


PILE-DRIVER. 


479 


of  affording  means  for  securing  a slightly  elastic  connection,  by  hard-wood  washers,  between  the  piston- 
rod  and  hammer-block. 

O,  the  hammer-block,  consisting  of  a rectangular  mass  of  cast-iron,  weighing  30  cwt.,  adapted  to  slide 
freely  but  without  much  play,  within  the  pile-case  G G.  It  is  furnished  with  suitable  recesses  for  the 
securing  of  the  hammer,  piston-rod,  &c.,  and  for  enabling  it  to  rise  clear  of  the  cylinder  stuffing-box ; 
and  at  its  upper  extremity  a recess  in  the  form  of  a species  of  inclined  plane  o'  o',  is  provided,  for  the 
purpose  of  acting  upon  the  valve-lever  so  as  to  permit  the  escape  of  the  steam,  after  it  has  raised  the 
hammer  to  a sufficient  height. 

P,  the  hammer:  a cylindrical  block  of  cast-iron,  formed  with  a slightly  concave  face,  fitted  into  the 
hammer-block,  and  fastened  thereto  by  a wrought-iron  key  o,  which  at  the  same  time  serves  to  secure 
the  connection  of  the  piston-rod. 

Q,  the  latch-lever  working  in  a recess  in  the  hammer-block,  (see  Fig.  3049.)  The  action  of  this  part 
of  the  apparatus  is  fully  described  in  the  account  of  the  steam-hammer. 

p,  a small  solid  piston  working  in  a cylindrical  part  of  the  valve-chest,  and  attached  to  the  valve  by 
a short  connecting-rod.  Its  under  surface  is  constantly  .acted  upon  by  the  pressure  of  the  steam  within 
the  valve-chest,  so  as  to  cause  the  steam-valve  to  assume  the  position  indicated  in  Fig.  3042,  unless 
counteracted  by  a superior  force. 

q,  the  valve-*spindle,  produced  downwards  and  working  in  suitable  bearings,  so  as  to  bring  it  under 
the  action  of  the  trigger  at  the  termination  of  the  stroke. 


r,  the  valve-lever,  working  outside  of  the  pile-case,  but  having  a small  friction-roller  attached  to  its 
inner  end,  and  situated  so  as  to  come  under  the  action  of  the  inclined  plane  o'  oo". 

s,  the  trigger,  the  function  of  which  is  to  keep  the  steam-valve  in  such  a position  as  to  prevent  the 
admission  of  steam  into  the  cylinder  during  the  descent  of  the  hammer-block. 

t,  the  parallel  bar,  against  which  the  latch-lever  acts  at  the  termination  of  the  stroke,  for  the  purpose 
of  releasing  the  valve-spindle  from  the  trigger,  in  order  to  allow  the  steam  to  be  admitted  for  a fresh 
stroke. 

u u u,  the  parallel  motion  bell-cranks  and  connecting-rod  of  the  disengaging  apparatus. 

v,  a buffer-box  for  the  purpose  of  restricting  the  travel  of  the  valve  to  its  proper  amount,  and  of  dead- 
ening the  shocks  to  which  it  is  subjected. 

The  above  enumeration,  together  with  the  explanations  previously  given,  will  convey  a sufficiently 
clear  idea  of  the  construction  of  the  pile-driving  apparatus,  properly  so  called.  We  shall  now  proceed  to 
describe  the  mechanism  by  which  the  pile-case  and  its  appendages  are  elevated  to  the  top  of  the  great 
vertical  guide-pole,  and  the  means  employed  to  render  the  whole  machine  locomotive. 

The  power  requisite  for  these  purposes  is  supplied  by  a small  horizontal  steam-engine  It,  situated 
opposite  to  the  great  upright  C,  and  under  the  boiler  I,  from  which  it  derives  its  supply  of  steam.  The 
motion  of  this  steam-engine  is  transferred  to  the  axis  of  the  great  chain-barrel  by  means  of  a train  of 
spur-geering  calculated  to  increase  the  power  to  the  required  extent.  Two  broad  plates  of  wrought- 
iron,  extending  across  the  entire  platform,  and  bolted  securely  to  its  timbers,  afford  a sufficiently  firm 
foundation  for  the  engine,  and  for  the  bearings  of  the  various  shafts  in  the  train  of  wheels,  which  con- 
sists of  three  pairs  marked  w,  x , and  y,  the  pinion  of  the  first  pair  being  fixed  upon  the  crank-shaft  of 
the  engine,  and  the  wheel  of  the  last  upon  the  axis  of  the  chain-barrel.  The  pinion  y is  fitted  to  slide 
ongitudinally  upon  its  shaft  by  means  of  a sunk  feather,  and  is  commanded  by  the  lever-handle  z so  as 
to  enable  the  attendant  in  charge  of  the  machine  to  throw  it  out  of  geer  with  the  wheel  upon  the  chain- 
barrel  shaft,  when  the  latter  is  to  be  left  free  to  revolve  during  the  driving  of  the  pile.  The  wheel  x, 
upon  the  third  motion  shaft,  geers  with  a similar  wheel  a,  fixed  upon  a cross-shaft  T,  working  in  bear- 
ings  under  the  platform,  and  serving  to  impart  motion  at  once  to  the  small  chain-barrel  b'  for  hoisting 

e piles,  and  to  the  locomotive  geer.  A clutch,  or  coupling  c,  sliding  upon  the  shaft  T,  enables  the 


480 


PILE-DRIVER— AMERICAN. 


attendant  to  throw  the  small  chain-barrel  into  geer  with  the  driving  apparatus  or  disengage  it  at 
pleasure  ; the  remaining  details  of  this  part  of  the  process  will  be  fully  understood  by  reference  to  Fig. 
3034,  where  ».  pile  H'  is  shown  suspended  from  the  chain  d',  ready  to  come  under  the  action  of  the 
driving  machinery.  To  adjust  the  pile-case  over  the  head  of  the  pile  at  the  commencement  of  the 
driving,  it  is  of  course  necessary  that  one  or  two  men  should  be  raised  to  the  summit  of  the  machine. 
A rope  e'  passed  over  a pulley  at  the  top  of  the  great  upright,  and  wound  round  the  barrel  of  a winch 
U,  serves  to  accomplish  tills  object. 

The  locomotive  geer  is  exceedingly  simple,  and  will  be  at  once  understood  by  referring  to  Figs.  3036 
and  8037.  A bevel-wheel/',  fixed  to  the  outer  end  of  the  shaft  T,  geers  with  another  of  equal  diameter 
working  loose  upon  the  shaft  V,  to  which  a pair  of  the  locomotive  wheels  a a are  fixed.  When  it  is 
required  to  move  the  platform,  with  its  superincumbent  machinery,  along  the  line  of  rails,  a sliding- 
clutch  g is  thrown  into  geer  with  the  last-mentioned  bevel-wheel,  and  is  disengaged  when  the  machine 
has  arrived  at  the  desired  position. 

Action  of  the  machine. — The  pile  having  been  raised  by  means  of  the  hoisting  apparatus,  and  its 
point  having  been  set  into  the  proper  position,  the  pile-case  G G,  with  its  attached  machinery,  is  low- 
ered down  over  tin;  head  by  reversing  the  small  engine  R,  so  that  the  jaws/ f rest  upon  the  shoulders 
of  the  pile,  which  sinks  down  into  the  ground  by  the  effect  of  the  superincumbent  weight,  till  it  has 
reached  soil  sufficiently  firm  to  support  it ; this  is  indicated  by  the  chain  cc  becoming  slack.  The  pin- 
ion y is  then  thrown  out  of  geer,  and  the  steam  is  admitted  into  the  driving-cylinder  F by  turning  the 
handle  i.  The  hammer-block  O is  by  this  means  raised  till  the  inclined  plane  o'  o",  coming  in  contact 
with  the  end  of  the  valve-lever  r,  causes  the  valve  k to  assume  the  position  represented  in  Fig. 
3044.  The  steam  which  had  served  to  raise  the  hammer  is  thus  allowed  to  blow  out  into  the  air, 
and  the  hammer  descends  and  discharges  its  Momentum  in  the  form  of  an  energetic  blow  upon  the 
head  of  the  pile.  During  the  descent  of  the  hammer-block,  the  steam-valve  is  retained  in  its  proper 
position  by  the  action  of  the  trigger  s,  but  by  the  effect  of  the  concussion  upon  the  head  of  the  pile,  the 
valve-spindle  is  released  from  contact  with  the  trigger,  and  the  steam-valve  assumes  the  position  indi- 
cated in  Fig.  3042,  in' which  circumstances  the  steam  is  allowed  to  act  freely  under  the  piston,  for  the 
purpose  of  again  raising  the  hammer. 

Such  is  the  rapidity  with  which  these  various  movements  and  functions  of  the  driving  apparatus  are 
accomplished,  that  the  machine  may  be  easily  made  to  perform  80  strokes  per  minute.  Some  idea  may 
be  formed  of  the  vast  efficiency  of  this  system  of  driving  piles,  when  it  is  stated  that,  in  ordinary 
ground,  piles  of  14  inches  square  are  driven  at  the  rate  of  upwards  of  10  feet  per  minute  1 

At  the  conclusion  of  the  driving  of  each  pile,  the  action  of  the  hammer  is  arrested  by  turning  the 
handle  i,  which  cuts  off  the  supply  of  steam.  The  great  chain-barrel  pinion  is  then  thrown  into  geer 
with  the  wheel  on  the  barrel-shaft,  and  the  small  engine  R is  started,  which  rapidly  raises  the  apparatus 
off  the  head  of  the  pile  to  the  top  of  the  great  guide-pole  C.  In  the  mean  time  the  locomotive  action 
is  applied,  and  the  machine  brought  opposite  the  next  pile,  when  the  process  just  described  is  repeated. 

PILE-DRIVING  MACHINE— THE  AMERICAN  STEAM.  The  following  is  a description  of  the 
American  steam  pile-driving  machine,  and  the  operations  for  which  it  is  applicable. 

The  machine  consists  of  two  pair  of  leaders,  similar  to  the  common  hand  machine,  placed  6 feet  from 
centre  to  centre,  and  firmly  bolted  to  a strong  horizontal  framing,  and  supported  by  two  oblique  lad- 
ders. The  frame  is  9 feet  wide  to  the  outside  of  the  framing,  and  28  feet  long ; it  carries  at  one  end 
a locomotive  boiler  11  feet  long  and  2 ft.  6 in.  diameter,  calculated  to  bear  120  lb.  per  square  inch 
pressure,  but  generally  worked  at  80  lb.  per  square  inch,  and  about  100  strokes  per  minute.  Under 
the  boiler  is  placed  the  supply  cistern.  In  the  centre  of  the  framing,  and  on  each  side  of  the  boiler,  is  a 
pair  of  inclined  cylinders  5J  inch  bore,  with  solid  pistons  working  well  without  packing,  and  14  inch 
stroke,  which  act  on  right-angled  crauks,  and  the  geering,  drums,  Ac.,  described  in  the  motions  of  the 
machine;  the  shaft  centres  are  1'  Z"  apart,  the  spur-wheel  has  56  and  the  pinion  19  teeth;  bevels  101 
and  40  teeth  ; saw-pulley  V 9"  and  10i  inches  diameter.  The  ram  is  generally  raised  from  4 to  5 
times  a.  minute,  the  steam  being  at  80  lb.  per  square  inch. 

For  river  work  the  machine  is  made  much  more  compact,  the  apparatus  is  placed  on  each  side  and 
over  the  boiler,  so  that  the  stage  is  little  more  than  half  the  length  of  the  machine  shown  in  the  en- 
graving, and  it  is  also  sometimes  made  with  an  apparatus  for  driving  one  pile  only,  consequently  re- 
quiring smaller  power. 

In  the  drawing,  Fig.  3050  is  a side  elevation  of  the  machine;  Fig.  3051  elevation  in  front  of  leaders, 
showing  saw,  &c. ; Fig.  3052  a section  taken  in  front  of  geering,  ifec. ; Fig.  3053  a plan  of  geering  end  with 
leaders  and  ladders  removed,  and  showing  saw  in  plan;  similar  letters  refer  to  similar  parts  in  each  figure. 

Taking  up  the  pile. — The  ram  A being  secured  by  placing  the  stop  B under  it,  by  means  of  the  small 
ropes  attached  to  the  latter,  and  passing  over  the  small  pulleys  C C,  to  within  three  feet  of  the  stage. 
The  dogs  D are  made  fast  to  the  pile,  Fig.  3052,  the  rope  attached  to  which  passes  upwards  through 
the  small  guide-pulleys  and  over  the  outer  pulley  E,  passes  downwards  and  is  coiled  round  the  pulley 
F fixed  on  the  shaft  G,  which  being  made  to  revolve,  raises  the  pile  to  its  place  between  the  leaders,  and 
is  then  secured  by  the  loose  stay  11  and  the  iron  work  II'  placed  round  it  for  guiding  it  perpendicularly. 

Driving  the  pile. — The  stop  B being  withdrawn  from  under  the  ram  A,  the  ram  is  raised  by  a rope, 
which,  being  secured  to  a staple  on  the  top  journal,  passes  down  under  the  pulley  I,  then  upwards  over 
the  pulley  K,  and  again  downwards  to  the  drum  L,  upon  which  the  rope  is  coiled.  The  drum  is  placed 
on  the  shaft  G,  which  is  made  to  revolve  by  the  spur-wheel  N working  in  the  pinion  O on  the  lower 
shaft  P,  which  shaft  revolves  by  the  action  of  two  cranks  Q,  Figs.  3050  and  3052,  placed  on  each  end  of 
the  shaft  P ; the  cranks  are  set  at  right  angles  to  each  other,  and  are  worked  by  the  connecting-rods  R 
attached  to  the  piston-rods,  which  are  furnished  with  slide  parallels,  as  shown  in  Fig.  3050.  The  slide- 
valves  of  the  piston  are  worked  by  the  eccentric  V on  the  end  of  the  shaft  P.  Steam  is  supplied  to 
the  cylinder  by  the  pipe  S from  the  boiler  T ; the  boiler  is  supplied  with  water  from  the  cistern  M, 
Fig-  3050,  by  the  pump  W,  which  is  worked  by  the  eccentric-rod  X fixed  on  the  spur  nave  at  Y,  or  by 


PILE-DRIVER— AMERICAN. 


481 


the  handle  at  Z ; the  supply  of  steam  is  regulated  by  the  handle  a acting  on  a valve  in  the  steam-pipe 
S.  The  drum  L consists  of  a fixed  and  a loose  cylinder,  the  latter  revolving  by  the  friction  of  the  for- 
mer, (fixed,)  and  is  brought  into  or  out  of  contact  by  the  hand-lever  Y,  Figs.  3050  and  3053,  which  has 
a fulcrum  attached  to  the  standard. 

The  follower/7  is  furnished  with  a pair  of  tongs  or  clippers,  which  takes  hold  of  a staple  fixed  on  the 
ram  and  carries  it  to  the  top  of  the  frame  ; then,  when  the  top  of  the  tongs  is  pressed  closer  together 
by  coming  between  the  contracted  cheeks  e'  e\  the  lower  part  opens  and  allows  the  ram  to  fall. 

For  working  the  apparatus,  the  engine-tender  stands  at  the  valve  S,  and  a man  at  the  lever  y of  each 
machine.  For  raising  the  ram  the  man  turns  on  the  steam  at  the  valve  S,  which  sets  in  motion 
the  apparatus  of  each  machine,  coils  the  rope  round  the  drums,  and,  at  the  same  time,  raises  the 
ram ; as  soon  as  the  latter  reaches  the  top  of  the  leaders,  the  ram  is  detached  and  descends  ; at  the 
same  moment  the  engine-tender  turns  off  the  steam,  and  the  men  at  the  levers  y throw  the  drum  out  of 
geer,  which  allows  the  clippers  and  chain  to  descend  again  and  lay  hold  of  the  ram,  when  the  drum  is 
again  thrown  into  geer,  the  steam  turned  on,  and  the  ram  again  raised,  and  so  the  operation  is  continued 
until  the  pile  is  driven. 

Drawing  a pile. — Chain  tackle  is  secured  to  the  pile  and  passed  over  the  top  pulley  to  the  drum  L, 
and  is  then  drawn  by  applying  the  power  to  turn  the  drum  of  the  apparatus. 


ITie  saw  apparatus  consists  of  a circular  saw  b,  4 feet  diameter,  having  teeth  set  three  inches  apart, 
secured  to  the  end  of  a beam  c,  which  beam  works  on  the  upright  shaft  d for  a centre,  and  slides  lat- 
erally on  the  iron  arc  e;  when  used,  the  saw  is  adjusted  to  the  proper  height  by  the  screws/,  and  a bar 
having  a hook  in  one  end,  and  fitting  into  a staple  in  the  beam’s  end,  is  used  to  press  the  saw  against 
the  work ; the  bevel-pinion  g being  raised  into  geer  by  the  foot-lever  h,  Fig.  3053,  motion  is  given  to 
the  pulleys  i and^'  and  band  k which  work  the  saw  b.  The  operation  of  sawing  off  the  end  of  a pile 
takes  less  than  a minute. 

Progressing  motion. — The  hook  l being  fastened  to  a driven  pile,  and  the  rope  passed  over  the  pulley 
m attached  to  the  side  of  the  frame  to  the  pulley  F,  round  which  it  is  coiled  twice  and  the  end  held  by 
a man  ; motion  being  now  given  to  the  drum  the  machine  progresses ; this  motion  is  shown  by  the 
dotted  rope,  Fig.  3050.  It  should  be  stated  that  the  frame  is  intended  to  be  supported  upon  six  rail- 
way wheels,  which  run  on  a temporary  rail  laid  on  the  top  of  the  piles  as  they  are  driven.  There  is 
another  mode  of  progressing,  but  which  is  not  found  to  answer  so  well,  viz.,  by  means  of  two  sledge 
beams  faced  with  iron  and  attached  to  the  under-framing ; these  are  placed  six  feet  apart  from  centre 
to  centre,  and  pass  under  the  whole  length  of  the  machine,  and  slide  on  small  iron  wheels  fixed  to 
standards,  which  are  placed  loose  on  the  piles. 

The  plumb-bob  l suspended  to  a line  regulates  the  pile  being  driven  perpendicularly,  and  Y is  a lever 
attached  to  a friction  baud  break  passing  over  the  end  of  the  drum,  which  is  only  used  occasionally. 

Vol.  II.— 31 


482 


PILING  MACHINE. 


For  the  steam  machine  it  requires  to  work  the  engine  and  apparatus  for  driving  two  piles  at  one  time, 
with  a ram  weighing  16  cwt.,  the  following  men : an  engine-tender,  one  man  for  throwing  each  apparatus 
in  and  out  of  geer,  and  one  man  to  attend  to  each  pile,  making  altogether  five  men  for  driving  two  piles 
For  the  ordinary  machine  it  requires  four  men  to  work  the  crab-engine  for  lifting  a ram  of  the  same 


3053. 


weight,  and  one  man  to  attend  to  the  driving  of  the  pile,  making  five  men  for  each  pile,  or  10  men  for 
two  piles.  With  the  steam  machine  the  ram  is  lifted  four  or  five  times  in  a minute,  thereby  the  opera- 
tion of  driving  the  pile  is  very  short  in  comparison  with  the  ordinary  machine.  The  cost  of  the  steam 
machine,  with  an  engine  of  ten  horse-power,  tubular  boiler  and  apparatus,  is  about  83500,  and  the  cost 
of  the  ordinary  pile-driving  machine,  with  crab-engine,  is  about  8350. 


3058. 

r‘ — =a 

J ^ L 


PILING  MACHINE.  Fig.  3054  represents  the  side  elevation,  Fig.  3055  the  front  elevation,  Fig, 
3056  the  plan,  and  Fig.  3057  a section  of  a pile-driver  used  at  the  construction  of  the  Dry  Dock.  Brook 


PILING  MACHINE. 


483 


484 


PILE,  SCREW,  AND  SCREW-MOORING. 


lyn  Navy  Yard,  drawn  to  a scale  of  8 feet  to  an  inch.  Fig.  3085  is  a plan  of  the  hammer,  weighing 
4050  pounds. 

Figs.  3061,  3059,  and  3060  are  plan,  elevation,  and  section  of  the  nippers. 

Fig.  3063,  plan  and  elevation  of  head-pulley. 

These  machines  were  operated  by  steam  ; the  fall  passing  through  the  leading-blocks  to  the  drum  o; 
a steam  engine. 

PILE,  SCREW  AND  SCREW  MOORING.  To  Alexander  Mitchell,  Esq.,  of  Belfast,  Ireland,  the 
profession  is  indebted  for  this  discovery,  by  means  of  which  we  are  now  able  to  construct  permanent 
foundations  in  deep  water,  on  shoals  of  sand,  mud,  clay,  or  gravel,  or  in  fact  on  any  bottom,  excepting 
solid  rock,  and  to  moor  shipping  of  the  largest  class  with  a degree  of  security  never  before  attained. 

8063 


The  plan  which  appeared  best  adapted  for  obtaining  a firm  hold  of  soft  ground  or  sand,  was  to  insert 
to  a considerable  distance  beneath  the  surface  a bar  of  iron,  fig.  3063,  having  at  its  lower  extremity  a 
broad  plate,  or  disk  of  metal,  in  a spiral  or  helical  form,  on  the  principle  of  the  screw,  in  order  that  it 
should  enter  the  ground  with  facility,  thrusting  aside  any  obstacles  to  its  descent,  without  materially  dis- 
turbing the  texture  of  the  strata  it  passed  through,  and  that  it  should  at  the  same  time  offer  an  ex- 
tended base,  either  for  resisting  downward  pressure,  or  an  upward  strain. 


Whether  this  broad  spiral  flange,  or  “ ground-screw,”  as  it  may  he  termed,  he  applied  to  the  foot  of  a 
pile  to  support  a superincumbent  weight,  or  be  employed  as  a mooring  to  resist  an  upward  strain,  its 
holding  power  entirely  depends  upon  the  area  of  its  disk,  the  nature  of  the  ground  into  which  it  is  in- 
serted, and  the  depth  to  which  it  is  forced  beneath  the  surface. 

The  proper  area  of  the  screw  should,  in  every  case,  be  determined  by  the  nature  of  tho  ground  in 


PILE,  SCREW,  AND  SCREW-MOORING. 


48, 


which  it  is  to  he  placed,  and  which  mnst  be  ascertained  by  previous  experiment.  The  largest  size 
nitherto  used  has  been  4 feet  in  diameter ; but  within  certain  sizes,  prescribed  by  the  facility  of  manufac- 
turing them,  the  dimensions  may  be  extended  to  meet  any  case,  and  may  be  said  to  be  limited  only  bj 
the  power  available  for  forcing  them  into  the  ground. 

Either  the  screw-pile  or  the  screw-mooring  can  be  employed  in  every  description  of  ground,  hard 
rock  alone  excepted  ; for  its  helical  form  enables  it  to  force  its  way  among  stones,  and  even  to  thrust 
aside  medium-sized  boulders.  In  ports,  harbors,  estuaries,  and  roadsteads,  rock  is,  however,  seldom  met 
with,  except  in  detached  masses,  the  ground  being  usually  an  accumulation  of  alluvial  deposit,  which 
is  well  adapted  for  the  reception  of  such  foundations,  and  is  also  that  in  which  they  are  generally  most 
required. 

The  ground-screw  has  been  already  extensively  used  for  several  purposes,  and  its  applicability  to 
many  others  will  be  evident  from  a succinct  account  of  its  present  employment. 

The  fixed  or  permanent  moorings  at  present  most  commonly  used  are  of  two  kinds — the  span-chain 
mooring,  and  the  sinker,  or  mooring-block. 

The  former  of  these  consists  of  a strong  chain  of  considerable  length,  stretched  along  the  ground 
(across  the  river),  and  retained  by  heavy  anchors,  or  mooring  blocks,  at  either  end,  and  to  the  middle 
of  the  ground-chain  the  buoy-chain  is  shackled. 

The  other  kind,  which  is  more  generally  employed,  consists  of  a heavy  sinker,  to  which  a strong  chain 
is  attached,  extending  to  a buoy  shackled  at  the  other  end  (fig.  3064).  This  sinker,  which  is  a block  of 
stone  or  iron,  is  either  laid  upon  the  surface  of  the  ground,  or  is  placed  in  an  excavation  prepared  for 
its  reception.  As  a simple,  effective,  and  at  the  same  time  an  inexpensive  mode  of  holding  the  buoy- 
chain  down,  Mr.  Mitchell  adopted  a modification  of  the  screw-pile,  fig  3065,  because  it  offers  great  facil- 
ities for  entering  the  ground,  and  when  arrived  at  the  required  depth,  it  evidently  affords  greater  holding 
power  than  any  other  form. 

Every  description  of  earth  is  more  or  less  adhesive,  and  the  greater  its  tenacity,  the  larger  must  be 
the  portion  disturbed,  before  the  mooring  can  be  displaced  by  any  direct  force.  The  mass  of  ground 
thus  affected,  in  the  case  of  the  screw-mooring,  is  in  the  form  of  a frustrum  of  a cone,  inverted ; that 
is,  with  its  base  at  the  surface,  the  breadth  of  the  base  being  in  proportion  to  the  tenacity  of  the 
ground ; this  is  pressed  on  by  a cylinder  of  water  equal  to  its  diameter,  the  axis  of  which  is  its  deptlr, 
and  the  water  again  bears  the  weight  of  a column  of  air  of  the  diameter  of  the  cylinder. 

It  is  evident,  therefore,  that  if  a cast  iron  screw,  of  a given  area,  be  forced  into  the  earth  to  a certain 
depth,  it  must  afford  a firm  point  of  attachment  for  a buoy-chain  in  every  direction  (fig.  3066),  and  will 
oppose  a powerful  resistance,  even  to  a vertical  strain,  which  generally  proves  fatal  to  sinker  moorings, 
depending  (as  they  do)  chiefly  on  their  specific  gravity. 

The  first  trials  were  upon  a comparatively  small  scale  ; but  their  success  was  so  decisive  that  the 
merits  of  the  moorings  were  acknowledged,  and  their  use  soon  became  extended. 

The  depth  to  vrhich  these  moorings  have  been  screwed  varies  from  8 to  18  feet;  the  former  is  deep 
enough  where  the  soil  is  of  a firm  and  unyielding  description,  and  the  latter  depth  is  found  to  give  suffi- 
cient firmness  in  a very  weak  bottom.  It  is  evident  from  its  form,  that  every  part  of  the  screw-mooring 
is  so  far  beneath  the  surface,  as  to  prevent  a vessel  from  receiving  injury  from  grounding  immediately 
above  it,  the  mooring  chain  alone  protruding  from  the  ground ; and  it  is  also  obvious  that  anchors, 
dropped  in  the  neighborhood,  cannot  be  hooked  into  or  get  foul  of  the  chain,  one  end  alone  being  at- 
tached to  the  ground. 

In  fixing  these  moorings  in  the  ports  and  harbors  where  they  have  been  used,  the  persons  hitherto 
engaged  in  the  operation  have  been  generally  compelled  to  avail  themselves  of  any  means  within  their 
reach,  for  the  construction  of  a floating  stage,  or  platform,  on  which  the  men  could  execute  the  work. 
Barges,  lighters,  and  pontoons  have  been  therefore  indifferently  employed ; those  that  were  without  ■ 
decks  being  planked  over  for  the  purpose.  Two  such  vessels  being  lashed  broadside  to  each  other,  with 
a certain  space  between  them,  are  securely  moored  over  the  spot,  and  the  screw-mooring  lowered,  with 
the  chain  attached  to  the  shackle,  from  the  centre  of  the  stage,  to  the  level  of  the  water,  and  as  it  de- 
scends to  the  bottom  the  lengths  of  the  apparatus  for  screwing  it  into  the  ground  are  successively  at- 
tached. 

This  apparatus,  fig.  3067,  consists  of  a strong  wrought-iron  shaft,  in  lengths  of  10  or  12  feet  each, 
connected  with  each  other  by  key-joints  or  couplings,  the  lower  extremity  having  a square  socket  to  fit 
the  head  of  the  centre  pin,  or  axis,  of  the  mooring.  When  the  centre  pin  rests  on  the  bottom,  a capstan 
is  firmly  keyed  upon  the  shaft  at  a convenient  height ; the  men  then  shift  the  capstan  bars  and  apply 
their  power  whilst  travelling  round  upon  the  stage,  the  capstan  being  lifted  and  again  fixed  as  the  moor- 
ing is  screwed  down  into  the  ground.  The  operation  is  continued  until  the  men  can  no  longer  move  the 
shaft  round,  or  until  it  is  considered  to  have  been  forced  to  a sufficient  depth. 

The  most  important  purpose  to  which  the  screw-pile  has  hitherto  been  applied,  to  any  considerable 
extent,  is  for  forming  the  foundations  of  lighthouses,  beacons,  and  jetties,  in  situations  where  the  soil, 
or  sand,  is  so  loose  and  unstable,  as  to  be  incapable  of  supporting  any  massive  structure,  or  whore  the 
waves  have  so  much  power  of  undermining  by  their  continuous  action,  or  beat  so  heavily,  that  the  sta- 
bility of  any  mass  of  masonry  would  be  seriously  endangered. 

In  1838,  Mr.  Mitchell  and  his  son  laid  the  foundation  of  the  Maplin  Sand  Lighthouse.  Before  deter- 
mining the  length  of  the  piles  and  the  area  of  the  screws  to  be  employed,  a careful  examination  of  the 
ground  was  made,  and  it  was  proposed  to  use  nine  malleable-iron  piles  of  5 inches  diameter,  and  26  feet 
in  length,  with  a cast-iron  screw  of  4 feet  diameter,  secured  to  the  foot  of  each.  Eight  of  the  piles 
were  placed  at  the  angles  of  an  octagon,  and  one  in  the  centre  ; these  were  put  down  in  nine  consecu- 
tive days,  being  screwed  into  the  bank  to  the  depth  of  22  feet,  leaving  4 feet  above  the  surface.  The 
tile  rises  on  the  bank  about  16  feet,  and  seldom  leaves  the  surface  dry. 

The  instrument  used  in  trying  the  nature  of  the  ground  was  also  employed  in  testing  its  holding 


486 


PILE,  SCREW,  AND  SCREW-MOORING 


power.  It  consisted  of  a jointed  rod  30  feet  long,  and  inch  in  diameter,  having  at  its  foot  a spiral 
flange  of  6 inches  diameter.  It  was  moved  round  by  means  of  cross  levers,  keyed  upon  the  boring-rod 
and  upon  these  levers,  when  the  screw  was  turned  to  the  depth  of  27  feet,  a few  boards  were  laid,  form 
ing  a platform  sufficiently  large  to  support  twelve  men.  A bar  was  then  driven  into  the  bank  at  some 
distance,  its  top  being  brought  to  the  same  level  as  that  of  the  boring-rod.  Twelve  men  were  theE 
placed  upon  the  platform  to  ascertain  if  their  weight,  together  with  the  apparatus,  in  all  about  one  ton, 
sufficed  to  depress  the  screw.  After  some  time  the  men  were  removed,  and  the  level  was  again  applied) 
but  no  sensible  depression  of  the  screw  could  be  observed. 

The  inference  from  it  was,  that  if  a screw  of  6 
inches  in  diameter  could  support  one  ton,  one  of 
4 feet  diameter  was  capable  of  supporting  at 
least  64  tons,  the  comparative  area  of  their  sur- 
faces being  as  the  square  of  their  diameters ; but 
this  experiment  was  nothing  more  than  an  ap- 
proximation to  the  truth,  a continuous  surface 
possessing  a much  greater  sustaining  power  than 
the  same  area  in  detached  portions. 

In  fixing  the  foundation  piles  for  the  Maplin 
Sand  Lighthouse,  a raft  of  36  feet  square  was 
used  as  a stage,  or  platform,  upon  which  the  men 
worked,  as  barges  would  have  been  too  high 
from  the  surface,  and  “ it  was  necessary  to  ground  the  raft  itself,” 
before  the  piles  could  be  screwed  down  to  the  required  depth, 
their  heads  being  only  a short  distance  above  the  bank.  The 
raft  was  constructed  of  balks  of  American  timber  bolted  together, 
leaving  an  aperture  of  two  feet  in  width  from  one  side  to  the  cen- 
tre, by  which  the  pile  was  brought  to  its  position. 

A screw-pile  lighthouse  of  iron  has  been  constructed  on  the 
Brandywine  Shoal,  in  Delaware  Bay,  under  the  orders  of  the 
Bureau  of  Topographical  Engineers.  This  work  being  very  much 
exposed  to  the  action  of  fields  of  drift  ice  during  the  winter 
months,  it  was  deemed  prudent  to  protect  it  by  an  exterior  work 
that  should  serve  as  an  ice-fender:  this  consists  of  30  screw-piles 
of  wrought-iron  of  5 inches  diameter.  These  30  piles  are  placed 
in  symmetrical  order,  so  as  to  form  an  oblong  hexagon,  75  feet 
on  the  largest  diameter,  and  45  feet  on  the  shorter.  The  piles  are 
framed  together  at  their  heads  by  ties  of  3-inch  round  iron,  keyed 
into  cast-iron  sleeves  fitted  to  the  pile-heads.  A similar  system 
of  ties  connects  the  piles  at  the  plane  of  low  water.  The  nine 
piles  that  form  the  foundation  of  the  lighthouse  are  inclosed  in 
this  system,  which  has  been  found,  during  a series  of  winters,  a 
most  effectual  protection  against  the  heaviest  drifts  of  field-ice — 
no  injury  w'hatever  having  thus  far  been  sustained  by  any  part  of 
the  work. 

Under  the  same  Bureau,  a screw-pile  lighthouse  of  great  size 
has  been  commenced  on  the  Florida  Beefs  at  Sand  Key,  and  the 
foundation  already  completed.  This  work  is  quite  peculiar,  and 
has  many  novel  features.  The  principal  one  is,  however,  the 
modification  of  the  form  of  the  screw,  into  something  like  a screw 
auger,  enabling  the  engineer  thereby  to  penetrate  through  solid 
masses  of  coral,  of  which  these  reefs  are  entirely  composed.  This 
invention  enables  the  government  to  erect  a chain  of  lights  along 
the  whole  reef  (upwards  of  250  miles  long),  and  right  on  the  edge 
of  the  Gulf  stream. 

Previously  it  was  thought  impracticable  to  locate  any  perma- 
nent structure  on  these  reefs,  as  in  hurricane  seasons  they  are 
deeply  submerged,  and  exposed  to  a tremendous  sea  from  the  Gulf 
stream.  By  means  of  the  screw-pile,  as  modified  for  this  locality, 
all  difficulties  are  now  surmounted,  and  it  is  supposed  that  within 
a few  years  the  whole  reef  will  be  illuminated,  and  rendered 
safely  navigable. 

The  superintendent  of  the  United  States  Coast  Survey  has 
adopted  this  modified  screw-pile  to  establish,  on  the  Florida 
Beefs,  his  marks  of  triangulation,  the  old  form  of  tripod  being 
annually  washed  away,  and  their  replacement  attended  with  a 
great  expense.  To  the  screw  is  attached  a tube  of  cast-iron  8 
fe^t  long ; by  means  of  this  tube,  which  takes  the  place  of  the  ordinary  pile,  the  screw  is  inserted  into 
the  reef  4 or  5 feet  deep.  A long  signal  pole,  with  a cone  or  ball  on  top,  is  then  inserted  in  the  iron 
tube,  and  will  stand  erect  during  the  heaviest  storms.  The  number  ot  wrecks  on  these  reefs  has  greatly 
dininished  since  the  operations  of  the  Coast  Survey  were  commenced. 

Three  beacons  have  been  erected  by  Mitchell  & Son  for  the  Dublin  Ballast  Board, ^ on  the  Kish  Bank, 
the  Arklow  Bank,  and  the  Blackwater  Bank,  which  are  parts  of  the  same  shoal.  Ihese  have  all  been 


PILE,  SCREW,  AND  SCREW-MOORING. 


4S7 


put  down  with  the  intention  of  placing  lighthouses  on  their  sites,  should  they  appear  eventually  to  suffer 
no  change  by  the  action  of  the  sea.  All  these  beacons  are  similar  in  form  and  principle  (fig.  3068) 
each  consisting  of  a single  pile  of  wrought-iron  in  two  joints,  connected  by  a strong  screw-coupling, 
and  measuring,  when  together,  63  feet  in  length  ; their  diameter  at  the  surface  of  the  ground  is  8 inches, 
diminishing  from  thence  both  up  and  down. 

The  incompressible  nature  of  the  sand  offering  considerable  opposition  to  the  descent  of  the  pile, 
screws  of  only  2 feet  in  diameter  were  used,  and  on  the  top  of  each  pile,  when  fixed,  a ball  was  placed 
of  3 feet  6 inches  diameter.  The  screws  used  for  the  Blackwater  and  the  Arklow  beacons  were  forged 
of  malleable  iron,  and  turned  in  the  lathe,  at  great  expense ; but  that  will  probably  never  again  bo 
necessary,  as  they  can  generally  be  quite  as  well  made  of  cast-iron,  and  at  much  less  cost. 

One  of  these  beacons  was  fixed  in  June,  1843,  the  other  two  in  the  summer  of  1846,  and  are  all 
standing,  though  two  of  them  diverge  considerably  from  the  perpendicular,  having  been  frequently 
struck  by  vessels  in  heavy  weather. 

The  engineer  of  the  Great  Portland  Breakwater,  which  the  British  government  have  ordered  to  be 
constructed  as  a harbor  of  refuge  for  the  Channel  fleets,  has  applied  the  screw-pile  in  a novel  and  effi- 
cient manner.  On  the  axial  line  of  the  breakwater  a viaduct  of  screw-piles  is  erected,  bearing  a railway, 
which  extends  inland  to  the  quarries,  and  is  prolonged  seaward  as  fast  as  the  growth  of  the  work  requires. 
The  stone  of  which  the  breakwater  is  to  consist  is  thus  brought  direct  from  the  quarry  by  rail,  to  the  site, 
and  there  dumped  into  the  water.  The  screw-pile  viaduct  is  of  course  buried  up  in  the  mass  of  the 
breakwater  ; but  an  enormous  saving  has  been  effected  by  this  arrangement,  when  compared  with  that 
pursued  at  the  Plymouth  Works.  An  extensive  railway  viaduct  was  erected  on  screw-piles  over  the 
fens  of  Linconshire  in  1849,  by  Mr.  W.  Cubitt,  and  other  similar  structures  are  now  in  progress. 

Messrs.  Ransomes  and  May  (of  Ipswich,  England)  have  constructed  several  kinds  of  cast-iron  screw- 
points,  shown  in  figs.  3069,  3070,  3071,  and  3072. 


8069 


8070 


Fig.  3069  shows  the  largest  size,  weighing  2 
cwt.  3 qrs.  14  lbs.,  adapted  for  whole  timber  piles, 
which  are  often  so  splintered  and  shattered,  and 
even  set  on  fire,  by  the  rapid  blows  of  the  steam 
pile-driver,  when  traversing  compact  ground,  and 
where  wrought-iron  shoes  are  generally  crushed 
into  the  timber  even  in  ordinary  ground,  with 
the  force  of  the  common  pile-engine.  The  small 
screw-point  opens  the  way  for  the  conical  part, 
and  the  larger  screw  not  only  draws  the  pile 
down,  but,  when  it  has  penetrated  to  a sufficient 
depth,  affords  an  extended  base  for  preventing 
further  .depression.  Thus  several  feet  of  timbei 
must  be  saved,  and  the  general  length  of  the  pile 
can  be  reduced,  as  it  will  bear  a greater  weight 
and  offer  a more  solid  base  when  introduced 
to  a less  distance,  than  when  it  rests  upon  the 
ordinary  sharp,  wrought-iron  pointed  shoe. 


8071 


Fig.  3070,  weighing  3 qrs.  22  lbs.,  shows  the  shape  adapted  for  railway  signal-posts ; and  fig.  3071, 
weighing  2 qrs.  4 lbs.,  that  for  the  supports  for  the  wires  of  the  electric  telegraph.  For  these  purposes 
the  screw-points  must  be  very  useful,  as  independent  of  the  economy  of  labor  in  putting  them  down  by 
merely  screwing  them  into  the  ground,  instead  of  digging  holes  to  introduce  the  cross-feet,  all  possibility 
of  injury  to  the  banks  would  be  precluded ; whereas  at.  present  there  is  always  a liability  of  causing  a 
slip  by  disturbing  uncertain  ground,  and  admitting  water  in  the  sides  of  cuttings. 


488 


PILE,  SCREW,  AND  SCREW  MOORING. 


The  cast-iron  screw  socket-points,  fig.  30G9,  have  recently  teen  very  successfully  applied  for  the  sup 
porting  posts  or  columns  of  timber-sheds  and  buildings  for  railway  stations  and  other  purposes. 

Fig.  3072  shows  the  applicability  to  smaller  objects,  and  a tent-pin  has  been  selected  as  the  most  famil 
iar  example,  as  it  requires  to  be  removed  so  frequently,  and  shows  the  use  that  may  be  made  of  the 
screw  for  the  standards  of  fencing,  and  for  an  infinite  number  of  agricultural  and  other  purposes. 

The  diagram  given  below  represents  four  lighthouses  that  have  been  erected  on  the  “ skeleton  frame 
tower  system,”  with  screw-pile  foundations.  The  whole  of  these  structures  are  drawn  to  one  scale,  sc 
that  at  a glance  their  comparative  magnitudes  in  elevation  and  area  of  foundations  are  immediately 
visible.  The  Brandywine  Lighthouse  i3  erected  upon  the  shoal  of  that  name  at  the  mouth  of  Delaware 


Sand  Key,  1851.  Brandywine,  1849.  Maplin,  1840.  Fleetwood,  1839. 

in  form,  and  consists  of  two  stories.  The  prevalence  of  vast  fields  of  ice  in  the  Delaware  in  winter, 
rendered  it  advisable  to  protect  the  frame  of  the  tower  by  surrounding  it  with  a system  of  thirty  5 
inch  screw-piles,  arranged  in  the  form  of  a hexagon  of  75  by  45  feet,  the  longer  axis  of  the  polygon 
being  parallel  to  the  thread  of  the  current.  This  ice-breaker  has  proved  perfectly  efficient  after  a trial 
of  seven  winters. 

The  screw-pile  lighthouse  at  Sand  Key,  constructed  by  I.  W.  P.  Lewis,  is  different  in  design  and  de- 
tail from  all  that  have  preceded  it.  On  reference  to  the  diagram,  it  will  be  seen  that  the  base  is  square. 
It  was  found  while  constructing  the  Brandywine  and  Carysfoot  lighthouses,  that  there  was  a want  of 
rigidity  in  the  frame-tower,  and  that  the  application  of  any  external  force  produced  a vibratory  move- 
ment about  the  central  axis  of  the  frame.  Secondly,  it  was  observed  that  in  tying  all  the  horizontal 
framing  to  a common  centre,  there  was  a very  unequal  distribution  of  metal  and  strength — the  centre  pile 
bearing  6 or  8 times  the  load  borne  by  any  one  of  the  angle  piles.  Both  these  important  defects  are 
entirely  remedied  by  adopting  the  square  base.  The  tower  at  Sand  Key  requiring  to  be  of  the  first 
class,  it  was  decided  to  increase  the  number  of  piles  to  16,  and  one  auxiliary  pile  in  the  centre  to  bear 
the  weight  of  the  staircase.  The  foundation  thus  is  formed  of  17  screw-piles  of  8 inches  diameter,  armed 
with  a modified  form  of  screw  2 feet  in  diameter.  A survey  in  1850  by  the  engineer,  enabled  him  to 
design  a form  of  screw,  similar  in  principle  to  a centre-bit  auger,  which  should  with  a very  slow  motion 
tut.  its  way  through  the  coral.  This  screw  was  entirely  successful ; being  slowly  turned  by  powerful 
Machinery,  it  descended  through  the  coral  about  2 inches  for  each  revolution. 

The  screws  are  bored  12  feet  into  the  reef,  and  the  pile-heads  being  framed  and  braced  together  as 
shown  in  the  diagram,  a perfectly  rigid  and  firm  foundation  is  obtained. 

The  superstructure  of  the  frame-tower  consists  of  six  series  of  cast-iron  tubular  columns,  framed  to- 
gether with  wrought-iron  ties  at  each  joint,  and  braced  diagonally  on  the  faces  of  each  tier,  as  seen  in 
the  diagram  ; the  rigidity  of  such  a system  of  pillars  and  braces  can  be  easily  estimated. 

The  keeper’s  house  rests  on  a floor  of  cast-iron,  supported  upon  cast-iron  girders  and  joists,  at  the 
height  of  20  feet  above  the  plane  of  the  foundation  top  ; this  is  higher  by  15  feet  than  the  great  hurri- 


^IN-MAKING  MACHINE 


489 


cane  tide  of  1846,  and  beyond  the  reach  of  any  sea  that  could  rise  there,  the  surrounding  coral  reel 
forming  a perfect  breakwater. 

The  foundation  of  Sand  Key  Lighthouse  measures  50  feet  on  the  side  of  the  square,  and  its  tota. 
height  is  132  feet,  or  120  feet  above  high-water  level.  The  site  is  a small  bank  of  calcareous  sand 
thrown  up  by  the  combined  effects  of  wind  and  tide,  to  the  height  of  4 feet  above  mean  high  water,  and 
in  depth  about  2 feet  below  low-water  leveL 

PIN-MAKING  MACHINE.  An  improved  method  of  making  pins,  by  John  J.  Howe,  of  New 
Haven,  Connecticut.  The  wire  having  been  properly  straightened  and  placed  in  a coil  upon  a suitable 
reel,  and  having  one  of  its  ends  introduced  in  a proper  manner  into  the  machine,  is,  in  successive  por- 
tions, drawn  in  and  converted  into  pins,  by  the  action  of  the  machine  ; each  pin  so  made  by  the  machine 
consisting  of  a single  piece  of  metal  or  wire,  the  head  of  the  pin  being  upset  or  raised,  and  formed  at 
one  end,  and  the  other  end  being  sharpened  in  a suitable  manner,  to  form  the  point.  The  following  is  a 
full  and  exact  description  thereof,  and  of  the  manner  of  constructing  and  using  the  same,  reference  being 
had  to  the  accompanying  figures. 

The  individual  parts  of  the  machine  are  marked  in  the  drawings  with  capital  letters,  with  small 
letters,  and  with  numbers  respectively ; and  the  same  marks  of  reference  refer  in  all  cases  to  the  same 
or  similar  parts. 

Of  tlie  driving-povicr. — The  machine  is  put  in  motion  through  a driving-shaft  F,  which  has  its  bear- 
ings formed  in  the  portion  A 7 of  the  fixed  frame,  shown  in  Fig.  8064.  The  shaft  F is  placed  at  right 
angles  to  the  main-shaft  B,  and  both  of  said  shafts  are  in  a horizontal  position  in  the  same  plane  with 
each  other. 

On  the  outer  end  of  the  shaft  F are  fixed  a fast  pulley  1,  a loose  pulley  2,  a fly-wheel  3,  and  a pulley  4, 
for  driving  the  shaft  L,  which  carries  the  pulleys  45  for  driving  the  pointing  mills,  and  on  the  inner  end 
of  said  shaft  F is  fixed  a bevel-pinion  G.  The  aforesaid  bevel-pinion  G works  into  the  bevel-wheel  K, 
which  is  fixed  on  the  shaft  B,  said  wheel  having  four  times  the  number  of  teeth  of  the  pinion  G,  so  that 
four  revolutions  of  the  driving-shaft  F communicate  one  revolution  to  the  shaft  B.  The  horizontal  shaft  B 
is  connected  with  the  vertical  shaft  c by  bevel  and  spur  geering,  so  that  both  the  said  shafts  revolve  in 
the  same  time  in  the  direction  indicated  by  the  arrows  on  the  respective  shafts,  as  is  shown  in  Fig.  3063. 
The  mitre  bevel-wheel  HI  on  the  shaft  B works  into  the  mitre  bevel-wheel  H2,  which  has  its  axis 
placed  perpendicularly  beneath  the  shaft  B.  On  the  axis  of  the  bevel-wheel  H2  is  fixed  a spur-wheel 
12,  which  works  into  a similar  spur-wheel  fixed  on  the  vertical  shaft  c. 

The  pulley  4,  Fig.  3067,  is  connected  by  a belt  to  the  pulley  5 on  the  shaft  L,  for  the  purpose  of  com- 
municating an  accelerated  rotary  motion  to  the  shaft  L.  On  tjie  shaft  L are  the  pulleys  45,  which  are 
respectively  connected  by  bands  44  with  the  pulleys  43,  Fig.  3063,  on  the  arbors  or  spindles  of  the 
mills  or  revolving  circular  files  38,  for  the  purpose  of  communicating  the  necessary  rapid  rotary  motion 
to  said  mills,  by  which  the  points  of  the  pins  are  ground  and  sharpened. 

Of  the  feeding  and  cutting  apparatus — Fig.  3069  is  a perspective  view  of  the  combined  apparatus  for 
feeding  in  and  cutting  off  the  wire,  with  a portion  of  the  semicircular  horizontal  part  of  the  frame, 
to  which  the  principal  parts  of  said  apparatus  are  attached.  Other  views  of  said  apparatus  are  repre- 
sented in  Figs.  3063  and  3064.  The  fixed  portion  of  the  feeding  apparatus  consists  of  a horizontal 
part  8a  and  two  arms,  86  and  8c,  depending  in  a perpendicular  direction  from  the  under  side  of  said 
horizontal  portion.  The  horizontal  portion  8a  has  an  oblong  opening  through  it,  extending  in  a hori- 
zontal direction  from  within  towards  the  shaft  c outwards.  The  two  vertical  surfaces  of  said  portion,  8a, 
are  dressed  straight  and  parallel  with  each  other,  and  the  two  sides  of  the  aforesaid  oblong  opening  are 
also  dressed  straight  and  parallel  with  each  other.  A slide  9 d,  which  rest3  against  the  front  vertical 
face  of  the  portion  8a,  is  connected  through  the  said  opening  in  8a  with  a cap,  which  rests  against 
the  back  vertical  face  of  the  portion  8a,  and  the  portion  by  which  the  slide  9a  is  connected  with  the 
cap  96  is  so  formed  and  fitted  into  said  opening  as  to  allow  said  slide  to  move  freely  forward  and 
backward,  but  not  to  turn  or  move  in  any  other  direction.  The  slide  9a  has  a stud  9c  standing  out 
horizontally  at  right  angles  to  and  near  the  centre  of  its  face.  There  is  a small  hole  made  horizontally 
through  said  stud  close  to  the  face  of  the  slide,  through  which,  and  also  through  an  eye  formed  for  the 
purpose,  near  each  end  of  the  slide,  the  wire  is  introduced  in  a horizontal  direction  from  right  to  left. 
There  is  a steel  cap  10  fitted  by  a hole  in  its  centre  on  the  stud  9c,  behind  which  the  wire  is  introduced 
as  aforesaid,  in  the  manner  represented  in  Fig.  3069.  The  lever  11  of  the  feeder  has  a fork  at  its  upper 
end  to  receive  the  stud  9c,  and  near  its  lower  end  it  has  the  stud  11a  and  the  plate  116  to  receive  the 
action  of  the  feeder-cam  a;  the  lever  11  is  jointed  to  the  extremities  of  the  two  arms  86  and  8c  of  the 
feeder-frame  8 a6c  by  the  ring  12,  and  the  four  centre  or  pivot  screws  13,  Fig.  3069,  so  as  to  furnish 
said  lever  with  two  horizontal  axes  intersecting  each  other  at  right  angles  in  the  manner  of  a universal 
joint ; by  means  of  which  the  forked  end  of  said  lever  is  allowed  to  be  alternately  pressed  against  the 
cap  10  and  then  removed  from  it,  at  the  same  time  that  it  has  a reciprocating  motion  forward  and  back- 
ward, for  the  purpose  of  carrying  forward  the  feeder  9a  in  the  act  of  introducing  the  wire  and  then 
carrying  said  feeder  back,  in  order  to  its  introducing  another  portion  of  wire.  The  cam  a,  by  which  the 
movements  and  actions  of  the  feeder  are  produced,  is  represented  in  Fig.  3069.  Said  cam  a (revolving 
in  the  direction  indicated  by  the  arrow)  acts  by  the  face  a2  on  its  periphery  against  the  stud  11a  of  the 
lever  11  to  carry  forward  the  feeder  9,  and  by  the  face  13,  on  its  periphery,  to  retain  said  feeder  for  a 
short  period  in  the  advanced  position  to  which  it  had  been  previously  carried ; the  face  a3  of  said  cam 
being  concentric  with  the  axis  B,  on  which  said  cam  is  fixed ; said  cam  a has  a rib  or  raised  portion  dl 
on  its  side,  by  which  it  acts  against  the  plate  116  of  the  lever  11  to  press  the  forked  end  of  said  lever 
against  the  cap  10  of  the  feeder,  in  order  to  grasp  the  wire  in  the  act  of  feeding  it  into  the  machine.  A 
spiral  spring  14  is  attached  to  the  lower  end  of  the  lever  11,  below  its  stud  and  plate  aforesaid,  and  t.> 
6ome  part  of  the  fixed  frame,  so  as  to  draw  obliquely  inward  that  end  of  said  lever,  and  to  retract  it  as 
soon  as  the  cam  a recedes  after  having  performed  its  aforesaid  actions  respectively  on  said  stud  11a  and 
plate  116. 


490 


PIN-MAKING  MACHINE. 


A gage-screw  15  is  fitted  into  the  exterior  end  of  the  portion  8a  of  the  feeder-frame,  against  the  poin* 
of  which  the  slide  of  the  feeder  stops,  when  it  is  carried  back  in  the  manner  above  described  by  the 
spring  14.  By  turning  the  aforesaid  gage-screw  15  out  or  in,  the  length  of  the  portion  of  wire  intro 
duced  at  each  operation  of  the  feeder  may  be  graduated  according  to  the  proposed  length  of  the  pin 


When  in  the  rotation  of  the  cam  a its  rib  al  comes  against  the  plate  115  of  the  lever  11,  it  crowds  the 
lower  end  of  said  lever  back  in  the  direction  of  the  length  of  the  shaft  B,  so  as  to  press  its  upper  o1' 
forked  end  against  the  cap  10,  pressing  said  cap  against  the  wire,  so  that  the  wire  is  embraced  and 
firmly  held  between  said  cap  10  and  the  face  of  the  slide  9.  and  while  the  wire  continues  to  be  held  the 


PIN-MAKING  MACHINE. 


491 


rising  face  on  the  periphery  of  the  cam  a comes  against  the  stud  1 \d  of  the  lever  1 1,  crowding  the  low  sr 
end  of  said  lever  back  in  a direction  at  right  angles  to  the  length  of  the  shaft  B,  and  consequently 
carrying  forward  the  upper  or  forked  end  of  said  lever,  which,  holding  on  to  the  stud  9c  of  the  feeder  bj 
the  fork  in  its  end,  carries  forward  the  feeder,  holding  the  wire  in  the  manner  above  described. 

In  the  regular  operation  of  the  machine,  where  the  wire  is  carried  forward  by  the  feeder,  the  end  of 
the  wire  enters  one  of  the  pointing  chucks  hereinafter  described,  which  is  in  readiness  to  receive  it;  and 
in  order  to  insure  the  entrance  thereof  a guide  is  placed  near  the  extremity  of  said  chuck : said  guide  is 
in  the  form  of  a hollow  cone,  having  its  apex  directed  towards  the  chuck,  and  its  base  towards  the 
feeder.  There  must  be  a perforation  at  the  apex  of  the  cone  to  allow  the  wire  to  pass  through  in  a 
straight  line  from  the  feeder  to  the  chuck ; and  there  must  also  be  an  opening  made  in  its  side  to  allow 
the  chuck  to  carry  the  pin,  or  wire,  out  laterally : said  guide  may  be  attached  to  the  cutter-staud  or  any 
convenient  part  of  the  faxed  frame. 


Before  the  concentric  face  a3,  before  described,  of  the  cam  d,  leaves  the  etud  11  d,  the  rib  dl  of  said 
^am  will  leave  the  plate  116,  so  as  to  allow  the  spring  II  to  retract  the  forked  end  of  the  lever  11  from 
the  cap  10 ; and  afterwards  said  high  concentric  part  of  the  cam  a passing  away  from  the  stud  11a,  will 
leave  the  feeder  free  to  be  carried  back  by  the  action  of  the  spring  II,  till  it  is  stopped  by  coming 
against  the  gage-screw  15.  The  apparatus  for  cutting  off  the  wire,  and  also  for  holding  it  after  it  has 
been  introduced  by  the  feeder,  while  the  feeder  is  going  back  and  renewing  its  grasp  on  the  wire,  in 
order  to  introduce  another  succeeding  portion  of  wire,  is  supported  by  and  consists  in  part  of  an  ad  ■ 
justable  frame-piece  or  stand,  which  is  fastened  by  a screw  on  the  top  of  the  portion  AI  of  the  fixed 
frame,  close  behind  the  frame  8 of  the  feeding  apparatus,  as  represented  in  Fig.  3063.  At  the  interior 
extremity  of  the  stand  16  it  has  a portion  16a  which  extends  across  in  front  of  the  interior  extremity  of 


492 


PIN-MAKING  MACHINE. 


(lie  portion  8 d of  the  feeder-frame,  furnishing  in  front  towards  the  vertical  shaft  c (or  the  centre  of  the 
revolving  table  D)  a vertical  plain  surface  at  right  angles  to  the  line  in  which  the  wire  is  fed  into  the 
machine.  To  the  aforesaid  vertical  face  of  the  portion  16<i  of  the  cutter-stand  is  fitted  a steel  plate 
This  plate  has  a hole  through  it  of  a suitable  size  and  in  a proper  situation  to  let  the  wire  pass 
through  it  in  a straight  line  from  the  feeder  to  the  pointing  chuck,  into  which  chuck  the  wire  enters, 
previous  to  a portion  of  it  being  cut  off  to  form  a pin.  A steel  cutter  18  is  fitted  into  a groove  or 
socket  in  the  cutter-stock  19,  so  as  to  admit  of  its  being  adjusted  and  fixed  therein  by  screws,  and  tc 
cause  the  cutting  edge  of  said  cutter  to  lie  flat  against  the  plate.  The  cutter-stock  19  is  jointed  to  the 
vertical  portion  1 (id  of  the  cutter-stand  by  means  of  a centre-screw  22,  so  that  19  forms  the  short  arm 
of  which  19 d forms  the  long  arm. 


A small  projection  or  plate  19c  extending  from  the  edge  of  the  arm  1 9c?  of  said  lever  rests  upon  the 
periphery  of  the  cutter-cam  6,  and  a stud  standing  out  laterally  from  said  arm  19<6  at  right  angles  tc 
the  plane  of  its  motion  on  its  centre  22,  rests  against  the  side  of  said  cam  b , on  which  side  the  acting 
parts  of  said  cam  are  formed.  The  cam  b is  circular  and  concentric  with  the  shaft  B on  which  it  is 
fixed,  and  has  its  acting  parts  formed  on  the  side  of  it  next  to  the  aforesaid  stud  of  the  lever  19. 
61  is  a recess  or  low  part,  which  is  connected  by  an  inclined  portion  at  one  of  its  extremities  to  the 
raised  part  62,  and  at  its  other  extremity  to  the  tooth  or  pivot  63  ; the  portion  or  face  62  is  a plain 
surface  coinciding  with  the  plane  in  which  the  cam  6 revolves ; and  the  tooth  63  is  a wedge-shaped 
projection  raised  upon  one  extremity  of  the  face  62.  A spiral  spring  235,  which  connects  the  extrem- 
ity of  the  arm  19 d with  the  fixed  frame,  serves  to  draw  said  arm  in  a direction  contrary  to  that  in 
winch  it  is  moved  by  the  action  of  the  cam  6,  and  to  retract  the  cutter  immediately  after  its  action 


PIN-MAKING  MACHINE. 


493 


in  cutting  off  the  wire.  The  cam  6 must  be  adjusted  on  the  shaft  B,  in  reference  to  the  feeder-cam  d,  sc 
that  its  recess  or  low  part  61  will  be  opposite  the  stud  of  the  lever  19  during  the  time  in  which  the 
said  cam  d is  engaged  in  carrying  forwards  the  feeder  to  feed  in  the  wire;  and  while  the  cam  d con- 
tinues to  hold  the  feeder  in  its  advanced  position,  and  before  the  feeder  relaxes  its  hold  upon  the  wire, 
iu  the  manner  before  described,  the  face  62  of  the  cutter-cam  must  arrive  at  the  stud  of  the  lever  19, 
so  as  to  cause  the  cutter  18  to  close  upon  the  wire  and  hold  it  without  cutting  it  off;  and  while  the  face 
62  of  the  cutter-cam  is  passing  the  stud,  and  before  the  tooth  63  reaches  said  stud,  the  feeder  must 
relax  its  grasp  on  the  wire ; and  then  before  the  feeder  begins  to  advance,  and  while  it  remains  station- 
ary in  its  retracted  position,  the  tooth  63  of  the  cutter-cam  must  pass  the  stud,  by  which  the  cutter  18 
will  be  suddenly  further  advanced  to  cut  off  the  wire  close  to  the  face  of  the  plate,  against  which  the 
flat  side  of  the  cutter  plays,  and  by  the  reaction  of  the  spring  235  the  stud  will  be  drawn  against  the 


low  part  61  of  the  cutter-cam,  so  as  to  retract  the  cutter  18  out  of  the  way,  to  allow  the  feeder  to  intro- 
duce another  succeeding  portion  of  wire.  The  length  of  wire  fed  in  and  cut  off  at  each  operation  ot 
the  feeding  and  cutting  apparatus  is  equal  to  the  length  of  the  pin  to  be  made,  and  a portion  of  wire 
sufficient,  by  being  raised  or  upset  and  properly  compressed  between  suitable  dies,  to  form  the  head 
of  the  pin. 

Of  the  pointing-chucks  and  revolving  table,  and  other  parts  accessor g to  their  movements. — In  the  pro- 
cess of  sharpening  the  points  of  the  pins  made  by  the  machine  herein  described,  the  piece  of  wire 
is  held  and  turned  round  by  a chuck  formed  at  the  extremity  of  a revolving  axis,  in  a manner  similar  to 
that  in  which  a piece  of  work  is  held  and  turned  in  the  chuck  of  a turning-lathe ; but  the  end  of  the 
wire  is  reduced  to  the  requisite  tapering  and  pointed  form  by  the  grinding  action  of  circular  revolving 


files,  and  not  by  the  point  or  edge  of  a tool,  as  in  the  common  operation  of  turning.  There  are  eight 
such  chucks,  mounted  in  suitable  bearings  on  a revolving  table  D.  The  revolving  table  D is  placed  in 
a horizontal  position  on  the  vertical  shaft  c , as  is  shown  in  Figs.  3063,  3064,  and  3068.  It  has  a hole 
in  its  centre  fitted  to  said  shaft,  so  as  to  allow  said  shaft  to  revolve  while  the  table  is  at  rest,  and  to 
allow  said  table  to  move  round  said  shaft  on  its  axis  or  centre  of  motion,  when  said  table  moves  round 
by  an  intermitting  motion.  The  upper  horizontal  face  of  said  table  furnishes  plane  surfaces  to  which 
are  fitted  and  fastened,  by  screws,  the  bearings  or  boxes  of  the  pointing-chucks  28,  and  said  table  has  on 
its  back  or  under  side  a hub,  which  rests  upon  a collar  on  the  shaft  c,  and  which  is  also  fitted  into  a 
hole  iu  the  middle  of  the  girt  A6.  It  has  on  its  under  side,  near  its  circumference,  a rim  extending  ver 


494 


PIN-MAKING  MACHINE. 


tically  downwards,  which  is  divided  at  its  lower  edge  into  eight  equal  divisions  or  teeth,  similar  to  saw 
teeth,  as  is  shown  in  Fig.  3068.  In  said  Fig.  3068  the  above-described  rim  is  represented  in  section 
with  all  the  other  parts  of  the  table  removed,  in  order  to  show  the  aforesaid  divisions  or  teeth,  which  are 
marked  in  the  figure  D 1 to  8. 

There  is  a semicircular  groove  formed  around  the  circumference  of  the  aforesaid  rim,  above  the  bot 
toms  of  its  teeth,  to  receive  the  clip-band  ef.  The  clip-band  ef  is  formed  of  a band  of  round  iron  or 
wire  of  a size  to  fit  the  aforesaid  groove.  The  ends  of  said  rod  e (being  straight)  are  passed  through 
eyes  in  the  yokes  / and  are  secured  in  that  situation  by  nuts  which  are  screwed  on  to  said  ends  of  the 


rod  e.  The  yoke/  is  placed  in  a horizontal  position,  and  presents  towards  the  table  D a concave  side, 
which  is  fitted  to  the  groove  in  the  rim  of  said  table.  Said  yoke  /has  a vertical  shot  formed  through 
it,  the  longitudinal  centre  of  wliich  is  in  continuation  of  a right  line  extending  horizontally  outwards 
from  the  centre  of  the  axis  c.  By  means  of  a stud  23  which  extends  upwards  in  a perpendicular  direction 
through  the  aforesaid  shot  in  yoke/,  from  the  end  of  the  lever  g to  which  said  stud  is  attached,  a con- 
nection is  formed  between  said  yoke  /and  said  lever  g,  so  that  when  said  lever  g is  moved  horizontally 


to  the  right  or  left  hand,  it  communicates  a corresponding  movement  to  said  yoke.  The  lever  g is 
connected  by  a vertical  axis  24  to  the  fixed  frame,  as  is  shown  also  at  24  in  Figs.  3063  and  3064 : it 
has  a broad  part  in  which  is  a slot  or  opening  of  sufficient  dimensions  to  allow  the  shaft  c to  pass  through 
it,  and  to  allow  said  lever  to  move  forwards  and  backwards  to  a certain  extent  around  its  axis  24.  A 
stud  26  is  attached  to  the  broad  part  of  the  lever  g,  in  a suitable  position  to  receive  the  action  of  the 
cam  /t,  which  is  fixed  on  the  vertical  shaft  c.  The  cam  h has  two  eccentric  faces  on  its  periphery,  viz., 
the  longer  face  hi  which  extends  around  three-fourths  of  the  circle  of  the  periphery ; and  the  shorte» 


PIPE  MACHINE,  LEAD. 


495 


face  h2  which  occupies  one-fourth  of  said  circle.  A spring  26  connects  the  end  of  the  lever  g with  the 
fixed  frame,  and  draws  said  lever  in  such  a direction  as  to  incline  the  stud  25  of  said  lever  inwards  to- 
wards the  vertical  axis  c. 

In  the  machine  herein  described  the  cam  h is  placed  beneath  the  lever  g,  and  the  stud  25  is  affixed  to 
the  under  side  of  said  lever.  In  Fig.  3068  said  cam  li  is  represented  above  said  lever,  and  the  stud  25 
affixed  to  its  upper  side,  in  order  to  show  the  action  of  said  cam  upon  said  stud. 

There  is  a spring-catch  27  attached  to  the 
girt  A6,  which  allows  the  table  D to  move 
round  freely  in  the  direction  of  the  arrow,  by 
yielding  under  the  inclined  faces  of  the  teeth 
D of  said  table ; but  which  prevents  or  arrests 
a retrograde  movement  of  said  table,  by 
springing  up  behind  the  perpendicular  faces 
of  said  teeth  and  catching  against  one  of  said 
perpendicular  faces  if  an  effort  be  made  to 
move  said  table  in  a retrograde  direction. 

The  table  moves  forwards  around  the  axis  c 
in  the  direction  indicated  by  the  arrow  marked 
on  the  rim  d of  said  table,  as  shown  in  Fig. 

3068,  one-eighth  of  a revolution  at  each  rev- 
olution of  the  shaft  c.  It  occupies  one-fourth 
of  the  time  of  a revolution  of  the  shaft  c in 
making  said  movement,  and  it  remains  at  rest 
during  three-fourths  of  the  time  of  a revolu- 
tion of  said  shaft  c.  The  aforesaid  alternate 
periods  of  motion  and  rest  of  the  table  D are 
produced  by  the  above-described  combina- 
tion, which  is  marked  in  the  figures  referred 
to  in  the  foregoing  description  with  the  fol- 
lowing letters  and  figures:  C,  D,  d,  (1  to  8,) 

«,/,  23,  g,  24,  Al,  A4,  A6,  27 h,  (1  to  3,)  25,  26, 
in  the  following  manner  : that  is  to  say,  sup- 
posing all  the  parts  of  the  aforesaid  combi- 
nation which  are  shown  in  the  figures  to  be 
in  the  positions  relatively  to  each  other  in 
which  they  are  represented,  and  that  the 
shaft  c and  the  cam  h are  in  the  act  of  re- 
volving in  the  direction  indicated  by  the  ar- 
rows ; the  face  hi  of  the  cam  h advancing 
against  the  stud  25  of  the  lever  g,  will  carry 
back  said  lever,  and  with  it  the  clip-band 
fe\  but  the  table  D will  be  prevented  from  moving  back  along  with  the  clip-band  ef  in  consequence 'ol 
the  tooth  of  said  tabic  being  arrested  by  the  catch  27 ; consequently  the  clip-band  will  slip  round  in 
the  groove  of  said  table  D,  and  said  table  D will  remain  stationary. 

FIPE  MACHINE,  LEAD.  Until  1820  lead  pipe  was  manufactured  by  casting  and  drawing 
something  similar  to  the  process  of  wire-drawing.  In  1820,  Burr  took  out  a patent  in  England 
on  the  following  plan : (in  these  figures,  so  much  of  the  machine  is  represented  as  is  essentia) 
3077  3078  3080 


496 


PISE-WORK. 


to  illustrate  tlie  principle  of  its  action,  without  aiming  at  accuracy  rf  detail.)  A hollow  cylinder  c,  of 
cast  iron  (fig.  3077)  is  furnished  with  a steel  die  d,  of  the  shape  and  dimensions  of  the  outside  of  the  pro- 
posed pipe.  A solid  piston  or  ram  r,  of  cast  iron,  fits  this  hollow  cylinder  as  snugly  as  possible,  without 
friction.  To  the  bottom  of  this  piston  is  affixed  a steel  mandril  or  core  m , of  the  length  of  the  cylinder, 
and  of  the  diameter  of  the  bore  of  the  proposed  pipe.  IVhen  this  piston  is  withdrawn  from  the  cylinder, 
the  point  of  the  mandril  is  just  within  the  die  at  the  bottom  of  the  cylinder.  The  cylinder  is  then  filled 
with  melted  lead,  which  is  allowed  to  set.  By  the  action  of  a hydrostatic  press  the  cylinder  is  then 
raised  between  guides,  or  the  piston  lowered  (it  matters  not  which),  and  the  solid  lead  is  forced  by  the 
action  of  the  piston  through  the  die,  and  enveloping  the  mandril  runs  off  the  point  of  the  latter  as  lead 
pipe.  This  action  continues  until  the  piston  has  reached  the  bottom  of  the  cylinder,  when  the  mandril 
projects  nearly  its  whole  length  through  the  bottom  of  the  cylinder. 

This  was  a great  improvement  on  the  old  method  of  drawing,  but  yet  accompanied  with  some  objec- 
tions, one  of  the  most  prominent  being  that,  for  small  pipe,  the  mandril  lacked  stiffness  to  preserve  itsell 
from  derangement,  and  the  pipe  in  consequence  was  irregular  in  its  thickness. 

To  obviate  this,  Hanson  took  out  a patent  in  Aug.,  1837,  the  principle  of  which  was,  that  the  mandril 
was  short,  and  instead  of  being  fixed  to  the  bottom  of  the  piston  or  ram,  as  before,  was  fixed  within 
the  cylinder,  and  a few  inches  from  the  die  to  a plate  or  diaphragm,  stretched  across  the  cylinder  a 
(fig.  3078).  The  mandril  in  this  case  being  immovably  fixed  concentric  with  the  die.  To  enable  the  lead 
to  arrive  at  the  die  and  mandril,  this  diaphragm  or  “ bridge  ” was  perforated  by  four  large  holes,  shown 
in  plan  fig.  3079,  through  which  the  lead  in  a solid  state  was  forced  by  the  action  of  the  ram,  but  united 
again  after  passing  the  bridge  and  before  reaching  the  die  and  mandril  poiut. 

By  this  means,  it  is  true,  the  irregularity  of  the  action  of  the  man- 
dril in  Burr’s  plan  was  avoided,  but  at  a great  expense  of  power,  and 
the  pipe  made  was  inferior,  the  lead  not  uniting  after  passing  the 
bridge  so  perfectly,  but  that  the  pipe  manufactured  by  this  machine 
would  split  at  the  points  corresponding  to  the  divisions  of  the  “ bridge.”  , 
To  overcome  this  difficulty,  as  well  as  that  of  Burr’s,  was  the  object 
of  the  patent  of  Tateham,  dated  Oct.,  1841,  in  which  the  piston  is 
truly  bored  from  end  to  end,  and  a larger  mandril  or  shaft  (fig.  3080) 
fitted  within,  nearly  of  the  length  of  the  cylinder,  into  the  bottom  of 
which  is  fixed  the  short  core  or  mandril  for  the  bore  of  the  pipe,  the 
mandril  remaining  as  in  Hanson’s  plan,  fixed  just  within  the  die. 

As  the  hollow  piston  descends*  upon  the  lead  (the  mandril  shaft 
rising  meanwhile  within  it),  the  latter  is  forced  around  the  shoulder  of 
the  mandril,  and  so  through  the  die  into  pipe. 

At  first  sight,  and  in  model,  this  plan  would  appear  to  he  very  effec- 
tual, but  in  practice  it  is  attended  with  some  objections,  the  principal 
of  which  is  the  difficulty  of  preserving  the  smooth,  and  at  the  same 
time  tight  action  of  the  hollow  piston,  and  the  mandril  shaft  moving 
within  ir. 

It  will  be  readily  foreseen  that  the  great  power  necessary  for  the 
manufacture  of  pipe,  will  force  the  lead  between  the  mandril  shaft  and 
the  bore  of  the  piston,  increasing  the  friction  to  a very  great  extent. 

Cornell’s  improvements  consist  simply  in  making  the  pipe  from  that 
action  of  the  power,  and  not  to  move  the  mass  of  compressed  lead 
through  the  cylinder  to  the  die.  This  is  effected  by  making  the  piston  or  ram  a die  holder,  and  hollow, 
and  affixing  the  mandril  to  the  bottom  of  the  cylinder,  and  extending  it  to  the  die  in  the  piston  bottom 
(fig.  3081).  The  effect  is  evident. 

The  instant  the  piston  commences  its  movement,  pipe  is  formed  a t the  die,  at  one  half  the  expenditure 
of  power  necessary  when  the  mass  of  lead  is  moved  through  the  cylinder. 

PISE-WOBK.  A method  of  constructing  very  durable  walls  of  kneaded  earth.  Any  kind  of  earth 
that  will  sustain  itself  with  a small  slope,  is  adapted  to  the  purpose ; but  that  best  suited  to  it  is  clay, 
containing  small  gravel  of  sufficient  consistence  to  be  dug  with  a spade.  It  is  first  well  beaten,  then 
screened  to  separate  stones  larger  than  a common  hazel  nut ; after  which,  it  is  wetted  sufficiently  to 
enable  it  to  retain  the  form  given  to  it  by  kneading  between  the  fingers.  It  is  now  fit  for  use,  and  in 
applying  it  to  build  a wall,  a sort  of  movable  box  or  mould  is  made  for  the  intended  wall,  of  deal  planks 
put  together  with  their  joints  ploughed,  and  tongued,  and  strengthened  with  clamps  on  the  outside. 
These  frames  rest  on  cross  pieces  or  putlocks,  which  pass  through  the  thickness  of  the  wall,  and  near 
the  ends  are  mortices,  into  which  are  placed  upright  pieces,  secured  by  wedges  at  the  bottom,  and  tied 
with  ropes.  These  uprights  are  set  to  the  intended  thickness  of  the  wall,  which  is  about  £0  inches  at 
bottom,  and  gradually  diminishes  upwards.  The  frames  are  steadied  at  the  top  by  means  of  cross 
sticks  or  struts,  and  the  ropes  are  made  tight  by  twisting  them  with  a small  piece  of  wood  placed  be- 
tween the  folds.  The  frames  being  properly  fixed,  the  earth  is  thrown  in,  and  worked  like  concrete  or 
mortar ; to  allow  the  putlocks  to  be  readily  withdrawn,  the  parts  about  them  must  be  well  wetted. 

In  commencing  a wall,  the  first  frame  is  put  at  one  of  the  extremities,  and  the  end  of  the  frame  closed 
by  planks  secured  by  iron  cramps ; at  the  other  part,  where  there  is  no  end,  the  wall  is  to  be  sloped  off 
at  an  angle  of  about  60°,  for  facility  in  joining  on  the  next  piece.  In  commencing  the  work,  the  bottom 
being  well  cleaned  and  sprinkled  with  water,  the  laborers  bring  the  masons  the  prepared  earth,  and 
tread  it  with  their  feet  into  a bed  3 or  4 inches  thick ; they  then  ram  it  down  with  a rammer.  In  ram- 


* Tor  convenience,  we  assume  that  the  piston  descends  in  all  these  machines,  as  it  matters  butlittle  iD  elucidating 
the  principle  whether  the  piston  descends  or  the  cylinder  ascends,  but  the  former  method  is  more  easily  compre- 
hended. • 


part  of  the  lead  subjected  to  the 


PLANES  AND  PLANING  MACHINES. 


497 


ming,  it  is  turned  round  at  each  stroke,  so  as  to  make  the  work  more  compact,  and  unite  it  with  tha 
previously  done.  By  means  of  the  rammer,  the  first  layer  is  reduced  in  thickness  about  one  half,  and 
on  this  compressed  bed  another  layer  is  spread  out,  and  beaten  in  the  same  manner,  and  so  on,  until  the 
case  is  filled.  The  frame  is  then  taken  down,  and  moved  further  on,  so  that  the  plank  entirely  covers 
the  inclined  part.  Lintels  are  placed  over  all  the  apertures,  and  the  finished  portions  are  left  for  some 
months  to  dry.  The  surface  may  then  be  coated  with  plaster,  and  the  wall  is  finished. 

Cob  walls,  as  they  are  termed  in  Devonshire,  resemble  pise-work  ; they  are  formed  of  clay,  loam,  and 
chopped  straw,  and  are  generally  2 feet  thick,  resting  on  brick  or  stone  foundations,  3 or  4 feet  above 
the  level  of  the  soil ; they  must  he  carried  up  at  several  times,  and  not  he  hurried.  After  each  addition 
the  sides  are  carefully  pared  down  with  an  iron  cob  parer,  which  resembles  a baker’s  peel.  When  dry, 
it  is  coated  with  fine  stucco  or  plaster,  and  if  kept  dry  at  its  top  and  foundation,  it  is  very  durable. 

Walls  similar  to  pise-work  are  sometimes  made  in  this  country  with  cement  of  lime  or  cement  mor- 
tar, and  small  stones  or  screenings;  the  interior  plastering  being  laid  directly  on  the  walls,  the  outer 
being  usually  left  in  its  rough  cast  state  ; the  timbers  for  the  floors  are  inserted  as  the  wall  progresses. 

PISTOL.  See  Gun. 

PISTON.  See  Pump — Engine,  etc. 

PLANES  AND  CHISELS.'*  If  we  drive  an  axe,  or  a thin  wedge,  into  the  centre  of  a block  of  wood, 
it  will  split  the  same  into  two  parts  through  the  natural  line  of  the  fibres,  leaving  rough  uneven  surfaces, 
and  the  rigidity  of  the  mass  will  cause  the  rent  to  precede  the  edge  of  the  tool.  The  same  effect  will 
partially  occur,  when  we  attempt  to  remove  a stout  chip  from  off  the  side  of  a block  of  wood  with  the 
hatchet,  adze,  paring  or  drawing  knife,  the  paring  chisel,  or  any  similar  tool.  So  long  as  the  chip  is 
too  rigid  to  bend  to  the  edge  of  the  tool,  the  rent  will  precede  the  edge ; and  with  a naked  tool,  the 
splitting  will  only  finally  cease,  when  the  instrument  is  so  thin  and  sharp,  and  it  is  applied  to  so  small  a 
quantity  of  the  material,  that  the  shaving  can  bend  or  ply  to  the  tool,  and  then  only  will  the  work  be 
cut,  or  will  exhibit  a time  copy  of  the  smooth  edge  of  the  instrument,  in  opposition  to  its  being  split  or 
rent,  and  consequently  showing  the  natural  disruption  or  tearing  asunder  of  the  fibres. 

The  axe  or  hatchet  with  two  bevils,  is  intended  for  hewing  and  splitting,  when  applied  to  paring  the 
surface  of  a block,  must  he  directed  at  the  angle,  which  would  be  a much  less  convenient  and  less  strong 
position  than  that  of  the  side  hatchet  with  only  one  chamfer ; but  for  paring  either  a very  large  or  a 
nearly  horizontal  surface,  the  side  hatchet  in  its  turn  is  greatly  inferior  to  the  adze,  in  which  the  handle 
is  elevated  at  some  CO  or  70  degrees  from  the  ground,  the  preference  being  given  to  the  horizontal  po- 
sition for  the  surface  to  he  wrought.  The  instrument  is  held  in  both  hands,  wLilst  the  operator  stands 
upon  his  work  in  a stoc  'ing  position,  the  handle  being  from  twenty-four  to  thirty  inches  long,  and  the 
weight  of  the  blade  from  two  to  four  pounds. 

The  chisel  admits  of  being  very  carefully  placed,  as  to  position,  and  when  the  tool  is  strong,  very  flat, 
and  not  tilted  up,  it  produces  very  true  surfaces,  as  seen  in  the  mouths  of  planes.  The  chisel  when 
applied  with  percussion,  is  struck  with  a wooden  mallet,  but  in  many  cases  it  is  merely  thrust  forward 
by  its  handle.  The  paring-knife,  exhibits  also  a peculiar  but  most  valuable  arrangement  of  the  chisel, 
in  which  the  thrust  obtains  a great  increase  of  power  and  control ; and  in  the  drawing-knife,  the  narrow 
transverse  blade  and  its  two  handles  form  three  sides  of  a rectangle,  so  that  it  is  actuated  by  'traction, 
instead  of  by  violent  percussion  or  steady  thru® 

The  chisel,  when  inserted  in  one  of  the  several  forms  of  stocks  or  guides,  becomes  the  plane,  the 
general  objects  being  to  limit  the  extent  to  which  the  blade  can  penetrate  the  wood,  to  provide  a defini- 
tive guide  to  its  path  or  direction,  and  to  restrain  the  splitting  in  favor  of  the  cutting  action.  In  gene- 
ral, the  sole  or  stock  of  the  plane  is  in  all  respects  an  accurate  counterpart  of  the  form  it  is  intended  to 
produce.  Although  convex  surfaces,  such  as  the  outside  of  a hoop,  may  be  wrought  by  any  of  the 
straight  planes,  applied  in  the  direction  of  a tangent,  it  is  obvious  the  concave  plane  would  be  more  con- 
venient. For  the  inside  of  the  hoop,  the  radius  of  curvature  of  the  plane,  must  not  exceed  the  radius 
of  the  work.  For  the  convenience  of  applying  planes  to  very  small  circles,  some  are  made  very  narrow 
or  short,  and  with  transverse  handles,  such  as  the  plane  for  the  hand-rails  of  staircases.  The  sections 
of  planes  are  also  either  straight,  concave,  convex,  or  mixed  lines,  and  suited  to  all  kinds  of  specific 
mouldings,  hut  we  have  principally  to  consider  their  more  common  features,  namely,  the  circumstances 
of  their  edges  and  guides ; first,  of  those  used  for  flat  surfaces,  called  by  the  joiners  bench  planes , 
secondly,  the  grooving  planes ; and  thirdly,  the  moulding  planes.  The  various  surfacing  planes  are  nearly 
alike,  as  regards  the  arrangement  of  the  iron,  the  principal  differences  being  in  their  magnitudes.  Thus 
the  maximum  width  is  determined  by  the  average  strength  of  the  individual,  and  the  difficulty  of 
maintaining  with  accuracy  the  rectilinear  edge.  In  the  ordinary  bench  planes  the  width  of  the  iron 
ranges  from  about  2 to  2^  inches  j 

The  lengths  of  planes  are  principally  determined  by  the  degree  of  straightness  that  is  required  in  the 
work,  and  which  may  be  thus  explained.  The  joiner's  plane  is  always  either  balanced  upon  one  point 
beneath  its  sole,  or  it  rests  upon  two  points  at  the  same  time,  and  acts  by  cropping  off  these  two  points, 
without  descending  to  the  hollow  intermediate  between  them.  It  is  therefore  clear,  that  by  supposing 
the  work  to  he  full  of  small  undulations,  the  spokeshave,  which  is  essentially  a very  short  plane , would 
descend  into  all  the  hollows  whose  lengths  were  less  than  that  of  the  plane,  and  the  instrument  is  there- 
fore commonly  used  for  curved  lines.  But  the  greater  the  length  of  the  plane,  the  more  nearly  would 
its  position  assimilate  to  the  general  line  of  the  work,  and  it  would  successively  obliterate  the  minor 
errors  or  undulations ; and  provided  the  instrument  were  itself  rectilinear,  it  ivould  soon  impart  that 
character  to  the  edge  or  superficies  submitted  to  its  action.  The  following  table  may  be  considered  to 
contain  the  ordinary  measures  of  surfacing  planes. 

* Holtzapfel. 

t The  “ iron,”  is  scarcely  a proper  name  for  the  plane-iron , which  is  a cutter  or  blade,  composed  partly  of  iros 
end  steel ; hut  no  confusion  can  arise  from  the  indiscriminate  use  of  any  of  these  terms. 

Vol.  11—32 


408 


PLANES  AND  PLANING  MACHINES. 


Names  of  Planes. 

Length 

is  it 

i inches. 

Width: 

; in  inches. 

Widths 

of  irons 

Modelling  Planes,  like  Smoothing  Planes 

1 

to 

5 — 

4 

to 

2 

— 8-16 

to 

11 

Ordinary  Smoothing  Planes  . 

6* 

to 

8 — 

2* 

to 

8 4 

— 14 

to 

24 

Rebate  Planes  . .... 

»4  - 

“1 

to 

2 

— 4 

to 

2 

Jack  Planes  .....  . 

12 

to 

IT  — 

24 

to 

3 

— 2 

to 

2J 

Panel  Planes  ..... 

144 

— 

?4 

- 24 

Trying  Planes  ....  . . 

20 

to 

22  — 

84 

to 

35 

— 24 

to 

44 

Long  Planes  ....... 

24 

to 

26  - 

84 

— 24 

Jointer  Planes  ....... 

28 

to 

80  — 

34 

- 34 

Cooper’s  Jointer  Planes  ..... 

. CO 

to 

T2  — 

5 

to 

54 

- 34 

to 

31 

The  succession  in  which  they  are  generally  used, 

is  the  jack  plane  for 

Ihe  coarser  w 

ork,  the 

trying 

plane  for  finer  work  and  trying  its  accuracy,  and  the  smoothing  plane  for  finishing. 

The  mouth  of  the  plane  is  in  the  narrow  aperture  between  the  face  of  the  iron,  and  the  wear,  or  face  of 
the  mortise;  the  angle  between  these  should  be  as  small  as  possible,  in  order  that  the  wearing  away 
of  the  sole,  or  its  occasional  correction,  may  cause  but  little  enlargement  of  the  mouth  of  the  plane ; at 
the  same  time  the  angle  must  be  sufficient  to  allow  free  egress  for  the  shavings,  otherwise  the  plane  is 
said  to  choke.  In  all  the  bench  planes  the  iron  is  somewhat  narrower  than  the  stock,  and  the  mouth  is 
a wedge-formed  cavity ; in  some  of  the  narrow  planes  the  cutting  edge  of  the  iron  extends  the  full 
width  of  the  sole,  as  in  the  rebate  plane. 

The  amount  of  force  required  to  work  each  plane  is  dependent  on  the  angle  and  relation  of  the  edge, 
»n  the  hardness  of  the  material,  and  on  the  magnitude  of  the  shaving;  but  the  required  force  is  in 
addition  greatly  influenced  by  the  degree  in  which  the  shaving  is  bent  for  its  removal  in  the  most  perfect 
manner.  The  spokeshave  cuts  perhaps  the  most  easily  of  all  the  planes,  and  it  closely  assimilates  to 
the  penknife ; the  angle  of  the  blade  is  about  25  degrees,  one  of  its  planes  lies  almost  in  contact  with 
the  work,  the  inclination  of  the  shaving  is  slight,  and  the  mouth  is  very  contracted.  The  spokeshave 
works  very  easily  in  the  direction  of  the  grain,  but  it  is  only  applicable  to  small  and  rounded  surfaces, 
and  cannot  he  extended  to  suit  large  flat  superficies,  as  the  sole  of  the  plane  cannot  be  cut  away  for 
such  an  iron,  and  the  perfection  of  the  moutii  is  comparatively  soon  lost  in  grinding  the  blade.  Plane 
irons  are  usually  ground  at  the  angle  of  25'°,  and  sharpened  on  the  more  refined  oilstone  at  35°,  so  as  to 
make  a second  bevil  or  slight  facet ; the  irons  so  ground  are  placed  at  the  angle  of  45°,  or  that  of 
common  pitch ; it  therefore  follows,  that  the  ultimate  bevil,  which  should  he  very  narrow,  lies  at  an  ele- 
vation of  10°  from  the  surface  to  be  planed.  In  the  planes  with  double  irons,  the  top  iron  is  not  intended 
to  cut,  but  to  present  a more  nearly  perpendicular  wall  for  the  ascent  of  the  shavings,  the  top  iron  more 
effectually  breaks  the  shavings,  and  is  thence  sometimes  called  the  break- iron.  Now  therefore,  the  shav- 
ing being  very  thin,  and  constrained  between  two  approximate  edges,  it  is  as  it  were  bent  out  of  the 
way  to  make  room  for  the  cutting  edge,  so  that  the  shaving  is  removed  by  absolute  cutting,  and  without 
being  in  any  degree  split  or  rent  off. 

Some  variation  is  made  in  the  angles  at  which  plane  irons  are  inserted  in  their  stocks.  The  spoke- 
shave is  the  lowest  of  the  series,  and  commences  with  the  small  inclination  of  25  to  30  degrees ; and 
the  general  angles,  and  purposes  of  ordinary  planes  are  nearly  as  follows.  Common  pitch,  or  45  de- 
grees from  the  horizontal  line,  is  used  for  all  the  bench  planes  for  deal  and  similar  soft  woods.  York 
pitch,  or  50  degrees  from  the  horizontal,  for  the  bencWdanes  for  mahogany,  wainscot,  and  hard  or 
stringy  woods.  Middle  pitch,  or  55  degrees,  for  mouldmg-planes  for  deal,  and  smoothing  planes  for 
mahogany,  and  similar  woods.  Half  pitch,  or  60  degrees,  for  moulding  planes  for  mahogany,  and 
woods  difficult  to  work,  of  which  bird’s-eye  maple  is  considered  one  of  the  worst. 

Boxwood,  and  other  close  hard  woods,  may  be  smoothly  scraped,  if  not  cut,  in  any  direction  of  the 
grain,  when  the  angle  constituting  the  pitch  entirely  disappears ; or  with  a common  smoothing-plane, 
in  which  the  cutter  is  perpendicular,  or  even  leans  slightly  forward ; this  tool  is  called  a scraping  plane , 
and  is  used  for  scraping  the  ivory  keys  of  piano-fortes,  and  works  inlaid  with  ivory,  brass,  and  hard- 
woods ; this  is  quite  analogous  to  the  process  of  turning  the  hard  woods.  The  cabinet-maker  also  em- 
ploys a scraping-plane,  with  a perpendicular  iron,  which  is  grooved  on  the  face,  to  present  a series  of 
fine  teeth  instead  of  a continuous  edge;  this,  which  is  called  a toothing  plane,  is  employed  for  roughing 
and  scratching  veneers,  and  the  surfaces  to  which  they  are  to  be  attached,  to  make  a tooth  for  the  better 
hold  of  the  glue.  The  smith’s-plane  for  brass,  iron,  and  steel,  has  likewise  a perpendicular  cutter, 
ground  to  70  or  80  degrees ; it  is  adjusted  by  a vertical  screw,  and  the  wedge  is  replaced  by  an  end 
screw  and  block. 

It  is  well  known  that  most  pieces  of  wood  will  plane  better  from  the  one  end  than  from  the  other,  and 
when  such  pieces  are  turned  over,  they  must  be  changed  end  for  end  likewise.  The  plane  working  with 
the  grain,  would  cut  smoothly,  as  it  would  rather  press  down  the  fibres  than  otherwise ; whereas,  against 
the  grain , it  would  meet  the  fibres  cropping  out,  and  be  liable  to  tear  them  up.  The  workman  will  ap- 
ply the  smoothing-plane  at  various  angles  across  the  different  parts  of  such  wood  according  to  his  judg- 
ment ; in  extreme  cases,  where  the  wood  is  very  curly,  knotty,  and  cross-grained,  the  plane  can  scarcely 
be  used  at  all,  and  such  pieces  are  finished  with  the  steel  scraper.  This  simple  tool  was  originally  a 
piece  of  broken  window-glass,  and  such  it  still  remains  in  the  hands  of  some  of  the  gun-stock  makers ; 
hut  as  the  cabinet-maker  requires  the  rectilinear  edge,  he  employs  a thin  piece  of  saw-plate.  The  edge 
is  first  sharpened  at  right  angles  upon  the  oilstone,  and  it  is  then  mostly  burnished,  either  square  or  at 
a small  angle,  so  as  to  throw  up  a trifling  burr,  or  wire-edge.  The  scraper  is  held  on  the  wood  at  about 
60°,  and  as  the  minute  edge  takes  a much  slighter  hold,  it  may  be  used  where  planes  cannot  be  well 
applied.  The  scraper  does  not  work  so  smoothly  as  a plane  in  perfect  order  upon  ordinary  wood,  and 
as  its  edge  is  rougher  and  less  keen,  it  drags  up  some  of  the  fibres,  and  leaves  a minute  roughness, 
interspersed  with  a few  longer  fibres. 

We  may  plane  across  the  grain  of  hard  mahogany  and  boxwood  with  comparative  facility,  as  the  fibres 
are  packed  so  closely,  like  the  loose  leaves  of  a book  when  squeezed  in  a press,  that  they  may  b»  cut  in 


PLANES  AND  PLANING  MACHINES. 


499 


nil  directions  of  the  grain  with  nearly  equal  facility,  both  with  the  flat  and  moulding  planes.  But  the 
weaker  and  more  open  fibres  of  deal  and  other  soft  woods,  cannot  withstand  a cutting  edge  applied  to 
them  parallel  with  themselves , or  laterally,  as  they  are  torn  up,  and  leave  a rough  unfinished  surface. 
The  joiner  uses  therefore,  for  deal  and  soft  woods,  a very  keen  plane  of  low  pitch,  and  slides  it  across 
obliquely,  so  as  to  attack  the  fibre  from  the  one  end,  and  virtually  to  remove  it  in  the  direction  of  its 
length ; so  that  the  force  is  divided  and  applied  to  each  part  of  the  fibre  in  succession.  The  moulding 
planes  cannot  be  thus  used,  and  all  mouldings  made  in  deal,  and  woods  of  similar  open  soft  grain,  are 
consequently  always  planed  lengthways  of  the  grain,  and  added  as  separate  pieces.  As  however  many 
cases  occur  in  carpentry,  in  which  rebates  and  grooves  are  required  directly  across  the  grain  of  deal,  the 
obliquity  is  then  given  to  the  iron , which  is  inserted  at  an  angle,  as  in  the  skew-rebate  and  fillister,  and 
the  stock  of  the  plane  is  used  in  various  ways  to  guide  its  transit. 

Moulding  planes. — All  the  planes  hitherto  considered,  whether  used  parallel  with  the  surfaces  as  in 
straight  works,  or  as  tangents  to  the  curves  as  in  curved  works,  are  applied  under  precisely  the  same 
circumstances  as  regards  the  angular  relation  of  the  mouth,  because  the  edge  of  the  blade  is  a right 
line  parallel  with  the  sole  of  the  plane  ; but  when  the  outline  of  the  blade  is  curved,  some  new  condi- 
tions arise  which  interfere  with  the  perfect  action  of  the  instrument.  It  is  now  proposed  to  examine 
these  conditions  in  respect  to  the  semicircle,  from  which  the  generality  of  mouldings  may  be  considered 
to  be  derived. 

A small  central  portion  may  he  considered  to  he  a horizontal  line ; two  other  small  portions  may  be 
considered  as  parts  of  vertical  dotted  lines,  and  the  intermediate  parts  of  the  semicircle  merge  from  the 
horizontal  to  the  vertical  line. 

The  reason  why  one  moulding  plane  figui-ed  to  the  half-round  cannot,  under  the  usual  construction, 
be  made  to  work  the  vertical  parts  of  the  moulding  with  the  same  perfection  as  the  horizontal,  exists  in 
the  fact,  that  whereas  the  ordinary  plane  iron  presents  an  angle  of  some  45  to  60  degrees  to  the  sole  of 
the  plane,  which  part  is  meant  to  cut,  it  presents  a right  angle  to  the  side  of  the  plane,  which  part  is 
not  meant  to  cut.  Thus  if  the  parts  of  the  iron  of  the  square  rebate  plane,  which  protrude  through 
the  sides  of  the  stock,  were  sharpened  ever  so  keenly,  they  would  only  scrape  and  not  cut,  just  the  same 
as  the  scraping  plane  with  a perpendicular  iron.  When,  however,  the  rebate  plane  is  meant  to  cut  at  the 
side,  it  is  called  the  side-rebate  plane,  and  its  construction  is  then  just  reversed,  that  is,  the  iron  is  in- 
serted perpendicularly  to  the  sole  of  the  plane,  but  at  an  horizontal  angle,  or  obliquely  to  the  side  of  the 
plane,  so  that  the  cut  is  now  only  on  the  one  side  of  the  plane,  and  which  side  virtually  becomes  the 
sole.  A second  plane  sloped  the  opposite  way,  is  required  for  the  opposite  side,  or  the  planes  are  made 
in  pairs,  and  are  used  for  the  sides  of  grooves,  and  places  inaccessible  to  the  ordinary  rebate  plane. 
The  square  rebate  plane,  if  applied  all  around  the  semicircle,  would  be  everywhere  effective  so  long  as 
its  shaft  stood  as  a radius  to  the  curve,  as  then  the  angle  of  the  iron  would  be  in  the  right  direction  in 
each  of  its  temporary  situations.  But  in  this  mode  a plane  to  be  effective  throughout,  demands  either 
numerous  positions  of  the  plane,  or  an  iron  of  such  a kind  as  to  combine  these  several  positions.  The- 
oretically speaking  therefore,  the  face  of  the  cutter  suitable  to  working  the  entire  semicircle  or  bead, 
would  become  a cone,  or  like  a tube  of  steel  bored  with  a hole  of  the  same  diameter  as  the  bead,  turned 
at  one  end  externally  like  a cone,  and  split  in  two  parts. 

As  all  the  imperfections  in  the  actions  of  moulding -planes  occur  at  the  vertical  parts,  there  is  a gen- 
eral attempt  to  avoid  these  difficulties  by  keeping  the  mouldings  flat,  or  nearly  without  vertical  lines. 
For  example,  concave  and  convex  planes,  called  hollows  and  rounds , include  generally  the  fifth  or  sixth, 
sometimes  about  the  third  of  the  circle ; and  it  is  principally  in  the  part  between  the  third  and  the 
semicircle  that  the  dragging  is  found  to  exist ; and  therefore,  when  a large  part  of  the  circle  is  wanted, 
the  plane  is  applied  at  two  or  more  positions  in  succession.  In  a similar  manner  large  complex  mould- 
ings often  require  to  be  worked  from  two  or  more  positions  with  different  planes,  even  when  none  of 
their  parts  are  undercut,  but  in  which  latter  case  this  is  of  course  indispensable.  And  in  nearly  all 
mouldings  the  plane  is  not  placed  perpendicularly  to  the  moulding,  but  at  an  angle  so  as  to  remove  all 
the  nearly  vertical  parts,  as  far  towards  the  horizontal  position  as  circumstances  will  admit. 

Planing  Machines  for  Wood. — In  using  hand-tools,  the  instrument  rests  immediately  upon  the  face 
of  the  work  under  formation  ; and  in  repeating  any  one  result,  the  same  careful  attention  is  again  re- 
quired in  every  successive  piece.  But  in  the  machines  acting  by  cutting,  the  accuracy  is  ensured  far 
more  readily,  by  running  either  the  work  or  the  tool,  upon  a straight  slide,  an  axis,  or  other  guide,  the 
perfection  of  which  has  been  carefully  adjusted  in  the  first  formation  of  the  machine  ; and  the  slide  or 
movement  copies  upon  the  work,  its  own  relative  degree  of  perfection.  The  economy  of  these  applica- 
tions is  therefore  generally  very  great,  and  they  are  frequently  most  interesting,  on  account  of  the 
curious  transitions  to  be  observed  from  the  hand-processes  to  the  machines,  in  some  cases  with  but  little, 
in  others  with  considerable  change  in  the  general  mode  of  procedure. 

The  first  planing  machine  for  wood  is  supposed  to  have  been  that  invented  by  General  Bentham, 
who  took  out  a patent  for  it  in  1791 ; it  was  based  on  the  action  of  the  ordinary  plane,  the  movements 
of  which  it  closely  followed.  This  contrivance  reduced  the  amount  of  skill  required  in  the  workman, 
but  not  that  of  the  labor ; it  appears  to  have  been  but  little  used.  The  board  to  be  planed  was  some- 
times laid  on  a bench,  at  other  times  fixed  by  long  cheeks  having  teeth,  which  penetrated  its  edges ; the 
iron  of  the  plane  extended  the  full  width  of  the  board,  and  the  stock  of  the  plane  had  slips  to  rest  on 
the  bench  and  check  the  cutting  action,  when  the  board  was  reduced  to  the  intended  thickness. 

For  feather-edged  boards,  the  two  slips  were  of  unequal  thicknesses;  for  those  intended  to  be  tape*- 
in  their  length,  the  guide  rails  had  a corresponding  obliquity,  and  were  fixed  to  the  bench.  The  plane 
was  moved  to  and  fro  by  a crank,  it  was  held  down  to  its  work  by  weights,  and  the  plane  was  lifted  up 
in  the  back  stroke  to  remove  the  friction  against  the  cutter. 

The  scale-board  plane,  abbreviated  into  scabbard-plane,  for  cutting  off  the  wide  chips  used  for  making 
hat  and  bonnet  boxes,  is  in  like  manner,  a plane  exceeding  the  width  of  the  board ; it  is  loaded  with 


PLANES  AND  PLANING  MACHINES 


500 


weights,  and  dragged  along  by  a rope  and  windlass,  the  projection  of  the  iron  determines  the  thicknesi 
of  each  shaving  or  scale-hoard.  This  construction  is  also  reversed,  by  employing  a fixed  iron,  drawing 
the  wood  over  it,  and  letting  the  scale-hoard  descend  through  an  aperture  in  the  bench  ; each  of  these 
modes  is  distinctly  based  on  the  common  plane. 

The  late  Mr.  Joseph  Bramah  took  out  a patent  in  1802  fora  planing  machine  for  wood;  one  of  which 
may  he  seen  in  the  Gun  Carriage  Department,  Woolwich  Arsenal.  The  timber  is  passed  under  a large 
horizontal  wheel,  driven  hy  the  steam  engine  at  about  ninety  revolutions  per  minute ; the  face  of  tint 
wheel  is  armed  with  a series  of  twenty-eight  gouges,  placed  horizontally  and  in  succession  around  it ; 
the  first  gouge  is  a little  more  distant  from  the  centre,  and  a little  more  elevated  than  the  next,  and  sc 
on.  The  finishing  tools  are  two  double  irons,  just  like  those  of  the  joiner,  but  without  the  advantage 
of  the  mouth. 

In  France,  planing  machines  for  wood  were  patented  as  early  as  1817-18  hy  M.  Roquin,  and  M. 
Manneville  in  1835.  The  first  was  intended  for  planing,  grooving,  and  tonguing,  and  moulding  for  the 
purpose  of  ornamant.  The  Board  was  placed  on  a platform  or  caariage,  adjustable  by  screws  to  suit 
different  thicknesses,  to  which  the  boards  or  planks  are  desire  to  be  reduced.  The  planes  were  “ cylin- 
drical rotating  planes.”  In  Manneville’s,  feed  rollers  were  introduced,  and  the  tonguing  and  grooving 
was  performed  by  circular  saws. 

In  this  country  the  most  successful  machine  for  planing  wood,  is  the  invention  of  Mr.  Woodworth, 
patented  in  1828,  and  reissued  in  1845  ; it  consisted  of  a rotary  cylinder  on  which  were  fastened  the 
blades  or  cutters,  placed  above  or  laterally  to  a carriage  on  which  wjis  placed  the  board  to  be  planed, 
which  was  moved  forward  by  rack  and  pinion.  The  cylinder  revolved  opposed  to  the  movement  of  the 
board,  and  rollers  were  introduced  bearing  upon  the  upper  surface,  so  as  to  prevent  the  board  being 
drawn  up  to  the  cutter.  The  following  is  the  claim  of  the  reissue  patent : 

“What  is  claimed  therein  as  the  invention  ofWm.  Woodworth,  deceased,  is  the  employment  of  rotary 
planes  substantially  such  as  herein  described,  in  combination  wdth  rollers,  or  any  analogous  device  to 
prevent  the  boards  from  being  drawn  up  by  the  planes,  when  cutting  upwards  ; or  from  the  reduced  oi 
planed  to  the  unplaned  surface  as  described’’ 

And  afterwards, 

“ The  effect  of  the  pressure  rollers  in  these  operations,  being  such  as  to  keep  the  boards,  etc.,  steady, 
and  prevent  the  cutters  from  drawing  the  boards  towards  the  centre  of  the  cutter  wheels,  whilst  it  is 
moved  through  hy  machinery.  In  the  planing  operation  the  tendency  of  the  plane  is,  to  lift  the  boards 
directly  up  against  the  rollers ; but  in  the  tonguing  and  grooving  the  tendency  is  to  overcome  the  fric- 
tion occasioned  by  the  pressure  of  the  rollers.” 

Woodworth  also  united  the  tonguing  and  grooving  machine  to  the  planer,  by  which  both  operations 
were  performed  at  one  and  the  same  time. 

Woodworth’s  planer  has  been  a fruitful  source  of  litigation.  The  only  novelty  seems  to  have  been  in 
the  pressure  rollers  to  keep  down  the  board,  and  the  union  of  the  tonguing  and  grooving  with  the  planing. 

Previous  to  the  machine  of  Woodworth,  Hill's  machine  was  constructed,  consisting  of  a rotaiy  cutter 
similar  to  Woodworth’s,  but  placed  beneath  the  bench ; the  board  was  pressed  down  on  the  bench  by 
means  of  rollers  ; in  this  machine  boards  were  planed  but  not  reduced  to  an  uniform  thickness.  To 
obviate  this,  an  improvement  was  made  on  this  machine  in  1850  by  N.  G.  Norcross.  He  has  made 
the  cutting  cylinder  movable,  vertically,  which  it  was  not  before,  and  has  connected  it  with  his  rest, 
that  is  with  the  pressure  roller,  so  that  when  the  latter  is  forced  upwards  by  the  increased  thickness  of 
the  board,  it  draws  the  cutter  upwards  with  it,  which  thereby  is  made  to  cut  just  as  much  more  from 
the  under  side  of  the  board,  as  the  roller  is  pressed  up  by  the  increased  thickness.  By  this  con- 
contrivance  the  edge  of  the  cutter  is  kept  in  a fixed  relation  to  the  rest,  or  in  other  words,  the  pres- 
sure roller,  the  space  between  them  being  always  the  same,  whereas  in  Hill’s,  and  also  in  Woodworth’s 
the  edge  of  a knife  had  a fixed  rotation  to  the  bed,  and  not  to  the  pressure  roller.  To  obviate  the  use  of 
the  rotary  cutter  and  continuous  feed,  which  by  many  were  supposed  to  be  inventions  of  Woodworth  and 
covered  by  his  patent,  many  machines  with  stationary  cutters  or  planes  were  made,  beneath  which 
the  board  to  be  planed  was  forced,  one  of  which  is  here  introduced ; but  the  rotary  cutter  is  by 
far  the  simplest  and  most  economical  in  regard  to  power.  The  Woodworth  planer  still  continues  to 
be  the  one  in  common  and  general  use  for  the  planing  of  boards  or  thin  plank,  but  for  the  planing 
of  timber,  the  Daniells’  planer  is  generally  preferred.  This  machine  consists  essentially  of  two  arms 
revolving  parallel  with  the  face  of  the  timber  to  be  planed,  near  the  extremities  of  which  are  inserted 
two  narrow  planes  or  gouges,  the  timber  lies  upon  a carriage,  and  the  feed  is  effected  by  a rack  and 
pinion.  Upon  the  shaft  to  which  the  arms  are  attached,  is  a long  drum  or  pulley,  to  which  motion 
is  given  by  means  of  a narrow  belt;  the  shaft  can  be  raised  or  depressed,  even  whilst  the  machine 
is  in  operation,  by  which  means  a thinner  or  thicker  chip  or  shaving  may  be  taken  off,  or  successive 
shavings  may  reduce  the  timber  to  the  thickness  required.  A machine  somewhat  similar  to  this,  is 
sometimes  used  for  the  planing  of  iron,  but  it  does  not  leave  a finished  surface. 

Tonguing  and  grooving  is  usually  performed  by  revolving  cutters;  the  cutter  irons  being  generally 
of  the  hook  form  or  duck  bill.  The  same  form  of  cutter  is  used  in  setting  mouldings ; they  are  roughed 
by  cutters  and  then  forced  through  stationary  irons  with  cutting  edges,  corresponding  in  form  to  the 
moulding  required.  Wave  mouldings,  such  as  are  used  in  cars  and  on  furniture,  are  finished  on  a 
machine  somewhat  similar  to  the  iron  planer,  the  wave  motion  being  given  by  a pattern  on  the  carriage, 
which  in  its  passage  vibrates  an  arm  connected  with  the  tool. 

Planing  Machine , Wood.  J.  P.  Woodbury’s  patent.  A Fig.  3076  is  the  frame  that  contains  the 
machinery.  B is  the  travelling  platform,  which  is  formed  of  lags,  and  linked  together  similar  to  some 
of  the  well-known  horse  powers,  the  upper  part  of  which  runs  on  ways  or  rollers,  which  sustain  it  per- 
fectly level.  C is  the  rollers  over  the  platform,  which  serve  to  aid  the  lower  platform  to  carry  the 
board  under  the  stationary  cutters.  D is  the  pulley  where  the  power  is  to  be  applied  to  drive  the  boar£ 


PLANES  AND  PLANING  MACHINES. 


501 


through  the  machine. 


It  operates  and  turns  the  chain-wheels  and  shafts  M,  thereby  moving  the 
platform,  and  making  an  endless  feeding  power.  E is  the  stocks 
or  cast-iron  beds  to  which  the  cutters  are  attached.  Said  cutters 
are  similar  to  those  of  a common  plane,  and  are  firmly  screwed 
to  the  beds  which  extend  across  the  machine,  and  attached  at 
each  end  to  the  cast  iron  frame  G,  where  they  are  each  ad- 
justed and  held  by  set-screws.  F is  the  yielding-bar  mouth- 
piece, which  also  extends  across  the  machine,  and  is  held 
down  by  springs  under  the  same.  This  bar  is  as  near  the  cut- 
ting edge  as  possible,  and  it  serve?  to  hold  the  grain  of  the 
wood  together  just  at  the  cutting  edge,  which  wholly  prevents 
splitting  or  tearing  the  wood.  It  adapts  itself  to  the  ine- 
qualities of  the  board  or  plank  without  clogging,  and  thereby 
produces  a perfect  surface.  G is  the  frame  that  holds  the 
cutters,  stocks,  and  mouth-pieces  in  their  proper  places,  and 
is  to  be  raised  or  lowered  to  suit  the  different  thicknesses  of 
material.  H is  the  crank  with  the  geering  attached  to  raise 
and  lower  the  frame  G,  which  holds  the  cutters.  I is  the 
geer-wheels.  that  connect  the  feeding  rollers  C to  the  endless 
travelling  platform  B.  J is  a series  of  rollers,  which  hold 
the  board  over  the  cutters,  to  plane  the  under  side  of  the 
board,  if  required.  L is  a wheel  attached  to  a screw  to 
move  a horizontal  slide  on  which  rests  the  frame  that  holds 
the  rollers  J,  and  to  which  is  attached  four  wedges.  The 
wheel  and  screw  L move  the  horizontal  slide,  thereby  raising 
and  lowering  the  rollers  to  admit  of  different  thicknesses  of 
material.  M is  the  chain-wheels  on  which  the  endless  plat- 
form revolves.  The  board  is  entered  between  the  platform 
B and  the  rollers  C,  and  carried  through  under  the  station-  ' 
ary  cutters  E,  which  plane  and  reduce  the  board  to  a uniform 
thickness.  It  then  moves  forward  between  the  rollers  J 
and  under  the  cutters  K,  which  plane  the  under  side,  if  re- 
quired. » 

The  above  described  machine  produces  a most  excellent 
surface,  and  does  the  work  with  great  rapidity. 

The  patent  includes  planing,  tonguing,  and  grooving  ma- 
chinery. 

Machines  for  Planing  Iron. 

Planing  Machine,  Hand.  The  following  figures  represent 
three  views  of  the  machine:  Fig.  3077  is  a front  .elevation, 
Fig.  3078  is  a side  elevation,  and  Fig.  3079  a plan.  The 
same  parts  are  denoted -by  the  same  letters  in  all  the  figures. 

A A the  supporting  legs  of  the  machine,  on  which  rests  B 
B the  bed  frame.  To  this  is  bolted  the  upright  frame  for 
carrying  the  slides. 

C,  the  vertical  slide.  On  this  are  cast  profecting  pieces 
a,  through  which  the  carrying  screws  f f pass.  By  these 
screws  the  slide  is  raised  and  depressed  at  pleasure  by  the 
geering  at  their  upper  extremities. 

D,  the  horizontal  slide,  which  is  carried  across  the  slide  C 
by  a screw  h b,  which  has  its  bearings  in  the  slide  c c,  which 

, ,k  \ j has  between  it  and  D a slide-carrier  d d,  admitting  of  a 

\1 small  amount  of  circular  motion  on  the  stud-bolts  h h.  These 

pass  through  circular  slots  in  the  plate,  and  are  provided 
with  pinching-nuts  to  retain  the  slide  in  the  position  desired. 
By  this  provision  the  slide  may  be  set  at  any  required 
angle,  as  iu  other  planing  machines.  In  front  of  the  cutter-slide  is  placed  the  tool-box  e and  g,  to  which 
is  fixed  the  cutting-tool  in  the  usual  way.  This  slide  is  moved  by  the  hand-wheel  on  the  upper  end  of 
the  slide-screw  k ; but  the  motion  of  the  cross-slide  D is  obtained  by  a self-acting  apparatus  from  E E, 
the  travelling  table.  On  this  the  article  to  be  planed  is  fixed  by  bolts,  sliding  in  dovetailed  grooves  in 
the  usual  way. 

F,  the  driving-pinion  which  geers  into  the  rack  M on  the  under  side  of  the  travelling  table  E.  This 
pinion  is  keyed  on  the  end  of  G the  driving-shaft,  on  one  end  of  which  is  the  driving-pinion  F,  and  on 
the  other  H a hand-cross,  keyed  on  the  end  of  the  shaft  G for  working  the  pinion  F,  which  travels  the 
work-table  E by  means  of  the  rack  M attached  to  its  under  side. 

K,  a ratchet-wheel  fast  on  one  end  of  the  slide-screw  b b. 

L,  a fclick  working  in  the  ratchet-wheel  K.  This  click  is  guided  in  the  length  of  its  travel  at  each 
stroke  by  the  position  of  the  sliding-studs  in  the  pieces  m.  and  n,  which  are  connected  by  the  rod  r. 
The  studs  slide  in  grooves  in  the  pieces  m and  n,  and  can  therefore  be  set  at  any  required  distances 
from  the  centres  of  motion ; and  accordingly,  the  number  of  teeth  over  which  the  click  is  carried  de- 
pending upon  the  positions  of  the  studs,  the  amount  of  feed-motion  of  the  screw  b b can  be  regulated 
at  pleasure. 


502 


PLANING  MACHINE,  HAND. 


PLANING  MACHINE. 


503 


M,  the  travelling  rack,  made  fast  to  the  table  and  worked  by  the  pinion  F.  The  form  of  the  rack  is 
shown  in  transverse  section  in  Fig.  30*77,  and  an  elevation  and  plan  are  shown  in  Figs.  3078  and  3079. 

o,  a balance-weight  on  the  end  of  a lever  projecting  from  the  same  small  shaft  on  which  the  crank’ 
ever  is  fixed.  On  the  opposite  end  of  this  small  shaft  is  fixed  another  lever,  placed  so  that  it  is  depressed 
by  the  tapet  S,  when  the  travelling  table  is  moved  towards  the  back  of  the  machine  ; by  this  the  crank- 
lev  er  n is  depressed  and  the  weight  o raised  at  the  same  instant. 

S is  a tapet  on  the  travelling  table,  and  which  may  be  shifted  to  any  required  position  and  fixed  there 
by  a pinching-screw  with  which  it  is  provided.  The  position  of  this  tapet  is  regulated  according  to  the 
length  of  the  travel  of  the  table  at  the  time. 


3079. 


V V Y V,  four  hovel-wheels,  geered  pair  and  pair,  for  turning  the  screws// to  raise  or  lower  the 
vertical  slide  C 0,  to  suit  the  work  upon  the  table.  Two  of  the  wheels  are  fast  upon  the  upper  ends  ol 
the  screws,  and  two  are  in  like  manner  made  fast  on  W a cross-shaft,  on  which  are  two  of  the  bevel- 
wheels  V V for  working  the  elevating  screws//.  This  shaft  has  a square  at  one  end  to  receive  the  eye 
of  a crank-handle  or  hand-wheel.  It  has  its  bearings  in  two  bored  pieces  which  rest  on  the  upper  ends 
of  the  screws,  and  against  the  eyes  of  the  wheels  keyed  on  them,  and  are  retained  in  their  places  by 
check-pins  in  the  usual  way. 

PLANING-  MACHINE,  by  Archibald  Mylne,  Glasgow.  This  machine  has  some  peculiarities  which 
render  it  worthy  of  a place  among  the  higher  order  of  tools  of  the  same  kind. 

Fig.  3080  is  a side  elevation,  and  Fig.  30802  a front  elevation  of  the  entire  machine,  with  the  same 
references. 

I;  is  the  bed- frame  of  the  machine,  carried  on  legs  or  supports  i.  The  bed-frame  is  formed  of  one 
casting,  with  two  projecting  edges  of  a shape,  which  are  planed  true,  and  fitted  to  corresponding 
V-shaped  grooves  in  the  under  side  of  the  travelling  table  m,  contrary  to  the  usual  arrangement  in  plan- 
ing machines. 

F is  the  upright  frame  for  carrying  the  slides ; and  m the  sliding  table  for  carrying  the  work  to  be 
planed.  The  work  is  fixed  to  the  table  by  bolts  with  dovetail  heads,  which  slide  in  grooves  of  corre- 
sponding form,  running  the  length  of  the  table.  The  upright  frame  F is  formed  of  two  side  brackets 
bolted  down  to  strong  flanges  cast  on  the  bed-frame  k,  and  joined  together  at  top  by  a cross-piece,  which 
gives  to  the  frame  the  necessary  rigidity  and,  strength.  The  faces  of  these  cheeks  and  cross-piece  are 
planed  true  and  polished.  This  is  requisite  in  respect  of  the  vertical  faces,  as  upon  these  the  vertical 
slide  a a moves  when  it  is  elevated  and  depressed  by  its  screws  n u ; and  the  cross-piece  is  polished  to 
avoid  unseemly  contrast  of  appearance. 

A is  the  driving-belt  for  the  forward  motion  of  the  table,  passing  round  a large  pullev,  as  shown  m 
Fig.  3080.  . F 1 

B,  a cross-belt  driving  a smaller  pulley  for  the  return  motion  of  the  table,  which  is  thus  made  quicker 
than  the  forward  motion.  These  belts  can  be  shifted  from  fast  to  loose  pulleys,  as  may  be  observed  by 
Fig.  3080,  in  which  they  are  shown  upon  their  loose  pulleys. 

D,  a pinion  fast  on  the  pulley-shaft. 

E,  a wheel  driven  by  the  pinion  D,  and  keyed  fast  on  a shaft  which  passes  through  the  bed-frame  of 
the  machine,  and  carries  the  two  fast  pinions  which  give  motion  to  the  sliding-table  by  geering  into 
racks  on  the  under  side  of  it,  shown  in  the  end  elevation.  These  two  racks  (or  double  rack)  have  the 
teeth  of  the  one  opposite  the  space  of  the  other,  so  as  to  render  the  motion  smooth  and  uniform. 

nn\  Fig.  3079,  are  tapets  to  reverse  the  motion  of  the  table. 

g,  a double  lever  keyed  on  a hollow  shaft  which  works  freely  on  the  driving-shaft. 

•*7  Fig.  3079,  a rod  having  one  end  attached  to  a lever,  fast  on  the  same  shaft  with  the  lever  t,  which 
carries  the  weights  r r , and  has  its  other  end  attached  to  a lever  keyed  on  the  same  hollow  shaft  with 
double  lever  g. 

M,  a traverse-shaft  connected  by  a lever  with  the  shaft  to  which  the  lever  / :s  attached. 


PLANING  MACHINE. 


50 1 


J,  a lever  fast  on  the  shaft  M ; and  C,  Fig.  30  802,  a guide  for  the  belts  connected  with  the  lever  J 
which  has  one  of  its  ends  flat  to  prevent  it  from  turning  round,  and  at  the  same  time  to  allow  it  to  slir 
lengthwise  and  shift  the  belts  from  the  fast  to  the  loose  pulleys. 


'The  machine  is  set  in  motion  by  moving  the  belt-guide  towards  the  off-side  of  the  machine,  by  which 
ttie  belt  is  shifted  on  the  narrow  pulley,  which  is  the  driver.  The  sliding  table  is  thus  put  in  motion, 
ana  moves  towards  the  back  part  of  the  machine,  until  the  tapet  n,  catching  one  of  the  legs  of  the 


lever  g,  turns  it  over,  throwing  outward  the  weight  r,  by  the  connecting-rod  x,  which  is  worked  by  a 
rever  fast  on  the  hollow  shaft  with  g. 

The  weights  r r'.  and  lever  t,  being  fast  on  the  same  shaft  and  connected  by  a link  with  M,  the  whole 


PLANING  MACHINE. 


505 


s simultaneously  put  in  motion,  and  the  upper  weight  r being  thrown  off  the  balance,  the  belt-guide  is 
pulled  by  the  lever  J until  the  belt  A is  shifted  to  the  loose  pulley,  and  the  cross-belt  B to  the  fast 
pulley,  to  produce  the  return  motion.  On  the  return  of  the  table  the  tapet  n'  turns  over  the  lever  g 
in  the  opposite  direction,  and  the  reversing  motion  is  produced  in  the  same  manner.  The  tapet  n' 
stands  further  out  than  n,  so  that  each  of  them  can  only  touch  one  leg  of  the  lever  g.  They  are  alsa 
made  to  slide  in  dovetail  grooves,  and  have  pinching  screws  to  fix  them,  to  suit  the  length  of  work  and 
its  position  on  the  table. 

The  lever  t,  which  moves  with  the  weights  r r',  communicates  motion  to  the  slides  on  the  frame  F, 
A section  of  these  slides  is  shown  at  Fig.  3081,  and  detached  parts  in  Figs.  3082  to  3086,  the  same  let- 
ters being  used  to  denote  the  same  parts  on  all  the  figures. 

a,  the  vertical  slide  attached  to  the  upright  frame  of  the  machine  by  four  screwed  pins,  which  pass, 
pair  and  pair,  through  long  grooves  in  the  cheeks  of  the  frame  F,  and  the  slide  being  set  at  the  requisite 
height  by  the  screws  uu,  it  can  then  be  tightened  by  jam-nuts  on  the  ends  of  the  pins  against  the  faces 
of  the  frame,  and  retained  in  the  required  position. 

b,  the  cross-slide  which  moves  across  the  breadth  of  the  machine,  upon  the  face  of  the  vertical  slide  a. 
Motion  is  communicated  to  it  by  a screw  which  has  its  bearings  ss  in  the  ends  of  the  vertical  slide,  and 
which  passes  through  a nut  attached  to  the  back  of  the  slide  b,  as  shown  in  Fig.  3081.  The  slide  is 
guided,  and  also  securely  retained,  on  the  slide  a by  dovetail  faces  formed  on  the  back,  and  which 
correspond  to  dovetails  formed  on  a.  The  upper  dovetail  is  made  adjustable,  Fig.  3081,  to  allow  for 
any  wear  of  the  surfaces  which  may  take  place.  On  the  face  of  the  slide  is  a graduated  arc  to  regulate 
the  setting  of  the  slide-carriage  c,  which  is  attached  to  it  by  fixing  screws  and  nuts,  Fig.  3080.  The 
screws  have  dovetail  heads,  which  slide  in  an  annular  groove,  Fig.  3082,  and  pass  through  two  holes  in 
the  circular  pieces  cast  on  the  edges  of  the  carriage  c.  The  bolts  are  put  in  from  the  back  of  the  slide  b 
through  a recess  cast  in  it  for  that  purpose.  The  carriage  thus  admits  of  being  placed  and  set  at  any 
required  angle  with  the  slide  b,  as  shown  by  Fig.  3087,  and  the  details  of  the  mode  in  which  this  is 
ell'ected  is  explained  by  Figs.  3082  and  3083,  and  partially  by  Figs.  3081  and  3080. 


3081. 


3082. 


3083. 


In  the  carriage,  c is  a screw  with  bearings  at  its  two  extremities,  in  the  metal  of  the  carriage.  It  is 
kept  from  moving  endways  by  a ruff  on  its  upper  end,  over  which  passes  a ring  of  malleable  iron,  fixed 
to  the  carriage  by  screwed  pins  tapped  into  the  metal.  On  the  lower  end  of  this  screw  is  fixed  a small 
bevel-wheel,  which  geers  with  one  of  a pair  checked  and  bolted  together,  so  that  motion  cannot  be 
communicated  to  the  one  without  the  other  being  moved  simultaneously  in  the  same  direction.  The 
second  of  the  wheels  geers  with  a similar  wheel  upon  the  rod  qq , Fig.  3080’,  and  their  common  bearing 
consists  of  the  V-shaped  groove  formed  by  the  backs  of  the  wheels  being  placed  against  each  other. 
This  groove  is  truly  turned  to  fit  the  corresponding  V-shaped  edge  of  an  annular  recess  cut  in  the 
centre  of  the  cross-slide  b,  (see  sections,  Figs.  3081  and  3082.)  The  purpose  of  this  arrangement  of 
wheels  will  be  explained  presently. 

On  the  face  of  the  carriage  c a projecting  piece  is  cast,  which  is  planed  with  dovetail  edges,  Fig.  3083, 
to  receive  corresponding  dovetails  of  the  slide  d,  Fig.  3084.  On  the  back  of  this  slide  is  also  fixed  a nut 
through  which  the  screw  in  the  carriage  c passes,  for  the  purpose  of  raising  and  depressing  the  slide, 
especially  when  set  obliquely,  according  to  the  circumstances  of  the  work  under  operation. 

e is  a second  slide-carriage  in  all  respects  similar  to  the  carriage  c,  except  that  it  is  smaller.  It  is 
attached  to  the  slide  d also  by  bolts  with  dovetail  heads,  which  work  in  an  annular  groove  in  the  face 
of  the  slide  d,  and  the  ends  of  the  bolts,  which  are  screwed  to  receive  the  fixing  nuts,  pass  through  holes 
in  the  projecting  lugs  cast  on  the  edges  of  the  carriage,  which  can  thus  be  set  at  any  required  angle  on 
the  face  of  the  slide  d. 

The  slide  f is  similar  to  that  marked  d,  and  is  attached  to  the  face  of  the  carriage  c in  exactly  the 
same  manner;  and  is,  moreover,  moved  by  the  screw  of  its  carriage,  with  which  it  is  connected  by  a 
nut,  Figs.  3081  and  3086,  to  any  position  required  within  the  range  of  its  travel.  The  tool-box  is 
attached  to  this  slide  by  a flexible  joint,  which  is  easily  understood  from  Figs.  3081  and  3086.  The  use 
ol  the  joint  is  to  prevent  the  tool  h from  cutting  during  the  returning  of  the  work-table,  which  in  this 
arrangement  of  slides  would  be  apt  to  injure  the  more  delicate  parts  of  the  machine,  and  possibly  the 
work  under  operation,  particularly  as  the  return  motion  of  the  table  is  much  too  quick  for  cutting.  Very 
little  moliou  of  the  joint  is  required  to  allow  the  tool  to  clear  the  work. 


506 


PLANING  MACHINE,  SELF-ACTING. 


The  mode  of  fixing  the  tool  is  by  T-headed  bolts  and  glands,  as  shown  in  Figs.  3080  and  3086.  It 
this  last  the  tool  and  glands  are  removed,  but  the  fixing  bolts  are  dotted  in  their  positions. 

uu,  screws  revolving  in  the  projecting  ends  of  the  top  rail,  and  working  into  nuts  on  the  back  of  the 
slide  a. 

o,  handle  to  turn  the  screws  by  means  of  a system  of  bevel-wheels,  in  order  to  raise  or  depress  the 
slide  a to  suit  the  work  to  lie  planed,  the  slide  a having  fixing  bolts  to  secure  it  to  the  planed  faces  oi 
the  frame  at  the  required  height. 

w,  a lever  with  a spring-catch  which  may  be  geered  into  the  wheel  y. 

v,  a rod  connecting  the  lever  t with  the  lever  w.  The  spring-catch  being  in  geer,  the  wheel  y receives 
motion  from  the  lever  t , and  being  geered  with  a pinion  on  the  end  of  the  cross  slide-screw,  which  re 
volves  in  bearings  s s,  it  communicates  its  motion  to  the  screw  and  cross-slide  b.  The  amount  of  feed  is 
adjusted  by  shifting  the  studs  in  the  slots  of  the  levers  t and  w\  and  the  direction  in  which  the  slide  is 
wanted  to  be  moved  is  regulated  according  as  the  spring-catch  is  geered  above  or  below  the  axis  of  the 
lever  w. 


3087. 


3086. 


3C35.  3084. 


This  self  acting  feeding  motion  is  also  communicated  to  the  down  cutting  slide  d by  shifting  the 
pinion  from  the  end  of  the  screw  to  the  end  of  the  small  shaft  which  works  in  the  bearings  q q , Fig.  308f> 
On  this  shaft  is  a small  bevel-wheel  shown  at  Figs.  3081  and  3082,  which  is  carried  round  by  having  a 
key  projecting  into  a groove  continued  the  whole  length  of  the  shaft.  This  wheel  is  carried  along  the 
shaft  by  a projecting  piece  on  the  slide  b,  Fig.  3082,  and  its  motion  is  communicated  to  that  on  the  end 
of  the  slide-screw  in  c,  Fig.  3081,  by  means  of  two  similar  intermediate  wheels  placed  in  slide  6,  as 
above  described. 

The  front  slide /is  not  commonly  attached  to  planing  machines;  but  it  is  valuable  where  work  is  tc 
be  done  which  requires  two  or  three  different  angled  surfaces  to  be  planed,  and  which  can  be  done  with 
this  machine  by  arranging  the  slides  before  starting,  no  shift  being  afterwards  required. 

Fig.  3087  shows  the  slides  set  at  different  angles. 

PLANING  MACHINE,  SELF-ACTING  COMPOUND,  by  Nasmyth,  Gaskeli.  A Co.  The  machine 
represented  in  Figs.  3088,  3089,  3090,  and  3091  is  remarkable  for  compactness  and  elegance  of  arrange- 
ment, and  for  the  accuracy  and  dispatch  with  which  a description  of  work  that,  previously  to  the  intro- 
duction of  such  machines,  could  only  be  intrusted  to  the  most  expert  and  skilful  mechanic,  but  which  can, 
by  its  means,  be  executed  by  workmen  of  the  most  ordinary  capacity.  It  is  especially  applicable  to  the 
finishing  of  the  numerous  small  levers  used  in  locomotive  engine  and  tool-making,  and  is  admirably 
adapted,  not  only  to  the  planing  of  the  sides  and  edges  of  such  levers,  but  also  to  the  finishing  of  their 
rounded  ends,  which  otherwise  could  only  be  accomplished  by  the  rude  and  tedious  process  of  chipping 
and  filing. 

Fig.  3088  is  a side  elevation  of  the  machine. 

Fig.  3089  is  a view  of  the  front  end  or  face. 

Fig.  3090,  a general  plan  ; and 

Fig.  3091,  a transverse  section  through  the  principal  working  parts. 

General  description. — The  frame  upon  which  the  machine  rests,  and  which  is  used  for  the  purpose  of 
raising  it  to  a convenient  height,  is  composed  of  two  cast-iron  cheeks  A A,  strengthened  by  flanges,  and 
held  together  at  the  lower  end  by  two  stay-rods  a a.  These  frames  are  disposed  at  an  angle  to  each 
other,  in  order  to  give  greater  stability  to  the  structure.  The  main  body  of  the  machine  consists  of  a 
cast-iron  table  or  box  B bolted  to  the  frames  by  internal  flanges,  as  shown  in  the  section,  Fig.  3091,  and 
on  the  upper  side  of  this  table  are  cast  the  bracket  C,  carrying  the  driving-spindle,  and  the  rectangular 
chamber  D,  furnished  with  bearings  for  the  other  working  parts  of  the  machine.  The  square  cast-iron 
sliding-bar  E,  which  carries  the  tool-holder,  is  accurately  planed,  and  fitted  into  a recess  in  the  upper 
portion  of  the  piece  D.  It  is  of  essential  importance  that  the  slide  E should  move  accurately'  and  with- 
out play  in  a rectilinear  and  horizontal  direction,  and  for  this  purpose  it  is  secured  laterally  by  the 
adjusting  screws  b b,  and  vertically  by  the  wrought-iron  plate  or  cover  c,  fixed  to  the  frame  by  the  six 
countersink  screws  ddd. 

On  the  front  end  of  the  square  slide  E is  cast  a flat  rectangular  plate,  which  serves  as  the  fixed  point 
of  resistance  to  the  various  motions  of  which  the  tool-box  is  susceptible.  The  first  of  these  is  a rotary 
motion,  which  is  impressed  upon  it  by  a toothed  quadrant  plate  e,  worked  by  an  endless  screw  on  the 
axis  f.  This  arrangement  enables  the  workman  to  set  the  tool  at  any  required  angle  to  the  work.  On 
the  upper  edge  of  that  part  of  the  tool-box  marked  F,  is  fixed  a nut,  through  which  works  a screw  g: 
surmounted  by  a handle  or  small  hand-wheel  This  screw  is  used  for  raising  or  depressing  the  tool,  and 


PLANING-MACHINE,  SELF-ACTING. 


507 


thereby  adapting  it  to  the  diameter  or  height  of  the  work  to  be  executed,  as  well  as  for  regulating  the 
depth  of  cut.  The  part  G,  which  is  thus  acted  upon  by  the  screw  g,  is  furnished  with  two  parallel 
cheeks  accurately  dressed  on  their  internal  surfaces,  and  fitted  to  receive  the  tool-holder  li.  The  tool 
itself  is  inserted  into  a square  hole  passing  through  the  piece  h,  and  fixed  firmly  to  it  by  two  pinching- 
screws.  The  tool-holder  h is  so  formed  as  to  admit  of  a small  amount  of  rotary  motion  round  two 
centre  screws  passing  through  the  cheeks  of  the  piece  G,  and  by  this  means  accidents  arising  from  the 
friction  of  the  tool  against  the  work  in  the  return  stroke  are  prevented. 

The  mode  in  which  motion  is  communicated  to  the  tool-box  is  as  follows : The  extremity  of  the 

square  slide  E opposite  to  that  on  which  the  tool-box  is  fixed,  is  traversed  by  a longitudinal  slot  or 
groove  i,  adapted  for  the  reception  of  a bolt-head,  as  shown  in  the  transverse  section,  Fig.  3091.  The 
projecting  part  of  the  bolt  passes  through  a hole  in  the  end  of  the  connecting-rod  H,  the  opposite  end 
of  which  is  attached  by  another  bolt  tc  a rectangular  cast-iron  piece  I,  fixed  to  the  end  of  the  driving- 
spindle,  and  acting  as  a crank  for  converting  the  rotary  into  a rectilinear  motion.  The  crank  I is 
traversed  throughout  its  whole  length  by  a slot  i,  the  form  of  which,  as  well  as  of  that  in  the  slide  E,  is 
shown  in  the  section,  Fig.  3091.  By  means  of  these  slots  the  length  of  the  stroke  and  the  position  w 
the  tool  may  be  easily  and  accurately  adjusted  to  suit  the  work,  as  will  be  sufficiently  obvious  by 
inspection  of  Fig.  3088.  The  driving-spindle  works  in  two  bearings,  one  of  which,  as  before  mentioned, 
is  cast  on  the  bed  of  the  machine  B,  and  tire  other  is  formed  in  the  extremity  of  a bracket  bolted  to  the 
eide  of  it.  The  velocity  of  the  driving-spindle  is  varied  and  regulated  by  means  of  the  cone-pulley  J 
anil  fly-wheel  K. 


3088. 


The  planing  of  circular  surfaces  is  effected,  in  this  machine,  by  means  of  a hollow  cylindrical  cast-iron 
Aiandrel  L,  Figs.  3091  and  3092,  accurately  turned  and  fitted  into  the  body  of  the  machine,  the  centre 
being  exactly  under  that  of  the  square  slide  E.  This  mandrel  is  provided  with  a conical  bearing  on  the 
front  end,  and  is  traversed  by  a malleable  iron  bolt  l,  secured  to  its  opposite  extremity  by  a nut.  The 
head  of  the  bolt  l is  formed  into  a cylindrical  socket,  into  which,  by  means  of  a cotter,  is  fixed  another 
bolt,  having  two  conical  pieces  mm,  one  of  which  is  immovable,  and  forms  part  of  the  bolt,  while  the 
other  slides  upon  it,  and  is  adjusted  by  means  of  the  nut  n.  These  pieces  are  used  for  the  purpose  of 
fixing  the  work  M,  upon  which  the  machine  is  to  operate ; and  from  their  conical  form,  adapt  themselves 
to  any  required  diameter,  so  as  to  insure,  without  any  trouble  in  setting,  the  concentricity  of  the  outer 
surface  with  the  eye. 

The  motion  of  the  mandrel  L,  with  its  appendages,  is  effected  by  means  of  the  worm-wheel  FT,  which 
is  fixed  to  its  inner  end  by  a large  circular  nut  screwed  to  the  cast-iron  mandrel  itself,  independently  of 
the  bolt  l,  which  passes  through  it.  The  worm-wheel  N geers  with  an  endless'  screw  on  the  horizontal 
axis  o,  working  in  two  bearings,  oue  of  which  is  formed  by  a small  malleable  iron  piece  bolted  to  the 
body  of  the  machine  D,  and  the  other  extends  considerably  beyond  the  table,  and  is  supported  by  the 
bracket  O bolted  to  it,  as  shown  in  the  section,  Fig.  3091.  The  axis  o,  besides  the  self-acting  mecha- 
nism which  we  are  about  to  describe,  is  provided  with  a handle,  by  which  it  can  at  pleasure  be  moved  by 
the  attendant  workman.  The  self-acting  geer,  which,  in  Fig.  3093,  is  shown  detached  from  the  machine, 
consists  of  an  eccentric  P,  fixed  upon  the  driving-spindle,  and  by  means  of  the  rod  pp,  communicating  a 
reciprocating  motion  to  the  slotted  lever  Q,  which  motion  is  again  conveyed  by  the  rod  r r to  the 
smaller  slotted  lever  S.  The  centres  of  motion  of  these  levers  are  respectively  on  the  extremities  of  the 
traverse  screw  v,  which  is  used  only  in  flat  planing,  and  on  that  of  the  axis  o,  of  the  endless  screw,  and 
on  these  centres  they  are  fitted  to  move  loosely  without  turning  them.  The  slots  which  traverse  the 
levers  are  for  the  purpose  of  altering  the  feed  to  any  required  amount.  The  motion  of  the  levers  is 
communicated  to  their  axes  by  the  double  pawls  q and  s,  which  work  respectively  into  the  wheels  R 
and  T,  fixed  upon  their  centres  v and  o.  These  wheels  act  in  this  case  as  ratchet-wheels,  and  from  the 
peculiar  form  given  to  the  pawls,  they  may  be  made  to  move  either  backwards  or  forwards  by  simply 
reversing  the  direction  of  the  pawls. 

For  the  purpose  of  planing  flat  surfaces  with  this  machine,  it  is  provided  with  a cast-iron  face-plaia 
G U,  which  is  traversed  by  several  slots,  cast  on  its  exterior  surface,  and  adapted  to  receive  the  bolts 
by  which  the  work  is  to  be  fixed  to  it.  The  back  of  the  face-plate  is  planed  and  fitted  to  move  trans- 
versely along  the  slide  V,  by  means  of  adjustable  dovetail  pieces,  in  the  manner  we  have  already  so 
requently  had  occasion  to  describe.  This  motion  is  effected  by  means  of  the  screw  v,  which  is  worked 


508 


PLATE-BENDING  MACHINE. 


by  the  mechanism  above  described,  and  which,  having  a bearing  at  each  end  of  the  slide  V,  passei 
along  a recess  cast  in  its  surface,  and  works  into  a brass  nut  fixed  on  the  back  of  the  face-plate  U.  The 
traverse  screw  v is  provided  with  a handle  w,  for  the  purpose  of  setting  the  work  into  its  proper  position 
under  tire  tool,  before  bringing  the  self-acting  mechanism  into  geer. 


noon. 


PLATE-BENDING  MACHINE,  by  Robert  Napier,  Glasgow.  This  species  of  machine,  originally 
confined  to  the  tinsmith's  shop,  has  recently — enlarged  in  its  dimensions  and  rendered  more  complete  in 
its  mechanism — become  indispensable  in  the  operations  of  boiler-making  and  iron-ship  building,  in  whicti 
plates  are  required  to  be  bent  to  various  degrees  of  curvature.  The  example  given  is  the  design  of  Mr. 
Elder,  the  manager  of  Mr.  Napier’s  works,  and  is  one  of  the  largest  yet  made,  being  intended  principally 
for  use  in  the  building  yard,  where  plates  of  greater  thickness  come  under  operation  than  those  required 
in  boiler-making. 

Fig.  3098  is  a side  elevation  of  the  machine,  and  Fig.  3099  an  end  view  towards  the  driving-geer. 

Fig.  3100  is  a plan  corresponding  to  Fig.  3098. 

General  description. — The  frame  of  the  machine  consists  of  two  very  strong  end  standards  A A,  cast 
with  soles  to  admit  of  their  being  bolted  down  to  a solid  stone  foundation.  They  are  braced  together 
by  four  strong  rods  of  malleable-iron  a a a,  the  screwed  ends  of  which  pass  through  projections  on  the 
standards,  of  such  thickness  that  the  nuts  by  which  they  are  secured  are  nearly  flush  with  the  outside 
of  the  frames,  thus  obviating  the  necessity  for  having  the  geering  far  overhung. 

The  three  rollers  BCD  are  solid ; the  dimensions  of  each  being  12  inches  diameter,  and  10  feet  long 
within  their  bearings.  The  two  rollers  B and  C are  placed  in  the  same  vertical  plane;  but  the  third 
roller  D moves  in  a plane  inclined  at  an  angle  of  thirty  degrees  to  the  vertical  plane.  On  one  end  ot 
the  roller  B is  keyed  a strong  pinion  E,  which  geers  with  another  pinion  of  the  same  size  marked  G on 
the  end  of  the  lower  roller  C.  On  the  opposite  end  of  this  last  is  fixed  a large  spur-wheel  H into  which 
works  a pinion  I on  the  shaft  J,  which  has  a bearing  in  each  of  the  two  standards,  and  carries  on  its 
other  end  a large  spur-wheel  K,  commanded  by  a pinion  upon  the  driving-shaft  L.  One  end  of  this 
shaft  is  carried  in  a bearing  in  the  adjacent  standard  of  the  machine,  and  the  other  in  an  independent 
standard  M bolted  to  the  foundation.  It  carries  four  pulleys,  two  of  which,  N O,  are  fast  upou  the  shaft, 
and  the  other  two,  P Q,  of  double  the  breadth  of  the  former,  are  loose.  On  these  are  two  belts,  the  one 
cross  and  the  other  open,  so  that  the  rollers  may  be  driven  in  either  direction  according  as  the  motion 
is  communicated  by  the  open  or  the  cross  belt.  The  belts  are  shifted  on  their  pulleys  by  means  of  the 
hand-bar  R,  on  which  are  the  guide-arms  S T,  so  placed  that  in  reversing  the  motion  of  the  machine, 
the  belt  thrown  out  of  action  shall  have  passed  entirely  from  its  fast  pulley  before  the  other  shall  have 
passed  from  its  loose  pulley  to  the  fast  one.  This  arrangement  obviates  the  injurious  effect  so  common 
in  machines  furnished  with  this  species  of  driving-geer,  of  the  one  belt  acting  against  the  other  during  a 
part  of  the  time  of  shifting,  thereby  occasioning  much  unnecessary  tear  and  wear  of  the  belts. 

The  upper  roller  B is  adjusted  to  the  thickness  of  the  plate  to  be  bent  by  two  strong  set-screws  U IT, 
which  work  in  hexagonal  brass  nuts  inserted  into  recesses  in  the  standards.  These  screws  bear  againel 


PLATE-BENDING  MACHINE. 


509 


a steel  plate  resting  upon  the  brass  block  in  "which  the  roller  revolves,  and  which  is  of  course  placed 
over  the  journal,  the  pressure  being  upwards ; and  thus  the  roller  is  kept  pressed  down  upon  the  plate, 
as  it  passes  through  the  machine  in  the  operation  of  bending. 

The  roller  D is  adjusted  to  the  required  position  by  the  double  hand-crank  on  the  upper  end  of  the 
vertical  spindle  b b,  which  communicates  by  means  of  a pair  of  small  bevel-wheels  c c with  the  screws 
dd,  working  into  long  brass  nuts  ee  inserted  in  recesses  of  the  frame.  The  upper  ends  of  these  nuts 
support  the  bearings  of  the  roller,  which  may  consequently  be  raised  and  lowered  at  pleasure,  according 
as  the  spindle  is  turned  in  one  direction  or  the  other.  The  nuts  ee  are  prevented  from  turning  round 
with  the  screws  by  feathers  upon  the  back  of  the  brasses  fitting  into  grooves  on  the  ends  of  the  nuts 


In  machines  of  this  kind  it  is  common  to  provide  geering  for  working  both  ends  of  the  shifting-roller 
simultaneously,  so  that  the  rollers  may  always  preserve  their  parallelism.  But  in  the  present  example 
that  mechanism  has  been  purposely  omitted,  to  adapt  it  for  bending  the  same  plates  with  different  de- 
grees ot  curvature  at  the  opposite  edges  ; a description  of  work  much  required  in  the  building  yard  and 
Tther  CaD  °Dly  be  effected  by  “S  one  end  of  tlle  movable  roller  D proportionally  higher  than  the 

Action  of  the  machine. — From  this  outline  of  the  arrangement,  the  action  of  the  machine  will  be 
easily  understood.  Motion  being  communicated  through  one  of  the  belts  to  the  driving-shaft  L,  the 
pinion  upon  the  end  of  that  shaft  geering  with  the  large  wheel  K gives  motion  to  the  shaft  J ; this  mo- 
tion by  means  of  the  pinion  I,  is  transferred  to  the  large  wheel  H,  which  is  fast  on  the  under  roller  C 


510 


PNEUMATICS. 


This  roller  being  put  in  motion,  communicates  an  equal  velocity  to  the  upper  roller  B by  means  of  the 
pinions  E and  G which  geer  together.  The  roller  L>,  the  position  of  which  determines  the  degree  ot 
curvature  ot  the  plate  under  operation,  is  only  driven  by  the  friction  of  the  plate  against  it  as  it  passes 
between  the  two  other  rollers. 


Literal  references. 


3099. 


A A,  the  end  standards  of  the  machine. 

a a a,  stay-rods,  2 inches  diameter,  for  connecting 
the  two  standards. 

B,  the  upper  roller,  12  inches  in  diameter,  and  10 
feet  long  between  its  bearings,  which  are  51- 
inches  in  diameter. 

C,  the  lower  roller,  of  the  same  dimensions. 

D,  the  shifting-roller,  of  the  same  dimensions. 

b,  the  upright  spindle  for  setting  the  roller  D. 

c,  small  bevel  pair  worked  by  the  spindle  b. 

il,  a screw,  2§  inches  diameter,  and  § inch  pitch. 

e,  brass  nut  into  which  the  screw  d works. 

E,  a pinion  on  the  end  of  the  top  roller  B ; pitch  2i 
niches,  number  of  teeth  1 G. 

G,  a similar  pinion  on  the  lower  roller  C. 

H,  a large  spur-wheel  on  the  opposite  end  of  the 
roller  C;  pitch  1J  inch,  number  of  teeth  100. 

I,  a pinion  of  13  teeth,  working  into  the  spur- 
wheel  H. 

J,  a wrouglit-iron  shaft  conveying  motion  to  the 
pinion  I from 

K,  a spur-wheel  at  the  opposite  end  of  the  ma- 
chine ; pitch  11  inch,  number  of  teeth  75. 

L,  the  driving-shaft  of  the  machine. 

M,  a standard  for  supporting  the  exterior  end  of 
the  driving-shaft. 


N O P Q,  fast  and  loose  pulleys  for  setting  in  mo- 
tion, stopping,  and  reversing  the  machine. 

R,  the  hand-bar  for  shifting  the  belts. 

S T,  guide-arms  fixed  on  the  hand-bar  R. 

U U,  screws  for  adjusting  the  top  roller. 


PLATINUM.  (So  called  from  the  Spanish  word  plata,  silver,  on  account  of  its  color.)  A metal  of  » 
white  color,  exceedingly  ductile,  malleable,  and  difficult  of  fusion.  It  is  the  heaviest  substance  known, 
its  specific  gravity  being  21'5.  It  undergoes  no  change  from  air  or  moisture,  and  is  not  attacked  by  any 
of  the  pure  acids ; it  is  dissolved  by  chlorine  and  nitromuriatic  acid,  and  is  oxidized  at  high  tempera- 
tures by  pure  potossa  and  lithia.  It  is  only  found  in  South  America  and  in  the  Uralian  Mountains  : it 
is  usually  in  small  grains  of  a metallic  lustre,  associated  or  combined  with  palladium,  rhodium,  iridium, 
and  osmium ; and  with  copper,  iron,  lead,  titanium,  chromium,  gold,  and  silver ; it  is  also  usually  mixed 
with  alluvial  sand.  The  particles  are  seldom  so  large  as  a small  pea,  but  sometimes  lumps  have  been 
found  of  the  size  of  a hazel-nut  to  that  of  a pigeon’s  egg.  In  1826  it  was  first  discovered  in  a vein  associated 
with  gold,  by  Boussingault,  in  the  province  of  Antioquia,  in  South  America.  When  a perfectly  clean  surface 
of  platinum  is  presented  to  a mixture  of  hydrogen  and  oxvgen  gas,  it  has  the  extraordinary  property  of 
causing  them  to  combine  so  as  to  form  water,  and  often  with  such  rapidity  as  to  render  the  metal  red- 
hot  : spongy  platinum,  as  it  is  usually  called,  obtained  by  heating  the  ammonio-muriate  of  platinum,  is 
most  effective  in  producing  this  extraordinary  result ; and  a jet  of  hydrogen  directed  upon  it  may  be 
inflamed  by  the  metal  thus  ignited,  a property  which  has  been  applied  to  the  construction  of  convenient 
instruments  for  procuring  a light.  The  equivalent  of  platinum  is  about  98.  It  is  precipitated  from  its 
nitromuriatic  solution  by  sal  ammoniac,  which  throws  it  down  in  the  form  of  a yellow  powder,  composed 
of  bichloride  of  platinum  and  sal  ammoniac. 

PNEUMATICS.  The  science  which  treats  of  the  mechanical  properties  of  elastic  fluids,  and  particu- 
larly of  atmospheric  air. 

Elastic  fluids  are  divided  into  two  classes — permanent  gases  and  vapors.  The  gases  cannot  be  con- 
verted into  the  liquid  state  by  any  known  process  of  art ; whereas  the  vapors  are  readily  reduced  to 
the  liquid  form  by  pressure,  or  diminution  of  temperature.  In  respect  of  their  mechanical  properties 
there  is,  however,  no  essential  difference  between  the  two  classes. 

Elastic  fluids,  in  a state  of  equilibrium,  are  subject  to  the  action  of  two  forces ; namely,  gravity,  and 
a molecular  force  acting  from  particle  to  particle.  Gravity  acts  on  the  gases  in  the  same  manner  as  on 
all  other  material  substances  ; but  the  action  of  the  molecular  forces  is  altogether  different  from  that 
which  takes  place  among  the  elementary  particles  of  solids  and  liquids ; for,  in  the  case  of  solid  bodies, 
the  molecules  strongly  attract  each  other,  (whence  results  their  cohesion,)  and,  in  the  case  of  liquids, 
exert  a feeble  or  evanescent  attraction,  so  as  to  be  indifferent  to  internal  motion ; but,  in  the  case  of  the 
gases,  the  molecular  forces  are  repulsive,  and  the  molecules,  yielding  to  the  action  of  these  forces,  tend 
incessantly  to  recede  from  each  other,  and,  in  fact,  do  recede,  until  their  further  separation  is  prevented 
by  an  exterior  obstacle.  Thus,  air  confined  within  a close  vessel  exerts  a constant  pressure  against  the 
interior  surface,  which  is  not  sensible,  only  because  it  is  balanced  by  the  equal  pressure  of  the  atmos- 
phere on  the  exterior  surface.  This  pressure  exerted  by  the  air  against  the  sides  of  a vessel  within 
which  it  is  confined  is  called  its  elasticity,  or  elastic  force,  or  tension. 

Conditions  of  equilibrium. — In  order  that  all  the  parts  of  an  elastic  fluid  may  be  in  equilibrium,  one 
condition  only  is  necessary ; namely,  that  the  elastic  force  be  the  same  at  every  point  situated  in  the 
same  horizontal  plane.  This  condition  is  likewise  necessary  to  the  equilibrium  of  liquids,  and  the  same 


PNEUMATICS. 


511 


circumstances  give  rise  to  it  in  both  cases  ; namely,  the  mobility  of  the  particles,  and  the  action  of  gravity 
upon  them.  Conceive  a close  vessel  to  be  filled  with  air,  or  a gas  ; and  let  a and  b be  two  molecules 
situated  in  the  same  horizontal  plane.  It  is  evident  that  if  the  two  molecules  are  in  a state  of  equili- 
brium, the  force  with  which  a repels  b must  be  exactly  counteracted  by  that  with  which  b repels  a,  for 
otherwise  motion  wyould  take  place.  The  same  thing  takes  place  in  respect  of  every  horizontal  section 
of  the  gas ; but  the  pressure  on  each  section  varies  with  its  altitude.  Suppose  c and  d to  be  twro  mole- 
cules situated  in  a horizontal  section,  lower  than  that  in  which  are  a and  b.  It  is  evident  that  the  mole- 
cules c and  d sustain  a greater  pressure  than  a and  6;  for,  in -the  first  place,  the  whole  of  the  pressure 
on  a and  b is  transmitted  to  them  by  the  principle  of  the  equality  of  pressure  in  all  directions ; and,  in 
the  second  place,  they  sustain  a new  pressure,  arising  from  the  weight  or  gravity  of  all  the  molecules 
situated  between  the  two  horizontal  planes  a b and  c d. 

The  principle  which  has  just  been  explained  is  proved  experimentally  by  the  diminution  of  the  pres- 
sure of  the  atmosphere  at  greater  altitudes.  A column  of  air  reaching  from  the  ground  to  the  top  of 
the  atmosphere  exerts  a pressure  equal  to  the  weight  of  a colunrn  of  mercury  of  the  same  diameter,  and 
whose  height  is  equal  to  that  in  the  barometric  tube.  Now,  on  carrying  the  barometer  to  the  top  of  a 
mountain,  for  example,  the  mercurial  column  is  observed  gradually  to  become  shorter  as  we  ascend ; 
and  the  diminution  of  the  column,  and  consequently  of  atmospheric  pressure,  is  connected  with  the  in- 
crease of  altitude  by  a certain  constant  law,  which  enables  us  to  deduce  the  one  from  the  other,  and  to 
apply  the  barometer  to  the  very  important  purpose  of  determining  the  relative  altitudes  of  places  on 
the  surface  of  the  earth. 

The  volumes  of  gases  are  inversely  as  the  pressures  which  they  support. — This  fundamental  property 
of  elastic  fluids  is  called  the  Law  of  Mariotte , from  its  having  been  discovered  by  that  philosopher  in 
France.  It  has  been  verified  in  several  ways,  on  all  the  known  gases ; and,  in  the  case  of  dry  air,  its 
verification  has  been  pushed,  by  MM.  Dulong  and  Arago,  to  pressures  equivalent  to  twenty-seven  at- 
mospheres. (Lame  Gours  de  Physique.)  It  also  holds  true  in  respect  of  vapors  or  steam,  subjected  to 
a smaller  degree  of  pressure  than  that  which  is  necessary  to  reduce  them  to  the  liquid  state  ; and  even 
for  mixtures  of  different  gases.  It  is  important,  however,  to  observe,  that  it  is  supposed  no  variation 
of  temperature  has  taken  place  during  the  experiment. 

The  density  of  bodies  being  inversely  as  their  volumes,  the  law  of  Mariotte  may  be  otherwise  ex- 
pressed, by  saying,  the  density  of  an  elastic  fluid  is  directly  proportional  to  the  pressure  it  sustains. 
Under  the  pressure  of  a single  atmosphere,  the  density  of  air  is  about  the  770th  part  of  that  of  water; 
whence  it  follows  that,  under  the  pressure  of  770  atmospheres,  air  is  as  dense  as  water.  Thus,  the 
average  atmospheric  pressure  being  equal  to  that  of  a column  of  water  of  about  32  feet  in  altitude,  at 
the  bottom  of  the  sea,  at  a depth  of  24640  ( = 770  X 32)  feet,  or  4f  miles,  air  would  be  heavier  than 
water  ; and  though  it  should  still  remain  in  a gaseous  state,  it  would  be  incapable  of  rising  to  the  surface. 

Effects  of  heat  on  the  elasticity  of  the  gases. — The  repulsive  energy  of  the  molecules  of  the  elastic 
fluids  is  greatly  augmented  by  an  increase  of  temperature  ; and  it  is  of  the  utmost  importance  in  many 
physical  inquiries  to  ascertain  the  relation  between  the  temperature  and  the  elastic  force.  If  the  air 
and  several  other  gases,  sustaining  the  same  constant  pressure,  are  exposed  to  an  increase  of  tempera- 
ture which  affects  all  of  them  equally,  it  is  proved,  by  observation,  that  they  all  undergo  an  equal  ex- 
pansion ; that  is  to  say,  the  increase  of  volume  of  all  the  gases  is  the  same  for  equal  augmentations  of 
temperature,  and  proportional  to  these  augmentations.  Experience  also  shows  that,  within  a considera- 
ble range  of  temperature,  the  indications  of  the  air  thermometer  differ  very  little  from  those  of  the  mer- 
curial thermometer ; so  that,  within  this  range,  the  expansion  of  any  gas  whatever  is  proportional  to  the 
increase  of  temperature  indicated  by  the  degrees  of  the  ordinary  thermometer.  From  the  temperature 
of  melting  ice  to  that  of  boiling  water,  or  from  zero  to  100°  of  the  centigrade  thermometer,  Gay-Lussac 
found  the  expansion  of  air  subjected  to  a constant  pressure,  to  be  in  the  ratio  of  unity  to  1'375 ; which 
gives  an  expansion  of  000375  for  each  centigrade  degree.  This  being  assumed,  let  Y be  the  volume 
of  any  gas  at  the  zero  temperature,  P its  elastic  force,  or  the  pressure  it  sustains,  and  D its  density. 
Let  a = '00375,  and  suppose  the  values  of  V and  D to  become  V'  and  D'  when  the  temperature  is  in- 
ti eased  t degrees;  then  the  pressure  P being  supposed  constant,  we  have  evidently 

V'  = V(1  +<zf ); 


and  the  density  being  inversely  as  the  volume,  we  have,  also, 

D'=  ° 

1 -j-  a t 

Now,  suppose  the  pressure  to  be  varied  without  any  change  of  the  temperature,  and  let  y>  denote  the 
Dew  pressure,  and  d the  corresponding  density;  the  law  of  Mariotte  gives 

p d 

P : D 1 ::p:  d,  whence  p = — ; 

p 

and,  on  substituting  for  D'  its  value  given  by  the  preceding  formula,  and  making  — = k,  we  obtain 
. p = kd{  1 + at) 

for  the  expression  of  the  elastic  force  of  any  gas  in  a function  of  its  density  and  temperature. 

The  coefficient  k is  constant  for  the  same  gas,  but  has  a different  value  for  different  gases,  depending 
on  their  densities  or  specific  gravities.  With  respect  to  atmospheric  ah',  its  value  may  be  found  thus : 
The  density  of  air,  compared  with  water,  is  0'0013,  and  that  of  mercury  13'59  ; therefore,  supposing  the 
height  of  the  barometer  to  be  30  inches,  the  value  of  k,  or  the  height  of  a column  of  air  of  uniform  den- 

sffy,  exerting  on  its  base  a pressure  equal  to  that  of  the  atmosphere,  is  30  in.  X — = 313860  inches 

ar  26155  feet,  (about  five  miles,)  the  temperature  being  that  of  freez-water 


512 


POLARIZATION  OF  LIGHT. 


Of  the  motion  of  the  gases. — Elastic  fluids,  in  escaping  from  a vessel  by  a small  orifice  or  tube,  into  a 
vacuum,  observe,  like  liquids,  a law  first  discovered  by  Torricelli ; namely,  that  the  velocity  of  the  mole 
cules,  when  they  escape  from  the  orifice,  is  equal  to  that  which  they  would  have  acquired  by  falling 
through  a height  equal  to  the  height  of  a vertical  column  of  uniform  density,  producing  the  same  pres- 
sure as  is  exerted  by  the  gas  at  the  level  of  the  orifice.  Thus,  it  has  just  been  shown  that  the  pressure 
of  the  atmosphere,  when  the  barometer  stands  at  30  inches,  and  the  temperature  is  that  of  freezing,  is 
equal  to  that  which  would  be  produced  by  a column  of  air  of  uniform  density  extending  to  an  altitude 
of  26155  feet.  Now,  putting  g = the  accelerating  force  of  gravity  = 32  feet  per  second,  the  velocity 
which  a heavy  body  would  acquire  by  falling  in  a vacuum  from  a height  of  26155  feet,  is  ^/(2  g X 
26155)  = 8^/26155  = 1294  feet  in  a second;  which,  therefore,  is  the  velocity  with  which  air  rushes 
into  a vacuum.  If  the  temperature  varies,  the  velocity  will  vary  also,  and  will  become  1294  -J (1  -+-  a t). 
For  example,  if  the  temperature  were  16°  centigrade,  (about  61°  of  Fahrenheit,)  the  velocity  would  be 
1332  feet  per  second. 

Since  the  densities  of  the  gases  are  proportional  to  the  pressures  they  support,  air  will  always  rush 
into  a vacuum  with  the  same  velocity,  whatever  its  density  may  be  in  the  vessel  from  which  it  escapes ; 
for  the  homogeneous  column  of  the  same  density,  and  exercising  the  same  pressure  as  the  air  in  the 
vessel,  must,  in  all  cases,  have  the  same  altitude. 

The  velocities  with  which  the  different  gases  enter  a vacuum  are  inversely  as  the  square  roots  of  their 
densities  ; for  they  are  proportional  to  the  square  roots  of  the  altitudes  from  which  the  molecules  are 
supposed  to  fall,  and  these  altitudes  are  inversely  as  the  densities.  Thus,  hydrogen  gas,  the  lightest  of 
all  the  gases,  and  whose  density  is  only  00688  of  that  of  air,  would  enter  a vacuum  with  a velocity  of 
4933  (=1294  divided  by  the  square  root  of  0-0688)  feet  in  a second.  It  is  to  be  remarked,  however, 
that  all  those  laws  relative  to  the  flow  of  gases,  are  rather  inferences  from  theory  than  truths  demon- 
strated by  direct  experiment. 

In  the  case  of  air  or  any  gas  flowing  into  a space  containing  a gas  of  an  inferior  density,  the  velocity 
will  be  the  same  as  that  of  an  incompressible  liquid  of  similar  density  with  the  effluent  gas,  and  capable 
of  exercising  a pressure  equal  to  the  difference  between  the  pressures  of  the  two  gases.  Taking,  for 
example,  the  case  of  a gas  flowing  from  a gasometer  into  the  atmosphere : let  h denote  the  height  of 
the  barometer,  and  h + II  that  of  the  column  of  mercury  exercising  a pressure  equal  to  the  elasticity 
of  the  effluent  gas,  so  that  11  is  the  difference  of  the  two  pressures.  Also,  let  A denote  the  density  of 
mercury,  d that  of  the  gas  in  the  gasometer  corresponding  to  the  pressure  h -f-  H,  and  v the  velocity  per 
second ; then 

Now  if,  in  the  formula p — hd(\  -f-  at ),  we  substitute  the  pressure  in  the  gasometer  (A  -f-  H)  A for 
p,  and  also  for  k its  value  as  above  determined  in  feet,  this  expression  will  become, 

w 1 294  ,/  j (1  + a ()  | , 

where  v is  expressed  in  feet.  If,  therefore,  A denote  the  area  of  the  orifice  in  feet,  the  volume  or  num- 
ber of  cubic  feet  discharged  in  a second  will  be  v A.  It  is  to  be  observed,  that  the  volume  thus  deter- 
mined is  the  volume  of  a gas  of  the  same  density  as  in  the  gasometer ; if  it  were  required  to  find  the 
number  of  cubic  feet,  at  a different  density,  corresponding  to  the  pressure  of  a mercurial  column  whose 
height  = h\  it  would  be  necessary  to  multiply  the  above  expression  by  the  ratio  (h  -}-  H)  —■  h'. 

From  the  experiments  of  D’Aubuisson,  it  has  been  ascertained  that  air,  in  passing  through  an  orifice 
pierced  in  a thin  plate,  forms  a vena  contracta,  whose  area,  as  in  the  case  of  a liquid,  is  065  of  the  area 
of  the  orifice.  The  application  of  cylindric  adjutages  increases  the  quantity  issuing  through  the  orifice 
to  0'93,  and  a conical  tube  to  0'95.  The  length  of  the  adjutage  may  be  20  or  30  times  the  diameter  of 
the  orifice  before  the  discharge  begins  to  be  diminished  by  friction.  If,  therefore,  we  suppose  the  gas 
to  flow  through  a cylindric  tube,  and  assume  the  multiplier  0’93  ; and  also  express  the  area  of  the  orifice 
in  terms  of  the  diameter  of  the  tube,  which  we  shall  suppose  = in  feet ; then,  observing  that  4 A = 
3T4159w2,  the  formula  for  the  number  of  cubic  feet  discharged  in  a second,  the  density  being  measured 
by  h -f  H,  will  become 

945wVlrFH(1+a<)S- 

POLARIZATION  OF  LIGHT.  Light  which  has  undergone  certain  reflections  or  refractions,  or 
been  subjected  to  the  action  of  material  bodies  in  any  one  of  a great  number  of  ways,  acquires  a certain 
modification,  in  consequence  of  which  it  no  longer  presents  the  same  phenomena  of  reflection  and  trans- 
mission as  light  which  has  not  been  subjected  to  such  action.  This  modification  is  termed  the  polari- 
zation of  light ; its  rays  being  supposed,  according  to  particular  theoretical  views,  to  have  acquired 
poles  (like  the  magnet)  or  sides  with  opposite  properties. 

The  polarization  of  light  may  be  effected  in  various  ways,  but  chiefly  in  the  following : 1.  By  reflec- 
tion at  a proper  angle  from  the  surfaces  of  transparent  media,  as  glass,  water,  &c.  2.  By  transmission 

through  crystals  possessing  the  property  of  double  refraction.  3.  By  transmission  tlirough  a sufficient 
number  of  transparent  uncrystallized  plates  placed  at  proper  angles.  4.  By  transmission  through  a 
number  of  other  bodies  imperfectly  crystallized,  as  agate,  mother  of  pearl,  itc.  The  saccharometer 
lately  invented  is  based  upon  this  property  of  light, 

POTASSIUM.  This  extraordinary  metal  was  discovered  by  Davy,  in  the  year  180Y,  and  was  one  of 
the  first  fruits  of  his  researches  into  the  chemical  powers  of  electricity.  Its  properties  are  so  remark 
able,  that  it  was  for  a time  doubted  whether  it  could  with  propriety  be  placed  among  the  metals ; but 
•he  progress  of  discovery  has  removed  all  difficulty  upon  that  point,  by  making  us  acquainted  with 


PRESS,  PROGRESSIVE-LEVER  STEAM. 


513 


other  metallic  substances,  the  properties  of  which  are,  as  it  were,  intermediate  between  those  of  potas- 
sium on  the  one  hand,  and  the  common  metals  on  the  other.  One  of  the  striking  peculiarities  of 
potassium  is  mechanical  rather  than  chemical,  namely,  its  low  specific  gravity,  it  being  the  lightest 
known  solid ; another  is  its  intense  affinity  for  oxygen,  and  its  consequent  energetic  action  when  placed 
upon  water,  where  it  immediately  takes  fire.  The  specific  gravity  of  potassium  is  -865  at  the  tem- 
perature of  60°  ; it  is  solid  at  the  ordinary  temperature  of  the  atmosphere;  at  80°  it  becomes  soft,  and 
at  150°  is  perfectly  liquid;  at  32°  it  is  brittle,  and  has  a crystalline  texture.  In  color  and  lustre  it 
resembles  mercury.  Its  attraction  for  oxygen  is  such  that  it  immediately  loses  its  brilliancy  on  ex 
posure  to  air,  and  becomes  converted  into  potassa. 

PRESS.  Under  the  head  of  hydrostatic  press  will  be  found  a full  description  of  Bramah's  most 
useful  invention,  and  this  is  in  general  use  for  the  billing  of  goods  for  shipment,  for  the  pressing  of  paper 
among  printers  and  lithographers,  for  the  corrugation  of  iron  and  metals.  It  was  used  by  Stephenson 
for  raising  the  tubes  of  the  Conway  and  Menai  Bridges,  and  by  Brunei  for  the  launching  of  the  Levia- 
than. It  is  the  most  compact  of  all  machines  for  the  transfer  and  multiplication  of  power,  but  is  slow 
in  its  operation,  as  usually  the  speed  when  driven  by  power  is  the  same  with  and  without  the  maximum 
lead. 

To  obviate  this  difficulty,  a steam  press  has  been  invented  by  Philos  B.  Tyler,  called  the  Progres- 
sive Lever  Steam,  lGth  January,  1845,  which  is  extensively  used  in  the  baling  of  cotton. 

3099.  3100. 


Looking  to  the  fact  that  at  the  commencement  of  the  operation  the  resistance  is  very  small,  scarcely 
perceptible,  and  gradually  increases  as  the  density  of  the  cotton  increases  under  the  action  of  the  press. 
Mr.  Tyler  conceived  the  happy  thought  of  interposing  between  the  piston-rod  of  the  engine  and  the  fol- 
lower of  the  press,  what  are  known  in  mechanics  as  progressive  levers ; that  is,  levers  so  arranged  that 
at  the  commencement  of  the  operation,  when  the  resistance  presented  by  the  cotton  is  at  its  minimum, 
the  arms  in  connection  with  the  follower  shall  be  at  their  greatest  length,  and  those  in  connection  with 
the  piston  at  their  shortest,  and,  as  the  resistance  increases,  that  these  relations  of  the  arms  of  the  levers 
shall  be  changed  gradually  and  in  proportion  to  the  increasing  resistance  of  the  cotton,  until  at  the  end 
of  the  operation — when  the  cotton  presents  its  maximum  resistance — the  arms  of  the  levers  in  connec- 
tion with  the  piston  shall  be  at  their  greatest  length,  and  those  in  connection  with  the  follower  at  their 
Bh  ortest. 

By  this  combination,  mechanically  true  and  admirably  adapted  to  the  purpose,  Mr.  Tyler  was  enaoled 
to  produce  a steam-press  which  will  compress  a bale  of  cotton  within  the  smallest  practicable  compass 
with  a steam-cylinder  and  piston  of  very  small  capacity,  and  economize  to  the  utmost  the  consumption 
of  steam ; for  at  no  time  from  the  commencement  to  the  end  of  the  operation,  is  there  any  more  steam 
applied  and  consumed  than  what  is  necessary  to  meet  and  overcome  the  resistance  presented  by  the 
cotton  and  the  necessary  friction  of  the  mechanism. 

Vol.  II.— 33 


514 


PRESS,  ANTI-FRICTION  CAM. 


There  are  various  modes  of  applying  the  principle  of  this  invention,  for  there  are  various  modifica- 
tions of  the  progressive  lever,  all  of  which  may  he  employed  to  form  the  connection  between  the  piston 
and  the  follower  of  the  press,  on  the  principle  invented  by  Mr.  Tyler ; but  the  arrangement  selected  and 
adopted  by  bin)  is  represented  in  the  accompanying  engravings,  in  which  Fig.  3009  is  a front,  and  Fig. 
3040  a side  elevation. 

In  this  arrangement  the  bed  a is  inverted  and  attached  to  the  under  side  of  a beam  b of  the  frame, 
•o  the  upper  side  of  which  beam  is  secured  the  cylinder  c,  of  the  steam-engine,  to  avoid  undue  strain  on 
the  frame ; for  in  this  way  the  beam  is  simply  exposed  to  a crushing  force. 

Within  the  cylinder  there  is  a piston  of  the  usual  construction,  the  rod  d of  which  is  provided  on  ojv- 
posite  sides  with  cogs  e e,  to  form  two  racks  which  engage  the  cogs  of  two  sector-racks  ff  that  turn  on 
fulcrum-pins  g g.  As  the  fulcrum-pins  of  these  two  sectors  have  to  bear  the  brunt  of  the  power  applied, 
the  boxes  in  which  they  turn  are  secured  at  the  angles  formed  by  a cross-beam  h,  and  the  sides  ii  of 
the  frame,  and  from  the  under  side  of  this  cross-beam,  there  are  two  diagonal  braces  which  extend  down 
to,  and  rest  on  the  beam  b,  each  side  of  the  steam-cylinder. 

The  sectors  are  connected  with  the  follower  R of  the  press  by  means  of  four  connecting-rods  III l, 
two  on  each  side. 

The  steam-cylinder  is  provided  with  the  requisite  steam  and  discharge  pipes  and  valves,  by  means 
of  which  the  attendant  admits  steam  from  a boiler  to  the  under  side  of  the  piston,  and,  at  the  end  of 
the  operation,  permits  it  to  escape. 

From  the  foregoing  it  will  be  seen  that  when  steam  is  admitted  the  piston  is  forced  up,  which  causes 
the  two  sectors  to  vibrate,  and  by  reason  of  their  connections  to  draw  up  the  follower,  forcibly  com- 
pressing the  cotton  between  its  upper  surface  and  the  under  surface  of  the  bed  until  the  cotton  is  com- 
pressed into  a bale  m , of  the  required  density,  which  is  then  tied  up  in  the  usual  way. 

It  will  be  observed  that  the  line  of  action  of  the  piston-rod  on  the  two  sectors  is  always  at  the  same 
distance  from  their  fulcra,  so  that  these  two  will  be  constant  levers  during  the  entire  operation,  but  the 
connecting-rods  attached  to  the  follower  being  jointed  to  the  sectors,  as  these  vibrate  upwards,  the  lines 
of  the  rods  gradually  approach  the  fulcra ; hence  the  leverage  of  these  connections  gradually  decreases 
during  the  operation  ; and  from  this  it  follows  that  the  leverage  power  with  which  the  piston  acts  on 
the  follower,  gradually  increases  in  the  ratio  of  the  increasing  resistance  of  the  cotton. 

This  is  a good  form  of  press,  both  from  the  soundness  of  the  principle  on  which  it  rests,  and  the  sim- 
plicity of  the  mechanical  arrangement  employed  to  carry  out  that  principle.  In  practice  it  is  found 
to  economize  fuel  and  labor,  and  is  so  easily  managed  by  ordinary  hands  that  it  will  supersede  many 
other  presses  for  this  purpose. 

A press  similar  in  principle  to  this,  but  worked  by  hand  instead  of  power,  is  used  in  many  of  the 
smaller  cotton  factories  for  the  baleing  of  goods. 

PRESS.  Dick’s  Anti- Friction  Cam.  For  punching  and  shearing  iron  and  metals,  a new  principle 
of  press  has  been  introduced  by  Mr.  Dick  of  Meadville,  Pennsylvania,  called  the  anti-friction  cam:  the 
machines  are  extensively  made  at  Holyoke,  Massachusetts.  The  principle  of  their  construction  will 
he  readily  understood  from  the  following  cuts  and  description  : 

Fig.  3103  represents  the  elevation,  Fig.  3103  a section,  and  Fig.  3104  the  combination  of  cams  on  a 
larger  scale  of  one  form  of  these  presses  intended  for  a punch.  A A are  two  eccentric  wheels ; B is  a 
roller  between ; c c are  two  pairs  of  sectors,  constituting  the  hearings  of  the  axes  of  the  eccentric 


310.!.  3103. 


PRESS,  ANTI-FRICTION  CAM. 


515 


wheels ; D D are  sections  of  the  follower  and  bearing  of  the  sectors.  The  axes  of  the  sectors  are  angu- 
lar or  edge  shaped. 

The  centre  roller  B is  made  to  revolve  by  means  of  the  winch  or  lever  E,  which  carries  by  its  tractive 
qualities  the  two  eccentric  wheels  A A,  the  axes  of  which  having  their  bearing  on  the  face  of  the  sectors, 


3104.  3105.  3106. 


are  transferred  the  length  of  their  faces  right  and  left ; and  as  the  sectors  are  edge  shaped  at  their  centre 
of  motion  o o,  they  necessarily  revolve  free  from  the  impediment  of  rubbing  surfaces,  and  consequently 
without  friction. 


When  the  eccentric  wheels  have  made  their  revolution,  the  follower  will  have  moved  the  sum  of  two 
eccentrics.  When  the  press  is  constructed  so  that  the  follower  movis  down,  a spring  G may  be  used  to 
return  the  moving  parts  to  their  places  when  the  press  is  relaxed. 


requiring  but  little  movement  or  traverse  of  the  follower. 

A A,  Fig.  3104,  are  two  eccentric  sectors ; B is  a centre  roller ; C C are  sections  of  the  follower  and 
Bearing.  Fig.  3106  is  an  edge  view  of  the  same,  showing  the  longitudinal  extension  of  the  edges  con- 


516 


FEINTING  MACHINE. 


stituting  the  axes  of  the  sectors.  Fig.  3107  is  a view  of  the  same  as  it  is  set  in  the  frame,  with  one  side 
of  the  frame  removed.  Fig.  3108  is  an  edge  view  of  the  same  with  frame  and  lever  all  complete. 

For  further  illustration  of  mechanical  devices  which  maybe  ranked  among  presses,  see  Embossing 
Machine,  Punching  and  Shearing  Machine,  Printing  Press,  etc.,  etc. 

PRINTING  MACHINE,  S.  W.  Francis’  Patent.  The  principal  feature  of  this  invention  consists  ir. 
arranging  a row  of  hammers  in  a circle,  so  that,  when  put  in  motion,  they  will  all  strike  the  same  place, 
which  is  the  centre  of  the  said  circle.  The  paper  is  not  touched  by  the  operator  till  the  page  is  finished, 
being  worked  by  means  of  a spring  and  catch,  so  connected  with  the  keys,  that  it  moves  the  pa- 
per the  distance  of  one  letter  whenever  a key  is  struck.  On  the  face  of  each  hammer  a letter  is  cut  in 
relief,  in  such  a position,  that  its  impression  on  the  paper  is  parallel  with  those  of  the  others.  When 
within  four  letters  of  the  end  of  the  line,  a little  hell  rings,  giving  notice  to  the  operator  that  the  word, 
if  of  more,  than  one  syllable,  must  he  divided  by  a hyphen.  At  the  end  of  each  line,  the  “car,”  which 
carries  the  paper,  is  drawn  back,  and  the  paper  is  moved  the  distance  of  two  lines,  in  a direction  perpen- 
dicular to  the  printed  line,  by  means  of  a catch  hereinafter  described.  The  keys  are  connected  with 
actions  somewhat  similar  to  those  used  in  pianos,  by  means  of  wires  and  hell-cranks,  which  actuate  the 
hammers.  There  is  also  an  arrangement  for  rendering  the  simultaneous  action  of  two  or  more  hammers 
impossible.  It  is  obvious  that  by  causing  two  or  more  hammers  to  strike  against  each  other,  serious  in- 
;ury  would  be  caused — rendering  machines,  where  key-boards  are  used,  practically  useless. 

Fig.  3109  represents  a top  or  plan  view  of  the  machine  (in part);  fig.  3110  a detailed  section  of  an 
action  and  hammer,  and  fig.  3111  an  open  and  front  view  of  the  stop-bolts  beneath  the  keys,  for  the 
purpose  of  preventing  the  downward  motion  of  more  than  one  at  the  same  time. 

(Fig.  3109).  B is  one  of  the  sides,  which  together  with  the  cross-bars  F and  C,  fig.  3110,  forms  part  of 
the  frame  to  which  all  parts  of  the  mechanism  are  secured.  Fig.  3110.  The  keys  K L , K1  L,  are  disposed 
in  a longitudinal  series  under  the  cross-bar  C.  They  all  carry  a counter  weight  M,  which  brings  them  by 
gravity  to  rest  against  the  board  A.  Their  downward  motion  is  checked  by  a cross-bar  into  which  the 
screw  R enters — two  pi?.s  act  as  guides  for  each  key.  Under  and  between  the  keys,  (fig.  3111,)  a row  of 
vertical  stop-bolts  P Q,  P Q',P"  Q”,  are  pivoted  by  screws^,  It',  It",  and  are  in  contact  with  each  other; 
the  tops  are  bevelled  on  both  sides,  and  are  lodged  in  corresponding  recesses  of  and  between  the  keys.  The 
recesses  are  made  twice  as  large  as  the  tops  of  the  stop-bolts  PQ,  P'  Q',  which  enter  them.  By  this 
arrangement  it  is  impossible  to  bring  down  more  than  one  key  at  the  same  time  ; for  supposing  a key  K', 
depressed,  the  stop-bolt  P Q,  placed  on  the  left  side  of  the  key,  with  all  the  other  stop-bolts  on  the  same 
slide  is  pushed  simultaneously  in  the  same  direction.  The  same  effect  is  produced  on  the  right  side  Tie- 
ginning  with  stop-bolt  P'  Q',  and  so  on.  If,  however,  it  is  attempted  to  bring  down  two  keys  at  once,  all 
the  stop-bolts  between  them,  being  equally  pressed  to  the  left  and  right,  will  keep  their  places  directly 
under  the  spaces  between  the  keys,  whereby  the  two  keys  which  are  acted  upon,  are  prevented  from 
coming  more  than  A of  an  inch. 

(Fig.  3109.)  The  keys  are  connected  with  the  “ actions  ” by  means  of  wires  V,  V,  V,  S,  S',  S’,  and 
bell  cranks  T,  T',  T".  These  actions  and  the  hammers  are  attached  to  a circular  frame  F,  (in  fig.  3110,) 
which  is  fastened  to  central  opening  of  the  board  A,  (fig.  3110).  Each  action  is  composed  of  a rocker  p 
movable  on  a fulcrum,  of  a pawl  p,  having  its  fulcrum  attached  to  the  upper  end  of  the  hammer  at  Z. 
When  a key  K , is  depressed,  that  part  of  it  to  which  the  wire  S is  attached  at  o",  pulls  upon  the  rocker 
p , moving  the  pawl  p,  and  thereby  causing  the  hammer  V to  strike  the  stud  PI. 

(Fig.  3109).  An  arm  h projects,  from  which  hangs  a stud,  fig.  3110,  against  the  end  of  which  all  the 
hammers  are  made  to  strike.  This  arm  moves  on  a cam,  and  is  turned  up  on  either  side,  while  the 
paper  is  put  in  the  car  g' d'  e' , which  moves  on  rails  c,  V . 

The  inking  is  effected  by  a silk  band  p,  which  is  carried  on  four  pulleys  similar  to  l,  secured  .on  two 
sliding  brackets  similar  to  z v.  The  brackets  may  be  elevated  when  the  band  is  inked — it  retaining  ink 
for  four  days.  The  paper  is  carried  upon  a “ car,”  sliding  between  two  rails  c b' ; this  car  consists  of  a 
quadrangular  frame  d'  e'  f g' , supporting  two  rollers  h i',  and  the  heavy  flat  bar  J',  to  which  the  latter  is 
united  by  means  of  levers  p q , n'  n',  and  rod  m' , in  such  a manner,  that  when  J’  is  raised  from  the 
frame,  along  a circle  the  centre  of  which  is  at  n' , the  roller  i'  is  equally  raised  by  moving  round  the 
axis  p q . The  paper  to  be  printed  is  first  placed  upon  the  roller  h1,  the  roller  I is  then  brought  down 
upon  it,  and  the  weight  of  the  bar  J'  causes  the  rollers  to  hold  together. 

The  car  is  propelled  by  a spring  power,  which  consists  of  a spiral  spring  pulling  the  car  by  means  of 
string  s'  passing  over  pulleys  in  a direction  contrary  to  the  lines  to  be  printed.  To  the  opposite  end  of 
the  car  is  atfached  a cord  a',  which,  passing  over  a pulley,  winds  around  a barrel  b" ; the  latter  is  firmly 
mounted  upon  a round  disc  c" , which  is  furnished  with  a row  of  pins  near  the  periphery  thereof,  d is  a 
catch ; on  the  under  side  it  has  a notch,  through  which  the  pins  may  pass  in  one  direction  only ; this  is 
effected  by  means  of  a spring  which  causes  the  opening  by  the  pressure  of  the  pins  against  it,  thus  es- 
tablishing a bar  against  the  passage  of  the  said  pins  ; hence,  against  the  revolution  of  the  disc  in  that 
direction.  The  catch  is  connected  by  a proper  system  of  leverage  with  the  frame  g h and  the. side  of 
the  caseing.  The  frame  bears  against  a stud  by  means  of  a spring,  but  when  acted  upon  by  either  of 
the  levers  L,  (fig.  3110,)  it  will  also  actuate  the  catch  by  withdrawing  the  spring  from  the  said  pressure 
of  the  pins.  The  spring  thus  relaxed  allows  the  passage  of  one  pin,  but  backs  against  the  next  following 
one.  These  are  the  means  employed  to  feed  the  “ car,”  and  consequently  the  paper,  the  distance  of  one 
single  letter,  until  the  whole  line  is  completed. 

The  knob  q",  is  then  pulled  so  as  to  bring  the  stud  PL,  (fig.  3110,)  to  bear  against  the  first  letter  of 
the  next  following  line.  The  moving  of  the  paper  in  a direction  perpendicular  to  the  lines  is  effected  by 
means  of  a spider-wheel  v",  made  fast  to  the  shaft  end  of  the  roller  I,  and  by  means  of  a lever  S",  and 
spring  it.  When  the  car  is  pulled  to  the  right,  one  of  the  spokes  of  the  spider-wheel  v"  is  pressed  against 
the  inclined  side  of  the  lever  S",  and  is  turned  the  distance  of  two  lines ; but  when  the  car  goes  back,  the 
spring  u plays  and  the  position  of  the  spider-wheel  v"  remains  unchanged.  Tht>  pulley  similar  to  l ia 


FEINTING  MACHINE, 


517 


518 


PRESS,  LITHOGRAPHIC  PRINTING. 


free  on  the  shaft  of  the  band  pulley,  and  carries  a ratchet  so  arranged  in  relation  to  a ratchet  wheel  up* 
on  the  shaft,  that  when  the  car  is  moved  to  the  right  the  pulley  turns  freely,  and  when  the  car  moves  te 
the  left,  the  pulley  carries  the  other  pulley  with  it ; the  band  is  thus  caused  to  follow  the  movements  of 
the  car,  and  every  letter  strikes  it  in  a different  place.  The  band  is  placed  between  two  pieces  of  paper, 
a thick  one  below  and  a thin  one  above  ; by  this  means  two  copies  are  printed  at  the  same  time  and 
with  equal  facility. 


The  above  description  with  the  cuts,  explains  fully  the  construction  of  a machine  necessarily  some- 
what complicated,  but  not  necessarily  liable  to  derangement  by  use.  On  examining  the  above  cut  or 
perspective  view  of  the  complete  machine,  it  will  be  seen  to  resemble  a piano  in  its  general  form  and 
arrangements,  in  its  finger-board,  and  in  the  position  of  the  manuscript  or  rather  proof.  The  keys  re- 
spond as  easily  to  the  touch,  and  the  letters  appear  on  the  paper  in  front  of  the  operator.  The  average 
size  of  this  portable  machine  is  two  feet  square,  not  much  larger  than  a writing  desk. 

FRINTING-PRESS,  LITHOGRAPHIC.  Fig.  3109  is  a front  elevation  of  a lithographic  printing  press, 
by  William  Smart,  of  London.  The  principle  of  it  consists  in  the  whole  of  the  press-work,  with  the  ex- 


ception of  the  operation  of  laying  on  and  taking  off  the  paper,  being  performed  by  a series  of  movements 
resulting  from  the  first  motion  given  to  the  machine,  and  not  requiring  the  aid  of  hand  labor  to  perform 
the  work  as  heretofore.  A portion  of  the  standard  frame  is  removed  at  one  end.  A A are  the  stand- 
ard and  body  frames  of  the  machine.  B E is  the  driving-shaft  and  pinion,  receiving  motion  from  steam 
or  any  motive  agent,  and  communicating  the  same  to  the  wheel  C,  which  takes  into  and  geers  with  D, 
thereby  giving  motion  to  the  wheel  G,  which  drives  the  pinion  F.  Keyed  on  the  main  shaft  with  the 


PRINTING  PRESS. 


519 


pinion  F is  a large  toothed  wheel  H,  moving  loosely  on  its  centre  or  shaft,  the  periphery  of  which  i? 
perforated  with  the  stud  holes  at  the  side,  of  sufficient  size  to  enable  the  studs,  when  brought  in  con- 
tact witli  them,  to  enter  into  and  take  hold  of  the  wheel  H ; for  this  purpose  a ring  or  disk  of  metal 
keyed  to  the  main  shaft  with  the  projecting  studs  is  employed,  so  that  by  any  lateral  action,  caused  bv 
a shifting  clutch-box  on  the  main  shaft,  the  wheel  II  may  be  coupled  witli  the  fixed  disk  by  the  studs 
entering  into  and  uniting  the  two  together,  and  revolve  with  the  main  shaft ; mounted,  also,  upon  this 
shaft,  there  is  a concentric  double-action  motion  rack  I,  in  which  a pinion  takes  into,  first  on  the  outside 
thereof,  thereby  causing  the  toothed  wheel  II  to  be  thrown  in  play  during  the  printing  process  in  one 
direction ; and  secondly,  on  the  inside,  by  passing  through  an  opening  in  the  periphery  of  the  rack,  and 
reversing  the  wheel.  J is  a horizontal  rack,  moving  longitudinally  in  the  direction  of  a machine,  in  a 
suitable  iron  bed,  in  geer  with  the  large  toothed  wheel  H.  K is  a wooden  bed  or  sleeper  fixed  to  the 
traversing-frame,  on  which  a rectangular  slab  of  slate  is  fitted  to  receive  the  stone  L at  the  top.  M are 
surplus  head  standards  carrying  the  wetting  and  inking  apparatus  ; this  part  of  the  improvement  con- 
sists in  giving  motion  by  means  of  the  endless  strap  from  the  driving  rigger  on  the  main  shaft  to  the 
doctor  ink-roller,  which  revolves  at  right  angles  with  the  supply  and  distributing  rollers  situated  under- 
neath, in  the  manner  represented  by  the  figures  1,  2,  3,  4,  5,  6,  *7,  8,  9 ; for  example,  by  the  revolution* 
of  the  rollers  2 3 moving  on  the  face  of  the  doctor  they  receive  ink  therefrom  and  convey  it,  through  the 
intervention  of  other  rollers,  to  the  stone,  thereby  completing  the  process  of  inking  in  the  manner  de- 
scribed. N is  the  water-trough  and  sponge-box.  It  consists  of  a vessel  of  water  having  a series  of 
tubes  passing  through  the  bottom  of  the  box  with  their  upper  ends  above  the  surface  of  the  water, 
whilst  their  lower  ends  communicate  with  the  sponge.  A warp  of  cotton  is  placed  in  the  upper  ends  of 
the  tubes,  and  allowed  to  descend  into  the  trough  below  the  water,  which  causes,  by  capillary  att-rs  - 
tion,  the  water  contained  in  the  trough  to  pass  down  the  tubes  in  connection  with  the  sponge,  and 
supply  it  with  water  without  overcharging  it.  This  box  is  brought  down  on  the  surface  of  the  stone 
when  passing  under  for  the  purpose  of  wetting,  and  remains  until  the  subsequent  process  of  inking  is  per- 
formed, when,  upon  the  stone  returning  to  the  centre  of  the  machine  from  which  it  started,  to  receive  the 
paper,  the  action  of  a cam,  so  operating  upon  a vertical  rod  in  connection  with  it,  causes  the  box  to  be 
raised  and  the  stone  to  pass  out  in  readiness  for  the  next  operation.  O is  a small  framing  mounted  on 
the  body  standards  A,  for  carrying  the  scraper  and  tympan-roller  P.  Q is  the  scraper,  fixed  to  a strong 
cross-head,  which  is  regulated  to  any  height  by  the  screw  R in  the  centre.  S is  the  tympan-cloth, 
which  is  fixed  at  one  end  to  a bar  T ; the  other  end  is  coiled  round  a roller  P,  on  the  shaft  of  which  a 
pulley-wheel  is  fixed,  having  a cord  or  rope  bearing  on  it  in  such  a manner  that  by  the  effect  of  this 
rope  passing  over  another  pulley,  suspended  at  a distance  apart,  as  shown,  it  shall  cause,  by  the  action 
of  a weight  at  one  end,  the  tympan-cloth  to  be  kept  stretched,  so  that  when  the  traversing-frame,  witi; 
the  stone,  is  passing  under  the  scraper,  it  may  catch  hold  of  the  bar  T,  and  by  the  onward  motion  of  the 
traversing-frame  unwind  the  tympan-cloth  and  lay  it  over  the  stone  until  it  shall  have  passed  under 
the  scraper  and  completed  the  printing  operation.  When,  by  the  pressure  being  withdrawn  from  un- 
derneath the  stone,  the  weight  suspended  from  the  end  of  the  cord  in  connection  with  the  pulley  P is 
then  the  medium  through  which  the  bed  and  stone  is  driven  back  into  the  centre  of  the  machine  ready 
for  the  next  operation,  by  reason  of  the  weight  acting  in  such  a manner  that  when  the  tympan-cloth 
has  been  unwound  and  placed  on  the  surface  of  the  stone,  the  mode  of  again  winding  it  up  is  only 
effected  by  the  proximity  of  the  bar  T to  the  roller  P producing  the  diminution  in  the  space  from  the 
contraction  of  the  tympan-cloth.  To  apply  the  power  to  the  scraper  and  the  traversing-frame,  a pressui  e 
roller  is  employed,  actuated  by  a cam  producing  pressure  at  given  times,  such  as  when  the  stone  is 
passing  under  the  scraper ; but  as  soon  as  it  has  performed  such  operation  the  pressure  will  be  with- 
drawn, and  the  means  employed  to  assist  its  return  rendered  free  to  act.  There  is  an  arrangement, 
consisting  of  a long  bar  or  bearer  U,  with  a counterbalance  weight  affixed;  this  bar  passes  along  (he 
sides  of  the  frame-work,  and  touches  the  boss  of  the  cam-wheel  V,  to  which  is  attached  a concentric 
arm  revolving  with  it ; the  movement  produced  by  such  means  on  the  long  lever  is  for  throwing  a stop 
behind  the  traversing-frame  and  checking  its  further  progress  when  not  required,  at  the  same  time, 
giving  to  it  an  elasticity  by  the  application  of  a spiral  spring,  so  as  to  prevent  concussion.  On  the 
means  employed  for  throwing  the  driving-wheel  H in  and  out  of  geer,  depends  the  proper  working  of 
the  machine.  The  means  of  employing  studs,  as  described,  consist  in  fixing  two  peripheries  together  bv 
pressing  the  projecting  pins  on  one  periphery  into  the  opposite  holes  in  the  other ; for  this  object  a side 
lever  with  a forked  end  is  placed  in  connection  with  the  clutch-box  on  the  main  shaft,  which  it  shifts 
laterally  within  the  limits  of  its  fulcrum  by  the  rotation  of  a cam  placed  on  the  sides  of  the  toothed 
wheel  Y;  this  lever,  so  acted  upon  by  the  cam,  requires  a corresponding  pressure  to  keep  it  up  to  its 
work.  To  do  this,  the  weight  is  applied  and  attached  to  it  by  a cord  passing  over  the  wheel  Y and  at- 
tached to  the  lever,  so  that  when  the  cam  moves  the  end  of  the  lever  outwards  the  weight  X will  be 
raised,  but  when  it  falls  it  will  tend  to  move  inward  and  throw  out  of  geer  the  coupling  disk  aforesaid. 
When  motion  is  given  to  the  driving-shaft  B by  E,  and  communicated  through  the  train  of  toothed  geer- 
ing wheels  to  the  main  shaft  F,  such  motion,  in  consideration  of  the  parts  arranged  for  such  purposes,  is 
caused  to  move  the  traversing-frame  by  reason  of  the  teeth  of  the  wheel  H taking  into  the  teeth  of  the 
horizontal  rack,  and  propelling  it  in  either  direction  by  the  reversing  rack.  The  rollers  may  be  made 
of  india-rubber  and  keot  cool  in  a trough  of  cold  water. 

PRINTING-PRESS.  We  cannot  do  better  under  this  head  than  to  exhibit  the  various  presses 
manufactured  for  this  purpose,  by  R.  Hoe  & Co.,  of  New  York. 

Type-revolving,  fast  printing-machine. — Fig.  3112.  A horizontal  cylinder  of  about  four  and  a half  feet  in 
diameter  is  mounted  on  a shaft,  with  appropriate  bearings ; about  one-fourth  of  the  circumference  of  this 
cylinder  constitutes  the  bed  of  the  press — the  periphery  of  which  portion  is  adapted  to  receive  the  form 
of  types — the  remainder  is  used  as  a cylindrical  distributing  table.  The  diameter  of  the  cylinder  is  less 
than  that  of  the  form  of  types,  in  order  that  the  distributing  portion  of  it  may  pass  the  impression  cvl 
inders  without  touching.  The  ink  is  contained  in  a fountain  placed  beneath  the  large  cylinder,  fro® 


520 


PRINTING-PRESS. 


PRINTING-PRESS. 


521 


which  it  is  taken  by  a ducter  roller  and  transferred,  by  a vibrating  distributing  roller,  to  the  cylindrical 
distributing  table ; the  fountain-roller  receives  a slow  and  continuous  rotary  motion,  to  carry  up  the  ink 
from  the  fountain. 

The  large  cylinder  being  put  in  motion,  the  form  of  types  thereon  is,  in  succession,  carried  to  four  or 
more  corresponding  horizontal  impression  cylinders,  arranged  at  proper  distances  around  it,  to  give  the 
impression  to  four  or  more  sheets,  introduced  one  by  each  impression  cylinder.  The  fly  and  feed  boards 
of  two  of  the  impression  cylinders  are  similar  to  those  on  the  well-known  double-cylinder  press  ; on  the 
other  two,  the  sheet  is  fed  in  below  and  thrown  out  above.  The  sheets  are  taken  directly  from  the 
feed-board  by  iron  fingers  attached  to  each  impression  cylinder.  Between  each  two  of  the  impression 
cylinders  there  are  two  inking-rollers,  which  vibrate  on  the  distributing  surface  while  taking  a supply 
of  ink,  and  at  the  proper  time  are  caused  to  rise,  by  a cam,  so  as  to  pass  over  the  form,  when  they 
again  fall  to  the  distributing  surface.  Each  page  is  locked  up  upon  a detached  segment  of  the  large 
cylinder,  called  by  the  compositors  a “ turtle,”  and  this  constitutes  the  bed  and  chase.  The  column-rules 
run  parallel  with  the  shafts  of  the  cylinder,  and  are  consequently  straight ; while  the  head,  advertising, 
and  dash  rules  are  in  the  form  of  segments  of  a circle.  A cross-section  of  the  column-rules  would  pre- 
sent the  form  of  a wedge,  with  the  small  end  pointing  to  the  centre  of  the  cylinder,  so  as  to  bind  the 
types  near  the  top ; for  the  types  being  parallel,  instead  of  radiating  from  the  centre,  it  is  obvious  that 
if  the  column-rules  were  also  parallel,  they  must  stand  apart  at  the  top,  no  matter  how  tight  they  were 
pressed  together  at  the  base ; but  with  these  wedge-shaped  column-rules,  which  are  held  down  to  the 
bed  or  turtle  by  tongues,  projecting  at  intervals  along  their  length,  and  sliding  in  rebated  grooves  cut 
crosswise  in  the  face  of  the  bed,  the  space  in  the  grooves,  between  the  column-rules,  being  filled  with 
sliding  blocks  of  metal,  accurately  fitted,  the  outer  surface  level  with  the  surface  of  the  bed,  the  ends 
next  the  column-rules  being  cut  away  underneath  to  receive  a projection  on  the  sides  of  the  tongues, 
and  screws  at  the  end  and  side  of  each  page  to  lock  them  together,  the  types  are  as  secure  on  this  cyl- 
inder as  they  can  be  on  the  old  flat  bed. 

Fig.  3112  represents  a press  with  four  impression  cylinders,  capable  of  printing  10,000  impressions  per 
hour.  Four  persons  are  required  to  feed  in  the  sheets,  which  are  thrown  out  and  laid  in  heaps  by  self- 
acting flyers,  as  in  the  ordinary  cylinder  presses.  A press  with  eight  impression  cylinders  will  print 
16,000  or  more  impressions  per  hour. 


Patent  single  large-cylinder  printing-machine. — Fig.  3113.  This  machine  is  particularly  adapted  to 
book  and  fine  newspaper  work.  It  has  a registering  apparatus  and  sheet-flyer;  also  adjustable  iron 
bearers,  so  that  stereotype  may  be  worked  with  the  same  facility  and  beauty  as  type  forms.  One  boy 
is  required  to  lay  on  the  sheets,  and  the  press  may  be  driven  by  man  or  steam  power.  With  the  same 
attendance,  it  will  print,  say  from  1,000  to  2,000  impressions  in  an  hour,  according  to  the  size  if  the  press 
and  the  quality  of  the  work  desired. 


522 


PRINTING-PRESS. 


Single  small- cylinder  printing-machine.— Fig.  3114.  In  this  press  the  form  of  types  is  placed  upon  a 
flat  bed,  and  the  impression  taken  upon  the  paper  by  means  of  a cylinder,  while  the  form  is  passing 
undei  it.  I he  small  size  of  the  cylinder  allows  the  machine  to  be  constructed  in  a very  compact  man- 
ual* so  as  to  shorten  the  distance  which  the  bed  travels,  thereby  considerably  increasing  the  number  ot 
mnressions  in  a given  time,  beyond  the  single  large-cylinder  press. 


This  machine  is  of  convenient  height  for  use.  One  person  only  is  required  to  feed  down  the  paper 
« hose  position  is  but  a step  from  the  floor.  It  will  give  from  2,000  to  3,000  impressions  per  hour,  with 
perfect  safety  to  the  machinery.  The  printed  sheets  are  thrown  out  by  a fly-frame  in  a uniform  pile. 
Register  sufficiently  accurate  for  newspaper  and  job  work  is  obtained  by  the  patent  feed-guides,  which 
are  attached  to  each  press.  When  required,  a registering  or  pointing  apparatus  is  furnished,  and  the 
press  may  then  be  used  advantageously  for  book-work. 

The  press  is  made  in  the  same  manner  as  the  double-cylinder  press  described  above,  with  buffers 
similarly  arranged  to  prevent  noise. 

Double-cylinder  printing-machine. — Fig.  3115.  In  its  arrangement  this  press  is  similar  to  the  single 
small-cylinder  machine ; except  that  it  has  two  impression  cylinders  each  alternately  giving  an  impression 
from  the  same  form.  The  sheets  are  supplied  by  two  attendants,  and,  if  required  to  print  short  editions 
of  various  sizes,  it  will  be  necessary  to  have  a boy  at  each  end  of  the  press  to  receive  the  printed  sheets ; 
but  where  large  editions  or  forms  of  uniform  size  are  worked,  not  requiring  frequent  changes  of  the 
tape-wheels,  the  self  sheet-flying  apparatus  is  very  efficient  and  economical,  placing  the  printed 
sheets  in  heaps  with  precision,  and  dispensing  entirely  with  the  two  boys  otherwise  required  for  that 
purpose. 

The  large  amount  of  printing  ordinarily  done  on  these  presses,  and  the  consequent  speed  required 
have  rendered  necessary  greatly  increased  strength  and  weight  of  material  in  all  the  parts,  together  witl 


3115 


PRINTING-PRESS, 


523 


524 


PRINTING-PRESS. 


simplicity  in  the  mechanical  arrangements,  and  the  utmost  perfection  of  workmanship.  The  noise  and 
annoyance  occasioned  by  the  concussion  of  the  bed  against  the  springs,  which  are  placed  at  each  end  ol 
the  machine  to  overcome  the  momentum  of  the  bed,  has  been  removed  by  means  of  adjustable  india- 
rubber  buffers  placed  at  the  points  of  contact,  which  in  no  way  interfere  with  the  lively  and  certain 
action  of  the  spiral  springs. 

Patent  machine  card-press. — Fig.  3116.  For  printing  cards  and  small  circulars,  this  machine  is  not 
surpassed.  It  is  worked  by  either  a crank  or  treadle,  and  will  print  from  1,000  to  1,500  cards  per  hour 
and  may  be  used  also  for  printing  note-paper  and  small  circulars.  Its  feeding  apparatus  for  cards  is 
self-acting.  Size  of  chase  inside  61  by  5 inches. 

3116. 


Improved  lithographic-press. — Fig.  3117.  This  is  believed  to  be  the  best  press  in  use  for  lithographic 
printing.  The  side-rods  and  top  beam  are  made  of  wrought-iron ; the  bed  and  stone  are  raised  to  the 
scraper  by  a lever  and  steel  cam,  working  on  a steel  friction-roller;  the  impression  is  regulated  by  a 


single  screw  through  the  top  beam  ; the  scraper  is  hung  on  a pivot,  that  it  may  accommodate  itself  to 
inequalities  in  the  surface  of  the  stone ; the  bed  is  made  of  the  toughest  ash  plated  with  iron,  with  iroit 


PROJECTION. 


525 


runners,  which  run  on  friction-rollers;  the  tympan-frame  is  wrought-iron,  with  screws  and  nuts  for 
stretching  the  tympan.  The  larger  sizes  are  geered,  so  as  to  enable  the  printer  to  take  an  impression 
from  the  largest  stone  with  ease. 

Copperplate-press. — 3118.  The  side-frames,  cylinders,  and  bed  are  made  of  cast-iron;  the  cylinders 
are  turned  and  the  bed  planed  perfectly  true.  The  shafts  through  the  cylinders,  the  braces,  arms,  and 
6crews,  are  of  wrought-iron,  the  bearings  of  composition. 


PROJECTION  Projections  are  of  various  kinds,  according  to  the  situations  in  which  the  eye  is 
supposed  to  be  placed  in  respect  of  the  body  and  the  plane  on  which  it  is  to  be  projected ; but  there 
are  three  which,  by  reason  of  the  frequency  of  their  use,  are  particularly  deserving  of  attention,  namely 
the  orthographic , the  stereographic,  and  the  central  or  gnomonic. 

1.  Orthographic  projection. — In  this  projection  the  eye  is  supposed  to  be  at  an  infinite  distance,  and 
the  plane  of  projection,  i.  e.,  the  plane  on  which  the  representation  is  made,  perpendicular  to  the  direc- 
tion of  the  rays  of  light,  which  are  all  parallel  to  each  other.  The  laws  of  this  projection  are  easily 
deduced.  1.  Any  point  in  space  is  projected  by  drawing  a straight  line  from  it  perpendicular  to  the 
plane  of  projection.  2.  A straight  line  perpendicular  to  the  plane  of  projection  is  projected  into  a point. 
A straight  fine  parallel  to  the  plane  of  projection  is  projected  into  an  equal  straight  line ; and  a straight 
line  inclined  to  the  plane  of  projection,  is  projected  into  a straight  line  which  is  shorter  than  the  first  in 
the  proportion  of  the  cosine  of  the  angle  of  inclination  to  radius.  3.  A plane  surface  perpendicular  to 
the  plane  of  projection  is  jsrojected  into  a straight  line.  4.  A circle  parallel  to  the  plane  of  projection 
is  projected  into  an  equal  circle  ; but  a circle  oblique  to  the  plane  of  projection  is  projected  into  an 
ellipse,  of  which  the  greater  axis  is  equal  to  the  diameter  of  the  circle,  and  the  lesser  axis  is  equal  to 
that  diameter  multiplied  by  the  cosine  of  the  obliquity. 

The  orthographic  projection  has  a multitude  of  applications.  The  plans  and  sections  by  which  arti- 
ficers execute  their  different  constructions  are  orthographic  projections  of  the  things  to  be  constructed  ; 
and  a solid  body  may  be  represented  in  all  its  dimensions  by  orthographic  projections  on  two  planes  at 
right  angles  to  each  other. 

2.  Stereographic  projection  of  the  sphere. — In  this  projection  the  eye  is  supposed  to  be  situated  at  the 
surface  of  the  sphere,  and  the  plane  of  projection  is  that  of  the  great  circle,  which  is  everywhere  90° 
from  the  position  of  the  eye. 

Two  of  the  principal  properties  of  this  projection  are  the  following : 1.  The  projection  of  any  circle  on 
the  sphere  which  does  not  pass  through  the  eye  is  a circle ; and  circles  whose  planes  pass  through  the 
eye  are  projected  into  straight  lines.  2.  The  angle  made  on  the  surface  of  the  sphere  by  two  circles 
which  cut  each  other,  and  the  angle  made  by  their  projections,  is  equal. 

3.  Gnomonic  or  central  projection. — In  this  projection  the  eye  is  situated  at  the  centre  of  the  sphere, 
and  the  plane  of  projection  is  a plane  which  touches  the  sphere  at  any  point  assumed  at  pleasure.  The 


526 


PROVING-  MACHINE,  HYDROSTATIC. 


point  of  contact  is  called  the  principal  point ; and  the  projections  of  all  other  points  on  the  sphere  are 
at  the  extremities  of  the  tangents  of  the  arcs  intercepted  between  them  and  the  principal  point.  As 
the  tangents  increase  very  rapidly  when  the  arcs  exceed  45°,  and  at  90°  become  infinite,  the  central 
projection  cannot  be  adopted  for  a whole  hemisphere. 


PROVING  MACHINE,  HYDROSTATIC,  for  proving  chain-cables.  Figs.  3119,  3120,  3121.  and 
3122  represent  a machine  designed  and  constructed  by  Wm.  M.  Ellis,  engineer,  United  States  Navv 
Yard,  Washington. 

A A,  plan,  Fig.  3119,  water  cistern,  with  three  force-pumps 


PUDDLER’S  BALLS. 


527 


B,  hydrostatic  cylinder.  C C,  wrought-iron  cross-heads.  D D,  wrought-iron  bars,  connecting  cross 
heads  0 C.  F,  granite  sills. 

H,  screw-wheel,  for  forcing  back  the  ram. 

E,  Fig.  3120,  compound  levers,  for  ascertaining  the  strain:  proportion,  1 to  200.  Fig.  3122,  section. 


PUDDLER’S  BALLS,  MACHINE  FOR  COMPRESSING,  by  J.  F.  Winslow,  Troy,  N.  Y.  In  Fig 
3 1 22|,  A is  the  rotating  cam-formed  compresser.  B B,  two  cylindrical  bed-rollers.  C,  leop  or  ball  of  iron, 
resting  upon  and  between  the  two  bed-rollers  in  position  for  being  compressed  by  the  rotating  cam  A. 
D,  helical  shaped  cam,  keyed  on  to  the  neck  of  one  of  the  bed-rollers  B and  revolves  with  it,  and 


528 


PUMPS. 


■which  forces  outward  the  ram  or  hammer  E,  which,  when  released  from  the  cam,  a powerful  helical 
spring  which  is  inserted  into  a cavity  in  the  outer  end  of  the  ram  throws  forward  against  the  loop  ol 
iron  and  upsets  it— the  opposite  end  of  the  loop,  or  ball,  or  bloom  being  supported  against  the  heavy 
flanch  F,  which  is  cast  upon  one  of  the  bed-rollers,  and  serves  as  an  anvil  against  which  to  upset  or 
hammer  the  blooms.  G,  spur-wheel  on  the  end  of  the  shaft  that  supports  the  cam  A.  H,  spur-pinion 
on  the  driving-shaft  I.  This  pinion  works  into  two  others  of  corresponding  size,  one  on  the  end  of  each 
bed-roller.  This  driving-pinion  H being  interposed  between  the  two  on  the  bed-rollers  and  the  spur- 
wheel  G,  gives  the  peripheries  of  all  the  rollers  and  the  cam  a direction  the  reverse  of  the  periphery 
of  the  ball  C,  and  all  being  in  motion  no  waste  or  abrasion  of  the  hot  iron  can  ensue,  as  the  ball  must 
necessarily  revolve  upon  its  axis  and  be  retained  in  proper  place  between  the  rollers  and  compressers 
I,  shipping-bar.  J,  shaft  communicating  with  the  driving  power. 

Advantages. — 1.  Great  expedition  in  shingling  puddlers’  iron,  one  of  these  machines  being  sufficient 
to  do  the  work  for  25  puddling  furnaces.  2.  The  almost  entire  saving  of  shinglers’  wages.  3.  No 
waste  of  iron — turning  out  the  blooms  while  very  hot,  enabling  the  roller  to  reduce  them  to  very 
smooth  and  sound  bars.  4.  Scarcely  no  expense  for  repairs.  5.  A very  small  amount  of  power  re- 
quired to  operate  it.  6.  The  ends  of  the  blooms  being  thoroughly  upset. 

PULLEY.  See  Mechanical  Powers. 

PUMPS. — The  common  pump.  Fig.  3123  represents  a section  of  the  common  suction  pump. 
A 0 is  a cylinder  or  barrel,  in  which  a piston  P is  moved  up  and  down  by  means  of  a piston-rod  R, 
attached  to  the  extremity  of  the  lever,  R H,  of  the  first  kind.  In  the  piston  is  a valve  v lifting 
upwards ; and  at  the  bottom  of  the  barrel  is  another  valve  V,  also  lifting  upwards.  A B is  a pipe, 
passing  from  the  bottom  of  the  barrel  into  the  well  from  which  the  water  is  to  be  raised. 

In  the  downward  stroke  of  the  piston,  it  plunges  amongst  the  water  in  the  barrel  of  the  pump;  the 
valve  Y closes,  and  the  valve  v opens,  and  allows  the  water  to  pass  to  the  upper  side  of  the  piston. 
In  an  upward  stroke  the  valve  v closes,  and  the  valve  V opens,  and,  by  the  pressure  of  the  atmos- 
phere, the  water  follows  the  piston  in  its  ascent,  whereas  the  water  above  the  piston  is  pushed  before 
it,  and  thus  the  fluid  is  discharged  in  a stream  at  the  mouth  C of  the  pump  ; and  so  on  to  any  num- 
ber of  strokes. 

If  a perfect  vacuum  were  formed  by  the  piston  as  it  ascends,  the  water  would  be  raised,  on  an  aver- 
age, to  the  height  of  34  feet  above  the  level  of  the  water  in  the  well,  which  is  the  height  of  a column 
of  water  calculated  to  balance  the  average  pressure  of  the  atmosphere. 

3124. 


The  common  forcing  pump. — This  pump,  Fig.  3124,  raises  water  from  the  well  into  the  barrel  on  the 
principle  of  the  suction  pump  just  described,  Fig.  3123,  and  then  the  pressure  of  the  piston  on  the 
water  elevates  it  to  any  height  that  may  be  required. 

Here  Pisa  solid  piston  working  up  and  down  in  a barrel ; Y a valve,  lifting  upwards,  placed  at  the 
top  of  the  pipe  descending  into  the  well ; v a valve,  also  lifting  upwards,  placed  in  a pipe  D,  which 
conveys  the  water  to  the  cistern. 

In  a descending  stroke  of  the  piston,  the  valve  Y closes  and  the  valve  v opens,  and  the  water,  being 
pressed  before  the  piston,  is  forced  up  the  pipe  D to  the  higher  level  required;  on  the  contrary,  in  an 
ascending  stroke,  the  valve  v closes  by  the  pressure  of  the  external  air  and  the  water  in  the  pipe  D ; 
the  valve  V opens,  and  the  water  rises  into  the  barrel  of  the  pump  by  the  pressure  of  the  atmosphere 
on  the  water  in  the  well ; and  so  on  to  any  number  of  strokes. 

The  forcing  pump  with  an  air-chamber. — This  engine,  Fig.  3125,  merely  differs  from  the  preceding 
one  by  having  an  air-chamber  ecv  connected  with  the  vertical  pipe  D.  This  air-chamber  is  a closea 
vessel,  having  the  pipe  D descending  into  it,  and  a valve  v opening  and  closing  its  communication  with 
the  barrel  of  the  pump.  When  the  piston  P descends,  the  water  is  forced  through  the  valve  v into 
the  air-chamber,  so  that  as  soon  as  the  water  rises  above  the  lower  orifice  of  the  pipe  D,  the  air  in  the 
upper  part  of  the  chamber  is  contracted  or  compressed ; and  this  compression  ot  the  air  causes  it  to 


PUMPS. 


529 


exert  a continuous  pressure  upon  the  surface  of  the  water  in  the  chamber,  which  forces  the  fluid  up 
the  pipe  D,  and  thus  a constant  discharge  into  the  cistern  is  sustained.  In  the  common  forcing  pump 
the  water  is  only  discharged  at  each  downward  stroke  of  the  piston,  whereas,  in  the  present  case,  the 
pressure  of  the  air  in  the  chamber  sustains  the  discharge  through  the  vertical  pipe  D during  the  in- 
tervals taken  up  by  the  upward  strokes  of  the  piston. 

The  great  defect  of  this  engine  is  as  follows  : — after  the  pump  lias  been  some  time  in  action  the  air 
in  the  chamber  becomes  absorbed  by  the  water  passing  through  it,  so  that  at  length  it  is  found  that 
nearly  all  the  air  at  first  in  the  chamber  has  passed  away  with  the  water  discharged  by  the  pump. 

Double-acting  pump . — This  pump,  Fig.  3120,  is  designed  to  remedy  the  defect  of  the  preceding  one.  It 
is  simply  a double-acting  forcing  pump.  P is  a solid  piston  which  moves  up  and  down  in  a cylinder ; the 
rod  of  this  piston  passes  through  a stuffing-box  at  S for  the  purpose  of  keeping  the  cylinder  air-tight.  On 
the  opposite  sides  of  the  cylinder  are  two  pipes  A 11  and  0 D ; where  A B descends  into  the  well,  and 
C D conveys  the  water  to  the  reservoir.  There  are  four  valves  ab  e c opening  and  closing,  as  the  case 
may  be,  the  communication  of  these  pipes  with  the  cylinder.  These  valves  all  lift  in  the  same  direc- 
tion, that  is,  to  the  right.  Suppose  the  cylinder  and  pipes  filled  with  water,  then  in  an  upward  stroke 
of  the  piston,  the  valves  a and  e are  opened,  and  c and  b are  closed ; the  water  is  forced  by  the  piston 
through  the  valve  e and  then  up  the  vertical  pipe  C D ; at  the  same  time  the  water,  by  the  atmospheric 
pressure,  rises  up  the  pipe  A,  and  opening  the  valve  a follows  the  piston  in  its  ascent : on  the  contrary, 
when  the  piston  descends,  the  valves  a and  e are  closed,  and  c and  b are  opened  ; the  water  is  then 
forced  through  the  valve  c,  up  the  vertical  pipe  C 1),  and  the  water  from  the  well  enters  the  cylinder 
through  the  valve  b,  and  follows  the  piston  in  its  descent ; and  so  on  to  any  number  of  strokes. 


3125. 


3120. 


Is 

jp 

T-S- 

' rfj _ 

A 

-tr 

It 

|f- 

III 

: r 

J 

rn 


3127. 


1A 


Another  variation  of  the  forcing  pump,  called  a plunger-pump,  Fig.  312*1,  consists 
in  making  the  piston  of  the  same  length  as  the  cylinder  but  rather  less  in  diame- 
ter, so  that  it  may  be  moved  freely  in  the  former  without  touching  the  sides.  These 
pistons  are  made  wholly  of  metal,  and  turned  smooth  and  cylindrical,  so  as  to 
work  through  a stuffing-box  or  cupped  leathers.  The  quantity  of  water  raised  at 
each  stroke  has  therefore  no  reference  to  the  capacity  of  the  cylinder,  however  large  that  part  of  one 
of  these  pumps  may  be,  for  the  liquid  displaced  by  the  piston  can  only  be  equal  to  that  part  of  the  lat 
ter  that  enters  the  cylinder.  It  is  immaterial  at  what  part  of  the  cylinder  the  forcing  or  ascending  pipe 
is_  attached,  whether  at  the  bottom,  near  the  top,  or  at  any  intermediate  place.  Small  pumps  of  this 
kind  are  now  commonly  employed  to  feed  steam  boilers  and  for  other  purposes,  and  are  worked  by 
levers  like  the  ordinary  lifting  and  forcing  pumps,  the  pistons  being  preserved  in  a perpendicular  posi- 
tion by  slings. 

This  is  one  of  the  most  valuable  modifications  of  the  forcing  pump.  The  friction  of  the  piston  is  not 
only  greatly  reduced,  but  the  boring  of  the  cylinder  is  dispensed  with  ; an  operation  of  considerable  ex- 
pense and  difficulty,  particularly  so,  before  efficient  apparatus  for  that  purpose  was  devised.  Another  ad- 
vantage is  the  facility  of  tightening  the  packing  without  taking  out  the  piston  or  even  stopping  the  pump. 

There  is  another  species  of  plunger-pumps,  Fig.  3128,  in  which  the  stuffing-box  is  dispensed  with,  and 
consequently  the  piston  works  without  friction.  A square  wooden  tube,  or  a common  pump  log  of  suffi- 
cient length,  and  with  a valve  at  its  lower  end,  is  fixed  in  the  well  as  shown  in  Fig.  3128.  The  depth 
of  the  water  must  be  equal  to  the  distance  from  its  surface  to  the  place  of  delivery ; and  a discharging 
pipe  having  a valve  opening  upwards  is  united  to  the  pump  tree  at  the  surface  of  the  water  in  the  well 
The  piston  (a  solid  piece  of  wood)  is  suspended  by  a chain  from  a working  beam,  and  loaded  sufficiently 
with  weights  to  make  it  sink.  As  the  liquid  enters  the  pump  through  the  lower  valve,  and  stands  at 
the^  same  level  within  as  without,  whenever  the  piston  descends,  it  necessarily  displaces  the  water, 
which  has  no  other  passage  to  escape  but  through  the  discharging  pipe,  in  consequence  of  the  lower 
valve  closing.  And  when  the  piston  is  again  raised  as  in  the  figure,  a fresh  portion  of  water  enters  tho 
pump  and  is  driven  up  in  like  manner. 

Vol.  II.— 3+ 


530 


PUMPS. 


Fig.  3129  is  a pump  to  raise  -water  without  any  friction  of  solids;  making  use  of  quicksilver  instead 
of  leather  to  keep  the  air  or  water  from  slipping  by  the  sides  of  the  pistons.  One  form  of  it  is  repre- 
sented by  the  figure.  A is  the  suction-pipe,  the  lower  end  of  which  is  inserted  in  the  water  to  be  raised. 
Its  upper  end  terminates  in  the  chamber  C,  and  is  covered  by  a valve.  The  forcing-pipe  B,  with  a valve 
at  its  lower  end,  is  also  connected  to  the  chamber.  Between  these  valves  a pipe,  open  at  both  ends,  is 
inserted  and  bent  down,  as  in  the  figure.  The  straight  part  attached  to  it  is  the  working  cylinder  of 
the  pump,  and  should  be  made  of  iron.  Another  iron  pipe,  a little  larger  in  the  bore  than  the  last,  and 
of  the  same  length,  is  made  to  slide  easily  over  it.  This  pipe  is  closed  at  the  bottom  and  suspended  by 
chains  or  cords,  by  which  it  is  moved  up  and  down.  Suppose  this  pipe  in  the  position  represented,  and 
tilled  with  mercury — if  it  were  then  lowered,  the  air  in  the  cylinder  and  between  the  valves  would  be- 
come rarified,  and  the  atmosphere  pressing  on  the  surface  of  the  water  in  which  the  end  of  A is  placed, 
would  force  the  liquid  up  A till  the  density  of  the  contained  air  was  the  same  as  before  ; then  by  rais- 
ing the  pipe  containing  the  mercury,  the  air,  unable  to  escape  through  the  lower  valve,  would  be  forced 
through  the  upper  one  ; and  by  repeating  the  operation,  water  would  at  last  rise  and  be  expelled  in  the 
same  way,  •provided  the  elevation  to  which  it  is  to  be  raised  does  not  exceed  thirteen  times  the  depth 
of  the  mercurial  column  around  the  cylinder ; the  specific  gravity  of  quicksilver  being  so  many  times 
greater  than  that  of  water.  When  the  depth  of  the  former  is  30  inches,  the  latter  may  be  raised  as 
many  feet  in  the  suction-pipe  and  forced  up  an  equal  distance  through  the  forcing  one,  making  together 
an  elevation  of  sixty  feet;  but  if  water  be  required  higher,  the  depth  of  the  mercurial  column  in  the 
movable  pipe  must  be  proportionably  increased.  To  make  a small  quantity  of  mercury  answer  the 
purpose,  a solid  piece  of  wood  or  iron  that  is  a little  less  than  the  cylinder  is  secured  to  the  bottom  oi 
the  movable  vessel  as  shown  in  the  centre : this  answers  the  same  object  as  an  equal  bulk  of  mercury. 

These  pumps  have  their  disadvantages  : they  are  expensive  : and  however  well  made,  the  quantity 
of  quicksilver  required  is  considerable — the  agitation  consequent  on  the  necessary  movement  soon  con- 
verts it  into  an  oxide  and  renders  it  useless.  Great  care  is  also  required  in  working  these  machines  : it 


the  movements  are  not  slow  and  regular,  the  mercury  is  very  apt  to  be  thrown  out ; to  prevent  which 
the  upper  end  of  the  vessel  containing  it  is  dished  or  enlarged.  For  the  reasons  above  stated,  they 
have  never  been  extensively  employed  in  the  arts. 

If  a common  atmospheric  pump  be  inverted,  as  shown  in  Figs.  3130  and  3131,  its  cylinder  immersed 
in  water,  and  the  valves  of  the  upper  and  lower  boxes  reversed,  it  becomes  a forcing,  or,  as  it  is  some- 
times named,  a lifting  pump ; because  the  contents  of  the  cylinder  are  lifted  up  when  the  piston  is 
raised,  instead  of  being  driven  out  from  below  by  its  descent.  In  a lifting  pump  the  liquid  is  expelled 
from  the  top  of  the  cylinder— in  a forcing  one  from  the  bottom  : it  is  the  water  above  the  piston  that  is 
raised  by  the  former  ; and  that  which  enters  below  it,  by  the  latter.  The  piston-rod  in  the  figure  is  at- 
tached to  an  iron  frame  that  is  suspended  to  the  end  of  a beam  or  lever.  The  valve  on  the  top  of  the 
piston,  like  that  at  the  end  of  the  cylinder,  opens  upwards.  When  the  piston  descends  (which  it  does 
by  its  own  weight  and  that  of  the  frame)  its  valve  opens  and  the  water  enters  the  upper  part  of  the 
cylinder,  then  as  soon  as  it  begins  to  rise  its  valve  closes,  and  the  liquid  above  it  is  forced  up  the  as- 
cending pipe.  Upon  the  return  of  the  piston  the  upper  valve  is  shut  by  the  weight  of  the  column  above 
it,  the  cylinder  is  again  charged,  and  its  contents  forced  up  by  a repetition  of  the  movements.  Machines 
of  this  description  are  of  old  date.  They  were  formerly  employed  in  raising  water  from  mines. 

Lifting  pump. — The  modern  form  of  this  pump  is  represented  in  Fig.  3132.  The  working  cylinder 
being  generally  metal,  and  having  a strong  flanch  at  each  end ; the  upper  one  is  covered  bv  a plate 
with  a stuffing-box  in  the  centre  through  which  the  polished  piston-rod  moves ; and  the  under  one  bv 
mother  to  which  the  suction-pipe  is  attached,  and  whose  orifice  is  covered  by  a valve. 


PUMPS. 


531 


The  fire-engine. — This  engine,  Fig.  3183,  is  simply  a combination  of  two  forcing  pumps,  having  a 
common  air-chamber  H,  and  the  same  suction-pipe  F descending  to  the  water  intended  to  supply  the 
engine.  The  beam  A B,  turning  on  its  centre  of  motion  K,  works  the  two  pistons  C and  D ; so  that 
while  the  one  is  descending  the  other  is  ascending,  thereby  keeping  up  a continuous  flow  of  water  into 
the  air-chamber  H.  A flexible  tube  E,  of  leather,  called  a hose,  is  attached  to  the  discharge-pipe,  to 
enable  the  engine-man  to  direct  the  stream  of  water  upon  any  particular  spot.  The  degree  of  compres- 
sion attained  by  the  air  in  the  chamber  regulates  the  velocity  with  which  the  water  is  projected  from 
the  nozzle  L of  the  hose. 

If,  for  example,  the  air  be  compressed  to  one  half  its  original  bulk,  then  it  will  act  upon  the  surface 
of  the  water  in  the  chamber  with  a pressure  equivalent  to  that  of  the  atmosphere,  and  the  water  would 
be  raised  in  the  pipe  E to  the  height  of  about  34  feet,  or  it  would  be  projected  from  the  nozzle  L with 
a velocity  equal  to  that  winch  a body  would  acquire  in  falling  freely,  by  the  force  of  gravity,  from  this 
height. 


3131. 


SI  32. 


3133. 


The  chain  pump. — This  engine,  Fig.  3184,  consists  of  a continuous  chain 
A B C,  to  which  are  attached  a series  of  pistons  or  buckets  for  raising  the  water. 
This  chain  passes  downwards  through  the  wooden  tube  E,  and  returns  up>- 
wards  through  C,  extending  over  two  sprocket  wheels  Q and  J.  The  arms  or 
teeth  of  the  upper  wheel  Q,  acting  upon  the  notches  or  teeth  cut  upon  the 
links  of  the  chain,  put  the  chain  of  pistons  or  buckets  in  motion.  The  lower 
portion  C D of  the  ascending  tube  is  lined  with  a brass  barrel,  in  which  the 
pistons  or  buckets  are  fitted ; so  that  whilst  they  are  ascending  through  this 
barrel,  the  water  is  lifted  and  discharged  at  the  top  A of  the  tube.  The 
wheel  Q is  turned  by  a winch,  a shows  the  shape  of  the  links  forming  the  chain,  b the  section  of  the 
piston  or  buckets. 

Rotary  pumps. — Two  cog-wheels,  the  teeth  of  which  are  fitted  to  work  accurately  into  each  other, 
are  inclosed  in  an  elliptical  case.  The  sides  of  these  wheels  turn  close  to  those  of  the  case,  so  that 
water  cannot  enter  between  them.  The  axle  of  one  of  the  wheels  is  continued  through  one  side  of  the 
case,  (which  is  removed  in  the  figure  to  show  the  interior,)  and  the  opening  made  tight  by  a stuffing- 
box  or  collar  of  leather.  A crank  is  applied  to  the  end  to  turn  it,  and  as  one  wheel  revolves,  it  ne- 
cessarily turns  the  other ; the  direction  of  their  motions  being  indicated  by  the  arrows.  The  water 
that  enters  the  lower  part  of  the  case  is  swept  up  the  ends  by  each  cog  in  rotation,  and  as  it  cannot 
return  between  the  wheels  in  consequence  of  the  cogs  being  there  always  in  contact,  it  must  neces- 
sarily rise  in  the  ascending  or  forcing  pipe.  The  machine  is,  therefore,  both  a sucking  and  forcing  one. 
Of  rotary  pumps  this  is  not  only  one  of  the  oldest,  but  one  of  the  best.  Fire-engines  made  on  the  same 
plan  were  patented  about  twenty-five  years  ago  in  England,  and  more  recently  pumps  of  the  same 
kind  in  this  country. 

Rotary  pumps  may  be  divided  into  classes  according  to  the  forms  of  and  methods  of  working  the 
pistons,  or  those  parts  that  act  as  such ; and  according  to  the  various  modes  by  which  the  hutment  is 
obtained.  It  is  tills  last  that  receives  the  force  of  the  water  when  impelled  forwards  by  the  jiiston ; 
it  also  prevents  the  liquid  from  being  swept  by  the  latter  entirely  round  the  cylinder  or  exterior  case, 
and  compels  it  to  enter  the  discharging  pipe.  In  these  particulars  consist  all  the  essential  differences 
in  rotary  pumps.  In  some  the  hutments  are  movable  pieces  that  are  made  to  draw  back  to  allow  the 
piston  to  pass,  when  they  are  again  protruded  till  its  return  ; in  others  they  are  fixed,  and  the  pistons 
themselves  give  way.  It  is  the  same  witli  the  latter;  they  are  sometimes  permanently  connected  to 
the  axles  by  which  they  are  turned,  and  sometimes  they  are  loose  and  drawn  into  recesses  till  the 
butments  pass  by.  In  another  class  the  pistons  are  rectangular,  or  other  shaped  pieces  that  turn  on 
centres,  something  like  the  vanes  of  a horizontal  wind-mill,  sweeping  the  water  with  their  broad  faces 
round  the  cylindrical  case,  till  they  approach  that  part  which  constitutes  the  hutment,  when  they  move 
edgeways  and  pass  through  a narrow  space  which  they  entirely  fill,  and  thereby  prevent  any  watet 


532 


PUMPS. 


passing  with  them.  In  other  pumps  the  butment  is  obtained  by  the  contact  of  the  peripheries  of  two 
wheels  or  cylinders,  that  roll  on  or  rub  against  each  other.  Fig.  3135  is  of  this  kind  : while  the  teeth 
in  contact  with  the  ends  of  the  case  act  as  pistons  in  driving  the  water  before  them,  the  others  are 
fitted  to  work  so  closely  on  each  other  as  to  prevent  its  return.  Fig.  3136  exhibits  another  modifiea- 
lion  of  the  same  principle. 


Eve's  patent  rotary  steam-engine  and  pump. — Within  a cylindrical  case  a solid  or  hollow  drum  A, 
Fig.  3136,  is  made  to  revolve,  the  sides  of  which  are  fitted  to  move  close  to  those  of  the  case.  Three 
projecting  pieces  or  pistons,  of  the  same  width  as  the  drum,  are  secured  to  or  cast  on  its  periphery : 
they  are  at  equal  distances  from  each  other,  and  their  extremities  sweep  close  round  the  inner  edge 
of  the  case,  as  shown  in  the  figure.  The  periphery  of  the  drum  revolves  in  contact  with  that  of  a 
smaller  cylinder  B,  from  which  a portion  is  cut  off  to  form  a groove  or  recess  sufficiently  deep  to  re- 
ceive within  it  each  piston  as  it  moves  past.  The  diameter  of  the  small  cylinder  is  just  one-third  that 
of  the  drum.  The  axles  of  both  are  continued  through  one  or  both  sides  of  the  case,  and  the  openings 
made  tight  with  stuffing-boxes.  On  one  end  of  each  axle  is  fixed  a toothed  wheel  of  the  same  diam- 
eter as  its  respective  cylinder ; and  these  are  so  geered  into  one  another,  that  when  the  crank  attached 


to  the  drum-axle  is  turned  (in  the  direction  of  the  arrow)  the  groove  in  the  small  cylinder  receives 
successively  each  piston ; thus  affording  room  for  its  passage,  and  at  the  same  time  by  the  contact  of 
the  edge  of  the  piston  with  its  curved  part,  preventing  water  from  passing.  As  the  machine  is  worked, 
the  water  that  enters  the  lower  part  of  the  pump  through  the  suction-pipe,  is  forced  round  and  com- 
pelled to  rise  in  the  discharging  one,  as  indicated  by  the  arrows.  Other  pumps  of  the  same  class  have 
such  a portion  of  the  small  cylinder  cut  off,  that  the  concave  surface  of  the  remainder  forms  a contin- 
uation of  the  case  in  front  of  the  recess  while  the  pistons  are  passing ; and  then  by  a similar  movement 


PUMPS. 


as  that  used  in  the  figure  described,  the  convex  part  is  brought  in  contact  with  the  periphery  of  the 
drum  till  the  piston’s  return. 

All  rotary  pumps  are  both  sucking  and  forcing  machines,  and  are  generally  furnished  with  valves  in 
both  pipes,  as  in  the  ordinary  forcing  pumps.  The  butments  are  always  placed  between  the  apertures 
of  the  sucking  and  forcing  pipes. 

There  is  another  class  of  pumps  that  bears  some  relationship  to  the  preceding  ; one  of  these  is  shown 
in  Fig.  3137.  The  butment  consists  of  a curved  flap  that  turns  on  a hinge ; it  is  so  arranged  as  to  be 
received  into  a recess  formed  on  the  rim  or  periphery  of  the  case,  and  into  which  it  is  forced  by  the 

Eiston.  The  concave  side  of  the  flap  is  of  the  same  curve  as  the  rim  of  the  case,  and  when  pushed 
ack  forms  a part  of  it.  Its  width  is,  of  course,  equal  to  that  of  the  drum,  against  the  rim  of  which 
its  lower  edge  is  pressed ; this  is  effected  in  some  pumps  by  springs,  in  others  by  cams,  cog-wheels, 
&c.,  fixed  on  the  axles,  as  in  the  last  one.  The  force  by  which  the  flap  is  urged  against  the  drum  must 
exceed  the  pressure  of  the  liquid  column  in  the  discharging  pipe.  The  semicircular  pieces  on  the  outer 
edge  of  the  case  represent  ears  for  securing  the  pump  to  planks  or  frames,  &c.,  when  in  use.  The  ar- 
rows in  the  figures  show  the  direction  in  which  the  piston  and  water  is  moved. 

Nearly  a hundred  years  before  the  date  of  Watt’s  patent,  Amontons  communicated  to  the  French 
Academy  a description  of  a rotary  pump  substantially  the  same  as  represented  in  Fig.  3187.  It  is, 
figured  and  described  in  the  first  volume  of  Machines  Approuv .,  p.  103  : the  body  of  the  pump  or  case 
is  a short  cylinder,  but  the  piston  is  elliptical,  its  transverse  diameter  being  equal  to  that  of  the  cyl- 
inder, hence  it  performed  the  part  of  two  pistons.  There  are  also  two  flaps  on  opposite  sides  of  the 
cylinder. 

In  other  pumps  the  flaps,  instead  of  acting  as  butments,  are  made  to  perform  the  part  of  pistons ; 
this  is  done  by  hinging  them  on  the  rim  of  the  drum,  of  which,  when  closed,  they  also  form  a part : 
they  are  closed  by  passing  under  a permanent  projecting  piece  or  butment  that  extends  from  the  case 
to  the  drum. 


In  Fig.  3138  the  butment  is  movable.  A solid  wheel,  formed  into  three  spiral  wings  that  act  as 
pistons,  is  turned  round  within  a cylindrical  case.  The  butment  B is  a piece  of  metal  whose  width  is 
equal  to  the  thickness  of  the  wings,  or  the  interior  breadth  of  the  cylinder ; it  is  made  to  slide  through 
a stuffing-box  on  the  top  of  the  case,  and  by  its  weight  to  descend  and  rest  upon  the  wings.  Its  upper 
part  terminates  in  a rod,  which,  passing  between  two  rollers,  preserves  it  in  a perpendicular  position. 
As  the  wheel  is  turned,  the  point  of  each  wing  (like  the  cogs  of  the  wheel  in  Fig.  3135)  pushes  before 
it  the  water  that  enters  the  lower  part  of  the  cylinder,  and  drives  it  through  the  valve  into  the  as- 
cending pipe  A ; at  the  same  time  the  butment  is  gradually  raised  by  the  curved  surface  of  the  wing, 
and  as  soon  as  the  end  of  the  latter  passes  under  it,  the  load  on  the  rod  causes  it  instantly  to  descend 
upon  the  next  one,  which  in  its  turn  produces  the  same  effect.  This  pump  is  as  old  as  the  16th  cent- 
ury, and  probably  was  known  much  earlier.  Besides  the  defects  common  to  most  of  its  species,  it  has 
one  peculiar  to  itself:  as  the  butment  must  be  loaded  with  weights  sufficient  to  overcome  the  pressure 
of  the  liquid  column  over  the  valve,  (otherwise  it  would  itself  be  raised  and  the  water  would  escape 
beneath  it;)  the  power  to  work  this  pump  is  therefore  more  than  double  the  amount  which  the  water 
forced  up  requires.  The  instrument  is  interesting,  however,  as  affording  an  illustration  of  the  early  use 
of  the  sliding-valve  and  stuffing-box;  and  as  containing  some  of  the  elements  of  recent,  rotary  pumps 
and  steam-engines. 

The  pump  represented  by  Fig.  3139  consists  also  of  an  exterior  case  or  short  cylinder  within  which 
a small  and  solid  one  A is  made  to  revolve.  To  the  last  an  arm  or  piston  is  attached  or  cast  in  one 
piece  with  it,  the  sides  and  ends  of  which  are  fitted  to  bear  slightly  against  the  sides  and  rim  in  the 
case.  A butment  B B slides  backwards  and  forwards  through  a stuffing-box,  and  is  so  arranged  (by 
means  of  a cam  or  other  contrivance  connected  to  the  axle  of  the  small  cylinder  on  the  outside  of  the 
case)  that  it  can  be  pushed  into  the  interior  as  in  the  figure,  and  at  the  proper  time  be  drawn  back  to 
afford  a passage  for  the  piston.  Two  openings  near  each  other  are  made  through  the  case  on  opposite 
sides  of  BB,  and  to  these  the  suction  and  forcing  pipes  are  united.  Thus  when  the  piston  is  moved  in 
the  direction  of  the  arrow  on  the  small  cylinder,  it  pushes  the  water  before  it,  and  the  vacuity  formed 
behind  is  instantly  filled  with  fresh  portions  driven  up  the  suction-pipe  by  the  atmosphere  ; aud  when 
the  piston  in  its  course  descends  past  BB  it  sweeps  this  water  up  the  same  wav 


584 


PUMPS. 


Fig.  3140  represents  another  rotary  engine.  This  is  also  a reinvention.  Lure  many  others,  it  con 
gists  of  two  concentric  cylinders  or  drums,  the  annular  space  between  them  forming  the  pump-chamber 
but  the  inner  one,  instead  of  revolving  as  in  the  preceding  figures,  is  immovable,  being  fixed  to  the 
6ides  of  the  outer  one  or  case.  The  piston  is  a rectangular  and  loose  piece  of  brass  or  other  metal 
accurately  fitted  to  occupy  and  move  in  the  space  between  the  two  cylinders.  To  drive  the  piston, 
and  at  the  same  time  to  form  a hutment  between  the  orifices  of  the  induction  and  eduction  pipes,  a 
third  cylinder  is  employed,  to  which  a revolving  motion  is  imparted  by  a crank  and  axle  in  the  usual 
way.  This  cylinder  is  eccentric  to  the  others,  and  is  of  such  a diameter  and  thickness  that  its  interior 
and  exterior  surfaces  touch  the  inner  and  outer  cylinders,  as  represented  in  the  cut,  the  places  of  con- 
tact preventing  water  from  passing : a slit  or  groove  equal  in  width  to  the  thickness  of  the  piston  is 
made  tlirough  its  periphery,  into  which  slit  the  piston  is  placed.  When  turned  in  the  direction  of 
the  large  arrow,  the  water  in  the  lower  part  of  the  pump  is  swept  round  and  forced  up  the  rising  pipe, 
and  the  void  behind  the  piston  is  again  filled  by  water  from  the  reservoir  into  which  the  lower  pipe 
is  inserted.  This  machine  was  originally  designed,  like  most  rotary  pumps,  for  a steam-engine. 

In  others  the  pistons  slide  within  a revolving  cylinder  or  drum  that  is  concentric  with  the  exterior 
one.  Fig.  3141  is  a specimen  of  a French  pump  of  this  kind.  The  hutment  in  the  form  of  a segment 
■is  secured  to  the  inner  circumference  of  the  case,  and  the  drum  turns  against  it  at  the  centre  of  the 
chord  line  ; on  both  sides  of  the  place  of  contact  it  is  curved  to  the  extremities  of  the  arc,  and  the 
sucking  and  forcing  pipes  communicate  with  the  pump  through  it,  as  represented  in  the  figure.  To 
the  centre  of  one  or  both  ends  of  the  case  is  screwed  fast  a thick  piece  of  brass  whose  outline  resem- 
bles that  of  the  letter  D ; the  flattened  side  is  placed  towards  the  butment,  and  is  so  formed  that  the 
same  distance  is  preserved  between  it  and  the  opposite  parts  of  the  butment,  as  between  its  convex 
surface  and  the  rim  of  the  case.  The  pistons,  as  in  the  last  figure,  are  rectangular  pieces  of  stout 
metal,  and  are  dropped  into  slits  made  through  the  rim  of  the  drum,  their  length  being  equal  to  that 
of  the  case,  and  their  width  to  the  distance  between  its  rim  and  the  D piece.  They  are  moved  by  a 
crank  attached  to  the  drum-axle.  To  lessen  the  friction  and  compensate  for  the  wear  of  the  butment, 
that  part  of  the  latter  against  which  the  drum  turns  is  sometimes  made  hollow ; a piece  of  brass  is  let 
into  it  and  pressed  against  the  periphery  of  the  drum  by  a spring. 


In  Fig.  3142  the  axis  of  the  drum  or  smaller  cylinder  is  so  placed  as  to  cause  its  periphery  to  rub 
against  the  inner  circumference  of  the  case.  Two  rectangular  pistons,  whose  lengths  are  equal  to  the 
internal  diameter  of  the  case,  cross  each  other  at  right  angles,  being  notched  so  as  to  allow  them  to 
slide  backwards  and  forwards  to  an  extent  equal  to  the  widest  space  between  the  two  cylinders.  The 
case  of  this  pomp  is  not  perfectly  cylindrical,  but  of  such  a form  that  the  four  ends  of  the  pistons  are 
always  in  contact  with  it.  An  axle  on  the  drum  is  moved  by  a crank.  Fire-engines  have  been  made 
on  the  same  principle. 

Rotary  pumps  are  as  yet  too  complex  and  too  easily  deranged  to  be  adapted  for  common  use.  To 
make  them  efficient,  their  working  parts  require  to  be  adjusted  to  each  other  with  unusual  accuracy 
and  care : their  efficiency  is,  by  the  unavoidable  wear  of  those  parts,  speedily  diminished  or  destroyed. 
The  expense  of  keeping  them  in  order  exceeds  that  of  others ; and  they  cannot  be  repaired  by  ordi 
nary  workmen,  since  peculiar  tools  are  required  for  the  purpose. 

This  remark  holds  true  of  all  the  rotary  pumps  we  have  seen,  including  Gwynne’s,  wdiich  is  nothing 
more  than  Dimpfel’s  fan,  Fig.  1612,  applied  to  raising  water ; it  is  without  the  merit  of  novelty  in  prin- 
ciple, and  in  practice  will  be  found  worthless  for  the  reasons  above  given. 

Reciprocating  rotary  pumps. — One  of  the  obstacles  to  be  overcome  in  making  a rotary  pump,  is  the 
passage  of  the  piston  over  the  butment,  or  over  the  space  it  occupies.  The  apparatus  for  moving  the 
butment  as  the  piston  approaches  to  or  recedes  from  it,  adds  to  the  complexity  of  the  machine ; nor  is 
this  avoided  when  that  part  is  fixed,  for  an  equivalent  movement  is  then  required  to  be  given  to  the 
piston  itself  in  addition  to  its  ordinary  one.  In  reciprocating  rotary  pumps  these  difficulties  are  avoid- 
ed by  stopping  the  piston  when  it  arrives  at  one  side  of  the  butment,  and  then  reversing  its  motion 
towards  the  other ; hence  tjiese  are  less  complex  than  the  former.  They  are,  however,  liable  to  some 
of  the  same  objections,  being  more  expensive  than  common  pumps,  more  difficult  to  repair,  and  upon 
the  whole  less  durable. 

Fig.  3143  consists  of  a close  case  of  the  form  of  a sector  of  a circle,  having  an  opening  at  the  bottom 
for  the  admission  of  wTater,  and  another  to  which  a forcing-pipe  with  its  valve  is  attached.  A movable 


PUMPS. 


535 


radius  or  piston  is  turned  on  a centre  by  a lever  as  represented ; thus,  when  the  latter  is  pulled  down 
towards  the  left,  the  former  drives  the  contents  of  the  case  through  the  valve  in  the  ascending  pipe. 

Fig.  3144  consists  of  a short  horizontal  cylinder;  a portion  of  the  lower  part  is  separated  from  the 
rest  by  a plate  where  the  suction-pipe  terminates  in  two  openings  that  are  covered  by  clacks  cc.  The 
partition  A extends  through  the  entire  length  of  the  cylinder,  and  is  made  air  and  water  tight  to  both 
ends,  and  also  to  the  plate  upon  which  its  lower  edge  rests.  The  upper  edge  extends  to  the  under 
side  of  the  axle  to  which  the  piston  B is  united.  One  end  of  the  axle  is  passed  through  the  cylinder, 
and  the  opening  made  tight  by  a stuffing-box ; it  is  moved  by  a crank  or  lever.  Near  the  clacks  c c two 
other  openings  are  made  through  the  plate,  to  which  the  forcing-pipes  are 
secured.  These  tubes  are  bent  round  the  outside  of  the  cylinder  and  meet 
in  the  chamber  C,  where  their  orifices  are  covered  by  clacks.  Thus  when 
the  piston  is  turned  in  either  direction,  it 
drives  the  water  before  it  through  one  or 
other  of  these  tubes  ; at  the  same  time  the 
void  left  behind  it  is  kept  filled  by  the 
pressure  of  the  atmosphere  on  the  surface 
of  the  liquid  in  which  the  lower  orifice  of 
the  suction-pipe  is  placed.  The  edges  of 
the  pistons  are  made  to  work  close  to  the 
ends  and  rim  of  the  cylinder  by  means  of 
strips  of  leather  screwed  to  them.  Modi- 
fications of  these  pumps  have  also  been 
used  in  England  as  fire  engines.  Watt 
patented  one  in  1782  for  a steam  engine. 

Centrifugal  Pumps.  If  a common  blow- 
ing fan  be  immersed  in  water,  and  put  in 
operation,  the  water  will  be  forced  to  the 
periphery  of  the  wheel,  and  may  be  ele- 
vated in  a rising  main  according  to  the 
velocity  given  to  the  fan.  Fig.  3145  rep- 
resents a side  rim  of  Appold’s  centrifugal 
pump  as  exhibited  at  the  World’s  Fair  in 
London.  It  consists  of  a hollow  disk  or  cylinder,  12  inches  diameter  and  3 inches  wide  on  the  rim,  with  a 
circular  opening  in  the  centre  of  6 inches  diameter.  This  cylinder  is  inclosed  on  both  sides,  excepting  the 
central  opening,  and  is  entirely  open  all  round  the  rim.  The  disk  is  placed  vertically  on  a shaft  passing 
through  its  centre,  and  on  the  end  of  this  shaft  is  fixed  a pulley  for  driving  it.  In  order  to  raise  the 
water,  the  disk  is  placed  in  the  bottom  of  a vertical  trunk,  as  shown  in  fig.  3146. 


In  the  centrifugal  pump,  the  velocity  of  the  circumference  must  be  constant  for  all  sizes  of  pumps 
ior  the  same  height  of  lift ; that  is,  a pump  1 inch  diameter  must  make  twelve  times  the  number  of 
revolutions  per  minute  of  one  12  inches  diameter,  and  both  pumps  will  then  raise  the  water  to  the  same 
height,  but  the  quantity  of  water  delivered  will  he  144  times  greater  than  the  12  inch  pump,  being  in 
proportion  to  the  area  of  the  discharging  orifices  at  the  circumference,  or  the  square  of  the  diameter, 
when  the  proportion  of  breadth  was  kept  the  same,  namely,  one  fourth  of  the  diameter  in  each  case. 

In  Mr.  Appold’s  pump,  a velocity  of  500  feet  per  minute  of  the  circumference  raised  the  water  1 foot 
high,  and  maintained  it  at  that  level  without  discharging  any ; and  a double  velocity  raised  the  water  to 
"our  times  the  height,  as  the  centrifugal  force  was  proportionate  to  the  square  of  the  velocity  ; conse- 
quently, 

500  feet  per  minute  raised  the  water  1 foot  without  discharge. 

1.000  “ “ “ 4 “ “ 

2.000  “ “ “16  “ “ 

4,000  “ “ “ 64  “ “ 

The  greatest  height  to  which  the  water  had  been  raised,  without  discharge,  in  the  experiments  with  the 
1 foot  pump,  was  67’7  feet,  with  a a velocity  of  4,153  feet  per  minute,  beiijg  rather  less  than  the  calcu- 
lated height,  owing  probably  to  leakage  with  the  greater  pressure. 

A velocity  of  1,128  feet  per  minute  raised  the  water  54  feet  without  any  discharge,  and  the  maximum 
effect  from  the  power  employed  in  raisins:  to  the  same  height  54  feet,  was  obtained  at  the  velocity  af 


536 


PUMPS. 


1,678  feet  per  minute,  giving  a discharge  of  1,400  gallons  per  minute  from  the  1 foot  pump.  The  ad- 
ditional velocity  required  to  effect  the  discharge  is  550  feet  per  minute ; or  the  velocity  required  to 
effect  a discharge  of  1,400  gallons  per  minute,  through  a 1 foot  pump,  working  at  a dead  level  without 
any  height  of  lift  is  550  feet  per  minute : consequently,  adding  this  number  in  each  case  to  the  velocity 
given  above  at  which  no  discharge  takes  place,  the  following  velocities  are  obtained  for  the  maximum 
effect  to  be  produced  in  each  case  : 

1,050  feet  per  minute,  velocity  for  1 foot  height  of  lift. 

1.550  “ “ “ 4 feet  “ 

2.550  “ “ “ 16  “ 

4.550  “ “ “ 64  “ “ 

Or,  in  general  terms,  the  velocity  in  feet  per  minute  for  the  circumference  of  the  pump  to  he  driven  to 
raise  the  water  to  a certain  height,  is  equal  to 

550 + (500  f height  of  lift  in  feet). 

In  some  situations  where  it  is  the  most  important  consideration  for  a pump  to  be  quickly  and  readily 
applied,  that  would  discharge  a very  large  quantity  of  water,  the  centrifugal  pump  is  found  very  advan- 
tageous in  such  cases.  In  one  instance,  in  putting  in  the  foundations  of  harbor  works  at  Dover,  a large 
quantity  of  water  of  2,000  to  3,000  gallons  per  minute  was  pumped  out  by  one  of  these  pumps.  The 
centrifugal  pump  had  another  important  advantage  for  such  applications,  from  having  no  valves  in 
action  when  at  work,  which  enabled  it  to  pass  large  stones,  and  almost  anything  that  was  not  too  large 
to  enter  between  the  arms.  The  largest  pump  constructed  at  present  on  this  plan  was  erected  at  Whit- 
tlesea  Mere,  for  the  purpose  of  draining,  and  has  worked  there  nearly  a year  with  complete  success.  The 
pump  is  4£  feet  diameter,  with  an  average  velocity  of  90  revolutions,  or  1,250  feet  per  minute,  and  is 
driven  by  a double-cylinder  steam-engine,  with  steam  40  lbs.  per  inch,  and  vacuum  134  lbs.  per  inch ; 
it  raises  about  15,000  gallons  of  water  per  minute  an  average  height  of  four  or  five  feet. 

Mr.  Appold  considers  the  spiral  form  of  the  arms  an  essential  point  in  his  pump,  instead  of  the  radial 
arms  in  the  other  centrifugal  pumps.  He  at  first  tried  straight  arms  inclined  at  45°,  but  he  found 
that  the  curved  arms  ending  nearly  in  a line  with  a tangent  to  the  outer  circumference  gave  the  greatest 
effect. 

The  comparative  value  of  the  different  forms  of  arms  was  proved  by  the  experiments  at  the  London 
Exhibition  mentioned  before  ; the  curved  arms  gave  a duty  of  68  per  cent.,  the  inclined  arms  43  per 
cent.,  and  the  radial  arms  only  24  per  cent. 

The  Spiral  Pump.  If  we  wind  a pipe  round  a cylinder,  of  which  the  axis  is  horizontal,  and  connect 
one  end  with  a vertical  tube,  while  the  other  is  at  liberty  to  turn  round  and  receive  water  and  air  in  each 
revolution,  the  machine  is  called  a spiral  pump ; it  was  invented,  about  1746,  by  Andrew  Wirz,  a pew- 
terer  in  Zurich,  and  was  employed  at  Florence  with  Bernoulli’s  improvement,  in  1779.  At  Archangel- 
sky,  near  Moscow,  a pump  of  this  kind  was  erected  in  1784,  which  raised  a hogshead  of  water  in  a 
minute  to  a height  of  74  feet,  and  through  a pipe  760  feet  in  length.  Eytelwein  enters  very  minutely 
into  calculations  of  the  effect  of  such  a machine  under  different  circumstances ; and  the  results  of  the 
theory,  as  well  as  of  experiment,  recommend  it  for  common  use,  instead  of  forcing  pumps  of  a more 
complicated  and  expensive  construction.  The  water-tight  joint  presents  the  only  difficulty : the  pipe 
may  form  either  a cylindrical,  a conical,  or  a plain  spiral,  and  it  appears  to  he  uncertain  which  is  the 
most  advantageous ; the  vertical  pipe  should  be  nearly  of  the  same  dimensions  as  the  spiral  pipe. 

The  Screw  of  Archimedes , or  the  Water-Snail , and  the  Water-screw.  The  screw  of  Archimedes  con- 
sists, either  of  a pipe  wound  spirally  round  a cylinder,  or  of  one  or  more  spiral  excavations,  formed  by 
means  of  spiral  projections  from  an  internal  cylinder,  covered  by  an  external  coating,  so  as  to  be  water- 
tight. But  if  the  coating  is  detached,  so  as  to  remain  at  rest  w'hile  the  spirals  revolve,  the  machine  is 
called  a water-screw.  Eytelwein  observes,  that  the  screw  of  Archimedes  should  always  be  so  placed, 
as  to  fill  exactly  one-half  of  a convolution  in  each  turn ; and  that  when  the  orifice  remains  constantly 
immersed,  the  effect  is  very  much  diminished.  When  the  height  of  the  water  is  so  variable  as  to  render 
this  precaution  impossible,  Mr.  Eytelwein  prefers  the  water-screw ; although,  in  this  instrument,  one- 
third  of  the  water  runs  back,  and  it  is  easily  clogged  by  accidental  impurities.  The  screw  of  Archime- 
des is  generally  placed  so  as  to  form  an  angle  of  between  45°  and  60°  with  the  horizon,  but  the  open 
water-screw  at  an  angle  of  30°  only:  for  great  heights,  the  spiral  pump  is  preferable  to  either. 

Belidor's  pressure  engine,  moved  hy  water. — Fig. 

3150:  A conveys  the  descending  column  of  water 
from  its  source  to  the  three-way  cock  F ; to  one  of 
the  openings  of  which  it  is  united.  This  cock  is  con- 
nected, at  another  opening,  to  the  horizontal  cylinder 
C,  whose  axis  coincides  with  that  of  a smaller  one  D. 

Both  cylinders  are  of  the  same  length ; and  their  pis- 
tons are  attached  to  a common  rod,  as  represented  in 
the  figure.  Two  valves  are  placed  in  the  ascend- 
ing pipe  B — one  below,  the  other  above  its  junction 
with  the  cylinder  D.  The  horizontal  pipe  H con- 
nects B and  D with  the  third  opening  of  the  cock. 

By  turning  the  plug  of  this  cock,  a communication 
is  opened  alternately  between  each  cylinder  and  the 
water  in  A.  Thus  when  the  water  rushes  into  C it 
drives  the  piston  before  it  to  the  extremity  of  the 
cylinder,  and  consequently  the  water  that  was  pre- 


PUMPS. 


537 


viously  in  D is  forced  up  the  ascending  pipe  B ; then  the  communication  between  A and  C is  cut  off, 
(by  turning  the  cock,)  and  that  between  A and  D is  opened,  when  the  pistons  are  moved  back  towards  F 
by  the  pressure  of  the  column  against  the  smaller  piston — the  water  previously  in  C escaping  through 
an  opening  shown  in  front  of  the  cock  and  runs  to  waste,  while  that  which  enters  D is  necessarily  forced 
up  B at  the  next  stroke  of  the  pistons.  The  cock  was  opened  and  closed  by  levers,  connected  to  the 
middle  of  the  piston-rod,  and  was  thus  worked  by  the  machine  itself.  By  the  air-chamber  the  discharge 
from  B is  rendered  continuous. 

Suppose  the  water  A has  a perpendicular  fall  of  thirty-four  or  thirty-five  feet,  and  it  was  required 
to  raise  a portion  of  it  to  an  elevation  of  seventy  feet  above  F ; it  will  be  apparent  that  if  both  pistons 
were  of  the  same  diameter,  such  an  object  could  not  be  accomplished  by  this  machine — for  both  cylin- 
ders would  virtually  be  but  one — and  so  would  the  pistons ; and  the  pressure  of  the  column  on  both 
sides  of  the  latter  would  be  equal.  A column  of  water  thirty -five  feet  high  presses  on  the  base  that 
sustains  it  with  a force  of  15  pounds  on  every  superficial  inch;  and  one  of  seventy  feet  high,  with  a 
force  of  30  pounds  on  every  inch ; hence,  without  regarding  the  friction  to  be  overcome,  which  arises 
from  the  rubbing  of  the  pistons,  from  the  passage  of  the  water  through  the  pipes,  and  from  the 
necessary  apparatus  to  render  the  machine  self-acting,  it  is  obvious  in  the  case  supposed  that  the  area 
of  the  piston  in  C must  be  more  than  double  that  in  D,  or  no  water  could  be  discharged  through  B. 
Thus  in  all  cases,  the  relative  proportion  between  the  area  of  the  pistons,  or  diameter  of  the  cylinders, 
must  be  determined  by  the  difference  between  the  perpendicular  height  of  the  two  columns.  When  the 
descending  one  passes  through  a perpendicular  space,  greatly  exceeding  that  of  the  ascending  one,  then 
the  cylinder  of  the  latter  may  be  larger  than  that  of  the  former ; a smaller  quantity  of  water  in  this 
case  raising  a larger  one.  It,  however,  descends  like  a small  weight  at  the  long  end  of  a lever,  through 
a greater  space. 

That  the  force  which  a running  stream  acquires  may  be  made  to  drive  a portion  of  the  liquid  above 
the  source  whence  it  flows,  is  obvious  from  several  operations  in  nature. 

The  hydraulic  ram  raises  water  on  this  principle : a quantity  of  the  liquid  is  set  in  motion  through  an 
inclined  tube,  and  its  escape  from  tire  lower  orifice  is  made  suddenly  to  cease,  when  the  momentum  of 
the  moving  mass  drives  up  a portion  of  its  own  volume  to  an  elevation  much  higher  than  that  from 
which  it  descended. 

The  first  person  who  is  known  to  have  raised  water  by  a ram,  designed  for  the  purpose,  was  Mr. 
'Whitehurst,  a watchmaker  of  Derby,  in  England.  He  erected  a machine  similar  to  the  one  represented 
in  Fig.  3151,  in  1772. 


A represents  the  spring  or  reservoir,  the  surface  of  the  water  in  which  was  of  about  the  same  level 
as  the  bottom  of  the  cistern  B.  The  main  pipe  from  A to  the  cock  at  the  end  of  0,  was  nearly  six 
hundred  feet  in  length,  and  one  and  a half  inch  bore.  The  cock  was  sixteen  feet  below  A,  and  fur- 
nished water  for  the  kitchen  offices,  &c.  When  it  was  opened  the  liquid  column  in  A C was  put  in 
motion,  and  acquired  a velocity  due  to  a fall  of  sixteen  feet ; and  as  soon  as  the  cock  was  shut,  the  mo- 
mentum of  this  long  column  opened  the  valve,  upon  which  part  of  the  water  rushed  into  the  air-vessel 
and  up  the  vertical  pipe  into  B.  This  effect  took  place  every  time  the  cock  was  used,  and  as  water 
was  drawn  from  it  at  short  intervals  for  household  purposes,  “ from  morning  till  night — all  the  days  in 
the  year,”  an  abundance  was  raised  into  B,  without  any  exertion  or  expense. 

The  Belier  hydraulique  of  Montgolfier  was  invented  in  1796.  Although  it  is  on  the  principle  of  the 
one  just  described,  its  invention  is  believed  to  have  been  entirely  independent  of  the  latter. 


538 


PUMPS,  STEAM. 


Fig.  3152  represents  a simple  form  of  Montgolfier’s  ram.  The  motive  column  descends  from  a spring 
or  brook  A,  through  the  pipe  B,  near  the  end  of  which  an  air  chamber  D,  and  rising  main  F,  are  attached 
to  it  as  shown  in  the  figure.  At  the  extreme  end  of  B the  orifice  is  opened  and  closed  by  a valve  E, 
.nstead  of  the  cock  in  Fig.  3151.  This  valve  opens  downwards,  and  may  either  be  a spherical  one,  as 
in  Fig.  3152,  or  a common  spindle  one,  as  in  Fig.  3153.  It  is  the  play  of  this  valve  that  renders  the 
machine  self-acting.  To  accomplish  this,  the  valve  is  made  of.  or  loaded  with,  such  a weight  as  just  to 
open  when  the  water  B is  at  rest;  i.  e.,  it  must  be  so  heavy  as  to  overcome  the  pressure  against  its 
under  side  when  closed,  as  represented  in  Fig.  3153.  Now  suppose  this  valve  open  as  in  Fig.  3152,  the 
water  flowing  through  B soon  acquires  an  additional  force  that  carries  up  the  valve  against  its  seat ; 
then,  as  in  shutting  the  cock  of  Whitehurst’s  machine,  a portion  of  the  water  will  enter  and  rise  in  F, 
the  valve  of  the  air-chamber  preventing  its  return.  When  this  has  taken  place  the  water  in  B has  been 
brought  to  rest,  and  as  in  that  state  its  pressure  is  insufficient  to  sustain  the  weight  of  the  valve,  E 
opens,  (descends ;)  the  water  in  B is  agaiu  put  in  motion,  and  again  it  closes  E as  before,  when  another 
portion  is  driven  into  the  air-vessel  and  pipe  F ; and  thus  the  operation  is  continued,  as  long  as  the 
spring  affords  a sufficient  supply  and  the  apparatus  remains  in  order. 

The  surface  of  the  water  in  the  spring  or  source  should  always  be  kept  at  the  same  elevation,  so  that 
its  pressure  against  the  valve  E may  always  be  uniform — otherwise  the  weight  of  E would  have  to  be 
altered  as  the  surface  of  the  spring  rose  and  fell. 

This  beautiful  machine  may  be  adapted  to  numerous  locations  in  every  country,  and  is  coming  much 
into  use  in  the  agricultural  districts  of  this  country.  When  the  perpendicular  fall  from  the  spring  to 
tlie  valve  E is  but  a few  feet,  and  the  water  is  required  to  be  raised  to  a considerable  height  through  F, 
then,  the  length  of  the  ram  or  pipe  B must  be  increased,  and  to  such  an  extent  that  the  water  in  it  is 
not  forced  back  into  the  spring  when  E closes,  which  will  always  be  the  case  if  B is  not  of  sufficient 
length. 

If  a ran.  of  large  dimensions,  and  made  like  Fig.  3152,  be  used  to  raise  water  to  a great  elevation, 
it  would  be  subject  to  an  inconvenience  that  would  soon  destroy  the  beneficial  effect  of  the  air-chamber 
If  air  be  subjected  to  great  pressure  in  contact  with  water,  it  in  time  becomes  incorporated  with  or 
absorbed  by  the  latter.  This  sometimes  occurs  in  water-rams  ; as  these,  when  used,  are  incessantly  at 
work  both  day  and  night.  To  remedy  this,  Montgolfier  ingeniously  adapted  a very  small  valve  (opening 
inwards)  to  the  pipe  beneath  the  air-chamber,  and  which  was  opened  and  shut  by  the  ordinary  action 
of  the  machine.  Thus,  when  the  flow  of  the  water  through  B is  suddenly  stopped  by  the  valve  E,  a 
partial  vacuum  is  produced  immediately  below  the  air-chamber  by  the  recoil  of  the  water,  at  which 
instant  the  small  valve  opens  and  a portion  of  air  enters  and  supplies  that  which  the  water  absorbs. 
Sometimes  this  snifting-valve,  as  it  has  been  named,  is  adapted  to  another  chamber  immediately  below 
that  which  forms  the  reservoir  of  air,  as  at  B in  Eig.  3153.  In  small  rams  a sufficient  supply  is  found 
to  enter  at  the  valve  E. 

Although  air-chambers  or  vessels  are  not,  strictly  speaking,  constituent  elements  of  water-rams,  they 
ate  indispensable  to  the  permanent  operation  of  these  machines.  Without  them,  the  pipes  would  soon 
oe  ruptured  by  the  violent  concussion  consequent  on  the  sudden  stoppage  of  the  efflux  of  the  motive 
column.  See  Embank' s Hydraulics. 

PUMPS,  STEAM.  Pig.  3154  and  3155  represent  an  independent  steam  pumping  machine,  pa- 
tented in  April,  1849,  by  Worthington-  & Baker,  of  the  city  of  New  York,  and  which  is  undoubtedly- 
the  best  pump  in  use  for  heavy  purposes. 

The  general  principle  involved  in  its  construction  is  the  combination  of  a pump  with  the  steam-cylin- 
ler  that  drives  it  by  direct  action,  without  the  intervention  of  a crank  fly-wheel  or  any  other  device 
for  producing  rotary  motion.  The  steam-cylinder  S is  in  all  respects  similar  to  that  of  an  ordinary 


aigh-pressure  engine,  with  the  parts  as  usually  constructed  for  the  admission  and  emission  of  the  steam. 
The  rod  of  the  piston  which  traverses  in  this  cylinder  is  prolonged  and  attached  to  the  plunger  P of  a 
double-acting  pump. 

The  arm  A is  fastened  to  the  middle  of  the  piston-rod,  and  strikes  the  tappits  or  nuts  on  the  valve- 


PUMPS,  STEAM. 


539 


rod  at  eacli  end  of  the  stroke,  in  order  to  change  the  position  of  the  steam-valve  and  admit  steam  to 
alternate  sides  of  the  piston.  The  necessary  reciprocating  motion  of  the  pump-plunger  is  thus  produced 
in  a very  simple  way,  with  the  least  possible  amount  of  friction  and  loss  of  power. 

The  brief  space  afforded  in  a notice  of  this  description,  will  only  allow  of  a glance  at  the  mechanical 
peculiarities  of  this  machine,  designed  to  overcome  the  difficulties  incident  to  the  direct  application  ol 
steam,  without  availing  of  the  controlling  power  of  the  crank  for  regulating  the  stroke  nor  of  the  ec- 
centric for  producing  the  proper  motion  of  the  steam-valve.  At  low  speed,  more  especially,  the  obvious 
tendency  of  the  motion  is  to  bring  the  steam-valve  directly  over  the  ports,  and  exclude  the  steam  from 
either  end  of  the  cylinder.  The  patentees  have  obviated  this  serious  difficulty  in  a manner  at  once  sim- 
ple and  effective.  By  a peculiar  arrangement  of  the  water  passages  in  the  pump,  the  resistance  is  re- 
duced or  relieved  at  or  near  the  end  of  the  stroke,  and  thus  a momentum  is  suddenly  generated  amply 
sufficient  to  throw  the  valve  wide  open.  A modification  of  the  ordinary  slide-valve,  which  the  patentees 
denominate  a B valve,  is  shown  in  the  drawing,  and  serves  to  admit  the  steam  in  the  proper  direction, 
without  resorting  to  levers  for  changing  the  motion. 

The  pump  shown  at  C,  called  the  double-acting  plunger  pump , consists  of  a plunger  or  plug  P,  work 
ing  through  a ring  R,  which  may  be  made  adjustable,  if  necessary. 

The  course  of  the  water,  as  indicated  by  the  arrows,  is  through  a set  of  valves  resting  upon  seats 
that  radiate  from  a common  centre,  and  covered  in  by  the  cap  A,  Fig.  3154,  which  is  held  firmly  in  its 
place  by  the  single  bolt  B.  As  all  these  valves  are  thus  accessible  at  a moment’s  warning,  a great 
source  of  danger  from  delay  in  relieving  them  from  impediments  is  avoided. 

This  pump  is  in  general  use  on  board  of  steamboats,  and  in  connection  with  stationary  boilers,  both 
on  account  of  its  value  as  an  independent  feed-pump,  and  also  as  a means  of  safety  against  accidents, 
having  been  found  of  great  use  as  a bilge  pump,  and  also  as  a fire  engine. 

This  pump  has  also  been  employed  for  water  supply  in  the  city  of  Savannah,  Ga.,  and  Cambridge, 
Mass.  The  duty  at  the  latter  place  almost  comes  up  to  that  of  the  best  Cornish  Engines.  The 
engines  consist  each  of  two  cylinders  on  the  Wolf  plan,  with  condensers.  The  cylinders  are  concentric, 
the  smaller  being  interior,  and  the  larger  exterior ; the  piston  of  the  latter  being  annular  with  two  rods 
The  whole  machine  is  compact  and  economical,  both  in  first  cost  and  in  working. 


PUMPS.  Carrett’s  Steam  Pump.  Figs.  3156  and  4157  represent  two  views  of  the  pump,  construct- 
ed to  deliver  ten  gallons  per  minute  at  a height  of  130  feet,  the  steam  power  being  derived  from  a 
two-horse  portable  high-pressure  boiler,  complete  in  itself,  and  weighing  under  6 cwt. 


540 


PUMPS,  STEAM. 


Fig.  3157  is  a front  elevation  of  the  pump  and  actuating  steam-cylinder,  and  Fig.  3156  is  a corre- 
sponding side  elevation  or  view,  at  right  angles  to  the  first  figure.  The  steam-cylinder  A is  inverted 
upon  the  horizontal  plate  B,  which  is  bolted  to  the  top  of  the  two-standards  C,  forming  the  framing 
of  the  machine.  These  standards  spring  from  the  chest  D,  which  answers  as  the  base  of  the  whole,  and 
contains  the  influx  and  efflux  vessels  for  the  water.  The  branch  E conveys  the  steam  to  the  slide-valve 
chest  F,  which  is  arranged  in  the  simplest  manner,  the  slide  being  worked  direct  from  the  eccentric  G, 
on  the  crank-shaft  H.  The  crank-shaft  is  carried  in  two  bearings  in  the  cross-piece  of  the  side  stand- 
ards, and  is  connected  to  the  piston-rod  I,  of  the  steam-cylinder,  by  passing  the  cranked-portion,  fitted 
with  a steel  slide  J,  through  the  horizontal  slotted  cross-head  K,  of  the  piston-rod.  The  latter  is  pro- 
longed below  the  cross-head,  for  the  purpose  of  carrying 
the  water-plunger  L,  which  is  bored  out  and  entered 
upon  the  rod,  and  secured  by  set  screws.  When  the 
engine  is  not  required  for  pumping,  the  plunges  is  dis- 
connected by  slackening  these  screws,  and  the  piston- 
rod  then  works  loose  inside  the  plunger  as  a guide,  the 
the  power  of  the  engine  being  then  devoted  to  driving 
other  machinery  by  a belt  on  the  fly-wheel,  or  by  con- 
necting the  crank-shaft  with  the  machinery  to  be  driven, 
by  means  of  a link  or  universal  joint,  which,  in  the 
figure,  is  supposed  to  be  broken  away.  The  whole  of 
the  pump-work  is  shown  by  sectioned  dotted  lines  in  the 
base  chest.  The  pump  cylinder  or  barrel  is  at  M, 
in  the  centre,  and  the  passage  N,  at-  the  top,  forms  the 
communication  with  the  vertical  influx  water-passage 
0,  governed  by  the  conical  lift-valve  P.  The  bottom 
of  this  passage  opens  into  an  air-vessel  Q,  which,  with 
the  corresponding  vessel  for  the  discharge  on  the  oppo- 
site side,  forms  the  chief  feature  of  improvement  in  the 
arrangement.  The  water  is  taken  in  by  a pipe  attached 
by  a union  joint  at  R,  to  the  base  chest.  The  discharge 
is  by  the  opposite  port,  fitted  with  the  lift-valve  S,  which 
opens  into  the  top  passage  T,  communicating  with  the 
top  of  the  discharge  air-vessel  U,  which  has  a discharge 
pipe  attached  at  V. 

It  is  this  neat  combination  of  air-vessels,  with  the  in- 
flux and  efflux  passages,  which  enables  the  pump  to  be 
worked  at  an  effective  speed  without  injury  to  the  differ- 
ent movements,  whilst  a constant  and  regular  delivery 
is  completely  secured.  Without  a provision  of  this  na- 
ture the  barrel  of  the  common  pump  is  only  partially 
filled  at  each  stroke,  and  the  ram  is  consequently  driven 
against  the  surface  of  the  water  with  a serious  shock  at 
each  down  stroke.  On  the  other  hand,  in  Mr.  Carrett’s 

pump,  the  lower  valve,  at  each  ascent  of  the  plunger, 

drains  its  water  supply  from  the  bottom  of  the  induction 
air-vessel ; which  again  is  fully  replenished  by  the  suc- 
tional  power  from  the  reservoir.  When  the  plunger 
descends,  the  water  in  the  barrel  is  driven  through  the 
upper  valve  into  the  discharge  air-chamber,  and  makes 
its  escape  thence  in  a “ continuous  stream,”  under  the 
pressure  of  the  contained  air.  Thus,  the  pump  has  a noiseless  and  perfectly  smooth  action,  with  a uni- 
form delivery. 

Our  plate  shows  the  old  slotted  cross-head  movement  as  adopted  for  returning  the  plunger  at  each 
termination  of  its  stroke,  and  for  this  purpose,  as  there  is  no  great  strain  on  the  working  parts,  this  sim- 
ple plan  has  met  with  an  apt  application.  For  powers  of  pumps  from  three  horses  upwards,  a connect- 
ing-rod and  vertical  slide  movement  is  substituted,  and  this  of  course  is  a much  more  suitable  arrange- 

ment where  the  engine  is  intended  occasionally  to  exert  its  power  through  the  crank-shaft. 

The  slotted  frame  is  not,  however,  a mere  aperture,  as  in  the  original  plan  adopted  in  steam-engines. 
A thin  metal  plate  is  bolted  on  each  side,  so  as  to  provide  projecting  edges  as  guide  flanges  for  the  slide- 
block,  and  to  retain  the  lubricating  oil  on  the  surfaces  where  it  is  wanted. 

Pumps  like  the  preceding,  with  a fly-wheel,  are  better  suited  to  constant  work  than  to  the  variable 
duty  of  feed-pump  to  a boiler.  They  must  be  run  with  sufficient  velocity  that  the  impetus  of  the  fly- 
wheel may  carry  the  valve  sufficiently  far  to  open  the  ports.  This  difficulty,  as  has  already  been  ex- 
plained, has  been  obviated  in  the  Worthington  pump,  by  relieving  the  pressure  on  the  pump  piston 
near  the  conclusion  of  the  stroke.  In  Garrison’s  pump,  also  a direct  action  pump,  this  throw  is  effected 
in  the  steam  chest. 

The  motion  is  somewhat  similar  to  the  working  motion  of  a planing  machine,  fig.  3080.  The  roa 
x is  the  valve,  and  the  weight  r consists  of  a small  piston  working  in  a cylinder  open  at  the  upper  end 
to  the  steam  pressure,  the  other  end  connected  with  the  exhaust.  In  this  way  the  pressure  of  the 
steam  is  made  to  serve  for  the  weight ; other  direct  engines  have  been  constructed  in  which  the  valve 
is  worked  by  another  sma.  1 engine. 


3157. 


PUMPING-ENGINE. 


541 


PUMPING-ENGINE,  erected  at  the  new  Dry  Dock,  Brooklyn  Navy  Yard,  New  York.  The  pumping- 
engine  of  the  new  Dry  Dock,  at  the  United  States  Naval  Station,  New  York,  is  of  the  largest  class, 
and  possesses  many  interesting  features.  It  was  built  at  Kemble’s  West  Point  Foundry,  and  affords 
additional  proof  of  the  capability  of  that  establishment  to  execute  the  most  massive  work  in  the  highest 
degree  of  perfection. 


There  are  but  very  few  specimens  of  large  pumping- engines  to  be  found  in  the  United  States,  those 
if  the  government  dry  docks  at  Norfolk  and  Boston  being  the  most  important.  These,  however,  are 
of  somewhat  antiquated  construction,  and  possess  no  remarkable  qualities  of  excellence.  The  new 
dock  at  New  York  being  the  largest  in  the  country,  and  at  the  most  extensive  naval  station,  it  was 
deemed  important  that  the  machinery  for  exhausting  it  should  be  of  the  most  perfect  kind,  and  of  great 
power  and  capacity  also,  as  but  a very  inconsiderable  amount  of  aid  is  afforded  by  the  recession  ol 
the  tide. 

The  “duty”  required  of  the  engine  was  to  raise  610,000  cubic  feet  of  sea-water  in  three  hours,  dis- 
.ributed  through  different  heights,  as  follows  : 

110.000  cubic  feet  of  water  raised  through  an  average  height  of  21-  feet. 

j.25,000  “ “ 71  “ 

115.000  “ “ 12J  “ 


542 


PUMPING-ENGINE. 


110.000  cubic  feet  of  water  raised  through  an  average  height  of  174  feet. 

110,000  “ “ 22|  “ 

40,000  “ “ 26 

610.000 

The  commission  appointed  to  devise  a plan,  unanimously  adopted  that  shown  in  the  accompanying 
figures,  a brief  description  of  which  is  here  given. 

The  pumps  are  two  in  number,  of  the  kind  denominated  “lifting-pumps,”  each  63  inches  in  diameter 
of  cylinder  and  8 feet  length  of  stroke.  The  suction-pipes  (also  63  inches  in  diameter)  are  extended  tc 
the  bottom  of  the  well,  and  terminate  in  suitable  rose-pieces,  with  ample  apertures  in  the  sides  for  the 


4028. — Elevation  and  Section  of  the  Pumps. 


? 1 1 M f , ..7s...  V 


admission  of  the  water.  By  this  arrangement  a staunch  support  is  furnished  for  the  insistent  weight 
of  the  upper  works  of  the  pumps  and  the  engine  above.  Each  suction-pipe  is  furnished  with  a capa- 
cious branch-piece,  (63  inches  diameter,)  forming  a connection  with  an  air  (or  vacuum)  chamber,  sit- 
uated centrally  between  the  pumps,  and  extending  up  to  the  bottom  of  the  upper  (or  engine)  bed-plate. 
This  air-chamber,  in  addition  to  the  support  received  from  the  branch  pipes,  is  upheld  by  a hollow 
cylindrical  pillar  resting  on  the  bottom  of  the  well.  A continuation  of  this  pillar  is  carried  through  the 
centre  of  the  air-chamber  to  the  under  side  of  the  lower  (or  pump)  bed-plate. 

The  pump-cylinders,  suction  and  branch  pipes,  the  air-chamber  and  its  support,  are  r>f  cast-iron, 


PUMPING-ENGINE. 


543 


flanged  and  ribbed,  as  represented  in  the  figures,  the  pump-cylinders  lieing  lined  with  composition 
metal. 

The  mouths  of  the  pumps  are  placed  at  the  level  of  mean  low  water,  in  a chamber  formed  of  cast- 
iron,  8 feet  wide,  13  feet  high,  and  30  feet  long, — the  bottom  of  the  chamber  forming  a support  to  the 
heads  of  the  pump-cylinders,  as  well  as  a bed-plate  for  the  air-pump  and  condenser  of  the  engine : its 
sides,  strongly  ribbed,  support  the  engine  bed-plate  with  the  superstructure,  and  the  top  is  itself  a part 
of  the  engine  bed-plate.  A culvert  from  the  bay  leads  up  to  one  of  the  sides  of  this  chamber,  and 
serves  as  a conduit  for  the  water  delivered  from  the  pumps.  Twelve  of  the  panels  of  the  side  of  the 


chamber  adjoining  the  conduit  are  open,  and  furnished  with  flap-valves  of  vulcanized  India-rubber, 
opening  outwardly  to  prevent  the  rising  tide  from  flowing  into  the  chamber.  Four  cast-iron  girders  of 
J.  section,  32  inches  deep,  are  placed  transversely  across  the  well,  directly  underneath  the  bottom  of 
this  chamber,  and  are  held  down  to  the  masonry  by  suitable  bolts. 

Ihe  arrangement  of  the  pump-valves  is  of  somewhat  novel  character,  a suction-valve  being  placed 
near  the  bottom  of  each  suction-pipe,  in  addition  to  the  usual  one  near  the  bottom  of  the  pump-cham- 
bers. Each  of  these  valves  is  provided  with  suitable  chests  and  bonnets,  and  is  composed  of  vulcanized 
ndia-rubber,  with  the  usual  metal  guard  above.  A disk  of  India-rubber,  cut  to  the  proper  shape,  with 
punctures  along  its  diameter,  is  slipped  over  standards,  tapped  into  the  valve-seat,  and  secured  by 
washers  and  the  nuts  of  the  guard;  the  India-rubber  alone,  from  its  flexibility,  forming  the  hinge. 

due  valve-seats  are  of  composition  metal,  their  faces  being  indented  in  such  ? manner  as  to  require 


0 44 


PUMPING  ENGINE. 


two  sets  of  valves  to  eaeli  chest,  and  are  divided  into  numerous  apertures  by  narrow  but  deep  bars, 
crossing  each  other  at  right  angles.  This  cross-barring  forms  a support  for  the  flexible  material  of  the 
valve,  and  obviates  all  the  difficulty  to  be  apprehended  from  the  tendency  of  the  valve  to  collapse  on 
being  loaded.  A perfectly  tight  and  quiet-working  valve  is  the  consequence  of  this  arrangement. 

The  pump-rods  are  double,  and  passing  through  stuffing-boxes  in  the  floating  covers  with  which  the 
pumps  are  provided,  take  hold  of  cross-heads  working  in  slides  below  the  engine  bed-plate.  From 
these  cross-heads,  double  connecting-rods  extend  directly  to  the  beam  of  the  engine. 

The  engine  is  a double-acting  condensing  one,  of  50  inches  diameter  of  cylinder,  and  12  feet  length 
of  stroke,  with  an  independent  adjustable  expansion-geer,  so  arranged,  that  as  the  load  upon  the  engine 
is  increased  by  the  lowering  of  the  water  in  the  dock,  a proportionate  increased  amount  of  steam  is  ad- 
mitted into  the  cylinder. 

The  working  beam  is  of  cast-iron,  31  feet  long  between  the  “ end  centres,”  and  4 feet  deep  at  the 
“ main  centre,”  strongly  flanged  and  bossed.  The  piston-rod  is  attached  to  the  beam  by  a parallel 
motion;  the  main-pump  and  air-pump  rods  are  connected  to  it  by  double  rods  and  links,  the  air-pump 
cross-head  working  in  slides  attached  to  the  columns  of  the  engine-frame.  The  balance-wheel  is  of 
cast-iron,  25  feet  in  diameter,  a cross  section  of  its  rim  having  an  area  of  about  80  square  inches.  Its 
arms  (eight  in  number,)  unite  in  a centre  case,  having  compartments  to  receive  their  tapered  ends. 

The  condenser  is  formed  from  a portion  of  the  air  or  vacuum  chamber  before  described,  a partition 
being  placed  in  that  portion  of  it  which  extends  above  the  engine  bed-plate.  The  air-pump  stands  level 
with  the  condenser.  The  air-pump  rod  and  bucket,  foot-valve  and  seat,  are  of  composition  metal.  The 
length  of  stroke  is  42  inches,  the  diameter  of  the  cylinder  44  inches.  The  interior  of  the  cylinder  is 
lined  with  composition  metaL 

The  piston,  cylinder-cover,  and  steam  chests,  side-pipes,  valves,  and  valve-geering,  are  all  nearly 
identical  with  those  used  in  the  best  specimens  of  American  steamboat  engines.  The  boilers  are  three  in 
number,  2G  feet  long,  and  of  7 feet  diameter  in  the  waist,  built  on  the  ‘ ‘ single  return  drop  flue  ” plan. 
They  are  fed  by  the  direct  action  steam-pumps  of  Worthington  and  Baker  of  New  York. 

PUMPING  ENGINES.  For  the  water  supply  of  cities  the  Cornish  Engine  (q.  v.)  for  this  purpose 
affords  the  highest  rate  of  duty.  We  know  of  no  others  that  are  remarkable  either  in  construction  or 
duty,  except  the  one  at  Cambridge,  Mass.,  already  spoken  of,  and  one  at  Hartford,  Conn.  The  pecu- 
liarity of  the  latter  consists  in  the  arrangement  of  the  piston  in  the  pump  cylinders : there  are  two 
pistons  in  each  cylinder,  the  piston-rod  of  the  lower  passing  through  that  of  the  upper,  and  so  arranged 
in  their  alternate  movements,  that  the  flow  of  water  is  nearly  continuous.  They  are  actuated  by  cams, 
driven  by  a vertical  steam  engine,  working  very  expansively. 

PUMP,  LEEGIIWATER  STEAM. — Drainage  of  the  Haarlem  Lake , Holland.  In  order  to  ascertain 
the  most  approved  method,  and  at  the  same  time  the  most  economical  manner,  of  draining  this  lake,  the 
Dutch  government  appointed  a commission  of  engineers  to  report  upon  the  best  means,  and  to  examine 
the  various  plans  of  drainage  adopted  in  England.  After  examining  a great  variety  of  schemes  and 
proposals,  it  was  determined  to  adopt  the  plan  submitted  by  Mr.  Joseph  Gibbs  and  Mr.  Arthur  Dean. 
It  is  proposed  to  have  three  engines  of  the  same  power,  and  three  sets  of  pumps.  The  first  of  these 
engines  is  now  in  operation,  and  is  shown  in  Figs.  3158  to  3161. 

Description  of  the  engines.  The  Leeghwater  Engine,  as  shown  in  the  figures,  has  two  steam  cylinders 
A and  C,  one  within  the  other,  united  to  the  same  bottom  X ; but  the  inner  one  is  not  attached  at  the 
top,  a clear  space  of  1^-  inch  existing  between  it  and  the  cover,  which  serves  for  both  cylinders.  The 
large  cylinder  A,  is  144'37  inches  diameter,  and  1^-  inch  thick;  and  C,  the  small  cylinder,  8D25  inches 
diameter,  and  If  inch  thick ; both  are  truly  bored  out,  and  the  small  cylinder  is  also  turned  on  its  outer 
circumference.  B is  a steam-jacket  for  the  large  cylinder,  cast  in  13  segments — which  is  again  enve- 
loped in  a wooden  casing  l , having  4 inches  of  peat  ashes  between  them. 

Pistons. — The  small  cylinder  C is  fitted  with  a plain  piston  of  5474-81  square  inches  area,  and  tho 
large  cylinder  A is  occupied  by  an  annular  piston  of  10323-36  square  inches  area.  The  areas  of  the 
two  cylinders,  after  deducting  472'8  square  inches  for  the  thickness  of  small  cylinder,  are  as  1 to  2-85. 
The  internal  and  external  packings  of  the  pistons  consist  of  hard  cast-iron  segments  at  bottom,  with 
gasket  above,  pressed  down  by  glands,  also  in  segments;  the  qpen  spaces  in  the  pistons  cc  are  filled 
with  cast-iron  plates,  and  the  tops  of  the  pistons  have  movable  cast-iron  covers. 

Cap  or  cross-head. — The  pistons  are  connected  to  the  great  cap  or  cross-head  G,  by  the  main  piston- 
rod  Y,  of  12  inches  diameter,  and  by  four  small  rods  y,  of  4£  inches  diameter,  (Fig.  3158.) 
The  great  cap  G has  a circular  body  9 feet  6 inches  diameter,  divided  into  eight  compartments,  which 
can  be  filled  with  cast-iron  weights ; from  its  centre  a guide-spindle  z,  passes  through  a stuffing-box 
placed  in  the  centre  of  a great  beam  of  timber  2 feet  square,  which  passes  across  the  engine-house,  and 
is  secured  to  its  walls ; there  are  two  other  guide-rods  b,  which  pass  through  stuffing-boxes  in  the  arms 
of  the  great  cap  G,  and  are  secured  to  the  upper  and  lower  spring  beams. 

Plungers. — Suspended  from  the  arms  of  the  great  cap  are  two  9-inch  plunger-poles  F,  working  ir. 
plunger-cases  D ; attached  to  D are  two  valve-nozzles  d'\  connected  with  stand-pipes  d\  by  two  branch 
pipes  d" ; the  valve-nozzles  are  connected  with  each  other  and  a hydrostatic  equilibrium  valve-nozzle 
O,  from  the  bottom  of  which  a branch  piece  is  connected  with  the  stand-pipes  d by  the  pipes  d"".  The 
exterior  surfaces  of  the  plunger-cases  D are  turned  truly,  so  as  to  allow  the  rings  e e to  slide  up  and 
down  freely  ; the  rings  are  suspended  from  the  great  cross-head  by  rods  v,  and  are  furnished  with  cross- 
bearings,  on  which  the  jaws  of  the  two  air-pump  balance-beams  E rest : the  inner  ends  of  these  balance- 
beams  move  in  a perfectly  vertical  line,  and  the  outer  ends  are  furnished  with  rollers  working  between 
guides,  to  allow  for  the  variation  of  the  beams  during  the  up  or  down  stroke. 

Air-pump. — From  the  centre  of  the  air-pump  balances,  the  two  air-pump  plunger  pistons  n are  sus- 
pended, (Fig.  3159;)  diameter  of  plunger  pistons  40  inches,  stroke  5 feet;  the  two  air-pumps  N are 
united  by  a branch  piece  with  the  bottom  of  the  condenser  M.  The  condenser  has  an  intermittent  in 


PUMP,  LEEGHWATER  STEAM. 


545 


jeclion  by  a valve  8 inches  diameter,  and  a constant  injection  by  another  valve  of  3 inches  diameter, 
it  is  the  condenser  cistern. 

Pipes  and  valves. — L is  the  steam-pipe  (2  feet  diameter)  from  the  boilers ; in  it  is  placed  a double 
beat  governor-valve  of  16  inches  diameter. 

P,  the  induction-valve,  10  inches  diameter  and  nozzle. 

Q,  Equilibrium-valve,  20  do.  do.  do. 

S,  Eduction-valve,  26  do.  do.  do 

q , Equilibrium  steam-pipe. 

The  induction  and  equilibrium  nozzles  are  each  connected  to  a separate  port  cast  in  the  cylinder’s  bot- 
tom. The  eduction  nozzle  is  connected  by  a pipe  M,  34  inches  diameter,  to  the  branch-pipe  M of  the 
condenser.  The  pipe  M is  also  connected  to  the  bottom  of  the  cylinder,  in  which  a port  is  cast,  which 
communicates  with  the  space  under  the  annular  piston;  by  this  arrangement  a constant  vacuum  is 
maintained  beneath  that  piston. 


The  hand-geer  is  connected  to  the  weigh-post  K,  and  the  plug-rod  is  worked  by  a lever  and  shaft  T, 
the  outer  end  of  which  is  slotted  and  worked  by  a pin  on  the  sliding-ring  e. 

Pumps.—  The  engine  works  eleven  pumps  of  63  inches  diameter ; each  pump  is  furnished  with  a 
cast-iron  balance-beam  H,  (Fig.  3158,)  which  radiates  from  the  centre  of  the  piston-rod  ; the  inner  and 
outer  arms  are  of  equal  lengths  from  the  centre  gudgeon.  The  inner  ends  of  the  balance-beams  are 
furnished  with  cast-iron  rollers,  working  against  a plate,  fitted  with  guides  for  each  roller,  which  is 
screwed  up  against  the  under  side  of  the  great  cap ; each  beam  is  connected  to  the  cap  by  two  slotted 
bridles,  to  insure  simultaneous  upward  motion  during  the  up-stroke  of  the  engine.  From  the  outer  end 
of  the  balance-beam  the  pump  piston  is  suspended  by  wrought-iron  rods,  3 inches  diameter  and  16  feet 
long,  and  an  additional  length  of  14  feet  of  patent  chain  cable  attached  to  the  pump  piston.  Fio\  3160 
shows  a section  of  one  of  the  pumps,  and  Fig.  3161  an  elevation  of  the  piston.  A,  working  barrel,  63 
inches  diameter  ; B,  windbore  and  clack  piece  ; C,  the  piston  or  bucket ; D,  bottom  valve  and  seat 
Vol.  II. — 35 


546 


PUMP,  LEEGHWATER  STEAM. 


The  pump  piston  C is  of  a peculiar  construction ; it  is  composed  of  a wrought-iron  centre-piece,  1 inch 
thick ; firmly  bolted  to  this  piece  are  two  double  elbow  frames  of  cast-iron,  called  “ the  cradles ;”  the 
elbows  are  faced  with  gun-metal  plates ; the  cradles  serve  to  support  two  wrought-iron  semi-elliptic 
valves  cc,  which  occupy  the  whole  area  of  the  pump  when  they  fall  out,  and  constitute  in  fact  the  pis- 
ton. These  valves  are  edged  with  wood,  having  a piece  of  leather  on  the  upper  side  secured  by  a 
wrought-iron  gland ; the  valves  are  hung  to  the  centre-piece  at  about  3 inches  from  their  lower  edges, 
so  that  when  they  open  during  the  down  stroke,  any  dirt  or  sand  which  has  lodged  on  the  bottom  may 
fall  through.  Attached  to  the  centre-piece  are  two  plates  of  cast-iron,  which  serve  as  ballast  to  sink 
the  piston ; these  ends  are  cast  with  a jaw,  in  which  pieces  of  wood  are  secured  to  prevent  friction 
against  the  sides  of  the  pump,  and  to  give  steadiness  to  the  piston.  These  pistons  require  a weight  of 
1'4  lb.  per  square  inch  of  the  area  of  the  pump  to  sink  them  with  the  velocity  required  upon  the  down 
stroke.  The  pump  pistons  of  the  Leeghwater  are  not  furnished  with  guides,  as  shown  in  Figs.  3160  and 
3161,  and  work  very  well  without  them : but  the  pistons  for  the  pumps  of  the  Cruquius  and  Van  Lyn- 
den  engines  (now  constructing  for  the  drainage  of  the  lake)  will  have  guides,  in  consequence  of  the 
diameter  of  the  pumps  being  increased  to  73  inches. 

Ptimp  valves. — The  bottom  valves  have  cast-iron  seats  secured  to  the  windbore,  the  valve  beats  are 
of  wood,  and  the  valves  are  simply  plates  of  wrought-iron,  1 inch  thick ; the  valves  are  not  hung  on 
tired  joints,  but  are  each  fixed  to  a bar,  the  ends  of  which  are  entered  in  cast-iron  slot-pieces,  allowing 
a rise  of  1 J inch,  so  that  the  valve  can  rise  altogether  from  its  beat,  and  give  a large  water  passage  all 
round. 

Power  of  engines. — The  steam  and  pump  pistons  both  perform  a stroke  of  10  feet  in  length:  each 
pump  by  calculation  should  deliver  6'02  tons  of  water  per  stroke,  or  66'22  tons  for  the  eleven  pumps; 
but  by  actual  admeasurement  of  the  quantity  delivered,  it  is  found  to  be  63  tons.  The  loss  might  be 
reduced,  but  probably  at  the  expense  of  increased  friction. 

The  engine-house  is  a massive  circular  tower,  concentric  to  the  cylinders ; on  its  walls  are  placed  the 
eleven  pump  balances  radiating  from  its  centre.  The  eleven  pump  balances  are  so  placed  as  in  no  way 
to  disturb  the  equilibrium  of  the  great  cap  of  the  engine,  under  which  the  inner  ends  of  all  the  balances 
are  concentrated.  If  any  of  the  pumps  require  repairs,  the  opposite  pairs  can  be  easily  detached,  with- 
out causing  more  than  a trivial  delay  to  the  working  of  the  engine. 

The  astion  of  the  engine  is  very  simple  ; the  steam  being  admitted  into  the  small  cylinder,  the  whole 
of  the  dead  weight  and  pump-balance  beams  attached  to  the  great  cross-head  are  elevated  with  it,  and 
the  steam  being  cut  off  at  such  portion  of  the  stroke  as  may  be  required,  the  remainder  is  effected  by 
the  momentum  acquired  by  the  dead  weight  and  the  pressure  of  the  expanding  steam  upon  the  small 
piston,  (the  pump  pistons  at  the  same  time  make  their  down  stroke ;)  at  the  end  of  the  up  stroke  a 
pause  of  one  or  two  seconds  is  requisite,  to  enable  the  valves  of  the  pump  pistons  to  fall  out,  so  that 
upon  the  down  stroke  of  the  steam  piston  they  may  take  their  load  of  water  without  shock.  During 
this  time  it  is  necessary  to  sustain  the  great  cross-head  and  its  load  of  dead  weight  at  the  point  to  which 
it  was  elevated  by  the  up  stroke,  as  otherwise  it  would  fall  back  until  the  expanded  steam  under  the 
small  piston  was  compressed  to  a density  equal  to  the  pressure  per  square  inch  of  the  load  lifted,  or 
would  cause  a very  violent  shock  upon  the  pump-valves  by  suddenly  throwing  them  out  against  the 
sides  of  the  pumps.  To  avoid  these  evils  the  hydraulic  apparatus  D F was  devised. 

Hydraulic  apparatus. — When  the  engine  makes  its  up  stroke,  the  plunger-poles  F (which  form  part 
of  the  dead  weight)  are  lifted,  and  the  water  from  the  stand-pipes  and  reservoirs  d'  flows  through  the 
valves  d",  and  follows  up  the  plunger-poles  as  fast  as  they  are  elevated.  At  the  end  of  the  stroke  the 
spherical  valves  instantly  close,  and  the  dead  weight  is  suspended  exactly  at  the  point  at  which  it  had 
arrived — and,  of  course,  if  the  valves  are  tight,  could  be  maintained  there  for  any  given  period ; in  con- 
sequence of  all  strain  being  thus  removed,  there  is  no  pressure  to  close  the  valves  of  the  pump  pistons 
beyond  their  own  weight ; therefore,  they  fall  out  without  the  slightest  shock.  To  make  the  down 
stroke,  the  equilibrium  steam-valve  Q,  and  the  hydraulic  valve  0 are  opened  simultaneously : the  water 
from  beneath  the  plungers  escapes  to  the  stand-pipes  and  reservoirs  by  the  pipes  d"",  and  the  steam 
from  the  small  cylinder  passes  by  the  pipe  q,  round  to  the  upper  side  of  the  small  and  annular  pistons, 
puts  the  pressure  on  the  small  piston  in  equilibrium,  and  presses  upon  the  annular  piston,  (beneath 
which  a constant  vacuum  is  maintained,)  in  aid  of  the  dead  weight  now  resting  upon  the  inner  ends 
of  the  pump  balances : by  the  united  effort,  the  pump  pistons  are  elevated  and  the  water  dis- 
charged. Before  the  next  stroke  is  made,  the  eduction-valve  is  opened  and  a vacuum  formed  over  both 
pistons. 

So  well  does  the  hydraulic  apparatus  just  described  effect  the  object  for  which  it  was  designed,  that 
the  Haarlem-mer  Meer  Commissioners  have  decided  to  use  only  eight  pumps,  but  of  73  inches  diameter, 
for  the  other  engines  ; the  chief  reason  for  the  adoption  of  the  63-inch  pumps  for  the  Leeghwater  Engine 
having  been  the  fear  of  the  shocks  to  which  such  large  pump  pistons  are  ordinarily  liable. 

Boilers. — The  Leeghwater  Engine  is  furnished  with  five  cylindrical  boilers,  each  30  feet  long  and  6 
feet  diameter,  with  a central  fire-tube,  4 feet  diameter : a return  flue  passes  under  the  boilers  to  the 
front,  and  then  splits  along  the  sides.  Over  the  boilers  is  a steam  chamber,  4 feet  6 inches  in  diameter 
and  42  feet  in  length,  communicating  with  each  boiler;  from  thence  a steam-pipe,  of  2 feet  diameter, 
conducts  the  steam  to  the  engine.  The  steam  space  in  the  chamber,  boilers,  'and  pipe  is  nearly  1 320 
cubic  feet,  and  as  the  engine  draws  its  supplies  from  such  an  immense  reservoir  of  steam,  no  “ primage’’ 
takes  place,  and  a very  uniform  pressure  upon  the  piston  is  obtained  until  the  induction-valve  closes 
These  boilers  have  produced  steam  enough  to  work  the  engine  to  the  net  power  of  400  horses.  The 
Oruquius  and  Van  Lynden  Engines  will  have  boilers  capable  of  working  to  500  horses’  power  if  re- 
quired. 

The  drainage.— Prior  to  the  construction  of  the  engine-house,  &c.,  an  earthen  dam  of  a semicircular 
form  was  thrown  out  into  the  lake,  to  inclose  about  1^  acres;  after  the  water  was  pumped  out  from 


PUMP,  LEEGHWATER  STEAM. 


547 


within  the  dam,  a strong  piled  foundation  was  made,  and  the  masonry  commenced  at  the  depth  of  21 
feet  below  the  surface  of  the  lake : a small  steam-engine  was  erected  to  evacuate  the  water  from  the 
dam.  When  the  Leeghwater  was  completed,  the  commissioners  determined  to  test  its  merits  fully 
before  deciding  on  the  construction  of  the  other  engines  upon  the  same  model ; and  as  they  had  the 
means  of  evacuating  the  water  within  the  dam  to  any  level  required,  the  Leeghwater  could  be  tried 
and  worked  continuously  under  any  circumstances,  precisely  similar  to  those  which  will  occur  during 
the  drainage  of  the  lake,  if,  instead  of  discharging  the  water  from  the  pumps  into  the  upper  canal,  it 
was  allowed  to  fall  back  again  to  the  level  from  whence  it  was  derived. 

The  average  depth  of  the  lake  is  13  feet  below  the  general  level  of  the  surface  water  of  the  canal 
and  water-courses  conducting  to  the  sea-sluices ; when  the  communications  between  those  waters  and 
♦lie  lake  are  closed,  the  engine  will  at  first  have  only  the  head  of  water  caused  by  the  discharge  from 
the  pumps,  and  the  friction  of  the  machinery,  to  overcome ; in  this  state,  all  the  filling  plates  or  ballast 
of  the  great  cap  and  pistons  will  be  taken  out,  and  counter-balances  added  to  the  pump  balance-beams 
“ out  of  doors,”  so  as  to  take  up  as  much  of  the  dead  weight  attached  to  the  great  cap  as  may  not  be 
required  for  working  the  engine  : as  the  lift  becomes  greater,  the  dead  weight  “ in-doors”  will  be  gradu- 
ally added.  In  this  manner  the  engine  was  worked  for  a considerable  time,  to  get  all  the  parts  in  good 
working  order.  A sub-committee  of  the  commission  conducted  a series  of  experiments,  and  satisfied 
themselves  that  the  Leeghwater  will  perform  a duty  of  75  million  pounds,  lifted  one  foot  high,  by  the 
consumption  of  94  lbs.  of  good  Welsh  coal,  whilst  exerting  a net  effective  force  of  350  horses’  power. 
With  a lift  of  13  feet,  the  engine  easily  worked  the  eleven  pumps  simultaneously;  the  net  load  of 
water  lifted  being  81'7  tons,  and  the  discharge  63  tons,  t«er  stroke. 

When  the  bed  of  the  lake  is  cultivated,  the  surface  of  the  water  in  the  drains  will  be  kept  at  IS 
inches  below  the  general  level  of  the  bottom ; but  in  time  of  winter  floods,  the  waters  of  the  upper 
level  of  the  country  will  be  raised  above  their  ordinary  height : in  which  case,  to  keep  the  bed  of  the 
lake  drained  to  the  regulated  height,  the  lift  and  head  may  be  increased  to  17  feet.  To  test  the  power 
of  the  engine  under  these  circumstances,  (and  without  regard  to  the  consumption  of  fuel,)  the  whole  of 
the  11  pumps  were  worked  simultaneously,  and  the  extraordinary  quantity  of  109  tons  net  of  water 
was  raised  per  stroke  to  the  height  of  10  feet;  but,  in  practice,  it  will  be  advisable  to  work  a less  num- 
ber of  pumps,  and  increase  the  number  of  strokes  per  minute. 

After  numerous  and  severe  trials  of  the  engine,  the  commissioners  were  satisfied  that  it  is  capable  of 
performing  its  work  under  the  most  difficult  circumstances  that  can  arise ; and  immediately  determined 
on  having  two  more  engines  constructed,  of  equal  size,  and  on  the  same  model — the  only  material  alter- 
ation being  in  the  arrangement  of  the  pumps ; the  number  being  reduced  to  8 for  each  engine,  but  of 
73  inches  diameter,  placed  in  pairs  opposite  each  other,  and  the  ends  of  the  balance-beams  projecting 
over  the  great  cap  of  the  engine,  (instead  of  under  as  in  the  Leeghwater,)  to  which  they  will  be  con- 
nected by  stout  wrought-iron  straps.  The  boilers  also  will  be  increased  in  number,  and  in  power  nearly 
100  horses.  All  the  feed-water  will  be  filtered  before  passing  into  the  boilers. 

Advantages  of  two  cylinders. — Many  persons  imagine  that  the  engines  are  constructed  witli  two  cylin 
ders  to  obtain  a greater  expansion  of  the  steam  than  would  be  attainable  in  one  cylinder  ; but  such  is 
not  the  case,  as  no  greater  economy  of  steam  can  be  obtained  by  the  use  of  two  cylinders  than  by  one, 
although  greater  steadiness  of  motion  for  rotatory  engines,  and  less  strain  upon  the  pit-work  of  a mine- 
pumping engine,  may  result  from  the  use  of  two  cylinders.  In  the  Haarlem  engines  two  cylinders  are 
used,  because  if  one  cylinder  only  were  employed  it  would  sometimes  be  necessary  to  use  a dead  weight 
of  125  tons  to  overcome  the  resistance  of  the  water  load  and  friction  of  the  engine  and  pumps  ; such  a 
mass  of  iron  or  other  heavy  material  would  be  unmanageable,  and  no  alteration  in  the  force  of  the  en- 
gine could  be  effected  but  by  taking  from  or  adding  to  the  dead  weight,  which  would  be  a source  of 
great  difficulty  and  inconvenience,  when  the  varying  character  of  the  load,  during  the  drainage  of  the 
lake,  is  considered  ; particularly  as  at  times  the  water  will  be  charged  with  so  much  foreign  matter  as 
greatly  to  add  to  the  friction  of  the  pumps.  By  the  system  adopted  the  maximum  dead  weight  ele- 
vated by  the  small  piston  will  seldom  exceed  85  tons,  the  additional  power  required  being  derived 
from  the  pressure  of  the  return  steam,  at  the  down  stroke,  on  the  annular  piston ; by  varying  the  ex- 
pansion and  pressure  of  the  steam  in  the  small  cylinder,  the  engineman  can  add  to,  or  diminish  the 
pressure  upon  the  annular  piston,  so  as  to  meet  any  case  of  variable  resistance  without  the  inconveni- 
ence and  delay  attending  an  alteration  of  the  dead  weight ; the  load  is  therefore  under  perfect  com- 
mand at  all  times. 

Quantity  of  water. — The  area  of  the  Haarlem  Lake  is  45,230  acres,  the  estimated  contents  to  be 
pumped  out  about  800  million  tons ; but  should  the  quantity  be  increased  by  any  unforeseen  cause 
even  to  1000  million  tons,  the  whole  amount  could  be  evacuated  by  the  three  engines  in  about  400 
days. 

The  bed  of  the  lake  when  drained  must  be  always  kept  dry  by  machinery,  and  observations  continued 
during  91  years  show  that  the  greatest  quantity  of  rain  which  fell  upon  the  area  of  the  lake  in  that 
period  would  give  36  million  tons  as  the  maximum  quantity  of  water  to  be  elevated  by  the  engines  in 
one  month ; to  perform  this  work  would  require  a force  of  1084  horses’  power  to  be  exerted  during  that 
period ; the  average  annual  drainage  is  estimated  at  54  million  tons. 

The  cost  of  the  Leeghwater,  buildings  and  machinery,  was  £36,000  ; of  this  amount  about  £15,000  are 
due  to  the  buildings  and  certain  contingencies.  For  the  foundations  1400  piles  were  driven  to  the  depth 
of  40  feet  into  a bed  of  hard  sand,  and  a strong  platform  laid  thereon  at  the  depth  of  21  feet  below  the 
surface  of  the  lake ; upon  this  platform,  at  the  distance  of  22  feet  from  the  engine-house,  a strong  wall 
pierced  with  arches  was  constructed,  and  at  7 feet  from  the  coping  a stout  floor  of  oak  was  laid  between 
the  wall  and  the  engine-house ; the  pumps  rest  upon  the  platform  beneath  and  opposite  the  arches,  and 
their  heads  come  through  the  floor  alluded  to,  and  stand  about  3 feet  above  its  level : into  the  canal 
thus  formed  between  the  engine-house  and  the  outer  wall,  the  water  from  the  pumps  is  discharged  and 


548 


PUNCH,  REVOLVING  SPRING. 


flows  off  on  either  side  of  the  boiler-house,  through  sluice-gates,  into  the  canals  conducting  to  the  sea 
sluices. 

The  great  cost  of  the  buildings,  for  whatever  description  of  machinery  might  have  been  employed, 
rendered  it  an  object  of  considerable  importance  to  lessen  this  expense  by  concentrating  the  power  tc 
drain  the  lake  in  three  engines ; in  addition  to  which  a considerable  saving  in  the  wages  of  enginemen, 
stokers,  and  others  is  effected,  as  these  large  engines  require  very  little  more  attendance  than  an  ordi- 
nary mine  engine ; this  is  an  important  feature  in  the  economy  of  the  charge  for  the  permanent  drain- 
age of  the  “Polder,”  which  will  be  formed  by  the  bed  of  the  lake. 

The  average  consumption  of  the  ordinary  land-draining  engines  applied  to  scoop-wheels  and  Archi- 
median  screws,  may  be  taken  at  15  lbs.  of  coal  per  net  horse-power  per  hour;  this  quantity  will  be 
greatly  reduced  if  the  horses  power  of  the  engines  be  calculated  by  the  pressure  of  the  steam  on  the 
pistons,  and  not  by  the  net  delivery  of  the  water ; in  a case  where  the  water  delivered  by  a large 
steam-engine  working  a scoop  wheel,  was  measured  during  eight  hours,  the  engine  was  found  to  exert 
a net  force  of  73  horses’  power  during  the  first  hour,  with  a consumption  of  15  lbs.  of  coals  per  net  horse- 
power ; as  the  lift  increased  the  power  diminished,  and  the  consumption  of  fuel  increased,  until  at  the 
eighth  hour  it  was  found  that  the  engine  only  exerted  a net  force  of  33  horses’  power,  and  consumed  24 
lbs.  of  coal  per  net  horse-power  per  hour.  The  consumption  of  fuel  by  the  Leeghwater  is  2-J  lbs.  of  coals 
per  horse-power  per  hour  when  working  with  a net  effective  power  of  350  horses. 

No  new  principle  has  been  developed  in  the  Leeghwater,  but  important  facts  have  been  demonstrated 
which  must  have  an  immense  influence  on  the  progress  of  agricultural  hydraulic  engineering : it  has 
proved  that  witli  proper  attention  to  well-known  principles,  steam-engines  of  the  very  largest  class  (the 
Leeghwater  is  believed  to  be  the  largest  and  most  powerful  land  engine  ever  constructed)  may  be  em- 
ployed to  raise  great  bodies  of  water  from  low  lifts  for  the  drainage  or  irrigation  of  low  lands  with  as 
great  an  economy  of  fuel  as  was  hitherto  generally  supposed  to  be  confined  to  the  elevation  of  com- 
paratively small  quantities  of  water  to  great  heights.  To  the  Haarlem-mer  Meer  Commissioners  be- 
longs the  merit  of  having  ventured  to  carry  out  this  bold  experiment,  and  they  will  reap  their  reward 
by  an  economy  of  at  least  £100,000  over  the  cost  of  draining  the  lake  by  the  ordinary  system  of  steam- 
engines  and  hydraulic  machinery  employed  to  drain  land  ; and  of  upwards  of  £170.000  and  three 
years  time  over  the  cost  of  draining  the  lake  by  the  windmill  system  hitherto  generally  employed  in 
Holland. 

The  Leeghwater  is  named  in  honor  of  a celebrated  Dutch  engineer,  who,  from  his  great  success  in 
draining  numerous  lakes  in  North  Holland,  was  popularly  known  by  the  name  of  “ Leeghwater,”  or  “ the 
drier-up  of  water,”  and  with  him  the  first  proposal  to  drain  the  lake  originated  in  1623. 

The  engines  and  pumps  were  manufactured  at  the  establishment  of  Messrs.  Harvey  Co.,  of  Hayle, 
and  Messrs.  Fox  & Co.,  of  Perran,  Cornwall. 

PUNCH,  REVOLVING-  SPRING.  Invented  by  S.  Merrick,  of  Springfield,  Mass.,  and  patented 
February  28th,  1848. 

This  tool  is  designed  for  punching  leather  and  other  like  material,  and  contains  four  punches  of  vary 
ing  size,  either  of  which  can  be  instantly  brought  into  use. 

In  the  drawings,  Fig.  3162  denotes  a side  elevation. 

Fig.  3163  an  end  view  of  the  cylinder  E,  and  the  series  of  rotating  punches  FFFF,  showing  the 
right-angular  shoulders  b,  on  the  punches. 

In  said  Figures  A denotes  the  bed-lever  of  the  punches  ; B,  the  punch-lever,  or  that  which  supiports 
or  carries  the  series  of  rotating  punches  FFFF,  which  are  sustained  and  revolve  between  spring-jaws 
D D.  I is  the  bed  or  blank  of  copper,  in  conjunction  with  which  the  lower  punch  acts  during  the  opera- 

3162.  3103. 


tion  of  punching ; E is  the  cylinder  to  which  the  several  punches  are  fastened : right-angular  notches 
are  made  in  the  lower  side  of  the  spring-jaws  D,  which  notches  are  made  to  fit  the  projections  or 
right-angular  shoulders  b,  made  on  the  sides  of  the  punches;  their  object  is  to  prevent  the  lower 
punch  from  being  moved  forward  towards  the  extremity  of  the  lever  A during  the  operation  of 
punching.  Each  punch  of  the  series  is  fitted  with  like  shoulders.  The  notches  are  made  in  cam  pro- 
jections, formed  respectively  on  the  spring-jaws.  For  the  purpose  of  effectually  discharging  the  little 
circles  or  cylinders  of  material  separated  from  any  article  by  the  cutters,  and  which  pass  through  the 
cutters  and  into  the  interior  of  the  cvlinder  E,  a cone  is  arranged  with  respect  to  the  discharging 
mouths  of  the  punches,  so  that,  after  the  pieces  of  leather  have  passed  out  of  the  punches  they  are 
forced  against  the  cone,  and  by  it  directed  laterally  and  out  of  the  space.  Without  some  such  con 
trivance,  the  space  is  very  liable  so  become  filled  or  choked  by  the  pieces  which  are  cut  away  by  the 
punches. 

The  remaining  parts  of  the  punch  will  be  obvious  without  further  description. 


PUNCHING  MACHINE,  STEAM. 


549 


PUNCHING  MACHINE,  STEAM. — By  M.  Cave,  Paris.  Fig.  3164,  elevation.  Fig.  3165,  end 
view.  Fi°\  3166,  nlan.  Fig.  8167,  sectional  plan  of  punching-frame.  Fig.  3168,  section  of  cutter 
adapted  to  machine  for  cutting  plate.  Fig.  3169,  elevation  of  the  same.  Fig.  3170,  plan.  Fig.  3171, 
section  showing  the  mode  of  keying  the  punch. 


Literal  References. 


* team-cylinder. 

b,  piston  and  cross-head  h’. 

c,  slide-valVe,  opening  alternately  the  steam-port 
c'  and  exhaust- port  c",  worked  by  rod  d. 

d shde-rod. 

e,  steam-pipe. 

f,  punching-lever,  connected  to  the  piston  by  the 
links/'  and  cross-head  b'  working  in  frames /". 


g,  punching  cylinder,  connected  to  lever  f by  the 
links  g. 

h,  frame  for  carrying  punching  machinery. 

j,  lever  fixed  to  the  rod  d for  stopping  the  machine 
by  the  pins/;  it  is  worked  by  the  handle  j " 
and  counterbalance/”. 

k,  connecting-rod. 

l,  crank  and  shaft. 


550 


PUNCHING  AND  PLATE-CUTTING  MACHINE. 


m,  fly-wheel. 

n,  punch, 

o,  dies. 
x>,  stop. 


I q,  plate  being  punched. 

r,  foundations. 

s,  aperture  through  which  the  iron  plate  punched 
I out  falls. 


PUNCHING  AND  PLATE-CUTTING  MACHINE.  By  Messrs.  Nasmyth,  Gaskell  d'  Co.,  Man 
Chester . Fig.  3172,  front  elevation.  Fig.  3173,  side  elevation. 


3172. 


Literal  References. 


а,  tight  and  loose  riggers. 

б,  fly-wheel. 

c,  spur-wheel  and  pinion. 


d,  frame  for  carrying  machinery. 

e,  shaft  and  eccentric  for  raising  and  depressing 
slide. 


3173. 


ft  slide,  the  upper  end  having  a steel  cutter  g,  and 
the  lower  end  the  punches  h. 

g,  steel  cutters. 

h,  punches. 

i,  die-frame. 

/,  stop  for  preventing  the  plate  from  rising. 
k,  travelling  table  for  carrying  plate  to  be  punched. 


l,  rods,  levers,  and  spindle  for  advancing  the  trav 
elling  table  by  means  of  tappet  m,  on  spur-wheel 

m,  tappet  on  spur-wheel. 

n,  rack-bar  attached  to  brackets  o of  travelling 
table. 

o,  brackets  fixed  to  table. 

p,  carriage  for  supporting  spindle. 


PUNCHING  AND  SHEARING  MACHINE. 


551 


PUNCHING  AND  SHEARING  MACHINE.  By  Cairo  & Co.,  Greenock.  These  figures  repre 
sent  the  form  and  general  arrangement  of  a machine  of  great  importance  and  utility  in  the  manufacture 
of  steam-engine  boilers.  The  present  example  is  distinguished  for  its  mechanical  elegance  of  design, 
simplicity  of  construction,  compactness  and  strength.  Although  the  machine  occupies  only  a very  in- 
considerable space  on  the  floor  of  the  factory,  it  is  capable  of  punching  and  shearing  plates  of  one  inch 
in  thickness. 

Fig.  .3174:  is  a general  side  elevation  of  the  machine. 

Fig.  BUS  is  a front  elevation,  looking  upon  that  face  of  the  machine  which  is  adapted  to  the  opera- 
tion of  shearing. 

Fig.  3176  is  a corresponding  elevation  of  the  opposite  end  at  which  the  operation  of  punching  is  per- 
formed. 

Fig.  3177  shows  the  form  of  the  main-shaft  and  section  of  the  slides. 

General  description. — The  framing  consists  of  a single  massive  casting  A A,  having  strong  brackets 
B C and  D E formed  upon  it  at  opposite  sides.  In  the  pieces  B and  D recesses  are  formed  for  the  re- 
ception of  the  bushes  of  the  shaft  N,  and  of  the  slides  b b,  to  which  the  shearing  cutter  and  punch  are 
attached  respectively.  The  bushes  of  the  shaft  N are  adjusted  to  the  proper  degree  of  tightness  by  the 

3174. 


cotters  dd;  and  the  extremities  a a of  the  shaft,  close  to  these  bearings,  are  formed  eccentrically,  as 
shown  in  Fig.  3177.  These  eccentric  ends  are  inserted  into  the  slides  bb,  and  work  in  oblong  bushes  of 
such  a form  as  to  allow  the  eccentrics  to  move  freely  in  a lateral  direction,  while  the  full  amount  of 
their  vertical  motion  is  transferred  to  the  slides.  These  bushes  are  retained  in  their  places  by  thin 
wrought-iron  covers  c c. 

The  slides  move  vertically  between  the  parallel  dovetail  guides  e e,  fixed  by  screws  tapped  into  the 
projecting  pieces  B and  D,  which  are  carefully  dressed  to  allow  the  slides  to  move  freely  but  without 
play  upon  them.  On  the  shearing  slide  is  fixed  a steel  cutter/,  acting  in  contact  with  the  stationary 
cutter  inserted  into  the  table  C ; the  cutting  edges  form  an  acute  angle  with  each  other,  so  that  during 
the  process  of  shearing,  the  action  is  rendered  gradual.  The  opposite  slide  carries  the  punching-tool  r/, 
which  is  held  in  its  socket  by  a cotter  h ; the  small  hole  i,  immediately  over  it,  is  for  the  convenience 
of  driving  the  punch  out  of  the  socket  when  required.  The  die-holder  is  attached  to  the  table  E by  two 
screws  tapped  into  the  table,  and  thus  admits  of  being  changed  at  pleasure. 

The  shaft  N derives  its  motion  from  the  large  bevel  mortise-wheel  M M,  keyed  upon  it  between  th< 
cheeks  of  the  frame.  This^pheel  geers  with,  and  is  put  in  motion  by,  the  pinion  L,  or  the  low  _ r enu 
of  the  vertical  shaft  J,  which  is  carried  in  a step  supported  in  a bracket  cast  on  the  inside  of  one  of  the 


552 


RAG  AND  WASTE  PICKER. 


cheeks;  the  upper  end  revolves  in  an  independent  hearing  attached  to  any  convenient  beam.  The 
power  is  transmitted  to  this  shaft  from  the  driving-shaft  F,  by  means  of  the  two  bevel-wheels  Cf  and 
H.  On  the  upper  end  of  the  same  shaft  J is  keyed  the  fly-wheel  K,  for  equalizing  the  motion  of  the 
machine  under  the  irregular  strains  to  which  it  is  subject. 

Action  of  the  machine. — Motion  being  communicated  to  the  eccentric-shaft  N,  the  slides  will  be  made 
to  travel  vertically  through  spaces  corresponding  to  the  eccentricity  of  the  parts  a a,  thereby  working 
the  shears  and  punch  alternately ; the  eccentricity  of  the  two  extremities  being  formed  on  opposite 
sides  of  the  shaft,  so  that  while  the  punch  is  descending,  the  cutter  of  the  shears  will  be  ascending,  and 
vice  versa.  The  plates  under  operation  are  shifted  by  hand,  upon  tables  of  wood  erected  at  the  proper 
levels,  and  usually  witlf  guides  fixed  upon  them  for  insuring  accuracy  in  the  operation  of  cutting. 


Literal  References. 


L A,  the  frame  of  the  machine. 

B,  hollow  bracket  for  the  shearing-slide. 

C,  the  fixed  table  for  the  same. 

D,  hollow  bracket  for  the  punching-slide. 

E,  the  table  upon  which  the  hollow  die  is  set. 

h a,  eccentric  ends  of  the  shaft  N. 

L b,  the  shearing  and  punching  slides. 

c c,  covers  fixed  upon  the  slides  over  the  ends  of  the 
eccentrics  a a. 

dd,  cotters  for  adjusting  the  adjusting  bearings  of 
the  shaft  N. 

ce,  dovetail  guiding  pieces  between  which  the 
slides  move. 

f the  shearing-cutter. 

(7,  the  punching-tool. 


/i,  a cotter  for  fixing  the  punch  in  its  socket. 

i,  an  oblong  hole  over  the  socket  of  the  punch  lor 
driving  it  out  when  required. 

F,  the  shaft  by  which  the  power  is  led  to  the  ma- 
chine. 

G,  a bevel-wheel  on  the  horizontal  driving-shaft, 
geering  with 

H,  a bevel-wheel  on  the  vertical  driving-shaft  J. 

K,  the  fly-wheel  for  regulating  the  motion  of  the 
machine. 

L,  a bevel-pinion  on  the  vertical  shaft  J,  geering 
with 

M,  a large  bevel  mortise-wheel  fixed  on 

FT,  the  main  eccentric-shaft. 


PYROMETER.  An  instrument  for  measuring  the  degrees  of  heat.  The  term  pyrometer  is  generally 
understood  to  denote  either  an  instrument  intended  to  measure  higher  temperatures  than  can  be 
measured  by  the  ordinary  thermometer,  or  an  instrument  for  comparing  the  expansions  of  different 
metals. 

Various  contrivances  have  been  employed  for  the  above  purposes.  Musschenbroek,  the  original 
inventor  of  the  pyrometer,  adopted  the  following  method  : A prismatic  rod  (about  six  inches  long)  of 

the  metal  under  trial  being  attached  at  one  extremity  to  an  immovable  obstacle,  and  heated  by  lamps, 
the  other  end  is  necessarily  pushed  forward ; and  this  being  fastened  to  the  end  of  a rack  playing  into 
a pinion,  communicates  a revolving  motion  to  an  axle  to  which  a train  of  wheel-work  is  attached, 
vdiereby  the  minutest  expansion  of  the  heated  bar  is  rendered  sensible,  and  measured  by  an  index  on  a 
dial.  The  principle  of  this  apparatus  is  sufficiently  simple;  but  the  uncertainty  attending  the  motion 
of  so  many  loosely  connected  wheels  and  pinions  must  have  rendered  its  indications  of  little  value  ; and 
the  method  is  liable  to  a still  more  serious  objection,  namely,  that  the  temperature  communicated  to 
the  bar  by  the  lamps  is  entirely  unknown.  Desaguliers,  and  afterwards  Ellicott,  made  several  improve- 
ments in  the  construction  of  the  instrument,  tending  to  give  it  a more  equable  motion  and  to  increase  its 
delicacy.  Graham  substituted  a micrometer  screw  for  the  wheels  and  levers  that  had  formerly  been 
employed ; and  on  this  principle  Mr.  Smeaton  contrived  an  ingenious  apparatus,  which  is  described  in 
the  Phil.  Trans.,  vol.  xlviii. 


RAG  AND  WASTE  PICKER — By  C.  G.  Sargent.  It  has  always  been  a desideratum,  and  hith- 
erto unaccomplished  in  any  practical  degree,  for  the  manufacturer  to  be  able  to  reduce  waste  yarn  and 
poor  or  worn  fabrics  to  their  original  condition  of  fibre,  and  capable  of  being  again  worked  into  cloth. 
The  above  machine  accomplishes  this  object,  being  capable  of  reducing  150  pounds  of  waste  woollen 
yarns,  so  that  they  may  be  easily  carded  and  spun  anew.  It  was  invented  after  trials  of  several  modes, 
and  after  much  consideration,  by  Mr.  Charles  G.  Sargent,  of  Lowell,  and  he  is  now  constructing  them 
for  most  of  the  woollen-mills  in  that  section  of  the  country.  The  cost  of  one  whose  cylinders  are  12 
inches  long,  with  full  rights  to  use  it,  is  about  §300. 

The  machine  and  its  action  may  be  described  by  reference  to  Fig.  3178,  which  represents  a longitu- 
dinal section  of  it.  The  frame  being  represented  at  A A A,  <fcc.,  the  casings  at  B B B,  <Src.,  D being  a 
shaft  put  in  motion  by  some  force,  and  from  which  motion  is  communicated  to  all  moving  parts.  The 
yarn,  cloth,  or  other  material  required  to  be  picked,  is  spread  upon  a feeding  apron  E,  which  has  a slow 
motion  towards  the  roll  F,  which  has  a motion  indicated  by  the  arrows,  and  being  fluted  or  toothed 
draws  in  the  material  between  itself  and  the  iron  shell  G,  and  passes  it  forward  to  the  roll  F',  which  is 
similar  to  F,  and  has  a quicker  angular  motion  than  it,  thereby  insuring  that  it  may  take  all  that  is 
presented  by  the  roll  F,  and  at  the  same  time  tending  to  draw  the  threads  or  fibres  to  a position  at 
right  angles  to  its  axis,  the  rolls  F and  F'  being  so  supported  that  they  can  rise  and  fall  from  and  to- 
wards the  shell  G,  according  as  there  may  be  large  or  small  pieces  between  them  and  the  shell. 

The  material  is  thrust  out  from  between  the  roil  F'  and  the  shell  G,  towards  the  first  picking  cylinder 
H.  This  cylinder  is  formed  by  adding  to  a plain  cylindrical  pulley  strips  of  metal,  about  1 inch  by  | 
inch,  and  of  the  same  length  as  the  face  of  the  pulley.  Parallel  to  its  axis  and  upon  the  outer  surfaces 
of  these  strips,  are  secured  plates  somewhat  wider  than  the  strips,  having  fine  teeth  cut  upon  one  of 
their  edges,  and  set  in  such  a manner  that  the  points  of  the  teeth  will  fc*;  somewhat  further  from  the 
centre  of  the  pulley  than  the  other  edge,  and  also  projecting  forward  in  the  direction  of  die  motion  ol 


RAILROADS. 


553 


the  pulley,  and  overlapping  the  strips  to  which  they  are  attached.  This  cylinder  being  so  placed  that 
the  teeth  of  the  serrated  plates  will,  when  the  cylinder  is  in  motion,  barely  clear  the  shell  G,  when  the 
material  is  projected  from  between  the  roll  F'  and  the  shell  G the  part  so  projected  will  be  combed  ana 
torn  to  shreds,  while  the  twist  of  the  yarn  will  be  taken  out  by  the  rapid  action  of  the  senated  plates, 
while  large  and  long  pieces  will  be  prevented  from  being  passed  through  by  being  held  between  the 
rolls  and  the  shells.  The  material  is  taken  from  the  cylinder  H by  the  brush  I,  which  revolves  more 
rapidly,  and  at  the  same  time  is  assisted  by  the  fan  R,  which  also  keeps  the  brush  clean.  By  the  cur- 
rent of  air  produced  by  the  fan  and  brush  the  material,  now  partially  picked,  is  blown  upon  the  second 
feeding  apron  J,  which  has  a slow  movement  indicated  by  the  arrows,  and  is  prevented  from  leaving 
this  apron  by  the  cylinder  K,  which  revolves  slowly,  being  carried  by  the  aprorf  This  cylinder  is  made 
by  covering  a slight  frame  with  wire  cloth,  thus  allowing  the  air  to  pass  through  it  and  retain  the  ma- 
terial upon  the  apron,  forming  a lap. 


3178. 


The  material  now  passes  under  the  small  roll  L,  which  is  a plain  cylinder,  and  for  the  purpose  j 
eading  it  to  the  second  pair  of  feeding-rolls  M M',  the  cylinder  0,  the  brush  P,  and  fan  R,  each  ol 
which  acts  respectively  the  same  as  the  rolls  F F',  the  cylinder  II,  brush  I,  and  fan  R,  except  that  the 
teeth  of  the  cylinder  O are  finer  than  those  of  H,  and  that  the  material  is  now  blown  out  of  the  machine 
picked,  and  again  ready  for  the  card. 

RAILROADS.  The  limits  and  scope  of  this  work  forbid  enlarging  upon  the  history  of  railroads,  or 
tracing  their  development  from  the  rude  tram-ways  of  the  German  mines,  to  their  present  highly  ad- 
vanced state  of  perfection.  A great  deal  has  been  written  on  this  branch  of  the  subject,  easy  of  access, 
and  the  reader  is  referred  to  Wood,  Breese,  Dempsey,  and  others  on  railroads.  We  have  to  do  in  this 
place  with  railroads  in  the  light  of  machines,  and  as  such  describe  them  as  they  are ; the  principles 
upon  which  they  are  projected  and  located,  constructed  and  worked. 

Railroads  are  roads  upon  which  the  carriages  travel  on  iron  rails,  to  which  they  are  confined  by  pro- 
jections on  their  wheels,  called  flanges. 

The  principles  which  govern  in  the  location  of  a railroad  are  the  same  as  those  of  a common  road ; 
the  motor  in  general  use  on  the  former,  however,  renders  necessary  a more  rigorous  observance  of  these 
principles. 

The  resistance  to  motion  on  roads  is  occasioned : 1st.  By  the  want  of  uniformity  in  the  surface  of  the 
road ; the  weight  of  the  load  having  to  be  lifted  over  the  projecting  points  and  out  of  the  hollows  or 
ruts,  thus  diminishing  the  effective  load  which  the  power  may  draw  to  such  as  it  can  lift. 

2d.  The  want  of  strength  of  the  road-bed  itself  let  its  surface  be  as  even  or  uniform  as  it  may,  adds 
another  impediment  to  the  movement  of  a load  over  it,  with  the  additional  disadvantage  that  while  the 
power  is  endeavoring  to  lift  the  load  from  a cavity  or  hollow,  the  fulcrum,  which  in  the  first  case  w’as 
supposed  to  be  rigid  and  fixed,  is  in  the  latter  yielding  and  variable,  subjecting  the  power  to  the  con- 
stant effort  of  lifting  instead  of  simply  drawing.  To  these  causes  of  resistance  are  to  be  added, 

3d.  The  grade  of  the  road,  or  the  quantity  by  which  it  differs  from  a level.  This  resistance  is  due  to 
the  force  of  gravity,  and  unlike  the  others  may  be  determined  from  the  well-known  laws  of  mechanics, 
whilst  the  former  are  determinable  entirely  by  experiment  on  the  road  in  question  or  a similar  one. 

Friction  of  the  axles  and  resistance  of  the  air. — This,  it  is  true,  is  a fourth  cause  of  resistance  to  mo- 
tion on  roads,  but  its  consideration  may  be  neglected  for  the  present,  as  its  effects  are  constant,  and  in 
dependent  of  the  imperfections  of  the  road. 

The  first  cause  of  resistance  above  enumerated,  want  of  uniformity  or  evenness  of  the  road  surface,  is 
attempted  to  be  overcome  in  the  railroad  by  substituting  for  the  uneven  gravel  or  pavement  a hard  and 
smooth  iron  surface,  or  the  rail.  The  second  cause  of  resistance  is  diminished  by  a system  of  construe 
tions  whose  aim  is  to  afford  the  iron  rail  a permanent  and  unyielding  support. 

The  whole  art  of  railroad  building , then,  consists  in  producing  for  the  carriage  to  roll  on,  a hard,  smooth 
surface,  upon  an  unyielding  foundation  or  road-bed — in  appearance  a very  simple  matter— in  reality  a 
’ ery  difficult  one. 

To  exhibit  at  a glance  the  value  of  a smooth  surface — From  experiments  made  upon  the  best  turn- 


554 


RAILROADS. 


pike  road  in  England,  and  probably  in  the  world,  the  following  was  found  to  be  the  force  of  traction,  or 
the  weight  in  pounds  which,  hanging  over  a pulley,  would  draw  one  ton  on  a level  part  of  the  road — 
the  road-bed  as  firm  as  most  railways : 

On  a well-made  smooth  pavement 33  lbs. 

On  a broken  stone  surface  (macadamized)  over  an  old  flint  road  65  “ 

On  a gravel  road  147  “ 

On  a macadamized  road,  on  a rough  permanent  foundation  46  “ 

On  a macadamized  surface,  on  a foundation  of  cement  and  gravel 46  “ 

Average,  67  lbs. 

On  a good  edge  railroad,  the  force  of  traction  on  a level  is  usually  taken 
for  one  ton  at 8 “ 

or  a horse  will  draw  from  five  to  eighteen  times  as  much  on  a good  railroad  as  upon  the  best  turn- 
pike roads  in  use,  and  this  is  due  to  the  smoothness  of  the  surface  alone. 

This  illustrates  the  extent  of  the  first  cause  of  resistance  to  motion  on  roads. 

For  the  second,  it  may  be  sufficient  to  mention  a circumstance  within  the  writer’s  experience.  A lo- 
comotive engine,  built  at  Lowell,  drew,  on  trial,  on  the  Lowell  and  Boston  Railroad,  up  a grade  rising 
30  feet  per  mile,  the  same  load  which  it  barely  drew  on  a level  part  of  the  inferior  railroad  upon  which 
it  was  subsequently  worked.  The  surfaces  in  the  two  cases  were  the  same,  wrought-iron  ; but  the  one 
road-bed  and  rail  was  firm,  and  the  other  yielding. 

The  engine  which  could  draw,  say  300  tons  gross,  on  a grade  rising  30  feet  per  mile,  the  rail  per- 
fectly firm,  would,  in  the  same  condition  of  rail,  draw  475  tons  on  a level.  This  illustrates  the  value  of 
a firm  and  unyielding  road  surface. 

Location. — In  the  location  of  a railroad,  the  termini  are  in  most  cases  fixed,  and  the  engineer,  having 
in  consideration  the  nature  and  amount  of  the  traffic  anticipated  on  the  road,  must  so  adjust  its  align- 
ment, both  vertical  and  horizontal,  as  with  the  least  expenditure  in  first  cost  and  in  subsequent  working, 
to  produce  the  greatest  effect — in  this  case,  the  greatest  return  on  the  capital  invested  in  the  building 
maintenance,  and  working  of  the  road. 

The  perfection  of  a railroad  would  seem  to  be  a straight  line  and  a level,  and  yet  there  may  be  con- 
trolling circumstances  which  would  render  a level  road  not  desirable ; such  as  a very  heavy  trade  of 
coal,  lumber,  ores,  &c.,  in  one  direction : in  fact,  the  trade  may  be  such  as  to  render  the  weight  of  the 
empty  return  wagons  alone  the  data  for  limiting  the  steepness  of  the  grade  ; and  again,  when  the  trade 
is  well  balanced,  it  would  be  desirable  to  have  the  acclivities  and  declivities  balanced,  and  the  profile 
to  be  an  undulating  grade,  providing  a level  road  could  not  be  found.  In  general,  however,  let  wdiat 
$ill  be  the  best  grade  in  view  of  the  weight  of  traffic  or  other  circumstances,  it  is  rarely  that  these  con- 
ditions can  be  rigorously  obtained,  save  at  a cost  which  will  defeat  its  own  object;  for  it  is  undeniable 
that  a good  road  may  cost  too  much.  For  instance,  a heavy  trade  in  one  direction  with  no  return  of 
freight  would  seem  to  call  for  a uniform  descending  grade,  or  a grade  undulating  between  level  and 
descending;  and  yet  to  obtain  these  advantages  ridges  may  require  tunnelling,  and  expensive  works 
encountered,  to  pay  the  cost  of  which  would  require  tolls  on  the  traffic  for  which  the  road  was  built, 
tending  to  throw  the  article  out  of  the  market  in  competition  with  other  sources  of  supply.  Between 
these  limits  of  maximum  acclivity  and  level  the  engineer  is  to  make  his  selection,  keeping  always  in 
view  the  conditions  which  he  is  aiming  to  fulfil,  avoiding  a hill  here,  cutting  through  a ridge  there,  again 
tunnelling  in  preference  to  adding  to  the  length  of  line  or  to  the  curvature,  or  the  reverse,  increasing  the 
length  of  the  road  very  materially  in  some  cases  in  order  to  avoid  encountering  heavy  expenditures,  &.C. 
After  he  has  made  a careful  reconnoissauce  of  the  country  between  the  termini,  and  an  instrumental 
examination  of  such  lines  of  route  as  appear  to  his  judgment  the  best  calculated  to  fulfil  the  conditions 
sought,  it  wffil  usually  be  found  that  one  of  two  things  exist : either  the  true  route  is  indicated  beyond 
all  doubt  by  the  features  of  the  country,  in  which  case  it  remains  but  to  improve  the  line  within  nar- 
rower limits,  or  else  several  lines  offer,  either  of  which  may,  to  the  unassisted  judgment,  appear  to  fulfil 
all  the  required  conditions.  In  the  latter  case,  after  improving  each  line  in  detail  in  reference  to  bal- 
ancing the  material  to  be  used,  that  is  to  say,  where  possible,  making  the  cuttings  furnish  the  material 
for  the  filling ; reducing  the  amount  of  curvature  as  much  as  possible ; selecting  the  proper  crossings  of 
rivers,  swamps,  ridges,  Ac. ; examining  foundations  of  all  kinds  ; ascertaining  the  fitness  of  the  material 
to  form  banks ; examining  quarries,  timber,  price  of  labor  and  materials,  and,  in  general,  ascertain- 
ing the  capabilities  of  the  country  on  each  route  : the  several  routes  are  then  compared  in  view  of  their 
first  cost,  maintenance,  and  working,  and  not  unlikely  a new  element  will  appear  of  the  varying  amounts 
of  the  local  or  way  business  to  be  anticipated  and  provided  for. 

A treatise  on  railroad  engineering  would  of  itself  require  more  space  than  can  be  allotted  to  the  whole 
subject  of  railroads  in  a dictionary.  This  will  account  for  the  suppression  of  much  of  the  detail  which 
would  be  sought  for  in  a complete  treatise  on  railroad  building.  We  must  omit,  therefore,  the  consid- 
eration of  the  preliminary  operations  of  surveying  and  levelling,  as  well  as  the  form  and  character  of  the 
respective  works  which  make  up  the  construction  of  a railroad  ; such  as  bridges,  culverts,  tunnels,  founda- 
tions, Ac.,  and  which,  in  their  principles  of  construction,  are  common  to  many  branches  of  internal  im- 
provement.* 

In  preparing  the  estimates  of  the  several  lines,  plans  in  detail  are  made  of  all  the  mechanical  struc- 
tures from  which  their  cost  is  deduced  : profiles  are  made  exhibiting  the  grades  of  the  road  together  with 


* These  are  subjects  of  but  little  interest  to  the  general  reader,  and  the  student  in  the  science  of  engineering  should  look 
Slsewliere  than  in  a dictionary,  however  comprehensive,  for  the  principles  of  his  profession. 

Ir.  the  first  volume  of  this  Dictionary  reference  is  frequently  made  to  “railway  engineering;”  but  the  subject  is,  we 
conceive,  foreign  to  the  character  of  this  work,  which  is  a dictionary  of  “ machines,”  showing  the  principles  of  their  construc- 
tion and  working,  or  the  “engineering  of  machinery”  simply. — [Ed.  2d.  VoL.j 


RAILROADS. 


the  cuts  and  fills,  and  tables  exhibiting  the  cubical  contents  of  the  various  sections  of  the  work,  as  also 
the  horizontal  alignment,  showing  the  relative  amounts  of  straight  line  and  curves,  and  the  character 
of  the  latter.  The  cost  of  construction  having  thus  been  obtained  of  the  various  lines,  they  are  equated 
for  their  respective  amounts  of  ascents,  descent,  and  curvature,  the  ruling  grade,  or  the  grade  which 
limits  the  effective  power  of  the  engines  to  be  used,  determined,  and  the  lines  of  routes  brought  under 
one  general  view  for  comparison. 

Equating  for  grades. — The  result  of  experiments  carefully  conducted  gives  as  the  resistance  to  motion 
of  one  ton,  moving  on  a well-built  level  railroad,  about  8-J-  pounds,  or  the  weight  which  hanging  freely 
over  a pulley  will  overcome  the  friction  of  one  ton.  This  resistance  to  motion  is  a constant  fraction  of 
the  weight  moved,  and  is  its  ^-Tth  part.  This  is  the  friction  of  the  load.  If  now  the  plane  be  elevated 
from  a level  to  a rise  of  -^J-j-th  its  length,  according  to  well-known  mechanical  laws  1 pound  will  on  this 
plane  sustain  264  pounds,  (See  Inclined  Plane  and  Mechanical  Powers,)  or  84  pounds  will  sustain 
one  ton ; and  the  fraction  representing  a rise  of  20  feet  in  a mile ; it  follows  that  on  this  grade  the 
effect  of  gravity  is  equal  to  that  of  friction,  and  in  order  to  produce  motion  up  this  grade,  twice  the 
power  must  be  applied  that  would  be  required  were  it  on  a level ; and  as  it  is  a well-known  mechani- 
cal law  that  the  same  amount  of  power  is  expended  in  raising  a weight  through  a given  height,  what- 
ever may  be  the  angle  of  the  plane  upon  which  the  motion  is  effected,  it  follows  that  for  every  20  feet 
in  height  that  we  ascend  on  a railroad,  we  expend  an  amount  of  power  equivalent  to  the  transport  of 
that  weight  over  one  mile  of  level ; and  this  holds  true  whatever  the  grade  may  be.  Equating  for 
grades  with  a view  to  a comparison  of  lines,  then,  consists  in  adding  to  the  measured  distance  one  mile  for 
each  and  every  twenty  feet  of  ascent  on  the  respective  routes. 

Equating  for  curves. — Direct  motions  on  levels  or  inclines  are  affected  less  by  disturbing  causes  than 
motion  in  curves ; for  in  addition  to  the  irregularities  growing  out  of  the  imperfections  of  the  curved 
track  and  the  varying  elements  of  the  curved  motion  in  practice,  is  to  be  added  all  the  disturbing  causes 
which  exist  in  the  first  case.  This  has,  as  yet,  prevented  that  rigorous  solution  of  the  latter  problem, 
which  is  to  be  desired,  and  which  is  essential  to  a true  comparison,  a priori , of  the  cost  of  movement  on 
curved  roads.  It  is  as  yet  entirely  an  empirical  formula  deduced  from  a few  experiments,  but  has  been 
used  for  the  purpose  of  comparison  of  routes  by  distinguished  engineers,  and  is  the  best  we  can  offer 
with  our  present  knowledge  of  the  subject 

We  find  by  the  experiments  referred  to  above,  that  a curve  of  400  feet  radius  doubles  the  resistance. 
In  propelling  a train,  then,  through  an  entire  circumference  of  such  a curve,  we  expend  twice  the  power 
that  would  be  consumed  in  travelling  an  equal  distance  in  a right  line. 

Taking,  then,  the  analogy  afforded  by  motion  on  ascents  as  compared  with  levels  as  a guide,  and  we 
conclude  that  the  same  power  would  be  expended  in  turning  through  an  entire  circle,  whatever  may  be 
its  radius,  (this,  of  course,  must  be  understood  as  confined  to  certain  limits ;).  hence,  for  every  circle  of 
860  degrees,  we  must  add  for  the  expenditure  of  power  on  a right  line  of  the  same  length,  the  circum- 
ference of  a circle  described  with  the  radius  of  double  resistance,  found  by  experiment  as  above  to  be 
400  feet ; this  will  be  half  a mile.  Equating  for  curves  consists,  then,  in  adding  to  the  measured  distance 
one  half  mile  for  each  and  every  three  hundred  and  sixty  degrees  of  curvature  on  the  respective  routes. 

Having  explained  the  principles  which  govern  in  reducing  the  several  routes  under  comparison  to  a 
aniform  standard  in  respect  to  their  distance,  curvature,  and  grades,  we  will  introduce  an  example  from 
actual  practice  illustrative  of  the  every-day  operations  of  comparing  routes  preliminary  to  a selection  of 
one  for  construction. 

The  road  in  question  was-  to  connect  two  points  some  ninety  miles  apart,  for  which  seven  routes  were 
examined,  nowhere  distant  from  each  other  more  than  seven  miles,  and  the  nature  of  the  country  and 
the  anticipated  traffic  such  as  to  reduce  the  question  of  a choice  of  routes  to  that  of  economy  of  con- 
struction, maintenance,  and  working — independently  of  any  local  advantages  which  one  route  might 
possess. 

The  cost  of  repairs  per  mile  per  year  of  roads  as  nearly  similarly  circumstanced  as  possible,  and  with 
a given  traffic,  having  been  obtained  from  their  official  returns,  as  also  the  cost  of  working,  the  former 
amounting  to  $600  per  mile,  was  multiplied  by  the  measured  distances  of  the  lines,  and  the  latter, 
amounting  to  $150  per  mile,  was  multiplied  by  the  distances  resulting  from  equating  the  lines  for  curva- 
ture and  grades  as  above  described. 

A capital  which  at  6 per  cent,  will  furnish  the  first  amount  is  shown  in  the  sixth  column  of  the  table 
below;  the  capital  to  furnish  the  second  is  shown  in  the  seventh  column. 


Table  exhibiting  the  measured  and  equated  Distances  on  the  Various  Lines  surveyed  for  Railroad , with 
the  estimated  Cost  of  each,  including  Graduation,  Masonry,  Wooden  Bridging,  and  Railway,  with  the 
Capital  requisite  at  6 per  cent,  to  f urnish  an  annual  sum  adequate  to  maintain  and  work  each  line. 


Description  of  Lines. 

No. 

Measured 
distances  in 
miles  and 
decimals. 

Equated 
distances  in 
miles  and 
decimals. 

Estimated 
cost  of  con- 
struction. 

Equivalent 
capital  to  main- 
tain. 

Equivalent 
capital  to  work. 

Grand  totals. 

Upper  line 

1 

92-63 

160-13 

$1,127,471 

$926,375,00 

$2,001,636,25 

$4,055,482,56 

Lower  line  

o 

91-06 

157-22 

1,067,816 

910,632,00 

1,965,256,25 

3,943,705,17 

I/>wer  line  B 

3 

89-64 

157'40 

1,076,042 

896,416,00 

1,967,527,50 

3,939,985,66 

Lower  line  C 

4 

90-07 

156-60 

1,087,689 

900,766,00 

1,957,543,75 

3,945,999,02 

Lower  line  D 

5 

90-24 

155-97 

1,073,518 

902,478,00 

1,949,741,25 

3,925,737,52 

| Lower  line  E 

6 

91'65 

159"55 

1,124,509 

916,596,00 

1,994,416,25 

4,035,522,00 

Upper  line  B 

7 

93-51 

160-79 

1,129,097 

935,116,00 

2,009,911,25 

4,074,124,74 

556 


RAILROADS. 


Judging  the  lines  by  these  tests,  we  find  that  No  1,  or  the  upper  line , stands  Gth  in  order  of  direct 
ness,  Gth  in  point  of  value  derive  1 from  present  actual  outlay,  Gth  in  order  of  working,  and  of  course  Gth 
in  the  aggregate  of  them  all. 


No  2.  or  the  lower  line,  is 


No.  3 stands 


No.  4 stands 


No.  5 stands 


No.  G stands 


f 2d 
J 4th 
1 2d 
[4th 

f 2d 
J 2d 

| 1st 
[1st 

f 5th 

J Oth 

1 5th 
[5th 


No.  7 


In  order  of  directness. 

In  value  derived  per  actual  present  outlay. 
In  order  of  working. 

In  the  aggregate  of  all  these  considerations. 

In  order  of  directness. 

In  value  derived  per  actual  present  outlay. 
In  order  of  working,  and 
In  aggregate  of  all  these. 

In  order  of  directness. 

In  actual  present  outlay. 

In  order  of  working. 

In  aggregate  of  all  these. 

In  order  of  directness. 

In  actual  present  outlay. 

In  cost  of  working,  and 
In  aggregate  of  them  all. 

In  order  of  directness. 

In  order  of  actual  present  outlay. 

In  cost  of  working. 

In  aggregate  of  alL 

Is  the  inferior  one  in  every  respect,  standing 
last  in  all  the  comparisons. 


Simplifying  the  matter  as  far  as  possible,  we  have  four  routes,  No.  2,  3,  4 and  5,  differing  from  each 
ether,  in  the  extremes  of  the  first  respect,  rather  less  than  two  per  cent.,  and  in  the  latter  about  per 
cent. 

There  seems  no  substantial  reason  at  this  stage  of  the  case,  founded  upon  such  minute  differences,  for 
preferring  one  hue  over  another,  and  we  must  therefore  consider  what  improvements  each  is  susceptible 
cf,  when  it  comes  to  be  definitely  staked  off  for  construction. 

It  is  very  rare,  however,  that  so  small  differences  appear  in  the  comparison  of  several  routes,  but  it 
is  introduced  here  as  an  example  in  actual  practice,  and  showing  a very  proper  method  of  comparison. 

The  route  having  been  determined  on,  we  proceed  to  the  construction. 

Excavation  and  embankment. — Let  ABC,  Tig.  3179,  represent  a profile  or  longitudinal  section  of  a 
portion  of  the  line  over  which  the  railroad  is  to  pass,  and  abed  the  level  at  which  the  road  is  to  be  formed, 


3179. 


constituting  what  is  called  the  grade  line.  All  those  parts  of  the  section  above  the  line  abed  will  re- 
quire to  be  cut  down,  and  are  called  cuttings  ; and  those  portions  below  this  line  will  require  to  be  filled 
up,  and  are  designated  as  embankment,  or  fillings. 

Where  a trifling  variation  in  the  general  inclination  of  the  line  or  of  the  grades  is  not  of  great  im- 
portance, it  is  very  advisable  that  the  line  should  be  so  laid  out  that  the  quantity  of  earth,  or  material 
required  for  making  the  embankments,  should  not  be  greater  than  what  is  to  be  obtained  from  the  ex- 
cavations. There  is,  however,  an  exception  to  this  in  cuttings  or  embankments  of  great  lengths.  Cases 
may  occur  where  the  distance  between  the  cutting  and  embankment  is  such,  that  the  expense  of  con- 


3180. 


veying  the  earth  from  one  part  of  the  line  to  another  is  greater  than  the  increased  expense  of  borrowing 
material  alongside  the  line  of  railway,  or  near  the  embankment,  for  the  purpose  of  forming  the  embank- 
ment ; and  of  depositing  the  earth  from  the  cut,  which  ought  to  have  formed  the  embankment,  upon 
waste  ground  alongside  such  cut,  in  spoil  bank.  These  are,  however,  cases  to  be  judged  of  by  the  en- 
gineer of  the  work,  and  are  entirely  questions  of  comparative  expense  between  the  one  mode  and  the 
other. 


RAILROADS. 


557 


Width  of  the  railway. — Fig.  3180  is  a cross  section  of  an  excavation  or  cutting,  and  Fig.  3181  a cross 
bection  of  an  embankment ; ab  being  the  original  surface  of  the  ground,  and  gh  the  bottom  level  or  ex 
treme  depth  of  the  excavation.  The  first  question  to  determine  is  the  width  at  the  bottom  level,  as  by 
this  the  whole  of  the  operations  are  guided  ; and  this  depends  upon  two  considerations  : first,  the  width 
between  the  rails ; and  next,  the  width  between  the  two  lines,  if  the  railway  is  intended  to  be  a double 
line. 


3181. 


N—  . . 

7. 

\ 

■ A 

s 

A 

. A 

f. 

+ 

\ 

1 

5 

i 

6 

i 

ft 

A 

Width  between  the  rails. — The  first  public  railway,  of  any  extent,  which  was  executed,  was  the  Stock- 
ton  and  Darlington  Railway.  The  width  between  the  rails  of  that  railway  was  made  four  feet  eight  inch- 
es and  a half,  taking  the  Ivillingworth  Colliery  Railway  as  a standard.  The  Liverpool  and  Manchester 
Railway,  constructed  by  the  same  engineer,  was  formed  of  the  same  width  ; and  it  was  then  made  a 
standing  order  of  the  legislature  in  England  that,  in  all  public  lines  of  railway,  the  width,  between  the 
lTiils,  should  be  four  feet  eight  inches  and  a half.  In  1836  this  standing  order  was  suspended,  and  there 
is  now,  or  was  until  lately',  no  standard  of  width  whatever. 

The  following  are  the  principal  gages  in  use,  ranging  from  4 feet  6 inches  to  7 feet : "Mo.  1. — 1 
feet  6 inches,  originally  laid  down  in  Scotland.  No.  2. — 4 feet  84  inches,  the  gage  in  most  general  use. 
No.  3. — of  5 feet,  formerly  adopted  for  the 
Eastern  Counties  and  Blackwall  lines,  in  Eng- 
land. No.  4. — of  5 feet  6 inches,  used  in  Scot- 
land. No.  5. — The  New  York  and  Erie  Rail- 
road of  6 feet.  No.  6. — The  Irish  gage  of  6 
feet  2 inches ; and  No.  7,  the  Great  "Western  of 
7 feet  gage,  in  England. 

The  confusion  actually  resulting,  and  to  be  an- 
ticipated by  this  want  of  uniformity  in  the  con 

etruction  of  the  “ arterial  circulation,”  so  to  speak,  of  Great  Britain,  led  to  the  appointment  by  government 
of  a commission  to  inquire  into  and  report  upon  the  most  advantageous  width  to  be  adopted  in  the  future 
construction  of  railroads  in  that  country.  The  subject  was  examined  with  all  the  minuteness  which  its 
importance  called  for;  every  evidence  was  received  from  the  friends  of  the  several  widths  which  it  was 
in  their  power  to  furnish,  and  the  result  was  a report  from  the  commission  in  favor  of  the  “ narrow 
gage,”  or  four  feet  eight  and  a half  inches  between  the  rails  as  affording  all  the  advantages  claimed  for 
the  “broad  gage,”  and  at  a diminished  expense.  It.  is  now  the  standard  gage  in  that  country,  but  in 
our  own  the  matter  is  still  left  to  the  caprice  of  individuals  or  companies. 

We  shall,  then,  assume  the  width  between  the  rails  to  be  four  feet  eight  inches  and  a half.  The 
breadth  of  the  bearing  part  of  the  rails  cannot  vary  much ; about  two  inches  and  a half  seem  to  be  the 
width  agreed  upon  by  almost,  if  not  all,  engineers.  The  width  between  the  outside  of  the  rails  will, 
therefore,  be  five  feet  one  inch  and  a half;  or  five  feet  one  inch  if  the  breadth  of  the  rail  itself  be  two 
inches  and  a quarter. 

Width  between  the  two  tracks. — The  next  consideration  is  the  width  between  the  tracks  of  the  railway. 
Upon  the  Liverpool  and  Manchester,  the  width  was  made  the  same  as  that  between  the  rails,  viz,  four 
feet  eight  inches  and  a half.  On  the  London  and  Birmingham,  and  the  Grand  Junction  Railways,  the 
width  is  six  feet;  and  less  than  this  is  not  considered  advisable,  and  is  the  width  almost  universally 
adopted  in  this  country. 

Width  on  the  outside  of  the  rails. — The  next  question  to  determine  is  the  width  required  on  the  out- 
side of  the  rails,  or  between  the  rails  and  the  edge  of  the  embankment,  or  side  of  the  excavations.  This 
is,  to  a great  extent,  determined  by  what  is  necessary  to  keep  the  ties  firm,  to  preserve  the  stability  of 
the  rails,  and  to  effect  the  passage  of  the  engines  and  carriages  along  the  railway  with  every  possible 
security.  Where  economy  of  construction  has  been  a primary  object,  a width  of  three  feet  and  a half 
from  the  rails  to  the  outer  edge  of  the  embankment  or  footpath  of  the  excavation,  or  from  n to  k,  or  o' 
to  l,  Figs.  3180  and  3181,  has  been  found  sufficient  to  secure  adequate  firmness  and  stability  to  the 
blocks,  or  cross-ties  and  rails. 

But  there  is  another  very  important  object  to  effect, — the  width  necessary  to  secure  the  safety  of  the 
engines  and  carriages  passing  along  the  railway,  and  which  is  more  difficult  to  determine,  without 
going  into  the  subject,  in  a speculative  point  of  view.  The  width  necessary  to  prevent  the  cars  running 
off  the  bank  will  vary  very  materially,  according  to  the  circumstances  of  the  case ; the  speed,  the  weight, 
the  dimensions,  and  the  shape  of  wheels,  the  material  forming  the  road-bed,  the  method  of  laying  the 
rails,  the  alignment  of  the  road,  whether  straight  or  curved,  <fec.,  all  having  more  or  less  bearing  on 
this  dimension  to  insure  safety.  It  has  been  attempted  to  investigate  this  question  mathematically,  but 
it  is  one  of  the  few  questions  wholly  beyond  such  method  of  determination.  Its  solution  can  only  be 
arrived  at  by  practical  observation  and  experience.  A standard  writer  on  railroads  has  calculated  that 
this  dimension  should,  when  the  road  is  travelled  at  a speed  of  twenty  miles  per  hour,  never  be  less 
than  the  distance  between  the  rails  of  the  two  tracks.  This,  it  appears  to  us,  is  unnecessarily  great, 
and  failing  a more  rigorous  solution  of  the  question,  we  will  assume  as  the  proper  distance  outside  of  the 
track,  the  distance  very  generally  adopted  in  this  country,  as  well  as  on  some  foreign  roads,  and  which 
s found  to  answer  sufficiently  well,  viz.,  three  feet. 


558 


RAILROADS. 


Supposing  the  width  of  gage  to  be  4 feet  8J  inches,  ov  to  outside  of  rails  to  be  five  feet  one  inch 
between  the  tracks  six  feet ; and  the  breadth  on  the  outside  of  the  rails  three  feet  on  each  side ; wo 
have,  then,  the  width  of  the  entire  road,  at  the  level  of  the  rails,  or,  between  lc  and  l , Figs.  3181  and 
3180,  twenty-two  feet  two  inches.  The  only  remaining  questions  for  consideration,  are  the  slopes  g k, 
h l,  required  for  the  filling  of  the  road,  and  the  width  required  for  the  drainage  of  the  excavations.  The 
depth  of  the  filling  is  usually  two  feet  or  two  feet  three  inches,  and  a slope  of  one  foot  horizontal,  to  one 
foot  perpendicular,  is  found  to  be  sufficient. 

The  width  of  the  drainage  eg,  hd,  Fig.  3180,  will  vary,  according  to  the  quantity  of  water  required 
to  be  conveyed  off ; but  one  foot  and  a half  on  each  side,  at  the  bottom  level,  is  generally  Lund 
sufficient. 

We  have,  then,  the  width  of  the  excavations  at  the  bottom  level,  as  follows: 

feet,  inches. 


’’wo  lines  of  railway,  including  rails  10  2 

Width  between  the  two  lines 6 0 

Width  on  the  outside  of  rails  6 0 

Width  required  for  the  slopes  4 0 

Width  for  the  drainage .' 3 0 


29  2 

which  will  be  the  width  /V,  c d,  Fig.  3180. 

And  for  the  embankments,  or  Ik,  Fig.  3181,  which  require  no  width  for  drainage,  three  feet  less,  or 
twenty-six  feet.  And  where  the  slope  of  the  embankments  is  one  and  a half  to  one,  the  width  at  the 
bottom  level,  so  called,  (two  feet  three  inches  below  grade,)  is  thirty-three  feet  nine  inches. 

Slopes  of  the  excavations  and  embankments. — Having  now  ascertained  the  width,  it  is  next  necessary 
to  determine  the  angle  to  be  given  to  the  slopes  of  the  excavations  and  embankments.  These 
depend,  in  some  degree,  upon  the  depth  of  the  excavation,  or  height  of  the  embankment ; in  the  former, 
when  the  material  is  sand,  gravel,  or  gravelly  clay,  a slope  of  one  and  a half  horizontal,  to  one  perpen- 
dicular, is  quite  sufficient ; and  in  excavations,  up  to  thirty  or  forty  feet,  this  slope  has  been  found  to 
stand  very  well.  In  some  descriptions  of  clay  a greater  slope  is  given,  sometimes  as  much  as  tw'o 
to  one.  The  embankments  are  generally  made  with  the  same  slope  as  that  of  the  excavations ; and  it 
is  presumed  that,  with  whatever  slope  the  excavation  will  stand,  the  embankment  formed  of  the 
material  from  such  excavation  will  stand  with  the  same  angle  of  slope. 

On  the  English  railways  the  slopes  are  covered  with  a layer  of  soil,  which  is  procured  from  the  base 
of  the  embankments,  or  from  the  top  of  the  cuttings ; this  layer  of  soil  is  spread  over  the  face  of  the 
slope  about  six  inches  thick,  or  of  the  thickness  which  the  soil  from  those  places  w'ill  yield.  It  is  of 
great  importance  to  the  security  of  the  slopes,  that  the  soil  should  be  laid  on  as  soon  as  possible,  after 
the  excavation  is  made,  or  the  embankment  consolidated  ; and  sown  wdth  grass  or  clover,  or  both,  to  get 
a turf  upon  it  before  the  slopes  are  affected  by  the  action  of  the  weather.  By  doing  so  slopes  will  often 
stand,  where,  without  the  soiling  and  turf,  or  when  exposed  to  the  action  of 
the  weather,  they  will  not  stand.  This  is  very  much  neglected  in  this  <J~ 

country,  and  the  conseauonce  is,  the  cuts  are  in  general  either  badly 
drained,  or  a gang  of  hands  are  constantly  at  wTork  to  keep  the  ditch  free 
from  the  wash  of  the  slopes ; and  it  is  a good  practice  to  sow  the  slope 
with  some  hardy  grass-seed,  or  defend  it  from  washing  by  loose  stones 
thrown  over  the  bank. 

In  these  figures  we  have  shown  the  slope  of  the  excavation  to  run 
down  to  the  bottom  of  the  drain.  In  some  cases,  where  stone  is  plentiful, 
and  where  there  is  an  excess  of  cutting,  side  walls,  similar  to  Fig.  3182, 
are  built,  to  retain  the  sides  of  the  excavation,  the  line  p q showing,  in  that 
case,  the  line  of  the  slope.  In  such  cases,  stone  drains,  similar  to  that  shown  at  g,  are  made  to  still 
further  diminish  the  width  of  the  railway.  The  propriety  of  doing  this  is,  however,  entirely  a matter 
of  calculation. 

Foundations  for  the  cross-ties. — The  line  having  been  formed  to  the  proposed  inclination  longitudi- 
nally, it  is  then  levelled  transversely.  But,  as  the  material  constituting  the  base  of  the  railway,  in  the 
excavations  and  embankments,  is  rarely  a proper  material  for  a road-bed,  it  is  necessary  to  cover  these 
surfaces  over  with  some  material  which  will  allow  the  water  to  drain  off  from  the  bottom  of  the 
ties,  and  which  will  likewise  form  a sufficiently  firm  foundation  for  the  ties  to  rest  upon.  This  is  gen- 
erally done  by  a layer  or  coating  of  broken  stone,  or  clean  gravel,  whichever  is  found  the  least  ex- 
pensive. 

The  drainage  having  been  effected,  and  the  under  coating  of  broken  stone  having  been  all  spread 
upon  the  line,  the  next  operation  is  setting  the  blocks  or  ties. 

On  all  the  excavations  where  stone  blocks  can  be  had  at  a moderate  cost,  and  on  the  embankments 
which  are  perfectly  consolidated,  which,  by  the  way,  is  never  sufficiently  the  case  on  a new  road,  they 
may  be  used ; but  upon  high  embankments  made  of  clay,  and  which  are  constantly  settling  down,  it  is 
found  most  advisable,  in  the  first  instance,  to  lay  down  wooden  sleepers  or  ties,  stretched  across  from 
one  rail  to  the  other. 

It  has  been  the  custom  in  England  to  lay  the  rails  on  stone  blocks,  which  rest  on  a laj-er  of  broken 
stone  about  nine  inches  thick,  and  the  whole  filled  in  afterwards  or  “ ballasted,”  as  it  is  called,  with 
gravel.  If  broken  stone  be  used,  about  one  foot  in  depth  will  be  sufficient;  but  if  gravel  be  used,  it  is 
customary  to  lay  a greater  depth,  about  two  feet.  This  serves  as  a drain  to  take  off  the  surface  water 
and  prevents  its  freezing  at  the  bottom  of  the  ties  or  blocks. 

The  American  system,  however,  is  beginning  to  prevail  to  a great  extent ; viz.,  the  use  of  cross-ties  of 
wood  instead  of  stone  blocks,  upon  which  to  rest  the  rail  In  our  country,  where  the  frost  is  so  severe, 


RAILROADS. 


559 


the  difficulty  and  expense  of  setting  and  preserving  the  stone  blocks  is  very  great,  and  they  have  long 
since  been  abandoned  for  the  wood  ties ; and  even  in  England,  some  roads  originally  laid  with  stone 
blocks  have  been  taken  up  and  wood  cross-ties  substituted  in  lieu  of  the  stone  blocks.  And  in  fact,  ii 
the  experience  in  this  country  be  worth  any  thing,  this  may  be  considered  the  proper  method,  as  most 
modern  works  are  now  projected  on  this  plan. 

These  wooden  sleepers  are  made  from  eight  to  ten  feet  long,  eight  to  ten  inches  broad,  and  about 
five  inches  thick. 

When  the  blocks  are  set,  or  sleepers  laid,  as  the  case  may  be,  the  space  between  the  blocks,  and  on 
the  outside  of  the  rails,  is  filled  up  to  about  three  inches  above  the  top  of  the  blocks,  or  about  the  same 
depth  below  the  top  of  the  rails. 

/Seating!  the  chairs  upon  the  blocks. — A seat  is  first  made  upon  the  top  of  the  block,  perfectly  level, 
and  in  the  same  plane  as  the  base  of  the  block,  upon  which  the  chair,  of  cast-iron,  and  weighing  from 
20  to  40  pounds,  is  to  be  set.  Holes  are  drilled  into  the  stone,  about  two  inches  in  diameter,  into  which 
oaken  plugs  are  driven,  Fig.  3183  ; these  plugs  are  then  bored  with  a three-eighth  inch  auger,  and  the 
chair,  having  been  properly  seated  upon  the  top  of  the  block,  an  iron  pin  is  driven  through  the  hole  of 
the  chair  into  the  wooden  plug,  and  which,  having  a head,  fastens  the  chair  to  the  sleeper. 


3183. 


3195. 


Keying  the  rails  to  the  chairs. — Various  methods  have  been  devised  for  fastening  the  rail  to  the  chair. 
Iron  wedges,  keys,  and  pins,  and  sometimes  a union  of  all  three,  have  in  their  turn  had  then  advocates  ; 
but  all  metal  fastenings  are  objectionable,  as  all  are  found  to  work  loose.  Wooden  keys  or  wedges  are 
beginning  to  be  in  favor.  Fig.  3184  is  the  rail  used  on  the  London  and  Birmingham  Railway,  and  weighs 
sixty -five  pounds  per  yard;  and  which  is  the  form  of  rail  used  upon  the  Grand  Junction  Railway. 


3184. 


3185. 


4199. 

o s a cc 

Xml - - I-  ' ; 


3187. 


These  rails  are  secured  to  the  chair  by  a wooden  key,  a a,  Figs.  3184  and  3185.  One  side  of  the  chair 
is  bevelled  vertically,  against  which  the  wedge  acts,  and  pressing  against  the  upper  side  of  the  base  of 
the  rail,  forces  it  downwards  into  the  chair,  while  it,  at  the  same  time,  forces  the  rail  against  the  other 
check  of  the  chair.  These  keys  are  made  of  oak  and  well  dried,  so  that  when  driven,  and  exposed  to 


3205. 


a a a- 

H 

^ 

R| 

V 

B 

h 

O 

A -!_ ' f 

H 

0 

,o 

tne  humidity  of  the  atmosphere  by  expanding,  they  act  with  very  powerful  effect  in  fastening  the  ran 
to  the  chair;  so  much  so  as  in  some  cases  to  split  the  chair.  The  plan  B of  Fig.  3184  shows  the  form 
of  the  wedge  a a longitudinally ; by  this  it  will  be  seen  that  the  side  of  the  chair  is  convex;  when, 


560 


RAILROADS. 


therefore,  the  wedge,  being  quite  dry,  is  driven  between  the  rail  and  chair,  and  expanding  by  the  damp 
of  the  atmosphere,  it  is  very  tightly  compressed  by  the  convexity  of  the  chair,  which  produces  a corre- 
sponding expansion  at  the  ends,  and  thus  fastens  the  wooden  wedge  so  securely  that  no  working  takes 
place  between  it  and  the  rail  or  chair.  This  key  has,  of  course,  no  tendency,  except  the  mere  friction  or 
pressure  of  its  sides,  to  prevent  the  ends  of  the  rails  at  the  joint  from  separating. 

Fig.  3186  represents  the  form  of  chair  in  use  on  the  New  York  and  Erie  Railroad,  in  this  State,  which 
is  found  to  answer  a good  purpose.  The  chair  is  complete  in  itself,  and  the  rail  fastened  by  means  ol 
it  and  the  spikes  to  the  cross-ties,  independent  of  the  oak  wedge,  which  is  driven  in  to  prevent  the 
rattling  of  the  rail  in  its  seat,  from  the  vibration  caused  by  the  passage  of  the  train.  It  will  be  per- 
ceived that  the  action  of  the  wedge  forces  the  rail  down  in  the  chair  and  firmly  against  its  opposite 
cheek. 

The  effect  of  the  expansion  and  contraction  of  the  rails,  by  the  variation  of  temperature,  amounts  to 
about  the  fifteenth  part  of  an  inch  in  a rail  fifteen  feet  in  length.  It  has  been  attempted  to  obviate  this 
shock  by  forming  the  ends  into  a half-lap  joint,  but  with  partial  success  only.  The  best  thing  that  can 
be  done  at  present  is  to  preserve  the  parallelism  of  the  upper  surface  of  the  rail ; but  the  opening  of  the 
joint  is  inevitable,  as,  from  the  expansion  and  contraction  of  the  rail,  an  open  joint  must  be  left, 
dependent  in  its  dimensions  upon  the  temperature  at  the  time  of  laying  the  rails. 


3188.  3190.  3192.  3194. 


Fig.  31  SI  is  a plan  of  rail  laid  down  on  some  of  the  railroads  in  this  country;  with  this  rail  chairs 
are  dispensed  with,  the  base  of  the  rail  being  very  broad,  and  being  laid  upon  the  longitudinal  sills  or 
cross-ties,  is  fastened  to  them  by  the  brad-headed  spikes  c and  d,  which  are  driven  into  the  sills.  A 
notch  is  cut  near  the  end  of  the  rail  on  each  side,  somewhat  longer  than  the  width  of  the  spike  which 
is  driven  through  the  notch,  thus  permitting  the  rail  to  expand  or  contract,  while  the  flat  head  of  the 
spike  confines  it  firmly  to  the  cross-ties. , This  has  become  a favorite  mode  of  fastening  rails  in  this 
country,  and  may  be  said  to  be  universal,  sometimes  without  any  chair  at  the  ends,  and  sometimes 
with  a mere  plate  to  prevent  the  ends  of  the  rail  from  bedding  themselves  into  the  wood.  This  form 
of  rail  is  now  known  in  Europe  as  the  “ American  rail.”  The  following  are  a few  of  the  various 
patterns  of  rail  in  use  : 

Fig.  3188  is  the  section  of  an  experimental  fish-bellied  or  elliptical  rail,  rolled  by  the  Newcastle  and 
Carlisle  Railway  Company,  for  the  purpose  of  ascertaining  the  comparative  rigidity  of  this  kind  of  rail, 
and  parallel  rails  of  the  same  weight  per  yard  ; the  w'eight  of  this  rail  was  about  fifty  pounds  per  yard  ; 
the  figure  shows  the  extreme  depth,  and  the  dotted  line  a b the  smallest  depth. 

Fig.  3189  is  the  section  of  the  parallel  rail,  rolled  for  the  purpose  above  described,  the  weight  of 
which  was  as  nearly  fifty  pounds  per  yard  as  it  could  be  rolled.  The  area  of  the  wearing  or  top  part 
of  the  two  rails  is  precisely  the  same,  as  likewise  the  breadth  of  the  base ; but  they  differ  in  the  depth 
and  thickness  of  the  middle  part  of  the  rail. 

Fig.  3190  is  the  section  of  a parallel  rail,  used  upon  the  Liverpool  and  Birmingham,  or  Grand  Junction 
Railway,  and  weighing  about  sixty-two  pounds  per  yard.  The  top  and  base  of  this  rail  are  the  same 
section. 

Fig.  3191  is  the  section  of  a rail  used  on  the  Dublin  and  Kingston  Railway,  and  which  is  a parallel 
rail,  weighing  about  forty-five  pounds  per  yard. 

Fig.  3192  is  a fish-bellied  rail,  made  by  Mr.  Stephenson,  and  weighing  about  forty-four  pounds  per 
yard.  The  entire  section  on  the  drawing  shows  the  extreme  depth  in  the  middle,  and  the  line  a b the 
depth  at  the  bearing  parts.  This  rail  does  not  swell  out  at  the  base,  being  intended  to  be  keyed  into 
the  chair. 

Fig.  3193  is  the  section  of  a parallel  rail,  of  the  weight  of  fifty  pounds  per  yard,  a few  of  which  are 
laid  down  on  the  Liverpool  and  Manchester  Railway. 


3201.  3202.  3204. 


Fig.  3194-  is  the  section  of  a rail  intended  for  the  Great  North  of  England  Railway,  the  weight  of  which 
is  about  sixty  pounds  per  yard.  This  is  likewise  a parallel  rail ; the  mode  of  keying  this  rail  differs 
from  any  of  the  preceding  plans,  and  is  shown  in  Figs.  3195  and  3196,  Fig.  3196  being  a section,  and  Fig 
3195  a plan.  One  side  of  the  chair  is  cast  to  fit  the  rail;  on  the  other  side  of  the  chair  a loose  inter- 
mediate wedge  slides  between  the  cheeks  of  the  chair,  shown  at  e ; this  intermediate  wedge  is  keyed 
against  the  rail  by  the  driving-key/,  which  may  be  driven  with  any  degree  of  tightness;  the  interme- 
diate key  prevents  the  vibration  of  the  rail  from  loosening  the  key  f This  chair,  it  will  be  seen,  has 
four  pins  to  fasten  it  to  the  block. 


RAILROADS. 


56.1 


Fig.  3197  is  the  section  of  a parallel  rail,  laid  down  on  the  Liverpool  and  Manchester  Railway,  and 
weighing  sixty  pounds  per  yard.  In  all  the  preceding  figures  of  rails,  both  sides  of  the  top  or  wearing 
part  of  the  rail,  whereon  the  wheels  roll,  is  the  same  ; but  as  it  is  only  on  one  side  of  the  rail  that  the 
flanch  of  the  wheel  rolls  against  it  below  the  plane  of  the  top  of  the  rail,  the  wheel  on  the  other  side 
rolling  along  the  plane  of  the  surface,  it  is  evident  that  there  is  no  necessity  to  have  both  sides  the 
same.  In  this  case  the  side  of  the  top,  acted  against  by  the  flanch  of  the  wheel,  is  of  the  same  outline 
as  that  part  of  the  wheel ; while,  on  the  opposite  side,  the  section  is  at  right  angles  to  the  plane  of  the 
top.  This  plan,  however,  prevents  the  rail  from  being  turned  with  the  opposite  side  to  the  flanch  of  the 
wheel,  which  it  is  sometimes  found  requisite  to  do. 

Fig.  3198  is  a section  of  the  thirty-five  pounds  per  yard  fish-bellied  rail,  originally  laid  down  upon 
the  Liverpool  and  Manchester  Railway ; the  entire  figure  showing  the  extreme  depth  in  the  middle,  and 
the  line  a b the  depth  in  the  bearing  parts  of  the  rail.  The  mode  of  keying  this  rail  is  shown  in  Fig.  3199. 

Fig.  3200  is  a section  of  a fifty  pound  per  yard  elliptical,  or  fish-bellied  rail,  laid  down  on  the  Liver- 
pool and  Manchester  Railway : the  section  of  this  is  nearly  similar  to  the  preceding  figure,  except  in 
the  area  and  weight;  the  keying  is  precisely  similar;  the  line  ab  shows  the  depth  at  the  bearings. 

Fig.  3201  is  a parallel  rail,  weighing  seventy-five  pounds  per  yard,  and  laid  on  the  London  and 
Birmingham  Railway.  The  mode  of  keying  is  similar  that  shown  in  Fig.  3199 ; the  distance  of  the 
supports,  five  feet. 

Fig.  3202  is  the  section  of  the  parallel  rail,  laid  down  upon  the  Liverpool  and  Manchester  Railway, 
weighing  seventy-five  pounds  per  yard.  The  top  of  this  rail  is  made  of  the  shape  explained  in  Fig.  3197. 

Fig.  3203  is  another  sixty  pounds  per  yard  parallel  rail,  which  has  been  laid  down  upon  the  Liver- 
pool and  Manchester  Railway. 

Fig.  3204  is  the  section  of  the  rail  laid  down  upon  the  Newcastle  and  Carlisle  Railway ; it  is  an  ellip- 
tical or  fish-bellied  rail,  shown  in  Fig.  3205,  with  a convex  projecting  knob  at  the  bearing  points.  The 
entire  figure  in  the  plate  shows  the  extreme  depth  of  section  at  a'  b',  Fig.  3205,  and  the  line  a b,  Fig. 
3204,  the  depth  near  the  knob,  the  latter  swelling  out  the  depth  of  half  an  inch  more  within  the  chair. 
These  rails  weigh  forty-two  pounds  per  yard,  and  are  laid  in  fifteen  feet  lengths,  with  five  bearings  of 
three  feet  each. 

The  compound  rail,  designed  with  a view  to  correct  the  defect  experienced  in  the  simple  rail  at  the 
joint,  is  now  receiving  a good  deal  of  attention  from  engineers.  Several  plans  have  been  devised,  but 
all  of  them  want  the  results  of  experience  before  they  can  be  recommended  for  general  adoption.  Un- 
doubtedly the  defects  of  the  joints  are,  to  a great  extent,  remedied  by  the  compound  rail,  but  it  is 
questionable  if  in  this  country  greater  evils  would  not  result  by  increasing  the  number  of  piarts  of  a 
machine  already  so  complicated  and  difficult  to  keep  in  repair  as  a railroad. 

Curves  on  the  line  of  railway. — It  has  been  usual  to  construct  the  wheels  for  railway  carriages  so  that 
the  outside  rim  is  conical,  or  enlarged  in  diameter  next  the  flanch;  when,  therefore,  the  carriages  are 
passing  round  a curve,  the  wheels  being  connected  together  by  the  axle,  forms,  as  it  were,  a conical 
roller,  running  upon  the  rails  with  different  radii ; the  larger  radii  being  on  the  outside  curve  of  the  rail. 
This  increase  in  the  diameter  of  the  wheel  running  on  the  outside  compensates,  to  a certain  extent,  for 
the  increased  length  of  the  outer  curve  of  the  rail ; and  if  the  radius  of  the  curve  is  not  less  than  the  line 
which  the  two  wheels  of  unequal  radii  would  describe,  the  wheels  will  travel  along  the  line  of  the  curve 
without  rubbing  against  the  Handles.  But  if  the  curve  is  more  acute  than  such  a line,  then  the  flanches 
of  the  wheels  are  the  only  guides  to  keep  the  carriages  on  the  rails. 

The  degree  of  cone  generally  given  to  the  tire  of  the  carriage  wheels  is  to  make  the  diameter  next 
the  flanch  one  inch  larger  than  the  diameter  next  the  outside  of  the  tire,  the  breadth  being  34  inches. 
In  practice,  it  is  likewise  usual  to  keep  the  wheels  at  such  a distance  from  each  other  upon  the  axles, 
that,  when  travelling  upon  a straight  line,  the  flanches  on  each  side  are  about  one  inch  from  the  rail. 
With  a view  to  provide  against  the  centrifugal  force  of  the  carriages  when  running  in  a curve,  it  has  been 
customary  to  elevate  the  outer  rail  of  the  track. 

The  following  table  will  show  the  elevation  to  be  given  to  the  outside  rail,  of  different  radii,  above 
that  of  the  inner  rail ; so  that  the  whole  amount  of  centrifugal  force  is  balanced  by  that  of  the  gravity 
of  the  load,  towards  the  inside  of  the  curve. 


Description  of  wagon  and  width  of 


Radius  of 


Surplus  of  elevation  in  inches,  the  velocity  in 
miles  per  hour  being : 


railway. 

in  feet. 

10  miles. 

15  miles. 

520  miles. 

30  miles. 

250 

1T6 

3-04 

5-67 

13- 

Diameter  of  wagon  wheels  3 feet ; 

500 

•58 

1-52 

2-83 

6'57 

width  of  railway  4 feet  8 inch. ; 

1000 

■29 

•76 

1-42 

3-30 

inclination  of  the  tire  of  the 

2000 

•15 

•38 

•71 

1'65 

wheel  ^ inch  in  the  breadth, 

3000 

TO 

•25 

•47 

1T0 

viz.,  3-1  inches. 

4000 

•07 

•20 

■36 

■83 

5000 

•06 

T5 

•29 

•67 

J 

It  was  a few  years  back  the  custom  in  this  coantry,  as  it  still  is  to  a great  extent  in  England,  to 
cone,  as  it  is  called,  the  tires  of  the  wheels  with  a view  to  prevent  the  rubbing  of  the  flaiKlies  of  the 
wheels  in  passing  the  curves.  The  above  calculations  of  the  elevation  of  the  outer  rails  includes,  as  an 
element,  this  coning  of  the  wheels.  Theoretically  and  practically,  with  a given  speed,  this  is  correct 
but  the  passenger,  express,  and  freight  trains,  travelling  at  very  different  speeds  without  their  wheels 
Vol.  II. — 36 


RAILROADS. 


m2 


are  coned  at  different  angles — which  in  practice  would  he  very  inconvenient,  if  not  wholly  impractica- 
ble— the  different  elevations  of  the  outer  rail  would  not  meet  the  necessities  of  the  particular  case 
a9  a speed  of  30  miles  per  hour  requires  an  elevation  some  11  times  greater  than  a speed  of  10 
miles.  It  is  now,  in  this  country,  the  custom  to  disregard  this  coning  of  the  wheels  to  the  extent  which 
the  theory  would  call  for,  and  simply  cone  them  to  the  amount  of  the  draft  (as  it  is  called)  of  the  cast- 
ing, about  J inch  on  the  tread  of  the  wheel;  and  engineers  differ  very  much  as  to  the  proper  amount  Oi 
elevation  which  should  be  given  to  the  outer  rail.  The  actual  amount  to  meet  a given  speed  is  easily 
estimated ; but  whether  it  is  expedient  to  give  more  or  less  than  this,  or  to  provide  for  the  freight  or 
passenger  trains,  is  as  yet  an  unsettled  question. 

As  there  can  be  no  doubt  that  the  higher  velocities  of  passenger  trains,  even  with  their  less  load,  is 
nroductive  of  greater  injury  to  a road  than  the  freight  trains,  it  would  seem  desirable  to  adjust  the  rail 
with  the  surplus  elevation  due  the  higher  velocity ; if  the  road  were  essentially  a passenger  road,  or  in 
other  words,  without  the  freight  trains  were  largely  in  excess  of  the  passenger  trains,  to  suit  the  curves 
to  the  latter  traffic,  having  in  view  the  diminution  of  “wear  and  tear”  of  both  wheels  and  rail,  rather 
than  an  economy  of  motive  power. 

Great  Western  Railroad  in  England — Mr.  BruneTs  plan. — Figs.  3205,  3206,  and  3181,  (p.  519,)  show 
a plan  apd  different  sections  of  Mr.  Brunei’s  plan  of  railway.  ABCDEF  and  G H are  the  longitudinal 
rails  forming  the  railway ; these  longitudinal  rails  are  14  to  15  inches  broad  and  6 or  7 inches  thick,  and 
are  made  of  American  pine,  ah'  ah'  and  cd'  cd'  are  double  transverse  ties  or  sleepers,  which  are  each 
six  inches  in  breadth  and  seven  inches  deep ; and  ef  single  transverse  ties  or  sleepers,  which  are  six 
inches  in  breadth  and  nine  inches  deep.  These  sleepers  are  stretched  across  the  line  of  railway,  and  tc 
them  the  longitudinal  rails  are  secured.  1 2 3 4 5 and  6 are  piles  which,  in  the  cuttings,  are  from  nine 
to  fourteen  feet  in  length,  according  to  the  nature  of  the  material,  and  in  the  embankments  12  to  30 
l'eet,  or  of  such  a length  as  that  they  will  reach  from  the  base  or  formation  line  of  the  railway  6 to  8 
feet  into  the  original  surface  of  the  ground.  The  cross-ties  are  American  pine,  and  the  piles  of  beech. 


3205. 


The  plan  of  construction,  or  of  forming  the  railway,  is  as  follows : the  piles  are  driven  at  intervals  of 
every  fifteen  feet,  as  shown  in  the  drawing,  and  in  the  middle  between  the  longitudinal  rails.  In  cut- 
tings, they  are  driven  from  eight  to  ten  feet  into  the  ground,  below  the  level  of  the  cross-sleepers;  and 
on  embankments  they  must  be  of  such  a length  as  to  be  driven  about  the  same  depth,  or  seven  or  eight 
feet  into  the  original  ground.  Upon  an  embankment  of  three  feet  they  must  be,  therefore,  ten  or  twelve 
feet  long,  and  so  on,  according  to  the  height  of  embankment,  and  the  kind  of  subsoil  into  which  they  are 
to  be  driven.  These  piles  are  always  to  be  driven  to  the  exact  depth  required ; no  part  of  the  head  is 
allowed  to  be  cut  off;  but  if  the  pile  does  not  drive  to  the  proper  depth,  it  must  be  drawn  and  driven 
again.  This  is  for  the  purpose  of  being  certain  that  they  have  sufficient  hold  of  the  ground ; near  the 
head  of  these  piles,  as  shown  at  1 2 3 4 5 6,  Fig.  3205,  and  at  b b'f  and  dd\  Fig.  3206,  a square  shoul- 
der, of  14  inch,  is  made  on  one  side  of  the  piles  for  the  single  ties,  and  on  both  sides  of  the  piles  12  5 6 
for  the  double  ties.  The  ties  or  cross-timbers  are  let  into  these  shoulders,  and  they  are  firmly  bolted  to 
the  piles,  as  shown  in  the  drawings.  The  double  cross-timbers  are  laid  down  thirteen  inches,  and  the 
single  timbers  nine  inches  below  the  line  of  the  rails.  Between  the  double  timbers,  as  shown  at  g g, 
Fig.  3205,  and  also  at  all  the  Other  points  where  the  longitudinal  rails  intersect  the  cross-timbers,  a piece 
of  wood  is  interposed,  which  is  pinned  to  the  cross-timbers,  and  upon  which  the  longitudinal  rails  rest. 

The  longitudinal  rails  are  then  laid  down  upon  the  cross-timbers,  the  upper  surface  of  which  is  three 
inches  below  the  surface  of  the  iron  rails  ; they  are  bolted  to  the  cross-timbers  with  screw-bolts  and 
washers,  as  shown  at  nnnn,  Fig.  3205,  and  by  a larger  scale  in  Fig.  3207,  ef  being  the  cross-timber, 
and  A B the  longitudinal  timbers ; the  latter,  it  will  be  seen,  is  let  into  the  cross-timber  a little,  the 
single  cross-timbers  being  deeper  than  the  double  cross-timbers.  The  head  of  the  bolt  and  washer  is 
countersunk  into  the  upper  surface  of  the  longitudinal  rail,  as  shown  in  the  figure.  One  of  these  bolts 
is  put  in  at  each  of  the  points  of  intersection  of  the  longitudinal  rails  with  the  single  cross-timbers,  and 
vwo  bolts  at  each  of  the  points  of  intersection  with  the  double  timbers. 

When  the  piles  are  firmly  driven,  the  cross-timbers  bolted  to  them,  and  the  longitudinal  timbers 
bolted  to  the  cross-timbers,  then  sand,  or  finely  screened  gravel,  is  beat  or  packed  underneath  the  longi- 
n dinal  timbers,  until  a base  or  bed  is  made  for  them  to  rest  upon,  perfectly  firm,  solid,  and  compact. 

Fig.  3208  shows  a section  of  the  rail  used,  which  weighs  from  4 3 to  44  pounds  per  yard,  and  which 


RAILROADS. 


585 


rests  upon  and  is  secured  to  the  hard-wood  plank  and  timbers  of  the  longitudinal  sills,  and  is  of  the  de- 
scription known  as  the  U or  bridge  rail. 

As  shown  in  the  figure,  the  rails  have  a slight  bevel  inwards. 

The  width  or  gauge  of  the  railway  is  7 feet  2^  inches,  from  centre  to  centre  of  the  rails ; and  the 
width  between  the  centres  of  the  inside  rails  is  6 feet. 

A few  instances  occur  in  this  country  of  the  use  of  stone  blocks  for  the  support  of  the  rail ; but  they 
form  the  exception,  it  being  found  that  the  wear  and  tear  of  machinery  on  the  stone  track  is  much 
greater  than  on  the  wood,  and  in  consequence,  the  use  of  the  latter  material  for  the  support  of  the 
rail  has  become  universal.  Upon  this  depends  in  a great  measure  the  perfection  of  the  road.  The 
point  in  which  our  roads  present  a great  inferiority  when  compared  with  the  English,  is  in  the  want  of 
complete  preparation  of  the  foundation.  All  the  refinement  of  science,  applied  to  the  form  and  dimen- 
sion of  rails,  chairs,  engines,  &c.,  is  useless,  if  the  foundation  be  liable  to  be  thrown  by  frost,  or  to  dis- 
placement from  any  cause.  To  prevent  this,  too  much  care  cannot  he  given  to  the  nature  of  the  mate- 
rial forming  the  road-bed,  and  to  the  position  and  preservation  of  the  ditches.  All  material  impervious 
to  water  should  be  excavated  from  the  bed  of  the  road  to  the  depth  at  least  of  two  feet,  and  its  place 
supplied  by  clean  gravel.  The  sleepers  or  cross-ties  of  chestnut,  cedar,  oak  or  other  durable  wood,  ac- 
cording to  the  locality,  are  laid  transversely,  at  intervals  of  about  two  feet.  These  ties  should  be  at 
least  6 inches  deep  by  7 or  8 inches  wide,  and  for  the  narrow  gauge  8 feet  long.  Upon  these  cross  ties 
are  to  he  spiked  the  iron  rails. 

The  rail  is  usually  secured  in  the  chair  by  the  brad-headed  spikes  which  hold  the  latter  to  the  ties,  the 
notch  in  the  rail  for  the  spike  being  elongated  so  as  to  permit  the  expansion  and  contraction  of  the  rail,  or 
else  the  chair  is  fastened  independently  of  the  rail,  and  the  latter  prevented  from  rising  out  of  the  chair 
by  the  latter  being  made  to  conform  to  the  shape  of  the  rail,  so  that  it  cannot  be  removed  from  its 
chair  but  by  drawing  it  out  in  the  direction  of  its  length.  At  the  intermediate  cross-ties  the  rail  is 
secured  inside  and  out  by  the  brad-headed  spike  driven  into  the  tie  on  each  side,  and  lapping  over  the 
base  of  the  rail.  The  rail  may  be  further  secured  in  the  chair  by  a wooden  wedge,  sawn  to  a taper, 
and  driven  into  the  chair  against  the  bottom,  side,  and  top  of  the  rail,  one  side  of  the  chair  being  cast 
to  receive  it.  It  is  not  advisable,  however,  to  make  the  fastening  of  the  rail  in  the  chair  dependent 
entirely  upon  the  wedge.  The  chair  should  be  safe  against  accident,  were  the  wedge  to  drop  out ; 
out  the  use  of  the  latter  should  be  to  perfect  the  joint,  and  prevent  the  small  motion  in  the  chair  oc- 
casioned by  the  vibration  of  the  rail,  which  in  the  end  might  prove  the  destruction  of  the  chair.  The 
spikes  should  be  machine-made,  with  chisel  points,  and  weigh  at  least  half  a pound  each,  and  occupying 
in  length  the  dejrth  of  the  cross-tie.  After  the  rails — we  have  supposed  the  H or  U section,  of  about 
from  60  to  80  pounds  per  yard — are  laid  and  spiked,  and  the  line  of  rails  adjusted  to  their  proper 
adjustment,  the  ballast  of  clean  gravel  is  brought  into  the  road  and  deposited  between  and  around 
the  cross-ties,  packed  well  underneath  them  with  the  shovel  and  rammer,  and  levelled  off  to  the  plane 
of  the  bottom  of  the  rail,  nearly.  This  is  the  method,  with  some  modification,  which  prevails  pretty 
generally  in  the  construction  of  the  modern  railroad.  A longitudinal  bearing  under  the  rail,  into  which 
the  cross-ties  are  framed  something- similar  to  the  Western  Railroad  in  England,  is  occasionally  adopt- 
ed ; but  its  want  of  simplicity,  as  well  as  other  defects,  has  occasioned  its  disuse. 

ROLLING  STOCK.  Under  this  term  are  included  the  locomotives  and  cars.  The  distinctive  feature 
of  the  American  locomotive  will  be  found  under  its  appropriate  head.  Our  cars  are  still  more  peculiar. 
Whilst  the  English,  adopting  the  stage  coach  as  their  model,  made  their  cars  with  compartments  re- 
sembling coach  bodies,  generally  three  to  each  car,  and  supported  on  but  two  sets  of  wheels,  we,  adopt- 
ing a new  and  distinct  construction,  have  adopted  a long  undivided  car,  supported  near  the  ends  by 
trucks  like  the  forward  trucks  of  our  locomotives.  Each  truck  has  not  less  than  two  sets  of  wheels, 
sometimes  three,  and  in  very  rare  instances  four.  Passenger  cars  are  provided  with  seats  for  from  40  to 
60  passengers.  Most  of  the  cars  are  entered  at  the  ends  from  the  end  platforms,  but  in  some,  as  in  the 
Jersey  Railroad  cars,  the  entrance  for  passengers  is  in  the  centre. 

The  freight  cars  are  in  general  construction  similar  to  those  for  passengers,  hut  shorter.  On  a few 
roads  the  short  four-wheeled  cars  are  adhered  to,  and  when  slow  speeds  are  preserved  they  are  more 
economical,  less  dead  weight  in  proportion  to  the  weight  carried,  and  easier  moved  at  the  stations. 
Freight  cars  are  either  open  or  boxed;  ballast  cars  are  usually  two  wheeled,  and  arranged  so  as  to  be 
capable  of  being  dumped. 

The  chief  objection  to  our  present  system  of  cars,  resulting  in  part  from  unnecessary  speed,  is  the 
amount  of  dead,  weight  drawn  in  proportion  to  their  freight ; and  even  this  is  disproportionately  increased 
by  the  often  unnecessary  hauling  of  empty  or  far  from  full  cars.  We  annex  the  following  table  from 
the  Report  of  the  New  York  Commissioners  for  1856. 

The  following  tabular  statement  gives  the  average  cost  per  mile,  for  building  and  manning  the  road; 
also  the  average  amoimt  of  freight  in  tons,  and  the  number  of  passengers  for  one  year : 


Average  cost  per  mile  of  road,  . 
Of  equivalent  siugle  track,  . . 

Average  cost  of  locomotive  en- 
gines and  fixtures,  .... 
Average  cost  of  passenger  and 

baggage  cars, 

Average  cost  of  freight  cars, 
Average  number  of  miles  of  road 
for  one  locomotive,  .... 
\verage  number  of  miles  of  road 
for  one  passenger  car,  . . . 


$50,792 

88 

36,833 

73 

9,625 

50 

2,011 

50 

631 

50 

3.43  miles. 


Average  number  of  miles  of  road 
for  one  freight  car,  .... 
Average  number  cars  per  train, 

passenger, 4.5 

Average  number  per  train  of 
passengers,  ....  72.6 
Average  number  per  cai-,  of 
passengers,  ....  16.13 
Average  number  of  tons  of 
non  - paying  weigh#  per 
passenger,  . . . . 1.17 


0.26  miles, 
freight,  18.2 
“ tons  71.2 

“ “ 3.91 


564 


RAILROADS. 


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RAILWAY"  BARS. 


66? 


The  great  weight  of  the  locomotive  and  of  the  carrying  stock  generally,  has  led  to  various  expedient, 
to  avoid  this  difficulty.  Rope  railways,  that  is  railways  in  which  the  cars  were  drawn  by  ropes  or  chains 
by  means  of  stationary  engines,  had  long  been  used  in  mining  districts  to  overcome  steep  gradients. 
This  system  was  adopted  with  some  ingenious  modifications,  to  propel  cars  on  a level  track,  on  the  Lon- 
don and  Blackwall  railway.  But  it  was  found  uncertain  and  expensive  and  given  up.  In  fact,  at  present 
there  are  but  few  inclines  in  this  country  worked  by  stationary  power,  it  being  found  more  economical  tc 
work  with  the  locomotive  on  zig-zag  or  Y tracks  to  overcome  steep  gradients. 

As  an  improvement  on  the  rope  railway,  Clegg  and  Samuda  introduced  the  atmospheric  railway  upon 
the  Dublin  and  Kingstown  road,  where  it  worked  so  successfully  for  a series  of  years,  that  it  was  intro- 
duced on  the  London  and  Croydon  Railroad,  but  it  proved  a failure.  As  an  expedient  it  was  very  in- 
genious, and  may  perhaps  in  some  form  be  serviceable  on  very  short  lines.  Suppose  a large  pipe  to  be 
laid  down  on  a road,  and  that  at  one  end  of  this  pipe  were  placed  an  air-pump  for  withdrawing  the  air, 
and  at  the  opposite  end  a piston,  working  accurately  in  the  pipe.  On  pumping  out  the  air  from  the 
pipe,  the  atmospheric  pressure  upon  the  piston  would  didve  it  along  the  tube.  In  order  that  the  piston 
and  the  carriages  might  travel  together,  much  in  the  same  way  as  the  short  tube,  or  pencil-holder 
inside  a pencil-case,  travels  with  the  outer  tube  or  ring, — some  connection  is  necessary  between  the 
piston  within  and  the  cars  without  the  tube.  The  arrangement  employed  on  the  line  from  Kingston  to 
Dalkev,  a distance  of  If  mile,  is  as  follows : 

In  this  railway  the  vacuum-pipe  was  about  15  inches  in  internal  diameter ; it  was  of  cast-iron,  and 
was  laid  down  in  the  same  way  as  the  large  water  mains,  between  the  two  rails  of  the  railway.  After 
the  pipes  were  cast,  a cutter  was  passed  through  them  in  the  direction  of  their  length : they  were  then 
raised  to  the  temperature  of  melting  tallow,  and  a mop  dipped  in  that  material  was  passed  through 
them,  and  being  followed  by  a wooden  piston,  the  inside  became  coated  with  a thin  surface  of  tallow, 
which  soon  acquired  great  hardness.  This  was  found  to  be  an  excellent  sui-face  for  the  piston  to  travel 
against.  On  the  top  of  the  tube  was  a narrow  opening  extending  the  whole  length,  closed  by  a valve 
so  as  to  render  the  tube  air-tight.  This  valve  was  a continuous  flap  of  leather,  on  the  upper  and  under 
sides  of  which  plates  of  iron  were  riveted,  the  inner  surface  of  the  lower  plate  formed  to  the  curve  of 
the  pipe,  the  upper  plate  and  the  leather  being  made  a little  wider  than  the  opening  or  slot,  and  extend- 
ing over  it  on  each  side.  This  continuous  valve  was  hinged  on  one  side  to  a projecting  rib,  and  the 
other  edge  fell  into  a groove  containing  a composition  of  wax  and  tallow,  which,  when  melted,  sealed 
up  the  pipe,  and  made  it  sufficiently  air-tight  for  the  working.  A flap  called  the  weather-valve,  protected 
the  apparatus  from  the  weather.  The  piston  contained  within  the  tube  was  furnished  with  a rod  1+  oi 
15  feet  in  length,  to  which  were  attached  rollers  for  opening  the  air-tight  valve  behind  the  piston  as  it 
advanced  along  the  pipe.  The  piston  was  connected  with  tbe  first  carriage,  or  driving-car,  by  means  of 
a coulter  : to  the  driving-car  was  attached  a copper  vessel,  several  feet  in  length,  heated  with  coke,  for 
the  purpose  of  melting  the  wax  and  tallow  when  the  valve  had  been  pressed  down  by  the  apparatus. 

It  will  be  understood,  then,  that  the  train  of  carriages  moved  on  rails  as  in  the  ordinary  railway : 
but  between  the  rails  the  tube  with  its  enclosed  piston  was  situated  ; and  that  an  air-pump  worked  by  a 
stationary  steam  engine  exhausted  the  air  in  the  tube  in  front  of  the  carriages.  The  speed  of  the  train 
would  evidently  be  in  proportion  to  the  rapidity  with  which  the  air  could  be  pumped  out.  It  was  found 
that  an  exhaustion  of  15  inches  could  be  produced  in  about  2 minutes,  and  that  a speed  of  50  or  GO 
miles  an  hour  could  be  produced. 

RAILWAY  BARS.— On  the  manufacture  and  form  of.  The  mass  out  of  which  the  rail  is  rolled  is 
called  a “ pile,”  and  is  composed  of  a number  of  plates  cut  from  rolled  bars  to  a length  suitable  to  the 
convenience  of  handling,  and  the  dimensions  of  the  close-furnace  in  which  the  piles  are  placed  to  receive 
a welding  heat.  The  piles  have  a bed  and  cap  plate  of  double  the  width  of  the  other  plates,  which 
keep  the  pile  together,  and  are  mostly  of  superior  iron  .See  Fig.  3196,  in  which  A represents  the  cross- 
section  of  the  pile. 

3198.— T or  edge  rail. 


The  furnace  is  closed  up  to  prevent  the  iron  from  burning  on  the  surface  before  the  middle  of  the  mass 
is  brought  to  a welding  heat.  It  requires  skill  and  practice  to  judge  of  the  degree  of  heat  necessary  to 
insure  a sound  rail.  If  the  heat  is  not  sufficient  for  an  effectual  weld  through  the  whole  mass,  the  rail, 
when  put  to  the  severe  action  of  the  locomotive-wheels,  will  crush  down,  or  peal  off  in  laminae ; and 
when  the  rail  is  finished  it  is  not  easy  to  see  a defect  in  the  welding,  as  the  surface  may  appear  sound. 
For  this  reason  a close  and  competent  superintendence  of  the  manufacture  is  much  more  important  than 
the  most  careful  inspection  after  the  work  is  done.  It  often  happens  that  a careful  headman,  who  man- 
ages the  rolling,  will  send  back  a pile  to  the  furnace,  before  or  after  passing  it  once  through  the  rolls,  to 
receive  a better  heat.  The  good  quality  of  a rail  is  as  much  dependent  on  effectual  welding  as  on  tha 
quality  of  the  metal. 


566 


RAILWAY  BARS. 


To  obtain  a more  solid  and  durable  surface  on  the  top  of  the  rail,  it  has  been  proposed  to  use  a ham 
mered  bar  of  double  the  usual  thickness  for  the  cap-plate  of  the  pile,  which  would  remain  a solid  ma- 
terial of  considerable  body  after  the  rail  is  finished.  See  Fig.  3197,  in  which  A represents  the  cross- 
section  of  the  pile. 

In  the  composition  of  the  pile  no  scraps  or  short  pieces  should  be  admitted,  for  the  reason  that  the 
process  of  rolling  and  extending  the  mass  lengthwise  is  adverse  to  welding  the  cross-joints  between  the 
pieces,  and  so  far  the  rail  is  diminished  in  strength  and  solidity.  Scraps  and  trimmings  had  better  be 
wrought  into  common  bars,  to  be  worked  over  again  in  the  smith-shop.  The  heavy  rail  is  a finished 
piece  of  work,  and  so  expensive  that  its  efficiency  should  not  be  endangered  by  the  use  of  improper 
materials. 

The  pile  should  always  be  of  sufficient  weight  to  afford  a surplus  in  length,  so  as  to  cut  the  rail  of  the 
desired  length  entirely  clear  of  the  fag-ends.  Rails  are  often  defective  and  give  way  at  the  ends  while 
other  parts  remain  sound,  for  the  want  of  due  attention  to  this  matter. 

3199. — Double-headed  rail,  to  be  reversed.  3200.— H-rail. 


Great  care  should  be  taken  in  the  straightening  and  trimming ; and  the  first  step  is  to  see  that  the 
large  cast-iron  plate  upon  which  the  rail  is  laid  while  hot  from  the  rolls  is  straight  and  out  of  wind — as 
tLe  rail,  being  lifted  and  slammed  down  while  soft,  will  conform  to  its  surface,  and  retain  a twist  when 
cola  if  the  plate  should  be  in  wind.  This  is  a most  mischievous  fault,  and  can  never  afterwards  be  per- 
fectly corrected.  Though  the  surface  may  be  brought  to  a line  longitudinally,  and  the  base  adjusted  on 
the  bearings,  the  pressure  on  the  top,  varying  from  side  to  side,  will  produce  a rocking  action,  lending 
constantly  to  loosen  the  rail. 

Close  attention  should  also  be  paid  to  accurate  straightening,  as  even  a slight  undulation  on  the  sur- 
face will  produce,  at  the  ordinary  velocity  of  the  train,  (30  miles  per  hour,)  a sensible  vibration,  un- 
pleasant to  the  passenger,  and  injurious  to  the  road  and  train. 


3201. — Bridge-rail.  3202. — Three-part  rail. 


To  prevent  rails  having  these  defects  from  being  brought  into  use,  a severe  inspection  should  be 
applied  to  them.  Each  rail  should  be  placed  on  a strong  bench,  in  length  equal  to  that  of  the  rail,  and 
the  surface  plated  with  iron  in  several  places  ; these  plates  should  be  dressed  to  a correct  fine  and  out 
of  wind,  which  will  at  once  detect  any  twist  or  crook  that  may  be  in  the  rail. 

The  circular  saw  is  now  generally  used  in  trimming,  which  is  a great  improvement  over  the  chisel,  as 
it  leaves  the  section  of  the  rail  undisturbed — a very  important  matter  in  making  even  joints. 

In  considering  the  form  of  the  railway  bar,  it  may  be  first  observed  that  the  more  simple  and  com- 
pact the  section,  the  more  sound  will  be  the  rail.  It  is  obvious  in  viewing  a section  of  the  pile,  (see  Fig. 
3196,)  that  there  are  a number  of  joints  between  the  plates  to  be  welded,  and  that  each  plate  must  of 


RAILWAY  BARS. 


5G7 


necessity  be  reduced  to  a thin  lamina  in  extending  the  mass  to  the  length  of  a rail,  and  that  the  strain 
on  the  weldings  and  materials  will  be  much  less  in  one  form  of  section  than  another;  therefore,  in  de 
signing  a form,  it  is  well  to  give  to  this  matter  its  due  consideration. 

The  X or  edge  rail,  set  in  chairs,  and  the  double-headed  rail,  Figs.  3198  and  3199  have  been  exten. 
sively  used  in  Europe ; but  it  is  said  that  the  H,  and  bridge  or  U rails,  American  designs,  are  coming 
into  favor  there.  They  have  long  been  the  favorite  patterns  in  America,  and  do  now  divide  the  opin- 
ions of  professional  men  and  railway  companies,  so  that  the  two  are  placed  in  competition  on  extend  ve 
divisions  of  the  same  line,  and  on  different  roads.  Each  has  its  peculiar  merits. 

The  H-rail  has  the  advantage  in  simplicity  and  beauty  of  form,  and  may  have  in  solidity,  by  a mod 
ification  of  the  section.  The  head  and  base  are  generally  made  too  light,  (see  Fig.  3200.)  It  also  affords 
a better  base  for  its  support  on  the  bearings. 

The  U or  bridge  rail  has  the  advantage  of  perpendicular  sides  to  support  the  head,  without  projections 
subject  to  be  split  off,  like  the  H-rail.  It  also  offers  better  facilities  in  its  hollow  form  to  secure  strone 
and  even  joints,  by  the  insertion  of  an  iron  core  at  those  points.  See  Fig.  3201. 

3204. 


3203.— Two-part  H-rail. 


But,  after  all  the  exertion  of  talent  and  skill  for  the  last  twenty  years  to  perfect  a line  of  road  with 
the  usual  form  of  rails,  it  still  remains  very  deficient  in  smoothness  and  stability  at  the  joinings,  and  it 
is  feared  will  continue  to  be  so  while  the  rails  are  made  in  independent,  separate,  solid  pieces 

The  perfection  of  a rail  would  be  one  of  sufficient  and  uniform  strength— rolled,  or  made  by  other 
means — in  one  piece,  without  joints  the  whole  length  of  the  line ; but  this  being  impracticable,  the  effort 
is  now  to  approach  it  by  a new  device,  which  is  to  form  the  rail  of  two  or  more  pieces,  say  20  feet  in 
length,  and  to  splice  them  together,  breaking  joint,  so  that  each  part  shall  act  as  a splicing-plate  to  the 
others  where  their  ends  meet. 

A three-part  compound  rail  of  cast  and  wrought  iron  has  been  on  trial  for  some  time  on  a line  of 
heavy  traffic,  and  stands  the  test  of  heavy  engines  remarkably  well.  It  is  more  elastic  than  a solid  rail 
of  the  same  weight,  and  the  line  is  more  uniform  in  strength,  and  of  course  more  easy  to  the  passenger, 
the  train,  and  the  road.  It  is  apparently  so  far  a considerable  advance  towards  theoretic  perfection. 
See  Fig.  3202. 

The  next  attempt,  having  the  same  object  in  view,  is  a compound  rail  of  two  parts,  bolted  together 
with  a vertical  joint,  and  each  part  breaking  joint  with  the  opposite  part.  It  is  now  under  trial  in  a 
section  of  an  important  road,  and  is  said  to  promise  well.  See  Fig.  3203. 

The  third  plan,  which  yet  exists  only  in  model,  is  also  a compound  rail  of  two  parts,  having  a vertical 
joint,  and  breaking  joint.  But  each  part  is  concave  on  the  inner  side,  so  that  when  they  are  combined 
they  form  a tube,  in  which,  at  each  cross-joint,  is  inserted  an  iron  core  which  fills  the  tube  for  a short 
epace,  and  is  designed  to  compensate  the  loss  of  strength  occasioned  by  the  semi-cross-joint,  and  to  pre- 
vent vertical  slipping  between  the  two  parts.  'The  edges  of  this  compound  rail  are  precisely  alike, 
which  renders  it  capable  of  being  twice  reversed,  thus  possessing  two  surfaces  to  be  worn  out  in  succes- 
sion, thereby  doubling  the  durability  of  the  rail.  But  without  actual  trial  it  is  questionable  whether 
this  presumed  advantage  will  compensate  the  expense  of  the  stancheons  intended  to  support  the  rail  in 
its  proper  position.  The  form,  however,  may  readily  be  modified,  (see  Figs.  3201  and  3205.)  Fig.  3206 
shows  the  break-joint  on  the  top,  the  dotted  lines  representing  the  core. 

A fair  statement  of  the  distinguishing  properties  of  these  three  new  American  devices  will  now  be 
attempted,  leaving  a comparison  of  their  merits  to  those  competent  to  make  it,  and  to  the  test  of 
experiment. 

The  leading  property  in  the  three-part  rail  is,  that  the  cap  piece  is  the  only  part  subject  to  renewal, 
and  being  but  about  one-third  of  the  whole  weight,  must  greatly  reduce  the  cost  of  repairs.  The  means 
of  securing  the  cap-piece  against  endwise  movement  under  the  stroke  of  the  locomotive- wlie.e.ls,  is  by 


568 


REFRIGERATOR,  THE  DRY. 


3206. 


assing  keys  through  the  tongue  of  the  cap-piece  and  fitting  in  stop-notches  cut  in  the  top  of  the 
earing- rails.  A better  mode  of  security  in  this  important  matter  is  suggested  by  the  inventor,  which 
is  to  let  the  tongue  of  the  cap-rail  project  downwards  sufficiently  low  that  the  bolts  which  hold  the 
base-rails  together  may  pass  through  it  also.  This  compound  rail  loses  about  one-third  of  its  strength  at 
each  cross-joint;  but  the  objection  may  be  relieved  to  a considerable  extent  by  inserting  an  iron  core  at 
each  cross-joint  under  the  tongue  of  the  cap-piece.  This  form  of  a composite  rail  necessarily  carries 
with  it  one  great  objection  in  view  of  a perfect  surface,  as  the  latter  is  broken  at  the  end  of  each  cap- 
rail  by  a thorough  cross-joint,  presenting  a notch  for  the  wheels  to  pass  over  of  more  or  less  extent,  pro- 
ducing more  or  less  jar  at  all  those  points. 

The  two-part  H-rail,  the  second  noticed,  and  the  two-part  tubular  rail  each  equally  possess  the  ad- 
vantage of  a surface  but  partially  broken,  as  the  cross-joint  extends  only  to  the  nriddle  of  the  surface, 
leaving  the  other  part  a bearing  to  the  wheels  in  passing  over.  They  also  equally  possess  a provision 
against  end-tlirusts,  in  merely  combining  the  two  parts.  When  the  surface  is  'worn  out,  the  whole  rail  is 
lost  in  each  case.  The  two-part  H-rail  loses  half  its  strength  at  each  cross-joint ; the  tubular  rail,  in 
consequence  of  the  core,  is  of  nearly  equal  strength  in  all  parts  of  the  line. 

REFRIGERATOR,  The  Dn/,  for  Family  Use.  A.  S.  Lyman’s.  Fig.  3207  is  an  interior  view.  The  ice  is 
placed  in  the  chamber  A,  and  the  air  in  contact  with  it  being  cooled  and  condensed,  and  therefore  rendered 
heavier,  flows  down  through  the  grate  R,  and  the  descending  cold  air  flue  C,  in  the  direction  of  the  arrows. 
It  is  discharged  up  through  the  opening  in  the  hack  part  of  the  bottom  of  the  lower  drawer.  The  warmer 
air  in  this  drawer  rises  up  through  the  opening  M,  in  the  division  hoard  above  and  onwards,  finally 
passing  up  the  flue  D,  and  over  again  upon  the  ice : thus  a current  is  formed,  as  shown  by  the  arrows. 

For  the  purpose  of  showing  more  clearly  its  inter- 
nal arrangement,  the  middle  drawer  is  represented  as 
partially  open.  This  shows  the  opening  M,  through 
the  division  board  on  which  that  drawer  rests,  and 
the  opening  N,  through  the  back  end  of  the  bottom 
of  that  drawer.  This  opening  If,  is  now  closed  by 
the  division  board.  When  the  drawer  is  closed,  these 
openings  M and  N coincide,  and  the  air  flows  freely 
through  them,  as  it  is  forced  from  the  lower  to  the 
upper  drawers  by  the  superior  weight  of  the  column 
of  cold  air  in  the  flue  C.  Tbe  back  end  of  the  drawer 
cuts  off  all  connection  with  the  refrigerator,  so  that 
no  air  can  flow  out  when  it  is  open.  The  cold  air  in 
this  drawer  being  heavier  than  the  air  outside,  re- 
mains in  it,  unless  there  are  currents  in  the  room, 
which  at  most  can  only  sweep  the  air  from  this  drawer. 

Some  of  the  gases  set  free  in  refrigerators  are  ab- 
sorbed by  ice,  or  rather  by  the  pure  water  as  it  is 
dissolving  from  ice ; but  that  alone  will  not  absorb  all 
impurities,  nor  prevent  a refrigerator  from  accumu- 
lating had  odors,  as  is  known  practically  by  all  who 
have  used  refrigerators  for  a sufficient  time. 

In  order  that  the  air  may  be  rendered  perfectly 
pure,  the  charcoal  filter  S,  is  placed  in  the  back  part 
of  the  drawer,  so  that  the  air  in  its  rounds  is  constantly  being  filtered  through  the  charcoal,  and  thus 
deprived  of  all  its  impurities.  The  water  from  the  melting  ice  runs  into  the  gutter  G,  and  off  by  a trap 
pipe  not.  shown.  These  refrigerators  are  all  made  double  as  represented,  and  the  spaces,  which  are  from 
l|-  to  3 inches  wide,  filled  with  pulverized  charcoal ; this  increases  the  weight  and  cost  somewhat,  but  it 
is  essential  to  practical  success. 

REGISTERING  AND  NUMBERING  MACHINE,  Bahanovvski’s  patent.  The  several  machines 
patented  by  Mr.  Baranowski  are  all  dependent  on  one  particular  arrangement  of  wheels  or  disks,  of 
which  he  gives  the  following  preliminary  description : 


REGISTERING  AND  NUMBERING  MACHINE. 


569 


The  'wheels  or  plates  d and  b,  Fig.  3209,  turn  on  their  centres  B and  A,  and  ■when  the  tooth  e falls 
into  one  of  the  notches  in  b,  it  moves  b round  one-tenth  of  its  circumference,  as  there  are  ten  notches  in 
the  wheel  b.  The  spaces  between  the  notches  in  b are  arcs  of  the  same  circle  as  d,  so  that  b is  always 
stationary  and  fixed,  except  when  moved  by  the  tooth  in  d once  for  each  revolution  of  d.  b is  fixed  to 
a,  the  edge  of  which  is  engraved  with  the  figures  from  0 to  9,  as  shown  in  Fig.  3208.  The  cogged- 


3208.  3210. 


wheel  c is  also  fixed  to  a,  and  works  into  a cogged-wheel  of  the  same  size  A turning  on  the  same  centre 
as  d,  the  edge  of  which  is  also  shown  in  Fig.  3208.  dl  is  fixed  to  this  last  cogged-wheel  f,  and  is  of  the 
same  form  and  size  as  d.  b'  is  fixed  to  a1,  the  edges  of  which  are  shown  in  Fig.  3208,  and  is  of  the 
same  form  and  size  as  b.  Again:  Fig.  3208,  b 2 is  fixed  to  a2,  and  is  turned  by  d2,  which  is  fixed  to 
working  into  the  cogged-wheel  c1 : b~  and  d 2 are  also  of  the  same  size  and  form  as  b and  d.  a1  and  a 2 
have  also  the  figures  from  0 to  9 engraved  upon  their  edges.  All  the  plates  or  wheels  move  freely  on 
their  cylinders  or  centres,  A and  B respectively,  although  it  will  be  seen  that  no  one  of  them  can  move 
without  moving  all  the  others,  at  intervals  of  time  dependent  upon  the  number  of  notches  in  the  wheels 
b,  b1,  and  b 2,  respectively,  and  also  upon  their  respective  distances  in  the  arrangement  from  the  first 
mover  d.  The  operation  of  counting  proceeds  thus : — The  first  revolution  of  d moves  a one-tenth,  or 
puts  the  unit  in  the  place  of  the  cipher  on  a;  ten  revolutions  af  d,  or  one  of  a — that  is,  one  revolution 


3212. 


3211. 


of  d'  (tor  the  cogged-wheels  are  equal  in  size) — moves  d1  one-tenth,  or  puts  unity  in  the  place  of  the 
cipher  on  a1,  or  shows  ten  where  there  is  0,  0,  0,  in  Fig.  3208.  One  revolution  of  as1,  that  is,  one  revo- 
lution of  d",  (for  the  cogged-wheels  are  of  the  same  size,)  moves  d2  one-tenth,  or  puts  unity  in  the  place 
of  the  cipher  on  a1,  or  shows  one  hundred  where  there  is  0,  0,  0,  in  Fig.  3208,  and  so  on  till  the  arrange- 
ment shows  9,  9,  9,  where  is  0,  0,  0,  in  Fig.  3208. 

It  is  obvious  that  the  notches  in  b b 1 and  5 2 need  not  be  each  ten  in  number,  nor  need  there  he  pre- 
cisely such  three  wheels  ; but  there  may  be,  for  instance,  only  two,  (see  Figs.  3210  and  3211,)  b having 
twelve  notches,  and  b1  twenty  notches ; and  in  such  a 'case,  the  numbers  on  the  edges  of  a and  a'  might 


570 


REGULATOR,  STEAM. 


represent  shillings  and  pounds.  It  will  also  be  seen,  by  examining  the  Figs.  3208  and  3210,  that  Fig- 
3210  differs  slightly  from  Fig.  3208,  without  affecting  the  peculiar  character  of  the  arrangement.  The 
same  letters  show  the  same  parts  in  both  figures.  6,  the  unit  wheel  a,  and  d'  are  all  fixed  to  the  axle 
A,  which  turns  upon  its  centres.  In  Fig.  3208  the  corresponding  wheels  are  loose  on  A ; d'  works  into 
b\  as  in  Fig  3208 ; and  as  f is  fixed  to  b\  and  c to  a1,  and  f and  c are  of  the  same  size,  and  work  into 
each  other,  every  complete  revolution  of  a is  attended  with  a partial  revolution  of  n‘  through  a space 
measured  by  the  distance  between  any  two  notches  in  b\  Fig.  3211.  The  object  of  this  variation  ii, 
the  Figs.  3208  and  3210  is  to  bring  the  numbers  on  the  edges  of  a and  a 1 close  together. 

Again : if  d had  two  teeth,  two  notches  of  b would  be  moved  round  at  each  revolution  of  d,  and  the 
odd  or  even  numbers  on  a "would  be  presented  from  time  to  time  where  there  is  now  0,  0,  0,  Fig.  3208, 
according  as  the  arrangement  was  started  with  1 or  2.  If  started  with  1,  it  would  skip  2,  4,  6,  &c.,  and 
show  1,  3,  5,  <kc. ; if  started  with  2,  it  would  skip  1,  3,  5,  &c.,  and  show  2,  4,  6,  &c.  The  Roman  method 
of  notation,  or  any  other  signs  or  symbols  expressive  of  numbers,  can  be  substituted  for  the  Arabic 
figures,  and  can,  by  means  of  this  arrangement,  (modified  so  as  to  facilitate  and  vary  its  application,) 
be  made  to  appear  at  0,  0,  0,  Fig.  3208. 


The  manner  in  which  this  simple  and  ingenious  arrangement  is  applied  to  the  numbering,  stamping, 
and  registering  railway  tickets,  for  example,  is  thus  described : 

Fig.  3212  is  a sectional  view  of  the  side  of  a machine  of  this  description.  R R is  a cylinder  which  is 
movable  up  and  down  in  the  frame  S S.  The  top  P,  upon  which  the  blow  with  the  hand  is  to  be  given, 
is  always  kept  up  some  distance  above  S S by  a spiral  spring  upon  R R.  The  whole  of  the  machinery 
forms  part  of  R R,  and  moves  up  and  down  with  it,  except  the  rack  X,  and  the  clicks  b and  b,  which 
are  fixed  to  S S.  When  R R is  struck  down,  a tooth  of  the  wheel  c passes  beyond  b,  and  when  R R 
rises  again  to  its  place,  the  wheel  c is  turned  one  tooth  by  the  position  and  resistance  of  b ; d is  a click 
to  keep  c fixed,  as  R R descends.  The  arrangement  here  is  the  same  as  shown  in  Fig.  3208,  only  there 
are  four  wheels  with  figures  on  them  instead  of  three,  as  the  number  shown  is  any  short  of  ten  thou- 
sand. There  are  also  two  sets  of  figured  or  marked  wheels,  one  above  the  other,  and  made  to  move  at 
the  same  time  by  the  cogged-wheels  on  the  middle  axle  g.  Figs.  3212  and  3213.  On  the  lower  set  the 
numbers  project  to  be  used  as  stamps,  the  neighboring  parts  being  cut  away,  as  shown  in  the  wheels  A, 
Fig.  3212.  The  upper  set  appear  at  H,  Fig.  3214,  so  that  each  number  from  time  to  time  is  both 
stamped  and  registered.  The  segment  of  a wheel  W,  Fig.  3212,  to  which  is  fixed  an  arm  carrying  a 
small  elastic  roller  T,  works  into  the  rack  X,  and  at  each  descent  of  R R is  thereby  carried  over  the 
under  side  of  the  apparatus  Z Z ; and  this  surface  being  charged  with  printing-ink,  the  roller  T inks  each 
projecting  figure  before  it  reaches  the  paper  below. 

REGULATORS.  Clarks'  Patent  Steam,  and  Fire  Regulator.  Even  in  the  earliest  application  of  steam, 
regulators  were  contrived  for  controlling  the  draft  of  the  fire  by  the  pressure  of  the  steam  in  the 
boiler,  by  which  an  even  pressure  may  be  maintained  and  no  greater  quantity  of  fuel  consumed  than 
may  be  necessary  to  maintain  the  desired  pressure.  Figs.  3215,  3216,  illustrate  the  most  successful  and 
practical  of  these  contrivances,  patented  by  Patrick  Clark,  in  January,  1854.  Both  figures  are  in 
section.  The  construction  can  be  readily  understood.  The  steam  trom  the  boiler  is  introduced 
beneath  a vulcanized  rubber  diaphragm,  upon  which  rests  a piston  I , weighted  like  a common 
safety  valve  to  its  lever  H,  as  rod  K is  attached,  which  connects  with  the  damper  in  the  chimney 
or  flue.  Fig.  3215  shows  the  position  of  the  diaphragm  and  piston  when  the  pressure  in  the  boiler  is 


REGULATOR,  STEAM. 


571 


below  that  required  ; wben  the  pressure  exceeds  the  desired  pressure,  the  diaphragm  and  piston  are  forced 
up,  and  the  damper  begins  to  close,  till  it  attains  the 
position,  fig.  32 1G,  when  the  draft  is  entirely  shut.  1 The 
amount  of  pressure  is  controlled  by  the  sliding  weight  or 
pea  on  the  steelyard  arm  H,  as  shown  in  fig.  3216.  The 
diaphragm  is  composed  of  a cup  or  cylinder,  and  the 
patentee  claims  “ the  combination  of  a cylindrical  dia- 
phragm with  a cylinder  and  piston,”  by  which  any  de- 
sired amount  of  motion  may  he  given  from  one  inch  to 
ten  feet,  but  for  a movement  not  greater  than  an  inch, 


haying  placed  on  its  side  or  face  a set  or  series  of  dies,  each  of  which  dies  is  placed  equidistant  from  the 
axis  of  the  disk  and  from  each  other,  and  are  intended  to  be  brought,  one  to  the  place  of  feeding  and 
another  to  the  place  of  heading,  and  one  to  the  place  of  discharging,  all  at  one  and  the  same  time 
while  at  an  intermediate  and  alternate  time  the  disk  may  revolve,  and  by  such  revolution  bring  tire 
next  set  of  dies  to  the  respective  points  for  the  before-named  operations  to  be  performed,  the  disk  r u 


RIVETING  MACHINE. 


572 


maining  at  rest  for  the  purpose  of  allowing  such  operations  to  take  place,  but  cutting  off  the  wire  or  roil 
that  has  been  fed  in  as  the  disk  and  dies  revolve,  and  holding  and  conveying  it  until  the  work  is  com 
plete ; that  is,  until  the  rivet  is  headed  and  discharged,  and  so  continuing  their  operations  m succession 
so  long  as  it  shall  be  desired. 

I arrange  a table  a upon  which  I place  a disk  b having  its  several  dies  c,  and  its  outer  edge  being  in 
the  form  of  a ratchet  d , and  which  may  he  caused  to  revolve  by  the  pawl  e,  or  any  equivalent  mechanism. 
This  may  be  understood  more  clearly  by  referring  to  Fig.  3219  of  the  drawings,  this  being  a plan  oi 
these  parts,  although  the  same  parts  are  known  by  the  same  references  in  all  the  drawings.  Above  the 
table  is  the  main  shaft,  from  which  is  conveyed  motion  to  all  parts  of  the  machine.  A double  acting 
crank,  by  an  intermediate  connecting  lever  g,  acts  upon  the  pawl  e to  cause  the  disk  to  revolve  at  the 
Draper  time,  and  to  the  proper  distance  ; while  a somewhat  similar  arrangement  hears  a like  relation 
through  its  connecting-rod  h to  the  discharger  i,  worked  by  an  intermediate  lever  k.  At  the  back  of 
the  pawl  e‘  is  a spring  /,  which  keeps  the  pawl  up  to  its  work  at  all  times;  there  is,  besides,  a strong 
coiled  spring,  designed  to  keep  the  disk  in  its  place  firmly  to  the  table ; a planihg-board  n is  used 
to  plane  off  and  level  the  head  after  the  header  or  meshing  tools  have  done  their  work.  This  tool 
may  be  constructed  with  a projecting  point  or  lip  to  fit  in  a recess  in  the  face  of  the  disk,  and  this  lip 
will  cut  the  nick  in  the  head  of  the  screw.  This  planing  tool  is  placed  immediately  in  front  of  the  dis- 
charger ; behind  the  discharger  is  a stop  or  gage  piece  v placed  in  an  oblique  position,  which  serves 
the  double  purpose  of  a gage  for  the  length  of  wire  to  be  cut  off,  and  as  a clearer  to  throw  off  the  work 
from  the  disk  after  it  has  been  discharged  from  the  dies.  I will  here  add,  that  I have  intended  to  use, 
if  necessary,  a lock-up  for  my  disk ; this  would  regulate  the  disk  by  stopping  its  motion  at  one  precise 
place  at  each  stop,  in  case  it  should  fall  a trifle  short  or  overreach  the  desired  point  by  the  inaccurate 
action  of  the  pawl.  This  lock-up  may  be  applied  in  many  ways,  but  can  be  well  applied  by  attaching  a 
wide  piece  to  the  end  of  the  discharging  lever,  and  upon  it  placing  two  pins  instead  of  one;  one  of  these 
could  have  a long  bevelled  or  taper  point  to  enter  one  of  the  dies,  and  thus,  as  it  is  pushed  in  to  the  full 
size,  will  bring  the  disk  to  the  exact  place  to  receive  the  other,  (the  discharging  pin ;)  this  discharging 
pin  is  for  operating  upon  a headed  rivet  to  discharge  it. 

Fig.  3217  shows  the  action  of  the  heading  hammer.  This  hammer  has  several  hammer-faces,  to 
act  upon  as  many  rivets  or  blank  screws,  and  gives  by  this  means  as  many  blows  upon  each  one  as 
there  are  of  these  faces  ; that  is,  one  acts  upon  the  head 
of  the  rivet  in  one  die  at  one  blow,  and  the  same  one 
acts  upon  the  next  rivet  after  one  move  of  the  disk,  and 
so  on,  while  the  one  acted  upon  first  is  acted  upon  by 
the  second  hammer-face,  and  so  on  to  the  finish.  This 
hammer  is  shown  at  o,  and  is  worked  by  a connection  p 
to  an  eccentric  or  crank  g,  by  which  it  is  raised  and  low- 
ered in  its  operation,  and  presses  or  crushes  down  the 
metal,  and  forms  a head  in  the  rough  where  a flat  head 
is  to  be  formed,  whiie  the  round  head  is  produced  by  a 
hollow  or  concave  in  the  face  of  the  hammers. 

I have  used  two,  three,  or  more  of  these  hammer- 
faces  as  before  stated,  for  the  more  perfectly  pressing 
and  consolidating  the  metal,  as  it  might  not  be  per- 
fectly solid  by  a single  blow,  particularly  when  the 
metal  is  used  in  a cold  state,  as  is  generally  the  case  for  blank  screws,  while  heated  metal  is  most 
generally  used  for  rivets.  I also  use  one  hammer  having  a chisel-face,  which  may  be  pressed  into  the 
head  and  form  a nick,  when  it  is  desired  to  form  nicks. 

I provide  a tube  r through  which  the  wire  or  rod  may  be  fed  to  the  die  in  the  disk,  and  which  does 
the  further  duty  of  one-half  of  the  shears  for  the  cutting  off  the  wire  or  rod,  the  die  itself  being  the  other 
half  of  said  shears.  The  rods  or  wire  may  be  fed  in  by  hand,  or  by  any  convenient  machinery,  in  many 
ways,  such  apparatus  being  common  to  machines  for  these  purposes. 

The  operation  of  my  machine  will  be  better  understood  by  saying  that  the  machinery  is  set  in  motion 
by  power  applied  at  the  pulley  s.  We  commence  feeding  wire  or  rods  through  the  tube  into  the 
dies,  while  the  disk  is  at  rest ; next,  the  disk  of  dies  move  round  (always  in  the  same  direction)  and 
cut  off  the  wire,  which  has  been  fed  in  until  it  meets  the  herein-before-named  gage  v.  This  revolving 
action  brings  a second  die  which  is  also  fed  in,  and  so  on  until  each  die  will  be  filled  as  intended.  As 
the  dies  continue  to  fill  and  cut  off,  they  pass  on,  and  one  after  the  other  meets  tire  header  and  subse- 
quently the  discharger,  wheli  one  after  the  other  is  discharged — all  the  other  operations  being  performed 
in  the  progress,  and  between  the  feeding  and  discharging. 

RIVETING  AND  STEAM  PUNCHING  MACHINE.  By  M.  Leiiattre,  Paris.  The  principle  on 
which  the  motive  power  of  the  steam-engine  is  applied  in  the  machine  now  before  us,  is  widely  different 
from  that  which  characterizes  most  of  those  of  which  we  have  yet  treated,  and,  simple  and  obvious  as  it 
may  appear,  it  is  only  beginning  to  be  appreciated  by  mechanicians  as  we  think  it  deserves. 

In  those  machines  in  which  a rectilinear  motion,  whether  in  a horizontal  or  vertical  direction,  is  re- 
quired to  be  produced,  that  object  has  hitherto,  in  most  cases,  been  accomplished  by  n.eans  of  mechan- 
ism, more  or  less  complicated  and  expensive,  for  converting  the  rotary  motion  transmitted  through  long 
trains  of  shafts  from  the  fly-wheel  of  a steam-engine,  into  a rectilinear  motion.  In  establishments  in 
which  a great  number  of  machines,  small  as  well  as  great,  have  to  be  kept  in  motion,  we  believe  that 
no  improvement  upon  this  roundabout  method  could  be  recommended ; but  for  single  and  independent 
machines,  where  great  power  acting  in  a rectilinear  direction  is  required,  we  believe  that  the  direct 
action  of  the  steam-engine,  as  exemplified  in  the  machine  now  to  be  described,  will  supersede  the  more 
rircuitous,  expensive,  and,  on  many  accounts,  objectionable  method  hitherto  practised. 

Another  very  important  peculiarity  in  the  machine  now  under  consideration,  deserves  to  he  specially 


3 ’19. 


RIVETING  MACHINE. 


573 


noticed.  In  riveting  by  hand  the  workman  finds  it.  necessary  to  bring  the  plates  upon  which  he  is  opera 
ting  into  close  contact,  by  striking  them  with  his  hammer  while  closing  and  finishing  the  head  of  the 
rivet.  The  necessity  of  this  will  be  obvious  when  we  consider  that  the  iron  pin,  which  is  to  form  the 
rivet,  tends,  by  the  compression  to  which  it  is  subjected  by  the  blows  of  the  hammer,  to  stave  up  through- 
out its  whole  length,  as  well  as  at  the  end,  and  that,  consequently,  unless  the  plates  are  brought  into 
very  close  contact  during  the  operation,  an  obstacle  to  their  perfect  junction  is  interposed  by  the  very 
means  employed  to  bring  them  into  intimate  contact.  In  M.  Lemaitre’s  machine  this  difficulty  is  obvi- 
ated by  a very  ingenious  and  effective  contrivance  which  we  shall  now  proceed  to  describe. 

Fig.  3220  is  an  elevation.  Fig.  3221  a plan.  Fig.  3222  an  end  view,  and  Fig.  3223  a partial  section 
of  the  steam  punching  and  riveting  machine. 


The  plates  to  be  operated  upon  are,  in  this  machine,  placed  horizontallv  between  the  fixed  and  mov 
able  dies  a and  b.  The  matrix  of  the  fixed  die  a is  at  the  extremity  of  a strong  malleable-iron  stem  or 
riveting-block  A,  fixed  firmly  into  the  sole  and  foundation  of  the  machine,  anti  serving  as  the  point  o{ 
resistance  against  the  action  of  the  punch  l , the  compressing  ferule  i,  and  the  riveting-die  b.  This  last, 
which,  as  well  as  its  corresponding  fixed  die  a,  is  made  of  hard-tempered  steel,  is  fixed  into  a malleable 
iron  stock  or  tool-holder  B,  accurately  planed  and  adjusted  to  slide  in  a vertical  direction,  and  without 
lateral  motion,  in  a socket  G,  the  further  purpose  of  which  will  hereafter  be  described.  The  tool-holder 
B has  an  alternate  rectilinear  motion  of  ascent  and  descent  communicated  to  it  by  a malleable-iron  lever 
C,  which  has  its  centre  of  oscillation  at  tire  upper  extremity  of  a strong  frame  D,  cast  in  a piece  with 
the  sole  or  base  by  which  the  machine  is  fixed  to  its  foundations.  The  opposite  end  of  the  lever  C is 
connected  by  the  rod  E,  to  a piston  working  in  the  cylinder  F.  This  cylinder,  which  is  open  above,  and 
close  beneath  the  piston,  is  furnished  with  a valve  inclosed  in  the  vaive-box  c,  and  by  this  valve  high- 
pressure  steam  is  alternately  admitted  under  the  piston,  through  the  steam-pipe  g,  and  allowed  to  es- 


cape through  the  exhaust-pipe  h.  The  valve  is  raised  or  depressed  by  means  of  the  combination  oi 
rods  and  levers  def,  which  are  disposed  so  as  to  place  the  machine  within  the  command  of  the  work- 
man who  superintends  the  operation.  The  mechanism  by  which  the  plates  are  compressed  during  the 
process  of  riveting  consists  of  a cylindrical  steel  ferule  i,  Fig.  3223,  through  the  centre  of  which  the  riv- 
eting-die b passes,  and  which  again  is  fitted  into  a strong  cast-iron  socket  G,  sliding  exactly  and  without 
play,  between  two  planed  guides  H H.  The  socket  G is  made  hollow  for  the  purpose  of  forming  the 
guide  to  the  tool-holder  B,  as  we  have  already  mentioned,  and  receives  a motion  similar  to,  though  in- 
dependent of,  the  latter,  from  the  two  malleable-iron  levers  1 1,  which  have  their  centre  of  oscillation  at 
the  same  point  as  the  lever  0,  and  are  connected  at  their  opposite  extremities  by  the  rod  J to  a piston 
contained  within  the  cylinder  K.  This  latter  cylinder  is  of  smaller  diameter  than  that  used  for  riveting 
and  like  it,  is  provided  with  a valve  c for  the  admission  and  escape  of  steam.  The  rods  and  levers  d, 
e /',  for  opening  and  shutting  this  valve,  are  arranged  in  the  same  way  as  those  already  described. 

This  machine  is  adapted  for  punching  as  well  as  riveting  iron  plates.  For  this  purpose  two  strong 
parallel  guides  M M are  fixed  to  the  movable  frame  which  carries  the  compressing  ferule*.  To  the 
centre  of  these  guides  a socket  or  tool-holder  L is  attached  by  means  of  a pin  m passing  through  its 
upper  extremity  and  the  guides.  The  punch  l is  fitted  to  the  opposite  end  of  the  socket  L,  and  its  po- 


574 


RIVETING  MACHINE. 


sition,  when  brought  into  operation  by  turning  it  downwards  upon  its  pivot  m and  securing  it  between 
the  guides  M M,  coincides  exactly  with  that  of  the  matrix  a',  upon  the  extremity  of  the  riveting-block  A 
The  matrix  a!  is  sunk  into  a circular  recess  cast  upon  the  riveting-block,  and  for  the  sake  of  accurate 
adjustment,  is  acted  upon  by  three  small  screws  passing  through  the  sides  of  the  recess.  Under  these 
circumstances,  it  is  obvious  that  the  operation  of  punching  will  be  performed  by  the  same  mechanism, 
by  which,  in  riveting,  the  compressing  ferule  is  made  to  descend.  When  not  required  to  be  used,  the 
punch  and  its  socket  are  turned  into  the  position  represented  in  Figs.  3222  and  3223. 

Action  of  the  machine. — The  plates  to  be  united  by  riveting,  having  been  previously  punched,  are 
placed  together,  as  shown  in  the  drawings,  upon  the  horizontal  stem  or  riveting-block  A.  The  heated 
rivet  is  then  placed  into  its  appropriate  hole,  with  the  head  inside,  and  the  plates  are  shifted  till  the 
rivet-head  falls  into  the  matrix  a.  The  attendant  workman  by  pulling  down  the  handle/'  depresses  the 
valve  inclosed  in  the  steam-chest  c,  and  thus  opens  a communication  through  the  pipe  g,  between  the 
steam  in  the  boiler  and  the  under  side  of  the  piston  working  in  the  cylinder  K.  The  piston  ascends,  and 
its  motion  being  communicated  through  the  rod  J to  the  level's  1 1,  causes  the  ferule  i to  descend,  and 
compress  the  plates  firmly  together.  The  same  workman  then,  by  pulling  down  the  handle/,  opens 
the  valve  of  the  large  cylinder  F,  taking  care  that  the  pressure  is  still  kept  upon  the  plates.  This 
causes  the  tool-holder  B,  and  riveting-die  b,  to  descend,  and  thus  the  rivet  is  finished.  The  valve  of  the 
cylinder  F is  then  first  moved  so  as  to  shut  the  communication  between  the  boiler  and  the  piston,  and 
allow  the  steam  to  escape  through  the  pipe  li.  The  weight  of  the  rod  E and  lever  C causes  the  piston 
to  descend  and  the  die  b to  rise.  The  handle  f is  then  released,  and  by  a similar  process  the  ferule  i 
rises  to  admit  of  the  plates  being  shifted  for  the  fixing  of  the  next  rivet. 

The  action  of  the  machine  in  punching  is  obviously  so  similar  to  that  already  explained  as  to  require 
no  further  description.  As  it  is  of  importance  that  the  rivet-holes  should  be  pierced  with  as  little  delay 
as  possible,  at  the  same  distance  from  each  other,  and  in  the  same  line,  M.  Lemaitre  makes  use  of  a 
marker  which  serves  as  a guide  to  the  workman  in  placing  the  plates  under  the  action  of  the  machine. 
This  contrivance  consists  of  a small  arm  n formed  into  a socket,  so  as  to  admit  of  being  adjusted  and 
fixed  upon  the  axis  o,  which  has  its  bearings  in  one  of  the  cheeks  or  guides  M.  Into  the  arm  n is  fixed 
a small  piece  of  sheet-iron,  shaped  at  the  outer  extremity  into  a circle,  the  diameter  of  which  is  equal  to 
that  of  the  punch,  and  its  centre,  when  turned  towards  the  punch,  coinciding  with  it.  In  making  use  of 
this  contrivance  the  handle  p of  the  axis  o is  turned  round  till  the  extremity  of  the  arm  n is  brought 
directly  under  the  punch.  The  plates  are  then  shifted  so  that  the  place  where  the  hole  is  to  be  pierced 
is  covered  by  the  circular  end  of  the  sheet-iron  marker,  and  thus  the  accuracy  of  the  work  is  insured. 

Figs.  3224  and  3225  represent  a very  ingenious  and  most  useful  contrivance  which  M.  Lemaitre  has 
adapted  to  this  machine,  for  the  purpose  of  riveting  long  and  narrow  tubes  from  the  interior,  a problem 
which,  at  first  sight,  is  of  very  difficult  solution.  The  stem  or  riveting-block  N is  made  hollow  through 
out  its  whole  length,  and  incloses  a long  rod  S,  terminated  by  a steel  wedge  r.  This  wedge  acts  upon 
the  movable  matrix  t,  which  passes  through  the  upper  side  of  the  riveting-block  A,  in  such  a way  as  to 
cause  it  to  rise  or  fall  according  as  the  rod  S is  pushed  in  or  drawn  out.  The  die  u and  its  holder  or 
stock  O are  of  the  same  form,  and  are  connected  with  the  machine  in  the  same  manner  as  those  already 
described.  In  using  this  form  of  the  machine,  the  rivets  are  inserted  from  the  outside  of  the  tube,  the 
dies  t and  u receive  simultaneously  a motion  in  opposite  directions,  the  lower  one  t being  made  to  rise 
by  pushing  in  the  rod  S,  and  the  upper  one  u descending  by  the  action  of  the  steam-piston  upon  the 
lever,  and  thus  the  rivet  is  formed. 

M.  Lemaitre  has  been  enabled,  by  this  contrivance,  to  rivet  tubes  of  considerable  length  and  small 
diameter ; a work  which  it  was  impossible  to  perform  either  by  hand  or  by  any  machine  formerly  in 
existence. 

Literal  References. 

A,  the  malleable-iron  stem  or  riveting-block. 

B,  the  stock  or  tool-holder  into  which  is  fixed  the  riveting-die  6,  and  which  is  made  to  move  in  a ver- 
tical direction  by  the  great  lever 

C,  by  which  the  pressure  necessary  for  forming  the  rivet-head  is  conveyed  from  the  steam-piston. 

I),  the  frame  and  sole  or  base  of  the  machine. 

E,  the  connecting-rod  between  the  piston  inclosed  within  the  cylinder  F and  the  lever  C. 

F,  the  steam-cylinder  in  which  the  power  required  for  forming  the  rivet-head  is  generated. 

G,  a socket  or  tool-holder,  to  the  lower  end  of  which  is  fixed  the  compressing  ferule  i,  and  which 
moves  vertically  between  the  two  planed  guides 

H H,  bolted  firmly  to  the  fixed  frame  of  the  machine. 

1 1,  a double  malleable-iron  lever,  by  which  the  pressure  necessary  for  keeping  the  plates  firmly  to 
gether  is  conveyed  from  the  piston  inclosed  within  the  cylinder  K,  to  the  compressing  ferule  i. 

J,  the  connecting-rod  between  the  piston  inclosed  within  the  cylinder  K and  the  lever  I. 

K,  the  steam-cylinder  in  which  the  power  required  for  compressing  the  plates  is  generated. 

L,  the  stock  or  socket  into  which  the  punch  l is  fitted. 

M M,  the  guides  for  confining  the  tool-holder  L,  laterally. 

a,  the  matrix  or  die  on  the  end  of  the  riveting-block. 

a , the  matrix  of  the  punching-tool, 

b,  the  cylindrical  stock  into  which  the  riveting-die  is  fixed,  and  which  works  up  through  the  compres 
«ing  ferule  i. 

c,  the  valve-box  fixed  to  the  lower  extremity  of  the  steam-cylinder  F. 

c,  a similar  valve-box  fixed  to  the  lower  extremity  of  the  cylinder  K. 

d ef  rods  and  levers  for  working  the  valve  attached  to  the  cylinder  F 

d'ef,  similar  rods  and  levers  for  working  the  valve  attached  to  the  cylinder  K. 

ci  h,  pipes  for  the  admission  and  escape  of  steam  into  and  from  the  valve-box  c. 


RIVETING  MACHINE. 


575 


g’  It,  pipes  for  the  admission  and  escape  of  steam  into  and  from  the  valve-box  c\ 

i,  the  compressing  ferule. 

k,  a strengthening  piece  by  which  the  foundations,  frame,  and  riveting-block  are  held  together. 

!>  the  puncking-tool. 

m,  a joint  by  which  the  punch-holder  L may  be  turned  upwards  or  downwards,  as  required. 

n,  a small  sheet-iron  arm  which  may  be  used  as  a marker. 

o,  the  axis  upon  which  this  marker  is  fixed. 

p , a handle  by  which  it  may  be  turned  out  or  in  as  required, 

N,  the  hollow  riveting-block  used  for  riveting  tubes  internally. 

O,  the  stock  or  die-holder  used  in  the  same  operation. 

S,  a long  rod  terminated  in  a wedge  r,  by  which  the  riveting-die  t is  made  to  ascend. 

r,  a steel  wedge  moving  in  the  interior  of  the  riveting-block  N. 

t,  the  internal  riveting-die  moving  upwards  and  downwards  by  the  action  of  the  wedge  r. 

u,  the  external  riveting-die  moving  upwards  and  downwards  by  the  action  of  the  steam. 

Ill  VET  [MG  MACHINE — By  William  Fairbairn  & Co.,  Manchester.  In  the  manufacture  of  steam- 
engine  boilers,  however  varied  and  important  the  improvements  which  have,  from  time  to  time,  been 
effected  in  the  form  and  arrangement  of  then-  parts,  no  attempt  has,  until  a very  recent  period,  beer 
made  to  facilitate  the  means  of  their  construction,  or,  by  the  introduction  of  machinery,  to  supersede 
the  necessity  for  manual  labor.  It  is  true,  the  punching  and  shearing  machine  has,  under  various  mod 
ifications,  been  long  in  use,  but  it  is  only  within  the  last  few  years  that  machines  for  bending  plates, 
for  making  rivets,  and  still  more  recently  for  riveting,  have  been  introduced. 

For  this  last  purpose,  a variety  of  ingenious  and  effective  combinations  have  been  proposed,  and  al- 
though, as  yet,  none  of  them  has  come  into  very  general  use  among  boiler-makers,  there  can  be  little 
doubt  that  the  laborious  and  expensi  ve  process  of  riveting  by  hand  will  be  superseded  by  some  form  of 
this  machine.  The  first  idea  of  the  riveting  machine  is  due  to  Mr.  Fairbairn,  of  Manchester,  who,  in 
1838,  patented  a machine  in  many  respects  similar  to  the  common  punching  machine,  but  having  the 
great  lever  of  such  a form  as  to  communicate  a horizontal  motion  to  the  dies  or  tool  for  forming  the 
head  of  the  rivet.  The  machine  represented  is  a modification  which  Mr.  Fairbairn  has  since  made, 
in  which  he  has  introduced  several  improvements,  and  remedied  several  defects  to  which  the  former 
was  subject. 


The  principle  of  Mr.  Fairbairn’s  machine  consists  in  its  performing  by  almost  instantaneous  pressure, 
what  could  formerly  only  be  done  by  a long  series  of  impacts.  Every  mechanic  is  aware  that  the  oper- 
ation of  riveting,  in  all  ordinary  cases,  requires  the  services  of  three  men,  one  to  hold  a hammer  or  other 
mass  of  iron  inside  the  boiler,  against  the  head  of  the  rivet,  while  the  other  two  beat  the  protruding  end 
into  the  conical  form  given  to  the  rivet  on  the  outside  of  the  boiler.  For  this  operation  very  expert  and 
skilful  workmen  are  required,  that  the  rivets  may  be  fixed  soundly  and  firmly  without  injury  to  the 
plates,  and  that  all  unnecessary  hammering,  which  has  only  the  effect  of  weakening  the  rivets,  may  be 
avoided.  By  means  of  the  riveting  machine,  the  process  is  accomplished  with  much  greater  rapidity 
and  regularity,  without  producing  the  stunning  and  disagreeable  noise  unavoidable  in  hand  riveting. 
Besides  these  advantages,  the  operation  being,  as  we  have  before  said,  performed  almost  instantane- 
ously by  the  machine,  the  danger  of  injuring  the  rivets  by  hammering  them  when  too  cold  is  avoided 
and  the  hemispherical,  which  we  think  greatly  preferable  to  the  conical  form,  is  more  easily  impressed 
upon  them. 

Fig.  3127  represents  an  elevation,  and  Fig.  3126  a plan  of  Mr.  Fairbairn’s  machine  in  its  most  im- 
proved form,  and  as  it  is  now  constructed  by  him.  It  possesses  the  advantage  over  his  first  proposed 
torm,  of  being  more  compact  and  portable,  and  is  capable  of  more  extensive  application,  being  adapted 
to  rivet  angle-iron,  and  finish  the  corners  of  boilers  and  cisterns. 

The  sole  or  base  of  the  machine  A is  made  of  cast-iron,  and  mounted  upon  wheels  adapted  to  rails, 
.or  the  convenience  of  shifting  it  to  any  required  place.  The  framing  B B is  cast  in  a piece  with  the 


576 


RIVETING  MACHINERY. 


sole  A,  and  consists  of  an  oblong  box,  open  at  the  top,  and  furnished  with  bearings  for  the  movable 
parts  of  the  machine ; C,  a strong  upright  stem  of  malleable  iron,  fitted  firmly  into  the  base  A,  which 
is  secured  against  the  effect  of  undue  strains,  arising  from  the  dies  coming  in  contact  with  a cold  rivet 
or  other  hard  substance,  by  a malleable-iron  strap  D passing  round  its  upper  edge,  and  secured  by  nuts 
at  a a.  The  stem  or  riveting-block  G is  the  point  of  resistance  to  the  action  of  the  dies,  and  against  it  is 
placed  that  part  of  the  boiler  which  is  to  undergo  the  process  of  riveting.  It  is  made  of  malleable-iron, 
in  order  that  it  may  possess  a certain  amount  of  elasticity,  which  is  necessary  to  the  prevention  of  such 
accidents  as  we  have  just  alluded  to.  Its  upper  extremity  is  formed  into  an  oblong  block  k,  and  in  this 
the  matrices  for  receiving  the  dies  are  placed.  - 

The  moving  parts  of  the  machine  consist  of  a shaft  carrying  the  fast  and  loose  pulleys  E and  F, 
driven  by  the  belt  b.  To  give  the  requisite  power  and  velocity  to  the  machine,  a pinion  G is  fixed 
upon  this  shaft,  and  works  into  a wheel  I,  keyed  upon  another  and  stronger  shaft  situated  directly  over 
the  former.  On  the  pinion-shaft  is  placed  the  fly-wheel  H,  for  giving  a uniform  motion  to  the  working 
parts  of  the  machine,  and  at  each  revolution  of  the  wheel  I the  machine  performs  one  stroke.  The 
ratio  of  the  pinion  G to  the  wheel  I is  as  1 to  6 ; consequently,  when  the  pulleys  are  driven  at  the  rate 
of  42  revolutions  per  minute,  the  machine  performs  7 strokes  per  minute,  and  this  is  found  to  be  the 
most  suitable  velocity.  On  the  axis  of  the  wheel  I is  fixed  a cam  c,  of  the  form  denoted  by  the  dotted 
lines  in  Fig.  3127.  This  cam,  in  its  revolution,  alternately  raises  and  suffers  to  fall  by  its  own  weight 
the  friction-pulley  d,  which  runs  loose  upon  the  centre  pivot  of  a knee-joint  composed  of  the  arms  e e 
and  ff.  The  arms  ee  working  upon  a fixed  centre,  as  shown  in  the  plan,  the  elevation  of  the  pulley  d 
by  the  cone  c necessarily  impresses  a horizontal  motion  upon  the  corresponding  extremities  of  the  arms 
//'.  These  extremities  are  connected  by  a joint  to  the  slide  g,  the  motion  of  which  is  guided  into  a per- 
fectly rectilinear  and  horizontal  direction  by  the  dovetail  pieces  h h,  planed  true  and  screwed  firmly  to 
the  frame  of  the  machine.  The  sliding  piece  g is  furnished  at  its  outer  extremity  with  three  holes  or 
matrices  for  receiving  the  die  i,  which  forms  the  head  of  the  rivet.  These  matrices  are  so  placed  that 
their  centres  coincide  exactly,  both  in  the  horizontal  and  vertical  planes,  with  the  centres  of  similar  ones 
in  the  upper  extremity  of  the  stem  or  riveting-block  c,  already  described.  Into  these  latter  is  fitted  the 
die?',  against  which  the  head  of  the  rivet  is  placed  during  the  process.  The  centre  matrix  in  which  the 
dies  are  represented  in  the  figure  is  used  for  riveting  every  description  of  flat  or  circular  work,  while 
those  at  each  side  are  required  for  finishing  the  corners  of  the  boilers..  Thus  the  machine  is  adapted 
for  riveting  vessels  of  almost  every  shape  within  the  given  depth. 

Action  of  the  machine. — The  plates  to  be  riveted  together,  having  been  previously  punched  in  the 
usual  way,  are  suspended  by  a block  and  chain,  as  shown  in  Fig.  3127.  The  heated  rivet  is  then  in- 
serted into  its  appropriate  hole,  and  the  attendant  workman  shifts  the  plates,  so  that  the  head  of  the 
rivet  falls  into  the  recess  on  the  point  of  the  diey.  The  machine  is  then  put  in  motion  by  changing  the 
position  of  the  strap  b from  the  loose  to  the  fixed  pulley.  This  motion  is  transmitted  by  the  mechanisn 
above  described,  to  the  sliding  tool-holder  g,  and  its  projecting-die  i,  in  its  advance,  forms  the  head  and 
finishes  the  rivet.  The  velocity  of  the  machine  is  so  calculated  as  to  allow  time  between  each  stroke 
for  the  insertion  of  another  rivet  and  the  readjustment  of  the  plates,  and  thus  the  work  proceeds  with- 
out interruption. 

It  is  stated  by  Mr.  Fairbairn  that,  with  two  men  and  two  boys  attending  to  the  plates  and  rivets,  his 
machine  can  fix,  in  the  firmest  manner,  eight  rivets  of  three-quarters  of  an  inch  diameter  in  a minute, 
whereas,  by  the  common  process  of  hand  riveting,  three  men  and  a boy  can  only  rivet  up  40  per  hour. 
Thus  the  quantity  of  work  done  in  the  same  time  in  the  two  cases  is  in  the  proportion  of  480  to  40,  or 
as  12  to  1,  exclusive  of  the  saving  of  one  man’s  labor. 

RIVETING  MACHINERY— GARFORTH’S  PATENT,  for  riveting  metallic  plates,  for  the  con- 
struction of  boilers,  and  other  purposes. 

These  improvements  in  machinery  or  apparatus  for  connecting  metallic  plates  for  the  construction 
of  boilers,  consist  in  the  direct  application  of  the  expansive  force  of  steam  to  the  dies  for  riveting 
such  plates  together,  and  in  an  arrangement  of  machinery  whereby  such  force  is  brought  into 
action. 


3228.  3229. 


Fig.  3228  represents  a plan  or  horizontal  view  of  an  arrangement  of  machinery  or  apparatus  designed 
for  connecting  or  riveting  metallic  plates  for  the  construction  of  steam-boilers ; Fig.  3329  is  a side  view ; 
and  Fig.  3230  a section,  taken  longitudinally  through  about  the  centre  of  the  apparatus,  a a is  the 


ROLLING  MACHINE. 


577 


frame-work  for  supporting  the  steam-cylinder  b b,  in  ■which  a steam-tight  metallic  or  other  piston  c « 
works ; this  piston  c c is  mounted  upon  the  rod  dd which  passes  out  through  stuffing-boxes  e e at  each 
end  of  the  cylinder  b b;  in  the  end  a*  of  the  piston-rod  the  die  /is  fixed,  the  other  die  g being  mounted 
in  the  pillar  h,  which  is  fast  to  the  frame-work.  Steam  being  admitted  through  the  entrance  or  feed- 
pipe i,  it  passes  onwards  through  a common  slide  or  other  valve  k,  to  the  cylinder ; and  after  having 
performed  its  office,  is  allowed  to  pass  out  through  'the  pipe  l.  The  slide-valve  k is  worked  by  hand, 
by  means  of  the  lever  m,  so  as  to  admit  the  steam  on  either  side  of  the  piston  as  required. 

The  operation  of  the  apparatus  is  as  follows : Steam  of  a sufficient  pressure  being  admitted  (by 
means  of  the  slide-valve  k)  at  the  back,  or  as  it  appears  in  Fig.  3230  at  the  left-hand  side  of  the  piston 
cc,  that  piston  will  be  forced,  together  with  the  piston-rod  dd*,  in  the  direction  of  the  arrow,  and  form 
the  ends  of  the  rivet  n,  between  the  two  dies/ and  17;  thus  firmly  connecting  the  plates  0 and p,  and 
thereby  producing  a perfectly  steam,  air,  or  water  tight  joint. 

The  head  of  the  rivet  is  formed  at  one  or  more  blows,  as  required;  the  intensity  of  the  blow  depend- 
ing upon  the  area  of  the  piston,  the  length  of  the  stroke,  and  the  pressure  of  the  steam  employed.  The 
valve  k is  then  reversed,  to  admit  the  steam  in  front  of  the  cylinder ; which  movement  will  withdraw 
the  die/,  when  another  rivet  may  be  put  in,  and  the  operation  proceeds  as  before. 

The  patentee  remarks  that  he  does  not  intend  to  confine  himself  to  the  use  of  steam  alone  for  such 
purposes,  as  the  direct  pressure  of  water,  air,  or  other  elastic  medium  may  be  similarly  employed, 
without  departing  from  the  principle  of  his  invention.  He  states  that  he  does  not  claim  the  exclusive 
use  of  the  several  parts  of  the  above-mentioned  apparatus,  when  taken  separately,  but  only  when  em- 
ployed for  the  purpose  of  his  invention,  which  consists  in  the  riveting  of  metallic  plates  by  dies  driven 
by  the  power  of  steam,  water,  &c. 


3231. 


ROLLING  MACHINE,  for  rolling  iron,  specially  intended  for  railroad  bars  and  locomotive  tires a 

new  method,  invented  by  Horatio  Ames,  of  Falls  Village,  Connecticut. 

We  are  induced  to  publish  the  entire  specification  and  drawings  of  this  invention,  not  only  on  account 
of  the  value  and  merit  which  it  presents,  but  because  of  the  deep  interest  which  must  be  felt  in  all  such 
improvements  by  those  who  are  engaged  in  the  manufacture  of  iron,  and  in  railroads.  The  great  rival- 
ship  now  going  on  in  this  country  and  in  England,  in  the  manufacture  of  iron,  renders  every  improve- 
ment which  looks  either  to  the  reduction  of  the  cost  of  manufacture,  or  to  the  amelioration  of  the  quality 
of  the  iion,  of  the  highest  importance.  And  as  the  cost  of  repairs  on  railroads  arises  in  a great  measure 
fiom  the  wear  of  railroad  bars  and  locomotive  tires,  by  exfoliation  and  splitting,  any  invention  which 
pi  onuses  to  avoid  this  evil  must  be  looked  upon  with  interest.  The  invention  in  question  has  already 
excited  a deep  interest  in  England,  where  the  inventor  has  secured  it  by  patent. 

Fig.  3-31  is  a plan  of  the  machine;  Fig.  3232,  a side  elevation;  Fig.  3233,  a longitudinal  vertical 
section  taken  at  the  line  X X of  Fig.  3231  ; and  Fig.  3234,  a like  section,  taken  at  the  line  ZZ  of  the 
same  figure.  The  same  letters  indicate  like  parts  in  all  the  figures. 

In  the  manufacture  of  iron,  either  by  rolling  or  hammering,  the  fibres  are  all  drawn  longitudinally, 
which,  foi  the  rails  of  railroads,  for  the  tires  of  railroad  wheels,  and  for  a variety  of  other  purposes, 
renders  it  liable  to  break  off  in  thin  leaves  or  scales,  or  to  split  lengthwise — this  state  of  things  bein°- 
very  common  in  the  two  instances  specified.  The  object  of  my  invention  is  so  to  treat  the  iron,  either 
m the  original  manufacture  thereof,  or  afterwards,  as  to  avoid  this  defect,  and  thereby  render  the  iron 
tor  these  purposes  more  durable,  by  laying  the  fibres  in  such  form  and  direction  as  to  prevent  it  from 
scaling  off  or  splitting.  And  my  invention  consists  in  twisting  the  iron  in,  or  before,  or  after,  the  opera- 
lion  ot  10  ing  01  hammering,  so  that  the  fibres  shall  wind  around  one  another,  in  a manner  somewhat 
similar  to  the  fibres  of  hemp  in  a twisted  rope  or  strand. 

. Aud  tl>e  second  part  of  my  invention  relates  to  the  machinery  by  which  I carry  into  effect  my 
improved  process,  and  consists  in  combining  two  or  more  sets  of  rollers,  one  or  both  of  which  are  to  be 
iaw  10  er^  and  one  set  turning  in  the  usual  permanent  bearings,  and  the  other  set  or  sets  working  in 
a frame  or  chuck  that  rotates  on  an  axis  at  right  angles  to  the  axis  of  the  rollers,  to  twist  the  bar  oi 
iron  between  the  two  sets  of  rollers. 

Vol.  II. — 37 


578 


ROLLING  MACHINE. 


To  enable  any  one  skilled  in  the  art  to  apply  my  improved  process  of  treating  iron,  and  to  construct 
and  use  the  machine  which  I have  invented  therefor,  I will  describe  the  mode  of  procedure  which  I 
have  essayed,  as  well  as  the  manner  of  constructing  and  raising  the  machine  therefor.  The  bloom  of 
iron,  or  a bar  previously  formed,  is  taken  while  in  a heated  state,  and  twisted  while  undergoing  the 
operation  of  hammering,  which  may  be  done  by  securing  one  end  of  the  bloom  or  bar  in  a clamp  and 
rotating  it  while  the  hammer  rests  on  the  other  end  ; or  by  securing  the  two  ends  in  separate  clamps 
and  twisting  one  of  them,  or  both,  in  opposite  directions,  until  the  required  twist  has  been  given,  and 
then  subjecting  it  to  the  operation  of  hammering.  But  when  the  bar  is  to  be  drawn  by  rolling,  the  bar 
is  to  undergo  the  operation  of  twisting  while  passing  between  the  rollers,  or  after  it  has  passed  between 
one  set,  and  before  it  passes  between  the  second  set;  and  when  it  is  twisted  on  its  way  to  the  rollers, 
one  end  of  the  bar  may  be  secured  to  a clamp,  which  is  to  be  rotated  as  the  bar  passes  between  the 
draw-rollers. 

3232. 


As  the  bars  thus  prepared  are,  in  most  instances,  to  be  reworked  to  receive  the  required  form  or 
forms,  according  to  the  purposes  which  they  are  to  be  applied  to,  it  will  be  evident  that  they  may  be 
twisted  as  they  pass  from  the  hammer  or  the  rollers,  instead  of  giving  the  twist  before  the  hammering 
or  rolling ; and  to  effect  this,  the  end  of  the  bar  may  be  clamped  as  it  leaves  the  hammer  or  rollers,  and 
the  required  twist  given ; but  it  is  better  to  give  the  twist  before  the  iron  has  undergone  the  operation 
of  rolling  or  hammering,  as  it  is  then  more  highly  heated,  and  the  fibres  will  not  be  so  severely  strained 
as  they  would  be  after  the  metal  has  been  partly  cooled. 

When  iron  has  been  treated  and  worked  according  to  this  process,  the  fibres,  instead  of  running  in  the 
bar  longitudinally,  in  straight  lines,  will  run  in  the  direction  of  a helix,  gradually  approaching  to  a 
straight  line  from  the  circumference  to  the  axis  of  the  bar,  so  that  when  used  for  making  tires,  or  for 
other  analogous  purposes,  the  bar  will  be  prevented  from  splitting  along  its  length  by  the  tenacity  of 
tire  fibres,  which  cross  the  bar  in  the  direction  of  a helix,  instead  of  the  mere  adhesion  of  the  fibres 
together ; and  when  used  for  the  rails  of  railroads,  or  similar  purposes,  none  of  the  fibres  can  be  sepa- 
rated from  the  mass  longitudinally,  as  heretofore,  nor  can  the  iron  be  stripped  off  in  scales  until  they 
have  been  cut  off  on  each  side,  for,  by  their  direction,  they  pass  diagonally  from  one  side,  over  the  sur- 
face, and  down  the  other  side,  whereby  they  are  completely  tied  together. 

3233. 


Of  the  machinery  for  working  iron  in  accordance  with  the  foregoing  process. — In  the  accompanying 
drawings  a represents  a frame  properly  adapted  to  the  purpose,  and  h h two  grooved  rollers,  such  as  are 
used  in  rolling-mills  for  rolling  bars  of  iron — the  groove  in  each  being  semicircular,  or  nearly  so,  that 
the  two  together  may  form  a cylindrical  bar.  These  two  rollers  are  placed  one  above  the  other,  with 
their  journals  in  appropriate  boxes  in  the  two  standards  c c.  The  shaft  of  the  lower  roller  extends  out 
beyond  one  of  the  standards,  and  is  provided  with  a level  cog-wheel  d,  which  mashes  into  a level 
pinion  e on  the  main  driving-shaft/,  which  turns  the  lower  roller  to  feed  in  the  bar  of  iron  g — the  upper 
roller  being  carried  by  the  motion  of  the  lower  one.  Just  back  of  the  first  set  of  rollers  above  described, 
there  is  another  pair  nn,  similar  to  the  first,  except  that  the  grooves  in  them  are  smaller,  to  draw  the 
iron  slightly,  after  passing  the  first  set — they  are  mounted  in  a hollow  chuck  or  frame  i on  the  forward 
end  of  a hollow  shaft  or  mandrel  j that  has  its  bearings  in  two  standards  k k,  and  which  is  provided 
with  a cogged  pinion  l,  the  teeth  of  which  engage  with  a cog-wheel  m on  the  main-shaft,  by  which  the 
second  set  of  rollers  are  made  to  rotate  at  right  angles  to  their  axes,  and  on  an  imaginary  line  passing 
through  the  bight  of  the  two  sets  of  rollers,  and  in  the  centre  of  the  two  holes  formed  by  the  grooves 
ui  the  rollers  at  the  bight  of  each  set,  the  axis  of  the  hollow  shaft  or  mandrel  being  in  this  imaginary 


ROPES,  STIFFNESS  OF. 


579 


line.  Back  of  the  clutch,  and  attached  to  the  front  face  of  the  forward  standard  k,  there  is  a wheel  n , 
the  cogs  of  which  mash  into  the  cogs  of  two  pinions  o o on  two  short  arbors  pp , one  on  each  of  the  two 
opposite  sides  of  the  chuck,  the  other  end  of  these  short  arbors  being  provided  each  with  a short  screw  q, 
the  threads  of  which  engage  with  the  cogs  of  two  pinions  r r,  one  on  the  end  of  each  of  the  rollers  of 
the  second  set,  so  that  the  cog-wheel  n,  being  permanently  attached  to  the  standard  when  the  hollow 
shaft  with  its  chuck,  and  the  second  set  of  rollers,  is  turned,  the  two  cogged  pinions  o o travel  about  this 
wheel,  which  turns  the  arbors  to  which  they  are  attached,  in  the  direction  of  the  reverse  of  the  rotation 
of  the  chuck,  and  the  threads  of  the  screw  in  turn  engaging  with  the  cogs  of  the  pinions  on  the  shafts 
of  the  second  set  of  rollers  causes  these  to  rotate  on  their  axes,  and  in  the  same  direction  with  the  first 
set,  and  with  a velocity,  relatively  to  the  rotation  of  the  first  set,  proportioned  to  the  amount  of  drawing 
action  which  they  are  intended  to  exert  on  the  bar  that  is  to  pass  between. 

In  this  way  it  will  be  obvious  that  when  the  machine  is  put  in  motion,  and  a bar  of  iron  fed  in,  it  will 
pass  between  the  first  pair  of  rollers  and  be  partly  drawn,  and  then  pass  between  the  second  pair, 
which  having  two  motions,  one  on  their  axis  and  another  at  right  angles  thereto,  and  on  the  axis  of 
tfc«  bar  of  iron,  it  (the  bar)  will  in  consequence  be  twisted  between  the  two  pairs  of  rollers,  and  also 
d;  awu  by  them,  and  the  fibres  compressed. 


3235. 


From  the  foregoing  it  will  be  obvious  that  the  extent  of  drawing  action  of  either  or  both  sets  of 
Ira  wing-rollers  can  be  regulated  at  pleasure,  by  simply  varying  the  size  of  the  grooves  and  relative 
motions  of  the  draw-rollers  on  their  axes,  and  their  rotation  on  the  axis  of  the  bar  of  iron. 

It  will  be  equally  obvious  that  the  number  of  draw-rollers  can  be  increased  -without  changing  the 
principle  of  my  invention.  It  is  to  be  understood  that  the  iron,  when  subjected  to  the  compound  action 
of  drawing  and  twisting,  is  to  be  in  a heated  state,  such  as  practised  by  and  known  to  iron-masters  in 
the  manufacture  of  iron. 

Claim. — What  I claim  as  my  invention  is,  first,  the  method  herein  described  of  treating  iron  to 
increase  its  toughness  or  durability  for  certain  purposes — such  as  railroad  bars  and  tires,  &c. — by  sub- 
jecting it,  in  a highly  heated  state,  to  the  compound  operation  of  drawing  and  twisting,  substantially  as 
herein  described. 

I also  claim  in  the  machinery  above  described,  giving  to  one  set  of  rollers  the  rotary  motion  on  their 
axes,  and  a rotary  motion  at  right  angles  thereto,  on  the  axis  of  the  bar  of  iron,  when  this  is  combined 
with  another  pair  of  rollers  that  have  simply  a rotary  motion  on  their  axes,  whereby  the  bar  of  iron,  in 
a highly  heated  state,  is  drawn  and  twisted. 

HOPES,  STIFFNESS  OF,  or  the  resistance  of  ropes  to  bending  upon  a circular  arc.  The  experi- 
ments upon  which  the  rules  and  table  following  are  founded  were  made  by  Coulomb,  with  an  appara- 
tus the  invention  of  Amonton,  and  Coulomb  himself  deduced  from  them  the  following  results  : 

1.  That  the  resistance  to  bending  could  be  represented  by  an  expression  consisting  of  two  terms,  the 
one  constant  for  each  rope  and  each  roller,  which  we  shall  designate  by  the  letter  A,  and  which  this 
philosopher  named  the  natural  stiffness,  because  it  depends  on  the  mode  of  fabrication  of  the  rope,  and 
the  degree  of  tension  of  its  yarns  and  strands ; the  other,  proportional  to  the  tension,  T,  of  the  end  of 
the  rope  which  is  being  bent,  and  which  is  expressed  by  the  product  BT,  in  which  B is  also  a number 
constant  for  each  rope  and  each  roller. 

2.  That  the  resistance  to  bending  varied  inversely  as  the  diameter  of  the  roller. 

Thus  the  complete  resistance  is  represented  by  the  expression 

A+  BT. 

D 

where  D represents  the  diameter  of  the  roller. 

Coulomb  supposed  that  for  tarred  ropes  the  stiffness  was  proportional  to  the  number  of  yarns,  and 
M.  Navier  inferred,  from  examination  of  Coulomb’s  experiments,  that  the  coefficients  A and  B were 
proportional  to  a certain  power  of  the  diameter,  which  depended  on  the  extent  to  which  the  cords  were 
worn.  M.  Morin,  however,  deems  this  hypothesis  inadmissible,  and  the  following  is  an  extract  from  his 
new  work,  “ Leqons  de  Mecanique  Pratique”  December,  1816  : 

“ To  extend  the  results  of  the  experiments  of  Coulomb  to  ropes  of  different  diameters  from  those 
which  had  been  experimented  upon,  M.  Navier  has  allowed,  very  explicitly,  what  Coulomb  had  but  sur- 
mised— that  the  coefficients  A and  B were  proportional  to  a certain  power  of  the  diameter,  which  depended 
on  the  state  of  wear  of  the  ropes ; but  this  supposition  appears  to  us  neither  borne  our,  nor  even  admis- 
sible, for  it  would  lead  to  this  consequence,  that  a worn  rope  of  a metre  diameter  would  have  the  same 
stiffness  as  a new  rope,  which  is  evidently  wrong ; and,  besides,  the  comparison  alone  of  the  values  oj 


580 


ROPES,  STIFFNESS  OF. 


A and  B shows  that  the  power  to  which  the  diameter  should  be  raised  would  not  be  the  same  for  the 
two  terms  of  the  resistance.” 

Since,  then,  the  form  proposed  by  M.  Navier  for  the  expression  of  the  resistance  of  ropes  to  bending 
cannot  be  admitted,  it  is  necessary  to  search  for  another,  and  it  appears  natural  to  try  if  the  factors  A 
and  B cannot  be  expressed  for  white  ropes,  simply  according  to  the  number  of  yarns  in  the  ropes,  as 
Coulomb  has  inferred  for  tarred  ropes. 

Now,  dividing  the  values  of  A,  obtained  for  each  rope  by  M.  Navier,  by  the  number  of  yarns,  we 
find  for 

A 

n = 30  <1=  0“-200  A = 0-222460 - = 0-0074153 

n 

n = 15  d=  0m-144  A = 0'003514  — = 0'0042343 

ii 

n—  6 d=Qm'  0088  A = 0-010604 - = 0D017673 

n 

It  is  seen  from  this  that  the  number  A 's  not  simply  proportional  to  the  number  of  yams. 

Comparing,  then,  the  values  of  the  r»  do  — > corresponding  to  the  three  ropes,  we  find  the  following 
results : 


Number  of 
yarns. 

Values  of  ^ • 

7 , 

Diffe.ences  of  the  numbers 
of  yarns. 

Differences  of 
the  values  of 
A 
n 

Differences  of 
the  values  of 

— for  each  yarn 
n 

of  difference. 

30 

0-0074153 

From  30  to  15. 

15  yarns 

0-0031810 

0-000212 

15 

0-f  04234 'J 

“ 15  to  6. 

9 “ 

00024770 

0-000272 

6 

'VOOR, 673 

“ 30  to  6. 

24  “ 

0-0056400 

0-000252 

Mean  difference  per  yarn,  0-000245. 


It  follows,  from  the  above,  that  the  values  of  A,  given  by  the  experiments,  will  be  represented  with 
sufficient  exactness  for  all  practical  purposes  by  the  formula 

A = n [0-0017673  + 0-000245  (n  — 6)]. 

= n [0-0002973  + 0-000245  «]. 

An  expression  relating  only  to  dry  white  ropes,  such  as  were  used  by  Coulomb  in  his  experiments. 
With  regard  to  the  number  B,  it  appears  to  be  proportional  to  the  number  of  yarns,  for  we  find  for 

5i  = 30  d = 0m-0200  B = 0-009738 - = 0-0003246 

n 

n=  15  cl  = 0m-0U4  B = 0-005518  - = 0-0003678 

n 


Whence 


51=  6 (f=0m-0088  B = 0-002380  — = 0-0003967 

n 

Mean 0-0003630 

B = 0-000363  n. 


Consequently,  the  results  of  the  experiments  of  Coulomb  on  dry  white  ropes  will  be  represented 
with  sufficient  exactness  for  practical  purposes  by  the  formula 

K = « [0-000297  + 0-000215  n + 0-000363  T]  kil. 

-which  will  give  the  resistance  to  bending  upon  a drum  of  a metre  in  diameter,  or  by  the  formula 


R = ~ [0-000297  + 0-000245  n + 0-000363  T]  kil. 
tor  a drum  of  diameter  D metres. 

These  formulae,  transformed  into  the  Englfeh  scale  of  weights  and  measures,  become 
R = k [0-0021508  + 0-0017724  n + 0-0011909S  T]  lbs. 
for  a drum  of  a foot  in  diameter,  and 


R = ^ [0-0021508  + 0-0017724  n + 0-00119096  T]  lbs. 
for  a drum  of  diameter  D feet. 

With  respect  to  worn  ropes,  the  rule  given  by  M.  Navier  cannot  be  admitted,  as  I have  shown  above 


ROPES,  STIFFNESS  OF. 


581 


Decause  it  would  give  for  the  stiffness  of  a rope  of  a diameter  equal  to  unity  the  same  stiffness  as  for  a 
new  rope ; and  it  is  from  having  adopted,  with  other  authors,  this  rule  without  investigation,  that  I have 
been  led  to  this  inadmissible  result,  in  calculating  the  table  of  the  stiffness  of  ropes  inserted  in  the  third 
edition  of  my  Aide  Memoire  de  Mecanique  Pratique , p.  328. 

The  experiments  of  Coulomb  on  worn  ropes  not  being  sufficiently  complete,  and  not  furnishing  any 
precise  data,  it  is  not  possible,  without  new  researches,  to  give  a rule  for  calculating  the  stiffness  of 
these  ropes. 

Tarred  ropes. — In  reducing  the  results  of  the  experiments  of  Coulomb  on  tarred  ropes,  as  we  have 
done  for  white  ropes,  we  find  the  following  values : 

n = 30  yarns  A = 0-34982  B = 0-0125605 
n — 15  “ A = 0-106003  B = 0-006037 

n—  6 “ A = 0-0212012  B = 0-0025997 

which  differ  very  slightly  from  those  which  M.  Navier  has  given.  But,  if  we  look  for  the  resistance 
corresponding  to  each  yarn,  we  find 

A B 

n = 30  yarns  — = 0'0116603  - = 0-000418683 

n n 

_ A _ B 
n = 15  “ - =0-0070662 - = 0-000402466 

n n 

A B 

n=  6 “ - =0-0035335  - =0-000433283 

n n 

Mean 0-000418144 

We  see  by  this  that  the  value  of  B is  for  tarred  ropes,  as  for  white  ropes,  sensibly  proportional  to  the 
number  of  yarns,  but  it  is  not  so  for  that  of  A,  as  M.  Havier  has  supposed. 

Comparing,  as  we  have  done  for  white  ropes,  the  values  of  — corresponding  to  the  three  ropes  of  30, 
15,  and  6 yarns,  we  obtain  the  following  results : 


Number  of 
yarns. 

Values  of  — • 
n 

Differences  of  the  numbers 
of  yarns. 

Differences  of 
the  values  of 
A 
n 

Differences  of 
the  values  of 

— for  each  yarn 
n 

of  difference. 

30 

0-0116603 

From  30  to  15. 

15  yarns 

0-0045941 

0-000306 

15 

0-0070662 

“ 15  to  6. 

9 “ 

0-0035327 

0-000392 

6 

0-0036335 

* 30  to  6. 

25  “ 

0-0081268 

0000339 

Mean 0-000346 


It  follows  from  this  that  the  value  of  A can  be  represented  by  the  formula 

A = n [0-0035335  + 0'000346  (n  — 6)] 

= n [0-0014575  -F  0-000346  n] 

and  the  whole  resistance  on  a roller  of  diameter  D metres,  by 

R = g [0-0014575  + 0-000346  n + 0-000418144  T]  kil. 

Transforming  this  expression  to  the  English  scale  of  weights  and  measures,  we  have 
R = g [0-01054412  -h  0-00250309  n + 0-001371889  T]  lbs. 
for  the  resistance  on  a roller  of  diameter  D feet. 

This  expression  is  exactly  of  the  same  form  as  that  which  relates  to  white  ropes,  and  shows  that  the 
stiffness  of  tarred  ropes  is  a little  greater  than  that  of  new  white  ropes. 

In  the  following  table  the  diameters  corresponding  to  the  different  numbers  of  yarns  are  calculated 
from  the  data  of  Coulomb,  by  the  formulae 

dcenl-  = V 0-1338  n for  dry  white  ropes,  and 
d ce"t-  = V O'l  86  n for  tarred  ropes, 
which,  reduced  to  the  English  scale,  become 

d inches  \f  0-020739  n for  dry  white  ropes,  and 
d in'hcs  = V 0-028S3  for  tarred  ropes. 

A nte. — The  diameter  of  the  rope  is  to  be  included  in  D ; thus,  with  an  inch  rope  passing  round  a pul 
ley,  8 inches  in  diameter  in  the  groove,  the  diameter  of  the  roller  is  to  be  considered  as  9 inches. 


582 


SAWS. 


i 

Ery  White  Ropes. 

Tarred  P»opes. 

Number  of 

Diameter. 

Value  of  the  natural 
stiffness,  A. 

Value  of  the  stiff- 
ness proportional 
to  the  tension,  B. 

Diameter. 

Value  of  the  natural 
stiffness,  A. 

Valueofthestiff- 
ness  proportional 
to  the  tension,  li. 

| 

ft. 

lbs. 

ft. 

lbs. 

6 

0'0293 

0-0767120 

0-0071457 

0-0347 

0-153376 

0-00823133 

9 

00360 

■ 01629234 

0-0107186 

0-0425 

0-297647 

0-01234700 

12 

0-0416 

0-2810384 

0-0142915 

0-0490 

0-486976 

0-01646267 

15 

0-0465 

0-4310571 

0-0178644 

00548 

0721357 

0-02057834 

18 

0-0509 

0 6129795 

0-0214373 

0-0600 

0-000795 

0-02469400 

21 

0 0550 

0-8268054 

0-0250102 

0-0648 

1-325289 

0-02880967 

24 

0-0588 

1-0725350 

0-0286831 

0-0693 

1-694839 

0-03292534 

27 

0-0622 

1-3501682 

00321559 

0-0735 

2-109444 

0-03704100 

30 

0-0657 

1-6597051 

0-0357288 

0-0775 

2-569105 

0'04115667 

33 

0-0689 

2-0011455 

0-0393017 

0-0813 

3-073821 

0-04527234 

36 

0-0720 

2-3744897 

0-0428746 

0-0849 

3-623593 

0-04938800 

39 

0-0749 

2-7797375 

0-0464475 

0-0884 

4-218416 

0-05350367 

42 

0-0778 

3-2168888 

0-0500203 

0-0917 

4-858303 

0-05761934 

45 

0-0805 

3-6859438 

0-0535932 

00949 

5-543242 

0-06173501 

48 

0-0831 

4-1869024 

0-0571661 

0-0980 

6-273287 

0-06585067 

51 

0-0857 

4"7 197647 

0-0607390 

0-1010 

7-048287 

0-06996634 

54 

0-0882 

5-2845306 

0-0643119 

0-1040 

7-868393 

0-07408201 

57 

0-0908 

5-8812001 

0-0678847 

0-1070 

8-733554 

0-07819767 

60 

0-0926 

6-5097733 

0-0714576 

0-1099 

9-643771 

0-08231334 

n 

v/0-000144  n 

( 0 0021508  n 

\ +0.0017724  7t2 

0'00119096?i 

v^0  00020  n 

< 0-01054412  n 

$ +0-00250309  nl 

0-001371889« 

Application  of  the  preceding  tables  or  formula. — To  find  the  stiffness  of  a rope  of  a given  diameter 
or  number  of  yarns,  we  must  first  obtain  from  the  table,  or  by  the  formulae,  the  values  of  the  quan- 
t.ties  A and  B corresponding  to  these  given  quantities,  and  knowing  the  tension,  T,  of  the  end  to  bf 
wound  up,  we  shall  have  its  resistance  to  bending  on  a drum  of  a foot  in  diameter  by  the  formula 

R = A + BT, 

Then,  dividing  this  quantity  by  the  diameter  of  the  roller  or  pulley  round  which  the  rope  is  actually 
to  be  bent,  we  shall  have  the  resistance  to  bending  on  this  roller. 

Example. — What  is  the  stiffness  of  a dry  white  rope,  in  good  condition,  of  60  yarns,  or  '0928  diameter 
which  passes  over  a pulley  of  6 inches  diameter  in  the  groove,  under  a tension  of  1000  lbs.?  The  table 
gives  for  a dry  white  rope  of  60  yarns,  in  good  condition,  bent  upon  a drum  of  a foot  in  diameter, 

A = 0-50977  B = 0'07l4576 


and  we  have  D — 0 5 + 0-0928  ; and  consequently, 

_ 6-50977  + 0-071457CX1000 
— 0-5928 


128  lbs. 


The  whole  resistance  to  be  overcome,  not  including  the  friction  on  the  axis,  is  then 
Q + K = 1000  + 128  = 1128  lbs. 

Tire  stiffness  in  this  case  augments  the  resistance  by  more  than  one-eighth  of  its  value. 


SAWS.*  Saws  may  he  considered  in  two  groups,  namely,  rectilinear  saws,  and  circular  saws.  The 
blade  of  the  rectilinear  saw  is  usually  a thin  plate  of  sheet  steel,  which  in  the  first  instance  is  rolled  of 
equal  thickness  throughout : the  teeth  are  then  punched  along  its  edge,  previously  to  the  blade  being 
hardened  and  tempered,  after  which  it  is  smithed  or  hammered,  so  as  to  make  the  saw  quite  flat.  The 
blade  is  then  ground  upon  a grindstone  of  considerable  diameter,  and  principally  crossways,  so  as  to 
reduce  the  thickness  of  the  metal  from  the  teeth  towards  the  back.  When,  by  means  of  the  hammer, 
the  blade  has  been  rendered  of  uniform  tension  or  elasticity,  the  teeth  are  sharpened  with  a file,  and 
slightly  bent,  to  the  right  and  left  alternately,  in  order  that  they  may  cut  a groove  so  milch  wider  than 
the  general  thickness,  as  to  allow  the  blade  to  pass  freely  through  the  groove  made  by  itself.  The  bend- 
ing, or  lateral  dispersion  of  the  teeth,  is  called  the  set  of  the  saw. 

The  circular  saw  follows  the  same  conditions  as  the  rectilinear  saw,  if  we  conceive  the  right  line  to 
be  exchanged  for  the  circle ; with  the  exception  that  the  blade  is,  for  the  most  part,  of  uniform  thick  - 
ness throughout,  unless,  as  in  the  circular  veneer  saws,  it  is  thinned  away  on  the  edge. 

It  is  to  be  observed  that  the  word  pitch,  when  employed  by  the  saw  maker,  almost  always  designates 
the  inclination  of  the  face  of  the  tooth,  up  which  the  shaving  ascends ; and  not  the  interval  from  tooth 
to  tooth,  as  in  wheels  and  screws.  The  teeth  of  some  kinds  are  usually  small,  and  seldom  so  distant  as 
an  inch  asunder : these  are  described  as  having  2,  3,  4,  5,  to  20  points  to  the  inch  ; such  as  are  used 


Holtzapfel. 


SAWS. 


58c 


by  hand,  are  commonly  from  about  -J  to  inch  asunder,  and  are  said  to  be  of  -ir  or  1^  inch  space 
although  some  of  the  circular  saws  are  as  coarse  as  2 to  3 inches  and  upwards  from  tooth  to  tooth. 

The  processes  denominated  sharpening  and  setting  a saw,  consist,  as  the  names  imply,  of  two  distinct 
operations : the  first  being  that  of  filing  the  teeth  until  their  extremities  are  sharp ; the  second,  that  of 
bending  the  teeth  in  an  equal  manner,  and  alternately  to  the  right  and  left,  so  that  when  the  eye  is  di- 
rected along  the  edge,  the  teeth  of  rectilinear  saws  may  appear  exactly  in  two  lines,  forming  collec- 
tively an  edge  somewhat  exceeding  the  thickness  of  the  blade  itself. 

3285.  3236. 


In  general  the  angles  of  the  points  of  the  saw 
teeth  are  more  acute,  the  softer  the  material  to 
be  sawn,  agreeably  to  common  usage  in  cutting 
tools ; and  the  angles  of  the  points,  and  those  at 
which  the  files  are  applied,  are  necessarily  the 
same.  Thus  in  sharpening  saws  for  metal,  the  file  is  generally  held  at  90  degrees  both  in  the  horizontal 
and  vertical  angle,  as  will  be  shown ; for  very  hard  woods  at  from  90  to  80  degrees,  ar.d  for  very  soft 
woods  at  from  70  to  60  degrees,  or  even  more  acutely.  The  vertical  angle  is  about  half  the  horizontal. 

Fig.  3235  represents  in  plan  and  two  elevations  the  saw-teeth  that  are  the  most  easily  sharpened, 
namely,  those  of  the  frame-saw  for  metal,  commonly  used  by  the  smith  : the  teeth  of  this  saw  are  not 
set  or  bent  in  the  ordinary  manner,  owing  to  the  thickness  and  hardness  of  the  blade,  and  the  small  size 
of  the  teeth. 


The  smith’s-saw  blade,  when  dull,  is 
placed  edgeways  upon  the  jaws  of  the  vice, 
and  the  teeth  which  are  placed  upwards, 
are  slightly  hammered  ; this  upsets  or  thick- 
ens them  in  a minute  degree,  and  the  ham- 
mer face  reduces  to  a general  level  those 
teeth  which  stand  highest.  They  are  then 
filed  with  a triangular  file  held  perfectly 
square,  or  at  ninety  degrees  to  the  blade, 
both  in  the  horizontal  direction  h,  and  the 
vertical  v,  until  each  little  facet  just  disap- 
pears, so  as  to  leave  the  teeth  as  nearly  as 
possible  in  a line,  that  each  may  fulfil  its 

share  of  the  work. 

The  most  minute  kind  of  saws,  those  which  are  made  of  broken  watch  springs,  have  teeth  that  are 
also  sharpened  nearly  as  in  the  diagram,  but  without  the  teeth  being  either  upset  or  bent ; as  in  very 
small  saws  the  trifling  burr,  or  rough  wiry  edge  thrown  up  by  the  file,  is  a sufficient  addition  to  the 
thickness  of  the  blade,  and  is  the  only  set  they  receive. 

Fig.  3236  illustrates  the  peg-tooth;  but  it  may  also  be  considered  to  apply  to  the  M tooth,  and,  in 
part,  to  the  mill-saw  tooth.  The  points  of  the  cross-cutting  saws  for  soft  woods  are  required  to  be 
acute  or  keen,  that  they  may  act  as  knives  in  dividing  the  fibres  transversely. 

The  left  sides  of  each  alternate  tooth,  are 
first  filed  with  the  horizontal  angle  denoted  by 
h,  and  then  the  opposite  sides  of  the  same  teeth 
with  the  reverse  inclination,  or  li.  Fig.  3237 
may  be  considered  to  refer  generally  to  all  teeth 
the  angles  of  which  are  60  degrees,  (or  the 
same  as  that  of  the  triangular  file,)  and  that 
are  used  for  wood.  The  most  common  exam- 
ple is  the  ordinary  hand-saw  tooth ; but  teeth 
of  upright  pitch,  such  as  the  cross-cut  saw, 
or  of  considerable  pitch,  are  treated  much  in 
the  same  manner.  The  teeth  having  been 
topped,  the  faces  5,  9,  are  first  filed  back, 
until  they  respectively  agree  with  a dotted  line 
a,  supposed  to  be  drawn  through  the  centre  of  each  little  facet  produced  in  the  topping;  the  file  is  then 
made  to  take  the  sides  6 and  t of  the  nook  until  the  second  half  of  the  facet  is  reduced,  and  the  point 
of  the  tooth  falls  as  nearly  as  may  be  on  the  dotted  line  a.  The  first  course  takes  the  face  only  of 
each  alternate  tooth  ; the  second  course  the  back  of  the  former  and  face  of  the  next  tooth  at  one  pro- 
cess ; and  the  third  course  takes  the  top  only  of  the  second  series,  and  completes  the  work.  This  ordei 
of  proceeding  is  employed,  that  the  faces  of  the  teeth  may  be  in  each  case  completed  before  the  tops  o. 
backs 


3233. 


3237. 


584 


SAWS. 


Fig.  3238  exhibits  also  in  three  elevations  a somewhat  peculiar  form  of  tooth,  namely,  that  of  the 
pruning-saw  for  green  wood.  The  blade  is  much  thicker  on  the  edge  than  the  back,  so  that  the  teeth 
are  not  set  at  all.  The  teeth  are  made  with  a triangular  file,  applied  very  obliquely  as  to  horizontal 
angle,  as  at  h,  sometimes  exceeding  45  degrees,  but  without  vertical  inclination,  as  at  v;  and  the  faces 
of  the  teeth  are  nearly  upright,  as  in  the  hand-saw.  The  large  sides  of  the  teeth  are  very  keen  and  each 
vertical  edge  is  acute  like  a knife,  and  sharply  pointed ; in  consequence  of  which  it  cuts  the  living  wood 
with  a much  cleaner  surface,  and  less  injury  to  the  plant,  than  the  common  hand-saw  toith. 

Fig.  3239  explains  the  method  em- 
ployed in  sharpening  gullet  or  briar- 
teeth  ; in  these  there  are  large  curvili- 
near hollows,  in  the  formation  of  which 
the  faces  of  the  teeth  also  become  hol- 
lowed so  as  to  make  the  projecting 
angles  acute.  The  gullets  3,  7,  are 
first  filed,  and  from  the  file  crossing  the 
tooth  very  obliquely,  as  at  v v in  the 
section,  the  point  of  the  tooth  extends 
around  the  file,  and  gives  the  curvature 
represented  in  the  plan.  The  file  should 
not  be  so  large  as  the  gullet ; it  is  there- 
fore requisite  that  the  file  be  applied  in 
twe  positions,  first  upon  the  face  of  the 
one  tooth,  and  then  on  the  back  of  the  preceding  tooth.  The  tops  of  the  teeth,  2,  6,  are  next  sharp- 
ened with  the  flat  side  of  the  file,  the  position  of  which  is  of  course  determined  by  the  angles  c and  d ; 
the  former  varies  with  the  material  from  about  5 to  40  degrees  with  the  edge,  and  the  latter  from  80  to 
60  degrees  with  the  side  of  the  blade;  the  first  angles  in  each  case  being  suitable  for  the  hardest,  and 
the  last  for  the  softest  woods.  The  alternate  teeth  having  been  sharpened,  the  remainder  are  completed 
from  the  other  side  of  the  blade  requiring  in  all  four  ranges. 

After  sharpening,  the  saw  is  to  he  set,  that  is,  an  uniform  bend  is  given  to  the  teeth  alternately  to  the 
right  and  to  the  left.  This  is  often  done  by  a hammer  and  set  punch,  but  usually  by  a saw  set  which 
consists  of  a narrow  blade  of  steel,  with  notches  of  various  widths,  for  different  saws.  The  saw  is 
firmly  held  in  clamps,  the  alternate  teeth  are  inserted  a little  way  into  the  proper  notch,  and  are  then 
bent  over  by  raising  or  depressing  the  handle  of  the  blade.  Some  sets  are  arranged  with  a guide  by 
which  the  bends  shall  he  uniform. 

The  method  of  sharpening  and  setting  circular  saws  is  very  similar  to  that  employed  for  rectilinear 
saws.  The  teeth  of  circular  saws  are  in  general  more  distant,  more  inclined  and  more  set,  than  those 
of  rectilinear  saws.  They  are  more  distant  on  account  of  the  greater  velocity  given  to  the  saw, 
whereby  the  teeth  follow  in  such  rapid  succession  that  the  effect  is  almost  continuous.  They  are  more 
inclined  because  such  teeth  cut  more  keenly,  and  the  extra  power  required  to  work  them  is  readily  ap- 
plied. The  harder  the  wood,  the  smaller  and  more  upright  should  he  the  teeth,  and  the  less  the  velocity 
of  the  saw.  The  teeth  are  more  set  in  order  to  produce  a wider  kerf,  since  the  large  circular  plate 
cannot  be  made  so  true,  nor  keep  so  true  as  the  narrow  straight  blade.  The  setting  must  be  very  uni- 
form, as  one  tooth  projecting  beyond  the  general  line  will  score  or  scratch  the  work.  ‘'It  is  generally 
politic  to  use  for  any  given  work  a saw  of  as  small  diameter  as  circumstances  will  fairly  allow,  as  the 
resistance,  the  surface  friction,  and  also  the  waste  from  the  thickness,  rapidly  increase»with  the  diameter 
of  the  saw.  But  on  the  other  hand,  if  the  saw  is  so  small  as  to  be  nearly  or  quite  buried  in  the  work, 
the  saw-plate  becomes  heated,  the  free  escape  of  the  dust  is  prevented,  and  the  rapidity  of  the  sawing 
is  diminished.”  As  a general  rule  the  diameter  of  the  saw  should  be  about  4 times  the  average  thick- 
ness of  the  wood ; and  the  flange  on  the  spindle  should  be  as  nearly  as  possible  flush  with  the  platform 
or  saw-table. 

In  cutting  with  the  grain,  the  teeth  of  the  saw  should  he  coarse  and  inclined,  and  the  speed  mod- 
erate, so  as  to  remove  shreds  rather  than  sawdust.  In  cutting  across  the  grain,  the  teeth  should  be 
finer  and  more  upright,  and  the  velocity  greater. 

The  usual  saws  used  at  saw-mills  for  the  manufacture  of  lumber  are  rectilinear  saws,  supported  in  an 
upright  frame,  to  which  motion  is  given  by  a crank,  either  attached  to  a small  water-wheel,  or  drum, 
driven  by  a steam  engine.  The  feed  is  generally  by  a carriage  geered  and  driven  by  a pawl  on  the  saw 
frame,  working  into  a ratchet  wheel.  In  water  mills  the  carriage  is  drawn  back  by  a distinct  wheel. 
In  many  mills  the  feed  is  continuous,  the  log  being  drawn  in  by  feed  rolls.  For  the  manufacture  of 
boards  many  saws  are  set  in  one  frame,  the  whole  log  being  split  at  once ; they  are  called  gang  saws. 
Saws  without  frame,  working  in  a guide  at  the  top,  and  attached  to  the  crank  at  the  bottom  are  called 
muley  saws.  Circular  saws  are  sometimes  used  for  the  manufacture  of  timber,  bat  not  to  any  great 
extent. 

SAWS.  Improvement  in  Tempering  and  Straightening,  Watermans  patent.  The  usual  method  of 
tempering  saws  is  to  heat  and  then  dip  them  in  oil. — This  process  is  slow,  laborious,  and  costly  ; it  is 
a.so  disadvantageous,  because  the  saws  become  warped,  and  require  to  be  hammered  up  straight  again 
by  hand. 

The  present  improvement  consists  in  tempering  and  straightening  the  saws  at  one  operation.  This 
is  done  by  heating  the  saws  to  the  proper  degree,  and  then  pressing  them,  with  a sudden  and  powerm. 
ftroke,  between  the  two  surfaces  of  cold  iron.  Drop  presses  are  employed  for  the  purpose.  The  en- 
graving shows  a pair  of  presses  conjoined,  one  for  long  the  other  for  circular  saws.  After  being  heated 
the  saws  are  supported  in  mid  air,  on  buttons  attached  to  the  framing  at  the  base  of  the  machine.  The 
heavy  drop-weights  A A,  are  now  liberated  by  pulling  the  cords  B B,  and  the  weights  fall  upon  their 


SAWS,  TEMPERING  AND  STRAIGHTENING. 


585 


respective  saws,  drive  them  down,  and  press  them  upon  the  solid  iron  base  C,  with  tremendous  force 
The  sudden  blow  hardens  the  metal  by  rendering  it  more  dense,  and  also  straightens  the  saw. 


SCALE,  a line  drawn  upon  wood,  ivory,  etc,,  and  divided  into  parts,  the  lengths  of  which  may  be 
taken  off  by  the  compasses  and  transferred  to  paper. 

^ '--I'll \\ . screws  aie  of  two  kinds,  external  or  male,  and  or  female,  The  first  kind  consists 

of  a cylinder,  on  the  surface  of  which  is  a projecting  fillet,  or  thread , passing  spirally  round  so  as  to  make 
equal  angles  with  lines  parallel  to  the  axis  of  the  cylinder.  The  second  kind  of  screw  consists  opa  cylin- 
drical perforation  through  a solid  block,  bearing  a spiral 
which  it  is  adapted. 

The  screw  is  usually  regarded  as  a continuous  circular 
tance  between  two  contiguous  centres  of  the  same  thread, 

(o  the  pitch.  . The  screw  will  be  a right-hand  or  a left-hand  screw,  according  as  the  wedge  is  wound 
upon  the  cylinder,  to  the  right  hand  or  to  the  left.  Double , triple,  or  quadruple  screws  are 'those  which 


groove,  corresponding  to  the  male  thread  to 

wedge.  The  pitch  of  the  screw'  is  the  dis- 
and the  screw  will  be  coarse  or  fine  according 


686 


SCREWS— SELF-OPERATING  SHAVER. 


have  a double,  triple,  or  quadruple  thread,  such,  for  example,  as  would  be  formed  by  placing  2,  or  4 
strings  in  contact,  and  coiling  them  as  a flat  band  round  the  cylinder.  The  screw  may  also  vary  in 
section,  that  is,  the  section  of  the  worm  or  thread  may  be  aru/ular , square , round , etc. 

Micrometer  screws  are  screws  of  extremely  fine  pitch,  accurately  made,  and  used  for  graduation. 
Wood  screws  is  a term  applied  to  the  common  screw,  as  used  by  carpenters.  Machine  screws  are  a sim- 
ilar screw  adapted  to  joiners  in  iron  work. 

SCREWS — SELF-OPERATING  SHAVER.  This  is  an  improvement  in  machinery  for  turning  or 
shaving  the  heads  of  the  blanks  which  are  to  be  formed  into  wood-screws,  by  J.  Cullen  Whipple, 
Providence,  Rhode  Island. 

In  the  machines  heretofore  used  for  turning  or  shaving  the  heads  of  blanks,  the  tool  or  cutter  by  which 
they  were  finished  was  brought  up  against  them  by  hand ; but  in  this  improved  machine  the  parts 
are?  made  self-acting  by  means  of  cams  and  levers,  and  other  devices  connected  therewith,  arranged  for 
that  mrrpose  in  the  manner  to  be  described. 


3241. 


In  the  accompanying  drawings  Fig.  3241  is  a side,  and  Fig.  3242  a plan  or  top  view.  A A is  the 
frame  of  the  machine,  which  is  made  of  cast-iron.  C C is  a tubular  or  hollow  arbor  or  spindle,  which  is 
sustained  by  and  runs  in  the  heads  A'  A'.  The  arbor  or  spindle  C is  driven  by  a band  on  a whirl  or 
pulley  D,  and  it  is  widened  out  at  its  end,  C',  so  as  to  constitute  two  cheeks  which  embrace  the  jaws 
E E.  Through  the  tubular  arbor  C the  sliding-bolt  F F passes,  and  serves  to  close  the  jaws  E,  its 
wedge-formed  end  F'  passing  in  between  the  tails  a a of  the  jaws  for  that  purpose.  The  sliding-bolt  F 


bears  at.  Its  outer  end  against  a regulating  screw  G.  This  screw  passes  through  the  head  H'  of  the  lever 
H,  which  has  its  fulcrum  at  I.  When  the  end  H2  of. this  lever  is  depressed,  its  end  H'  will  force  the  bolt 
F forward,  and  cause  the  jaws  E to  close  and  embrace  the  blank  which  is  to  be  turned  The  lever  H is 
depressed  by  means  of  a cam  J,  which  is  carried  by  a cam-shaft  K K.  The  cam  J as  it  revolves  oper- 
ates upon  a lever  L,  having  its  fulcrum  at  L2,  the  short  arm  of  which  L'  serves  to  depress  the  end  H2  ot 


SCREW  BLANKS. 


5X7 


i hardened  roller  M,  near  its  end  H2,  upon  which  L'  bears.  As  represented  in  Fig.  3241,  the  lever 
L is  relieved  from  its  action  on  the  lever  II  by  its  having  fallen  into  the  recess  between  the  points  J'  J' 
of  the  cam  J ; the  weight  II3  serves  to  raise  the  lever  H.  The  arbor  C C and  the  sliding-bolt  F F then 
fall  back,  release  the  blank  that  has  been  turned,  and  allow  a new  one  to  be  fed  in.  There  is  a second 
cam  N N,  carried  by  the  shaft  K,  which  cam  serves  to  advance  the  tool  or  cutter  0 against  the  head  to 
be  turned.  This  tool  or  cutter  does  not  differ  from  those  used  in  other  machines  for  turning  the  heads 
of  screws.  P is  a lever  upon  which  the  cam  N operates  to  raise  the  cutter  and  carry  it  regularly  against 
the  head  of  the  blank  ; the  fulcrum  of  this  lever  is  at  Q.  P'  is  a branch  of  the  lever  P,  which  by  the 
aid  of  the  set-screw  P"  allows  the  action  of  the  cutter  to  be  accurately  graduated.  The  periphery  of 
the  cam  J is  equidistant  from  its  centre  K,  but  that  of  the  cam  N has  a gradually  increasing  diameter, 
to  cause  the  cutter  to  advance  gradually,  as  it  takes  a shaving  off  the  head.  The  cutting  part  of  the. 
tool  is  so  formed  as  to  cut  both  the  top  and  bevel  of  the  head  at  the  same  time. 

On  the  same  shaft  with  the  cams  there  is  a large  spur-wheel  R,  and  motion  is  given  to  this  wheel  by 
means  of  a tubular  pinion  S,  on  a third  shaft  T,  the  bearings  of  which  shaft  are  on  the  standards  A2  A2. 
The  shaft  T also  carries  the  large  band-wheel  U U,  which  receives  a band  from  a small  band-wheel  or 
whirl  Y on  the  shaft  0.  The  shaft  C and  the  band-wheel  U have  their  motion  continuous,  the  band 
around  the  whirl  Y and  the  wheel  U connecting  these  two  parts.  W is  a sliding  clutch-box,  having  the 
pinion  S attached  to  it ; and  these  are  moved  back  and  forth  by  the  shipper  X,  which  is  governed  by 
the  handle  Y,  a rock-shaft  Z on  the  lower  end  of  which  extends  to  the  lower  end  of  the  shipper,  by 
means  of  which  the  clutch-box  is  brought  into  contact  with  or  removed  from  the  clutch-pin,  the  clutch- 
ing being  effected  by  a tooth  or  pin  b falling  into  one  of  the  spaces  ccc.  For  the  purpose  of  arresting 
the  wheel  R at  the  proper  time  for  removing  a finished  and  feeding  in  a new  blank,  that  is  to  say,  at 
the  period  when  the  cams  cease  to  act  upon  the  levers  P and  L,  there  is  a pin  p projecting  from  the 
shipper  X at  its  upper  end,  on  the  side  opposite  to  that  seen  in  Fig.  3241,  which  pin  points  towards  the 
wheel  R,  and  said  wheel  has  a hole  in  its  side,  as  at  d,  Fig.  3241,  into  which  said  pin  will  fall  when  the 
wheel  comes  round  to  the  proper  point.  The  spiral  spring  e'  draws  upon  the  shipper  X for  the  purpose 
of  forcing  said  pin  into  the  hole,  and  of  arresting  the  wheel.  There  is  a gage-pin  d within  the  cheeks 
c,  against  which  a blank  e is  stopped  when  fed  in ; this  pin  is  regulated  by  a set-screw/  to  suit  blanks 
of  different  lengths.  B is  a rest  which  sustains  a blank  whilst  it  is  being  turned.  Within  the  jaws  E E 
there  is  a spring  g g by  which  they  are  opened,  and  the  blanks  relieved  as  the  bolt  F recedes.  The 
feeding  is  effected  by  passing  the  blank  in  between  the  jaws  on  the  side  shown  in  Fig.  3241,  where  B' 
is  the  head  of  a blank  inserted  ready  for  the  shaving  or  turning,  by  the  tool  0.  When  it  has  been 
turned  and  the  jaws  opened,  it  is  removed  and  another  inserted  by  hand  ; the  blank  being  stopped  by 
the  gage-pin  d'. 

One  person  can  readily  attend  two  such  machines,  his  duty  being  to  operate  the  clutch  at  the  proper 
time  and  to  feed  in  a new  blank. 

SCREW  BLANKS — Merrick’s  patent.  Fig.  8243  denotes  a plan  of  the  blank  feeder;  Fig.  3244,  a 
longitudinal,  vertical,  and  central  section. 

In  the  said  figures  A represents  a conical  hopper,  sustained  in  position  by  a suitable  frame-work  B. 
Two  conic  frustra  C D are  disposed  within  the  said  hopper,  and  the  one  over  the  other,  and  sustained 
upon  shafts  or  bearings,  as  seen  in  the  drawings.  The  said  conic  frustra  should  revolve  in  contrary  di- 
rections, as  denoted  by  arrows  in  the  figures.  The  diameter  of  the  base  of  the  lower  frustum  is  some- 
what less  than  the  diameter  of  the  lowest  part  of  the  interior  of  the  hopper,  there  being  a circular  space 
E left  between  them  of  a width  to  correspond  with  the  diameter  of  the  shank  of  each  of  the  screw 
blanks,  and  permit  them  to  move  freely  through  it,  as  will  be  hereinafter  described.  The  exterior  sur- 
faces of  the  two  conic  frustra  should  be  roughened  or  indented  in  such  manner  as  to  act  upon  the  screw 
or  pin  blanks  and  cause  them  to  revolve.  Generally  speaking,  the  angles  of  inclination  of  the  exterior 
edge  of  the  two  conic  frustra  and  the  interior  edge  of  the  hopper,  with  respect  to  a horizontal  plane, 
are  to  be  equal,  or  about  equal,  as  denoted  in  Fig.  3244.  Between  the  inner  face  of  the  hopper  and  the 
outer  faces  of  the  two  frustra,  I extend  a partition  F,  which  I secure  to  the  hopper,  and  permit  to 
approach  as  near  as  possible  towards  the  frustra  and  not  interfere  with  their  revolving  movements,  and 
at  a suitable  distance  from,  or  on  the  right  of  the  said  partition,  and  between  the  interior  face  of  the 
hopper  and  the  exterior  faces  of  the  frustra,  I arrange  a revolving  beater  G. 

The  said  beater  consists  of  one  or  more  triangular  or  other  suitably  shaped  plates  H H,  applied  to  a 
horizontal  shaft  I extending  into  the  hopper,  and  sustained  in  bearings  at  L JVI,  as  represented  in  the 
figures.  The  said  beater  may  be  revolved  by  an  endless  band  N,  which  may  pass  around  a grooved 
pulley  o placed  upon  the  shaft  P of  the  upper  conic  frustum,  and  thence  over  guide-pulleys  Q R,  and 
under  a small  pulley  S fixed  upon  the  shaft  of  the  beater.  The  lower  conic  frustum  should  have  a 
pulley  T fixed  upon  its  axis ; from  the  said  pulley  an  endless  belt  V proceeds  to  and  around  a pulley 
Y fixed  upon  a vertical  shaft  W.  The  said  shaft  has  another  pulley  X fixed  upon  its  upper  end,  the 
said  pulley  communicating  with  another  one  (viz.  Y upon  the  shaft  of  the  upper  conic  frustum)  by  a 
cross-band  L.  Instead  of  the  aforesaid  modes  of  giving  motion  to  the  several  parts,  any  suitable  geer- 
work  may  be  adopted. 

The  screw  or  other  blanks  of  the  kind  are  to  be  thrown  previously  into  the  hopper  on  the  left-hand 
side  of  the  partition  F ; as  the  upper  conic  frustum  C revolves  from  left  to  right,  and  the  lower  one  D 
from  right  to  left,  they  will  disturb  the  screw  blanks  which  come  in  contact  with  them  in  such  manner 
as  to  cause  them  to  successively  move  downwards  the  circular  space  E before  mentioned,  through  which 
the  shanks  will  fall  until  arrested  in  vertical  positions  by  the  heads  of  the  blanks  coming  into  contact 
with  the  adjacent  inclined  surfaces  of  the  lower  conic  frustum  and  the  hopper. 

As  the  lower  frustum  continues  to  revolve,  it  will  advance  each  screw  blank  through  the  circular 
space  E,  in  the  direction  in  which  it  (the  frustum)  travels.  The  circular  space  E will  thus  be  filleu 
with  screw  blanks,  whose  shanks  stand  in  vertical  positions,  as  denoted  at  a a.  The  object  of  the  beater 
is  to  prevent  any  one  of  the  blanks  from  overriding  the  others  or  disturbing  the  arrangement  of  those 


SCREWS,  BURRING  MACHINE  FOR. 


588 


which  may  be  in  that  part  cf  the  space  E which  exists  on  the  right  of  the  partition  F,  and  between  it 
and  the  beater.  The  object  of  the  upper  conic  frustum  is  to  prevent  the  blanks  from  being  carried 
around  towards  the  beater  in  too  great  a body ; it  also  facilitates  the  downward  movements  of  the 
Dlanks  towards  the  space  E. 

The  triangular  plates  or  arms  of  the  beater,  shaped  as  seen  in  Fig.  324-1,  revolve  in  the  same  directior 
a9  does  the  upper  conic  frustum.  They  therefore  throw  or  keep  back  such  blanks  as  might  accumulate 
to  an  injurious  extent  in  rear  of  them. 

3244. 


The  next  part  of  the  apparatus  is  that  by  which  the  blanks  are  regularly  delivered  or  fed  from  the 
circular  space  E.  It  consists  of  a horizontal  slide-plate  b,  Fig.  3243,  (which  represents  a view  of  the 
under  sides  of  the  hopper  and  lower  conic  frustum  D,)  affixed  to  the  lower  edge  of  the  hopper  just  on 
the  right  of  the  partition  F,  the  said  plate  being  suitably  sustained,  so  as  to  slide  towards  and  from  the 
axis  of  the  lower  conic  frustum.  It  is  forced  inwards  or  towards  the  same  by  means  of  a spring  c ap- 
plied to  it  and  the  hopper.  The  said  plate  has  a circular  aperture  d cut  through  one  end  of  it,  and  a 
passage  e into  said  aperture  cut  through  the  side  of  the  plate,  the  whole  being  as  seen  in  the  figures. 
The  inner  end  of  the  plate  is  cam-shaped,  as  seen  at  f so  that  when  a stud  g,  projecting  from  the  under 
side  of  the  lower  frustum,  is  brought  into  contact  with  it,  the  stud  shall  press  the  slide  outwards,  or  in 
a direction  away  from  the  frustum,  and  bring  the  passage  e into  line,  or  so  as  to  correspond  with  the 
circular  opening  E.  When  this  takes  place,  the  movement  of  the  lower  frustum  will  carry  one  of  the 
screw  blanks  through  the  passage  e and  cause  it  to  drop  out  of  the  machine,  the  circular  aperture  d 
being  made  larger  in  its  diameter  than  that  of  the  head  of  the  blank. 

There  is  a small  stud  h fixed  upon  the  rear  side  of  the 
entrance  e of  the  slide,  as  seen  in  the  figure.  When  the  slide 
is  pressed  outwards  this  stud  enters  between  the  screw  blank 
wdiich  is  to  be  discharged  and  the  one  next  to  it,  and  thereby 
prevents  the  escape  of  the  latter.  As  soon  as  the  blank  is 
discharged,  the  slide-plate  should  be  moved  inwards  by  its 
spring. 

The  screw,  or  pin,  or  other  blank  thus  discharged,  may 
be  received  by  or  into  any  apparatus  calculated  to  hold  or 
dispose  of  it  for  any  other  operation  necessary  to  be  per- 
formed. 

Instead  of  the  conical  frustra  and  hopper,  I sometimes 
make  use  of  two  or  more  chain-belts  arranged  parallel  to 
each  other  and  at  a proper  distance  apart,  and  I apply  to 
them  a hopper  and  beater ; but  I consider  the  said  chain- 
belts,  as  mechanical  equivalents  to  the  aforesaid  mechan- 
ism, by  no  means  so  useful  or  perfect  in  their  operation. 

The  beater  may  be  applied  to  two  cylinders  or  rollers 
placed  parallel  to  and  apart  from  each  other,  and  provided 
with  a hopper  and  other  contrivances  by  which  the  blanks  may  be  dropped  between  them,  and  ad- 
vanced towards  the  beater. 

In  some  cases  but  one  conic  frustum  may  be  used  in  connection  with  the  hopper ; in  others,  a greater 
number  may  be  necessary,  according  to  circumstances. 

SCREWS,  BURRING  MACHINE  FOR — By  J.  Cullen  Whipple,  of  Providence,  Rhode  Island. 
Fig.  3245  is  a front  view  of  the  machine,  or  of  that  part  opposite  to  which  the  person  stands  who  is 
using  it;  Fig.  3246  is  a side  view  of  it;  Fig.  3241,  a section  through  the  main  spindle  or  arbor;  Fig. 
3248,  the  under  face  of  the  machine;  and  Fig.  3249,  the  upper  face  of  the  lower  end. 

A A is  the  bed-piece  or  main-frame,  which  supports  the  working  parts,  and  which  is  usually  of  cast- 
iron.  A'  is  a piece  projecting  therefrom,  by  which  it  may  be  fastened  to  a bench.  B is  a whirl  or 
pulley  on  the  main  arbor  or  spindle  C C.  This  arbor  runs  and  slides  in  collars  in  the  heads  A2  A2.  The 
arbor  C widens  out  at  its  lower  end  C',  and  is  divided  so  as  to  form  two  cheeks,  between  which  the 
jaws  D D are  to  be  received.  These  jaws  work  upon  pins  a a,  which  pass  through  them  and  through 
the  cheeks.  HH  is  an  adjustable  slide,  which  is  fastened  to  the  bed-piece  A by  a-  screw  b passing 
through  a slot. 


3243. 


SCREWS,  BURRING  MACHINE  FOR. 


589 


The  part  H7  of  the  adjustable  slide,  which  stands  at  right  angles  to  the  part  H,  has  on  its  face  a 
piece  I fastened  to  it  by  a screw  c,  and  this  holds  the  tool  G,  by  which  the  burs  are  to  be  removed  fiorn 
the  under  side  of  the  heads,  the  proper  form  being  given  to  the  cutting  part  G2  of  said  tool,  to  adapt  it 


cut  away,  as  shown  at  e. 

The  arbor  C 0 is  tubular,  and  there  passes  through  it  a sliding-bolt  K,  having  a wedge-formed  head  K', 
cy  which  the  jaws  DD  are  to  be  closed,  and  this  closing  will  take  place  as  the  bolt  is  drawn  back,  and 


(tie  wedge  part  K'  is  forced  against  the  tails  ffoi  the  jaws.  F'  is  a shaft,  to  which  is  attached  an 
sum  F,  that  is  forked  at  its  outer  end  F2,  and  is  received  between  collets  L L attached  to  the  sliding- 


590 


SCREW-CUTTING  MACHINE. 


bolt  K.  EE  are  a handle  and  lever,  by  which  the  sliding-bolt  K and  the  spindle  C are  drawn  upwards 
A spiral  spring  M surrounds  the  arbor  C,  and  bearing  against  the  uppermost  of  the  heads  A2  and  against 
the  pulley  B,  causes  the  spindle  and  bolt  to  descend,  when  the  handle  E is  allowed  to  recede  and  ren  • 
ders  the  motion  in  both  directions  regular  and  smooth.  As  the  bolt  K descends  it  is  brought  into  con- 
tact with  the  pins  g g,  which  are  made  fast  to  the  jaws  and  forces  them  open. 

In  using  this  machine,  when  the  handle  E has  been  moved  back,  and  the  sliding-bolt  and  arbor  have 
descended,  a blank,  which  has  been  notched,  is  fed  in  through  the  countersunk  opening  in  the  plate  J, 
so  as  to  enter  between  the  jaws.  The  handle  E is  then  drawn  forward,  which  closes  said  jaws  and 
brings  the  head  up  against  the  cutting  edge  of  the  tool  G,  by  which  the  removal  of  the  bar  is  instan- 
taneously effected,  the  edge  of  the  tool  projecting  a little  within  the  countersink.  In  removing  the 
handle  back  the  blank  is  liberated  and  falls  out,  and  another  is  fed  in. 

SCREW-CUTTING  MACHINE.  This  is  an  invention  of  1’eter  II.  Watson,  Esq.,  of  Rockford, 
Illinois,  for  cutting  serews. 

Fig.  3250  is  a perspective  view  of  the  machine,  as  arranged  for  cutting  a male  screw  upon  a rod  of 
metal. 


Fig.  3251  is  a view  of  the  face  of  the  bevelled  cog-wheel,  carrying  the  dies,  cutter  and  rest,  <fcc. 

Fig.  3252  is  a vertical  transverse  section  of  the  carriage  and  jaws  for  holding  the  material  to  be 
operated  on. 

Fig.  3253  is  a plan  of  the  cutter. 

Fig.  3254  is  a plan  of  the  tap  in  the  act  of  cutting  the  thread  in  a nut. 

The  nature  of  this  improvement  consists  in  combining  and  arranging  in  a suitable  frame  certain 
known  mechanical  principles  in  such  a way  as  to  form  a new  and  useful  machine,  which  will  enable  the 
mechanic  to  make  screws  and  nuts  with  greater  dispatch  and  correctness  than  by  the  modes  now 
in  use. 

325.*. 


The  combination  consists  of  a cog-wheel  A and  pinion  B working  into  the  same,  supported  by  suitable 
framework  C on  a permanent  bed  D,  said  cog-wheel  having  attached  to  its  face  two  sliding-dies  E E of 
the  usual  form  for  indenting  the  screw  on  the  rod  of  iron  F,  said  dies  being  turned  with  said  cog-wheel, 
which  is  caused  to  revolve  by  turning  a crank  G on  the  axle  of  the  pinion  B,  while  the  rod  of  iron  F is 
held  in  a horizontal  position  between  two  vertical  parallel  jaws  H,  attached  to  sliding-carriage  I,  moved 
in  parallel  grooves  S in  the  bed  towards  the  dies,  by  the  draft  of  the  dies  and  chaser,  on  the  rod  in 
cutting  the  thread  which  passes  through  the  hub  of  the  wheel,  made  hollow  for  that  purpose,  the  screw 
being  perfected  and  finished  before  passing  through  the  opening  in  the  centre  of  the  wheel,  by  means 
of  an  adjustable  cutter  or  chaser  J,  of  a shape  corresponding  to  the  shape  of  the  thread  to  be  cut, 
attached  tr  the  face  of  the  wheel  between  the  dies  and  the  wheel  directly  behind  the  dies,  and  in  a 


SCREW  FINISHER. 


591 


[KJsition  to  bring  tlie  cutter  for  chaser  in  contact  with  the  thread  as  marked  by  the  dies,  so  as  to  cut  and 
perfect  it  as  it  leaves  the  dies,  said  cutter  being  attached  to  the  face  of  the  wheel  by  a set  screw  J 
passing  through  an  oblong  mortise  in  its  shank. 

A forked  rest  K is  connected  to  the  cog-wheel  in  the  same  manner  so  as  to  bear  against  the  screw  on 
tire  side  opposite  to  that  where  the  cutter  is  placed  being  designed  to  support  the  screw  while  under 
the  operation  of  the  chaser  or  cutter. 

The  dies  are  contained  in  and  supported  by  a sliding-frame  L,  and  are  moved  by  a right  and  left 
screw  M,  attached  by  a collar  to  a stud  N inserted  into  the  face  of  the  wheel  turned  by  a milled  head 
or  other  means,  without  changing  its  position  longitudinally,  the  right  thread  working  in  a female  head 
in  the  middle  of  the  top  of  said  sliding-frame  L,  and  the  left  thread  in  a female  thread  in  the  middle  of 
the  sliding  follower  which  slides  in  the  sliding-frame,  the  lower  die  being  placed  against  the  bottom  of 
the  sliding-frame  and  the  upper  die  against  the  under  side  of  the  follower  P,  so  that  when  said  screw  is 
turned  it  causes  the  dies  to  approach  or  recede  from  each  other  simultaneously  by  giving  the  follower 
and  bottom  of  the  frame  similar  movements  in  opposite  directions.  The  inner  sides  of  the  frame  are 
made  of  a V-shape  to  enter  corresponding  shaped  grooves  in  the  ends  of  the  die-plates  and  follower. 
The  outsides  of  the  sliding-frame  are  similarly  shaped  to  slide  in  corresponding  grooves  made  on  the 
under  sides  of  parallel  ribs  and  fastened  to  the  face  of  the  wheel. 

This  arrangement  is  adopted  for  the  purpose  of  adapting  the  dies  to  various  diameters  of  rous  upon 
which  screws  are  to  be  made,  and  for  centering  the  dies  and  rods. 

The  jaws  for  holding  the  rod  of  iron  on  which  the  screw  is  to  be  cut  consists  of  two  vertical  parallel 
plates  H H,  notched  or  recessed  on  their  inner  sides  where  they  grip  or  clamp  the  rod  F,  having  their 
lower  ends  turned  at  right  angles  to  enter  and  slide  back  and  forth  in  parallel  grooves  R R on  the  upper 
side  of  the  sides  of  the  sliding-carriage  I at  right  angles  to  the  grooves  S in  the  bed  in  which  the 
carriage  I moves.  These  jaws  are  opened  or  closed  by  means  of  a right  and  left  horizontal  screw  T, 
turned  in  corresponding  right  and  left  female  screws  in  the  jaws  H H,  said  screw  being  prevented  from 
changing  its  position  longitudinally  by  attaching  it  to  the  head  of  a post  U,  inserted  into  the  carriage  I 
by  a suitable  neck  V,  formed  in  the  middle  of  the  screw  between  the  right  and  left  threads,  said  neck 
turning  in  a corresponding  box  fixed  in  the  head  of  the  post  U.  By  turning  this  screw  the  jaws  will  be 
moved  simultaneously  in  opposite  directions. 

When  a nut  is  required  to  be  made,  the  piece  of  iron  W to  form  the  same  must  be  held  between  the 
jaws  H H instead  of  the  rod,  and  a tap  X with  a T-head  such  as  that  represented  at  Fig.  3254  must  be 
placed  between  the  dies ; then,  by  inserting  the  tapered  end  of  the  tap  into  the  hole  in  the  centre  of  the 
piece  of  iron  t,o  form  the  nut,  and  turning  the  crank-axle  Cf,  the  thread  will  be  cut  by  the  said  tap. 

The  frame  C containing  the  cog-wheel  and  pinion  may  be  made  to  revolve  horizontally  on  a pivot  or 
centre,  and  the  cog-wheel  may  be  made  the  driver  and  the  pinion  the  carrier  of  the  cutting  tools  and 
dies,  especially  in  cutting  screws  of  small  diameter  where  speed  is  required. 

SCREW  FINISHER — Whipple’s  patent.  (We  copy  from  his  specification.)  The  cutter  or  chaser, 
by  means  of  which  the  threads  are  to  be  cut,  is  the  same  in  all  respects  with  that  described  and  claimed 
by  me  in  the  specification  of  Letters  Patent  for  a machine  for  cutting  the  threads  upon  wood  screws, 
granted  to  me  under  date  of  the  18th  of  August,  in  the  year  1842;  but  the  combination  and  arrange- 
ment of  the  other  parts  of  the  machinery  which  I am  now  about  to  describe,  differ  essentially  from  that 
which  was  the  subject  of  the  patent  above  referred  to. 

Fig.  3255  is  a front  elevation  of  such  a machine. 

Fig.  3256  is  a view  of  the  right-hand  end  thereof. 

Fig.  3257  is  the  top  view,  with  the  omission  of  certain  parts  shown  fully  in  the  next  figure. 

Fig.  3258  is  the  top  view  of  the  apparatus,  into  which  the  blanks  that  are  to  be  cut  are  to  be  fed,  and 
by  which  they  are  successively  presented  to  the  action  of  the  tool  for  cutting  the  thread : most  of  the 
operating  parts  shown  in  this  figure  are  omitted  in  each  of  the  others. 

The  other  figures  represent  parts  in  detail  which  could  not  be  otherwise  fully  shown.  In  each  of  these 
figures,  where  the  same  parts  are  shown,  they  are  designated  by  the  same  letters  of  reference. 

A A is  the  frame-work  of  the  machine,  which  may  be  of  cast-iron.  The  part  A'  is  a circular  horizon- 
tal table,  upon  which  is  sustained  a movable  zone  or  ring  I F,  and  the  apparatus  by  which  it  is  governed 
in  its  motion,  these  parts  being  distinctly  shown  in  Fig.  3258.  The  zone  or  ring  1 1'  rests  loosely  upon 
the  horizontal  table  A',  and  is  kept  in  place  by  means  of  a projecting  circular  rim  N,  Fig.  3258,  attached 
to,  or  in  one  piece  with  the  circular  table  A'.  The  outer  portion  I of  the  ring  has  on  its  periphery  a 
series  of  tubes  a a into  which  the  blanks  are  to  be  fed ; these  tubes  are  countersunk  at  the  upper  ends 
so  as  to  adapt  them  to  the  heads  of  the  blanks,  and  below  the  countersunk  part  a portion  of  each  tube 
is  cut  away,  as  shown  at  a s'  a',  to  admit  the  end  of  the  cutter  or  chaser.  The  blank  which  is  being  cut  is 
made  to  revolve  within  its  tube  by  means  of  a revolving  screw-driver,  which  takes  into  the  nick  on  its 
head,  and  is  operated  in  a manner  to  be  presently  described. 

J J is  the  horizontal  shaft,  which  may  be  connected  with  the  first  mover  for  the  purpose  of  driving 
the  machine;  on  this  shaft  there  is  a bevel-wheel  b which  geers  into  the  bevel-wheel  b',  on  the 
vertical  shaft  C.  On  this  latter  shaft  there  is  an  endless  screw  or  worm  c that  mashes  into  a worm- 
wheel  D D on  the  main  horizontal  shaft  B B,  to  which  it  consequently  gives  motion  ; this  shaft  runs  into 
boxes  a"  a"  attached  to  the  frame.  The  shaft  C passes  up  through  the  table  A',  in  which  it  has  its 
upper  bearing;  its  continuation  is  seen  at  C',  and  to  its  upper  end  is  affixed  the  spur-wheel  e',  which, 
geering  into  the  wheel  g‘  on  a shaft  R,  which  is  that  which  carries  the  screw-driver,  gives  motion 
thereto. 

(I  G,  shown  in  detail  in  Fig.  3264,  is  a bar  which  I will  call  the  vertical  cutter-slide ; this  may  be 
rectangular,  and  it  passes  through  mortises  in  the  bed  A"  and  in  the  upper  part  A'",  Fig.  3256, 
of  the  frame:  in  these  it  slides  up  and  down  freely  as  the  thread  is  chased  by  the  cutter.  The  cutter 
i not  attached  directly  to  the  bar  G,  but  to  the  upper  end  of  a lever  o o which  works  on  a fulcrum- 
pin  in,  by  which  it  is  connected  to  said  bar ; the  lever  o allows  the  cutter  to  move  laterally  to  and 


592 


SCREW  FINISHER. 


from  the  blank  to  be  cut ; the  head  o'  of  this  lever  is  widened  out  for  the  purpose  of  sustaining  the  cut- 
ter, which  is  shown  in  place  at  xx,  Figs.  3257  and  3264. 

This  is  held  in  place  by  the  cap  P,  which  has  a curved  groove  on  its  under  side  to  receive  it,  the 
screw  q pressing  through  said  cap  into  the  head  o'  of  the  lever ; r is  a steel  spring  that  bears  against 
the  inner  side  of  the  lever  o,  serving  to  force  it  back  when  not  pressed  up  by  the  apparatus  by  which 
tire  cutter  is  made  to  operate  .on  the  blanks,  which  I will  now  describe. 

E,  shown  most  distinctly  in  Figs.  3255  and  3256,  is  a cam-wheel  made  fast  on  the  main  horizontal 
shaft  B.  The  periphery  of  this  wheel  is  divided  into  fourteen  equal  parts,  and  is  cut  so  as  to  have  on 
it  thirteen  tooth-like  projections  ddd',  Fig.  3256,  the  part  d'  occupying  two  of  the  fourteen  divisions, 
leaving  twelve,  dd,  equal  in  size.  Each  of  these  projections  operates  as  a cam  in  causing  the  cutter  to 
operate  on  a blank ; the  number  of  equal  projections  determines  the  number  of  times  that  each  blank 
shall  be  acted  on  by  the  cutter,  and  this  number  may  be  varied,  but  that  which  I have  given  is  found 


3055. 


sufficient  for  screws  of  ordinary  size.  To  the  cutter-slide  G is  attached  a hardened  steel  bearing-piece  n, 
the  upper  end  of  which  is  in  the  form  represented,  and  is  kept  in  contact  with  the  projections  d d of  the 
cam-wheel ; this  wheel,  therefore,  by  its  revolution,  will  depress  the  slide  and  carry  the  cutter  down : 
the  cam-teeth  and  the  bearing-piece  n are  made  very  true  and  smooth.  The  faces  of  the  projections  d 
which  act  on  the  piece  n are  finished  to  an  irregular  curve,  which  is  such  as  to  cause  the  direct  down- 
ward motion  of  the  slide  to  be  equal  in  equal  periods  of  time,  the  motion  of  the  wheel  being  uniform. 
The  slide  G is  raised  in  the  following  manner,  after  each  descent:  H is  a steel  spring,  shown  most 
plainly  in  Fig.  3255,  which  presses  on  a lifting-piece  Y that  works  on  a joint-pin  U',  and  bears  against  a 
pin  on  the  back  side  of  the  slide  G.  At  the  time  when  this  lifting  is  effected,  the  cutter  is  drawn  off 
from  the  blank  by  the  action  of  the  gage-wheel  F and  its  appendages. 


SCREW  FINISHER. 


593 


F,  Figs.  3255  and  3256,  is  what  I call  the  gage-wheel,  which  is  affixed  to  the  horizontal  shaft  B ; this, 
wheel  has  a projecting  rim  i i on  its  face,  like  a crown-wheel,  which  is  divided  into  a number  of  parts 
corresponding  with  those  of  the  projections  on  the  cam-wheel,  there  being  thirteen  recesses  or  notches 
ij,  twelve  of  which  are  of  one  size,  whilst  the  other  j'  corresponds  with  the  projection  d'  on  the  cam- 
wheel.  The  gage-wheel  F is  intended  to  regulate  the  feed  of  the  cutter  in  its  successive  actions  on  the 
blank;  under  the  arrangement  described  the  cutter  will,  as  before  remarked,  operate  twelve  times  in 
forming  the  thread  of  each  screw,  the  operation  on  each  being  completed  by  one  revolution  of  the  shaft 
B.  The  cutter  is  forced  up  against  the  blank  in  the  following  manner : K'  is  a lever  which  ■works  on  a 
fulcrum-pin  /,  and  the  end  K'  of  which  bears  upon  the  face  of  the  projecting  rim  i i of  the  gage-wheel 
during  the  time  that  the  cutter  is  operating  upon  the  blank,  when  the  point  K is,  by  the  revolution  of 
the  wheel  F,  brought  opposite  to  one  of  the  recesses  j,  the  lever  o with  its  cutter  is  passed  back  by  the 
action  of  the  spring  r,  and  at  the  same  instant  the  piece  n falls  into  one  of  the  notches  on  the  cam-wheel, 
the  slide  G rising,  consequently,  to  its  original  elevation.  The  lever  k advances  the  cutter  against  a 


blank  by  bearing  against  a sliding-piece  t,  which  bearing  is  regulated  by  means  of  a thumb  screw  s, 
Every  successive  cut  of  the  tool  must,  of  course,  be  to  a greater  depth  than  that  which  preceded  it,  and 
this  is  effected  in  the  following  manner : the  face  of  the  projecting  rim  i i of  the  wheel  F is  not  in  a 
vertical  plane,  but  each  projecting  portion  rises  by  a regular  inclination  beyond  that  which  preceded  it, 
which  rise  amounts,  in  machines  intended  for  cutting  ordinary  |-inch  screws,  to  about  one-tenth  of  an 
inch  in  its  whole  circumference.  By  this  manner  of  forming  the  gage-wheel  is  also  obtained  the  right 
taper  on  the  screw.  T is  a conductor  down  which  the  cliffs  pass  from  the  cutter. 

When  the  cutting  of  a screw  is  to  be  commenced,  the  screw-driver  must  be  forced  down  so  as  to  enter 
the  nick  on  the  blank,  and  when  it  has  been  completed  it  must  be  raised  therefrom,  and  the  zone  or 
l ing  1 1'  must  be  moved  so  far  round  as  to  bring  another  blank  into  the  proper  situation  for  the  action 
of  the  cutter.  The  apparatus  for  depressing  and  raising  the  screw-driver  is  as  follows : on  one  side  of 


594 


SCREW  FINISHER. 


the  cam-wheel  E there  is  attached  a broad  rim  or  hoop  vv,  Fig.  3255,  and  the  situation  of  which 
is  indicated  also  by  the  dotted  lines  V Y,  Fig.  3256  ; this  hoop  is  continuous  for  about  10-llths  of  a 
circle,  about  1-1 1th  of  it  being  removed,  as  at  the  part  h.  The  outer  surface  of  it  is  made  perfectly 
.rue  and  smooth,  and  there  bears  on  it  one  end  of  a crooked  lever  Q,  which  is  shown  separately  in  Fig. 
3263  ; its  end  Q is  that  which  bears  on  the  hoop  UU;  it  has  a fulcrum-pin  at  Q".  K"  is  a pin  attached 
to  the  upper  end  of  this  lever,  which  pins  enter  a notch  or  opening  in  a piece  k',  to  which  is  attached 
tlie  vertical  sliding-rod  P that  makes  a part  of  the  sliding-frame  P P,  Fig.  3256,  which  frame  sustains 
the  shaft  of  the  screw-driver : when,  by  the  revolution  of  the  cam-wheel,  the  end  Q'  of  the  lever  Q,  is 
brought  opposite  to  the  opening  h in  the  hoop  U U it  falls  into  it,  and  the  sliding-frame  P with  the 
screw-driver  attached  to  it  is  raised ; the  lever  Q is  kept  in  contact  with  the  hoop  U U by  the  action  of 
a spring  l'  that  bears  against  it,  and  is  attached  to  the  circular  table  A'.  The  passing  of  the  end  of  the 
lever  Q into  the  recess  in  the  hoop  U occurs  at  the  moment  that  a screw  has  been  finished.  R,  Figs.  3255 
and  3256,  is  the  shaft  of  the  screw-driver;  this  shaft  passes  through  and  revolves  within  in  the  arms 
0 0,  Fig.  3256,  making  a part  of  the  stationary  screw-driver  frame.  By  means  of  a feather  the  shaft  R 
slides  freely  up  and  down  through  the  wheel  g',  which  is  driven  by  the  wheel  c.  O,  Fig.  3258,  is  the 
bottom  plate  or  basis  of  the  frame  0 O,  which  is  fastened  on  to  the  top  of  the  circular  table  A by  screws, 
as  at  f"  /".  The  upper  end  of  the  shaft  R is  connected  to  the  sliding-frame  P by  the  springs  in!  n\  Fig. 
3256.  The  lowermost  of  these  springs  serves  to  lift  it,  and  the  upper  one,  by  means  of  the  thumb- 
screw o’,  serves  to  adjust  it  to  the  different  thicknesses  of  the  heads  of  the  blanks,  the  shaft  R is  de- 
pressed, and  the  screw-driver  kept  in  contact  with  the  blank  by  the  bearing  of  the  lever  Q on  the 
hoop  U U. 


The  removing  of  the  finished  screw  from  the  tubes  a is  effected  by  the  aid  of  the  same  hoop  TJ  that  is 
concerned  in  the  depressing  and  raising  of  the  screw-driver.  S,  Figs.  3255  and  3256,  is  a stationary 
tubular  rod  placed  vertically,  which  receives  within  it  a small  sliding-rod  p'\  there  is  a slot  along  the 
rod  S,  and  a small  arm  r"  attached  to  the  sliding-rod  p passes  through  this  slot  and  bears  upon  the 
periphery  of  the  hoop  U until  it  arrives  at  the  opening  li ; whilst  it  bears  on  the  hoop  the  rod  p'  is  de- 
pressed, but  when  it  enters  the  opening  h the  spiral  spring  r'  forces  the  rod  pf  up,  which,  passing  into 
the  tube  containing  the  last  but  one  finished  screw,  removes  it,  and  it  falls  into  a receiver. 

The  apparatus  used  for  causing  the  zone  or  ring  1 1'  to  revolve  and  carry  a blank  to  the  distance  ne- 
cessary to  its  being  operated  on  by  the  cutter,  is  shown  in  Figs.  3255,  3258,  3259,  3260,  3261,  and  3262 
One  side  of  the  worm-wheel  D D is  widened  out,  so  as  to  leave  a guide-groove  fff  formed  upon  it  ■ 
this  groove  passes  uniformly  round  the  wheel,  excepting  at  the  point  f.  Fig.  3255,  where  it  forms  an 
angle,  as  represented.  This  groove  receives  the  pin  g which  constitutes  the  end  of  a short  arm  g",  seen 
separately  in  Fig.  3262  ; from  this  arm  a shaft  M rises  vertically  and  passes  through  the  circular  table 
A',  and  is  firmly  attached  to  an  arm  or  lever  K which  rests  on  the  top  of  the  table,  as  seen  in  Fig.  3258  ; 
the  piece  K is  shown  separately  in  Fig.  3261,  and  the  part  of  it  to  which  the  shaft  M is  attached  is  rep- 
resented by  dotted  lines  in  Fig.  3258.  Whilst  the  pin  g remains  in  the  direct  part  of  the  groove//,  the 
piece  K remains  stationary,  but  where  it  enters  the  angular  part/'  the  shaft  M is  made  to  revolve  par- 
tially back  and  forth,  and  carries  with  it  the  piece  K.  The  arm  g"  is  situated  below  the  table  A' ; the 
shaft  M to  which  it  is  attached  has  its  step  in  the  stud  d‘.  To  cause  the  pin  g to  pass  readily  back  into 
the  straight  part  of  the  groove/,  a spring  s',  the  lower  end  of  which  is  seen  in  Fig.  3255,  is  made  to  bear 
against  said  pin,  as  shown  in  Fig.  3262.  The  finger  Y on  the  piece  K draws  back  the  bolt  y,  Fig. 
3258,  seen  separately  in  Fig.  3259,  so  as  to  relieve  it  from  one  of  a series  of  notches  on  the  interior  edge 
of  the  ring  1 1'.  These  notches  x x",  &c.,  correspond  in  number  and  position  with  the  tubes  for  the  blanks, 
and  it  will  be  manifest  that  the  bolt  y,  when  inserted  in  one  of  these  notches,  will  keep  the  ring  sta- 
tionary. The  bolt  y is  forced  into  the  notches  by  means  of  a spiral  spring  z,  acting  against  the  plate  O 


SCREWS,  MACHINE  FOR  NICKING. 


595 


To  the  piece  K is  also  connected  the  feed-hand  L by  a joint-pin  a'";  this  feed-hand  carries  the  ring  1 1' 
round  to  the  requisite  distance.  The  steel  spring  b'",  which  has  a bearing  on  the  pin  c,  serves  to  throw 
the  feed-arm  forward  to  the  proper  position  to  bear  against  the  angle  of  one  of  the  notches,  as  seen  at  x " 
In  describing  the  various  parts  of  this  machine,  I have  also  shown  the  manner  in  which  they  are  in- 
tended to  operate,  but  I will  now  give  a general  view  of  the  action  of  the  whole.  The  tubes  a a in 
the  horizontal  ring  I V are  to  be  kept  supplied  with  blanks,  which  are  to  be  fed  in  by  hand.  Imme- 
diately preceding  the  first  operation  of  the  cutter  on  a blank,  the  lever  Q will  have  occupied  the  recess 
li  in  the  hoop  U on  the  cam-wheel,  and  the  lever  lv  the  recess  j'  in  the  gage-wheel;  and  the  machine 
being  in  motion,  the  cutter-slide  G G will  be  raised  by  the  action  of  the  spring  H on  the  joint-piece  u. 

3264. 


At  the  commencement  of  the  ascent  of  the  cutter-slide,  the  cutter  will  be  thrown  back  by  the  action 
of  the  spring  r on  the  lever  o.  During  this  period  of  time  the  revolving  of  the  hoop  U on  the  cam-wheel 
will  bring  the  end  of  the  lever  Q,  which  had  occupied  the  recess  h,  in  contact  with  said  hoop,  on  the 
periphery  of  which  it  will  rise,  thereby  lowering  the  screw-driver,  when  the  screw-driver  will  enter  the 
nick  on  the  blank,  which  it  will  cause  to  revolve  rapidly  ; the  lever  K also  at  the  proper  instant  will 
leave  the  recess  on  the  gage-wheel  and  bear  on  a projecting  part  of  its  rim,  bringing  the  cutter  into 
contact  with  the  blank.  That  one  of  the  tooth-like  projections  on  the  cam-wheel,  which  is  next  to  the 
double  one,  will  at  the  same  time  be  in  contact  with  the  steel  bearing-piece  n,  and  the  cutter  will  be 
thereby  caused  to  make  its  first  cut,  which  being  succeeded  by  the  action  of  the  remaining  cam-teeth, 
completes  the  screw. 

At  the  time  of  the  completion  of  the  screw  last  cut,  the  revolution  of  the  cam-wheel  will  have  brought 
the  hoop  U into  the  position  in  which  the  end  of  the  lever  Q will  enter  the  recess  h,  and  the  screw- 
driver will  be  lifted. 

At  this  time  the  cutter  will  have  been  withdrawn  from  the  screw,  and  the  point  g of  the  arm  g", 
traversing  in  the  guide-groove  ff  of  the  worm-wheel,  will  have  attained  its  greatest  variation  from  its 
direct  course  in  the  angular  part  of  the  said  groove  f,  in  passing  and  returning  along  which  it  will  have 
given  the  revolving  motion  to  the  shaft  M necessary  to  the  operation  of  the  parts  concerned  in  the  shift- 
ing of  the  ring  1 1'  one  notch,  in  the  manner  above  described,  which  will  bring  a fresh  blank  into  a situ- 
ation to  be  operated  on  by  the  cutter,  and  will  also  bring  the  cut  screw  directly  over  the  rod  p'.  This 
screw  will  be  removed  by  the  passing  of  the  small  arm  r"  into  the  recess  h by  the  revolution  of  the 
hoop  U,  which  will  leave  the  rod  p'  free  to  rise  by  the  action  of  the  spiral  spring  r'\ 

SCREWS— MACHINE  FOR  NICKING.  By  II.  L.  Pierson.  In  this  machine  the  blanks  or  screws 
to  be  nicked  are  fed  or  placed  in  holes  made  radially  in  the  periphery  of  a carrying-wheel  composed  of 
two  plates,  the  holes  being  made  at  the  junction  of  the  two  pilates,  and  by  the  rotation  of  this  wheel 
they  are  carried  up  to  and  passed  under  a cutter  that  forms  the  nick ; they  are  griped  and  held  tight 
during  that  operation,  and  then,  by  the  further  rotation  of  the  wheel,  are  liberated  and  discharged. 
The  nature  of  this  invention  consists  in  griping  the  blanks  in  recesses  made  radially  in  the  face  of  a 
wheel  by  making  pressure  on  one  or  both  sides  as  the  wheel  rotates,  so  that  the  blanks  may  be  dropped 
into  the  holes  or  recesses  with  their  heads  outwards,  and  griped  while  passing  under  the  nicking  cutter ; 
aud  then,  by  the  further  rotation  of  the  wheel,  liberated  that  they  may  be  discharged. 

In  Figs.  3265  and  3266  A A is  the  frame-work  of  the  machine.  B is  a shaft  to  which  the  driving 


596 


SCREWS,  MACHINE  FOR  NICKING. 


power  is  applied,  upon  which  there  are  two  pulleys  C C,  with  bands  for  driving  the  different  parts  of  the 
machinery.  D is  a whirl  on  the  shaft  E,  which  carries  the  circular  cutter  F,  by  which  the  screws  art 
to  be  nicked.  A band  from  the  whirl  C drives  the  whirl  G on  the  shaft  H,  upon  which  there  is  an  end- 
less screw  or  worm  I,  which  takes  into  a pinion  J,  upon  the  upper  end  of  a vertical  shaft,  the  lower  end 
of  which  runs  into  a bridge-tree  or  shifting-bar,  the  end  of  which  is  shown  at  K,  Fig.  3266.  This  shaft 
carries  an  endless  screw  or  worm  L,  which  takes  into  and  drives  the  toothed  wheel  M,  Fig.  3265,  which 
toothed  wheel  is  on  the  same  shaft  with  that  of  N for  holding  the  blanks ; the  lower  end  0 of  the  verti- 
cal shaft  being  seen  in  Fig.  3266  ; the  connecting-rod  P acting  upon  the  bridge-tree  or  shifting-bar  K. 

The  blank-wheel  N is  in  two  parts,  divided  through  its  plane,  as  shown  by  the  line  along  its  periph- 


ery ; one  of  these  parts  is  fixed  firmly  on  its  axle,  whilst  the  other  part  slides  upon  a square  eye,  or 
otherwise,  upon  the  axle,  and  is  capable  therefore  of  receding  from  the  fixed  part,  although  it  revolves 
with  it.  The  periphery  of  this  wheel  is  perforated  with  holes  at  the  junction  of  its  two  parts,  as  shown 
in  the  figures,  which  holes  are  of  such  size  as  to  receive  and  hold  the  blanks  which  are  to  be  nicked.  To 
cause  the  two  portions  of  this  wheel  to  grip  the  blank  while  it  is  being  nicked,  there  is  a friction  roller 
which  bears  against  the  outer  edge  of  the  periphery  of  the  movable  part,  immediately  under  the  circu- 
lar cutter.  The  dotted  lines  Q,  Fig.  3265,  mark  its  situation,  which  is  opposite  to  the  screw-nut  R, 
Fig.  3266,  which  confines  the  friction-wheel  box  in  its  place.  To  react  against  this  friction  roller,  a simi- 
lar one  is  placed  opposite  to  it,  and  bears  upon  the  fixed  portion  of  the  blank-wheel ; the  bar  S is  to 
sustain  this  friction-wheel.  The  shaft  which  carries  the  saw  is  raised  or  lowered  by  means  of  the  ad- 
justing screws  TT,  and  by  this  means  the  depth  of  the  nick  is  perfectly  regulated. 

3206. 


Having  thus  fully  described  the  construction  of  this  machine,  its  operation  will  be  readily  understood. 
The  shaft  B being  made  to  revolve  by  any  motive  power,  the  blanks  are  dropped  into  the  holes  in  the 
blank-wheel  N as  it  approaches  the  cutter,  and  are  held  firmly  whilst  being  cut  by  the  pressure  of  the 
friction  rollers ; and  being  released  from  this  pressure,  they  fall  out  by  their  own  gravity  as  they  are 
jarried  round  to  the  lower  part  of  the  machine. 


SCREWS,  MACHINE  FOR  SHAVING  AND  TURNING. 


597 


It  will  be  obvious  from  the  foregoing,  that  instead  of  having  one  part  of  the  wheel  firmly  attached 
to  the  shaft,  that  both  parts  may  be  loose  thereon  provided  they  are  so  connected  witli  it  as  to  be  car- 
ried around  by  its  rotation,  and  admit  of  being  pressed  together  to  grip  the  blanks  firmly  while  passing 
under  the  operation  of  the  cutter  to  be  nicked,  whether  this  cutter  be  a rotating  cutter  or  any  other  kind 
of  instrument  for  this  purpose,  although  the  rotating  cutter  is  deemed  to  be  the  best.  Instead  of  the 
rollers  to  press  together  the  two  parts  of  the  carrying-wheel,  cheeks  may  be  substituted,  but  with  less 
advantage  on  account  of  the  friction  of  the  rubbing  surfaces  ; and  instead  of  making  use  of  two  rollers, 
die  one  that  bears  against  the  face  of  the  permanent  part  of  the  wheel  may  be  dispensed  with  by  mak- 
ing this  part  of  the  wheel  very  strong,  and  the  shaft  to  run  in  firm  bearings  that  will  afford  sufficient 
strength  to  resist  the  pressure  required  to  grip  the  blanks  firmly  while  being  nicked.  It  will  also  be 
obvious  tliat  the  two  parts  of  the  wheel  may  be  kept  apart  for  the  free  reception  and  delivery  of  the 
blanks  either  by  a boss  or  shoulder  on  the  shaft,  or  by  the  introduction  of  something  between  them,  or 
by  any  other  equivalent  means ; although  a projection  boss,  or  shoulder  on  the  shaft,  is  the  simplest  and 
most  effective. 

SCREWS,  MACHINE  FOR  SHAVING  AND  TURNING.  Crum  & Pierson’s  patent.  The  na- 
ture of  the  first  part  of  this  invention  or  improvement  in  the  before-mentioned  machine  consists  in  giv- 
ing to  the  frame  or  carriage  that  carries  the  carrying  and  holding  wheel  (sometimes  misnamed  the  feed- 
ing-wheel) an  intermittent  reciprocating  motion  to  withdraw  the  turned  blank  and  insert  the  points  oi 
others  in  the  jaws,  in  succession,  instead  of  giving  an  endwise  motion  to  the  mandrel  for  this  purpose  as 
heretofore ; and  also  in  giving  to  the  carrying-wheel  an  intermittent  rotary  motion  to  present  a new 
blank  to  the  jaws  preparatory  to  the  insertion  of  the  same  into  the  jaws  by  the  motion  of  the  carriage. 
And  the  second  part  of  this  invention  consists  in  shaving  the  under  and  upper  surface  of  the  heads, 
within  the  rim  of  the  carrying  and  holding  wheel,  by  means  of  a tool  properly  adapted  to  the  purpose, 
which  is  attached  to  the  end  of  a vibrating  tool-holder,  that  receives  its  appropriate  motions  at  right 
ano-les  to  the  axes  of  the  blank  from  a cam  on  the  main-shaft. 

z 


In  Figs.  3261,  3268,  and  3269,  a represents  a frame  properly  adapted  to  the  purpose,  but  which  may 
be  changed  at  the  discretion  of  the  constructor.  On  the  table  b of  this  frame,  and  near  one  end  thereof, 
there  are  two  ways  c c,  in  which  slides  a carriage  d,  that  carries  the  carrying  and  holding  wheel  e,  for 
the  purpose  of  withdrawing  from  the  jaws  the  blank  that  has  been  turned,  and  presenting  a new  one  to 
the  jaws. 

The  carrying  and  holding  wheel  e is  made  with  a projecting  rim  f in  which  spaces  are  cut  out  at 
equal  given  distances  apart,  and  extending  from  the  fac.e  of  the  wheel  to  the  middle  of  the  width  of  the 
projecting  rim,  and  in  these  recesses  are  fitted  dies  g,  which  are  secured  by  screws  to  the  wheel — the 
holes  that  receive  the  screw-blanks  are  made  half  in  the  end  of  the  dies  and  the  other  half  in  the  edge 
of  the  recesses,  so  that  by  sliding  the  dies  the  holes  can  be  adapted  to  different  sizes  of  screw-blanks. 
The  wheel  thus  formed  is  hung  on  the  end  of  a shaft  i,  which  turns  in  standards  jj  of  the  carriage  d,  and 
it  is  turned  the  distance  required  at  each  operation  by  a clutch-wheel  l,  one-half  of  which  is  attached 
permanently  to  the  shaft,  and  the  other  to  a cog-wheel  K,  that  turns  freely  on  the  shaft,  the  cogs  of  the 
wheel  Iv  engaging  with  a rack  M,  that  slides  freely  in  the  standards  of  the  carriage,  so  that  when  this 
carriage  is  moved  back  from  the  jaws  during  the  operation  of  the  machine,  the  end  of  the  rack  strikes 
against  the  end  of  a set-screw  N attached  to  the  frame  which  slides  the  rack  and  turns  the  carrying- 
wheel  the  required  distance  to  take  the  turned  blank  from  the  jaws  and  present  another  to  be  turned ; 
and  on  the  return  motion  of  the  carriage  the  other  end  of  the  rack  strikes  against  another  set-screw  o, 
which  forces  it  back,  and  also  the  cog-wheel  and  that  half  of  the  clutch-wheel  attached  to  it,  the  form  of 
the  clutch-cogs  being  such  as  to  permit  the  two  halves  to  turn  in  that  direction  independently  of  one 
another,  the  movable  half  being  forced  towards  the  other  by  the  tension  of  a helical  spring  p out  the  shaft. 

The  blanks  are  fed  into  the  holes  of  the  carrying-wheel  e by  hand,  with  the  heads  inwards,  and  the 
required  motions  are  given  to  the  wheel  in  the  following  manner  : An  elbow-lever  g,  which  turns  on  a 


598 


SCREWS,  MACHINE  FOR  SHAVING  AND  TURNING. 


32C8. 


fulcrum-pin  r,  has  the  end  of  one  arm  working  in  a slot  s of  the  carriage  d,  while  the  end  of  the  other 
arm  is  provided  with  a roller  or  wrist  which  runs  in  a cam-groove  t,  made  in  the  face  of  a plate  u,  on  ;; 
shaft  v , that  makes  half  a revolution  for  each  complete  operation  ; that  is,  for  every  blank  that  is  intro- 
duced, turned  and  discharged;  and  the  cam-groove  is  formed  so  that  from  the  point  1 to  2,  in  the  direc- 
tion the  reverse  of  the  arrow,  it  runs  out  of  the  circle  to  move  the  carriage,  and  with  it  the  carrying- 
wheel  from  the  jaws  w,  to  remove  a blank  that  has  had  the  head  turned ; and  from  the  point  2 to  3,  in 
the  same  direction,  the  groove  runs  towards  the  shaft  by  a curve  the  reverse  of  that  from  1 to  2,  for  the 
purpose  of  moving  the  carrying- wheel  towards  the  jaws  to  present  a new  blank,  the  previous  motion  oi 
the  carriage  from  the  jaws  having  turned  the  carrying-wheel  a distance  equal  to  a space  between  two 
of  the  holes  in  the  dies  to  present  a new  blank,  and  then  from  the  point  3 to  4 the  groove  is  concentric 
to  hold  the  carrying-wheel  in  the  same  position  while  the  head  of  a blank  is  being  turned.  The  other 
half  of  the  cam-groove  is  similar  to  the  one  described  to  repeat  the  operation.  So  soon  as  the  carrying- 
wheel  has  completed  its  motion  towards  the  jaws  and  while  that  part  of  the  cam-groove  from  the  point 
3 to  4 is  passing  over  the  end  of  the  lever  q , the  carrying-wheel  is  held  firmly  in  that  position  to  hold 
the  blank  firmly  while  it  is  being  rotated  by  the  jaws  and  acted  on  by  the  cutter ; and  this  is  done  by 
the  point  of  a follower  x,  that  is  forced  by  a helical  spring  around  it  to  enter  one  of  the  series  of  holes 
y in  the  face  of  the  wheel,  and  preparatory  to  turning  the  wheel  to  shift  a blank,  a cam  z on  the  periph- 
ery of  the  cam-plate  u forces  up  a sliding  wedge-piece  a',  that  acts  on  a follower  x,  to  force  it  back  out 
of  the  hole  in  the  wheel,  and  the  moment  that  the  cam  passes  the  follower  x is  in  a condition  to  be 
forced  by  the  tension  of  the  spring  into  the  next  hole  when  the  wheel  is  turned  round  to  present  another 
blank  to  the  jaws. 

The  screw-blanks  thus  presented  are  caught, 
gripped,  and  rotated  by  the  pair  of  jaws  w,  that  are 
minted  to  the  end  of  an  arbor  or  mandrel  b\  which 
runs  in  standards  or  puppets  c c\  and  rotated  by  a 
belt  d'  from  a pulley  e‘  on  the  driving-shaft/'.  This 
mandrel  is  hollow,  and  within  it  there  is  a sliding- 
rod  </',  one  end  of  which  is  jointed  by  links  K K with 
the  levers  of  the  jaws,  and  the  other  end  projects 
out  beyond  the  back  of  the  mandrel,  and  is  there 
provided  with  two  collars  i i',  that  embrace  the 
forked  end  of  a lever  / that  turns  on  a fulcrum-pin  k\ 
the  other  end  being  provided  with  a roller  or  wrist 
that  runs  in  a cam-groove  l'  in  the  periphery  of  a 
wheel  rti  on  the  shaft  of  the  cam  that  operates  the 
carrying-wheel.  The  form  of  this  cam-groove  is  such 
that  from  the  point  1 to  2 it  runs  by  a sudden  curve 
to  the  left  to  open  the  jaws  just  as  the  carrying- 
wheel  begins  to  move  from  the  jaws  to  draw  out  the 
blank  that  has  been  turned ; from  2 to  3 for  a short 
distance  it  runs  ha  the  direction  of  the  periphery  to 
give  time  for  the  carrying-wheel  to  present  a new 
blank,  and  then  from  the  point  3 to  4 it  runs  by  a 
curve  the  reverse  of  the  one  from  1 to  2,  to  close  the 
jaws  and  grip  the  end  of  a blank,  and  then  the 
groove  runs  in  the  direction  of  the  periphery  to  com- 
plete half  the  circumference  from  the  point  1,  the 
groove  for  the  other  half  of  the  circumference  being 
a repetition  of  the  first  half  to  repeat  the  operation. 

It  will  be  obvious  from  the  foregoing  and  the  fig- 
ures that  the  sliding  of  the  rod  in  the  mandrel  by  its 
connections  will  open  and  close  the  jaws.  So  soon 
as  the  blank  has  been  presented  and  gripped  the 
cutter  n'  is  moved  up.  The  cutting  edge  of  this 
cutter  is  somewhat  in  a A form,  the  edge  d being 
nearly  at  right  angles  with  the  axis  of  the  screw- 
blank  to  turn  the  top  of  the  head,  and  the  other  edge 

v'  forming  the  required  angle  therewith  to  turn  the  under  surface  of  the  head.  This  cutter  is  fitted  to 
a stock  q,  and  slides  therein  that  its  cutting  edge  may  be  properly  set  by  a screw  r.  The  cutter-stock 
turns  on  a fulcrum-pin  s'  and  it  rests  on  the  upper  end  of  a sliding-bar  t‘,  provided  with  a friction-roller 
u at  the  lower  end,  which  is  acted  upon  at  the  appropriate  time  ; that  is,  the  moment  that  the  blank 
is  griped  by  the  jaws,  by  a cam  v on  the  same  shaft  with  the  other  cams  before  described ; this  cam 
suddenly  runs  out  from  the  axis  to  carry  the  cutter  to  the  head  of  the  blank  and  then  runs  for  a short 
distance  by  a slight  eccentricity  to  force  the  cutter  gradually  against  the  blank  until  the  head  thereof  is 
sufficiently  reduced  or  turned,  at  which  point  the  cam  suddenly  runs  towards  the  axis  that  the  cutter 
may  be  drawn  back  from  the  blank  by  the  weight  of  the  cutter-stock.  There  are  two  cutter-cams  v 
to  correspond  with  the  double  cams  for  operating  the  jaws  and  the  carrying-wheel;  but  it  will  be  ob- 
vious that  by  doubling  the  motion  of  this  cam-shaft  relatively  to  the  motions  of  the  other  parts  of  the 
machine,  that  the  cams  may  be  single.  The  cam-shaft  receives  its  motions  from  the  mandrel  by  an 
endless-screw  w on  the  latter,  which  actuates  a spur-wheel  x on  one  end  of  a shaft  y , the  other  end  o! 
which  has  a bevel  cog-wheel  z , the  cogs  of  which  take  into  the  cogs  of  a similar  wheel  a?  on  the  cam 
shaft,  shown  by  dotted  lines.  As  stated  before,  the  screw-blanks  are  placed  in  the  carrying-wheel,  and 
carried  up  by  its  rotation,  and  when  presented  to  the  gripping-jaws  the  point  is  forced  against  a stop  L 


SCREWS,  MACHINE  FOR  THREADING. 


599 


within  the  jaws  by  the  motion  of  the  carrying-wheel.  And  after  being  turned,  the  further  motion  o I 
the  wheel  carries  them  up,  their  heads  resting  on  to  a curved  rest  c1 , which  is  so  curved  at  <P  as  to  per- 
mit them  to  fall  out  by  their  weight  so  soon  as  they  reach  the  top. 

By  doubling  the  length  of  the  carriage,  and  putting  another  carrying-wheel  on  the  other  end  of  the 
shaft,  as  represented  iii  Figs.  3267  and  3268,  and  putting  up  a duplicate  of  the  mandrel,  gripping-jaws, 
and  cutting  tools,  with  their  connections,  the  cam-shaft  and  cams  will  answer  for  two  machines,  with 
the  exception  of  the  cutter-cams,  which  must  also  be  doubled  to  avoid  complexity ; but  even  these  mav 
be  dispensed  with  by  changing  the  form  of  the  cutter-stock  and  the  slide  that  communicates  motion 
io  it  from  the  cutter-cam. 


3269. 


SCREWS,  MACHINE  FOR  THREADING  : John  Crum’s.  Figs.  3270,  3271,  3272,  3273,  and  3274. 
The  nature  of  this  invention  consists  in  giving  a reciprocating  motion  to  a carriage,  in  which  is  hung  the 
shaft  of  the  carrying  and  holding  wheel  to  draw  the  stem  of  the  blank  from  the  dies  as  they  rotate  to 
give  the  pitch  to  the  thread,  and  to  return  it  to  the  dies  for  a succession  of  operations  until  the  thread  is 
cut,  this  series  of  motions  being  given  by  a simple  segment  cog-wheel,  the  cogs  of  which  act  alternately 
on  an  upper  and  a lower  rack  connected  with  the  carriage.  And  also  in  giving  to  the  carrying  and 
holding  wheel  an  intermittent  rotary  motion  (to  remove  a threaded  screw  and  present  a blank)  from  c 
wheel  below,  provided  with  a pin  on  its  face,  which,  at  every  rotation,  lifts  a lever,  the  upper  end  ot 
which  is  provided  with  a hand  that  acts  on  the  teeth  of  a ratchet-wheel  on  the  shaft  of  the  carrying- 
wheel  to  turn  it  the  required  distance  for  the  presentation  of  a blank,  the  wheel  that  carries  the  lifting- 
pin  being  turned  a part  of  a revolution  for  each  cut  of  the  dies  by  an  arm  on  the  shaft  of  the  cam  that 
closes  the  dies ; the  number  of  teeth  or  pins  on  the  wheel  that  are  to  be  struck  by  the  arm  on  the  crank 
shaft  being  such  for  each  pin  on  the  other  face  of  the  wheel,  as  to  correspond  with  the  number  of  cuts  to 
be  given  by  the  dies  for  the  completion  of  the  thread  of  the  screw. 

The  nature  of  this  invention  also  consists  in  holding  the  blanks  while  under  the  operation  of  the  dies 
by  the  pressure  of  a spring-roller  within  the  rim.  And  the  last  part  of  this  invention  consists  in  closing 
the  dies  for  the  cutting  of  the  threads  by  means  of  a cam,  which  makes  one  revolution  for  each  cut,  and 
acts  by  means  of  a sliding-rod  on  a lever  that  forces  a rod  in  the  hollow  arbor  of  the  jaws  to  close  them 
when  this  is  combined  with  a sliding  wedge-piece  interposed  between  the  sliding-rod  and  the  lever  ti 
increase  the  depth  of  the  cut  at  each  operation,  the  said  wedge-piece  being  made  to  slide  for  this  pur- 
pose by  means  of  another  cam  combined  therewith. 

In  the  accompanying  figures,  a represents  a frame,  properly  adapted  to  the  purpose,  and  b the  main 
driving-shaft  with  a pulley  c,  from  which  a belt  cl  passes  to  a pulley  e on  a hollow  mandrel  f that 
carries  the  jaws  g g,  in  which  are  secured  dies  or  chasers  It  h made  in  the  usual  manner.  The  jaws  are 
joined  to  ears  ii  on  the  end  of  the  mandrel  with  springs  jj  interposed,  that  tend  constantly  to  keep  the 
jaws  open,  and  the  rear  end  of  the  levers  pass  into  the  mandrel  and  are  then  acted  on  to  force  the  dies 
together  in  threading  the  screw  by  the  conical  end  of  the  rod  Iv,  that  slides  within  the  mandrel.  Tbf 


SCREWS,  MACHINE  FOR  THREADING. 


GOO 


rear  end  of  this  rod  passes  out  of  the  mandrel  and  is  acted  on  -when  the  jaws  are  to  be  closed  by  the 
point  of  an  adjustable  screw  l on  the  upper  end  of  a lever  m,  the  lower  arm  of  the  said  lever  being 
acted  upon  by  a sliding-rod  n that  bears  against  the  face  of  a cam  o on  a transverse  shaft  p.  The  form 
of  this  cam  is  sucli  that  from  the  point  1 to  2,  extending  one-half  of  the  circumference,  it  is  concentric; 
at  the  point  2 it  suddenly  runs  out  from  the  centre  to  close  the  jaws,  and  therefore  to  make  the  dies 
grasp  the  shank  of  the  blank,  and  then  from  this  sudden  swell  to  the  point  3 it  gradually  runs  out 
from  the  centre  to  increase  the  bight  of  the  dies,  and  then  by  a radial  line  it  runs  back  to  the  point  of 
beginning,  to  permit  the  springs  to  force  open  the  jaws  that  the  screw-blank  may  be  run  back  for  a repe- 
tition of  the  operation.  This  cam  receives  its  motions  from  the  mandrel  by  a train  of  cog-wheels  qr  s,  the 
one  q being  on  the  shaft  of  the  cam  and  engaging  with  the  cogs  of  the  one  r,  which  is  on  the  shaft  of  the 


3270. 


wheel  s that  is  actuated  by  an  endless  screw  t on  the  mandrel.  Between  the  lower  arm  of  the  lever  m 
and  the  sliding-rod  n there  is  interposed  a wedge-formed  slide  n'  placed  at  right  angles  with  the 
sliding-rod  n.  The  end  v of  this  slide  is  forced  by  a spring  w against  the  face  of  a series  of  cam- 
formed  projections  x on  the  face  of  a wheel  y on  a shaft  z,  the  periphery  of  the  said  wheel  being  pro- 
vided with  teeth  a',  which  strike  against  a pawl  or  hand  b'  jointed  to  the  main  frame,  the  shaft  of  the 
said  wheel  y having  its  bearings  in  a frame  a?  attached  to  and  moved  by  the  lever  rn,  so  that  at  every 
back  motion  of  the  lower  end  of  this  lever  to  open  the  jaws  the  wheel  y is  turned  a portion  of  a revo- 
lution, that  the  cam-formed  projections  x may  act  on  the  end  of  the  wedge-formed  slide  and  force  it 
back,  and  thus  cause  the  threading-cam  at  each  operation  to  close  the  cutting-dies  more,  and  in  this 
way  complete  the  cutting  of  the  thread  by  a series  of  operations.  The  cam-formed  projections  x are  as 
series  of  planes  inclined  to  the  plane  of  the  face  of  the  wheel  from  which  they  project,  and  the  length 
of  each  is  such,  relatively  to  their  motion,  as  that  each  shall  move  its  whole  length  for  the  complete 
cutting  of  one  screw ; and  of  course  the  number  of  these  cam-formed  projections  will  depend  on  the 
diameter  of  the  wheel  to  which  they  are  attached  and  to  the  extent  of  the  motion  of  the  said  wheel. 

3271. 


The  screw-blanks  c'  are  inserted  in  holes  in  the  rim  d'  of  what  is  called  the  carrying  and  holding 
wheel  e',  the  rim  being  made  to  project  from  the  face  of  the  wheel  sufficiently  for  this  purpose.  The 
shaft  f of  this  wheel  runs  in  standards  g'  of  a carriage  h'  that  runs  on  ways  i'i',  and  this  carriage 
receives  a reciprocating  motion  to  move  the  blank  towards  and  from  the  chasers  or  dies  by  a segment 
_og-wheel  j on  the  shaft  of  the  threading-cam.  The  cogs  extend  over  a little  less  than  one-half  of  the 
oircumference,  and  alternately  act  on  the  teeth  of  a lower  rack  k'  to  move  the  carrying-wheel  towards 
the  cutting-dies,  and  then  on  the  cogs  of  an  upper  rack  l'  to  run  it  back  to  form  the  thread,  the  said 
racks  being  formed  in  the  opening  of  a bar  attached  to  the  carriage  of  the  carrying-wheel.  In  this  way 
the  motions  back  anti  forth  of  the  carriage  are  given  to  determine  the  pitch  of  the  threads  and  to  return 
the  screw  for  the  repetition  of  the  operation. 

So  soon  as  a screw  has  been  threaded  it  must  be  carried  away  and  a blank  presented  to  the  dies. 
This  is  done  in  the  following  manner:  On  the  shaft  of  the  carrying-wheel  there  is  a ratchet-wheel  m', 
which  is  turned  by  a hand  n'  on  the  end  of  a lever  o'  that  turns  on  a fulcrum  at  p' ; the  lower  arm  is  bent 


SCREWS,  MACHINE  FOR  THREADING. 


601 


as  at  q',  so  that  when  lifted  the  hand  on  the  upper  end  turns  the  ratchet-wheel,  and  with  it  the  carry' 
ing-wheel,  the  required  distance  to  carry  off  the  threaded  blank  and  present  a new  one.  The  lever  is 
operated  in  the  following  manner : On  the  threading-cam  shaft  there  is  an  arm  r'  which,  at  every  rota- 
tion of  the  shaft,  strikes  one  of  a series  of  pins  s'  projecting  from  a wheel  t'  to  turn  it  a distance  equal 
to  the  space  between  the  centres  of  any  two  of  these  pins,  and  on  the  other  face  of  this  wheel  there  is  a 
pin  u'  which,  at  every  entire  revolution  of  the  wheel,  strikes  under  the  bent  arm  of  the  lever  o'  and 
gives  it  the  requisite  motion  to  turn  the  carrying-wheel.  Back  of  the  lever  o'  there  is  a standard  a? 
with  a set-screw  62,  against  which  the  lever  strikes  when  thrown  back  by  the  weight  of  the  bent  part  q\ 
so  that  by  the  set  of  this  screw  the  extent  of  motion  of  the  lever  and  the  carrying-wheel  can  be 
determined.  The  position  of  the  arm  r on  the  segment  cog-wheel  shaft  relatively  to  the  segment  of 
cogs  should  be  such  that  the  carrying-wheel  will  be  turned  for  removing  the  threaded  screw  and  pre- 
senting a blank  when  the  carriage  is  farthest  from  the  jaws.  And  the  number  of  pins  s'  on  the  wheel  t' 
must  be  equal  to  the  number  of  times  it  is  intended  that  the  chasers  or  dies  shall  pass  over  the  blank 
to  complete  the  thread ; but  if  desired  this  number  may  be  doubled,  trebled,  &c.,  by  having  two,  three, 
(fee.,  pins  u on  the  other  face  of  the  wheel.  It  is,  however,  preferred  to  have  it  as  described.  In  this 
uray  it  will  be  seen  that  the  carrying-wheel  carries  the  blanks  towards  the  jaws  and  inserts  the  blank 
in  the  open  dies  and  moves  it  back  to  form  the  thread,  and  that  these  motions  are  repeated  a given 
number  of  times  until  the  thread  is  completely  chased  or  cut,  and  that  when  completed  the  carrying- 
wheel  is  turned  far  enough  around  to  remove  the  threaded  screw  and  present  a hlank  to  the  jaws  to 
undergo  the  same  series  of  operations. 


3273.  3273. 


While  the  screw  is  being  cut  or  chased  it  is  held  in  its  hole  in  the  rim  of  the  carrying-wheel  by  means 
of  a roller  v within  the  rim  of  the  wheel,  and  turning  on  a stud-pin  at  the  end  of  a lever  w,  which  turns 
on  a fulcrum-pin  x\  the  roller  being  held  against  the  inner  periphery  of  the  rim  of  the  wheel  by  a 
pressure-screw  y that  bears  against  the  lower  end  of  the  lever,  so  that  as  the  blank  is  carried  up  by 
the  wheel  to  be  presented  to  the  dies,  the  pressure  of  this  roller  against  the  head  holds  it  firmly  in  the 
rim  of  the  wheel.  The  machine  can  be  made  double  for  threading  two  screws  at  one  and  the  same 
time,  as  shown  in  the  figures,  by  having  two  carrying-wheels  on  the  same  shaft,  and  two  mandrels  with 
their  jaws,  dies,  and  sliding-rods,  the  two  mandrels  being  geered  together  by  two  cog-wheels  z'  z'. 


It  will  be  obvious  from  the  foregoing  that,  instead  of  the  segment  cog-wheel  for  giving  the  recipro- 
cating motions  to  the  carriage  of  the  carrying-wheel,  this  may  be  done  by  a segment  volute-cam,  the  face 
of  which  shall  act  alternately  against  the  front  and  back  faces  of  the  open  space  of  the  bar  attached  to 
the  carriage,  as  the  object  is  simply  to  give  a regular  reciprocating  motion  to  the  carriage,  particularly 
during  the  operation  of  threading;  for  during  that  operation  the  motion  of  the  carriage  must  be  regain 
to  give  a regular  pitch  to  the  thread.  As  it  is  only  important  to  give  a regular  motion  to  the  carriage 
in  the  operation  of  threading,  the  segment-cog  or  the  volute-cam  need  only  act  in  this  direction,  and  the 
motion  to  run  back  the  carriage  for  the  presentation  of  the  blank  may  be  given  by  a separate  cam  of  a 
more  sudden  curve,  or  an  arm  of  greater  length  to  perform  the  return  motion  faster ; but  as  these  are 


G02 


SCREWING  MACHINE  FOR  BOLTS. 


well-known  mechanical  equivalents,  they  are  simply  named  to  indicate  the  various  modes  in  which  thb 
part  of  the  invention  may  be  applied. 

SCREWING  MACHINE  FOR  BOLTS.  Fig.  3275  is  a general  plan  of  the  machine. 

F’ig.  3276  is  an  end  view  looking  upon  the  frame  K,  the  guide-rods  R R and  chuck  L being  removed 
Fig.  3277  is  an  end  view  looking  upon  the  frame  N. 

F’ig.  3278  is  a general  side  elevation  of  the  machine  corresponding  with  the  plan  in  Fig.  3275. 

F’ig.  3279  is  a face  view  of  the  chuck  L,  seen  also  in  F’igs.  3275  and  3280. 

Fig.  3280  is  a corresponding  front  view  of  the  die-frame,  which  is  retained  upon  the  guide-rods  R R 
of  the  machine  by  recesses  in  the  projecting  ends. 

The  same  letters  of  reference  are  used  in  all  the  figures. 


The  head-frame  of  the  machine  consists  of  three  pieces  fastened  to  a sole  in  the  usual  manner.  The 
forms  of  the  frame-pieces  K and  N are  distinctly  shown  in  the  drawings,  particularly  by  Figs.  3276 
and  3277.  A separate  view  of  the  intermediate  upright  is  not  given,  but  it  is  easy  to  perceive  from 


SCREWING  MACHINE,  DOUBLE. 


C03 


Figs.  3275  and  3277,  that  it  has  a projecting  piece  corresponding  to  that  on  the  bracket  N to  carry  the 
spindle  of  the  back-speed  wheels  GH;  and  that  it  has  besides  a centre-bearing  corresponding  to  that 
of  Fig.  3276,  for  the  end  of  the  main-spindle,  on  which  are  the  pinion  C and  wheel  L>,  and  which  carries 
the  chuck  L. 

P,  the  driving-pulleys  on  the  driving-spindle  of  the  machine.  This  spindle  has  a bearing  at  each 
end,’ and  a bearing  also  in  the  middle  standard  of  the  frame.  The  pinion  F and  wheel  I are  keyed  on 
the  spindle,  and  geer  with  the  wheel  and  pinion  G and  H on  a separate  spindle,  like  the  back-speed  of 
a lathe.  The  clutch-wheels  A and  B are  loose  on  the  same  spindle  which  carries  the  similar  pair  F 
and  I,  so  that  either  of  them  may  be  made  drivers  by  means  of  the  clutch  S,  which  slides  on  the  shaft, 
and  is  made  to  turn  with  it  by  a sunk  feather  which  connects  the  clutch  and  shaft.  This  clutch  is 
worked  by  a lever  passing  to  the  hand  of  the  operator  in  the  usual  manner.  The  pinion  A geers  with 
D on  the  main-spindle ; B geers  with  a carrier-pinion  E,  Fig.  3276,  which,  in  its  turn,  geers  with  0 on 
the  main-spindle. 

3279. 


To  explain  the  action  of  the  machine,  suppose  the  bolt  to  be  centered  in  the  chuck  L,  and  the  die- 
holder,  shown  by  Fig.  3280,  to  be  placed  on  the  guide-rods  It  R,  and  brought  up  so  that  the  end  of  tne 
bolt  just  enters  the  dies;  then  the  clutch  being  locked  with  the  pinion  A,  and  the  machine  set  in  mo- 
tion, the  chuck  will  be  made  to  revolve,  and  with  it  the  bolt  to  be  screwed  ; and  meanwhile  the  die- 
holder  being  pressed  against  the  end  of1  the  bolt,  this  will  enter  them  as  into  a nut  and  will  continue 
to  screw  itself  into  them,  and  by  this  means  the  desired  thread  will  be  cut  upon  its  circumference. 

The  bolt  being  thus  screwed,  the  next  operation  is  to  unscrew  it.from  the  die-holder.  For  this  pur- 
pose, the  clutch  is  disengaged  from  the  pinion  A,  and  locked  with  B,  which  geering  with  an  interme- 
diate pinion  E,  reverses  the  motion,  and  it  at  the  same  time  increases  the  speed  in  proportion  to  the 
increase  of  diameter  of  B to  A. 

This  form  of  screwing  machine  has  some  advantages,  but  it  is  wanting  in  compactness  and  simplicity 
of  geering,  so  much  the  aim  of  constructors  of  engineering  tools. 

SCREWING  MACHINE,  DOUBLE — By  William  Moore,  Glasgow.  This  is  one  of  the  most  pow- 
erful and  complete  machines  of  its  class.  It  is  capable  of  cutting  the  threads  of  screws  of  4-£  inches 
diameter,  and,  unlike  most  other  machines  of  the  kind,  the  geering  is  so  adjusted,  that  both  sides  of  the 
machine  can  be  employed  simultaneously  upon  bolts  and  nuts  of  different  sizes. 

A A,  the  two  main  standards  of  the  machine,  are  fixed  upon  a strong  cast-iron  sole-plate  B,  which  ex- 
tends the  whole  length  of  the  machine,  and  is  securely  bolted  to  a stone  foundation.  Upon  these  standards 
all  the  geering  of  the  machine  is  mounted.  The  driving-spindle  J is  placed  intermediate  to  the  screwing- 
spindles  E and  N,  and  carries  the  three-speed  cone  I,  by  which  motion  is  communicated  to  the  machine. 
The  spindle  J has  a bearing  in  each  of  the  two  standards,  and  carries  the  fast-pinions  a and  b,  also  the 
wheel  U and  pinion  cl,  which  are  cast  together,  but  run  loose  on  the  spindle.  The  pinion  a geers  into 
the  two  spur-wheels  S and  F,  which  are  loose  upon  the  two  screwing-spindles  E and  N ; and  the  pinion 
b geers  with  the  spur-wheel  K,  which  is  loose  upon  a spindle  L,  immediately  under  the  driving-spindle 
J.  The  wheel  U geers  into  the  wheel  R,  and  the  pinion  d into  the  wheel  O,  fast  on  the  screwing- 
spindle  N.  The  spindle  L has  its  bearings  also  in  the  two  end  standards,  and  carries,  besides  the 
wheel  K,  another  wheel  M,  which  geers  with  the  loose  wheel  G on  the  screwing-spindle  E ; also  a fast- 
pinion  c,  which  geers  with  the  fast-wheel  P,  upon  the  screwing-spindle  N.  The  wheels  K and  M are 
loose  on  the  shaft  L,  but  are  both  fast  upon  a common  hollow  boss,  so  that  motion  being  communicated 
to  the  wheel  K,  the  other,  M,  will  be  carried  round  in  the  same  direction  with  an  equal  velocity. 

The  arrangement  of  the  wheels  on  the  large  screwing-spindle  N is  fully  shown  by  Fig.  3286.  This 
spindle  is  provided  with  a hollow  boss  Q,  ou  which  are  the  fast-wheel  R and  the  loose  clutch-wheel  S : 
this  last  can  be  brought  into  action  by  the  sliding-clutch  T,  upon  the  same  hollow  boss  Q,  and  which 
can  be  worked  from  either  end  of  the  machine,  by  the  double  handle  Z Z.  The  wheels  O and  P are 
fast  upon  the  spindle. 

The  smaller  screwing-spindle  carries  only  the  two  loose  clutch-wheels  G and  F,  either  of  which  can 
be  brought  into  action  by  the  sliding-clutch  H,  which  is  worked  by  the  double  handle  Y Y.  This  hau, 
die  is  placed  upon  a small  rocking-shaft  l,  carried  on  two  brackets  mm,  resting  upon  the  sole-plate  of 
the  machine,  and  has  the  clutch-fork  n keyed  upon  it,  so  that  in  moving  the  handle  from  the  vertical 
position,  the  clutch  will  be  brought  into  geer  with  one  of  the  wheels  G F,  on  the  spindle  E.  The  handle 
L Z is  in  like  manner  fixed  upon  a cross-shaft  o,  carried  by  the  brackets  pp,  similarly  fixed  upon  the 
6ole  plate;  but  this  shaft,  besides  the  clutcli-fork  q for  working  the  clutch  T on  the  hollow  boss  Q of 


604 


SCREWING  MACHINE,  DOUBLE. 


the  screwing-spindle  N,  has  a second  fork  for  working  a clutch  on  the  spindle  L,  to  engage  and  disen 
gage  the  loose  boss  of  the  wheels  K and  M.  But  these  two  clutches  are  so  fixed  in  relation  to  each 
other,  that  one  of  them  only  can  be  in  action  at  the  same  time,  consequently,  when  the  wheel  S is  en- 
gaged by  the  clutch  T,  the  wheels  K and  M must  necessarily  be  loose  on  the  shaft  L. 

This  arrangement  of  the  geering  being  kept  in  view,  the  action  of  the  machine  will  easily  be  com- 
prehended. Thus  supposing  motion  to  be  communicated  to  the  speed-cone  I,  if  the  clutches  T and  H 
be  in  geer  with  the  wheels  S and  F respectively,  these  wheels  will  be  driven  by  the  pinion  a,  with  a 
speed  proportioned  to  their  respective  diameters,  and  in  opposite  directions.  Meantime,  the  clutch  on 
the  under  shaft  L,  being  out  of  action,  the  wheels  K and  M will  be  loose  upon  it,  and  the  shaft  itself 
will  be  made  to  revolve  idly  by  means  of  the  wheel  P,  which  geers  with  the  pinion  c upon  it.  The 
angular  velocity  of  the  wheel  F will  be  immediately  communicated  to  the  screwing-spindle  E and  its 
chuck  V;  but  the  angular  velocity  of  the  wheel  S will  be  transferred  to  the  hollow  boss  Q,  and  thence 


”p  s 32s3.  o 


to  the  wheel  R,  which  geers  with  the  wdieel  U.  But  this  Iasi,  being  loose  upon  the  driving-shaft,  and 
fast  with  the  pinion  d,  will  communicate  its  motion  to  the  wheel  0,  which  is  fast  upon  the  screwing- 

x X R X d 

spindle  N,  and  so  communicate  a reduced  speed  in  the  ratio  of  the  numbers  — . But  let  the 

to  X B X H 

clutch  T be  disengaged — the  clutch  II  remaining  in  geer  as  before — then  the  under  clutch  will  engage 
the  wheels  K and  M to  their  shaft  L,  and  in  consequence  this  shaft  will  be  driven  by  the  pinion  b,  which 
geers  with  the  wheel  K,  and  will  drive  the  wheel  P,  which  is  fast  on  the  screwing-spindle  N,  with  a 

b X c 

speed,  in  the  opposite  direction  to  its  former  motion,  determined  by  the  ratio  of  the  numbers  — — 

k X 1 

Let  the  clutch  H be  brought  out  of  geer  with  the  wheel  F,  and  engaged  with  the  wheel  G,  then  the 
spindle  E will  receive  an  increased  speed  in  the  opposite  direction  to  its  former  motion.  Thus  the  twc 
screwing-spindles  may  be  driven  in  either  direction  independently  of  each  other,  and  may  be  employed 
at  the  same  time  to  screw-bolts  and  nuts  of  different  sizes  and  pitches  of  thread. 


SCREWING  MACHINE,  DOUBLE. 


605 


The  screwing-spindles  are  of  malleable  iron  to  insure  strength,  and  are  made  hollow  to  allow  the 
bolts  to  pass  into  them  as  they  are  screwed.  The  chucks  are  fast  upon  the  ends  of  the  spindles,  and 
to  these  the  die-holders  are  bolted.  The  die-holder  of  the  smaller  spindle  is  of  the  common  form,  and 
fits  into  a dovetailed  recess  Y,  from  which  it  can  be  removed  and  have  its  cutters  changed  at  pleasure ; 

3234. 


V 


but  that  for  the  larger  spindle  is  differently  constructed,  as  will  be  observed  from  the  face  view  of  it 
given  in  Fig.  3287.  This  consists  of  a strong  plate  W,  annularly  recessed  to  receive  a ring  X,  flush 
with  its  exterior  surface.  The  ring  X has  a portion  of  its  circumference  cut  into  teeth  to  geer  with  a 
worm  recessed  in  the  plate  W,  and  which  can  be  worked  by  a handle  placed  upon  the  projecting  square 
end  of  its  spindle  h.  Consequently,  as  this  worm  is  turned  in  one  direction  or  the  other,  the  ring  X 

3285. 


will  be  correspondingly  affected,  and  will,  by  its  motion,  change  the  relation  of  the  cutters  fff  in  re- 
spect of  the  axis  of  the  chuck.  For  this  purpose,  three  spiral  recesses  g g g are  formed  on  the  interior 
circumference  of  the  ring,  into  which  the  exterior  ends  of  the  cutters  project  and  abut  against  the 
inner  edges  of  the  spiral  recesses.  It  is  therefore  clear  that  if  the  ring  be  made  to  pass  through  a 


3386. 


3287. 


small  aic  from  right  to  left,  the  cutters  will  be  forced  to  approach  the  centre  ; and  conversely,  if  the 
motion  be  from  left  to  right,  the  cutters  will  be  allowed  to  expand  and  receive  a larger  diameter  of 
bolt.  The  cutters  are  accurately  fitted  into  recesses  prepared  for  their  reception  in  the  ring  e/  which  is 
of  a piece  with  the  plate  W,  and  the  whole  is  covered  by  the  thin  plate  j.  In  this  plate  are  three  ra- 


606 


SEA-LIGHTS. 


dial  slots  kkk,  through  which  pass  three  small  round  pins  projecting  from  the  cutters,  for  the  purpose 
of  guiding  them  in  a rectilinear  motion. 

In  the  operation  of  screwing,  the  head  of  the  bolt  is  caught  in  the  gland-frame  D,  Fig.  3288,  which 
fits  between  the  guide-rods  C C,  along  which  it  slides  towards  the  chuck,  as  the  thread  is  being  cut, 
and  the  screw  thereby  formed  passes  into  the  hollow  interior  of  the  screwing-spindle.  When  nuts  are 
to  be  tajiped,  they  are  inserted  into  glands  which  fit  the  guide-rods  C 0,  at  the  opposite  end  of  the 
machine,  and  the  taps  are  fitted  into  the  square  holes  in  the  ends  of  the  spindles. 

SEA-LIGHTS,  or  Light-Houses.  Powerful  lights  exhibited  from  lofty  towers  or  headlands,  to  warn 
navigators  of  their  proximity  to  the  land.  These  are  divided  into  coast-lights,  which  occupy  the  most 
salient  points  ; bay-lights,  located  within  the  recessed  lines  of  coast ; channel-lights,  arranged  to  desig- 
nate some  particular  course  for  vessels  to  steer  over  a bar  or  past  some  danger,  and  hence  are  often 
called  “ leading-lights tide-lights,  to  indicate  the  height  of  tide  at  the  port;  and  lastly,  floating-lights, 
which  are  vessels  from  which  are  exhibited  lights  to  indicate  the  vicinity  of  some  shoal  lying  off  from 
the  shore,  in  a position  where  no  permanent  structure  can  be  erected. 

Light  houses,  properly  speaking,  are  of  modern  origin,  and  date  their  efficiency  from  about  the  year 
1780,  when  Citizen  Argand,  of  Geneva,  in  Switzerland,  invented  the  admirable  lamp  that  yet  bears  his 
name,  and  which  combines  in  a degree  not  yet  equalled  by  any  other  the  best  principles  of  combustion, 
and  consequently  the  evolution  of  a brilliant  light.  Previous  to  the  invention  of  Argand,  navigators 
were  compelled  to  trust  to  the  dim  and  murky  light  of  wood  and  coal  fires,  burned  on  the  tops  of  tow- 
ers or  lofty  promontories,  which,  when  the  wind  was  off  shore,  must  have  been  nearly  or  quite  concealed 
by  their  own  smoke.  Coal  lights  have  been  continued  in  the  Baltic  till  within  ten  years  past.  Smeaton, 
who  erected  the  celebrated  Eddystone  Light-house,  (justly  considered  the  work  of  a man  of  genius,  and 
as  displaying  a high  degree  of  mechanical  skill,)  had  not  the  talent  sufficient  to  devise  any  improvement 
in  the  lights,  but  was  obliged  to  illuminate  that  superb  Pharos  with  tallow  candles  ! How  great  would 
be  his  delight,  could  he  now  see  the  beautiful  combination  of  science  and  practice  that  are  united  in  the 
admirable  dioptric  apparatus  of  Fresnel,  which  is  installed  in  the  Eddystone  Light-house,  and  makes  it 
one  of  the  most  efficient  lights  in  the  English  Channel ! 

'The  great  increase  of  commerce  and  navigation  in  the  last  century,  and  the  repetition  of  frightful  dis- 
asters by  frequent  shipwrecks,  naturally  directed  the  minds  of  men  to  suggest  means  for  ameliorating 
the  danger  to  which  shipping  of  all  classes  was  then  exposed,  and  an  effort  to  improve  the  light-houses 
was  one  step  towards  the  accomplishment  of  this  desirable  object.  The  clumsy  means  of  producing 
light  from  wood  and  coal  fires,  prevented  the  use  of  a glazed  lantern  to  protect  the  flame  from  the 
furious  winds  of  the  Atlantic,  and  consequently  the  application  of  optical  instruments  to  magnify  the 
light.  These  fires  were  made  in  large  iron  braziers,  and  about  225  lbs.  of  coal  were  used  in  one  night. 
The  first  attempt  to  economize  the  light  from  coal  or  other  fires,  and  to  direct  the  rays  to  the  horizon, 
was  made  in  1727,  at  the  Cordouan  Light-house,  by  M.  Bitri,  an  engineer  employed  to  repair  that 
structure.  He  placed  over  the  flame  an  inverted  cone  of  tin  plates,  which  reflected  all  the  light  inci- 
dent upon  its  surface,  and  must  have  added  materially  to  its  effect  as  long  as  the  tin  was  kept  polished ; 
but  it  is  evident  that  with  an  open  fire  beneath  the  cone,  the  smoke  and  gas  must  speedily  have  de- 
stroyed the  polish,  and  with  it  the  reflecting  power. 

The  effects  of  a light  in  giving  out  rays  without  any  controlling  apparatus,  will  be  to  fill  a sphere 
whose  radius  is  equal  to  the  distance  at  which  the  light  is  visible.  In  the  light  shown  from  a light- 
house, those  rays  which  are  thrown  upwards  or  downwards  beyond  the  reach  of  vision,  would  be  totally 
lost  for  practical  utility,  and  it  therefore  becomes  necessary  to  economize  the  light,  to  deflect  these  rays 
and  cause  them  to  assume  that  direction  only  in  which  they  are  required : in  short,  our  apparatus  must 
be  so  ordered  as  to  produce  a horizontal  band  or  zone  of  light.  To  do  this  we  have  two  methods,  both 
of  which  have  been  successfully  applied : the  first  being  to  collect  the  rays  in  a concave  mirror,  and  by 
its  reflective  power  project  them  to  the  horizon  ; a circle  of  these  mirrors  would  thus  be  visible  from 
every  point  of  the  horizon : this  is  termed  the  catoptric  method.  Secondly,  to  place  lenses  of  a 
proper  form  around  the  light,  when  all  the  rays  falling  upon  these  will  be  refracted  in  a horizontal 
plane : this  is  called  the  dioptric  method,  and  is  the  more  modern  and  by  far  most  perfect  of  the  two 
systems. 

As  the  catoptric  or  reflector  system  is  the  only  one  used  in  the  United  States,  we  shall  briefly  de- 
scribe the  form  and  construction  of  the  reflectors,  which  ought  to  be  paraboloidal  to  produce  the  proper 
result,  though,  we  regret  to  say,  there  are  few  such  reflectors  in  this  country. 

It  is  proper  to  premise  that  a parabola  is  a curve  of  the  second  order,  obtained  by  cutting  a cone  in 
a plane  parallel  to  one  side,  and  possessing  this  remarkable  property,  that  a line  drawn  from  the  focus 
to  any  point  in  the  curve  makes,  with  a tangent  at  that  point,  an  angle  equal  to  that  which  a line  par- 
allel to  the  axis  of  the  curve  makes  with  that  tangent.  An  inspection  of  the  diagram  will  render  this 
apparent,  and  it  is  easy  to  see  that  a revolution  of  this  curve  upon  its  axis  will  generate  a parabolic 
conoid,  which  is  the  form  of  concave  mirror  we  require  for  light  houses. 

The  line  P Y G,  Fig.  3289,  is  a parabolic  curve,  and  within  it  is  the  focal  point  F,  which  is  the  situa- 
tion of  the  lamp-flame  in  the  reflector,  of  which  this  may  be  supposed  to  represent  a section.  Now,  a 
ray  from  the  lamp  at  F falling  on  the  concave  surface  at  d,  will  be  reflected  in  the  direction  a f which 
is  parallel  to  the  axis  of  the  curve  Y Z,  and  the  angle  of  reflection  bac  is  equal  to  the  angle  of  incidence 
d a e ; in  other  words,  it  makes  with  the  normal  a z the  angle  g ah  equal  to  the  adjacent  angle  h a i,  and 
this  property  belongs  to  every  portion  of  the  surface  of  the  parabola,  and  consequently  the  rays  from 
the  focal  point  will  be  represented  by  the  lines  F x x',  F w w. 

With  respect  to  the  invention  of  parabolic  mirrors,  we  find  them  mentioned  at  a very  early  period, 
though  not  in  connection  with  the  subject  of  illumination,  but  in  reference  to  their  powers  of  focalizing 
the  rays  of  the  sun  to  form  burning  instruments,  an  inverse  principle  of  that  of  lamp  reflectors. 

In  a work  entitled  “ Pantometria,”  by  Leonhard  Digges,  published  in  London  in  1571,  the  authoi 
states  that,  “ with  a glasse,  framed  by  a revolution  of  a section  parabolicall,  I have  sef  fire  to  powdei 


SEA-LIGHTS. 


GOT 


half  a mile  and  more  distant.”  In  the  prosecution  of  this  subject  the  celebrated  Napier  and  Sir  Isaac 
Newton  experimented  with  parabolic  reflectors  before  1673,  and  lluffon,  the  great  naturalist,  with  the 
same  object  proposed  the  polyzonal  lens,  now  adapted  to  light-house  purposes,  as  will  be  described 
further  on.  The  first  parabolic  reflectors  for  light-houses  of  which  any  authentic  record  remains,  were 
used  at  the  port  of  Liverpool,  England,  previous  to  1777,  for  in  that  year  Wm.  Hutchinson,  dock-master 
of  the  port,  published  his  “Practical  Seamanship,”  and  in  that  work  he  fully  describes  the  apparatus 
used  in  the  four  light-houses  built  at  Liverpool  in  1763.  These  reflectors  were  formed  to  a parabolic 
curve  by  a somewhat  rude  process,  which  he  describes. 

Figs.  3290  and  3291  represent  the  parabolic  reflectors  used  in  the  Liverpool  light-houses,  copied  from 
a plate  in  Hutchinson’s  “Practical  Seamanship,”  formed  of  wood,  and  lined  with  pieces  of  looking-glass, 
or  of  plates  of  tin.  The  oil  is  kept  on  a level  with  the  flame  by  a dripping-pot,  supplying  the  reservoir 
at  the  back.* 


3290. 


3291. 


He  evidently  had  a perfect  knowledge  of  the  properties  of  the  parabolic  reflector,  and  had  also 
a just  idea  of  its  correct  application  as  an  illuminating  instrument,  and  he  also  proposed  other 
aud  more  complete  reflectors,  similar  to  those  now  in  use ; but  like  Smeaton,  who  proposed  the 
use  of  lenses,  neither  seems  to  have  attempted  the  production  of  a more  perfect  method  of  obtain- 
ing the  artificial  fight,  one  thinking  candles  best,  the  other  preferring  a rude  oil  lamp.  The  inven- 
tion of  Argand’s  lamp,  in  1780,  led  the  celebrated  Chevalier  de  Borda  to  propose  its  union  with 
parabolic  reflectors  of  silver  plate,  for  the  illuminating  apparatus  of  light-houses.  A suite  of  Argand 
lamps  and  silver-plate  parabolic  reflectors  were  accordingly  made  by  Lenoir,  the  eminent  optician,  and 
set  up  in  the  Cordouan  Light-house  in  1783  by  M.  Teulfere,  Ingenieur  en  chef  Ponts  et  Chaussees,  who 
had  just  completed  the  alteration  of  that  structure,  and  raised  it  to  its  present  height  of  206  feet. 
This  apparatus  was  arranged,  moreover,  as  a revolving  light,  being  the  first  one  of  that  kind  ever  ex- 
hibited, the  reason  for  which  will  be  explained  further  on. 

The  Trinity  House,  London,  adopted  De  Borda’s  plan  of  the  Argand  lamp  and  silver-plate  parabolic 
reflector  in  1788,  and  the  Scottish  Light-house  Board  did  the  same  in  1803,  at  Inchkeith.  The  inven- 
tion was  imported  into  this  country  in  1810,  and,  strange  to  say,  a patent  was  granted  for  this  impor- 
tation, and  our  government  bought  out  the  patentee  in  1812,  although  the  Argand  lamp  was  a French 


* “We  have  had,”  says  Mr.  Hutchinson,  “ and  used  here  in  Liverpool,  reflectors  of  1,  2,  and  3 feet  focus,  and  3,  51,  7'-, 
and  12  feet  diameter.  The  smallest  made  of  tin  plates  soldered  together,  and  the  largest  of  wood  covered  with  plates  of 
looking-glass,  and  a copper  lamp ; the  cistern  part  for  the  oil  and  wick  stands  behind  the  reflector,  so  that  nothing  stands 
before  the  reflector  to  interrupt  the  blaze  of  the  lamp  acting  upon  it,  but  the  tube  that  goes  through  with  a spreading 
burner  mouth-piece,  to  spread  the  blaze  parallel  thereto,  and  with  the  middle  of  it  just  in  the  focus  or  burning  point  of 
the  reflector.  The  lamps  are,  like  the  reflectors,  proportioned  to  make  a greater  or  less  blaze  as  required  ; their  spread- 
ng  burning  parts  are  from  3 to  12  and  14  inches  broad,  and  are  trimmed  every  four  hours.  Thus  are  these  light-houses 
sonstructed,  kept,  and  situated,  and  have  stood  the  test  of  a fair  trial,  and  the  preference  and  advantages  given  to  them 
even  by  their  opponents,  as  there  always  will  be  to  new  things,  commonly  calling  them  new  whims,  till  time  and  trial 
confirm  them  as  useful  improvements.” 


608 


SEA-LIGHTS. 


patent,  and,  combined  with  the  reflector  of  De  Borda,  had  then  been  in  public  use  in  the  French  and 
English  lightdiouses  for  thirty  years. 

The  manner  in  which  these  instruments  are  applied  to  produce  the  effect  of  fixed  and  revolvin'* 
lights  will  be  understood  by  inspecting  the  diagrams. 

Fig.  3292  is  a half-plan  and  elevation  of  a fixed  light  of  1G  lamps.  The  reflectors  are  arranged  in 
two  series,  one  above  the  other,  on  circular  frames  of  iron  ; at  the  back  of  each  reflector  an  Argand 
lamp  is  attached,  the  supply-tube  from  which  passes  through  a hole  cut  in  the  reflector  and  leading  to 
the  burner,  which  is  accurately  set  in  the  focus  of  the  instrument.  Each  reflector  must  thus  illuminate 
that  portion  of  the  horizon  towards  which  it  faces,  and  consequently  the  distant  observer  sees  the  light 
of  but  one  lamp. 


Fig.  3293  is  a half-plan  and  elevation  of  a revolving  light  of  four  faces.  In  the  diagram  there  are 
but  two  lamps  on  each  of  the  four  sides  of  a square,  though  as  many  as  ten  lamps  are  often  so  placed 
in  lights  of  the  first  class.  It  is  obvious  in  this  arrangement  that  the  light  from  this  apparatus  must 
be  visible  in  four  directions  only,  and  these  90°  apart,  or  at  right  angles  to  each  other,  while  the  inter- 
vening spaces  must  be  dark  or  eclipsed.  By  causing  this  apparatus  to  rotate  slowly  on  its  vertical 
axis,  the  bright  and  dark  portions  of  the  square  will  be  presented  alternately  to  the  eye  of  a distant 
observer ; in  other  tvords,  the  light  will  appear  and  disappear  at  intervals  of  time  corresponding  to  the 
speed  of  rotation.  Two  objects  are  gained  by  this  arrangement : 1st.  A distinctive  appearance,  by 
which  a light  that  is  eclipsed  at  regular  intervals  can  never  be  mistaken  for  a light  steadily  visible,  or, 
as  they  are  termed,  a fixed  light.  2d.  The  power  and  brilliancy  of  the  light  is  greater  than  in  a fixed 
light,  just  in  proportion  to  the  number  of  lamps  on  each  face  of  the  frame  ; for  while  in  the  fixed  light 
we  cannot  receive  the  light  of  but  one  reflector  at  a time,  owing  to  the  circular  form  of  arrangement, 
in  the  revolving  light  we  have  the  combined  power  of  from  two  up  to  ten  reflectors  at  one  view,  sim- 
ply by  placing  so  many  reflectors  on  each  face  of  the  frame.  The  difference,  then,  between  the  illumi- 
nating power  of  the  two  methods  of  fixed  and  rotary  lights,  is  in  the  ratio  of  2 to  1,  3 to  1,  or  10  to  1, 
as  the  case  may  be.  Consequently,  the  relative  economy  of  the  two  plans  is  in  a like  ratio.  In  a 
fixed  light  of  24  lamps,  the  seaman  can  only  have  the  aid  of  one  reflector,  no  matter  from  what  direc- 
tion he  views  the  light ; while  in  a revolving  light  of  24  lamps,  arranged  in  groups  of  eight  reflectors  on 
the  three  sides  of  a triangular  frame,  the  seaman  has  eight  times  as  powerful  a light  presented  to  his 
view  at  short  intervals — yet  the  cost  of  maintaining  these  two  lights  is  exactly  similar.  Notwith- 
standing the  simplicity  of  this  fact,  and  the  cogent  reasons  that  exist  for  availing  ourselves  of  the 
superior  economy  and  brilliancy  of  the  revolving  light,  it  is  rarely  adopted  in  the  United  States  light 
houses.  With  more  than  300  lights  on  our  coast,  there  are  yet  but  38  revolving  fights,  against  287 
fixed. 

In  Fig.  32S9  the  theoretical  properties  of  the  parabola  are  stated,  and  it  is  obvious  that  if  these 
should  remain  true  in  practice,  the  beam  of  light  from  such  a reflector  would  be  a simple  cylinder  ol 
a diameter  equal  to  the  double  ordinate  of  the  mirror.  Such,  however,  is  fortunately  not  the  case 


SEA-LIGHTS. 


609 


3294. 


The  size  of  the  flame  of  the  lamp  causes  a divergence  of  the  reflected  light,  which  divergence  increases 
and  decreases  with  the  length  of  the  focal  axis  of  the  mirror  and  the  size  of  the  flame.  1 n practice, 
the  effective  divergence  of  the  beam  of  light  from  a 21-inch  reflector  of  4 inches  focal  axis  is  found 
to  be  about  14  degrees  in  azimuth.  Hence  we  require  26  reflectors  in 
a fixed  light,  in  order  to  produce  a tolerably  equal  distribution  of  light 
around  the  horizon.  If  a less  number  is  used,  the  intervals  between 
each  pair  of  reflectors  is  poorly  lighted,  and  not  visible  at  any  great 
distance. 

Fig.  3294  is  a vertical  section  of  a parabolic  reflector,  with  its  lamp 
in  the  proper  place,  and  the  burner  in  the  focal  point. 

Dioptric  system  of  lights. — One  of  the  earliest  notices  of  the  applica- 
tion of  lenses  to  light-houses  is  in  Smeaton’s  Narrative  of  the  Eddy- 
stone  Light-house,  where  it  is  mentioned  that  a London  optician,  in 
1759,  proposed  grinding  the  glass  of  the  lantern  to  a radius  of  seven 
feet  six  inches.  About  the  middle  of  the  last  century,  however,  lenses 
were  actually  tried  in  several  light-houses  in  the  south  of  England,  and 
in  particular  at  the  South  Foreland  in  the  year  1752;  but  their  imper- 
fect figure  and  the  quantity  of  light  absorbed  by  the  glass,  which  was 
of  impure  quality  and  of  considerable  thickness,  rendered  their  effect 
so  much  inferior  to  that  of  the  paraboloidal  reflectors  then  in  use,  that 
after  trying  some  strange  combinations  of  lenses  and  reflectors,  the 
former  were  finally  abandoned. 

The  celebrated  Buffon,  in  order  to  prevent  the  great  absorption  of  light  by  the  thickness  of  the  ma- 
terial, which  would  necessarily  result  from  giving  to  a lens  of  great  dimensions  a figure  continuously 
spherical,  proposed  to  grind,  out  of  a solid  piece  of  glass,  a lens  in  steps,  or  concentric  zones.  This 
suggestion  of  Buffon  about  the  construction  of  large  burning  glasses  was  first  executed,  with  tolerable 
success,  about  the  year  1780,  by  the  Abbe  Rochon. 

The  merit -of  having  first  suggested  the  building  of  lenses  in  separate  pieces  seems  to  be  due  to 
Condorcet,  who,  in  his  Eloge  de  Buffon,  published  so  far  back  as  1773,  enumerates  the  advantages  to 
ae  derived  from  this  method.  Sir  David  Brewster  also  described  this  mode  of  building  lenses  in  181 1, 
and  in  1822  the  late  eminent  Fresnel,  unacquainted  with  the  suggestions  of  Condorcet  or  the  descrip- 
tion by  Sir  David  Brewster,  explained,  with  many  ingenious  and  interesting  details,  the  same  mode  of 
constructing  those  instruments  which  he  had  discovered  for  himself  in  1819. 

Spherical  lenses,  like  spherical  mirrors,  collect  truly  into  the  focus  those  rays  only  which  are  incident 
near  the  axis ; and  it  is,  therefore,  of  the  greatest  importance  to  employ  only  a small  segment  of  any 
sphere  as  a lens.  The  experience  of  this  fact,  among  other  considerations,  led  Condorcet,  as  already 
noticed,  to  suggest  the  building  of  lenses  in  separate  pieces.  Fresnel,  however,  was  the  first  who  actu- 
ally constructed  a lens  on  that  principle,  and  fully  availed  himself  of  the  advantages  which  it  affords  ; 
and  he  has  subdivided,  with  such  judgment,  the  whole  surface  of  the  lens  into  a centre  lens  and  concen- 
tric annular  bands,  and  has  so  carefully  determined  the  elements  of  curvature  for  each,  that  it  does  not 
seem  likely  that  any  improvement  will  soon  be  made  in  their  construction. 

Fig.  3295  represents  a plan  of  the  great  lens ; Fig.  3296  a section  through  the  line  A B. 


3295. 


pi' 


The  central  disk  of  the  lens,  which  is  employed  in  lights  of  the  first  order,  and  whose  focal  distance  is 
920  millimetres,  or  36'22  inches,  is  about  11  inches  in  diameter;  and  the  annular  rings  which  surround 
'*■  gradually  decrease  in  breadth,  as  they  recede  from  the  axis,  from  2J  to  II  inches.  The  breadth  of 
any  zone  or  ring  is,  within  certain  limits,  a matter  of  choice,  it  being  desirable,  however,  that  no  part  of 
Vol.  n.— 39  1 


610 


SEA-LIGHTS. 


the  lens  should  be  much  thicker  than  the  rest,  as  well  for  the  purpose  of  avoiding  inconvenient  projec- 
tions on  its  surface,  as  to  permit  the  rays  to  pass  through  every  part  of  it  with  nearly  equal  loss  by 
absorption.  The  objects  to  be  attained  in  the  polyzonal  or  compound  lens  are  chiefly,  as  above  noticed, 
to  correct  the  excessive  aberration  produced  by  refraction  through  a hemisphere  or  great  segment,  whose 
edge  would  make  the  parallel  rays  falling  on  its  curve  surface  converge  to  a point  much  nearer  the  lens 
than  the  principal  focus,  as  determined  for  rays  near  the  optical  axis,  and  to  avoid  the  increase  of  ma- 
terial, which  would  not  only  add  to  the  weight  of  the  instrument  and  the  expense  of  its  construction,  but 
would  greatly  diminish  by  absorption  the  amount  of  transmitted  light. 

In  applying  lenses  to  the  flame  of  a light  house  lamp,  similar  considerations  must  guide  us  iu  making 
the  necessary  arrangements  as  in  the  case  of  reflectors.  The  size  of  the  flame  and  its  distance  from  the 
surface  of  a mirror  have  an  important  practical  bearing  on  the  utility  of  the  instrument,  and  the  di- 
vergence of  the  resultant  beam  materially  affects  its  fitness  for  the  purpose  of  a light-house.  So  also  in 
the  case  of  the  lens ; unless  the  diameter  of  the  flame  of  the  lamp  has  to  the  focal  distance  of  the  instru- 
ment a relation  such  as  may  cause  an  appreciable  divergence  of  the  rays  refracted  through  it,  it  could 
not  be  usefully  applied  to  a light-house ; for,  without  this,  the  light  would  be  in  sight  during  so  short  a time 
that  the  seaman  would  have  much  difficulty  in  observing  it.  To  determine  the  amount  of  this  diverg 
ence  of  the  refracted  beam,  therefore,  is  a matter  of  great  practical  importance,  and  we  shall  briefly 
point  out  the  conditions  which  regulate  its  amount,  as  they  are  nearly  identical  with  those  which  deter- 
mine the  divergence  of  a paraboloidal  mirror  illuminated  by  a lamp  in  its  focus.  The  divergence,  in 
the  case  of  lenses,  may  be  described  as  the  angle  which  the  fame  subtends  at  the  principal  focus  of  the 
lens,  the  maximum  of  which,  produced  at  the  vertex  of  Fresnel’s  great  lens  by  the  lamp  of  four  concen- 
tric wicks,  is  about  5°  9'. 

This  will  be  easily  seen  by  examining  Fig.  8297,  in  which  Q q represents  the  lens,  A its  centre,  F the 
principal  focus,  b F and  b'  F the  radius  of  the  flame ; then  is  the  angle  b A b'  equal  to  the  maximum 

divergence  of  the  lens.  Sin  b A F = — - = sin  6'AF  = ; and  twice  JAF  = the  whole 

A r focal  distance 

divergence  at  A.  Then  for  the  divergence  at  the  margin  of  the  lens,  or  at  any  other  point,  we  have 
FQ  = N/(AQ2+ AF2)  and  Q x — y/  (Q F2 -f-  F x 2) ; and  for  any  angle  at  Q,  we  have  sin  F Q x 
_ Far 
~FQ' 


On  the  subject  of  the  illuminating  power  of  the  lenses,  it  seems  enough  to  say  that  the  same  general 
principle  regulates  the  estimate  as  in  reflectors.  Owing  to  the  square  form  of  the  lens,  however,  there 
is  a greater  difficulty  in  finding  a mean  focal  distance  whereby  to  correct  our  estimate  of  the  angle  sub- 
tended by  the  light,  so  as  to  equate  the  varying  distance  o*f  the  several  parts  of  the  surface ; but,  prac- 
tically, we  shall  not  greatly  err  if  we  consider  the  quotient  of  the  surface  of  the  lens  divided  by  the  sur- 
face of  the  flame  as  the  increased  power  of  illumination  by  the  use  of  the  lens.  The  illuminating  effect 
of  the  great  lens,  as  measured  at  moderate  distances,  has  generally  beeu  taken  at  3000  Argand  flames, 
the  value  of  the  great  flame  in  its  focus  being  about  16,  thus  giving  its  increasing  power  as  nearly  equal 
to  180.  The  more  perfect  lenses  have  produced  a considerably  greater  effect. 

The  application  of  lenses  to  light-houses  is  so  obvious  as  to  require  little  explanation.  They  are  ar- 
ranged round  a lamp  placed  in  their  centre,  and  on  the  level  of  their  focal  plane  in  the  manner  shown 
in  Fig.  3298,  which  is  a vertical  section  and  plan  of  a revolving  light  of  eight  lenses,  that  form,  by  their 
union,  a right  octagonal  hollow  prism,  circulating  round  the  flame  which  is  fixed  in  the  centre,  and 
showing  to  a distant  observer  successive  flashes  or  blazes  of  light,  whenever  one  of  its  faces  crosses  a 
line  joining  his  eye  and  the  lamp,  in  a manner  similar  to  that  already  noticed  in  describing  the  action  of 
the  mirrors.  The  chief  difference  in  the  effect  consists  in  the  greater  intensity  and  shorter  duration  of 
the  blaze  produced  by  the  lens;  which  latter  quantity  is,  of  course,  proportional  to  the  divergence  of 
the  resultant  beam.  Each  lens  subtends  a central  horizontal  pyramid  of  light  of  about  46°  of  inclina- 
tion, beyond  which  limits  the  lenticular  action  could  not  be  advantageously  pushed,  owing  to  the  extreme 
obliquity  of  the  incidence  of  light;  but  Fresnel  at  once  conceived  the  idea  of  pressing  into  the  service 
of  the  mariner,  by  means  of  two  very  simple  expedients,  the  light  which  would  otherwise  have  uselessly 
“soaped  above  and  below  the  lenses. 

For  intercepting  1br  upper  portion  of  the  light,  he  employed  eight  smaller  lenses  ol  500  mm.  focal 


SEA-LIGHTS. 


611 


listance  (19'68  inches)  inclined  inwards  towards  the  lamp,  which  is  also  their  common  focus,  and  thus 
forming,  by  their  union,  a frustum  of  a hollow  octagonal  pyramid  of  50°  of  inclination..  The  light  fall- 
ing on  those  lenses  is  formed  into  eight  beams  rising  upwards  at  an  angle  of  50°  inclination.  Above 
them  are  ranged  eight  plane  mirrors,  as  in  Fig.  3299,  so  inclined  as  to  project  the  beams  transmitted  by 
the  small  lenses  into  the  horizontal  direction,  and  thus  finally  to  increase  the  effect  of  the  light.  In 
placing  those  upper  lenses,  it  is  generally  thought  advisable  to  give  their  axes  a horizontal  deviation  Oi 
no  or  go  from  that  of  the  great  lenses,  and  in  the  direction  contrary  to  that  of  the  revolution  of  the 
frame  which  carries  the  lenticular  apparatus.  By  this  arrangement  the  flashes  of  the  smaller  lenses 
precede  those  of  the  large  ones,  and  thus  tend  to  correct  the  chief  practical  defect  of  revolving  lenticular 
fights,  by  prolonging  the  bright  periods.  The  elements  of  the  subsidiary  lenses  depend  upon  the  very 
same  principles,  and  are  calculated  by  the  same  formulas  as  those  given  for  the  great  lenses.  In  fixing 
the  focal  distance  and  inclination  of  those  subsidiary  lenses,  Fresnel  was  guided  by  a consideration  of 
the  necessity  for  keeping  them  sufficiently  high  to  prevent  interference  with  the  free  access  to  the  lamp. 
He  also  restricted  their  dimensions  within  very  moderate  limits,  so  as  to  avoid  too  great  weight.  Their 
focal  distance  is  the  same  as  that  for  lenses  of  the  third  order  of  lights. 


Owing  to  certain  arrangements  of  the  apparatus  which  are  necessary  for  the  efficiency  of  the  lamp, 
but  a small  portion  of  those  rays  which  escape  from  below  the  lenses  can  be  rendered  available  for  the 
purposes  of  a light-house ; and  any  attempt  to  subject  them  to  lenticular  action,  so  as  to  add  them  to 
the  periodic  flashes,  would  have  led  to  a most  inconvenient  complication  of  the  apparatus.  Fresnel 
adopted  the  more  natural  and  simple  course  of  transmitting  them  to  the  horizon  in  the  form  of  flat 
rings  of  light,  or  rather  of  divergent  pencils,  directed  to  various  points  of  the  horizon.  This  he  effected 
by  means  of  small  curved  mirrors,  disposed  in  tiers,  one  above  another,  like  the  leaves  of  a Venetian 
blind  an  arrangement  which  he  also  adopted  (see  Fig.  3300)  for  intercepting  the  light  which  escapes 
above  as  well  as  below  the  dioptric  belt  in  fixed  lights.  Those  curved  mirrors  are,  strictly  speaking, 
generated  (see  Fig.  3301)  by  portions  such  as  a b of  parabolas,  having  their  foci  coincident  with  F,  the 
common  flame  of  the  system.  In  practice,  however,  they  are  formed  as  portions  of  a curved  surface, 
ground  by  the  radius  of  a circle,  which  osculates  the  given  parabolic  segment.  The  mirrors  are  plates 
ot  glass,  silvered  on  the  back  and  set  in  flat  cases  of  sheet-brass.  They  are  suspended  on  a circular  frame 
by  means  of  screws  which,  being  attached  to  the  backs  of  the  brass  cases,  afford  the  means  of  adjusting 
them,  to  their  true  inclination,  so  that  they  may  reflect  objects  on  the  horizon  of  the  light-house  to  an 
observer’s  eye  placed  in  the  common  focus  of  the  system. 

Having  once  contemplated  the  possibility  of  illuminating  light- houses  by  dioptric  means,  Fresnel 


012 


SEA-LIGHTS. 


* 


quickly  perceived  the  advantage  of  employing  for  fixed  lights  a lamp  placed  in  the  centre  of  a polyg 
onul  hoop,  consisting  of  a series  of  refractors,  infinitely  small  in  their  length  and  having  their  uxes  ir. 
plants  parallel  to  the  horizon.  Such  a continuation  of  vertical  sections,  by  refracting  the  rays  proceed- 
ing from  the  focus,  only  in  the  vertical  direction,  must  distribute  a zone  of  light  equally  brilliant  in 

33U0. 


every  point  of  the  horizon.  This  effect  will  be  easily  understood,  by  considering  the  middle  vertical 
section  of  one  of  the  great  annular  lenses,  already  described,  abstractly  from  its  relation  to  the  rest  of 
the  instrument.  It  will  readily  be  perceived  that  this  section  possesses  the  property  of  simply  refracting 
the  rays  in  one  plane  coincident  with  the  line  of  the  section,  and  in  a direction  parallel  to  the  horizon, 
end  cannot  collect  the  rays  from  either  side  of  the  vertical  line ; and  if  this  section,  by  its  revolution 

I 

i 


about  a vertical  axis,  becomes  the  generating  line  of  the  enveloping  hoop  above  noticed,  such  a hoop 
will  of  course  possess  the  property  of  refracting  an  equally  diffused  zone  of  light  round  the  horizon,  Fig 
8302.  The  difficulty,  however,  of  forming  this  apparatus  appeared  so  great,  that  Fresnel  determined 
to  substitute  for  it  a vertical  polygon,  composed  of  what  have  been  improperly  called  cylindric  lenses 
but  which  in  reality  are  mixtiliuoar  prisms  placed  horizontally,  and  distributing  the  light  which  they 


SEA-LIGHTS. 


G13 


receive  from  the  focus  nearly  equally  over  the  horizontal  sector  which  they  subtend.  This  polygon  has 
a sufficient  number  of  sides  to  enable  it  to  give,  at  the  angle  formed  by  the  junction  of  two  of  them,  a 
light  not  very  much  inferior  to  what  is  produced  in  the  centre  of  one  of  the  sides ; and  the  upper  and 
lower  courses  of  curved  mirrors  are  always  so  placed  as  partly  to  make  up  for  the  deficiency  of  the 
light  at  the  angles.  The  effect  sought  for  in  a fixed  light  is  thus  obtained  in  a much  more  perfect  man- 
ner than  by  any  conceivable  combination  of  the  paraboloidal  mirrors. 


3305. 


An  ingenious  modification  of  the  fixed  apparatus  is  also  due  to  the  inventive  mind  of  Fresnel,  who 
conceived  the  idea  of  placing  one  apparatus  of  this  kind  in  front  of  another,  with  the  axes  of  the 
cylindric  pieces  crossing  each  other  at  right  angles.  As  those  cylindric  pieces  have  the  property  oi 
refracting  all  the  rays  which  they  receive  from  the  focus,  in  a direction  perpendicular  to  the  mixtilinear 
cection  which  generates  them,  it  is  obvious  that  if  two  refracting  media  of  this  sort  be  arranged  as 
above  described,  their  joint  action  will  unite  the  rays  which  come  from  their  common  focus  into  a beam, 
whose  sectional  area  is  equal  to  the  overlapped  surface  of  the  two  instruments,  and  that  they  will  thus 
produce,  although  in  a disadvantageous  manner,  the  effect  of  a lens.  It  was  by  availing  himself  of  this 
property  of  crossed  prisms,  that  Fresnel  invented  the  distinction  for  lights  which  he  calls  a fixed  light 
varied  by  flashes ; in  which  the  flashes  are  caused  by  the  revolution  of  cylindric  refractors  with  vertical 
axes  ranged  round  the  outside  of  the  fixed  light  apparatus  already  described.  See  Fig.  3303. 

The  loss  of  light  by  reflection  at  the  surface  of  the  most  perfect  mirrors,  and  the  perishable  nature  of 


(314 


SEA-LIGHTS. 


the  material  composing  their  polish,  led  to  the  introduction  of  totally  reflecting  prisms  as  a substitute 
for  the  silvered  glass  mirrors  placed  above  and  below  the  great  refracting  belt.  These  prismatic  zones 
nr  catadioptric  rings,  involve  some  very  difficult  calculations  in  order  to  determine  the  proper  section  oi 
each.  In  a dioptric  light  of  the  first  order  there  are  13  zones  above  the  refractor  and  6 below  it.  In 
each  one  the  triangular  section  differs  according  to  its  position  with  respect  to  the  focal  centre  of  the 
system  of  lenses. 

The  problem  is,  therefore,  the  determination  of  the  elements  and  position  of  a triangle  ABC,  Fig. 
830-1,  which,  by  its  revolution  about  a vertical  axis,  passing  through  the  focus  of  a system  of  annular 
lenses  or  refractors  in  F,  would  generate  a ring  or  zone  capable  of  transmitting  in  a horizontal  direction, 
by  means  of  total  reflection,  the  light  incident  upon  its  inner  side  BC  from  a lamp  placed  in  the 
point  F.  The  conditions  of  the  question  are  based  upon  the  well-known  laws  of  total  reflection,  and 
require  that  all  the  rays  coming  from  the  focus  F shall  be  so  refracted  at  entering  the  surface  B C,  as  to 
meet  the  side  B A at  such  an  angle,  that  instead  of  passing  out  they  shall  be  totally  reflected  from  it, 
and  passing  onwards  to  the  side  C A shall,  after  a second  refraction  at  that  surface,  finally  emerge  from 
the  zone  in  a horizontal  direction.  For  the  solution  of  this  problem,  we  have  given  the  positions  of  F 
the  focus,  of  the  apex  C of  the  generating  triangle  of  the  zone,  the  length  of  the  side  B C,  or  C A,  and 
the  refractive  index  of  the  glass. 

The  position  of  the  several  prismatic  zones  is  shown  in  the  annexed  section,  Fig.  3305,  or  generatrix 
of  the  complete  system  drawn  in  perspective  elevation,  Fig.  3306,  which  is  a fixed  light  of  the  first 
order.  ABC,  catadioptric  zones.  JD  E F,  compound  dioptric  belt  with  diagonal  joints  C N M.  A'  B'  C', 
lower  catadioptric  zones,  one  division  being  left  out  for  free  access  to  lamp.  F,  focus  with  flame  oi 
lamp.  XXX,  diagonal  supports  for  the  upper  catadioptric  zones.  HH,  service  table,  on  which  the 
lamp  rests  and  where  the  keeper  stands  to  trim  the  burner,  and  which  is  supported  by  a pillar  resting 
on  the  light-room  floor. 

The  original  conception  of  this  magnificent  apparatus  is  seen 

in  the  annexed  diagram,  Fig.  3307,  which  represents  a plan  r-- — -, 

and  vertical  section  of  Fresnel’s  fourth  order,  combining  a 
central  annular  refractor,  with  totally  reflecting  zones  above 
and  below.  Mr.  Stevenson  has  very  unjustly  attempted  to 
appropriate  this  invention  as  his  own ; but  the  only  claim  he 
can  properly  advance  is  that  of  proposing  the  adoption  of  this 
plan  of  Fresnel's  on  a larger  scale. 

We  have  next  to  consider  the  great  lamp,  to  the  proper 
distribution  of  whose  light  the  whole  of  the  apparatus  above 
described  is  applied.  Fresnel  immediately  perceived  the  ne- 
cessity of  combining  with  the  dioptric  instruments  which  he 
had  invented  a burner  capable  of  producing  a large  volume  of 
flame ; and  the  rapidity  with  which  he  matured  his  notions  on 
this  subject  and  at  once  produced  an  instrument  admirably 
adapted  for  the  end  he  had  in  view,  affords  one  of  the  many 


„ m 

VA 

f /f.v/ 

> J i fjt 

■ \ .■/  ^ 

.. 




ZZL.JST 


proofs  of  that  happy  union  of  practical  with  theoretical  talent, 
for  which  he  was  so  distinguished.  Fresnel  himself  has  mod- 
estly attributed  much  of  the  merit  of  the  invention  of  this 
lamp  to  M.  Arago ; but  that  gentleman,  w7ith  great  candor, 
gives  the  whole  credit  to  his  deceased  friend,  in  a notice  regard- 
ing light-houses,  which  appeared  in  the  Annuaire  du  Bureau 
des  Longitudes  of  1831.  The  lamp  has  four  concentric  "burners, 
which  are  defended  from  the  action  of  the  excessive  heat  pro- 
duced by  their  united  flames,  by  means  of  a superabundant 
supply  of  oil,  which  is  thrown  up  from  a cistern  below  by  a 
clockwork  movement  and  constantly  overflows  the  wicks,  as  in 
the  mechanical  lamp  of  Carcel.  A very  tall  chimney  is  found 
to  be  necessary,  in  order  to  supply  fresh  currents  of  air  to  each 
wick  with  sufficient  rapidity  to  support  the  combustion.  The 
carbonization  of  the  wicks,  however,  is  by  no  means  so  rapid 
as  might  be  expected  ; and  it  is  even  found  that  after  they 
have  suffered  a good  deal  the  flame  is  not  sensibly  diminished, 
as  the  great  heat  evolved  from  the  mass  of  flame  promotes  the 
rising  of  the  oil  in  the  cotton.  The  large  lamp  at  the  Tour  de  Corduan  burns  for  seven  hours  without 
being  snuffed  or  even  having  the  wicks  raised;  and,  in  the  Scotch  light-houses,  it  often,  with  Colza  oil, 
maintains,  untouched,  a full  flame  for  no  less  a period  than  seventeen  hours. 

The  annexed  diagrams  will  give  a perfect  idea  of  the  nature  of  the  concentric  burner.  The  first, 
Fig.  3308,  shows  a plan  of  a burner  of  four  concentric  wicks.  The  intervals  which  separate  the  wicks 
from  each  other  and  allow  the  currents  of  air  to  pass,  diminish  a little  in  width  as  they  recede  from  the 
centre.  The  next.  Fig  3309,  shows  a section  of  this  burner.  C C1  C"  C"  are  the  rack-handles  for  raising 
or  depressing  each  wick ; A B is  the  horizontal  duct  which  leads  the  oil  to  the  four  wicks  ; L L L are 
small  plates  of  tin  by  which  the  burners  are  soldered  to  each  other,  and  which  are  so  placed  as. not  to 
hinder  the  free  passage  of  the  air;  P is  a clamping-screw,  which  keeps  at  its  proper  level  the  gallery 
It  R,  which  carries  the  chimney.  The  next,  Fig.  3310,  shows  the  burner  with  the  glass  chimney  and 
damper.  E is  the  glass  chimney;  F is  a sheet-iron  cylinder,  which  serves  to  give  it  a greater  length, 
and  has  a small  damper  D,  capable  of  being  turned  by  a handle  for  regulating  the  currents  of  air ; and 
B is  the  pipe  which  supplies  the  oil  to  the  wicks.  To  prevent  the  occurrence  of  such  accidents  as1 
itoppage  of  the  machinery  of  these  lamps,  and  to  render  their  consequences  less  serious,  various  precau 


SEA-LIGHTS. 


U1S 


tions  have  been  resorted  to.  Amongst  others,  an  alarum  is  attached  to  the  lamp,  consisting  of  a small 
cup  pierced  in  the  bottom,  which  receives  part  of  the  overflowing  oil  from  the  wicks,  and  is  capable, 
when  full,  of  balancing  a weight  placed  at  the  opposite  end  of  a lever.  The  moment  the  machinery 
stops  the  cup  ceases  to  receive  the  supply  of  oil,  and,  the  remainder  running  out  at  the  bottom,  the 
equilibrium  of  the  lever  is  destroyed,  so  that  it  falls  and  disengages  a spring  which  rings  a bclJ 
enfticiently  loud  to  waken  the  keeper  should  he  chance  to  be  asleep. 


3309. 


There  is  another  precaution  of  more  importance,  which  consists  of  having  always  at  hand  in  the 
light-room  a spare  lamp,  trimmed  and  adjusted  to  the  height  for  the  focus,  which  may  be  substituted 
for  the  other  in  case  of  accident.  It  ought  to  be  noticed,  however,  that  it  takes  about  twenty  minutes 
from  the  time  of  applying  the  light  to  the  wicks  to  bring  the  flame  to  its  full  strength,  which,  in  order 
to  produce  its  best  effect,  should  stand  at  the  height  of  nearly  four  inches  (10cm\)  The  inconveniences 
attending  the  great  lamp  have  led  to  several  attempts  to  improve  it ; and,  among  others,  M.  Delaveleye 
has  proposed  to  substitute  a pump  having  a metallic  piston,  in  place  of  the  leathern  valves,  which 
require  constant  care,  and  must  be  frequently  renewed.  A lamp  was  constructed  in  this  manner  by  M. 
Lepaute,  and  tried  at  Corduan ; but  was  afterwards  discontinued  until  some  of  its  defects  could  be 
remedied.  It  has  lately  been  much  improved  by  M.  Wagner,  an  ingenious  artist,  whom  M.  Fresnel  had 


3310. 


P3D 


Li 


3311. 


employed  to  carry  some  of  his  improvements  into  effect.  In  the  dioptric  lights  on  the  Scotch  const,  » 
common  lamp,  with  a large  wick,  is  kept  constantly  ready  for  lighting  ; and,  in  the  event  of  the  sudden 
extinction  of  the  mechanical  lamp  by  the  failure  of  the  valves,  it  is  only  necessary  to  unscrew  and  re- 
move its  burner,  and  put  the  reserve-lamp  in  its  place.  The  height  of  this  lamp  is-so  arranged  that  its 
flame  is  in  the  focus  ot  the  lenses,  when  the  lamp  is  placed  on  the  ring  which  supports  the  burner  of  the 
mechanical  lamp;  and  as  its  flame,  though  not  very  brilliant,. has  a considerable  volume,  it  answers  the 


f>l6 


SEA-LIGHTS. 


purpose  of  maintaining  the  light  in  a tolerably  efficient  state  for  a short  time,  until  the  light-keepers 
have  time  to  repair  the  valves  of  the  mechanical  lamp.  Only  three  occasions  for  the  use  of  this  reserve- 
lamp  have  yet  occurred. 

The  most  advantageous  heights  for  the  flames  in  dioptric  lights  are  as  follows : 


Inches. 

1st  Order 10  to  11  centimetres  = 3'94  to  4'33 

2d  Order 8 to  9 “ =3T5  to  3 54 

3d  Order 7 to  8 “ =2  76  to  315 


The  dioptric  system  of  Fresnel  has  another  capital  advantage  over  the  old  system  of  reflectors,  by 
which  a great  economy  is  secured,  and  what  is  more  important,  the  amount  of  light  at  each  station  can 
be  graduated  to  the  wants  of  navigation  and  the  peculiar  features  of  the  location.  The  dioptric  system 
is  divided  into  four  orders  of  magnitude,  represented  by  Figs.  3311,  3312,  and  3313,  drawn  to  a uniform 
scale.  Each  order  may  be  either  a fixed  light,  a revolving  light,  or  a fixed  light  varied  by  flashes,  or  a 
flashing  light.  Here  are  four  different  appearances  or  characteristics,  in  addition  to  which,  the  times  ot 
the  flashes  and  eclipses  can  be  so  essentially  varied  as  to  produce  new  distinctive  appearances  perfectly 
intelligible  to  the  practical  seaman. 

1.  Lights  of  tiie  1st  order,  Fig.  3212,  3312. 

have  an  interior  radius  or  focal  distance  of 
92  centimetres,  or  36  22  in.,  and  lighted  by 
a lamp  of  four  concentric  wicks,  consume 
annually  570  gallons  of  oil.  The  revolv- 
ing lights  of  this  order,  having  eight  large 
polyzonal  lenses,  with  the  catadioptric 
zones  above  and  below,  produce  a beam 
?>f  light  whose  power  is  equal  to  5000 
Argand  flames  of  one  inch  diameter  and 
one  and  a half  inch  height.  The  fixed 
lights  of  the  same  order  with  catadioptric 
cupole  and  zones,  produce  a beam  whose 
power  in  all  azimuths  is  equal  to  800 
Argand  burners,  as  above. 

2.  Lights  of  the  2d  order.  Fig.  3313, 
having  an  interior  radius  of  70  centime- 
tres, or  27'55  in.,  lighted  by  a lamp  of  3 
concentric  wicks,  consume  annually  384 
gallons  of  oil.  The  best  revolving  lights 
of  this  order  have  a brilliancy  equal  to 
3000  Argand  burners  as  above,  and  the 
fixed  lights  of  same  order,  have  a power 
in  all  azimuths  equal  to  450  such  burners. 

3.  Lights  of  the  3d  order,  having  an 
interior  radius  of  50  centimetres,  or  19'68 
inches,  and  lighted  by  a lamp  with  two 
concentric  wficks,  consume  annually  183 
gallons  of  oil.  The  revolving  lights  of 
this  order  produce  a flash  equal  to  800 
Argand  burners,  and  the  fixed  lights  of 
same  order  have  a power  in  all  azimuths 
of  100  such  burners. 

4.  Lights  of  the  4th  order,  Fig.  3311, 
nave  an  interior  radius  of  15  centimeters, 
or  5’9  in.,  and  are  lighted  writh  a simple 
Argand  burner,  consuming  annually  48 
gallons  of  oil.  The  flash  of  this  light  is 
equal  to  150  burners,  and  as  a fixed  light 
its  power  in  all  azimuths  is  25  burners. 

There  is  no  combination  of  reflectors 
that  can  be  made  to  produce  such  powers 
of  light  as  the  first  order  described  above. 

A revolving  reflecting  light,  such  as  the 
one  on  Beachy  Head,  has  three  faoes  of 
ten  reflectors  each,  whose  combined  power 
of  10X280  = 2800  burners.  We  have 
thus  three  portions  of  the  horizon  illumin- 
ated at  the  same  time  with  a power  equal 
to  2800  burners. 

The  consumption  of  oil  per  lamp  at 
Beachy  Head  is  44  gallons  per  annum,  which,  for  30  lamps,  gives  an  aggregate  combustion  of  1320  gal 
ions  of  oil  each  year.  The  aggregate  power  of  light  produced  is  2800  X 3 = 8400  burners.  A 1st  order 
dioptric  illuminates  eight  portions  of  the  horizon  at  one  time,  with  a power  of  5000  burners,  or  ar 
aggregate  effect  of  40,000  burners,  consuming  in  one  year  570  gallons  of  oil. 


SEA-LIGHTS. 


617 


We  hare  thus  the  following  comparison  : 

1st  order  dioptric  570  galls,  oil 5000X8  points  = 40,000 

1st  “ catoptric  1320  “ “ 2800X3  “ = 8,000 

Saving  in  oil  = 750  gallons  per  annum. 

Gain  of  light  = 31,600  burners  in  eight  points. 

Gain  of  light  = 3,200  “ at  any  one  point. 

The  greater  the  amount  of  sea  horizon  there  is  to  be  illuminated,  the  more  economical  and  useful 
becomes  the  dioptric  light ; while  the  catoptric  system  increases  in  first  cost,  and  maintenance  after- 
wards, by  the  same  law.  In  the.  first  no  increased  consumption  of  oil  is  caused  by  extending  the  area  of 
illumination,  while  in  the  latter  system  the  number  of  lamps  and  consequent  cost  and  consumption 
must  be  increased  in  proportion  to  the  number  of  degrees  of  horizon  to  be  lighted. 

The  spheroidal  form  of  the  earth  requires  that  the  height  of  a light-house  tower  should  increase  pro- 
portionally to  the  difference  between  the  earth’s  radius  and  the  secant  of  the  angle  intercepted  between 
the  normal  to  the  spheroid  at  the  light-house  and  the  normal  at  the  point  of  the  light’s  occultation  from 
the  view  of  a distant  observer.  The  effect  of  atmospheric  refraction,  however,  is  too  considerable  to  be 
neglected  in  estimating  the  range  of  a light,  or  in  computing  the  height  of  a tower  which  is  required  tc 
give  to  any  light  a given  range ; and  we  must,  therefore,  in  accordance  with  the  influence  of  this  element, 
on  the  one  hand  increase  the  range  due  to  any  given  height,  and,  vice  versa,  reduce  the  height  required 
for  any  given  range,  which  a simple  consideration  of  the  form  of  the  globe  would  assign.  In  ascertain 
ing  this  height,  we  may  proceed  as  follows : 


3314. 


Referring  to  the  accompanying  figure,  3314,  in  which  S'  d L'  is  a segment  of  the  ocean’s  surface,  O the 
centre  of  the  earth,  17  L a light  house,  and  S the  position  of  the  mariner’s  eye,  we  obtain  the  value  of 
LL'  = H',  the  height  of  the  tower  in  feet  by  the  formula, 
o P 

h'=t (1.) 

m which  l = the  distance  in  English  miles  L' d at  which  the  light  would  strike  the  ocean’s  surface.  We 
then  reduce  this  value  of  H'  by  the  correction  for  mean  refraction,  which  permits  the  light  to  be  seen  at 

2 P 

a greater  distance,  and  which  = - — > (2.) 


2 p op 

1 IT 


4 P 

T 


73d 


So  as  to  get, 


618 


SEAMING  MACHINE. 


an  expression  which  at  once  gives  the  height  of  the  tower  required,  if  the  eye  of  the  mariner  were  just 
on  the  surface  of  the  water  at  d,  where  the  tangent  between  his  eye  at  S and  the  light  at  L would 
touch  the  sea.  We  must,  therefore,  in  the  first  instance,  find  the  distance  dS  = l',  which  is  the  radius  ol 
the  visible  horizon  due  to  the  height  S S'  — A of  his  eye  above  the  water,  and  is,  of  course,  at  once  ob- 
tained conversely  by  the  expression, 


Deducting  this  distance  from  S L,  the  whole  effective  range  of  the  light,  we  have  L d — /,  and  operating 
with  this  value  in  the  former  equation, 


we  find  the  height  of  the  tower  which  answers  the  conditions  of  the  case.  From  the  above  data  the 
following  table  has  been  computed  : 


11 

Heights  in 

A 

Lengths  in 
English 

A' 

Lengths  in 
nautical 
miles. 

H 

Heights  in 

A 

Lengths  in 
English 
miles. 

A' 

Lengths  in 
nautical 
miles. 

H 

Heights  in 

A 

Lengths  in 
English 
miles. 

A' 

Lengths  in 
nautical 
miles. 

5 

2-958 

2-505 

70 

11-067 

9-598  I 

250 

20-916 

18-14 

10 

4-184 

3-628 

75 

11-456 

9 935 

300 

22*912 

19-87 

15 

5123 

4-443 

80. 

11-832 

10-26 

350 

24-748 

2146 

20 

5-916 

5-130 

85 

12T96 

10-57  1 

400 

26  457 

22-94 

25 

6014 

5-736 

90 

12549 

10-88  1 

450 

28-062 

24-33 

30 

7-245 

6-283 

95 

12-893 

11-18 

500 

29-580 

25-65 

35 

7-826 

6787 

100 

13-228 

11-47 

550 

31-024 

26-90 

40 

8306 

7-255 

110 

13874 

1203 

600 

32-403 

28-10 

45 

8-874 

7-696 

120 

14-490 

12-56 

050 

33-726 

29-25 

50 

9-354 

8112 

130 

15-083 

13-08  1 

700 

35-000 

30-28 

55 

9811 

8-509 

140 

15-652 

13-57 

800 

37-416 

32-45 

00 

10-240 

8-886 

150 

17-201 

14-91 

900 

39-836 

34-54 

65 

10-665 

9 249 

200 

18-708 

16-22 

1000 

41-833 

36-28 

If  the  distance  at  which  a light  of  given  height  can  be  seen  by  a person  on  a given  level  be  required, 
it  is  only  needful  to  add  together  the  two  numbers  in  the  column  of  lengths  A or  A',  (according  as  nauti- 
cal or  English  miles  may  be  sought,)  corresponding  to  those  in  the  column  of  heights  H,  which  repre- 
sent respectively  the  height  of  the  observer’s  eye  and  the  height  of  the  lantern  above  the  sea.  When 
the  height  required  to  render  a light  visible  at  a given  distance  is  required,  we  must  seek  first  for  the 
number  in  A or  A'  corresponding  to  the  height  of  the  observer’s  eye,  and  deduct  this  from  the  whole 
proposed  range  of  the  light,  and  opposite  the  remainder  in  A or  A'  seek  for  the  corresponding  number 
in  II. 

SEAMING  MACHINE,  DOUBLE.  George  R.  Moore,  Philadelphia,  Penn.  Fig.  331 5 represents 
a general  view  of  this  machine.  All  the  parts  that  are  not  lettered  compose  the  frame  simply,  the  con- 
struction of  which  is  obvious  from  the  drawing,  as  it  is  similar  to  other  tin  machines,  and  made  of  the 
same  materials ; it  may,  however,  be  varied. 

We  proceed  to  describe  the  working  machinery,  noticing  first  the  two  arbors  a and  b,  which  are  con- 
nected by  cog-wheels,  and  turned  by  the  crank  e.  Two  heads,  d and  e,  are  affixed  to  the  ends  of  these 
arbors,  and  between  these  heads  the  double  seaming  is  performed.  A pan  p is  represented  in  dotted 
lines,  as  placed  over  the  head  d,  on  the  lower  arbor,  so  as  to  bring  the  edge  which  is  to  be  seamed  down 
between  the  head  c,  and  a small  roller/,  hereinafter  described.  The  shape  of  the  head  e should  be 
carefully  noticed.  This  head  consists  of  a flanch  1,  projecting  from  a cylindrical  surface  2,  similar  to 
some  other  machines  now  in  use  ; this  cylindrical  surface  is  terminated  by  a shoulder  3,  that  connects 
with  a conical  moulding  4.  The  bevel  surface  of  the  head  e bears  first  upon  the  edge  of  the  pan,  which 
is  sustained  by  the  head  d,  the  shoulder  3,  above  named,  coming  against  the  bottom,  and  the  edge  is 
forced  to  yield  to  the  bevel  of  the  head  e,  as  this  is  screwed  down  upon  it  by  means  of  the  screw  g ; and 
should  any  part  of  the  edge  be  inclined  to  slip  out  towards  the  top  of  the  pan,  (as  this  edge  is  always 
composed  of  three  thicknesses,)  it  is  prevented  from  so  doing  by  the  little  roller/  attached  to  the  collar 
k,  that  surrounds  the  arbor  b near  the  head. 

At  this  stage  of  the  operation  the  crank  c is  turned,  the  pan  revolves  in  the  machine,  and  the  edge 
is  turned  down  as  far  as  the  bevel  part  4,  of  e , will  turn  it,  while  the  shoulder  3 prevents  the  edge  oi 
the  pan  from  bending  too  far  down  towards  the  centre ; after  this  the  head  e must  be  raised  up  a little 
by  turning  the  screw  g,  attached  to  the  box,  (in  which  the  arbor  b runs,)  and  then  the  lever  A is  brought 
into  use  to  move  the  arbor  b inwards,  by  which  the  cylindrical  part  2 of  the  head  e,  which  is  parallel 
with  the  outer  surface  of  the  head  d,  is  brought  over  the  same  and  then  screwed  down  towards  it,  by 
(he  screw  g,  when,  by  again  turning  the  crank,  the  work  is  completed.  The  outside  shoulder  1 of  the 
head  e keeps  the  bottom  of  the  pan  close  against  the  head  d.  The  lever  A passes  through  an  aperture 
in  the  frame,  where  it  has  room  to  be  moved  back  and  forth,  and  places  are  fitted  to  receive  it  when 
bo  moved,  into  which  it  is  thrown  by  a spring,  or  by  its  own  elasticity.  It  also  passes  between  two 
shoulders  on  the  arbor  b,  and  its  lower  end  is  connected  to  the  frame  by  a pivot.  Its  use  has  already 
Wen  explained,  i is  a sliding  gage  for  the  purpose  of  holding  in  proper  position  flaring  articles,  such 


619 


SEWERS. 


as  the  pan  represented  in  the  drawing,  where  the  bottom  need?  to  be  thrown  out  from  a perpendiculat 
with  the  arbors,  in  order  to  bring  the  body  parallel  with  them.  This  gage  consists  of  a shank  that  is 
attached  by  the  scr ewj  to  the  frame,  and  is  terminated  by  heads  branching  out  for  the  bottom  of  the 
pan  to  rest  against,  upon  the  inside.  This  is  found  to  be  indispensable  when  the  work  is  much  flaring. 
The  heads  of  this  gage  are  provided  with  soft  or  smooth  surfaces,  to  prevent  them  rubbing  the  tin  so  as 
to  mar  or  injure  it.  When  it  is  not  desirable  to  use  the  gage,  the  work  will  rest  against  the  head  d, 
which  is  faced  nearly  to  the  edge  with  leather,  although  other  materials  may  be  used,  to  prevent  its 
rubbing  the  tin. 


The  piece  k is  a collar  with  a lever  attached  thereto;  the  collar  part  of  it  is  fitted  upon  the  arbor  b, 
allowing  the  arbor  to  turn  freely  in  it,  while  the  upper  end  passes  through  a loop  m in  the  frame,  to 
keep  it  in  an  upright  position;  and  below  the  collar,  this  lever  passes  through  the  little  roller/.  The 
only  use  of  the  loop  m is  to  bring  the  roller/  to  bear  properly  upon  the  work ; and  to  secure  this  the 
oetter,  the  lever  k is  made  crooked  at  the  top,  so  that,  by  pressing  it  down,  this  part  of  it  is  brought 
towards  the  frame,  and  consequently  the  roller/  is  moved  up  closer  towards  e,  and  vice  versa. 

A spring  1 is  applied  to  throw  k back  as  it  rises  up,  to  make  it  easy  to  get  the  work  properly  into 
die  machine. 

SEWERS.  Subterranean  passages  formed  for  the  drainage  of  a town.  The  inclination  and  depth  of 
sewers  must  be  regulated  according  to  circumstances.  The  Ilolborn  and  Finsbury  regulations  require 
that  “the  inclination  be  not  less  than  A inch  to  every  10  feet  in  length,  and  as  much  more  as  circum- 
stances will  admit  in  those  portions  that  are  in  a straight  line,  and  double  that  fall  in  portions  that  are 
curved.”  It  is  stated  in  the  regulations  of  the  Westminster  Commission,  (1836)  that  the  current  re- 
quired for  sewers  in  all  cases  is  1J  inch  to  every  length  of  10  feet;  hut  later  regulations  order  “ that 
the  current  of  all  sewers  to  be  built,  be  regulated  by  the  commissioners  according  to  surface  required  to 
be  drained,”  without  stating  any  particular  inclination.  It  is,  as  already  observed,  frequently  a matter 
of  difficulty  to  obtain  sufficient  inclination  in  a sewer,  and  yet  to  make  it  deep  enough  to  drain  the 
basement  story  of  the  neighboring  houses. 

To  remedy  the  evils  of  insufficient  declivity,  the  process  of  flushing  has  been  adopted  in  the  sewers; 
that  is,  the  water  is  allowed  to  accumulate  for  a time  by  means  of  gates  or  dams,  and  is  then  suddenly 
let  loose  so  as  to  act  like  a powerful  current  in  sweeping  all  the  loose  matter  before  it.  Sewers  receive 
the  drainage  of  houses  by  means  of  small  channels  or  drains , usually  of  circular  form. 

The  Westminster  commissioners  require  that  the  bottoms  of  private  drains  shall  be  12  inches  above 
the  bottom  of  the  sewer ; and  they  recommend  that  such  drains  have  a fall  of  at  least  \ inch  in  a foot. 
Glazed  stoneware  pipes  are  excellent  substitutes  for  brickwork  in  the  smaller  drains.  They  are  more 
quickly  laid  than  the  others  can  be  built,  and  they  present  a much  better  surface  for  the  rapid  flow  of 
the  sewage.  They  are  constructed  in  various  forms  of  bends  and  junction  pieces,  and  from  tire  compar- 
ative thinness  of  these  pipes  a much  larger  capacity  is  obtained  with  a given  quantity  of  excavation 
for  laying  them,  than  brickwork  sewers,  which  even  for  the  smallest  diameter  cannot  be  less  than  half 
a brick,  or  4/  inches  in  thickness.  Each  pipe  has  a socket  at  one  end  for  receiving  the  plain  end  of  the 
adjoining  pipe. 

The  entrances  to  private  drains  are  usually  secured  by  a stink-trap.  These  traps  are  constructed  in  a 
variety  of  forms,  but  they  depend  for  their  action  upon  the  formation  of  what  the  chemist  calls  a water-lute. 

The  form  of  sewer  most  generally  adopted  is  the  egg  section,  with  the  smallest  end  down,  so  that 
under  a diminished  flow  the  velocity  of  the  current  may  not  be  impaired.  The  size  of  the  sewer  must 
depend  on  the  area  to  be  drained,  the  requirements  of  the  rain  shed,  and  the  house  sewage.  Knowing 
the  descent,  the  discharge  may  be  calculated  from  the  usual  formulas  for  the  flow  of  water  through  pipes, 
very  liberal  allowance  being  made  for  accidental  obstructions,  and  for  excessive  falls  of  rain.  Mr.  Phil- 
lips, before  the  Metropolitan  Sanitary  Commission  of  England,  classed  the  sewers  by  7 sizes,  the  first  being 
3.9  x 2.3,  with  an  area  of  6.6  square  feet,  and  the  7th  class  15  inches  x 9 inches,  area,  736  souare  feet. 


620 


SEWING  .MACHINES. 


SEWING  MACHINES.  The  application  of  machinery  to  the  purposes  of  sewing,  is  of  very  recen’ 
date.  It  was  only  since  the  invention  of  Mr.  Howe  in  1846,  that  it  assumed  any  practical  value,  and 
still  more  recently  by  other  improvements,  has  it  become  a household  utensil.  The  germ  of  the  sewing 
machine  is  the  tambouring  machine,  a description  of  which  may  be  found  in  the  Edinburgh  Encyclo- 
pedia, under  the  head  of  “ Chainwork.”  This  machine  contained  54  needles,  placed  one  inch  asunder 
and  was  designed  to  tambour  muslin  J wide,  one  whole  row  being  wrought  at  the  same  time.  In  the  de 
tails  of  its  construction  may  be  found  many  principles  which  are  still  employed. 

8316.  The  tambour  or  chain  stitch  is  that  in  general  use 

in  the  cheaper  single  thread  sewing  machines.  The 
form  of  stitch  is  represented  in  fig.  3316;  a loop  of 
thread  e,  is  thrust  through  the  fabric  c,  and  held 
open  till  the  next  movement  of  the  needle  forces  a second  loop  through  the  cloth  and  through  the  first 
loop;  the  first  loop  is  now  drawn  tightly,  and  the  second  loop  held  open  for  the  third  stitch,  and  so  on. 
At  the  completion  the  upper  surface  of  the  work  shows  a single  line  of  thread,  the  lower  a succession  of 
loops : about  four  and  a half  yards  of  thread  are  a fair  average  for  one  yard  of  this  work.  The  great 
objection  to  this  stitch  is  the  facility  with  which  it  may  be  ravelled,  and  on  this  account  it  is  often  used 
in  cloth  bleaclieries  and  printeries,  where  pieces  of  cloth  are  stitched  together  for  the  purposes  of  under- 
going temporary  operations.  The  low  price  of  these  machines  has  led  to  a large  sale  of  them,  and  for 
many  purposes  they  may  be  considered  of  practical  value,  but  the  purchase  and  use  of  them  tend  to 
develop  the  necessity  of  sewing  machines,  and  the  purchase  of  the  more  costly,  and  by  far  the  most  useful 
double-threaded  machines. 

Besides  the  tambour  machine,  there  are  two  other  single-threaded  machines  essentially  different  in 
principle. 

The  first  is  the  invention  of  Benjamin  W.  Bean  of  New  York  City,  patented  March  4,  1843,  reissued 
March  10,  1849.  The  following  is  the  claim  : “ What  I claim  as  my  invention  is  the  combination  of 
a straight  or  curved  needle  and  two  or  more  paired  wheels  for  forming  the  doubles  or  corrugations  of  the 
cloth,  the  whole  being  made  to  operate  together  essentially  as  above  specified,  and  in  combination  there- 
with. I claim  one  or  more  cogged  wheels,  applied  substantially  as  above  specified,  and  for  the  purpose 
of  advancing  the  doubles  of  the  cloth  along  the  needles  as  above  explained.” — This  machine  formed  a 
running  or  basting  stitch. 

Second,  the  Robinson  & Roper  machine ; this  is  essentially  a hand-sewing  machine,  single-threaded, 
forming  the  same  kind  of  stitches  that,  are  made  by  hand,  to  wit : back  stitches,  half  and  quarter  back, 
side,  sail,  quilting,  hemming,  running,  etc.  Two  needles  are  employed,  one  above,  the  other  below  the 
cloth,  traversing  large  arcs  in  a circular  slide.  The  needles  are  somewhat  like  those  used  in  the  first 
tambouring  machines.  The  eye  opens  at  the  side  for  the  slipping  in  of  the  thread,  which  is  retained 
in  its  place  by  a piston  sliding  down  through  the  upper  part  of  the  needle.  The  principle  of  the  action 
of  the  machine  is  as  follows:  a needleful  of  thread,  say  about  18  inches,  is  drawn  off  the  spool  in  its 
proper  position  beneath  the  upper  needle,  as  the  upper  needle  passes  down  through  the  cloth  it  forces 
down  a loop,  which  is  caught  in  the  eye  of  the  lower  needle,  and  by  the  down  movement  of  this  needle, 
the  whole  needleful  is  drawn  through  the  cloth,  and  by  the  return  motion  of  the  under  needle,  a loop  is 
presented  at  the  upper  surface  for  a similar  operation  on  the  part  of  the  upper  needle.  When  the 
needleful  of  thread  is  exhausted,  another  is  supplied  by  the  operator.  The  variety  of  form  of  stitch  is 
effected  by  changes  in  the  relative  position  of  the  upper  and  lower  needles. 

A similar  machine  with  a rotary  feed,  has  been  constructed  for  the  working  of  eyelet  holes;  for  this 
improvement  a patent  was  granted  to  S.  H.  Roper,  November  4,  1856. 

To  Elias  Howe,  Jr.,  of  Spencer,  Mass.,  now  of'  New  York  City,  is  due  the  credit  of  inventing  the  first 
practical  sewing  machine.  This  he  patented  in  1846,  and  under  licenses  from  him,  are  manufactured 
all  the  most  valuable  and  practical  sewing  machines,  as  I.  M.  Singer's,  Grover  & Baker’s,  and  Wheeler 

The  stitch  invented  by  Mr.  Howe  may  be  properly 
termed  a lock-stitch ; it  is  formed  with  two  threads,  one 
above  and  the  other  below  the  fabric  sewed ; inter- 
locked with  each  other  in  the  centre  of  the  fabric,  as 
in  fig.  3317,  c being  the  section  of  fabric  sewed,  e the 
thread  above  the  fabric,  and  z the  thread  below  the 
fabric ; a single  line  of  thread  extending  upon  each  sur 
face  of  the  fabric  from  stitch  to  stitch.  The  same 
thread  does  not  appear  both  above  and  below  the  fabric  at  each  alternate  stitch,  but  that  shown  upon 
the  upper  surface  is  exclusively  the  thread  e,  and  that  shown  upon  the  lower  surface  exclusively  the 
thread  z.  It  may  be  formed  by  hand  with  two  ordinary  needles  as  follows  : 

Take  two  needles  threaded  in  the  ordinary  manner,  and  a piece  of  soft  cloth ; tie  the  long  ends  of 
the  thread  together,  and  thrust  the  needle  A,  containing  the  thread  e,  through  the  cloth  head  first,  as  in 
fig.  3318,  say  three-fourths  of  an  inch ; withdraw  it  slightly,  and  a small  loop  of  the  upper  thread  e 
will  be  formed  below  the  fabric.  Through  this  loop  pass  the  needle  with  the  lower  thread  s,  and  with- 
draw the  needle  A,  entirely  from  the  fabric.  The  upper  thread  e,  thus  surrounds  the  lower  thread  z,  and 
interlocks  with  it;  the  point  of  interlocking  being  drawn  into  the  fabric  as  in  fig.  3318,  and  the  process 
repeated,  a seam  will  be  formed  with  a single  line  of  thread  visible  upon  each  surface,  and  having  the 
same  appearance  as  that  given  by  stitching.  About  two  and  one-half  yards  of  thread  are  an  average 
for  a yard  of  seam  with  this  stitch,  one  yard  being  expended  upon  the  upper  surface  of  the  fabric,  one 
upon  the  lower,  and  one-half  of  a yard  in  passing  through  the  fabric.  A firm  knot  might  be  tied  at  each 
stitch,  but  as  this  would  involve  a waste  of  thread  and  form  an  uneven  seam,  it  has  not  been  practised. 

In  the  machine  invented  by  Mr.  Howe,  this  stitch  was  formed  in  the  following  manner:  one  of  thr 


SEWING  MACHINES.  621 


threads  was  carried  through  the  cloth  by  means  of  a needle,  the  pointed  end  of  which  passed  through 
the  cloth.  The  needle  had  the  eye  to  receive  the  thread  near  the  point,  the  other  end  was  held  by  a bar 
or  arm  vibrating  upon  a pivot.  When  the  needle  was  forced  through  the  cloth  about  three-fourths  of 
an  inch,  a small  shuttle  carrying  a bobbin,  filled  with  silk  or  thread,  was  made  to  pass  between  the 
needle  and  the  thread  which  it  carried,  and  when  the  needle  was  drawn  up,  it  forced  the  thread 
received  from  the  shuttle  into  the  body  of  the  cloth  and  formed  a stitch ; this  being  repeated,  a seam 
was  formed. 

The  cloth  to  be  sewed  was  suspended  perpendicularly  upon  pins  projecting  from  a baster  plate,  be- 
tween which  and  a pad-plate  in  front  of  it,  which  pressed  the  fabric  upon  the  baster-plate,  it  passed, 
while  the  stitch  was  formed,  the  needle  having  a horizontal  action.  This  baster-plate  with  the  fabric 
was  moved  forward  by  a mechanical  contrivance,  by  which  also  the  length  of  stitch  was  regulated. 
The  invention  of  the  endless  rotary  feed,  and  the  change  of  the  needle  from  a horizontal  to  a vertical 
action,  were  the  first  improvements  upon  it.  The  baster-plate  was  abandoned,  the  fabric  was  laid 
horizontally  upon  a cloth-plate  beneath  the  vertical  acting  needle,  pressed  upon  the  plate  by  a cloth 
presser,  and  moved  forward  by  a wheel  with  pins  or  other  projections  upon  its  periphery,  penetrating 
the  fabric  from  beneath,  by  the  action  of  which  also  the  length  of  stitch  was  graduated.  The  pins 
penetrating  the  cloth  were  objectionable,  in  not  allowing  that  free  movement  to  the  fabric  which  is 
essential  in  forming  curved  seams.  A feed  was  desired  that  should  not  only  advance  the  fabric,  but 
should  intermit  its  action,  so  that  the  fabric  might  be  readily  turned  in  any  direction.  The  rough 
surface  feed,  with  the  yielding  spring  pressure  invented  by  A.  B.  Wilson,  admirably  answers  these  re- 
quirements, and  the  patent  has  become  the  joint  property  of  the  three  manufacturers  above  named. 

Many  expedients  are  devised  to  increase  the  speed  of  shuttle  machines — a machine  was  invented  in 
which  the  shuttle  had  a rotary  motion,  and  was  made  to  travel  an  entire  circuit  at  each  stitch ; but 
the  shuttle  was  kept  in  its  place  with  difficulty  ; the  thread  was  liable  to  become  entangled,  and  was 
untwisted  at  each  stitch.  Another  machine  was  invented  for  using  a shuttle  pointed  at  both  ends,  to 
take  a stitch  at  each  movement  backwards  and  forwards. 

The  sewing  machines  of  I.  M.  Singer  are  identical  in  their  stitch  with  Howe’s  machine.  Many  im- 
provements in  construction  and  in  the  details  have  been  the  subjects  of  patents  of  either  Mr.  Singer 
himself,  or  have  been  acquired  by  purchase.  In  general  arrangement  the  machines  are  strong  and 
well  made,  and  the  seam  secure.  They  are  applied  to  the  sewing  of  leather  as  well  as  that  of  cloth. 

The  Gi'over  & Baker  Machine.  Although  making  use  of  two  threads  to  form  the  stitch,  the  seam  is 
widely  different  in  its  appearance  from  that  of  the  lock  stitch ; it  may  be  called  the  double-threaded 
tambour  stitch.  Fig.  3319  represents  the  stitch  in  process  of  formation,  fig.  3320  when  completed. 

8319.  , 8320. 


On  the  upper  surface  a single  thread  is  shown,  on  the  lower  side  three.  The  upper  needle  forms  a loop 
as  in  all  machines,  and  the  seam  is  made  by  a chain  stitch  passing  through  this  loop.  The  stitch  is 
strong  and  somewhat  elastic,  and  the  machine  simple,  but  it  is  the  least  economical  of  thread  of  all  the 
machines  ; the  stitch  requiring  about  six  and  a half  yards  of  thread  for  each  yard  of  seam.  Like  all 
the  other  sewing  machines,  the  machine  embodies  several  patents. 

The  Wheeler  & Wilson  Machine.  In  1851,  Mr.  A.  B.  Wilson  patented  his  celebrated  lock-stitch 
machine,  which,  with  the  co-operation  of  Mr.  N.  Wheeler,  was  soon  introduced  into  successful  opera- 
tion. The  merit  of  Mr,  Wilson’s  invention  consists  in  the  rough  surface  feed  above  mentioned,  and  in 
the  improved  mode  and  mechanism  by  which  sewing  is  effected.  The  main  feature  of  the  invention 
consists  in  a “ rotating  hook,”  by  which  the  needle  or  upper  thread  upon  being  passed  through  the 
fabric,  is  enlarged  and  carried  around  a stationary  bobbin  containing  the  lower  tliroad,  interlocked  with 
it,  and  the  point  of  interlocking  drawn  into  the  fabric.  It  may  be  made  by  hand  in  an  analogous  manner. 


Take  an  ordinary  needle  threaded,  and  a small  ball  of  thread/,  say  of  the  size  of  a hazelnut,  as  m 
fig.  3321,  tie  the  ends  of  the  thread  together,  leaving  an  inch  or  two  of  thread  z , unrolled  from  the 
ball.  Thrust  the  needle  h,  head  first  through  the  fabric,  withdraw  it  slightly,  seize  the  loop  thus  made 
by  the  upper  thread,  enlarge  it,  and  instead  of  passing  the  ball  with  the  lower  thread  through  this 
loop,  hold  the  ball  stationary  and  pass  the  loop  around  it  as  in  fig.  3321  ; then  withdraw  the  needle 
entirely  from  the  fabric,  and  draw  up  the  loop,  so  that  the  point  of  the  threads  e and  z interlocked 
will  be  in  the  centre  of  the  fabric.  The  manner  of  making  this  stitch  with  the  AVheeier  & Wilson 
machine  is  represented  by  the  following  diagrams. 


622 


SEWING  MACHINES. 


E in  fig.  3322  is  the  rotating  hook  referred  to ; it  is  formed  by  cutting  away  a portion  of  the  peri- 
phery of  the  circular  concave  disk,  upon  the  end  of  the  arbor  C.  Y,  is  the  concavity  of  the  disk;  a, 
the  point  of  the  hook  cut  clear  to  the  point  d ; and  d is  a small  groove  diagonal  across  the  periphery  of 
the  hook  to  the  point  b,  where  the  edge  is  beveled  off ; h is  the  needle  with  the  eye  near  the  point,  that 
has  been  thrust  through  the  fabric,  with  the  thread  c,  the  loop  of  which  has  just  been  entered  by  the 
point  of  the  hook  a.  The  lower  thread  is  contained  in  a double  convex  metallic  bobbin,  to  lie  in  the 
concavity  Y of  the  hook  E,  and  held  in  its  position  by  a concave  ring  (not  represented)  between  which 


3328. 


and  the  concave  surface  of  the  disk  it  lies.  No  axis  passes  through  it,  so  that  a loop  of  thread  can 
pass  around  it  as  around  the  small  ball  of  thread  in  the  last  diagram.  By  the  revolution  of  the  hook 
after  entering  the  loop  of  the  upper  thread,  this  loop  is  enlarged  and  carried  forward.  Fig.  3323  re- 
presents the  hook  as  having  made  about  one-third  of  a revolution,  and  the  lower  thread  z extending 
from  the  lower  surface  of  the  fabric  to  the  bobbin  in  the  concavity  of  the  hook  containing  it.  The 
upper  thread  e,  extends  through  the  fabric  from  a previous  stitch,  down  into  the  concavity  of  the  disk, 
behind  the  bobbin,  around  the  hook  at  the  point  d,  thence  diagonally  along  the  groove  and  to  the  eye 
of  the  needle  h.  Fig.  3324  represents  the  hook  as  having  made  about  half  a revolution,  with  the 
bobbin  F in  its  proper  position.  The  upper  thread  c has  been  drawn  further  behind  the  bobbin,  thence 
around  the  hook  at  d,  and  diagonally  across  the  periphery  of  the  hook  in  the  groove  by  b to  h the 
needle.  As  the  hook  further  revolves  to  the  position  in  fig.  3325,  both  lines  of  the  loop  e are  upon  the 
same  side  of  the  hook.  The  line  of  thread  that  extended  in  fig.  3324  along  the  groove  of  the  hook 
from  d to  b,  has  slipped  off  at  the  termination  of  this  groove,  and  fallen  in  front  of  the  bobbin  F,  so  that 


the  loop  extends  behind  the  bobbin;  around  the  point  of  the  hook  a,  and  across  theTront  jf  the  bobbin 
to  the  needle  h,  thus  surrounding  the  bobbin  and  inclosing  the  lower  thread  z.  The  hook  revolving 
further,  the  loop  e slips  off  from  the  point  of  the  hook,  and  being  drawn  up,  interlocks  with  the  lowei 
thread  z in  the  fabric,  and  forms  a stitch  similar  to  those  represented  in  the  several  figures  above. 

The  following  is  a description  of  the  accompanying  plates. 

To  illustrate  more  clearly  the  method  of  making  the  Howe  stitch  by  the  'Wheeler  & Wilton  Machine, 
we  have  exhibited  the  rotating  hook  E and  the  bobbin  F,  carrying  the  lower  thread  detached  from  the 
machine.  In  the  subsequent  figures  the  same  parts  are  represented  in  their  proper  places  combined  with 
the  other  parts  of  the  machine,  and  which  are  respectively  numbered  as  follows:  1,  1,  the  Bed  Plate 
supporting  2,  2,  the  front  standards,  and  3,  3,  the  back  standards.  4 is  the  Arbor  with  its  bearings  in 
the  front  standards,  and  upon  which  are,  5 the  Rotating  Hook,  6 the  Feed  Cam,  7 the  Band  Pulley,  8 
the  Eccentric  Ring,  and  9 the  Spooling  Spindle,  bloving  in  grooves  in  the  front  standards  is  10  the  Feed 
Bar ; 11,  11,  Ears  of  the  feed  bar,  12  the  Spiral  Feed  Spring,  working  between  the  left  front  standard 
and  the  left  ear  of  the  feed  bar.  13  the  Feed  Tongue,  slrtted  in  the  feed  bar,  and  furnished  with  14 


SEWING  MACHINES. 


628 


Feed  Points.  15  is  the  double  convex  metallic  Bobbin,  containing  the  lower  thread,  and  held  in  the 
concavity  of  the  rotating  hook  by  16,  the  Bobbin  Ring,  mounted  upon  17,  the  Ring  Bar,  sliding  in  a 
groove  in  the  bed  plate,  and  held  by  18  the  Thumb  Screw.  19  is  the  Fixed  Arm,  projecting  from  the 
back  standard,  and  supporting  20,  the  Cloth  Pressor,  attaclted  to  the  Piston  in  2 1,  the  Piston  Cylinder. 
22  is  the  Thumb  Screw  of  the  cloth  presser,  23  the  Lever  of  the  cloth  presser.  24  is  the  Needle  Rocker, 
pivoted  upon  25,  25,  the  Centre  Screws,  26  the  Short  Arm  of  the  rocker  hinged  by  27  to  28  the  Con- 
necting Rod.  Upon  the  rocker  is  29  the  Needle  Arm,  bearing  30  the  Thread  Spool,  31  the  Spool  Brake,  32 
the  Brake  Screw,  33,  33  the  Thread  Eyelets,  34  tlie  Needle  Yoke,  35  the  Needle.  36  is  the  Loop  Check, 
37  the  Spool  Pin,  38  a spool  of  Thread,  39  a Thread  Guide,  40  a Tension  Pulley,  41  volute  Tension  Spring, 
42  large  Seam  Gauge,  43  Gauge  Screw,  44  Screw  for  Small  Gauge,  45  the  fabric  sewed,  46  the  Cloth 
Plate,  47  Table  Screws.  52  Feed  Slots,  53  Set  Screw,  54  Feed  Stop,  55  Stop  Pivot,  56  Thread  Guard, 
57  Thread  Hold,  58  small  Gauge,  59  Spiral  Spring  of  the  cloth  presser,  60  Needle  Hole. 

In  constructing  the  machine,  the  lower  surface  of  the  bed-plate  1 1 is  planed  with  perfect  exactness, 
and  made  the  plane  to  which  all  the  planes  and  lines  of  the  machine  are  adjusted.  The  standards  2 2 
are  levelled  to  a plane  parallel  with  the  plane  of  the  bed-plane,  at  a fixed  height  above  it,  and  pierced 
in  another  parallel  plane  for  the  arbor  4,  and  grooved  in  a parallel  line  for  the  feed-bar  10.  The  bed- 
plate is  grooved  in  the  same  line  for  the  slide  bar  1 7 ; the  standards  3 3,  are  pierced  parallel  to  the  line 
of  piercing  in  2 2,  for  the  centre  screws  25  25 ; and  the  arbor  4,  and  the  rocker  24,  are  adjusted  parallel  to 
each  other  and  to  the  plane  of  the  bed-plate  1 1.  The  connecting-rod  28,  the  short  arm  26,  the  needle 
arm  29,  the  fixed  arm  19,  are  adjusted  at  right  angles  to  the  lines  of  4 and  24.  The  rotating  hook  5, 
the  bobbin  15  and  the  needle  35,  move  in  planes  vertical  to  the  plane  of  the  bed-plate  1 1.  The  rotating 
hook  is  a portion  of  the  thread  of  a screw,  formed  upon  the  periphery  of  this  circular  concave  disc. 
To  the  left  of  the  notch  d,  is  a portion  of  another  parallel  thread  of  the  screw:  the  disc  is  cut  away 
below  the  point  d into  its  concavity,  so  that  the  thread  of  the  screw  forms  the  clear  point  of  the  hook  a. 
The  groove  between  the  two  threads  of  the  screw  extends  diagonally  across  the  periphery  of  the  hook  disc 
to  the  point  6,  where  the  hook  thread  of  the  screw  is  entirely  chamfered  off  and  the  groove  disappears. 
The  concave  surfaces  of  the  disc,  and  the  slide  ring  16,  contain  the  bobbin  15  ; the  needle  35  is 
curved  to  the  arc  in  which  the  end  of  the  needle  arm  vibrates.  A perfectly  rectangular  figure  is  formed  : 
the  arbor  4 forms  one  side  ; the  connecting-rod  28,  the  second  ; the  rocker  24,  the  third  ; and  the  needle 
arm  29,  with  the  needle  35,  and  the  rotating  hook  5,  the  fourth.  The  opening  is  made  for  sewing  be- 
tween the  needle  and  the  hook. 

The  working  parts  are  secured  to  a frame  constituted  by  the  bed-plate  1 1,  and  the  standards  there- 
on, 2 2 and  3 3.  The  slide  ring  16,  is  adjusted  by  the  set  screw  53,  to  retain  the  bobbin  15,  and  allow 
it  to  turn  freely  in  the  concavity  of  the  hook  disc.  The  needle  35  is  adjusted  with  its  head  in  the  needle 
yoke  34,  to  vibrate  through  a small  hole  60,  in  the  cloth  plate  46,  and  so  that  in  its  rise  the  eye  will 
be  brought  just  below  the  point  of  the  hook  a,  which  revolves  so  close  by  the  right  side  of  the  needle  35, 
that  nothing  can  lie  between  them  as  they  come  opposite  each  other.  The  eccentric  ring  8,  through  the 
connecting-rod  28  and  the  rocker  24,  vibrates  the  needle  arm  so  that  it  begins  to  rise  just  before  the 
point  of  the  hook  a reaches  the  needle.  The  pressure  of  the  fabric  upon  the  thread  about  the  needle  as 
it  begins  to  rise,  loops  the  thread  slightly  upon  the  right  of  the  needle ; this  loop  is  caught,  enlarged 
and  carried  around  the  bobbin  as  before  illustrated.  When  the  loop  of  thread  is  about  to  slip  from  the 
hook,  as  is  represented  on  fig.  3325,  it  is  checked  for  an  instant  until  the  hook  has  completed  its  full 
revolution  and  enters  the  next  loop,  in  the  process  of  enlarging  which,  it  draws  up  the  loop  already 
formed.  36,  the  loop  check  employed,  is  a small  piece  of  leather  or  an  equivalent,  held  in  contact  with 
the  periphery  of  the  hook,  so  that  the  loop  cannot  pass  until  the  chamfered  part  b of  the  hook  reaches 
and  frees  it,  as  it  does,  just  as  the  hook  enters  the  next  loop. 

This  rotating  hook  is  of  singularly  ingenious,  simple,  and  novel  construction,  and  is  equivalent  to 
several  pieces  of  elaborate  machinery.  It  performs  the  three  operations  of  enlarging  the  loop  of  the 
upper  thread,  passing  it  around  the  bobbin  carrying  the  lower  thread,  and  tightening  the  preceding 
loop 

The  bobbin  15  is  placed  in  its  proper  position,  with  the  thread  flowing  from  the  top  towards  the  front 
of  the  machine,  in  which  direction  it  revolves  slowly.  The  thread  is  wound  upon  this  bobbin  with 
great  facility,  at  the  rate  of  one  hundred  yards  per  minute.  For  this  purpose  it  is  placed  upon  the 
spooling  spindle  9,  and  the  spool  of  thread  upon  the  spool  pin  37 ; the  thread  is  then  rewound  upon  the 
bobbin  by  working  the  treadles  as  in  sewing. 

The  upper  thread  may  be  used  from  the  original  spool  38,  or  from  another  spool  30  on  which  it  has 
been  rewound.  The  tension  of  the  two  threads  used  is  a point  of  importance.  To  form  the  stitch  per- 
fectly, the  point  of  interlocking  the  two  threads  should  be  drawn  to  the  centre  of  the  fabric  sewed, 
so  that  each  thread  may  be  held  firmly,  and  the  seam  present  the  same  appearance  upon  each  side — a 
single  line  of  thread  extending  from  stitch  to  stitch.  In  this  machine  the  tension  of  the  lower  thread  is 
rendered  sufficiently  great  by  the  friction  between  the  surface  of  the  bobbin  15,  and  the  rotating  hook 
in  the  cavity  of  which  it  is  placed,  the  two  revolving  in  opposite  directions.  The  tension  of  the  upper 
thread  must  be  so  adjusted,  as  to  draw  the  lower  thread  into  the  fabric  in  the  formation  of  a stitch. 

Were  the  spools  of  thread  always  uniform,  and  the  thread  uniformly  wound,  there  would  be  no  diffi- 
culty in  using  the  thread  from  the  original  spool.  But  this  is  not  the  case.  In  fig.  3331  it  is  shown  as 
fed  from  the  original  spool  38,  through  the  thread  guide  39,  to  the  tension  pulley  40,  and  thence 
through  the  eyelets  33,  33,  to  the  needle  35.  The  tension  is  attained  by  the  volute  spring  41,  pressing 
upon  the  wheel  40,  which  may  be  regulated  at  pleasure  by  the  thumb  screw  at  the  end.  In  fig.  3331 
the  tension  is  attained  by  the  break  31,  upon  the  spool  30,  and  which  is  regulated  by  the  thumb  screw 
32.  The  next  point  of  importance  is  the  Feed  This  is  that  part  of  the  mechanism  by  which  the  fabric 
to  be  sewed  is  moved  forward,  and  the  length  of  stitch  regulated.  The  length  of  stitch  does  not  depend 
at  all  upon  the  speed  of  the  machine,  but  upon  the  feed  alone. 


624 


SEWING  MACHINES 


22 


22 


^rr~n  y ■ ■ ■ 


n 

1 

W 

Iw 

§ 

p 

If 

H 

eh 

SEWING  MACHINES. 


625 


22 


3333. 


Vox.  II. — 40 


SEWING  MACHINES. 


B26 


The  feed  consists  of  a bar  10,  lying  in  grooves  in  the  front  standards,  and  directly  beneath  the  cleft 
plate  46.  It  has  a slot  nearly  its  entire  length,  in  which  is  pivoted,  near  the  left  end,  a tongue  13,  with 
its  right  end  resting  upon  the  right  front  standard,  armed  with  two  rows  of  small  points  14.  The  rela- 
tive position  of  the  feed  bar  and  its  appendages  to  the  cloth  plate  is  best  seen  in  fig.  3327.  The  cloth 
plate  is  furnished  with  a slot  52,  through  which  the  feed  points  when  raised  project,  and  enter  the  fabric 
held  upon  the  cloth  plate  by  the  cloth  presser  20.  The  feed  is  worked  by  the  cam  6,  which  rotates  with 
the  arbor  4.  As  this  cam  revolves,  the  swell  of  its  periphery  strikes  the  under  surface  of  the  feed 
tongue  15,  and  raises  the  feed  points  14,  through  the  slot  52,  while  the  swell  on  the  right  side  of  tlia 
cam  6,  presses  upon  the  right  ear  11  of  the  feed  bar,  and  throws  it  forward.  The  cam  further  revolv- 
ing, brings  a point  of  depression  both  on  its  periphery  and  its  side  next  to  the  feed  bar  ear,  when  the 
points  drop  below  the  surface  of  the  cloth  plate,  and  the  feed  spring  12,  throws  the  bar  back  to  the  left 
against  the  feed  slot  54,  and  the  next  revolution  of  the  cam  throws  it  forward  again.  It  will  he  ob- 
served that  while  the  needle  penetrates  the  cloth,  the  feed  points  are  below  the  surface  of  the  cloth 
plate,  and  intermit  their  action  upon  the  cloth ; hence  the  needle  constitutes  a pivot  upon  which  the 
fabric  may  he  turned  to  sew  a curved  seam  of  any  radius. 

The  feed  points  rising  and  penetrating  the  cloth  at  each  stitch,  their  movement  forward  determines 
the  length  of  the  stitch,  which  is  graduated  by  regulating  the  play  of  the  feed  bar.  The  play  of  this 
bar  is  limited  to  the  difference  between  the  narrowest  and  the  widest  parts  of  the  feed  cam,  which  is 
about  one-fourth  of  an  inch,  and  may  be  graduated  to  any  length  within  these  limits  by  the  eccentric 
feed  slot  54,  against  which  the  heel  of  the  feed  bar  is  thrown  by  the  feed  spring  12.  As  the  narrowest 
or  widest  parts  respectively  of  this  slot  are  turned  towards  the  feed  bar,  greater  or  less  play  of  it  is  per- 
mitted, and  longer  or  shorter  stitches  are  made.  This  slot  is  turned  with  great  facility  while  the  ma- 
chine is  in  motion,  by  pressing  upon  the  lever  with  which  it  is  furnished.  The  machine  when  used 
is  mounted  upon  a neat  work-table,  and  driven  by  sandal  treadles  and  band  7.  The  fabric  to  be  sewed 
45,  is  laid  upon  the  cloth  plate  46,  beneath  the  needle,  and  held  by  the  cloth  presser  20.  The  operator 
seats  herself  before  the  table,  on  which  the  machine  is  placed,  with  her  feet  upon  the  sandal  treadles 
by  which  the  machine  is  driven.  The  threads  being  adjusted,  the  machine  is  touched  into  motion  by 
a gentle  pressure  of  the  feet  upon  the  sandals.  The  cloth  moves  forward  from  left  to  right,  and  the 
sewing  is  accomplished  in  the  manner  above  described.  Two  and  one-half  }ards  of  thread  is  the 
average  required  for  a yard  of  sewing.  There  is  no  limit  to  the  number  of  stitches  that  may  be  made 
in  any  given  time.  The  driving  wheel  is  graduated  ordinarily  so  as  to  make  five  stitches  at  each 
tread,  so  that  from  six  hundred  to  one  thousand  stitches  per  minute  are  readily  made. 

The  bearings  and  friction  surfaces  are  so  slight,  that  the  propelling  power  required  is  merely  nominal. 
The  rotary  hook,  feed,  bobbin,  and  other  parts  at  all  subject  to  wear,  are  made  of  finely  tempered  steel  • 
the  other  parts  of  the  machine  are  tastefully  ornamented,  or  heavily  silver  plated. 

Various  appliances  are  furnished  for  regulating  the  widths  of  hems,  etc.,  as  42  and  53.  The  seam  guide 
42  is  attached  to  the  fixed  arm  19,  by  the  thumb  screw  43,  and  extends  down  over  the  cloth  plate  with 
various  projections  for  guiding  the  work.  It  is  slotted  and  jointed  so  as  to  be  adjusted  in  various  positions. 
A smaller  gauge  58  is  commonly  used,  but  not  in  conjunction  with  42.  It  is  fastened  to  the  cloth  plate 
by  the  thumb  screw  42. 

Another  appendage  is  the  hemmer  48 ; it  is  used  in  place  of  the  cloth  presser  20,  and  is  in  fact  a 
cloth  presser,  so  convoluted,  that  as  the  edge  of  the  cloth  passes  through  it  is  turned  down  as  in  ordinary 
hemming  and  beautifully  stitched.  All  numbers  of  thread  are  used,  and  needles  of  various  sizes  are  fur- 
nished suited  to  the  several  threads. 

Thousands  are  used  by  seamstresses,  dressmakers,  tailors,  manufacturers  of  skirts,  cloaks,  mantillas, 
clothing,  hats,  caps,  corsets,  ladies’  gaiters,  umbrellas,  parasols,  silk  and  linen  goods  with  complete  suc- 
cess ; sometimes  from  one  hundred  to  two  hundred  are  used  in  a single  manufactory.  The  amout  of 
sewing  that  an  operator  may  accomplish  depends  much  upon  the  kind  of  sewing  and  her  experience ; one 
thousand  stitches  per  minute  are  readily  made,  which  would  form  more  than  a yard  of  seam  with  stitches 
of  medium  length.  Fifty  dozens  of  shirt  collars,  or  six  dozens  of  shirt  bosoms  are  a day’s  work.  Upon 
straight  seams  an  operator  with  one  machine  will  perform  the  work  of  twenty  by  hand ; on  an  average 
one  probably  performs  the  work  of  ten  seamstresses. 

The  Wheeler  & Wilson  machine  is  applicable  to  every  variety  of  sewing  for  family  wear  ; from  the 
lightest  muslins  to  the  heaviest  cloths,  it  works  equally  well  upon  silk,  linen,  woolen  and  cotton  goods, 
seaming,  quilting,  hemming,  gathering  and  felling,  performing  every  species  of  sewing  except  making 
button-holes,  stitching  on  buttons,  and  the  like.  Its  mechanism  is  the  fruit  of  the  highest  inventive 
genius,  combined  with  practical  talent  of  the  first  order.  Its  principles  have  been  elaborated  with  great 
care,  and  it  involves  all  the  essentials  required  in  a family  sewing  machine.  It  is  simple  and  thorough 
in  construction,  elegant  in  model  and  finish,  facile  in  management,  easy,  rapid,  and  quiet  in  operation, 
and  reflects  additional  credit  upon  American  mechanical  skill. 

SHEARS  ROTARY,  Ruggles’  Patent.  This  machine  is  made  of  sizes  adapted  to  cut  sheet  metal  of 
all  numbers.  One  straight  and  one  circular  cutter  are  employed,  the  latter  being  revolved  and  moved 
slowly  along  the  edge  of  the  former.  The  cutting  edges  do  not  lap  by  each  other  except  iu  cases  of  very 
thin  metal,  but  are  at  a vertical  distance  of  about  half  the  thickness  of  the  metal  to  be  cut. 

SHEARS  ROTARY.  Fig.  3320  Js  a representation  of  Bulkley  & Norton’s  patent  improved  rotary 
shears.  The  shears,  when  used,  stand  in  the  position  of  the  figure,  and  revolve  upon  the  perpendicular 
axis  or  standard.  The  material  to  be  cut  is  placed  between  the  clamps,  put  up  to  the  cutters  and  the 
gauge,  and  held  there  by  the  screw,  and  is  cut  by  one  revolution  of  the  machine. 

The  cutters  revolve  and  are  placed  upon  a movable  half  bows,  which  is  easily  set  to  any  required 
size.  A boy  can  use  them,  and  his  work  will  be  cut  perfect,  while  there  is  great  saving  of  labor  and 
stock,  as  it  leaves  the  work  and  pieces  perfectly  smooth.  They  will  cut  any  wire  varying  but  a hair’s 
breadth  from  21  to  22  inches  in  diameter.  The  above  shears  have  been  in  constant  use  in  various 


SHINGLER,  BURDEN’S  PATENT. 


627 


heavy  manufacturing  establishments  more  than  five  years,  and  the  many  high  testimonials  of  theil 
value  which  we  have  seen  are  fully  corroborative  of  their  excellence.  When  tin  is  required  to  be  cut 
in  a circular  form  these  shears  must  be  exceedingly  useful ; indeed  it  is  said  that  an  entire  box  of  tin 
can  be  cut  perfectly  uniform  in  twenty  :r  thirty  minutes  by  this  improvement.  Orders  for  these  shears 
are  addressed  to  the  patentees  and  proprietors,  Messrs.  Bulkley  & Norton,  Berlin,  Conn. 


O 


nr 


3326. 


SHINGLER,  BURDEN’S  PATENT.  This  machine,  which  is  represented  in  Figs.  3327,  3328,  and 
3329,  is  the  invention  of  Henry  Burden,  Esq.,  of  the  Troy  Iron  Works,  New  Tork.  Fig.  3327  is  a 
cross-section  through  B F E.  Fig.  332S  is  a vertical  section  through  B F E.  Fig.  8329  is  a perspective 


view  ABODE  are  five  pillars  fixed  to  the  sole-piece  1 1 1 1,  which  support  the  strong  eccentric  eas 
iog  H H H H,  and  the  top  journal  of  the  shaft  F.  G G is  a cylinder  keyed  on  the  shaft  F,  and  driven 


628 


SHINGLER,  BURDEN'S  PATENT. 


SHOT,  SMITH’S  PATENT. 


629 


in  the  direction  of  tlie  arrow  by  the  pinion  I.  K K is  a heavy  ring  or  thimble  which  is  allowed  to  rise 
and  fall  up  and  down  the  shaft  F ; its  weight  upsets  the  upper  end  of  the  bloom.  The  dotted  line  at 
L represents  a large  hook,  to  deliver  the  bloom  when  finished.  The  dotted  line  at  M represents  a 
scraper  to  clean  away  any  slag  that  may  remain  on  the  flange  of  the  cylinder.  D is  the  rough  bloom 
entering,  and  E is  it  just  leaving  in  its  finished  state.  F FFF  are  flanges  to  strengthen  the,  eccentric 
casing.  The  bloom  being  thrown  in  at  the  wide  end  is  laid  hold  of  by  the  cylinder,  and  by  its  action 
pressed  against  the  outside  casing,  and  revolving  on  its  own  axis,  is  taken  through  the  machine,  being 
thus  gradually  brought  to  its  finished  state,  and  at  the  same  time  deprived  of  its  scoria.  The  under 
end  of  the  bloom  is  upset  by  the  action  of  the  flange  of  the  cylinder,  and  the  upper  end  by  that  of  the 
lifting-ring  K K,  in  the  most  perfect  manner. 

Tlie  advantages  are : — 1.  The  entire  saving  of  shingler’s  wages,  no  attendance  being  necessary.  2. 
Very  considerable  saving  in  first  cost.  3.  Great,  or  rather,  almost  entire  saving  of  repairs.  4.  Con- 
siderable saving  in  power.  5.  The  immense  saving,  in  time,  from  the  quantity  of  work  done,  one  ma- 
chine being  capable  of  working  to  sixty  puddling  furnaces.  6.  Saving  of  waste,  nothing  but  the  slag 
being  thrown  otf.  7.  The  staffs  are  also  saved.  8.  It  will  be  readily  seen,  from  the  shortness  of  the 
time  required  to  finish  a bloom,  (six  or  seven  seconds,)  that  tlie  scoria  can  have  no  time  to  set,  and  is 
thus  got  rid  of  much  better  than  when  allowed  to  congeal.  9.  The  blooms  from  this  machine  being 
discharged  so  perfectly  hot,  they  roll  much  better,  and  thus,  besides  being  much  easier  on  the  rollers, 
the  bars  produced  are  much  sounder  and  better  finished. 

By  the  use  of  this  machine,  common  iron,  of  an  excellent  quality,  can  be  finished  off  at  the  first  heat, 
viz.,  that  of  the  puddling  furnace. 

SHINGLE  MACHINE — JOHNSON'S.  Fig.  3331  represents  a machine  invented  by  Mr.  J.  G. 
Johnson,  of  Augusta,  Maine. 

The  machinery  is  adjusted  to  a frame  of  10  feet  in  length  by  3 feet  10  inches  in  width.  On  this  is 
placed  a movable  carriage  E E,  which  runs  on  trucks  attached  to  the  carriage  F F.  B is  the  block  or 
bolt  of  wood  to  be  sawed,  and  is  held  in  its  place  by  dogs.  C is  a piece  of  wood  fastened  on  the  end 
of  the  frame,  the  object  of  which  is  to  cause  the  lever  D to  turn  the  set-shaft  one  quarter  round  every 
time  the  carriage  returns  back ; this  lever  is  raised  by  a piece  of  wood  fastened  to  the  main  frame.  To 
this  lever  is  also  fastened  a hook,  which  hooks  on  to  the  set-shaft.  G G are  handles  attached  to  a rod 
which  has  a cam  on  it.  By  turning  the  handles  up,  the  rack  is  raised  out  of  geer  and  stops  the  carriage 
while  the  operator  supplies  another  bolt  or  block  of  wood.  The  set-shaft  has  a dog  on  each  end,  placed 
at  right  angles  so  as  not  to  set  but  one  of  the  blocks  at  a time.  Those  dogs  move  two  gages  that  are 
secured  to  the  headstock  which  holds  tlie  block  or  bolt  of  wood.  The  carriage  is  fed  by  a decreased 
motion  received  from  the  saw-shaft. 


SHOT.  The  usual  method  of  making  lead  shot,  is  by  letting  melted  lead,  with  a small  alloy  of  ar- 
senic, fall  through  the  air  from  a considerable  elevation,  and  thus  the  leaden  rain  becomes  cold,  and 
solidified  into  leaden  hail  or  shot.  To  carry  out  this  process,  high  shot  towers  are  erected  ; at  the  top 
the  lead  is  melted  and  poured  into  colanders  with  different  sized  holes  according  to  the  size  of  the  shot 
required.  That  the  shot  may  not  be  bruised  in  falling  upon  one  another,  they  are  received  into  a ves- 
sel of  water  at  the  bottom.  To  separate  the  imperfect  shot,  a slab  of  polished  iron  is  tilted  at  a certain 
angle,  and  the  shot  are  strewed  along  the  upper  part  of, the  ipclined  plane  thus  formed.  The  perfect 
shot  proceed  rapidly  in  straight  lines  and  fall  into  a bin  placed  to  receive  them,  about  a foot  distant  from 
the  bottom  of  the  slab,  whilst  the  misshapen  shot  on  the  contrary,  travel  with  a slower  zig-zag  motion 
and  fall  without  any  bound  into  a bin  immediately  at  the  foot  of  the  incline. 

To  obviate  the  necessity  and  expense  of  high  towers,,  an  expedient  is  in  use  for  causing  the  fused 
metal  to  fall  through  an  ascending  current  of  air.  This  method,  of  which  the  following  is  a description, 
has  been  secured  to  David  Smith  by  patent. 

Fig.  3332  is  a vertical  sectional  elevation  of  a sheet-metal  cylinder,  set  up  as  a tower  within  a build- 
ing, and  may  be  of  about  twenty  inches  internal  diameter  to  eaph  fifty  feet  of  height,  or  nearly  in  such 
proportions  for  other  heights.  Fig.  3333  is  a plan  at  the  line  A B of  Fig.  3332 ; Fig.  3334  is  a plan  at 
.he  line  C D of  Fig.  3332 ; Fig.  3335  is  a plan  at  the  line  E F of  Fig.  3332 ; and  Fig.  3336  is  a plan  at 


630 


SHOT,  SMITH’S  PATENT. 


the  line  G H of  Fig.  3332.  The  similar  letters  used  as  marks  of  reference  apply  to  the  like  parts  in  all 
the  figures. 


3333.  3334. 


In  these,  I is  a -water-cistern  beneath  the  tower.  A is  a pipe  from  any  competent  blowing  apparatus, 
leading  into  a hollow  annular  ring-chamber  b,  the  bottom  of  which  is  to  be  supported  in  any  proper 
manner  above  the  cistern  I ; the  inner  face  forms  a portion  of  the  passage  for  the  descending  shot ; the 
upper  face  c is  fitted  with  holes,  as  shown  in  plan  Fig.  3334,  to  pass  and  dispense  the  entering  and  as- 
cending air ; and  the  outer  side  of  the  ring  b forms  the  base  of  a truncated  cone  that  sustains  a metal 
cylindrical  tower  dd , which  at  ee  spreads  to  pass  the  ascending  blast  through  a frame  //;  this  is  shown 
in  plan  Fig.  3335,  and  in  Fig.  3332  is  shown  as  sustaining  a cylindrical  standard  g,  the  upper  central 
portion  of  which  receives  the  pouring-pan  /t : this  is  made  changeable  for  each  separate  size  of  shot,  to 
be  made  by  larger  or  smaller  holes  through  the  bottoms  of  the  successive  pans,  as  usual ; and  round 
the  pouring-pan  h is  a circular  waste-trough  i ; round  these  parts  the  tower  dd  finishes  also  a trumpet- 
mould  K K.  The  intent  and  effect  of  this  arrangement  is,  that  the  fluid  metal  running  through  the 
pouring-pan  h into  the  ascending  current  of  air,  in  a tower  fifty  feet  high,  when  the  air  is  passing  up 
with  twice  the  velocity  of  the  descending  metal,  will  be  operated  on  to  the  same,  or  to  a greater  extent, 
by  the  air,  as  when  it  falls  through  the  stagnant  air  in  a costly  tower  of  one  hundred  and  fifty  feet  or 
more  high ; and  in  the  like  proportions  with  the  greater  or  less  velocities  of  the  ascending  current  of  air. 
The  particles  of  metal  fall  through  the  open  centre  of  the  ring  b into  the  water  in  the  cistern  I,  where, 
for  convenience,  a shoot  l carries  the  particles  of  metal  into  a tub  m,  which  may  be  placed  empty,  and 
removed  when  full  through  a scuttle  n in  the  cover  of  the  cistern. 

The  patentee  does  not  intend  to  confine  himself  to  the  proportions  of  the  parts  as  here  described,  nor 
does  he  intend  confining  himself  to  the  parallel  cylindrical  form  of  the  tower  dd,  kk,  as  this  may  be 
made  more  or  less  conical ; and  the  other  parts  may  be  varied  in  any  way  that  is  substantially  tha 
same,  in  the  means  employed  to  produce  the  like  and  intended  effects. 

SHUTTLES.  See  Loom. 

SILEX.  The  earth  of  flints.  The  characteristic  ingredient  of  a great  variety  of  minerals,  as 
quartz,  chalcedony,  flint,  etc. ; the  predominating  material  in  granite,  many  varieties  of  sand  stone 
and  quartz  rock.  Its  chief  importance  in  practical  arts  is  in  the  manufacture  of  Glass. 

SILVER.  See  Metallurgy. 

SINKING.  In  mining,  digging  downwards.  In  rising  and  sinking  a shaft  one  set  of  men  sink  from 
an  upper  level  while  auother  set  rises  from  a lower  level  and  meet  them. 

SLATE.  An  argillaceous  stone,  readily  split,  and  employed  to  cover  the  roofs  of  buildings.  Most  of 
the  slate  at  present  used  in  this  country  is  Welsh,  but  within  a few  years  it  has  been  extensively  quar- 
ried in  Vermont. 

Slate  has  heretofore  been  all  cut  out  in  quarries  by  hand  labor.  The  workmen  with  picks  cut  grooves 
in  the  rock  to  the  depth  required,  and  then  the  slate  comes  off  in  thin  layers  the  size  of  the  space  be- 
tween the  cut  grooves,  forming  rectangular  slabs.  To  supersede  this  slow  method  of  quarrying  slate. 
H.  J.  Bremner,  of  Nazareth,  Pa.,  has  invented  a machine,  in  which  cutters  are  operated  so  as  to  feed 
forward  and  cut  out  a groove  in  one  direction,  the  desired  length,  and  then  it  (the  machine)  is  turned, 
and  the  cutters  made  to  cut  a transverse  groove,  and  thus  proceed  until  the  rock  is  so  grooved  that  the 
space  between  the  side  and  two  end  grooves  or  cut  channels,  forms  a slab  of  the  size  desired  for  the 
slate ; the  slate  is  then  forced  out,  and  splits  easily  into  as  many  separate  slabs  as  there  have  been  hori- 
zontal layers  from  the  surface  to  the  depth  the  cutters  have  penetrated. 

Machine  far  Cutting  and  Trimming  Slate.  A machine  for  cutting  and  trimming  slate  has  been  invented 
and  patented  by  Asa  Keyes,  of  Brattleboro’,  Vermont.  The  nature  of  the  invention  consists  in  apply- 
ing a rapid  succession  of  stone  hammer  blows,  each  of  which  beats  off  a minute  piece  of  the  slate, 
while  it  (the  slate)  is  carried  along  by  a carriage  on  ways.  The  wheel  which  carries  the  hammers  or 
cutters  is  heavy,  and  this  weight  of  the  wheel  not  only  furnishes  the  momentum  of  the  individual  blows 
of  each  hammer,  hut  supplies  the  purpose  of  a fly-wheel  to  the  machine.  The  hammers  are  held  into 
mortises  cast  in  the  wheel,  by  bolts  and  nuts. 

SLEEPERS.  Pieces  of  timber  laid  on  the  ground,  taking  a bearing  their  whole  length;  the  term  ? 
applied  to  the  cross  ties  on  a railroad. 

SLIDE-REST.  See  Tools. 

SLIDE  VALVE.  See  Engines,  and  Lap  and  Lead  of  Slide  Valves. 

SLIDING  RULE.  A rule  constructed  with  logarithmic  lines,  formed  upon  a slip  of  wood,  ivory  or 
brass,  inserted  in  a groove  in  another  rule,  so  that  by  means  of  another  scale  upon  the  rule  itself  tha 
»ontents  of  a surface  or  solid  may  be  known. 


G32 


SLOTTING  MACHINE. 


3337. 


SLOTTING  MACHINE,  Self-acting,  by  Caird  Co.,  Greenock.  The  following  figures  represent  a 
machine  adapted  for  slotting  or  paring  work  of  moderate  size,  and  for  cutting  the  key-grooves  or  seats 
of  wheels  not  exceeding  five  feet  in  diameter.  It  is  at  once  elegant  in  design,  simple  in  construction, 
and  capable  of  adaptation  to  a great  variety  of  circumstances. 

Fig.  3331  is  a front,  and  Fig.  3339  a side  elevation  of  the  machine,  showing  the  general  arrangement 
of  the  working  parts.  Fig.  3338  is  a general  plan,  and  Fig.  3340  a transverse  section  of  the  work-table 
and  part  of  the  framing  on  which  it  rests. 

The  framing  consists  of  a strong  fluted  column  A, 
ivith  two  brackets  of  proportionate  strength  for  carry- 
ing the  working  geer  and  slotting-bar,  and  a sole- 
frame  for  supporting  the  work-table  and  its  append- 
ages, and  having  a strong  bottom  plate  by  which  the 
machine  can  be  bolted  to  a stone  foundation.  The 
whole  of  this  framing  consists  of  a single  casting,  and 
therefore  may  be  presumed  to  possess  all  the  strength 
and  rigidity  which  can  possibly  be  obtained  with  the 
form  adopted  and  the  weight  of  metal  employed; 
two  conditions  of  the  utmost  importance  in  machines 
of  this  kind,  in  which  the  strain  varies  suddenly  from 
the  mere  weight  of  the  slotting-bar  to  the  maximum 
pressure  necessary  to  effect  the  cut. 

The  projecting  palms  of  the  brackets  are  faced  and 
formed  with  dovetail  edges,  between  which  the  slot- 
ting-bar B slides  in  its  up  and  down  motion.  Two  of 
these  dovetail  pieces  are  attached,  by  screws,  and  can 
be  adjusted  by  set-pins,  as  they  are  worn  by  the 
sliding  action  of  the  bar.  On  the  lower  extremity  of 
this  bar  the  slotting-tool  is  attached  by  two  glands 
and  set-screws,  in  the  usual  way ; and,  at  some  dis- 
tance from  jts  upper  end,  it  has  an  adjustable  stud 
fitted  into  it,  to  which  the  upper  end  of  the  connecting- 
rod  0 is  jointed.  The  mode  of  fixing  and  adjusting 
the  stud  is  clearly  shown  in  the  front  elevation  of  the 
machine.  From  this  view  it  will  be  observed  that  the 
bar  has  a long  slot,  occupying  about  a third  of  its 
length  at  the  upper  end,  between  the  parallel  cheeks 
of  which  the  rectangular  body-part  of  the  stud  is 
accurately  fitted.  This  part  of  the  stud  is  formed 
with  shoulders  which  bear  against  the  inside  of  the 
bar,  and  has  a strong  screwed  pin  projecting  from  it3 
exterior  surface,  on  wliich  a large  pinching-nut  is 
passed.  This  nut  being  screwed  tight  against  the  face 
of  the  bar,  the  stud  is  effectually  secured  from  shifting 
its  position  in  the  slot,  by  the  friction  induced  between 
the  bar  and  the  shoulders  of  the  stud  on  the  inside, 
and  the  nut  on  the  outside. 

The  rectangular  body  of  the  stud  is  traversed  by  a 
long  square-threaded  screw,  which  occupies  the  whole 
length  of  the  slot  in  the  bar,  and  which  can  be  worked 
by  the  small  hand-wheel  P,  fixed  on  its  upper  end. 

This  screw  is  so  fitted  into  the  machine  as  to  have  no 
end-long  motion  independent  of  the  bar;  but  when 
turned  by  means  of  the  wheel  P,  on  its  upper  extrem- 
ity, it  will  cause  the  stud  to  assume  any  required  posi- 
tion in  the  slot.  But  it  is  easy  to  perceive  that  by 
changing  the  position  of  the  stud  in  the  slot,  the  height 
of  the  slotting-bar  will  be  correspondingly  changed  in 
relation  to  the  work-table  of  the  machine.  In  effect 
the  stud  may  be  considered  as  a fixed  point  by  which 
the  bar  is  suspended,  and  consequently  by  turning  the 
hand-wheel  of  the  screw  in  one  direction  or  other,  the 
bar  will  be  correspondingly  elevated  or  depressed, 
and  the  tool  thereby  set  at  any  height  above  the 
table  that  may  be  necessary  for  the  kind  of  work 
ULder  operation.  And  when  it  is  so  adjusted,  the  stud 
is  made  fast  in  its  place  by  tightening  the  pinchiug- 
n it  on  the  screwed  tail  projecting  in  front  of  the  bar, 
as  above  described. 

The  lower  end  of  the  connecting-rod  O is  flexibly  attached  by  a stud-bolt  to  the  disk  or  crank-wheel 
N,  which  has  a radial  dovetail  groove  a formed  in  its  plane  face  to  receive  the  correspondingly  formed 
head  of  the  bolt.  This  bolt  or  stud  is  embraced  by  a strong  ferule  of  slightly  greater  length  than  the 
eye  of  the  connecting-rod,  which  fits  upon  it  freely ; and  being  in  its  place,  a large  nut  is  passed  upon 
the  projecting  end  of  the  bolt,  which  fixes  the  ferule  between  it  and  the  edges  of  the  groove  in  the  face 


3340. 


SLOTTING  MACHINE. 


633 


of  the  wheel,  and  thereby  effectually  secures  the  stud  in  the  required  position,  while  the  connecting-rou 
is  left  free  to  revolve  on  the  ferule,  in  consequence  of  the  latter  being  slightly  greater  in  length  than 
the  eye  of  the  rod.  The  position  of  the  stud  in  relation  to  the  centre  of  the  crank-wheel  obviously  de 
termines  the  length  of  the  stroke  of  the  slotting-bar.  Thus,  the  wheel  admits  of  the  stud  being  fixea 
at  seven  and  a half  inches  from  the  centre  as  a maximum,  and  therefore  the  utmost  throw  will  be  tjf 
teen  inches. 


formed  in  halves,  to  admit  of  their  being  adjusted,  as  they  wear,  by  cotters  acting  against  the  under 


034 


SLOTTING  MACHINE. 


brasses,  as  shown  in  the  side  elevation  of  the  machine.  On  the  opposite  end  of  the  crank-wheel  shaf1 
is  keyed  the  spur-wheel  G,  which  geers  with  the  pinion  H on  the  driving-shaft.  The  cone-pulley  K 
receives  motion  by  a strap  from  the  main  shaft,  and  is  susceptible  of  three  modifications  of  speed,  to 
suit  the  kind  of  work  under  operation,  the  fly-wheel  I rendering  the  motion  uniform,  and  obviating  the 
jerks  and  variations  to  which  it  would  otherwise  be  liable.  This  shaft  lias  one  of  its  bearings  in  the 
columnar  frame  of  the  machine,  while  the  other  is  independently  supported  by  a pillow  resting  on  the 
solo  of  a wall  recess. 

The  sliding-table  D is  movable  on  the  upper  surface  of  the  bed-plate  E,  in  a direction  parallel  to  tne 
sole-frame  of  the  machine ; and  the  circular  table  C is  capable  of  sliding  horizontally  on  this  last,  in  a 
direction  at  right  angles  to  the  direction  of  motion  of  the  table  D.  From  the  sectional  view,  Fig.  8340, 
it  will  be  observed  that  the  table  0 is  provided  with  a rectangular  sole-plate,  to  which  it  is  attached 
by  a central  stud  and  socket,  in  such  a manner  as  to  be  capable  of  working  freely  on  the  stud  as  on  an 
axis.  By  this  arrangement  two  motions  of  the  upper  table  are  obtained,  one  rectilineal  and  the  other 
circular.  The  rectilineal  motion  is  obtained  from  the  sole-plate,  on  which  are  bevelled  ledges,  adjusted 
to  slide  in  corresponding  faces  formed  on  the  table  D,  as  shown  in  Fig.  3388 ; and  the  circular  motion 
is  obtained  by  causing  the  upper  plate  to  revolve  on  its  centre.  The  first  of  these  motions  is  commu- 
nicated by  means  of  a screw  e , which  passes  through  a longitudinal  recess,  formed  for  its  reception  in 
the  table  D,  and  works  into  a nut  attached  to  the  sole-plate  of  ihe  upper  table.  To  obtain  the  circular 
motion,  the  table  C is  formed  with  a worm-wheel  on  its  circumference,  into  which  the  worm  on  the 
spindle  S geers ; and  as  this  spindle  is  attached  by  its  bearings  to  the  rectangular  sole-plate,  whici 
cannot  revolve  in  consequence  of  its  attachment  to  the  table  D,  it  is  obvious  that  by  turning  the  crank 
handle  on  the  worm-spindle,  the  plate  C will  be  made  to  revolve  on  its  central  stud. 

The  table  D can  also  be  worked  by  hand,  by  placing  a crank-handle  on  the  square  end  of  the  screw  h, 
the  self-acting  mechanism  to  be  described  presently  being  out  of  geer.  This  screw  has  its  bearings  in 
the  bed  plate  E,  and  works  in  a nut  attached  to  the  under  side  of  the  table.  It  may  also  be  observed 
that  one  of  the  dovetail  or  bevelled  ledges  of  each  of  the  sliding-tables  is  adjustable  by  set-screws  when 
reduced  by  wearing,  as  shown  in  the  section  of  the  table  D. 

A self-acting  motion  may  be  given  to  the  under  table  by  means  of  an  arrangement  of  parts  shown  in 
the  side  elevation  of  the  machine.  These  consist  of  the  ratchet-wheel  L,  which  is  keyed  upon  the  end 
of  a spindle  connected  by  a universal  joint  at  M,  with  the  screw  h ; and  a pawl  l,  attached  to  the  end  of 
the  lever  m , on  the  same  axis  and  formed  of  a piece  with  the  lever  n.  In  one  arm  of  the  wheel  G is 
fixed  a stud  o,  carrying  a small  friction  pulley,  and  adjustable,  like  the  stud  in  the  crank-wheel,  to  any 
required  distance  from  the  centre.  This  stud,  as  the  wheel  revolves,  comes  in  contact  with  the  lever  n, 
which,  being  loose  on  its  axis,  yields  to  the  pressure,  and  through  the  lower  arm  m , and  pawl  l,  trans- 
mits its  motion  to  the  ratchet-wheel,  and  through  this  again  to  the  screw  h.  The  pawl  l can  be  applied 
to  either  side  of  the  ratchet-wheel,  so  that  the  table  may  be  made  to  travel  upon  the  bed  E,  in  either 
direction,  and  as  the  throw  of  the  lever  n can  be  regulated  by  the  position  of  the  stud  o,  the  amount  of 
the  feed  motion  may  thus  be  adjusted  to  the  kind  of  work.  The  object  of  the  universal  joint  at  M is  to 
permit  the  table  to  be  set  at  a small  angle  with  the  horizontal  plane,  when  necessary,  as  in  cutting  the 
key-seats  of  wheels.  This  is  effected  by  raising  the  inner  end  of  the  table  by  means  of  the  screwed 
link  b,  jointed  to  the  bed-plate  E,  as  shown  in  Fig.  3340,  and  acted  upon  by  the  set-nuts  marked  2,  2, 
shown  in  the  side  elevation  of  the  machine.  The  bed-plate  of  the  table,  when  in  this  position,  is  sup- 
ported by  two  palms  fitted  to  a cylindrical  piece  formed  on  the  front  of  the  main  sole  ; and  is  prevented 
from  moving  laterally  by  the  set-screws  g g. 

The  circular  motion  of  the  table  0 may  be  communicated  by  the  handle  on  the  end  of  the  worm- 
spindle  S ; but,  to  render  it  self-acting,  a double  ratchet-wheel  is  substituted  for  the  handle,  and  is 
worked  by  pawls  attached  to  a rocking-lever,  which  communicates  by  a series  of  small  rods  with  the 
lever  in.  The  transverse  motion  of  the  upper  table  can  also  be  given  by  the  handle  on  the  end  of  the 
screw  e ; but  a ratchet  may  also  be  substituted  for  this  handle,  and  worked  by  a pawl  connected  with 
the  levers  employed  to  transmit  the  circular  motion  of  the  table.  Thus  each  and  all  of  the  three  mo- 
tions of  the  table  may  be  rendered  self-acting,  and  the  work  thereby  carried  on  independently  of  that 
constant  attention  which  would  otherwise  be  requisite  on  the  part  of  the  workman.  It  is  seldom,  how- 
ever, that  more  than  one  of  the  self-acting  motions  is  required  to  be  in  action  at  a time,  the  other  mo- 
tions being  adjusted  by  hand. 

Literal  References. 


A,  the  frame  of  the  machine. 

B,  the  slotting-bar. 

a,  dovetail  groove  in  the  crank-wheel  N. 

0,  the  circular  table  upon  which  the  work  is  fixed. 

D,  the  under  slide  of  the  table. 

E,  the  bed-plate  of  this  slide. 

b,  a fink  with  adjusting  nuts  for  setting  the  work- 
table at  an  angle. 

e,  guide-screw  of  the  upper  table, 
o g,  set-screws  for  preventing  lateral  motion  of  the 
table. 

h,  guide  screws  of  the  lower  table. 

G,  spur-wheel  on  the  crank-wheel  shaft,  geering 
with 

H,  a pinion  on  the  driving-shaft. 

1,  fly-wheel  on  the  driving-shaft. 


' K,  cone-pulley  for  driving  the  machine. 

j L,  a ratchet-wheel  by  which  motion  is  transmitted 
to  the  slide-screw  h. 

l,  a pawl  for  working  the  wheel  L. 

m,  lower  arm  of  the  lever  to  which  the  pawl  is  at- 
tached. 

n,  upper  arm  of  the  same  lever  receiving  motion 
from  the  stud  o. 

| M,  a universal  joint  by  which  the  spindle  of  the 
ratchet-wheel  L is  connected  to  the  screw  h. 

N,  the  crank-wheel  on  the  main  shaft. 

O,  the  connecting-rod  to  the  slotting-bar. 

i P,  hand-wheel  on  the  screw  for  adjusting  the  stroke 
of  the  machine. 

j S,  the  spindle  of  the  worm  geering  w.tb  the  worm- 

1 wheel  on  the  table  0 


SMUT  MACHINE. 


635 


SLUICE-COCKS,  Waller’s  Patent.  This  invention  consists  in  applying  movable  bushes  or  facings  to 
sluice-cocks,  and  in  constructing  the  bushes  in  such  a manner  that  they  shall  be  harder,  and  fit  more 
truly,  and  may  be  more  readily  applied  and  replaced  when  worn  ; it  further  consists  in  a mode  of  render- 
ing the  working  surfaces  of  sluice-cocks,  which  are  made  without  movable  bushes,  more  hard  and  durable 
Fig.  3341  is  a vertical  section  of  the  improved  sluice-cock ; Fig.  3342  also  represents  a vertical  sec 
tion,  taken  on  the  line  AB  of  Fig.  3341 ; and  Fig.  3343  is  a horizontal  section  taken  on  the  line  CD  oi 
Figs.  3341  and  3342.  a is  the  body  of  the  cock,  and  b b are  portions  of  two  pipes  which  enter  the 
sockets  of  the  cock,  and  are  retained  therein  water-tight  by  the  application  of  melted  lead,  in  the 
usual  manner.  The  body  of  the  cock  is  bored  out,  and  the  backs  of  the  bushes  cc  are  turned 
in  a lathe,  so  as  to  fit  the  recesses  thus  formed.  The  bushes  are  made,  by  preference,  of  cast-iron, 
(although  other  metal  may  be  used ;)  the  working  surfaces  are  chilled  in  the  act  of  casting,  and  art 
ground  or  “ faced  lip”  with  emery  in  a lathe.  The  bushes  are  coated  on  their  backs  with  marine  glue. 


or  similar  material,  previous  to  introducing  them  into  the  co< 't ; and  after  the  bushes  have  been  intro- 
duced into  the  cock,  they  are  moved  back  in  the  recesses  before  mentioned,  into  a proper  working  posi- 
tion by  forcing  down  the  plug  d into  its  place.  The  patentee  does  not  confine  himself  to  the  shape  oi 
the  recesses  formed  in  the  body  of  the  cock,  as  that  may  be  varied,  e is  a screw  for  raising  and  lower- 
ing the  plug;  / is  a screw-nut,  fitted  into  a recess  at  the  top  of  the  plug;  <j g are  ribs,  formed  on  the 
interior  of  the  upper  part  of  the  cock ; and  k h are  corresponding  ribs  on  the  outer  surface  of  the  upper 
part  of  the  plug  ; the  use  of  the  ribs  being  to  guide  the  plug  correctly  in  its  movement  up  and  down. 
The  surfaces  of  the  plug  are  chilled  in  the  act  of  casting,  and  are  then  ground  with  emery. 

When  making  sluice-cocks  without  movable  bushes,  the  patentee  causes  the  surface  against  which 
the  plug  works  to  be  chilled  in  the  act  of  casting  the  body  of  the  cock,  so  as  to  make  it  more  durable  , 
and  this  surface  is  afterwards  rendered  true  by  means  of  a revolving  tool  and  emery. 

The  patentee  claims,  Firstly,  the  mode  of  preparing  the  bodies  of  sluice-cocks  with  recesses  for 
receiving  bushes ; the  planes  of  the  surfaces  being  inclined  to  the  central  line  of  the  barrel  of  the 
cock  as  above  described.  Secondly — the  mode  of  applying  movable  bushes  to  cocks.  Thirdly — mak- 
ing the  movable  bushes,  and  also  the  plugs  of  sluice-cocks,  with  chilled  working  surfaces  as  described. 
Fourthly — the  making  of  sluice-cocks  with  chilled  surfaces,  which  form  the  bed  of  the  plug. 

SMUT  MACHINE.  F.  Harris  efe  Sons’  Patent  Smut  and  Scouring  Machine,  for  cleaning  aP  kinds 


cl  grain,  was,  we  understand,  originally  invented  for  hulling  and  pearling  rice  and  coffee,  as  also  foi 
Eiuutting  and  polishing  wheat  and  other  grain.  It  has  been  in  successful  operation  for  several  years 


636 


SOLDERING. 


past,  giving  entire  satisfaction  to  all  who  have  used  it,  and  acknowledged  to  be  superior  for  cleaning 
and  scouring  grain — being  capable  (when  set  the  right  distance  apart)  of  pearling  barley  and  wheat 
with  ease. 

This  machine  is  constructed  of  three  concave  and  convex  stones,  of  a very  porous  and  gutty  nature, 
dressed  similar  to  a mill-stone,  are  equally  as  durable,  with  a perforated  iron  case  around  the  running 
or  concavo-convex  stone,  (which  makes  400  revolutions  per  minute,)  all  set  into  a frame,  as  repre- 
sented in  Fig.  8344,  with  a perpendicular  blower  or  fan  attached  to  the  spindle,  capable  of  blowing 
every  thing  from  the  grain  without  a particle  of  waste. 

This  machine  is  capable  of  cleaning  from  10  to  80,000  bushels  of  grain  previous  to  being  dressed  or 
picked,  which  makes  it  do  the  work  as  well  as  when  first  put  in  operation.  The  stones  can  be  set  as 
necessity  requires,  closer  or  further  apart,  so  as  to  suit  all  kinds  of  grain,  and  are  well  adapted  for 
custom  mills. 

SOLDERING.  Soldering  is  the  process  of  uniting  the  edges  or  surfaces  of  similar  or  dissimilar  met- 
als and  alloys  by  partial  fusion.  In  general,  alloys  or  solders  of  various  and  greater  degrees  of  fusi- 
bility than  the  metals  to  be  joined,  are  placed  between  them,  and  the  solder  when  fused  unites  the  threa 
parts  into  a solid  mass ; less  frequently  the  surfaces  or  edges  are  simply  melted  together  with  an  addi- 
tional portion  of  the  same  metal. 

The  circumstances  to  be  considered  in  respect  to  soldering,  are,  for  the  most  part,  that  the  solders 
must  be  necessarily  somewhat  more  fusible  than  the  metals  to  be  united ; and  that  it  is  of  primary  im- 
portance that  the  metallic  oxides  and  any  foreign  matters  be  carefully  removed,  for  which  purpose  the 
edges  of  the  metals  are  made  chemically  clean,  or  quite  bright,  before  the  application  of  the  solders  and 
heat ; and  as  during  this  period  their  affinity  for  oxygen  is  violent,  they  are  covered  with  some  flux 
which  defends  them  from  the  air,  as  with  a varnish,  and  tends  to  reduce  any  portion  of  oxide  accident- 
ally existing. 

The  solders  are  broadly  distinguished  as  hard-solders  and  soft-solders ; the  former  only  fuse  at  the 
red  heat,  and  are  consequently  suitable  alone  to  metals  and  alloys  which  will  endure  that  temperature; 
the  soft-solders  melt  at  very  low  degrees  of  heat,  and  may  be  used  for  nearly  all  the  metals. 

The  attachment  is  in  every  case  the  stronger  the  more  nearly  the  metals  and  solders  respectively 
agree  in  hardness  and  malleability.  Thus,  if  two  pieces  of  brass  or  copper,  or  one  of  each,  are  brazed 
together,  or  united  with  spelter  solder,  an  alloy  nearly  as  tough  as  the  brass,  the  work  may  be  ham- 
mered, bent,  and  rolled,  almost  as  freely  as  the  same  metals  when  not  soldered,  because  of  the  nearly 
equal  cohesive  strength  of  the  three  parts. 

Lead,  tin,  or  pewter,  united  with  soft-solder,  are  also  malleable  from  the  near  agreement  of  these  sub- 
stances ; whereas  when  copper,  brdss,  and  iron  are  soft-soldered,  a blow  of  the  hammer  or  any  accidental 
violence,  is  almost  certain  to  break  the  joint  asunder,  so  long  as  the  joint  is  weaker  than  the  metal  gen- 
erally ; and  therefore  the  joint  is  only  safe  when  the  surrounding  metal  from  its  thinness  is  no  stronger 
than  the  solder,  so  that  the  two  may  yield  in  common  to  any  disturbing  cause. 

When  the  spaces  between  the  works  to  be  joined  are  wide  and  coarse,  the  fluid  solder  will  probably 
fall  out,  simply  from  the  effect  of  gravity ; but  when  the  crevices  are  fine  and  close,  the  solder  will  be 
as  it  were  sucked  up  by  capillary  attraction.  All  soldered  works  should  be  kept  under  motionless  re- 
straint for  a period,  as  any  movement  of  the  parts  during  the  transition  of  the  solder  from  the  fluid  tc 
the  solid  state,  disturbs  its  crystallization  and  the  strict  unity  of  the  several  parts. 

In  hard-soldering  it  is  frequently  necessary  to  bind  the  works  together  in  their  respective  positions ; 
this  is  done  with  soft  iron  binding  wire,  which  for  delicate  jewelry  work  is  exceedingly  fine,  and  for 
stronger  works  is  the  twentieth  or  thirtieth  of  an  inch  in  diameter ; it  is  passed  round  the  work  in  loops, 
the  ends  of  which  are  twisted  together  with  the  pliers.  The  Asiatics  seldom  use  binding  wire. 

In  soft-soldering  the  binding  wire  is  scarcely  ever  used,  as  from  the  moderate  and  local  application 
of  the  heat,  the  hands  may  in  general  be  freely  used  in  retaining  most  thin  works  in  position  during  the 
process.  Thick  works  are  handled  with  pliers  or  tongs  whilst  being  soft-soldered,  and  they  are  often 
treated  much  like  glue  joints,  if  wre  conceive  the  wood  to  be  replaced  by  metal,  and  the  glue  by  solder, 
as  the  two  surfaces  are  frequently  coated  or  tinned  whilst  separated,  and  then  rubbed  together  to  dis- 
tribute and  exclude  the  greater  part  of  the  solder. 

The  succeeding  “ Tabular  View  of  the  Processes  of  Soldering”  may  be  considered  as  the  index  to  the 
entire  subject;  which  refers  to  the  ordinary  methods  of  soldering  most  metals.  The  article  is  arranged 
under  three  divisions,  illustrated  in  distinct  sections,  preceded  by  one  section  on  the  modes  of  applying 
heat 

Tabulae  view  of  the  processes  of  soldephng. — To  avoid  continual  repetition,  references  are  made  tc 
the  lists  on  the  succeeding  page,  in  -which  some  of  the  solders,  fluxes,  and  modes  of  applying  heat  are 
enumerated. 

Hard  soldering. — Applicable  to  nearly  all  metals  less  fusible  than  the  solders ; the  modes  of  treat- 
ment nearly  similar  throughout. 

The  hard-solders  most  commonly  used  are  the  spelter  solders  and  silver  solders.  The  general  flux  is 
borax  marked  A,  on  next  page ; and  the  modes  of  heating  are  the  naked  fire,  the  furnace  or  muffle,  and 
the  blowpipe,  marked  a,  b , g. 

Note. — The  examples  commence  with  the  solders,  (the  least  fusible  first,)  followed  by  the  metals  for 
which  they  are  commonly  employed. 

Fine  gold,  laminated  and  cut  into  shreds,  is  used  as  the  solder  for  joining  chemical  vessels  made  ol 
platinum. 

Silver  is  by  many  considered  as  much  the  best  solder  for  German  silver. 

Copper  in  shreds  is  sometimes  similarly  used  for  iron. 

Gold  solders  laminated  are  used  for  gold  alloys. 

Spelter  solders,  granulated  whilst  hot,  are  used  for  iron,  copper,  brass,  gun-metal,  German  silver,  (fee, 

Silver  solders  laminated  are  employed  for  all  silver  works  and  for  common  gold  work,  also  for  Ger- 


SOLDERING. 


637 


man  silver,  gilding  metal,  iron,  steel,  brass,  gun-metal,  Ac.,  -when  greater  neatness  is  required  than  is  ob- 
tained with  spelter  solder. 

White  or  button  solders  granulated  are  employed  for  the  white  alloys  called  button  metals ; they 
were  introduced  as  cheap  substitutes  for  silver  solder. 

Soft-soldering. — Applicable  to  nearly  all  the  metals  ; the  modes  of  treatment  very  different. 

The  soft-solder  mostly  used  is  2 parts  tin  and  1 part  lead ; sometimes  from  motives  of  economy  much 
more  lead  is  employed,  and  1-J  tin  to  1 lead  is  the  most  fusible  of  the  group  unless  bismuth  is  used, 
The  fkixes  B to  G-,  and  the  modes  of  heating,  a to  i,  are  all  used  with  the  soft-solders. 

Note. — The  examples  commence  with  the  metals  to  be  soldered.  Thus  in  the  list,  zinc,  8,  C,  f im- 
plies that  zinc  is  soldered  with  No.  8 alloy,  by  the  aid  of  the  muriate  or  chloride  of  zinc  and  the  copper 
bit.  Lead,  4 to  8,  F,  d,  e,  implies  that  lead  is  soldered  with  alloys  varying  from  No.  4 to  8,  and  that 
it  is  fluxed  with  tallow,  the  heat  being  applied  by  pouring  on  melted  solder,  and  the  subsequent  use  of 
the  heated  iron  not  tinned ; but  in  general  one  only  of  the  modes  of  heating  is  selected,  according  to  cir- 
cumstances. 

Iron,  cast-iron,  and  steel,  8,  B,  D,  if  thick,  heated  by  a,  b,  or  c,  and  also  by  g. 

Tinned  iron,  8,  C,  D ,/. 

Silver  and  gold  are  soldered  with  pure  tin  or  else  with  8,  E,  a,  g,  or  li. 

Copper  and  many  of  its  alloys,  namely,  brass,  gilding  metal,  gun-metal,  Ac.,  8,  B,  C,  D ; when  thick, 
heated  by  a,  b , c,  e,  or  g,  and  when  thin  by  f or  g. 

Speculum  metal,  8,  B,  C,  D,  the  heat  should  be  most  cautiously  applied ; the  sand-bath  is  perhaps  the 
best  mode. 

Sine,  8 0,/ 

Lead  and  lead  pipes,  or  ordinary  plumbers’  work,  4 to  8,  F,  d,  or  c. 

Lead  and  tin  pipes,  8 D and  G mixed,  g,  and  also/. 

Britannia  metal,  8,  C,  D,  g. 

Pewters : the  solders  must  vary  in  fusibility  according  to  the  fusibility  of  the  metal,  generally  G and 
i are  used,  sometimes  also  G and  g,  or  / 

Tinning  the  metals,  and  washing  them  with  lead,  zinc,  <fcc. 

Soldering  per  se,  or  burning  together. — Applicable  to  some  few  of  the  metals  only,  and  which  in  gen- 
eral require  no  flux. 

Iron,  brass,  Ac.,  are  sometimes  burned,  or  united  by  partial  fusion,  by  pouring  very  hot  metal  over 
or  around  them,  d. 

Lead  is  united  without  solder,  by  pouring  on  red-hot  lead,  and  employing  a red-hot  iron,  d,  e,  and 
also  by  the  autogenous  process. 


Alloys  and  their  Melting  Heats*  Fluxes. 


).  1. 

1 Tin, 

25  Lead  

558  Fahr. 

A.  Borax. 

2. 

1 “ 

10  “ 

....  541  “ 

B.  Sal-ammoniac,  or  muriate  of  ammonia. 

8. 

1 “ 

5 “ 

....  511  “ 

C.  Muriate,  or  chloride  of  zinc. 

4. 

1 “ 

3 “ 

....  482  “ 

D.  Common  resin. 

5. 

1 “ 

2 “ 

....  441  “ 

E.  Venice  Turpentine. 

6. 

1 “ 

i “ 

F.  Tallow. 

7. 

14  “ 

i “ 

....  334  “ 

G.  Gallipoli  oil,  a common  sweet  oil. 

8. 

2 “ 

i “ 

....  340  “ 

9. 

3 “ 

i “ 

....  356  “ 

Modes  of  Applying  Heat. 

10. 

4 “ 

i “ 

....  365  “ 

a.  Naked  fire. 

11. 

5 “ 

i “ 

....  378  “ 

b.  Hollow  furnace  or  muffle. 

12. 

6 “ 

i “ 

....  381  “ 

c.  Immersion  in  melted  solder. 

13. 

4 Lead,  4 Tin,  1 Bismuth  .... 

....  320  “ 

d.  Melted  solder  or  metal  poured  on. 

14. 

3 “ 

3 “ 1 

....  310  “ 

c.  Heated  iron  not  tinned. 

15. 

2 “ 

2 “ 1 

....  292  “ 

/.  Heated  copper  tool,  tinned. 

16. 

i “ 

1 “ 1 

....  254  “ 

g.  Blowpipe  flame. 

17. 

2 “ 

1 “ 2 “ 

....  236  « 

h.  Flame  alone,  generally  alcohol. 

18. 

3 “ 

5 “ 3 

....  202  “ 

i.  Stream  of  heated  air. 

The  modes  of  applying  heat  in  soldering. — The  modes  of  heating  works  for  soldering  are  extremelv 
varied,  and  depend  jointly  upon  the  magnitude  of  the  objects,  the  general  or  local  manner  in  which  they 
are  to  be  soldered,  and  the  fusibility  of  the  solders.  It  appears  to  be  now  desirable  to  advert  to  sue! 
of  the  modes  of  applying  heat  enumerated  in  the  tabular  view,  as  are  of  more  general  application,  leav- 
ing the  modes  specifically  employed  in  heating  works  to  their  respective  sections. 

In  hard-soldered  works,  the  fires  bear  a general  resemblance  to  those  employed  in  forging  iron  ana 
steel ; in  fact,  the  blacksmith’s  forge  is  frequently  used  for  brazing,  although  the  process  is  injurious  to 
the  fuel  as  regards  its  ordinary  use.  Coppersmiths,  silversmiths,  and  others,  use  a similar  hearth,  but 
which  stands  further  away  from  the  upright  wall,  so  as  to  allow  of  the  central  parts  of  large  objects 
being  soldered ; the  bellows  are  always  worked  by  the  foot,  either  by  a treadle,  or  more  commonly  by 
a chain  from  the  rocking-staff  terminating  in  a stirrup. 

The  brazier’s  hearth  for  large  and  long  works,  is  a flat  plate  of  iron,  about  four  feet  by  three,  which 
stands  in  the  middle  of  the  shop  upon  four  legs : the  surface  of  the  plate  serves  for  the  support  of  long 
tubes  and  works  over  the  central  aperture  in  the  plate  which  contains  the  fuel,  and  measures  about 


* By  the  addition  of  3 parts  of  mercury  to  No.  18  it  melts  at  122°  F.,  and  may  be  used  for  anatomical  injections  and  fee 
Hopping  teeth. 


SOLDERING. 


bi  8 


twc  feet  by  one,  and  five  or  six  inches  deep.  The  revolving  fan  is  commonly  used  for  the  blast,  and 
the  tuyere  irons,  which  have  larger  apertures  than  usual,  are  fitted  loosely  into  grooves  at  the  ends,  to 
admit  of  easy  renewal,  as  they  are  destroyed  rather  quickly.  The  fire  is  sometimes  used  of  the  full 
length  of  the  hearth,  but  is  more  generally  contracted  by  a loose  iron  plate ; occasionally  two  separate 
fires  are  made,  or  the  two  blast-pipes  are  used  upon  one.  The  hood  is  suspended  from  the  ceiling,  with 
counterpoise  weights,  so  as  to  be  raised  or  depressed  according  to  the  magnitude  of  the  works  ; and  it 
has  large  sliding  tubes  for  conducting  the  smoke  to  the  chimney. 

Furnaces  are  occasionally  used  in  soldering,  or  the  common  fire  is  temporarily  converted  into  the  con- 
dition of  a furnace  from  being  built  hollow,  or  by  the  insertion  of  iron  tubes  or  muffles  amidst  the  ignited 
fuel,  as  already  explained  in  reference  to  forging  and  hardening.  For  want  of  any  of  these  means,  the 
amateur  may  use  the  ordinary  grate,  or  it  is  better  to  employ  a brazier  or  chafing-dish  containing  char- 
coal, and  urged  with  hand-bellows  blown  by  an  assistant,  as  then  both  hands  are  at  liberty  to  manage 
the  work  and  fuel. 

Fresh  coals  are  highly  improper  for  soldering  on  account  of  the  sulphur  they  always  contain ; the 
best  fuel  is  charcoal,  but  in  general  coke  or  cinders  are  used.  Lead  is  equally  as  prejudicial  to  the  fire 
in  soldering  as  it  is  in  welding  iron  and  steel,  or  in  forging  gold,  silver,  or  copper ; as  the  lead  readily 
oxidizes  and  attaches  itself  to  the  metals  that  are  being  soldered  or  welded,  preventing  the  union  of  the 
parts,  and  in  almost  all  cases  rendering  the  metals  brittle  and  unserviceable. 

There  are  many  purposes  in  the  arts  which  require  the  application  of  heat  having  the  intensity  of 
the  forge-fire  or  of  the  furnace,  but  with  the  po-wer  of  observation,  guidance,  and  definition  of  the  artist’s 
pencil.  These  conditions  are  most  efficiently  obtained  by  the  blowpipe,  an  instrument  by  which  a stream 
of  air  is  driven  forcibly  through  a flame,  so  as  to  direct  it  either  as  a well-defined  cone,  or  as  a broad 
jet  of  flame,  against  the  object  to  be  heated,  which  is  in  many  cases  supported  upon  charcoal,  by  way 
of  concentrating  the  heat. 

The  blowpipe  is  largely  used — namely,  in  soldering,  in  hardening  and  tempering  small  tools,  in  glass- 
blowing  for  philosophical  instruments  and  toys,  in  glass-pinching  with  metal  moulds  made  like  pliers, 
in  enamelling,  and  by  the  chemist  and  mineralogist,  as  an  important  means  of  analysis  : the  instrument 
has  consequently  received  very  great  attention  both  from  artisans  and  distinguished  philosophers. 

Most  of  the  blowpipes  are  supplied  with  common  air,  and  generally  by  the  respiratory  organs  of  the 
operator  ; sometimes  by  bellows  moved  with  the  foot,  by  vessels  in  which  the  air  is  condensed  by  a 
syringe,  or  by  pneumatic  apparatus  with  water  pressure.  In  some  few  cases  oxygen  or  hydrogen,  or  the 
same  gases  when  mixed,  are  employed  ; they  are  little  used  in  the  arts. 

The  ordinary  blowpipe  is  a light  conical  brass  tube,  about  10  or  12  inches  long,  from  one-half  to  one- 
fourth  of  an  inch  diameter  at  the  end  for  the  mouth,  and  from  one-sixteenth  to  one-fiftieth  at  the  aper- 
ture or  jet ; the  end  is  bent  as  a quadrant,  that  the  flame  may  be  immediately  under  observation. 

The  lungs  may  be  used  for  the  blowpipe  with  much  more  effect  than  might  be  expected,  and  with  a 
little  practice  a constant  stream  may  be  maintained  for  many  minutes  if  the  cheeks  are  kept  fully  dis- 
tended with  wind,  so  that  their  elasticity  alone  shall  serve  to  impel  a part  of  the  air,  whilst  the  ordinary 
breathing  is  carried  on  through  the  nostrils  for  a fresh  supply. 

The.  most  intense  heat  of  the  common  blowpipe  is  that  of  the  pointed  flame ; with  a thick  wax  can 
die,  and  a blowpipe  with  a small  aperture  placed  slightly  within  the  flame,  the  mineralogist  succeeds 
in  melting  small  fragments  of  all  the  metals,  when  they  are  supported  upon  charcoal  and  exposed  to 
the  extreme  point  of  the  inner  or  blue  cone,  which  is  the  hottest  part  of  the  flame  ; that  is,  fragments  of 
all  metals  which  do  not  require  the  oxyhydrogen  blowpipe. 

Larger  particles,  requiring  less  heat,  are  brought  somewhat  nearer  to  the  candle,  so  as  to  receive  a 
greater  portion  of  the  flame ; and  when  a very  mild  degree  of  heat  is  needed,  the  object  is  removed  fur- 
ther away,  sometimes  as  in  melting  the  fluxes  preparatory  to  soldering,  even  to  the  stream  of  hot  air 
beyond  the  point  of  the  external  yellowish  flame. 

The  first,  or  the  silent  pointed  flame,  is  used  by  the  chemist  and  mineralogist  for  reducing  the  metal- 
lic oxides  to  the  metallic  state,  and  is  called  the  deoxidizing  flame ; the  second,  or  the  noisy,  brush-like 
flame,  is  less  intense,  and  is  called  the  oxidizing  flame. 

The  artisan  employs  in  soldering  a much  larger  flame  than  the  chemist,  namely,  that  of  a lamp  the 
wick  of  which  is  from  a quarter  to  one  inch  diameter:  this  must  be  plentifully  supplied  with  oil ; the 
blowpipe  in  such  cases  is  selected  with  a larger  aperture,  it  is  blown  vigorously,  and  held  a little  distant 
from  the  flame,  so  as  to  spread  it  in  a broad  stream  of  light,  extending  over  a large  surface  of  the  work, 
which  is  in  most  cases  supported  upon  charcoal.  When  any  minute  portion  alone  is  to  be  heated,  the 
pointed  flame  is  used,  with  a milder  blast  of  air  and  a decreased  distance. 

The  following  method  is  much  employed  by  the  cheap  jewelry  manufacturers  at  Birmingham.  A 
6tream  of  air  from  a pair  of  bellows  directs  a gas  flame  through  a trough  or  shoot,  the  third  of  a cylin- 
drical tube  placed  at  a small  angle  below  the  flame.  Instead  of  a charcoal  support  they  employ  a 
wooden  handle,  upon  which  is  fixed  a flat  disk  of  sheet-iron,  about  three  or  four  inches  diameter,  covered 
witli  a matting  of  waste  fragments  of  binding  wire,  entangled  together  and  beaten  into  a sheet  about 
throe-eighths  or  half  an  inch  thick ; some  few  of  the  larger  pieces  of  wire  extend  round  the  edge  of  the 
disk  to  attach  the  remainder.  The  work  to  be  soldered  is  placed  upon  the  wire,  which  becomes  par- 
tially red-hot  from  the  flame,  and  retains  the  heat  somewhat  as  the  charcoal,  but  without  the  inconve- 
nience of  burning  away,  so  that  the  broad  level  surface  is  always  maintained.  Small  cinders  are  fre- 
quently-placed,  upon  the  tool,  either  instead  of,  or  upon  the  wire. 

Sometimes  the  gas-pipe  is  surmounted  by  a square  hood,  open  at  both  ends,  and  two  blast-pipes  are 
directed  through  it ; the  latter  arrangement  is  used  by  the  makers  of  glass  toys  and  seals ; these  are 
pinched  in  moulds  something  like  bullet-moulds ; the  devices  on  the  seals  are  produced  by  inserting  in 
the  moulds  dried  casts,  made  in  plaster  of  Paris. 

Makeis  of  thermometers  and  other  philosophical  instruments  generally  use  a table  blowpipe,  with  a 
thallow  oval,  or  rather  a kidney-shaped  lamp,  with  a loop  placed  lengthways  upon  the  short  diametei 


SOLDERING. 


689 


• : 

for  holding  the  cotton,  -which  is  sometimes  an  inch  long  and  half  an  inch  wide.  The  wick  is  plentifully 
supplied  with  tallow  or  hog’s  lard,  and  a furrow  is  made  through  it  with  a wire  to  afford  a free  passage 
for  the  blast  from  the  fixed  nozzle,  by  the  size  of  which,  and  its  distance  from  the  flame,  the  latter  is 
made  to  assume  the  pointed  or  brush-like  character.  This  lamp  is  more  cleanly,  and  emits  less  smell 
than  those  supplied  with  oil ; any  overflow  of  the  tallow  is  caught  in  the  outer  vessel  or  tray,  and  when 
cold,  the  fat  solidifies. 

Many  blowpipes  have  been  invented  for  the  employment  of  oxygen  and  hydrogen ; the  mixed  gases 
were  first  used  by  Dr.  Hare,  of  Philadelphia,  who  has  been  followed  in  various  ways  by  Clark,  Gurney, 
CummiDg,  Hemming,  Marcet,  Leeson,  and  many  others.  Two  subsequent  modifications  of  gas  blow- 
pipes which  have  been  invented  for  the  workshop  will  alone  be  here  described,  namely,  Sir  John  Rob- 
ison’s Workshop  Blowpipe,  intended  for  soldering,  hardening,  and  other  purposes;  and  the  Count  de 
Richemont’s  Airo-hydrogen  Blowpipe. 

The  general  form  of  the  “ workshop  blowpipe”  is  that  of  a tube  open  at  the  one  end,  and  supported 
on  trunnions  in  a wooden  pedestal,  so  that  it  may  be  pointed  vertically,  horizontally,  or  at  any  angle  as 
desired.  Common  street  gas  is  supplied  through  the  one  hollow  trunnion,  and  it  escapes  through  an 
annular  opening ; whilst  oxygen  gas,  or  more  usually  common  air,  is  admitted  through  the  other  trun- 
nion which  is  also  hollow,  and  is  discharged  in  the  centre  of  the  hydrogen  through  a central  conical  tube  ; 
the  magnitude  and  intensity  of  the  flame  being  determined  by  the  relative  quantities  of  gas  and  air,  and 
by  the  greater  or  less  protrusion  of  the  inner  cone,  by  which  the  annular  space  for  the  hydrogen  is  con- 
tracted in  any  required  degree. 

Prom  amongst  numerous  other  small  applications  of  heat,  Mr.  Gill’s  portable  blowpipe  furnace  may 
be  noticed ; it  consists  of  a lump  of  pumice-stone  three  or  four  inches  diameter,  scooped  out  like  a pan 
or  crucible,  and  filled  with  small  fragments  of  charcoal ; sometimes  a conical  perforated  cover  is  added  ; 
the  inside  may  be  intensely  ignited,  whilst  the  slow  conducting  power  of  the  pumice-stone  guards  the 
hand  from  inconvenient  heat. 

Examples  of  hard-soldering. — It  was  mentioned  in  the  tabular  view  that  the  several  works  united 
with  hard-solders  receive  nearly  the’  saine  treatment ; a few  examples  will  therefore  serve  to  convey  a 
general  idea  of  hard-soldering — a process  commonly  attended  with  some  risk  of  partially  melting  the 
works,  because  the  fusing  points  of  the  metals  and  their  respective  solders  often  approach  very  nearly 
together. 

Several  of  the  hard-solders  contain  zinc,  which  appears  to  be  useful  in  different  ways : first,  it  in- 
creases their  fusibility ; in  cases  where  the  solder  cannot  be  seen  it  serves  as  an  index  to  denote  the 
completion  of  the  process,  for  when  the  solder  is  melted  the  zinc  volatilizes,  and  burns  with  the  well- 
known  blue  flame ; and  as  at  this  moment  some  of  the  zinc  is  consumed,  the  alloy  left  behind  becomes 
tougher,  and  more  nearly  approaches  to  the  condition  of  the  metal  which  it  is  desired  to  unite.  The 
zinc  may  be  therefore  considered  to  act  as  a flux,  and  so  likewise  does  the  arsenic  occasionally  intro- 
duced into  the  gold  and  silver  solders,  as  the  arsenic  is  for  the  most  part  lost  between  the  processes  of 
making  and  using  the  solders ; but  this  metal  being  of  a noxious  quality,  it  is  but  little  resorted  to,  and 
besides,  it  renders  the  other  metals  very  brittle. 

In  every  case  of  soldering,  a general  regard  to  cleanliness  in  the  manipulation  is  important,  and  for 
the  most  part  the  edges  of  the  metals  are  filed  or  scraped  prior  to  their  being  soldered,  as  before  ob- 
served; in  those  cases  in  which  the  red-heat  is  employed,  filing  or  scraping  are  less  imperative,  as  any 
greasy  or  combustible  matters  are  burned  away,  and  the  borax  has  the  property  of  combining  with 
nearly  all  the  metallic  oxides  and  earthy  bases,  thereby  cleansing  the  edges  of  the  metals,  should  that 
proceeding  have  been  previously  omitted. 

The  works  in  copper,  iron,  brass,  &c.,  having  been  prepared  for  brazing,  (or  soldering  with  a fusible 
brass,)  and  the  joints  secured  in  position  by  binding  wire  where  needful,  the  granulated  spelter  and 
pounded  borax  are  mixed  in  a cup  with  a very  little  water,  and  spread  along  the  joint  by  a slip  of  sheet- 
metal  or  a small  spoon. 

The  work,  if  sufficiently  large,  is  now  placed  above  the  clear  fire,  first  at  a small  distance  so  as  grad- 
ually to  evaporate  the  moisture,  and  likewise  to  drive  off  the  water  of  crystallization  of  the  borax;  dur- 
ing this  process  the  latter  boils  up  with  the  appearance  of  froth  or  snow,  and  if  hastily  heated  it  some- 
times displaces  the  solder.  The  heat  is  now  increased,  and  when  the  metal  becomes  faintly  red,  the 
borax  fuses  quietly  like  glass ; shortly  after,  that  is  at  a bright  red,  the  solder  also  fuses,  the  indication 
of  which  is  a small  blue  flame  from  the  ignition  of  the  zinc.  Just  at  this  time  some  works  are  tapped 
slightly  with  the  poker  to  put  the  whole  in  vibration,  and  cause  the  solder  to  run  through  the  joint  to 
the  lower  surface,  but  generally  the  solder  flushes,  or  is  absorbed  in  the  joint,  and  nearly  disappears 
without  the  necessity  for  tapping  the  work. 

It  is  of  course  necessary  to  apply  the  heat  as  uniformly  as  possible  by  moving  the  work  about  so  as 
to  avoid  melting  the  object  as  well  as  the  solder;  the  work  is  withdrawn  from  the  fire  as  soon  as  the 
solder  has  flushed,  and  when  the  latter  is  set,  the  work  may  be  cooled  in  water  without  mischief. 

Tubes  are  generally  secured  by  loops  of  binding  wire  twisted  together  with  the  pliers ; and  those  sol- 
dered upon  the  open  fire  are  almost  always  soldered  from  within,  as  otherwise  the  heat  would  have  to 
be  transmitted  across  the  tube  with  greater  risk  of  melting  the  work,  air  being  a bad  conductor  of  heat ; 
it  is  necessary  to  look  through  the  tube  to  watch  for  the  melting  of  the  solder.  Long  tubes  are  rested 
upon  the  flat  plate  of  the  brazier’s  hearth,  and  portions  equal  to  the  extent  of  the  fire  are  soldered  in 
succession.  The  common  Birmingham  tubes  for  gas-works,  bedsteads,  and  numerous  other  purposes, 
are  soldered  from  the  outside ; but  this  is  done  in  short  furnaces  open  at  both  ends  and  level  with  the 
floor,  by  which  the  heat  is  applied  more  uniformly  around  the  tubes. 

Works  in  iron  require  much  less  precaution  in  point  of  the  heat,  as  there  is  little  or  no  risk  of  fusion ; 
thus  in  soldering  the  spiral  wires  to  form  the  internal  screw  within  the  boxes  of  ordinary  tail-vices,  the 
work  is  coated  with  loam,  and  strips  of  sheet-brass  are  used  as  solder ; the  fire  is  urged  until  the.  blue 
flame  appears  at  the  end  of  the  tube  when  the  fusion  is  complete : the  work  is  withdrawn  from  the  fire 


040 


SOLDERING-. 


5: 

and  rolled  backwards  and  forwards  on  the  ground  to  distribute  the  solder  equally  at  every  part.  Other 
common  works  in  iron,  such  as  locks,  are  in  like  manner  covered  with  loam  to  prevent  the  iron  from 
scaling  off.  Sheet-iron  may  be  soldered  by  filings  of  soft  cast-iron,  applied  in  the  usual  way  of  solder- 
ing with  borax,  which  has  been  gradually  dried  in  a crucible  and  powdered,  and  a solution  of  sal-am- 
moniac.” 

The  finer  works  in  iron  and  steel,  those  in  the  light-colored  metals  generally,  and  also  the  works  in 
brass  which  are  required  to  be  very  neatly  done,  are  soldered  with  silver-solder.  From  the  superior 
fusibility  of  silver -solder,  and  from  its  combining  so  well  with  the  different  metals  without  “gnawing 
them  or  eating  them  away"  or  wasting  part  of  the  edges  of  the  joints,  silver-solder  is  very  desirable  for 
a great  many  cases ; and  from  the  more  careful  and  sparing  manner  in  which  it  is  used,  many  objects 
require  but  little  or  no  finishing  subsequently  to  the  soldering,  so  that  the  more  expensive  solder  is  not 
only  better,  but  likewise  in  reality  more  economical. 

The  practice  of  silver-soldering  is  essentially  the  same  as  brazing.  The  joint  is  first  moistened  with 
borax  and  water ; the  solder,  (which  is  generally  laminated  and  cut  into  little  squares  with  the  shears,) 
is  then  placed  on  the  joint  with  forceps.  In  heating  the  work  additional  care  is  given  not  to  displace 
the  solder;  and  for  which  reason  some  persons  boil  the  borax,  or  drive  off  its  water  of  crystallization  at 
the  red-heat,  then  pulverize  it  and  apply  it  in  the  dry  state  along  with  the  solder ; others  fuse  the  borax 
upon  the  joint  before  putting  on  the  solder. 

Numerous  small  works  united  with  hard-solders,  such  as  mathematical  and  drawing  instruments,  but- 
tons, and  jewelry,  are  soldered  with  the  blowpipe  ; in  almost  all  cases  the  work  is  supported  upon  char- 
coal, and  sometimes  for  the  greater  concentration  of  the  heat  it  is  also  covered  with  charcoal.  The 
management  of  the  blowpipe  having  been  explained,  it  is  only  necessary  to  add  that  the  magnitude  and 
shape  of  the  flame  are  proportioned  to  those  of  the  works. 

In  soldering  gold  and  silver  the  borax  is  rubbed  with  water  upon  a slate  to  the  consistence  of  cream, 
and  is  laid  upon  the  work  with  a camel's  hair  pencil,  and  the  solders  although  generally  laminated  are 
also  drawn  into  wire  or  filed  into  dust ; but  it  will  be  remembered,  the  more  minute  the  particles  of 
the  granulated  metals  the  greater  is  the  degree  of  heat  required  in  fusing  them. 

In  many  of  the  jewelry  works  the  solder  is  so  delicately  applied,  that  it  is  not  necessary  to  file  or 
scrape  off  any  portion,  none  being  in  excess,  and  the  borax  is  removed  by  immersing  the  works  in  the 
various  pickling  and  coloring  preparations. 

Examples  of  soft-soldering. — In  this  section  the  employment  of  the  less  fusible  of  the  soft-solders  will 
be  first  noticed ; the  plumbers’  sealed-solder,  2 parts  lead  and  1 of  tin,  melts  at  about  440°  F. ; the 
usual  or  fine  tin-solder,  2 parts  tin  and  1 of  lead,  melts  at  340°  ; and  the  bismuth-solders  at  from  250° 
to  270°  : the  modes  of  applying  the  heat  consequently  differ  very  much,  as  will  be  shown. 

The  soft-solders  are  prepared  in  different  forms  suited  to  the  nature  of  the  various  works.  No.  5,  p. 
590,  the  plumber’s-solder,  is  cast  in  iron  moulds  into  triangular  ingots  measuring  from  1 to  6 superficial 
inches  in  the  section.  No.  8,  the  fine  tin-solder,  is  cast  in  cakes  about  4 by  6 inches,  and  \ to  J inch 
thick ; and  this  and  the  more  fusible  kinds  are  trailed  from  the  ladle  upon  an  iron  plate  or  flat  stone,  to 
make  slight  bars,  ribbons,  and  even  threads,  that  the  magnitude  of  the  solder  may  be  always  propor- 
tioned to  the  magnitude  and  circumstances  of  the  work. 

It  is  very  essential  that  all  soft-soldered  joints  should  be  particularly  clean  and  free  from  metallic 
oxides ; and  except  where  oil  is  exclusively  used  as  the  flux,  greasy  matters  should  be  avoided,  as  they 
prevent  the  ready  attachment  of  the  aqueous  fluxes.  It  is  therefore  usual  with  all  the  metals,  except 
clean  tinned  plate,  and  clean  tin  alloys,  to  scrape  the  edges  immediately  before  the  process,  so  far  as 
the  solder  is  desired  to  adhere. 

Lead  works  are  first  smeared  or  soiled  around  the  intended  joints  with  a mixture  of  size  and  lamp- 
black, called  soil,  to  prevent  the  adhesion  of  the  melted  solder ; next  the  parts  intended  to  receive  the 
solder  are  shaved  quite  clean  with  the  shave-hook,  (a  triangular  disk  of  steel  riveted  on  a wire  stem,) 
and  the  clean  metal  is  then  rubbed  over  with  tallow.  Some  joints  are  wiped,  without  the  employment 
of  the  soldering-irou ; that  is,  the  solder  is  heated  rather  beyond  its  melting  point,  and  poured  somewhat 
plentifully  upon  the  joint  to  heat  it ; the  solder  is  then  smoothed  with  the  cloth,  or  several  folds  of  thick 
bed-tick  well  greased,  with  which  the  superfluous  solder  is  finally  removed. 

Other  lead  joints  are  striped,  or  left  in  ridges,  from  the  bulbous  end  of  the  plumber’s  crooked  solder- 
ing-iron, which  is  heated  nearly  to  redness,  and  not  tinned ; the  iron  and  cloth  are  jointly  used  at  the 
commencement  for  moulding  the  solder  and  heating  the  joint.  In  this  case  less  solder  is  poured  on,  and 
a smaller  quantity  remains  upon  the  work;  and  although  the  striped-joints  are  less  neat  in  appearance, 
they  are  by  many  considered  sounder  from  the  solder  having  been  left  undisturbed  in  the  act  of  cooling. 
The  vertical  joints,  and  those  for  pipes,  whether  finished  with  the  cloth  or  iron,  require  the  cloth  to  sup- 
port the  fluid  solder  when  it  is  poured  on  the  lead. 

Slight  works  in  lead,  such  as  lattices,  requiring  more  neatness  than  ordinary  plumbing,  are  soldered 
with  the  copper-bit  or  copper-bolt ; they  are  pieces  of  copper  weighing  from  three  or  four  ounces  to  as 
many  pounds,  riveted  into  iron  shanks  and  fitted  with  wooden  handles.  All  the  works  in  tinned  iron, 
sheet-zinc,  and  many  of  those  in  copper  and  other  thin  metals,  are  soldered  with  this  tool,  frequently 
misnamed  a soldering-iron,  which  in  general  suffices  to  convey  all  the  heat  required  to  melt  the  more 
fusible  solders  now  employed. 

If  the  copper-bit  have  not  been  previously  tinned,  it  is  heated  in  a small  charcoal  stove  or  otherwise 
to  a dull  red,  and  hastily  filed  to  a clean  metallic  surface ; it  is  then  rubbed  immediately,  first  upon  a 
tump  of  sal-ammoniac,  and  next  upon  a copper  or  tin  plate,  upon  which  a few  drops  of  solder  have  been 
placed ; this  will  completely  coat  the  tool ; it  is  then  wiped  clean  with  a piece  ot  tow  and  is  ready  for 
use. 

In  soldering  coarse  works,  when  their  edges  are  brought  together  they  are  slightly  strewed  with  pow 
dered  resin,  or  it  is  spread  on  the  work  with  a small  spoon;  the  copper-bit  is  held  in  the  right  hand, 
the  cake  of  solder  in  the  left,  and  a few  drops  of  the  latter  are  melted  along  the  joint  at  short  intervals 


SOLDERING. 


641 


The  iron  is  then  used  to  heat  the  edges  of  the  metal,  both  to  fuse  and  to  distribute  the  solder  along  the 
joint,  so  as  entirely  to  till  up  the  interval  between  the  two  parts ; only  a short  portion  of  the  joint, 
rarely  exceeding  six  or  eight  inches,  is  done  at  once.  Sometimes  the  parts  are  held  in  contact  with  a 
broad  chisel-formed  tool,  or  a hatchet  stake,  whilst  the  solder  is  melted  and  cooled,  or  a few  distant 
parts  are  first  tacked  together  or  united  by  a drop  of  solder,  but  mostly  the  hands  alone  suffice  without 
the  tacking. 

Two  soldering-tools  are  generally  used,  so  that  whilst  the  one  is  in  the  hand  the  other  may  be  reheat- 
ing in  the  stove  ; the  temperature  of  the  bit  is  very  important ; if  it  be  not  hot  enough  to  raise  the  edges 
of  the  metal  to  the  melting  heat  of  the  solder,  it  must  be  returned  to  the  tire ; but  unless  by  misman- 
agement it  is  made  too  hot  and  the  coating  is  burned  off,  the  process  of  tinning  the  bit  need  not  be  re- 
peated, it  is  simply  wiped  on  tow  on  removal  from  the  fire.  If  the  tool  be  overheated  it  will  make  the 
solder  unnecessarily  fluid,  and  entirely  prevent  the  main  purpose  of  the  copper-bit,  which  is  intended  to 
act  both  as  a heating  tool  and  as  a brush,  first  to  pick  up  a small  quantity  or  drop  from  the  cake  of 
solder  which  is  fixed  upright  in  a tray,  and  then  to  distribute  it  alone  the  edge  of  the  joint. 

The  tool  is  sometimes  passed  only  once  slowly  along  the  work,  being  guided  in  contact  with  the  fold 
or  edge  of  the  metal.  This  supposes  the  operator  to  possess  that  dexterity  of  hand  which  is  abundantly 
exhibited  in  many  of  the  best  tin  wares ; in  these  the  line  of  solder  is  very  fine  and  regular.  The  sol- 
dering-tool is  then  thin  and  keen  on  the  edge,  and  the  flux  instead  of  being  resin  is  mostly  the  muriate 
of  zinc,  with  which  the  joint  is  moistened  by  means  of  a small  wire  or  a stick  prior  to  the  application  of 
the  heated  tool ; sometimes  the  workman  cools  the  part  just  finished  by  blowing  upon  it  as  the  bit  pro- 
ceeds in  its  course ; and  the  iron  if  overheated  is  cooled  upon  a moistened  rag  placed  in'  the  empty 
space  of  the  tray  containing  the  solder. 

Copper  works  are  more  commonly  fluxed  with  powdered  sal-ammoniac,  and  so  likewise  sheet-iron, 
although  some  mix  powdered  resin  and  sal-ammoniac ; others  moisten  the  edges  of  the  work  with  a satu- 
rated solution  of  sal-ammoniac,  using  a piece  of  cane,  the  end  of  which  is  split  into  filaments  to  make  a 
stubby  brush,  and  they  subsequently  apply  resin  : each  method  has  its  advocates,  but  so  long  as  the 
metals  are  well  defended  from  oxidation  any  mode  will  suffice,  and  in  general  management  the  pro- 
cesses are  the  same. 

Zinc  is  more  difficult  to  solder  than  the  other  metals,  and  the  joints  are  not  generally  so  neatly  exe- 
cuted ; the  zinc  seems  to  remove  the  coating  of  tin  from  the  copper  soldering-tool ; this  probably  arises 
from  the  superior  affinity  of  copper  for  zinc  than  for  tin.  The  flux  sometimes  used  for  zinc  is  sal-ammo- 
niac, but  the  muriate  of  zinc,  made  by  dissolving  fragments  cf  zinc  in  muriatic  acid  diluted  with  about 
an  equal  quantity  of  water,  is  much  superior ; and  the  muriate  of  zinc  serves  admirably  likewise  for  all 
the  other  metals,  without  such  strict  necessity  for  clean  surfaces  as  when  the  other  fluxes  are  used. 

The  copper  tool  is  only  applicable  to  thin  metals,  because  it  requires  such  a degree  of  heat  as  will 
allow  it  to  raise  the  temperature  of  the  work  to  be  joined  to  the  melting  point  of  the  solder ; and  the 
excess  of  heat  thus  required  for  stout  metals,  is  apt  either  to  burn  off  the  coating  of  solder,  or  to  cause 
it  to  be  absorbed  as  a process  of  superficial  alloying.  It  requires  some  tact  to  keep  the  heat  of  the  tool 
within  proper  limits  by  means  of  the  charcoal  or  cinder  fire,  but  with  the  airo-hydrogen  blowpipe  it  is 
easy  to  maintain  any  required  temperature  for  an  indefinite  period. 

Thicker  pieces  of  metal,  such  as  the  parts  of  philosophical  apparatus,  gas-fittings,  and  others  which 
cannot  be  conveniently  managed  with  the  copper-bit,  are  first  prepared  by  fifing  or  turning,  and  each 
piece  is  then  separately  tinned  in  one  of  the  following  ways.  Small  pieces,  immediately  after  being 
cleaned  with  the  file  or  other  tool,  and  without  being  touched  with  the  fingers,  are  dipped  into  a ladle 
containing  melted  solder,  which  is  covered  with  a little  powdered  sal-ammoniac.  The  flux  meets  the 
work  before  it  is  subjected  to  the  heat,  and  the  tinning  is  then  readily  done  ; sometimes  the  work  is  in 
the  first  instance  sprinkled  with  resin,  or  rubbed  over  with  sal-ammoniac  water ; the  latter  is  rather  a 
dangerous  practice,  as  the  moisture  is  apt  to  drive  the  melted  metal  in  the  face  of  the  operator. 

Thin  pieces  of  bx-ass  or  of  copper  alloys,  if  submitted  to  this  method,  must  be  quickly  dipped,  or  their 
is  risk  of  their  being  attacked  and  partly  dissolved  by  the  solder.  There  is  some  little  uncertainty  as 
to  iron,  and  especially  as  to  steel,  being  well  coated  by  dipping;  sometimes  a forcible  jar  or  a hard  rub 
will  remove  most  of  the  tin,  and  it  is  therefore  safer  to  rub  these  works  with  a piece  of  heated  copper 
shaped  like  a file,  immediately  on  their  removal  from  the  melted  solder,  which  makes  the  adhesion 
more  certain. 

Larger  pieces  of  metal,  or  those  it  is  inconvenient  to  dip  into  the  ladle,  are  first  moistened  with  sal 
ammoniac  water,  or  dusted  with  the  dry  powder  or  resin,  and  heated  on  a clear  fire  either  of  charcoal, 
coke,  or  cinders,  until  the  strip  of  solder  held  against  them  is  melted  and  adheres ; as  the  lowest  heat 
should  be  always  used.  Another  cleanly  way  of  applying  the  heat,  and  which  is  also  employed  in  tem- 
pering tools,  varnishing,  and  cementing,  is  to  make  red-hot  a few  inches  of  the  end  of  a flat  iron  bar 
about  two  feet  long,  to  pinch  it  in  the  vice  by  the  cold  part,  and  to  lay  the  work  upon  that  spot  which 
is  at  a suitable  temperature ; the  work  can  be  thus  very  conveniently  managed,  especially  as  it  may  be 
likewise  placed  in  a good  light. 

Until  the  two  parts  of  the  work  are  thoroughly  tinned,  they  must  be  well  defended  from  the  air  by 
the  flux  to  prevent  oxidation  ; they  are  next  made  a trifle  hotter  than  is  required  for  tinning,  and  placed 
in  contact  while  the  solder  is  quite  fluid,  and  a little  additional  solder  is  also  used ; when  practicable, 
the  two  surfaces  are  rubbed  together  to  perfect  the  tinning  and  spread  the  alloy  evenly'  through  the 
joint,  the  work  is  then  allowed  to  cool  under  pressure  applied  by  the  hammer  handle,  the  blunt  end  of  a 
tool,  the  tail-vice,  or  in  any  convenient  manner.  The  stages  of  this  practice  are  similar  to  those  of  the 
carpenter,  who  having  brushed  the  glue  over  the  two  pieces  of  wood,  rubs  them  together  and  fixes  them 
with  the  hand-screws  until  cold,  as  before  adverted  to. 

Small  works  are  sometimes  united  by  cleaning  the  respective  surfaces,  moistening  them  with  sal- 
ammoniac  water,  or  applying  the  dry  powder  or  resin,  then  placing  between  the  pieces  a slip  of  tin 
Vol.  II. — 41 


642 


SOLDERING. 


foil,  previously  cleaned  with  emery-paper,  and  pinching  the  whole  between  a pair  of  heated  tongs  to 
melt  the  foil ; or  other  similar  modifications  combining  heat  and  pressure  are  used. 

Many  workmen  who  are  accustomed  to  the  blowpipe,  as  jewelers,  mathematical  instrument  makers, 
and  others,  apply  the  blowpipe  with  great  success  in  soft-soldering  ; but  as  the  methods  are  in  other 
respects  similar  to  those  given,  they  do  not  require  particular  notice,  except  that  in  some  cases  there  is 
no  choice  but  to  tie  the  works  together  with  binding  wire,  as  in  hard-soldering ; but  the  preference  is 
always  given  to  detached  tinning  and  rubbing  together. 

The  modern  gas-fitters  are  remarkably  expert  in  joining  tin  and  lead  pipes  with  the  blowpipe ; they 
do  not  employ  the  method  of  the  plumbers  and  pewterers,  or  the  spigot  and  faucet  joint  surrounded  by 
a bulb  of  solder,  but  they  cut  off  the  ends  of  the  pipes  with  a saw,  and  file  the  surfaces  to  meet  in  butt- 
joints,  in  mitres,  or  in  T-form  joints,  as  required.  In  confined  situations  they  apply  the  heat  from  one 
side  only  with  the  blowpipe  and  rushes;  they  employ  a rich  tin-solder,  with  oil  and  resin  mixed  in 
equal  parts  as  the  flux ; the  work  looks  like  carpentry  rather  than  soldering. 

An  ingenious  workman  assured  us  that  he  had  employed  this  mode,  for  lead  pipes  measuring 
externally  one  inch  and  a half  diameter  and  situated  in  angles,  by  placing  pieces  of  slate  against  the 
floor  and  the  perpendicular  partition  to  defend  them  from  the  flame,  the  action  of  which  was  assisted 
by  two  pieces  of  charcoal  inserted  in  the  corners.  And  also  that  as  a trial  of  skill,  he  had  made  fifteen 
joints  in  three-quarter  inch  tin  pipe,  five  of  each  kind,  namely,  plain,  mitre,  and  T form,  including  the 
preparations,  in  the  exceedingly  short  period  of  twenty-five  minutes. 

Iron,  copper,  and  alloys  of  the  latter  metal,  are  frequently  coated  with  tin,  and  occasionally  with  lead 
and  zinc,  to  present  surfaces  less  subject  to  oxidation ; gilding  and  silvering  are  partly  adopted  from 
similar  motives. 

Copper  and  brass  vessels  are  first  pickled  with  sulphuric  acid,  mostly  diluted  with  about  three  times 
its  bulk  of  water;  they  are  then  scrubbed  with  sand  and  water,  washed  clean  and  dried;  they  are  next 
sprinkled  with  dry  sal-ammoniac  in  powder,  and  heated  slightly  over  the  fire ; then  a small  quantity  of 
melted  block-tin  is  thrown  in,  the  vessel  is  swung  and  twisted  about  to  apply  the  tin  on  all  sides,  and 
when  it  has  well  adhered  the  portion  in  excess  is  returned  to  the  ladle,  and  the  object  is  cooled  in 
water,  When  cleverly  performed  very  little  tin  is  taken  up,  and  the  surface  looks  almost  as  bright  as 
silver ; some  objects  require  to  be  dipped  into  a ladle  full  of  tin. 

Iron  presents  rather  more  difficulty,  the  affinity  of  the  tin  being  less  strong  for  iron  than  for  copper ; 
but  the  treatment  is  in  general  nearly  the  same.  Old  works  require  that  the  grease  should  be  removed 
with  concentrated  muriatic  acid,  before  the  other  processes  are  commenced ; and  in  cast-iron  vessels  the 
grease  often  penetrates  so  deeply,  owing  to  the  porous  nature  of  the  metal,  that  the  retinning  is  some- 
times scarcely  possible,  and  it  is  often  more  economical  to  obtain  a new  vessel. 

An  alloy  of  nickel,  iron,  and  tin,  has  been  introduced  as  an  improvement  in  tinning  the  metals. 
Mr.  G.  M.  Braithwaite,  one  of  the  patentees,  says  that  “ the  nickel  and  tin  compound  is  harder 
than  tin,  and  endures  a much  longer  time  ; it  is  less  fusible,  and  will  not  run  or  melt  at  a heat  that, 
would  cause  the  ordinary  tinning  of  pans  to  forsake  the  sides  and  lie  in  a mass  at  the  bottom.  Also 
that  as  an  experiment  to  show  the  tenacity  of  the  nickel,  a piece  of  cast-iron  tinned  with  the  compound 
had  been  subjected  by  him  for  a few  minutes  to  the  white  heat  under  a blast,  and  although  the  tin  was 
consumed,  the  nickel  remained  as  a permanent  coating  upon  the  iron.” 

The  proportions  of  nickel  and  iron  mixed  with  the  tin  in  order  to  produce  the  best  tinning,  are  ten 
ounces  of  the  best  nickel  and  seven  ounces  of  sheet-iron  to  ten  pounds  of  tin.  These  metals  are  mixed 
in  a crucible,  and  to  prevent  the  oxidation  of  the  tin  by  the  high  temperature  necessary  for  the  fusion  of 
the  nickel,  the  metals  are  covered  with  one  ounce  of  borax  and  three  ounces  of  pounded  glass.  The 
fusion  is  completed  in  about  half  an  hour,  when  the  composition  is  run  off  through  a hole  made  in  the 
flux.  In  tinning  metals  with  this  composition  the  workman  proceeds  in  the  ordinary  manner. 

There  is  also  another  method,  that  of  cold-tinning , by  aid  of  the  amalgam  of  mercury ; but  this  pro- 
cess, when  applied  to  utensils  employed  for  preparing  or  receiving  food,  appears  questionable  both  as 
regards  effectiveness  and  wholesomeness,  and  the  activity  of  the  muriatic  acid  must  not  be  forgotten ; it 
should  be  therefore  washed  carefully  off  with  water.  The  tin  adheres,  however,  sufficiently  well  to 
allow  other  pieces  of  metal  to  be  afterwards  attached  by  the  ordinary  copper  soldering-bit. 

Soldering  per  se,  or  hurtling  together. — This  principally  differs  from  ordinary  soldering,  in  the  circum- 
stance that  the  uniting  or  intermediate  metal  is  the  same  as  those  to  be  joined,  and  that  in  general  no 
fluxes  are  employed. 

The  method  of  burning  together,  although  it  only  admits  of  limited  application,  is  in  many  cases  of 
great  importance,  as  when  successfully  performed  the  works  assume  the  condition  of  greatest  strength, 
from  all  parts  being  alike.  There  is  no  dissimilarity  between  the  several  parts  as  when  ordinary  solders 
are  used,  which  are  open  to  an  objection,  that  the  solders  expand  and  contract  by  heat  either  more  or 
less  than  the  metals  to  which  they  are  attached.  There  is  another  objection  of  far  greater  moment : 
the  solders  oxidize  either  more  or  less  freely  than  the  metals,  and  upon  which  circumstances  hinge  some 
galvanic  or  electrical  phenomena;  and  thence  the  soldered  joints  constitute  galvanic  circuits,  which  in 
some  cases  cause  the  more  oxidizable  of  the  two  metals  to  waste  with  the  greater  rapidity,  especially 
when  heat,  moisture,  or  acids  are  present. 

In  chemical  works  this  is  a most  serious  inconvenience,  and  therefore  leaden  vessels  and  chambers  for 
sulphuric  acid  must  not  be  soldered  with  tin-solder,  the  tin  being  so  much  more  freely  dissolved  than 
the  lead.  Such  works  were  formerly  burned  together  by  pouring  red-hot  lead  on  the  joint,  and  fusing 
the  parts  into  one  mass,  by  means  of  a red-hot  soldering-iron.  This  is  troublesome  and  tedious,  and  it 
is  now  replaced  by  the  autogenous  soldering. 

Pewter  is  sometimes  burned  together  at  the  external  angles  of  works,  simply  that  no  difference  ol 
color  may  exist;  the  one  edge  is  allowed  to  stand  a little  above  the  other,  a strip  of  the  same  pewter  is 
laid  in  the  angle,  and  the  whole  are  melted  together,  with  a large  copper-bit  heated  almost  to  redness 
the  superfluous  metal  is  then  filed  off,  leaving  a well-defined  angle  without  any  visible  joint. 


SOLDERING. 


643 


Brass  is  likewise  burned  together ; for  instance,  the  rims  of  large  mural  circles  for  observatories,  that 
are  live,  six,  or  seven  feet  diameter,  are  sometimes  cast  in  six  or  more  segments,  and  attached  by  burn- 
ing. The  ends  of  the  segments  are  tiled  clean,  two  pieces  are  fixed  vertically  in  a sand  mould  in  their 
relative  positions,  a shallow  space  is  left  around  the  joint,  and  the  entire  charge  of  a crucible,  say  thirty 
or  forty  pounds  of  the  melted  brass  a little  hotter  than  usual,  is  then  poured  on  the  joint  to  heat  it  to 
the  melting  point.  The  metal  overflows  the  shallow  chamber  or  hole,  and  runs  into  a pit  prepared  for 
it  in  the  sand  ; but  the  last  quantity  of  metal  that  remains,  solidifies  with  the  ends  of  the  segments,  and 
forms  a joint  almost  or  quite  as  perfect  as  the  general  substance  of  the  metal ; the  process  is  repeated 
for  every  joint  of  the  circle. 

The  compensation  balance  of  the  chronometer  and  superior  watches  is  an  interesting  example  of 
natural  soldering.  The  balance  is  a small  fly-wheel  made  of  one  piece  of  steel,  covered  with  a hoop  of 
brass ; the  rim  consisting  of  the  two  metals,  is  divided  at  the  two  extremities  of  the  one  diametrical  arm 
of  the  balance,  so  that  the  increase  of  temperature  which  weakens  the  balance-spring  contracts  in  a pro- 
portionate degree  the  diameter  of  the  balance,  leaving  the  spring  less  resistance  to  overcome.  This 
occurs  from  the  brass  expanding  much  more  by  heat  than  steel,  and  it  therefore  curls  the  semicircular 
arcs  inwards,  an  action  that  will  be  immediately  understood  if  we  conceive  the  compound  bar  of  brass 
and  steel  to  be  straight,  as  the  heat  would  render  the  brass  side  longer  and  convex,  and  in  the  balance 
it  renders  it  more  curved. 

In  the  compensation  balance,  the  two  metals  are  thus  united : the  disk  of  steel  when  turned  and 
pierced  with  a central  hole,  is  fixed  by  a little  screw-bolt  and  nut  at  the  bottom  of  a small  crucible  with 
a central  elevation,  smaller  than  the  disk ; the  brass  is  now  melted  and  the  whole  allowed  to  cool.  The 
crucible  is  broken,  the  excess  of  brass  is  turned  off  in  the  lathe,  the  arms  are  made  with  the  file  as  usual, 
the  rim  is  tapped  to  receive  the  compensation  screws  or  weights,  and  lastly  the  hoop  is  divided  in  two 
places,  at  opposite  ends  of  its  diametrical  arm. 

A little  black-lead  is  generally  introduced  between  the  steel  and  the  crucible ; and  other  but  less 
exact  modes  of  combining  the  metals  are  also  employed. 

Cast-iron  is  likewise  united  by  burning,  as  will  be  explained  by  the  following  example : to  add  a 
flange  to  an  iron  pipe,  a sand  mould  is  made  from  a wood  model  of  the  required  pipe,  but  the  gusset  or 
chamfered  band  between  the  flange  and  tube  is  made  rather  fuller  than  usual,  to  afford  a little  extra 
base  for  the  flange.  The  mould  is  furnished  with  an  ingate,  entering  exactly  on  the  horizontal  parting 
of  the  mould,  at  the  edge  of  the  flange,  and  with  a waste-head  or  runner  proceeding  upwards  from 
the  top  of  the  flange,  and  leading  over  the  edge  of  the  flask  to  a hollow  or  pit  sunk  in  the  sand  oi 
the  floor. 

The  end  of  the  pipe  is  filed  quite  clean  at  the  place  of  junction,  and  a shallow  nick  is  filed  at  the  inner 
edge  to  assist  in  keying  on  the  flange  ; lastly  the  pipe  is  plugged  with  sand  and  laid  in  the  mould.  After 
the  mould  is  closed,  about  six  or  eight  times  as  much  hot  metal  as  the  flange  requires  is  poured  through 
the  mould ; this  heats  the  pipe  to  the  temperature  of  the  fluid  iron,  so  that  on  cooling  the  flange  is  at- 
tached sufficiently  firm  to  bear  the  ordinary  pressure  of  screw-bolts,  steam,  &c* 

The  method  of  burning  is  occasionally  employed  in  most  of  the  metals  and  alloys,  in  making  small 
additions  to  old  castings,  and  also  in  repairing  trifling  holes  and  defects  in  new  ones ; it  is  only  success- 
ful, however,  when  the  pieces  are  filed  quite  clean,  and  abundance  of  fluid  metal  is  employed,  in  order 
to  impart  sufficient  heat  to  make  a natural  soldering : a jjrocess  which  is  also,  although  differently 
accomplished,  in  plating  copper  with  silver,  as  the  two  metals  are  raised  to  a heat  just  short  of  the 
melting-point  of  the  silver,  and  the  metals  then  unite  without  solder  by  partial  alloying. 

To  conclude  the  description  of  soldering  processes,  we  have  to  refer  to  the  airo-hydrogen\  blowpipe, 
invented  in  France  by  the  Count  de  Richemont.  It  is  in  a great  measure  converting  the  oxy-hydrogen 
blowpipe,  invented  by  Dr.  Hare,  to  the  service  of  the  workshop,  and  it  is  done  with  great  simplicity  and 
safety.  An  elastic  tube  supplies  hydrogen  from  the  generator,  and  a pipe  supplies  atmospheric  air  from 
a small  pair  of  double  bellows  worked  by  the  foot  of  the  operator,  and  compressed  by  a constant  weight ; 
the  two  pipes  meet  in  an  arch,  and  proceed  through  the  third  pipe  to  a small  jet,  from  whence  proceeds 
the  flame.  All  the  connections  are  by  elastic  tubes,  which  allow  perfect  freedom  of  motion,  so  that  the 
portable  blowpipe  is  carried  to  the  work. 

In  soldering  by  the  autogenous  process,  the  works  are  first  prepared  and  scraped  clean  as  usual,  the 
hydrogen  is  ignited,  and  the  size  of  the  flame  is  proportioned  by  a stop-cock ; the  ah'  is  then  admitted 
through  the  air-pipe  until  the  flame  assumes  a fine-pointed  character,  with  which  the  work  is  united 
after  the  general  method  of  blowpipe  soldering,  except  that  a strip  of  lead  is  used  instead  of  solder,  and 
generally  without  any  flux. 

This  mode  is  described  as  being  suitable  to  most  of  the  metals,  but  its  best  application  appears  to  be 
to  plumber’s  work.  The  weight  of  lead  consumed  in  making  the  joints  is  a mere  fraction  of  the  weight 
of  ordinary  solder,  which  is  both  more  expensive  and  more  oxidizable,  from  the  tin  it  contains.  The  gas 
soldering,  as  it  is  called,  removes  likewise  the  risk  of  accidents  from  the  plumber’s  fires,  as  the  gas  gen- 


* Steam  and  water-tight  joints,  in  cast-iron  works  not  requiring  the  power  of  after-separation,  are  often  made  by  means 
of  iron  cement  in  the  following  proportions:  112  lbs.  of  cast-iron  filings  or  borings,  1 lb.  of  sal-ammoniac,  1 lb.  of  sulphur, 
and  4 lbs.  of  whitening.  Small  quantities  of  the  materials  are  mixed  together  with  a little  water  shortly  before  use. 

For  minute  cracks  the  cement  is  laid  on  externally  as  a thin  seam,  or  for  larger  spaces  it  is  driven  in  with  caulking-irons. 
The  edges  of  the  metal  and  the  cement  shortly  commence  one  common  process  of  rusting,  and  at  the  end  of  a week  or  ten 
days  the  joints  will  be  found  hard,  dry,  and  permanent. 

t The  following  is  the  broad  difference  between  the  airo-hydrogen  and  the  oxy-hydrogen  blowpipes.  In  the  oxy-hydro- 
gen blowpipe,  the  pure  gases  are  mixed  in  the  exact  proportions  of  two  volumes  of  hydrogen  to  one  of  oxygen,  which 
quantities  when  combined  constitute  water,  and  in  this  particular  case  there  is  the  greatest  condensation  of  volume,  and 
the  greatest  evolution  of  latent  as  well  as  of  sensible  heat. 

The  airo-hydrogen  blowpipe  is  supplied  wilh  common  air  and  with  pure  hydrogen;  this  instrument  is  also  the  most 
effective  when  the  oxygen  and  hydrogen  are  mixed  in  the  proportions  of  1 to  2;  but  the  nitrogen,  which  constitutes  four- 
fifths  of  our  atmosphere,  is  now  in  the  way  and  detracts  from  the  intensity  of  the  effect. 


644 


SPARK  ARRESTER. 


erator  which  is  in  itself  harmless,  may  he  allowed  to  remain  on  the  ground  whilst  the  workman  ascends 
to  tne  roof,  or  elsewhere,  with  the  pipe. 

Lead  is  interposed  as  solder  in  uniting  zinc  to  zinc,  and  it  is  also  used  m soldei'ing  the  brass  nozzles 
and  cocks  to  the  vessels  of  lead,  and  those  of  copper  coated  with  lead,  used  as  generators.  Another 
very  practical  application  of  the  gas  flame  is  for  keeping  the  copper  soldering  tool  at  one  temperature, 
which  is  done  hy  leading  the  mixed  gases  through  a tube  in  the  handle,  so  that  the  flame  plays  on  the 
back  of  the  copper  bit.  This  mode  seems  to  be  very  well  adapted  to  tin-plate  and  zinc  works,  espe 
eially  as  the  common  street-gas  may  be  used,  thereby  dispensing  with  the  necessity  for  a gas  generator 

SPANDRIL.  An  irregular  triangular  space  formed  between  the  outer  curve  or  extrados  of  an  arch 
and  a line  tangent  at  or  near  the  crown,  and  the  perpendicular  line  from  the  springing»of  the  arch. 

SPARK  ARRESTER — Cutting’s  patent.  Fig.  3339  is  a vertical  section  of  the  machine. 

Fig.  3341,  a view  of  the  diaphragm  with  its  curved  and  inclined  planes,  separating  the  outer  chamber 
from  the  inner  chambers,  and  exhibiting  a view  of  the  ventilators,  or  air-flues,  in  the  lower  or  inclined 
section. 

Fig.  3342  is  a horizontal  view  of  the  under  side  of  Fig.  3341,  showing  a series  of  ventilators  or  air- 
lines, and  the  curved  plane. 

Fig.  3340  is  a perspective  view  of  a section,  showing  the  combination  of  the  different  parts. 

Fig.  3343  is  a horizontal  view,  taken  at  the  line  a a of  Fig.  3344,  showing  the  air-flue,  and  the  en- 
trance of  the  ventilating  tubes. 

Fig.  3344  is  a vertical  section  of  the  chimney  in  combination  with  the  ventilating  tubes  and  air- 
chambers. 

The  same  letters  in  the  several  figures  represent  the  same  parts. 

The  nature  of  the  first  part  of  this  invention  consists  in  arranging  upon  the  outside  of  the  inclined 
plane,  at  the  base  of  the  diaphragm,  a series  of  air-flues,  extending  from  the  spark-chamber  through 
the  diaphragm,  the  mouths  of  said  flues  being  in  the  spark-cliamber,  and  their  exits  in  the  diaphragm, 
so  that  the  rotary  current  of  steam,  &c.,  through  a series  of  curved  flues  in  said  diaphragm,  will  pass 
over  the  exits  of  said  air-flues,  causing  a current  of  air  to  be  drawn  from  said  spark-chamber  through 
said  air-flues  in  the  direction  of  the  current  of  steam,  &c.,  for  the  purpose  of  creating  a partial  vacuum 
in  said  spark-chamber  into  which  the  sparks  fall.  And  in  order  to  effect  the  deposit  of  such  light 
particles  as  may  possibly  reach  the  top  of  the  diaphragm,  the  nature  of  the  second  part  of  the  in- 
vention consists  in  arranging  an  air-chamber  within  the  diaphragm  at  the  top  of  the  stack,  which 
chamber  is  ventilated  or  exhausted  by  means  of  tubes  connecting  that  chamber  with  the  air-flue  at 
the  bottom  of  the  chamber  at  the  top  of  the  chimney. 

To  enable  others  skilled  in  the  art  to  make  and  use  this  invention,  we  will  proceed  to  describe  the 
same  with  reference  to  the  drawings. 


3339.  3340. 


At  the  top  of  the  chimney  A is  placed  an  air-chamber  B,  over  which  is  placed  a deflecting  cone  C,  in 
the  form  of  a funnel,  with  the  outer  edges  turned  down  all  around  uniformly,  to  reverberate  the  steam, 
gases,  and  particles,  and  throw  them  into  a series  of  curved  and  inclined  flues  D,  surrounding  the  air- 
chamber  B,  by  which  a whirling  or  rotary  motion  is  produced  within  the  diaphragm  0.  This  dia- 
phragm is  provided  with  a series  of  apertures  G-.  The  exhaust  steam,  in  passing  through  th# 


SPEEDER 


615 


chimney  A into  the  air-chamber  B,  has  the  effect  of  drawing  a current  of  air  between  the  curved  plane 
K,  and  the  chimney  A.,  through  the  air-flues  F,  out  of  the  spark-chamber  J. 

The  air-flues  F are  arranged  on  the  outer  side  of  the  inclined  plane  E,  at  the  base  of  the  diaphragm, 
and  extend  from  the  chamber  J through  the  diaphragm  O.  The  mouths  of  the  flues  F are  in  the  spark- 
chamber  J,  and  their  exits  c in  the  diaphragm  O,  the  current  of  air  through  them  being  in  the  direction, 
of  the  current  of  steam,  passing  through  the  inclined  flues  D,  as  shown  by  the  arrows,  so  as  to  allow 
the  air  to  pass  out  from,  and  prevent  the  sparks,  &c.,  from  passing  into  the  spark-chamber  through  said 
flues  F. 

At  the  bottom  of  the  diaphragm  0,  under  the  series  of  curved  and  inclined  flues  D,  is  a curved 
plane  K,  and  an  inclined  plane  E.  In  the  inclined  plane  E is  placed  the  series  of  flues  F above 
described.  The  effect  of  the  passage  of  thte  circular  current  of  steam,  <fcc.,  within  the  diaphragm  O, 
and  over  the  air-flues  F,  is  to  still  further  exhaust  the  spark-chamber  J of  its  air,  on  the  same  prin- 
ciple that  the  spark-chamber  J is  ventilated  by  the  passage  of  steam,  etc.,  over  the  air-flue  P,  (shown 
by  dotted  lines  in  Fig.  3344,)  at  the  bottom  of  the  air-chamber  B. 

The  circular  current  has  the  tendency  by  its  centrifugal  force  to  throw  the  particles  off  in  a tan- 
gent, against  the  inner  walls  of  the  diaphragm  0,  and  through  the  apertures  G into  the  outer  or 
spark-chamber  J.  The  deposit  of  the  sparks,  &c.,  in  the  spark-chamber  J is  greatly  facilitated  by 
the  action  of  the  partial  vacuum  in  the  spark-chamber  J,  by  which  a draught  is  occasioned  through  the 
apertures  G of  the  diaphragm  O,  towards  said  spark-chamber  J. 

3341.  3344. 


It  will  be  seen  that  the  spark-chamber  J is  exhausted  of  its  air,  in  part,  by  every  pulsation  of  ex- 
haust steam,  consequently  between  every  pulsation  there  will  be  a draught  towards  the  spark-chamber 
J through  the  air-flue  as  well  as  through  the  aperture  G of  the  diaphragm  0.  This  draught  through  the 
air-flue  towards  the  spark-chamber  J will  have  the  effect  to  create  a draught  upwards  through  the 
chimney  A,  by  which  the  draught  of  the  furnace  will  be  to  a great  extent  regulated,  and  the  heat  cor- 
respondingly increased. 

Fig.  3344  represents  the  chimney  A,  with  air-chamber  B,  in  connection  with  'he  pipes  H,  which 
pass  to  another  air-chamber  I,  at  the  top  of  the  stack.  The  passage  of  the  steam  through  the  chim- 
ney A tends  to  draw  a current  of  air  through  the  pipes  H,  in  the  same  manner  in  which  the  ventila- 
tion of  the  spark-chamber  J is  effected,  the  result  of  which  is  to  exhaust  the  air-chamber  I of  a por- 
tion of  its  air.  This  air-chamber  I is  provided  with  apertures,  the  object  of  which  is  to  arrest  such 
light  particles  as  may  possibly  reach  the  top  of  the  stack,  and  cause  them  to  pass  around  again  with 
the  view  of  their  being  deposited.  L is  the  general  outlet  of  the  steam  and  such  gases  as  may  be 
evolved. 

SPECIFIC  GRAVITY.  See  Gravity. 

SPEEDER.  After  cotton  in  the  course  of  preparation  for  yarn  has  passed  through  the  drawing-frame, 
the  next  operation  is  the  making  of  roving ; this  is  effected  in  most  American  mills  by  the  speeder. 
Of  speeders  there  is  some  variety ; as  the  Taunton  speeder,  the  Eclipse  speeder,  the  Plate  speeder,  and 
the  Double  speeder.  The  rovings  produced  from  the  first  three  are  alike,  having  no  twist  and  built  on 
bobbins  or  spools  with  conical  ends.  In  the  first  the  roving  passes  through  a revolving  tube,  in  the 
second  between  two  opposing  surfaces  of  a travelling  endless  belt ; in  the  third,  between  two  plate  sur- 
faces revolving  in  opposite  directions.  The  double  speeder  is  somewhat  similar  to  the  English  bobbin 
ana  fly  frame.  The  double  speeder  is  made  in  two  different  forms,  the  first  of  which  receives  the  arms 


04G 


SPIKE  MACHINE. 


direct  from  the  drawing  frame,  and  has  only  one  row  of  spindles  on  one  side  of  the  frame ; these  are 
usually  called  speeders:  the  other  receives  the  bobbins  from  the  speeders  and  still  further  reduces  the 
rovings ; these  are  called  stretchers,  and  have  rows  of  spindles  on  each  side  like  the  throstle.  The 
roving  from  these  machines,  unlike  the  first  varieties,  has  a little  twist : the  chief  objection  to  them 
lies  in  the  power  required  to  drive  them,  and  on  this  account  chiefly,  they  have  been  superseded  by  the 
bobbin  and  fly  frame  in  the  finer  mills ; two  machines  being  commonly  used,  corresponding  to  the 
speeder  and  stretcher,  a coarse  and  fine  frame.  In  their  general  action  they  may  be  said  to  unite  the 
drawing  and  spinning  frame,  performing  both  processes,  and  being  the  connecting  link  between  the  two. 


SPIKE  MACHINE.  Burden’s  Patent.  “ In  my  improved  machine,  the  feeding  in  of  the  rod,  the 
rutting  it  off,  and  the  pointing  the  spike,  are  effected  in  the  way  previously  used  by  me  for  performing 


SPIKE  MACHINE. 


647 


3346. 


the  same  offices  in  my  ordinary  spike  machines, 
or  adopted  by  others ; and  my  improvement  for 
forming  the  spikes  with  hook  or  brad  heads,  may 
be  applied  to  spike  machines  of  various  construc- 
tions. 

Before  the  introduction  of  my  improvement, 
the  heads  of  hook  or  brad-headed  spikes  were, 
so  far  as  I am  informed,  always  made  by  hand, 
and  they  were  necessarily  imperfect,  being  de- 
ficient in  that  uniformity  in  shape  and  strength 
which  are  important  requisites.  My  improve- 
ment in  manufacturing  them  consists  principally 
in  the  employment  of  what  I denominate  a bend- 
ing lever,  or  some  analogous  device,  by  means  of 
which  the  portion  of  the  rod  which  is  to  consti- 
tute the  head  is  bent  down  so  as  to  form  an  angle 
with  the  shank,  and  in  then  forcing  up  a heading 
die,  properly  formed,  so  as  to  upset  the  bent 
portion,  and  to  cause  it  to  assume  the  desired 
shape. 

In  each  of  these  figures,  where  like  parts  are 
shown,  they  are  designated  by  the  same  letters 
of  reference.  A A is  the  bed-plate  upon  which 
most  of  the  operating  parts  of  the  machine  are 
sustained.  B B are  the  dies  which  grip  and  hold 
the  spike-rod  during  the  time  the  bending  and 
heading  are  effected.  C is  a lever  by  which  the 
die  B is  closed,  the  die  B being  stationary.  This 
lever  is  acted  on  by  the  segmental  cam  D on 
the  driving-shaft  E of  the  machine ; the  frame 
F F,  which  holds  the  die  H,  works  on  a joint- 
rod  c c,  and  is  lifted  by  the  strap  cl  d,  attached 
by  the  joint-pin  e to  the  lever  C.  The  spike-rod 


amS 


G48 


SPIKE  MACHINE. 


fia  to  be  fed  into  the  dies  in  the  usual  way,  and  as  soon  as  the  dies  are  closed  upon  the  piece  to  be 
headed,  the  bending  lever  G has  its  outer  end  h raised  by  the  cam  II  on  the  shaft  E,  which  causes  its 
end  g to  descend  upon  the  projecting  end  of  the  spike-rod,  and  to  bend  it  down  in  the  manner  shown. 
I is  the  heading-slide  which  carries  the  heading-die  J,  and  as  soon  as  the  cam  H escapes  from  the  outer 
end  of  the  bending  lever  h,  and  that  end  descends,  the  cam  K comes  in  contact  with  the  end  L of  the 
heading-slide,  which  it  forces. 


In  the  accompanying  figures  a represents  the  frame-work  of  the  machine,  in  which  are  hung  tne 
shafts  b b b of  three  rolls  ccc,  arranged  at  equal  distances  around  a common  axis.  Each  shaft  has  two 
journals  running  in  boxes  dd,  the  lower  one  so  mounted  in  the  frame  by  means  of  set-screws  e the  axis 
of  the  rollers  can  be  adjusted  in  a radial  direction  from  or  towards  the  central  line  around  which  they 
are  arranged.  The  rolls  are  frustums  of  cones  from  the  lines  1 to  2,  and  2 to  3,  which  is  the  extremity 
of  the  rolls ; they  are  in  the  form  of  the  frustum  of  a flatter  or  more  obtuse  cone,  so  that  in  the  plane 
of  the  radii  of  the  common  centre,  the  latter  part  will  be  parallel  with  the  common  axis  around  which 
the  three  rolls  are  arranged. 


SPIKE  MACHINE. 


641} 


3353. 


335G. 


3249. 


650 


SPIKE  MACHINE. 


There  is  a cog-wheel/  on  the  shaft  of  each  of  the  rolls,  the  three  being  of  equal  diameter,  and  these, 
three  are  caused  to  rotate  in  the  same  direction  by  means  of  two  intermediate  cog-wheels  g g.  The 
driving  power  should  be  applied  to  the  shaft  h of  one  of  the  rolls  in  any  desired  manner,  although  it 
may  be  applied  to  the  shafts  of  one  of  the  intermediate  wheels.  The  dotted  lines  ij  in  sections, 
represent  the  inclination  of  the  axis  of  the  rolls,  and  the  intermediate  wheels  form  the  axis  round 
which  they  are  arranged,  and  the  dotted  lines  k k k represent  vertical  planes  radiating  from  this 
common  axis,  and  the  dotted  lines  III  the  lines  of  the  axis  of  the  three  rolls  which  are  slightly  inclined 
thereto 


When  the  rolls  are  set  in  motion  a loop  or  ball  of  iron  m,  in  a highly  heated  state,  is  dropped  in  be- 
tween them,  at  their  upper  end,  the  frame-work  being  left  open  above  for  that  purpose,  and  the  slight 
inclination  of  the  axis  of  the  three  rolls  from  the  vertical  plane,  as  indicated  by  the  dotted  lines  b bb, 
causes  the  rolls  gradually  to  carry  down  between  them  the  ball  of  iron  towards  their  lower  end,  where 
they  are  nearer  together  by  reason  of  the  inclination  of  their  axis  from  the  vertical  line  being  greater 
than  the  lines  of  the  cones. 


By  this  means  not  only  is  the  mass  of  iron  gradually  drawn  down  in  the  direction  of  the  common 
axis,  around  which  the  rolls  are  arranged,  but  by  the  action  of  the  rotating  surface  of  the  rolls,  in  a 
line  nearly  at  right  angles  to  this  common  centre,  the  iron  is  rotated  on  its  axis  and  squeezed  in  a spiral 
direction,  and  the  mass  gradually  elongated  and  carried  out  at  the  bottom  in  a round  bar  n,  of  a di- 
ameter equal  to  the  space  between  the  lower  end  of  the  three  rolls,  where  the  cones  are  so  flat  as  to 
reduce  the  bar  to  a cylindrical  form.  For  the  purpose  of  preventing  the  rolls  from  being  overheated 


STATIONARY  STEAM  ENGINE. 


651 


by  contact  with  the  highly  heated  mass  of  iron  under  treatment,  the  rolls  may  be  made  hollow 
as  indicated  by  the  dotted  lines,  with  a central  water-tube  o,  extending  down  to  near  the  bottom, 
through  which  water  is  introduced,  and  which  flows  out  around  the  tube,  and  is  discharged  at 
the  top. 

Fig.  3345  elevation  of  right  side  of  machine,  showing  the  fly-wheel,  pulleys,  bands,  and  fixtures,  to 
apply  the  moving  power. 

Fig.  3345a  section  of  same  through  cd. 

Fig.  3346  elevation  of  left  side  of  machine  when  closed  in  the  act  of  finishing  a spike. 

Fig.  3346a  section  of  same  through  a b. 

Fig.  3347  front  elevation,  with  pointing-levers  closed. 

Fig.  3348  rear  elevation,  with  pointing-levers  closed. 

Fig.  3349  longitudinal  section  and  elevation  of  machine,  prepared  for  making  hook-head  spikes,  th* 
machine  open,  and  immediately  after  forwarding  the  nail-road,  and  ready  for  the  downward  motion  oi 
the  upper  lever  and  hooker. 

Fig.  3350  section  after  the  downward  motion  of  upper  lever  and  hooker. 

Fig.  3351  section  after  the  downward  motion  of  upper  lever  and  hooker,  with  the  header  home  and 
the  spike  headed  and  pointed. 

Fig.  3352  plan  of  heading-box  and  heading-lever  B,  heading-bolt  FT. 

SPINNING  FRAME.  See  Mule  and  Throstle. 

SPINNING-FRAME  BANDING,  MACHINE  FOR  MAKING.  Applicable  to  the  making  of  small 
cord  for  any  purpose. 

Description. — A,  Fig.  3361,  is  the  combination  of  fixed  loose  pulleys  receiving  the  driving-band.  B 
is  a cone,  from  which  a band  leads  to  a round  cone  directly  in  the  rear  of  B on  the  shaft  b ; thence  In 
another  band  to  the  pulley  c motion  is  communica- 
ted to  shaft  c,  which  takes  up  the  banding  as  it  is 
laid,  which  from  thence  passes  to  a bobbin,  and  is 
wound  by  the  friction  of  a drum  on  which  the  bob- 
bin lies,  which  is  driven  by  a band  from  the  pulley 
f,  but  which  are  not  shown  in  the  drawing.  E is 
the  machine  which  lays  the  banding.  A revolving 
motion  is  given  by  the  band-geer  C around  the  fixed 
spindle  D,  while  the  upper  is  steadied  in  a socket 
at  d.  and  the  whole  is  supported  by  the  point  l 
bearing  on  the  top  of  D.  The  twist  to  be  made 
into  banding  is  wound  on  two  bobbins  p placed 
within  the  flyers  /(,  held  between  two  disks,  which 
disks  are  kept  together  firmly  by  two  rods,  not 
shown  in  the  figure.  The  twist,  as  it  leaves  the 
bobbins,  passes  round  the  rim  of  the  flyer,  or 
through  a staple  in  the  conical  weight  i,  thence 
through  a hole  in  the  end  of  the  bar  f,  thence 
through  the  centre  of  the  flyer  twice  or  thrice 
round  the  geered  rolls  k,  thence  through  the  centre 
of  the  spindle  of  the  machine  E,  when  the  two 
strands  are  twisted  together  or  laid.  The  shaft  E 
takes  up  and  dedivers  the  banding.  It  is  evident 
that  in  laying  the  banding,  if  the  bobbins  were 
stationary,  a portion  of  the  twist  would  be  taken 
out ; to  remedy  this  by  meaus  of  the  geer  m fixed 
on  the  spindle  D and  an  intermediate  n,  motion  is 
given  to  thenjgeer  o to  which  the  flyer  is  fastened  ; 
by  this  means,  as  much  or  more  twist  is  put  into 
the  strands  as  would  be  lost  in  the  laying.  The 
bobbins  of  twist  p are  held  on  spindles,  which  spin- 
dles fit  into  a socket  in  the  bottom  of  the  flyer,  and  the  upper  end  passing  through  the  bar_/"  is  held  by 
a small  screw.  To  take  out  the  spindle,  the  bar  f can  be  revolved. 

STATIONARY  STEAM  ENGINE.  Under  the  head  of  “Engine”  will  be  found  the  usual  varieties 
of  Stationary  Engines.  By  far  the  largest  class  in  this  country  are  horizontal  cylinders,  with  every  va- 
riety of  valve  and  cut  off.  Of  late  years  it  has  been  found  economical  to  avoid  wire  drawing,  to  open 
and  close  the  steam  ports  as  suddenly  as  possible,  and  to  attach  the  governor  directly  to  the  steam-valve. 
Of  this  class  of  engines  Mr.  Geo.  H.  Corliss,  of  Providence,  has  been  the  most  successful  builder  and 
inventor.  Plate  VII  represents  one  of  his  engines : in  this  case  a vertical  engine,  but  the  improvements 
are  equally  adapted  to  horizontal  engines. 

Stationary  Steam  Engine,  Corliss  Patent.  The  chief  peculiarities  lie  in  the  method  of  working  the 
valves,  and  in  controlling  the  valve  motion  by  the  governor,  so  as  to  regulate  the  motion  of  the  engine 
with  perfection,  and  use  the  steam  to  the  best  advantage  under  all  conditions. 

The  valves  employed  are  rotary  sliding  valves.  Their  motion  is  similar  to  that  of  the  common  plug- 
cock  or  faucet,  but  the  form  adopted  is  such  that  they  fill  a portion  only  of  the  cylindrical  cavities  in 
which  they  are  mounted.  The  connection  of  each  valve  to  its  spindle  or  stem  is  such  that  it  is  free  to 
adapt  itself  to  all  conditions.  It  works  freely  and  yet  remains  tight,  precisely  like  an  ordinary  slide 
valve.  There  are  two  steam  valves  cd , and  two  exhaust  valves  ef  all  worked  independently,  yet  by 
simple  mechanism.  The  exhaust  valves  are  held  open  during  the  whole  stroke  of  the  piston,  but  the 
steam  valves  are  opened  at  the  proper  time  and  allowed  to  shut  automatically  at  some  point  in  the  early 


652 


STATIONARY  STEAM  ENGINE. 


portion  of  the  stroke.  The  precise  point  at  which  this  shutting  of  the  steam  valve  occurs,  and  conse- 
quently the  volume  of  steam  admitted  into  the  cylinder  in  any  g ven  stroke,  depends  on  the  position  of 
the  governor  balls  1,  and  the  speed  of  the  engine  is  regulated  by  the  variations  in  the  quantity  of  steam 
thus  admitted.  The  principal  improvements  in  this  engine  are  therefore  twofold. 

First:  There  is  a peculiar  device  for  moving  each  steam  valve  and  each  exhaust  valve,  with  a dis- 
tinct and  independent  motion,  by  means  of  a crank- wrist.  A series  of  crank  wrists,  a 1 a3  a3  u‘,  are  at- 
tached to  a common  disc  or  plate,  a,  which  latter  is  secured  to  a rock  shaft  connected  with  the  main  ec- 
centric. Each  wrist  operates  through  a distinct  lever  upon  its  proper  valve  ; and  all  of  the  wrists  are 
so  arranged  on  the  common  wrist-plate,  with  reference  to  their  levers,  that  they  act  like  cranks,  each  of 
which  vibrates  near  its  dead  point  or  point  of  slowest  throw,  and  therefore  imparts  but  little  movement 
to  the  valve  it  actuates,  while  that  valve  is  closed,  and  moves  with  its  fastest  throw,  and  therefore  im- 
parts the  greatest  movement  to  its  valve,  during  the  opening  and  closing  motions.  This  is  a substitute 
for  the  common  slide  valve  arrangement.  As  commonly  constructed,  a steam  valve  and  an  exhaust  valve 
are  rigidly  connected  together,  so  that  when  one  is  moved  the  other  is  forced  to  move  equally  with  it. 

The  whole  amount  of  force  consumed  in  unnecessarily  moving  a valve  while  closed,  is  expended  to  no 
good  purpose,  and  tends  to  increase  the  wear  of  the  engine.  The  new  device  therefore,  secures  two  ad- 
vantages : first,  it  saves  much  of  the  power  which  was  injuriously  expended  in  moving  the  closed  valve ; 
second , it  prevents  wire-drawing  or  waste  of  the  expansive  force  of  the  steam,  because  the  valves  are 
moved  with  increased  speed  while  opening  and  closing  their  ports. 

The  second  improvement  in  this  engine  consists  in  a method  of  automatic  regulation  of  the  steam  in 
its  passage  into  the  cylinder,  so  that,  by  means  of  the  steam  valves  only,  the  entire  expansive  force  of 
the  steam  is  saved  and  applied.  This  is  effected  by  combining  the  governor — all  its  sensibility  being 
completely  preserved — through  the  agency  of  stops  or  cams,  with  the  catches  that  liberate  the  steam 
valves  for  the  purpose  of  cutting  olf  the  flow  of  steam  into  the  cylinder. 

The  Corliss  engine  then,  is  a steam  engine  with  sliding  or  circular  valves,  and  with  a new  valve-gear 
adapted  to  perfect  automatic  regulation  and  to  the  saving  of  fuel.  The  regulation  in  this  engine  is  purely 
automatic,  and  practically  perfect,  as  it  acts  without  impairing  the  effect  of  the  steam.  The  common 
method  of  regulation  is  by  the  employment  of  a throttle  valve,  a kind  of  damper  in  the  steam  pipe,  de- 
scribed on  page  . This  is  connected  to  the  governor,  so  that  as  the  speed  of  the  engine  is  increased 
the  aperture  through  which  the  steam  passes  is  diminished ; by  thus  retarding  its  flow,  the  pressure  of 
the  steam  in  the  cylinder  is  diminished,  and  the  velocity  of  the  engine  is  consequently  checked.  The 
action  is  a continual  choking  of  the  engine,  which  is  increased  and  diminished  according  to  circum- 
stances, but  is  always  a tax  on  the  power.  The  loss  by  the  use  of  the  throttle-valve  is  universally  ac- 
knowledged to  be  very  serious.  Maudsley,  in  Great  Britain,  and  several  others,  succeeded  in  regulating 
by  varying  the  cut-off  by  the  hand  of  an  attendant,  but  the  adjustments  could  not  be  successfully  effect- 
ed by  the  governor  prior  to  this  invention,  as  the  power  required  to  change  the  parts  exhausted  the  sen- 
sibility of  the  governor  and  made  the  motion  very  irregular.  Even  the  slight  resistance  experienced  in 
turning  a throttle-valve — as  it  is  necessarily  effected  through  the  intervention  of  a steam-tight  stuffing 
box- — is  sufficient  to  affect  the  action  of  the  governor,  and  make  the  throttle  regulation  not  only  waste- 
ful, but  imperfect.  In  the  method  here  represented,  there  is  practically  no  resistance  to  the  rise  and  fall 
of  the  governor  balls,  and  the  engine  is  found  to  work  with  apparent  uniformity,  even  in  driving  such 
machinery  as  large  rolling  mills,  where  the  resistance  varies  suddenly  from  60  to  360  horse  power. 

In  the  engraving,  the  letters  c and  d as  before  observed,  indicate  the  steam  valves,  or  rather  indicate 
levers,  keyed  on  the  stems  of  such,  and  by  which  they  are  worked.  Near  the  extremity  of  each  rody 
and  k , is  provided  a suitable  hook  or  catch,  which  at  each  rocking  movement  of  the  plate,  a,  seizes  the 
respective  lever  c or  d,  and  opens  the  valve,  but  by  a movement  which  necessarily  presses  the  polished 
side  of  j or  k against  the  end  of  one  of  the  light  and  loosely  mounted  slides  n n.  This  contact,  as  the 
circular  motion  of  the  wrist  pin  a'  or  a?  continues,  aided  by  the  curvilinear  motion  of  the  extremity  of 
the  lever,  compels  the  hook  to  slip  off  and  release  its  valve,  which  is  then  immediately  closed  by  a 
weight  suspended  to  the  rod  r or  s.  The  slight  rods  or  slides  n n,  are  free  to  slip  endwise  until  their  op- 
posite extremities  press  against  the  side  of  the  pieces  o o,  mounted  for  the  purpose  on  the  rod  m of  the 
governor.  The  sides  of  o o are  inclined  slightly,  and  as  they  are  elevated  by  the  rise  of  the  governor 
balls,  they  urge  n n forward,  and  cause  the  hooks  to  detach  and  the  steam  valves  to  shut  at  an  earlier 
point  in  the  stroke.  When,  on  the  other  hand,  the  engine  inclines  to  run  too  slow,  and  the  balls  sink, 
the  slides  n n,  yield  to  the  slight  pressure  of  j and  k,  and  slip  back  until  they  are  in  contact  with  o,  and 
thus  more  steam  is  admitted  into  the  cylinder,  the  steam  valves  not  being  detached  until  a later  period 
in  the  stroke.  In  case  either  the  resistance  to  the  motion  of  the  engine  becomes  very  great,  or  the 
pressure  of  the  steam  becomes  very  slight,  the  slides  n n retreat  so  far  that  they  fail  to  detach  the  hooks 
and  the  steam  valves  consequently  remain  open  during  the  whole  stroke,  like  the  exhaust  valves. 

It  will  be  observed  that  in  this  engine  the  governor  nowhere  performs  any  labor,  and,  on  the  contrary, 
only  indicates  the  change  required  to  the  levers  which  move  the  valves.  This  does  not  task  its  powers : 
it  puts  forth  only  the  force  necessary  to  move  the  small  stops  nn.  This  movement  is  attended  with  the 
least  possible  friction,  and  the  stop  presents  absolutely  no  resistance  to  the  governor,  except  at  the  very 
instant  when  it  is  in  actual  contact  withy  or  k. 

In  puppet-valve  engines,  the  valves  must  be  started  from  their  seats  or  places  of  rest  at  the  moment  of 
opening  their  ports.  In  this  engine,  as  we  have  seen,  the  sliding  or  circular  valves  have  a rapid  mo- 
tion at  that  point,  analogous  to,  but  faster  than,  that  in  the  common  slide  valve  arrangement.  This  al- 
lows the  ports  to  be  uncovered  and  covered  very  rapidly,  without  involving  any  accompanying  sudden 
motions  and  concussions.  It  allows  the  valves  to  be  opened  very  widely  with  great  rapidity,  a point  of 
considerable  importance  in  the  motion  of  the  exhaust  valves,  as  it  is  always  desirable  to  discharge  the 
steam  as  freely  and  rapidly  as  possible  when  its  work  is  performed.  But  its  greatest  merit  lies  in  the 
dvet  that  it  prevents  a wire-drawing  of  steam  at  the  closing  of  the  steam  valves,  by  means  of  the  suck 


STAVE-DRESSING  MACHINE. 


653 


cienness  of  the  motion ; a result  which  cannot  he  obtained  in  an  engine  having  puppet- valves,  because 
the  descent  of  the  valves  by  gravity,  must,  in  such  engines,  be  very  moderate  at  the  termination  of  the 
motion,  to  prevent  their  slamming  on  their  seats. 

The  alternations  in  the  action  of  the  steam,  as  ordinarily  effected,  are  constantly  in  progress.  The 
opening  for  the  admission  of  the  steam  enlarges  gradually,  and  is  no  sooner  fully  and  freely  open  than 
it  commences  to  close : the  same  is  true  cf  the  opening  for  the  exhaust.  In  order  to  so  effect  the  op- 
erations of  admitting  and  discharging  the  steam  that  the  mean  of  each  shall  be  at  the  proper  time,  it  is  ne- 
cessary to  commence  a certain  time  in  advance.  Thus  the  steam  begins  to  enter  the  cylinder  to  produce 
a movement  of  the  piston  in  one  direction  before  the  previous  stroke  has  been  fully  completed,  and  con- 
sequently acts  for  a brief  period  in  the  wrong  direction,  or  as  a retarding  force ; and  subsequently  begins 
to  escape,  and  to  lose  its  effect  before  the  piston  has  completed  its  proper  movement.  These  imperfec- 
tions in  the  action  of  the  steam  are  unavoidable  in  the  common  varieties  of  the  steam  engine,  whether 
using  slide  valves  or  puppet  valves,  but  are  completely  avoided  in  this  style  of  engine ; the  steam  being 
admitted  and  discharged  very  freely,  and  at  the  moment  the  piston  is  at  the  ends  of  the  stroke.  The 
construction  allows  of  the  adjusting  of  the  valve  motion  so  as  to  receive  and  discharge  a little  in  ad- 
vance or  a little  behind  this  period  if  preferred,  and  in  fact,  these  engines  are  frequently  adjusted  in  va- 
rious conditions  in  this  respect ; but  the  necessity  for  commencing  either  operation  in  advance,  or  giving 
“lead”  to  the  valves,  is  entirely  removed  by  the  rapidity  with  which  it  is  effected. 

Perfection  of  economy  in  the  use  of  steam  is  to  admit  it  freely  at  a high  pressure  at  the  moment  the 
piston  commences  its  stroke,  and  allow  it  to  follow  at  full  pressure  through  such  a fraction  of  the  stroke 
that  the  subsequent  expansion  shall,  during  the  remainder  of  the  stroke,  reduce  it  to  the  lowest  pressure 
at  which  it  can  be  useful.  A certain  amount  of  pressure,  varying  from  one  to  three  or  four,  pounds 
is  always  required  to  overcome  the  friction  of  the  engine.  Whenever  steam  is  discharged  from  a cylin- 
der at  a higher  effective  pressure  than  this,  it  proves  that  there  is  still  power  remaining  in  it  which 
might  have  been  utilized  by  a better  arrangement  and  proportion  of  the  engine.  It  might  seem  reason- 
able to  suppose  that  the  gain  of  effect  due  to  expansion,  explained  on  page  , may  be  increased  in- 
definitely by  increasing  the  initial  or  boiler  pressure,  and  cutting  off  at  a proportionally  early  period  in 
the  stroke ; but  there  are  other  considerations,  due  to  the  strains  on  the  parts,  the  friction  of  the  surfaces, 
and  the  leakage  of  steam,  which  limit  it.  In  the  Corliss  engine,  the  average  expansion  allowed  is  that 
found  most  economical  in  practice. 

It  should  be  premised  that  it  requires  a higher  temperature , but  only  a very  little  greater  amount,  of  heat, 
to  evaporate  a given  quantity  of  water  at  a high  pressure  than  at  a low.  Recent  elaborate  scientific 
experiments,  as  also  the  results  of  general  experience,  assure  us  that  there  is  a little,  and  but  a little 
difference  in  the  amount  of  fuel  consumed,  in  evaporating  a cubic  foot  of  water  at  100  pounds  pressure 
or  at  1 pound  pressure,  while  the  power  derivable  is  much  greater  from  the  steam  of  highest  pressure, 
used  expansively  as  above  described.  The  actual  cost  for  fuel  to  obtain  any  given  power,  is  a subject 
which  has  not  received  the  attention  it  deserves.  The  following  condensed  tabular  statement  indicates 
the  actual  performances  of  these  engines.  The  data  are  from  large  mills  in  ordinary  and  constant  use, 
and  in  this  respect  differ  very  widely  from  experiments  conducted  for  short  periods  and  with  miniature 
apparatus, — good  common  engines  had  been  previously  employed  in  each. 


The  quantities  marked  with  an  asterisk  (*)  indicate  the  amount  used  for  heating  and  dressing  in  addition  to 
that  required  for  power. 


Establishment. 

Horse  power 
by  Indicator. 

lbs.  Coni  consumed  per 
day  with  Corliss  Engine. 

lbs.  Coal  per  Morse 
per  Hour. 

* Ounces  Coal  per 
day  per  Spindle. 

lbs.  Coal  consumed 
with  former  Engines. 

Atlantic  M l,  Prov- 
idence R.  I. 

1 

o 

Cl 

6,000 

T88 

3-942 

— 

Bartlett  M’lsNew- 
buryport,  Mass. 

200 

6,000* 

. 2-5* 

5-690* 

9,250* 

James  Mills,  do. 

190 

5,690* 

2 5* 

5-27* 

10,483* 

Globe  Mills,  do. 

294 

8,800* 

2-49* 

— 

11,000* 

Crocker  & Bro’s, 
(Rolling  Mill,) 
Taunton,  Mass. 

60  to  860 

4,000 

— 

10,000 

STAVE-DRESSING  MACHINE.  Fig.  3362  gives  only  a representation  of  this  machine  in  the 
manner  of  looking  down  upon  the  face  of  the  frame,  therefore  the  geering  underneath  cannot  be  seen ; 
but  from  this  vertical  view  a good  mechanic  will  be  able  to  trace  the  relation  of  the  different  parts,  and 
perceive  the  beauties  of  the  whole  machine  and  its  adaptations  to  the  purpose,  so  much  to  be  desired 
and  so  essential  to  the  great  and  rising  trade  of  American  cooperage. 

A A A is  the  frame  ; K is  the  iron  bed-plate  represented  by  the  dark  shading.  B represents  the  large 
knife  or  cutting-roller,  somewhat  hid  by  the  belt  which  drives  it  from  the  power-roller  D.  C C are 
friction-rollers,  edged,  as  it  were,  to  run  upon  a rail  to  keep  the  large  knife-roller  steady,  and  underneath 
is  another  for  the  same  purpose,  all  three  set  equidistant,  like  at  the  points  of  a triangle.  E H are  rollers 
connected  with  another  belt  to  drive  the  small  knife-roller  I.  G is  a driving-belt  on  an  idle  roller  near 
the  motion  or  drive  pulley  F.  N N are  pulleys  which  are  driven  by  a cross  rope-belt  to  drive  a hori- 
zontal shaft,  on  which  is  the  notched  wheel  which  moves  the  two  vertical  shafts  or  feeding-rollers  (two 
biting  wheels)  a a,  and  which  are  now  represented  as  feeding  a stave  into  the  knife-rollers.  E is  a spiral 
spring  which  makes  the  feeders  accommodate  themselves  to  the  bendings  of  the  staves,  b is  a rest  on  a 
straight  line  which  keeps  the  stave  up  to  the  other  two  smooth  rollers  with  springs  cd,  which  act  as 
subordinate  to  the  biting  feeders.  C is  another  rest  and  roller  to  keep  firm  the  small  cutting-roller  T, 
between  which  and  the  large  knife-roller  B the  stave  passes  and  comes  out  shaved  through  the  centre 


G54 


STAVE- JOINTING  MACHINE. 


of  B,  tlie  large  cutting-roller,  -which  is  open.  L is  the  lever  or  handle  to  set  the  feed-geer  in  motion,  bj 
lifting  the  wheel  which  drives  the  feed-shafts. 

The  nature  of  this  invention  and  improvement  consists  in  combining  and  arranging  two  revolving  rings 
or  wheels  having  cutters  on  their  opposing  surfaces  uext  each  other,  for  shaving  the  stave  transversely 
on  both  sides  at  once,  producing  a stave  the  cross-section  of  which  is  the  segment  of  a circle,  the  diam- 
eter of  which  is  to  be  greater  than  the  diameters  of  the  wheels,  and  the  curve  of  the  stave  being  variable 
at  pleasure  for  all  kinds  of  casks.  The  position  of  the  whole  geering  can  be  changed  to  suit  the  angle 
of  the  stave’s  curvature,  as  the  stave  moves  on  the  cutters  it  being  the  hvpothenuse  of  a right-angled 
triangle  formed  by  the  parallel  lines  on  which  the  cutters  are  placed.  The  whole  machine  is  constructed 
on  the  principle  of  considering  a circle  (for  the  curvature)  to  be  a regular  polygon  of  an  indefinite  num- 
ber of  sides,  the  sum  of  the  sides  being  the  perimeter  of  the  circle. 


3302. 


A patent  was  granted  for  this  machine  to  Judson  <fc  Pardee,  New  Haven,  Conn.  It  cannot  but  be  >1 
great  benefit  to  our  country,  as  it  destroys  at  once  the  rough,  slavish  work  of  cooperage,  and  lets  the 
cooper  occupy  his  hands  with  the  most  light  and  easy  parts  of  his  trade. 

STAVE-JOINTING-  MACHINE.  Fig.  3363  is  an  engraving  of  a stave  jointer,  the  invention  of  Mr. 
H.  Law,  of  Wilmington,  North  Carolina,  who  has  taken  measures  to  secure  a patent  for  the  same.  Its 
utility,  nature,  and  mode  of  operation  will  be  fully  understood  by  the  following  description : 

AAA,  frame.  B,  lever,  which  moves  the  frame  L L,  together  with  the  saw  and  roller  D,  which  are 
all  attached  to  frame  L L.  C,  lever,  by  means  of  which  lever  B is  moved.  D D,  concave  rollers  under 
which  the  stave  passes.  E E E E,  standards  to  support  D D.  F F,  circular  saws,  standing  in  a raking 
position,  verging  in  opposite  directions,  so  as  to  give  the  proper  bevel  to  the  edges  of  the  stave.  GG 
G G,  raised  pieces  over  which  the  stave  passes,  which  raised  pieces  together  with  the  concave  rollers 
D D form  throats  or  slots  just  the  thickness  of  the  stave,  and  through  which  the  stave  is  made  to  pass 
H,  a guide-piece  to  conduct  the  stave  to  the  second  saw.  I,  a light  spring  to  press  the  stave  against  the 
guide-piece  H.  J,  the  end  of  the  feed-chain  which  connects  with  the  dresser.  K K,  dogs  or  hooks,  at- 
tached to  the  endless  chain  and  traversing  in  the  curved  slot  S S S to  carry  forward  the  stave — the  chain 


is  underneath,  and  does  not  appear  in  the  engraving  except  at  J.  L L,  movable  frame  that  supports 
the  saw,  and  that  is  attached  to  and  acted  upon  by  lever  B to  adjust  the  saw  to  the  width  of  the  stave. 
M,  journal-box.  P P,  pulleys  to  drive  the  circular  saw.  0,  pawls,  or  hold-fasts,  to  lever  C.  N N,  weight 

ani  rope  that  move  lever  B.  Q Q,  index  beds.  R,  curved  piece  attached  to  lever  B dotted 

curved  line  ranging  with  the  saw,  and  governing  the  feed  of  stave  on  that  side. 

Operation.— The  stave  is  deposited  by  the  machine  on  the  floor  of  the  jointer,  and  is  placed  by  hand 
With  the  back  of  the  stave  up,  with  one  edge  on  the  dotted  lines,  being  the  proper  position  for  that  edge 


STEAM. 


655 


ro  be  jointed  by  the  first  saw,  and  with  a single  glance  of  the  eye  on  the  index  lines  on  the  near  side  the 
tender  can  see  what  width  the  stave  will  bear;  if  it  is  described,  for  instance,  by  the  first  line,  the  lever 
0 is  immediately  placed  on  the  corresponding  first  line,  and  held  fast  by  pulley  O,  or  if  the  stave  is  of 
some  other  width  it  is  readily  seen,  and  the  lever  C placed  in  the  proper  position ; but  it  is  not  conve- 
nient that  the  saw  should  take  that  position  immediately,  therefore  lever  B is  still  held  fast  in  its  former 
position  by  ratchets  underneath  and  attached  to  circular  piece  It,  which  circular  piece  is  attached  to  and 
traverses  with  lever  B.  There  is  a ketch  attached  to  the  frame  of  the  machine,  which  is  pressed  into 
r-he  ratchets  and  holds  fast  lever  B.  This  hold-fast  is  tripped  by  one  of  the  dogs  passing  through  a 
throat  under  the  floor  at  the  proper  time,  when  the  weight  N immediately  shifts  lever  B to  lever  C,  and 
places  the  saw  in  its  proper  position.  The  dog  that  carries  the  stave  forward  traverses  in  a curved  line 
corresponding  to  the  bilge  or  taper  of  the  stave,  giving  to  the  stave  its  taper,  and  both  saws  standing  in 
a raking  position  corresponding  to  the  bevel  of  the  stave,  gives  to  the  stave  its  proper  bevel,  the  stave 
passing  between  the  raised  pieces  GGGG  and  the  concave  roller  1)  D,  which  together  form  a slot  just 
the  thickness  of  a stave,  must  of  necessity  bring  every  crook  or  twist  fair  to  the  saw,  jointing  to  corre- 
spond with  the  crooks  and  twists,  and  making  a more  perfectly  shaped  stave  than  can  possibly  be  done 
bv  the  hand.  The  staves  are  pressed  by  springs  (which  do  not  appear  in  the  engraving)  up  against  the 
rollers  D D,  and  as  the  rollers  are  more  concave  than  the  stave  is  convex,  one  edge  of  a narrow  stave 
is  forced  into  this  concavity  and  presents  an  edge  less  bevelling  to  the  saw  than  a wide  stave  does, 
so  that  without  any  alteration  of  machinery  the  bevel  is  made  to  correspond  to  the  width  of  the  stave ; 
to  accomplish  this  with  the  second  saw  the  concave  roller,  together  with  the  near  standard  E and  raised 
piece  Gr,  is  attached  to  the  frame  and  shifts  with  the  saw. 

STEAM.  The  elastic  fluid  into  which  water  is  converted  by  the  continued  application  of  heat. 

All  liquids  whatever,  when  exposed  to  a sufficiently  high  temperature,  are  converted  into  vapor. 
The  mechanical  properties  of  vapor  are  similar  to  those  of  gases  in  general.  The  property  which  is 
most  important  to  be  considered,  in  the  case  of  steam,  is  the  elastic  pressure.  When  a vapor  or  gas  is 
contained  in  a close  vessel,  the  inner  surface  of  the  vessel  will  sustain  a pressure  arising  from  the  elas- 
ticity of  the  fluid.  This  pressure  is  produced  by  the  mutual  repulsion  of  the  particles,  which  gives  them 
a tendency  to  fly  asunder,  and  causes  the  mass  of  the  fluid  to  exert  a force  tending  to  burst  any  vessel 
within  which  it  is  confined.  This  pressure  is  uniformly  diffused  over  every  part  of  the  surface  of  the  ves- 
sel in  which  such  a fluid  is  contained : it  is  to  this  quality  that  all  the  mechanical  power  of  steam  is  due. 

To  render  the  chief  properties  of  steam  intelligible,  it  will  only  be  necessary  to  explain  the  phenomena 
which  attend  the  conversion  of  water  into  vapor  by  the  continued  application  of  heat,  under  the  various 
circumstances  of  external  pressure  which  present  themselves  in  the  processes  of  nature  and  art. 

Let  A B,  Fig.  3364,  be  a tube  or  cylinder,  the  magnitude  of  whose  base  is  a square  inch,  and 
let  a piston  move  steam-tight  in  it ; let  it  be  imagined  that  under  this  piston,  in  the  bottom  of 
the  cylinder,  there  is  an  inch  depth  of  water,  which  will  therefore  be  in  quantity  a cubic 
inch  ; let  the  piston  be  counterbalanced  by  a weight  W acting  over  a pulley,  which  shall 
be  sufficient  to  counterpoise  the  weight  of  the  piston  and  its  friction  in  the  cylinder ; and 
let  the  weight  W be  so  arranged  that  from  time  to  time  its  amount  may  be  diminished  to 
any  required  extent.  Under  the  circumstances  here  supposed,  the  piston  being  in  contact 
with  the  water,  and  all  air  being  excluded  from  beneath  it,  it  will  be  pressed  down  by 
the  weight  of  the  atmosphere,  which  we  shall  assume  to  be  14f  lbs.  Let  it  be  also  sup- 
posed that  a thermometer  is  placed  in  the  water  under  the  piston,  and  that  the  tube  A B 
is  transparent,  so  that  the  indications  of  the  thermometer  may  be  observed.  The  temper- 
ature of  the  water  under  the  piston  being  reduced  to  that  of  melting  ice,  which  is  32°  of 
the  common  thermometer,  let  the  flame  of  a lamp  be  applied  under  the  tube,  and  let  the 
time  of  its  application  be  noted.  If  the  thermometer  be  now  observed,  it  will  be  seen  slowly  and  grad- 
ually to  indicate  an  increasing  temperature  of  the  water,  the  piston  maintaining  its  position  in  contact 
with  the  water  unchanged.  This  augmentation  of  the  temperature  will  continue  until  the  thermometer 
indicates  the  temperature  of  212°.  Let  the  time  be  then  noted.  It  will  be  found  that  after  that  epoch, 
the  water  will  cease  to  increase  in  temperature,  notwithstanding  the  continued  application  of  the  lamp, 
the  thermometer  not  rising  above  212°.  But  another  effect  will  begin  to  be  manifested;  the  piston 
will  be  observed  gradually  to  rise,  leaving  a space  apparently  vacant  between  it  and  the  water.  The 
depth  of  the  water  will,  however,  be  at  the  same  time  gradually  diminished,  and  the  diminution  of  its 
depth  will  be  found  to  bear  constantly  the  same  proportion  to  the  ascent  of  the  piston.  This  propor- 
tion will  render  the  circumstances  here  supposed  to  be  that  of  1 100  to  1.  If  the  application  of  the 
lamp  be  continued,  and  the  tube  have  sufficient  length,  the  water  will,  after  the  lapse  of  a certain  time, 
altogether  disappear  from  the  bottom  of  the  tube ; and  when  that  occurs,  the  piston  will  have  risen  to 
the  height  of  1700  inches,  being  1700  times  the  original  depth  of  the  water. 

The  tube  will  now,  to  all  appearance,  be  empty  ; but  if  the  apparatus  were  weighed,  it  would  be 
found  to  have  the  same  weight  as  at  the  commencement  of  the  experiment.  The  water,  therefore,  must 
Btill  be  contained  in  the  tube,  though  it  has  assumed  an  invisible  form.  To  demonstrate  its  presence,  let 
the  lamp  be  removed ; immediately  the  piston  will  begin  to  descend,  and  the  inner  surface  of  the  tube 
will  be  covered  with  a dew,  which  speedily  increasing,  will  fall  to  the  bottom  in  drops  of  water.  The  pis- 
ton meanwhile  will  continue  to  move  downwards,  sweeping  before  it  the  water  from  the  sides  of  the  tube  ; 
and  at  length  will  recover  its  first  position,  having  under  it,  as  at  the  beginning,  a cubic  inch  of  water. 

In  the  above  process,  the  elevation  of  the  piston  is  produced  by  tbe  elastic  force  of  the  steam,  into 
which  the  water  was  gradually  converted  by  the  lamp.  The  space  between  the  piston  and  the  water 
during  its  ascent,  though  apparently  empty,  was  filled  with  steam;  which,  like  air  and  most  other 
gases,  is  a colorless  and  invisible  fluid.  The  proportion  of  the  elevation  of  the  piston  to  the  diminution 
of  depth  of  the  water  being  1700  to  1,  proves  that  the  water  in  passing  into  steam  increases  its  volume 
in  that  proportion.  When  the  water  altogether  disappeared,  the  height  of  the  piston  from  the  bottom 
of  the  tube  was  1700  inches;  and  as  the  tube  under  the  piston  was  then  filled  with  the  steam  into 


3364. 


656 


STEAM. 


which  the  water  had  been  converted,  it  is  apparent  that  the  cubic  inch  of  water,  in  this  case,  was  con- 
verted into  1700  inches  of  steam. 

The  pressure  of  the  atmosphere  above  the  piston  was,  in  this  case,  overcome  by  the  elastic  force  o.f 
the  steam,  and  the  piston,  bearing  that  pressure  upon  it,  was  raised  to  a height  of  1700  inches.  In  the 
evaporation,  therefore,  of  this  cubic  inch  of  water,  a mechanical  force  has  been  evolved  equivalent  tc 
14J  lbs.  raised  to  the  height  of  1700  inches. 

From  the  moment  at  which  the  water  began  to  be  converted  into  steam  the  thermometer,  having 
then  attained  212°,  ceased  to  rise.  Nevertheless,  the  application  of  the  lamp  was  continued,  and  there- 
fore the  same  quantity  of  heat  per  minute  was  still  supplied  to  the  water.  Since  the  water  did  not 
increase  in  temperature,  it  may  be  asked  what  became  of  this  continued  supply  of  heat  received  from 
the  lamp  ? It  may  be  said  that  it  was  imparted  to  the  steam  into  which  the  water  was  converted ; but 
if  the  thermometer  were  raised  out  of  the  water,  and  held  in  the  steam  between  the  water  and  the  pis- 
ton, it  would  still  indicate  the  same  temperature  of  212°.  We  thus  arrive  at  the  extraordinary  and 
unexpected  fact,  that  notwithstanding  a large  supply  of  heat  imparted  to  water  during  its  evaporation, 
that  heat  is  sensible  neither  in  the  water  itself  nor  in  the  vapor  into  which  the  water  is  converted. 

The  quantity  of  heat  which  is  thus  absorbed  in  converting  water  into  steam  is  easily  determined,  the 
interval  of  time  being  noted  which  elapsed  between  the  first  application  of  the  lamp  and  the  moment 
at  which  the  thermometer  ceased  to  rise.  Let  us  suppose  that  interval  to  be  an  hour ; the  interval  be- 
ing also  noted  between  the  moment  the  thermometer  ceases  to  rise  and  the  process  of  evaporation 
begins,  and  the  moment  at  which  the  last  particle  of  water  disappears  from  the  bottom  of  the  tube  and 
the  evaporation  is  completed,  it  will  be  found  that  this  interval  is  54  hours ; and  in  general,  whatever 
may  be  the  length  of  time  necessary  to  raise  the  temperature  of  the  water  from  32°  to  212°,  5|  times 
that  interval  will  be  necessary  for  the  same  source  of  heat  to  evaporate  the  same  quantity  of  water. 
It  follows,  therefore,  that  to  evaporate  water  under  a pressure  of  14f  pounds  per  square  inch  requires 
5J  times  as  much  heat  as  is  necessary  and  sufficient  to  raise  the  same  water  from  32°  to  212°. 

Since  the  difference  between  212°  and  32°  is  180°,  and  since  5-J-  times  180°  is  990°,  it  follows  that 
to  convert  the  water  into  steam  after  it  has  attained  the  temperature  of  212°,  as  much  heat  must  be 
supplied  to  it  as  would  be  sufficient,  if  it  were  not  evaporated,  to  raise  it  990°  higher.  The  heat  thus 
absorbed  in  evaporation,  and  not  sensible  to  the  thermometer,  is  said  to  be  latent  in  the  steam ; and 
the  phenomena  which  have  been  just  described  form  the  foundation  of  the  whole  theory  of  latent  heat. 
That  this  large  quantity  of  heat  is  actually  contained  in  the  steam,  though  not  sensible  to  the  thermo- 
meter, admits  of  easy  demonstration,  by  showing  that  it  may  be  reproduced  by  converting  the  steam 
into  water.  If  a cubic  inch  of  water,  in  the  form  of  steam  at  the  temperature  of  212°,  be  introduced 
into  the  same  vessel  with  5J  cubic  inches  of  water  at  the  temperature  of  32°,  the  steam  will  be  imme- 
diately converted  info  water;  the  temperature  of  the  inches  of  ice-cold  water  will  be  raised  to  212°, 
and  there  will  be  found  in  the  vessel  6^-  cubic  inches  of  water  at  212°.  Thus,  while  the  steam,  in  re- 
assuming the  liquid  form,  has  lost  none  of  its  temperature,  it  has  nevertheless  given  up  as  much  heat 
as  has  raised  5^-  cubic  inches  of  water  from  32°  to  212°.  It  is  therefore  demonstrated  that  this  quan- 
tity of  heat  was  actually  in  the  steam ; and  that  it  was  its  presence  there  in  the  latent  state,  by  some 
agency  not  yet  explained,  that  conferred  upon  the  water  in  the  vaporous  form  the  property  of  elasticity. 

We  have  here  supposed  that  the  pressure  under  which  the  water  in  the  tube  was  evaporated  was 
the  mean  pressure  of  the  atmosphere,  or  14  j lbs.  per  square  inch.  Let  us  now  suppose  that  the  piston 
resting  on  the  water  is  loaded  with  a force  of  14f  lbs.,  besides  the  pressure  of  the  atmosphere,  which 
may  be  done  by  taking  14  J lbs.  from  the  counterpoise  W.  If  the  same  process  be  followed  as  before, 
it  will  now  be  found  that  the  thermometer  will  not  cease  to  rise  when  it  has  attained  212°  ; nor  will 
the  piston  then  begin  to  ascend.  The  thermometer  will,  on  the  other  hand,  continue  to  rise  until  it  has 
attained  250°.  It  will  then,  as  in  the  former  case,  cease  to  rise ; the  piston  will  ascend,  and  the  water 
will  begin  to  be  converted  into  steam ; the  proportion,  however,  between  the  ascent  of  the  piston  and 
the  diminished  depth  of  the  water,  or,  in  other  words,  between  the  volume  of  steam  produced  and  the 
volume  of  water  producing  it,  instead  of  being  1700  to  1,  will  now  be  about  930  to  1,  being  little  more 
than  half  the  former  proportion.  The  force  against  which  the  elasticity  of  the  steam,  in  the  present 
case,  acts,  is  294  lbs. ; and  this  force  is  raised  about  930  inches  by  the  evaporation  of  a cubic  inch  of 
water.  In  the  former  case,  a force  of  14J  lbs.,  being  half  the  present  force,  was  raised  to  1700  inches 
by  the  evaporation  of  the  same  quantity  of  water.  If  the  double  force,  instead  of  being  raised  930 
inches,  had  been  raised  only  850  inches,  or  half  the  first  elevation,  then  the  mechanical  effect  evolved 
would  in  both  cases  be  precisely  the  same,  the  double  resistance  being  raised  through  only  half  the 
space ; but  the  actual  height  through  which  the  double  resistance  is  raised  being  930  inches  instead  of 
850,  a greater  mechanical  effect  is  produced  in  the  one  case  than  in  the  other,  in  the  proportion  of  930 
to  850,  being  an  advantage  on  the  part  of  the  steam  of  greater  pressure  of  about  8 per  cent. 

If  the  pressure  under  which  the  evaporation  is  produced  were  further  varied,  it  would  be  found  that 
with  every  increase  of  pressure  the  temperature  at  which  the  evaporation  would  commence  would  be 
augmented,  and  that  with  every  diminution  of  pressure  that  temperature  would  be  diminished.  It 
would  be  also  found  that  the  volume  of  steam  produced  by  a cubic  inch  of  water  would  be  less  with 
every  increase  of  pressure  under  which  the  evaporation  is  made ; and  that  the  diminution  of  volume 
would  be  nearly,  but  not  in  quite  so  great  a proportion,  as  the  increase  of  pressure.  In  like  manner,  if 
the  pressure  be  diminished,  the  volume  of  steam  produced  by  a cubic  inch  of  water  will  be  augmented 
in  nearly,  but  not  quite  so  great  a proportion,  as  that  of  the  diminution  of  pressure.  From  all  this,  it 
obviously  follows  that  the  mechanical  effect  evolved  by  the  evaporation  of  a given  volume  of  water 
under  different  pressures  is  very  nearly  the  same ; greater  pressures,  however,  having  a slight  advan- 
tage over  lesser  ones. 

It  has  been  seen  that  14f  lbs.  are  raised  to  a height  of  1700  inches  by  the  evaporation  of  a cubic 
inch  of  water  under  the  pressure  of  14J  lbs.  per  square  inch.  Now,  1700  inches  are  nearly  equal  tc 
142  feet ; and  14  j lbs.  raised  142  feet  is  equivalent  to  142  times  14|  lbs.  raised  one  foot,  which  is  eauaJ 


STEAM. 


657 


to  very  nearly  2100  lbs.  raised  one  foot.  To  use  round  numbers,  it  may  then  be  stated,  that  by  thi 
evaporation  of  a cubic  inch  of  water  a mechanical  force  is  produced  equivalent  to  a ton  weight  raised  a 
foot  high ; and  that  this  force  is  very  nearly  the  same,  whatever  be  the  temperature  or  pressure  unde; 
which  the  evaporation  takes  place. 

In  the  following  table,  calculated  by  Dr.  Lardner,  and  given  by  him  in  the  Appendix  to  the  7th  edi- 
tion of  his  work  on  the  Steam-Engine,  is  exhibited  the  temperatures  at  which  water  is  evaporated  undei 
different  pressures,  the  volume  into  which  the  water  expands  by  evaporation,  the  mechanical  eftec; 
evolved  expressed  in  lbs.  raised  one  foot. 


1 

Total  pressure 
in  pounds  per 
square  inch. 

Correspond- 
ing Tempera- 
ture. 

Volume  of  the 
steam  com- 
pared to  the 
volume  of  the 
water  that  has 
produced  it. 

Mechanical  ef- 
fect of  a cubic 
inch  of  water 
evaporated,  in 
pounds  raised 
one  foot. 

Total  pressure 
in  pounds  per 
square  inch. 

Correspond- 
ing Tempera- 
ture. 

Volume  of  the 
steam  com- 
pared to  the 
volume  of  the 
water  that  has 
produced  it. 

Mechanical  ef- 
fect of  a cubic 
inch  of  water 
evaporated,  in 
pounds  raised 
one  foot. 

i 

102-9 

20868 

1739 

58 

292-9 

484 

2339 

2 

1261 

10874 

1812 

59 

294-2 

477 

2343 

3 

141-0 

7437 

1859 

60 

295'6 

470 

2347 

4 

152-3 

5685 

1895 

61 

296-9 

463 

2351 

5 

161-4 

4617 

1924 

62 

298-1 

456 

2355 

6 

169-2 

3897 

1948 

63 

299-2 

449 

2359 

7 

175-9 

3376 

1969 

64 

300-3 

443 

2362 

8 

182-0 

2983 

1989 

65 

301-3 

437 

2365 

9 

187-4 

2674 

2006 

66 

302-4 

431 

2369 

10 

192-4 

2426 

2022 

67 

303-4 

425 

2372 

11 

197-0 

2221 

2036 

68 

304-4 

419 

2375 

12 

201-3 

2050 

2050 

69 

305-4 

414 

2378 

13 

205-3 

1904 

2063 

70 

306-4 

408 

2382 

14 

209-1 

1778 

2074 

71 

307-4 

403 

2385 

15 

212-8 

1669 

2086 

72 

308-4 

398 

2388 

16 

216-3 

1573 

2097 

73 

309-3 

393 

2391 

17 

219-6 

1488 

2107 

74 

310-3 

388 

2394 

18 

222*7 

1411 

2117 

75 

311-2 

383 

2397 

19 

225-6 

1343 

2126 

76 

312-2 

379 

2400 

20 

228-5 

12S1 

2135 

77 

313-1 

374 

2403 

21 

231-2 

1225 

2144 

78 

314-0 

370 

2405 

22 

233-8 

1174 

2152 

79 

314-9 

366 

2408 

23 

236-3 

1127 

2160 

80 

315-8 

362 

2411 

24 

238-7 

1084 

2168 

81 

316-7 

358 

2414 

25 

2410 

1044 

2175 

82 

317-6 

354 

2417 

26 

243-3 

1007 

2182 

83 

318-4 

350 

2419 

27 

245'5 

973 

2189 

84 

3193 

346 

2422 

28 

247  6 

941 

2196 

85 

320-1 

342 

2425 

29 

249-6 

911 

2202 

86 

- 32T0 

339 

2427 

30 

251-6 

883 

2209 

87 

321-8 

335 

2430 

31 

253'6 

857 

2215 

88 

322-6 

332 

2432 

32 

255'5 

833 

2221 

89 

323-5 

328 

2435 

33 

257-3 

810 

2226 

90 

324-3 

325 

2438 

34 

259-1 

788 

2232 

91 

325-1 

322 

2440 

35 

260  9 

767 

2238 

92 

325-9 

319 

2443 

36 

262-6 

743 

2243 

93 

326-7 

316 

2445 

37 

264-3 

729 

2248 

94 

327-5 

313 

2448 

38 

265'9 

712 

2253 

95 

328-2 

310 

2450 

39 

267-5 

695 

2259 

96 

329-0 

307 

2453 

40 

269-1 

679 

2226 

97 

329-8 

304 

2455 

41 

270-6 

664 

2268 

98 

330-5 

801 

2457 

42 

272-1 

649 

2273 

99 

33T3 

298 

2460 

43 

273-6 

635 

2278 

100 

332-0 

295 

2462 

44 

275-0 

622 

2282 

110 

339-2 

271 

2486 

45 

276-4 

610 

2287 

120 

345-8 

251 

2507 

46 

277-8 

598 

2291 

130 

352-1 

233 

2527 

47 

279-2 

586 

2296 

140 

357-9 

218 

2545 

48 

280-5 

575 

2300 

150 

363-4 

205 

2561 

49 

281-9 

564 

2304 

160 

368-7 

193 

2577 

50 

283-2 

654 

2308 

170 

373-6 

183 

2593 

51 

284-4 

544 

2312 

180 

378-4 

174 

2608 

52 

285-7 

534 

2316 

190 

382-9 

166 

2622 

53 

286-9 

525 

2320 

200 

387-3 

158 

2636 

54 

288-1 

516 

2324 

210 

391-5 

151 

2650 

55 

289-3 

508 

2327 

220 

395-5 

145 

2663 

56 

290-5 

500 

2331 

230 

399-4 

140 

2675 

67 

291-7 

492 

2335 

240 

403-1 

134 

2687 

You  II.— 42 


558 


STEAM. 


From  what  has  been  above  explained,  it  is  apparent  that  the  quantity  of  sensible  heat  in  steam  k> 
augmented  with  every  increase  of  pressure  under  which  the  evaporation  takes  place  ; but  if  the  interval 
ef  time  be  observed  which  elapses  between  the  first  application  of  the  lamp  to  the  ice-cold  water  in 
the  experiment  above  described,  and  the  moment  at  which  the  last  particle  of  water  disappears  by 
evaporation  from  the  bottom  of  the  tube,  it  will  be  found  that  this  interval  is  exactly  the  same,  what- 
ever be  the  temperature  or  pressure  under  which  the  evaporation  takes  place.  It  follows,  therefore, 
that  the  actual  quantity  of  heat  necessary  to  convert  ice-cold  water  into  steam  is  the  same,  whatever 
be  the  pressure  of  the  steam ; but  as  the  temperature  of  steam  increases  and  diminishes  as  the  pressure 
is  increased  or  diminished,  it  follows  that  this  given  quantity  of  heat  is  differently  distributed  between 
sensible  and  latent  heat  in  steam  of  different  pressures.  As  the  pressure  is  increased  the  sensible  heat 
is  augmented,  and  the  latent  heat  undergoes  a corresponding  diminution,  and  vice  versa.  The  sum  of 
the  sensible  and  latent  heats  is,  in  fact,  a constant  quantity;  the  one  being  always  increased  at  the  ex- 
pense of  the  other.  It  has  been  shown  that  in  converting  water  at  32°  of  temperature,  and  under  a 
pressure  of  14  J lbs.  per  square  inch,  it  was  necessary  first  to  give  it  180°  additional  sensible  heat,  and 
afterwards  990°  of  latent  heat,  the  total  heat  imparted  to  it  being  1170°.  Such,  then,  is  the  actual 
quantity  of  heat  which  must  be  imparted  to  ice-cold  water  to  convert  it  into  steam.  The  actual  tem- 
perature to  which  water  would  be  raised  by  the  heat  necessary  to  evaporate  it,  if  its  evaporation  could 
oe  prevented  by  confining  it  in  a close  vessel,  will  be  found  by  adding  32°  to  1170°.  It  may,  there- 
fore, be  stated  that  the  heat  necessary  for  the  evaporation  of  ice-cold  water  is  as  much  as  would  raise 
it  to  the  temperature  of  1202°,  if  its  evaporation  were  prevented.  If  the  temperature  of  red-hot  iron 
be,  as  is  supposed,  about  800°,  and  that  all  bodies  become  incandescent  at  the  same  temperature,  it 
follows  that  to  evaporate  water  it  is  necessary  to  impart  to  it  400°  more  heat  than  would  be  sufficient 
to  render  it  red-hot  if  its  evaporation  were  prevented.  As  the  mechanical  effect  evolved  by  water 
evaporated  at  all  pressures  is  nearly  the  same,  and  as  the  quantity  of  heat  necessary  to  effect  that 
evaporation  is  also  the  same,  it  follows  that  the  same  quantity  of  fuel  employed  in  the  evaporation  of 
water  is  productive  of  very  nearly  the  same  mechanical  effect,  whatever  be  the  pressure  of  the  steam. 

Since  the  heat  imparted  to  water  in  evaporation  is  necessary  to  sustain  it  in  the  form  of  vapor,  it 
follows  that  if  any  portion  of  that  heat  be  taken  from  it,  the  steam  will  not  be  lowered  in  temperature, 
but  a portion  of  it  will  be  reconverted  into  water ; a process  which  is  called  condensation.  To  illustrate 
this,  let  us  suppose  the  tube  AB  to  be  filled  with  steam  of  212°  of  temperature,  produced  from  a 
cubic  inch  of  water  evaporated  under  the  pressure  of  1-4  J lbs.  on  the  piston.  If,  by  the  application  of 
external  cold,  or  any  other  means,  a quantity  of  heat  be  extracted  from  this  steam,  say  as  much  as 
would  be  sufficient  to  evaporate  the  tenth  of  a cubic  inch  of  water,  then  a tenth  part  of  the  steam  in 
the  tube  will  be  condensed  and  deposited  in  the  liquid  state  in  the  bottom,  the  piston  will  descend 
through  a tenth  of  its  entire  height,  and  the  steam  remaining  uncondensed  will  still  have  the  tempera- 
ture of  212°  and  the  pressure  of  14J  lbs.  per  square  inch,  while  the  water  in  the  bottom  of  the  tube 
produced  by  the  condensation  will  also  have  a temperature  of  212°.  The  heat,  therefore,  which  has 
been  thus  abstracted,  is  the  heat  which  was  latent  in  the  steam  formed  by  the  water  thus  deposited. 
And  in  the  same  manner,  any  heat  which  is  drawn  from  the  steam  will  be  latent  heat ; a correspond- 
ing condensation  will  take  place  until  all  the  steam  has  been  condensed,  and  the  piston  brought  into 
contact  with  the  bottom  of  the  tube.  After  that,  any  abstraction  of  heat  must  be  made  at  the  expense 
of  the  sensible  heat  of  the  water. 

It  has,  in  some  works,  been  stated  that  by  mere  mechanical  compression  steam  will  be  converted 
into  water.  This  is,  however,  an  error,  since  steam,  in  whatever  state  it  may  exist,  must  possess  at 
least  212°  of  heat;  and  as  this  quantity  of  heat  is  sufficient  to  maintain  it  in  the  vaporous  form,  under 
whatever  pressure  it  may  be  placed,  it  is  clear  that  no  compression  or  increase  of  pressure  can  diminish 
the  actual  quantity  of  heat  contained  in  the  steam ; and  it  cannot,  therefore,  convert  any  portion  of  the 
steam  into  water. 

If  steam,  by  mechanical  pressure,  be  forced  into  a diminished  volume,  it  will  undergo  an  augmenta- 
tion both  of  temperature  and  pressure,  the  increase  of  pressure  being  greater  than  the  diminution  of 
volume  ; in  fact,  any  change  of  volume  which  it  undergoes  will  be  attended  with  the  change  of  temper- 
ature and  pressure  indicated  in  the  above  table.  The  steam,  after  its  volume  has  been  changed,  will 
assume  exactly  the  pressure  and  temperature  which  it  would  have  in  the  same  volume  if  it  were  im- 
mediately evolved  from  water.  Thus,  let  us  suppose  a cubic  inch  of  water  converted  into  steam  under 
a pressure  of  14f  lbs.  per  square  inch,  and  at  the  temperature  of  212°.  Let  its  volume  be  then  reduced 
by  compression  in  the  proportion  of  1700  to  930.  When  so  reduced,  its  temperature  will  be  found  to 
have  risen  from  212°  to  250°,  and  its  pressure  will  be  increased  from  14J  lbs.  per  square  inch  to  29-J 
lbs.  per  square  inch ; but  this  is  exactly  the  state,  as  to  pressure,  temperature,  and  density,  as  the  steam 
would  be  in  if  it  were  immediately  raised  from  water  under  the  pressure  of  29^-  lbs.  per  square  inch. 
It  appears,  therefore,  that  in  whatever  manner,  after  evaporation,  the  density  of  steam  be  changed, 
whether  by  expansion  or  contraction,  it  will  still  remain  the  same  as  if  it  were  immediately  raised  from 
water  in  its  actual  state. 

The  circumstance  which  has  given  rise  to  the  erroneous  notion  that  mere  mechanical  compression  will 
produce  a condensation  of  steam  is,  that  the  vessel  in  which  steam  is  contained  must  necessarily  have 
the  same  temperature  as  the  steam  itself.  If  then  the  steam  contained  in  the  vessel  be  suddenly  com- 
pressed, it  will  undergo  as  sudden  an  elevation  of  temperature ; and  the  vessel  containing  it  not  receiv- 
ing at  the  same  time,  from  any  external  source,  a corresponding  increase  of  temperature,  it  will  rob  the 
steam  of  a portion  of  its  heat,  and  a partial  condensation  will  be  produced,  and  will  be  continued  until 
the  temperatures  of  the  steam  and  the  vessel  containing  it  shall  be  equalized. 

While  water,  in  passing  into  steam,  suffers  a great  enlargement  of  volume,  steam,  on  the  other  hand, 
m being  converted  into  water  undergoes  a corresponding  diminution  of  volume.  It  has  been  seen  that 
a cubic  inch  of  water,  evaporated  at  the  temperature  of  212°,  swells  into  1700  cubic  inches  of  steam. 
it  follows,  therefore,  that  if  a close  vessel,  containing  1700  cubic  inches  of  such  steam,  be  exposed  to 


STEAM. 


G59 


cold  sufficient  to  take  from  the  steam  all  its  latent  heat,  the  steam  will  be  reconverted  into  water,  will 
shrink  into  its  original  dimensions,  and  will  leave  the  remainder  of  the  vessel  a vacuum.  This  prop- 
erty of  steam  has  supplied  the  means,  in  practical  mechanics,  of  obtaining  that  amount  of  mecbanieai 
power  which  the  properties  of  the  atmosphere  confer  upon  a vacuum.  If  by  any  means  whatever  the 
space  in  a cylinder  under  the  piston  be  rendered  a vacuum,  the  atmospheric  pressure  will  take  effect 
above  the  piston,  and  will  urge  the  piston  downwards  with  a force  amounting  to  about  15  lbs.  on  each 
square  inch  of  the  surface  of  the  piston.  To  render  steam  available  for  this  purpose,  it  is  only  neces- 
sary to  inject  it  into  the  cylinder  until  it  expels  from  the  cylinder  all  the  atmospheric  air  or  other  un- 
condensable gases  which  the  cylinder  contains ; and  when  that  is  effected,  the  pure  steam  which  remains 
in  the  cylinder  being  suddenly  condensed  by  the  application  of  cold,  leaves  the  cylinder  a vacuum,  and 
gives  effect  to  the  atmospheric  pressure  above  the  piston,  as  before  explained.  This  is,  in  fact,  the 
principle  of  the  atmospheric  engine. 

The  temperature  and  pressure  of  steam  produced  by  immediate  evaporation,  when  it  has  received 
no  heat,  save  that  which  it  takes  from  the  water,  have  a fixed  relation  one  to  the  other.  If  this  rela- 
tion were  known,  and  expressed  by  a mathematical  formula,  the  temperature  might  always  be  inferred 
from  the  pressure,  or  vice  versa.  But  physical  science  has  not  yet  supplied  any  principles  by  which 
such  a formula  can  be  deduced  from  any  known  properties  of  liquids.  In  the  absence,  therefore,  of  any 
general  relation  established  by  direct  reasoning,  empyrical  formulae  have  been  proposed  which  express, 
with  more  or  less  precision,  this  relation  in  different  parts  of  the  thermometric  scale. 

When  the  pressure  under  which  the  evaporation  takes  place  does  not  exceed  one  atmosphere,  or  15 
lbs.  per  square  inch,  the  relation  between  the  temperature  and  the  pressure  will  be  expressed  with 
sufficient  accuracy  by  the  following  formula!,  proposed  by  Southern : 


P 


0-04948 


/51-3  + T\5'13 
\ 155T256  ) 


T = 155-7256  X V P — 0-04948  — 51‘3  , 

where  P expresses  the  pressure  in  pounds  per  square  inch,  and  T the  temperature  by  Fahrenheit’s 
thermometer. 

For  pressures  exceeding  one  atmosphere  and  not  exceeding  four,  the  relation  is  expressed  by  the 
following  formulas,  proposed  by  Tredgold : 

/103  + T\C 
\ 201-18  / 

T = 201-18  v'_P  — 103; 

or  by  the  following  formulae, 

_/98-206  + T\  6 
“V  198-562  / 

T = 198-562  l/~Y—  98-806. 

For  pressures  extending  from  four  to  fifty  atmospheres,  the  following  formulas  have  been  proposed 
by  Messrs.  Dulong  and  Arago : 

P = (0-26793  + 0-0067585  T)6 
T = 147-961  y/T-  39-644. 

Biot  has  proposed  a more  general  formula,  which  expresses  the  relation  between  the  pressure  and 
the  temperature,  whatever  be  the  pressure  under  which  the  evaporation  takes  place.  Let  p be  the 
pressure,  expressed  in  millimetres,  of  mercury  at  the  temperature  of  melting  ice ; let  t be  the  tempera- 
ture of  the  water  taken  on  the  centesimal  air  thermometer ; and  let  a,  a,,  «2,  bu  h be  constant  quanti- 
ties, whose  values  shall  be  determined  by  the  following  conditions  : 


a = 5-96131330259 

Log.  a,  = 1-82340688193 

Log.  bl  = — 0-01309734295 
Log.  «a=  0-74110951837 

Log.  = — 0-00212510583. 

The  relation  between  p and  t will  then  be  expressed  by  the  following  formula, 


Log.  p = 


■ a\  bi 


20  + £ 


20  + t. 


M.  Biot  compared  the  temperature  and  corresponding  pressures,  calculated  by  this  formula,  with  tho 
series  determined  by  an  extensive  course  of  experiments  undertaken  by  MM.  Arago  and  Dulong  by 
order  of  the  French  government,  to  those  of  the  experiments  of  Taylor  at  lower  temperatures,  and  to  a 
numerous  series  of  MSS.  observations  of  M.  Gay-Lussac,  extending  from  the  boiling  point  to  tempera- 
tures considerably  below  that  of  melting  ice,  and  found  that  the  calculated  and  observed  results  cor- 
responded within  the  limits  of  error  of  the  experiments  themselves.  The  formula;  first  given  above 
offer,  however,  much  greater  facility  for  practical  calculation,  and  afford  as  accurate  results  as  are  re- 
quired for  all  ordinary  purposes. 

The  same  difficulty  which  attends  the  establishment  of  a general  formula  expressing  the  relation  be- 
tween the  temperatures  and  pressures  of  steam,  also  attends  the  determination  of  one  expressing  the 
relation  between  the  pressure  and  the  augmented  volume  into  which  the  water  expands  by  evaporation. 
Empirical  formulae  have  accordingly  been  likewise  proposed  to  express  this  relation.  The  late  Pro- 
fessor Navier  proposed  the  following  formula  for  this  purpose. 


660 


STEAM. 


Let  V express  the  number  of  cubic  inches  of  steam  produced  by  one  cubic  inch  of  water,  and  let  P 
express  the  pressure  of  this  steam  in  kilograms  per  square  metre ; then  we  shall  have 

_ iooe 

- 0-09  + 0-0000484  ?' 

This  formula  gives  sufficiently  accurate  results  when  applied  to  pressures  much  above  one  atmosphere, 
It  fails  to  give  the  same  accuracy,  however,  when  applied  to  lower  pressures. 

The  following  formulae  have  been  proposed  by  M.  de  Pambour : 

1T_  10,000 

~ 0-4227  -f  0-00258  P’ 

which  will  apply  to  low  pressures ; and 

v _ 10,000 

~ 1-421  -f  (TOO 2 3 P’ 

which  will  be  applicable  to  high  pressures.  In  each  of  these  P is  expressed  in  pounds  per  square  foot 
Dr.  Lardner  proposes  the  following  modified  formula,  V and  P retaining  their  signification : 

w — 38’75969 
~ 164  + P’ 

which  may  be  used  in  reference  to  low-pressure  engines  of  every  form,  as  well  as  for  high-pressure 
engines  which  work  expansively. 

When  the  pressure  is  not  less  than  30  lbs.  per  square  inch,  the  following  formula  will  be  more 
accurate : 

_ 434*7826 

~ 018  4-  P' 

In  the  preceding  observations  steam  has  been  considered  as  receiving  no  heat  except  that  which  it 
takes  from  the  water  during  the  process  of  evaporation,  the  amount  of  which,  as  has  been  shown,  is 
1170°  more  than  the  heat  contained  in  ice-cold  water.  But  steam,  after  having  been  formed  from 
water  by  evaporation,  may,  like  all  other  material  substances,  receive  an  accession  of  heat  from  any 
external  source,  and  its  temperature  may  thereby.be  elevated.  If  the  steam  to  which  such  additional 
heat  is  imparted  be  so  confined  as  to  be  incapable  of  enlarging  its  dimensions,  the  effect  produced  upon 
it  by  the  increase  of  temperature  will  be  an  increase  of  pressure  ; but  if,  on  the  other  hand,  it  be  con- 
fined under  a given  pressure,  with  power  to  enlarge  its  volume,  subject  to  the  preservation  of  that 
pressure,  as  would  be  the  case  if  it  were  contained  in  a cylinder  under  a movable  piston  loaded  with  a 
given  pressure,  then  the  effect  of  the  augmented  temperature  will  be,  not  an  increase  of  pressure  but 
an  increase  of  volume ; and  the  increase  of  volume  in  this  latter  casp  will  be  in  exactly  the  sam  , r >- 
portion  as  the  increase  of  pressure  in  the  former  case. 

These  effects  of  elevated  temperature  are  common,  not  only  to  the  vapors  of  all  liquids,  but  also  to 
all  permanent  gases ; but,  what  is  much  more  remarkable,  the  numerical  amount  of  the  augmentation 
of  pressure  or  volume  produced  by  a given  increase  of  temperature  is  the  same  for  all  vapors  and  gases. 
If  the  pressure  which  any  gas  or  vapor  would  have  were  it  reduced  to  the  temperature  of  melting  ice 
be  expressed  by  100,000,  then  the  pressure  which  it  will  receive  for  every  degree  of  temperature  by 
which  it  is  raised  will  be  expressed  by  208  or,  what  amounts  to  the  same,  the  additional  pressure 
produced  by  each  degree  of  temperature  will  be  the  480th  part  of  its  pressure  at  the  temperature  of 
melting  ice.  From  these  data  it  is  easy  to  obtain  an  algebraical  expression  by  which  the  augmentation 
of  pressure  in  a given  volume,  or,  what  is  the  same,  the  augmentation  of  volume  under  a given  pressure 
for  every  increase  of  temperature,  may  be  calculated. 

Let  v be  the  volume  of  any  elastic  fluid  at  the  temperature  of  32°  ; and  let  it  be  then  supposed  to 
be  raised  by  the  application  of  heat  to  the  temperature  T,  if  under  a given  pressure.  Let  its  aug- 
mented volume  be  V.  The  increase  of  volume  will  then  be  Y — v,  while  the  increase  of  temperature 

V 

will  be  T°  — 32°.  But  since  the  increase  of  volume  for  one  degree  of  temperature  is  — -,  the  increase 

4oU 


for  T°  - 


■ 32°  will  be  — — X (T°  — 32°)  ; and  therefore  the  augmented  volume  V will  be 
480  v ° 


V = c 4-  — (T°  — 32°). 
' 480  v 


S , , T°-32°  ) 

= v \ 1 -j — — - ; 

( 480 


If  Y'  be  the  volume  at  any  other  temperature  T',  we  shall  have 

V'  = * j 


T/0 qoo  ) 


480 


From  whence  we  infer 

V T -f-  448  _ 

Y7- TM-  448’ 

by  which,  when  the  volume  of  steam  at  any  one  temperature  is  known,  the  volume  at  any  other  tem- 
perature may  be  found,  supposing  that  the  steam  receives  no  accession  of  water  by  evaporation. 

Steam  which  thus  receives  additional  heat  after  its  separation  from  the  water  from  which  it  is 
evolved  has  been  called  by  Dr.  Lardner  superheated  steam , to  distinguish  it  from  common  steam,  which 
is  that  usually  employed  in  steam-engines.  Superheated  steam  admits  of  losing  a part  of  its  heat  with- 
out suffering  partial  condensation  ; but  common  steam  is  always  partially  condensed  if  any  portion  ol 
heat  be  withdrawn  from  it.  For  further  details  on  these  properties,  see  Lardner  on  the  Steam-Emjine 
7th  ed.  p.  168,  et.  seq  ; also  Appendix.  See  also  Lardner  on  Heat,  chap.  viii. ; Cabinet  Cyclopccdia, 


STEAM. 


661 


In  the  mechanical  operation  of  steam,  ■which  has  been  already  explained,  the  pressure,  density,  and 
temperature  of  the  steam  are  supposed  to  remain  the  same  during  its  action,  and  the  mechanical  effect 
is  produced  by  the  continual  increase  of  the  quantity  of  steam  produced  by  evaporation.  Thus,  the 
piston  in  the  apparatus  represented  in  the  figure  is  moved  upwards,  not  by  any  change  in  the  tempera- 
ture, density,  or  pressure,  but  by  the  increased  volume  required  by  the  continual  production  of  steam. 
It  has  been  proved  that  by  this  process  alone  the  evaporation  of  a cubic  inch  of  water,  whatever  be  the 
pressure  under  which  it  takes  place,  evolves  a mechanical  force  equivalent  to  a ton  weight  raised  a foot 
high.  But  if,  after  this  evaporation  has  been  completed,  the  steam  be  separated  from  the  water  which 
produced  it,  and  the  load  on  the  piston  be  gradually  diminished,  the  steam  would  expand  by  moving 
the  piston  upwards  in  virtue  of  its  excess  of  pressure,  and  this  expansion  will  continue  until  tire  press- 
ure of  the  steam  shall  be  reduced  to  equality  with  the  load  on  the  piston.  All  mechanical  effect  de- 
veloped in  this  process  is  due  to  the  steam  itself,  independently  of  any  further  evaporation. 

To  make  this  important  quality  of  the  expansive  action  of  steam  understood,  let  us  suppose  the  pis- 
ton loaded  with  a pressure  amounting  to  four  times  that  of  the  atmosphere,  including  that  of  the  at- 
mosphere itself.  If  the  water  under  the  piston  be  evaporated  under  this  pressure,  it  will  have  a tem- 
perature of  about  291°,  and  by  its  evaporation  the  piston  will  be  raised  40  feet.  This  will,  therefore, 
be  the  whole  mechanical  effect  arising  from  the  immediate  evaporation  of  the  water.  But  when  the 
evaporation  has  been  completed,  and  the  piston,  with  its  load  of  four  atmospheres,  stands  suspended  at 
40  feet  above  the  bottom  of  the  tube,  let  a pressure  equal  to  that  of  one  atmosphere  be  removed  from 
the  piston.  The  remaining  pressure  of  three  atmospheres  being  less  than  that  of  the  steam  below  the 
piston,  the  piston  will  be  raised,  and  will  continue  to  rise  until  it  has  attained  a height  of  about  50  feet, 
and  the  temperature  of  the  steam  thus  expanded  will  fall  to  about  275°;  and  its  pressure  being  re- 
duced to  that  of  three  atmospheres,  it  will  cease  to  rise.  By  this  process,  therefore,  a mechanical  force 
has  been  obtained  from  the  steam  equal  to  the  weight  of  three  atmospheres  raised  10  feet,  in  addition 
to  the  effect  obtained  by  immediate  evaporation  ; but  the  expansive  action  does  not  stop  here.  Let  it 
be  supposed  that  the  piston  is  again  relieved  from  the  pressure  of  another  atmosphere,  the  superior 
pressure  of  three  atmospheres  below  will  cause  it  to  rise,  and  it  will  ascend  to  the  height  of  about  7 5 
feet,  the  temperature  of  the  steam  falling  to  about  250°,  and  its  pressure  being  reduced  to  two  atmos- 
pheres. A further  mechanical  effect  equivalent  to  the  weight  of  two  atmospheres  raised  to  about  25 
feet,  has  thus  been  obtained  ; and  it  is  evident  that  by  constantly  and  gradually  diminishing  the  load 
on  the  piston,  an  additional  effect  may  be  always  obtained  from  a given  amount  of  evaporation,  to  an 
extent  which  is  only  limited  by  practical  circumstances  which  restrain  the  application  of  this  expansive 
principle.  Since  the  cost  of  producing  steam  as  a mechanical  agent  depends  chiefly  on  the  quantity  of 
fuel  necessary  to  effect  the  evaporation  of  a given  volume  of  water,  it  follows  that  all  the  mechanical 
effect  obtained  by  this  principle  of  expansion  is  so  much  power  added  to  the  steam  without  further 
expense.  Its  importance,  therefore,  will  be  obvious  in  the  economy  of  steam-power.  For  the  manner 
of  rendering  it  available  in  steam  machinery,  see  Steam-Engine. 

Table  No.  1 exhibits  the  temperatures  and  corresponding  pressures  of  steam  as  determined  by  the 
experiments  of  the  committee  of  the  French  Institute  up  to  fifty  atmospheres — the  atmosphere  being 
measured  by  a column  of  mercury  29'922  inches  high. 

The  last  six  temperatures  in  table  No.  1 are  deduced  by  calculation  from  the  formula  c — (1  -f- 
0-7153  tf,  in  which  e expresses  the  elasticity  in  atmospheres,  and  t the  temperatures  in  centieme  de 
grees,  beginning  from  100°,  and  proceeding  upwards. 

The  most  recent  experiments  on  the  elastic  force 
of  steam  are  those  by  a committee  of  the  Franklin 
Institute.  The  object  of  the  committee  was  to  in- 
quire into  the  causes  of  the  explosion  of  steam- 
boilers,  to  investigate  which  they  were  requested 
to  make  experiments  on  the  properties  of  steam, 
the  expense  of  which  was  defrayed  out  of  the 
treasury  of  the  United  States. 

The  results  are  contained  in  the  following  table, 
No.  2,  arranged  as  in  table  No.  1,  up  to  ten  atmos- 
pheres. 

Table  II. 


Table  I. 


Pressure  in 
Atmospheres. 

Temperature. 

Pressure  in 
Atmospheres. 

Temperature. 

i 

212° 

13 

380-66° 

H 

234 

14 

386-94 

o 

250\5 

15 

392-86 

2i 

263-8 

16 

398-48 

3 

275-2 

17 

403-83 

3* 

285 

18 

408-92 

4 

293-7 

19 

413-78 

44 

300-3 

20 

418-46 

5 

307"5 

21 

422-96 

54 

314-24 

22 

427-28 

6 

320-36 

23 

431-42 

64 

326-26 

24 

435'56 

7 

331-7 

25 

439-34 

n 

336-86 

30 

457-16 

8 

341-78 

35 

472-73 

9 

350-78 

40 

486-59 

10 

358-88 

45 

499-14 

11 

366-85 

50 

510-6 

12 

j 

‘374 

Pressure  in 
Atmospheres. 

Temperature. 

Pressure  in 
Atmospheres. 

Temperature. 

i 

212° 

6 

315-J° 

H 

235 

6J 

321 

2 

250 

7 

326 

24 

264 

U 

331 

3 

275 

8 

336 

34 

284 

8| 

340|- 

4 

2914 

9 

345 

4i 

298$ 

94 

349 

5 

304  i 

10 

352  J 

54 

310 

We  add  the  following  table,  calculated,  we  believe,  by  Professor  Alexander,  of  Baltimore,  on  the 
orcssure  of  steam  at  various  temperatures. 


emp 

in 

:gre« 

0 

5 

10 

15 

20 

25 

30 

32 

33 

34 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

50 

51 

52 

53 

54 

55 

56 

57 

58 

59 

60 

61 

62 

%3 

64 

65 

66 

67 

68 

69 

70 

71 

72 

73 

74 

75 

76 

77 

78 

79 

80 

81 

82 

83 

84 

85 

86 

87 

88 

89 

90 


STEAM. 


of  Steam  in  inches  of  Mercury  at  the  temperature  of  melting  ice  from  degree  tt 
degree  of  Fahrenheit' s thermometer. 


Difference 

for 

1 degree. 

Temp. 

in 

degrees. 

Pressure  in 
inches  of 
Merc. 

Difference 

for 

1 degree. 

Temp. 

in 

degrees. 

Pressure  in 
inches  of 
Merc. 

Difference 

for 

1 degree. 

0-002 

91 

1-67 

157 

9-54 

0-003 

92 

1-72 

158 

9-76 

0-004 

93 

1-77 

0-06 

159 

9-98 

0-23 

0-005 

94 

1-83 

160 

10-21 

0-24 

0-006 

95 

1-89 

161 

10-45 

0-007 

96 

1-95 

162 

10-69 

0-008 

97 

2-01 

163 

10-93 

0-25 

98 

2-07 

164 

11-18 

0-009 

99 

213 

165 

11-43 

100 

2-19 

166 

11-68 

0-26 

o-oio 

101 

2-25 

0-07 

167 

11-94 

0-27 

0-011 

102 

2-32 

168 

12-21 

0-010 

103 

2-39 

169 

12-48 

0-28 

o-oii 

104 

2-46 

170 

12-76 

105 

2-53 

171 

13-04 

106 

2-60 

0-08 

172 

13-32 

0-29 

0-012 

107 

2-68 

173 

1361 

0-30 

108 

2-76 

174 

13-91 

0-013 

109 

2-84 

175 

14-21 

0-31 

0-014 

110 

2-92 

176 

14-52 

111 

3- 

177 

14-83 

0-32 

112 

308 

009 

178 

15-15 

113 

3-17 

179 

15-47 

0-33 

0-015 

114 

3'-26 

180 

15-80 

0-34 

0-016 

115 

3-35 

181 

16-14 

116 

3-44 

182 

16-48 

0-35 

0-017 

117 

3-53 

010 

183 

16-83 

118 

3-63 

184 

17-18 

0-36 

0-018 

119 

3-73 

185 

17-54 

0-37 

120 

3-83 

186 

17-91 

0-019 

121 

3-93 

0-11 

187 

18-28 

0-38 

122 

4-04 

188 

18*66 

0-020 

123 

415 

189 

19-04 

0-39 

0-021 

124 

4"26 

190 

19-43 

0-40 

125 

4-37 

012 

191 

19-83 

0-41 

0022 

126 

4-48 

192 

20-24 

0023 

127 

4-60 

193 

20-65 

0-42 

128 

4-72 

194 

21-07 

0-43 

0-024 

129 

4-84 

0-13 

195 

21-50 

0-025 

130 

4-97 

196 

21-93 

0-44 

0-026 

131 

5-10 

197 

22-37 

0-45 

132 

5-23 

198 

22-82 

0-027 

133 

5-36 

014 

199 

23-27 

0-46 

0-028 

134 

5-50 

200 

23-73 

0.47 

0-029 

135 

5-64 

201 

24-20 

0-48 

136 

5-78 

0-15 

202 

24-68 

0-49 

0-030 

137 

5-93 

203 

25-17 

0-031 

138 

6-08 

204 

25-66 

0-50 

0-033 

139 

6-23 

205 

26-16 

0-51 

140 

6-38 

0-16 

206 

26-67 

0-52 

0-034 

141 

6-54 

207 

27-19 

0-53 

0-035 

142 

6-70 

208 

27-72 

0-54 

143 

6'86 

0-17 

209 

28-26 

0-55 

0-037 

144 

7-03 

210 

28-80 

0-038 

145 

7-20 

0-17 

211 

29-35 

056 

0039 

146 

7-37 

0-18 

212 

29-91 

0-57 

0-040 

147 

^*55 

213 

30-48 

0-58 

148 

7-73 

0-19 

214 

31-06 

0-59 

0-043 

149 

7-92 

215 

31-65 

0-60 

0-043 

150 

8-11 

216 

32-25 

0-61 

0-04 

151 

8*30 

0-20 

217 

32-86 

0-05 

152 

8-50 

218 

33-47 

0-63 

153 

8-70 

219 

34-10 

154 

8-90 

021 

220 

34-73 

0-65 

155 

9-11 

221 

35-38 

156 

9-32 

0-22 

009 

36-03 

067 

STEAM. 


663 


Temp. 

in 

degrees. 


°23 

224 

225 

226 

227 

228 

229 

230 

231 

232 

233 

234 

235 

236 

237 

238 

239 

240 

241 

242 

243 

244 

245 

246 

247 

248 

249 

250 

251 

252 

253 

254 

255 

256 

257 

258 

259 

260 
261 
262 

263 

264 

265 

266 

267 

268 

269 

270 

271 

272 

273 

274 

275 

276 

277 

278 


Table  of  the  Pressure  of  Steam,  dbc.,  (Continued.) 


Pressure  in 

Difference 

Temp. 

Pressure  in 

Difference 

Temp. 

Pressure  in 

Difference  ! 

inches  of 

for 

in 

inches  of 

for 

in 

inches  of 

for 

Merc. 

1 degree. 

degrees. 

Merc. 

1 degree. 

degrees. 

Merc. 

1 degree,  j 

36‘70 

279 

94-47 

1-50 

335 

213-74 

2-94 

37-37 

0-69 

280 

95-97 

1-51 

336 

216-68 

2-97 

38-06 

0-70 

281 

97-48 

1-52 

337 

219-65 

3- 

38-76 

0-71 

282 

99- 

1-54 

338 

222-65 

3-03 

39-47 

0-72 

283 

10054 

1-56 

339 

225-68 

3-07 

40-19 

0-73 

284 

102-10 

1-58 

340 

228-75 

3-10 

40-92 

0-75 

285 

] 03*08 

1-60 

341 

231-85 

3-13 

41-67 

286 

105-28 

1-63 

342 

234-98 

3-16 

42-42 

0-76 

2S7 

106-91 

1-65 

343 

238-14 

3-20 

43-18 

0-77 

288 

108-56 

1-67 

344 

241-34 

3-24 

4395 

0-78 

289 

110-23 

1-69 

345 

244-58 

3-28 

44-73 

0-80 

290 

111-92 

1-71 

346 

247-86 

3-32 

45’53 

0-81 

291 

113-63 

1-72 

347 

251-18 

3-36 

46-34 

0-82 

292 

115-35 

1-75 

348 

254-54 

3-39 

47-16 

0-83 

293 

117-10 

1-77 

349 

257  93 

3-42 

47-99 

0-85 

294 

118-87 

1-80 

350 

261-35 

3-45 

48-84 

0-86 

295 

120-67 

1-83 

351 

264-80 

3-49  j 

49-70 

0-87 

296 

122-50 

1-85 

352 

268-29 

353 

50’57 

0-88 

297 

124-35 

1-87 

353 

271-82 

3-59 

51-45 

0-89 

298 

126-22 

1-89 

354 

275-39 

361 

52-34 

0-91 

299 

128-11 

1-91 

355 

279- 

366 

53-25 

0-92 

300 

130-02 

1-93 

356 

282-66 

3-71 

54-17 

0-94 

301 

131-95 

1-96 

357 

286-37 

3-75  i 

55-11 

0-95 

302 

133-91 

1-99 

358 

290-12 

3-79 

56-06 

0-96 

303 

135-90 

2-01 

359 

293-91 

3-83 

57-02 

0-97 

304 

137-91 

2-03 

360 

’297-74 

3-87 

57-99 

1- 

305 

139-94 

2-06 

361 

301-61 

3-91 

58-99 

1-01 

306 

142- 

209 

362 

305'52 

3-95 

60- 

307 

144-09 

2-11 

363 

309-47 

3-99 

61-01 

1-03 

308 

146-20 

2-13 

364 

313-46 

4-04 

62-04 

1-04 

309 

148-33 

2-16 

365 

317-50 

63-08 

1-07 

1-07 

310 

150-49 

220 

2’22 

64-15 

311 

152-69 

65"22 

1 09 

312 

154-91 

2-24 

Formula. 

66-31 

313 

157-15 

9*27 

inches. 

67-41 

1-10 

314 

159-42 

2-30 

v — 

pressure  in 

68-53 

112 

315 

161-72 

2-32 

t = 

temp,  in  deg.  Fahr. 

69-67 

114 

316 

16404 

2-34 

/ t 990  \ 0 

70-83 

116 

317 

166-38 

2-37 

.-./>  = 

(T80  + 1695) 

71-99 

318 

168-75 

2-40 

73-18 

119 

319 

171-15 

2-44 

t 

180  1/  p— 105°,  13. 

74-37 

1-23 

320 

173-59 

2-48 

75-60 

1-24 

321 

176-07 

2-51 

P‘  = 

atmosphere 

76-84 

1-25 

322 

o-53 

pressure  in 

78-09 

1-27 

323 

181-11 

2'55 

of  29*915  inches  at  32° 

79-36 

1 28 

324 

183*66 

2-58 

r . 

80-64 

1 30 

325 

186-24 

2-61 

t 

temp,  as  before ; 

81-94 

1-33 

326 

188-85 

2 61 

/ t 561-91  \c 

83- 27 

84- 61 

1-34 

1-35 

327 

328 

191-49 

194-15 

2-66 

2-69 

1 1 

- 9 

• ■ P 

y 317-13  1 

1695  ) 

85-96 

1 36 

329 

196-84 

2-73 

( * , 

\ ft  1 

87-32 

1-39 

330 

2-76 

990  \ 

88-71 

1-41 

331 

202-33 

2-80 

^317-13  1 

2986-33  / 

9012 

1-43 

332 

205  13 

2-84 

and 

91-55 

93 

1-45 

1-47 

333 

334 

207-97 

210-84 

2-87 

2-90 

t ~ 

317-13  V p' 

— 105°,  13 

For  a more  exceuoed  and  at  the  same  time  practical  view  of  the  theory  of  steam  and  the  steam 
engine,  embracing  rules  for  all  the  calculations  likely  to  be  introduced  in  the  practice  of  constructing  ol 
working  steam-engines,  the  reader  cannot  do  better  than  consult  “Bourne  on  the  Steam-Engine,”  put 
lished  by  the  Artisan  Club.  It  should  be  in  the  hands  of  every  one  using  steam,  and  Is  recommended 
to  our  readers  as  a standard  work  on  this  subject. 


664 


STEEd. 


STEEL.  Steel  appears  to  occupy  an  intermediate  place  between  cast  and  malleable  iron.  The 
researches  of  the  French  academicians,  Monge,  Barthollet,  and  Vandermonde,  show  the  distinction 
between  cast-iron  and  steel  to  be  that  the  former  is  charged  with  a superabundant,  the  latter  with  a 
minute  yet  sufficient  dose  of  carbon ; hammered  iron,  on  the  contrary,  if  pure,  consists  of  iron  free  from 
all  heterogeneous  matter.  It  is  to  be  regretted  that  the  constituent  proportions  of  steel  have  not  been 
accurately  determined.  Vauquelin  assumes  the  average  amount  of  carbon  to  be  l-150th,  and  Clouet 
places  it  as  high  as  l-32d.  Mr.  Parkinson  considers  the  quantity  of  carbon  necessary  for  making  of  steel 
to  be  very  small,  indeed  the  actual  amount  seldom  exceeding  l-200th,  or  1 -300th,  and  perhaps  never 
more  than  l-100th,  the  remaining  portion  of  charcoal  flying  off  at  the  time  of  cementation  in  the 
form  of  gaseous  oxide  of  carbon.  Dr.  Thomson  analyzed  some  specimens  of  cast-steel,  from  the  man- 
ufactory of  Mr.  Buttery,  near  Glasgow,  and  the  general  results  of  his  trials  gave  the  constituents  as 
follows : 


Iron 99 

Carbon,  with  some  silicon 1 

100 

Now  this  approaches — 

Iron,  20  atoms  VO 

Carbon,  1 atom 0’75 


VO-75 

And  this  Dr.  Thomson  considers  as  likely  to  be  the  constitution  of  cast-steel.  He  did  not  m like 
manner  attempt  the  analysis  of  blistered  steel,  but  concludes  the  proportion  of  carbon  in  it  to  be  rather 
less.  It  is  well  ascertained  that  iron  and  carbon  are  capable  of  combining  together  in  a variety  of 
different  proportions : when  the  carbon  exceeds,  the  compound  is  carburet  of  iron ; when  the  iron 
exceeds,  the  compound  is  steel  or  cast-iron  in  various  states  according  to  the  proportion  : all  these  com- 
pounds may  be  considered  as  subcarburets  of  iron.  The  most  complete  detail  of  experiments  on  these 
compounds  which  has  yet  appeared  in  this  country  is  by  Mr.  Mushet.  This  ingenious  metallurgical 
chemist  has  observed  that  the  hardness  of  iron  increases  with  the  proportion  of  charcoal  with  which  it 
combines,  till  the  carb6n  amounts  to  about  l-80th  of  the  whole  mass.  The  hardness  is  then  a maxi- 
mum, the  metal  acquires  the  color  of  silver,  loses  its  granulated  appearance,  and  assumes  a crystallized 
form.  If  more  carbon  be  added  to  the  compound  the  hardness  diminishes  in  proportion  to  the  quantity, 
as  appears  from  the  following  tabular  arrangement,  extracted  from  Mr.  Mushet’s  papers  on  iron 
and  steel : 


Iron,  semi-steelified 

Soft  steel,  capable  of  welding 

Cast-steel  for  common  purposes  

Cast-steel  requiring  more  hardness 

Steel  capable  of  standing  a few  blows,  but  quite  unfit  for  drawing, 

First  approach  to  a steely  granulated  fracture  

White  cast-iron 

Mottled  cast-iron 

Carbonated  cast-iron 

Super-carbonated  crude  iron 


contains  1-1 50th  of  carbon. 
“ 1-1 20th 

“ l-100th 

“ l-90th 

“ l-50th  “ 

„ j 1-3  0th  ) 

( l-40th  y 

“ 1-2 5 th  “ 

“ 1-2  0th 

“ 1-1 5th 

“ 1-1 2th 


Dr.  Schafthacutl  has  lately  propounded  a novel  and  startling  theory,  viz.,  that  steel  is  entirely  a 
mechanical  production  of  the  forge-hammer,  which  tears  the  molecules  of  certain  species  of  white  cast- 
iron  out  of  their  original  positions,  into  which  the  forces  of  attraction,  in  respect  to  the  centres  as  well 
as  to  the  position  of  the  molecules,  had  arranged  those  molecules  by  the  slow  action  of  heat,  and  that 
steel,  as  it  comes  out  of  the  converting-furnace  or  the  crucible,  is  nothing  more  or  less  than  white  cast- 
iron,  of  which  Indian  steel,  called  wootz,  is  the  fairest  specimen. 

Steel,  as  is  well  known,  is  made  by  combining  carbon  with  iron,  the  atmosphere  being  excluded  and 
a white  heat  kept  up  until  the  iron  has  imbibed  from  the  carbonaceous  matter  with  which  it  is  sur- 
rounded a sufficient  quantity,  which  may  be  more  or  less,  according  to  the  use  for  which  the  steel  is 
intended.  Iron  is  very  slightly,  and  if  pure,  not  at  all,  altered  or  increased  in  hardness  by  sudden  cool- 
ing from  a red-heat,  but  the  small  amount  of  carbon  which  it  receives  during  the  process  of  cementation 
greatly  increases  both  its  strength  and  toughness,  leaving  it  alike  malleable  and  ductile,  and  imparts  to 
it  that  peculiarly  valuable  property  of  becoming  extremely  hard  if  suddenly  cooled  from  a red-heat. 
With  this  first  dose  of  carbon  it  is  denominated  mild  steel , possessing  all  the  distinctive  properties  oi 
iron  with  increased  strength.  A larger  dose  of  carbon  renders  the  metal  susceptible  of  greater  hard- 
ness, and  proportionably  more  brittle.  It  is  also  fusible,  and  therefore  called  cast-steel,  but  being  less 
malleable  is  more  difficult  to  work. 

Steel  made  by  cementation  is  designated  blistered-steel,  because  it  is  supposed,  while  the  carbon  is 
entering  it  meets  with  oxygen,  hydrogen,  or  some  foreign  matter  which  it  causes  to  become  gaseous, 
and  thus  blisters  the  surface  of  the  steel.  Dr.  Thomson  attributes  these  blisters  to  a gas  evolved  in  the 
interior  of  the  bar,  which  pushes  up  by  its  elasticity  a film  of  the  metal,  and  Mr.  Gill  considers  them  as 
indications  of  the  quality  of  the  steel,  as  “ the  hardest  will  be  found  to  be  blistered  all  over  its  surface 
while  the  milder  will  be  smoother.”  Cast-steel  being  made  by  fusion  admits  of  an  equal  distribution  of 
the  carbon,  to  the  expulsion  of  every  other  substance,  which  cannot  endure  the  intense  heat : the  sound- 
ness of  this  description  of  steel  is  obviously  a great  recommendation,  but  the  excess  of  carbon  renders  it 


STEEL. 


665 


harsh  and  consequently  intractable ; under  the  hammer,  however,  by  careful  treatment  during  the 
operation  of  forging,  the  excess  of  carbon  may  be  dissipated  and  the  quality  of  the  steel  ameliorated 
and  greatly  improved  for  general  purposes. 

The  question  whether  steel  contains  any  thing  besides  iron  and  carbon  is  purely  chemical,  the  con- 
sideration of  which  would  form,  did  space  allow,  an  interesting  theoretical  illustration  of  the  practical 
details  of  the  present  inquiry.  A good  workman  merely  requires  steel  free  from  flaws,  completely 
homogeneous,  and  such  as  will  harden  at  the  lowest  heat,  for  this  test  supersedes  all  others  in  proving 
its  superior  quality. 

Perfectly  pure  iron  cemented  in  equally  pure  carbon  would  doubtless  produce  steel  free  from  blisters, 
but  as  in  practice  these  blisters  are  unavoidably  evolved,  it  is  needless  to  inquire  into  their  origin  more 
minutely  than  we  have  already  done,  especially  as  it  seems  to  be  admitted  that  blistered-steel  is 
unequally  carbonized,  the  outside  retaining  the  larger  portion.  It  is  therefore  rendered  fit  for  the 
market  by  doubling  and  welding  several  times,  by  which  means  the  parts  are  more  intimately  blended 
together,  and  the  carbon  more  equally  distributed ; in  this  state  it  is  called  sheer-steel.  These  repeated 
weldings,  although  they  tend  to  condense  the  metal,  are  apt  to  produce  flaws,  1st.  by  imperfect  union, 
2d.  by  the  carbon  burning  out  of  the  commingling  surfaces,  thereby  interposing  a stratum  of  iron  or 
imperfectly  converted  steel,  and  this  being  softer  than  the  surrounding  particles  would  give  way  during 
the  extension  of  the  steel.  To  whatever  cause  such  defects  are  to  be  attributed  must  necessarily 
remain  a matter  of  conjecture,  but  that  they  do  very  largely  accompany  this  description  of  steel 
is  certain,  and  it  is  a question  whether  any  process  short  of  actual  fusion  can  totally  remove  them ; 
nevertheless,  it  is  ascertained  that  long-continued  forging  essentially  conduces  to  the  soundness  or 
homogeneity. 

Besides  these  flaws  there  is  another  obstacle  frequently  met  with  in  steel : it  is  said  to  have  pins, 
when,  in  the  operation  of  turning  or  filing,  knots  are  developed  harder  than  the  other  portions  of  the 
metal ; these  knots  or  pins  present  themselves  of  almost  every  degree  or  hardness,  commencing  with 
mere  harshness,  and  advancing  to  absolute  intractability,  so  that  whilst  turning  in  the  lathe  the  pins 
would  remain  projecting  out  and  grind  or  break  the  edge  of  the  tool  rather  than  submit  to  be  cut  away, 
and  it  is  by  no  means  unusual  to  find  their  hardness  nearly  approach  that  of  a file  applied  to  remove 
them.  Various  causes  have  been  assigned  for  these  knots;  Mr.  Varley  thinks  they  are  portions  of 
metal  over-steeled,  that  is,  so  completely  charged  with  carbon  as  to  be  incapable  of  being  annealed  by 
any  known  process  of  slow  cooling.  Mr.  Clement  states  that  he  broke  the  steel  across  these  pins,  hav- 
ing filed  away  the  back  to  render  it  weak  enough  to  part  at  the  right  place,  when  he  found  a cut  or 
division,  on  which  account  he  attributes  the  flaw  and  its  extreme  hardness  to  an  oxide  of  iron,  which 
prevented  the  union  of  the  parts.  It  would  be  a curious  and  by  no  means  an  unprofitable  investiga- 
tion to  analyze  the  condition  of  the  deepest  blisters,  in  order  to  determine  whether  they  are  alloyed  or 
oxidized,  or  in  any  way  differing  in  their  state  of  carbonization  from  the  more  solid  parts.  It  seems 
clear  that  if  these  pins  are  induced  by  the  presence  of  oxygen,  then  the  adjoining  metal  would  be  iron, 
for  there  would  be  a gradation  from  the  oxide  through  iron  to  the  steel,  and  consequently  the  circum- 
ference of  such  a spot  would  be  softest. 

An  excess  of  carbon  renders  steel  harder  and  more  brittle,  therefore  au  inequality  is  liable  to  occur. 
This  may  be  illustrated  by  the  known  fact,  that  portions  of  an  iron  casting  intended  to  be  soft  are  fre- 
quently hardened  by  contact  with  the  moist  sand  of  which  the  mould  is  formed,  and  those  parts  near- 
est the  outside  break  with  a fracture  more  glassy  than  even  hard  steel.  How  good  steel  hardened  by 
sudden  immersion  in  cold  water,  when  at  a red-heat,  will  invariably  return  to  a soft  state  by  slow  cool- 
ing from  such  heat,  and  more  equally  so  if  the  external  atmosphere  be  carefully  excluded ; but  this 
hard  cast-iron  on  the  contrary  does  not ; it  requires  to  be  exposed  for  many  hours  to  an  intense  heat, 
and  must  not  be  smothered  by  fuel  to  prevent  the  escape  of  the  superabundant  carbon  with  which  it  is 
charged.  The  air  too  should  be  allowed  free  access  as  a means  of  disengaging  some  portions  of  the 
carbon,  while  the  remainder  has  a tendency  to  equalize  itself;  then,  if  slowly  cooled,  the  mass  will  be 
found  to  be  sufficiently  aunealed. 

The  knots  or  pins  in  steel  are  rarely  removed  by  slow  cooling  alone ; there  is,  however,  an  opinion 
prevalent  among  workmen  that  pinny  steel  may  be  rendered  uniform  in  its  substance  if  it  be  first 
hardened  and  then  annealed.  To  bum  out  these  pins  would  manifestly  spoil  the  steel,  because  it  has 
no  carbon  to  spare  but  in  the  pins,  (supposing  this  to  be  the  cause  of  their  hardness,)  and  the  process 
of  annealing  in  air-tight  vessels  is  not  found  to  produce  equality  sufficient  for  any  good  purpose.  Even 
cast-steel,  which  is  undeniably  purer  and  more  homogeneous  than  any  other  description,  is  liable  to 
long  streaks  or  veins  harder  than  the  other  portions  of  the  bar.  All  these  show  the  necessity  of  greater 
and  more  minute  attention  to  the  treatment  of  steel  than  the  subject  appears  to  have  received,  and  for 
this  end  two  modes  of  hammering  are  indispensable.  To  illustrate  our  position,  let  us  take  any  article 
forged  in  the  usual  way,  not  out  of  blistered  or  sheer-steel,  both  of  which  may  be  presumed  to  contain 
carbon  unequally  distributed,  but  of  cast-steel,  which  having  been  fused  and  passed  through  the  rolls, 
or  under  a jjonderous  tilt-hammer,  is  characterized  as  refined,  and  considered  uniform.  Yet  notwith- 
standing every  precaution,  we  still  see  the  labor  and  skill  of  the  machinist  defeated  by  those  veins, 
fissures,  and  pins,  which  denote  either  metal  of  inferior  quality,  or  that  the  original  texture  of  the  steel 
has  been  deteriorated  by  the  ignorance  and  carelessness  of  the  smith.  The  first  supposition  does  not 
apply  to  cast-steel,  in  which  the  dose  of  carbon  is  diffused  equally  throughout  the  mass,  or  so  nearly  so 
as  to  render  the  difference  inappreciable.  We  are  therefore  compelled  to  admit  the  second  position, 
and  this,  unless  we  have  entirely  mistaken  the  bearings  of  the  case,  will  enable  us  to  account  for  past 
failures  and  guard  against  future  disappointment. 

The  two-fold  process  of  hammering,  already  alluded  to,  is  intended  to  correct  the  greater  part,  if  not 
the  whole,  of  the  defects  pointed  out.  It  is  necessary  in  the  first  place  to  hammer  the  steel  at  a forg- 
ing heat,  so  as  to  knead  the  parts  together  and  keep  them  moving  among  themselves.  This  should  bo 
continued  till  the  different  constituents  are  not  only  intimately  blended,  but  as  it  were  dissolved  iu  each 


(1(36 


STRENGTH  OF  MATERIALS  OF  CONSTRUCTION. 


other,  so  as  to  insure  perfect  uniformity,  for  the  carbon  being  thus  spread  the  metal  will  be  rendered 
as  sound  as  can  be  expected  of  cemented  steel ; and  it  is  clear  that  if  by  mechanical  agency  all  foreign 
matter  be  expelled  and  the  carbon  alone  remain,  there  is  nothing  to  prevent  a perfect  union  of  the  parti 
while  under  the  hammer.  Good  steel  consists  of  that  proportion  of  carbon  and  iron,  which  combined 
form  the  strongest  and  toughest  compound ; each  purer  portion,  therefore,  when  brought  into  contact  by 
the  hammer  remains  in  that  state  and  resists  its  percussive  force  the  more  from  the  greater  cohesion  of 
the  particles.  Hence  the  redundant  or  deficient  portions  suffer  most  till  they  become  equalized,  and 
the  impurities  are  either  beaten  out  or  formed  into  a homogeneal  compound  with  the  entire  mass. 

Although  by  this  means  sound  steel  may  be  obtained,  it  is  far  from  being  in  a perfect  state ; it  is  still 
very  unequal  in  density,  and  in  a state  of  distraction  ; some  portions  are  close  and  dense,  and  others  are 
fissured.  A second  hammering  at  a particular  heat  is  therefore  necessary,  and  under  circumstances 
required  by  the  shape  of  the  steel — such  as  recesses  in  the  anvil  or  blocks  laid  thereon,  technically 
termed  swedges  and  moulds.  For  this  purpose  the  metal  is  first  brought  as  near  as  eligible  to  the  re- 
quired dimensions,  and  is  then  to  be  hammered  in  order  to  close  and  condense  the  particles  equally 
and  throughout,  yet  leaving  every  part  in  a state  of  rest  and  ease — a condition  very  essential  for  good 
springs,  and  indeed  every  article  formed  of  steel,  that  has  to  vibrate  or  act  by  tension. 

This  second  hammering  is  also  intended  to  prepare  the  steel  for  receiving  the  utmost  hardness  of 
which  it  is  susceptible — a quality  which  entitles  it  to  be  considered  the  master  metal — the  one  by  which 
we  give  shape  and  form  to  all  others.  How  steel  at  a red-heat,  when  suddenly  plunged  in  cold  water, 
becomes  both  brittle  and  hard,  but  even  in  this  state  its  toughness  greatly  exceeds  that  of  any  other 
brittle  substance.  This  characteristic  hardness  cannot  be  given  in  part,  but  always  in  full  and  to  its 
highest  limit.  So  true  is  this,  that  in  a piece  of  steel,  a portion  of  which  is  hard  and  a portion  soft,  no 
gradation  of  hardness  can  be  detected,  the  parts  adjacent  to  the  hard  portion  being  quite  soft,  or,  as 
some  think,  softer  than  if  slowly  cooled.  This  singular  fact  has  been  thus  accounted  for  : — Suppose  a 
rod  of  well-hammered  steel  to  be  heated  at  one  end  for  hardening,  there  will  be  a gradation  of  tem- 
perature from  the  coldest  to  the  hottest  extremity,  and  the  annealing  or  reduction  of  that  hardness 
which  it  has  received  will  be  in  proportion  to  the  heat,  consequently  the  rod  will  be  softer  and  softer 
towards  the  end  where  the  heat  is  applied.  On  plunging  the  bar  into  cold  water,  that  portion  which 
has  become  sufficiently  hot  to  harden,  is  rendered  quite  hard,  but  that  part  immediately  adjacent  to  it 
will  be  found  to  be  most  annealed,  and  will  endure  more  twisting  and  bending  than  any  other.  Al- 
though this  hardness  may  be  imparted  in  its  full  extent,  it  may  nevertheless  be  lowered  in  any  assigna- 
ble degree — that  is,  a portion  of  its  brittleness  may  be  removed  by  the  application  of  moderate  heat,  a 
greater  portion  by  more  heat,  and  so  on,  as  the  purposes  may  require.  This  is  called  tempering.  If 
hard  steel  be  brought  to  a red-heat  and  then  suffered  to  cool  slowly,  it  will  become  as  soft  as  if  never 
hardened : this  is  called  softening , and  is  distinguished  from  annealing , which  is  a similar  process  of 
slow  cooling,  but  applied  to  steel,  iron,  or  brass,  merely  to  remove  all  mechanical  condensation,  whether 
by  hammering  or  otherwise  ; for  if  metal  has  been  altered  in  shape  by  the  hammer  or  any  other  pro- 
cess, as  much  as  it  will  bear  without  breaking,  then  by  annealing  it  will  be  softened  and  may  again  be 
altered  in  form  as  often  as  requisite.  Now  as  different  degrees  of  heat  remove  different  degrees  of 
condensation  received  from  the  hammer,  and  a white-heat  removes  all,  it  is  of  great  importance  to 
harden  steel  from  the  lowest  possible  degree  of  heat,  in  order  to  retain  as  much  condensation  as  practi- 
cable ; and  it  is  a fortunate  coincidence  that  the  greater  the  condensation  the  lower  is  the  heat  from 
which  steel  will  harden,  and  the  stronger  and  tougher  it  will  be.  But  should  this  condensed  metal  be 
once  over-heated,  it  will  then  no  longer  harden  from  that  lower  degree,  but  only  from  a heat  nearly 
approaching  that  to  which  it  was  originally  raised.  In  this  case,  the  condensation,  with  all  its  attend- 
ant advantages,  can  only  be  restored  by  rehammering. 

The  lowest  heat  at  which  steel  will  generally  harden,  is  a dull  or  cherry -red,  just  visible  in  day-light ; 
therefore,  to  be  safe,  the  same  test,  that  is,  a dull  red-heat,  just  perceptible  in  the  dark,  is  chosen  for 
the  process  of  hammering ; it  offers,  too,  the  advantage  of  coating  the  article  with  carbonaceous  matter, 
thereby  securing  instead  of  losing  by  the  action  of  the  fire  a due  supply  of  carbon,  which  is  of  particu- 
lar consequence.  Different  modes  of  performing  this  part  of  the  process  may  be  adopted.  It  is  de- 
sirable that  the  forge  should  not  be  under  the  influence  of  a strong  light;  the  anvil  should  be  placed  as 
near  as  circumstances  will  permit  to  the  flat  bed  of  the  forge,  and  the  fire  smothered  with  small  fuel, 
just  kept  alive  by  the  bellows,  so  as  never  to  allow  the  gas  bursting  into  flame.  The  pieces  of  steel 
under  treatment  are  now  placed  in  the  smouldering  and  partially  kindled  fuel  enveloped  in  smoke, 
whence  they  imbibe  a portion  of  carbon,  which  the  hammering  heat  is  insufficient  to  expel ; they  are 
then  brought  in  succession  from  the  fire  to  the  anvil,  and  back  again  to  the  fire  when  too  cool,  the  ham- 
mer is  moved  quickly,  and  every  part  of  the  steel  subjected  to  its  blow.  The  position  of  the  article  is 
then  slightly  changed,  and  the  operation  continued  and  repeated  as  often  as  needful,  till  it  has  been 
hammered  well  in  every  direction.  See  Tools,  as  also  Tempering.  See  also  Mushet  on  Steel. 

STRENGTH  OF  MATERIALS  OF  CONSTRUCTION.  1.  Direct  cohesion.— The  power  of  co- 
hesion is  that  resistance  which  bodies  exhibit  when  force  or  weight  is  applied  to  tear  asunder  in  the 
direction  of  their  length  the  fibres  or  particles  of  which  they  are  composed. 

The  strength  to  resist  force  or  weight  that  produce  fracture  is  as  the  area  of  the  cross-section  acted 
upon.  Hence,  multiply  the  area  of  the  section  in  inches  by  the  power  in  pounds  (as  in  the  following 
table)  opposite  the  name  of  the  material,  and  the  product  will  be  equal  to  the  weight  in  pounds  the  rod, 
bar,  or  piece  will  just  support;  but  the  greatest  constant  load  should  never  exceed  one-fourth. 


STRENGTH  OP  MATERIALS  OF  CONSTRUCTION. 


667 


Table  of  the  Cohesive  Power  of  Bodies  whose  Cross-Sectional  Areas  equal  One  Square  Inch. 


Woods. 

Cohesive 
Power, 
in  lbs. 

Cohesive 
Power, 
in  tons. 

Metals. 

Cohesive 
Power, 
in  lbs. 

Cohesive 
Power, 
in  tons. 

23,400 

10-44 

Swedish  bar-iron 

65,000 

29'20 

19  980 

8-92 

Russian  do 

59,470 

26'70 

Turtosa,  African  teak. 

17*000 

7'58 

English  do 

56,000 

25'00 

Ash  

15,780 

7'04 

Cast  steel 

134,256 

59-93 

Teak  wood,  or  Indian 

Blistered  steel 

133,152 

59-43 

14,500 

647 

Shear  do 

127,632 

56-97 

Poona,  or  Peon 

1 2^350 

551 

Wrought  copper 

33,892 

15-08 

12,000 

5-35 

Hard  cun-metal 

36,368 

16-23 

American  fir,  or  pine. . 

11,800 

526 

Cast  copper 

19,072 

8-51 

Oak 

11,592 

5-17 

Yellow  brass,  cast 

17,968 

8-01 

11  500 

5-13 

Cast-iron 

17,628 

7-87 

Mahogany,  Honduras. 

11,475 

5'12 

Tin,  cast 

4,736 

211 

11,000 

4-91 

Bismuth,  cast  

3,250 

1-45 

Chestnut,  Spanish 

10,800 

4-82 

Lead,  cast 

1,824 

0-81 

Alder 

9,700 

4'33 

Elastic  power,  or  direct 

Larch 

9,500 

4'24 

tension  of  wrought- 

Walnut 

7,740 

3'45 

iron,  medium  qual- 

Mahogany,  Spanish  ... 

7,560 

3'37 

ity 

22,400 

10-00 

Cedar,  Libanus 

7,000 

312 

Poplar 

6,500 

2'90 

Note. — A bar  of  iron  is  extended  '000096,  or  nearly  one  ten-thousandth  part  of  its  length,  for  every 
ton  of  direct  strain  per  square  inch  of  sectional  area. 

The  resistance  being  proportional  to  the  area,  the  strength  of  any  given  bar  or  bolt  will  be  found  by 
multiplying  the  sectional  area  in  inches  by  the  tabular  number. 


Table  of  the  relative  Weight  and  Strength  of  Ropes  and  Chains. 


Cireum.  of 
Rope. 

Weight  per 
fathom. 

Weight  of 
chain  per  fath. 

Proof 

Strength. 

Cireum.  of 
rope. 

Weight  per 
fathom. 

Weight  of 
chain  per  fath. 

Proof 

Strength. 

Inches. 

lbs. 

lbs. 

tons. 

cwt. 

Inches. 

lbs. 

lbs. 

tons. 

cwi. 

H 

2} 

54 

1 

54 

10 

23 

43 

10 

0 

44 

4| 

8 

1 

16| 

104 

28 

49 

11 

11 

5 

H 

lOJ 

2 

10 

114 

304 

56 

13 

8 

5J 

7 

14 

3 

54 

124 

36 

63 

14 

18 

64 

94 

18 

4 

34 

13 

39 

71 

16 

14 

7 

HI 

22 

5 

2 

134 

45 

79 

18 

11 

8 

15 

27 

6 

44 

144 

484 

87 

20 

8 

19 

32 

7 

7 

154 

56 

96 

OO 

13 

94 

21 

37 

8 

134 

16 

60 

106 

24 

18 

2.  Transverse  strength,  or  resistance  to  lateral  pressure. — The  strength  of  bodies  to  resist  fracture  in 
this  direction  is  as  the  breadth  and  square  of  the  depth,  directly,  and  inversely  as  the  length. 

The  general  formula  being 

Sad~  = l w, 

where  a is  the  breadth,  d the  depth,  l the  length,  w the  weight,  and  S a number  determined  by  experi- 
ment on  ditferent  materials.  When  the  beam  is  supported  at  each  end  and  loaded  in  the  middle,  the 
values  of  S for  different  materials  have  been  determined  by  Mr.  Barlow  as  in  the  following  table — the 
breadth  and  depth  being  taken  in  inches,  the  length  in  feet,  and  the  weight  in  pounds. 


Values  of  S for 


Elastic  strength  of 

Good  English  malleable  iron 2050 

Cast-iron 2548 

Teak 820 

English  oak 400 

Best  Canadian 688 

Ash 675 


different  Materials. 
Elastic  strength  of 


Pitch  pine 544 

Red  pine 447 

Riga  fir 376 

Mar  forest  fir 415 

Larch 280 


Note. — It  must  be  observed  that  these  numbers  indicate  the  extreme  strengdL  The  practical  man 
must  not  depend  upon  more  than  a third  of  these  values. 


868 


STRENGTH  OF  MATERIALS  OF  CONSTRUCTION. 


If  the  depth  is  taken,  a certain  fractional  part  of  the  depth  as  - th,  the  above  formula  becomes 

S d3  — n l w, 

,nl  10 


or,  d = V- 


Hence  the  following  rule  in  words  : 


Rule. — Multiply  the  length  between  the  bearing  in  feet  by  the  weight  to  be  supported  in  pounds 
and  by  the  number  indicating  the  ratio  of  the  depth  to  the  breadth — divide  the  product  by  the  tabular 
value,  and  the  cube  root  of  the  quotient  equals  the  dejith  in  inches ; and  the  depth  divided  by  the  pro- 
portional breadth  is  the  breadth  in  inches. 

Example. — Suppose  a uniform  beam  of  cast-iron,  18  feet  in  length,  be  required  to  carry  a weight  of 
20,000  pounds  on  the  middle,  between  the  supports,  what  must  be  the  breadth  and  depth,  in  inches, 
when  the  breadth  is  one-fifth  of  the  depth,  and  the  strain  not  to  exceed  one-third  of  the  strength  ? 

We  must  here  take  ^s  = 850. 

88  X 20000  X 5 l'^*8 

Hence, = 3*/  2117'6  = 12'8  in.  in  depth,  and  — ' — = 2'56  in.  in  breadth  or  thickness. 

850  5 

2.  Given  the  length  and  breadtlt  of  a uniform  beam,  and  the  weight  it  is  to  support  in  the  middle , to 
find  the  required  depth ; or  the  depth  given,  to  find  the  breadth  required. 

Here,  d = — . 

s a 

Rule. — Multiply  the  length  in  feet  by  the  weight  in  pounds.  Also  the  tabular  value  of  S by  the 
breadth  in  inches.  Divide  the  former  product  by  the  latter,  and  the  square  root  of  the  quotient  will 
give  the  depth  in  inches. 

Or,  divide  the  former  product  by  S times  the  square  of  the  depth,  and  the  quotient  will  be  the 
breadth. 

Example. — Let  it  be  required  to  find  the  breadth  of  a uniform  beam  of  oak  to  sustain  a weight  of 
6000  pounds  in  the  middle  of  its  length,  the  distance  between  the  supports  being  20  feet,  and  the  depth 
of  the  beam  9 inches.  The  strain  to  be  half  the  strength. 


G000  X 20 


: 7 '4  inches,  the  breadth ; and 


V 6000  X 20 


= 9-1  inches,  the  depth. 


200  X 9-  ’ ' ~~  ’ " 200  X 7 

Note  1. — When  the  load  is  not  on  the  middle  of  the  beam,  but  placed  nearer  to  one  end,  divide  four 
times  the  product  of  the  distance  of  the  weight  in  feet  from  each  bearing  by  the  whole  distance  in  feet, 
and  the  quotient  equals  the  length  of  the  beam  to  be  taken  into  account. 

Example. — Suppose  a beam  80  feet  in  length  with  a load  placed  9 feet  from  one  end ; required  the 
length  to  be  taken  into  calculation  as  affected  by  the  load. 

21  X 9 X 4 

30  — 9 = 21,  and = 25'2  feet  effective  length. 

30  ° 

Note  2, — When  the  load  is  distributed  over  the  whole  length  of  a beam,  it  will  bear  double  the  as- 
sumed load  as  above ; hence,  in  such  cases,  the  divisors  must  be  doubled. 

Note  8. — When  a beam  is  to  be  fixed  at  one  end  and  the  weight  placed  on  the  other,  take  only  one- 
fourth  of  the  tabular  number  for  the  divisor;  but  if  the  weight  is  to  be  laid  uniformly  along  its  whole 
length,  use  one-half. 

Example  to  Rule  2. — Required  the  depth  for  the  cantilevers  of  a balcony  of  cast-iron  to  project  4 feet, 
and  to  be  placed  5 feet  apart,  the  weight  of  the  stone  part  being  1000  pounds,  the  breadth  of  each  can- 
tilever 2 inches,  and  the  greatest  possible  load  that  can  be  collected  upon  5 feet  in  length  of  the  balcony 
2200  pounds. 

1000  + 2200  = 3200  lbs.;  and  800  = 2 = 400,  the  divisor. 


Hence, 


V 3200  X 4 . , , , , 

= 4 inches,  the  depth  required. 


400  X 2 

Deflection  of  rectangular  beams.— To  ascertain  the  amount  of  deflexion  of  a uniform  beam  of  cast-iron 
supported  at  both  ends,  and  loaded  in  the  middle  to  the  extent  of  its  elastic  force. 

Rule. — Multiply  the  square  of  the  length  in  feet  by  -02,  and  the  product  divided  by  the  depth  in 
inches  equals  the  deflexion. 

Example. — Required  the  deflexion  of  a cast-iron  beam  18  feet  long  between  the  supports,  12’8  inches 
deep,  2'56  inches  in  breadth,  and  bearing  a weight  of  20,000  pounds  in  the  middle  of  its  length. 

182  X '02 

7 = 506  inches  from  a straight  line  in  the  middle. 

12-8 

Note. — For  beams  of  a similar  description,  loaded  uniformly,  the  rule  is  the  same,  onl)  multiply  by 
025  in  place  of  '02. 

To  find  the  deflexion  of  a beam  when  fixed  at  one  end  and  loaded  at  th  e other. 

Rule. — Divide  the  length  in  feet  of  the  fixed  part  of  the  beam  by  the  length  in  feet  of  the  part  which 
yields  to  the  force,  and  add  1 to  the  quotient ; then  multiply  the  square  of  the  length  in  feet  by  the 
quotient  so  increased,  and  also  by  T3  ; divide  this  product  by  the  middle  depth  in  inches,  and  the  quo- 
tient will  be  the  deflexion,  in  inches  also. 

Multiply  the  deflexion  so  obtained  for  cast-iron  by  -86,  the  product  equals  the  deflexion  for  wrought 
iron  ; for  oak,  multiply  by  2'8  ; and  for  fir,  2'4. 


STRENGTH  OF  MATERIALS  OF  CONSTRUCTION. 


(169 


A Table  of  the  Depths  of  Square  Beams  or  Bars  of  Cast-Iron,  calculated  to  support  from  1 cwt.  to  1* 
tons  in  the  Middle,  the  Deflexion  not  to  exceed  1-40  th  of  an  inch  for  each  foot  in  Length,. 


Lengths  in  feet. 

4 

6 

8 

10 

12 

14 

16 

i8 

20 

22 

24 

26 

28 

30 

Weight 

Weight 

i 

5 

f 

a 

4 

4 

4 

5 

CL 

s 

i 

5 

5 

ft 

in  cwt. 

in  lbs. 

a 

o 

a 

a 

a 

a 

a 

a 

a 

a 

a 

« 

« 

a 

In. 

In. 

In. 

In. 

In. 

In. 

In. 

In. 

In. 

In. 

In. 

In. 

In. 

In. 

1 cwt. 

112 

1-2 

1-4 

1-7 

1-9 

2-0 

2-2 

24 

2-5 

29 

27 

29 

39 

31 

3-2 

2 

124 

1'4 

1-7 

29 

2'2 

2-4 

2-6 

2-8 

39 

3-1 

39 

3-4 

39 

37 

3-8 

3 

336 

16 

1-9 

2-2 

2-4 

27 

29 

31 

39 

3-4 

39 

3-8 

39 

41 

4*2 

4 

448 

1-7 

2-0 

2-4 

2'6 

29 

3-1 

39 

3-5 

37 

39 

4*0 

42 

43 

4-5 

r> 

560 

1-8 

2'2 

2*5 

28 

3-0 

39 

35 

37 

39 

41 

43 

4-4 

4*6 

4-8 

G 

672 

1'8 

2'2 

2-0 

29 

32 

34 

37 

39 

41 

49 

45 

46 

4-8 

59 

7 

784 

1-9 

23 

2'7 

30 

33 

39 

3-8 

41 

4-2 

4-4 

49 

4-8 

59 

5-2 

8 

896 

2-0 

2-4 

2'8 

31 

34 

37 

3-9 

4-2 

4'4 

49 

48 

59 

59 

54 

9 

1,008 

2-0 

2-5 

2-9 

32 

35 

3-8 

4 0 

49 

49 

47 

4-9 

5-1 

59 

5-5 

10 

1,120 

21 

26 

30 

3'3 

36 

39 

4-2 

44 

47 

49 

5*2 

59 

5'4 

57 

11 

1,232 

2-1 

2'6 

30 

34 

37 

40 

4‘3 

4 5 

4-8 

59 

59 

5*4 

59 

58 

12 

1,344 

2-2 

2'7 

3'1 

35 

3-8 

41 

4’4 

47 

4‘9 

5-1 

5-3 

55 

57 

59 

13 

1,456 

2*2 

2-7 

31 

35 

3-8 

42 

4'4 

47 

49 

5*2 

54 

59 

59 

69 

14 

1,568 

23 

2'8 

3-2 

3'6 

39 

4'2 

45 

4-8 

5*0 

59 

5-5 

57 

6-0 

6-1 

15 

1,680 

23 

2'8 

3'2 

36 

4-0 

49 

46 

49 

5*2 

5*4 

5'6 

58 

6-1 

0-2 

16 

1,792 

2-4 

2-9 

3'3 

37 

4-0 

4-4 

47 

59 

52 

5-5 

57 

59 

6'2 

6*4 

17 

1,904 

2'4 

29 

3’4 

3'8 

4-1 

44 

47 

59 

59 

5-5 

5'8 

6*0 

6’2 

6-5 

18 

2,016 

2-4 

30 

34 

3-8 

42 

45 

4'8 

57 

5-4 

59 

59 

6-1 

04 

6*6 

19 

2,128 

2-5 

3-0 

3-5 

39 

42 

49 

4’9 

59 

5'4 

57 

69 

6-2 

6'5 

6 7 

1 ton. 

2,240 

2-5 

3-0 

3'5 

3-9 

4-3 

49 

49 

5-2 

5'5 

5-8 

6*0 

69 

65 

6*6 

H 

2,800 

2-0 

3'2 

37 

4-1 

45 

49 

5‘2 

5'5 

5-8 

61 

6*4 

69 

69 

7-2 

4 

3,360 

2-8 

34 

39 

4-3 

47 

57 

5'5 

5-8 

O'l 

64 

6*7 

79 

7*2 

7-5 

1-1 

3,920 

2-9 

3-5 

4*0 

4-5 

4-9 

59 

57 

69 

69 

07 

69 

7-2 

7'5 

77 

2 

4.480 

2-9 

35 

41 

47 

57 

5'5 

59 

6*2 

69 

6-8 

7-2 

7-6 

77 

89 

24 

5,600 

31 

3'8 

44 

4-9 

55 

5’8 

G'2 

6*6 

6*9 

79 

7-6 

79 

8'2 

8-5 

3 

6,720 

3-3 

40 

4'6 

51 

57 

67 

6’5 

69 

7’3 

79 

79 

8-3 

89 

89 

34 

7,840 

3-4 

4-1 

4'8 

53 

5-8 

69 

67 

71 

7'5 

79 

8-2 

89 

89 

9'2 

4 

8,960 

35 

43 

4'9 

5*5 

60 

65 

79 

7-4 

7'8 

8-2 

8'5 

89 

9*2 

9 5 

44 

10,080 

4-4 

5-1 

57 

62 

67 

7*2 

79 

89 

8-4 

8-8 

9-1 

9-5 

9-8 

5 

11,200 

4'5 

5-2 

5.8 

64 

6'9 

7’4 

78 

8‘2 

89 

9*0 

9-4 

97 

107 

6 

13,440 

55 

6-1 

67 

7-2 

7.7 

8-2 

8'6 

9*0 

9-4 

9-8 

10-2 

10*5 

7 

15,680 

57 

6-3 

69 

7*5 

89 

8-5 

89 

9*4 

9-8 

10-2 

109 

119 

8 

17,920 

59 

66 

7 2 

7-8 

89 

8-8 

99 

97 

10-1 

10*6 

109 

119 

9 

20,160 

6*0 

6-8 

7-4 

89 

89 

90 

9-5 

100 

104 

109 

119 

117 

in 

22,400 

6-9 

7-6 

82 

8-8 

99 

9-8 

109 

107 

11-2 

119 

129 

n 

24,640 

7-1 

7-8 

8-4 

99 

9-5 

10  0 

105 

119 

115 

119 

129 

12 

26,880 

7-2 

79 

89 

9*2 

97 

10*2 

10-8 

11*2 

117 

12-1 

12-5 

13 

29,120 

7-4 

8-1 

88 

9 4 

99 

10*4 

119 

145 

11*9 

12-4 

129 

14 

31,360 

7-5 

8-3 

8-9 

9-5 

10-4 

109 

111 

117 

12-1 

129 

139 

Deflexion  in  inches. . 

I 

•15 

■2 

•25 

■3 

•35 

■4 

•45 

•5 

•55 

9 

•65 

7 

75 

Lengths  in  feet. 

10 

12 

14 

16 

18 

20 

22 

24 

2G 

23 

30 

32 

34 

36 

15 

33,600 

7-7 

8-4 

91 

97 

10-3 

10-8 

11-4 

119 

129 

12-8 

13-2 

137 

141 

145 

lo 

35.840 

7-8 

8-5 

9-2 

9-8 

10-4 

119 

11-5 

129 

12*5 

130 

13-5 

139 

149 

147 

17 

38,080 

7-9 

8-7 

9-4 

10-0 

10-6 

11-2 

117 

12-2 

127 

13-2 

13  7 

141 

1 4*5 

149 

18 

40,320 

8-0 

8-8 

95 

107 

10-8 

119 

119 

12-4 

129 

13-4 

139 

143 

147 

15-1 

19 

42,560 

81 

8-9 

96 

103 

10-9 

1 1-5 

12-2 

129 

13  1 

139 

141 

14-5 

159 

15-4 

29 

44,800 

90 

9-7 

104 

no 

119 

12-5 

127 

13  2 

13  8 

14-2 

147 

15-1 

15*6 

22 

49,280 

9-2 

lo-o 

107 

11-3 

119 

12-8 

13*0 

139 

141 

149 

157 

15*5 

159 

24 

53,760 

9-4 

102 

109 

11-5 

12-2 

139 

13-4 

139 

14*4 

149 

15-4 

159 

169 

26 

58,240 

90 

10  4 

lit 

11-8 

12-4 

13-3 

139 

142 

147 

15*2 

157 

16-2 

167 

28 

62,720 

9-8 

10-6 

11-4 

129 

127 

13-5 

139 

144 

159 

15*5 

169 

16*5 

179 

Deflexion  in  inches. . 

•25 

•3 

•35 

•4 

•45 

•5 

•55 

•0 

•6G 

•7 

•75 

•8 

•85 

•9 

1 

Lengths  in  feet. 

14 

16 

18 

20 

22 

24 

26 

28 

30 

32 

34 

36 

38 

40 

30 

67,200 

10-8 

11-5 

12-2 

12-9 

13-5 

141 

147 

15*2 

157 

16-3 

16-8 

179 

177 

18-2 

32 

71,680 

11*0 

117 

12-4 

13-1 

13-7 

149 

14*9 

15-5 

169 

16-5 

179 

17-5 

189 

18  5 

34 

76,160 

111 

1 1-9 

12-6 

13-3 

139 

14-5 

151 

157 

16-2 

16*8 

179 

17-8 

189 

18-8 

36 

80,640 

11-3 

12-0 

12-8 

13-4 

111 

147 

159 

159 

16-5 

179 

17-5 

189 

18-5 

199 

38 

85,120 

11-4 

12-2 

130 

13  6 

14  3 

149 

15  5 

161 

167 

17-2 

17-8 

189 

18-8 

199 

40 

89,600 

12-4 

13-1 

13-8 

14-5 

15-1 

157 

16-4 

169 

17'5 

189 

18-5 

101 

19-5 

42 

94,080 

12'5 

13-3 

140 

14-7 

159 

159 

16  5 

171 

177 

18-2 

187 

199 

19-8 

44 

98,560 

12-7 

13*5 

142 

149 

15*5 

161 

10-8 

17-4 

179 

18'5 

199 

19-5 

20*0 

46 

103,040 

12-8 

13  6 

14*3 

150 

157 

169 

170 

179 

181 

187 

19-2 

19-8 

209 

48 

107,520 

I3'0 

137 

14-5 

152 

159 

16*5 

17 1 

177 

189 

18'8 

19-4 

20*0 

20-5 

50 

112,000 

13-8 

14-6 

159 

169 

16  6 

17-3 

179 

18-5 

199 

199 

20-1 

207 

52 

116,480 

14-0 

147 

15-5 

16  2 

16-8 

17-5 

18-1 

187 

19'2 

198 

20*3 

21-0 

54 

120,960 

14-1 

14-9 

15-7 

169 

179 

179 

182 

18-8 

19*4 

199 

20*5 

21-1 

56 

125,440 

14-3 

150 

15  8 

16*5 

17-1 

178 

18-4 

199 

199 

207 

20*7 

219 

58 

129,920 

14-4 

15-1 

159 

16  6 

179 

17*9 

18-5 

192 

197 

209 

20*9 

21-4 

60 

134,400 

14-5 

15-3 

160 

167 

17-4 

18-1 

187 

199 

199 

20*5 

241 

219 

Deflexion  in  inches. 

•35 

•4 

■45 

•5 

■55 

•6 

|95 

7 

75 

•8 

•85 

•9 

95 

19 

670 


STRENGTH  OF  MATERIALS  OF  CONSTRUCTION. 


Examples  illustrative  of  the  Table. — 1.  To  find  the  depth  of  a rectangular  bar  of  cast-iron  to  support 
a weight  of  10  tons  in  the  middle  of  its  length,  the  deflexion  not  to  exceed  l-40th  of  an  inch  per  foot  in 
length,  and  its  length  20  feet,  also  let  the  depth  be  6 times  the  breadth. 

Opposite  6 times  the  weight  and  under  20  feet  >n  length  is  15'3  inches,  the  depth,  and  l-6th  ol 
15'3  = 2'6  inches,  the  breadth. 

2.  To  find  the  diameter  for  a cast-iron  shaft  or  solid  cylinder  that  will  bear  a given  pressure,  the 
flexure  in  the  middle  not  to  exceed  l-40th  of  an  inch  for  each  foot  of  its  length,  the  distance  of  the  bear- 
ings being  20  feet,  and  the  pressure  on  the  middle  equals  10  tons. 

Constant  multiplier  T7  for  round  shafts,  then  10  X TV  = 17.  And  opposite  17  tons  and  under  20 
feet  is  1T2  inches  for  the  diameter. 

But  half  that  flexure  is  quite  enough  for  revolving  shafts : hence  17  X 2 = 34  tons,  and  opposite  34 
tons  is  13'3  inches  for  the  diameter. 

The  preceding  tables  of  the  strength  of  cast-iron  bars  are  the  data  of  recent  experiments  by  Mr 
Hodgkinson  of  Manchester,  and  extracted  from  his  new  edition  of  Tredgold  on  the  strength  of  cast-iron. 
This  gentleman  has  also  made  extensive  experiments  for  obtaining  the  strongest  form  of  t 
section  for  beams,  the  following  of  which  is  the  strongest  form  yet  obtained.  J 

The  bottom  flange  B is  as  6 to  1 of  the  top  flange  T,  or  contains  6 times  its  sectional  area. 

He  also  gives  the  following  rule  for  ascertaining  the  ultimate  strength  of  beams  of  cast- 
iron  of  the  preceding  section  and  proportions. 

Multiply  the  sectional  area  of  the  bottom  flange  in  inches  by  the  depth  of  the  beam  in 
inches,  and  divide  the  product  by  the  distance  between  the  supports,  also  in  inches,  and 
514  times  the  quotient  will  give  the  breaking  weight  in  cwts. 


Table  of  the  Weight  of  Modulus  of  Elasticity  of  various  Metals 


Name  of  Metal. 

Modulus  of  Elas- 
ticity, in  lbs. 

Name  of  Metal. 

Modulus  of  Elas- 
ticity, in  lbs. 

Steel  

29,000,000 

24.920.000 

18.400.000 

13.680.000 

Gun-metal 

Brass  

9.873.000 

8.930.000 

4.608.000 
720,000 

Tin 

Lead  

Note. — Modulus  of  elasticity,  or  measure  by  which  the  comparative  stiffness  of  bodies  may  be  ascer- 
tained: thus,  the  modulus  of  elasticity  for  oak  is  1714500,  and  for  cast-iron  18400000,  or  10'7  times 
that  of  oak;  therefore  a piece  of  cast-iron  is  107  times  as  stiff  as  a piece  of  oak  of  equal  dimensions 
and  bearing. 

A hard  body  is  that  which  yields  least  to 
any  stroke  or  impressive  force;  and  in  uni- 
form bodies  the  degree  of  yielding  is  always 
proportioned  to  the  weight  of  the  modulus  of 
elasticity. 

Resilience,  or  toughness  of  bodies,  is  strength 
and  flexibility  combined ; hence  any  material 
or  body  which  bears  the  greatest  load,  and 
bends  the  most  at  the  time  of  fracture,  is  the 
toughest. 

Annexed  i9  a Table  of  experiments  on  rect- 
angular bars  of  malleable  iron  by  Mr.  Bar- 
low,  for  the  purpose  of  determining  the  point 
of  neutral  axis,  the  centre  of  compression, 
and  the  greatest  deflexion  to  which  railway 
bars  or  lines  of  rail  might  be  submitted 
without  causing  permanent  injury  to  the  pro- 
perties of  the  iron. 

Note. — Distance  between  the  bearings  33 
inches ; breadth  of  bar  1 j inch  ; depth  3 
inches. 

The  neutral  axis  was  found  to  be  l-5th  of 
the  depth  from  the  top  of  the  bar ; the  centre 
of  compression  §ds  of  that  fifth  above  the 
neutral  axis ; and  the  rule  for  obtaining  the 
utmost  degree  of  deflexion  as  follows : 

Divide  '22  by  4-5ths  the  depth  of  the  bar 
,n  inches,  and  the  quotient  is  the  utmost  de- 
flexion that  can  be  suffered  with  safety  on 
bearing  33  inches  apart. 

To  find  the  weight  that  railway  bars  will 
support. — Observe,  that  whatever  figure  may 
oe  given  to  the  transverse  section,  the  head, 
or  top  portion  of  the  rail,  is  generally  sup- 
posed to  occupy  the  2-5ths  of  the  whole  section  ; or,  in  the  larger  description,  to  have  two  inches  sec 
tion,  and  to  be  one  inch  deep,  and  that  the  lower  web  be  the  same  depth  as  the  head 


Weight  in 
tons. 


Deflexion 
in  inches. 


Deflexion 
per  half 
ton. 


Remarks. 


T25 

■500 

TOO 

T50 

2-00 

2-50 

8-00 

350 

4-00 

4-50 

•50 

TOO 

T50 

2-00 

2- 50 
300 

3- 50 

4- 00 
4-50 

•50 

TOO 

T50 

2-00 

2- 50 

3- 00 
3-50 


7-50 


•043 

•059 

•074 

•083 

•095 

•101 

•109 

•120 

T31 

T48 

•017 

•037 

•052 

•061 

•064 

•078 

•089 

T02 

T24 

■003 

■050 

•060 

•074 

•093 

•110' 

T49 


015 

009 

012 

006 

008 

Oil 

Oil 

017 


015 

009 

003 

014 

011 

013 

022 


020 

010 

014 

019 

017 


Mean,  ‘0103. 
k)  = 4F  Neutral  axis, 
Y 1 : 4-9. 

Elasticity  preserved 
at  4 j tons. 


Mean,  ‘0108. 
w — 4R  Neutral  axis, 
1 : 4-9. 

Elasticity  injured. 


The  depth  of  this  bar 
only  2 1 inches. 
Mean,  -0173. 


Bent  8 inches. 


w = 3.  Neutral  axis,  1 
4 9.  Elasticity  pre- 
served, 3 tons. 


STRENGTH  OF  MATERIALS  OF  CONSTRUCTION. 


671 


Resistance  of  the  head  or  upper  portion  of  the  rail. — Rule. — Subtract,  the  thickness  of  the  middle  rib 
from  2 inches,  and  multiply  the  remainder  by  10. — Again,  subtract  an  inch  from  the  whole  depth, 
and  multiply  the  remainder  by  12;  then  divide  the  former  product  by  the  latter  and  the  quotient 
equals  the  resistance,  in  tons,  due  to  the  head,  not  including  the  continuation  of  the  middle  rib. 

Resistance  of  the  centre  rib. — Rule. — Multiply  the  whole  depth  of  the  rail  in  inches  by  the  whole 
depth  minus  ^ an  inch,  and  that  product  by  10  times  the  thickness  of  the  rib;  jd  of  the  last  product 
equals  the  resistance,  in  tons,  of  the  middle  rib  continued  through  the  whole  depth. 

Resistance  of  lower  web. — Rule. — Multiply  the  whole  depth  of  the  rail,  minus  1 inch,  by  the  breadth 
of  the  bottom  web,  minus  the  thickness  of  the  rib,  and  that  product  by  10. — Again:  from  the  whole 
depth  of  the  rail  subtract  1 inch,  and  to  12  times  the  square  of  the  remainder  add  6 times  the  remain- 
der, and  call  this  the  first  number.  From  this  subtract  twice  the  remainder,  and  add  1,  and  call  this 
the  second  number.  Then  say,  as  the  first  number  is  to  the  second,  so  is  the  product  obtained  in  the 
former  part  of  the  rule  to  the  resistance  of  the  lower  web,  not  including  the  continuation  of  the  mid- 
dle rib. 

Then,  the  sum  of  these  three  resistances  multiplied  by  4,  and  divided  by  the  clear  bearing  length, 
will  be  the  weight,  in  tons,  that  the  rail  will  sustain  without  injury. 

Ex.  1.  Let  the  depth  of  a rail  be  5 inches,  with  a plain  rib,  whose  thickness  is  -9  of  an  inch  ; required 
the  greatest  weight  that  it  ought  to  be  required  to  bear. 

R . , fl  , < (2  — -9).  X 10  = 11  ) 11  no 
Resistance  of  head  j (5  _ x 12  = 54  \ 54  = °'2' 


44  X 5 X -9  X 10  67-5  , 4 X 67'7  , . , 

Resistance  of  rib = — — ; and, 8*21  tons,  the  greatest  weight;  and 

3 67*7  33  6 & ’ 


•22 

the  deflexion  with  this  weight  — =-05  of  an  inch  nearly. 
5 4-5 


Ex  2.  Suppose  a rail  with  bottom  web,  the  depth  of  rail  being  5 inches,  the  thickness  of  rib  6 of 
an  inch,  breadth  of  section  of  lower  web  1 '32,  and  weight  50  lbs.;  required  the  greatest  load. 

Resistance  of  head  j j j * jj>  II  1 j j-  ~=  0'26  tons. 

t,  • . . .,4$'  X 5 X -6  X 10 

Resistance  of  rib = 45'00  do 

f (5  — 1)  X '72  X 10  X 28-8 
Lower  web  I 12  (5  — l)2  -f-  24  = 210,  or  1st  number  j 
( 216  — 7 = 209,  or  2d  number 

Then  210  : 209  : : 28-8  : 27'94  = 27'94 


And 


73  2 X 4 
33 


= 8'75  tons,  the  greatest  weight. 


73-20 


ON  THE  STRENGTH  OF  COLUMNS,  OR  POWER  OF  RESISTANCE  TO  COMPRESSIVE  FORCE. 


Ti  jle  of  Practical  Formulce  by  which  to  determine  the  Amount  of  Weight  a Column  of  given  Dimen- 
sions will  support  in  lbs. 


For  a rectangular  column  of  cast-iron 


For  a rectangular  column  of  malleable  iron 


For  a rectangular  column  of  oak 


For  a solid  cylinder  of  cast-iron 


For  a solid  cylinder  of  malleable  iron 


For  a solid  cylinder  of  oak 

Vote. — AV  = the  weight  the  column  will  support  in  lbs. 
b = the  breadth  in  inches. 

1 = the  length  in  feet. 
d = the  diameter  in  inches. 


15300  lb3 

~ 4 b-  + 18  lr 
17800  lb3 
~ 4 6s  + -16  A 
3960  lb' 

W — 4 62  + -5  P' 
_ 9562  d‘ 

~4d2  + -18  A 
11!25  d' 

~ 4</2  + -16  f2' 
_ 2470  d* 

4 d2  -f-  -5  P' 


Ex.  1.  A rectangular  column  of  oak,  6 inches  on  the  side,  and  12  feet  in  length,  what  weight  will  it 
support  ? 


3960  X 12  X 63 
4 X O2  + -5  X J22 


10264320 


= 47520  lbs. 


216 


672 


STRENGTH  OF  MATERIALS  OF  CONSTRUCTION. 


Ex.  2.  What  weight  will  a cast-iron  cylinder  support,  whose  diameter  is  4 inches,  and  length  10 
feet  ? 


95G2  X 5' 

4 X 52  + -18  X 10'2 


5976250 

118 


= 50646  lbs. 


Table  to  shovi  the  Weight  or  Pressure  a Column  of  Cast-iron  will  sustain  with  safety. 


Length  or 
height  in 
feet. 

4 

6 

8 

10 

12 

14 

16 

18 

20 

22 

24 

Diameter. 

Weight 
in  cwts. 

Weight 
in  cwts. 

Weight 
in  cwts. 

Weight 
in  cwts. 

Weight 
in  cwts. 

Weight 
in  cwts. 

Weight 
in  cwts. 

Weight 
in  cwts. 

Weight 
in  cwts. 

Weight 
in  cwts. 

Weight 
in  cwts. 

In. 

24 

119 

105 

91 

77 

65 

55 

47 

40 

34 

29 

25 

178 

163 

145 

128 

111 

97 

84 

73 

64 

56 

49 

H 

247 

232 

214 

191 

172 

156 

135 

119 

106 

94 

83 

4 

326 

310 

288 

266 

242 

220 

198 

178 

160 

144 

130 

H 

418 

400 

379 

354 

327 

301 

275 

251 

229 

208 

189 

5 

522 

501 

479 

452 

427 

394 

365 

337 

310 

285 

262 

6 

607 

592 

573 

550 

525 

497 

469 

440 

413 

386 

360 

7 

1032 

1013 

989 

959 

924 

887 

848 

808 

765 

725 

686 

8 

1333 

1315 

1289 

1259 

1224 

1185 

1142 

1097 

1052 

1005 

959 

• 9 

1716 

1697 

1672 

1640 

1603 

1561 

1515 

1467 

1416 

1364 

1311 

10 

2119 

2100 

2077 

2045 

2007 

1964 

1916 

1865 

1811 

1755 

1697 

11 

2570 

2550 

2520 

2490 

2450 

2410 

2358 

2305 

2248 

2189 

2127 

12 

3050 

3040 

3020 

2970 

2930 

2900 

2830 

2780 

2730 

2670 

2600 

Relative  Strength  of  Long  columns  of  different  materials,  Cast-iron  being  1000  : 


Steel 

Wrought-iron 
Dantzic  oak.. 
Red  deal 


= 2518 
= 1745 
= 108-8 
= 78-5 


Elasticity  of  torsion,  or  resistance  of  bodies  to  being  twisted. — The  angle  of  flexure  by  torsion  is  as 
the  length  and  extensibility  of  the  body  directly  and  inversely  as  the  diameter.  Hence,  the  length  of  a 
bar  or  shaft  being  given,  the  power,  and  the  leverage  the  power  acts  with,  being  known,  and  also  the 
number  of  degrees  of  torsion  that  will  not  affect  the  action  of  the  machine,  to  determine  the  diameter 
in  cast-iron  with  a given  angle  of  flexure : 

Rule. — Multiply  the  power  in  pounds  by  the  length  of  the  shaft  in  feet,  and  by  the  leverage  in  feet ; 
divide  the  product  by  55  times  the  number  of  degrees  in  the  angle  of  torsion,  and  the  fourth  root  of  the 
quotient  equals  the  shaft’s  diameter  in  inches. 

Ex.  Required  the  diameter  of  a series  of  shafts,  30  feet  in  length,  and  to  transmit  a power  equal  to 
4000  lbs.,  acting  at  the  circumference  of  a wheel  of  2 feet  radius,  so  that  the  twist  of  the  shafts  on  the 
application  of  the  power  may  not  exceed  one  degree. 


4000  X 30  X 2 
55  X 1 


4*/4364  = 8T3  inches  diameter. 


Note. — The  rule  is  the  same  for  hollow  shafts,  only  using  48  in  place  of  55,  the  thickness  of  metal 
being  l-5th  the  shaft’s  diameter. 

To  determine  the  side  of  a square  shaft  to  resist  torsion  with  a given  flexure : 

Rule. — Multiply  the  power  in  pounds  by  the  leverage  it  acts  with  in  feet,  and  also  by  the  length  of 
the  shaft  in  feet;  divide  this  product  by  92-5  times  the  angle  of  flexure  in  degrees,  and  the  square  root 
of  the  quotient  equals  the  area  of  the  shaft  in  inches. 

Ex.  Suppose  the  length  of  a shaft  to  be  12  feet,  and  to  be  driven  by  a power  equal  to  700  lbs., 
acting  at  1 foot  from  the  centre  of  the  shaft ; required  the  area  of  cross-section,  so  as  it  may  not  exceed 
1 degree  of  flexure. 

700  X 1 X 12  . , 

— — — : — = \/90-8  = 9’oS  inches. 

9 2 ‘ o X 1 


Relative  Strength  of  Bodies  to  resist  Torsion,  Lead  being  1. 


Tin = 1-4 

Copper  = 4'3 

Yellow  brass  = 4'6 

Gun-metal . . = 5 0 

Cast-iron = 9'0 


Swedish  iron 

— 9-5 

English  do 

— 10-1 

Blistered  steel 

— 16-6 

Shear  do 

— 17-0 

Cast  do 

— 19-5 

STRENGTH  OF  MATERIALS  OF  CONSTRUCTION. 


673 


Strength  of  hletals  when  Pulled  in  the  Direction  of  their  Length. 


Names  of  metals. 

Specific 

(Gravity. 

Force 
necessary 
to  tear 
nsunder  1 
sq.  in.  in 
lbs.  Avd. 

Antimony,  cast 

4-500 

1-060 

Bismuth,  cast  

9-810 

3-250 

“ cast  

9-926 

3-008 

Copper,  cast,  Barbary  

8-182 

22-570 

“ “ Japan  

8-726 

20-27 

61-228 

Gold,  cast  

19-238 

20-450 

30-888 

Iron,  cast 

“ gray,  of  Cruzot,  1st  fusion. 

30-162 

“ “ “ 2d  “ 

30-6S0 

“ Engli-di 

52-000 

“ “ soft 

40-824 

70-367 

<<  a 

50-981 

U (( 

42-666 

“ “ soft 

63-622 

“ “ gray 

37-680 

“ German  

7-807 

68-295 

Iron,  -wrought  

“ bar,  coarse  grained  

20-460 

“ “ medium  fineness  

34-081 

“ “ fine-grained 

O 

49-982 

“ “ of  good  quality 

CO 

55000 

“ bar  

o 

61041 

“ “ of  best  quality 

o 

66000 

“ bar  

o 

80-000 

u 

G 

80-333 

u tc 

£ 

84-443 

“ Germ,  marked  B.  R 

o 

f-t 

,61-361 

W “ “ “ 

93069 

“ “ common  

69-133 

“ “ marked  L 

69*538 

Names  of  metals. 

* 

Specific 
G ravity. 

Ferce 
neco-jsary 
to  tear 
asunder  1 
sq.  in.  in 
lbs.  Avd. 

Iron,  German,  marked  L 

85-900 

62-369 

“ ditto  

o 

82-839 

“ Oosement 

CO 

68-728 

“ ditto  

G 

76-697 

“ Spanish. 

-2 

81-901 

“ Swedish  

o 

o 

68-728 

“ ditto  

88-972 

“ cable 

54-513 

o 

73024 

85-797 

113-077 

Lead,  cast 

11-479 

0-885 

2-547 

1 1-282 

2-581 

11-348 

3-146 

“ milled 

11-407 

3-328 

52-987 

20-847 

56-473 

Silver,  cast  

11-091 

40-902 

38-257 

7-780 

120-000 

“ razor-tempered  

to 

7*840 

150-000 

Tin,  cast,  Banca  

7-217 

7-295 

5*322 

“ “ ditto  

u “ Malacca  

6-126 

3-211 

7-1  9,9 

Zinc,  cast,  Goslar 

“ “ ditto  

7-215 

7-215 

2*937 

2*689 

“ patent  sheet 

16*616 

“ wire  

22-551 

Strength  of  Alloys  when  Pulled  in  the  Direction  of  their  Length. 


Parts.  Parts.] 


Brass 

i 

45-882 

Copper  

10— Tin 

i 

32-093 

“ 

8 “ 

i| 

36-088 

“ 

6 “ 

ii 

44-071 

“ 

4 “ 

i 

35-739 

“ 

0 « 

i 

1-017 

“ 

1 “ 

i 

0-725 

Gold 

5 — Copper  ... 

i 

50-000 

“ 

o — Silver 

1 

28-000 

Lead,  Scotch,  1 0 — Bismuth  . . . 

i 

10-827 

2-826 

“ “ 

2 “ 

i 

11-090 

5-840 

“ “ 

i 

i 

10-931 

7-319 

Silver 

. 5 — Copper.... 

i 

4S-500 

“ 

. 4— Tin  

i 

41*000 

Tin,  Banca.. 

10 — Antimony. 

i 

7-359 

11-181 

“ “ 

8 

i 

7-276 

9-881 

“ .. 

6 

i 

7-228 

12-632 

“ “ 

4 

ii 

7-192 

13-480 

2 “ 

i 

7-105 

12-029 

U U 

i 

i 

7-060 

3-184 

it  (( 

10 — Bismuth ... 

i 

7-576 

12-688 

U it 

4 

ii 

7 613 

16-692 

u u 

2 “ 

1 

8-070 

14-017 

Parts.  Paits. 

Tin, 

Banca... 

1— Bismuth  .. 

i 

8-146 

12-020 

“ 

... 

1 

2 

8-580 

10-013 

“ 

“ ... 

1 

4 

9-009 

7-875 

“ 

“ ... 

1 

10 

9-439 

3-871 

“ 

“ ... 

10 — Zinc,  In- 

dian 

1 

7-288 

12-914 

“ 

“ ... 

2 “ 

1 

7-000 

15-025 

“ 

“ 

i “ .... 

1 

7-321 

15-844 

“ 

“ ... 

i “ .... 

2 

7-100 

16023 

“ 

“ 

i “ .... 

10 

7-130 

5*671 

U 

4 — Antimony 

1 

11-323 

“ 

“ 

3 

2 

3-184 

“ 

“ ... 

1 

i 

7-000 

1-450 

Tin, 

English 

10 — Lead  ..... 

i 

6-904 

“ 

“ 

8 “ 

i 

7-922 

“ 

“ 

6 « 

i 

7-997 

“ 

“ 

4 “ 

i 

10-607 

“ 

“ 

2 “ 

i 

7-470 

“ 

« 

i “ 

i 

7-074 

“ 

8 Zinc,  Goslar 

i 

10-607 

“ 

“ 

4 >< 

i 

10-25S 

“ 

“ 

2 “ “ 

i 

10964 

“ 

“ 

i “ 

i 

9-024 

1) 

Vol.  II— 4: 


674 


STRENGTH  OF  MATERIALS  OF  CONSTRUCTION. 


Strength  of  Woods  when  Pulled  in  the  Direction  of  their  Length. 


Names  of  woods. 

> 

Specific 
Gravity,  a 

Acacia 

0-860 

Alder  

Ash  

0-840 

0-780 

Ash  

1 Ash  

Ash,  red,  seasoned 

0-812 

0-685 

“ white,  seasoned  

Bay  '. 

| Bay  

0-720 

Beech  

Birch 

0-640 

0-990 

0-400 

0-540 

Box  

Cedar  

Cedar 

Chestnut,  horse 

0-610 

0-610 

0-877 

“ do.,  100  years  in  use... 

Citron  

Citron  

Cypress 

! Damson 

0-790 

0-340 

Deal,  Norway  spruce 

“ ditto.  

0-460 

0-460 

0-460 

0-470 

0-498 

0-472 

“ ditto.  

“ ditto.  

“ . English 

“ Scotch,  white  

“ “ yellow  

Elder I 

Elm 

Fir,  American 

0-416 

“ Riga  

“ Russian 

0-459 

“ ditto  

“ ditto  

“ Mem  el,  seasoned 

“ weakest  

“ strong  red 

“ strongest 

“ ditto  

Hawthorn 

0-910 

Hawthorn 

Holly 

0-760 

Jujube  

Jasmine 

Jasmine 

j Laburnum 

0920 

1-010 

1-022 

0'636 

0-496 

0-470 

“ Scotch,  seasoned 

“ “ very  dry 

Force 
ecessai-y 
to  tear 
asunder  1 
sq. in. in 
lbs.  Avd. 


1G-000 

14-186 

7- 667 
17-379 

16- 700 
19-600 

17- 000 
12-000 
17-892 
14-220 

14- 572 
10-220 
22-200 

17- 709 

15- 000 

15- 500 
6-300 

11- 400 

4- 973 

12- 100 
10-500 
12-168 

8- 176 
12-782 

5- 105 

6- 895 
14-000 

18- 100 

17- 600 
1 2-400 

12- 300 
14-000 

7- 000 
4-290 

8- 478 
10-230 

13- 489 

8- 874 

9- 072 
10-008 
10000 

9-792 

10- 876 
8-280 

11- 040 

12- 420 

13- 000 

10- 700 
9-200 

16- 000 

18- 915 
12-020 

11- 756 
10-500 

23- 400 

24- 696 
11093 

7-888 
7 020 


Names  of  woods. 

Specific 
Gravity,  a 

Lemon 

Lignum  Vitte  

1-220 

Lime-tree  

0-760 

Mahogany 

0-870 

Mahogany 

0-800 

Maple,  Norway  

0-793 

Mulberry  

0-660 

Mulberry  

0-660 

Mulberry  

0-673 

“ ditto,  old  

“ ditto  

0-760 

0-760 

0-700 

“ pile  out  of  River  Cam 

0-610 

0-670 

“ ditto  

1-068 

0-660 

0-660 

0-771 

0-828 

1-164 

“ Norway 

0-590 

0-660 

“ St.  Petersburg  

0-550 

0-490 

0-360 

0-700 

0-690 

0-530 

“ Java,  seasoned 

“ Malabar,  seasoned 

0-697 

0-688 

0-619 

Walnut  

0590 

0-390 

Willow,  dry  

0790 

Force 


9- 457 

11-800 
23-500 

20- 582 

21- 800 

16- 500 

12-186 

10- 584 

17- 400 

10-600 

14-054 

11- 501 

11- 412 

7- 704 

8- 820 

10- 224 

14- 000 

15- 000 
19-800 

4-500 

7-700 

16079 

9-043 

9-985 

13- 659 

16- 300 

14- 000 

12- 839 

13- 602 

14- 685 

7- 818 

12- 096 

13- 176 

12- 400 

14- 300 

13- 100 
13-300 

11- 351 

12- 782 

8- 308 
11-501 

7- 200 

6- 641 

4- 596 

5- 878 

8- 822 

18- 600 

13- 000 
6'895 

11- 247 
8-200 

14- 220 
13-140 
13-194 

7- 800 
14  000 

12- 782 

7- 628 

8- 000 


STRENGTH  OF  MATERIALS  OF  CONSTRUCTION. 


675 


Transverse  strength  of  timber. — The  following  table  contains  the  results  of  five  different  series  of  ex- 
periments upon  the  strength  and  qualities  of  different  sorts  of  timber.  The  experiments  are  detailed 
at  considerable  length  in  Yol.  Y.  of  the  Professional  Papers  of  the  Royal  Engineers.  The  names  of  the 
experimenters  are  given  at  the  top  of  the  columns  in  which  the  mean  results  of  their  experiments  are 
contained. 

W l 

The  transverse  strength  S is  calculated  from  the  common  formula -,  in  which  W is  the  weight  in 

4 a cr 

pounds  necessary  to  break  a beam  of  l length,  a breadth,  and  d depth,  and  supported  at  the  ends  ; oi 
S may  be  taken  as  the  resistance  of  a rod  an  inch  square. 


Table  of  the  Transverse  Strength  of  Timber. 


Names  of  woods. 

OBSERVERS. 

Mean. 

LT.  NELSON,  j 

CAPT.  YOUNG j 

MR.  MOORE. 

MR.  BARLOW. 

LT.  DENISON. 

sp.  gr. 

S. 

sp.  gr. 

s. 

sp.  gr. 

S. 

sp.  gr. 

S. 

sp.  gr. 

S. 

sp.  gr 

S. 

African  Oak 

885 

2484 

962 

2522 

982 

2493 

1024 

2595 

988 

2523 

Ash,  English 

700 

2026 

700 

2026 

kk  American 

oil 

1550 

042 

2041 

626 

1795 

u u Swamp 

925 

1165 

925 

1165 

u “ Black 

533 

861 

533 

801 

Beech,  English 

090 

1550 

696 

1556 

American  White. 

7ii 

ioso 

711 

1380 

“ “ Red... 

778 

1720 

772 

1758 

775 

1739 

Birch,  Common 

711 

1928 

711 

1928 

“ American  Black. . 

6 82 

i848 

649 

1810 

679 

2525 

670 

2061 

u “ Yellow. 

750 

1335 

756 

1335 

Cedar,  Bermuda 

748 

1395 

H'ji 

748 

1443 

Gaudaloupe 

75(3 

2044 

756 

2044 

u American  White. 

3o4 

700 

354 

700 

u of  Lebanon 

330 

1493 

330 

1493 

1013 

605 

551 

579 

782 

u Canada  Rock 

700 

1809 

751 

2072 

725 

1970 

Hickory,  American 

871 

1672 

2447 

786 

2PJ2 

83« 

2205 

831 

2129 

“ “ Bitter  Nut 

871 

1465 

871 

1465 

Oak,  English 

834 

1029 

810 

ioio 

934 

1672 

733 

1 550 

829 

1694 

*•  American  White  . . 

645 

1699 

830 

1699 

872 

1766 

772 

1809 

779 

1743 

“ “ Red 

940 

1709 

964 

1005 

952 

1687 

u li  Live 

1100 

1862 

1160 

1862 

u Adriatic 

7is 

i 509 

993 

1383 

855 

1471 

“ Dantzic 

684 

1579 

756 

1457 

720 

1518 

u Italian 

790 

1688 

796 

1088 

“ Lorraine 

790 

1483 

796 

1483 

u Memel 

727 

1005 

727 

1605 

Pine,  American  White.. 

453 

1456 

iio 

i()73 

432 

1160 

432 

1229 

“ “ Red .... 

621 

1944 

1799 

521 

P289 

657 

i:iii 

500 

1261 

576 

1527 

“ “ Yellow  . 

516 

1188 

553 

1102 

450 

1266 

508 

1185 

“ “ Pitch  . . . 

— 

000 

1632 

820 

1822 

740 

1727 

u Virginia 

590 

1450 

590 

1456 

u Archangel 

551 

1370 

551 

1370 

“ Dantzic 

049 

I486 

649 

1420 

u Memel 

001 

1348 

601 

1348 

u Prussian 

590 

1445 

590 

14-15 

“ Riga 

562 

1687 

740 

i()79 

054 

1383 

Spruce 

503 

1346 

503 

1346 

“ American 

772 

1036 

772 

1036 

Mar-Forest  Fir 

698 

1232 

698 

1232 

Norway  Spar 

577 

1474 

577 

1474 

Deal,  Christiana 

G89 

1502 

089 

1502 

Canada  Balsam 

548 

112;) 

548 

1123 

Hemlock 

911 

1142 

911 

1142 

1958 

542 

995 

408 

1 052 

1335 

u Amer.  or  Tamarak 

433 

911 

433 

911 

Licmum-ViLe 

1082 

2oi:i 

1082 

2013 

Mahogany,  Nassau 

812 

1752 

iyiH 

525 

1503 

068 

1719 

Mangrove,  Bermuda  Bl'k 

1188 

1699 

1188 

1699 

u “ White 

951 

1985 

951 

1985 

Teak 

719 

1898 

723 

1964 

745 

2462 

729 

2108 

Poon 

708 

1687 

579 

2221 

673 

1954 

710 

1867 

Sneeze  wood 

1006 

3305 

1060 

3305 

Yellow-wood 

920 

2103 

926 

2103 

Greenheart 

970 

8471 

1000 

2759 

985 

2615 

Wallaba 

1147 

1643 

1147 

1043 

Bullet-tree 

1075 

2733 

1029 

2651 

1052 

2092 

Kakarally 

1223 

2379 

1223 

2379 

Crab-wood 

648 

1875 

648 

1875 

Locust 

954 

3430 

954 

3430 

Cabacally 

900 

2518 

900 

2518 

Iron-wood 

— 

— 

879 

1800 

879 

1800 

Sott  Maple 

.... 

.... 

075 

1094 

675 

1694 

Remarks. 


i Sr-  e- 

f when  dry. 


S.  Africa. 
W.  Indies. 


676 


SUGAR-MILL,  HORIZONTAL. 


SUGAR-MILL,  HORIZONTAL.  By  M.  Nillus,  of  Havre.  The  figures  furnish  a good  example  ol 
file  form  of  machine  used  for  crushing  sugar-canes,  as  constructed  by  an  eminent  French  engineer,  who 
has  devoted  his  attention,  in  an  especial  manner,  to  the  improvement  of  the  apparatus  used  in  the  colo- 
nies for  the  manufacture  of  sugar.  It  differs  but  slightly  from  the  form  usually  adopted  by  English 
makers.  Many  improvements  have  been  recently  proposed,  but  we  have  preferred  giving  engravings 
of  the  more  simple  and  compact  form  which  is  still  mostly  in  use. 

The  conformation  of  the  sugar-cane  does  not  render  it  necessary  that,  for  the  extraction  of  its  juice, 
the  cells  which  contain  it  should  be  previously  broken,  as  is  the  case  with  sugar  obtained  from  other 
sources;  simple  pressure,  properly  applied,  is  all  that  is  required  for  its  expulsion.  For  this  purpose 
the  canes  are  squeezed  by  being  passed  successively  between  rollers  disposed  somewhat  like  those  of 
a rolling-mill.  In  the  older  form  of  machines  employed  for  the  extraction  of  the  juice,  the  rollers  are 
placed  vertically,  and  it  is  only  within  the  last  few  years  that  this  arrangement  has  been  supersedeo 
by  the  sugar-mill  with  horizontal  cylinders,  which  is  not  only  cheaper  in  construction  and  more  easily 
fixed,  but  by  its  use  the  process  of  feeding  is  performed  with  much  less  labor,  and  at  the  same  time 
more  efficiently. 

Fig.  33C5  represents  a front  elevation  of  the  entire  mill,  showing  the  form  of  the  framing,  and  the 
general  disposition  of  the  cylinders  or  rollers,  and  of  the  feeding-board,  returner,  and  delivering-board. 

Fig.  336(3  is  an  end  view  of  the  same,  showing  the  geering  by  which  the  rollers  are  driven. 


33(36. 


Fig.  3367  is  a half-sectional  plan  taken  on  the  line  v — w,  in  Fig.  3365. 

Fig.  3368  is  a similar  half-section  taken  on  the  line  x — y. 

Fig.  3369  is  a vertical  transverse  section,  through  the  centre  of  the  mill,  exhibiting  the  form  of  section 
of  the  framing  or  standards,  and  the  internal  construction  of  the  top-roller,  with  its  gudgeon  and  bear- 
'UgS; 

Fig.  3370  is  a longitudinal  section  of  the  entire  mill,  in  which  the  arrangement  and  dimensions  of  the 
rollers  and  their  gudgeons,  and  the  disposition  of  the  feeding-board,  returner,  and  delivering-board,  are 
most  distinctly  represented. 


Fig.  3371  is  a longitudinal  section  of  one  of  the  lower  or  feeding  and  delivering  rollers,  and  of  one  ot 
the  driving  pinions. 

Fig.  3372  a front  elevation  of  the  three  driving  pinions,  corresponding  in  position  with  their  respec- 
tive rollers,  as  shown  in  Fig.  3370. 

Fig.  3373  a detached  view  of  one  of  the  stay-bolts  for  strengthening  the  standards. 

Fig.  3374  is  a section  of  part  of  the  feeding-board,  through  the  socket  of  one  of  its  supporting  columns. 

Fig.  3375  is  a section  of  that  part  of  the  standard  through  which  passes  the  screw  for  adjusting  the 
Searings  of  the  feeding  and  delivering  rollers  ; and  Fig.  3376  shows  a face  view  of  one  of  these  bearing; 
themselves. 


SUGAR  MILL,  HORIZONTAL. 


677 


General  description. — The  crushing-rollers  consist  of  three  strong  cast-iron  cylinders  A B C,  mounted 
between  the  two  massive  lieadstocks  or  standards  D D,  and  so  disposed  that  the  periphery  of  the  upper 
roller  A is  nearly  in  contact  with  those  of  both  the  others.  The  rollers  are  made  from  2^  1°  3 inches 
thick,  and  to  give  additional  strength,  are  ribbed  in  the  centre.  They  are  traversed  by  the  strong  mal- 
leable-iron gudgeons  a b c,  fixed  into  their  respective  rollers  by  keys,  in  the  usual  manner,  and  carrying 
at  one  extremity  the  geering  by  which  the  rollers  are  moved.  The  gudgeon  of  the  upper  roller  A is 
made  of  considerably  greater  strength  than  those  of  the  others,  as  it  has  to  sustain  simultaneously  the 
strain  of  both.  The  feeding  and  delivering  rollers  B and  C have  small  flanges  at  their  ends,  between 
which  the  top-roller  is  placed,  as  shown  in  Fig.  3369  ; these  flanges  are  for  the  purpose  of  preventing 
the  pressed  canes  from  working  into  the  mill-bed.  Some  makers  still  continue  the  practice,  once  uni- 
versally adopted,  of  fluting  the  top-roller,  in  order  the  better  to  seize  the  canes,  but  it  is  now  very  gene- 
rally abandoned,  as  it  is  found  that  after  working  some  time,  the  surface  of  the  rollers  becomes  suffi- 
ciently rough  to  bite  the  canes  effectively;  and  the  fluted  rollers  have  this  disadvantage,  that  the  grooves 
carry  round  with  them  a considerable  portion  of  the  expressed  juice,  which  is  speedily  absorbed  by  the 
spongy  canes,  besides  causing  considerable  waste  by  breaking  the  canes  themselves. 

The  standards  D D are  securely  fixed  to  the  strong  cast-iron  sole-plate  E,  which,  besides  performing 
this  function,  is  constructed  of  such  a form  as  to  serve  as  a receptacle  for  the  collection  of  the  expressed 
juice.  For  this  purpose  that  part  of  the  sole-plate  marked  F,  which  lies  between  the  two  standards,  is 
made  to  slope  downwards  from  all  sides,  thus  forming  a species  of  trough  or  cistern,  the  bottom  of 
which  communicates  with  the  gutter  e,  also  cast  of  a piece  with  the  sole-plate,  and  through  which  the 
juice  runs  off  into  the  proper  receptacles.  The  whole  mill  rests  upon,  and  is  bolted  firmly  to  its  foun- 
dation G,  which,  in  the  example  before  us,  consists  of  two  strong  beams  of  timber,  but  more  generally  a 
stone  foundation  is  preferred.  The  bolts///  which  serve  this  purpose,  pass  through  foundation,  sole- 
plate,  and  standards,  so  that  the  whole  are  at  once  bound  together. 


The  standards  D D are  formed  with  indentations  for  the  purpose  of  receiving  the  bearings  H H of  the 
feeding  and  delivering  rollers.  These  bearings  consist  of  a single  brass  bush  for  each  journal,  and  their 
form,  as  well  as  the  mode  of  their  adjustment,  is  shown  detached  from  the  machine  in  Figs.  3375  and 
3376.  To  regulate  the  distance  of  the  rollers  from  each  other,  and  to  compensate  for  the  wear  and  tear 
of  the  bearings,  these  latter  are  so  formed  as  to  be  capable  of  being  moved  to  a greater  or  less  distance 
from  the  centre  of  the  mill,  and  for  this  last  purpose  the  bearings  are  made  of  considerable  thickness  at 
the  points  opposite  to  which  the  strain  is  applied.  A projecting  tongue  on  the  under  side  of  the  brass 
fits  into  a corresponding  groove  in  the  standard,  by  which  means  the  bearing  is  guided  laterally,  and 
its  motion  is  circumscribed  to  the  required  limits  by  a small  projection  d,  cast  upon  the  standard.  A 
small  gutter  g,  which  is  indicated  by  the  dotted  lines  in  the  general  elevation,  is  also  cast  upon  the 
standard  round  the  sole  of  the  bearing,  by  which  the  oil  applied  for  its  lubrication  is  prevented  from  fall- 
ing into  the  mill-bed,  and  is  carried  round  to  the  outside  of  the  mill.  A strong  screw  h passes  through 
the  end  of  the  standard  opposite  to  the  centre  of  each  bearing,  and  works  into  a nut  i sunk  into  it  for 
the  purpose  of  adjusting  the  lower  rollers. 

The  cheeks  1 1 of  the  standards  through  which  the  screws  h h pass,  are  united  to,  and  consolidated 
with,  the  main  body  of  the  lieadstocks,  by  the  strong  bolts  K K,  fixed  to  the  latter  by  cotters,  and  se 
cured  externally  by  nuts,  after  traversing  the  upper  extremities  of  the  cheeks  II  and  the  cast-iron  fer 
ules  k k,  which  serve  to  fill  up  the  intermediate  space.  See  Fig.  3373. 

The  axis  a of  the  upper  roller  revolves  in  the  brass  bearings  L L,  which  consist  of  double  brass  bushes 
fitted  into  the  upper  portion  of  the  standards  D D.  They  are  surmounted  by  the  massive  caps  or  covers 
>1  M,  which  are  retained  in  their  places  by  strong  bolts  N N,  traversing  the  whole  height  of  the  stand- 
ards, and  secured  under  the  sole-plate  by  cotters.  These  bolts  serve  likewise,  by  means  of  the  nuts  n n, 
to  regulate  the  pressure  to  which  it  may  be  thought  expedient  to  subject  the  upper  roller. 

Between  the  lower  rollers  is  placed  a cast-iron  plate  0.  called  the  returner ; it  is  usually  made  con- 
cave upon  its  upper  surface,  and  is  serrated  at  the  edges  to  admit  of  the  free  flowing  of  the  liquor  to 
the  mill-bed.  At  each  extremity  it  is  furnished  with  projecting  tails,  which  pass  through  slots  in  the 


678 


SUGAR  MILL,  HORIZONTAL. 


standards,  and  are  supported  by  the  slips  of  wood  P P,  which  may  be  made  of  greater  cr  less  thickness 
according  as  it  is  found  necessary  to  elevate  or  depress  the  returner.  The  use  of  the  returner  is  to 
direct  the  canes  which  have  been  crushed  between  the  top-roller  A and  the  feeding-roller  C,  so  that  thev 
may  be  again  subjected  to  pressure  between  the  former  and  the  delivering-roller  B. 

The  three  rollers  ABO  are  simultaneously  set  in  motion  by  the  strong  spur-pinions  Q R S,  fixed  by 
keys  upon  the  extremities  of  their  respective  gudgeons  and  geering  together,  as  shown  in  Fig.  3372. 
The  pinion  of  the  upper  roller,  which  communicates  motion  to  the  others,  is  itself  set  in  motion  by  the 
driving-shaft,  through  the  intervention  of  a clutch  or  coupling-box,  fitting  into  the  teeth  q q q,  which  are 
cast  upon  it.  To  provide  for  the  varying  resistance  arising  from  irregular  feeding,  or  from  the  acciden- 
tal crossing  of  the  canes,  by  which  accidents  the  engine  is  liable  to  be  brought  up  so  suddenly  as  to  en- 
danger the  breaking  of  the  fly-wheel  shaft,  it  is  necessary  to  make  all  these  connections  of  unusual  size 
and  weight.  The  best  surface  speed  for  the  rollers  is  3'4  or  3'6  feet  per  minute. 

The  feed-board  P consists  of  a flat  plate  of  cast-iron,  strengthened  by  feathers  on  its  under  surface. 
It  is  set  at  a considerable  inclination,  and  furnished  with  sheet-iron  sides,  and  its  purpose  is  to  convey 
the  canes  regularly  and  equably  from  the  hands  of  the  feeder  to  the  mill.  The  feed-board  rests  upon 
two  cast-iron  columns  1 1,  fixed  by  cotters  at  their  lower  extremities  to  the  edge  of  the  mill-bed.  Fig. 
3374  shows  the  mode  of  their  attachment  to  the  feed-board. 

On  several  sugar  estates  a continuous  system  of  feeding  has  been  recently  adopted,  and  might,  we 
think,  be  generally  employed  with  advantage.  This  consists  of  an  endless  web  of  cloth,  carried  by  two 
parallel  rollers,  on  which  the  canes  are  laid.  One  of  the  rollers  receives  motion  from  the  mill  itself,  and 
consequently  the  cloth  progresses  regularly,  carrying  the  canes  with  it,  and  delivering  them  to  be 
crushed  between  the  feeding  and  upper  rollers.  By  this  means  the  canes  are  all  presented  to  the  action 
of  the  rollers  in  a longitudinal  direction,  and  in  the  most  equable  and  regular  manner  ; whereas,  when 
spread  on  the  hopper  by  the  hands  of  the  negroes,  the  quantity  admitted  is  sometimes  too  large  and 
sometimes  too  small,  which  has  the  disadvantage,  in  the  one  case,  of  permitting  a portion  of  the  canes 
to  pass  between  the  rollers  without  receiving  the  due  amount  of  pressure,  and  in  the  other  of  unneces- 
sarily straining  the  mill. 

The  delivering-board  U,  by  which  the  crushed  canes  are  withdrawn  from  the  mill  after  the  juice  has 
been  expressed,  consists,  like  the  feed-board,  of  a cast-iron  table,  set  at  a great  angle,  and  fitted  close  to 
the  delivering-roller  B,  so  as  to  detach  any  small  portions  of  the  canes  that  may  adhere  to  it,  and  might 
otherwise  mix  with  the  liquor.  It  is  made  so  as  to  turn  upon  pivots  at  the  top  of  the  small  columns  u it 
which  support  it. 

Action  of  the  machine. — The  action  of  the  sugar-mill  is  so  obvious  as  scarcely  to  require  to  be  spe- 
cially noticed.  The  sugar-canes,  having  been  previously  cut  into  short  lengths  of  about  three  feet,  are 
brought  to  the  mill  tied  up  in  small  bundles;  there  the  feeder  unites  them,  throws  them  on  the  feed 
board  T,  and  spreads  them  so  that  they  may  cross  each  other  as  little  as  possible.  They  are  drawn  in 
between  the  feeding  and  top  rollers  A and  C,  where  they  are  split  and  slightly  pressed  ; the  liquor 
flows  down  and  is  received  into  the  mill-bed  F,  while  the  returner  O guides  the  canes  between  the  top 
and  delivering  rollers  A and  B,  where  they  receive  the  final  pressure,  and  sliding  down  the  delivering- 
board  U,  are  turned  out  on  the  floor  of  the  mill,  while  the  liquor  runs  back  and  falls  into  the  mill-bed. 

When  circumstances  will  admit  of  it,  it  is  desirable  that  the  mill  should  be  situated  at  such  an  eleva- 
tion above  the  rest  of  the  sugar  apparatus  as  to  render  it  unnecessary  to  raise  the  juice  which  flows 
through  the  gutter  e by  pumping,  as  the  contact  of  the  air  occasioned  by  the  agitation  of  the  liquor  in 
the  pump-barrels  tends  to  throw  it  into  a state  of  fermentation.  In  very  many  cases,  however,  a pump 
is  attached  to  the  sugar-mill,  and  is  worked  by  suitable  geering  affixed  to  the  gudgeon  a of  the  upper 
roller,  wliich  in  our  figures  is  shown  of  sufficient  length  to  effect  this  purpose  if  required. 

Literal  References.  , 

A,  the  upper  roller  or  cylinder. 

«,  the  gudgeon  or  shaft  of  the  upper  roller,  upon  which  it  is  fixed  by  keys. 

B 0,  the  delivering  and  feeding  rollers. 

b c,  their  respective  gudgeons. 

D D,  the  standards  or  headstocks  of  the  mill. 

d d,  small  projections  thereon  for  guiding  the  bearings  of  the  rollers  B and  C. 

E,  the  sole-plate,  to  which  the  standards  D D are  fitted,  and  which  is  also  formed  intc 

F,  the  mill-bed,  into  which  the  expressed  liquor  flows. 

e,  the  gutter  for  withdrawing  the  liquor  from  the  mill-bed. 

fff  6)e  holding-down  bolts  of  the  mill. 

G G,  strong  beams,  forming  the  foundation  of  the  mill. 

g g , gutters  for  withdrawing  the  superfluous  oil  from  the  bearings  of  the  rollers  B and  C. 

H H,  brass  bushes,  forming  the  bearings  of  the  rollers  B and  0. 

hh,  regulating  screws  for  the  adjustment  of  the  rollers  B and  C 

% i,  their  nuts,  sunk  into  the  framing. 

1 1,  the  cheeks  of  the  framing,  traversed  by  the  screws  li  h. 

K K,  cotter-bolts,  for  strengthening  the  cheeks  1 1. 

k k,  cast-iron  ferules  on  tiie  bolts  K K. 

L L,  the  brass  bearings  of  the  top-roller. 

M M,  the  plummer-block  covers  of  the  top-roller. 

N N,  the  plummer-block  cover  bolts,  which  also  regulate  the  pressure  upon  the  top-roller  by  meara 
jt  the  nuts  n n. 

O,  the  returner,  fixed  between  the  lower  rollers,  and  serrated  at  each  edge. 

P P small  slips  of  wood  for  supporting  the  returner. 


SUGAR  BOILERS. 


6 <9 


Q,  a stroDg  spur-pinion  on  the  gudgeon  of  the  top-roller.  On  its  face  are  also  cast  the  projections 
q q q,  engaging  with  similar  projections  on  the  coupling-box  of  the  driving-shaft. 

RS,  spur-pinions  on  the  gudgeons  of  the  lower  rollers,  geering  with  the  pinion  Q. 

T,  the  feed-board. 

1 1,  small  columns  for  supporting  the  feed-board. 

U,  the  delivering-board,  fitted  with  hinge-joints,  to  admit  of  its  turning  upon 
u u,  the  small  columns  upon  which  it  is  supported. 


3377. 


Fig.  3377  represents  a five-roller  sugar-mill  built  by  Nellius  in  France  for  the  French  colonies. 

The  mills  used  for  grinding  the  cane  are  generally  placed  ten  to  twelve  feet  from  the  ground,  in  ordei 
!o  give  sufficient  fall  for  the  juice  to  flow  into  the  juice-boxes,  and  from  them  into  the  kettles. 


3378. 


The  thickness  of  the  shell  of  the  rollers  in  those  mills  constructed  by  Leeds  & Co.,  New  Orleans 
represented  in  Fig.  3378,  varies  from  2^  to  3 inches,  according  to  size ; the  depth  of  the  eye  of  the 
roller  is  12  inches  in  all  these  mills.  The  shafts  are  of  wrought-iron.  The  journals  vary  in  size 
from  7J  to  8J  inches  in  diameter.  The  boxes  in  which  the  journals  revolve  are  of  brass,  lined  with 
“ Babbitt’s  metal.”  The  return  plats,  about  which  there  is  a great  difference  of  opinion  respecting  their 
proper  position,  are  placed  from  one  to  two  inches  below  the  top-roller.  The  cane-carrier  is  from  fifty 
to  ninety  feet  in  length,  according  to  the  height  at  which  the  mill  is  placed. 

SUGAR  BOILERS,  Reed’s  improved.  The  art  of  making  sugar  consists  in  separating  the  crystal- 
lizable  sugar  from  the  liquor  of  the  cane.  This  liquor  often  contains  more  than  70  per  cent,  of  its 
weight  of  sugar,  and,  in  some  instances,  this  amount  has  been  extracted  from  the  cane.  Sugar  is  also 
obtained  from  the  beet,  the  maple,  the  melon,  the  carrot,  the  turnip,  the  green  Indian  corn  plant,  and 
from  many  other  substances.  Extensive  manufactories  of  beet  sugar  are  now  in  operation  on  the  con- 
tinent of  Europe,  and  in  our  forests  vast  quantities  of  maple  sugar  are  annually  manufactured. 

Fig.  3379  is  a view  and  description  of  parts  of  Mr.  Knight  Reed’s  patent  Flue  Boiling  Sugar  Pans,  to 
whom  was  awarded  a silver  medal,  by  the  American  Institute,  at  the  late  Fair  of  October,  1850. 
ABC,  boilers.  D E,  clarifiers.  F G H 1 1,  flues.  J K L M N",  stopcocks  for  drawing  off  syrup.  0,  stop- 
;ock  for  drawing  off  syrup  from  striking-teache.  P,  damper  between  striking-teache  and  second  boiler. 
R.  damper,  closing  flues  to  striking-teache.  S,  door  for  draft.  7’,  damper  for  shutting  oft’  fire  from  flues 
So  striking-teache.  U J stop-cock  for  drawing  off  washings.  V,  damper  for  shutting  off  the  tire  from 


580 


SUGAR  BOILERS. 


going  directly  under  the  clarifiers,  sending  the  draught  through  the  teache  and  all  the  boilers.  W W 
dampers  for  shutting  off  draught  from  clarifiers  D E.  XXX,  feeding-doors  to  the  boilers.  Y Y,  feediug 
doors  to  clarifiers.  Z Z Z,  doors  for  drawing  the  ashes  from  under  the  boilers. 

The  sugar-cane  is  twice  subjected  to  the  action  of  the  mills,  or  is  passed  through  two  sets  of  rollers 
of  which  the  second  pair  are  adjusted  more  closely  together  than  the  first.  By  this  process,  the  sugar- 
cane comes  out  from  the  rollers  nearly  dry,  but  some  juice  is  still  retained  by  the  capillary  forces  ol 
the  plant,  and  cannot  be  entirely  separated  from  it  by  any  degree  of  pressure.  The  liquor  thus  pro- 
duced soon  undergoes  fermentation  if  left  to  itself,  and  by  very  slight  causes  is  changed  into  substances 
of  a nature  entirely  different  from  the  pure  solution  of  sugar,  of  which  it  at  first  consisted.  Among 
these  substances  are  mucilage,  lactic  acid,  alcohol,  and  carbonic  acid.  To  prevent  this  change  by  fer- 
mentation, the  liquor,  as  soon  as  possible  after  it  is  expressed  from  the  cane,  is  exposed  to  a high  heat. 
This  checks  its  tendency  to  ferment. 

As  it  comes  from  the  mill,  the  juice  is  passed  through  a sieve  or  coarse  cloth,  to  separate  the  coarse 
6olid  feculencies.  It  then  flows  from  the  mill-bed  into  channels  through  which  it  is  conducted  to  re- 
ceivers. These  are  generally  two  in  number,  placed  in  a situation  as  cool  as  possible,  to  diminish  the 
tendency  of  the  liquor  to  ferment.  They  are  also  usually  on  a higher  level  than  the  boiling-house. 


The  crushed  cane-stalks  are  carried  from  the  mill  to  the  trash-house,  which,  on  large  plantations,  is  a 
building  about  one  hundred  feet  long,  eighteen  feet  wide,  and  fourteen  feet  high.  In  these  the  cane- 
trash  is  carefully  spread  out,  and  means  taken  to  render  it  perfectly  dry.  When  dry  it  is  employed 
as  fuel. 

When  the  receiver,  is  filled  with  cane-liquor,  a valve  is  opened,  and  the  liquor  flows  out  through  a 
channel  lined  with  sheet-lead,  into  the  clarifiers  D and  E,  Fig.  3379.  In  the  ordinary  method,  a fire  is 
lighted  under  these  clarifiers,  and  lime  is  stirred  into  the  cane-juice.  The  liquor  soon  becomes  heated, 
and  the  temperature  gradually  rises  till  the  thermometer  stands  at  about  210°.  As  the  heat  increases, 
minute  bubbles  of  air  make  their  appearance,  and  a greenish-gray  scum  forms  upon  the  surface  of  the 
liquor.  The  temperature  is  not  allowed  to  rise  to  the  boiling  point,  as  the  motion  thus  produced  in  the 
liquor  would  break  the  scum  at  the  top,  and  mingle  it  again  with  the  fluid  by  carrying  down  the  fecu- 
lencies which  had  risen  to  the  top.  In  about  forty  minutes,  the  scum  attains  a thickness  which  causes 
it  to  “ crack,”  or  to  divide  into  white  froth,  as  watery  vapor  rises  up  and  forces  its  way  through.  Wheu 
this  is  observed,  the  liquor  is  skimmed  for  about  ten  or  twelve  minutes,  after  which,  if  circumstances 
will  admit  of  the  delay,  the  fire  is  damped,  and  the  cane-liquor  is  allowed  to  remain  undisturbed  in  the 
<Tu  ifiers  for  twenty  or  thirty  minutes,  or  even  longer,  during  which  period  there  ensues  a more  com 


SUGAR  BOILERS. 


681 


plete  separation  and  rising  of  the  impurities.  This  process  is  called  clarifying,  because  in  this  way 
the  greater  part  of  the  feculencies  is  removed. 

From  the  clarifiers  the  liquor  is  drawn  off  by  stop-cocks  M and  N,  (in  Reed’s  process ; various  methods 
are  employed  in  other  processes.)  These  stop-cocks  are  placed  at  such  a distance  from  the  bottom 
that  about  one-twentieth  of  the  liquid  will  remain  in  the  boiler.  In  some  cases  the  boiling-house  is  fur- 
nished with  only  one  clarifier ; in  general,  however,  two  or  three,  and  in  some  large  establishments 
four  are  employed.  The  boiling-house  of  an  estate  in  Jamaica,  which  produces  400  hogsheads  of  sugar 
annually,  is  provided  with  three  clarifiers,  each  of  440  gallons  capacity,  one  grand  evaporator  of  equal 
magnitude,  one  of  300  gallons,  another  of  180  gallons,  and  another  of  90  gallons,  wine  measure. 

From  the  clarifiers  the  liquor  passes  into  the  first  evaporator  C,  which,  in  Reed’s  arrangement,  holds 
about  400  gallons.  Flere  the  juice  is  allowed  to  boil.  This  boiling  separates  a kind  of  feculencies 
which  could  not  be  separated  by  gentle  heat,  and  which,  therefore,  were  not  removed  in  the  clarifiers. 
The  scum,  as  it  rises,  is  carefully  removed  by  scummers.  When,  in  this  way,  the  cane-liquor  is  im- 
proved in  quality,  thickened  to  a syrup,  and  reduced  about  two-thirds  in  quantity,  it  is  then  drawn  off 
into  the  second  and  smaller  evaporator  B.  This  evaporator  holds  about  200  gallons.  New  liquor  may 
now  be  admitted  from  the  clarifiers  into  C.  The  syrup  from  C.  is  concentrated  still  further  in  B,  and 
then  drawn  off  into  the  last  evaporator  A.  This  evaporator  is  technically  called  the  tcache.  In  this 
the  syrup  is  concentrated  to  the  requisite  degree  for  crystallizing.  This  is  called  the  striking-point, 
and  the  concentrated  syrup  the  strike , while  striking  is  an  operation  performed  in  a set  of  wooden  ves- 
sels or  wooden  vats,  not  represented  in  the  figure.  These  are  made  of  cypress  planks,  and  are  very 
shallow,  measuring  from  four  to  five  feet  in  width,  by  twelve  to  fourteen  inches  in  depth.  Not  less 
than  six  of  these  are  used  with  one  set  of  kettles,  and,  in  general,  a sugar-house  contains  eight  or  ten, 
or  even  a greater  number.  They  are  called  coolers,  for  the  liquor  is  removed  from  the  teache  and 
poured  into  these  vessels  to  cool.  Their  size  is  such  that,  when  filled,  the  syrup  will  cool  at  that  rate 
which  is  most  favorable  to  a proper  crystallization  of  the  sugar.  The  more  gradually  the  syrup 
cools  the  larger  will  be  “ the  grain”  of  the  sugar,  and  the  more  easily  will  the  molasses  be  drained 
from  it. 

The  degree  of  concentration  of  the  syrup  is  determined  by  several  methods,  of  which  the  best  is 
called  the  proof  by  touch.  A small  portion  of  the  syrup  is  taken  from  a ladle  or  stirrer  on  the.  end  of 
the  thumb,  and  the  middle  finger  is  then  brought  in  contact  with  it,  and  again  separated  from  it.  If, 
in  this  case,  two  drops  of  liquid  separate,  that  on  the  thumb  below  being  the  larger,  the  concentration 
is  as  yet  weak.  If  the  drops  become  nearly  equal  and  do  not  separate  until  the  finger  and  thumb  are 
drawn  widely  apart,  the  concentration  is  stronger.  The  third  state  of  concentration  is  where,  by  the 
separation  of  the  finger  and  the  thumb  half  an  inch,  a thread  is  drawn  out,  which  finally  breaks  below ; 
the  end  of  the  thread  becomes  club-shaped,  and  rises  slowly  towards  the  finger.  In  the  fourth  stage, 
the  same  thing  occurs  at  a greater  distance,  the  end  is  folded  backwards,  and  the  thread  has  the  form 
of  a ribbon  or  long  strip,  which  rises  more  rapidly  than  before.  In  the  fifth  and  last  degree  of  concen- 
tration, after  a greater  separation,  the  thread  breaks,  being  very  fine  at  the  end  which  turns  aside  and 
twists  up  like  a cork-screw.  It  does  not  fold  itself  upon  the  upper  part  of  the  thread  as  before.  A 
little  mote  concentration  prevents  the  thread  from  shrinking  at  all  upon  itself. 

The  scum  which  is  removed  from  the  cane-liquor  and  syrup  is  taken,  together  with  the  feculencies 
collected  in  the  clarifiers,  to  the  still-house,  where  it  is  converted  into  spirit.  The  furnace  is  maintained 
at  a uniform  heat,  day  and  night,  from  the  commencement  of  the  grinding  season  in  November,  till  its 
conclusion  in  January,  stopping  only  a few  times  that  the  kettles  may  be  scraped  from  the  accumula- 
tion of  rust,  lime,  and  earthy  impurities,  which  collect  upon  them,  and  which,  if  not  occasionally  re- 
moved, cause  them  to  crack. 

From  the  coolers  the  sugar  is  taken  to  the  curing-house,  which  is  a large  building  contiguous  to  the 
boiling-house.  In  a cavity  in  the  lower  part  of  the  curing-house  is  the  molasses  cistern.  Over  this  cis- 
tern and  on  the  floor  of  the  boiling-house,  is  an  open  frame-work  of  strong  joists,  leaving  a gangway  in 
the  middle.  Upon  these  joists  are  supported  a series  of  hogsheads,  into  which  the  sugar,  when  suffi- 
eiently  crystallized  in  the  coolers,  is  removed,  and  the  molasses  drained  off  through  holes  in  the  bottom. 
This  molasses  flows  through  a trough  below  into  the  cistern.  The  curing-house  is  built  so  capacious  as 
to  hold  all  the  sugar  which  can  be  made  in  three  or  four  weeks,  or  till  it  is  freed  from  the  greater  part 
of  its  molasses.  Some  molasses  will  always  remain  entangled  in  the  crystals  of  sugar,  but  when  tol- 
erably dry,  the  sugar  is  removed  from  the  curing-house  for  shipment.  The  sugar  thus  manufactured 
is  called  muscovado  or  raw  sugar,  and  is  the  material  used  by  sugar-refiners  in  making  white  or  loaf- 
sugar. 

Description  of  Reeds  sugar  boilers,  with  the  method  of  preparing  them  for  use. — In  every  process 
for  the  manufacture  of  sugar,  there  must  be  a series  of  boilers,  evaporators,  coolers,  and  the  other 
arrangements  which  have  already  been  described.  The  peculiarity  of  Reed’s  boilers  consists  chiefly  in 
the  mode  in  which  the  fire  is  applied. 

In  Fig.  3380,  d is  a valve  which  closes  either  the  flue  de  or  the  open  passage'  represented  by  the 
bent  arrow.  Another  valve  e is  represented  as  open,  which,  when  let  down,  closes  the  flue  e d.  The 
valve  c affords  a direct  communication  with  the  chimney  through  the  flue  c a h.  The  valves  c and  a 
being  opened,  the  fire  is  kindled  beneath  boilers  Nos.  2 and  3,  on  the  grate  m n.  When  the  fire  is 
sufficiently  kindled,  the  valve  c is  shut,  e is  opened,  as  shown  in  the  figure,  d is  shut  down  over  the 
space  represented  by  the  bent  arrow,  and  thus  the  heat  from  the  fire  passes  down  beneath  the  teache, 
and  then  turns  upwards,  as  shown  by  the  bent  arrow  e,  through  the  flue  ed,  and  passes  on  through  the 
flues  beneath  Nos.  3 and  '2.-  If  the  valve  b is  thrown  entirely  open  the  heat  will  ascend  through  the 
grate  immediately  above,  and  pass  around  in  the  flue  under  No.  1,  and,  descending  in  the  direction  rep 


* These  flues  pass  through  the  boilers. 


682 


SUGA.R  BOILERS. 


resented  by  the  bent  arrow,  will  finally  pass  through  the  flue  a A into  the  chimney.  Two  valves  are 
represented  by  the  letter  a,  and  two  by  the  letter  b,  corresponding  to  the  two  clarifiers  represented  by 
No.  1.  The  object  of  this  double  arrangement  is  to  shut  off  the  heat  from  either  clarifier,  according  to 
circumstances. 


* 


The  flue  eel  passes  through  the  teache  and  is  composed  of  a series  of  pipes,  as  represented  at  I' , ir 
Fig.  3879.  The  valve  e is  so  constructed  as  to  close  all  these  pipes,  and  corresponds  to  the  valve  R, 
in  Fig.  3379.  The  valve  d is  made  in  the  same  way.  The  flues  beneath  Nos.  3 and  2 pass  through 
these  boilers,  as  represented  in  G-  and  H,  in  Fig.  3379.  The  flue  beneath  No.  1 has  a different  con- 


SUGAR  BOILERS. 


635 


st-ruction.  In  this  two  large  pipes  pass  through  each  clarifier,  as  is  shown  at  ffff  Fig.  3380.  By 
the  valve  b the  fire  may  at  any  time  be  entirely,  or  in  part,  cut  off  from  the  clarifiers,  and  by  the  valve 
e from  the  teache. 

The  remaining  arrangements  are  represented  in  Fig.  3319.  XXX  W are  doors  opening  to  the  fur- 
nace, by  which  a fire  may  at  any  time  be  kindled  directly  under  each  of  the  boilers  or  under  the  clari- 
fiers. Z Z Z are  doors  for  removing  ashes  from  under  the  boilers.  O is  a stop-cock  for  drawing  oil 
syrup  from  the  teache.  The  stop-cocks  for  drawing  off  the  syrup  from  the  other  boilers  have  been 
already  mentioned. 

To  prepare  the  boilers  for  use. — AB  and  0 are  at  first  nearly  filled  with  water,  D and  E are  filled 
with  cane-juice.  The  fire  is  then  kindled,  and  the  heat  is  made  to  pass,  as  described  above,  through 
all  the  boilers,  and  one  of  the  clarifiers  D,  but  not  through  the  other,  E.  When  the  cane-liquor  in  D is 
heated  nearly  to  the  boiling  point,  the  heat  is  cut  off  from  this  and  made  to  pass  through  E.  The 
water  is  now  drawn  off  from  boiler  C,  and  the  clarified  cane-juice  from  D is  drawn  off  into  this  boiler 
L)  is  then  again  filled  with  cane-liquor. 

When  the  cane-liquor  in  Eds  sufficiently  clarified,  the  contents  of  C are  drawn  off  into  B,  the  watei 
of  which  has  been  previously  removed.  The  liquor  from  E is  then  drawn  off  into  C,  and  E is  filled 
with  fresh  cane-juice. 

The  liquor  from  D being  ready  to  be  drawn  off  again,  the  water  is  removed  from  the  striking-teaehe 
A,  and  the  syrup  is  drawn  from  B to  A,  from  C to  B,  and  from  D to  C.  I)  is  filled  with  fresh  cane- 
juice,  and  all  the  boilers  are  now  in  operation.  When  the  syrup  in  A is  sufficiently  concentrated,  the 
fire  is  cut  off  from  this  boiler  by  raising  the  valve  d.  Fig.  3380.  The  syrup  is  allowed  to  remain  in  the 
teache  for  a few  moments  till  it  is  somewhat  cooled,  and  is  then  drawn  off  except  3 or  4 inches  at  the 
bottom. 

Advantages  of  Reed’s  Boilers.  1.  Economy  of  fuel. — In  most  of  the  tropical  countries  where  sugar 
is  made,  fuel  has  become  scarce  ; hence  the  great  object  of  the  planter  is  so  to  arrange  his  works  as  to 
economize  fuel.  The  usual  arrangement  for  this  purpose,  is  of  a series  of  boilers  in  a horizontal  flue. 
The  heat  of  the  fire  is  thus,  to  a great  extent,  abstracted  before  it  arrives  in  the  flue.  The  saving  of 
fuel,  in  Reed’s  arrangement,  is  produced  by  cutting  off  the  fire  when  it  is  not  needed. 

Mere  position  cannot  adapt  the  boilers  to  the  different  degrees  of  heat  which  they  require,  for  there 
is  no  gradation  in  this  respect.  When  the  liquor  is  first  introduced  into  the  clarifiers,  a great  amount 
of  heat  is  frequently  necessary,  on  account  of  the  large  quantity  of  water  which  the  cane-juice  contains. 
But,  as  the  evaporation  proceeds,  the  amount  of  heat  required  diminishes.  In  the  striking-teaehe, 
also,  it  is  equally  important  to  be  able  to  diminish  or  cut  off  the  heat  at  once.  This  is  easily  managed 
in  Reed’s  method,  and,  at  the  same  time,  the  heat  is  not  lost,  but  is  applied  immediately  to  the  evap- 
orators Nos.  2 and  3,  Fig.  3380. 

2.  Economy  of  time. — On  many  plantations,  and  on  all  at  certain  times,  it  is  far  more  important  to 
hasten  the  conversion  of  cane-juice  into  sugar,  even  if  this  is  done  imperfectly,  than  to  obtain  a more 
perfect  article  with  a greater  expenditure  of  time.  It  is  often  far  more  profitable  to  make  a large 
quantity  of  rather  inferior  sugar,  than  a smaller  amount  of  the  first  quality. 

Economy  of  time  is  important  in  another  respect.  It  has  been  ascertained  that  sugar  is  rendered 
dark  and  uncrystallizable  more  by  the  duration  of  boiling  than  by  the  intensity  of  the  heat  employed. 
Slow  evaporation  by  steam,  for  instance,  instead  of  producing  a better  result,  gives  very  dark  and  un- 
crystallizable syrups.  A rapid  evaporation  in  6 or  8 minutes,  in  the  usual  evaporating  pan,  renders  less 
of  the  sugar  uncrystallizable,  than  a slow  evaporation  in  the  same  pan  continued  for  40  or  50  minutes. 
The  same  effect  lias  been  found  to  take  place  even  in  the  vacuum  process,  where  the  sugar  is  boiled 
at  a very  low  temperature. 

Reed’s  process  secures  this  advantage  in  three  ways.  (1.)  Evaporation  takes  place  much  faster 
when  the  heat  is  distributed  through  the  syrup  by  pipes,  than  when  it  is  applied  to  the  flat  or  round 
bottom  of  the  common  boiler.  For  this  reason  steam-pipes  are  introduced  into  the  syrup,  in  the  vacuum 
process,  besides  the  steam  which  fills  the  double  bottom  of  the  boilers  used  in  this  process,  and  commu- 
nicates heat  from  beneath.  (2.)  A much  higher  degree  of  heat  can  be  used  in  this  method  than  in  the 
one  generally  employed.  In  the  common  boiler,  as  the  heat  of  the  fire  acts  directly  on  the  flat  or 
round  bottom,  the  greatest  care  is  necessary  to  prevent  the  sugar  from  being  burnt,  or  from  being  ren- 
dered uncrystallizable.  If  a high  heat  is  employed,  it  is  impossible  to  prevent  this  effect  from  taking 
place  to  a greater  or  less  extent.  But,  by  distributing  the  heat  through  the  syrup,  as  in  Reed’s  pro- 
cess, the  danger  from  this  source  is  entirely  removed.  (3.)  The  whole  arrangement  is  so  easily  man 
aged  by  dampers,  &c.,  that  the  five  evaporating  pans  will  require  no  more  attendance  than  one  of  the 
ordinary  boilers.  Much  labor  will  thus  be  saved  when  it  is  most  important  to  economize  labor  in  the 
hurry  of  gathering  the  crop  and  converting  the  cane-juice  into  sugar. 

Simplicity  of  construction. — Compared  with  the  other  methods  by  which  sugar  is  made  in  tolerable 
perfection,  this  is  remarkable  for  the  simplicity  of  its  construction.  The  vacuum  processes  of  Howard 
and  others  require  a steam-engine,  and  are  very  complicated  in  all  their  parts.  Only  large  plantations 
can  employ  these  methods,  on  account  of  their  great  expense,  and  the  skilful  hands  required  to  work 
them.  The  amount  of  sugar  manufactured  must  be  great  to  pay  the  interest  on  the  cost  of  these  ar- 
rangements. The  entire  cost  of  Reed’s  boilers  will  not  very  greatly  exceed  that  of  the  arrangements 
now  generally  employed,  while  it  will  be  much  less  liable  to  accident.  It  can  be  managed  by  common 
hands,  as  it  requires  less  skill  than  even  the  common  methods  of  making  sugar.  (Prof.  A.  F.  Olmsted.) 

Two  vacuum-pans. — This  mode  of  boiling  sugar  requires  a careful  defecation  and  filtration  of  the  juice 
and  syrup  through  animal  charcoal.  The  cane-juice,  after  having  been  defecated,  is  passed  through 
bone-black  filters,  collected  in  a vat  from  which  the  first  vacuum-pan  is  supplied;  when  the  cane-juico 
is  concentrated  therein  to  28°  or  29°  of  Beaume,  or  thereabouts,  it  is  drawn  off  into  a vat  from  whence 
the  concentrated  juice  is  passed  again  through  bone-black  filters,  collected  into  a proper  vat  from  which 


684 


SUGAR  BOILERS. 


the  second  vacuum-pan  is  supplied,  where  it  is  then  brought  to  the  striking  point.  The  vacuum-pans 
used  in  this  mode  of  boiling  are  like  those  described  under  the  mode  of  boiling  in  open  kettles  and 
vacuum-pans ; they  are  heated  with  low-pressure  steam,  and,  consequently,  the  burning  of  the  concen- 
trated saccharine  liquid  is  thereby  obviated.  When  the  operations  of  defecation,  filtering,  and  boiling 
are  well  managed,  the  sugar  is  equal  in  every  respect  to  any  made  in  any  apparatus  of  the  most  im- 
proved method.  By  this  mode  of  boiling  sugar  the  consumption  of  fuel  is  as  great  as  with  common  ket- 
tles. These  kinds  of  vacuum-pans  require  a great  quantity  of  fresh  water  for  condensing;  and  in  places 
where  water  is  scarce,  vacuum-pans  of  this  description  cannot  be  employed. 

Degrand's  apparatus. — Degrand’s  system  consists  of  a condenser.  The  vapors  arising  from  the  juice 
or  syroD  boiled  in  a vacu»m-pan  and  condensed  by  means  of  a serpentine  tube,  over  which  a film  of  cold 
juice  is  continually  kept  flowing,  which  absorbs  the  latent  heat  of  the  vapor  within  the  tube,  and  a por- 
tion of  the  water  from  the  juice  passes  off  as  vapor  in  the  air.  Degrand's  condenser  serves  the  double 
purpose  of  a condenser  and  evaporator. 

There  are  only  two  of  Degrand’s  apparatus  in  Louisiana.  They  were  constructed  at  the  Novelty 
Works,  New  York,  and  are  more  commonly  known  as  Derosne’s  apparatus;  but  Mr.  Degrand  is  the 
eal  inventor  and  patentee  of  this  apparatus,  and  Derosne  it  Cail  are  only  the  constructors  and  assignees 
jf  his  apparatus  for  the  north  of  France  and  the  colonies. 


The  Degrand  apparatus  in  operation  in  Louisiana  have  vacuum-pans  with  a very  large  heating  sur- 
face, and  heated  with  low-pressure  steam ; the  air-pumps  are  larger  than  those  used  in  the  Island  of 
Cuba.  The  artificial  draught  of  air  is  not  made  use  of  here,  but  the  same  result  is  obtained  by  the  in- 
jection of  water  between  the  condenser  and  air-pump ; this  increases  somewhat  the  consumption  of  fuel, 
but  the  vacuum  obtained  in  that  way  is  as  perfect  as  by  means  of  the  draught  of  air ; and  the  sugar 
made  with  this  apparatus  is  as  good  as  any  made  in  Louisiana. 

In  the  beet-sugar  manufactories  in  Germany  the  manufacturers  were  beginning  to  abandon  its  use,  in 
consequence  of  the  practical  difficulties  in  distributing  the  beet-juice  regularly  over  the  serpentine;  and 
in  case  one  of  the  many  tubes  which  form  the  serpentine  has  the  slightest  deviation  from  the  straight 
line,  the  juice  will  concentrate  more  at  such  depressions,  and  disturb  the  regular  distribution  of  juice 
over  the  tubes.  When  a leak  happens,  the  juice  or  syrup  is  rapidly  absorbed  into  the  interior  of  the 
tube  on  account  of  the  vacuum,  and  causes  a considerable  loss.  It  is  likewise  found  that  the  economy 
of  water  for  condensing  is  not  so  great  as  was  anticipated,  and  finally  it  was  concluded  to  return  to  the 
former  plan  of  boiling  in  common  vacuum-pans. 

The  consumption  of  fuel  by  a Degrand's  apparatus  is  If  to  2 cords  of  wood  for  every  1000  pounds 
of  sugar  produced.  In  the  Island  of  Cuba  this  apparatus  takes  off  the  wdiole  crop  with  the  bagasse 
alone  ; however,  some  require  great  quantities  of  wood  besides  the  bagasse. 

Mr.  Derosne  obtained  a patent  in  Europe  in  1836,  and  in  America  in  1845. 

The  following  description  of  the  mode  of  working  his  apparatus  is  taken  from  his  patent. 

The  juice  which  is  taken  from  the  mills  is  defecated  in  pans  or  boilers,  a row  of  which  is  shown  at 
fff  Fig.  3382.  In  Fig.  3381,  the  elevation  of  one  of  these  boilers,/,  is  represented.  The  juice  from 
the  mill  passes  into  a reservoir  d,  that  is  connected  by  a pipe  d'  with  an  air-tight  cylinder  e,  in  which 
pipe  there  is  a stop-cock  that  is  turned  by  a long  handle  d",  by  turning  which  the  cylinder  e can  be 
filled,  and  the  communication  can  be  afterwards  cut  off  by  admitting  steam  from  the  generators  or  boil  ■ 
ers,  (shown  in  Fig.  3382,  G,  in  dotted  lines,  that  supplies  steam  to  the  engines  and  heating  apparatus  or 
the  whole  manufactory,)  into  the  top  of  the  cylinder  e.  The  juice  is  forced  through  a pipe  e',  in  the 
bottom  of  said  cylinder,  up  into  the  clarifying  boilers/,  which  is  constructed  wfith  a double  bottom,  be- 
tween which  steam  is  admitted  by  the  tube  a'  from  the  generator  ; the  condensed  water  being  returned 
to  the  boilers  by  a force-pump  through  the  pipe  b' . The  construction  is  common,  but  the  employment 


SUGAR  BOILERS. 


085 


of  the  series  of  these  pans,  for  this  purpose,  has  never  before  been  done,  or  the  juice  cl'tified,  as  about 
to  be  described. 

When  the  cane-juice  has  reached  the  point  proper  for  receiving  the  clarifying  mixture,  which  point  is 
from  60°  to  63°  of  Beaume,  it  is  added.  This  composition  is  made  by  a compound  of  the  sulphate  of 
alumine  of  the  cheapest  character,  either  with  or  without  the  presence  of  iron,  which  is  formed  by  mix- 
jng  sulphuric  acid  with  aluminous  earth,  and  adding  thereto  lime,  potash,  or  other  similar  salt,  and  a 
quantity  of  liquified  blood,  either  fresh  or  dried,  being  incorporated  into  the  precipitate.  This  is  united 
with  the  juice  by  carefully  stirring  it  while  pouring  in  the  mixture,  and  clarifies  it;  or,  instead  of  this, 
dme  alone  can  be  used,  as  in  the  former  processes,  the  quantity  being  much  greater  than  that  used  in 
the  old  colonial  mode  of  proceeding,  as,  in  this  system,  there  is  nothing  to  fear  from  an  excess  of  lime, 
which  a subsequent  part  of  the  process  perfectly  corrects  to  any  extent  that  it  may  have  been  found 
necessary  to  use  it,  in  order  to  obtain  a good  clarification.  The  steam  is  kept  on  until  the  juice  begins 
to  boil,  and  when  this  point  is  reached,  the  steam  is  cut  off.  The  result  of  this  is,  where  the  mixture  is 
used,  that  at  the  top  of  the  boiler  ff  a thick  and  solid  coat  of  scum  is  formed,  and  only  a very  small 
quantity  of  matter  is  precipitated  to  the  bottom  of  the  boiler.  In  a few  minutes  the  liquor  will  have 
become  clear,  and  can  be  drawn  off'  through  a tube  m,  by  turning  a cock  in  the  bottom  by  means  of  a 
key  in',  when  it  can  be  ascertained  if  the  liquor  is  limpid.  A small  quantity  of  thick  matter  usually 
issues  from  the  tube  first,  but  it  soon  runs  clear.  By  this  mode  of  proceeding  we  avoid  all  the  trouble- 
some labor  of  skimming,  &c.  The  juice,  after  leaving  the  tube  m,  passes  into  a gutter  M which  commu- 
nicates by  a pipe  c with  another  reservoir  j,  by  which  the  filters,  hereafter  described,  are  charged  with 
the  juice. 

When  all  the  clear  juice  is  drawn  off,  the  scum  and  the  remainder  is  drawn  into  a reservoir  under- 
neath ; after  which  bags  are  filled  with  it,  and  the  syrup  is  drained  and  pressed  out  of  it.  The  clarified 
cane-juice  in  the  reservoir  F is  next  to  be  filtered  through  animal  charcoal  in  grain;  and  this  filtration 
constitutes  one  of  the  most  important  operations  of  the  manufacture — it  purifies  the  juice  and  furnishes 
the  means  for  readily  obtaining  sugar  of  the  first  quality.  In  Fig.  3381  eight  of  these  filters  are  repre- 
sented, li  h h,  all  of  the  same  construction  ; the  same  are  shown  in  Fig.  3382.  They  are  constructed  to 
contain  about  one  and  one-seventh  tons  of  animal  charcoal.  They  are  made  of  sheet-iron  or  wood  lined 
wTith  copper,  of  a square  form,  narrowing  slightly  towards  the  bottom.  At  the  lower  part  there  is  a grat- 
ing, leaving  a small  space  between  that  and  the  bottom,  through  which  the  filtered  liquid  flows.  On 
this  grating  is  placed  a thick  blanket  for  the  purpose  of  supporting  the  charcoal,  which  should  be  suffi- 
ciently large  to  allow  the  edges  to  be  pressed  against  the  sides  ; a thick  layer  of  charcoal  is  then  spread 
over  this  blanket  firmly  and  evenly,  after  which  another  layer  of  charcoal  is  put  on,  care  being  taken  to 
equalize  it  with  a trowel  as  it  is  thrown  in,  and  the  filter  is  filled  thus  to  about  four  and  a half  feet  in 
depth ; the  upper  surface  is  then  carefully  smoothed,  and  it  is  ready  for  uee.  • 

A plate  is  laid  on  the  place  where  the  cock  discharges  the  juice  or  syrup  into  the  filter,  in  order  that 
t may  spread  horizontally  over  the  surface  without  forming  hollows  therein.  The  syrup  penetrates  the 
animal  charcoal,  and  drives  the  air  down  before  it,  which  is  discharged  from  a pipe  that  leads  up  from 
the  space  below  the  grating  to  the  top  of  the  filter.  The  syrup,  after  passing  through  the  grating  and 
having  deposited  all  its  impurities  in  the  filter  above,  is  drawn  off  through  the  cock  in  the  bottom,  from 
whence  it  is  conducted  to  a reservoir,  shown  in  Fig.  3382  by  the  letter  k,  from  which  it  is  elevated  by  a 
cylinder  l into  a reservoir  l'.  This  cylinder  or  monte-jus  is  made  and  operates  precisely  the  same  as 
that  previously  described  and  shown  in  Fig.  3381. 

From  the  reservoir  l'  of  Fig.  3382  the  juice  is  conveyed  to  the  evaporator,  which  is  one  of  the  most 
important  parts  of  this  invention,  and  is  constructed  as  follows  : Fig.  3382  (O'  C"  O'")  being  a top  plan, 
and  Fig.  3381  a side  elevation  thereof;  it  consists  of  a double  or  triple  series  of  horizontal  tubes  of  81- 
inches  in  diameter,  and  about  300  feet  in  length,  each  series  being  placed  one  over  the  other,  forming 
two  or  three  parallel  lines ; the  tubes  of  each  series  are  connected  together  at  each  end,  so  as  to  form 
one  long  conductor  for  the  steam,  by  which  they  are  heated.  The  tubes  of  each  series  are  supported  by 
two  upright  posts,  one  at  each  end,  which  are  connected  at  the  top  by  a cross-beam  or  cup-brace  just 
under  this  beam ; there  is  a bracket  on  the  inside  of  each  post  which  supports  a triangular-shaped 
trough  or  distributor  P,  that  extends  from  one  to  the  other,  the  lower  edge  of  said  trough  being  serrated 
without  being  cut  through,  and  standing  directly  over  the  centre  of  the  upper  tube  of  the  series,  C' ; one 
side  of  this  trough  has  a row  of  small  vertical  oblong  holes  in  it,  through  which  the  juice  received  from 
the  reservoir  V percolates,  and  guided  by  the  lower  serrated  edge,  drops  upon  the  top  of  the  upper  tube, 
spreads  itself  around  it,  and  then  falls  on  the  next,  and  so  on  to  the  bottom,  passing  over  the  entire  sur- 
face of  the  tubes,  which,  by  the  heat  of  the  steam  within  them,  serve  to  evaporate  some  of  the  aqueous 
portions  of  the  juice  that  is  then  received  at  the  bottom  in  a receiver  V , and  ultimately  into  the  reser- 
voir u,  and  the  juice  being  heated  by  the  tubes,  and  being  exposed  to  the  action  of  the  air  in  a state  of 
extreme  division,  is  evaporated,  and  conducted  in  a proportion  determined  by  the  rate  at  which  it  es- 
capes from  the  distributor  above,  as  it  falls  into  the  receiver  t'. 

A is  a pan  of  a common  construction  for  boiling  by  steam  in  vacuum,  with  the  usual  fixtures  attached 
thereto ; a vacuum  is  formed  by  an  apparatus  hereafter  named,  in  the  boiler  A,  and  by  opening  a com- 
munication between  the  boiler  and  the  reservoir  u through  the  connecting-pipe  d",  which  extends  from 
the  bottom  of  said  reservoir  to  the  pan,  the  juice  contained  in  the  reservoir  rushes  into  the  pan.  As  soon 
as  'the  pan  is  filled,  which  is  ascertained  by  means  of  the  glasses  in  the  lid  of  the  pan,  the  pipe  d"  is 
stopped,  and  the  steam  is  introduced  into  the  respective  heaters  of  the  boilers  from  the  steam-generators. 

The  steam  which  rises  from  the  juice  in  the  pan  into  the  cup  Id,  passes  through  a tube  a into  a large 
upright  cylinder  B,  in  which  any  saccharine  matter  is  separated  from  the  steam  which  has  been  forced 
up  with  it.  From  the  vase  B the  steam  passes  by  the  pipes  e"  into  each  series  of  tubes  above  described, 
(lettered  C'  C"  C'",)  entering  the  upper  tubes  of  the  series  and  passing  out  of  the  l;wer  ones  on  the  op- 
posite sides ; the  steam,  in  passing  through  the  tube  0,  is  condensed  by  the  juice  which  runs  down  over 
the  outside,  the  apparatus  thus  performing  the  two-fold  operation  of  evaporating  the  juice  and  forming 


686 


SUGAR  BOILERS. 


ft  condenser  for  the  steam  rising  from  the  vacuum-pan.  The  steam,  when  condensed  into  water,  runs 
out  of  the  lower  tubes,  as  above  named,  into  an  injecting -cylinder  D,  where,  if  the  condensation  is  not 
perfect,  water  can  be  injected  to  complete  it ; from  the  cylinder  D the  water  of  condensation,  <5rc.,  is 
drawn  off  by  the  action  of  the  air-pump  attached  to  a steam-engine,  indicated  in  the  drawing  by  E. 
The  pump  and  cylinder  D,  above  named,  may  be  omitted,  and  a ventilator  placed  in  their  stead ; but 
the  vacuum  will  not  in  that  case  be  so  complete,  although  the  expense  of  the  apparatus  is  somewhat 
reduced.  Instead  of  attaching  the  condenser  with  the  vacuum-pan,  as  above  described,  it  may  be  con 
nected  with  the  exhaust-pipe  of  the  steam-engine. 

As  the  depth  of  juice  in  vacuum-pan  A is  reduced  by  evaporation  down  10  the  heaters  inside,  a fur- 
ther supply  is  to  be  admitted  from  u through  the  pipe  d",  as  in  the  first  instance;  and  when  the  juice 
under  evaporation  acquires  a density  of  2I0  or  25°  of  Beaume,  it  must  be  drawn  out  of  the  pan,  the 
passage  of  the  steam  to  the  heaters  being  first  cut  off,  and  the  vacuum  therein  destroyed. 

The  syrup  at  25°  then  passes  through  a movable  spout  L,  which  is  directed  into  another  spout  N,  and 
thence  into  the  reservoir  I,  after  which  the  boiler  is  charged  with  juice  from  u,  and  the  process  again 
proceeds  as  before.  During  the  operation  of  emptying  and  refilling  the  pan,  the  time  is  so  short  as  not 
to  require  the  stopping  of  the  flow  of  the  cane-juice  over  the  outside  of  the  tubes  C'  C"  O'". 

From  the  reservoir  I the  syrup  is  raised  by  means  of  a hand-pump  J into  a spout  which  is  represented 
at  i,  Fig.  3382,  for  feeding  the  filters  before  described.  The  syrup  runs  from  the  spout  i into  either  of 
the  filters  li  through  stop-cocks  attached  thereto  for  that  purpose,  and  passing  down  through  the  filters, 
it  is  soon  after  drawn  off  through  the  cock  and  received  into  the  gutter  i\  whence  it  is  conducted  into 
the  reservoir  k',  Fig.  3382  ; and  when  there  is  a sufficient  quantity  therein  to  fill  the  pan  A,  the  other 
processes  are  stopped,  and  the  pan  A is  filled  with  the  syrup  from  the  reservoir  k',  by  means  of  a pipe 
u',  which  connects  them  by  a proceeding  similar  to  that  for  filling  the  pan  from  the  reservoir  u.  The 
evaporation  of  this  syrup  of  25°  is  then  proceeded  with  until  it  is  sufficiently  boiled,  which  is  ascertained 
by  the  testing-rod  of  common  form.  When  the  syrup  is  in  a proper  state  of  condensation,  the  pan  is  to 
be  emptied  by  means  of  the  movable  spout  L,  through  the  spout  N,  into  one  or  the  other  of  the  heating 
pans  shown  by  letter  F. 

The  pans  I’  have  double  bottoms,  and  are  supplied  with  steam  from  the  generators  between  the  two 
bottoms,  by  which  they  are  heated,  until  the  temperature  of  the  syrup  contained  therein  reaches  1 0° 
Beaume,  at  which  point  crystallization  almost  immediately  commences;  and  when  it  is  quite  deter- 
mined, the  mixture  of  crystals  and  syrup  must  be  stirred  with  a wooden  spatula,  care  being  taken  to  dis- 
tribute the  crystal  formed  on  the  bottom  and  sides  equally ; the  matter  is  then,  while  in  a liquid  state, 
ready  to  pour  into  the  moulds. 


In  the  process  of  filtration,  herein  before  named,  as  soon  as  it  is  found  that  from  the  use  of  the  filter 
the  syrup  of  25°  comes  from  it  less  pure  than  at  first,  it  is  stopped  and  turned  into  another  filter;  the 
clarified  juice  is  then  admitted  into  the  filter  from  spout  j ; this  drives  the  syrup  still  contained  in  the 
filter  down,  and  takes  its  place.  When  the  degree  of  the  flowing  syrup  is  found  to  be  reduced  to  15°, 
the  juice  flowing  from  the  cock  is  directed  into  the  gutter  j,  which  conducts  it  into  the  reservoir  lc,  from 
whence  it  takes  its  course  as  before  indicated.  _ ...  . 

When  the  animal  charcoal  is  sufficiently  exhausted  by  the  filtration  of  the  clarified  juice,  water  is  let 
on  to  the  filter,  and  assumes  the  place  of  the  clarified  juice  in  the  same  way  as  the  juice  did  the  syrup  ; 
by  this  means  the  greater  part  of  the  juice  is  recovered,  the  flow  being  stopped  when  the  degree  of  the 
liquid  is  too  weak  to  be  of  value.  _ . . 

The  coal  is  then  taken  out  of  the  filter  and  conveyed  to  the  revivifier,  and  the  filter  is  again  refilled 
with  fresh  black.  _ . 

Ddrosne  claims  the  employment  of  a series  of  horizontal  tubes,  placed  one  above  another,  in  the  man- 
ner described,  having  a current  of  steam  passing  through  them,  and  the  cane-juice  flowing  over  the  ex- 
terior surface,  by  which  the  steam  is  condensed  and  the  juice  is  somewhat  concentrated ; thus  serving 
the  double  purpose  of  condenser  and  evaporator  as  before  described,  said  condenser  being  attached  either 
to  the  vacuum-pan  or  to  the  exhaust-pipe  of  the  steam-engine. 

milieux’s  apparatus.— Norbert  Rillieux,  of  New  Orleans,  invented  an  apparatus  for  boiling  sugar  m 
vacuo?  in  which  he  uses  the  latent  heat  arising  from  one  pan  to  boil  the  juice  or  syrup  in  succession  in 
another  vacuum-pan  of  similar  construction.  To  heat  the  first  pan  he  uses  the  escape  steam  of  the 


SUGAR  BOILERS. 


G87 


steam-engine  -which  works  the  grinding-mill;  the  second,  third,  or  fourth  pan  is  heated  from  the  vapors 
arising  from  the  second  and  third  pans. 

An  air-pump  produces  the  necessary  vacuum. 

Mr.  Rillieux  obtained  letters  patent  for  his  invention  in  1843,  and  for  improvement  in  the  same  in  1 84f>. 

The  following  description  and  figures  will  give  a correct  idea  of  the  apparatus  and  its  mode  of  working. 

Rillieux’s  boiling  apparatus  is  composed  of  three  or  four  pans. 

The  four-pan  apparatus. — The  cane-juice,  after  having  passed  the  clarifiers  and  filters,  flows  into  a 
vat,  from  which  it  is  pumped  in  the  first  pan  A,  through  a pipe  a,  Fig.  3385,  which  leads  to  the  back 
part  of  that  pan,  on  which  pipe  there  is  a stop-cock,  which  is  opened  or  closed  by  means  of  a handle  h 
placed  in  front  of  the  apparatus,  where  the  man  who  manages  the  apparatus  is  placed ; and,  in  turning 


that  handle  more  or  less,  he  can  regulate  the  feeding  of  that  pan,  in  front  of  which  is  a pipe  r,  Fig» 
8383  and  3385,  leading  the  cane-juice  to  the  back  part  of  the  second  pan  B ; on  that  pipe  and  under  th< 
first  pan  is  a stop-cock,  worked  by  the  hand  d,  by  which  the  feeding  of  the  second  pan  B is  regulated 
and  in  the  front,  on  this  second  pan  and  below,  is  another  stop-cock,  worked  by  the  hand  e ; from  that 
stop-cocx  a pipe  e'  leads  to  the  back  of  pan  0,  to  convey  the  cane-juice,  now  at  the  density  of  15° 
Beaume,  into  said  pan;  and  from  this  pan  a pipe  leads  to  a pump  which  draws  the  syrup,  now  arrived 
at  28°,  from  the  pan  c,  and  forces  it  up  to  the  clarifiers  E E.  In  those  clarifiers  the  syrup  is  heated  up 
to  the  boiling  point  and  scummed ; from  thence  it  passes  through  the  bone-black  filters  G G,  whence  it 
goes  to  a vat  H,  Fig.  3384,  below,  to  supply  the  fourth  or  strike  pan  D. 


688 


SUGAR  BOILERS. 


Now  let  us  follow  the  steam  : 

The  exhaust  steam  from  the  boilers  goes  through  the  pipe  I,  Figs.  3383  and  3384,  to  the  first  pan  A. 
Below  that  is  another,  K,  which  brings  the  direct  steam  from  the  boiler  and  feeds  the  clarifiers  F F and 
the  pumping  engine  L.  At  M,  Fig.  3384,  is  a valve  which  connects  the  two  steam-pipes  together,  and 
through  which  any  quantity  of  direct  steam  wanted,  besides  the  exhaust  steam,  can  be  let  into  the  ex 
haust  steam-pipe  I for  boiling  the  juice. 

The  vapors  arising  from  the  cane-juice  of  the  pan  A are  carried  down  through  a pipe  h,  Figs.  3385 
and  3386,  and  column  i,  in  a cast-iron  box,  o2,  steam-chest  k.  A part  of  this  steam  passes  up  through 
the  column  l to  feed  the  second  pan  B,  and  passes  through  the  horizontal  pipe  m,  Fig.  3385,  and  up  the 
column  q to  feed  the  strike-pan  D. 

The  vapor  arising  from  the  second  pan  B passes  through  column  n and  steam-chest  k1,  and  up  through 
the  column  o,  to  boil  the  pan  C.  The  vapor  from  C D passes  through  the  columns  p 2 through  the 
horizontal  pipe  s,  and  brings  the  vapor  to  the  condenser  s,  where  it  is  condensed  by  means  of  a jet  of 
water;  the  vacuum  being  maintained  through  the  means  of  an  ordinary  air-pump  T.  S is  a pipe  which 
connects  the  pumping  engine  with  the  condenser,  the  third  and  fourth  pan. 


3385. 


The  waste  water  of  the  first  pan  A comes  down  through  a pipe  into  an  air-tight  chest  in  the  bot- 
tom-plate of  the  pumping  engine,  from  w’hich  the  force-pump  u takes  it  and  sends  it  back  to  the  steam- 
boilers. 

The  waste  water  of  the  second  and  third  pans,  which  is  the  condensed  water  of  the  vapor  arising 
from  the  cane-juice  in  the  first  and  second  pans,  passes  through  similar  stop-cocks  and  pipes,  which 
carry  it  to  the  small  air-pump  U,  which  forces  it  up  to  a vat,  where  it  serves  for  all  the  cleansings  of  the 
establishment.  _ ...  , „ 

Three-pan  apparatus. — When  the  three-pan  apparatus  is  used,  the  cane-juice  is  pumped  into  the  first 
pan  A ; from  thence  to  the  third  C ; the  second,  marked  B,  is  omitted ; whence  it  is  drawn  off  by  the 


SUGAR  BOILERS. 


689 


pump  to  the  clarifiers,  and  the  juice  follows  the  same  course  as  in  the  four-pan  apparatus,  above  de 
scribed. 

The  exhaust  steam  and  the  direct  steam  are  let  in  the  first  pan  by  means  of  the  valve  M,  above 
mentioned,  and  the  vapor  arising  from  this  pan  feeds  the  pan  C,  and  the  third  pan  D,  and  the  vapor  of 
the  second  C,  and  third  D,  goes  as  in  the  other  apparatus  already  described  to  the  condenser.  The 
waste  water  of  the  second  0,  and  third  D,  follows  the  same  course  as  already  described  in  the  four -pan 
apparatus,  to  the  small  air-pump.  As  the  main  part  of  the  boiling  in  the  apparatus  is  effected  by  the 
exhaust  steam  of  the  mill-engine,  the  mill  must  be  kept  grinding  at  a uniform  speed,  and  with  a contin- 
ually regular  supply  of  cane  ; and  as  the  power  of  the  engine  is  regulated  by  the  difference  of  pressure 
between  the  steam  in  the  boilers  and  the  steam  in  the  exhaust-pipe,  and,  as  that  difference  is  regulated 
by  the  weight, on  the  valve  M,  it  follows  that,  in  loading  that  valve  M more  or  less,  the  different  pres- 
sure of  steam,  or  what  is  called  the  effective  pressure  of  the  steam,  is  adjusted  in  such  a way  that  the 
mill  will  furnish  as  much  cane-juice  as  the  apparatus  boils — in  such  a way  that  the  clarifiers,  filters, 
and  filtered  juice-vat  are  always  kept  full.  The  liquid  flows  from  the  mill  up  to  the  clarifiers  and  down 
to  the  filters,  with  the  same  S23eed  as  it  comes  from  the  mill,  the  cane-juice  passing  out  of  the  aforesaid 
vat  as  fast  as  it  comes  in,  to  supply  the  first  pan,  and  from  thence  to  the  second  pan,  (or  third,  as  the 
case  may  be,)  when  it  is  brought  to  the  density  of  29°  Beaumti,  A small  pump  is  attached  to  the  en- 
gine to  take  it  out  of  that  pan  fast  enough  to  keep  the  syrup  at  a certain  height  in  it. 

The  syrup  is  pumped  into  one  of  the  clarifiers  E as  high  as  the  jacket  reaches ; when  that  clarifier  is 
filled  to  that  point  the  rest  of  the  syrup  is  turned  into  the  other,  which  is  heated  by  letting  in  the  steam 
before  it  is  full ; when  the  first  clarifier  has  reached  the  boiling  point,  the  steam  is  shut  off,  the  scum 
removed,  and  the  liquid  emptied  by  the  cock  W into  a trough,  and  thence  down  to  the  filters. 

The  only  operation  which  the  attendants  of  the  pans  have  to  observe  is  to  keep  the  juice  or  syrup  at 
the  proper  level  in  the  first  and  second  pans,  and  to  feed  them  as  well  as  the  third  pan  in  such  a way 
that  the  syrup  be  maintained  at  29°  Beaumfe  in  the  second  pan,  (or  third,  as  the  case  may  be,)  by  open- 
ing or  closing  tlie  feeding-cocks  when  the  syrup  runs  too  thick  or  too  thin,  or  when  the  juice  is  too  high 
or  too  low,  and  also  to  regulate  the  pressure  of  the  steam  by  the  valve  M.  It  will  be  observed  that 
there  are  two  sets  of  clarifiers  EE — one  set  to  boil  the  syrup,  and  the  other  set  to  defecate  the  juice  as 
it  comes  from  the  mill. 

When  the  stop-cocks  are  regulated  they  require  a constant  watching  by  the  person  employed  at  the 
pans  ; but  they  remain  sometimes  hours  without  being  moved,  or  the  handles  require  to  be  moved  more 
than  one-eighth  of  an  inch  to  one  or  the  other  side  to  keep  the  cane-juice  at  the  proper  height,  and  the 
syrup  at  its  proper  density.  The  cane-juice,  when  it  leaves  the  mill,  passes  in  a constant  stream  to  the 
clarifier  E,  from  thence  to  the  filters  and  pans,  and  returns  again  to  the  clarifier  F,  at  syrup  of  29°  den- 
sity, and  from  there  it  goes  through  the  bone-black  filters  G G to  the  vat  H,  which  again  supplies  the 
strike-pan,  and  then,  at  last,  the  boiling  is  done  by  strikes,  as  the  sugar-boiler  calls  it. 

The  juice  goes  from  the  first  into  the  second  in  the  three-pan  apparatus,  and  from  the  first  to  the  sec- 
ond, and  from  the  second  to  the  third  in  the  four-pan  apparatus ; because,  in  the  latter  apparatus  there 
is  more  vacuum  in  the  second  than  in  the  first,  and  more  in  the  third  than  in  the  second ; and  it  is  that 
excess  of  vacuum  which  draws  the  cane-juice  from  one  pan  into  the  other. 

The  waste  water  of  the  juice-clarifier  F F comes  through  pipe  X in  the  steam-chamber  of  the  first 
pan ; on  which  pipe  there  is  a three-way  cock,  which,  when  properly  turned,  sends  it  directly  back  to 
the  waste-water  pipe  t of  the  first  pan.  The  waste  water  of  the  two  other  clarifiers  E E comes  directly 
to  the  waste-water  pipe  t of  said  pan.  When  the  second  pan  is  boiling,  the  three-way  cock  is  turned 
to  bring  said  waste  water  from  the  cane-juice  clarifier  to  the  steam-chamber  of  the  first  pan  ; arid  all 
the  steam  arising  from  said  waste  water  upwards  mixes  itself  with  the  exhaust  steam,  and  helps  the 
boiling  of  said  pan  ; the  water  flows  to  the  lower  row  of  pipes  through  the  other  end  of  the  pan,  and 
mixes  itself  with  the  waste  water  of  said  pan,  and  goes  down  through  the  waste-water  pipe  f,  mixed 
with  the  waste  water  of  the  clarifier  E E to  the  closed  chest  in  the  bed-plate  of  the  pumping-engine, 
from  whence  the  whole  is  pumped  back  to  the  boilers  in  such  a way  that  all  the  steam  condensed  in 
the  jacket  of  the  cane-juice  and  syrup  clarifier,  and  that  which  has  been  condensed  in  the  pipe  of  the 
first  pan,  is  returned  to  the  boilers.  Now,  as  all  the  exhaust  steam  of  the  mill  and  pumping  engine  is 
used  for  the  boiling  of  the  first  pan,  it  follows  that  all  the  steam  raised  in  the  boilers,  except  the  small 
portions  which  escape  from  the  leak  of  stuffing-boxes  or  safety-valves,  is  entirely  condensed  and  ren- 
dered available  for  heating  the  cane-juice  and  syrup  in  the  clarifier,  and  the  whole  of  the  waste  water 
heated  to  the  boiling  point  is  sent  back  to  the  boiler. 

In  Rillieux’s  apparatus  the  use  of  the  latent  heat  is  carried  out  more  perfectly  and  fully,  perhaps, 
than  in  any  other  system  known. 

The  first  pan  of  his  apparatus  is  heated  by  steam  not  exceeding  a pressure  of  four  to  eight  lbs.  per 
square  inch,  and  the  latent  heat  of  the  vapor  from  this  pan  is  used  to  evaporate  the  syrup  in  the  next  of 
the  series  of  pans,  and  so  on.  We  have  seen  from  the  description  of  this  apparatus  that  he  uses  an  air- 
pump  to  form  the  vacuum,  which  is  worked  in  connection  with  the  various  other  pumps  by  a separate 
steam-engine,  which  is  placed  under  the  apparatus. 

Merrick  & Town,  of  Philadelphia,  assignees  of  N.  Rillieux’s  patent,  carried  the  plans  of  the  highly  in- 
telligent inventor  into  execution,  and  developed  in  its  results  its  admirable  adaptation  to  the  purpose 
for  which  it  was  intended. 

The  principle  of  the  successive  use  of  latent  heat  has  been  long  known  and  applied  for  distilling  and 
evaporating,  but  it  has  never  been  applied  in  connection  with  vacuum,  by  which  connection  only  the 
rapid  boiling  required  for  the  evaporation  of  saccharine  can  be  obtained. 

This  is,  therefore,  an  American  invention,  which  will  form  a new  era  in  the  sugar-growing  interest  of 
the  United  States. 

Mr.  Tli.  Packwood  uses  three  steam-boilers  of  ordinary  size : the  fire-grate  extends  only  under  two  of 
them;  the  third  boiler  is  heated  by  a return  flue,  and  this  is  the  only  fire  employed  about  the  whole 
Vol.  II.— if 


SUGAR  BOILERS. 


GOO 


sugar-house,  generating  enough  steam  to  work  the  grinding-mill,  to  heat  the  defecators,  supply  the  ne- 
cessary  quantity  of  steam  to  the  boiling  apparatus,  to  work  the  engine  for  the  air,  juice,  syrup,  anq 
water  pumps  ; making  12,000  lbs.  of  sugar  in  24  hours. 

The  apparatus  is  solid  and  requires  very  small  space,  and  has  a pleasant  appearance. 

The  sugar  made  with  this  apparatus  is  of  a beautiful  light  straw-color,  of  tine  large  crystal,  and  free 
from  unpleasant  odor,  and  commanding  a good  price  and  ready  sale. 

The  price  of  a Rillieux  apparatus  varies  according  to  the  size ; a three-pan  apparatus  sufficiently 
large  to  take  off  a crop  of  440  hogsheads  of  first  sugar,  including  clarifiers,  bone-black  filters,  vat  for 
tiltered  cane-juice  and  syrup,  three  boiling-pans,  pumping  engine,  cast-iron  and  copper  pipes,  and  all 
expenses  of  setting  up,  is  $11,000.* 

A.  Stillman  patented  an  improvement  in  evaporating  saccharine  juices  in  1843. 

The  invention  consists  in  employing  the  surplus  or  waste  heat  from  the  " train”  in  generating  steam 
for  grinding  cane,  pumping,  or  any  other  purpose  for  which  it  may  be  required. 

To  supply  the  deficiency  of  evaporating  power  occasioned  by  diminishing  the  train  of  kettles,  he  sub- 
stitutes in  their  place  any  number  of  steam  evaporators  or  clarifiers,  into  which  is  introduced  the  “ ex- 
haust" or  waste  steam,  from  the  steam-engine.  This  waste  steam,  to  be  made  effective,  must  be  intro- 
duced into  the  clarifiers  or  evaporators  under  a pressure  greater  than  that  of  the  atmosphere,  and  the 
effect  will  be  in  proportion  to  the  jiressure. 

The  objects  of  this  arrangement  are,  a saving  of  fuel  and  improvement  in  the  quality  of  the  product, 
and  the  improvement  in  the  latter  respect  will  be  proportionate  to  that  amount  of  the  process  of  clari- 
fying and  evaporating  which  is  transferred  from  the  ordinary  kettles  in  contact  with  the  fire,  to  those 
making  use  of  the  waste  steam. 


Fig.  3387  is  a section  of  the  sugar- works  in  which  are  shown  the  application  of  the  improvement,  and 
respecting  only  a general  arrangement.  A A are  the  steam-boilers  so  placed  as  to  receive  under  them 
the  waste  heat  from  the  train ; B,  the  steam-engine ; E,  pump  for  bringing  the  liquor  from  the  reservoir 
to  the  clarifiers  through  the  pipe  F.  This  pump  is  not  an  essential  fixture,  as  the  mill  is  more  frequently 
elevated  to  a height  sufficiently  for  the  liquor  to  run  directly  to  the  clarifiers.  GG,  the  clarifiers;  H, 
the  evaporator,  which  is  of  the  same  form  and  construction  as  the  clarifiers  ; IKL,  a train  of  “ coppers” 
or  evaporators,  such  as  are  in  common  use  ; M,  fireplace  for  the  train  ; N,  the  flue,  through  which  the 
flame  passes  from  the  “ train”  under  the  steam-boilers  to  the  chimney  ; O P is  also  a flue  to  the  chim- 
ney, so  that  the  flame  from  the  “ train”  may  be  turned  off  from  the  steam-boilers  at  will ; R,  exhaust 
steam-pipe  from  the  engine  ; this  pipe  communicates  with  the  pipes  in  the  clarifiers  or  evaporators  ; S, 
the  escape-valve,  by  which  a pressure  is  maintained  in  the  exhaust-pipe. 

The  clarifiers  are  rectangular  boxes  of  sheet-iron,  (boiler-plate,)  the  bottoms  of  which  are  double,  so 
as  to  form  a steam-chamber  a\  around  the  top  they  have  a channel-way  m,  which  forms  the  “skim- 
ming-spout the  skimmings,  which  it  receives,  are  carried  off  by  a pipe.  In  addition  to  the  heating 
surface  obtained  by  the  double  bottom,  there  is  above  it  one  or  more  tiers  of  copper  pipes.  The  method 
of  introducing  them  is  as  follows  : on  two  opposite  sides  of  the  clarifiers  is  a cast-iron  box  riveted,  which 
forms  the  side  chamber  b b,  and  extends  the  whole  length  of  the  clarifier ; this  chamber  is  closed  by  a 
movable  plate  which  is  fastened  by  bolts ; these  two  opposite  chambers  are  connected  by  the  cross- 
pipes e;  the  pipes  are  received  into  the  chambers  through  “packing-joints,”  so  as  to  prevent  any  com- 
munication between  the  steam  in  the  chamber  and  the  liquor  within  the  clarifier.  To  the  top  of  one  of 
the  side  chambers  there  is  a cylindrical  valve-chamber  attached,  which  receives  the  steam  from  the  ex- 
haust-pipe on  either  side ; from  the  lower  side  of  this  valve-chamber  is  a steam  passage  communicating 
with  the  chamber  b ; this  steam  passage  is  opened  or  closed  by  means  of  a sliding-valve  d. 

When  the  engine  is  in  operation,  the  waste  steam  passing  through  the  exhaust-pipe  R is  admitted 
through  into  the  side  chamber  b , and  from  thence  into  the  pipes  c c.  and  also  through  apertures  into  the 
bottom  chamber  a.  The  liquor  in  the  clarifier  is  then  exposed  to  the  heating  surfaces  of  the  pipes  c e, 
and  also  of  the  “ false”  or  “ double  bottom.” 

Steam-pipes  passing  through  the  liquor  have  been  before  employed,  but  not  in  combination  with  the 
double  bottom.  The  advantage  of  this  combination  is  this:  by  using  the  pipes  alone,  that  portion  of 
the  liquor  beneath  them  would  be  in  a great  measure  unaffected,  whilst  the  double  bottom  above  would 
not  give  the  necessary  heating  surface ; so  that  the  combination  is  necessary  to  a perfect  operation. 

h and  i are  two  valves  ; one  for  discharging  the  clarified  or  concentrated  liquor,  and  the  other  for 
discharging  -the  sediment  formed  in  clarifying.  Their  construction  is  as  follows  : the  valve  is  the  ordi- 
nary “ puppet  valve,”  with  a hinge  on  the  upper  side  for  attaching  the  rods ; the  seat  is  fitted  between 
:he  two  bottoms  of  the  clarifier  and  riveted  to  both  ; the  pipes  for  carrying  the  liquor  and  sediment  arc 


See  De  Row’s  Commercial  Review,  p.  292,  vol.  5 


SWITCH. 


691 


attached  by  fianches  and  bolts  to  the  bottom  of  the  seats.  The  valves  will  close  by  their  own  weight, 
and  the  weight  of  the  liquor  above  them  will  keep  them  tight ; the  valves  are  raised  by  cords  con 
necting  them  to  levers  on  the  shaft  R,  which  shaft  is  worked  by  a handle  on  the  outside  of  the  clarifier 

The  valves  are  so  placed  that  the  levers  stand  in  opposite  directions  upon  the  same  shaft,  so  that 
both  valves  can  never  be  opened  at  the  same  time. 

S .the  escape-valve,  made  like  an  ordinary  safety-valve,  and  attached  to  the  exhaust-pipe  of  the  en- 
gine. Its  particular  construction,  however,  is  not  essential,  its  purpose  being  to  obtain  all  the  useful 
effect  of  the  waste  steam  by  confining  it  in  the  exhaust-pipe  and  clarifiers  at  any  required  pressure. 
Suppose,  for  instance,  that  the  engine  is  in  operation,  and  the  exhaust-pipe  terminating  in  the  clarifiers, 
but  in  some  part  of  the  exhaust-pipe  there  is  an  opening  into  the  air  of  a size  equal  to  that  of  the  pipe, 
the  steam,  of  course,  would  escape  through  the  opening  against  the  pressure  of  the  atmosphere  only ; 
its  effect  in  the  clarifiers  would  then  be  very  slight ; but  when  that  opening  is  closed  by  means  of  a 
loaded  valve,  by  increasing  the  weight  on  the 

valve,  we  may  so  confine  the  waste  steam  as  to  3388- 

effect  the  entire  absorption  of  its  heat  in  the  clari- 
fiers or  evaporators. 

The  operation  of  this  apparatus  is  as  follows : 

The  Hues  N and  P being  closed  by  dampers,  a 
fire  is  made  under  the  steam-boilers  in  the  usual 
manner.  As  soon  as  a sufficiency  of  steam  is 
generated  the  engine  and  cane-mill  are  put  in 
operation.  The  pump  E is  then  put  in  operation, 
and  the  liquor  carried  to  the  clarifiers  G G,  through 
the  pipe  F ; the  steam  is  then  admitted  from  the 
exhaust-pipe  into  the  clarifiers ; and  the  liquor  hav- 
ing gone  through  the  usual  process  of  clarifying,  is 
discharged  by  means  of  the  valves  h h into  the 
evaporators  H,  and  through  that  into  the  train  of 
coppers  I K L,  where  the  evaporation  is  to  be 
completed.  These  coppers  or  kettles  being  filled 
with  the  clarified  liquor,  the  furnace  is  closed,  and 
the  fire  started  under  the  trains  of  coppers  on  the 
furnace  M,  by  which  fire,  besides  effecting  the 
concentration  of  the  liquor  in  the  kettles,  the  steam 
is  generated  in  the  boilers  and  the  operation  con- 
tinued. 

The  steam-clarifiers  may  be  used  indiscrimi- 
nately in  clarifying  or  evaporating,  as  the  case  may 
require. 

If  the  train  of  coppers  be  very  much  diminish- 
ed, more  of  the  evaporation,  of  course,  must  be 
carried  on  in  the  steam  evaporator. 

SWITCH.  A contrivance  of  a variable  rail  by 
means  of  which  the  cars  on  a railroad  are  passed 
from  one  line  of  rail  to  another. 

Fig.  3388  shows  the  method  of  operating.  S S 
are  called  the  switch-bars,  movable  about  the 
point  H,  at  which  point  they  form  part  of  the  line 
of  rail  of  the  straight  track  BBBB.  These  bars 
are  secured  together  by  iron  rods  rrr;  a rod  r'  is 
connected  to  the  short  arm  of  a lever  l,  seen  in 
elevation  in  Fig.  3389  : by  throwing  this  lever  to 
the  right  or  left  the  switch-bars  are  moved  so  that 
they  form  either  part  of  the  straight  and  right-hand 
track  B A,  B A,  or  part  of  the  straight  and  left- 
hand  track  B 0,  B 0.  Where  the  rails  cross  at  E 
is  the  fixed  casting  called  a frog,  the  use  of  which 
to  pass  the  flange  of  the  wheel  through  the 
curved  rail  is  too  obvious  to  require  explanation. 

This  is  the  double  switch  connecting  a main  line 
with  a turn-out  or  track  on  either  side,  and  wher- 
ever the  rails  cross  each  other  a frog  is  inserted, 
bolted  to  the  cross-ties.  See  Frog. 

Innumerable  forms  of  switch-bar  and  frog  have 
been  devised  for  accomplishing  the  same  purpose, 
and  several  patents  have  been  taken  out  for 
switches  called  “safety  switches,”  the  object  of 
which  is  to  prevent  the  cars  passing  off  the  track 
when  through  negligence  the  variable  rail  is  left 
in  a wrong  position.  Mr.  Nichols,  of  Philadelphia,  is  the  patentee  of  a very  efficient  form  of  safetj 
switch,  as  is  also  Mr.  Tyler,  of  Worcester,  Mass. 


692 


TELEGRAPH. 


TELEGRAPH,  History  of  the.  Soon  after  the  discovery  of  the  Leyden  jar,  in  1747,  it  was  observed 
that  the  shock,  passed  through  twelve  thousand  feet  of  wire,  affected  persons  placed  at  either  extremity, 
apparently  at  the  same  instant  of  time.  The  idea  of  the  instantaneous  passage  of  electricity  was  prob- 
ably thus  first  received,  and  it  was  forced,  by  new  observations,  on  the  attention  of  all  succeeding 
electricians. 

In  1794,  Reizen  proposed  a telegraph,  employing  the  spark,  with  seventy-six  wires,  or  thirty-six 
complete  circuits,  one  for  each  letter  and  number.  In  1798,  Betancourt  constructed  a telegraph,  also 
employing  the  spark,  which  is  stated  to  have  been  in  successful  operation,  between  Madrid  and  Aran- 
juez,  for  twenty-six  miles.  This  was  the  achievement  of  the  close  of  the  last  century.  The  difficulty 
of  insulating  free  electricity  made  it  impossible  that  any  great  results  should  be  obtained  from  its  use. 

The  first  year  of  the  present  century  produced  the  voltaic  or  galvanic  battery.  In  1809,  Soemmering 
improved  this  discovery  by  inventing  a telegraph  of  thirty-five  wires,  which  indicated  the  letters  by 
the  decomposition  of  water,  which  took  place  under  the  eye  of  the  observer,  from  little  pins  of  gold. 
He  also  caused  the  liberation  of  the  gases  to  raise  a cup  attached  to  a lever,  and  thereby  drop  a weight 
on  a little  platform,  connected  with  chime  machinery,  so  as  to  ring  a bell.  In  1816,  Dr.  J.  R.  Coxe,  of 
Philadelphia,  proposed  a similar  decomposing  apparatus,  and  confidently  predicted  the  ultimate  sue 
cess  of  the  telegraph.  In  the  same  year,  Ronalds,  in  England,  returned  to  the  use  of  free  electricity,, 
inventing  an  elaborate  telegraph,  which  was  put  into  operation  over  eight  miles  of  wire. 

The  first  registering  telegraph  seems  to  have  been  constructed  by  Mr.  Harrison  Gray  Dyar,  of  Long 
Island,  in  1826,  who  used  the  decomposing  power  of  the  spark,  acting  upon  a fillet  of  paper,  moistened 
and  stained  with  litmus,  and  moved  by  hand  or  clock-work.  The  passage  of  each  spark  from  a con- 
ductor to  the  paper  produced  a discoloration,  and,  by  different  combinations  of  marks  thus  made,  any 
signal  could  be  transmitted  and  registered.  This  was  a very  important  step  in  the  history  of  the  tele- 
graph, and  appears  to  be  the  origin  of  the  system  of  telegraphic  alphabets  so.  generally  used  in  later 
inventions. 

In  the  telegraphs  already  referred  to,  it  had  been  necessary  to  interpose  the  indicating  apparatus  in 
the  course  of  the  circuit ; that  is,  to  interrupt  the  circuit  for  a short  space.  This  was  obviated  by  the 
discovery  of  the  deflection  of  the  compass  needle  by  (Ersted,  in  1819,  and  the  discovery  of  the  electro- 
magnet by  Ampere,  in  1820.  According  to  the  first  of  these  discoveries,  a magnetic  needle  tends  to 
place  itself  at  right  angles  to  a wire  in  its  neighborhood,  through  which  a galvanic  current  passes. 
According  to  the  second,  a piece  of  soft  iron,  placed  in  the  axis  or  centre  of  a coil  of  wire,  becomes  a 
magnet  during  the  passage  of  a galvanic  current  through  the  coil. 

In  1820  and  1822,  Ampere  proposed  and  fully  described  the  use  of  the  deflection  of  a number  of 
needles  to  constitute  a telegraph  similar  to  that  of  Wheatstone,  now  in  operation,  with  a less  number 
of  circuits,  in  England.  From  this  time  the  subject  became  one  of  frequent  suggestion  among  philoso- 
phers. The  deflective  telegraph  was,  however,  finally  introduced  into  practice  by  Schilling,  in  Russia, 
at  the  end  of  1832,  by  Gauss  and  Weber  at  Gottingen,  in  1833,  and  finally,  on  a large  scale,  by  Wheat- 
stone, in  England,  and  Steinheil,  at  Munich,  in  1837,  or  soon  after.  The  credit  of  the  first  construction 
of  the  galvanic  telegraph  belongs  thus  to  Schilling,  Steinheil,  and  Wheatstone,  by  the  latter  of  whom, 
with  some  of  his  English  coadjutors,  many  of  the  practical  difficulties  in  the  modes  of  transmitting  the 
current  were  overcome. 

The  telegraph  of  Steinheil,  which  was  in  operation  between  Munich  and  Bogenhausen  in  the  sum- 
mer of  1837,  seems  to  be  the  first  electro-magnetic  telegraph  on  record  which  employed  a registering 
apparatus.  The  deflection  of  his  needles  moved  little  levers,  carrying  pen-points,  which  marked  dots 
or  short  lines  on  a fillet  of  paper  moved  by  clock-work,  as  had  been  done  with  common  electricity  pre- 
viously by  Dyar,  and  as  was  subsequently  brought  into  use  in  this  country  by  Professor  Morse. 

The  deflective  telegraph  was  still  imperfect,  each  deflection  of  the  needle  requiring  a very  apprecia- 
ble time  to  be  accomplished.  The  use  of  the  electro-magnet  was  the  next  step  taken  in  advance.  It 
was  not  until  the  experiments,  in  1830,  of  Professor  Joseph  Henry,  now  secretary  of  the  Smithsonian 
Institute,  upon  powerful  electro-magnets,  and  the  effect  of  long  conductors,  that  this  form  of  telegraph 
became  possible ; and  in  his  first  paper  on  the  result  of  these  experiments,  he  at  once  applied  the  new 
facts  to  the  idea  of  the  construction  of  the  telegraph. 

In  1844,  the  registering  telegraph  of  Professor  S.  F.  B.  Morse,  employing  the  electro-magnet,  was 
introduced  upon  a line  between  Baltimore  and  Washington,  the  caveat  to  his  patent  bearing  the  date 
of  October,  1837.  The  first  suggestion  of  this  form  of  telegraph  is  claimed  to  have  been  made  by  Pro- 
fessor Morse  in  1832,  and  also,  in  its  general  character,  by  Dr.  0.  T.  Jackson.  This  telegraph,  together 
with  the  House  telegraph,  and  the  Bain  decomposing  telegraph,  constitute  the  three  systems  now,  for 
the  most  part,  in  operation  in  this  country 


Description  of  the  telegraph.. — Fig.  3390  represents  a series  of  twelve  pairs  of  Grove’s  battery,  such 
as  is  generally  used  in  connection  with  the  telegraph.  When  a plate  of  platina  and  a plate  of  zinc  are 
placed  in  an  acid  solution,  a current  tends  to  flow  from  the  platina  to  the  zinc,  through  any  conductor 


TELEGRAPH. 


693 


which  may  be  so  disposed  as  to  connect  the  two.  In  the  figure,  the  galvanic  series  is  represented,  cor,, 
eisting  of  twelve  single  pairs,  the  zinc  of  each  of  which  is  connected  with  the  platina  of  the  next.  It 
may  be  considered  that  a current  is  produced  by  each  of  these  pairs,  which  has,  however,  to  flow  in  the 
same  direction,  and  fall  in  with  all  the  others.  Hence  their  intensity  is  multiplied  twelve  times.  It  is 
by  this  means  that  the  resistance  to  the  passage  of  the  current  through  very  long  conductors  is  over- 
come. The  number  of  pairs  in  the  telegraph  is  always  proportioned  to  the  distance  which  the  current 
is  to  traverse,  fifty  or  more  being  used  on  a line  of  two  hundred  miles. 

Each  pair  of  the  battery  consists  of  a pint  glass  tumbler,  a cylinder  of  zinc,  a small  porous  cylindri- 
cal earthenware  cell  within  the  zinc,  and  a platinum  strip  suspended  within  the  cell  from  an  arm  be- 
longing to  the  zinc  of  the  next  pair.  A solution  of  diluted  sulphuric  acid  is  used  with  the  zinc,  outside 
the  porous  cell,  and  the  cell  itself  is  filled  with  nitric  acid.  The  two  acids  are  used  on  account  of  an 
increase  of  power  depending  on  a chemical  reaction.  The  zinc  cylinder  is  amalgamated  with  mercury, 
to  prevent  its  being  acted  upon  by  the  acid  when  the  battery  is  not  in  use.  A solution  of  sulphate  of 
soda  is  sometimes  added  to  the  sulphuric  acid,  to  assist  in  accomplishing  the  same  object.  This  is  the 
most  powerful  form  of  battery  known. 

A battery,  usiug  copper  and  zinc  plates  in  flat  glass  cells,  has  been  lately  employed  on  the  lines  of 
the  chemical  telegraph  in  this  country.  The  interval  between  the  plates  is  filled  with  white  sand.  The 
sand  is  moistened  to  the  consistency  of  a paste  with  diluted  sulphuric  acid.  This  battery  proves  very 
constant,  and,  though  less  powerful,  is  much  more  easily  managed  than  the  Grove  battery. 

Two  screw-cups  will  be  seen  rising  above  the  battery  in  Fig.  3390,  one  of  which  is  the  positive  pole 
or  extremity  of  the  series,  the  other  the  negative.  To  these  the  wires  are  attached  which  convey  the 
current.  These  wires,  as  first  used  in  the  telegraph,  were  of  copper,  which  is  a better  conductor  of  gal- 
vanism than  iron ; but  the  liability  to  accident,  from  their  want  of  strength,  was  so  great,  that  iron 
wires  were  substituted  by  Steinheil,  in  Germany,  of  a size  sufficient  to  make  up  by  their  quantity  for 
the  poorness  of  their  quality  as  conductors. 

The  wires  are  usually  supported  on  posts,  from  which  they  are  insulated  by  glass  supports  or  knobs. 
They  have  been  sometimes  carried  through  the  ground,  insulated  within  a metallic  tube. 

Fig.  3391  represents  the  signal-key  in  its  simple  form.  It  is  placed,  when  in  use,  in  the  course  of  the 
conductors  or  telegraphic  circuit,  proceeding  from  the  battery.  When  the  hand  depresses  the  key,  it 
comes  in  contact  with  the  knob  and  metallic  strip  below,  making  connection  between  the  two  screw- 
cups,  and  completing  the  batteiy  circuit.  While  the  key  is  depressed,  a continuous  current  passes ; 
but  if  it  be  depressed,  and  allowed  to  spring  immediately  up,  only  an  instantaneous  wave  or  impulse 
is  communicated.  The  use  of  the  signal-key,  in  connection  with  the  telegraph,  was  described  by  Am- 
pere, in  1820. 

3392. 


The  signal-key,  in  its  more  perfect  construction,  is  represented  in  Fig.  3392.  It  consists  of  a lever, 
mounted  on  a horizontal  axis,  with  a knob  of  ivory  for  the  hand  at  the  extremity  of  the  long  arm,  which 
is  at  the  right  in  the  figure.  This  lever  is  tlirown  up  by  a spring,  so  as  to  avoid  contact  with  the  button 
on  the  frame  below,  except  when  the  lever  is  depressed  for  the  purpose  of  completing  the  circuit.  A 
regulating  screw  is  seen  at  the  extremity  of  the  short  arm  of  the  lever,  which  graduates  precisely  the 
amount  of  motion  of  which  it  is  at  any  time  capable. 

3393. 


The  registering  part  of  Morse’s  telegraph  is  shown  in  Fig.  3393.  Two  screw-cups  are  seen  on  tne 
board,  intended  for  the  insertion  of  the  wires  from  the  distant  battery.  Next  the  screw-cups  is  seen  a 
U-shaped  electro-magnet,  with  coils  of  wire  upon  it,  the  ends  of  which,  passing  down  through  the  board, 
are  connected  with  the  screw-cups.  Over  the  poles  of  the  magnet  is  a little  armature,  or  bar  of  soft 
iron,  attached  to  the  short  arm  of  a lever,  whose  long  arm  carries  a point  or  style,  nearly  in  contact 
with  the  grooved  roller  above.  The  action  which  takes  place,  on  depressing  the  signal-key  at  the  dis- 
tant station,  is,  in  the  simplest  terms,  as  follows : A wave  of  electricity  is  transmitted  over  the  wire  of 
the  telegraph,  arrives  at  the  electro-magnet,  and  circulates  through  the  coil  of  wire  surrounding  it.  The 
U-shaped  soft  iron  becomes  at  once  a magnet,  (see  Magnetism,)  and  attracts  the  little  armature  down 
to  it.  The  long  arm  of  the  lever  is  thrown  up,  and  marks  the  strip  of  paper  passing  between  it  and 
the  roller.  When  the  distant  operator  lets  the  signal-key  fly  back,  and  the  current  ceases,  the  iron 


694 


TELEGRAPH. 


of  the  electro-magnet  losing  all  its  magnetism,  and  the  armature,  with  the  lever,  is  carried  back  by 
the  action  of  a little  spring,  being  a dot  impressed  upon  the  strip  of  paper.  Should  the  distant  opera- 
tor hold  down  the  key,  a continuous  current  will  pass,  and  a line  is  marked  on  the  paper  which  mover 
under  the  roller. 


/ 

h 


t — 


The  complete  registering  instrument,  shown  in  Fig.  3304,  is  a large  spool,  on  which  the  strip  c4 
paper  is  wound,  and  clock-work,  with  rollers,  give  the  strip  a steady  motion  onwards  under  the  style 
upon  the  lever  of  the  electro-magnet.  A bell  may  also  be  added,  which  is  struck  by  its  hammer  on  the 
first  motion  of  the  lever,  to  draw  attention.  There  is  a stop-motion  sometimes  used,  by  which  the  clock- 
work is  brought  to  rest  in  a few  seconds  after  the  lever  ceases  to  act,  and  which  is  released  again  bv 
the  first  motion  of  the  lever. 

The  annexed  is  the  combination  of  dots  and  morse’s  telegraphic  alphabet. 
lines  on  the  fillet  of  paper  used  by  Professor  Morse 
to  indicate  the  different  letters  and  numbers. 

Between  each  letter  of  a word  a short  space  is  ^ p 

allowed,  between  words  a longer  space,  and  be- 
tween sentences  a still  longer  one.  Many  short-  c - - - 9 

hand  signals  are  also  employed. 

Where  a long  circuit  is  used,  the  resistance  to 
conduction,  measured  by  the  amount  of  electricity 
which  passes,  is  very  great.  The  diminution  of 
the  current  is  most  sensible  when  tested  through 
the  first  few  miles  of  wire,  the  amount  which  sub- 
sequently passes  appearing  nearly  constant  for  a 
long  distance.  It  is  not,  however,  sufficient,  in  its 
electro-magnetic  effects,  to  work  one  of  Morse’s 
registers  directly.  The  current,  which  has  trav- 
ersed a great  length  of  wire,  can  only  move  the 
lever  of  the  electro-magnet  sufficiently  to  bring  a 
platina  point  in  contact  with  a little  platina  disk 
placed  opposite  to  it,  so  as  to  complete  the  circuit 
of  a local  battery,  which  works  the  register  with 
energy.  This  is  the  principle  of  combination  of 

circuits,  and  constitutes  the  important  invention  n _ | 

of  the  receiving  magnet  and  relay  or  local  battery, 

as  they  are  familiarly  known  in  connection  with  Morse’s  telegraph. 

The”  effect  of  the  combination  of  circuits  is  to  enable  a weak  or  exhausted  current  to  bring  into  action, 
and  substitute  for  itself,  a fresh  and  powerful  one.  This  is  an  essential  condition  to  obtaining  useful 
mechanical  results  from  electricity  itself,  where  a long  circuit  of  conductors  is  used,  and  accordingly  it 
received  the  attention  of  early  experimenters  with  the  telegraph.  This  principle  seems  to  have  been 
first  successfully  applied  by  Professor  Joseph  Henry,  of  Princeton  College,  in  the  latter  part  of  1836. 
He  was  thus  enabled  to  ring  large  bells  at  a distance,  by  means  of  a combined  telegraphic  and  local 
circuit.  In  the  early  part  of  1831,  Wheatstone,  in  England,  used  a combining  instrument,  which  con- 
sisted of  a magnetic  needle,  so  arranged  as  to  dip  an  arch  of  wire  into  two  mercury  cups,  when  deflected 
by  a feeble  current,  thus  completing  the  circuit  of  a local  battery,  which  struck  a signal-bell.  Davy 
patented  in  England,  in  1838,  a system  of  combined  circuits,  for  four  different  purposes  connected  with 
his  telegraph.  He  brought  into  action  a local  circuit,  1st,  to  discolor  or  dye,  by  electro-decomposition, 
the  calico  on  which  he  registered  his  signs  ; 2d,  to  actuate  an  electro-magnet  regulating  the  motion  ol 
the  calico ; 3d,  to  direct  the  long  or  telegraphic  circuit  to  either  of  two  branches,  by  means  of  a receiv- 
ing instrument  placed  at  their  point  of  meeting,  and  operated  upon  from  a distance ; 4th,  he  provides 
for  a complete  system  of  relays  of  long  circuits.  His  instrument  resembled  Wheatstone  s,  only  the  con* 
.act  was  made  by  two  surfaces  of  metal,  without  the  use  of  mercury. 


NUMERALS. 


0 


TELEGRAPH. 


695 


The  receiving  magnet  used  by  Professor  Morse  is  a very  slight  modification  of  his  register,  the  platiria 
noint  for  completing  the  local  circuit  being  substituted  for  the  marking  point.  The  magnet  is  sur 
■minded  with  helices  of  tine  wire,  which  multiply  the  effects  of  the  feeble  current,  and  the  whole  instru- 
ment is  constructed  with  delicacy.  By  Morse’s  patent  of  1840,  this  is  applied  to  the  combination  o( 
long  circuits,  or  the  relay  of  currents ; and  by  his  patent  of  1846,  it  is  applied  to  operating  the  register 
by  a local  or  office  circuit.  The  electro-magnet,  armature,  and  lever,  constituting  the  chief  part  of  botn 
these  instruments,  is  simply  the  electro-magnet  of  Professor  Henry,  described  in  1831. 

In  a line  of  telegraph  of  several  hundred  or  thousand  miles,  any  number  of  receiving  magnets  may 
be  interspersed,  as  they  do  not  interrupt  the  circuit.  Each  one  of  these  may  work  a local  register,  and 
thus  the  same  message  may  be  recorded  at  a multitude  of  places,  practically  at  the  same  moment  oi 
time.  If  the  receiving  magnet  is  to  effect  a relay  of  currents,  the  motion  of  its  lever  brings  into  action 
a powerful  battery  on  the  spot,  which  works  the  next  receiving  magnet  in  succession,  and  so  on. 

The  use  of  the  receiving  magnet,  however,  for  the  purpose  of  relay  of  the  galvanic  force,  may  be  hi? 
pensed  with  by  simply  increasing  the  number  of  pairs,  and  distributing  them  in  groups  along  the  line 
Thus  Mr.  Sears  C.  Walker,  of  the  Coast  Survey,  writes,  “ We  have  made  abundant  experiments  on  the 
line  from  Philadelphia  to  Louisville,  a distance  in  the  air  of  nine  hundred  miles,  and  in  circuit  of  eighteen 
hundred  miles.  The  performance  of  this  long  line  was  better  than  that  of  any  of  the  shorter  lines  has 
hitherto  been.  I learn,  from  au  authentic  source,  that  the  same  success  attends  the  work  from  Phila- 
delphia to  St.  Louis,  a distance  in  circuit  of  one-twelfth  of  the  earth’s  circumference.  The  number  oi 
Grove’s  pint  cups  used  is  about  one  for  every  twenty  miles.  It  is  natural  to  conclude,  from  this  experi- 
ment, that,  if  a telegraph  line  round  the  earth  were  practicable,  tv’elve  hundred  Grove’s  pint  cups,  in 
equidistant  groups  of  fifties,  would  suffice  for  the  galvanic  power  for  the  whole  line.  The  daily  ex- 
pense of  acids,  for  maintaining  this  whole  line,  would  be  about  five  mills  per  day  for  each  cup,  or  six 
dollars  per  day  for  the  whole  line.”  This  distribution  of  the  galvanic  agency  is  frequently  adopted  in 
the  mode  of  placing  one  half  of  the  necessary  number  of  pairs  at  each  extremity  of  the  line. 

The  conductors  hitherto  spoken  of  have  been  exclusively  the  telegraph  wires.  It  has  now,  however, 
become  a universal  custom  to  use  the  earth  as  one-half  of  the  circuit,  and  thus  to  employ  but  one  wire. 
T his  is  accomplished  by  carrying  a wire  down  at  each  extremity  of  the  line,  and  connecting  it  with  a 
metallic  plate  buried  in  the  earth.  The  advantage  consists  not  only  in  the  economy  of  employing  a 
single  wire  to  each  circuit,  but  the  loss  from  conduction  by  using  the  earth  is  vastly  less.  The  use  of 
the  ground  circuit  for  the  telegraph  seems  to  be  due  to  Professor  Steinheil,  of  Munich. 

In  case  of  interruption  of  the  telegraph  wire,  much  ingenuity  lias  been  shown  by  the  association  of  a 
through  line  and  a test  line,  which  latter  communicates  with  a number  of  intermediate  stations,  and  by 
means  of  which  the  place  of  interruption  can  be  readily  ascertained,  and  the  injury  repaired.  An  in- 
terruption is  shown  by  the  increased  strength,  the  weakness,  or  the  suspension  of  the  current,  which 
each  station  has  the  means  of  examining,  and  from  which  the  direction  and  nature  of  the  accident  can 
be  inferred. 

A great  source  of  irregularity  in  the  action  of  the  telegraph,  in  this  country,  has  been  atmospheric 
electricity.  The  air  being  in  different  electrical  states  in  different  places,  or  thunder-storms  taking  place 
in  the  course  of  the  line,  the  insulated  telegraph  wires  frequently  become  the  medium  of  transfer  of 
atmospheric  electricity.  The  safety  of  the  operators,  and  even  the  regular  action  of  the  electro-magnet, 
requires  the  use  of  conductors  at  the  stations,  which  are  nearly  in  contact  with  the  wires,  and  which 
communicate  with  the  earth,  so  as  to  carry  off'  any  excessive  charge  of  electricity  which  might  destroy 
the  instrument,  or  even  endanger  life.  Much  irregularity  in  the  action  of  the  telegraph  still  exists  from 
this  cause. 

These  facts  of  general  application  to  the  electric  telegraph  have  been  considered  here,  as  many  oi 
them  were  first  developed  and  applied  in  this  country,  in  connection  with  Morse’s  register.  This  in- 
strument, and  the  system  connected  with  it,  will  always  deserve  credit  for  its  early  service  in  adapting 
the  telegraph  to  our  climate  and  natural  resources. 

Lightning  Protector.  By  L.  Pocget,  Maisonneuve.  This  is  a beautiful  and  most  important  discovery 
as  an  auxiliary  in  the  perfection  and  full  development  of  the  electric  telegraph.  It  is  designed  to  drain 
off  the  atmospheric  electricity,  which  in  certain  conditions  of  the  atmosphere  accumulates  in  the  wire, 
seriously  interrupting  the  transmission  of  signals  by  deranging  the  magnets,  and  often  even  melting  and 
destroying  them.  The  beauty  of  the  invention  is  in  its  simplicity  : it  consists  in  the  discovery  that 
absolute  alcohol,  after  having  been  subjected  to  proper  chemical  treatment,  becomes  a good  conductor  of 
the  high  tension  electricity  of  the  atmosphere,  while  it  is  a non-conductor  of  the  current  generated  by 
the  galvanic  battery. 


The  apparatus  consists  simply  of  a glass  tube,  two  inches  in  diameter  by  five  in  length,  filled  with  the 
prepared  liquid,  and  a brass  cap  hermetically  sealed  to  each  end.  The  telegraph  wire  is  made  to  pass 
through  the  tube,  and  is  surrounded  by,  and  is  in  direct  contact  with  the  liquid.  On  one  side  of  the 
tube  is  introduced  a wire  connecting  with  the  ground,  which  terminates  in  the  liquid,  but  does  not  come 
in  metallic  contact  with  the  former  wire.  Its  operation  is  as  follows  : 

The  accumulations  of  high  tension  electricity  from  the  atmosphere  pass  along  the  wire  until  they 
enter  the  tube,  where  they  leave  the  wire,  pass  through  the  liquid  to  the  ground  wire,  and  thence  to 
the  great  reservoir  of  electricity,  in  the  earth.  Thus  the  line  wire  is  relieved  of  the  disruption  dis- 
charges, which  otherwise  would  pass  through  and  interrupt  the  proper  action  of  the  magnets,  and  the 
battery  current  is  left  free  from  disturbance,  and  goes  on  to  its  destination,  performing  its  mission  with 
fidelity. 

Bain  s Telegraph.  The  telegraph  of  Bain,  represented  in  fig.  3395,  is  constructed  on  the  principle 
of  the  decomposition  of  a saline  solution,  through  which  a galvanic  current  passes,  and  is  the  most  sim- 
ple now  in  use.  The  indication  of  the  current  takes  place  here  without  motion.  The  circular  tablet, 
on  which  the  writing  is  obtained,  is  moved  by  clock-work,  at  a uniform  rate,  under  the  wire,  which  con 
stitutcs  the  telegraphic  pen.  But  the  pen  itself  never  stirs.  It  bears  silently  on  the  tablet,  and  as  the 


696 


TELEGRAPH 


eye  observes  the  point  of  contact,  now  a blank  space,  and  now  a deep  blue  line,  appears  upon  the  re- 
treating  surface.  This  is  the  record  of  the  intermitting  current,  sent  over  the  wires  from  a distance. 

In  Fig.  3395  the  clock-work  which  moves  the  tablet  is  seen  on  the  left.  Its  motion  is  regulated  by 
n fly-wheel  above,  the  vanes  of  which  can  be  inclined  so  as  to  present  greater  or  less  resistance  to  the 
an.  A lever  or  break  bears  upon  the  axle  of  the  fly-wheel,  by  moving  which  lever  the  clock-work  may 
be  stopped,  or  allowed  to  go  on.  The  circular  disk,  or  tablet  of  brass,  carried  by  the  clock-work,  is  seen 
on  the  right  of  the  figure,  inclined  towards  the  observer.  In  the  centre  of  the  disk,  occupying  the  shaded 
portion,  a spiral  groove  is  cut,  in  which  the  guide  to  the  pen  travels.  This  guide  is  seen  attached  at 
right  angles  to  the  penholder,  which  extends  over  the  disk.  The  pen-wire  is  seen  held  by  a little 
clamp,  descending  so  as  to  touch  the  tablet.  This  wire,  of  course,  traces  a spiral  upon  the  outer  ring 
of  the  disk’s  surface,  exactly  corresponding,  in  the  distance  of  its  lines,  to  the  spiral  groove  within, 
which  serves  as  a guide.  By  this  beautiful  contrivance,  the  writing  is  disposed  in  a close  spiral,  occu- 
pying but  very  little  space. 

The  outer  part  of  the  surface  of  the  disk,  upon  which  the  letters  are  represented  in  the  figure,  is 
covered  with  a ring  of  moistened  and  chemically  prepared  paper.  This  may  be  renewed  or  removed 
at  pleasure.  The  penholder  is  connected  with  the  positive  wire  of  the  telegrajih,  and  the  tablet  with 
the  negative.  The  circuit  of  conductors  is  completed  by  the  moistened  paper  which  intervenes,  and 
which  the  current  accordingly  traverses.  This  paper  is  moistened  w'ith  a solution  of  the  yellow  prus- 
siate  of  potash,  acidulated  with  nitric  or  sulphuric  acid.  The  pen-wire  consists  of  iron.  When  the 
current  passes,  this  pen-wire  is  attacked  by  the  solution,  and  the  portion  of  iron  dissolved  unites  with 
the  prussiate  of  potash  to  form  the  color  known  as  Prussian  blue,  which  permanently  stains  or  dyes 
the  paper. 

A modification  in  the  mode  of  marking  has  been  introduced  in  this  telegraph  by  Mr.  Rogers,  of  Bal- 
timore. He  substitutes  a pen  carrying  an  ink  which  is  decomposed  by  the  current  when  in  contact  with 
the  brass  disk,  without  any  intervening  paper.  A superficial  stain  is  produced  on  the  metallic  surface, 
which  is  easily  obliterated  by  friction. 

3395.  3305. 


In  Bain’s  telegraph,  no  receiving  magnet  is  necessary.  The  current  traversing  the  long  wires  is  suffi- 
cient to  leave  its  trace  upon  the  paper.  There  would  be  a disadvantage,  however,  in  the  use  of  this 
telegraph,  with  a simple  circuit,  where  it  is  desirable  to  register  the  same  communication  at  a number 
of  different  places,  as  the  interposition  of  the  paper,  moistened  with  a saline  solution,  somewhat  obstructs 
the  current.  The  receiving  magnet  and  register  used  by  Morse  present  a metallic  conductor  for  the 
current  throughout,  and  they  can,  therefore,  be  multiplied  without  serious  loss.  To  compensate  this 
disadvantage,  a system  of  branch  circuits  at  way-stations  has  been  devised,  in  connection  with  the  Bain 
telegraph,  by  which  communications  can  be  received  at  various  places  at  the  same  time.  Morse’s  in- 
strument requires  the  time  taken  by  the  motion  of  the  armature  to  make  each  mark.  The  decomposi- 
tion in  Bain’s  instrument  is  instantaneous.  This  is  an  advantage  where  mechanical  means  are  used  to 
complete  and  break  the  circuit  W'itli  great  rapidity  for  the  purpose  of  rapid  communication. 

An  ingenious  instrument  to  effect  this  object  has  been  recently  contrived.  One  of  the  circular  me- 
tallic disks  of  the  register  has  its  surface  coated  with  wax  or  other  composition.  The  lines  and  dots 
which  constitute  the  writing  to  be  transmitted,  are  scratched  through  this  so  as  to  expose  the  metal,  by 
the  operator,  previous  to  completing  the  telegraphic  circuit.  This  writing  is  effected,  and  disposed  in 
spirals  around  the  disk,  by  simply  putting  a little  signal-key  in  place  of  the  pen-wire,  and  allowing  the 
uisk  to  revolve.  The  guide  to  the  penholder,  of  course,  carries  the  signal-key  over  the  same  spiral 
which  the  pen-wire  would  describe  on  the  disk.  The  signal-key  lias  a sharp  or  cutting  point.  which 
removes  the  wax  from  the  disk  whenever  the  key  is  depressed.  The  usual  motion  for  signalizing  the 
letters,  therefore,  prepares  the  impression  of  the  writing,  which  is  afterwards  to  be  connected  with  the 
telegraph,  and  transmitted  with  speed.  This  transmission  is  effected  by  restoring  again  the  pen-wire 
’,o  its  holder,  and  allowing  it  to  follow  over  the  track  just  made  by  the  signal-key.  The  battery  being 
connected,  the  wire  completes  the  circuit  whenever  it  touches  the  exposed  metal,  and  breaks  the  circuit 
when  it  rests  upon  the  wax.  The  disks  at  both  the  transmitting  and  receiving  ends  are  made  finally  to 


TELEGRAPH. 


697 


revolve  rapidly,  and  the  message  is  said  to  be  thus  communicated  at  the  rate  of  one  thousand  or  more 
letters  per  minute. 

The  alphabet  used  by  Bain  is  the  same  in  principle  as  that  employed  by  Dyar,  Steinheil,  and  also  bv 
Morse,  consisting  of  combinations  of  dots  and  lines. 

The  call,  commonly  used  on  the  Bain  lines,  is  represented  in  Fig.  3396.  It  consists  of  a U-shapea' 
receiving  magnet,  placed  horizontally  on  the  board,  with  two  helices  of  wire  surrounding  the  leg3.  An 
armature,  supported  on  an  upright  bar,  so  as  to  form  a cross,  is  seen  in  the  figure  before  the  poles  ot 
the  magnet.  This  is  held  back  by  a delicate  spiral  spring,  graduated  by  a screw,  which  is  also  seen  to 
the  left.  Above  are  two  circular  plates  of  glass.  The  upright  bar,  armed  with  two  little  knobs,  to 
perform  the  part  of  a hammer,  rises  between  these  plates.  When  the  armature  is  drawn  to  the  mag- 
net, it  strikes  one  of  them,  and  on  being  drawn  back  it  strikes  the  other.  As  they  are  of  different  tone, 
the  repetition  of  this  signal  at  once  draws  attention  to  the  register.  The  duty  of  the  operator  is  then  to 
set  the  clock-work  in  motion,  and  receive  the  message  communicated.  This  instrument  can  be  used 
also  as  a receiving  magnet,  by  placing  a platinum  point  on  the  upright  bar  or  pendulum,  and  a little 
platinum  disk  immediately  in  front  of  it,  so  connected  that  the  interval  between  the  point  and  disk  shall 
constitute  the  break  in  a local  circuit,  an  additional  pair  of  screw-cups  for  the  attachment  of  which 
may  be  seen  upon  the  base-board.  When  the  armature  approaches  the  electro-magnet,  it  closes  the 
local  circuit,  and  when  it  recedes  it  breaks  it.  This  is  essentially  the  receiving  instrument  of  Morse 
and  others. 

This  call  is  similar  in  purpose  or  principle  to  those  used  by  Soemmering  in  1811,  Schilling  in  1831, 
and  Henry,  Steinheil  and  Wheatstone  in  1836  and  1837. 

Bain’s  telegraph  has  been  introduced  very  extensively  into  this  country,  especially  in  connection  with 
the  network  of  lines  constructed  throughout  the  South  and  West  by  the  enterprise  of  O’Reilly. 

The  receiving  magnet  in  its  improved  form,  Fig.  3397,  used  for  the  purpose  of  combining  or  connect- 
ing circuits,  is  closely  allied  in  its  construction  to  the  call, 
and  may  therefore  be  described  here,  though  already  referred 
to  in  connection  with  Morse’s  telegraph.  The  armature  is 
mounted  on  an  upright  bar,  and  is  seen  forming  part  of  the 
cross  just  in  front  of  the  poles  of  the  horizontal  electro-mag- 
net, surrounded  with  helices  of  fine  wire.  The  long  or  tele- 
graphic circuit  is  connected  with  these  helices  by  means  of 
two  of  the  screw-cups  on  the  board.  When  the  current  flows, 
the.  armature  is  attracted  to  the  magnet,  and  the  upright  bar 
is  brought  in  contact  with  the  end  of  the  horizontal  screw, 
seen  at  the  top  of  the  instrument.  This  completes  a local 
circuit,  or  branch  circuit  from  the  main  battery,  the  conduc- 
tors of  which  are  connected  with  the  instrument  by  means 
of  two  other  serew-cups,  seen  on  the  left  of  the  hoard.  The 
points  of  contact  of  the  upright  bar  and  screw  are  protected  from  oxidation  by  the  use  of  platinum 

TELEGRAPHIC  COMPOSITOR.  The  experience  of  Bain  and  others,  in  transmitting  signals  by 
electricity,  has  demonstrated  that  the  amount  of  time  requisite  to  send  a message  to  a distant  place,  is 
not  dependent  upon  the  speed  with  which  the  electricity  travels,  but  upon  the  time  in  which  the  human 
hand  can  perform  the  proper  manipulations.  This,  in  actual  practice,  as  experience  with  the  various 
methods  in  use  has  proved,  has  never  reached  an  average  of  more  than  eighty  letters  per  minute.  In 
the  mean  time  the  researches  in  electricity  have  shown,  that  when  the  wave  or  pulsation  is  given  to  the 
current  by  the  finger,  it  flies  to  its  destination  with  the  swiftness  of  thought,  though  its  path  may  he 
thousands  of  miles  in  length,  and  leading  over  precipitous  mountains  and  through  barren  deserts. 

The  telegraphic  compositor  was  invented  by  J.  P.  Humaston,  of  New  Haven,  Connecticut,  and  was 
patented  September  8,  1857.  Its  object  is  to  increase  the  rapidity  of  manipulation  so  that  it  shall  bear 
some  fair  proportion  to  the  capacity  of  electricity  to  record  the  signals.  This  is  effected  by  an  instru- 
ment termed  a compositor , which  cuts  the  dots  and  lines  of  the  telegraphic  letters  in  a strip  of  paper  of 
about  three-eighths  of  an  inch  in  width.  The  message  thus  prepared  is  passed  through  the  transmitting 
instrument,  which  may  be  run  at  any  speed  requisite  to  keep  pace  with  the  record  of  the  signals.  This 
speed  with  the  magnetic  instruments,  is  not  more  than  about  three  hundred  letters  per  minute  ; this  is 
owing  to  the  fact  that  they  require  machinery  whose  moving  parts  have  weight  and  inertia.  With  the 
electro-chemical  mode,  Mr.  Bain,  in  1846,  transmitted  as  many  as  one  thousand  letters  per  minute  be- 
tween London  and  Manchester,  England  ; this  was  done  by  preparing  the  message  strip  by  hand,  and 
then  passing  it  rapidly  between  the  poles  of  contact  in  the  electro-chemical  instrument. 

The  compositor  consists  of  a key-board  and  twelve  small  steel  cutters,  which  lie  side  by  side  ; the  keys 
are  connected  with  the  cutters  in  such  a manner,  that  when  any  key  is  depressed,  the  cutters  are  carried 
forward,  and  through  the  paper  in  the  proper  combination  to  form  the  letter  which  it  represents.  This  is 
done  as  rapidly  as  the  touch  can  be  made,  and  a single  touch  forms  the  letter  with  mathematical  certainty 
and  accuracy.  The  compositor  is  to  the  telegraph  wire  what  the  font  of  type  is  to  the  printing  press, 
and  any  number  of  compositors  may  be  used  to  prepare  the  messages  which  the  capacity  of  the  wire  will 
enable  it  to  transmit.  Thus  far,  its  use  has  proved  that  one  well  insulated  wire  will  transmit,  per  day 
of  12  hours,  10,800  messages  of  ten  words  each.  To  do  this  with  any  system  depending  upon  the, 
manipulation  or  touch  of  the  finger  direct,  would  require  the  use  of  at  least  ten  wires  and  twenty  in- 
struments. With  the  rapid  extension  and  future  development  of  the  telegraph,  this  improvement  fur- 
nishes the  means  of  reducing  the  tariff  for  telegraphing  to  a point  low  enough  to  bring  it  within  the 
means  of  every  human  being  possessing  sufficient  intelligence  to  commit  his  thoughts  to  writing.  It  can 
be  used  as  an  auxiliary  to  the  magnetic  telegraph,  and  is  readily  changed  to  any  system  of  telegraphic 
alphabet.  Its  usefulness  however  is  greatly  enhanced  in  connection  with  the  electro-chemical  instru- 
ment, which  records  its  signs  by  the  simple  pulsations  of  the  electric  current. 


698 


TELEGRAPH. 


Home's  Printing  Telegraph.  This  beau- 
tiful  invention  may  be  considered  as  one  of 
the  wonders  of  the  age.  Using  but  a single 
wire,  it  is  yet  able  to  select  and  print  in 
order  the  letters  of  the  common  alphabet, 
with  a greater  rapidity  than  the  hierogly- 
phic marks  of  Professor  Morse,  representing 
the  same  letters  can  he  produced. 

This  instrument  is  complicated,  though 
all  its  parts  are  simple.  We  shall  try  to  de- 
scribe it  so  that  the  mode  of  its  operation 
may  be  understood.  A perspective  view  of 
the  instrument  is  shown  in  Fig.  3398,  com- 
prising both  the  transmitting  and  receiving 
apparatus.  The  principle  by  which  the  dif- 
ferent letters  are  signalized  over  the  wire,  is 
the  transmission  of  a given  number  of  elec- 
trical impulses  for  each  letter,  by  the  rapid 
opening  and  closing  of  the  circuit.  This  is 
accomplished  by  means  of  the  twenty-six 
letter-keys,  and  the  two  keys  for  the  dot  and 
dash,  seen  in  the  figure.  Under  the  key-board 
is  a horizontal  cylinder,  which  is  kept  in  revolution  by  turning  the  crank  and  wheel,  seen  at  the  left  of  the 
figure.  At  one  end  of  this  cylinder  is  a circuit-wheel  or  break-piece,  having  fourteen  projections  and 
fourteen  spaces,  on  which  a spring,  connected  with  the  telegraphic  circuit,  bears.  Consequently  the 
battery  circuit  is  completed  fourteen  times  and  broken  fourteen  times  with  each  revolution  of  the  cyl- 
inder. Under  each  key  a projection  or  stop  is  placed  upon  the  cylinder,  in  such  a position  that  when 
the  key  is  depressed  and  comes  in  contact  with  it,  the  cylinder  shall  have  performed  such  part  of  a 
revolution  as  to  have  made  and  broken  the  circuit  the  number  of  times  which  represents  the  letter  cor- 
responding to  the  key.  The  motion  of  the  cylinder  is  communicated  by  means  of  slight  friction,  and  it 
is  accordingly  arrested  by  depressing  the  key.  This  is  the  transmitting  or  “ composing”  apparatus. 

The  receiving  or  printing  apparatus  is  seen  behind  the  key-board  in  the  figure.  There  is  one  such  at 
each  extremity  of  the  line,  to  receive  messages  transmitted  from  the  other  extremity.  But  both  are 
left  constantly  in  the  circuit,  so  that  the  operator  signalizes  or  prints  the  message  which  he  sends  both 
at  the  distant  end  of  the  line  and  immediately  before  his  eyes.  The  printing  instrument  which  we  are 
examining  is,  therefore,  a fac-simile  of  the  one  which  receives  the  communication  at  a distance  from  the 
operator  at  the  key-board  in  the  figure. 

The  printing  apparatus  consists  of  an  upright  rod-electro-magnet,  inclosed  in  the  metallic  cylinder  A 
of  a little  engine,  operated  by  condensed  air,  and  moving  an  escapement  at  B ; of  a type-wheel  at  C 
of  a printing  eccentric  and  lever,  the  end  of  which  is  seen  at  D ; of  a black  coloring-band  at  E,  and  the 
strip  of  printing  paper  at  F F. 

The  electro  magnet  consists  of  a compound  rod  of  several  short  pieces  of  iron  strung  upon  a rod  or 
brass.  This  rod  is  inclosed  in  a tube  of  brass,  attached  to  which,  within,  are  several  short  tubes  of  iron, 
corresponding  to  and  reacting  with  the  pieces  belonging  to  the  axial  magnet.  This  whole  system  of 
tubular  and  axial  magnets  is  inclosed  in  a single  helix  of  fine  wire,  connected  with  the  telegraphic  cir- 
cuit. The  tube  is  fixed,  but  the  compound  rod  is  movable,  and  attracted  downwards  by  several  co- 
operating reactions  when  the  current  passes.  This  rod  is  suspended  by  a cross-wire,  which  may  be  seen 
stretched  across  the  top  of  the  cylinder  A,  and  acts  as  a spring,  drawing  the  rod  back  after  the  current 
has  ceased  to  act.  A very  rapid  vibration  of  the  rod  is  thus  obtained,  corresponding  to  the  opening  and 
closing  of  the  circuit  effected  at  the  transmitting  end  of  the  line. 

Connected  with  the  wheel  is  a condensing  pump  at  G,  which  keeps  up  a supply  of  condensed  air. 
At  the  upper  part  of  the  electro-magnetic  rod  is  a collar- valve,  which  changes  the  direction  of  the  cur- 
rent of  condensed  air  with  each  vibration  of  the  rod,  though  these  vibrations  are  only  l-64th  of  an  inch. 
The  air  is  thus  admitted  to  opposite  sides  of  the  cylinder  of  a little  atmospheric  engine,  which,  by  means 
of  its  reciprocating  motion,  permits  the  action  of  an  escapement,  tooth  by  tooth,  and  the  corresponding 
revolution  of  the  type-wheel,  which  is  impelled  by  a spring  kept  wound  up  by  the  manual  power  em- 
ployed at  the  crank  and  wheel. 

The  result  is  that  the  type-wheel,  which  has  twenty-eight  teeth,  revolves  just  as  far  as  the  cylinder 
attached  to  the  circuit-wheel,  at  the  distant  extremity  of  the  line,  has  been  permitted  to  revolve  by  de- 
pressing one  of  the  keys.  Each  break,  as  well  as  each  completion  of  the  circuit,  thus  corresponds  to  a 
letter.  It  only  requires  that  the  instruments  at  both  ends  of  the  line  should  be  set  to  the  same  letter, 
and  then  the  cylinder  at  one  extremity  and  the  type-wheel  at  the  other,  regulated  by  the  pulsations  ot 
the  current,  will  always  revolve  at  the  same  rate ; and  if  the  cylinder  is  stopped  at  any  one  point  rep- 
resenting a letter,  the  type-wheel  is  stopped  at  the  same  point,  and  presents  the  type  which  it  carrie 
on  its  periphery  to  the  strip  of  paper  in  front  of  it. 

When  the  type-wheel  stops,  an  eccentric,  actuated  also  by  the  local  power  at  the  crank  and  wh< 
brings  the  black  band  and  paper  forcibly  against  the  type,  and  leaves  the  impression  of  the  let 
The  paper  is  then  carried  on  just  the  distance  of  a letter,  and  is  ready  for  another  impression.  Roman 
letters  are  thus  printed  over  a long  line  at  the  rate  of  from  one  hundred  and  fifty  to  more  than  two 
hundred  a minute. 

In  the  figure  the  letter  A will  be  observed  at  a little  window  above  the  type-wheel.  This  letter  is 
>n  a letter-wheel,  connected  with  the  type-wheel  below,  so  that  the  letters  may  be  presented  to  the 


TELEGRAPH. 


C9S 


sight  at  the  same  time  as  printed ; or  the  printing  eccentric  may  be  detached,  and  only  the  visible 
letters  read. 

The  action  of  the  electricity  in  this  telegraph  is  merely  to  produce  correspondence  of  motion  in  ma- 
chinery at  different  ends  of  the  line,  in  the  same  manner  that  uniformity  of  rate  has  been  secured  in 
clocks  at  different  places,  regulated  by  the  electro-telegraphic  current.  All  the  mechanical  results  of 
House’s  telegraph  are  produced  by  local  mechanical  power.  For  this  purpose,  clock-work,  having  a 
regular  rate,  would  be  preferable  to  manual  power. 

Horn's  igniting  telegraph. — The  register  invented  by  G.  H.  Horn  employs  a principle  never  before 
applied  to  the  telegraph,  namely,  the  heating  or  igniting  effect  of  electricity.  When  an  electrical  cur- 
rent flows  through  a fine  platinum  wire  it  ignites  it,  or  brings  it  to  a red-heat.  If  this  wire  is  bent,  as 
at  A,  in  the  figure  below,  so  as  to  be  in  contact,  for  a short  distance,  with  a moving  fillet  of  paper,  it 
will  burn  a hole  through  the  paper  when  the  current  passes.  This  can  be  done  with  great  rapidity,  so 
as  to  represent  probably  a hundred  linear  letters  per  minute. 


3399. 


This  instrument  is  shown  in  Fig.  8399,  the  greater  part  of  which  consists  of  the  clock-work,  spool,  <5rc, 
required  for  moving  the  paper.  Above  the  clock-work  are  two  pillars,  supporting  an  axis,  upon  which 
is  the  adjustable  wire-holder,  the  lower  extremity  of  which  is  seen  touching  the  fillet  of  paper.  By 
means  of  the  connections  and  insulations  of  the  pillars,  axis,  and  wire-holder,  the  platinum  wire,  which' 
passes  over  a little  slip  of  porcelain  at  the  end  of  the  wire-holder,  becomes  part  of  the  circuit,  with 
which  the  two  screw-cups  on  the  right  of  the  base-board  are  connected.  When  the  wire  needs  adjust- 
ment, the  wire-holder  can  be  turned  up  on  its  axis.  The  bed  supporting  the  fillet  of  paper  is  also  ad- 
justable, so  as  to  regulate  the  contact  between  the  wire  and  the  paper. 

This  register  requires  a quantity  current  to  produce  the  effect  of  ignition,  and  therefore  needs  a re- 
ceiving instrument  and  local  battery,  to  be  operated  by  the  telegraphic  circuit. 


3400.  2401. 


700 


TELEGRAPH. 


of  this  reaction  is  so  great,  that  it  has  been  successfully  applied  by  Prof.  Charles  G.  Page,  of  Washing- 
ton, to  the  propulsion  of  machinery  on  a large  scale. 

The  axial  telegraph  is  represented  in  a simple  form  in  Fig.  3100.  The  U-shaped  iron  rests  upon  a 
spring,  seen  on  the  board.  A style  attached  to  the  iron,  projects  up  between  the  coils  so  as  to  be  nearly 
in  contact  with  the  roller,  under  which  the  strip  of  paper  is  made  to  pass.  A little  rod  or  armature  of 
iron,  placed  across  the  top  of  the  coils,  causes  the  soft  iron  to  move  in  obedience  also  to  electro-magnet- 
ic attraction,  somewhat  increasing  the  power,  but  introducing  a new  and  unnecessary  principle  into 
the  reaction.  The  axial  telegraph  in  its  complete  form,  is  represented  in  Fig.  3401,  where  the  spool 
and  clock-work  for  the  movement  of  the  paper  are  added. 

The  axial  motion  is  due  to  the  deflective  power  of  a coil,  as  in  the  telegraphs  of  Amphere,  Steinheil, 
and  Wheatstone,  and  not  to  electro-magnetic  attraction.  This  instrument  requires,  on  a long  line,  the 
intervention  of  a receiving  instrument  and  short  circuit. 

Telegraph , Hughes.  The  Hughes  instrument  consists  of  a train  of  clock  work,  keys  for  closing  the 
circuit,  an  electro-magnet,  and  a vibrating  spring  to  govern  the  type  wheel,  which  revolves  by  aid  of  the 
train  of  wheels.  The  clock  work  consists  of  four  cog  wheels,  turned  by  a weight,  which  turns  a shaft 
with  a wheel,  upon  which  are  engraved  the  letters  of  the  alphabet.  This  wheel  is  inked  by  a small  roll- 
er. Below  the  type  wheel  a small  press  moves  the  paper  to  be  printed  upon  against  the  letters.  This 
press  moves  only  when  the  armature  of  the  magnet  acts  by  a current  of  electricity  being  sent  along  the 
line. 

The  magnet  of  the  Hughes  instrument  is  a peculiarly  simple  and  effective  arrangement,  by  which 
electricity  is  made  to  work  at  its  highest  development.  Electricity  only  holds  the  armature  whilst  in 
contact.  As  soon  as  it  is  set  free  by  the  distant  operator  closing  the  circuit,  it  falls  against  a detent 
which  brings  a small  cam  in  play,  and  restores  the  armature  to  its  resting  place  in  contact  with  the 
electro-magnet.  This  operation  is  performed  every  letter  that  is  printed,  the  magnet  never  acting  until 
a letter  is  sent,  and  then  only  once  to  each  letter. 

The  principle  of  making  all  the  instruments  keep  exact  time  with  one  another,  so  that  they  always 
present  a certain  letter  opposite  the  press  at  the  same  instant,  and  also  to  revolve  rapidly,  has  been  ac- 
complished by  the  union  of  a well  known  law  in  acoustics  to  mechanics : thus  a certain  number  of  vi- 
brations per  second  produces  a certain  musical  tone ; if  these  two  instruments  have  each  a vibrating 
spring  of  the  same  tone,  the  two  instruments  must  always  revolve  in  exact  time  with  each  other. 

These  type  wheels,  revolving  by  means  of  clock  work,  carry  around  with  them  a circuit  closer,  which 
travels  over  twenty-eight  pins  corresponding  to  the  letters  upon  type  wheels ; if  any  of  these  pins  are 
touched  by  corresponding  keys,  the  circuit  is  closed  at  the  moment  the  closer  passes  that  point.  The 
armature  immediately  falls  off,  opens  the  detent  which  locks  the  press  to  the  wheel  work  ; this  moves 
up  the  press,  and  when  the  letter  is  printed  unlocks  itself  until  again  locked  by  the  action  of  the  arma- 
ture. 

The  fact  of  the  possibility  of  writing  both  ways  simultaneously  on  one  wire  has  been  fully  demon- 
strated. This  is  accomplished  by  the  arrangement  of  the  battery,  so  that  it  does  not  affect  the  magnet 
at  the  office  sending,  but  the  instant  that  a distant  office  puts  on  battery  the  magnet  acts  ; thus  each 
magnet  acts  only  from  the  distant  battery,  and  is  not  affected  by  its  own  writing,  whilst  it  receives  per- 
fectly what  is  sent  to  it.  Another  great  feature  in  this  machine  is  the  freedom  of  disturbance  from 
atmospheric  causes.  This  is  caused  by  the  line  being  always  open  except  at  the  instant  of  the  letter 
being  sent ; then  if  in  same  direction,  can  only  assist  the  current  from  the  battery. 

Another  new  feature  is  its  power  of  cutting  off  all  offices  except  those  to  which  it  is  desired  to  com- 
municate. This  is  accomplished  by  a flange  on  the  type  wheel — this  flange  having  a space  cut  out 
opposite  a certain  letter — each  office  having  the  flange  cut  out  at  different  letters  from  each  other.  A 
bolt  is  made  to  slide  through  this  space,  and  moved  through  by  the  action  of  the  instrument.  If  this 
bolt  is  sent  through  at  the  moment  the  space  is  opposite,  it  permits  the  instrument  to  run ; if  not,  it 
goes  against  the  flange  and  locks  the  wheel. 

The  success  of  telegraphs  for  overland  communications  soon  turned  the  attention  to  its  practicability 
as  a submarine  conductor.  As  early  as  in  August  1843,  Prof.  S.  F.  B.  Morse,  in  a letter  to  the  Secre- 
tary of  the  Treasury  of  the  United  States,  speaking  of  an  experiment  which  he  made  the  previous  year, 
of  passing  an  electric  current  through  a submerged  conductor,  says : the  inference  from  this  law  is  that 
a telegraphic  communication  may  with  certainty  be  established  across  the-  Atlantic.  In  the  autumn  of 
1842,  he  submerged  an  insulated  wire  from  the  Battery  to  Governor’s  Island,  and  had  just  begun  to 
operate,  having  received  but  two  or  three  characters,  when  the  wire  was  raised  and  broken  by  being 
drawn  up  with  the  anchor  of  a vessel.  He  also  succeeded  in  transmitting  a current  across  a stream  or 
canal,  by  means  of  parallel  lines  along  the  banks. 

In  the  fall  of  1850,  a wire  of  about  the  size  of  an  ordinary  knitting  needle  encased  in  a coating  of  gutta 
percha,  was  laid  from  Calais  to  Dover ; communications  were  transmitted  for  a time  through  this  wire, 
but  soon  a portion  became  broken,  and  another  cable  was  laid  composed  of  four  copper  wires,  each  insu 
lated  with  gutta  percha,  and  afterwards  bound  together  with  hemp  steeped  in  a solution  of  tar  and  tallow. 

In  May,  1852,  Holyhead  and  Howth,  a distance  of  65  miles  across  the  Irish  Channel,  were  connected 
by  a single  wire  encased  in  gutta  percha.  Scotland  and  Ireland  were  connected  by  a cable  of  thirty 
miles  long  consisting  of  six  wires. 

The  following  June  a cable  was  laid  from  Orfordness,  in  England,  to  the  Hague  in  Holland,  a distance 
of  115  miles.  This  task  was  accomplished  in  thirty-four  hours,  and  only  44  miles  of  cable  were  re- 
quired in  the  paying  out  over  the  actual  length  from  point  to  point,  making  hardly  120  miles  altogether 
Another  cable  connects  Dover  with  Ostend,  making  the  third  between  England  and  the  continent. 

In  the  summer  of  1854  a telegraphic  union  was  effected  between  Corsica  and  Sardinia.  This  work 
was  attended  with  much  difficulty  in  consequence  of  the  breaking  of  a part  of  the  wire.  The  submerg- 
ng  of  a cable  between  Corsica  and  the  island  of  Sardinia  was  successfully  accomplished  shortly  after- 


TELEGRAPH. 


701 


but  the  attempt  which  was  subsequently  made  to  connect  the  island  of  Sardinia  and  Algeria,  and  thus 
establish  immediate  communication  between  the  continents  of  Europe  and  Africa,  was  unsuccessful,  and 
bas  not  since  been  attempted. 

The  New  York,  Newfoundland  and  London  Telegraph  Company  made. an  attempt  in  August  of  1855, 
to  unite  the  islands  of  Newfoundland  and  Cape  Breton,  but  the  vessels  employed  in  the  work  were 
caught  in  a gale,  the  cable  was  obliged  to  be  cut,  and  the  undertaking  abandoned  for  that  time.  The 
cable,  as  may  be  seen  from  the  accompanying  engravings,  which  show  the  exact  size,  had  three  con- 
ductors, and  was  protected  in  the  same  manner,  by  iron  wire,  as  those  already  described. 

3402.  In  1856  the  company  succeeded  in  making  the  desired  connection  be- 

tween the  opposite  shores  of  Newfoundland  and  Cape  Breton.  This  time  they 
rejected  the  three  wire  cable  and  procured  a much  lighter  one,  with  a single 
wire,  consisting  of  seven  strands.  The  object  of  this  arrangement,  instead  of 
a single  wire  of  the  same  thickness,  is  to  provide  against  the 
possibility  of  any  break  of  continuity  taking  place  in  the 
metal.  This  strand  will  stretch  twenty  per  cent,  of  its  own 
length,  and  is  covered  with  three  layers  of  the  purest  gutta 
t jpercha,  separately  applied.  The  cable  weighs  somewhat 
sinless  than  a ton  to  the  mile,  and  is  one  of  the  lightest  and 
strongest  of  its  thickness  yet  manuactured. 

A few  weeks  after  the  allied  army  entered  the  ( ’rimea 
a single  wire  cable  was  laid  across  the  Black  Sea,  a dis- 
tance of  374  miles,  between  Varna  and  Balaklava,  and  it  was  through  this  that  the  English  and  French 
governments  were  apprised  every  day  of  the  movements  of  the  belligerent  forces  on  either  side.  This 
is  the  longest  submarine  cable  which  has  yet  been  laid. 

In  the  fall  of  1857,  an  attempt  was  made  to  lay  a cable  between  Valentia  Bay,  Ireland,  and  St.  Johns, 
Newfoundland,  a distance  of  1650  miles.  The  attempt  was  unsuccessful,  the  cable  having  parted  after 
some  300  and  odd  miles  had  been  laid.  It  will  be  again  undertaken  this  year,  and  it  is  to  be  hoped 
with  better  success. 

From  the  following  engravings  it  will  be  seen  that  the  transatlantic  submarine  cable  is  somemhat  dif- 
ferently made  from  any  previously  manufactured.  The  core,  or  conductor,  is  composed  like  that  of  the 

gulf  cable,  of  seven  cop- 
per wires  wound  together 
in  the  same  manner.  The 
cable  will  be  2,500  miles 
in  length,  the  surplus 
over  the  actual  distance 
to  be  traversed  being 
considered  necessary  in 

case  of  emergency  to  make  up  for  the  inequalities  in  the  bed  of  the  ocean,  and  the  variations  that  may 
be  caused  by  the  winds  and  the  currents.  The  protecting  wires  are  made  into  strands,  each  composed  of 
seven  of  the  best  charcoal  iron  wires.  The  aggregate  length  of  the  smaller  wires  required  in  the  manu- 
facture of  one  mile  of  the  cable  is  one  hundred  and  twenty-six  miles,  and  the  whole  cable  will  require 
three  hundred  and  fifteen  thousand  miles  of  this  wire. 

The  flexibility  of  this  cable  is  so  great  that  it  can  be  made  as  manageable  as  a small  rope,  and  it  is- 
capable  of  being  tied  around  the  arm  without  injury.  Its  weight  is  but  1,800  pounds  to  the  mile,  and 
its  strength  such  that  it  will  bear  in  water  over  six  miles  of  its  own  length  if  suspended  vertically. 


3404. 


3403. 


Table  of  Submarine  Cables  already  laid  down. 


Miles. 

From  Dover  to  Calais,  . . . 21 

From  Ilowth  to  Holyhead,  . . .65 

Between  Ireland  and  Scotland,  . . 20 

From  England  to  Holland,  . . .115 

From  Dover  to  Ostend,  ...  60 

From  Balaklava  to  Varna,  Black  Sea,  . 374 
Between  Sardinia  on  the  main  land,  and 

Corsica, 60 

Total  miles  now  laid, 


Miles. 

Between  Corsica  and  the  Island,  of  Sar- 
dinia, ......  G 

Across  the  Gulf  of  St.  Lawrence,  from 

Cape  Breton  to  Newfoundland,  . 74 

Across  the  straits  of  Northumberland,  be- 
tween Cape  Tormentine  and  Prince 
Edward’s  Island,  . . .101 

805 ^ 


The  application  of  the  telegraph  to  comparative  astronomical  observations  is  a splendid  result  of  the 
iperations  of  the  American  Coast  Survey.  The  transit  of  a star  over  the  meridian  of  two  places,  con- 
nected by  telegraph,  was  notified  from  one  to  the  other  by  a touch  of  the  signal-key,  and  the  time  at  eacli 
was  observed.  The  longitude  could  be  thus  obtained,  with  some  precautions,  with  an  ease  and  accu- 
racy not  before  possible.  A second  step  was  then  taken,  by  connecting  the  chronometer,  which  was  the 
standard  of  time,  directly  with  the  telegraph.  Thus  the  seconds-wheel  was  made,  by  Dr.  Locke,  to 
raise  a little  platinum  hammer,  by  which  the  circuit  of  the  telegraph  was  broken  once  a second.  By 
another  invention,  the  pendulum  swept  through  a little  globule  of  mercury  when  at  its  centre  of  oscil- 
lation, thus  completing  the  circuit  once  a second.  The  fillet  of  paper  of  the  telegraph,  as  it  unwound 
from  its  spool,  at  the  extreme,  and  also  at  the  intermediate  stations  of  the  line,  was  thus  graduated 
accurately  into  seconds,  represented  by  a line  with  a short  break,  or  a break  with  a short  line.  A 
signal-key  was  also  included  in  the  circuit,  by  which  the  observer  could  complete  or  break  the  circuil 


702 


TELESCOPE. 


momentarily  so  as  to  mark  upon  the  same  fillet  the  transit  of  the  star  over  the  wire  of  the  telescope. 
A permanent  and  incomparably  accurate  record  was  thus  made  of  the  observation,  and  the  instant  of  its 
time.  It  is  estimated  that  the  facilities  of  astronomical  observation  are  increased  sixty-fold  by  this  in- 
vention. In  fact,  it -constitutes  an  era  in  modern  astronomy.  Though  the  work  of  the  last  one  or  twc 
years,  it  has  already  received  the  tribute  of  the  most  distinguished  foreign  observers. 

TELESCOPE.  An  optical  instrument  for  viewing  distant  objects. 

For  several  reasons  a distant  object  is  seen  less  distinctly  than  a similar  near  one.  The  angle  which 
an  object  subtends  diminishes  as  the  distance  increases  ; the  density  of  the  light  which  renders  it  visible 
also  diminishes  with  the  distance,  but  in  a much  faster  ratio;  and  a considerable  portion  of  light  is  al- 
ways lost  in  its  passage  through  the  atmosphere. 

It  is  found  by  experience  that  to  be  discernible  at  all  in  ordinary  daylight,  a detached  object  must 
subtend  at  the  eye  an  angle  of  not  less  that  30",  and  that  the  least  angle  under  which  contiguous  ob- 
jects can  be  satisfactorily  distinguished  is  about  one  minute.  By  the  aid  of  a telescope  a magnified 
image  of  the  object  is  obtained  ; and  within  certain  limits  the  object  is  not  only  apparently  enlarged, 
nut  rendered  brighter  than  it  appears  to  the  unassisted  eye. 

The  invention  of  the  telescope,  to  which  practical  astronomy  is  indebted  for  its  most  important  dis- 
coveries, has  been  ascribed  to  various  persons.  Sir  David  Brewster  ( Encyc . Brit.,  art.  “ Optics”)  says 
“ We  have  no  doubt  that  this  invaluable  instrument  was  invented  by  Roger  Bacon  or  Baptista  Porta,  in 
the  form  of  an  experiment ; though  it  had  not,  perhaps,  in  their  hands  assumed  the  maturity  of  an  in- 
strument made  for  sale,  and  applied  to  useful  purposes,  both  terrestrial  and  celestial.  If  a telescope  is 
an  instrument  by  means  of  which  things  at  a distance  can  be  seen  better  than  by  the  naked  eye,  then 
Baptista  Porta’s  concave  lens  was  a real  telescope ; but  if  we  give  the  name  to  a tube  having  a convex 
object-glass  at  one  end,  and  a convex  or  concave  lens  at  the  other,  placed  at  the  distance  of  the  sum  or 
difference  of  their  focal  lengths,  then  we  have  no  distinct  evidence  that  such  an  instrument  was  used  be- 
fore the  beginning  of  the  17th  century.”  Descartes  ascribes  the  invention  to  James  Metius,  a citizen  of 
Alkmaer  in  Holland  ; Huygens  to  John  Lippersey,  or  Zacharias  Jansen  ; Borellus  also  to  Jansen.  Pro- 
fessor Moll,  who  has  discussed  these  rival  claims,  after  examining  the  official  papers  preserved  in  the 
archives  at  the  Hague,  comes  to  the  conclusion  that  Metius  (whose  proper  name  was  Jacob  Adriaansy,) 
on  the  17th  of  October,  1608,  was  in  possession  of  the  art  of  making  telescopes,  but  that  from  some  un- 
explained reason  he  concealed  his  invention,  and  thus  gave  up  every  claim  to  the  honor  he  would  have 
derived  from  it ; that  on  the  21st  of  October  in  the  same  year,  1608,  John  or  Hans  Lippersey,  a spectacle- 
maker  of  Middleburg,  was  actually  in  possession  of  the  invention;  and  that  there  is  little  reason  to  be- 
lieve that  either  Hans  or  Zacharias  Zanz  (or  Jansen,  father  and  son)  were  inventors  of  the  telescope, 
though  one  of  them  invented  a compound  microscope  about  1590.  (, Journal  of  the  Royal  Institu- 

tion, vol.  i.) 

The  telescope  soon  made  its  way  into  other  countries.  In  April  or  May,  1609,  the  illustrious  Galileo, 
having  heard  a rumor  of  the  invention,  set  about  considering  the  means  whereby  distant  objects  could 
be  seen  distinctly,  and  was  soon  in  possession  of  a telescope  which  magnified  three  times.  In  subse- 
quent trials  he  succeeded  in  increasing  the  magnifying  power;  and  before  the  beginning  of  1610  he  had 
observed  the  satellites  of  Jupiter.  In  England,  Harriot  also,  in  1609,  began  to  use  the  telescope 
for  examining  the  disk  of  the  moon,  and  before  he  had  heard  of  the  discoveries  of  Galileo.  ( Priestley's 
History  of  Discoveries  relating  to  Vision,  Light,  and  Colors .) 

Telescopes  are  of  two  kinds,  refracting  and  reflecting  telescopes:  the  former  depending  on  the  use  of 
properly  figured  lenses,  through  which  the  rays  of  light  pass ; and  the  latter  on  the  use  of  specula,  or 
polished  metallic  mirrors,  which  reflect  the  rays ; an  inverted  image  of  the  object  being  formed  in  both 
cases  in  the  focus  of  the  lens  or  mirror. 

Refracting  telescopes  were  those  which  were  first  constructed.  They  were  of  the  most  simple  char- 
acter, consisting  merely  of  an  object-glass  of  one  lens,  and  an  eye-glass  of  one  lens,  but  of  a shorter 
focus.  But  in  this  construction  the  prismatic  colors  produced  by  the  difference  of  the  refrangibility  of 
the  luminous  rays  tinged  the  images  of  all  objects  seen  through  the  telescope,  and  the  image  was  like- 
wise distorted  by  the  aberration  of  the  extreme  rays.  It  was  soon  found  that  the  latter  defect  could 
be  sufficiently  corrected  by  employing  more  lenses  than  one  in  the  eye-piece ; but  it  was  long  before  a 
remedy  was  found  for  the  chromatic  dispersion ; and  artists,  despairing  of  success,  generally  turned 
their  attention  to  the  improvement  of  instruments  of  the  reflecting  class.  The  difficulty,  however,  was 
at  length  overcome  through  the  persevering  efforts  of  John  Dolland,  (see  Achromatism  ;)  and  the  achro- 
matic refracting  telescope  may  now  be  regarded  as  an  instrument  all  but  perfect. 

The  general  aim  in  the  construction  of  a telescope  is  to  form,  by  means  of  lenses  or  mirrors,  as  large, 
bright,  and  distinct  an  image  of  a distant  object  as  possible,  and  then  to  view  the  image  with  a magnify- 
ing glass  in  any  convenient  manner.  We  shall  first  describe  those  of  the  refracting  glass. 

Galilean  telescope. — This  is  the  most  ancient  form  of  the  telescope,  and  is  that  which  was  used  by 
Galileo.  It  consists  of  a converging  object-glass  AB,  Fig.  3402,  and  a concave  diverging  eye-glass  C D 
On  passing  through  the  object-glass  A B the  rays 

of  light  coming  from  the  different  points  of  a dis-  3402- 

tant  object  in  jjarallel  pencils  are  rendered  con-  A 

vergent,  and  proceed  towards  the  principal  focus, 
where  they  would  form  an  inverted  image ; but 
before  they  arrive  at  this  point  they  fall  upon  the 
concave  lens  C D,  by  which  they  are  again  rendered 
parallel,  or  at  least  their  convergence  is  corrected 
so  as  to  give  distinct  vision  of  the  object  to  the  eye 
at  E.  The  lens  C D is  therefore  placed  between  the  object-glass  and  the  image,  and  at  a distance  from 
the  image  equal  to  its  principal  focal  distance.  The  magnifying  power  is  equal  to  the  princiDal  focal 
distance  of  the  object-glass.  Seo  Lens. 


TELESCOPE. 


708 


In  this  telescope  the  object  is  seen  erect,  and  the  length  of  the  tube  is  only  the  difference  between 
the  focal  lengths  of  the  two  lenses.  These  properties  render  it  preferable  to  any  other  telescope  for 
many  ordinary  purposes ; as,  for  example,  an  opera-glass.  When  used  for  this  purpose  the  magnifying 
power  is  hardly  ever  greater  than  4 ; and  it  is  often  as  low  as  2. 

Astronomical  telescope. — This  is  composed  of  a converging  object-glass  A B,  Fig.  3403,  and  of  a con- 
verging eye-glass  C D.  Rays  of  light  proceeding  from  any  point  M of  a distant  object  M 1ST,  and  falling 
on  the  different  points  of  the  object-glass,  are  refracted  into  a point  m in  the  principal  focus.  In  like 
manner,  those  proceeding  from  the  point  N are 

refracted  into  the  point  n ; and  thus  an  invert-  3403. 

ed  image  rn  n is  formed  at  the  focus  of  the  ob-  c,  M 

ject-glass.  The  eye-glass  is  placed  so  that  its 
focus  shall  coincide  with  the  place  of  the  im- 
age ; consequently  rays  diverging  from  any 
point  of  the  image,  and  falling  on  the  lens 
O D,  are  refracted  into  a joarallel  direction  be- 
fore they  enter  the  eye  at  E,  and  are  thereby 
rendered  fit  to  produce  distinct  vision.  The  length  of  the  telescope  is  equal  to  the  sum  of  the  focal  dis- 
tances of  the  two  lenses;  and  the  magnifying  power  is  equal  to  the  focal  distance  of  the  object-glass 
divided  by  the  focal  distance  of  the  eye-glass.  This  telescope  was  first  described  by  Kepler  in  his 
Rioptrice,  1611  ; but  it  does  not  appear  to  have  been  executed  until  about  twenty  or  thirty  years 
later. 

Terrestrial  telescope. — This  differs  from  the  astronomical  telescope  only  in  having  two  additional 
lenses  E F,  G H,  Fig.  3404,  placed  in  the  tube  of  the  eye-glass  for  the  purpose  of  restoring  the  inverted 
image  to  its  erect  position,  and  thereby  accommodating  the  telescope  to  terrestrial  objects.  The  focal 
lengths  of  these  additional  lenses  are  usually  the  same  as  that  of  the  eye-glass.  The  two  pencils  of 
rays  proceeding  from  the  points  M and  N cross  each  other  in  the  anterior  focus  of  the  second  lens  E F, 
and  falling  parallel  on  E F form  in  its  principal  focus  an  inverted  image  of  m n,  and  consequently  an 
erect  image  of  the  object  M N.  This  image  m'  n’  is  seen  by  the  eye  at  E through  the  lens  GH,  as  the 
rays  diverging  from  m'  and  n'  in  the  focus  of  G H enter  the  eye  in  parallel  pencils.  When  the  three 
first  lenses  are  equal,  the  magnifying  power  is  the  same  as  that  of  the  astronomical  telescope,  whose 
object  and  eye  glasses  are  the  same  as  A B and  C D. 


3404 . 


The  performance  of  refracting  telescopes  depends  most  essentially  on  the  goodness  of  the  object-glass  , 
for  if  the  first  image  is  bright  and  distinct,  and  perfectly  achromatic,  there  is  little  difficulty  in  construct- 
ing eye-pieces  to  magnify  it,  without  causing  it  to  undergo  any  sensible  alteration. 

Reflecting  telescopes. — In  reflecting  telescopes  the  speculum,  or  mirror,  performs  the  same  office  that 
the  object-glass  does  in  those  of  the  refracting  kind,  and  is  therefore  called  the  object-mirror.  The  in- 
strument is  constructed  in  various  forms ; but  these  differ  from  one  another  chiefly  in  reference  to  the 
contrivances  which  have  been  adopted  for  bringing  the  focal  image  into  a convenient  situation  for  being 
viewed  by  the  eye-piece.  The  principal  forms  are  the  Newtonian,  the  Gregorian,  the  Cassegrainian,  and 
the  Herschelian. 

Newtonian  telescope. — Let  ABCD,  Fig.  3405,  represent  a section  of  the  tube  of  the  telescope  ; A B the 
object-mirror,  which  would  form  at  its  focus  the  image  a of  any  distant  object.  Now  if  a person  at- 
tempted to  view  the  image  in  its  place  at  a by  placing  himself  directly  before  the  mirror,  he  would  ne- 
cessarily intercept  the  rays  of  light  from  the  object  passing  down  the  tube  to  the  mirror,  and  conse- 
quently there  would  be  no  image  to  view.  Sir  Isaac  Newton  overcame  this  difficulty  by  introducing  a 
small  diagonal  plane  speculum  d between  A B and  a,  which  intercepting  itself  but  a small  portion  of 


light,  reflects  towards  the  side  of  the  tube  the  rays  converging  from  A B,  and  causes  the  image  which 
would  have  been  formed  at  a to  be  formed  at  b,  where  it  can  be  conveniently  viewed  by  the  eye-piece 
E attached  to  the  side  of  the  tube.  The  small  mirror  is  of  an  oval  form,  and  is  fixed  on  a slender  arm 
c connected  with  a slide,  by  means  of  which  it  may  be  made  to  approach  or  recede  from  the  large  spec- 
ulum A B,  according  as  the  image  approaches  to  or  recedes  from  it.  In  this  telescope  the  magnifying 
power  is  equal  to  the  focal  length  of  the  object-mirror  A B divided  by  that  of  the  eye-glass- 


704 


TELESCOPE. 


Gregorian  telescope. — In  this  construction  the  object-mirror  A B,  Fig.  3406,  is  perforated  in  the  mid- 
dle, and  the  rays  of  light  from  a distant  object  being  reflected  from  the  surface  of  A B cross  each  other 
in  the  focus,  where  they  form  an  inverted  image  a,  and  are  then  intercepted  by  a small  concave  mirror 
d,  which  causes  them  again  to  converge  to  a focus  at  b,  near  the  perforation  of  the  object-mirror,  where 
they  form  a reinverted  or  direct  image,  which  is  viewed  by  an  eye-piece  E screwed  into  the  tube  behind 
AB.  The  curvature  of  the  small  speculum  should  be  elliptical,  having  the  foci  at  a and  i> ; but  it  is 
generally  made  spherical,.  In  this  case  the  great  speculum  should  be  slightly  hyperbolic,  to  counteract 
the  aberration  of  the  small  mirror. 

Cassegrainian  telescope. — The  great  speculum  of  this  instrument. is  perforated  like  the  Gregorian ; but 
the  rays  converging  from  the  surface  of  the  mirror  AB,  Fig.  3407,  towards  the, focus  a,  are  intercepted 
before  they  reach  that  point  by  a small  convex  mirror  d,  not  sufficiently  convex  to  make  the  rays  diver- 
gent, but  of  such  a curvature  as  to  prevent  them  from  coming  to  a focus  till  they  are  thrown  back  to  b, 
near  the  aperture  in  A B,  where  they  form  an  inverted  image  which  is  viewed  by  the  eye-piece  E.  This 
construction  has  the  advantage  of  requiring  a shorter  tube  than  the  Gregorian ; but  the  inversion  of  the 
image  is  not  corrected,  and  for  this  reason  probably  it  has  not  been  much  used. 

In  the  two  last  constructions  the  small  mirror  d is  adjusted  by  means  of  a rod  turning  on  a shoulder 
near  the  eye  end  of  the  tube,  and  connected  by  a screw  with  the  apparatus  which  carries  the  arm  c,  to 
which  the  mirror  is  attached. 


3-107. 


3108. 

D 


Herschelian  telescope. — This  construction  differs  from  the  others  in  having  no  second  mirror.  The 
large  speculum  A B,  Fig.  3408,  is  placed  at  the  bottom  of  the  tube  in  an  inclined  position,  so  as  to  bring 
the  focal  image  a near  the  edge  of  the  tube,  where  it  is  viewed  directly  by  the  eye-piece  F without  in- 
terfering with  the  light  entering  the  telescope  from  the  object  observed.  The  magnifying  power  is  the 
same  as  in  the  Newtonian. 

The  reflecting  telescope  was  invented  by  James  Gregory,  and  is  described  by  him  in  his  Optica  Pro- 
mota,  1663  ; but  the  first  telescope  of  the  kind  was  executed  by  Newton.  P^eflecting  telescopes  have 
been  made  on  a very  large  scale.  The  celebrated  instrument  of  Sir  William  Herschel,  erected  at  Slough 
in  1789,  was  40  feet  in  length.  Its  great  speculum  had  a diameter  of  49^  inches ; its  thickness  was 
about  3-J-  inches,  and  its  weight  when  cast  was  2118  lbs.  Its  focal  length  was  40  feet,  and  it  admitted 
of  a power  of  6450  being  applied  to  it.  The  essential  advantage  of  large  telescopes  of  this  kind  consists 
in  the  immense  quantity  of  light  which  they  collect,  whereby  the  observer  is  enabled  to  perceive  faint 
nebulae  and  stars  which  are  altogether  invisible  in  ordinary  instruments. 

Reflecting  telescopes  are  used  only  for  observing  phenomena , and  are  not  like  refracting  telescopes, 
attached  to  circular  instruments  for  the  purpose  of  measuring  angles  with  greater  precision.  In  order 
to  derive  full  benefit  from  them  they  must  be  used  in  the  open  air ; and  must  either  be  mounted  equa- 
torially,  (see  Equatorial  ;)  or  else  in  such  a manner  as  to  be  capable  of  a smooth  motion  both  in  a ver- 
tical and  horizontal  direction.  Telescopes  of  this  kind  being  generally  used  with  a high  magnifying 
power,  and  consequently  having  a small  field  of  view,  are  always  accompanied  with  a smaller  telescope 
or  finder  fixed  to  the  tube,  so  that  the  axes  of  the  two  inst  ruments  are  exactly  parallel. 

Eye-pieces  of  telescopes.— When  the  image  formed  by  the  object-glass  or  mirror  is  viewed  with  a sin- 
gle lens  or  eye-glass,  whether  concave  or  convex,  it  is  only  in  the  centre  of  the  field  that  distinct  vision 
is  obtained,  all  towards  the  margin  being  hazy  and  distorted.  To  remedy  this  defect,  Boscovich  and 
Huygens  separately  proposed  the  construction  of  an  eye-piece  formed  of  two  lenses,  placed  at  a distance 
from  each  other  equal  to  half  their  focal  distances.  Boscovich  recommended  two  similar  lenses  ; Huy- 
gens, that  the  focal  length  of  the  one  should  be  twice  that  of  the  other ; and  as  this  construction  is  found 
to  answer  best  in  practice,  it  is  that  which  is  most  commonly  used. 

The  two  lenses  are  usually  plano-convex,  with  the  convex  faces  towards  the  object-glass ; the  larger 
lens,  called  the  field  glass,  is  innermost,  or  nearest  the  object-glass ; and  a diaphragm  cutting  off  the 
marginal  rays  is  usually  placed  between  them  near  the  focus  of  the  eye-lens,  where  the  image  is  formed. 
This  eye-piece  is  usually  called  the  negative  eye-piece,  from  its  having  the  image  seen  by  the  eye  be- 
hind the  field  glass  ; and  is  that  which  is  commonly  supplied  with  telescopes  intended  only  for  the  pur- 
pose of  seeing  objects  without  reference  to  measurement. 

Another  modification  of  the  two-lens  eye-piece  was  proposed  by  Ramsden,  and  is  called  the  pjositive 
eye-piece,  because  the  image  observed  is  before  both  lenses.  The  lenses  are  plano-convex,  and  nearly 
of  the  same  focal  length ; but  their  distance  from  each  other  is  less  than  the  focal  distance  of  the  lens 
nearest  the  eye,  two  lenses  thus  placed  acting  as  a compound  simple  lens.  This  eye-piece  is  the  most 
convenient  when  micrometer  wires  are  placed  in  the  focus,  because  it  can  be  taken  out  without  injuring 
the  wires  ; and  it  has  also  this  advantage,  that  the  measure  of  an  object  given  by  one  eye-piece  is  not 
altered  when  it  is  changed  for  another  of  a different  magnifying  power. 

In  both  the  eye-pieces  now  described,  the  image  is  seen  inverted  ; and  though  this  is  of  no  import 


TEMPERING  METALS,  ETC. 


705 


ance  in  astronomical  observations,  it  is  inconvenient  when  the  telescope  is  used  for  looking  at  terrestrial 
objects.  By  placing  an  additional  pair  of  lenses  in  the  tube  of  the  eye-piece,  the  image  is  repeated  and 
reinverted,  and,  consequently,  seen  erect.  By  this  means,  as  explained  above,  the  terrestrial  telescope 
is  obtained. 

The  name  of  diagonal  eye-piece  has  been  given  to  eye-pieces  furnished  with  a diagonal  reflecting  mir- 
ror, tlie  object  of  which  is  to  give  a more  convenient  direction  to  the  rays  emerging  from  tire  eye-piece 
when  the  telescope  is  pointed  high. 

Telescopes  are  generally  supplied  with  eye-pieces  of  different  powers,  which  are  all  fitted  to  enter  the 
same  tube ; and  the  focal  adjustment  is  commonly  effected  by  a rack  and  pinion  motion  acting  on  the 
tube  which  carries  the  eye-piece. 

TEMPERING,  HARDENING,  AND  SOFTENING  METALS  used  in  the  mechanical  and  useful 
arts. — When  the  malleable  metals  are  hammered,  or  rolled,  they  generally  increase  in  hardness,  in 
elasticity^,  and  in  density  or  specific  gravity,  which  effects  are  produced  simply  from  the  closer  approxi- 
mation of  their  particles ; and  in  this  respect  steel  may  be  perhaps  considered  to  excel,  as  the  process 
called  hammer-hardening,  which  simply  means  hammering  without  heat,  is  frequently  employed  as  the 
sole  means  of  hardening  some  kinds  of  steel  springs,  and  for  which  it  answers  remarkably  welL 

After  a certain  degree  of  compression,  the  malleable  metals  assume  their  closest  and  most  condensed 
states ; and  it  then  becomes  necessary  to  discontinue  the  compression  or  elongation,  as  it  would  cause 
the  disunion  or  cracking  of  the  sheet  or  wire,  or  else  the  metal  must  be  softened  by  the  process  of  an- 
nealing. 

The  metals,  lead,  tin,  and  zinc,  are  by  some  considered  to  be  perceptibly  softened  by  immersion  in 
boiling  water ; but  such  of  the  metals  as  will  bear  it  are  generally  heated  to  redness,  the  cohesion  of 
the  mass  is  for  the  time  reduced,  and  the  metal  becomes  as  soft  as  at  first,  and  the  working  and  an- 
nealing may  be  thus  alternately  pursued,  until  the  sheet  metal,  or  the  wire,  reaches  its  limit  of  tenuity. 

The  generality  of  the  metals  and  alloys  suffer  no  very  observable  change,  whether  or  not  they  are 
suddenly  quenched  in  water  from  the  red-heat.  Pure  hammered  iron,  like  the  rest,  appears  after  an- 
nealing to  be  equally  soft,  whether  suddenly  or  slowly  cooled ; some  of  the  impure  kinds  of  malleable 
iron  harden  by  immersion,  but  only  to  an  extent  that  is  rather  hurtful  than  useful,  and  which  may  be 
considered  as  an  accidental  quality. 

Steel  however  receives  by  sudden  cooling  that  extreme  degree  of  hardness  combined  with  tenacity, 
which  places  it  so  incalculably  beyond  every  other  material  for  the  manufacture  of  cutting  tools  ; espe- 
cially as  it  likewise  admits  of  a regular  gradation  from  extreme  hardness  to  its  softest  state,  when  sub- 
sequently reheated  or  tempered.  Steel  therefore  assumes  a place  in  the  economy  of  manufactures 
Unapproachable  by  any  other  material ; consequently  we  may  safely  say  that  without  it,  it  would  be 
impossible  to  produce  nearly  all  our  finished  works  in  metal  and  other  hard  substances  ; for  although 
some  of  the  metallic  alloys  are  remarkable  for  hardness,  and  were  used  for  various  implements  of  peace- 
ful industry,  and  also  those  of  war,  before  the  invention  of  steel,  yet  in  point  of  absolute  aDd  enduring 
hardness,  and  equally  so  in  respect  to  elasticity  and  tenacity,  they  fall  exceedingly  short  of  hardened 
steel. 

Hammer-hardening  renders  the  steel  more  fibrous  and  less  crystalline,  and  reduces  it -in  bulk;  on  the 
other  hand,  fire-hardening  makes  steel  more  crystalline,  and  frequently  of  greater  bulk ; but  the  elastic 
nature  of  hammer-hardened  steel  will  not  take  so  wide  nor  so  efficient  a range  as  that  which  is  fire- 
hardened. 

If  we  attempt  to  seek  the  remarkable  difference  between  pure  iron  and  steel  in  their  chemical  analy- 
ses, it  appears  to  result  from  a minute  portion  of  carbon ; and  cast-iron,  which  possesses  a much  larger 
share,  presents,  as  we  should  expect,  somewhat  similar  phenomena. 

Iron  semi-steelified  contains  one  150th  of  carbon. 


Soft  cast-steel  capable  of  welding “ 120th 

Cast-steel  for  common  purposes “ 100th 

Cast-steel  requiring  more  hardness  “ 90th 

Steel  capable  of  standing  a few  blows,  but  quite  unfit  for  drawing  “ 50th 

First  approach  to  a steely  granulated  fracture “ 30th  to  40th 

White  cast-iron “ 25th 

Mottled  cast-iron  “ 20th 

Carbonated  cast-iron  “ 15th 

Super-carbonated  crude  iron , “ 12th 


Moreover,  as  the  hard  and  soft  conditions  of  steel  may  be  reversed  backwards  and  forwards  without 
any  rapid  chemical  change  in  its  substance,  it  has  been  pronounced  to  result  from  internal  arrangement 
or  crystallization,  which  may  be  in  a degree,  illustrated  and  explained  by  similar  changes  observed 
in  glass. 

A wine-glass,  or  other  object  recently  blown,  and  plunged  whilst  red-hot  into  cold  water,  cracks  in  a 
thousand  places,  and  even  cooled  in  warm  air  it  is  very  brittle,  and  will  scarcely  endure  the  slightest 
violence  or  sudden  change  of  temperature  ; and  visitors  to  the  glass-house  are  often  shown  that  a wine- 
glass or  other  article  of  irregular  form,  breaks  in  cooling  in  the  open  air  from  its  unequal  contraction  at 
different  parts.  But  the  objects  would  have  become  useful,  and  less  disposed  to  fracture,  if  they  had 
been  allowed  to  arrange  their  particles  gradually,  during  their  very  slow  passage  through  the  long  an- 
nealing oven  or  leer  of  the  glass-house,  the  end  at  which  they  enter  being  at  the  red-heat,  and  the  op- 
posite extremity  almost  cold 

To  perfect  the  annealing,  it  is  not  unusual  with  lamp-glasses,  tubes  for  steam-gages,  and  similar 
pieces  exposed  to  sudden  transitions  of  heat  and  cold,  to  place  them  in  a vessel  of  cold  water,  which  is 
slowly  raised  to  the  boiling  temperature,  kept  for  some  hours  at  that  heat,  and  then  allowed  to  cool 
very  slowly : the  effect  thus  produced  is  far  from  chimerical.  For  such  pieces  of  flint-glass  intended 
Von.  II.— 45 


TEMPERING  METALS,  ETC. 


700 


for  cutting  as  are  found  to  be  insufficiently  annealed,  the  boiling  is  sometimes  preferred  to  a spcond 
passage  through  the  leer : lamp-glasses  are  also  much  less  exposed  to  fracture  when  they  have  been 
once  used,  as  the  heat  if  not  too  suddenly  applied  or  checked,  completes  the  annealing. 

Steel  in  like  manner  when  suddenly  cooled  is  disposed  to  crack  in  pieces,  which  is  a constant  source 
ol  anxiety ; the  danger  increases  with  the  thickness  in  the  same  way  as  with  glass,  and  the  more  espe- 
cially when  the  works  are  unequally  thick  and  thin. 

Another  ground  of  analogy  between  glass  and  steel,  appears  to  exist  in  the  pieces  of  unannealed 
glass  used  for  exhibiting  the  phenomena,  formerly  called  double  refraction,  but  now  polarization  of 
light;  an  effect  distinctly  traced  to  its  peculiar  crystalline  structure. 

In  glass  it  is  supposed  to  arise  from  the  cooling  of  the  external  crust  more  rapidly  than  the  internal 
mass ; the  outer  crust  is  therefore  in  a state  of  tension,  or  restraint,  from  an  attempt  to  squeeze  the 
inner  mass  into  a smaller  space  than  it  seems  to  require ; and  from  the  hasty  arrangement  of  the  unan- 
nealed glass,  the  natural  positions  of  its  crystals  are  in  a measure  disturbed  or  dislocated. 

It  has  been  shown  experimentally,  that  a rearrangement  of  the  particles  of  glass  occurs  in  the  pro- 
cess of  annealing,  as  of  two  pieces  of  the  same  tube  each  40  inches  long,  the  one  sent  through  the  leer, 
contracted  one-sixteenth  of  an  inch  more  than  the  other,  which  was  cooled  as  usual  in  the  open  air. 
'lubes  for  philosophical  purposes  are  not  annealed,  as  their  inner  surfaces  are  apt  to  become  soiled  with 
the  sulphur  of  the  fuel ; they  are  in  consequence  very  brittle  and  liable  to  accident. 

In  the  philosophical  toy,  the  Prince  Rupert’s  drop,  this  disruption  is  curiously  evident  to  the  sight,  as 
the  inner  substance  is  cracked  and  divided  into  a multitude  of  detached  parts,  held  together  by  the 
smooth  external  coat.  The  unannealed  glass,  when  cautiously  heated  and  slowly  cooled,  ceases  to 
present  the  polarizing  effect,  and  the  steel  similarly  treated  ceases  to  be  hard,  and  may  we  not  there- 
fore indulge  in  the  speculation,  that  in  both  cases  a peculiar  crystalline  structure  is  consequent  upon 
the  unannealed  or  hardened  state  ? 

In  the  process  of  hardening  steel,  water  is  by  no  means  essential,  as  the  sole  object  is  to  extract  its 
heat  rapidly  ; and  the  following  are  examples,  commencing  with  the  condition  of  extreme  hardness,  and 
ending  with  the  reverse  condition. 

A thin  heated  blade  placed  between  the  cold  hammer  and  anvil,  or  other  good  conductors  of  heat, 
becomes  perfectly  hard.  Thicker  pieces  of  steel,  cooled  by  exposure  to  the  air  upon  the  anvil,  become 
rather  hard,  but  readily  admit  of  being  filed.  They  become  softer  when  placed  on  the  cold  cinders,  or 
other  bad  conductors  of  heat.  Still  more  soft  when  placed  in  hot  cinders,  or  within  the  fire  itself,  and 
cooled  by  their  gradual  extinction.  When  the  steel  is  incased  in  close  boxes  with  charcoal  powder,  and 
it  is  raised  to  a red-heat  and  allowed  to  cool  in  the  fire  or  furnace,  it  assumes  its  softest  state ; unless 
lastly,  we  proceed  to  its  partial  decomposition.  This  is  done  by  inclosing  the  steel  with  iron  turnings 
or  filings,  the  scales  from  the  smith’s  anvil,  lime,  or  other  matters  that  will  abstract  the  carbon  from  its 
surface ; by  this  mode  it  is  superficially  decarbonized,  or  reduced  to  the  condition  of  pure  soft  iron,  in 
the  manner  practised  by  Mr.  Jacob  Perkins,  in  his  most  ingenious  and  effective  combination  of  pro- 
cesses, employed  for  producing,  in  unlimited  numbers,  absolutely  identical  impressions  of  bank  notes 
and  checks,  for  the  prevention  of  forgery. 

A nearly  similar  variety  of  conditions  might  be  referred  to  as  existing  in  cast-iron  in  its  ordinary 
state,  governed  by  the  magnitude,  quality,  and  management  of  the  castings ; independently  of  which, 
by  one  particular  method,  some  cast-iron  may  be  rendered  externally  as  hard  as  the  hardest  steel: 
such  are  called  chilled-iron  castings ; and,  as  the  opposite  extreme,  by  a method  of  annealing  combined 
with  partial  decomposition,  malleable-iron  castings  may  be  obtained,  so  that  cast-iron  nails  may  be 
clenched. 

Again,  the  purest  iron,  and  most  varieties  of  cast-iron,  may,  by  another  proceeding,  be  superficially 
converted  into  steel,  and  then  hardened,  the  operation  being  appropriately  named  case-hardening. 

It  may  perhaps  be  truly  said,  that  upon  no  one  subject  connected  with  mechanical  art  does  there 
exist  such  a contrariety  of  opinion,  not  unmixed  with  prejudice,  as  upon  that  of  hardening  and  temper- 
ing steel ; which  makes  it  often  difficult  to  reconcile  the  practices  followed  by  different  individuals  in 
order  to  arrive  at  exactly  similar  ends.  The  real  difficulty  of  the  subject  occurs  in  part  from  the  mys- 
teriousness of  the  change ; and  from  the  absence  of  defined  measures,  by  which  either  the  steps  of  the 
pirocess  itself,  or  the  value  of  the  results  when  obtained,  may  be  satisfactorily  measured ; as  each  is  de- 
termined almost  alone  by  the  unassisted  senses  of  sight  and  touch,  instead  of  by  those  physical  means 
by  which  numerous  other  matters  may  be  strictly  tested  and  measured,  nearly  without  reference  to  the 
judgment  of  the  individual,  yhieh  in  its  very  nature  is  less  to  be  relied  upon. 

The  excellence  of  cutting-tools,  for  instance,  is  pronounced  upon  their  relative  degrees  of  endurance, 
but  many  accidental  circumstances  here  interfere  to  vitiate  the  strict  comparison : and  in  respect  to  the 
measure  of  simple  hardness,  nearly  the  only  test  is  the  resistance  the  objects  offer  to  the  file,  a mode  in 
two  ways  defective,  as  the  files  differ  among  themselves  in  hardness ; and  they  only  serve  to  indicate 
in  an  imperfect  manner  to  the  touch  of  the  individual,  a general  notion  without  any  distinct  measure, 
so  that  when  the  opinion  of  half  a dozen  persons  may  be  taken,  upon  as  many  pieces  of  steel  differing 
hut  slightly  in  hardness,  the  want  of  uniformity  in  their  decisions  will  show  the  vague  nature  of  the  proof 

Under  these  circumstances,  instead  of  recommending  any  particular  methods,  we  have  determined  to 
advance  a variety  of  practical  examples  derived  from  various  sources,  which  will  serve  in  most  cases  to 
confirm,  but  in  some  to  confute  one  another ; leaving  to  every  individual  to  follow  those  examples  which 
may  be  the  most  nearly  parallel  with  his  own  wants.  There  are,  however,  some  few  points  upon  which 
it  may  be  said  that  all  are  agreed ; namely, 

The  temperature  suitable  to  forging  and  hardening  steel  differs  in  some  degree  with  its  quality  and 
its  mode  of  manufacture  ■ the  heat  that  is  required  diminishes  with  the  increase  of  carbon  : 

In  every  case  the  loxeest  available  temperature  should  be  employed  in  each  process,  the  hammering 
should  be  applied  in  the  most  equal  manner  throughout,  and  for  cutting  tools  it  should  be  continued 
mtil  they  ar  - nearly  cold  : 


TEMPERING  METALS,  ETC. 


TOT 


Coke  or  charcoal  is  much  better  as  a fuel  than  fresh  coal,  the  sulphur  of  which  is  highly  injurious  : 

The  scale  should  be  removed  from  the  face  of  the  work  to  expose  it  the  more  uniformly  to  the  effect 
of  the  cooling  medium  : 

Hardening  a second  time  without  the  intervention  of  hammering  is  attended  with  increased  risk;  and 
the  less  frequently  steel  passes  through  the  fire  the  better. 

In  hardening  and  tempering  steel  there  are  three  things  to  be  considered ; namely,  the  means  of 
heating  the  objects  to  redness,  the  means  of  cooling  the  same,  and  the  means  of  applying  the  heat  for 
tempering  or  letting  them  down.  I will  speak  of  these  separately,  before  giving  examples  of  their 
application. 

The  smallest  works  are  heated  with  the  flame  of  the  blowpipe  and  are  occasionally  supported  upon 
charcoal.  (See  Soldering.) 

For  objects  that  are  too  large  to  be  heated  by  the  blowpipe,  and  too  small  to  be  conveniently  warmed 
in  the  naked  fire,  various  protective  means  are  employed.  Thus  an  iron  tube  or  sheet-iron  box  inserted 
in  the  midst  of  the  ignited  fuel  is  a safe  and  cleanly  way ; it  resembles  the  muffle  employed  in  chemi- 
cal works.  The  work  is  then  managed  with  long  forceps  made  of  steel  or  iron  wire,  bent  in  the  form 
of  the  letter  U,  and  flattened  or  hollowed  at  the  ends.  A crucible  or  an  iron  pot  about  four  to  six 
inches  deejy  filled  with  lead  and  heated  to  redness,  is  likewise  excellent,  but  more  particularly  for  long 
and  thin  tools,  such  as  gravers  for  artists,  and  other  slight  instruments ; several  of  these  may  be  inserted 
at  once,  although  towards  the  last  they  should  be  moved  about  to  equalize  the  heat ; the  weight  of  the 
lead  make9  it  desirable  to  use  a bridle  or  trevet  for  the  support  of  the  crucible.  Some  workmen  place 
on  the  fire  a pan  of  charcoal  dust,  and  heat  it  to  redness. 

Great  numbers  of  tools,  both  of  medium  and  large  size,  are  heated  in  the  ordinary  forge  fire,  which 
should  consist  of  cinders  rather  than  fresh  coals  : coke  and  also  charcoal  are  used,  but  far  less  generally  ; 
recourse  is  also  had  to  hollow  fires  ; but  the  bellows  should  be  very  sparingly  used,  except  in  blowing 
up  the  fire  before  the  introduction  of  the  work,  which  should  be  allowed  ample  time  to  get  hot,  or,  as  it  is 
called,  to  “ soak.” 

It  is  a common  and  excellent  practice  among  some  workmen  to  use  coke  both  in  forging  and  harden- 
ing steel  goods.  They  frequently  prepare  it  for  themselves,  either  upon  the  forge-hearth  or  in  a heap 
in  the  open  yard. 

Which  method  soever  may  be  resorted  to  for  heating  the  work,  the  greatest  care  should  be  given  to 
communicate  to  all  the  parts  requiring  to  be  hardened  a uniform  temperature,  and  which  is  only  to  be 
arrived  at  by  cautiously  moving  the  work  to  and  fro  to  expose  all  parts  alike  to  the  fire ; the  difficulty 
of  accomplishing  this  of  course  increases  with  long  objects,  for  which  fires  of  proportionate  length  are 
required. 

It  is  far  better  to  err  on  the  side  of  deficiency  than  of  excess  of  heat ; the  point  is  rather  critical,  and 
not  alike  in  all  varieties  of  steel.  Until  the  quality  of  the  steel  is  familiarly  known,  it  is  a safe  precau- 
tion to  commence  rather  too  low  than  otherwise,  as  then  the  extent  of  the  mischief  will  be  the  neces- 
sity for  a repetition  of  the  process  at  a higher  degree  of  heat ; but  the  steel  if  burned  or  overheated 
will  be  covered  with  scales,  and  what  is  far  worse,  its  quality  will  be  permanently  iujured ; a good 
hammering  will,  in  a degree,  restore  it ; but  this  in  finished  works  is  generally  impracticable. 

It  is  argued  by  some,  that  by  heating  pieces  of  steel  to  different  degrees,  before  plunging  them  into 
the  water,  the  one  piece  attains  full  hardness,  the  next  the  temper  of  a tool  fit  for  metal,  another  of  a 
tool  fit  for  wood,  a fourth  that  of  a spring,  and  so  on;  That  this  view  is  not  altogether  without  founda- 
tion, appears  in  the  fact  that  if  the  end  of  a piece  of  steel  be  made  entirely  hard,  the  transition  is  not 
quite  immediate  from  the  hard  to  the  soft  part;  in  making  points,  such  as  are  used  in  a dividing-engine, 
it  is  customary  to  harden  the  end  of  a longer  piece  of  steel  than  is  required,  and  form  the  point  upon 
the  grindstone,  exactly  at  that  part  where  the  temper  suits,  without  the  steel  being  let  down  at  all.  In 
hardening  by  this  method,  however,  without  tempering,  the  scale  of  proper  hardness  is  confined  within 
such  extremely  narrow  limits,  as  to  be  nearly  useless ; thus,  it  frequently  happens  that  in  a number  of 
tools  heated  as  nearly  alike  as  the  workman  could  judge,  some  few  will  be  found  too  soft  for  any  use, 
although  they  were  all  intended  to  receive  the  ordinary  hardness,  so  as  to  require  letting  down,  as  usual 
with  those  tools  exposed  to  violent  strains  or  blows,  such  as  screw-taps,  cold  chisels,  and  hatchets, 
although  many  tools  for  metal,  used  with  quiet  and  uniform  pressure,  are  left  of  the  full  hardness  for 
'greater  durability. 

With  the  excess  of  heat,  beyond  tlie  lowest  that  vr.ll  suffice,  the  brittleness  rather  than  the  useful  hard- 
ness of  tools  is  increased ; and  when  no  excess  of  heat  is  employed  beyond  that  absolutely  requisite  for 
hardening  in  the  usual  manner,  the  steel  does  not  appear  to  be  injured,  and  the  colors  on  its  brightened 
surface  that  occur  in  tempering  are  an  excellent,  and  in  general,  sufficiently  trustworthy  index  of  the 
inferior  degrees  of  hardness  proper  for  various  uses. 

Less  than  a certain  heat  fails  to  produce  hardness,  and  in  the  opinion  of  some  workmen  has  quite  the 
opposite  effect,  and  they  consequently  resort  to  it  as  the  means  of  rapid  annealing,  not,  however,  by 
plunging  the  steel  into  the  water  and  allowing  it  to  remain  until  cold,  but  dipping  it  quickly,  holding 
it  in  the  steam  for  a few  moments,  dipping  it  again,  and  so  on,  reducing  it  to  the  cold  state  in  a hasty 
but  intermittent  manner. 

There  is  another  opinion  prevalent  among  workmen,  that  steel  which  is  “pinny”  or  as  if  composed 
of  a bundle  of  hard  wires,  is  rendered  uniform  in  its  substance  if  it  is  first  hardened  and  then  an- 
nealed. 

Secondly,  the  choice  of  the  cooling  medium  has  reference  mainly  to  the  relative  powers  of  conducting 
heat  they  severally  possess:  the  following  have  been  at  different  times  resorted  to  with  various  degrees 
of  success:  currents  of  cold  air;  immersion  in  water  in  various  states,  in  oil  or  wax,  and  in  freezing 
mixtures ; mercury,  and  flat  metallic  surfaces  have  been  also  used.  Mr.  Perkins  recommended,  as  the 
result  of  his  experiments,  plain  water  at  a temperature  of  40°  Fahrenheit.  On  the  whole,  however, 
there  appears  to  be  an  opinion  that  mercury  gives  the  greatest  degree  of  hardness;  then  cold  salt  ano 


708 


TEMPERING  METALS,  ETC. 


water,  or  water  mixed  with  various  ‘"astringent  and  acidifying  matters;”  plain  water  follows;  and 
lastly,  oily  mixtures. 

I find  but  one  person  who  has  commonly  used  the  mercury ; many  presume  upon  the  good  conduct- 
ing power  of  the  metal,  and  the  nonformation  of  steam,  which  causes  a separation  betwixt  the  steel  and 
water  when  the  latter  is  employed  as  the  cooling  medium.  I have  failed  to  learn  the  reason  of  the  ad- 
vantage of  salt  and  water,  unless  the  fluid  have,  as  well  as  a greater  density,  a superior  conducting 
power.  The  file-makers  medicate  the  water  in  other  ways,  but  this  is  one  of  the  questionable  myste- 
ries which  is  never  divulged  ; although  it  is  supposed  that  a small  quantity  of  white  arsenic  is  gener- 
ally added  to  water  saturated  with  salt.  One  thing  however  may  be  noticed,  that  articles  hardened  in 
salt  and  water  are  apt  to  rust,  unless  they  are  laid  for  a time  in  lime-water,  or  some  neutralizing  agent. 

With  plain  water  an  opinion  very  largely  exists  in  favor  of  that  which  has  been  used  over  and  over 
again  even  for  years,  provided  it  is  not  greasy : and  when  the  steel  is  very  harsh,  the  chill  is  taken  off 
plain  water  to  lessen  the  risk  of  cracking  it ; oily  mixtures  impart  to  thin  articles,  such  as  springs,  a 
sufficient  and  milder  degree  of  hardness,  with  less  danger  of  cracking,  than  from  water ; and  in  some 
cases  a medium  course  is  pursued  by  covering  the  water  with  a thick  film  of  oil,  which  is  said  to  be 
adopted  occasionally  with  scythes,  reaping-hooks,  and  thin  edge-tools. 

From  experiments  upon  all  these  means,  we  are  induced  fully  to  acquiesce  in  Mr.  Perkins’  recom- 
mendation of  plain  cold  water  for  general  purposes ; except  in  the  case  of  thin  elastic  works,  for  which 
oil,  or  oily  compositions  are  certainly  more  proper. 

A so-called  natural  spring  is  made  by  a vessel  with  a true  and  a false  bottom,  the  latter  perforated 
with  small  holes ; it  is  filled  with  water,  and  a copious  supply  is  admitted  beneath  the  partition ; it 
ascends  through  the  holes,  and  pursues  the  same  current  as  the  heated  portions,  which  also  escape  at 
the  top.  This  was  invented  by  the  late  Jacob  Perkins,  and  was  used  by  him  in  hardening  the  rollers 
for  transferring  the  impressions  to  the  steel-plates  for  bank  notes. 

Sometimes  when  neighboring  parts  of  works  are  required  to  be  respectively  hard  and  soft,  metal 
tubes  or  collars- are  fitted  tight  upon  the  work,  to  protect  the  parts  to  be  kejrt  soft  from  the  direct  ac- 
tion of  the  water,  at  any  rate  for  so  long  a period  as  they  retain  the  temperature  suitable  to  hardening. 

The  process  of  hardening  is  generally  one  of  anxiety,  as  the  sudden  transition  from  heat  to  cold  often 
causes  the  works  to  become  greatly  distorted  if  not  cracked.  The  last  accident  is  much  the  most  likely 
to  occur  with  thick  massive  pieces,  which  are  as  it  were  hardened  in  layers,  as  although  the  external 
crust  or  shell  may  be  perfectly  hard,  there  is  almost  a certainty  that  towards  the  centre  the  parts  are 
gradually  less  hard ; and  when  broken  the  inner  portions  will  sometimes  admit  of  being  readily  filed. 

When  in  the  fire  the  steel  becomes  altogether  expanded,  and  in  the  water  its  outer  crust  is  suddenly 
arrested,  but  with  a tendency  to  contract  from  the  loss  of  heat,  which  cannot  so  rapidly  occur  at  the 
central  part ; it  may  be  therefore  presumed  that  the  inner  bulk  continues  to  contract  after  the  outer 
crust  is  fixed,  and  which  tends  to  tear  the  two  asunder,  the  more  especially  if  there  be  any  defective 
part  in  the  steel  itself.  An  external  flake  of  greater  or  less  extent  not  unfrequently  shells  off  in  har- 
dening; and  it  often  happens  that  works  remain  unbroken  for  hours  after  removed  from  the  water,  but 
eventually  give  wTay  and  crack  with  a loud  report,  from  the  rigid  unequal  tension  produced  by  the  vio- 
lence of  the  process  of  hardening. 

The  contiguity  of  thick  and  thin  parts  is  also  highly  dangerous,  as  they  can  neither  receive,  nor  yield 
up  heat,  in  the  same  times ; the  mischief  is  sometimes  lessened  by  binding  pieces  of  metal  around  the 
thin  parts  with  wire,  to  save  them  from  the  action  of  the  cooling  medium.  Sharp  angular  notches  are 
also  fertile  sources  of  mischief,  and,  where  practicable,  they  should  be  rejected  in  favor  of  curved  lines. 

As  regards  both  cracks  and  distortions,  it  may  perhaps  be  generally  said,  that  their  avoidance  de- 
pends principally  upon  manipulation , or  the  successful  management  of  every  step : first  the  original 
manufacture  of  the  steel,  its  being  forged  and  wrought,  so  that  it  may  be  equally  condensed  on  all 
sides  with  the  hammer,  otherwise  when  the  cohesion  of  the  mass  is  lessened  from  its  becoming  red-hot, 
it  recovers  in  part  from  any  unequal  state  of  density  in  which  it  may  have  been  placed. 

While  red-hot,  it  is  also  in  its  weakest  condition ; it  is  therefore  prone  to  injury  either  from  incautious 
handling  with  the  tongs,  or  from  meeting  the  sudden  cooling  action  irregularly,  and  therefore  it  is  gen- 
erally best  to  plunge  works  vertically,  as  all  parts  are  then  exposed  to  equal  circumstances,  and  less 
disturbance  is  risked  than  when  the  objects  are  immersed  obliquely  or  sideways  into  the  water ; al- 
though for  swords,  and  objects  of  similar  form,  it  is  found  the  best  to  dip  them  exactly  as  in  making  a 
vertical  downward  cut  with  a sabre,  which  for  this  weapon  is  its  strongest  direction. 

Occasionally  objects  are  clamped  between  stubborn  pieces  of  metal,  as  soft  iron  or  copper,  during 
their  passage  through  the  fire  and  water.  Such  plans  can  be  seldom  adopted  and  are  rarely  followed, 
the  success  of  the  process  being  mostly  allowed  to  depend  exclusively  upon  good  general  management. 

In  recent  experiments  in  making  the  magnets  for  dipping-needles,  which  are  about  ten  inches  long, 
one-fourth  of  an  inch  wide,  and  the  two-hundredth  part  of  an  inch  thick,  this  precaution  entirely  failed ; 
and  the  needles  assumed  all  sorts  of  distortions  when  released  from  between  the  stiff  bars  within  which 
they  were  hardened.  The  plan  was  eventually  abandoned,  and  the  magnets  were  heated  in  the  ordi- 
nary way  within  an  iron  tube,  and  were  set  straight  with  the  hammer  after  being  let  down  to  a deep 
orange  or  brown  color.  Steel  however  is  in  the  best  condition  for  the  formation  of  good  permanent 
magnets  when  perfectly  hard. 

In  all  cases  the  thick  unequal  scale  left  from  the  forge  should  be  ground  off  before  hardening,  in 
order  to  expose  a clean  metallic  surface,  otherwise  the  cooling  medium  cannot  produce  its  due  and 
equal  effect  throughout  the  instrument.  The  edges  also  should  be  left  thick,  that  they  may  not  be 
burned  in  the  fire ; thus  it  will  frequent.lv  happen  that  the  extreme  end  or  edge  of  a tool  is  inferior  in 
quality  to  the  part  within,  and  that  the  instrument  is  much  better  after  it  has  been  a few  times 
ground : 

“ He  that,  -will  a good  Edge  win 
Must  Forge  thick  and  Grind  thin.” 


TEMPERING  METALS,  ETC. 


70', 


Thirdly,  the  heat  for  tempering  or  letting  down.  Between  the  extreme  conditions  of  hard  and  soft 
steel  there  are  many  intermediate  grades,  the  common  index  for  which  is  the  oxidation  of  the  brightened 
surface,  and  it  is  quite  sufficient  for  practice.  These  tints,  and  their  respective  approximate  tempera- 
tures, are  thus  tabulated : 


1.  Very  pale  straw  yellow 

2.  A shade  of  darker  yellow  

3.  Darker  straw  yellow 

4.  Still  darker  straw  yellow 

5.  A brown  yellow  

6.  A yellow,  tinged  slightly  with  purple. 

7.  Light  purple 

8.  Dark  purple 

9.  Dark  blue 

10.  Paler  blue 

11.  Still  paler  blue 

12.  Still  paler  blue,  with  a tinge  of  green 


410  | Tools  for  metal. 

470  ) Tools  for  wood,  and  screw-taps, 
490  \ &c. 

500  i Hatchets,  chipping-chisels,  and 
520  >•  other  percussive  tools,  saws, 
530  ) &c. 

550  / c • 

-,_A  1 Springs. 
o,0  J 1 ° 

590  1 

610  > Too  soft  for  the  above  purposes. 
630  ) 


The  first  tint  arrives  at  about  430°  F.,  but  it  is  only  seen  by  comparison  with  a piece  of  steel  not 
heated  : the  tempering  colors  differ  slightly  with  the  various  qualities  of  steel. 

The  knife-edges,  for  Cajotain  Eater’s  experimental  pendulum,  were  very  carefully  hardened  and  tem- 
pered in  a bath  heated  to  430°  ; being  then  found  too  soft  they  were  rehardened,  and  tempered,  at  only 
the  heat  of  boiling  water,  after  which  they  were  considered  admirably  suited  to  their  purpose. 

The  heat  for  tempering  being  moderate,  it  is  often  supplied  by  the  part  of  the  tool  not  requiring  to 
be  hardened,  and  which  is  not  therefore  cooled  in  the  water.  The  workman  first  hastily  tries  with  a 
file  whether  the  work  is  hard,  he  then  partially  brightens  it  at  a few  parts  with  a piece  of  grindstone 
or  an  emery  stick,  that  he  may  be  enabled  to  watch  for  the  required  color ; which  attained,  the  work 
is  usually  cooled  in  any  convenient  manner,  lest  the  body  of  the  tool  should  continue  to  supply  heat. 
But  when,  on  the  contrary,  the  color  does  not  otherwise  appear,  partial  recurrence  is  had  to  the  mode 
in  which  the  work  was  heated,  as  the  flame  of  the  candle,  or  the  surface  of  the  clear  fire  applied,  if 
possible,  a little  below  the  part  where  the  color  is  to  be  observed,  that  it  may  not  be  soiled  by  the 
smoke. 

A very  convenient  and  general  manner  of  tempering  small  objects,  is  to  heat  to  redness  a few  inches 
of  the  end  of  a flat  bar  of  iron  about  two  feet  long;  it  is  laid  across  the  anvil,  or  fixed  by  its  cold  ex- 
tremity in  the  vice ; and  the  work  is  placed  on  that  part  of  its  surface  which  is  found  by  trial  to  be  of 
the  suitable  temperature,  by  gradually  sliding  the  work  towards  the  heated  extremity.  In  this  manner 
many  tools  may  be  tempered  at  once,  those  at  the  hot  part  being  pushed  off  into  a vessel  of  water  or 
oil,  as  they  severally  show  the  required  color,  but  it  requires  dexterity  and  quickness  in  thus  managing 
many  pieces. 

Vessels  containing  oil  or  fusible  alloys  carefully  heated  to  the  required  temperatures  have  also  been 
used,  and  I shall  have  to  describe  a method  called  “ blazing  off’"  resorted  to  for  many  articles,  such  as 
springs  and  saws,  by  heating  them  over  the  naked  fire  until  the  oil,  wax,  or  composition  in  wdiich  they 
have  been  hardened  ignites ; this  can  only  occur  wheu  they  respectively  reach  their  boiling  tempera- 
tures and  are  evaporated  in  the  gaseous  form. 

The  period  of  letting  down  the  works  is  also  commonly  chosen  for  correcting,  by  means  of  the  ham- 
mer, those  distortions  which  so  commonly  occur  in  hardening ; this  is  done  upon  the  anvil,  either  with 
the  thin  pane  of  an  ordinary  hammer,  or  else  with  a hack-hammer,  a tool  terminating  at  each  end  in  an 
obtuse  chisel-edge,  which  requires  continual  repair  on  the  grindstone. 

The  blows  are  given  on  the  hollow  side  of  the  work,  and  at  right  angles  to  the  length  of  the  curve ; 
they  elongate  the  concave  side,  and  gradually  restore  it  to  a plane  surface,  when  the  blows  are  dis- 
tributed consistently  with  the  positions  of  the  erroneous  parts.  The  hack-hammer  unavoidably  injures 
the  surface  of  the  work,  but  the  blows  should  not  be  violent,  as  they  are  then  also  more  prone  to  break 
the  work,  the  liability  to  which  is  materially  lessened  when  it  is  kept  at  or  near  the  tempering  heat, 
and  the  edge  of  the  hack-hammer  is  slightly  rounded. 

Watchmakers’  drills  of  the  smallest  kinds,  are  heated  in  the  blue  part  of  the  flame  of  the  candle; 
larger  drills  are  heated  with  the  blowpipe  flame,  applied  very  obliquely,  and  a little  below  the  point ; 
when  very  thin  they  may  be  whisked  in  the  air  to  cool  them,  but  they  are  more  generally  thrust  into 
the  tallow  of  the  candle  or  the  oil  of  the  lamp  ; they  are  tempered  either  by  their  own  heat,  or  by  im- 
mersion in  the  flame  below  the  point  of  the  tool. 

For  tooLs  between  those  suited  to  the  action  of  the  blowpipe,  and  those  proper  for  the  open  fire,  there 
are  many  which  require  either  the  iron  tube,  or  the  bath  of  lead  or  charcoal ; but  the  greater  number 
of  works  are  hardened  in  the  ordinary  smith’s  fire,  without  such  defences. 

Tools  of  moderate  size,  such  as  the  majority  of  turning  tools,  carpenters’  chisels  and  gouges,  and  so 
forth,  are  generally  heated  in  the  open  fire ; they  require  to  be  continually  drawn  backwards  and  for- 
wards through  the  fire,  to  equalize  the  temperature  applied : they  are  plunged  vertically  into  the  water, 
and  then  moved  about  sideways  to  expose  them  to  the  cooler  portions  of  the  fluid.  If  needful,  they 
are  only  dipped  to  a certain  depth,  the  remainder  being  left  soft. 

Some  persons  use  a shallow  vessel  filled  only  to  the  height  of  the  portion  to  be  hardened,  and  plunge 
the  tools  to  the  bottom ; but  this  strict  line  of  demarcation  is  sometimes  dangerous,  as  the  tools  are  ajjt 
to  become  cracked  at  the  part,  and  therefore  a small  vertical  movement  is  also  generally  given,  that 
the  transition  from  the  hard  to  the  soft  part  may  occupy  more  length. 

■Razors  and  penknives  are  too  frequently  hardened  without  the  removal  of  the  scale  arising  from  the 
forging;  this  practice  which,  is  not  done  with  the  best  works,  cannot  be  too  much  deprecated.  The  blades 
are  heated  in  a coke  or  charcoal  fire,  and  dipped  into  the  water  obliquely.  In  tempering  razors,  they 


710 


TEMPERING  METALS,  ETC. 


are  laid  on  their  backs  upon  a clear  fire,  about  half-a-dozen  together,  and  they  are  removed  one  at  a 
time,  "when  the  edges,  ■which  are  as  yet  thick,  come  down  to  a pale  straw-color ; should  the  backs  acci 
dentally  get  heated  beyond  the  straw-color,  the  blades  are  cooled  in  water,  but  not  otherwise.  Pen 
knife  blades  are  tempered,  a dozen  or  two  at  a time,  on  a plate  of  iron  or  copper,  about  twelve  inches 
long,  three  or  four  wide,  and  about  a quarter  of  an  inch  thick ; the  blades  are  arranged  close  together 
on  their  backs,  and  lean  at  an  angle  against  each  other.  As  they  come  down  to  the  temper,  they  are 
picked  out  with  small  pliers  and  thrown  into  water,  if  necessary  ; other  blades  are  then  thrust  forward 
from  the  cooler  parts  of  the  plate  to  take  their  place. 

Hatchets,  adzes,  cold  chisels,  and  numbers  of  similar  tools,  in  which  the  total  bulk  is  considerable 
compared  with  the  part  to  be  hardened,  are  only  partially  dipped ; they  are  afterwards  let  down  by 
the  heat  of  the  remainder  of  the  tool,  and  when  the  color  indicative  of  the  temper  is  attained,  they  are 
entirely  quenched.  With  the  view  of  removing  the  loose  scales,  or  the  oxidation  acquired  in  the  fire, 
some  workmen  rub  the  objects  hastily  in  dry  salt  before  plunging  them  in  the  water,  in  order  to  give 
them  a cleaner  and  whiter  face. 

In  hardening  large  dies,  anvils,  and  other  pieces  of  considerable  size,  by  direct  immersion,  the  rapid 
formation  of  steam  at  the  sides  of  the  metal  prevents  the  free  access  of  the  water  for  the  removal  of 
the  heat  with  the  required  expedition ; in  these  cases,  a copious  stream  of  water  from  a reservoir  above 
is  allowed  to  fall  on  the  surface  to  be  hardened.  This  contrivance  is  frequently  called  a “ float,”  and 
although  the  derivation  of  the  name  is  not  very  clear,  the  practice  is  excellent,  as  it  supplies  an  abun- 
dance of  cold  water ; and  which,  as  it  falls  directly  on  the  centre  of  the  anvil,  is  sure  to  render  that  part 
hard.  It  is,  however,  rather  dangerous  to  stand  near  such  works  at  the  time,  as  when  the  anvil  face  is 
not  perfectly  welded,  it  sometimes  in  part  flies  off  with  great  violence  and  a loud  report. 

Occasionally  the  object  is  partly  immersed  in  a tank  beneath  the  fall  of  water,  by  means  of  a crane 
and  slings ; it  is  ultimately  tempered  with  its  own  heat,  and  dropped  in  the  water  to  become  entirely 
cold. 

Oil,  or  various  mixtures  of  oil,  tallow,  wax,  and  resin,  are  used  for  many  thin  and  elastic  objects,  such 
as  needles,  fish-hooks,  steel  pens  and  springs,  which  require  a milder  degree  of  hardness  than  is  given 
by  water. 

For  example,  steel  pens  are  heated  in  large  quantities  in  iron  trays  within  a furnace,  and  are  then 
hardened  in  an  oily  mixture  ; generally  they  are  likewise  tempered  in  oil,  or  a composition  the  boiling 
point  of  which  is  the  same  as  the  temperature  suited  to  letting  them  down.  This  mode  is  particularly 
expeditious,  as  the  temper  cannot  fall  below  the  assigned  degree.  The  dry  heat  of  an  oven  is  also 
used,  and  both  the  oil  and  oven  may  be  made  to  serve  for  tempers  harder  than  that  given  by  boiling 
oil ; but  more  care  and  observation  are  required  for  these  lower  temperatures. 

Saws  and  springs  are  generally  hardened  in  various  compositions  of  oil,  suet,  wax,  and  other  ingre- 
dients. The  composition  used  by  an  experienced  saw-maker  is  two  pounds  of  suet  and  a quarter  of  a 
1ound  of  bees- w7 ax  to  every  gallon  of  whale-oil ; these  are  boiled  together,  and  will  serve  for  thin  works 
and  most  kinds  of  steel.  The  addition  of  black  resin,  to  the  extent  of  about  one  pound  to  the  gallon, 
makes  it  serve  for  thicker  pieces  and  for  those  it  refused  to  harden  before ; but  the  resin  should  be 
added  with  judgment,  or  the  works  will  become  too  hard  and  brittle.  The  composition  is  useless 
when  it  has  been  constantly  employed  for  about  a month : the  period  depends,  however,  on  the  extent 
to  which  it  is  used,  and  the  trough  should  be  thoroughly  cleaned  out  before  new  mixture  is  placed  in  it. 

The  following  recipe  is  recommended  by  an  experienced  workman : “ Twenty  gallons  of  spermaceti 
oil ; twenty  pounds  of  beef  suet  rendered  ; one  gallon  of  neats-foot  oil ; one  pound  of  pitch ; three 
pounds  of  black  resin.  These  tw7o  last  articles  must  be  previously  melted  together,  and  then  added  to 
the  other  ingredients ; w7hen  the  whole  must  be  heated  in  a proper  iron  vessel,  with  a close  cover  fitted 
to  it,  until  the  moisture  is  entirely  evaporated,  and  the  composition  will  take  fire  on  a flaming  body 
being  presented  to  its  surface,  but  which  must  be  instantly  extinguished  again  by  putting  on  the  cover 
of  the  vessel.” 

The  above  ingredients  lose  their  hardening  property  after  a few  weeks’  constant  use.  The  saws  are 
heated  in  long  furnaces,  and  then  immersed  horizontally  and  edgeways  in  a long  trough  containing  the 
composition ; two  troughs  are  commonly  used,  the  one  until  it  gets  too  warm,  then  the  other  for  a pe- 
riod, and  so  on  alternately.  Part  of  the  composition  is  wiped  off  the  saws  with  a piece  of  leather,  when 
they  are  removed  from  the  trough,  and  they  are  heated  one  by  one  over  a clear  coke  fire,  until  the 
grease  inflames  ; this  is  called  “ blazing  off.”  When  the  saws  are  wanted  to  be  rather  hard,  but  little 
of  the  grease  is  burned  off;  when  milder,  a larger  portion ; and  for  a spring  temper,  the  whole  is  allowed 
to  burn  away.  When  the  work  is  thick,  or  irregularly  thick  and  thin,  as  in  some  springs,  a second  and 
third  dose  is  burned  off,  to  insure  equality  of  temper  at  all  parts  alike. 

Gun-lock  springs  are  sometimes  literally  fried  in  oil  for  a considerable  time  over  a fire  in  an  iron 
tray ; the  thick  parts  are  then  sure  to  be  sufficiently  reduced,  and  the  thin  parts  do  not  become  the 
more  softened  from  the  continuance  of  the  blazing  heat. 

Springs  and  saws  appear  to  lose  their  elasticity,  after  hardening  and  tempering,  from  the  reduction 
and  friction  they  undergo  in  grinding  and  polishing.  Towards  the  conclusion  of  the  manufacture,  the 
elasticity  of  the  saw  is  restored  principally  by  hammering,  and  partly  by  heating  it  over  a clear  coke 
fire  to  a straw-color : the  tint  is  removed  by  very  diluted  muriatic  acid,  after  which  the  saws  are  well 
washed  in  plain  w7ater  and  dried. 

Watch-springs  are  hammered  out  of  round  steel  wire,  of  suitable  diameter,  until  they  fill  the  gage 
for  width,  which  at  the  same  time  insures  equality  of  thickness ; the  holes  are  punched  in  their  ex- 
tremities, and  they  are  trimmed  on  the  edge  with  a smooth  file;  the  springs  are  then  tied  up  with 
binding-wire,  in  a loose  open  coil,  and  heated  over  a charcoal  fire  upon  a perforated  revolving-plate, 
they  are  hardened  in  oil,  and  blazed  off. 

The  spring  is  now  distended  in  a long  metal  frame,  similar  to  that  used  for  a saw-blade,  and  ground 
end  polished  with  emery  and  oil,  between  lead  blocks;  by  this  time  its  elasticity  appears  quite  Iosl, 


TEMPERING  METALS,  ETC. 


71] 


and  it  may  be  bent  in  any  direction ; its  elasticity  is,  however,  entirely  restored  by  a subsequent  ham 
mering  on  a very  bright  anvil,  which  u puts  the  nature  into  the  spring .” 

The  coloring  is  done  over  a flat  plate  of  iron,  or  hood,  under  which  a little  spirit  lamp  is  kept  burning; 
the  spring  is  continually  drawn  backwards  and  forwards,  about  two  or  three  inches  at  a time,  until  it 
assumes  the  orange  or  deep-blue  tint  throughout,  according  to  the  taste  of  the  purchaser ; by  many  the 
coloring  is  considered  to  be  a matter  of  ornamant,  and  not  essential.  The  last  process  is  to  coiL  the 
spring  into  the  spiral  form,  that  it  may  enter  the  barrel  in  which  it  is  to  be  contained  ; this  is  done  by  a 
tool  with  a small  axis  and  winch-handle,  and  does  not  require  heat. 

The  balance-springs  of  marine  chronometers,  which  are  in  the  form  of  a screw,  are  wound  into  the 
square  thread  of  a screw  of  the  appropriate  diameter  and  coarseness  ; the  two  ends  of  the  spring  are 
retained  by  side-screws,  and  the  whole  is  carefully  enveloped  in  platinum  foil,  and  tightly  bound  with 
wire.  The  mass  is  next  heated  in  a piece  of  gun-barrel  closed  at  the  one  end,  and  plunged  into  oil, 
which  hardens  the  spring  almost  without  discoloring  it,  owing  to  the  exclusion  of  the  air  by  the  close 
platinum  covering,  which  is  now  removed,  and  the  spring  is  let  down  to  the  blue,  before  removal  from 
the  screwed  block. 

The  balance  or  hair  springs  of  common  watches  are  frequently  left  soft ; those  of  the  best  watches 
are  hardened  in  the  coil  upon  a plain  cylinder,  and  are  then  curled  into  the  spiral  form  between  the 
edge  of  a blunt  knife  and  the  thumb,  the  same  as  in  curling  up  a narrow  riband  of  paper,  or  the  fila- 
ments of  an  ostrich  feather. 

Mr.  Dent  says  that  3200  balance-springs  weigh  only  one  ounce ; but  springs  also  include  the  heaviest 
examples  of  hardened-steel  works  uncombined  with  iron ; for  example,  of  Mr.  Adams’  patent  bow- 
springs  for  all  kinds  of  vehicles,  some  intended  for  railway  use,  measure  3-1  feet  long,  and  weigh  50 
pounds  each  piece ; two  of  these  are  used  in  combination  : other  single  sjirings  are  6 feet  long,  and  weigh 
70  pounds. 

In  hardening  them  they  are  heated  by  being  drawn  backwards  and  forwards  through  an  ordinary 
forge-fire,  built  hollow,  and  they  are  immersed  in  a trough  of  plain  water : in  tempering  them  they  are 
heated  until  the  black-red  is  just  visible  at  night;  by  daylight  the  heat  is  denoted  by  its  making  a piece 
of  wood  sparkle  when  rubbed  on  the  spring,  which  is  then  allowed  to  cool  in  the  air.  The  metal  is 
9-16ths  of  an  inch  thick,  and  Mr.  Adams  considers  5-8ths  the  limit  to  which  steel  will  harden  properly 
— that  is,  sufficiently  alike  to  serve  as  a spring : he  tests  their  elasticity  far  beyond  their  intended  range. 

Great  diversity  of  opinion  exists  respecting  the  cause  of  elasticity  in  springs : by  some  it  is  referr  d 
to  different  states  of  electricity ; by  others  the  elasticity  is  considered  to  reside  in  the  thin,  blue,  oxidized 
surface,  the  removal  of  which  is  thought  to  destroy  the  elasticity,  much  in  the  same  manner  that  the 
elasticity  of  a cane  is  greatly  lost  by  stripping  off  its  siliceous  rind.  The  elasticity  of  a thick  spring  is 
certainly  much  impaired  by  grinding  off  a small  quantity  of  its  exterior  metal,  which  is  harder  than  the 
inner  portion  ; and  perhaps  thin  springs  sustain  in  the  polishing  a proportional  loss,  which  is  to  them 
equally  fatal. 

It  has  been  found  experimentally  that  the  bare  removal  of  the  blue  tint  from  a pendulum  spring,  by 
its  immersion  in  weak  acid,  caused  the  chronometer  to  lose  nearly  one  minute  each  hour  ; a second  and 
equal  immersion  scarcely  caused  any  further  loss.  It  is  also  stated  as  a well-known  fact  that  such 
springs  get  stronger,  in  a minute  degree,  during  the  first  two  or  three  years  they  are  in  use,  from  some 
atmospheric  change ; when  the  springs  are  coated  with  gold  by  the  electrotype  process,  no  such  change 
is  observable,  and  the  covering,  although  perfect,  may  be  so  thin  as  not  to  compensate  for  the  loss  of 
the  blue  oxidized  surface. 

One  of  the  most  serious  evils  in  hardening  steel,  especially  in  thick  blocks,  or  those  which  are  un- 
equally thick  and  thin,  is  their  liability  to  crack,  from  the  sudden  transition ; and  in  reference  to  hard- 
ening razors,  a case  in  point,  Mr.  Stodart  mentions  it  as  the  observation  and  practice  of  one  of  his  work- 
men, “ that  the  charcoal  fire  should  be  made  up  with  shavings  of  leather and  upon  being  asked  what 
good  he  supposed  the  leather  could  do,  this  workman  replied,  “that  he  could  take  upon  him  to  say  that 
he  never  had  a razor  crack  in  the  hardening  since  he  had  used  this  method,  though  it  was  a frequent 
occurrence  before.” 

When  brittle  substances  crack  in  cooling,  it  always  happens  from  the  outside  contracting  and  becom- 
ing too  small  to  contain  the  interior  parts.  But  it  is  known  that  hard  steel  occupies  more  space  than 
when  soft;  and  it  may  easily  be  inferred  that  the  nearer  the  steel  approaches  to  the  state  of  iron,  the 
less  will  be  this  increase  of  dimensions.  If,  then,  we  suppose  a razor  or  any  other  piece  of  steel  to  be 
heated  in  an  open  fire  with  a current  of  air  passing  through  it,  the  external  part  will,  by  the  loss  of 
carbon,  become  less  steely  than  before ; and  when  the  whole  piece  comes  to  be  hardened,  the  inside 
will  be  too  large  for  the  external  part,  which  will  probably  crack.  But  if  the  piece  of  steel  be  wrapped 
up  in  the  cementing  mixture,  or  if  the  fire  itself  contain  animal  coal,  and  is  put  together  so  as  to  operate 
in  the  manner  of  that  mixture,  the  external  part,  instead  of  being  degraded  by  this  heat,  will  be  more 
carbonated  than  the  internal  part,  in  consequence  of  which  it  will  be  so  far  from  splitting  or  bursting 
during  its  cooling,  that  it  will  be  acted  upon  in  a contrary  direction,  tending  to  render  it  more  dense 
and  solid. 

The  cracking  which  so  often  occurs  on  the  immersion  of  steel  articles  in  water,  does  not  appear  to 
arise  so  much  from  any  decarbonization  of  the  surface  merely,  as  from  the  sudden  condensation  and 
contraction  of  a superficial  portion  of  the  metal,  while  the  mass  inside  remains  swelled  with  heat,  and 
probably  expands  for  a moment  on  the  outside  coming  in  contact  with  the  water. 

The  file-makers,  to  save  their  works  from  clinking,  or  cracking  partly  through  in  hardening,  draw  the 
files  through  yeast,  beer-grounds,  or  any  sticky  material,  and  then  through  a mixture  of  common  salt 
and  animal  hoof  roasted  and  pounded.  This  is  corroborative  of  the  above,  as  in  the  like  manner  it  sup- 
plies a little  carbon  to  the  outside,  and  also  renders  the  steel  somewhat  harder  and  less  disposed  to 
crack  ; the  composition  also  renders  the  more  important  service  of  protecting  the  fine  points  of  the  teeth 
from  beintr  injured  by  the  five. 


712 


TEMPERING  METALS,  ETC. 


An  analogous  method  is  now  practised  in  hardening  patent  axletrees  which  are  of  wrought-iron,  with 
two  pieces  of  steel  welded  into  the  lower  side  where  they  rest  upon  the  wheels  and  sustain  the  load 
The  work  is  heated  in  an  open  forge-fire,  quite  in  the  ordinary  way,  and  when  it  is  removed  a mixture, 
principally  the  prussiate  of  potash,  is  laid  upon  the  steel ; the  axletree  is  then  immediately  immersed 
in  water,  and  additional  water  is  allowed  to  fall  upon  it  from  a cistern.  The  steel  is  considered  to  be- 
come very  materially  harder  for  the  treatment,  and  the  iron  around  the  same  is  also  partially  hardened 

These  are,  in  fact,  applications  of  the  case-hardening  process,  which  is  usually  applied  to  wrought- 
iron  for  giving  it  a steely  exterior,  as  the  name  very  properly  implies.  Occasionally  steel  which  hardens 
hut  imperfectly,  either  from  an  original  defect  in  the  material,  or  from  its  having  become  deteriorated 
by  bad  treatment,  or  too  frequent  passage  through  the  fire,  is  submitted  to  the  case-hardenitag  process 
in  the  ordinary  way,  by  inclosing  the  objects  in  iron  boxes,  as  will  be  explained.  This  in  part  restores 
the  carbon  which  has  been  lost,  and  the  steel  admits  of  being  hardened ; but  this  practice  is  not  to  be 
generally  recommended,  although  it  is  well  employed  for, the  purposes  of  transfer  engraving,  explained 
at  Engraving  on  Steel,  a method  introduced  by  Mr.  Jacob  Perkins,  and  which  took  its  origin  in  the 
curious  transfer  processes  of  the  calico- works,  wherein,  however,  copper  is  the  material  principally  used. 

Various  methods  have  been  likewise  attempted  to  prevent  the  distortions  to  which  work  is  liable  in 
the  operation  of  hardening,  but  without  any  very  advantageous  results  : for  instance,  it  has  been  rec- 
ommended to  harden  small  cylindrical  wires  by  rolling  them  when  heated  between  cold  metallic  sur- 
faces to  retain  them  perfectly  straight.  This  might  probably  answer,  but  unfortunately  cylindrical  steel 
wires  supply  but  a very  insignificant  portion  of  our  wants. 

Another  mode  tried  by  Dr.  Wollaston  was  to  inclose  the  piece  of  steel  in  a tube  filled  with  Newton’s 
fusible  alloy,  the  whole  to  be  heated  to  redness  and  plunged  in  cold  water;  the  object  was  released  by 
immersion  in  boiling  water,  which  melted  the  alloy,  and  the  piece  came  out  perfectly  unaltered  in  form, 
and  quite  hard.  This  mode  is  too  circuitous  for  common  practice,  and  the  reason  why  it  is  to  be  always 
successful  is  not  very  apparent. 

Mr.  Perkins  resorted  to  a very  simple  practice  with  the  view  of  lessening  the  distortion  of  his  en- 
graved steel  plates,  by  boiling  the  water  in  which  they  were  to  be  hardened  to  drive  off  the  air,  and 
plunging  them  vertically  ; and  as  the  plates  were  required  to  be  tempered  to  a straw  color,  instead  ol 
allowing  them  to  remain  in  the  water  until  entirely  cold,  he  removed  them  whilst  the  inside  was  still 
hot,  and  placed  them  on  the  top  of  a clear  fire  until  the  tallow  with  which  they  were  rubbed  smoked ; 
the  plate  was  then  returned  to  the  water  for  a few  moments,  and  so  on  alternately  until  they  were  quite 
cold,  the  surface  never  being  allowed  to  exceed  the  tempering  heat. 

From  various  observations,  it  appears  on  the  whole  to  be  the  best  in  thick  works  thus  to  combine  the 
hardening  and  tempering  processes,  instead  of  allowing  the  objects  to  become  entirely  cold,  and  then  to 
reheat  them  for  tempering.  To  ascertain  the  time  when  the  plate  should  be  first  removed  from  the 
water,  Mr.  Perkins  heated  a piece  of  steel  to  the  straw  color,  and  dipped  it  into  water  to  learn  the  sound 
it  made ; and  when  the  hardened  plate  caused  the  same  sound,  it  was  considered  to  be  cooled  Ic  the 
right  degree,  and  was  immediately  withdrawn. 

Locomotive  wheels  with  hardened-steel  tires  may  be  viewed  as  the  most  ponderous  example  of  hard- 
ening, as  the  tires  of  the  eight-foot  wheels  weigh  about  10  cwt.,  and  consist  of  about  one-third  steel,  and 
there  seems  no  reason  why  this  diameter  might  not  be  greatly  exceeded. 

The  materials  for  the  tires  are  first  swaged  separately,  and  then  welded  together  under  the  heavy 
hammer  at  the  steel-works,  after  which  they  are  bent  to  the  circle,  welded,  and  turned  to  certain  gages. 
The  tire  is  now  heated  to  redness  in  a circular  furnace  ; during  the  time  it  is  getting  hot  the  iron  wheel, 
previously  turned  to  the  right  diameter,  is  bolted  down  upon  a face-plate ; the  tire  expands  with  the 
heat,  and  when  at  a cherry-red  it  is  dropped  over  the  wheel,  for  which  it  was  previously  too  small,  and 
is  also  hastily  bolted  down  to  the  surface-plate,  the  whole  load  is  quickly  immersed  by  a swing-crane 
into  a tank  of  water  about  five  feet  deep,  and  hauled  up  and  down  until  nearly  cold ; the  steel  tires  are 
not  afterwards  tempered. 

Hardening  and  softening  cast-iron. — The  similitude  of  chemical  constitution  between  steel,  which 
usually  contains  about  one  per  cent,  of  carbon,  and  cast-iron,  that  has  from  three  to  six  or  seven  per 
cent.,  naturally  leads  to  the  expectation  of  some  correspondence  in  their  characters,  and  which  is  found 
to  exist.  Thus  some  kinds  of  cast-iron  will  harden  almost  like  steel,  but  they  generally  require  a higher 
temperature ; and  the  majority  of  cast-iron,  also  like  steel,  assumes  different  degrees  of  hardness,  ac- 
cording to  the  rapidity  with  which  the  pieces  are  allowed  to  cool. 

The  casting  left  undisturbed  in  the  mould,  is  softer  than  a similar  one  exposed  to  the  air  soon  after  it 
has  been  poured.  Large  castings  cannot  cool  very  hastily,  and  are  seldom  so  hard  as  the  small  pieces, 
some  of  which  are  hardened  like  steel  by  the  moisture  combined  with  the  moulding  sand,  and  cannot  be 
filed  until  they  have  been  annealed  after  the  manner  of  steel,  which  renders  them  soft  and  easy  to  be 
worked. 

Chilled  iron  castings  present  as  difficult  a problem  as  the  hardening  and  tempering  of  steel ; the  fact 
is  simply  this,  that  iron  castings,  made  in  iron  moulds  under  particular  circumstances,  become  on  their 
outer  surfaces  perfectly  hard,  and  resist  the  file  almost  like  hardened  steel ; the  effect  is,  however,  su- 
perficial, as  the  chilled  exterior  shows  a distinct  line  of  demarcation  when  the  objects  are  broken. 

Ploughshares  are  sometimes  cast  on  this  principle ; the  under  sides  and  points  are  hard  from  the 
chilling  process,  and  these,  from  resisting  abrasion  more  than  the  softer  parts,  maintain  a comparatively 
thin  edge. 

The  production  of  chilled  castings  is  always  a matter  of  some  uncertainty,  and  depends  upon  the 
united  effect  of  several  causes:  the  quality  of  the  iron,  the  thickness  of  the  casting,. the  temperature  of 
the  iron  at  the  time  of  pouring,  and  the  condition  or  temperature  of  the  iron  mould,  which  has  a greater 
effect  in  “ striking  in”  when  the  mould  is  heated  than  if  quite  cold : a very  thin  stratum  of  earthy  matter 
will  almost  entirely  obviate  the  chilling  effect.  A cold  mould  does  not  generally  chill  so  readily  as  one 
heated  nearly  to  the  extent  called  “ black-hot;”  but  the  reverse  conditions  occur  with  some  cast-irrn- 


TEMPERING  METALS,  ETC. 


713 


There  is  this  remarkable  difference  between  cast-iron  thus  hardened,  and  steel  hardened  by  pi  .inging 
whilst  hot  into  water : that  whereas  the  latter  is  softened  again  by  a dull-red  heat,  the  chilled  castings, 
on  the  contrary,  are  turned  out  of  the  moulds  as  soon  as  the  metal  is  set,  and  are  allowed  to  cool  in  the 
air ; yet  although  the  whole  is  at  a bright-red  heat,  no  softening  of  the  chilled  part  takes  place.  This 
material  has  been  employed  for  punches  for  red-hot  iron ; the  punches  were  fixed  in  cast-iron  sockets, 
from  which  they  only  projected  sufficiently  to  perforate  the  wheel-tires  in  the  formation  of  which 
they  were  used,  and  from  retaining  their  hardness  they  were  more  efficient  than  those  punches  made 
of  steel. 

Chilled  castings  are  also  commonly  employed  for  axletree-boxes,  and  naves  of  wheels,  which  are  fin- 
ished by  grinding  only ; also  for  cylinders  for  rolling  metal,  for  the  heavy  hammers  and  anvils  or  stithies 
for  iron-works,  the  stamp-heads  for  pounding  metallic  ores,  <fcc.  Cannon-balls,  as  well  as  ploughshares, 
are  examples  of  chilled  castings ; with  the  destructive  engine  the  chilling  is  unimportant,  and  occurs 
alone  from  the  method  essential  to  giving  the  balls  the  required  perfection  of  form  and  size. 

Malleable-iron  castings  are  at  the  opposite  extreme  of  the  scale,  and  are  rendered  externally  soft  by 
the  abstraction  of  their  carbon,  whereby  they  are  nearly  reduced  to  the  condition  of  pure  malleable  iron, 
but  without  the  fibre  which  is  due  to  the  hammering  and  rolling  employed  at  the  forge. 

The  malleable-iron  castings  are  made  front  the  rich  Pennsylvania  iron,  and  are  at  first  as  brittle  as 
glass  or  hardened  steel ; they  are  inclosed  in  iron  boxes  of  suitable  size,  and  surrounded  with  pounded 
iron-stone,  or  some  of  the  metallic  oxides,  as  the  scales  from  the  iron  forge,  or  with  common  linte,  and 
various  other  absorbents  of  carbon,  used  either  together  or  separately.  The  cases,  which  are  sometimes 
as  large  as  barrels,  are  luted,  rolled  into  the  ovens  or  furnaces,  and  submitted  to  a good  heat  for  about 
live  days,  and  are  then  allowed  to  cool  very  gradually  within  the  furnaces. 

The  time  and  other  circumstances  determine  the  depth  of  the  effect ; thin  pieces  become  malleable 
entirely  through,  they  are  then  readily  bent,  and  may  be  slightly  forged ; cast-iron  nails  and  tacks  thus 
treated  admit  of  being  clinched,  thicker  pieces  retain  a central  portion  of  cast-iron,  but  in  a softened 
state,  and  not  brittle  as  at  first ; on  sawing  them  through,  the  skin  or  coat  of  soft  iron  is  perfectly  dis- 
tinct from  the  remainder. 

The  mode  is  particularly  useful  for  thin  articles  that  can  be  more  economically  and  correctly  cast 
than  wrought  at  the  forge,  as  bridle-bits,  snuffers,  parts  of  locks,  culinary  and  other  vessels,  pokers  and 
tongs,  many  of  which  are  subsequently  case-hardened  and  polished,  as  will  be  explained,  but  malleable 
cast-iron  should  never  be  used  for  cutting-tools. 

Case-hardening  wrought  and  cast  iron. — The  property  of  hardening  is  not  possessed  by  pure  malleable 
iron;  but  we  have  now  to  explain  a rapid  and  partial  process  of  cementation,  by  which  wrought-iron  is 
first  converted  exteriorly  into  steel,  and  is  subsequently  hardened  to  that  particular  depth ; leaving  the 
central  parts  in  their  original  condition  of  soft  fibrous  iron.  The  process  is  very  consistently  called  case- 
hardening,  and  is  of  great  importance  in  the  mechanical  arts,  as  the  pieces  combine  the  economy, 
strength,  and  internal  flexibility  of  iron,  with  a thin  casing  of  steel ; which,  although  admirable  as  an 
armor  of  defence  from  wear  or  deterioration  as  regards  the  surface,  is  unfit  for  the  formation  of  cutting 
edges  or  tools,  owing  to  the  entire  absence  of  hammering,  subsequent  to  the  cementation  with  the  car- 
bon. Cast-iron  obtains  in  like  manner  a coating  of  steel,  which  surrounds  the  peculiar  shape  the  metal 
may  have  assumed  iri  the  iron-foundry  and  workshop. 

The  principal  agents  used  for  case-hardening  are  animal  matters,  as  the  hoofs,  horns,  bones,  and  skins 
of  animals ; these  are  nearly  alike  in  chemical  constitution,  and  they  are  mostly  charred  and  coarsely 
pounded ; some  persons  also  mix  a little  common  salt  with  some  of  the  above  ; the  works  should  be  sur- 
rounded on  all  sides  with  a layer  from  half  an  inch  to  one  inch  thick. 

The  methods  pursued  by  different  individuals  do  not  greatly  differ  ; for  example,  the  gunsmith  inserts 
the  iron-work  of  the  gun-lock  in  a sheet-iron  case  in  the  midst  of  bone-dust,  (often  not  burned,)  the  lid  of 
the  box  is  tied  on  with  iron-wire,  and  the  joint  is  luted  with  clay ; it  is  then  heated  to  redness  as  quickly 
as  possible  and  retained  at  that  heat  from  half  an  hour  to  an  hour,  and  the  contents  are  quickly  im- 
mersed in  cold  water.  The  objects  sought  are  a steely  exterior,  and  a clean  surface  covered  with  the 
pretty  mottled  tints,  apparently  caused  by  oxidation  from  the  partial  admission  of  air. 

Some  of  the  malleable-iron  castings,  such  as  snuffers,  are  case-hardened  to  admit  of  a better  polish ; 
it  is  usually  done  with  burnt  bone-dust,  and  at  a dull-red  heat ; they  remain  in  the  fire  about  two  or 
three  hours,  and  should  be  immersed  in  oil,  as  it  does  not  render  them  quite  so  brittle  as  when  plunged 
into  water.  It  must  be  remembered  they  are  sometimes  changed  throughout  their  substance  into  an 
inferior  kind  of  steel,  by  a process  that  should  in  such  instances  be  called  cementation,  and  not  case- 
hardening,  consequently  they  will  not  endure  violence. 

The  mechanician  and  engineer  use  horns,  hoofs,  bone-dust,  and  leather,  and  allow  the  period  to  extend 
from  two  to  eight  hours,  most  generally  four  or  five ; sometimes,  for  its  greater  penetration,  the  process 
is  repeated  a second  time  with  new  carbonaceous  materials.  Some  open  the  box  and  immerse  the  work 
in  water  direct  from  the  furnace ; others,  with  the  view  to  preserve  a better  surface,  allow  the  box  to 
cool  without  being  opened,  and  harden  the  pieces  with  the  open  fire  as  a subsequent  operation ; the 
carbon  once  added,  the  work  may  be  annealed  and  hardened  much  the  same  as  ordinary  steel. 

When  the  case-hardening  is  required  to  terminate  at  any  particular  part,  as  a shoulder,  the  object  is 
left  with  a band  or  projection,  the  work  is  allowed  to  cool  without  being  immersed  in  water,  the  band 
is  turned  off,  and  the  work  when  hardened  in  the  open  fire  is  only  effected  so  far  as  the  original  ce- 
mented surface  remains.  This  ingenious  method  was  introduced  by  Mr.  Roberts,  who  considers  the 
success  ot  the  case-hardening  process  to  depend  on  the  gentle  application  of  the  heat ; and  that,  by 
proper  management  not  to  overheat  the  work,  it  may  be  made  to  penetrate  three-eighths  of  an  inch  in 
lour  or  five  hours. 

A new  substance  for  the  case-hardening  process,  but  containing  the  same  elements  as  those  more 
commonly  employed,  has  of  late  years  been  added,  namely,  the  prussiate  of  potash,  (a  salt  consisting  r- 
two  atoms  of  carbon  and  one  of  nitrogen,)  which  is  made  from  a variety  of  animal  matters. 


714 


THERMOMETER. 


It  is  a new  application  ■without  any  change  of  principle  ; the  time  occupied  in  this  steelifying  process 
is  sometimes  only  minutes,  instead  of  hours  and  days ; as,  for  example,  when  iron  is  heated  in  the  open 
fire  to  a dull  red,  and  the  prussiate  is  either  sprinkled  upon  it  or  rubbed  on  in  the  lump,  it  is  returned 
to  the  fire  for  a few  minutes  and  immersed  in  water ; but  the  process  is  then  exceedingly  superficial, 
and  it  may  if  needful  be  limited  to  any  particular  part  upon  which  alone  the  prussiate  is  applied.  The 
effect  by  many  is  thought  to  be  partial  or  in  spots,  as  if  the  salt  refused  to  act  uniformly,  in  the  same 
manner  that  water  only  moistens  a greasy  surface  in  places. 

The  prussiate  of  potash  has  been  used  for  case-hardening  the  bearings  of  wrought-iron  shafts,  but  this 
seems  scarcely  worth  the  doing.  It  has  been  also  employed  with  the  view  of  giving  an  additional  and 
extreme,  although  superficial  hardness  to  steel,  as  in  axletrees,  Perkins’s  engraved  steel-plates,  <tc. ; but 
we  have  only  heard  of  one  individual  who  has  encased  work  with  this  salt — it  was  for  case-hardening 
the  iron  rollers  and  side-plates  of  glaziers’  vices  employed  for  milling  window-lead. 

In  the  general  way,  the  conversion  of  the  iron  into  steel  by  case-hardening  is  quite  superficial,  and 
does  not  exceed  the  sixteenth  of  an  inch ; if  made  to  extend  to  one-quarter  or  three-eighths  of  an  inch 
in  depth,  to  say  the  least,  it  would  be  generally  useless,  as  the  object  is  to  obtain  durability  of  surface, 
with  strength  of  interior,  and  this  would  disproportionately  encroach  on  the  strong  iron  within.  The 
steel  obtained  in  this  adventitious  manner  is  not  equal  in  strength  to  that  converted  and  hammered  in 
the  usual  way,  and  if  sent  in  so  deeply,  the  provision  for  wear  would  far  exceed  that  which  is  required. 

Let  us  compare  the  case-hardening  process  with  the  usual  conversion  of  steel.  The  latter  requires  a 
period  of  about  seven  days,  and  a very  pure  carbon,  namely,  wood  charcoal,  of  which  a minute  portion 
only  is  absorbed  ; and  it  being  a simple  body,  when  the  access  of  air  is  prevented  by  the  proper  security 
of  the  troughs,  the  bulk  of  the  charcoal  remains  unconsumed,  and  is  reserved  for  future  use,  as  it  has 
undergone  no  change.  The  hasty  and  partial  process  of  cementation  is  produced  in  a period  commonly 
less  than  as  many  hours  with  the  animal  charcoal,  or  than  as  many  minutes  with  the  prussiate  of  pot- 
ash ; but  all  these,  are  compound  bodies,  (which  contain  cyanogen,  a body  consisting  of  carbon  and  nitro- 
gen,) and  are  never  used  a second  time,  but  on  the  contrary  the  process  is  often  repeated  with  another 
dose.  It  would  be,  therefore,  an  interesting  inquiry  for  the  chemist,  as  to  whether  the  cyanogen  is  ab- 
sorbed after  the  same  manner  as  carbon  in  ordinary  steel,  (and  which  in  Mackintosh’s  patent  process 
was  driven  through  the  crucible  in  the  form  of  carbonic  acid  gas,  and  is  stated  to  be  absorbed  at  the 
rate  of  one-thirtieth  of  an  inch  in  depth,  each  hour ;)  or  whether  the  nitrogen  assists  in  any  way  in  hast- 
ening the  admission  of  the  carbon,  by  some  as  yet  untraced  affinity  or  decomposition. 

This  hasty  supposition  will  apply  less  easily  to  cast-iron,  which  contains  from  three  to  seven  times  as 
much  carbon  as  steel,  and  although  not  always  hardened  by  simple  immersion,  is  constantly  under  the 
influence  of  the  case-hardening  process ; unless  we  adopt  the  supposition,  that  the  carbon  in  cast-iron 
which  is  mixed  with  the  metal  in  the  shape  of  cinder  in  the  blast-furnace,  when  all  is  in  a fluid  state,  is 
in  a less  refined  union  than  that  instilled  in  a more  aeriform  condition  in  the  acts  of  cementation  and 
case-hardening.  (See  Tools.) 

THERMOMETER.  An  instrument  for  measuring  variations  of  heat  or  temperature.  The  principle 
upon  which  thermometers  are  constructed  is  the  change  of  volume  which  takes  place  in  bodies  when 
their  temperature  undergoes  an  alteration.  Generally  speaking,  all  bodies  expand  when  heated  and 
contract  when  cooled,  and  in  such  a manner  that,  under  the  same  circumstances  of  temperature,  they  re- 
turn to  the  same  dimensions;  so  that  the  change  of  volume  becomes  the  exponent  of  the  temperature 
which  produces  it.  But  as  it  is  necessary  not  merely  that  expansion  and  contraction  take  place,  but 
that  they  be  capable  of  being  conveniently  observed  and  measured,  only  a small  number  of  bodies  are 
adapted  for  thermometrical  purposes.  Solid  bodies,  for  example,  undergo  so  small  a change  of  volume 
with  moderate  variations  of  temperature,  that  they  are  in  general  only  used  for  measuring  very  high 
temperatures,  as  the  heat  of  furnaces,  of  melting  metals,  <kc.  Instruments  for  such  purposes  are  called 
pyrometers.  (See  Pyrometer.)  The  gaseous  fluids,  on  the  other  hand,  are  extremely  susceptible  ol 
the  impressions  of  heat  and  cold ; and  as  their  changes  of  volume  are  great  even  with  moderate  acces- 
sions of  heat,  they  are  only  adapted  for  indicating  very  minute  variations,  or  for  forming  differential 
thermometers.  Liquids  hold  an  intermediate  place  ; and  by  reason  of  their  moderate  but  sensible  ex- 
pansion through  the  ranges  of  temperature  within  which  observations  have  to  be  made  for  by  far  the 
greater  number  of  purposes,  are  commonly  used  for  the  construction  of  thermometers.  Various  liquids 
have  been  proposed,  as  oils,  ether,  spirits  of  wine,  and  mercury ; but  scarcely  any  other  than  the  two 
last  are  now  ever  used,  and  mercury  by  far  the  most  generally. 

The  properties  which  render  mercury  preferable  to  all  other  liquids  (unless  for  particular  purposes) 
are  these:  1.  It  supports,  before  it  boils  and  is  reduced  to  vapor,  more  heat  than  any  other  fluid,  ex- 
cepting certain  oils,  and  endures  a greater  cold  than  would  congeal  most  other  liquids,  excepting  certain 
spirituous  liquors.  2.  It  takes  the  temperature  of  the  medium  in  which  it  is  placed  more  quickly  than 
any  other  fluid.  Count  Rumford  found  that  mercury  was  heated  from  the  freezing  to  the  boiling  point 
of  water  in  58  seconds,  while  water  took  133  seconds,  and  air  617  seconds,  the  heat  applied  being  the 
same,  in  all  the  three  cases.  3.  The  variations  of  its  volume  within  limits  which  include  the  tempera- 
tures most  frequently  required  to  be  observed,  are  found  to  be  perfectly  regular,  and  proportional  tc 
the  variations  of  temperature.  The  spirit  thermometer  is  now  little  used  excepting  for  observations  oi 
very  low  temperatures,  or  as  a self-registering  instrument  for  meteorological  observations. 

Construction  of  the  mercurial  thermometer. — In  order  to  render  small  changes  of  volume  sensible,  a 
glass  bulb,  having  a slender  hollow  tube  attached  to  it,  is  filled  with  mercury,  so  that  expansion  or  con- 
traction can  only  take  place  by  the  rise  or  fall  of  the  liquid  in  the  tube.  The  diameter  of  the  tube  may 
be  of  any  convenient  size  ; but  the  smaller  it  is  the  larger  will  be  the  scale  of  the  variations ; and  capil- 
lary tubes  are  usually  employed.  It  is  essential  that  the  diameter  of  the  bore  be  of  a uniform  width 
throughout ; a quality  which  is  tested  by  drawing  up  into  the  tube  a short  column  of  mercury,  and 
measuring  its  length  at  the  different  parts  with  a pair  of  compasses.  Not  more  than  a sixth  part  of  the 
tubes  which  come  from  the  glass-house  are  found  to  be  fit  for  the  purpose. 


THERMOMETER. 


71, 


Having  selected  a tube,  the  workman  begins  by  blowing  a hollow  ball  A,  Fig.  3409,  upon  one  extrem- 
'ty  of  it,  by  means  of  an  air-bag  of  caoutchouc,  (in  order  to  avoid  the  introduction  of  watery  vapor  by 
olowing  from  the  mouth.)  The  length  which  the  thermometer  is  to  have  is  then  marked,  and 
above  this  point  the  tube  is  expanded  into  a second  bulb  B,  rather  larger  than  the  first.  When  the  3409 
tube  has  acquired  its  natural  temperature  one  of  the  bulbs  is  warmed,  in  order  to  expel  the  air  I 
from  it,  and  the  open  end  of  the  tube  is  plunged  into  distilled  and  well-boiled  mercury.  During  I 
the  cooling  the  mercury  rises  into  the  second  bulb  B,  whence  it  is  made  to  pass  into  A by  placing  JL._ 
this  undermost,  and  expelling  the  air  from  it  by  heat,  after  which  the  mercury  descends  from  the 
effect  of  cooling.  When  the  bulb  A has  been  completely  filled,  and  also  a part  of  B,  the  tube  is 
suspended  horizontally  over  a charcoal  fire,  so  as  to  be  equally  heated  throughout,  and  the  in- 
closed mercury  boiled,  in  order  to  expel  every  remaining  particle  of  air  or  humidity.  The  open 
end  is  then  touched  with  sealing-wax,  and  the  tube  withdrawn  from  the  fire,  and  placed  in  an  up- 
right position  until  it  is  cooled,  when  the  bulb  A and  the  portion  of  the  tube  under  B will  be  filled  j 
with  mercury.  A portion  of  mercury  is  then  expelled  by  heat,  so  that  the  column  may  stand  at 
the  proper  height  in  the  tube.  The  tube  is  then  carefully  softened  with  the  blowpipe,  and  her- 
metically sealed  under  the  bulb  B,  which  is  thus  cut  off. 

Graduation  of  the  scale. — The  instrument  prepared  in  the  manner  now  described  is  admirably  adapted 
for  rendering  evident  the  expansions  and  contractions  of  the  inclosed  fluid,  and  it  only  remains  to  adopt 
a scale  to  it  in  order  to  have  a complete  thermometer.  The  graduation  of  the  scale  is  in  some  measure 
arbitrary ; nevertheless,  in  order  that  different  thermometers  may  be  comparable  with  each  other,  it  is 
necessary  that  two  points  at  least  be  taken  on  the  scale  corresponding  to  fixed  and  determinate  tem- 
peratures, the  distance  between  which  will  determine  the  graduation.  The  two  points  which  are  now 
universally  chosen  for  this  purpose  are  those  which  correspond  to  the  temperatures  of  freezing  and  boil- 
ing water.  With  respect  to  the  first  of  these  there  is  no  difficulty  ; it  is  only  necessary  to  surround  the 
bulb  with  ice,  and  to  mark  on  the  stem  the  point  at  which  the  mercury  stands  when  the  ice  begins  to 
melt.  The  boiling  point  is  not  so  readily  determined.  As  the  temperature  at  which  water  boils  varies 
to  a small  extent  with  the  barometric  pressure,  it  is  necessary,  in  order  to  have  instruments  comparable 
with  each  other,  either  that  the  boiling  point  on  the  scale  be  determined  when  the  barometer  stands  at 
a certain  height  which  is  arbitrarily  assumed  for  the  standard,  or  else  to  apply  a correction  when  the 
actual  height  of  the  barometer  is  above  or  below  the  assumed  standard.  De  Luc  made  a number  of 
experiments  on  this  subject,  and  gave  a formula  for  the  correction,  which  was  adapted  to  Fahrenheit’s 
scale  and  English  inches  by  Horsley.  (Phil.  Trans.,  vol.  Ixiv.)  A committee  of  the  Royal  Society  who 
undertook  to  investigate  the  best  method  of  adjusting  the  fixed  points,  and  whose  report  is  contained  in 
vol.  lxvii.  of  the  Transactions,  laid  down  a set  of  rules  which  have  been  generally  followed  by  English 
instrument-makers.  They  recommended  the  adoption  of  29'8  inches  for  the  standard  barometric  pres- 
sure, and  gave  a table  of  the  corrections  for  all  ordinary  pressures  above  or  below  this  standard.  Their 
table  is  very  nearly  represented  by  the  following  simple  rule,  which  will  be  quite  sufficient  for  the  guid- 
ance of  the  artist  in  all  ordinary  cases  : 

Supposing  the  thermometer  placed  in  an  atmosphere  of  steam  immediately  over  the  surface  of  boil- 
ing water,  then  for  every  tenth  of  an  inch  by  which  the  barometer  is  above  or  below  29'8,  the  correction 
for  the  boiling  point  of  the  scale  of  the  thermometer  is  one-thousandth  part  of  the  interval  between  the 
freezing  and  boiling  points.  The  corrected  must  be  placed  lower  than  the  observed  boiling  point  by 
this  quantity  when  the  pressure  exceeds  29'8  inches,  and  higher  when  the  pressure  is  less  than  the 
standard. 

Several  other  minute  circumstances  must  be  attended  to  in  the  construction  of  delicate  instruments. 
As  the  temperature  of  boiling  water  is  different  at  the  top  and  near  the  bottom  of  the  vessel  in  which 
it  boils,  the  thermometer  should  not  be  plunged  into  the  water  itself,  but  into  the  vapor  which  rises 
above  it,  in  a close  vessel  with  an  aperture  for  the  escape  of  the  steam.  The  vessel  should  be  of  metal, 
because  water  boils  at  a different  temperature  in  vessels  of  different  substances,  as  metal  and  glass. 
Distilled  water,  or  clear  soft  water,  should  be  used ; if  mixed  with  saline  ingredients,  the  temperature 
at  which  it  boils  would  be  affected,  and  the  instrument  rendered  inaccurate. 

The  interval  between  the  two  fixed  points  on  the  stem  may  be  divided  into  any  number  of  degrees 
at  pleasure,  and  the  graduation  continued  above  and  below  as  far  as  may  be  thought  requisite : the  nu- 
meration may  also  be  begun  at  any  point  whatever  on  the  scale ; but  there  are  only  three  methods  of 
division  so  generally  adopted  as  to  require  particular  notice.  The  first  is  Fahrenheit’s,  which  is  used  in 
England,  Holland,  and  North  America ; the  second,  Reaumer’s,  which  was  formerly  in  general  use  in 
France,  and  is  still  followed  in  Sj>ain  and  some  parts  of  Germany ; and  the  third  that  of  Celsius,  or  the 
centigrade  scale,  now  used  in  France,  Germany,  and  Sweden. 

Fahrenheit's  scale. — Tn  this  scale  the  interval  between  the  freezing  and  boiling  points  of  water  is 
divided  into  180  equal  parts  or  degrees,  which  number  was  chosen  by  Fahrenheit,  (or  probably  Roemer,) 
from  some  theoretical  ■considerations  respecting  the  expansion  of  mercury ; it  being  computed  that  the 
thermometer,  when  plunged  into  melting  snow,  contained  11,156  parts  of  mercury,  which,  at  the  tem- 
perature of  boiling  water,  were  expanded  into  11,336  parts,  being  an  increase  of  180  parts.  The  zero 
point  of  the  scale  is  placed  at  32°  below  the  freezing  point  of  water.  It  has  been  frequently  stated 
that  this  point  was  selected  as  indicating  the  temperature  of  a freezing  mixture  of  snow  and  salt ; but 
it  appears  from  Boerhaave  that  it  was  adopted  from  a still  more  precarious  supposition,  namely,  the 
greatest  cold  observed  in  Iceland,  which  was  probably  assumed  to  be  the  lowest  natural  temperature. 
The  freezing  point  is  thus  marked  32°,  and  consequently  the  boiling  point  at  32  -f-  180  = 212.  It  must 
be  admitted  that  this  scale,  though  it  possesses  some  advantages  in  the  lowness  of  the  zero  point  and 
the  smallness  of  the  divisions,  is  not  well  adapted  to  philosophical  purposes. 

Reaumer's  scale. — Reaumer,  in  1130,  proposed  the  adoption  of  the  temperature  of  melting  ice  as  tho 
r.ero  of  the  scale,  and  to  divide  the  distance  between  this  and  the  boiling  point  of  water  into  80°,  hav- 
ing observed  that  between  those  temperatures  spirits  of  wine  (which  he  used  for  the  thermometric 


716 


THERMOMETER. 


fluid)  expanded  from  1000  parts  to  1080.  This  division  soon  became  general  in  France  and  othet 
countries,  and  a great  number  of  valuable  observations  have  been  recorded  in  terms  of  it;  but  it  is  now 
seldom  used  in  works  of  science. 

Centigrade  scale. — In  1742  Celsius,  professor  at  Upsal,  in  Sweden,  proposed  to  divide  the  space  be- 
tween the  freezing  and  boiling  points  of  water  into  100  equal  parts,  the  zero  point  being  placed  (as  in 
Reaumer’s)  at  freezing.  This  division  being  in  harmony  with  our  decimal  arithmetic,  is  better  adapted 
than  the  two  former  to  scientific  purposes.  It  has  been  adopted  by  all  the  French  writers  since  the 
Revolution,  and  is  the  best  known  in  most  parts  of  the  north  and  middle  of  Europe. 

It  has  been  sometimes  objected  to  this  scale,  (and  the  objection  applies  equally  to  Reaumer’s,)  that 
on  account  of  the  comparatively  high  point  at  which  the  zero  is  placed,  meteorological  observations  are 
embarrassed  with  the  algebraic  signs  of  plus  and  minus.  The  inconvenience  (if  any)  is  a very  trifling 
one,  and  is  much  more  than  compensated  by  the  facilities  for  calculation  which  the  scale  affords. 

Conversion  of  degrees  of  one  scale  into  degrees  of  another. — From  the  manner  in  which  the  three  scales 
are  graduated,  it  is  easy  to  deduce  formul*  expressing  any  temperature  given  according  to  one  scale  in 
terms  of  either  of  the  others.  The  interval  which  in  Fahrenheit’s  scale  is  divided  into  180  parts  is  di- 
vided into  only  100  parts  in  the  centigrade  scale,  and  into  80  in  Reaumer’s.  Hence  one  degree  of  Fah- 
renheit’s is  equal  to  5-9ths  of  a degree  of  the  centigrade,  and  to  4-9ths  of  a degree  of  Reaumer.  But 
some  attention  is  required  on  account  of  the  difference  of  the  zero  points.  For  the  sake  of  perspicuity, 
it  is  convenient  to  adapt  the  expressions  to  three  distinct  cases.  Let  F denote  degrees  of  Fahrenheit’s 
scale,  C degrees  of  the  centigrade,  and  R degrees  of  Reaumer ; then, 

Case  I.  For  all  temperatures  above  the  freezing  point, 

F — 32  = fC  = JR. 

Case  2.  For  all  temperatures  between  the  freezing  point  and  the  zero  of  Fahrenheit’s  scale, 

32  — F = — 4 C = — SR. 

Case  3.  For  all  temperatures  below  the  zero  of  Fahrenheit, 

— 32  — F=  — fC=  — §R. 

By  substituting  numbers  in  these  formula?  for  F,  C,  or  R,  as  the  case  may  require,  the  corresponding 
values  on  the  other  scales  is  immediately  obtained ; but  if  many  reductions  are  required  to  be  made,  it 
is  more  convenient  to  have  comparative  tables,  by  which  the  correspondence  of  the  scales  is  seen  at  a 
glance.  Such  tables  are  given  in  most  treatises  on  chemistry. 

Theory  of  the  graduation. — It  will  be  evident  from  what  has  now  been  said  that,  whatever  scale  be 
adopted,  the  division  is  founded  on  the  assumed  principle  that  equal  increments  of  heat  produce  equal 
expansions.  This  assumption  may  be  put  to  the  test  of  experiment  by  the  mixture  of  fluids  at  different 
temperatures.  For  example,  if  a pound  of  water  at  212°  Fahr.  be  mixed  with  another  pound  of  water 
at  32°,  and  the  requisite  precautions  be  used,  then  the  temperature  of  the  mixture  will  be  122°,  which 
is  the  arithmetical  mean  between  the  two  temperatures  ; and  if  the  assumed  principle  be  correct,  a ther- 
mometer plunged  into  the  mixture  will  stand  at  122°.  This  is  found  to  be  the  case  with  the  mercurial, 
but  not  with  the  spirit  thermometer ; and,  in  general,  thermometers  formed  of  different  fluids,  when  ex- 
posed to  the  same  temperatures,  do  not  give  the  same  indications  throughout  the  whole  extent  of  the 
scale.  An  important  question  hence  arises : what  substance  ought  to  be  adopted  as  the  standard  to 
which,  in  comparing  observations,  all  others  should  be  reduced  ? It  is,  perhaps,  not  possible  to  deter- 
mine this  question  with  absolute  certainty;  but  the  experiments  of  the  French  chemists  Dulong  and 
Petit  on  the  dilatation  of  various  substances,  render  it  probable  that  air  and  the  other  permanent  gases 
(which  all  expand  equally)  afford  the  most  accurate  indications  of  the  true  variations  of  temperature. 
As  compared  with  the  air  thermometer,  the  expansion  of  mercury  is  proportional  to  the  increase  of  tem- 
perature from  — 30°  to  -f-  100°  of  the  centigrade  scale.  From  this  point  to  360°  (the  boiling  point  of 
mercury)  mercury  expands  more  rapidly  than  air,  and  consequently  the  mercurial  thermometer  stands 
higher  than  the  air  thermometer  in  the  same  temperature.  When  the  former  indicates  200°  and  300°, 
the  latter  indicates  197°  and  292'7°  respectively ; and  it  seems  to  be  a general  law  that  all  fluids  with 
the  same  increase  of  heat  expand  more  rapidly  as  the  temperature  approaches  their  boiling  point.  The 
more  rapid  expansion  of  the  mercury  at  high  temperatures  is,  however,  in  some  measure  corrected  by 
the  expansion  of  the  bulb. 

Change  of  the  zero  point.- — There  is  a circumstance  connected  with  the  mercurial  thermometer  which 
requires  to  be  attended  to  when  very  exact  determinations  of  temperature  are  to  be  made.  Bellani,  in 
Italy,  and  Flaugergues  in  France,  observed  that  when  thermometers  which  have  been  constructed  for 
several  years  are  placed  in  melting  ice,  the  mercury  stands  in  general  higher  than  the  zero  point  of  the 
scale  ; and  this  circumstance,  which  renders  the  scale  inaccurate,  has  been  usually  ascribed  to  the  slow- 
ness with  which  the  glass  of  the  bulb  acquires  its  permanent  arrangement,  after  having  been  heated  to 
a high  degree  in  boiling  the  mercury.  Despretz  ( Trcdte  de  Physique)  observes,  that  in  very  nice  ex- 
periments it  is  always  necessary  to  verify  the  zero  point;  for  he  found  that  when  thermometers  have 
been  kept  during  a certain  time  in  a low  temperature,  the  zero  point  rises,  but  falls  when  they  have 
been  kept  in  a high  temperature ; and  this  remark  applies  equally  to  old  thermometers  and  to  those 
which  have  been  recently  constructed. 

Register  thermometers. — In  meteorological  observations  it  is  of  great  importance  to  ascertain  the  lim 
its  of  the  range  of  the  thermometer  in  a given  period  of  time,  during  a day  or  night,  for  example,  while 
the  observer  is  absent.  Numerous  contrivances  have  accordingly  been  proposed  for  this  purpose,  but 
the  two  following  are  those  most  frequently  used. 

Six's  register  thermometer. — This  instrument  was  invented  by  Mr.  Six,  of  Colchester,  England,  and  is 
described  in  the  Phil.  Trans.,  vol.  lxxii.  It  is  a spirit  thermometer,  having  a long  cylindrical  bulb  A, 
Fig.  3410,  with  the  tube  bent  in  the  form  of  a siphon,  and  terminating  in  a small  cavity  B.  A part  of 
the  tube,  from  a to  6,  is  filled  with  mercury  ; but  the  bulb  A,  and  the  remaining  portion  of  the  tube 


THERMOMETER. 


717 


3410. 


■ 1 


and  a small  part  of  the  cavity  13,  with  highly  rectified  alcohol.  The  use  of  the  mercury  in  the  middle 
of  the  tube  is  to  give  motion  to  two  indices,  c and  d,  which  consist  each  of  a glass  tube  in  which  a small 
bit  of  iron  wire  is  inclosed,  the  ends  being  capped  with  enamel.  The  indices  are  of  such  a 
size  that  they  move  freely  within  the  barometric  tube,  and  allow  the  spirit  to  pass  ; but  a 
slender  spring  is  attached  to  each,  which  presses  against  the  side  of  the  tube,  and  is  just 
strong  enough  to  prevent  the  index  from  falling  down  when  it  has  been  raised  to  any  point 
and  the  mercury  recedes.  The  action  of  the  instrument  will  be  readily  apprehended  from 
the  figure.  An  increase  of  heat  expands  the  alcohol  in  the  bulb  A,  depresses  the  mercury 
at  a,  and  consequently  raises  it  in  the  other  branch  of  the  siphon  at  b.  The  mercury  while 
rising  drives  the  index  d before  it;  and  when  the  temperature  diminishes,  the  mercury  re- 
cedes from  the  index,  which  is  retained  in  its  place  by  the  action  of  the  spring,  and  conse- 
quently marks  the  highest  point  at  which  the  mercury  has  stood.  In  like  manner,  when 
the  spirit  in  the  bulb  A is  contracted  by  a diminution  of  heat,  the  mercury  is  pressed  to- 
wards A by  the  elastic  force  of  a portion  of  air  purposely  left  in  the  cavity  B,  and  drives 
before  it  the  index  c,  which  is  prevented  from  falling  back  by  the.  spring,  and  consequently 
remains  at  the  highest  point  at  which  the  mercury  has  stood  in  that  branch  of  the  siphon. 

When  the  observation  has  been  made,  the  indices  are  brought-  back  to  the  surface  of  the 
mercury  by  means  of  a magnet,  which  acts  on  the  inclosed  iron  wire  and  overcomes  the  force  of  the 
spring.  A scale  is  applied  to  each  limb  of  the  siphon,  and  graduated  by  comparison  with  a standard 
thermometer. 

This  instrument  has  all  the  defects  which  belong  to  the  spirit  thermometer,  and  the  indications  arc 
besides  in  some  degree  deranged  by  the  expansion  and  contraction  of  the  inclosed  column  of  mercury; 
probably,  also,  by  the  friction  of  the  indices.  Nevertheless,  it  is  the  best  instrument  we  possess  for  de- 
termining the  temperature  of  the  sea  at  great  depths. 

Rutherford's  thermometer. — Another  register  thermometer,  simpler  in  its  construction,  and  less  ex- 
pensive than  the  former,  and  consequently  more  generally  used,  is  the  day  and  night  thermometer  pro- 
posed by  Dr.  Rutherford  in  the  Edinburgh  Transactions,  vol.  iii.  It  consists  simply  of  two  thermome 
ters;  a mercurial  thermometer  A,  Fig.  3411,  and  a spirit  thermometer  B, 
attached  horizontally  to  the  same  frame,  and  each  provided  with  its  own 
scale.  The  index  of  A is  a bit  of  steel,  which  is  pushed  before  the  mer- 
cury ; but,  in  consequence  of  its  horizontal  position,  remains  in  its  place 
when  the  mercury  recedes,  and  consequently  indicates  the  highest  degree 
of  the  scale  to  which  the  mercury  has  risen.  The  index  of  B is  of  glass, 
with  a small  knob  at  each  end.  This  lies  in  the  spirit,  which  freely 
passes  it  when  the  thermometer  rises  ; but  when  the  spir  it  recedes,  the  cohesive  attraction  between  the 
fluid  and  the  glass  overcomes  the  friction  arising  from  the  weight  of  the  index,  and  the  index  is  conse- 
quently carried  back  with  the  spirit  towards  the  bulb.  As  there  is  no  force  to  move  it  in  the  opposite 
direction,  it  remains  at  the  point  nearest  the  bulb  to  which  it  has  been  brought,  and  thus  indicates  the 
lowest  temperature  which  has  occurred.  By  inclining  the  instrument  the  indices  are  brought  to  the 
surfaces  of  their  respective  fluids,  and  prepared  for  a new  observation. 

History  of  the  thermometer. — The  invention  of  the  thermometer  dates  from  about  the  beginning  of 
the  17th  century,  but  it  is  not  certainly  known  when  or  by  whom  it  was  first  brought  into  use.  By  the 
Dutch  authors  it  is  ascribed  to  Cornelius  Drebbel,  a peasant  of  Alkmaar,  and  by  the  Italians  to  Sanc- 
torio.  Libri  ( Annates  de  Chitnie,  Dec.  1830)  maintains,  on  the  authority  of  Castelli  and  Viviani,  that ' 
the  instrument  was  invented  by  Galileo  prior  to-1597.  The  thermometer  of  Drebbel  and  Sanctorio  was 
a very  imperfect  instrument.  It  consisted  of  a glass  tube,  having  a ball  blown  on  one  of  its  extremi- 
ties, and  the  other  end  left  open.  A portion  of  air  being  expelled  from  the  ball  by  heat,  the  open  end 
was  plunged  into  a cup  containing  any  liquid,  when,  on  the  cooling  of  the  ball,  the  liquid  would  rise  in 
the  tube,  and  the  variations  of  its  height  indicate  the  increase  or  diminution  of  the  temperature  of  the 
bulb.  The  instrument  had  no  scale,  and  was  therefore  merely  an  indicator  of  changes  of  temperature, 
or  a thermoscope ; and  it  was  defective  even  in  this  respect,  inasmuch  as  it  is  affected  not  merely  by 
heat  and  cold,  but  by  the  varying  pressure  of  the  atmosphere.  The  Florentine  academicians  first  ex- 
cluded the  influence  of  atmospheric  pressure  by  using  a spirit  instead  of  an  air  thermometer,  and  her- 
metically sealing  the  tube.  The  next  step  in  improvement  was  the  adoption  of  a fixed  point  in  the 
scale.  Boyle  proposed  the  thawing  oil  of  aniseeds,  which  he  preferred  to  thawing  ice,  because  it  could 
be  readily  obtained  at  all  times  of  the  year.  Halley  proposed  the  uniform  temperature  of  a deep  pit, 
which  he  probably  considered  would  be  the  mean  temperature  of  the  earth ; but  he  also  suggested  the 
point  at  which  spirit  boils  as  well  as  the  boiling  point  of  water.  Newton  appears  to  have  been  the  first 
who  saw  the  advantage  of  having  two  fixed  points  in  the  scale  ; and  in  order  that  the  instrument  might 
be  applicable  to  a wider  range  of  temperature,  he  used  linseed  oil  as  the  thermometric  fluid.  This, 
however,  has  not  been  found  to  answer,  on  account  of  its  sluggish  motion  and  adhesion  to  the  sides  of 
the  tube.  The  astronomer  Roemer  proposed  the  substitution  of  mercury,  which  is  now  generally  used  ; 
and  the  knowledge  of  the  fluctuation  of  the  boiling  point  of  water,  owing  to  atmospheric  pressure,  is 
due  to  Fahrenheit,  about  1724.  Since  that  time  no  improvement  has  been  made  in  the  principle  of  the 
instrument. 

For  further  information  on  this  subject  the  reader  may  be  referred  to  Deluc,  Recherches  sur  les  Modi- 
fications de  V Atmosphere,  Geneve,  1772;  Biot,  Traite  de  Physique,  tome  1 ; Nicholson's  Chemistry; 
Library  of  Usef  ul  Knowledge,  “ Thermometer  and  Pyrometer ;”  Muncke  in  Gehler's  Physicalisckes 
1 Vorterbuch. 

Saxton's  Deep  Sea  Thermometer.  In  conducting  the  off-shore  hydrography  of  the  United  States  Coast 
Survey,  the  proximity  of  the  Gulf  Stream,  and  its  important  bearings  on  the  chief  highways  of  our 
commerce,  have  made  it  specially  incumbent  on  the  Coast  Survey  organization  to  develop  the  great 
physical  features  of  this  phenomenon  with  as  much  accuracy  as  possible.  The  exigency  of  the  work  of 


718 


THERMOMETER. 


sounding  along  the  shore  has  hitherto  withheld  the  organization  from  any  full  investigation  of  the  Gulf 
Stream  problems,  yet  several  results  of  much  interest,  as  to  its  form,  position,  movements,  and  tempe- 
ratures, have  been  already  reached  in  more  or  less  detail.  How  to  observe  the  deep  sea  temperatures 
which  are  ever  disturbing  the  rest  of  the  ocean — how  to  bring  up,  from  a depth  of  several  miles,  a trust- 
worthy reading  of  the  heat  which  prevails  in  those  unexplored  recesses,  is  a question  which  demands  an 
answer  before  the  Gulf  Stream  can  be  fully  comprehended  in  its  fundamental  facts. 

The  proposed  investigations  were  seriously  obstructed  by  the  enormous  pressures  in  the  regions  to  be 
explored,  which  deranged  all  common  contrivances.  The  ordinary  glass  thermometers  were  repeatedly 
tried  in  the  Coast  Survey  soundings,  hut  as  uniformly  broken.  Attempts  were  made  to  protect  them  by 
strong  metallic  cases,  which  were  also  crushed  in.  Mr.  Saxton,  the  eminently  ingenious  and  successful  head 
of  the  Instrument  Department  in  the  Coast  Survey  Office,  then  devised  the  deep  sea  thermometer  which 
bears  his  name,  and  which  has  been  used  for  several  years  with  entire  success.  Some  accidents,  not 
faults  of  the  instrument,  have  had  the  effect  to  prevent  such  extensive  observations  as  Mr.  Bache  had 
provided  for,  hut  it  is  to  be  hoped  that  each  year  will  contribute  to  the  number  of  our  reliable  observa- 
tions with  this  elegant  apparatus.  \\e  proceed  to  state  its  principle  and  the  arrangement  of  its  parts. 

The  main  feature  is  a compound  spiral  of  helical  band  or  ribbon, 
composed  of  two  similar  plates  firmly  united  along  their  surface  of 
contact,  the  outer  one  being  of  silver,  and  the  inner  one  of  plati- 


i 


nurn.  As  the  rates  of  expansion  of  these  two  metals  are  widely  different,  the  variation  of  temperature 
to  which  the  spiral  is  exposed,  will  produce  a considerable  movement  of  torsion,  or  rotation  at  the  bot- 
tom of  the  helix,  the  top  being  fixed.  This  principle  is  familiar  in  Breguetfs  torsion  thermometer,  and 
Mr.  Saxton  has  only  applied  it  to  a novel  case,  with  an  improved  arrangement  at  the  upper  extremity  of 
the  spiral,  for  magnifying  and  reading  the  indication  furnished.  The  motion  of  rotation  given  by  a 
change  of  temperature,  is  very  well  fitted  for  reading,  as  by  gearing  it  up,  it  gives  a quite  ample  rota- 
tion to  an  index  hand.  Within  the  spiral  is  a hollow  tube,  to  which  at  the  top  the  spiral  is  screwed  fast, 
as  shown  in  fig.  1.  Within  this  tube  is  a small  rod  or  axle,  which  is  connected  with  the  bottom  of  the 
spiral,  and  turns  freely  on  a supporting  pivot,  so  as  to  communicate  the  torsion  rotation  to  a toothed 


THERMOMETER 


719 


silver  wheel  on  its  top,  which  is  shown  in  fig.  2 ; that  part  only  being  toothed  which  will  he  needed. 
A small  pinion,  which  bears  the  index  hand,  takes  up  the  motion,  and  is  made  to  traverse  the  graduated 
silver  rim,  and  carry  with  it  a stop  hand,  fig.  3,  which  will  indicate  the  maximum  or  minimum  tempe- 
ratures passed  in  the  descent,  according  to  its  arrangement.  Suriace  temperatures  are  read  off  at  once, 
and  the  sounding  lines  give  the  depths.  _ 

The  whole  of  this  arrangement  is  inclosed  in  a firm  metal  case,  a§  shown  in  fig..  4,  which  protects  it 
from  injury,  and  yet  permits  the  water  to  pass  freely  around  the  spiral,  causing  it  instantly  to  take  the 
temperature  of  its  locality.  The  top  case  is  covered  with  a cap,  pierced  with  small  holes  to  permit  the 
water  to  pass  freely.  The  whole  case  is  then  mounted  in  a metal  frame  by  means  of  two  rings.  The 
top  ring  turns  on  two  side  pivots,  to  permit  the  insertion  of  the  case  ; but  the  lower  ring  is  in  halves, 
one  of  which  is  fixed,  and  the  other  opens  out  to  receive  the  case,  after  which  it  closes,  and  is  tightly 
clamped.  An  eye  at  the  top  receives  the  sounding-line,  and  one  at  the  bottom  any  requisite  sinking 
weights.  All  the  delicate  parts  of  this  thermometer  which  could  be  corroded,  are  heavily  electro-plated 
with  gold  by  Mr.  Mathiot  in  the  Coast  Survey  Electrotype  Laboratory,  so  that  they  are  not  liable  to 
injury  with  fair  treatment. 


In  using  this  instrument,  it  is  thrown  from  the  side  of  the  vessel  at  successive  times,  first  observing 
the  surface  temperature,  and  then  sinking  it  to  a small  depth,  and  again  to  one  a little  greater,  and  so 
on,  till  it  can  be  decided  that  the  stop  hand  indication  belongs  to  the  greatest  depth  attained.  The  pass- 
ing of  a point  of  maximum  or  minimum  temperature,  however,  complicates  the  problem,  and  makes  it 
a matter  of  critical  judgment  to  connect  the  temperature  and  depth  with  accuracy.  In  the  hands  of 
good  observers,  it  yields  excellent  results,  and,  though  not  all  that  could  be  desired,  is  still  a most  excel- 
lent instrument  within  the  range  of  its  capacities.  Its  cost,  made  in  the  limited  numbers  required  in  the 
operation  of  the  Coast  Survey,  is  about  sixty  dollars,  though  a demand  for  considerable  numbers  would 
much  reduce  this  amount.  We  trust  that  this  or  some  better  instrument,  if  possible,  will  hereafter  be  em- 
loyed  with  increased  zeal  in  the  study,  not  only  of  Gulf  Stream  temperatures,  but  of  the  ocean  through- 
out its  whole  expanse,  and  even  in  our  lakes  and  the  interior  seas  of  the  whole  world.  Surface  tempe- 
ratures alone  are  quite  insufficient  to  give  correct  results,  for  the  solar  radiation  produces  a great  effect 
on  the  superficial  layers,  and  we  must  penetrate  to  one  or  two  hundred  feet  before  we  enter  on  the 
grand  temperature  scale.  A minimum  temperature  is  usually  passed  in  descending,  at  that  depth  where 
the  sun’s  effects  may  be  assumed  to  terminate,  and  we  then  enter  on  an  increasing  scale  of  tempera- 
tures, which,  according  to  one  of  Prof.  Bache’s  discussions,  give,  with  the  co-ordinates  of  depth,  a curve 
clearly  and  obviously  the  logarithmic  curve.  The  connection  between  this  result,  and  some  of  the 
grand  results  of  that  theory  of  heat,  which  treats  it  as  an  elastic  fluid,  is  striking  and  eminently  sug- 
gestive, though  too  recondite  to  be  more  than  mentioned  here.  There  is  then  a vast  field  of  research, 
full  of  interest  and  promise,  for  whose  exploration  this  thermometer  is,  we  believe,  the  most  reliable  in- 
ttrument,  and  we  trust  it  will  therefore  be  put  into  increasingly  active  requisition. 

THRESHING  MACHINE,  WATER,  of  eight  horse-power.  Fig.  3412  contains  a side  elevation  of 
the  machine,  and  Fig.  3413  contains  a plan  of  the  same. 

The  same  parts  are  denoted  by  the  same  letters  in  both  of  the  drawings. 

The  water-wheel  is  of  the  kind  denominated  overshot , with  wooden  buckets.  The  shaft  of  this  wheel 


720 


THRESHING  MACHINE. 


rests  on  pillow-blocks  bolted  to  the  stone-work  forming  the  sides  of  the  wheel-pit.  These  pillow-blocks 
have  sometimes  covers  of  the  regular  form,  but  more  commonly  they  are  unprovided  with  covers  of  any 
sort;  occasionally  they  are  furnished  with  shell-covers  for  the  sake  of  appearance,  and  to  preserve  the 
gudgeons  from  water  and  sand. 

On  the  end  of  the  water-wheel  shaft,  which  passes  into  the  barn , is  keyed  a spur-wheel  1,  of  121 
teeth ; this  wheel  geers  with  the  pinion  3,  of  sixteen  teeth,  upon  the  shaft  B.  On  the  other  end  of  the 
shaft  is  keyed  the  cog-wheel  2,  of  115  teeth;  this  last  geers  with  the  pinion  4,  of  15  teeth,  on  the  end 
of  the  shaft  of  a drum  D,  which  carries  on  its  circumference  four  projecting  pieces  called  the  beaters, 
their  purpose  being  to  beat  or  thresh  the  grain  from  the  straw  as  this  passes  forward  between  the  feed- 
rollers  R,  at  the  bottom  of  the  feed-table  F,  upon  which  the  unthreshen  material  is  spread  out  in  a layer 
previous  to  its  being  introduced  between  the  feed-rollers.  The  feed-rollers  are  both  fluted,  and  derive 
their  motion  from  a pulley  on  the  shaft  B,  by  means  of  a pitch-chain  6,  which  passes  over  the  pulley  8, 
on  the  spindle  of  the  lower  roller. 


On  passing  the  beater-drum  D,  the  straw  is  taken  up  by  the  two  sets  of  shakers  S S in  succession. 
The  shakers  are  driven  likewise  from  the  shaft  B by  a pulley  marked  7,  and  a pitch-chain  which  passes 
over  a pulley  marked  5,  on  the  shaft  of  the  first  set  of  shakers.  The  second  set  of  shakers  is  connected 
with  the  first  by  a pitch-chain,  which  passes  over  the  equal  pulleys  a a,  upon  their  shafts. 

During  the  operation  of  threshing,  the  straw  is  tossed  out  behind  the  machine  by  the  second  set  of 
shakers  upon  a heck  Y,  and  the  grain  falling  through  the  sparred  segmental  bottoms  H H,  is  collected 
by  the  hopper  kk  into  the  fanner,  situated  below  the  machine,  as  shown  in  Fig.  3412.  The- fan  is 
driven  from  the  shaft  of  the  beater-drum  by  a rope-band,  which,  passing  from  the  pulley  P on  the 
beater-shaft  to  the  guide-pulleys  b b,  embraces  the  fan-pulley  C,  of  the  same  diameter  as  P,  so  that  the 


THROSTLE. 


721 


3413. 


of  the  machine. 

THROSTLE.  A spinning  frame  for  the  manufacture 
of  cotton  yarn  of  the  lower  numbers,  say  below  110’s 
Throstles  are  designated  as  the  live  spindle , used  in  the 
Middle  and  Southern  States,  the  dead  spindle  used  in 
Lowell.  The  Cap  Spinner,  or  Danforth  Throstle;  the 
Ring  Throstle,  or  Ring  and  Traveller.  Figs.  341-1,  3415, 
3410  represent  one'  of  the  latter  class  ; it  differs  from 
the  more  common  form  of  ring  and  traveller  in  its  man- 
ner of  driving  the  spindle.  In  all  other  throstles  the 
motion  is  given  to  the  flyer  or  to  the  spindle  by  a twisted 
band,  from  a central  drum  passing  round  a small  pulley 
on  the  spindle. 


fan  and  the  beater-drum  have  the  same  speed,  supposing  no  slip  of  the  band.  But  the  guide-pulleys  b b 
are  usually  fixed  in  a frame,  which  can  be  shifted  vertically,  so  as  to  increase  or  lessen  the  tension  of 
the  band  at  pleasure,  according  as  the  grain  is  heavy  or  light;  for,  when  the  grain  is  light,  it  will  be 
more  easily  blown  away  with  the  chaff  than  when  heavy,  and  for  that  reason  a certain  amount  of  slip 
of  the  band  is  allowed  by  lessening  the  tension,  until  the  proper  strength  of  blast  is  obtained. 

The  directions  of  the  motions  of  the  several  parts  of 
the  machine  are  indicated  by  arrows  on  the  elevation 
figures,  and,  indeed,  are  obvious  from  the  mode  of  action 


Fig.  3414  is  an  end  elevation,  showing  the  arrangement  for  the  geers  and  belts  for  driving  the  rolls 
and  lifting  motion  for  the  rails. 

Fig.  3415  is  a front  elevation,  showing  the  rolls,  spindles,  and  an  edge  view  of  the  friction-disks  a a 
for  driving  the  spindles.  These  disks  and  the  whirls  running  upon  them  constitute  the  parts  patented 
by  McCulley.  The  advantages  derived  by  tins  improvement  are  the  saving  of  power,  (which  is  60  per 
cent.,)  and  the  dispensing  with  the  bands,  which  constantly  require  tightening  and  renewing,  also  a great 
saving  in  room,  wear,  and  repair.  The  whirls,  which  are  covered  witli  leather,  will  last  several  years 
without  need  of  repair. 

Fig.  3416  is  a vertical  section  of  the  machine  through  the  centre  of  one  section,  showing  the  roller 
stands  s,  the  manner  of  weighting  top-rolls  by  the  weights  g g,  tile  bearings  for  the  side-shafts,  stands 
for  the  spindles,  guide-rod  d for  raising  top  or  ring  rail,  &c. 

C is  a collar  on  spindle  in  which  the  bobbin  rests,  b is  the  whirl  on  spindle  resting  on  the  friction- 
disk  a.  E,  weight  to  balance-rails,  u is  the  heart,  combined  with  geers  and  segment,  which  gives 
motion  to  the  ring-rail  which  forms  the  shape  of  the  bobbin. 

These  frames  are  capable  of  being  run  at  a great  speed.  The  front  roll  may  run  at  130  revolutions 
per  minute  for  No.  14  yarn. 

The  live  spindle,  a great  improvement  upon  the  method  first  adopted  by  McCulley,  is  the  application 
Vol.  II. — 46 


3410. 


THROSTLE. 


TIMBER  BENDING. 


723 


made  by  the  Lowell  Machine  Shop,  -who  build  frames  of  this  kind  to  run  with  each  side  separate,  thereby 
stopping  only  half  of  the  spindles  while  doffing. 

In  general  arrangement,  this  machine  differs  but  in  the  mode  of  driving  from  other  ring-throstles ; 
and  in  all  respects  but  this  the  description  applies  to  all  ring-throstles.  The  older  mode  of  driving  is 
by  a central  drum,  from  which  bands,  passing  round  whirls  on  the  spindles,  give  motion  to  the  same. 

This  latter  mode  of  driving,  by  the  friction  of  the  whirl  on  the  edge  of  a revolving  disk,  is  fully  tested 
and  very  largely  in  operation.  It  gives  a stronger,  more  regular  and  uniform  motion  to  the  spindle 
than  is  given  by  bands,  and  is  applied  to  driving  the  spindles,  flyers,  and  bobbins  of  all  kinds  of  thros 
ties,  also  to  worsted  frames,  and  to  doublers  and  twisters,  with  similar  advantages. 

TIMBER  BENDING.  The  usual  way  of  bending  planks  to  curved  forms,  has  been  by  straining  or 
heating  the  pieces  and  bending  over  a mould  or  frame,  and  leaving  them* keyed  in  this  position  till  they 
had  by  cooling  taken  a set.  This  process  not  only  strained  the  fibre  of  the  wood,  but  was  inapplicable 
to  the  formation  of  curves  of  short  radius  in  large  scantling.  In  1819  letters  patent  were  granted  to 
Thomas  Blanchard  for  improvements  in  bending  wood  and  other  fibrous  substances.  This  patent  claimed 
the  bending  timber  by  placing  a powerful  pressure  on  the  ends  of  the  body ; and  while  the  pressure  was 
continued,  it  was  forced  around  a mould  to  the  desired  curve.  The  pressure  upon  the  ends  of  the  tim- 
ber prevented  the  elongation  of  the  fibre  outside  of  the  curve,  while  the  inside  was  necessarily  shortened, 
thereby  preventing  the  rupture  or  breaking  of  the  same. 

It  was  found,  in  the  course  of  experiment  in  bending  heavy  timber  for  ships’  knees,  requiring  short 
curves,  that  the  timber,  in  the  process  of  conforming  to  the  mould,  spread  or  bulged,  much  to  its  deface- 
ment. To  remedy  this  defect,  Mr.  Blanchard  was  employed  to  construct  another  machine,  in  all  re- 
spects adapted  to  bending  ship  timber.  This  was  accomplished  by  encasing  the  timber  on  all  sides,  and 
effectually  preventing  its  spreading  in  any  direction.  This  improvement  was  of  vital  importance  in 
bending  heavy  timber,  and  without  which  large  knees  could  not  be  made.  Previous  to  being  subjected 
to  the  pressure,  the  fibres  of  the  wood  are  softened  by  steaming,  which  also  incidentally  by  dissolving 
the  acid  contained  in  the  capillary  vessels,  increases  the  durability  of  the  timber. 

The  fibres  of  wood  have  their  origin  in  cells,  generally  shaped  like  a double  cone,  greatly  elongated, 
and  placed  close  and  parallel  to  one  another,  with  the  various  extremities  of  one  set  wedged  in  between 
those  of  another  set.  These  fibres  are  generally  collected  together  into  layers,  so  arranged  as  to  pre- 
sent the  greatest  resistance  to  forces  tending  to  displace  them  in  the  longitudinal  direction.  The  masses 
of  fibre  contain  assemblages  of  cells  which  retain  the  air,  fluids,  gums,  and  resins  of  the  tree. 

In  the  application  of  heavy  lateral  forces  to  a body  of  wood,  as  in  the  operation  of  bending,  the  re- 
sult is  but  a compression  of  its  fibres  to  a solid  mass,  by  the  breaking  up  of  the  cells  of  which  the  fibres 
are  only  the  coat  or  covering.  These  fibres  will  remain  under  the  action  of  any  force,  entire  and  con- 
tinuous throughout  the  body,  through  their  flexibility  and  elasticity,  most  hard  woods  being  taken  as  a 
standard.  The  grain  of  the  wood  or  fibre  is  easily  traceable,  even  at  the  point  of  greatest  tension  and 
displacement,  the  angle  at  a short  curve,  where  they  interlace  and  lock  each  other  so  firmly  as  to  hold 
the  extremities  of  a stick  in  position,  after  being  bent  to  a right  angle. 

The  aggregation  and  complication  of  the  fibres  at  the  angle  of  the  curves,  gives  the  greatest  strength 
where  it  is  most  required,  as  at  that  point  one-fourth  of  every  inch  lost  in  bending  the  interior  side  of 
the  curve,  is  there  gained.  The  severest  tests  have  shown  the  impossibility  of  restoring  a stick  of  tim- 
ber, of  whatever  size,  to  its  original  form,  after  being  subjected  to  this  process ; fracture  would  first  ensue, 
but  at  those  parts  quite  removed  from  the  centre  of  the  curve.  Additional  strength  and  elasticity  are 
given  to  a bent  piece  of  wood,  by  the  interstices  and  cellular  spaces  being  filled  up  by  the  solid  fibrous 
material. 

In  185G  tests  were  made  at  the  Brooklyn  Navy  Yard,  under  the  direction  of  officers  of  the  navy,  with 
the  following  results : 

The  knees  upon  which  these  tests  were  made,  were  of  the  largest  size  commonly  used  for  hanging 
knees.  In  order  to  make  the  test  analogous  to  the  appliance  in  the  vessel,  a piece  of  oak  timber  of  equal 
siding  size  with  the  knees,  was  fastened  to  the  body,  representing  a timber  of  the  ship’s  frame ; also 
another  to  the  arm  representing  the  beam  of  a vessel.  The  body  was  secured  upon  an  iron  frame,  in 
which  the  press  rested,  while  the  power  was  applied  to  the  arm,  on  some,  to  contract  the  angle  of  the 
knee,  by  drawing  it  inward  to  a point  of  rupture  ; and  on  others,  to  thrust  the  arm  outward  to  the  rup- 
turing point.  In  several  cases,  the  fastenings  were  found  inadequate  to  hold  the  beam  and  arm  together, 
although  placed  in  about  equal  quantity,  size  and  distribution,  to  the  proportion  commonly  used  in 
vessels.  It  should  be  considered,  however,  that  the  knees  were  of  more  than  ordinary  stamp  in  quality. 

Result  of  Tried. 

No.  1 — Bent  knee,  sided  101  inches;  moulded  10  inches  at  throat;  remainder  of  size  in  throat  made  up 
of  chock  on  the  comer;  angle  of  knee,  95  degrees;  power  applied,  5.37  feet,  from  corner  of  arm; 
and  fulcrum  at  right  angles  with  a point  on  the  body,  1.92  feet  from  corner: 

Bent  inward,  at  \ inch  required 5.500  pounds.  I Bent  inward,  at  1-junch,  required 8.500  pounds. 

“ “ I “ “ 7.500  “ | “ “ 2 “ “ 10.000  “ 

No.  2. — Natural,  or  grown,  sided  10^  inches,  moulded  to  corner;  angle,  96  degrees;  power,  fulcrum, 
and  fastenings,  same  as  No.  1 : 

Bent  inward,  at  it  inch,  required 3.500  pounds.  I Bent  inward,  at  11  inch,  required 7.000  pounds. 

“ “ 1 “ “ 5.500  “ | “ “ 2 “ “ 9.500  “ 

No.  3. — Bent  knee,  sided  10^  inches;  moulded  11  inches  in  throat,  and  filled  out  to  corner  with  chock, 
angle,  88  degrees ; power  applied  as  in  No  1 and  2 ; fulcrum  at  middle  of  throat ; fastenings  as  before 
distributed ; 


1 24 


TOBACCO  CUTTING  MACHINE. 


Bent  inward,  at  4 inch,  required 6.500  pounds,  j Bent  inward,  at  14  inch,  required 10.000  pounds. 

“ “I  “ “ 9.500  “ | “ “ 2 “ “ 11.000  “ 

Note. — Tliis  knee,  (No.  3.)  was  "bent  inward  six  inches,  when  the  fastenings  giving  way,  the  knee  was  allowed  to  re- 
turn, which  it  did;  was  re-fastened,  and  again  bent  inward,  when  it  sustained  within  about  9 per  cent,  of  its  first 
pressure. 

No.  4. — Natural  or  grown  knee,  sided  104  inches;  moulded  to  corner;  angle  square,  or  90  degrees; 
power  applied,  same  as  those  before  bent ; fulcrum  at  middle  of  throat,  at  angle  of  45  degrees,  with 
arm  and  body : 

Bent  inward,  at  4 inch,  required 5.500  pounds.  I Bent  inward,  at  14  inch,  required 9.000  pounds. 

“ “ 1 “ “ 7.500  “ | “ “ 2 “ “ 10.500  “ 

No.  5. — Bent  knee,  sided  10 J-  inches;  moulded  11  inches;  filled  out  to  corner  with  chock;  angle  right, 
or90  degrees;  leverage  as  before,  5.37  feet  from  corner:  fulcrum  at  right  angles  from  middle  of 
throat,  = to  3.08  feet : 

Bent  outward,  at  4 inch,  required 8.000  pounds.  I Bent  outward,  at  14  inch,  required... 18.000  pounds. 

“ “ 1 “ “ ...14.000  “ I “ “ 2 “ *•  ...22.500  “ 

Note. — This  knee,  (No.  5,)  was  bent  outward  10  inches,  without  the  least  rupture,  and  the  highest  resisting  pressure 
= 38.000*  pounds;  and  on  being  relieved,  returned  to  within  41  degrees  of  its  former  angle;  was  again  subjected  to 
pressure,  and  when  at  11J  inches  from  its  relieved  position,  the  pressure  amounted  to  36.500t  pounds. 

No.  6. — Natural  or  grown  knee,  sided  104  inches ; moulded  to  corner  ; full  and  well-grown,  with  5 feet 
arm,  the  very  best  the  Navy  or  market  could  furnish  : was  prepared  at  the  navy  yard,  angle  82  de- 
grees ; fastenings,  leverage,  and  fulcrum  as  before  applied  ; one  inch  larger  in  body  at  commencement 
of  throat.  This  knee  had  two  trials,  in  consequence  of  the  necessity  of  re-arranging  to  secure  equal- 
ity of  position. 

On  First  Trial. 

Bent  outward,  at  4 inch,  required 7.500  pounds.  I Bent  outward,  at  14  inch,  required. ..26.500  pounds, 

“ “ 1 “ “ ...20.000  “ | “ “2  “ “ ...33.000  “ 

On  Second  Trial. 

Bent  outward,  at  4 inch,  required...  11.500  pounds.  I Bent  outward,  at  14  inch,  required. ..31. 500  pounds. 
“ “ 1 “ “ ...22.500  “ | “ “ 2'  “ “ ...38.500  “ 

It  broke  at  two  inches  in  the  throat,  the  rupture  being  complete.  Blanchard’s  patent  has  passed  into 
the  hands  of  the  Timber  Bending  Co.,  who  have  now  nearly  ready  for  operation  an  improved  machine, 
with  capacity  to  bend  timber  fifty  feet  long  and  twenty  inches  square. 

TOBACCO-CUTTING  MACHINE.  This  is  a superior  constructed  tobacco-cutting  machine,  the  in’ 
vention  of  A.  P.  Finch,  Red  Falls,  Greene  Co.,  N.  Y.  Its  workmanship  is  of  a very  superior  kind, 
strong,  correct,  and  simple,  and  there  can  be  no  question  of  its  qualities. 

A,  Fig.  3419,  is  the  frame;  BB  are  two  wheels  on  which  is  fixed  the  cutting-knife  C,  across  the  end 
of  the  box  D ; E is  the  lid  of  the  box,  under  which  is  pressed  down  the  tobacco  to  be  cut,  by  four  screws 
FFFF.  As  the  tobacco  to  be  cut  has  to  be  pressed  down  to  a very  solid  bed,  two  cross-bars  extend 
under  the  nuts  of  the  screw-bolts  across  the  box  D,  on  the  top  of  the  cover  E,  and  there  are  notches  in 


3419. 

N 


the  sides  of  the  box  to  allow  these  bars  to  descend  with  the  cover  on  the  top  of  the  tobacco  as  it  is 
screwed  down.  H is  a cog-wheel  on  the  screw  L.  The  screw  passes  through  it,  and  as  there  is  a 
thread  in  the  interior  of  the  wheel,  the  screw  will  be  moved  forward  or  backward  by  the  motion  of  the 
wheel.  On  the  end  of  the  screw  in  the  box  there  is  a square  block  pressing  behind  the  tobacco  to  movf 


TOOLS. 


725 


it  gradually  towards  the  knife.  This  is  the  office  of  the  screw.  Therefore  as  the  knife  cuts  up  the  to- 
bacco under  E,  at  the  right  end  of  the  box,  the  screw  pushes  up  the  compressed  tobacco  to  present  al- 
ternately a new  layer  of  tobacco  to  the  knife  at  every  revolution  of  the  revolving  cutter-wheels  B B. 
N is  a fly-wheel  on  the  cutter-shaft,  and  the  pulley  on  the  left  of  the  cutter  is  for  a band  to  drive  the 
shaft.  The  cog-wheel  F,  at  the  left  end  of  the  box,  is  driven  by  a worm-wheel  J,  (scarcely  seen,)  under 
the  bottom  of  the  box.  K is  a set  of  pulleys  on  the  shaft  of  J to  drive  the  said  shaft,  so  that  the  screw 
may  receive  a forward  or  backward  motion  by  the  changing  of  the  band.  The  handle  on  the  end  of  the 
screw  is  merely  to  show  the  manner  in  which  it  may  be  turned. 

TOOLS.  The  great  and  manifest  importance  of  tools  to  the  mechanic  is  so  self-evident  that  it  is  ex- 
traordinary the  subject  has  not  hitherto  received  that  investigation  which  it  obviously  deserves.  The 
vast  improvements  in  modern  machinery  are  mainly  attributable  to  the  excellence  and  accuracy  of  the 
tools  used  in  preparing  and  completing  the  various  parts  of  which  every  machine  is  composed. 

By  the  expression  tools,  according  to  the  definition  given  by  Mr.  George  Rennie,  we  understand  in- 
struments employed  in  the  manual  arts  for  facilitating  mechanical  operations  by  means  of  percussion, 
penetration,  separation,  and  abrasion  of  the  substances  operated  upon,  and  for  all  which  operations 
various  motions  are  required  to  be  imparted  either  to  the  tool  or  the  work. 

For  the  sake  of  distinctness  it  would  be  desirable,  so  far  as  is  practicable,  to  treat  the  subject  under 
two  points  of  view:  1st.  Where  motion  is  given  to  the  tool,  as  in  handicraft  work;  2d.  Where  motion 
is  given  either  to  the  tool  or  the  work,  as  in  self-acting  or  automatic  tools.  Now,  in  the  case  of  the 
turning-lathe  the  tool  usually  remains  fixed,  while  the  object  invariably  moves — in  that  of  the  planing- 
machine  the  tool  or  cutter  may  either  remain  fixed  or  be  made  to  move,  according  to  the  duty  required 
to  be  performed.  In  almost  all  the  other  machines  which  come  under  the  denomination  tools — such, 
for  example,  as  are  intended  to  perform  the  various  mechanical  operations  of  slotting,  key-grooving, 
punching,  drilling,  nut-trimming,  cutting  the  teeth  of  wheels,  boring,  screw-cutting — the  tool  receives 
motion,  although  in  some  cases,  particularly  in  the  nut-trimming  and  screw-cutting  machines,  the  tool 
may  be  either  movable  or  fixed. 

It  would  afford  much  matter  for  curious  and  instructive  inquiry  to  trace  the  early  history  of  tools,  as 
there  can  be  little  doubt  that  the  use  of  handicraft  tools  is  coeval  with  the  earliest  ages  ; and  assuming 
the  recent  researches  of  modern  travellers  to  be  satisfactory  proof  of  the  fact  that  the  ancients  were 
acquainted  with  almost  all  the  tools  now  in  use,  we  cannot  fail  to  admire  the  patient  perseverance  of 
the  workman,  whose  skill,  combined  with  manual  labor,  enabled  him  to  produce  so  many  beautiful  spe- 
cimens of  his  art— a circumstance  the  more  remarkable  when  we  consider  the  rude  and  simple  imple- 
ments by  the  aid  of  which  this  extraordinary  degree  of  excellence  was  attained. 

The  gradual  improvement  in  tools,  which  of  late  years  have  reached  a very  high  point  of  perfection, 
is  well  illustrated  by  the  wheel-cutting  and  dividing-engine.  We  therefore  propose  very  briefly  to 
sketch  the  history  of  those  machines  and  appliances  which  come  under  the  general  name  above  prefixed. 

While  the  art  of  constructing  wheel-work  was  in  a less  advanced  state,  the  dividing  of  the  circum- 
ference of  a wheel  into  the  requisite  number  of  parts,  and  cutting  out  the  tooth  spaces  by  a manual 
operation,  was  not  only  a tedious  but  also  an  extremely  imperfect  way  of  proceeding.  To  facilitate 
such  manual  operation  by  a file,  the  simple  platform  described  by  Pere  Alexandre,  in  his  Treatise  on 
Clock-making,  was  invented ; this  platform  was  simply  a circular  plate  of  brass,  of  ten  or  more  inches 
in  diameter,  with  concentric  circles  traced  thereon  corresponding  to  the  numbers  of  teeth  in  the  wheels 
and  pinions  of  clock-work.  In  the  centre  of  this  platform  was  fixed  a stud  or  fast  arbor,  round' which 
an  index,  with  a straight  edge  pointing  to  the  centre,  turned  freely  into  any  given  point  of  a required  . 
circle,  by  means  of  which  the  divisions  of  any  given  circle  were  transferred  to  a wheel  placed  on  the 
central  arbor  under  the  index  already  described,  by  a marking  point.  This  mode  of  dividing  a wheel 
is  still  practised  in  some  branches  of  the  mechanical  arts,  and  is,  doubtless,  an  easy  way  of  transferring 
divisions  from  a larger  to  a smaller  circle  for  various  purposes,  where  rigid  accuracy  is  not  required. 
But  one  great  difficulty  still  remained  to  be  surmounted : the  spaces  necessarily  required  to  be  cut  by 
hand  with  a file.  At  length  a small  frame  was  mounted  on  the  index,  which  was  contrived  to  direct 
and  confine  the  file  in  such  a way  as  to  cut  the  notches  in  a wheel  placed  over  the  index,  with  less  de- 
viation from  the  truth  than  could  be  managed  by  mere  manual  dexterity.  It  is  extremely  probable 
that  this  addition  led  to  the  adoption  of  a circular  file  or  cutter,  and  of  such  other  appendages  as  com- 
pleted the  construction  of  a simple  wheel-cutting  machine,  and  it  is  asserted  by  M.  Le  Roy  that  Dr. 
Hooke  was  the  first  person  who  contrived  such  an  arrangement  as  could 
merit  the  name  of  a cutting-engine.  The  machine  thus  converted  into  a 
self-acting  piece  of  mechanism  was  made  up  of  the  strong  frame,  the  slid- 
ing-bars for  supporting  the  platform  or  plate,  with  a horizontal  screw  for 
adjusting  the  distance  from  the  circular  file,  the  divided  plate  with  a re- 
volving arbor  to  receive  the  wheel  to  be  cut,  and  the  alidade  or  index  fixed 
to  the  great  frame  in  the  position  of  a tangent  line  to  any  of  the  divided 
circles,  and  applying  its  bent  and  rounded  point  to  any  of  the  pierced 
marks  of  division  on  the  circle  successively,  as  the  plate  revolved,  during 
the  operation  of  cutting  the  successive  teeth  of  a wheel.  This  construc- 
tion of  the  engine  is  very  nearly  identical  in  principle  to  that  used  in  the 
present  day,  more  especially  for  cutting  the  teeth  of  small  wheels,  as  shown 
in  Fig.  3420.  Here  A shows  the  arbor  on  which  the  wheel  to  be  cut  is 
fixed.  B,  the  cutter.  0,  a toothed-wheel  worked  by  the  handle  E,  and 
faking  into  the  pinion  D,  which  being  on  the  same  axis  as  the  cutter  B, 
imparts  to  it  a velocity  proportionate  to  the  number  of  teeth  in  the  wheel 
C,  and  the  pinion  D.  F is  a lever-handle  by  means  of  which  the  swinging  frame  may  be  gradually 
depressed  as  the  cutter  B is  brought  into  operation,  or  raised  when  it  lias  performed  its  work.  G 
the  horizontal  screw  of  adjustment ; H,  the  division-plate,  and  I the  index  or  pointer. 


3420. 

c,<r? 


72G 


TOOLS. 


The  original  divisions  of  the  circle,  namely,  360,  300,  150,  90,  60,  <fcc.,  are  commonly  retained  in  tho 
ordinary  engines,  although  many  of  the  smaller  numbers  are  included  in  the  larger  ones,  and  are,  there- 
fore, superfluous;  lor,  taking  every  fourth  hole  in  the  circle  of  360,  gives  precisely  the  same  result  as 
using  the  circle  of  90,  or  every  sixth  as  using  the  circle  of  60,  and,  in  like  manner,  taking  every  other 
hole  in  the  circle  of  300,  will  be  precisely  the  same  in  effect  as  using  the  circle  of  150.  It  must,  we 
think,  be  obvious  to  every  one,  acquainted  with  the  ordinary  process  of  cutting  the  teeth  of  wheels, 
that  engines,  of  the  construction  just  described,  are  very  limited  in  their  operations,  by  reason  of  their 
powers  extending  only  to  the  numbers  marked  on  the  divided  circles,  or  the  factors  of  which  those 
numbers  are  composed,  and  because  the  prime  numbers  are  not  usually  inserted.  To  remedy  this  de- 
fect, and  at  the  same  time  render  the  engine  of  greater  practical  utility,  appears  to  have  been  a favorite 
study  with  different  ingenious  artisans,  whose  daily  avocations  admirably  qualified  them  to  appreciate 
the  improvements  we  have  already  referred  to,  as  well  as  to  devise  such  additional  apparatus  as  would 
make  the  engine  more  perfect. 

It  is  unnecessary  to  pursue  further  the  minute  details  of  this  subject,  but  it  is  to  be  observed  that  the 
only  true  and  accurate  method  of  circular  division,  namely,  by  a tangent-wheel  and  endless  screw,  first 
contrived  and  used  by  Dr.  Hooke  in  1 661,  for  the  purpose  of  dividing  astronomical  instruments,  has 
been  from  time  to  time  advantageously  applied  to  the  wheel-cutting  engine  by  eminent  mechanicians. 

We  now  proceed  to  the  dividing-engine,  of  which  it  has  been  justly  observed,  that  “ none  has  so  much 
contributed  to  the  interest  of  navigation  considered  as  a science  indeed  the  facility,  and  at  the  same 
time  the  accuracy,  with  which  the  measuring  portion  of  any  astronomical  or  mathematical  instrument, 
however  portable,  can  now  be  divided  by  our  best  engines,  are  truly  astonishing ; the  fine  lines  of  divi- 
sion which  in  many  instances  are  scarcely  visible  to  the  naked  eye,  are,  when  magnified  by  a suitable 
lens,  perceived  to  be  laid  down  with  perfect  equality,  as  to  relative  distance,  so  much  so,  that  no  one 
who  has  not  examined  the  means  by  which  the  result  is  produced,  can  conceive  the  possibility  that  the 
expedition  with  which  the  divisions  are  made,  is  equal  to  the  accuracy  with  which  they  are  measured 
and  marked  down. 

Several  trials  were  made  at  the  Greenwich  Observatory,  by  Flamsteed,  the  Astronomer  Royal,  but 
the  method  was  found  defective,  probably  in  consequence  of  imperfect  workmanship,  and  was  soon 
abandoned.  In  Mr.  Smeaton’s  paper,  read  before  the  Royal  Society  of  London,  November  17th,  1785, 
on  the  “ Graduation  of  Astronomical  Instruments,”  he  mentions  an  engine  made  by  Mr.  Henry  Hindley 
of  York,  which  indented  the  edge  of  any  circle  in  such  a way  that  a screw  with  fifteen  threads  acting 
at  once,  would,  by  means  of  a micrometer,  read  off  any  given  number  of  divisions,  so  as  to  answer  the 
purpose  of  subdividing  the  circle.  Mr.  Ramsden,  in  consequence  of  the  reward  offered  by  the  Board  of 
Longitude  to  Mr.  Bird,  for  his  method  of  dividing,  in  the  year  1760,  turned  his  attention  towards  the 
contrivance  of  an  engine  that  would  divide  nautical  instruments  with  sufficient  accuracy,  without  resort- 
ng  to  the  delicate  and  tedious  process  of  manipulation,  practised  by  Mr.  Bird.  Lie  completed  an  en- 
gine with  an  indented  plate,  or  wheel  of  thirty  inches  diameter,  which,  though  it  did  not  entirely  answer 
hi3  expectations  to  their  full  extent,  yet  was  found  very  useful  for  dividing  theodolites,  and  such  like 
instruments,  with  great  facility.  This  was  effected  before  the  spring  of  1768;  and  in  1771,  a much 
larger  and  more  efficient  engine  was  produced,  with  an  indented  plate  of  forty-five  inches  diameter, 
which  divided  a sextant  for  Mr.  Bird’s  examination  so  accurately,  that  the  Board  of  Longitude,  ever 
ready  to  remunerate  any  successful  endeavor  to  promote  the  lunar  method  of  determining  the  longi- 
tude at  sea,  did  not  hesitate  to  confer  a handsome  reward  on  the  inventor,  but  on  the  express  condition 
that  the  said  engine  should  be  at  the  service  of  the  public,  and  that  Mr.  Ramsden  should  publish  an 
explanation  of  his  method  of  making  and  using  it. 


In  1820,  Mr.  James  Allan  was  rewarded  by  the  Board*of  Longitude  with  one  hundred  pounds, 
f r his  improvement  on  Ramsden's  dividing-engine.  This  improvement  consists  in  the  method  em- 
ployed to  cut  or  rack  the  teeth  around  the  periphery  of  the  great  circle,  worked  by  an  endless  screw, 
upon  which  the  arc  to  be  divided  is  placed,  so  as  to  insure  perfect  equality  of  size,  as  regards  the  teeth, 
in  all  parts  of  the  circle.  This  extremely  ingenious,  though  simple  contrivance  of  Mr.  Allan,  is  described 
in  the  transactions  of  the  Society  of  Arts.  The  great  circle  of  bell-metal,  a semi-plan  of  which  is  shown 
in  Fig.  3121,  is  mounted  upon  an  axis  A,  and  its  surface  made  truly  plane  and  perpendicular  to  the 
axis ; the  section  shows  the  figure  of  the  axis,  and  the  central  ring  B,  to  give  the  greatest  strength  to 
the  circle ; C is  a section  of  a portion  of  the  frame  of  the  engine  ; and  D,  a socket  into  which  the  axis 
A is  fitted;  the  circumference  of  the  large  circle  is  then  turned  to  such  a figure  as  to  receive  a ring  oi 
brass  a,  which  is  united  firmly  to  it  by  a number  of  pins.  Upon  this  ring  a second,  b,  is  placed,  the  two 


TOOLS. 


727 


making  the  same  thickness  as  the  circle,  a sectional  view  of  which  is  here  introduced.  The  inside  of 
the  ring  b,  and  the  outside  of  the  bell-metal  circle,  are  fitted  to  each  other  with  the  greatest  accuracy 
and  great  care  taken  to  turn  the  same  truly  fitting  concentric  with  the  axis  of  the  circle ; the  brass 
rings  a and  b are  held  together  by  twenty- four  screws,  and  a groove  corresponding  to  the  curvature  ot 
the  screw  which  moves  the  circle  is  then  turned  in  the  outside  of  the  two ; in  this  state  the  racking  of 
the  teeth  is  performed  by  a screw  similar  to  that  afterwards  used  to  turn  the  circle  to  its  divisions,  but 
notched  across  the  threads  so  that  it  cuts  like  a saw,  when  pressed  against  the  circle  and  turned  round, 
and  removes  the  metal  from  the  spaces  between  the  teeth,  which  are  by  this  means  formed  around  the 
edge  of  the  circle ; when  this  has  been  performed  all  round,  two  fine  lines  are  drawn  across  the  brass 
and  bell-metal  circles,  diametrically  opposite  to  each  other ; the  twenty-four  brass  screws  are  then 
withdrawn,  and  the  upper  brass  ring  turned  exactly  half  round,  which  is  determined  by  the  lines  before 
mentioned  ; and  by  this  means  the  teeth  of  the  circle  are  divided  into  two  thicknesses,  and  being  put 
together  again  in  opposite  directions,  if  any  error  arose  in  racking  the  teeth,  it  would  be  shown  by  the 
upper  and  lower  halves  of  the  teeth  not  coinciding  when  reversed,  and  by  racking  them  while  reversed, 
the  screw  would  cut  away  the  inequalities,  and  make  all  the  teeth  of  the  same  size  and  distance  from 
each  other;  this  reversing  the  teeth  is  performed  several  times,  till  the  teeth  are  brought  to  a perfect 
equality  in  all  parts  of  the  circle ; four  steady  pins  are  accurately  fitted  into  the  two  rings  to  hold 
them  together  in  any  of  the  positions  in  which  they  have  been  racked  together,  and  it  is  upon  them 
that  dependence  is  placed  for  the  coincidence  of  the  teeth,  the  twenty-four  screws  being  merely 
to  hold  them  fast  together,  and  fitted  rather  loosely  in  their  holes  that  they  may  not  strain  the 
steady-pins. 

We  have  purposely  omitted  any  mention  of  the  improved  engine  by  Mr.  E.  Troughton,  in  who3e 
hands  the  art  doubtless  arrived  at  a high  degree  of  exactness,  because,  to  adopt  the  language  of  a com- 
petent judge,  there  are  various  difficulties  in  the  application  and  construction  of  the  apparatus,  to  avoid 
which  was  the  avowed  object  of  the  engine  now  in  part  to  be  described,  by  adopting  principles  perfectly 
independent  of  mechanical  action,  and  governed  only  by  vision,  assisted  by  the  most  powerful  optical 
means.  For  this  really  scientific  piece  of  mechanism  we  are  indebted  to  Mr.  Alexander  Ross,  mathe- 
matical instrument  maker,  to  whose  ingenuity  the  Society  of  Arts  of  London,  in  1831,  awarded  the  Gold 
Isis  Medal  and  fifty  guineas. 

Fig.  3422  is  a side  view  of  Mr.  Ross’s  apparatus  for  cutting  original  divisions,  and  consists  of  the  fol 
lowing  parts:  a small  circle  10  or  12  inches  diameter,  divided  into  spaces  of  3°  45'  or  96  parts,  by  the 
usual  dividing-engine  or  by  any  ordinary  means — -two  micrometer  microscopes,  represented  at  a b an 
arc  co  of  the  length  of  3°  45'  of  the  circle  to  be  divided — a cutting-frame  <1  e,  and  a frame  ffgg  to  sup- 
port the  apparatus.  The  frame  fg  consists  of  a bottom  and  top  plate  connected  by  two  strong  pillars, 
one  of  which  is  represented  at  li,  the  front  one  being  removed  to  show  the  other  parts.  In  the  bottom 
plate  are  screwed  the  nuts  i i which  form  adjustable  feet  for  the  frame ; these  nuts  are  perforated,  an-j 
the  screws  jj  pass  through  and  fasten  the  whole  securely,  after  being  levelled  by  the  nuts  i and  the 
level  l.  The  upper  plate  is  secured  to  the  pillars  h by  two  screws  and  collets,  moving  on  the  one  as  a 
centre,  and  adjustable  at  the  other  by  the  pushing  screw  n for  the  purpose  of  setting  the  cutting-point 
o,  which  is  attached  to  the  upper  plate  /-,  to  cut  a radiating  division  on  the  circle  to  be  divided:  an  arc 
and  index  not  capable  of  being  shown  in  a side  view,  indicate  the  inclination  given.  To  the  upper  plate 
is  likewise  attached  the  hollow  centre  q ; in  this  works  a male  centre,  the  flanch  of  which  is  seen  at  r ; 
this  supports  the  bar  ss  which  carries  the  microscopes  a b and  the  level  l.  The  microscopes  are  secured 
to  this  bar  by  two  pulling  and  two  pushing  screws  tt,tt,  passing  through  a flanch  v,  and  acting  ih  and 
on  the  bar  s.  The  microscopes  are  secured  to  the  flanch  by  fitting  into  strong  tubes  u u,  and  when  ad- 
justed to  distinct  vision  can  be  fixed  in  that  position  by  the  clamping-rings  w w.  The  handle  x x for  the 
cutting-frame  is  attached  to  the  perpendicular  sling  d,  having  a double  joint  at  the  point  where  it  is 
fixed,  in  order  to  prevent  any  unequal  pressure  from  producing  a lateral  motion  of  the  cutting-point ; 
the  other  end  is  connected  to  the  upright  dovetail  slide  34,  which  forms  part  of  the  apparatus  for  mov- 
ing the  cutting-point.  (See  article  Automatic,  in  1st  volume  of  this  Dictionary.) 

From  a consideration  of  the  foregoing  sketch  we  draw  the  following  conclusion,  namely,  that  the  dif- 
ficulties and  failures  which  have  from  time  to  time  checked  the  progress  of  inventive  genius  are  to  be 
traced  to  two  sources:  first,  a limited  knowledge  of  elementary  principles;  and  secondly,  the  defective 
construction  and  consequent  imperfect  performance  of  the  tools  employed. 

One  of  the  most  valuable  aids  to  the  more  perfect  construction  of  machinery  is  due  to  Mr.  Joseph 
Whitworth,  of  Manchester,  who  has  recently  introduced  the  simple  process  of  scraping,  instead  of  the 
dirty  and  unsatisfactory  operation  of  grinding,  as  a means  of  producing  plane  metallic  surfaces.  It  is 
essentially  required  in  a surface  for  mechanical  purposes,  that  all  the  bearing  points  should  be  in  the 
same  plane,  that  they  should  be  equidistant  from  each  other,  and  that  they  should  be  sufficiently  nu- 
merous for  the  particular  application  intended.  Where  surfaces  remain  together  in  fixed  contact,  the 
bearing  points  may,  without  disadvantage,  be  fewer  in  number,  and  consequently  wider  apart ; but  in 
the  case  of  sliding  surfaces  the  points  should  be  numerous,  and  in  close  approximation. 

A little  consideration  will  make  it  evident  that  these  conditions  cannot  be  obtained  by  the  process  of 
grinding.  And  first,  with  regard  to  general  outline,  how  is  the  original  error  to  be  got  rid  of  ? For  if 
it  be  supposed  that  one  of  the  surfaces  is  concave,  and  the  other  a true  plane,  then  the  tendency  of 
grinding,  no  doubt,  would  be  to  reduce  the  error  of  the  former,  but  the  opposite  error  would  at  the  same 
time  be  created  in  the  true  surface.  The  only  case  in  which  an  original  error  could  be  extirpated, 
would  be  when  it  was  met  by  a corresponding  and  contrary  error  of  exactly  the  same  amount  in  the 
oj posed  surface;  but  it  is  evident  that  where  only  two  surfaces  are  concerned,  the  variety  of  error  in 
the  general  outline  is  not  sufficient  to  afford  any  probability  of  mutual  compensation.  It  will  furthei 
appear,  that  if  the  original  error  be  inconsiderable,  the  surfaces  must  lose  instead  of  gaining  truth.  It 
results  from  the  nature  of  the  process  that  certain  parts  are  acted  upon  for  a longer  time  than  others ; 
the}r  are  consequently  more  worn,  and  the  surfaces  are  made  hollow;  nor  is  there  any  probability  o' 


728 


TOOLS. 


obviating  this  source  of  error  except  by  sliding  the  one  surface  entirely  out  of  the  other  at  each  move, 
a method  which  is  clearly  impracticable. 

It  may  be  mentioned  as  an  additional  cause  of  error,  that  the  grinding  powder  collects  in  greater 
quantity  about  the  edges  of  the  metal  than  upon  the  interior  parts,  producing  the  well-known  effect  ol 
the  bell-mouthed  form.  This  is  particularly  objectionable  in  the  case  of  slides,  from  the  access  afforded 
to  particles  of  dust,  and  the  immediate  injury  necessarily  occasioned  thereby.  Another  circumstance 
materially  affecting  the  durability  of  ground  slides  is,  that  a portion  of  the  emery  becomes  fixed  in  the 
pores  of  the  metal,  and  can  never  be  entirely  eradicated  therefrom,  causing  a rapid  and  irregular  wear 
of  the  surface. 

If,  then,  grinding  be  not  adapted  to  form  a true  general  outline,  neither  is  it  to  produce  accuracy  in 
the  minuter  detail.  There  can  be  little  chance  of  a multitude  of  points  being  brought  to  bear,  and  dis- 
tributed equally  under  a process  from  which  all  particular  management  is  obviously  excluded.  To 
obtain  any  such  result,  it  is  necessary  to  possess  the  means  of  operating  independently  on  each  point  as 
occasion  may  require,  whereas  grinding  affects  all  simultaneously.  It  is  subject  neither  to  observation 
nor  control,  there  is  no  opportunity  of  regulating  the  distribution  of  the  powder,  or  of  modifying  its  ap- 
plication, with  reference  to  the  particular  condition  of  the  different  parts  of  the  surface.  The  variation 
in  the  quantity  of  the  powder  and  the  quality  of  the  metal  will  of  necessity  produce  inequalities,  even 
supposing  they  did  not  previously  exist.  Hence,  if  a ground  surface  be  carefully  examined,  the  bearing 
points  will  be  found  lying  together  in  irregular  masses,  with  extensive  cavities  intervening.  An  ap- 
pearance indeed  of  beautiful  regularity  is  produced,  to  which,  no  doubt,  we  may  trace  the  universal 
prejudice  so  long  established  in  favor  of  the  process;  but  this  appearance,  so  far  from  being  any  evi- 
dence of  truth,  serves  only  to  conceal  error,  and  under  this  specious  disguise  surfaces  pass  without 
examination,  which  if  unground  would  be  at  once  rejected. 

In  addition  to  what  has  been  stated,  it  must  be  remembered  another  great  evil  of  grinding  is  that  it 
takes  from  the  mechanic  all  sense  of  responsibility  and  all  spirit  of  emulation,  while  it  deludes  him  with 
the  idea  that  the  surface  will  be  ultimately  ground  true ; hence  he  slurs  his  work  over  in  a slovenly 
manner,  trusting  to  the  effect  of  grinding,  being  conscious  that  it  will  efface  all  evidence  either  of  care 
or  neglect  on  his  part. 

Thus  it  appears  that  the  practice  of  grinding  has  altogether  impeded  the  progress  of  improvement. 
A true  surface,  instead  of  being,  as  it  ought,  in  common  use,  was  until  lately  almost  unknown ; few 
mechanics  have  any  distinct  knowledge  of  the  method  to  be  pursued  for  obtaining  it,  nor  do  practical 
men  sufficiently  advert  either  to  the  immense  importance  or  to  the  comparative  facility  of  the  acquisi- 
tion. The  expression  “true  surface”  may  appear  contradictory,  and  therefore  require  qualification. 
Absolute  truth  is  confessedly  unattainable ; moreover,  it  would  be  possible  to  aim  at  a degree  of  perfec- 
tion far  beyond  the  necessity  of  the  particular  case,  the  difficulty  of  which  would  more  than  counter- 
balance the  advantage ; nevertheless  it  is  certain  that  the  progress  hitherto  made  falls  far  short  of  this 
practical  limit,  and  that  considerations  of  economy  alone  would  carry  improvement  many  degrees 
higher.  The  extensive  class  of  machinery  denominated  tools,  affords  an  important  application  of  the 
subject;  here  every  consideratiou  combines  to  enforce  accuracy.  It  is  implied  in  the  very  name  of  the 
planing  engine,  the  express  purpose  of  which  is  to  produce  true  surfaces,  and  it  is  itself  constructed  of 
slides,  according  to  the  truth  of  which  will  be  that  of  the  work  performed ; and  when  it  is  considered 
that  the  lathe  and  the  planing  engine  are  employed  in  the  making  of  all  other  machines,  and  are  con- 
tinually reproducing  surfaces  similar  to  their  own,  it  will  manifestly  appear  of  paramount  importance 
that  they  should  themselves  be  perfect  models.  Indeed  it  would  be  difficult  to  mention  any  description 
of  machinery  which  would  not  serve  as  an  illustration  of  the  importance  belonging  to  truth  of  surface, 
and  at  the  same  time  offer  abundant  evidence  of  the  present  necessity  for  material  improvement ; nor 
is  there  any  subject  connected  with  mechanics,  the  bearings  of  which,  whether  regarded  in  a manufac 
turing  or  scientific  point  of  view,  are  more  varied  or  more  extensive. 

The  tool  employed  for  scraping  is  not  only  simple  but  easily  made ; it  should  be  of  the  best  cast-steel, 
and  carefully  sharpened  to  a fine  edge  on  a Turkey-stone,  the  use  of  which  must  be  frequently  repeated ; 
but  worn-out  files  may  be  converted  into  convenient  scraping-tools.  A flat  file  with  the  broad  end  bent 
and  sharpened  will  be  most  suitable  in  the  first  instance,  and  afterwards  a three-angled  file  sharpened 
on  all  the  edges.  The  process  of  scraping  is  equally  simple,  requiring  rather  care  than  skill  on  the  part 
of  the  work  man,  whilst  it  affords  a certain  and  speedy  means  of  attaining  any  degree  of  truth  that  may 
be  deemed  necessary,  thus  tending  to  the  gradual  establishment  of  a higher  standard  of  excellence,  the 
influence  of  which  cannot  fail  to  affect  beneficially  all  mechanical  operations,  opening  at  the  same  time 
to  the  mechanic  himself  a new  field  in  which  he  will  find  ample  scope  for  the  exercise  of  skill,  both 
manual  and  mental. 

We  are  now  in  a condition  to  proceed  with  the  matter  more  immediately  under  consideration.  The 
value  of  every  cutting  instrument  depends  upon  the  excellence  of  the  steel  of  which  it  is  made,  the  care 
bestowed  daring  the  several  processes  of  forging,  hardening,  and  tempering,  and  the  just  adaptation  of 
the  angle  or  bevel  which  forms  its  edge  to  the  work  it  is  intended  to  perform.  Generally  speaking,  this 
angle  is  determined  by  the  hardness  of  the  substance  to  be  operated  upon.  Thus  we  see  chisels  for 
cutting  soft  woods  are  thinner  than  those  used  for  the  harder  species,  and  these  again  are  more  acute 
than  chisels  employed  for  cutting  metals,  or  in  other  words,  the  greater  the  resistance  offered  by  the 
material  to  be  cut,  the  more  obtuse  must  be  the  angle  of  the  tool.  This  definition  is  not  propounded  as 
rigidly  correct  in  all  cases,  although  it  is  susceptible  of  abundant  practical  illustration ; for  example,  in 
hand-turning,  the  workman  is  enabled  by  raising  or  lowering  the  T of  the  rest,  to  vary  the  direction  and 
limit  the  cut  of  the  tool  employed,  according  to  circumstances.  This  one  fact,  amongst  a multitude  oi 
others  equally  palpable  that  could  be  adduced,  might  have  been  expected  to  induce  inquiry  and  inves- 
tigation. On  the  contrary,  we  have  the  authority  of  Mr.  Nasmyth  for  stating  that  the  form  of  tools, 
more,  especially  those  us.ed  in  turning  and  planing  iron,  brass,  <fec.,  has  not  hitherto  received  either  that 
attention  which  the  importance  of  the  subject  calls  for,  nor  has  any  attempt  been  made  to  reduce  it  to 


TOOLS. 


729 


plain  and  general  principles,  of  which  it  is  highly  susceptible,  and  if  so  treated  would  be  of  much  service 
to  those  in  whose  hands  the  management  of  such  tools  is  for  the  most  part  intrusted.  So  many  consid- 
erations of  a practical  nature  are  inseparable  from  this  subject,  that  the  quality  as  well  as  the  quantity 
of  work  produceable  from  turning  lathes  and  planing  machines  depends  entirely  upon  the  skill  of  the 
workman  in  giving  to  his  tools  the  proper  form. 

The  general  principle  propounded  by  Mr.  Nasmyth,  which  is  equally  applicable  whether  the  motion 
be  horizontal,  circular,  or  vertical,  is  deduced  from  a consideration  of  the  direction  in  which  the  metal 
is  to  be  cut  or  penetrated.  With  regard  to  the  first  case,  as  in  the  planing  machine,  it  is  manifest  that 
the  face  of  the  tool  is  at  right  angles  to  the  plane  of  the  material  to  be  cut,  and  consequently,  if  its  point 
or  cutting  edge  be  made  in  the  form  of  a very  obtuse  angle,  it  will  possess  little  or  no  penetrating  qual- 
ity— such  a tool  would  not  cut,  but  rather  abrade,  or  probably  crush  off  the  particles  of  metal.  Again, 
if  wo  resort  to  the  other  extreme,  and  give  to  the  cutting  edge  the  shape  of  an  extremely  acute  angle, 
we  shall  find,  however  sharp  it  may  appear,  a total  absence  of  penetrating  quality,  or  at  all  events  in 
the  required  direction,  and  what  is  equally  objectionable,  the  point  being  weak  would  snap  off,  incajja- 
ble  of  resisting  the  least  applied  force. 

From  an  investigation  of  these  and  other  obvious  facts,  Mr.  Nasmyth  concludes  that  a tool  of  the 
form  shown  in  Fig.  3423  fulfils  the  requisite  conditions,  as  it  combines  a high  degree  of  acuteness  with 
sufficient  strength — the  former  in  the  direction  of  the  cut,  and  the  latter  behind  the  point  or  cutting  edge, 
where  it  is  most  needed.  Hence  the  following  principle  may  be  established,  namely,  that  in  forming 
and  setting  a tool  to  cut  any  surface,  it  is  (jssentially  necessary  so  to  place  it  that  the  end  shall  form  the 
least  possible  angle  with  the  surface  to  be  cut,  or  in  other  words,  as  nearly  parallel  as  possible,  and  what- 
ever degree  of  acuteness  may  be  deemed  necessary  must  be  obtained  by  hollowing  out  the  face  E C,  on 
which  the  shavings  slide.  An  apt  and  very  familiar  illustration  of  the  principle  may  be  drawn  from  the 
common  plane  of  the  joiner.  An  artificial  end  being  given  to  the  plane-iron,  which  is  here  the  cutting 
tool,  by  means  of  the  sole  of  the  plane,  this  necessarily  limits  the  penetrating  quality  in  all  directions 
except  that  in  which  it  is  required  to  remove  the  material.  Further,  it  can  scarcely  have  escaped  ob- 
servation that  the  bevelled  surface  of  a chisel  is  invariably  placed  outwards,  and  the  flat  surface  next 
to  the  wood,  so  that  the  face  of  the  chisel  next  the  wood  and  the  surface  of  the  wood  itself  shall  form 
the  least  possible  angle. 

The  same  principle  is  similarly  true  in  the  case  of  turning-tools,  and  indeed  in  every  tool,  from  the 
smallest  and  most  delicate  of  the  clock  and  watch  maker,  up  to  the  largest  and  most  powerful  tool  in 
an  engineer’s  lathe  or  planing  machine. 

As  regards  circular  motion,  we  have  a clear  exemplification  of  the  principle  by  merely  considering 
the  tool  already  described  as  a turning-tool.  In  Fig.  3424,  A B shows  a section  of  a cylindrical  bar  in 
the  lathe,  and  E F so  placed  as  to  be,  as  nearly  as  circumstances  will  permit,  a tangent,  that  is,  at  right 
angles  to  the  radius  of  the  curve — the  requisite  acuteness  being  obtained,  as  before,  bv  hollowing  out 
the  face  E C. 


The  same  principle  applies  to  drills.  Thus  Fig.  3425  being  the  end  view  of  a drill,  the  edge  0 P 
should  be  in  the  least  degree  prominent  or  out  of  the  plane  of  the  surface,  of  which  the  bounding  lines 
are  the  edges,  0 S being  slightly  less  prominent  than  O P,  so  that  the  penetrating  quality  at  the  edge 
0 P may  be  limited  as  much  as  possible.  An  adherence  to  these  rules  will  produce  a drill  that  shall 
cut  a smooth  and  equal  hole,  without  chattering,  as  is  commonly  the  case  when  the  edges  are  bevelled 
very  much  back,  as  shown  at  R.  The  necessary  acuteness  to  the  cutting  edge  of  the  drill  is  easily  ob- 
tained by  merely  observing  the  principle  laid  down  in  respect  to  turning-tools,  that  is,  by  hollowing  out 
a groove  at  X,  on  each  cutting  face. 

Every  mechanic  is  sensible  of  the  value  of  good  tools  as  necessary  appliances  to  the  performance  of 
his  work  more  quickly,  with  less  exertion,  and  more  accurately  than  can  be  done  with  inferior  ones  ; yet 
how  few  are  in  a position  to  answer  this  apparently  simple  question,  what  constitutes  this  quality  de- 
nominated goodness  ? The  excellence  of  cutting-tools  is  generally  decided  by  their  relative  degrees  of 
endurance,  but  how  many  incidental  circumstances  may,  and  frequently  do,  interfere  to  vitiate  any  ac- 
curate comparison.  As  regards  hardness,  nearly  the  only  test  is  the  resistance  the  objects  offer  to  the 
file,  a mode  extremely  fallacious,  because  files  differ  among  themselves  in  hardness,  and  at  best  only 
serve  to  indicate  in  a very  imperfect  manner,  to  the  touch  of  the  individual,  a vague  notion  without  any 
distinct  measure.  Take,  for  example,  two  chisels  for  turning  iron,  both  of  cast-steel,  and  from  the  hands 
of  the  same  maker,  and  although  precisely  alike  in  outward  appearance,  the  one  may  be  absolutely 
worthless  and  the  other  equally  valuable.  Nay,  one  portion  of  the  same  chisel  may  be  good  and  the 
other  bad.  If  during  the  process  of  fabrication  of  two  cutting-tools  the  same  treatment  be  practised 
witli  similar  care,  we  should  naturally  expect,  all  things  being  coincident,  that  the  one  would  correspond 
with  the  other.  Experience  shows  the  fallacy  of  this  mode  of  reasoning.  Nearly  every  metal-turner 
makes  his  own  tools,  and  for  this  plain  reason,  that  he  cannot  place  any  dependence  on  those  he  pur 
chases.  The  smith  who  forges,  hardens,  and  tempers  these  tools,  rarely  uses  them ; he  labors  to  pro- 


730 


TOOLS. 


duce  a certain  number  in  a given  time,  and  if  they  satisfy  the  eye  his  o eject  is  attained.  The  good  or 
bad  quality  of  a tool  depends  more  on  the  care  and  attention  bestowed  during  the  process  of  forging 
than  is  commonly  imagined,  and  the  defects,  whether  of  texture  or  edge,  which  so  often  present,  them- 
selves in  articles  manufactured  of  steel,  are  to  be  traced  not  so  much  to  any  natural  imperfection  or 
partial  conversion  of  the  metal,  as  to  a slovenly  and  hasty  mode  of  forging.  (See  Steel.) 

The  tool  employed  for  chipping  is  simply  a chisel  with  an  edge  assuming  the  shape  of  an  acute 
wedge ; it  is  ordinarily  made  from  square  or  oval  steel  of  the  best  quality,  rather  spread  out  at  that 
end  which  is  intended  to  form  the  edge,  so  as  to  afford  a greater  surface.  Whatever  may  be  the 
length  of  the  chisel,  whether  six  or  eight  inches — and  this  must  depend  in  some  measure  upon  the  na- 
ture of  the  work — the  form  of  the  cutting  edge  is  in  all  cases  nearly  similar ; observing,  however,  that 
it  is  advisable  to  have  the  chisel  drawn  out  by  the  smith,  by  which  precaution  the  edge,  when  injured, 
may  be  more  easily  restored  on  the  grindstone.  The  operation  of  chipping  is  materially  facilitated  by 
the  use  of  the  cross-cutting  chisel,  of  which  Fig.  3420  shows  a front  and  Fig.  342*7  a side  view,  a a'  in 
the  latter  figure  being  a section.  The  cutting  edge  of  this  extremely  useful  tool  varies  in  breadth  from 
one-sixteenth  to  five-sixteenths  of  an  inch  ; its  utility  and  application  will  probably  be  rendered  more  ob- 
vious to  the  reader  by  a diagram  than  by  any  lengthened  verbal  explanation. 

Suppose  the  surface  of  a block  of  cast-iron,  represented  by  Fig.  3428,  to  require  chipping.  In  the 
first  place,  the  workman  cuts  longitudinal  grooves  a a',  h b',  cc\  throughout  or  across  the  entire  length 
or  breadth  of  the  surface  by  means  of  the  cross-cutting  chisel,  and  at  such  a distance  from  each  other  as 
is  rather  less  than  the  width  of  the  chipping  chisel  intended  to  be  subsequently  employed ; by  which 
means  the  corners  of  the  edge  of  the  chipping  chisel  are  essentially  preserved  from  injury,  as  under  or- 
dinary circumstances  it  is  found  that  the  corners  of  the  chisel  first  give  way,  and  require  constant  repair. 

The  interior  portions  of  any  piece  of  metal  are  usually  removed  by  a tool  called  a drill.  Boring  dif- 
fers from  drilling  principally,  as  we  shall  hereafter  show,  in  being  applied  to  larger  works.  The  class 
of  tools  which  come  within  the  general  description  of  drills,  or  cutters,  is  extremely  numerous ; that 
more  commonly  employed  is  too  well  known  to  require  description,  more  especially  as  we  have  already 
given  Mr.  Nasmyth’s  imjrroved  form  of  this  tool.  The  pin-drill  and  half-round  drill  are,  in  certain  cases, 
extremely  useful ; the  only  objection  to  the  former  is,  that  it  requires  a small  hole  to  be  first  cut  in  and 
through  the  metal  in  which  the  pin  of  the  drill  works  and  necessarily  follows ; it  answers,  however,  for 


3420.  3427.  3431.  3430.  3420. 


ill  ordinary  purposes,  and  performs  its  work  extremely  well,  although  it  cannot  be  depended  on  in 
cases  where  rigid  accuracy  is  required.  The  half-round  drill  offers  little  or  no  security  whatever  as  re- 
gards piercing  in  a right  line ; it  is,  however,  a very  useful  tool,  and  may,  in  many  instances,  be  advan- 
tageously employed.  Perhaps  the  most  effective  form  of  drill  yet  introduced,  more  especially  if  ap- 
plied to  any  metallic  substance  revolving  in  a lathe,  is  that  invented  by  M.  Collas,  an  eminent  French 
mechanician.  This  tool,  of  which  Fig.  3429  is  a front  view,  and  Figs.  3430  and  3431  side  views,  taken 
from  from  e and/,  is  turned  truly  cylindrical  throughout  its  entire  length,  except  at  that  end  which  is 
intended  to  fit  into  the  brace,  or  if  used  in  a lathe  a small  portion  of  the  metal  is  filed  square,  or  the 
edges  taken  off  to  admit  of  any  convenient  mode  of  preventing  the  drill  turning.  At  the  other  or  oppo- 
site extremity  of  this  cylinder  of  steel,  and  through  the  centre  a small  hole  is  drilled  in  proportion  to  the 
size  of  the  tool ; one  half  of  a portion  of  the  bar  is  then  cut  away,  leaving  the  remainder  cylindrical; 
this  part  is  then  equally  divided  into  three,  and  one  of  them  filed  out,  as  is  clearly  shown  in  the  plan 
views  of  Figs.  3429,  3430,  and  3431,  by  which  process  the  central  hole  is  cut  into  two  equal  parts,  and 
becomes  a small  semicircular  groove.  With  regard  to  the  angle  of  inclination  to  be  given  to  the  cutting 
end  of  the  drill,  this  must  depend  principally  upon  the  resistance  offered  by  the  material.*  This  tool 
manifestly  cuts  circularly,  except  at  the  centre,  where  it  forms  a small  projecting  pin,  which  enters  the 
central  groove  and  serves  as  a conductor;  in  proportion  as  the  tool  advances  this  pin  increases  in  length 
until  it  reaches  the  extremity  of  the  groove,  when  it  necessarily  breaks  and  comes  away  with  the  chips. 
It  is  important  to  observe  that  this  groove  must  be  rather  less  than  greater  than  a semicircle,  otherwise 
the  pin  of  metal  which  enters  therein,  being  cylindrical,  could  not  leave  it  during  the  progress  of  the 
operation,  and  the  distinguishing  feature  of  this  tool  would  be  destroyed. 

Small  drills  are  commonly  made  of  a single  piece  of  steel  wire,  upon  which,  near  to  the  middle,  a 
pulley  or  drill-barrel  is  driven.  Occasionally  a small  mandrel  is  used,  provided  at  one  end  with  a square 


* Drills  or  boring-bits  ought  to  have  the  angles  of  their  edges  varied  according  to  the  nature  of  the  metal  to  be  bored  ; 
thus,  wrouglit-irou  would  require  a very  different  angle  from  that  used  for  cast-iron.  If  in  use,  the  bit  trembles  or  jars,  it 
is  a sign  that  the  angle  is  too  acute,  and  must  be  made  more  obtuse,  or  nearer  to  a right  angle  with  the  plane  or  Hat  lacy 
of  the  drill.  Again,  if  the  obliquity  of  the  other,  or  crossing  angle,  be  too  great,  the  tool  will  also  have  too  great  a ten- 
dency to  form  a nipple  or  cone  in  the  centre  of  the  bottom  of  the  hole,  and  to  bore  the  hole  gradually  wider  aDu  wider 
instead  of  truly  cylindrical,  as  it  will  do  when  properly  formed;  and  that  fault  must  therelore  be  corrected  by  grinding  the 
drill  or  bit  so  as  to  reduce  its  obliquity,  or  bring  it  nearer  to  a right  angle  with  the  sides  of  the  bit 


TOOLS. 


781 


hole  about  half  an  inch  deep,  into  ■which  drills  of  various  dimensions  can  be  inserted.  The  disadvan- 
tage of  this  mode  of  construction  is,  that  the  drill  is  rarely  placed  true  in  the  mandrel,  which  necessarily 
causes  it  to  perform  indifferently;  it  is,  therefore,  but  seldom  employed  by  practical  men  who  have  the 
convenience  of  readily  sujoplying  themselves  with  drills  of  various  dimensions  as  required. 

When  small  drills  are  used  they  are  held  horizontally  and  kept  up  to  the  work  by  a breast-piece, 
which  is  usually  made  of  wood,  armed  with  a plate  of  steel  superficially  pierced  with  holes  of  different 
dimensions,  in  one  of  which  the  blunt  end  of  the  drill  works.  The  drill  receives  a reciprocating  motion 
from  an  elastic  bow,  the  spring  of  which  is  coiled  once  round  the  pulley.  Common  bows  are  ordinarily 
made  of  stout  cane,  those  of  a better  description  of  steel,  and  the  string  of  catgut,  but  the  strength  of 
both  must  necessarily  be  proportioned  to  the  size  of  the  drill. 

In  order  to  cut  large  holes  more  force  is  obviously  required  than  can  be  imparted  by  the  method 
just  described,  instead  of  which  a brace,  not  very  dissimilar  to  that  used  by  carpenters,  is  employed, 
and  the  drill  itself  is  fitted  as  a boring-bit ; but  with  this  difference  in  the  mechanical  arrangement,  in- 
stead of  the  stock  remaining  stationary,  we  have  in  this  case  a long  tapering  spindle,  which  being  noth- 
ing more  than  a continuation  of  the  brace,  is  necessarily  carried  round  at  the  same  time,  and  the  motion 
becomes  continuous.  The  upper  part  of  this  spindle  works  in  an  iron  or  steel  plate,  which  is  attached 
to  the  under  side  of  the  beam,  called  the  drill-beam.  One  end  of  this  beam  turns  upon  a transverse  pin, 
between  two  uprights,  pierced  with  various  holes,  to  allow  facility  of  fixing  it  by  means  of  the  pin  at 
different  elevations.  The  other  end  of  the  beam  traverses  between  two  uprights,  and  carries  a heavy 
weight,  which  acting  as  a lever  necessarily  keeps  the  drill  to  its  work,  and  the  point  of  the  drill  being 
placed  upon  that  part  of  the  metal  to  be  bored,  the  brace  is  revolved  by  the  hand  of  the  workman. 

The  shank  of  the  drill  should  be  accurately  fitted  in  the  brace,  and  the  apparatus  is  generally  so  ar- 
ranged that  the  work  may  be  held  in  a strong  bench-vice  during  the  process. 

The  difficulty  of  applying  a press  or  lever  drill  in  confined  situations  appears  to  have  been  very  gen- 
erally felt.  In  Bergeron’s  Manuel  du  Tourner,  there  is  a plan  of  a brace  worked  by  a pair  of  bevel- 
wheels,  and  Mr.  George  Rennie,  in  the  last  edition  of  Buchanan  on  Mill-work  and  other  Machinery,  has 
given  two  views  of  a portable  drill,  invented  by  Messrs.  Nasmyth,  Gaskell,  &'  Co.,  of  Manchester,  which 
consists  of  a cast-iron  frame,  carrying  an  upright  drilling  spindle,  the  top  of  which  is  formed  into  a 
screw,  so  that  it  may  be  raised  or  depressed  by  a handle-wheel,  while  the  requisite  revolving  motion  is 
imparted  to  it  by  two  small  bevel-wheels.  When  required  to  drill  a hole  in  any  piece  of  machinery, 
it  is  first  of  all  set  in  its  proper  place ; after  this  is  done  the  handle  or  small  fly-wheel  is  turned  round 
for  working  the  drill,  and  by  a slow  revolving  motion  given  to  the  upper  handle,  communicating  by 
means  of  the  screw,  the  drill  while  working  is  made  gradually  to  descend. 

* The  contrivance  we  have  now  to  describe  is,  we  are  informed,  the  invention  of  a practical  mechanic, 
then  in  the  employ  of  Mr.  Hague,  of  London.  The  distinguishing  feature  of  this  tool  is  the  introduction 
of  a ratchet-wheel  and  click,  which  obviate  the  necessity  of  turning  the  brace  completely  round,  so  that 
the  effective  power  of  the  workman  is  constantly  acting  at  the  greatest  advantage.  Big.  8432  shows 
an  elevation  of  the  complete  tool.  Fig. 

3483  is  a section  of  the  same ; and  Fig. 

3434  the  ratchet  with  its  appendages, 
and  the  arm  separately.  It  is  composed 
of  two  parts  : the  first  distinctly  shown 
in  the  sectional  view,  and  distinguished 
by  the  letter  a,  which  is  simply  an  elon- 
gated nut ; the  second  is  a circular  piece 
of  wrought-iron,  terminating  in  a square 
threaded  screw  h,  and  working  into  the 
aforesaid  nut  a.  The  combined  length 
of  these  two,  which  constitute  the  prin- 
cipal part  of  the  tool,  as  shown  in  Fig. 

3432,  may  be  lengthened  or  shortened 
at  pleasure,  by  means  of  a nut  a.  The 
bottom  piece  b has  a square  hole,  slightly  tapered,  cut  in  its  extremity,  and  in  a direction  with  its  axis 
for  receiving  the  drill  f The  handle  or  third  portion  of  the  tool,  shown  separately  in  Fig.  3434,  fits  on 
to  b,  for  which  purpose  a square  hole  is  cut  in  it  as  shown  at  e ; the  handle  has  a portion  of  it  at  one 
end  cut  out  to  receive  the  ratchet  and  its  appendages,  as  is  apparent  from  inspection  of  the  figure,  and 
is  kept  in  its  place  by  the  ring  or  cap,  shown  in  section  at  m m,  Fig.  3433.  The  action  of  the  ratchet- 
vheel  is  plainly  restrained  to  one  direction  by  means  of  the  click  g and  spring  h,  so  that  when  the  han- 
dle is  moved  with  a backward  pull,  the  drill  does  not  move. 

In  working,  the  conical  point  of  the  brace  is  placed  under  a temporary  framing  of  cast-iron;  the  tool 
being  thus  fixed  is  set  in  motion  by  means  of  the  handle  c,  the  drill  being  pressed  down  when  neces- 
sary, or,  in  technical  language,  “ kept  to  its  work,”  by  unscrewing  the  upper  portion  or  nut  a,  by  means 
of  a piece  of  pointed  iron  which  enters  a hole  cut  for  that  purpose,  and  obviously  urges  the  drill  down- 
ward. 

Such,  with  some  unimportant  modifications,  is  the  form  in  which  this  very  useful  implement  has  till 
recently  been  constructed.  Its  advantages  may  be  enumerated  in  few  words : it  requires  less  exertion 
than  any  form  of  brace  or  drill-stock  previously  introduced,  and  it  performs  its  work  with  greater  accu- 
racy. It  is  not,  however,  free  from  defects ; the  ratchet-wheel,  click,  and  spring,  are  liable  to  derange- 
ment, and  require  to  be  frequently  replaced,  and  the  noise  which  is  produced  in  working  the  instrument 
is  far  from  agreeable.  These  objections  are  obviated  by  an  arrangement  recently  proposed  by  Me 
Shanks  of  Johnstone,  England,  which,  we  think,  will  be  found  in  every  respect  superior  to  the  old  form, 
and  only  requires  to  be  more  generally  known  to  insure  its  preference  and  adoption.  The  principal 
peculiarity  of  Mr.  Shanks’s  hand-drill  is  the  substitution  of  a spiral  steel  band,  or  clutch,  embracing  the 


3432.  3433. 


732 


TOOLS. 


drill-stock,  and  acting  upon  it  by  friction  for  the  more  complicated  combination  of  ratcliet-wlieel,  click, 
and  spring.  Fig.  3435  shows  an  elevation,  and  Fig.  3486  a section  of  this  improved  form  of  the  tool, 
a is  the  hallow  nut  for  adjusting  the  drill  to  different  lengths,  b the  screw  fur  feeding  the  drill,  c the 
handle  of  the  same  form,  and  worked  in  the  same  manner  as  that  already  described,  but  made  with  a 
cylindrical  socket  c',  which  embraces  the  spiral  riband  k,  and  of  which  Fig.  3437  is  a detached  view 
This  spiral  riband  or  clutch  iti  bored  truly  cylindrical  to  fit  the  drill-stock  e,  and  rests  without  being 
fixed  upon  a collar  at  the  lower  end  cf  the  stock  ; it  is  fixed  to  the  upper  part  of  the  socket  c'  by  the 
screw  l,  and  the  washer  m secures  all  these  parts. 


3435.  343G. 


3437.  3438. 


The  mode  in  which  the  tool  works  will  be  sufficiently  obvious  from  the  above  description  and  an  ex- 
amination of  the  section,  Fig.  3436.  When  the  handle  c is  turned  in  the  direction  in  which  the  drill  f 
cuts,  the  clutch  k by  its  friction  firmly  embraces  the  drill-stock  e,  and  turns  the  drill,  however  great  the 
resistance  may  be.  When  the  handle  is  returned  the  clutch  relaxes  and  slips  upon  the  stock,  thereby 
preventing  the  return  of  the  drill. 

The  class  of  tools  wTkich  come  within  the  general  description  of  rose-bits,  countersinks,  wideners,  or 
broachers,  is  far  too  numerous  to  admit  of  any  specific  description  in  an  article  like  the  present.  Some 
are  intended  partially  to  enlarge  a hole  previously  drilled,  others  to  do  so  throughout  its  entire  depth. 
M.  Lenseigne,  a French  mechanician,  has  made  a great  and  decided  improvement  in  the  form  of  his 
broaches.  It  is  a well-ascertained  fact  that  pentagonal  broaches  do  not  perform  their  work  very  accu- 
rately, more  especially  when  applied  to  enlarge  a hole  drilled  through  a thin  plate  of  metal.  The  mo- 
tion of  the  brace  has  a tendency  to  render  the  hole  sensibly  larger  at  the  mouth.  To  correct  this  defect 
some  workmen  turn  the  broach  truly  cylindrical  and  then  remove  a portion  of  two  sides  with  a file,  as 
is  showm  in  the  sectional  view,  Fig.  3438  : the  part  a,  which  is  a segment  of  a circle,  bears  against  the 
sides  of  the  bole,  and  serves  as  a conductor,  and  whilst  the  acute  angular  edge  b quickly  removes  the 
material,  the  obtuse  angle  c,  which  follows,  corrects  any  inequality  of  cutting.  This  form  of  broach  is 
unquestionably  preferable  to  any  previously  introduced ; nevertheless  it  has  this  defect:  if  a chip  of 
metal  gets  between  the  round  part  a of  the  broach  and  the  side  of  the  bole,  the  angular  edge  b is 
necessarily  thrust  forward,  and  the  truth  of  the  work  is  destroyed.  To  avoid  this  difficulty,  M.  Len- 
seigne gives  to  his  broaches  the  form  shown  in  section  in  Fig.  3439.  Here  there  are  three  segments  of 
a cylinder  which  serve  as  guides,  and  the  metal  i9  removed  by  the  obtuse  angular  edges.  A tool  thus 
formed  cuts  nearly  as  fast  and  much  more  accurately  than  that  shown  in  Fig.  3438 ; it  also  possesses 
the  advantage  of  being  more  easily  made  than  those  which  are  either  pentagonal  or  hexagonal. 

We  have  now  to  consider  the  method  of  cutting  a screw  or  spiral  thread  upon  any  cylinder  of  metal 
by  a manual  operation.  Before  describing  the  tools  by  w7hich  this  effect  is  produced,  we  propose  to  lay 
before  the  reader  a brief  analysis  of  Mr.  Joseph  Whitworth’s  excellent  and  thoroughly  practical  essay 
on  a Uniform  System  of  Screw  Threads,  as  applied  to  bolts  and  screws,  used  in  fitting  up  steam-en- 
gines and  other  machinery.  The  difficulty  of  ascertaining  the  exact  pitch  of  any  particular  thread,  es- 
pecially when  it  is  not  a submultiple  of  the  common  inch  measure,  occasions  extreme  embarrassment, 
au  evil  which  would  be  completely  obviated  by  uniformity  of  system,  the  tnread  becoming  constant  for 
a given  diameter.  The  same  principle  would  also  supersede  the  costly  variety  of  screwing  apparatus 
required  in  many  establishments,  and  remove  the  confusion  and  delay  occasioned  thereby ; it  wTould 
likewise  prevent  the  waste  of  bolts  and  nuts  which  is  at  present  unavoidable. 

It  does  not  appear  that  any  combined  effort  has  been,  hitherto,  made  to  attain  so  desirable  an  object ; 
as  yet  there  is  no  recognized  standard,  and  this  will  cease  to  be  a matter  of  surprise  when  it  is  consid- 
ered that  any  standard  must,  to  a great  extent,  be  arbitrary.  On  the  one  hand,  it  is  impossible  to  de 
duce  a precise  rule  from  mechanical  principles,  or  from  any  number  of  experiments ; and,  on  the  other, 
the  nature  of  the  case  is  such  that  mere  approximation  would  be  unimportant  and  unsatisfactory,  ab- 
solute identity  of  thread  being  indispensable.  To  how  great  an  extent  the  choice  of  thread  is  arbitrary 
will  appear  from  a cursory  consideration  of  the  principles  affecting  it.  Without  attempting  to  discuss 
these  in  detail,  which  would  be  foreign  to  the  present  purpose,  it  may  he  interesting  to  notice  the  gen- 
eral outline  and  bearings  of  the  subject. 

The  use  of  the  screw-bolt  is  to  unite  certain  parts  of  machinery  in  close  and  firm  contact,  and  it  is 
peculiarly  adapted  for  this  purpose  by  the  compact  form  in  which  it  possesses  necessary  strength  and 
mechanical  power.  The  extreme  familiarity  of  the  object  tends  to  prevent  the  observation  of  its  pecu- 
liar fitness,  yet  among  all  the  applications  of  mechanics  there  is,  perhaps,  no  instance  of  adaptation 
more  remarkable.  The  ease  with  which  distinct  parts  of  machinery  can  be  united,  the  firmness  of  the 
union,  and  the  facility  with  which  they  may  he  separated,  are  conditions  of  the  utmost  importance, 
Which  by  no  other  contrivance  could  be  combined  in  an  equal  degree. 


TOOLS. 


73S 


While,  however,  the  utility  of  the  screw  in  this  application  is  abundantly  obvious,  it  is  by  no  means 
evident  what  may  be  the  precise  formation  most  advantageous  under  all  circumstances.  No  exact  data 
of  any  kind  can  be  obtained  for  calculation,  and  the  problem  will  be  found  to  be  capable  only  of  ap- 
proximate solution. 

The  principal  conditions  required  in  the  screw-bolt  are  power,  strength,  and  durability — the  latter 
having  reference  to  the  wear  occasioned  by  frequent  fixing  and  unfixing.  But  none  of  these  conditions 
can  be  reduced  to  any  definite  quantity.  We  cannot,  for  example,  determine  the  exact  amount  of  pow7er 
necessary  to  draw  the  parts  of  a machine  into  due  contact,  of  the  precise  degree  of  strength  which  may 
suffice  for  resisting  the  strains  to  which  they  may  be  exposed.  Hence  we  cannot  lay  down  any  rule 
for  determining  the  diameter  of  the  screw-bolt  required  for  a given  purpose.  Practical  men  can  judge  of 
the  proper  size  with  considerable  accuracy,  but  they  have  no  means  of  ascertaining  it  with  absolute 
precision. 

If  the  diameter  be  given,  and  it  be  required  to  find  the  proper  thread,  the  nature  of  the  question  is 
not  essentially  altered.  The  amount  neither  of  power  nor  of  strength,  nor  indeed  any  other  condition, 
is  thereby  determined.  A certain  limit  is  assigned,  but  within  that  limit  the  proportions  of  strength 
and  power,  <fcc.,  may  vary  indefinitely  according  to  the  actual  formation  of  the  thread.  There  are  three 
essential  characteristics  belonging  to  the  screw  thread,  namely,  pitch,  depth,  and  form.  Each  of  these 
may  be  indefinitely  modified  independently  of  the  others,  and  any  change  will  more  or  less  affect  the 
several  conditions  of  power,  strength,  and  durability.  The  mechanical  power  of  the  screw  clearly  de- 
pends on  the  pitch,  which,  for  a given  diameter,  determines  the  angle  of  the  inclined  plane,  and  on  the 
form  of  thread  which  regulates  the  direction  in  which  the  force  applied  w'ill  act.  The  strength  of  the 
screw,  as  regards  the  thread,  varies  with  each  of  the  three  characters ; in  the  centre  part  being  as  the 
area,  it  is  little  affected,  except  by  change  of  depth.  The  durability  of  the  thread  also  depends  chiefly 
on  its  depth,  and  the  proper  degree  of  the  latter  is  determined  principally  with  reference  to  this  condi- 
tion. In  the  selection  of  the  thread  considerable  latitude  of  choice  will  be  found  to  prevail  with  refer- 
ence to  all  the  characteristics ; therefore  no  definite  rule  can  be  given  for  determining  any  one  of  them. 
It  may  be  manifest  that  particular  threads  are  too  coarse  or  too  fine,  too  deep  or  too  shallow,  but  there 
are  clearly  intermediate  degrees,  within  which  the  choice  of  thread,  like  that  of  the  diameter,  is  arbi- 
trary, and  must  be  guided  rather  by  discretion  than  by  calculation. 

The  mutual  dependence  of  the  several  conditions  required  in  the  thread  may  be  noticed  as  having  a 
tendency  to  perplex  the  choice.  Thus,  increase  of  power,  according  to  a known  law,  is  necessarily  at- 
tended with  diminution  of  strength,  and  the  square  thread  which  has  the  advantage  in  respect  of  power 
is  proportionally  weaker  than  the  angular  thread.  A fine  thread  loses  in  strength  while  it  gains  me- 
chanically as  compared  with  one  that  is  coarser ; and  deep  threads,  while  they  are  more  durable  than 
shallow,  materially  detract  from  the  strength  of  the  bolt. 

The  selection  of  the  thread  is  also  affected  by  the  mutual  relation  subsisting  between  the  three  con- 
stituent characters  of  pitch,  depth,  and  form.  Each  of  these,  as  already  observed,  may  be  separately 
modified ; but  practically  no  one  character  can  be  determined  irrespectively  of  the  others.  The  pitch 
of  the  square  thread  is  usually  twice  that  of  the  angular,  for  the  same  diameter,  to  retain  similar  pro- 
portions of  power  and  strength.  Coarse  threads  should  be  deep  as  compared  with  fine  to  provide 
against  the  wear  from  friction,  and  a coarse  angular  thread  will  require  additional  depth,  not  only  to 
preserve  the  due  proportion  of  power,  but  also  to  prevent  the  longitudinal  strain  from  being  thrown 
too  much  sideways  on  the  nut.  Hence  each  character  acts  as  a limit  to  the  variation  of  the  others,  and 
in  some  instances,  that  is,  in  the  case  of  certain  diameters,  it  will  be  found  that  the  leading  considera- 
tions in  fixing  one  character  is  the  resulting  effect  on  another.  Thus,  in  some  of  the  smaller  sizes 
screws,  the  pitch  is  determined  principally  by  reference  to  the  depth,  a coarser  thread  being  objectiona 
ble,  because  the  extra  depth  would  obviously  tend  to  weaken  the  centre  part  of  the  bolt,  while  the 
necessary  shallowness  of  a finer  thread  would  render  it  too  liable  to  wrear  with  friction. 

The  proportionate  strength  of  the  thread  and  centre  part  of  the  screw  is  regulated  mainly  by  the 
depth  of  the  nut,  which  is  usually  of  the  same  measure  as  the  diameter  of  the  bolt.  Assuming  this 
dimension  as  fixed,  the  proportion  of  strength  between  the  two  parts  will  necessarily  vary  with  the 
different  characters  of  thread,  and  more  particularly  with  the  depth.  The  centre  part  not  being  liable 
to  wear,  while  the  thread  is  obviously  subject  to  friction  and  accidental  injury,  the  original  proportion 
of  strength  ought  to  be  considerably  in  favor  of  the  latter. 

Such  being  the  variety  and  vague  character  of  the  principles  involved  in  the  subject,  a corresponding 
degree  of  latitude  might  naturally  be  expected  in  their  practical  application.  Accordingly  we  find, 
instead  of  that  uniformity  which  is  so  desirable,  a diversity  so  great  as  almost  to  discourage  any  hope 
of  its  removal.  The  only  mode  in  which  this  could  be  attempted  with  any  probability  of  success  would 
be  by  a sort  of  compromise,  all  parties  consenting  to  adopt  a medium  for  the  sake  of  common  advan- 
tage. The  average  pitch  and  depth  of  the  various  threads,  used  by  the  leading  engineers,  would  thus 
become  the  common  standard,  which  would  not  only  have  the  advantage  of  conciliating  general  con- 
currence, but  would,  in  all  probability,  be  nearer  the  true  standard  for  all  practical  purposes  than  any 
other. 

Some  years  ago  Messrs.  Whitworth  & Co.  altered  the  threads  of  their  screwing  tackle  on  this  princi- 
ple, and  the  result  of  the  experiment  has  proved  abundantly  satisfactory.  An  extensive  collection  of 
screw-bolts  was  made  from  the  principal  workshops  throughout  England,  and  the  average  thread  care- 
fully observed  for  different  diameters.  The  4-,  1,  and  1-J  inch  were  particularly  selected,  and  taken 
as  fixed  poinls  of  a scale  by  which  the  intermediate  sizes  were  regulated,  and  the  only  deviation  made 
from  the  exact  average  was  such  as  was  absolutely  necessary  to  avoid  the  great  inconvenience  of  small 
fractional  parts  in  the  number  of  threads  to  the  inch.  The  following  table  shows  the  number  of  threads 
to  the  inch,  standard  measurb,  for  each  diameter. 


,34 


TOOLS. 


It  ■will  be  observed  that  above  one  inch  diameter  the 
same  pitch  is  used  for  two  sizes.  This  was  unavoidable 
without  introducing  small  fractional  parts ; moreover,  the 
economy  of  screwing  apparatus  is  promoted  by  repetition 
of  the  thread. 

Further,  it  is  important  to  remark  that  the  proportion 
between  the  pitch  and  the  diameter  varies  throughout  the 
entire  scale.  Thus  the  pitch  of  the  \ inch  is  one-fifth  of  the 
diameter ; that  of  the  4 inch,  one-sixth ; of  the  1 inch,  one- 
eighth  ; of  the  4 inch,  one-twelfth ; of  the  6 inch,  one-fif- 
teenth. It  is  obvious  that  more  power  is  required  as  the 
diameter  increases  : but  this  consideration  alone  will  not 
account  for  the  actual  deviation,  which  is  obviously  much 
less  than  it  would  be  if  the  scale  were  calculated  mathe- 
matically with  reference  to  the  power  required.  The  ne- 
cessary amount  of  power  must  be  determined  in  relation 
to  the  muscular  force  of  the  human  arm,  aided  by  the  lever- 
age of  the  screw-key.  Now  in  the  case  of  smaller  screws, 
there  is  a considerable  excess  of  force,  and  consequently  of 
power.  Again  in  the  larger  we  discover  a deficiency  of 
power,  for  with  all  the  leverage  that  can  generally  be  ap- 
plied, it  requires  the  united  force  of  several  men  to  fix  a 
bolt  of  six  inches  diameter.  Hence  it  is  evident  that  at  the  two  extremes  of  the  scale  the  amount  of 
power  required  is  not  the  leading  consideration  in  determining  the  pitch  of  the  thread,  and  in  the  smaller 
sizes  the  necessary  depth  of  a coarser  thread,  as  already  observed,  would  too  much  weaken  the  centre 
jrart  of  the  screw.  It  may  also  be  mentioned  that  coarse  threads  would  render  small  screws  apt  to 
work  loose  for  want  of  sufficient  hold  to  prevent  the  effect  of  jarring ; and,  on  the  other  hand,  finer 
threads  on  large  bolts,  besides  being  wTeaker,  and  consequently  less  durable,  might  render  it  a matter 
of  difficulty  to  unfix  them  when  occasion  required. 

It  may,  perhaps,  be  necessary  to  remark  that  the  threads,  of  which  the  preceding  table  shows  the 
average,  are  used  in  cast  as  well  as  wrought-iron,  and  this  circumstance  has,  doubtless,  had  the  effect 
of  rendering  them  somewhat  coarser  than  they  would  have  been  if  restricted  to  wrought-iron.  The 
variation  in  depth  among  the  different  specimens,  before  alluded  to,  was  found  to  be  greater  propor- 
tionally than  in  pitch.  The  angle  made  by  the  sides  of  the  thread  will  afford  a simple  and  convenient 
expression  for  the  depth.  The  mean  of  the  variation  of  this  angle  in  one-inch  screws  was  found  to  be 
about  55°,  and  this  was  also  very  nearly  the  mean  of  the  angle  in  screws  of  different  diameters.  As 
it  is  obviously  desirable  that  this  angle  should  be  constant,  more  especially  with  reference  to  general 
uniformity  of'  system,  the  angle  of  55°  has  been  adopted  throughout  the  entire  scale ; a constant  pro- 
portion is  thus  established  between  the  depth  and  pitch  of  the  thread.  In  calculating  the  former,  a 
deduction  must  be  made  for  the  quantity  rounded  off,  amounting  to  one-third  of  the  whole  depth— that 
is,  one-sixth  from  the  top,  and  one-sixth  from  the  bottom  of  the  thread.  Making  this  deduction,  it  will 
be  found  that  the  angle  of  55°  gives  for  the  actual  depth  rather  more  than  three-fifths,  and  less  than 
two-thirds  of  the  pitch.  The  precaution  of  rounding  off  is  adopted  to  prevent  the  injury  which  the 
thread  of  the  screw  and  that  of  the  taps  and  dies  might  sustain  from  accident. 

Two  descriptions  of  tools  are  employed  for  cutting  screws  by  hand  ; namely,  the  screw-plate  and  the 
screw-stock,  with  movable  dies.  The  first,  and  doubtless  the  most  ancient  form,  is  simply  a flat  plate 
of  steel,  assuming  the  shape  of  a file,  having  a tang  and  handle  at  one  or  both  ends  ; in  this  plate  are 
one  or  more  series  of  graduated  screwed  holes,  so  that  by  passing  the  bolt  or  pin  successively  through 
several  a finished  screw  is  obtained.  This  form  of  tool,  however  modified  in  its  construction,  is  obvi- 
ously imperfect,  and  but  rarely  used  except  for  screws  under  § inch  diameter. 

The  first  decided  improvement  with  which  we  are  acquainted  is  due  to  Mr.  Peter  Keir,  who  intro- 
duced a cutter,  let  into  a groove  sunk  in  one  of  the  dies,  which  follows  the  lead  obtained  by  the  dies, 
and  deepens  the  thread.  This  arrangement  is  more  especially  applicable  to  square-threaded  screws. 

In  1828,  Mr.  J.  Jones  submitted  to  the  Society  of  Arts  of  London  an  improved  form  of  scr.ew-stock 
and  tap,  for  which  he  received  the  thanks  of  the  society.  In  this  case,  also,  a cutter  is  used,  secured 
by  clamps  on  the  face  of  the  screw-stock,  which  necessarily  follows  the.  lead  obtained  by  the  dies,  and 
completes  the  screw  in  an  expeditious  manner.  Thq  altered  form  of  tap  is  a combination  of  the  taper 
and  plug  tap,  the  part  towards  the  point  being  conical,  and  the  upper  part  cylindrical.  The  threads 
are  rounded  off  both  at  top  and  bottom,  and  the  tap  is  fluted  with  four  or  more  rectangular  grooves, 
one  side  of  which  is  in  a line  with  the  centre,  thus  giving,  in  a cross  section  of  the  tap,  a form  some- 
what similar  to  a ratchet-wheel.  About  one-third  of  the  threads  have  their  tops  filed  down  to  diminish 
the  quantity  of  surface  in  contact,  by  which  much  labor  is  saved,  as  the  greater  part  of  the  power  re- 
quisite for  screwing  in  the  usual  way  is  expended  in  overcoming  the  friction,  and  not  in  cutting  away 
the  superfluous  metal.  This  form  of  tap  answers  perfectly  well  for  nuts  not  exceeding  one  incli  and  a 
quarter,  but  for  those  of  larger  size,  as  two  or  three  inches,  it  is  advisable  to  insert  a cutter  in  the  body 
of  the  tap  just  at  the  part  where  the  cone  terminates,  by  which  nearly  the  whole  of  the  metal  is  cut 
out,  and  the  upper  or  plug  part  of  the  tap  has  nothing  to  do  but  to  equalize  and  smooth  the  thread. 

In  1838,  M.  Gouet  proposed  a new  form  of  screw-stock  with  four  dies,  two  of  which  were  conductors 
or  guides,  and  the  other  two  acted  as  a screw-cutting  or  chasing  tool.  In  the  Bulletin  de  la  Societie 
Industrielle  de  Mul house,  we  find  a description  of  two  forms  of  screw-stoqjk,  and  an  expanding  tap  by 
M.  Lamoriniere.  The  first  is  composed  of  three  dies,  two  of  which  are  of  tempered  steel,  and  the  third 
of  wood,  intended  merely  to  serve  as  a conductor.  The  second  has  four  dies,  very  narrow  and  directly 
opposite  to  each  other,  which  are  made  to  approach  by  means  of  a circular  plate,  holloaed  in  an  ellip- 


Diameter 
in  inches. 

Threads  to 
the  inch. 

Diameter 
in  inches. 

Threads  to 
the  inch. 

3 

TF 

24 

2 

44 

i 

20 

n 

4 

IB 

18 

24 

4 

3 

8 

16 

21 

H 

1 

7B~ 

14 

3 

3-J- 

i 

12 

si 

H 

& 

8 

11 

H 

34 

4 

10 

3f 

o 

7 

9 

4 

3 

1 

8 

44 

-B 

n 

7 

44 

- B 

H 

7 

4 

2J 

it 

6 

5 

2J 

14 

6 

54 

9 3. 

- 8 

it 

5 

5i 

H 

5 

5f 

24 

it 

44 

6 

24 

TOOLS. 


735 


3440. 


tical  shape,  and  its  circumference  cut  into  teeth.  With  regard  to  the  expanding  screw-tap  the. object 
of  the  inventor  appears  to  have  been  to  dispense  with  a series  of  taps  of  different  sizes,  to  cut  rather 
than  press  out  the  metal,  and  to  allow  sharpening  on  a grindstone  when  the  cutting  edges  become  im- 
paired. M.  Waldeck  also  invented  a screw-stock  with  a series  of  cutters,  which  produced  either  angu- 
lar or  square  threads,  and  the  same  mechanician  subsequently  introduced  further  improvements  with 
regard  to  taps.  The  screw-stock  invented  and  patented  by  Mr.  Joseph  Whitworth,  of  Manchester,  next 
claims  our  attention.  Of  this  tool  there  are  two  forms  ; the  first  is  rather  complicated : the  dies,  of  which 
there  are  three,  work  in  as  many  eccentric  curves  sunk  in  a metal  disk,  whose  exterior  edge  is  cut  into 
teeth  in  the  manner  of  a tangent-wheel,  and  worked  by  an  endless  screw,  the  action  of  which  necessa- 
rily causes  the  dies  either  to  approach  or  recede  from  a common  centre. 

This  tool  cuts  the  metal  with  great  rapidity,  requires  but  little  exertion,  and  produces  very  excellent 
screws.  The  principal  objection  to  it  is,  that  the  complication  of  its  parts,  and  the  wear  and  tear  of  the 
tangent-wheel  render  frequent  repair  necessary,  more  especially  in  the  hands  of  careless  or  indifferent 
workmen. 

The  second,  or  guide  screw-stock,  is  entirely  new  in  form,  and  not  liable  to  the  same  objection  ; more- 
over, it  is  alleged  by  the  inventor  that  it  will  cut  a screw  scarcely  inferior  to  that  obtained  in  a slide- 
lathe  from  a true  guide.  The  thread  produced  is  not  only  true,  and  of  the  exact  pitch  required,  but 
. perfectly  formed  throughout,  being  cut  clean,  without  distortion  of  the  metal. 

In  all  these  respects  the  advantage  of  the  guide  over  the  common  screw-stock  is  remarkable.  The 
latter  will  not  cut  a screw  in  any  degree  perfect ; the  thread,  besides  being  irregular,  is  never  of  the 
right  pitch ; it  is  also  more  or  less  swollen  by  the  violence  done  to  the  metal,  so  that  the  diameter  of 
the  screw  is  frequently  found  to  exceed  that  of  the  blank-bolt  in  which  it  is  cut.  These  defects  are 
attended  with  the  most  serious  practical  inconvenience ; they  frequently  render  it  extremely  difficult  to 
obtain  a fit  between  the  screw  and  the  nut,  and  consequently  occasion  a considerable  sacrifice  both  of 
time  and  labor.  They  necessarily  impair,  in  a very  great  degree,  the  efficiency  of  the  screw-bolt,  which 
cannot  possess  either  the  strength  or  mechanical  power  which  it  would  have  if  the  thread  were  cut 
clean  and  true. 

The  defects  in  question  are  variously  modified  according  to  the  size  of  the  master-tap  used  in  cutting 
the  dies.  If  they  have  been  cut  by  a master-tap  double  the  depth  of  the  thread,  larger  in  diameter 
than  the  bolt  to  be  screwed,  they  will  act  very  well  at  first,  and  the  thread  will  be  started  true,  but, 
as  the  operation  proceeds,  they  become  altogether  unsteady  and  uncertain  in  their  action.  If,  on  the 
other  hand,  they  have  been  cut  by  a master-tap  of  the  same  size  as  the  bolt  to  be  screwed,  the  thread 
is  made  out  of  truth  in  its  origin.  They  first  touch  the  bolt  only  on  the  extreme 
point  of  their  outer  edges,  as  shown  in  Fig.  3440,  a being  the  die,  and  b the  pin  or 
bolt.  Further,  they  have  neither  sufficient  guide  nor  steady  abutment  till  the  oper- 
ation is  on  the  point  of  completion.  It  is  not  unusual  to  employ  a master-tap  of  an 
intermediate  size.  In  this  case,  however,  it  is  obvious  that  the  dies  will  combine  in 
a modified  degree  the  defects  peculiar  to  each  of  the  cases  already  mentioned.  In 
the  guide-stock  this  perplexity  is  entirely  obviated,  and  the  dies  act  with  full  advantage  from  the  com- 
mencement of  the  operation  to  its  conclusion.  They  are  cut  by  a master-tap  double  the  depth  of  the 
thread,  larger  in  diameter  than  the  screw-blank ; while  their  general  form  and  the  direction  in  which 
they  are  moved  forward,  are  'such  as  to  preserve  their  cutting  power,  and  steadiness  of  action,  undi- 
minished to  the  full  depth  of  the  thread. 

The  plan  of  the  guide-stock  will  be  easily  understood  from  Fig.  3441.  The  interior  of  the  stock  is 
shown  in  dotted  lines  through  the  top-plate  a,  which  is  fastened  by  the  screws  b b'  b" ; c is  a stationary 
or  fixed  die;  dd'  are  moving  dies  simultaneously  brought  up 
by  a piece  e,  sliding  in  a recess  in  the  stock,  and  bearing  with 
a distinct  incline,  as  shown  by  dotted  lines,  against  the  back  r 

of  each  die.  The  piece  e terminates  with  a square-threaded  f<_  -J  , 

screw  e',  and  is  drawn  up  by  a nut  f on  the  outside  of  the  &Eggj 
stock.  The  dies  having  been  cut  by  a full-sized  master-tap,  as 
already  mentioned,  the  curve  made  by  their  outer  edges  is  that 
of  the  blank-pin  or  bolt  they  are  intended  to  screw.  Hence, 
in  starting  the  thread  they  bear  at  all  points  of  the  common 
curve,  and  the  impression  made  by  indentation  is  an  exact  copy  of  the  thread  of  the  die.  The  parts  in- 
dented serve  as  a steady  guide  to  the  dies  in  cutting  round  the  blank-pin.  A groove  in  the  stationary 
die  facilitates  the  operation.  Four  cutting  edges  are  brought  into  action,  at  points  of  the  circumference 
nearly  equidistant ; so  that  by  little  more  than  a quarter  turn,  the  thread  is  completely  started  round 
the  pin,  and  the  difficulty  involved  in  the  operation,  by  the  common  screw-stock,  is  entirely  removed. 

After  the  thread  is  started,  the  fixed  die  serves  principally  as  a guide  and  abutment  for  the  others. 
The  moving  dies  are  peculiar  both  in  regard  to  their  form  and  direction,  which  depend  on  the  piston  of 
the  arc  in  the  shank  of  the  die.  The  two  sides  have  each  a different  inclination  to  the  arc.  As  the  die 
moves  forward  one  side  becomes  prominent  towards  the  screw-bolt,  and  its  cutting  edge  continues  in 
contact  with  the  thread,  till  it  is  cut  to  the  full  depth  required.  The  prominent  sides  of  the  moving 
dies  are  those  turned  towards  each  other. 

The  direction  of  the  common  die  in  screw-stocks,  of  the  old  form,  is  necessarily  towards  the  axis  ot 
the  screw-bolt.  In  the  guide-stock  the  direction  of  the  moving  dies  is  that  of  two  planes  meeting  be- 
yond the  centre  of  the  stock,  in  a line  parallel  to  the  axis  gf  the  screw-bolt,  and  considerably  behind  it. 

This  direction  is  determined  by  reference  to  the  change  which  takes  place  in  the  relative  position  of 
the  screw-bolt  as  the  thread  is  cut  deeper.  One  of  the  three  dies  being  stationary,  there  must  necessarily 
be  a constant  change  in  the  position  of  the  screw-bolt  in  relation  to  the  two  others,  the  effect  of  which, 
if  nut  counteracted,  would  be  to  deprive  the  cutting  edges  of  the  requisite  prominence ; but  by  giving 
them  the  direction  before  mentioned,  the  proper  degree  of  prominence  is  secured,  notwithstanding  the 


3441. 


736 


TOOLS. 


change  of  position,  and  the  latter  when  combined  with  the  eccentricity  of  the  dies,  so  far  from  being 
any  impediment  to  their  action,  materially  assists  it.  The  newly  formed  thread  is  thereby  kept  in  con- 
tact with  the  dies,  for  some  distance  behind  their  cutting  edges,  affording  them  the  same  kind  of  sup 
port  throughout  the  operation  which  they  have  at  the  commencement ; when,  as  already  observed,  the 
curve  made  by  their  outer  edges  is  coincident  with  that  of  the  screw-blank.  This  continued  support, 
which  is  necessary  to  steady  their  action,  could  not  be  obtained  without  a change  in  the  position  of  the 
screw-bolt.  They  would  otherwise  acquire  too  much  clearance  as  they  form  the  thread  deeper,  and 
their  cutting  edges  would  be  apt  to  dig. 

The  steadiness  of  the  guide-stock,  and  its  easy  action  in  screwing,  are  equally  remarkable.  In  using 
it,  not  one-half  the  force  consumed  by  the  common  stock  is  required.  The  inner  edges  of  the  moving 
dies,  which  principally  act  in  cutting  out  the  metal,  are  filed  olf  to  an  acute  angle;  this  enables  them 
to  cut  with  extreme  ease,  and  without  in  any  degree  distorting  the  thread,  while  they  take  off  shavings 
similar  to  those  cut  in  the  lathe ; their  action  in  cutting  is  in  effect  the  same  as  a chasing-tool,  to  which 
indeed  they  bear  an  obvious  resemblance  in  form,  and  they  may  be  sharpened  on  a grindstone  in  the 
same  manner. 

A practical  difficulty  has  hitherto  attended  the  use  of  the  screw-stock,  arising  from  the  wear  of  the 
taps  and  dies.  The  tap  becomes  less  in  diameter,  and  consequently  taps  the  hole  too  small,  while  the 
opposite  effect  takes  place  with  the  dies,  which,  being  unable  to  cut  a full-sized  thread,  leave  the  screw 
too  large.  The  only  mode  of  counteracting  this  two-fold  error,  so  as  to  obtain  a fit  between  the  screw 
and  the  nut,  is  by  forcing  the  dies  forward  till  they  have  reduced  the  diameter  of  the  screw  a propor- 
tionate quantity,  and  from  what  has  been  before  observed,  it  is  manifest  that  this  cannot  be  done  in  the 
case  of  common  dies,  without  injury  to  the  thread.  In  using  the  guide-stock,  on  the  contrary,  it  is 
attended  with  no  disadvantage,  and  lest  the  diameter  of  the  screw  should  inadvertently  be  reduced 
more  than  necessary,  figures  are  stamped  on  the  sides  of  the  nut/,  to  indicate  when  the  thread  is  full. 

We  have  now  to  describe  another  screw-stock.  This  tool  is  constructed  on  the  principle  of  the  ordi- 
nary screw-stock,  with  such  additions  and  alterations  as  appeared  necessary.  The  principal  objection 
to  the  old  form  is,  that  the  metal  is  rather  pressed  out  than  cut,  at  the  expenditure  of  much  force  ; in 
that  now  under  consideration,  one  die  acts  as  a guide,  and  the  other  as  a cutter,  by  which  arrangement 
not  only  is  a perfect  thread  produced,  but  the  tenacity  of  the  metal  is  preserved  and  less  power  em- 
ployed. 

Figs.  3442  and  3443  show  Mr.  Bodmer’s  improved  screw-stock,  with  the  lid  removed  in  a plan  and 
longitudinal  section  ; a a ' is  the  box  made  either  of  steel,  wrought,  or  cast  iron ; b the  vibrating  tool  or 
cutting-die,  which  is  fixed  in  the  die-holder  c,  in  such  a manner  as  to  accommodate  itself  to  the  inclina- 
tion of  the  thread  when  the  die  begins  to  cut  on  the  surface.  The  die  may  also  be  a perfect  fit  in  the 
die-holder  c,  but  in  that  case  it  must  be  cut  to  a larger  diameter  than  the  screw  itself  would  require,  as 
usually  done  in  common  stocks ; d is  the  guide-die  recessed  into  the  stock  a a',  and  which  may  be  bored 
out  to  the  full  diameter  of  the  bolt  or  pin  to  be  screwed,  or  tapped  in  the  ordinary  manner.  The  guide- 
die  d is  prevented  from  turning  by  a small  key  e ; the  screw/,  in  the  die-holder  c,  is  not  only  the  handle 
or  lever  by  which  the  stock  is  worked,  but  also  advances  the  cutting-die  b as  the  operation  proceeds. 
The  cutting  die-holder  c is  recessed  into  the  stock,  in  a manner  similar  to  d,  and  has  as  much  room  at 
x and  x as  is  necessary  to  allow  that  part  of  the  cutting-die  which,  when  the  stock  is  turned  in  the  op- 
posite direction  would  drag,  to  recede  out  of  the  thread  so  as  to  clear  the  thread  and  particles  of  metal 
cut  out  during  the  operation,  by  which  arrangement  the  cutting-die  will  preserve  its  keen  edge.  Sup- 
pose the  operation  of  screwing  to  have  been  commenced  at  the  bottom  of  a pin,  and  the  stock  arrived 
at  the  top  ; the  handle  or  screw  / will  require  to  be  advanced  a little,  and  then  the  stock  is  ready  to 
work  in  the  opposite  direction.  It  is  evident  that  the  moment  the  handles  ff  are  pulled  by  the  work- 
man, the  die  will  bite  on  that  side  which  is  moved  deeper  by  the  pull,  and  recede  out  of  cut  on  the 
opposite  side ; it  will  therefore  act  and  cut  like  a tool  in  a lathe  or  planing  machine,  and  preserve  its 
keen  edge  much  longer,  and  remove  filaments  of  metal  much  more  easily  than  dies  constructed  in  the 
ordinary  way. 


344‘i.  3445.  3444. 


Fig  3444  is  an  end  view  of  the  stock;  Fig.  3445  a ground  plan  and  an  end  view  of  the  cutting  die- 
holder,  and  Fig.  3446  the  lid  of  the  stock  fitting  the  bevel  or  half  V grooves  of  the  same ; Fig.  3447  is 
a plan  and  section  of  the  guide-die  d,  and  Fig.  3448  shows  a mode  of  regulating  the  play  or  motion  of 
the  cutting-die  b,  by  means  of  set-screws. 

' Fig.  3449  is  a ground  plan,  and  Fig.  34^0  a section  of  a stock  with  two  cutting-dies  moving  in  a 
lateral  direction;  a a' is  the  stock  or  frame;  bb'  the  handles  or  set-screws,  acting  upon  the  dies  cc', 
which  are  perfect  fits  in  the  stock,  and  against  which  the  cutting-dies  dd'  slide  laterally.  These  dies 
are  confined  between  two  plates  which  are  screwed  or  riveted  to  the  stock  in  the  ordinary  manner.  It 
is  evident  that  the  two  cutting-dies  dd',  when  tightened  up  against  the  piece  which  is  to  be  screwed. 


TOOLS. 


737 


will  recede  in  the  contrary  direction  to  that  of  the  pull,  as  much  as  there  is  space  left  between  the  dies 
and  the  side  of  the  stock,  and  in  so  doing  will  operate  in  the  manner  already  described  with  reference 
to  the  vibrating  dies. 

3450.  3449. 


Fig.  3451  shows  a longitudinal  and  end  view  of  one  of  these  taps.  After  having  been  finished  to 
nearly  the  right  measure  in  the  screwing  lathe,  the  taps  are  subjected  to  the  operation  of  a mechanism 
in  a tap-cutting  lathe,  by  means  of  which  the  convolute  form  is  given. 


3451. 


The  advantage  of  this  construction  of  tap  is  evident,  because  not  only  is  the  top  of  the  thread  eased 
in  a convolute  form,  as  usually  done  by  hand,  but  likewise  the  bottom ; the  sides  of  the  thread  also  are 
tapered,  or  relieved,  in  the  same  proportion,  so  that  the  tap  cuts  like  an  ordinary  turning-tool,  instead 
of  making  its  way  through  the  metal  by  sheer  pressure. 

The  annexed  table  indicates  the  number  of  threads  per 
inch  both  for  angular  and  square  threads. 

To  describe,  within  the  limits  of  a brief  article,  the  various 
tools  used  among  the  different  classes  of  turners  is  manifest- 
ly impossible.  They  are  so  infinitely  diversified  both  in 
form  and  size,  according  to  the  necessities,  the  ingenuity, 
and  frequently,  perhaps,  the  prejudice  of  those  who  use 
them,  that  a volume  would  scarcely  suffice  to  do  justice  to 
the  subject. 

Gravers,  triangular,  square,  round,  pointed,  heel  or  hook, 
and  screw  tools,  with  various  other  nameless  sorts,  the  con- 
trivance of  individual  skill,  are  used  in  turning  hard  bodies, 
such  as  bone,  ivory,  and  the  metals. 

The  graver  is  made  from  a square  bar  of  steel  cut  off  by 
an  oblique  plane  at  the  end,  which  forms  a lozenge  or  dia- 
mond face,  and  produces  two  inclined  edges,  at  two  of  the 
flat  sides  of  the  bar ; these  are  inclined  opposite  ways,  so 
that  the  graver  serves  either  for  left  or  right  hand  work  by 
merely  turning  it  one  quarter  round  to  bring  up  another 
side.  The  point  formed  by  the  acute  angle  in  which  the 
two  inclined  edges  meet,  is  better  adapted  for  cutting  than 
any  other  form,  and  is  exceedingly  strong;  the  flat  sides 
give  it  an  excellent  bearing  upon  the  rest.  Another  conve- 
nience of  the  graver  is  the  ease  with  which  it  may  be  sharp- 
ened, an  object  of  considerable  importance  in  turning  hard 
metal ; it  only  requires  to  be  held  on  the  grindstone  at  the 
proper  angle  to  grind  the  diamond  face  away,  and  thus  make  sharp  edges  with  the  two  flat  sides.  The 
graver  is  principally  used  to  rough  the  work,  its  point  being  applied  to  cut  grooves  all  over  the  surface 
till  it  is  true,  and  then  the  welved  edge  of  the  graver,  or  a square,  or  round  tool,  makes  it  smooth,  and 
of  a proper  figure. 

Triangular  and  square  tools  are  so  denominated  from  their  respective  sections  being  of  these  figures 
— they  are  flat  at  the  end.  The  former  have  three  cutting  edges,  namely,  each  arris  in  a longitudinal 
direction ; the  latter,  which  are  principally  used  for  turning  brass,  have  four,  that  is,  each  arris  at  the 
extremity. 

Hound  tools  have  the  edges  of  a semicircular  form,  and  are  used  for  forming  hollow  mouldings. 

The  pointed  tool  has  two  inclined  edges,  forming  a point,  which  cut  grooves  in  any  piece  of  work,  or 
its  edges  may  be  used  to  turn  shoulders  either  right  or  left. 

Heel-tools  are  used  for  turning  wrought-iron,  steel,  and  copper ; they  are  made  with  all  the  edges 
already  described,  but  the  end  where  the  edge  is  formed  is  bent,  so  that  when  it  is  presented  to  the 
work  in  a proper  direction,  the  handle  is  inclined  upwards  in  such  a position  that  the  end  of  it  will  rest 
upon  the  workman’s  shoulder,  and  he  holds  it  down  firmly  with  both  hands,  the  heel  of  the  tool  being 
at  the  same  time  supported  on  the  lathe-rest.  The  metals  above  mentioned,  being  of  a fibrous  texture, 
turn  away  in  a connected  shaving ; the  tools  are  therefore  presented  in  the  direction  of  a tangent  to  the 
work,  but  as  the  drift  of  the  work  would  force  the  tool  endways,  it  is  necessary  to  have  a heel  or  angle 
which  is  placed  immediately  upon  the  rest : then  the  long  handle  serves  to  guide  and  fix  it,  and  by  ele- 
vating the  end  its  edge  cuts  deeper. 

Cast-iron  is  turned  by  hook-tools ; their  edges  are  formed  in  various  ways,  but  invariably  very  obtuse, 
being  nearly  a right  angle ; in  turning  they  are  held  in  such  a position  that  a line  bisecting  the  angle  of 
the  edge  is  made  to  point  nearly  to  the  centre,  and  as  the  metal  is  usually  hard  and  refractory,  they 
Vol.  II.— 47 


V-Threads. 

Square  Taper-threads. 

Diameter 

Threads 

Diameter 

Threads 

in  inches. 

per  inch. 

in  inches. 

per  inch. 

5 

77f 

18 

5 

TF 

9 

3 

8 

16 

3. 

8 

9 

7 

TF 

14 

7 

TF 

8 

4 

12 

4 

7 

y 

TF 

11 

TB 

7 

5 

8 

11 

8 

7 

1 1 

TF 

10 

1 1 

TF 

7 

l 

10 

f 

6 

1 3 

TF 

9 

1 3 

TF 

6 

7 

F 

9 

7 

B 

6 

1 5 

TF 

8 

1 5 

TF 

6 

i 

8 

i 

5 

7 

4 

H 

7 

H 

4 

if 

6 

1 3. 

1 8 

3 

H 

6 

n 

3 

M 

5 

if 

2f 

if 

5 

if 

24 

TOOLS. 


i 38 


arc  made  with  a hook,  which,  being  laid  over  the  rest,  acts  as  a lever,  and  causes  the  edge  to  approach 
to  or  recede  from  the  work  by  merely  raising  or  depressing  the  end  of  the  handle. 

Screw-tools  are  very  important  appendages  to  a lathe,  and  in  many  cases  indispensable ; they  are 
usually  made  in  pairs,  namely,  an  outside  and  an  inside  tool,  and  the  teeth  of  both  should  be  so  accu- 
rately cut  that  on  being  placed  together,  the  teeth  of  the  one  in  the  intervals  between  the  teeth  of  the 
other,  they  should  exactly  fit,  even  to  tire  exclusion  of  light.  It  may  probably  appear  fastidious  to 
insist  on  this  rigid  perfection  in  a tool  which  is  apparently  of  simple  and  easy  construction  ; a little 
consideration,  however,  will  show  that  unless  the  teeth,  whatever  be  their  shape,  are  similar  in  every 
respect,  it  will  be  impossible  to  cut  an  accurate  thread,  since  if  one  tooth  be  in  the  least  degree  larger 
than  the  others,  it  will  necessarily  destroy  the  proportion  of  the  thread. 

Many  methods  have  been  suggested  to  enable  the  mechanic  to  cut  his  screw-tools.  M.  Seguier,  a 
distinguished  amateur  turner,  recommends  that  a model  be  taken  in  lead  or  soft  brass,  by  impression  of 
the  required  screw,  and  then  to  place  the  pattern  so  obtained  and  the  blank  tool  back  to  back  in  a vice, 
and  with  a triangular  file  remove  the  steel,  until  the  projecting  teeth  exactly  coincide  with  the  model. 
To  this  we  object  that  the  form  of  a triangular  file  does  not  agree  with  the  shape  of  a screw-thread — it 
is  much  too  obtuse ; what  is  called  a slitting  file  is  certainly  more  suitable.  With  very  great  care  and 
dexterity  in  the  use  of  the  file,  this  method  may  answer,  but  the  operation  demands  an  aptitude  and 
precision  of  hand  rarely  attained — added  to  which  the  loss  of  time  and  risk  of  failure  are  scarcely  com- 
pensated by  the  probability  of  success. 

We  now  proceed  to  explain  a method  very  generally  adopted  to  cut  the  teeth  in  screw-tools.  A 
piece  of  cast-steel  is  turned  cylindrical,  and  being  suspended  between  the  centres  of  the  lathe,  is  made 
to  revolve ; upon  the  surface  of  this  cylinder  a series  of  concentric  and  equidistant  circles  are  cut  by 
means  of  a screw-tool,  or  a simple  V-tool,  which  is  held  firmly  and  in  a fixed  position  against  the  steel 
cylinder.  When  the  teeth  are  sufficiently  raised  by  the  cutting  action  of  the  tool,  the  cylinder  is  re- 
moved from  the  lathe,  and  gaps  or  notches  cut  across  its  surface  in  a diagonal  direction,  so  as  to  give  to 
the  teeth  a cutting  edge.  It  is  then  hardened,  and  tempered  to  a straw-color.  This  is  technically  called 
a hob,  or  hub. 

The  great  objection  to  this  method  is,  that  it  produces  perpendicular  and  not  inclined  teeth  in  the 
screw-tool.  This  however,  is  easily  remedied  by  cutting  a regular  helix,  instead  of  merely  concentric 
circles,  upon  the  surface  of  the  hob ; or  still  more  readily  by  employing  a common  plug-tap,  which  an 
swers  the  purpose  perfectly  well. 

We  will  now  suppose  either  a hob  or  plug-tap  to  be  made  to  revolve  between  the  centres  of  the  lathe. 
The  workman  takes  a blank  screw-tool,  which  must  be  well  annealed,  and  applies  its  face  to  the  re- 
volving hob ; being  careful  to  hold  the  tool  very  firmly,  yet  not  to  allow  the  hob  at  the  commencement 
to  bite  too  greedily,  and  supplying  oil  to  the  surface  of  the  hob  or  tap,  which  essentially  assists  the 
operation.  The  blank  tool  may  be  held  either  above  or  below  the  centre  of  the  hob.  The  latter  is 
shown  in  Fig.  3453,  and  is  in  some  respects  preferable  to  the 
former,  as  it  affords  a better  purchase  for  the  tool.  The  method 
practised  in  Manchester  of  cutting  screw-tools,  is  in  many  re- 
spects similar  to  that  we  have  just  described,  except  that  it 
requires  the  aid  of  change-wheels  and  a slide-lathe.  Never- 
theless, as  many  of  the  details  are  common  to  both,  the  obser- 
vations we  are  about  to  make  will,  in  some  measure,  apply  to  manual  as  well  as  mechanical  power. 

The  first  thing  is  to  cut  the  hob,  or  hub,  which  is  effected  by  a self-acting  slide-rest.  It  is  simply  a 
screw  cut  on  the  surface  of  a solid  cylinder  of  cast-steel,  with  diagonal  grooves  cut  across  the  thread  ot 
the  screw  to  act  as  cutters,  as  shown  in  Fig.  3452  ; the  two  necks  of  the  hob  have  concave  holes  drilled 
in  the  ends  to  carry  the  centres  of  the  lathe. 

The  hob  is  placed  between  the  centre  points  of  the  lathe,  by  means  of  a dog  or  catch  attached  to  one 
end  in  the  usual  way-.  Change-wheels  are  then  put  on  to  connect  the  mandrel  or  spindle  with  the 
guide-screw  of  the  lathe,  and  which  carries  along  the  slide-rest.  The  wheels  are  so  arranged  that  one 
turn  of  the  mandrel  causes  the  slide-rest  to  travel  a distance  exactly  equal  to  one  thread.  The  blank 
which  is  to  be  cut  is  firmly  screwed  down  in  the  tool-box  of  the  slide-rest,  and  made  to  stand  above  the 
centre  of  the  hob,  as  shown  in  Fig.  3454.  It  is  then  pressed,  by  the  screw  of  the  slide-rest,  against  the 
hob ; and  the  lathe  being  put  in  motion  causes  the  tool  to  traverse  along  and  against  the  hob,  cutting  it 
as  deep  as  may  be  thought  necessary.  The  face  of  the  tool,  when  cut,  is  a segment  of  a circle,  varying, 
of  course,  according  to  the  diameter  of  the  hob. 


3452.  5343. 


3454.  3455.  3456. 


Fig.  3455  is  a side  view  of  the  tool  in  this  condition  ; but  this  form  is  not  found  sufficiently  economical 
n practice,  since  it  can  only  be  ground  and  sharpened  to  a particular  point,  as  to  b , for  when  ground  to 
/,  as  from  a to  c,  it  ceases  to  cut,  owing  to  the  top  of  the  tool  being  then  as  far  from  the  screw  to  be 
cut  as  the  bottom.  The  method  adopted  to  obviate  this  difficulty  is  to  give  the  tool  an  angular  instead 
of  a circular  face,  and  this  is  managed  in  the  following  way : the  screw-tool  is  removed  from  the  slider- 
rest,  and  as  the  hob  revolves,  the  workman  elevates  and  depresses  the  end  of  the  tool  which  is  in  his 
hand,  so  as  to  present  different  points  of  the  face  to  the  cutting  action  of  the  hob,  until  by  degrees  he 
succeeds  in  obtaining  a perfectly  angular  face,  which  allows  the  tool  to  be  ground  nearly  or  quite  to  the 
bottom,  with  a certainty  of  preserving  a good  cutting  edge.  In  order  to  fix  the  blank  which  is  intended 


TOOLS. 


739 


to  make  an  inside  screw-tool,  in  the  slide-rest,  some  little  contrivance  is  necessary,  the  stem  is  usually 
bent,  and  afterwards,  when  cut,  set  straight  previously  to  hardening. 

The  handles  of  turning-tools,  it  may  be  premised,  must  be  varied  in  size,  according  to  the  manner  in 
which  they  are  intended  to  be  held.  For  heavy  work,  more  especially  when  the  lathe  is  turned  by 
machinery,  they  must  be  sufficiently  long  to  reach  to  the  shoulder,  upon  which  one  end  rests  during  the 
operation  of  turning,  besides  being  held  by  both  hands  of  the  workman  at  the  same  time.  In  using  the 
foot-lathe  the  tools  are  held  by  both  hands  only,  and  the  handles  are  rarely  more  than  half  the  length 
required  in  the  former  instance. 

The  socket-handle  for  turning-tools,  Fig.  3456,  is  an  extremely  ingenious  and  useful  appendage  to  the 
lathe,  as  it  is  equally  applicable  to  slide-rest  tools.  This  handle  is  9 J inches  long ; the  brass  socket  a a' 
has  a longitudinal  slot  b b’ , which  terminates  at  the  circular  hole  c.  This  socket  is  confined  by  the  steel 
ring  d d',  which  has  at  one  side  a steel  set-screw  e,  and  at  the  other  a pincbing-screw  f which  necessa- 
rily contracts  the  aperture,  and  consequently  grips  the  tang  of  a tool  placed  within  it.  The  slot  b b’,  as 
well  as  the  opening  for  the  tang  of  the  tool  and  the  pinching-screw,  are  more  clearly  shown  in  the  end 
view. 

The  tool-gage  is  a very  simple  and  convenient  method  of  ascertaining  whether  a tool  is  ground  oi 
formed  to  the  proper  angle.  It  consists  of  a planed  plate  of  metal,  on  whose  surface  there  is,  at  one 
end,  fixed  a conical  steel  pin,  whose  taper,  or  the  angle  formed  by  the  sides  of  the  cone  with  the  surface 
of  the  plate,  is  exactly  that  which  is  proper  for  the  cutting  face  of  the  tool.  The  angle  formed  by  the 
sides  of  the  cone  and  the  surface  of  the  base  plate  should  be  about  three  degrees.  By  using  this  gage, 
all  difficulty  of  forming  the  tools  to  the  proper  angle  is  at  once  removed.  Moreover,  this  same  gage  will 
answer  for  every  kind  of  planing  or  turning  tool  of  whatever  size. 

We  now  proceed  to  a very  important  practical  inquiry,  namely,  the  velocity  at  which  tools  cut  most 
advantageously  for  different  kinds  of  material. 

It  cannot,  we  apprehend,  have  escaped  the  observation  of  such  of  our  readers  who  are  in  the  habit  of 
turning  metal,  that  if  a velocity  exceeding  certain  prescribed  limits  be  imparted  to  the  material,  the 
edge  of  a cutting-tool  applied  to  reduce  the  surface  of  that  material  is  brought  to  a soft  state  and  ren- 
dered obtuse.  This  is  an  acknowledged  fact,  and  many  ingenious  contrivances  have  been,  from  time  to 
time,  introduced  to  meet  the  exigency,  of  the  case,  or  in  other  words,  to  regulate  the  speed  of  the  lathe- 
mandrel  according  to  the  hardness  and  diameter  of  the  metal  or  other  substance  to  be  turned.  It  is 
commonly  supposed  that  for  wood  the  velocity  cannot  be  too  great,  yet  this  is  probably  a vulgar  error, 
since  if  we  allow  the  speed  to  pass  certain  limits  the  tool  necessarily  becomes  hot,  loses  its  temper,  and 
ceases  to  cut.  Wrought-iron  requires  a slow  motion,  and  cast-iron,  above  all,  ceases  to  be  affected  by 
the  edge  of  the  tool,  unless  a very  slow  and  regular  motion  is  preserved,  as  it  appears  to  act  by  abrasion, 
and  actually  grinds  away  the  face  of  the  tool. 

The  opinion  of  practical  men  is  much  divided  on  this  point— some  name  from  ten  to  fifteen  feet  per 
minute  as  a maximum  velocity,  others  allow  thirty  to  forty  feet,  whilst  others  again  regard  this  as  the 
minimum  speed  which  should  be  given  to  cast-iron,  in  order  to  obtain  the  greatest  effect  from  the  tool. 

For  turning  or  boring  cylinders,  or  indeed  any  substance  of  which  the  diameter  is  nearly  equal 
throughout,  a uniform  velocity  fully  answers  the  purpose,  since  the  speed  can  easily  be  increased  or 
diminished  by  means  of  conical  pulleys  placed  in  opposite  directions,  as  also  by  many  other  mechanical 
contrivances*  which  are  too  familiar  to  practical  men  to  require  any  extended  description  on  this  occa- 
sion. Suppose,  for  example,  we  have  a cylinder  of  wood  of  considerable  diameter  to  turn,  we  devise 
some  lViethod  to  control  the  speed,  as,  for  instance,  by  diminishing  the  diameter  of  the  fly-wheel,  and 
increasing  that  of  the  pulley  or  mandrel-wheel ; by  this  means  the  motion  is  made  slower,  and  in  some 
respects  in  proportion  to  the  diameter  of  the  material.  Had  the  cylinder  been  composed  of  cast-iron 
instead  of  wood,  we  should  have  pursued  a somewhat  similar  course,  but  carried  to  further  limits  than 
that  we  have  just  described.  The  facility  afforded  by  two  elongated  cones,  fixed  in  opposite  directions, 
as  regards  their  respective  diameters — the  one  attached  to  or  in  immediate  connection  with  the  ffy- 
wheel,  and  the  other  on  the  lathe-mandrel — enables  us  to  regulate  the  velocity  with  a precision  that  in 
many  operations  is  of  the  highest  importance ; but  it  must  be  remembered  that  the  advantageous  effects 
of  this  arrangement  are  limited  to  the  circumference,  or  perimeter. 

The  back-geer  lathe,  Fig.  2538,  p.  179,  answers  the  purpose  perfectly  well  for  cylindrical  turning.  In 
this  arrangement  the  driving-cone  b and  pinion  p are  connected,  and  may  either  run  loose  or  be  locked 
to  the  spur-wheel  w,  but  in  the  former  case  the  speed  of  the  lathe-spindle,  and  consequently  whatever  is 
attached  to  it,  is  greatly  reduced,  as  indeed  is  manifest  from  inspection  of  the  engraving ; for  sujjposing 
the  spur-wheel  w and  pinion  p to  have  respectively  52  and  13  teeth,  and  the  spur-wheel  h and  pinion  i 
on  the  back-geer  spindle  also  52  and  13  teeth,  tire  ratio  of  speed  of  the  driving-cone  to  that  of  the  lathe- 
spindle  would  be  as  16  to  1 ; or,  in  other  words,  the  latter  would  perform  1 revolution  for  every  16  rev- 
olutions of  the  former. 

M.  Armengaud,  a distinguished  French  engineer,  has  arranged  the  different  degrees  of  velocity 
applicable  to  the  several  mechanical  operations  of  turning,  boring,  drilling,  &c.,  in  the  following 
manner : 

The  velocity  at  the  circumference  of  the  material,  or  of  the  tool  for  turning  or  planing  cast-iron,  should 
be  from  7 to  8 centimetres-)-  per  second. 

The  velocity  of  the  tool  at  its  circumference  for  widening  or  broaching  cast-iron  is  from  4 to  5 cen- 
timetres per  second. 


* Those  who  wish  to  investigate  the  subject  will  gather  much  information  from  the  specification  of  Mr.  Bramah’s  patent, 
long  since  expired. 

+ The  centimetre,  according  to  Professor  Millington,  is  equivalent  to  0-393  of  an  English  inch,  and  M.  Armengaud  states 
that  the  latter,  compared  with  the  French  inch,  is  as 25  : 27  very  nearly;  that  is  to  say,  the  French  inch  containing  27 
millimetres,  the  English  vuch  contains  only  25  mills.  4. 


740 


TOOLS. 


Diameter 
in  inches. 

Revolutions 
of  spindle  per 
minute. 

Diameter 
in  inches. 

Revolutions 
of  boring-bar 
per  minute. 

i 

50 

i 

25 

2 

25 

2 

12-5 

3 

16-67 

8 

833  - 

4 

12-50 

4 

6-25 

5 

10 

5 

5 

6 

8-32 

6 

4-16 

7 

7-15 

7 

3-57 

8 

6-25 

8 

3125 

9 

5'55 

9 

2-77 

10 

5- 

10 

2-5 

15 

3-33 

15 

1-66 

20 

2-50 

20 

1-25 

25 

2 

25 

1 

30 

1-667 

30 

0-833 

35 

1-430 

35 

0-714 

40 

1-250 

40 

0-425 

45 

1-12 

45 

0-56 

50 

1 

50 

0 5 

60 

0-834 

60 

0-417 

70 

0-716 

70 

0-358 

80 

0-626 

80 

0-313 

90 

0-554 

90 

0-278 

100 

0-50 

100 

0 25 

The  velocity  of  cast-iron,  turned  by  a hook-tool,  held 
and  guided  by  the  hand  of  the  workman,  to  finish  or 
complete,  is  12  centimetres. 

For  iron  turned  by  means  of  the  slide-rest,  the  velo- 
city at  the  circumference  of  the  work  is  about  14  cen- 
timetres. When  the  metal  is  turned  by  hand-tools,  the 
speed  at  its  circumference  is  from  18  to  20  centime- 
tres to  rough  out,  and  from  28  to  30  centimetres  to 
finish. 

The  difference  of  velocity  of  the  work  or  the  tool 
when  the  turning  is  effected  mechanically  or  by  the 
hand,  is  deduced  from  the  obvious  fact,  that  in  the  for- 
mer case  the  contact  between  the  tool  and  the  work  is 
constant  and  invariable,  whilst  in  the  latter  it  is  inter- 
mittent. 

The  foregoing  velocities  are  equally  applicable  to 
drills  or  cutters  in  boring  machines. 

The  lateral  progress  of  the  tool  varies  according  to 
the  power  of  the  machine  ; it  is  in  general  from  4 to  -J- 
of  a millimetre  for  each  revolution  of  the  work,  never- 
theless it  should  be  less  for  drills. 

The  annexed  table  indicates  the  average  degree  of 
speed,  as  well  for  turning  as  boring. 

If  we  have  occasion  to  turn  a plane  surface  accu- 
rately true,  the  motion  of  the  lathe-mandrel,  or  what 
is  the  same  thing,  the  substance  affixed  to  it,  requires 
to  be  accelerated  or  retarded  in  a ratio  proportioned 
to  the  progress  of  the  tool,  either  to  or  from  its 
centre ; then  that  portion  of  the  plane  where  the 
tool  takes  effect  would  pass  its  edge  always  at  the  same  velocity;  and  if  a proper  speed  be  obtained 
in  the  first  instance  not  only  will  the  tool  preserve  its  originally  keen  edge  for  a very  considerable  time 
uninjured,  but  the  surface  produced  by  its  action  would  be  nearly  perfect.  This  control  and  command 
of  the  movement  obviously  require  that  it  be  continuous ; since  if  the  lathe  be  stopped,  a mark,  or  false 
cut,  as  it  is  termed,  will  be  the  unavoidable  result. 

Under  ordinary  circumstances,  regular  motion  in  surface-turning  is  not  only  prejudicial  in  relation  to 
its  effects,  but  it  also  involves  great  waste  of  time.  We  will  suppose  that  a speed  suitable  for  the  cir- 
cumference and  the  proximate  parts  is  obtained,  it  is  evident,  as  we  approach  the  centre,  the  rotary 
movement  becomes  less  effective ; until  at  length  near  the  centre  it  produces  little  or  none,  and  the 
work  does  not  proceed  at  all.  The  reason  of  this  is  obvious ; the  velocity  continues  unaltered,  while 
the  diameter  of  the  material  is  progressively  reduced.  It  is  also  manifest  as  an  inevitable  consequence 
to  uniform  motion  in  surface-turning,  that  presuming  a suitable  velocity  be  communicated  when  the  tool 
is  at  the  greatest  distance  from  the  centre  of  rotation,  if  it  be  made  to  advance  regularly  towards  the 
same  point,  similar  uniform  speed  being  continued,  the  cutting  edge  of  the  tool  would 
not,  on  its  arrival  at  the  centre,  be  more  deteriorated  than  if  the  velocity  had  been  in- 
creased in  a proportionate  ratio  to  its  progress  towards  the  centre.  This,  we  believe, 
is  an  admitted  fact  by  competent  judges ; but  it  must  be  remembered  there  would  be  a 
sacrifice  of  nearly  one-lialf  of  the  time  employed.  This  statement,  extraordinary  as 
it  may  appear,  is  nevertheless  susceptible  of  mathematical  demonstration,  a mode  of 
proof  which,  we  presume,  few  will  feel  inclined  to  dispute.  Let  the  parallelogram,  a 
bed,  Fig.  3457,  represent  the  time  that  would  be  required  to  turn  a surface.  Draw 
the  diagonal  line  b c ; bisect  the  line  a c at  e,  e c at  g,  and  g c at  i ; then  draw  the  lines 
ef,  g h,  and  ij  parallel  to  a b. 

Let  c represent  the  centre,  a c equal  the  radius,  and  a b equal  the  circumference,  or  time  of  one  revo- 
lution at  its  greatest  diameter;  therefore,  the  lines  ef,  g h,  and  ij,  will  also  represent  their  circumfer- 
ence, or  time  of  one  revolution  at  their  respective  radii  at  eg  and  i;  and  as  the  lines  a b,  ef,  gh,  and 
ij,  are  one-half  the  length  of  each  other,  so  will  their  revolutions  be  performed  in  similar  proportions  of 
time,  and  the  velocity  of  the  lathe-mandrel  will  be  increased  in  the  inverse  ratio,  as  the  length  of  the 
lines  a b,  ef,  g h,  and  ij ; consequently,  the  right-angled  triangle  a b c will  represent  the  time  that  would 
be  required  to  turn  a surface,  when  the  velocity  of  the  lathe-mandrel  is  increased  in  the  manner  already 
described.  The  parallelogram  abed  will  represent  the  time  that  would  be  required,  if  the  velocity  re- 
main unaltered — that  is,  from  the  moment  the  tool  is  applied  to  the  surface  at  its  greatest  diameter,  to 
its  arrival  at  the  centre ; for  if  the  length  of  the  line  a b represent  the  time  of  one  revolution  at  its 
greatest  diameter,  the  line  cd  will  similarly  represent  the  time  of  one  revolution  when  the  tool  reaches 
the  centre  ; therefore,  as  the  length  of  the  iine  c d is  equal  to  a b,  so  will  all  the  intermediate  revolutions 
be  performed  in  similar  spaces  of  time. 

This  inquiry  may  be  usefully  applied  to  determine  the  period  of  time  necessary  for  surface-turning. 
Thus,  if  we  wish  to  know  what  time  would  be  required  to  turn  a plane  surface  of  cast-iron,  the  diame- 
ter being  twenty-four  inches,  to  make  fifty  revolutions  or  cuts  in  each  inch  of  the  radius,  and  to  pass  the 
tool  at  the  rate  of  15  feet  per  minute:  Multiply  the  circumference,  say  75‘39  inches  by  the  radius 
equal  12  inches,  then  multiply  the  product,  904'68,  by  the  number  of  revolutions  or  cuts  in  one  inch  of 
the  radius,  in  this  instance  50,  this  will  give  45,234  inches ; divide  this  by  12,  to  reduce  it  to  feet,  and 
we  have  3769'5  ; divide  again  by  15,  which  gives  251'3  minutes,  and  lastly  dividing  by  60,  we  have  4 
hours,  ll-3  minutes;  consequently  this  would  be  the  time,  if  each  revolution  were  performed  in  equal 


TOOLS. 


741 


portions  of  time,  but  if  the  speed  of  the  lathe-mandrel  be  regulated  so  that  the  surface  to  be  turned 
shall  always  pass  the  tool  at  the  same  velocity,  then  the  time  required  to  perform  the  work  will  be 
only  one-half  of  the  above  ; for  in  this  case  we  must  multiply  the  radius  by  one-half  of  the  circumfer- 
ence, as  that  will  be  a mean  proportion  of  the  lengths  of  all  the  intermediate  revolutions. 

We  have  now  arrived  at  a very  important  and  interesting  inquiry: — namely,  the  principle  and  mode 
of  action  of  automatic  or  self-acting  tool-machines. 

If  we  consider  the  separate  and  distinct  parts  which  combined  make  up  a machine,  whether  simple 
or  complex,  to  be  disunited  and  viewed  in  detail,  we  shall  find  that  their  constituent  parts,  however  nu- 
merous, are  composed  either  entirely  or  partially  of  certain  original  geometrical  figures,  so  that  it  is  evi- 
dent the  more  nearly  the  configuration  of  each  individual  part  approaches  strict  mathematical  truth, 
the  more  regular  and  perfect  will  be  the  performance  of  the  machine. 

But  the  accuracy  and  precision  of  workmanship  here  predicated,  and  which  peculiarly  distinguishes 
the  machinery  of  the  present  day,  is  obviously  unattainable  by  mere  manual  dexterity ; it  is  principally 
to  be  attributed  to  the  slide-rest. 

The  invention  and  introduction  of  this  tool  may  justly  be  considered  an  era  in  the  history  of  construc- 
tive mechanism ; it  has  entirely  superseded  both  manual  labor  and  dexterity,  which  previously  were  re- 
quired ; added  to  which,  it  enables  us  to  produce  work  infinitely  superior,  and  in  a much  shorter  space 
of  time  than  could  be  effected  by  hand-turning : so  many  and  so  conclusive  are  the  beneficial  results  con- 
sequent to  the  introduction  of  this  tool  that  it  is  not  affirming  too  much  to  assert  that  nearly  all  the  im- 
provements in  modern  machinery  are  in  a greater  or  less  degree  to  be  attributed  to  its  almost  universal 
application  in  some  or  other  of  its  many  and  varied  forms. 

It  constitutes  no  part  of  the  present  inquiry  to  investigate  the  principles  of  turning,  except  so  far  as 
is  absolutely  necessary  to  illustrate  the  subject  in  hand.  Let  us  suppose  then,  that  instead  of  the  tool 
being  held  and  guided  by  the  hand  of  the  workman,  assisted  merely  by  muscular  strength,  the  same 
tool  is  firmly  fastened  to  the  lathe-rest,  so  that  during  the  operation  of  cutting,  it  could  be  slid  along  the 
bed  of  the  lathe,  in  a direction  parallel  to  the  axis  of  the  work,  the  result  of  this  operation  would  ne- 
cessarily be  a cylinder ; if,  however,  the  tool  move  in  a line  forming  an  angle  with  the  axis  of  the  man- 
drel, a conical  form  would  be  obtained,  and  if  it  operate  at  right  angles  to  the  same  axis  a plane  surface 
would  be  the  result.  Such  are  the  elementary  principles  on  which  this  important,  and  in  many  respects 
invaluable  tool  is  constructed,  the  details  of  which,  and  the  different  forms,  we  defer  for  the  present, 
thinking  it  preferable  in  the  first  instance  to  describe  the  machine  of  which  it  forms  an  appendage. 

One  of  the  primary  and  most  indispensable  requisites  of  a well-constructed  lathe  is,  that  the  centre  of 
the  cone-spindle  should  coincide  exactly  with  the  adjustable  centre  of  the  movable  head-stock,  or,  in 
other  words,  that  each  of  these  parts  should  be  in  the  same  line,  parallel  to  the  face  of  the  lathe-bed. 

The  spindle  is  a very  important  part  of  the  lathe,  as  upon  its  truth  and  accuracy  of  motion  the  circu- 
lar rotation  of  any  work  attached  to  it  mainly  depends ; it  is  usually  made  of  iron,  but  the  working 
parts  of  the  two  extremities  are  altogether  of  steel,  which  are  hardened  after  being  turned  and  finished ; 
they  are  then  ground  in  their  places  to  fit  the  collars  or  bearings  with  finely  pulverized  Turkey  stone 
and  oil;  the  left-hand  end  lias  a hole  bored  exactly  in  its  centre  to  receive  the  point  of  a screw,  which 
supports  and  retains  it  in  its  place,  as  shown  in  Figs.  2523  and  2524,  p.  176. 

The  other,  or  right-hand  end. of  the  spindle,  is  somewhat  larger,  and  has  a conical  hole  bored  in  the 
direction  of  its  axis  for  the  purpose  of  receiving  a centre  point ; this  is  disengaged  when  necessary  by 
means  bf  any  tapered  instrument  which,  being  inserted  in  a slot  cut  in  the  mandrel,  acts  as  a lever  and 
forces  the  centre  forwards. 

In  the  larger  class  of  lathes  the  spindle  is  usually  fitted  up  to  run  in  divided  collars  of  brass  or  gun- 
metal  ; these  slide  on  V-shaped  grooves  cast  in  the  head-stock,  and  are  adjusted  to  fit  the  neck  of  the 
mandrel  or  spindle  by  means  of  screw-bolts  which  pass  through  a cap  or  plate  of  wrought-iron,  fitted  on 
the  upper  surface  or  top  of  the  head-stock. 

V arious  contrivances  have  from  time  to  time  been  suggested  to  avoid  the  inconvenience  of  a back- 
screw,  and  at  the  same  time  insure  uniformity  of  position  under  all  possible  circumstances.  The  boring  and 
turning  machine,  pp.  180,  181,  and  182,  offers  an  example  of  this  modification : here  the  sjoindle  works 
in  divided  collars,  but  has  shoulders  at  the  necks,  by  which  contrivance  all  longitudinal  motion  is  en- 
tirely avoided.  The  method  adopted  by  Mr.  Whitworth,  of  Manchester,  to  effect  this  object  is  extremely 
ingenious,  and  peculiarly  entitled  to  the  distinctive  epithet,  self-sustaining ; as  a specimen  of  the  adap- 
tation of  mechanical  means  applied  to  produce  certain  results,  it  is  probably  unrivalled. 

In  this  lathe  the  inner  journal  of  the  spindle  is  turned  conically,  but  at  two  different  angles,  that  part 
next  the  nose  being  more  acute  than  the  remaining  portion.  This  arrangement  meets  the  great  difficulty 
attendant  on  conical  bearings,  as  the  base  of  the  cone  is  opposed  to  direct  pressure,  and  consequently 
removes  all  danger  of  the  spindle  becoming  fixed  or  jammed  in  its  collar.  The  sliding  cone  which  is 
placed  upon  the  spindle  for  working  in  the  outer  bearing,  becomes,  as  it  were,  a part  of  the  spindle,  but 
having  longitudinal  motion ; it  tends  to  balance  the  effect  of  pressure  applied  directly  to  the  screw. 

The  method  shown  in  the  sectional  view,  Fig.  2532,  p.  177,  is  by  no  means  so  well  contrived  as  in  this 
case ; a set-screw  is  introduced  to  counteract  longitudinal  motion  by  direct  pressure  against  the  left- 
hand  end  of  the  spindle. 

The  movable  or  right-hand  head-stock  now  requires  consideration.  The  first  decided  step  towards 
improvement  in  this  part  of  the  lathe  may  doubtless  be  traced  to  the  substitution  of  a plain  cylinder  for 
a screw,  both  terminating  alike  in  a conical  point;  in  the  former  case  the  cylinder  turning  upon  itself, 
the  apex  of  the  cone  is  not  so  liable  to  deviation,  but  this  does  not  compensate  for  the  absence  of  regu- 
lar pressure,  which  can  be  imparted  at  will,  and  at  any  moment,  by  means  of  a screw,  and  that  in  a 
degree  exactly  required  by  the  nature  of  the  case  ; nevertheless  this  great  inconvenience  must  not  be 
overlooked,  the  screw  is  extremely  liable  to  vary  relatively  to  the  centre  line.  If,  for  instance,  either 
the  pin  or  the  thread  be  slightly  twisted,  which  it  frequently  and  unavoidably  is,  the  point  will  describe 
a small  circle  at  each  revolution,  and  however  well  and  carefully  the  thread  of  the  screw  may  be  cut 


742 


TOOLS. 


it  is  almost  impossible  to  make  it  perfectly  regular  and  mathematically  true ; consequently,  if  the  centraj 
line  of  the  cone,  -which  forms  the  point,  be  not  that  of  the  screw  itself,  the  same  effect  will  be  produced 
These  and  other  considerations  of  a like  nature  that  might  be  adduced,  probably  suggested  the  ar 
rangement  shown  in  Fig.  2538,  which  combines  the  simplicity  and  uniformity  of  position  of  the  cylinder 
with  the  mechanical  power  of  the  screw.  In  this  case  the  sliding  cylinder  in  the  head-stock  is  deprived 
of  rotary  motion,  its  outer  end  being  connected  by  a coupling  to  a second  cylinder  of  smaller  diameter, 
which  constrains  both  to  move  in  a parallel  direction  ; between  these,  a square-threaded  screw  works, 
which  is  capable  only  of  longitudinal  motion,  being  connected  to  the  aforesaid  coupling,  so  that  the 
screw  being  worked  to  the  left  hand,  compels  the  cylinder  in  the  head-stock  to  travel  with  it,  as  is  evi 
dent  from  inspection  of  the  figure. 

The  form  of  head-stock  just  described  probably  suggested  that  generally  known  as  the  cylinder  head 
stock.  This  was  invented  simultaneously,  we  believe,  by  M.  Collas,  of  Paris,  and  Mr.  Joseph  Clement, 
of  London.  The  arrangement  now  usually  adopted  is  shown  in  section  in  Fig.  3458.  The  head-stock 
is  bored  out  true  and  an  iron  or  steel  cylinder  ground  therein  so  as  to  insure  an  accurate  fit ; this  re- 
ceives a forward  and  backward  motion  from  a screw  which  is  rendered  endless  by  means  of  a collar  or 

3458.  3459. 


cap,  and  is  worked  by  a handle-wheel.  The  sliding  cylinder  is  fixed  when  requisite  by  a pinchmg- 
screw,  which  presses  against  a piece  of  iron  let  into  the  head-stock.  A sectional  view  of  another  mode 
of  fitting  up  is  given  in  Fig.  3459.  This  is  unquestionably  not  so  expensive  to  get  up  as  that  just  de- 
scribed, but  it  is  liable  to  the  objection,  that  nearly  the  whole  amount  of  pressure  is  thrown  upon  the 
driving-screw  connected  with  the  cylinder  and  attached  to  the  handle-wheel.  In  this  latter  example 
the  mode  of  fixing  the  spindle  in  its  required  position  is  superior  to  that  shown  in  Fig.  3458.  A malle- 
able iron  ring,  bored  out  so  as  accurately  to  fit  the  spindle,  is  let  into  a recess  in  the  head-stock,  and 
tightened  up  by  means  of  a handle  passing  through  a screwed  shank  projecting  from  the  ring. 

In  some  cases  it  is  desirable  to  possess  the  means  of  moving  the  shifting  head-stock  in  a direction  at 
right  angles  to  the  bed  of  the  lathe.  A very  convenient  mode  of  effecting  this  is  shown  in  Figs.  2523 
and  2524,  by  means  of  the  screw  f,  which  causes  the  head-stock  to  move  transversely,  an  arrangement 
which  is  peculiarly  applicable  to  conical  turning. 

In  heavy  lathes  the  sliding  head-stock  is  usually  moved  along  the  bed  by  means  of  a train  of  bevel- 
wheels,  as  in  Fig.  2542.  Here  a bevel-pinion  attached  to  a horizontal  spindle,  which  is  worked  when 
necessary  by  a crank-handle  fitted  upon  the  square  end  o,  gives  motion  to  a bevel-wheel  upon  one  end 
of  a vertical  shaft,  which  has  its  bearings  inside  a hollow  column  cast  in  the  body  of  the  head-stock  for 
that  purpose.  On  the  other  end  of  this  shaft  is  a bevel-pinion ; this  again  geers  with  a small  bevel- 
wheel  keyed  upon  the  spindle  p, 'which  works  in  bearings  attached  to  the  sole  of  the  head-stock  and 
also  carries  a pinion  which  works  into  the  rack  M,  fixed  upon  the  bed-plate  of  the  lathe,  and  thus  obvi- 
ously completes  the  connection,  enabling  the  workman  to  adjust  the  sliding  head-stock  in  any  required 
position  with  ease  and  facility. 

Cones  or  speed-pulleys  are  very  important  adjuncts  to  tool-machines  in  general,  and  more  especially 
the  lathe,  as  from  the  nature  of  the  operations  performed  by  it,  it  is  a primary  requisite  that  the  range 
of  variation  in  the  velocity  of  the  spindle  should  be  as  large  as  possible.  Professor  Willis  has  investi- 
gated the  mechanical  principles  of  their  adjustment  in  a very  clear  and  satisfactory  manner. 

Supposing  a pair  of  cones  or  speed-pulleys  to  be  arranged  upon  two  parallel  axes  and  in  opposite 
directions,  we  have  an  easy  mode  of  changing  the  ratio  of  the  angular  velocity  of  the  shafts  by  simply 
moving  the  belt  from  one  pair  of  speeds  to  another. 

In  this  case  it  is  evident  that  the  diameters  of  each  pair  of  opposite  pulleys  should  be  so  adjusted  that 
the  belt  shall  be  equally  tense  upon  any  pair  of  the  whole  series  ; this,  as  may  be- easily  demonstrated, 
is  attained  by  making  the  sum  of  each  pair  of  opposite  pulleys  equal  throughout  the  whole  series. 

We  have  now  to  describe  the  slide-rest,  a tool  which  has  unquestionably  contributed  more  than  any 
other  to  the  improvement  of  modern  machinery.  The  invention  of  this  truly  important  tool  is  claimed 
by  Mr.  Nasmyth  for  the  late  Mr.  Henry  Maudslay ; but,  as  it  appears  to  us,  the  conclusion  arrived  at 
by  that  gentleman  has  been  hastily  adopted  and  without  sufficient  inquiry,  inasmuch  as  a form  certainly 
similar  in  all  important  details  was  well  known  and  commonly  used  by  rose-engine  turners  long  pre- 
viously, added  to  which  we  may  remark  that  the  original  slide-rest  constructed  by  Mr.  Maudslay  for 
Mr.  Bramah  bears  so  slight  a resemblance  to  that  now  in  use  as  scarcely  to  be  capable  of  identification  ; 
moreover,  it  is  extremely  doubtful  whether  a form  of  rest,  known  as  the  parallel  rest,  as  well  as  a tool 
very  similar  in  principle,  invented  by  the  late  Earl  Stanhope  for  turning  metallic  surfaces  of  large  di- 
mensions truly  plane,  did  not  precede  the  slide-rest  of  Mr.  Maudslay. 

It  is  foreign  to  our  purpose  to  pursue  the  subject  further,  nor  are  we  disposed  to  depreciate  the  great 
merit  of  an  ingenious  and  highly  talented  engineer ; nevertheless,  as  the  principle  has  been  so  extensively 
and  so  successfully  applied  to  modern  tool  machinery,  we  have  been  solicitous  to  perform  an  act  of  jus- 
tice in  attributing  to  those  who  have  in  any  way  contributed  to  the  invention  of  this  important  tool  a 
fair  share  of  commendation. 

The  form  of  slide-rest  shown  in  Figs.  2542  and  2543  is  a very  convenient  arrangement  in  many  of  its 


TOOLS. 


74  o 


details,  and  the  one  most  commonly  adopted.  Here  J is  the  saddle-plate  upon  which  the  slide-rest  K 
is  supported,  and  the  longitudinal  slide  L which  carries  the  tool-holder  is  firmly  secured  upon  the  part 
K by  the  screw  u ; the  parallel  motion  of  the  tool-holder  is  obtained  by  means  of  the  screw  r,  and  simi- 
larly a transverse  motion  of  the  same  in  order  to  place  the  tool  in  and  out  of  cut  by  the  screw  s ; these 
necessarily  work  at  tight  angles  to  each  other,  and  the  tool  itself  is  made  fast  on  the  tool-holder  by  the 
two  clamps  u.  The  adjustment  requisite  for  setting  the  tool  to  the  work  is  effected  by  disengaging  the 
sole  K from  the  saddle-plate  J ; the  nuts  on  the  bolts  which  pass  through  the  slots,  shown  in  the  plan 
view,  Fig.  2543,  being  released,  by  this  means  the  sole  K may  then  be  moved  to  the  requisite  distance 
from  the  longitudinal  axis  of  the  lathe,  and  to  a certain  extent  in  the  line  of  that  axis  by  shifting  the 
bolts  in  the  dovetail  grooves  of  the  saddle-plate,  should  that  operation  be  more  convenient  than  to  shift 
the  latter  on  the  bed-frame  of  the  lathe. 

A transverse  adjustment  to  a limited  extent  may  be  obtained  by  means  of  the  screw  s,  and  the  tool- 
carrier  may  be  adjusted  longitudinally  by  the  screw  r. 

The  slide-rest  we  have  now  to  describe  is  due  to  the  ingenuity  of  Mr.  Joseph  Whitworth.  It  is  un- 
questionably an  excellent  specimen  of  constructive  mechanism,  combining  the  requisite  stability  with 
great  accuracy  of  motion,  and  the  manner  in  which  the  details  are  worked  out  displays  considerable 
ability  and  mechanical  talent.  Figs.  3460  and  3461,  the  latter  being  a section,  show  the  rest  set  for 
facing  a circular  plate ; that  is,  the  motion  of  the  upper  slide  is  in  a line  at  right  angles  to  the  lathe-bed 
A A,  which  is  bolted  in  the  usual  manner  to  the  supports  B B. 

The  saddle  upon  which  is  placed  the  carriage  of  the  rest  is  simply  a broad  and  strong  plate  of  cast- 
iron  C C,  planed  true  and  finished  by  scraping  upon  both  horizontal  faces.  The  slides  a a,  similarly 
planed  and  dressed,  are  screwed  to  the  lower  surface  of  the  saddle  on  either  side  of  the  lathe-bed,  to 
enable  it  to  traverse  with  uniform  motion  its  entire  length  without  shake  or  play,  and  so  arranged  as  to 
compensate  for  wear  and  tear  by  means  of  lateral  screws  countersunk  in  the  cheeks  of  C 0. 

When  the  saddle  is  required  to  remain  stationary  during  the  work,  as,  for  example,  when  a circular 
or  other  plate  is  to  be  faced,  it  is  firmly  fixed  on  the  lathe-bed  A A by  means  of  a single  screw-bolt  b, 
the  nut  of  which  is  screwed  up  by  the  lever-handle  c. 

The  carriage  of  the  rest  is  composed  of  three  principal  parts  : the  first  D D,  which  rests  upon  the  sad- 
dle, and  is  susceptible  of  different  positions ; the  second  E is  a plate  movable  upon  the  preceding,  and 
the  third  F which  carries  the  tool.  The  base  or  carriage  is  of  cast-iron,  planed  and  finished  by  scraping 
not  only  on  the  two  horizontal  faces,  but  also  on  the  two  upper  lateral  edges,  which  are  angular  like 
those  of  the  lathe-bed,  so  as  to  receive  the  slides  e e fitted  on  each  side  of  the  rectangular  plate  E.  A 
screw-bolt  d,  the  square  head  of  which  is  lodged  in  a gap  sunk  in  the  saddle  C C,  serves  to  adjust  the 
carriage  D D upon  the  saddle-plate,  and  this  adjustment  obviously  depends  upon  the  diameter  of  the 
piece  to  be  turned. 

The  rectangular  plalfe  E is  rendered  movable  in  the  direction  of  the  lengtl#  of  the  carriage  D D by 
means  of  an  endless-screwy,  which  is  entirely  sunk  in  its  thickness,  and  receives  a rotary  motion  either 
from  the  handle  g or  from  the  lathe  itself.  This  endless-screw  works  in  a brass  nut  fitted  under  the 
plate  E,  and  being  deprived  of  endlong  motion,  it  necessarily  follows  that  in  its  rotation  it  imparts  a 
forward  aud  backward  motion  to  the  nut,  and  consequently  the  tool-carrier. 

The  part  F,  which  may  properly  be  designated  the  tool-carrier,  is  susceptible  of  another  movement — 
that  is,  in  a direction  exactly  at  right  angles  to  that  just  described— by  means  of  a second  endless-screw 
smaller  than  the  former ; this  is  intended  to  be  worked  only  by  the  handle  h,  and  that  in  the  event  of 
its  being  necessary  to  regulate  in  an  exact  manner  the  position  of  the  tool  with  regard  to  the  piece  upon 
which  it  is  to  operate.  This  endless-screw  works  in  a brass  nut  attached  to  the  plate  E,  and  conse- 
quently imparts  a forward  and  backward  motion  to  the  tool-carrier  F,  which  moves  between  two  slides 
screwed  upon  this  plate. 

The  tool  i,  which  is  intended  to  act  upon  the  material  either  for  turning  or  screw-cutting,  is  securely 
fixed  on  the  tool-carrier  F by  vertical  pinching-screws  jj,  which  are  screwed  through  the  thickness  of 
the  upper  plate  or  cap ; these  screws,  four  in  number,  are  placed 
at  the  anglea  of  the  cap,  an  arrangement  which  allows  the  tool 
to  be  fixed  in  different  directions,  and  in  such  a manner  that  it 
is  always  acted  upon  by  two  screws.  This  disposition  enables 
the  workman  to  employ  two  tools  which  shall  act  at  the  same 
time  or  nearly  so  upon  the  material ; for  instance,  the  one  to 
rough  out  and  the  other  to  complete  the  work. 

Motion  is  communicated  to  the  carriage,  and  consequently  to 
the  tool-slide,  by  a peculiar  arrangement  of  the  guide-screw, 
which  is  so  formed  as  to  be  alike  capable  of  performing  the  office 
of  a rack  as  well  as  that  of  a screw  > to  this  end  the  thread  is 
rounded  off  both  at  top  and  bottom,  instead  of  being  either  tri- 
angular or.  square.  It  is  thus  enabled  to  work  either  in  a nut  or 
with  a tangent-wheel. 

This  guide-screw  is  shown  at  G-,  Fig.  3460.  It  is  placed  with- 
in the  lathe-frame,  not  in  the  direction  of  the  axis  of  the  machine, 
but  rather  on  one  side,  in  order  to  screen  it  from  the  falling  turn- 
ings, and  the  nut  k,  when  needful,  is  taken  out  of  geer  by  the 
pin  l.  When  the  guide-screw  is  required  to  answer  the  pur- 
pose of  a rack — as,  for  instance,  to  bring  the  saddle,  and  consequently  the  carriage,  to  any  particular 
position — the  nut  k is  disengaged,  and  the  handle  in,  the  socket  of  which  is  fitted  on  a horizontal  spindle 
carrying  the  small  meter-wheel  n,  which  geers  with  a larger  one  o,  keyed  on  one  end  of  a vertical  shaft 
placed  in  the  centre  of  the  saddle  0,  and  on  the  other  extremity  of  this  shaft  is  a tangent-wheel  p 
which  works  with  the  guide-screw  of  the  lathe.  JNTow  as  this  last  is  deprived  of  rotary  motion,  it  is  evj 


3460. 


744 


TOOLS. 


dent  that  by  turning  the  handle  in,  the  tangent- wheel  p,  driven  as  already  described,  will  produce  pre 
ciselv  the  effect  of  a rack ; that  is  to  say,  the  saddle  and  carriage  will  receive  a traversing  motion  ic 
the  direction  of  the  length  of  the  lathe-bed. 

In  actual  work  the  saddle,  and  consequently  the  rest  itself,  is  placed  in  any  required  position,  the 
handle  in  being  removed  and  the  nut  k brought  into  connection  with  the  guide-screw  G,  which,  actuated 
and  regulated  by  a train  of  wheels  attached  to  the  lathe,  causes  the  saddle  with  its  appurtenances  t» 
travel  with  any  degree  of  speed  that  may  be  required. 

By  a peculiar  and  ingenious  arrangement,  the  guide-screw  is  made  to  drive  the  carriage  and  tool- 
carrier  in  a direction  at  right  angles  to  the  axis  of  the  lathe.  This  is  effected  in  the  following  man- 
ner : — with  the  mitre-wheel  o a similar  but  smaller  one  q geers  ; this  is  keyed  on  the  end  of  a shaft  iu 
the  same  straight  line  as  that  which  carries  the  small  mitre-wheel  n.  At  the  opposite  extremity  of  this 
axis  is  a spur-wheel  r which  geers  with  a similar  spur-wheel  s mounted  on  an  iron  spindle,  which  ter- 
minates at  the  other  end-  in  a grooved  shoulder ; this  axis  is  movable  in  a socket  which  forms  a support 
and  is  fixed  to  the  saddle  C,  and  by  means  of  an  'ingenious  contrivance  the  forked  lever  t is  made  to 
connect  or  disconnect  at  pleasure  the  spindle  that  carries  the  spur-wheel  s,  with  the  square  end  of  the 
screw  f of  the  carriage  1)  1). 

It  is  obvious,  if  we  suppose  the  saddle  to  be  fixed  on  the  lathe-bed — and  to  effect  this  it  is  merely 
necessary  to  screw  up  the  bolt  c — that  the  guide-screw  G giving  motion  to  the  tangent-wheel  p deter- 
mines the  motion  of  the  toothed-wlieels,  and  consequently  that  of  the  screw/,  which  after  this  manner 
gives  motion  to  the  carriage  and  the  tool-carrier,  to  which  we  have  given,  by  anticipation,  the  position 
shown  in  the  sectional  view,  Fig.  8461.  It  is  evident  that  when  this  transverse  motion  is  not  required, 
it  is  only  necessary  to  throw  the  wheels  out  of  geer  by  means  of  the  forked  lever  t,  and  then  these 
wheels  will  revolve  on  their  axes  without  producing  any  effect. 


\ 


The  collars  or  bearings  in  which  the  axes  of  the  bevel-wheels  n and  q revolve  freely,  are  nothing 
more  than  long  hollow  cylinders  bored  out  true,  and  fixed  on  the  saddle  or  bed-plate  c,  and  to  avoid 
the  injury  which  might  result  from  these  wheels  becoming  clogged  by  chips  of  metal,  they  are  usually 
protected  by  a metallic  cover  either  of  tin  or  sheet-brass. 

In  the  construction  of  steam-engines  and  engineering  work  generally,  there  are  a great  number  of 
parts,  such  as  steps,  bushes,  ifcc.,  which  require  their  outer  diameter  to  be  turned  truly  concentric  with 
the  hole  bored  through  them.  The  most  general  method  of  accomplishing  this,  is  by  driving  the  work 
upon  a mandrel  sufficiently  tight  to  withstand  the  action  of  the  turning-tool.  The  common  mandrel, 
which  is  perhaps  the  most  universal  adjunct  of  the  lathe,  is  a cylindrical  bar  of  steel,  turned  with  an 
exceedingly  slight  taper  to  fit  the  central  hole  of  the  work. 

The  time  lost  in  preparing  these  mandrels,  and  the  great  weight  of  useless  metal  which  must  thus 
be  kept  in  stock,  prove  serious  objections  to  their  use,  and  led  Mr.  Hick  to  the  invention  of  the  expand- 
ing mandrel,  by  which  various  sizes  of  holes  may  be  fitted. 

Figs.  3462  and  8463  represent  a longitudinal  section  and  an  elevation  of  the  mandrel,  the  expanding 
wedges  being  shown  in  two  different  positions,  a is  the  mandrel, *the  central  portion  of  which  is  turned 
conically  as  at  b.  This  cone  is  provided  with  four  dovetail  grooves  c running  in  the  direction  of  the 
axis  of  the  mandrel,  and  fitted  to  receive  the  four  wedges  dd,  shown  in  Fig.  3462,  in  their  highest  po- 
sition. The  dotted  circles  in  the  end  view  represent  the  work,  which  is  placed  upon  the  four  wedges ; 
these  are  pressed  onwards  by  the  hollow  conical  collet  e,  urged  by  the  nut  f working'  on  the  screw- 
threads  cut  on  the  mandrel.  In  this  manner  the  wedges  d are  driven  up  the  inclined  grooves,  and  thus 
fix  the  mandrel  concentrically  within  the  hole  of  the  work  so  that  any  diameter  of  hole  may  be  readily 
fitted,  which  is  within  the  range  of  the  travel  of  the  wedges. 

Another  equally  important  appendage  of  the  lathe,  is  the  universal  chuck.  Yarious  views  of  this 
chuck  are  given  in  Figs.  2542 — 2545,  pp.  180-2.  For  turning  or  boring  articles  of  a regular  external 
configuration,  this  arrangement  has  a decided  advantage  over  the  common  chuck,  where  each  adjust- 
ing screw  is  moved  separately ; and  effects  a considerable  saving  in  time,  in  setting  the  work. 

There  are,  besides  the  modification  just  referred  to,  various  other  species  of  chucks,  among  which  we 
may  class  Mr.  Bodmer’s  as  one  of  the  best. 


TOOLS. 


715 


In  this  arrangement,  the  clutches  are  expanded  and  contracted  by  means  of  a series  of  radiating 
screws,  each  of  which  carries  a pinion  geering  with  a large  central  wheel  on  the  front  plate  of  the 
chuck ; the  work  is  fastened  by  setting  the  lathe  in  motion,  and  holding  back  the  front  plate  until  the 
wheel  upon  it  shall  have  driven  in  the  clutches  worked  by  the  screws  sufficiently  far  to  grasp  it. 

The  object  of  change-wheels  applied  to  a lathe  is,  generally  speaking,  to.  obtain  a screw  of  any  re- 
quired pitch ; that  is,  in  relation  to  the  leading  or  guide  screw*  by  which  the  cutter  is  moved  in  a lon- 
gitudinal direction. 


If  a spur-wheel  be  attached  to  the  left-hand  end  of  the  lathe-spindle,  and.so  arranged  as  to  geer  with 
mother  spur-wheel  similarly  fixed  on  the  axis  of  the  guide-screw,  and  continuous  motion  be  commu- 
nicated to  the  lathe-spindle,  it  is  evident  that  this  motion  will  be  transferred  by  means  of  the  aforesaid 
wheels  to  the  saddle  of  the  slide-rest ; consequently  a screw-tool  attached  thereto,  will  receive  direct 
rectilinear  motion,  and  thus  trace  the  spiral  thread  of  a screw  on  the  exterior  surface  of  any  revolving 
cylinder  opposed  to  its  action. 

The  relative  proportions  of  these  wheels  obviously  determine  the  pitch  of  the  screw  to  be  cut,  as 
compared  with  that  of  the  guide-screw  of  the  lathe  ; so  that  if  they  are  of  equal  diameter,  or,  what  is 
the  same  thing,  have  an  equal  number  of  teeth,  the  result  will  be  a screw  of  the  same  pitch  as  that  of 
the  leading  screw ; but  if  the  driving-wheels  be  larger  than  the  driven — suppose  in  the  proportion  of 
two  to  one,  then  will  the  pitch  of  the  work  be  exactly  double  that  of  the  guide-screw,  and  if  these  pro- 
portions were  reversed  a contrary  result  would  follow. 

It  is  obvious  in  such  a case  as  we  have  here  supposed,  that,  as  the  wheel  fixed  on  the  lathe-spindle 
and  that  upon  the  guide-screw,  each  revolve  in  contrary  directions,  all  screws  cut  by  this  arrangement 
will  be  the  reverse  of  the  guide-sCrew,  or  left-hand  threaded.  In  order,  therefore,  to  cut  a right-hand 
screw,  ^t  will  be  necessary  to  introduce  an  intermediate  wheel  geering  with  both  wheels,  so  that  the 
direction  of  motion  of  the  work  shall  be  the  same  as  that  of  the  lathe-spindle. 

The  principle  of  this  arrangement  is  shown  in  Fig.  3464,  entirely  _ 

disconnected  from  the  frame-work  of  the  lathe,  and  without  strict 
regard  to  proportion,  it  being  intended  merely  to  exhibit  the  parts 
as  distinctly  as  possible.  Here  A A'  is  a portion  of  the  lathe- 
spindle,  to  which  is  attached  in  the  usual  way  a cylindrical  rod, 
for  the  purpose  of  cutting  a thread  upon  it.  G represents  the 
leading  or  guide  screw  revolving  in  suitable  bearings,  and  giving 
motion  by  means  of  a nut  to  the  saddle,  and  consequently  the 
carriage  of  the  rest,  upon  which  is  firmly  clamped  a suitable  tool 
intended  to  cut  the  screw. 

In  this  arrangement  it  is  manifest  that  every  revolution  of  the 
guide-screw  G will  cause  the  rest  to  advance  through  a space  ex- 
actly equal  to  its  own  pitch,  or,  in  other  words,  supposing  the 
guide-screw  to  have  four  threads  in  the  inch,  it  will,  in  every  rev- 
olution it  makes,  advance  the  rest,  and  consequently  the  tool  or 
cutter,  one-fourth  of  an  inch  end-long  upon  the  work,  so  that  if  the 
lathe-spindle  revolve  with  the  same  velocity  as  the  guide-screw, 
the  tool  will  produce  a screw  of  precisely  similar  pitch ; but  if,  on 
the  contrary,  AA'  revolve  with  less  velocity  than  G,  then  the 
effect  will  be  a greater  pitch,  and  vice  versa.  How  if  the  lathe- 
spindle  and  the  guide-screw  be  connected  by  a set  of  change- 
wheels,  we  have  the  means,  by  properly  choosing  the  numbers  of 
these  wheels,  to  obtain  any  desired  pitch.  This  is  practically 
etfected  by  an  intermediate  axis  which  is  supported  by  a grooved 
bearer  ; this  carries  an  arrangement  of  additional  change-wheels, 
according  to  circumstances  and  the  conditions  of  the  case.  The 
leading  or  guide  screw  which  communicates  motion  to  the  saddle  of  the  slide-rest  is  driven  by  a train 


* Screw-cutting  and  boring  machines  are  reducible  to  the  principle  of  aggregate  motion.  For  the  cutting  of  a screw  ir 
In  fact  the  tracing  of  a spiral  upon  the  surface  of  a cylinder,  and  the  motion  of  boring  is  also  the  tracing  of  a spiral  unor 


746 


TOOLS. 


of  wheels  which  are  in  connection  with  the  spindle  of  the  lathe,  it  passes  through  and  forms  the  axis  of 
a movable  piece  H,  and  at  its  extremity  carries  the  fast-wheel  1,  which  geers  with  a pinion  E ; this 
and  the  wheel  F,  wnich  geers  with  the  pinion  D upon  the  end  of  the  lathe-spindle,  are  carried  by  r 
stud  B fixed  in  a straight  slot  cut  in  the  movable  arm  H,  which'  has  likewise  a curvilinear  slot  near  its 
end,  through  which  two  fixed  studs  pass  , upon  these  studs  pinching-nuts  are  placed,  which  being 
screwed  up  tightly,  retain  it  securely,  and  by  altering  the  angular  position  of  H,  a pinion  of  greater  or 
less  diameter  than  I)  may  be  used,  and  consequently  the  motion  of  the  leading  or  guide  screw  regu- 
lated. 

Having  now  explained  the  arrangement  of  geering  necessary  for  effecting  a change  of  speed  in  the 
guide-screw,  we  shall,  for  the  sake  of  a practical  illustration,  give  determinate  values  to  the  wheels 
D F E and  J.  Thus  let  the  number  of  teeth  in  the  wheels  D and  E be  30,  and  that  in  F and  J 60  each, 
the  pitch  of  the  guide-screw  G being  -J  inch,  or  in  other  words,  that  it  lias  two  threads  per  inch.  It  is 

now  evident  that  one  complete  revolution  of  G will  advance  the  tool  through  the  space  -gy-',  and  simi- 


30  X 30 

larly  one  revolution  of  A will  advance  the  tool  through  the  space = 0'25  turns  of  G,  or  ith 

6 ^ 60  X 60  ’ 8 

inch,  and  consequently  the  pitch  of  the  screw  cut  by  this  arrangement  will  be  Jth  inch.  In  this  man- 
ner any  desired  pitch  of  screw  may  be  cut  by  proportioning  the  change-wheels  accordingly.  This  may 
be  much  facilitated,  by  arranging  the  various  pitches  of  screw’s  in  a tabular  form  and  placing  the  re- 
spective change-wheels  required  for  each  opposite  to  them,  so  that  all  computation  during  the  actual 
progress  of  the  work  is  avoided. 

In  order,  however,  to  meet  emergencies,  it  is  necessary  that  the  process  of  calculation  for  any  given 
pitch  should  be  thoroughly  understood,  and  for  this  purpose  we  shall  give  an  example  as  a guide. 
Suppose  it  is  required  to  cut  a screw  which  shall  contain  13  threads  in  the  inch.  Here  the  ratio  of 

t 23  ) 

speed  between  the  cone-spindle  and  the  guide-screw  is  required  to  be  as  6 J to  1 ^ — \ , so  that 

— t &c.  = 64.  In  this  case,  the  wheels  D and  J are  supposed  to  be  geered  together  merely 

(D)  20.  24  1 1 & o j 

by  a single  carrier-wheel ; but  as  this  arrangement  is  not  always  convenient,  we  shall  now  find  the  ratios 
of  the  wheels  as  given  in  Fig.  3464,  where  four  are  used.  Here  we  must  remember  that  the  condition 
of  the  case  is  that  the  numerator  divided  by  the  denominator  of  the  expression  (13)  shall  be  64-  We 

will  assume  28  and  56  as  the  respective  values  of  D and  J,  or  — = 2.  Hence  we  have  only  to  find 


we  have 


E 64 

such  values  of  F and  E,  so  that  — = -^  or  34,  which  informs 


D 

us  that  E must  have  34  times  as  many 


teeth  as  F.  Suppose  then  F has  32  teeth,  we  have  32  X 34  = 104  = the  number  of  teeth  in  E,  the 
whole  set  of  wheels  standing  as  follows  : D = 281,  J = 56,  F = 32,  E = 104.  This  result  is  capable 

of  verification  as  follows:  — — 2 = 2.  31.  2 ' 13,  or  the  number  of  threads  per  inch  of  the  screw  to 
28.  32  1 

be  cut.  Thus  in  all  cases  of  calculations  of  this  nature,  the  expression  in  general  terms  stands  thus  : 

(Ho.  of  teeth  in  J,)  (Ho.  of  teeth  in  E Ho.  of  threads  per  inch  of  screw  to  be  cut, 

(Ho.  of  teeth  in  D,)  (Ho.  of  teeth  in  F * Ho.  of  threads  of  guide-screw. 

The  following  table  shows  the  train  of  wheels  to  be  used  in  cutting  screws  varying  in  pitch  from  1 

to  70  threads  in  the  inch ; the  leading  or  guide  screw  is  supposed  to  have  two  threads  per  inch,  yet 

may  the  table  be  still  employed  where  the  leading  screw  has  four  threads  to  the  inch,  for  the  same 
train  of  wheels  would  suit  for  cutting  screws  of  double  fineness ; and  similarly  when  the  leading  screw 
has  only  one  thread  to  the  inch,  a screw  of  only  one-half  the  fineness  will  be  produced  with  any  train 
given  in  the  table. 

In  the  first  columns  it  will  be  observed  that  the  wheel  and  pinion  carried  by  the  stud  B are  omitted ; 
these  not  being  required  in  cutting  screws  of  the  pitches  there  stated,  are  displaced,  and  a simple  car- 
rier-wheel substituted  for  them.  To  facilitate  this  arrangement,  the  wheel  J,  on  the  leading  screw,  has 
the  boss  of  its  socket  longer  on  one  side  than  the  other ; so  that  when  reversed,  as  in  this  instance,  it  is 
brought  into  train  with  the  carrier-wheel,  placed  upon  the  stud ; and  this  again  is  placed  in  train  wTith 
the  pinion  D. 

Such  are  the  general  principles  of  screw-cutting  for  single  threads ; but  when  it  is  required  to  cut  a 
multi-threaded  screw,  it  is  evident  that  some  additional  apparatus  will  be  requisite  to  effect  the  requi- 
site exactitude  of  division,  so  as  to  bring  in  each  parallel  thread  in  its  proper  place. 


the  surface  of  a hollow  cylinder;  the  tool  being  in  both  cases  the  describing  point,  and  the  plain  cylinder  the  surface. 
Now  as  the  tracing  of  this  spiral  is  resolvable  into  two  simultaneous  motions,  one  of  revolution  with  respect  to  the  axis 
of  the  cylinder,  and  the  other  of  transition  parallel  to  that  axis,  we  have  in  the  construction  of  machines  for  boring  and 
screw-cutting  the  choice  of  four  arrangements: 

(i.)  The  cylinder  may  be  fixed  and  the  tool  revolve  and  travel.  This  is  the  case  in  all  simple  instruments  for  boring 
and  tapping  screws,  in  machines  for  boring  the  cylinders  of  steam-engines,  and  in  engineers’  boring  machines. 

(2.)  The  tool  may  he  fixed  and  the  cylinder  revolve  and  travel.  Screws  are  cut  upon  this  principle  in  small  lathes  with 
a traversing  mandrel.  ' 

(3.)  The  tool  may  revolve  and  the  cylinder  travel.  The  boring  of  the  cylinders  of  pumps  is  often  effected  upon  this 
principle. 

(4.)  The  cylinder  may  revolve  and  the  tool  travel.  Guns  are  thus  bored,  and  engineers’  screws  cut  in  the  lathe. 


TOOLS. 


747 


CD  O 

a o 

6 -2 
£ u 
P. 

No.  of 
teeth  on 

No.  of  threads 
per  inch  of  screw. 

No  of  teeth  on 

No.  of  threads 
per  inch  of  screw. 

No.  of  teeth  on 

No.  of  threads 
per  inch  of  screw. 

No.  of  teeth  on 

Mandrel  pin- 
ion D. 

Leading 
screw-wheel  I. 

Mandrel  pin- 
ion D. 

Stud-wheel  F. 

Stud-pinion 

K. 

Leading 
screw-wheel  I. 

Mandrel  pin- 
ion D. 

Stud-wheel  F. 

Stud-pinion 

E. 

tp  s 

O ^ 

o 

Mandrel  pin- 
ion D. 

fa 

3q 

3 

‘rH 

m 

tD  03 

o P 

CJ 

1 

80 

40 

84 

40 

55 

20 

60 

18 

40 

60 

20 

120 

32 

30 

80 

20 

120 

14 

80 

50 

84 

90 

85 

20 

90 

184 

80 

100 

20 

150 

33 

40 

110 

20 

120 

u 

80 

60 

84 

60 

70 

20 

75 

19 

50 

95 

20 

100 

34 

30 

85 

20 

120 

14 

80 

10 

94 

90 

90 

20 

95 

194 

80 

120 

20 

130 

35 

60 

140 

20 

150 

2 

90 

90 

94 

40 

60 

20 

65 

20 

60 

100 

20 

120 

36 

30 

90 

20 

120 

24 

80 

90 

10 

60 

75 

20 

80 

204 

40 

90 

20 

90 

38 

30 

95 

20 

120 

24 

80 

100 

104 

50 

70 

20 

75 

21 

80 

120 

20 

140 

39 

40 

120 

20 

130 

24 

80 

110 

11 

60 

55 

20 

120 

22 

60 

110 

20 

120 

40 

30 

100 

20 

120 

3 

80 

120 

12 

90 

90 

20 

120 

224 

80 

120 

20 

150 

42 

50 

140 

20 

150 

sj 

80 

130 

I2f 

60 

85 

20 

90 

22J 

80 

130 

20 

140 

44 

30 

110 

20 

120 

34 

80 

140 

13 

90 

90 

20 

130 

23| 

40 

95 

20 

100 

45 

30 

90 

20 

150 

34 

80 

150 

134 

60 

90 

20 

90 

24 

65 

120 

20 

130 

454 

40 

130 

20 

140 

4 

40 

80 

134 

80 

100 

20 

110 

25 

60 

100 

20 

150 

50 

30 

100 

20 

150 

44 

40 

85 

14 

90 

90 

20 

140 

254 

30 

85 

20 

90 

52 

35 

130 

20 

140 

44 

40 

90 

144 

60 

90 

20 

95 

26 

70 

130 

20 

140 

524 

40 

140 

20 

150 

44 

40 

95 

15 

90 

90 

20 

150 

27 

40 

90 

20 

120 

55 

30 

110 

20 

150 

5 

40 

100 

16 

60 

80 

20 

120 

274 

40 

100 

20 

110 

56 

30 

120 

20 

140 

5-J- 

40 

110 

164 

80 

100 

20 

130 

28 

75 

140 

20 

150 

60 

30 

120 

20 

150 

6 

40 

120 

164 

80 

110 

20 

120 

284 

30 

90 

20 

95 

65 

30 

130 

20 

150 

64 

40 

130 

17 

45 

85 

20 

90 

30 

70 

140 

20 

150 

70 

30 

140 

20 

150 

7 

40 

140 

Hi 

80 

100 

20 

140 

14 

40' 

150 

8 

30 

120 

Two  separate  contrivances  have  been  devised  for  this  purpose.  Pihet’s  apparatus  is  shown  in  Figs, 
8465  and  8466 ; the  former  of  which  is  a front  elevation  and  the  latter  a section  in  a line  with  the  axis 
of  the  lathe,  a is  a cast-iron  disk  cut  with  a female  screw  to  tit  the  nose  of  the  lathe-spindle,  and  on 
the  face  of  this  disk  is  fitted  the  division-plate  b,  the  tubular  portion  of  which  also  answers  for  chucking 
the  work.  The  circumference  of  this  disk  is  divided  by  notches,  into  60  equal  parts,  numbered  respect- 
ively from  0 to  60,  into  which  the  spring-catch  or  stop  c takes,  so  that  when  the  disk  a is  put  in  mo- 
tion, and^the  catch  put  down  in  any  notch  as  required,  the  whole  moves  together  as  in  one  piece. 


The  disk  b is  held  in  its  place  merely  by  friction  generated  by  the  pressure  of  the  ring  e ; this  ring 
is  shown  removed  in  Fig.  8465,  in  order  to  show  the  graduation  of  the  disk  e , which  is  bolted  to  the 
disk  a,  and  carries  in  one  portion  of  its  circumference  a screw  d.  This  screw  passes  through  the  exter- 
nal ring  e,  and  is  screwed  into  the  stop  c,  so  as  to  fix  the  latter  in  any  required  division  of  the  plate  b. 

In  cutting  a multi-threaded  screw  by  this  apparatus,  it  takes  the  place  of  the  common  chuck,  the 
workman  fixing  his  work  to  it,  by  means  of  the  radiating  screws  in  the  tubular  portion  of  b. 

Supposing  it  is  required  to  cut  a triple-headed  screw,  the  first  operation  which  is  necessary  is  the 
detaching  of  the  stop  c from  the  disk,  so  that  the  latter  may  be  turned  round  alone,  until  the  division  o 
comes  opposite  the  hole  in  the  external  ring  seen  at  e,  in  Fig.  3466  ; the  screw  d is  then  adjusted  so  as 
to  connect  the  division-plate  with  the  disk  a,  and  the  first  thread  of  the  intended  screw  is  cut  through- 
out its  whole  length.  Now  as  the  thread  is  to  be  a triple  one,  it  is  obvious  that  the  circumference  of 
the  work  must  be  divided  into  three  equal  parts,  so  that  each  thread  may  be  equidistant  when  cut; 
accordingly  the  stop  is  again  detached,  and  the  division-plate  carrying  the  work  turned  round,  until  the 
notch  20  arrives  at  the  hole  e \ the  stop  is  then  replaced,  and  the  second  thread  is  cut  in  a similar  man- 
ner as  before.  Lastly,  the  division-plate  is  moved  round,  until  the  notch  40  is  seen  through  the  hole  e, 
when  the  remaining  thread  is  cut,  the  three  having  the  same  reference  to  each  other  as  the  divisions  0, 
20,  and  40  relatively  bear  to  each  other. 


748 


TOOLS. 


In  the  production  of  the  minor  screws  and  bolts  used  in  engineering  work,  the  lathe  is  superseded  by 
the  screwing  and  tapping  machine,  in  which  the  thread  is  formed  by  a travelling  die  working  upon  the 
revolving-bolt  intended  to  be  screwed.  The  principle  of  the  action  of  this  machine  will  be  understood 
by  referring  to  Fig.  3275,  in  which  we  have  given  an  elevation,  ground  plan,  and  different  detailed 
views  of  a single  screwing  machine  of  great  simplicity.  In  this  arrangement  the  frame  containing  the 
dies  travels  upon  the  parallel  guide-rods  It  R,  the  work  being  fixed  in  the  chuck  L,  and  entered  into 
the  dies  which  are  then  contracted  until  they  embrace  the  bolt  sufficiently  to  be  drawn  along  its  surface 
by  its  revolution.  The  quick  return  motion  of  the  die-frame  is  produced  in  the  ordinary  manner  as 
applied  to  planing  machines.  This  machine  is  objectionable  on  account  of  its  want  of  compactness 
otherwise  it  is  a pretty  fair  specimen  of  its  class. 


The  double  screwing  machine  by  Messrs.  Randolph,  Elliot,  and  Co.,  of  Glasgow,  is  a much  more 
complete  and  useful  workshop  auxiliary  than  the  last,  and  has,  besides,  the  merit  of  great  compactness. 
Fig.  3467  is  a side  elevation  of  the  machine,  Fig.  3469  is  a ground  plan,  Fig.  3468  is  an  elevation  of  the 


3470. 


nut- tapping  end  and  Fig.  3470  is  a similar  view  of  the  bolt-screwing  end.  The  frame-work  of  the  ma- 
chine A A°and  the  sole-plate  B B,  are  cast  in  one  piece.  The  driving-cone  C is  supported  by  the  up- 
rio-ht  frames  near  the  centre  of  the  machine,  and  carries  a pinion  D,  of  15  teeth,  which  geers  with  ha 
wheel  E,  of  56  teeth,  keyed  on  the  smaller  screwing-spindle  F ; thus  the  relative  speeds  of  the  driving- 
tone  and  the  spindle  F are  as  3-73  to  1.  The  spindle  F again  carries  a pinion  G of  18  teeth,  geenng 


TOOLS. 


749 


with  the  wheel  H of  72  teeth,  keyed  on  the  larger  screwing-spindle  L the  ratio  of  speed  in  this 
case  being  as  4 to  1.  In  the  end  view  the  chucks  KK  are  shown  with  square  recesses,  for  the 
purpose  of  receiving  the  heads  of  taps  for  tapping-nuts.  In  the  view  of  the  contrary  or  bolt-screwing 
end,  the  chucks  L L are  provided  with  plates  grooved  for  the  purpose  of  receiving  the  screwing-dies, 
which  are  adjusted  by  means  of  two  set-screws,  which  press  against  the  backs  of  the  dies  so  as  to  suit 
them  to  any  diameter  of  bolt.  The  motion  of  the  spindles  is  stopjred  or  reversed  by  the  handles  M M, 
at  each  end  of  the  machine.  They  are  connected  by  a lever  with  the  vertical  rod  E,  which  carries  the 
shifting-strap  forks.  The  top  driving-geer  consists  of  three  pulleys,  a fixed  central  one,  with  a loose  one 
on  each  side,  all  being  on  one  shaft,  which  also  carries  a cone  of  three  speeds  exactly  similar  to  C, — 
the  last  carries  the  driving-belts  communicating  directly  with  the  machine.  The  centre  pulley  of  the 
6et  of  three  is  much  narrower  than  that  on  each  side  of  it,  so  as  to  allow  of  the  release  of  the  cross- 
strap before  the  op^i  one  comes  upon  it,  and  vice  versa.  For  another  somewhat  similar  arrangement, 
see  Figs.  3282  to  3287. 

34G9. 


formed  by  manual  labor,  a tedious  and  uncertain  process,  but  now  effected  wTith  facility  and  precision 
by  self-acting  machinery. 

In  Figs.  2974  to  2976  we  have  given  detailed  views  of  a complete  machine  for  this  purpose,  by  Mr.  A, 
Mylne,  of  Glasgow.  The  nut  to  be  cut  is  fixed  on  the  upright  spindle  of  the  support  r,  and  is  brought 
in  contact  hvith  the  revolving-cutter  x by  means  of  the  screw  y,  the  requisite  division  of  the  faces  of  the 
nut  being  effected  by  means  of  the  circular  table,  which  is  provided  with  six  equal  notches  fitted  with 
a spring-catch  from  the  lever  n.  This  machine  is  also  provided  with  a self-acting  feed  motion,  by  which 
the  nut  is  gradually  moved  up  to  the  cutter  while  in  action.  This  is  effected  by  the  shaft  c of  the  speed- 
pulley  e,  which  carries  a worm  s geering  with  the  wheel  h,  upon  the  shaft  of  which  is  fixed  a pinion 
geering  with  a rack  on  the  lower  side  of  the  table  carrying  the  nut.  This  motion  may  be  dispensed 
with  when  thought  necessary,  and  the  work  may  be  carried  forward  by  hand,  by  means  of  the  hand- 
wheel  and  shaft  b. 

This  machine  is  very  compact  and  fully  answers  the  purpose  of  dressing-nuts  of  any  number  of  sides, 
by  using  differently  divided  plates.  In  many  engineering  works,  nuts  of  all  numbers  of  sides  are  forged 
iu  swages  made  for  the  purpose ; the  accuracy  and  beauty  of  finish  of  which  is  nearly  equal  to  nuts 
cut  by  the  machine,  and  answer  all  purposes  where  extreme  finish  is  not  required,  the  expense  of  pro- 
duction being  at  the  same  time  very  greatly  diminished. 

The  subject  of  nut-cutting  leads  us  now  to  the  consideration  of  screw-keys,  by  means  of  which  all 
nuts  of  screws  used  in  the  connection  of  the  different  portions  of  machinery  are  adjusted  to  suit  the 
ever-varying  exigencies  of  mechanical  contrivances.  The  common  screw-key  with  fixed  jaws  must  be 
so  familiar  to  our  readers  as  to  render  any  description  of  it  unnecessary,  and  we  shall  therefore  point 
out  a few  examples  of  attempts  to  remedy  the  defects  of  this  most  necessary  instrument.  In  the  dis- 
section of  any  piece  of  machinery,  even  of  the  more  simple  species,  we  invariably  find  a multitude  ot 
different  sized  bolts,  the  nuts  of  which  of  course  each  require  a key  suited  to  its  own  particular  size. 
A reference  to  the  number  of  gradations  of  size  of  nuts,  given  in  a previous  portion  of  our  pages,  will 
immediately  poiut  out  the  necessity  of  some  contrivance  for  dispensing  with  the  number  of  these  instru- 
ments, and  introducing  an  adjustable  apparatus,  by  which  a number  of  different  sized  nuts  may  be 
worked  without  entailing  the  awkward  drawback  of  keeping  so  many  all  but  useless  workshop  ap- 
pendages. 

The  earliest  contrivance  for  this  purpose  is  what  is  technically  called  a monkey,  the  use  of  which, 
previous  to  the  introduction  of  the  more  refined  species  of  tools,  was  almost  universal. 

But  a more  elegant  instrument  for  this  purpose  is  the  coach-wrench,  which  is  equally  applicable  to 
the  working  of  nuts  and  all  similar  purposes. 

Our  example  of  this  key,  Fig.  3471,  is  capable  of  receiving  nuts  from  the  smallest  size  up  to  four 
inches,  and  is  of  course  sufficient  of  itself  for  all  ordinary  purposes.  The  end  jaw  a is  in  one  piece 
with  the  lever-handle  b.  The  movable-jaw  c is  mortised  to  slide  upon  that  portion  of  the  lever  between 


750 


TOOLS. 


3471. 


the  end  a and  the  fixed  stop  d\  it  is  held  in  its  place  when  set  for  any  nut  by  means  of  the  second 
lever  e,  which  works  on  a centre-pin  in  the  projecting  portion  of  the  jaw.  This  lever  also  carries  a 
projection  at  / by  which  it  is  jointed  to  a thin  wedge,  passing  between  the  top  of  the  lever  b and  the 
interior  surface  of  the  slotted  portion  of  the  movable  jaw.  Thus,  when  the  lat- 
ter is  set  to  the  size  of  nut  required,  a slight  pressure  upon  the  side  of  the  lever 
e forces  down  the  wedge,  and  secures  the  jaw  immovably.  (See  Wrench.) 

The  peculiar  merit  of  this  species  of  key  is,  that  all  allowance  for  wear  is 
made  up  by  the  wedge,  which  will  never  permit  any  looseness  in  the  jaw,  as 
the  only  difference  caused  by  the  wear  of  the  surfaces  in  contact  will  be  a greater 
travel  of  the  fixing  wedge.  Practical  men  who  have  made  use  of  those  keys 
which  are  adjusted  by  means  of  nuts  will  at  once  see  the  value  of  this  advantage. 

Next  to  the  turning-lathe  in  its  importance  to  the  engineer,  the  planing  ma- 
chine stands  foremost  in  rank  of  constructive  machines.  The  primary  idea  of 
planing  by  machinery  was  doubtless  brought  into  existence  by  the  necessity 
which  constantly  presents  itself  of  diminishing  the  enormous  amount  of  labor 
expended  in  producing  plane  surfaces  on  wood  by  hand,  as  practised  by  means 
of  the  common  joiner’s  plane.  Next  to  the  process  of  sawing,  there  is  no  opera- 
tion connected  with  the  working  of  wood,  which  consumes  so  much  time,  and 
adds  so  much  to  the  expense  of  the  conversion  of  timber  as  the  production  of  the 
hand-planed  surface. 

The  first  attempt  to  obviate  this  difficulty  with  which  we  are  acquainted,  was 
made  by  General  Bentham,  in  1791,  who  took  out  a patent  for  a method  of  effect- 
ing this  object.  In  this  scheme,  the  plane  or  cutting-edge,  which  was  movable, 
was  made  of  the  full  width  of  the  board  intended  to  be  cut,  and  on  each  side  of 
it  were  fixed  fillets  which  projected  below  the  face  of  the  plane,  a distance  equal 
to  the  amount  of  the  thickness  intended  to  be  taken  off  the  board.  Several 
plans  were  adopted  for  obtaining  a good  surface  from  a very  thin  board,  but  the 
whole  scheme  eventually  proved  all  but  abortive — the  machine  was  never  prac- 
tically worked  by  mechanical  power,  but  whether  thus  driven,  or  by  the  hand 
of  the  attendant  workman,  the  idea  had  still  the  advantage,  that  it  exonerated 
the  latter  from  the  charge  which  he  had  of  his  tool  in  the  ordinary  operation  of 
planing,  rendering  a common  workman  as  useful  as  the  skilful  joiner  for  this 
purpose.  The  next  epoch  in  the  history  of  mechanical  planing  is  the  improve- 
ment produced  by  Mr.  Bramah,  who,  in  1802,  patented  a method  of  producing 
“ straight,  smooth,  parallel,  and  curvilinear  surfaces  on  wood  and  other  mate- 
rials.” This  invention  embraced  the  original  machine  for  producing  spheres,  the 
principle  of  which  is  still  preserved  in  all  machines  of  a similar  nature  to  the 
present  day.  Bramah’s  planing  machine,  as  constructed  for  the  Royal  Arsenal 
at  Woolwich,  gives  us  a specimen  of  an  embodiment  of  his  ideas  at  this  period. 

Here  the  cutters  are  attached  to  a horizontal  disk  keyed  on  a strong  vertical 
spiudle.  This  disk  is  put  in  rotation  at  a speed  of  about  90  revolutions  per 
minute,  the  material  to  be  cut  being  attached  to  a sliding  cast-iron  bed,  which  is 
moved  by  hydrostatic  pressure.  A pipe  communicating  with  a hydrostatic  press  is  carried  in  below  th6 
bed  of  the  machine,  and  terminates  in  a plunger-barrel,  the  plunger  of  which  carries  a rack-geering 
with  a pinion  on  a rag-wheel  shaft.  This  wheel  is  provided  with  teeth,  over  which  a pitch-chain  at- 
tached to  the  table  of  the  machine  is  carried. 

In  all  planing  machines  as  at  present  constructed,  the  cutter  is  invariably  the  fixed  portion,  the  work 
being  passed  beneath  it  in  the  act  of  cutting,  by  means  of  a sliding-table.  The  particular  species  of 
planing  machine  which  has  been  most  lately  introduced,  is  termed  the  hand-planing  machine. 

In  Figs.  3477  and  3479  we  have  given  three  views  of  a simple  and  effective  hand-planing  machine, 
as  suited  for  small  work  generally,  such  as  links  and  connecting-rod  ends  for  locomotive  engines,  and 
other  portions  of  machinery  where  a plane  surface  of  small  extent  is  required. 

The  table  of  the  machine  is  here  supported  in  the  usual  manner,  as  employed  in  similar  tools  of  a 
larger  class,  upon  a bed  bolted  to  the  top  of  two  standards  attached  to  the  floor.  The  lower  surface  of 
the  table  carries  a rack  M,  which  is  driven  by  a pinion  F,  upon  the  shaft  G,  supported  in  bearings  at- 
tached to  the  fixed  bed  of  the  machine.  Motion  is  given  to  this  shaft  in  either  direction,  by  the  cross- 
handle H,  worked  by  hand  in  a similar  manner  as  applied  to  small  presses. 

The  cross-slide  C is  supported  by  two  uprights  bolted  down  to  the  bed ; this  slide  carries  the  tool-holder 
D,  which  is  traversed  across  the  bed  of  the  machine  by  means  of  the  horizontal  screw  b.  The  automa- 
tic action  of  the  transverse  feed  motion  of  the  cross-slide  is  effected  by  the  movable  stud  S,  attached  to 
the  travelling-table ; this  stud,  being  movable  in  a groove  in  the  side  of  the  table,  is  capable  of  being 
set  at  any  point  in  order  to  suit  the  required  length  of  stroke  for  the  work.  The  pressure  of  this  stud, 
upon  a short  lever  keyed  on  the  small  shaft  carrying  the  piece  n,  depresses  it,  and  the  latter,  by  its 
connecting-rod  r,  acts  upon  the  ratchet-plate  K,  upon  the  horizontal  screw  b. 

The  amount  of  travel  thus  given  to  the  screw  is  varied  by  shifting  the  position  of  the  sliding-studs  in 
the  pieces  m and  n.  The  front  plate  of  the  tool-holder  is  provided  with  two  short  circular  slots,  through 
which  bolts  pass  from  the  back  plate ; in  this  manner  the  tool  may  be  set  at  any  angle  to  suit  the  na- 
ture of  the  work  required.  The  tool-holder  or  cross-slide  is  raised  or  lowered  to  suit  the  circumstances 
by  the  vertical  screws//,  driven  by  bevel-geering  in  the  usual  manner. 

A somewhat  similar  but  more  useful  machine  of  this  species  has  been  introduced  by  Mr.  Charles 
Walton,  of  Leeds.  In  this  machine  the  bed  is  so  arranged  that  it  may  be  fixed  upon  the  workman’s 
bench,  and  may  be  driven  either  by  manual  or  steam  power.  Immediately  beneath  the  bed  of  the  ma- 
chine is  placed  a horizontal  grooved  disk,  driven  by  bevel-geering,  either  from  the  pulley-shaft  of  the 


TOOLS. 


751 


workshop  or  by  a winch.  This  disk  is  grooved  directly  across  its  upper  surface  for  the  purpose  of  re- 
ceiving a pin,  which  is  connected  by  a link  with  the  lower  surface  of  the  short  travelling-table.  In  this 
manner  a reciprocating  motion  is  given  to  the  table  in  the  simplest  manner,  and  the  length  of  stroke  is 
capable  of  variation  according  to  the  distance  of  the  pin  in  the  horizontal  grooved  disk,  from  the  centre 
of  motion.  The  feed  motion  of  the  cross-slide  is  effected  by  a stud  fixed  on  the  under  surface  of  the 
horizontal  disk;  this  stud  works  a short  lever  keyed  upon  a shaft  working  in  bearings  attached  to  the 
side  of  the  bed.  This  shaft  again  curries  a second  lever  outside  the  bed,  and  is  jointed  by  a link  to  an 
arrangement  of  ratchets.  For  all  small  machines,  this  method  of  giving  motion  to  the  table  is  decidedly 
the  simplest  and  most  compact,  and  although  the  introduction  of  the  disk  has  the  effect  of  producing 
a variable  speed  in  the  cutting,  being  greatest  at  the  middle  of  its  stroke  and  least  at  each  end ; yet  as 
the  disk  is  confined  to  machines  of  a short  stroke,  its  diameter  is  not  so  great  as  to  bring  about  a detri- 
mental variation  in  the  speed.  Small  machines  of  this  species,  ■which  are  quite  an  innovation  in  the 
workshop,  are  now  becoming  indispensable  where  much  small  work  is  required,  and  have  served  in  a 
great  measure  to  banish  that  most  expensive  of  all  tools,  the  file,  and  thus  rendered  an  important  ser- 
vice in  cheapening  engineering  work  in  general.  So  much  indeed  is  this  the  case,  that  it  is  an  estab 
lished  fact  that  different  portions  of  machinery,  the  configuration  of  which  is  made  up  of  curved  and 
plane  surfaces,  are  now  entirely  finished  by  means  of  the  lathe  and  planing  machine,  without  the  neces- 
sity of  touching  them  with  the  file. 

As  a spacimen  of  a step  higher  in  the  order  of  completeness  and  general  usefulness  in  machines 
of  this  kind,  we  must  now  refer  the  reader  to  Figs.  3080  and  30802,  where  we  have  given  very 
complete  views  of  the  machine  invented  by  Mr.  Mylne,  of  Glasgow.  Here  tire  system  of  working 
the  vertical  and  horizontal  slides  is  similar  to  that  made  se  of  in  the  hand-machine,  Figs.  3077 
and  3078. 

The  chief  peculiarities  in  the  present  machine  are  the  arrangement  of  the  geering  for  travelling  the 
table,  and  the  great  completeness  of  the  tool-holder.  The  forward  or  cutting  motion  of  the  table  is  ob- 
tained from  the  large  pulley  A,  the  shaft  of  which  carries  a pinion  D geering  with  the  large  wheel  E 
upon  the  rack-pinion  shaft. 

This  shaft  carries  two  pinions  geering  with  two  racks  of  similar  pitch  bolted  to  the  under  side  of  the 
travelling-table.  These  racks  are  so  placed  that  each  tooth  of  the  one  shall  be  opposite  to  each  space 
of  the  other ; in  this  manner  the  irregularity  of  motion  so  much  complained  of  in  ordinary  rack-worked 
machines,  as  producing  a waved  surface  on  the  work,  is  to  some  extent  avoided.  A more  effectual 
method  of  attaining  this  end  has  been  introduced  by  Mr.  Collier,  of  Manchester ; this  plan  consists  in 
making  the  teeth  of  the  rack  and  pinion  on  what  is  technically  termed  the  step  system,  that  is,  each 
tooth  is  divided  in  its  breadth  into  three  parts,  each  division  being  set  a distance  equal  to  one-third  of 
the  true  pitch  of  the  teeth  behind  its  neighbor.  The  practical  result  of  this  arrangement  is,  that  although 
the  strength  of  the  original  coarse  pitch  is  preserved,  yet  the  teeth  work  with  the  steadiness  due  to  a 
pitch  three  times  finer,  or  so  many  times  less  as  the  number  of  divisions  of  the  teeth  amounts  to.  This 
plan  is  now  universally  adopted  in  all  rack  machines,  as  it  is  simple,  easy  of  application,  and  completely 
effectual. 

This,  although  in  our  opinion  not  the  best,  is  probably  the  most  universally  used  species  of  driving 
geering  applied  to  planing  machines.  Of  the  two  remaining  systems,  the  chain  and  seme , the  latter,  for 
excellence  of  workmanship,  is  decidedly  to  be  preferred.  Mr.  Whitworth’s  planing  machine  is  perhaps 
the  most  finished  specimen  of  modern  tool-making  extant. 

The  principle  of  anti-friction  rollers  acted  on  by  a screw,  as  a means  of  obtaining  a rectilinear  motion, 
was  first  introduced  by  Mr.  Whitworth,  in  1835,  when  he  employed  it  as  a motion  for  the  carriage  of 
the  self-acting  spinning  mule.  In  his  planing  machine  the  rollers  are  placed  parallel,  face  to  face,  on 
opposite  sides  of  the  screw,  their  axes  revolving  in  bearings  attached  to  the  under  surface  of  the  bed, 
and  their  peripheries  projecting  into  the  spaces  between  the  threads  of  the  driving-screw.  It  will  be 
seen  that  each  periphery  has  two  opposite  points  of  contact,  acting  alternately  according  to  the  direction 
of  motion  of  the  screw,  which,  as  it  revolves,  brings  its  threads  to  bear  upon  the  rollers,  causing  them  to 
revolve,  and  at  the  same  time  to  carry  forward  the  table  to  which  they  are  fixed.  The  friction  which 
would  occur  if  the  threads  of  the  screw  bore  simply  against  a fixed  nut,  is  thus  transferred  to  the  axes 
of  the  rollers,  where  the  velocity  is  reduced  in  the  proportion  existing  between  their  peripheries  and  the 
circumference  of  their  axes.  The  proportion  found  to  answer  best  for  this  arrangement  is  as  7 to  1. 
The  advantage  which  this  mode  of  driving  has  over  the  common  rack  and  the  chain  will  be  perceived  a4 
a glance,  as  not  only  is  the  motion  rendered  perfectly  uniform,  a condition  essentially  necessary  to  the 
proper  action  of  the  cutter  in  producing  a good  surface,  but  the  construction  of  the  driving  geering  is 
rendered  to  the  last  degree  simple. 

The  arrangement  of  catches  employed  by  Mr.  Mylne  is  good,  but  tire  geering  connecting  the  catch- 
shaft  with  the  strap-fork  is  capable  of  much  simplification. 

Referring  to  Figs.  3080  and  30802,  it  will  be  seen  that  there  are  two  adjustable  catches  n n set  in  a 
groove  running  along  the  side  of  the  table ; these  catches  are  not  set  in  the  same  plane,  but  one  projects 
out  beyond  the  other  in  order  to  suit  the  levers  g,  which  are  cast  to  a tubular  shaft  working  loose  on 
the  driving-shaft.  When  the  table  is  moving  forward  one  of  the  catches  comes  in  contact  with  its  lever 
and  turns  it  over,  as  seen  in  the  end  view  of  the  machine.  The  boss  of  these  levers  again  carries  a third 
lever  connected  to  the  weighted  lever  on  the  end  of  the  bed,  which  again  communicates  by  a shaft  run- 
ning along  the  side  of  the  machine,  with  the  strap-fork  shaft  0;  the  latter  thus  causes  the  shift  of  the 
straps  from  one  pulley  to  the  other,  and  reverses  the  motion  of  the  table.  Upon  the  return  of  the  table, 
the  catch  which  has  just  acted  now  returns  without  coming  in  contact  with  its  lever,  as  its  former  motion 
has  placed  it  out  of  its  reach,  having  at  the  same  time  raised  the  second  lever  on  the  same  shaft  to  an 
upright  position,  so  that  it  may  be  acted  upon  by  the  other  catch  at  the  contrary  end  of  the  table,  when 
the  straps  are  brought  back  to  their  primary  positions. 

As  a driving  and  reversing  geer  for  small  planing  machines,  Mr.  Nasmyih  has  applied  the  mangle- 


752 


TOOLS. 


wheel  motion,  so  called  from  its  adaptation  as  a continuous  forward  motion  for  common  clothes-mangles. 
It  consists  of  a large  disk,  having  near  its  circumference  a circle  of  pins  bolted  through  the  metal  at 
right  angles  to  its  plane;  these  pins  answer  as  a set  of  teeth,  into  which  a small  driving-pinion  geers, 
working  alternately  on  the  outside  and  inside  of  the  teeth  so  as  to  effect  the  desired  reverse  motions. 
In  Mr.  Nasmyth’s  arrangement,  the  driving-pulley  is  keyed  upon  a light  shaft  passing  transversely  be- 
neath the  table  of  the  machine.  The  contrary  extremity  of  this  shaft,  which  projects  beyond  the  edge 
of  the  bed,  carries  the  mangle-pinion  geering  with  the  pins  of  the  mangle-wheel.  The  latter  is  keyed 
upon  a central  transverse  shaft  which  passes  beneath  the  table  of  the  machine  and  carries  a large  chain- 
pulley.  Round  this  pulley  a chain  is  passed  twice,  and  its  two  extremities  are  passed  round  two  fixed 
pulleys  placed  at  contrary  ends  of  the  bed,  and  attached  to  the  opposite  ends  of  the  travelling-table. 
The  reversing  of  the  mangle-wheel,  and  consequently  that  of  the  table,  is  effected  in  the  following  man- 
ner : at  two  points  in  the  circumference  of  the  mangle-wheel,  one  or  two  of  the  pin-teeth  are  removed, 
and  a sloping  guide  or  stud  is  placed  at  each  point,  so  that  when  the  driving-pinion  arrives  there,  this 
guide  causes  it  to  traverse  in  or  out,  as  the  case  may  be,  to  geer  with  the  inner  or  outer  sides  of  the 
pins,  under  which  conditions  it  is  easy  to  see  that  the  two  contrary  motions  of  the  wheel  will  be  the 
result.  The  guide  supporting  the  pinion-shaft  is  slotted  horizontally  to  allow  of  the  traversing  of  the 
shaft  as  well  as  to  prevent  its  running  beyond  the  point  of  geer  with  the  pins  of  the  mangle-wheel,  the 
bearing  on  the  opposite  end  of  the  shaft  next  the  driving-pulley  being  arranged  to  swivel  on  a centre, 
so  as  to  permit  of  this  motion.  This  movement  of  the  pinion-shaft  is  also  taken  advantage  of  in  giving 
the  feed  motion  to  the  cross-slide  of  the  machine,  being  connected  to  the  vertical  rod  carrying  the  catches 
for  the  ratchet-wheel  of  the  transverse  screw. 

This  movement,  although  ingenious,  is  destitute  of  the  ad- 
vantage  of  an  increased  speed  in  the  return  stroke,  consequent- 
ly much  time  is  lost  by  it  when  applied  to  single-acting  ma- 
chines. 

The  arrangement  applied  by  Messrs.  Nasmyth  and  Gaskell 
to  the  rack-planing  machines  is  a very  convenient  though 
somewhat  cumbrous  motion.  Fig.  3472  is  a ground  plan  of 
this  geering,  in  which  a is  the  forward  motion  driving-pulley, 
keyed  on  the  hollow  shaft  b,  which  carries  a pinion  c geering 
with  a large  spur-wheel  d.  The  latter  is  keyed  directly  on 
the  rack-pinion  shaft  e,  shown  in  dotted  lines  passing  beneath 
the  table  of  the  machine.  The  backward-motion  pulley/  is 
keyed  on  the  solid  shaft,  passing  through  the  hollow  one  and 
revolving  at  one  extremity  in  the  bearing  g fixed  on  a pedestal 
attached  to  the  bed-plate,  and  at  the  other  in  the  bearing  k 
bolted  to  the  side  of  the  bed.  This  latter  shaft  carries  another 
pinion  k geering  by  means  of  an  intermediate  carrier-wheel, 
with  the  spur-wheel  l also  keyed  on  the  rack-pinion  shaft. 

The  centre  pulley  is  of  course  loose,  serving  merely  to  carry 
the  strap  when  the  machine  is  stopped,  and  during  the  trans- 
fer from  the  forward  to  the  backward  pulley.  Thus  it  will  be  seen  that  the  return  stroke  of  the  table 
will  be  so  much  quicker  than  the  cutting  one,  as  the  difference  in  diameter  of  the  two  wheels  l and  d,  or 
rather,  as  the  ratio  which  exists  between  the  wheels  k and  I and  c and  d. 

The  strap-fork  is  seen  at  m ; it  is  worked  by  catches  fixed  on  the  other  side  of  the  table,  a connecting- 
shaft  from  which  passes  beneath  the  bed  where  it  is  attached  to  the  fork;  n is  a weighted  lever  for  the 
purpose  of  giving  a sudden  shift  to  the  strap,  so  as  to  give  the  workman  a better  command  over  his 
machine. 

Of  chain-worked  planing  machines,  the  modification  introduced  by  M.  Decoster,  of  Paris,  is  perhaps 
one  of  the  most  complete.  In  his  machine  he  has  made  use  of  the  driving-geer  as  applied  by  Mr. 
Whitworth  to  his  screw-machines.  In  the  example  by  M.  Decoster,  to  which  we  refer,  the  chain- 
motion  is  applied  to  give  motion  to  the  tool-slide,  while  the  table  of  the  machine  remains  stationary. 
This  plan  is  found  extremely  useful  in  planing  heavy  and  unmanageable  pieces  of  metal,  as  the  latter 
may  be  firmly  secured  to  a foundation  independent  of  the  machine,  while  the  tool  alone  traverses  over 
it ; and  consequently  no  more  power  is  absorbed  by  a heavy  casting,  than  by  the  lightest  possible  piece 
of  metal.  The  driving  geering  before  referred  to  is  here  placed  alongside  the  bed  of  the  machine,  near 
one  end ; the  pinion  on  the  central  bevel-wheel  geers  with  a large  spur-wheel,  on  a shaft  passing  trans- 
versely across  the  bed  of  the  machine,  below  the  table.  The  latter  shaft  carries  two  rag-wheels,  placed 
near  its  two  extremities  just  within  the  frame  of  the  machine.  Round  each  of  these  wheels  is  passed 
an  endless  chain,  which  passes  along  the  whole  length  of  the  machine,  returning  round  a similar  pair  of 
w’heels  revolving  loosely  on  studs  at  the  contrary  end  of  the  bed.  The  upper  length  of  this  chain  is 
attached  to  the  lower  surface  of  a V-grooved  slide,  working  in  corresponding  grooves  planed  in  the 
upper  surface  of  the  bed.  This  slide  carries  a second  horizontal  slide  supporting  the  tool-holder  in  the 
usual  manner.  The  feed-motion  of  the  cross-slide  is  ingeniouslv  effected  by  two  ratchet-catches  attached 
to  the  spur-geering  on  the  end  of  the  horizontal  screw.  The  lower  extremities  of  these  catches  are  set 
to  come  in  contact  with  movable  tappets  attached  to  the  fixed  frame  of  the  machine,  so  as  to  give  the 
proper  amount  of  motion  to  the  screw  of  the  cross-slide.  The  method  of  attachment  of  the  driving- 
chains  adopted  by  M.  Decoster  has  the  advantage  of  giving  a steadier  pull  to  the  tool-slide  than  can  be 
obtained  by  the  central  mode  of  fastening,  with  a single  chain. 

The  principle  of  the  movable  tool  and  fixed  table  has  also  been  adopted  by  M.  Cave  and  Mi-.  Hick,  of 
Bolton.  In  M.  Cave’s  machine,  the  driving  motion  is  given  to  the  tool-slide  by  an  endless  strap.  The 
driving-pulley  is  placed  immediately  over  the  centre  of  the  bed  of  the  machine,  the  strap  from  whicn 
passes  below  two  fixed  tension-pulleys,  placed  just  beneath  the  driver,  and  thence  round  two  fixed  pul- 


l C uLS. 


753 


leys  attached  to  the  opposite  ends  of  the  bed.  The  attachment  of  this  strap  to  the  sliding-frame  of  tb6 
tool  is  effected  by  passing  the  strap  in  contrary  directions  round  two  separate  pulleys,  each  carrying  a 
pinion  geering  with  a central  driving-wheel.  'The  shaft  of  the  latter  passes  across  the  bed  of  the  ma- 
chine, and  carries  two  pinions,  geering  with  two  racks,  placed  within  the  framing,  and  running  along  the 
whole  length  of  the  bed. 

The  arrangement  of  the  spur  reversing-geer  will  be  understood  by  referring  to  Fig.  3473,  which  is  a 
side  view  of  the  tool-slide,  frame,  and  geering,  with  the  driving-pulleys  removed.  A is  the  travelling 
tool-slide,  eairying  the  central  driving-wheel  B,  keyed  on  the  pinion-shaft — the  shafts  C C each  carry  a 
loose  driving-pulley,  capable  of  connection  by  means  of  sliding  clutch-boxes  with  the  two  pinions  D D 
These  latter  work  loose  on  the  pulley-shafts,  and  geer  with  the  central  wheel  B,  so  as  to  drive  it  ir. 
either  direction  accordingly  as  the  clutch-boxes  are  set. 


3173. 


Two  povable  inclined  tappets  are  fixed  to  the  bed  of  the  machine,  which  alternately  come  in  contact 
with  the  lever  E on  the  oblique  shaft  F,  so  as  to  move  it  in  and  out  according  to  the  motion  of  the  slide. 
The  shaft  F carries  the  two  forks  G,  connected  to  the  clutch-boxes  of  the  pinions  D D,  which  are  placed, 
one  on  each  side  of  it,  so  that  when  the  lever  E is  pressed  upon  by  its  tappets,  the  hold  of  the  two 
clutches  is  changed  accordingly — one  being  thrown  out  of  geer  at  the  same  time  the  other  is  put  in.  In 
this  manner,  as  the  two  pulleys  on  the  pinion-shafts  revolve  in  different  directions,  a reciprocating  mo- 
tion is  given  to  the  travelling-slide. 

The  cross-slide  of  this  machine  is  provided  with  two  tool-holders,  one  on  each  side,  so  as  to  cut  in  both 
directions ; this  improvement  effects  a great  saving  of  time,  as  the  return  stroke  is  rendered  equally  as 
effective  as  the  forward  one. 

In  Mr.  Hick's  movable  tool-slide  machine,  the  traversing  motion  is  given  to  it  by  means  of  steel  belts. 
The  driving-pulley  of  the  machine  is  alternately  worked  by  a cross  and  open  strap ; the  shaft  of  this 
pulley  is  connected,  by  means  of  spur-geering,  with  a transverse  shaft  carrying  two  pulleys  working 
outside  the  frame  of  the  machine.  These  pulleys  each  carry  an  endless  steel  belt,  running  along- 
side the  frame,  and  passing  round  two  similar  pulleys  placed  at  the  contrary  extremity  of  it.  The 
steel  belts  are  attached  to  projecting  levers  on  the  cross-slide  by  means  of  tightening  screws,  so  as 
to  communicate  an  alternate  motion  to  it,  accordingly  as  the  open  or  crossed  strap  is  working  on  the 
driving-pulley. 

As  the  speed  of  the  travelling-table  of  this  machine  is  the  same  in  each  direction,  it  is  arranged  to 
cut  both  ways,  by  the  adaptation  of  Mr.  Whitworth’s  revolving  tool-holder,  subsequently  described. 

It  is  a'  matter  of  considerable  importance  in  planing  machines,  to  have  a compact  arrangement  at 
command,  both  for  reversing  the  motion  of  the  table,  and  also  for  giving  the  self-acting  feed-motion  to 
the  cross-slide.  As  regards  the  reversing  motion,  in  planing  delicate  or  complicated  work,  it  is  often 
requisite  to  be  able  to  stop  the  motion  of  the  table  within  the  shortest  possible  limits,  as,  for  instance, 
in  planing  up  to  an  abrupt  shoulder ; in  such  a case,  if  the  tool  does  not  proceed  sufficiently  far,  a sur- 
face of  metal  is  left  which  must  be  removed  by  some  more  laborious  means ; or,  on  the  other  hand,  if  it 
proceeds  a little  too  far,  the  tool  strikes  against  the  obstacle  and  causes  an  injury  either  to  the  work  or 
to  its  own  geering.  In  small  machines  this  is  easily  avoided,  by  the  use  of  the  crank  or  grooved  disk, 
which  allows  of  the  greatest  exactitude  in  the  length  of  travel ; but  in  machines  of  the  larger  class  we 
are  driven  to  some  other  expedient  to  attain  this  end.  Where  the  change  of  motion  is  effected  by  the 
pulley-belt,  the  simplest  and  most  effective  system  of  quick  stoppage  is  the  addition  of  the  weighted 
balance-lever  attached  to  the  strap-fork ; the  sudden  fall,  in  either  direction,  of  this  weight  causes  an 
instantaneous  motion  of  the  strap,  and  stops  the  table  within  very  short  limits.  Where  still  greater 
nicety  is  required,  possibly  the  addition  of  a movable  clutch-box  may  be  of  some  assistance  Soma 
Vol.  II. — 48  * 


754 


TOOLS. 


maker's,  indeed,  have  applied  Ihe  clutch-box  instead  of  the  shifting-strap,  the  clutch  being  arranged  to 
throw  the  two  side  bevel-wheels  in  geer  alternately  with  the  centre  one. 

Asa  compact  and  efficient  self-acting  reversing  and  feed  motion,  we  give  that  adopted  by  Mr.  Whit 
worth,  as  one  of  the  best.  Fig.  3474  is  a side  elevation  of  the  apparatus  ; a is  the  table  of  the  planing 
machine,  on  the  side  of  which,  at  the  centre,  is  screwed  the  fixed  catch  b,  which,  in  the  course  of  work- 
ing, alternately  comes  in  contact  with  the  movable  catches  cc,  adjustable  on  the  shaft  d which  runs 
alongside  the  table,  sliding  in  the  bearings  e e at  each  end  of 
the  frame.  This  shaft  carries  a third  adjustable  catch/,  con- 
nected with  a short  lever  cast  on  the  boss  g working  loose  on 
a stud  screwed  to  the  frame.  The  same  boss  has  also  cast 
upon  it  a second  lever  /t,  at  right  angles  to  the  former  one, 
the  end  of  which  works  in  a slot  in  the  scrap-fork  i.  The  lat- 
ter oscillates  on  a centre  attached  to  the  bed  at  k ; when  the 
catch  b comes  in  contact  with  one  or  other  of  the  studs  c,  the 
shaft  d is  carried  along  laterally,  and  gives  motion,  through 
the  arrangement  of  levers  just  described,  to  the  strap-fork  so 
as  to  shift  the  strap  from  one  pulley  to  the  other,  and  reverse 
the  table. 

The  self-acting  feed-motion  of  the  cross-slide  is  effected  in 
the  following  simple  manner : on  the  sliding  shaft  or  rod  d a 
few  rack-teeth  l are  cut,  which  geer  with  a segment  of  a spur- 
wheel  keyed  on  the  shaft  m,  working  in  bearings  screwed  to 
the  upright  frame  of  the  machine,  and  carrying  the  eccentri- 
cally-grooved disk  n,  which  revolves  with  it ; o is  the  vertical 
rod  carrying  the  ratchet-catches  for  working  the  horizontal 
screw  of  the  cross-slide  : it  is  guided  by  a bearing  p screwed 
to  the  frame,  and  carries  at  its  lower  extremity  a pin  working 
in  the  eccentric  slot  of  the  disk  n.  Thus  when  the  rod  d re- 
ceives its  motion  from  the  catch  b,  at  the  termination  of  the 
stroke  of  the  table,  its  short  rack  causes  the  disk  n to  make  a 
portion  of  a revolution,  so  as  to  raise  or  depress  the  rod  o 
by  means  of  the  eccentric  groove.  This  motion  is  at  once  ef- 
fectual and  easy  of  application,  besides  possessing  that  great 
desideratum  in  all  tools,  compactness. 

We  now  come  to  the  consideration  of  tool-holders.  The 
specimen  of  a tool-holder  given  in  Mr.  Mylne’s  machine,  is  one 
of  the  more  complicated  variety,  being  provided  with  a double 
set  of  slides  and  appropriate  screws,  for  the  purpose  of  plan- 
ing at  two  different  angles  with  one  adjustment  of  the  tool. 

The  saving  in  time,  however,  by  this  arrangement,  is  more 
than  counterbalanced  by  the  increased  cost  of  the  tool-box, 

3475. 


and  the  disadvantage  which  it  entails  upon  the  machine,  by  throwing  the  point  of  resistance  in  cutting 
so  far  from  the  surface  of  the  supporting  frame  as  to  render  the  cutting  action  unsteady. 

A somewhat  simpler  modification  of  the  same  variety  of  holder  is  represented  in  Fig.  3475,  where  the 


TOOLS. 


(05 


edf-acting  down  cut  motion  is  obtained  by  one  screw;  a is  a transverse  section  through  the  cross-slide 
of  the  machine,  to  which  is  fitted,  by  dovetails,  the  horizontal  sliding-plate  b.  The  latter  again  carries 
the  down-cut  slide  c,  being  attached  to  it  by  dovetail-headed  bolts  working  in  a circular  groove  in  the 
former.  The  slide  c is  fitted  with  a central  screw  carrying  a nut  fixed  on  the  front  sliding- plate  d,  so 
that  the  latter  may  be  moved  at  any  angle  to  the  bed  of  the  machine  according  to  the  angular  position 
of  the  screw;  e is  a front  plate,  checked  into  the  slide  d,  to  which  is  hinged  the  tool-holder/,  carrying 
the  tool  as  shown  at  g. 

The  self-acting  feed-motion  is  given  to  the  screw  in  the  plate  c by  bevel-geering,  similar  to  that  em- 
ployed in  Mr.  Mylne’s  machine.  The  hinge  at  the  upper  end  of  the  tool-holder  is  for  the  purpose  of 
nllowing  the  tool  to  give  way  in  case  it  comes  in  contact  with  any  obstacle  during  the  return  stroke  of 
the  machine.  In  all  properly  constructed  tool-boxes,  the  mechanism  is  arranged  to  lift  the  tool  out  of 
the  way  at  each  return  stroke,  so  that  it  never  rests  upon  the  surface  of  the  work  in  the  back  motion. 
This  is  effected  by  a separate  transverse  screw  placed  parallel  to  the  main  traversing  screw,  and  worked 
by  the  same  geering.  In  Mr.  Bodmer’s  tool-boxes  this  screw  carries  a nut  with  a slotted  projection  fit- 
ting to  a pin  in  the  upper  end  of  the  front  plate,  which  oscillates  loosely  on  a fixed  centre.  The  nut 
being  carried  along  with  the  tool-slide  by  the  revolution  of  its  screw,  remains  always  immediately  above 
the  centre  of  the  tool-holder;  at  the  termination  of  a stroke,  the  reversing  geering  is  so  connected  with 
the  screw  as  to  give  the  latter  a lateral  sliding  motion,  the  nut  upon  it  then  moves  the  front  plate  by 
the  pin  in  its  upper  side.  This  plate  carries  a small  inclined  pin,  which  in  its  motion  presses  against 
the  front  of  the  hinged  tool-holder,  thus  raising  it  out  of  connection  with  the  work. 

The  self-feeding  down-cut  motion  is  also  given  by  the  same  oscillating  plate.  The  latter  is  provided 
with  a toothed  sector  screwed  to  it  near  its  lower  extremity,  and  geering  with  a small  bevel-pinion  on 
the  down-cut  screw-spindle.  The  latter  being  fitted  with  a ratchet-wheel,  receives  at  each  stroke  of  the 
machine  an  amount  of  motion  proportioned  to  the  material  to  be  cut.  This  is  probably  one  of  the  most 
complete  and  effective  of  all  single-acting  tool-holders,  and  is  a good  specimen  of  the  high  degree  of 
eminence  which  Mr.  Bodmer  has  attained  as  a maker  of  constructive  machinery. 

In  addition  to  the  common  rectilineal  planing  machine,  machinists  have  of  late  years  found  a power- 
ful auxiliary  in  the  circular  machine ; this  may  be  defined,  in  general  terms,  as  a lathe  with  a vertical 
spindle.  The  tool  is  either  fixed  or  movable,  the  former  being  the  preferable  and  more  general  ar- 
rangement. The  advantages  which  these  machines  possess  over  common  turning-lathes,  are,  firstly,  the 
greater  facility  of  adjustment  of  heavy  castings  preparatory  to  planing  them  ; and  secondly,  the  greater 
latitude  they  allow  for  acting  on  masses  of  metal  of  great  diameter,  as  the  driving-wheels  of  locomotive 
engines,  fly-wheels,  &c.  Of  this  species  of  tools,  perhaps  Mr.  Bodmer’s  modification  stands  highest  in 
the  scale  of  usefulness.  It  consists  of  a heavy  foundation  plate,  in  the  centre  of  which  a strong  vertical 
spindle  revolves,  having  a horizontal  circular  table  of  large  diameter  keyed  upon  it,  and  provided  in  the 
usual  manner  with  slots  for  fixing  the  work.  The  fixed  cutter  is  held  in  a tool-box  precisely  similar  to 
that  adopted  in  the  common  planing  machines.  It  is  placed  on  a strong  horizontal  cross-slide,  which  is 
adjusted  to  work  freely  in  a vertical  direction  upon  two  upright  frames,  placed  one  on  each  side  of  the 
revolving-table.  The  tool-holder  being  fitted  with  a down-cut  motion,  is  readily  adjusted  with  great 
ninety  to  suit  the  work,  besides  which  its  horizontal  motion  on  the  cross-slide,  combined  with  the  verti- 
cal motion  of  the  latter  upon  the  uprights  of  the  frame,  permit  the  tool  to  be  set  to  any  portion  of  the 
radius  of  the  table.  The  machine  is  fitted  with  a self-feeding  motion ; this  is  found  very  serviceable  in 
turning  up  the  tires  of  locomotive  and  carriage  wheels,  the  rims  of  small  fly-wheels,  <fce.  Machines  have 
been  constructed  which  combine  the  advantages  both  of  the  rectilineal  and  circular  machines,  with  a 
view  to  the  finishing  of  more  complicated  work  than  can  be  effected  by  either  of  these  separately.  The 
machine  is  provided  with  a rectilineal  sliding-table,  as  ordinarily  used,  supported  on  a fixed  bed.  A 
horizontal  shaft  passes  transversely  below  the  bed,  and  carries  a plain  sector  of  considerable  radius,  to 
which  a chain  is  attached,  and  is  connected  to  the  opposite  ends  of  the  table.  Motion  is  given  to  this 
sector  by  a plain  grooved  disk,  as  usually  applied  to  slotting  machines  ; this  is  driven  by  over-head 
geering,  supported  by  the  upright  framing  which  springs  from  the  bed  of  the  machine.  The  pin  of  this 
disk  is  attached  by  a suitable  connecting-rod  to  a crank  keyed  on  the  extremity  of  the  shaft  of  the  sec- 
tor, which  thus  communicates  a reciprocating  motion  to  the  table,  of  a length  dependent  on  the  position 
of  the  pin  in  the  radius  of  the  disk. 

When  continued  circular  work  is  required,  the  driving  disk  is  thrown  out  of  geer,  and  the  driving- 
shaft  is  connected  with  an  upright  spindle  revolving  in  bearings  attached  to  the  upper  framing  of  the 
machine,  and  carrying  an  adjustable  cutter  in  a projecting  arm  at  its  lower  extremity.  This  cutter  is 
provided  with  suitable  slides,  by  which  it  may  be  set  at  any  required  distance  from  the  centre  of  motion 
of  the  spindle,  so  as  to  act  upon  any  given  circle.  When  thus  arranged  it  may  be  used  as  a powerful 
boring  machine,  by  detaching  the  facing  cutters,  aud  fitting  the  proper  tools  as  applied  to  the  usual  bor- 
ing bars.  When  the  combination  of  the  straight  and  circular  movements  is  required,  as  for  finishing 
the  flat  sides  and  circular  ends  of  strap-links,  ifcc.,  both  movements  are  effected  by  the  same  driving- 
shaft  as  follows : — On  the  end  of  the  driving-shaft  are  keyed  two  toothed  sectors,  arranged  to  give  al- 
ternately a semi- revolution  to  the  wheel  on  the  driving  disk  for  the  rectilineal  motion,  and  that  on  the 
train  for  giving  the  circular  motion  to  the  cutter-spindle— each  wheel  being  alternately  held  by  a de- 
tent while  the  other  is  being  driven.  In  this  manner  various  kinds  of  work  may  be  finished  in  a very 
superior  manner,  such  as  the  plane  and  circular  surfaces  of  plummer-blooks,  connecting-rod  straps,  Ac. 

In  addition  to  these  two  descriptions  of  machines  for  obtaining  a plane  surface,  a third  species  for 
planing  curves  has  latterly  filled  an  important  office  in  the  engineer’s  workshop.  The  tool  to  which  we 
refer  is  the  compound  machine  by  Messrs.  Nasmyth  and  Gaskell.  This  little  machine  forms  another 
link  in  the  catalogue  of  automatic  contrivances  for  superseding  the  delicate  manipulations  of  file  labor. 
By  its  assistance  the  circular  ends  of  levers,  connecting-links,  &c.,  are  correctly  cut  out,  and  finished  with 
a degree  of  celerity  that  sets  manual  labor  at  defiance.  The  essential  principle  of  the  machine  is  iden- 
tical with  a slotting  machine  with  a horizontal  tool  movement,  the  tool-slide  being  worked  in  a similar 


756 


TOOLS. 


manner  by  a circular  slotted  disk.  In  planing  the  circular  ends  of  levers,  the.,  the  work,  after  being 
drilled,  is  fixed  on  an  ingenious  adjustable  mandril,  with  its  rectilineal  surface  in  a line  with  the  direc- 
tion of  the  traverse  of  the  tool.  A self-feeding  motion  causes  the  work  to  revolve  slowly  in  the  action 
of  cutting,  similarly  to  the  same  arrangement  in  the  slotting  machine.  By  detaching  this  geering  the 
tool  becomes  available  for  the  production  of  plane  surfaces  at  any  angle  by  an  appropriate  adjustment 
of  the  tool-holder — thus  it  unites  the  offices  usually  consigned  to  separate  tools,  and  is  a very  useful 
auxiliary  to  the  engineer. 

Though  not  in  immediate  connection  with  the  subject  of  planing,  we  may  here  mention  Mr.  Bodmers 
stand-cutting  machine.  This  tool  is  a species  of  planing  machine,  provided  with  a revolving  cutter,  and 
is  used  for  the  purpose  of  cutting  out  the  recesses  in  the  small  stand  bearings,  ifcc.,  in  cotton  and  other 
machinery,  a species  of  work  which  requires  the  utmost  precision  and  exactitude  of  management.  In 
preparing  and  fitting  up  the  supporting  pedestals  used  for  the  rollers  of  spinning  machinery  it  is  essen- 
tially necessary  to  preserve  their  line  of  bearing  perfectly  level,  otherwise  the  rollers  will  undergo  an 
injurious  strain  in  the  working.  To  accomplish  this  in  a speedy  manner,  Mr.  Bodmer  fixes  a row  of 
pedestals  upright  on  a movable  bed,  constructed  like  an  ordinary  planing  machine.  The  upright  fram- 
ing in  the  centre  of  the  machine  carries  a revolving  cutter,  similar  to  the  steel  cutters  used  for  cutting 
the  teeth  of  wheels ; the  row  of  pedestals,  which  are  placed  in  a line  with  the  motion  of  the  bed,  are 
then  passed  slowly  beneath  the  cutter,  thus  securing  an  accurate  adjustment  of  the  height  of  each. 

A machine  similar  in  principle  is  used  for  fluting  the  wooden  rollers  of  flax  machinery,  mechanism 
being  introduced  for  the  purpose  of  causing  the  rollers  to  make  a portion  of  a revolution  after  the  cut- 
ting of  each  groove. 

Slotting  machines,  in  their  general  principle  of  action,  may  be  defined  as  planing  machines  with 
movable  tools.  The  period  of  their  introduction  to  the  workshop  dates  among  the  latest  of  the  automa- 
tic tools  of  the  day,  as,  until  a short  time  back,  the  species  of  work  now  executed  by  them  was  entirely 
performed  by  the  file  and  chipping-tool.  As  a finished  specimen  of  this  tool  we  may  refer  the  reader 
to  Messrs.  Caird  & Co.’s  machine,  Figs.  3337,  3338,  3339,  3340. 

The  method  of  transmitting  motion  from  the  driving-gesr  to  the  reciprocating  tool  is  here  very  simple, 
and  the  machine,  as  a whole,  has  a very  handsome  appearance.  The  table,  in  addition  to  the  usual  rec- 
tilineal and  circular  motions,  is  provided  with  apparatus  for  setting  it  at  any  angle  to  suit  the  different 
varieties  of  work.  This  angular  motion  is  useful  in  cutting  the  key-seats  of  wheels,  where  a slight  in- 
clination is  necessary  to  suit  the  shape  of  the  fixing-key. 

In  such  a machine  as  the  one  before  us,  it  is  evident  that  the  size  of  the  work  capable  of  being  oper- 
ated upon  by  it,  is  circumscribed  by  the  distance  from  the  cutting  centre  to  the  edge  of  the  supporting 
pillar.  If  this  distance  is  increased  in  order  to  suit  the  dimensions  of  wheels  and  castings  of  a large 
size,  a greater  disadvantage  ensues,  namely,  an  increased  amount  of  unsteadiness  of  action.  Messrs. 
Nasmyth  & Gaskell  have  remedied  this  disadvantage  most  efficiently  by  doing  away  with  the  support- 
ing framing  of  the  machine,  and  causing  the  tool  to  cut  from  below  upwards.  The  machine  is,  as  it 
were,  entirely  reversed  in  this  modification,  the  driving  disk  and  geering  connected  with  the  slotting-bar 
being  placed  under  ground  in  a pit  made  for  the  purpose.  The  cutting  end  of  the  slotting-bar  projects 
upwards,  through  a fixed  cast-iron  table  on  the  floor  of  the  workshop,  upon  which  the  work  is  laid  in 
the  act  of  slotting.  As  in  this  arrangement  there  are  no  supports  to  interfere  with  the  work  on  the 
table,  it  is  evident  that  this  tool  possesses  an  unlimited  range  of  action.  In  another  modification  by  the 
same  firm,  this  object  is  attained  by  supporting  the  tool-slide  in  a bottom-plate  attached  to  the  floor,  to 
which  are  attached  four  strong  pillars,  carrying  a square  table  for  the  support  of  the  work,  at  the  height 
required  for  the  convenience  of  the  workman.  The  driving-geer,  in  this  instance,  consists  of  a horizontal 
shaft,  passing  under  the  table,  near  the  level  of  the  floor,  driven  by  a strap,  and  carrying  a pinion  geer- 
ing with  a large  spur-wheel,  which,  at  the  same  time,  serves  to  communicate  the  reciprocating  motion 
to  the  slotting-bar,  being  grooved  across  one  side,  for  the  purpose  of  receiving  the  traversing-pin  of  the 
connecting-rod.  The  self-acting  motion  of  the  table  is  extremely  neat  and  convenient.  The  spur-wheel 
shaft  carries  a small  eccentric,  the  rod  of  which  communicates  with  the  ratchet-wheels  of  two  shafts 
running  horizontally  at  right  angles  to  each  other,  beneath  the  movable  sides  of  the  table.  Each  of 
these  shafts  carries  screws,  one  of  which,  passing  beneath  the  centre  of  the  table,  gives  the  rectilineal 
motion,  while  the  other  geers  with  the  screw  teeth  cut  round  the  circumference  of  it,  and,  consequently, 
traverses  the  table  in  a circular  direction. 

We  have  already  discussed  the  philosophy  of  the  true  form  of  cutting  edge  for  drills,  as  well  as  the 
minor  species  of  tools  of  this  class ; it  remains  for  us,  therefore,  now  to  enter  upon  the  construction  of 
what  are  more  properly  termed  drilling  machines.  The  varieties  of  these  useful  machines,  as  used  by 
the  engineer,  are  so  numerous,  that  we  can  only  find  space  to  touch  upon  a few  of  those  best  adapted 
to  the  wants  of  the  workshop.  Practically  speaking,  drilling  machines  are  divisible  into  two  classes 
only,  namely,  the  common  vertical  pillar,  or  wall-side  drill,  and  the  radial  machines. 

For  a good  example  of  the  former  of  these  varieties  we  may  refer  the  reader  to  the  detailed  views  in 
Figs.  1122-1128,  of  Mr.  Whitworth’s  vertical  drill.  This  machine,  which  probably  takes  the  first  rank 
in  its  class,  is  independent,  being  provided  with  its  own  separate  frame  intended  to  be  screwed  to  the 
floor  without  the  additional  support  of  a pillar  or  wall.  Motion  is  communicated  to  the  drill-spindle  by 
an  arrangement  similar  to  the  back  geer  of  a lathe,  contained  in  an  opening  in  the  upper  portion  of  the 
frame.  The  rectilineal  feed  motion  of  the  drill-spindle  is  self-acting ; it  is  a beautifully  ingenious  ar- 
rangement, and  is  pre-eminently  deserving  of  attention.  The  upper  portion  of  the  spindle  between  its 
bearings  is  screwed  for  the  purpose  of  geering  with  the  inclined  teeth  of  a pair  of  worm-wheels,  placed 
one  on  each  side  of  it ; the  axes  of  which  work  in  bearings  attached  to  the  front  of  the  frame.  A com- 
pact friction-clip  worked  by  a vertical  screw  from  below  embraces  the  projecting  ends  of  these  axes,  by 
which  arrangement  the  revolution  of  the  wheels  may  be  completely  stopped  when  requisite.  Thus,  we 
will  suppose  the  tightening  screw  of  the  friction-clip  to  be  screwed  up  so  that  the  latter  holds  the  worm- 
wheels  firmly  in  their  position ; it  follows,  then,  that  if  the  drill  is  set  in  motion,  the  threads  upon  the 


TOOLS. 


757 


spindle  will  act  upon  the  teeth  of  the  worm-wheels  exactly  as  in  a nut,  and  a quick  descent  of  the  spin- 
dle will  be  the  result.  If  now  the  friction  is  slightly  relaxed,  then  the  speed  ot  the  descent  of  the  spin- 
dle will  have  diminished  so  much  as  is  due  to  the  slipping  round  of  the  worm-wheels.  In  this  manner 
any  amount  of  feed  motion  may  be  communicated  to  the  spindle  with  a nicety  unattainable  by  any  other 
means,  so  that  the  varying  hardness  of  the  metal  under  action  may  be  immediately  accommodated  by 
a speed  exactly  suitable  for  cutting  most  advantageously.  The  table  ot  the  machine  is  provided  most 
completely  with  all  the  requisite  movements,  and  may  be  raised  or  lowered  to  suit  the  work  by  a pinion 
working  in  a vertical  rack  attached  to  the  front  of  the  frame. 

In  Figs.  3652  to  3659  we  have  given  complete  views  of  Messrs.  Nasmyth  & Gaskell’s  drilling-ma- 
chine, which  differs  from  the  last  specimen  in  the  fact  of  its  being  destitute  of  a self-acting  feed  motion. 
The  downward  pressure  necessary  for  the  feed  of  the  tool  being  given  by  the  pressure  of  the  foot  act- 
ing on  a bottom  lever,  which  is  connected  by  a vertical  rod  at  the  back  of  the  frame,  with  a second 
lever  working  on  a bearing  at  the  top.  The  front  end  of  this  lever  works  a sliding  bearing  fitting  on 
the  top  of  the  spindle,  which  thus  receives  a downward  motion  according  to  the  pressure  of  the  foot,  the 
counter- weight  on  the  back  end  of  the  lever  bringing  up  the  spindle  again,  on  the  lever  being  released 
from  the  pressure  of  the  foot.  This,  as  an  independent  variable  motion,  is  very  convenient,  though  in- 
ferior in  nicety  to  that  used  by  Mr.  Whitworth. 

Fig.  3476  is  a front  view  of  the  self-acting  feed  motion 
applied  by  Mr.  Lewis,  of  Manchester,  to  a wall-side  drill. 

Here  the  vertical  spindle  a carries  a bevel-wheel  b,  into 
which  a second  bevel-wheel  c on  the  driving  cone-shaft 
geers.  The  spindle  works  in  two  bearings  d d,  attached 
to  a vertical  plate  bolted  to  the  wall.  A small  spur-wheel 
e is  keyed  on  the  spindle,  a little  above  the  lower  bearing ; 
this  wheel  geers  with  a second  wheel/,  which  carries  a 
sliding  bush  g,  so  that  it  may  be  thrown  in  and  out  of  geer 
with  the  driving-wheel  e at  pleasure.  The  shaft  li,  carry- 
ing this  latter  wheel,  passes  up  the  side  of  the  drill,  and 
carries  a second  spur-pinion  k at  its  upper  extremity,  geer- 
ing with  a large  wheel  l , the  bush  of  which  carries  a nut 
working  on  the  screw  m on  the  spindle. 

This  motion  may  be  driven  by  hand  at  pleasure  by  dis- 
connecting the  wheel  f and  working  a hand-wheel  fixed  on 
the  spindle  h. 

This  may  be  taken  as  a specimen  of  the  best  kind  of 
self-feeding  motions:  it  is  compact,  effective,  and  inexpen- 
sive. 

Of  pillar  drills,  the  modification  introduced  by  Messrs. 

Randolph,  Elliot  ifc  Co.,  of  Glasgow,  is  one  of  the  most  com- 
pact. This  drill  is  certainly  the  simplest  and  most  gener- 
ally applicable  of  its  class,  its  component  parts  being  con- 
fined to  a set  of  brackets  to  carry  the  drill-spindle,  without 
any  additional  frame,  the  office  of  which  is  supplied  by  any 
of  the  pillars  of  the  workshop.  The  spindle-brackets,  as 
well  as  those  for  supporting  the  table,  are  clamp-bolted 
to  the  pillar — the  spindle  being  worked  either  directly 
through  a speed  cone  or  by  double  geering,  as  applied  to 
lathes  generally.  The  self-acting  feed  motion  in  its  gen- 
eral details  is  similar  to  that  of  Mr.  Lewis.  The  table  is 
provided  with  a strong  central  foot,  to  which  two  project- 
ing brackets  at  the  foot  of  the  pillar  are  bolted ; it  is  thus 
fixed  immovably,  and  so  far  lacks  the  important  advan- 
tage possessed  by  a movable  table.  In  some  varieties  of 
drills  the  feed  motion  is  confined  entirely  to  the  table, 
which  is  worked  by  a rack  and  pinion  movement,  its  weight 
being  balanced  by  a counterpoise  attached  to  a chain  pass- 
ing over  a pulley  on  the  top  of  the  frame.  In  drills  in- 
tended for  boring  to  a considerable  depth,  this  arrangement  may  have  the  advantage  of  steadiness  of 
action,  otherwise  the  movable  spindle  is  in  every  respect  preferable. 

In  Figs.  3650  and  3651  we  have  given  two  views  of  Mr.  Whitworth’s  modification  of  the  second  class 
of  drilling  machines,  the  radial  drill.  A reference  to  this  drawing  will  show  that  it  is  an  arrangement 
on  a principle  quite  distinct  from  that  of  the  ordinary  drilling  machine.  In  the  radial  drill  the  motion 
of  the  spindle  is  not  confined  to  the  vertical  direction,  but  is  provided  with  a lateral  motion,  whereby  it 
may  be  set  to  any  portion  of  the  work  within  the  limits  of  the  radial  arm,  thus  superseding  one  of  the 
rectilineal  motions  of  the  table,  which  in  this  arrangement  need  only  travel  in  one  rectilineal  direction 
beneath  the  drill.  This  machine  is  likewise  provided  with  the  same  feed  motion  as  applied  by  this 
maker  to  his  ordinary  vertical  machine. 

Messrs.  Hick  make  use  of  a somewhat  different  arrangement  of  driving  and  feed  geer.  The  central 
frame  of  this  machine  consists  in  a short  hollow  circular  bracket,  having  a nut  fitted  on  its  upper  end 
for  the  purpose  of  receiving  a strong  square-threaded  screw,  which  carries  the  radial  arm  for  the  tool- 
slide.  The  vertical  motion  of  the  drill  is  therefore  not  confined  to  the  motion  of  the  spindle  in  its  own 
bearings,  but  the  whole  radial  arm  is  capable  of  a considerable  vertical  movement  by  turning  the  nut 
on  the  central  screw.  The  fast  and  loose  pulleys  for  the  driving  geer  are  placed  on  a vertical  shaft 


3476. 


758 


TOOLS. 


working  in  a bearing  on  the  top  of  the  radial  arm  immediately  over  the  centre  of  the  screw — motion 
being  communicated  from  it  to  the  drill-spindle  by  means  of  bevel  geer  as  in  Mr.  Whitworth’s  machine 
The  additional  horizontal  traversing  motion  of  the  spindle  is  effected  by  means  of  a pinion  keyed  on  a 
hand-wheel  shaft  and  geering  into  a rack  on  the  radial  arm  ; the  downward  motion  for  the  feed  is  given 
by  hand  by  means  of  an  overhead  ratchet  lever  connected  to  a ratchet-wheel  on  a short  horizontal  shaft, 
over  which  a chain  connected  to  a cross-head  on  the  drill-spindle  is  wound.  A rod  from  this  lever  is 
brought  within  the  reach  of  the  workman,  so  that  he  can  depress  the  spindle  at  pleasure,  the  upward 
motion  being  accomplished  by  means  of  a counter-weight  attached  to  a chain-pulley  on  the  ratchet- 
wheel  shaft.  A somewhat  similar  mode  of  central  movement  has  been  adopted  by  Mr.  Bodmer  in  his 
improved  radial  drill.  Here  the  main  central  support  consists  of  a strong  hollow  circular  pillar  provided 
with  wrought-iron  centres  at  top  and  bottom,  upon  which  it  revolves.  A screw  passes  down  the  centre 
of  this  pillar,  and  carries  a nut  attached  to  a bevel-wheel  on  a bracket  projecting  through  a vertical  slot 
in  the  pillar.  This  bracket  is  screwed  to  the  radial  arm  of  the  machine,  and  is  raised  or  lowered  by  a 
lever  handle  on  a shaft  carrying  a bevel-wheel  geering  with  the  one  referred  to  above  as  carrying  the 
nut  on  the  central  screw.  The  driving  geer  consists  of  an  overhead  horizontal  shaft  carrying  a bevel- 
pinion  working  in  a large  bevel-wheel  on  the  top  of  the  supporting  pillar ; the  latter  carries  a spur- 
wheel  geering  with  a pinion  on  a vertical  grooved  shaft  working  in  bearings  attached  to  the  pillar. 
This  shaft  carries  a sliding  Devel-wheel  provided  with  a key  to  fit  its  groove,  so  that  it  is  at  liberty  to 
rise  and  fall  with  the  radial  arm  without  revolving  loosely  on  its  shaft.  From  this  bevel-wheel  motion 
is  transmitted  by  a train  of  geering  to  the  drill-spindle  in  the  radial  arm,  in  the  usual  manner.  The 
self-acting  feed  motion  is  highly  ingenious  and  effective ; the  horizontal  driving-shaft  of  the  radial  arm 
carries  a small  band-pulley  from  which  motion  is  given  to  a short  horizontal  worm-wheel  shaft,  the  worm 
of  which  geers  with  a wheel  on  an  upright  shaft  carrying  a long  pinion  on  its  upper  extremity.  This 
pinion  geers  with  a spur-wheel  attached  to  the  nut  of  the  top  driving-screw  of  the  spindle,  which  thus 
receives  a regular  descending  motion  according  to  its  boring  speed.  By  detaching  this  geering,  the 
long  pinion  may  be  worked  by  hand  at  pleasure.  Although  for  some  specific  purposes  this  species  of 
drill  is  highly  useful,  yet  where  great  accuracy  is  required,  it  is  inferior  to  the  ordinary  pillar  or  wall- 
side  machine  on  account  of  its  want  of  steadiness  and  rigidity. 

Boring  machines  are,  abstractedly,  merely  modifications  of  the  larger  class  of  drills,  and  are  applied 
to  the  same  purposes. 

They  are  divisible  into  two  classes,  namely,  horizontal  and  vertical  machines.  The  latter  species  of 
machine  is  generally  considered  to  be  the  most  useful  for  engineering  works,  and  there  is  no  doubt  that 
it  possesses  some  great  advantages  over  the  former  one.  In  the  first  place,  the  vertical  position  of  the 
cylinder  entails  no  transverse  strain  upon  it,  which  would  be  pretty  considerable  in  a cylinder  of  large 
«ize  placed  horizontally.  Such  a strain  would,  of  course,  render  the  action  of  the  tool  extremely  uncer- 
tain, and  would  detract  materially  from  the  required  true  surface.  Again,  the  boring-bar  may  in  some 
sort  be  considered  as  liable  to  the  same  disadvantage  which  its  vertical  position  remedies.  Lastly,  the 
action  of  the  cutters  is  not  at  all  impeded  by  the  presence  of  the  turnings,  which  immediately  fall  to 
the  foot  of  the  cylinder  and  leave  the  cutter  free  at  each  progressive  step.  The  most  convenient  and 
secure  place  for  a boring-machine  of  a large  size  is  the  corner  of  the  workshop,  where  the  two  angular 
walls  form  firm  supports  for  the  framing  of  the  machine. 

Messrs.  Nasmyth  & Gaskell  have  produced  a useful  tool  of  this  particular  class;  the  framing  consists 
of  a stout  circular  bottom  casting,  provided  with  a clamping  ring  for  holding  down  the  cylinder  in  the 
act  of  boring,  and  an  overhear!  cross-beam  for  carrying  the  upper  extremity  of  the  boring-bar  spindle. 
The  footstep  of  the  boring-bar's  placed  beneath  the  ground  floor  of  the  shop,  where,  as  well  as  for  a 
portion  of  the  driving  geering,  an  excavation  is  purposely  made  to  receive  them.  The  driving-pulleys 
are  placed  outside  this  pit ; they  communicate  with  an  oblique  shaft,  which  carries  a worm  on  its  end, 
geering  with  a large  worm-wheel  near  the  foot  of  the  boring-bar,  to  which  motion  is  thus  given.  The 
cutter-boss  is  traversed  in  the  usual  manner  by  a longitudinal  screw  in  the  bar,  but  a different  method 
is  adopted  for  returning  it  after  the  first  rough  cut.  Immediately  this  is  accomplished  the  cutter-boss 
is  detached  from  the  nut  of  the  traversing  screw,  and  is  hauled  up  alone  by  a small  crane  attached  to 
the  machine ; the  cutters  are  then  reset  and  the  finishing  cut  is  gone  over. 

A machine  somewhat  similar,  but  of  gigantic  dimensions,  has  been  constructed  by  the  same  engineers 
for  the  Great  Western  Steam  Navigation  Company,  for  the  purpose  of  boring  out  the  cylinders  of  the 
Great  Britain  steamer. 

In  this  machine,  the  entablature  carrying  the  upper  end  of  the  boring-bar  is  supported  on  two  mas- 
sive pillars  of  masonry,  placed  one  on  each  side  of  the  boring-bar.  The  feed-motion  of  the  cutters  is 
novel  and  ingenious  in  the  extreme ; it  consists,  primarily,  of  an  internal  screwed  collar  fixed  on  the  upper 
surface  of  the  entablature,  and  surrounding  the  boring-bar.  A train  of  geering,  terminating  in  a pinion 
working  into  a rack  running  down  the  side  of  the  boring-bar,  is  attached  to  the  latter  and  revolves  with 
it.  The  first  wheel  of  the  train  is  a species  of  crown-wheel,  its  teeth  being  set  at  right  angles  to  its  axis 
of  motion ; this  geers  with  the  internal  threads  of  the  screwed  collar  before  mentioned,  so  that  by  this 
means,  the  train  is  set  in  motion  by  the  revolution  of  the  bar,  and  the  cutter-boss,  which  is  attached  to 
the  lower  end  of  the  rack,  is  raised  and  lowered  at  pleasure. 

Mr.  Walton,  of  Leeds,  has  introduced  a highly  effective  boring  machine,  with  columnar  framing  in- 
tended principally  for  boring  the  apertures  in  the  tube  plates  of  locomotive  engines.  The  machine  is 
capable  of  drilling  a series  of  parallel  holes  on  a surface  of  five  feet  square,  without  refixing  the  object 
under  operations,  the  tool-holder  and  the  table  being  movable  at  right  angles  to  each  other.  This  bor- 
ing machine  may  be  considered  as  a magnified  drill,  as  the  spindle  is  fed  longitudinally,  no  cutter-boss 
being  attached.  The  framing  consists  of  two  plain  columns,  coupled  at  the  top  by  a suitable  entabla- 
ture, and  carrying  two  other  transverse  beams  for  the  support  of  the  drill-spindle  and  driving-gear 
The  self- feeding  motion  is  similar  to  that  illustrated  by  Fig.  347  6,  and  it  may  also  be  worked  by  hand 
in  the  same  way 


TOOLS. 


759 


The  spindle  is  capable  of  a vertical  travel  of  24  inches,  and  is  consequently  well  suited  for  boring 
out  the  small  cylinders  of  locomotives,  Ac.,  as  well  as  for  boring  out  the  eyes  of  carriage  and  othei 
wheels,  which  it  will  receive  up  to  6 feet  in  diameter. 

Figs.  2547  and  2548  now  introduce  to  us  the  second  species  of  boring  machine,  the  horizontal  one 
Our  example  is  intended  for  the  heaviest  kind  of  work  in  the  engine-shop,  and  is  purposely  very  strongly 
constructed.  The  arrangement  of  the  train  of  driving-geer  allows  of  a considerable  latitude  of  speed 
of  the  cutters ; the  changes  by  alteration  in  the  geering  permit  of  as  small  a variation  as  1 to  1-J,  so 
that  any  speed  within  the  entire  range  may  be  obtained  within  Jth  of  the  one  required.  In  Figs.  2542 
and  2543  we  have  given  a still  more  complete  tool  by  Messrs.  Kinmonds,  Hutton,  and  Steel,  of  Dun- 
dee. It  is  provided  with  a slide-rest  and  tool-holder,  and  thus  becomes  available  for  turning  as  well 
as  boring.  This  is  a very  valuable  machine,  and  where  ground  space  is  an  object  in  the  w7orksbop,  will 
be  found  highly  convenient  from  the  saving  of  space  which  it  effects.  The  proper  speed  at  which  the 
cutter  should  pass  over  the  surface  of  the  metal  may  be  stated  as  from  6 to  7 feet  per  minute,  though 
this  must,  of  course,  be  dependent  in  a considerable  degree  upon  the  relative  hardness  of  the  metal. 
Until  a few  years  back,  cannon  were  cast  with  a core,  in  the  same  manner  as  steam-engine  cylinders 
are  now.  Experience  has,  however,  pointed  out  the  fallacy  of  this  method,  as  it  was  impossible  to 
make  a true  bore,  the  cutter  having  a tendency  to  follow  the  inaccuracies  of  the  yet  rough  surface.  In 
addition  to  this,  the  guns,  when  cast  hollow,  have  a tendency  to  become  spongy  near  the  inner  surface 
of  the  bore.  To  remedy  these  defects,  all  ordnance  are  now  cast  solid,  and  thus  the  metal  is  rendered 
closer  in  the  grain,  and  any  “ blown”  or  defective  parts  are  confined  to  the  centre  of  the  metal,  when 
they  are  cut  out  in  boring.  Guns  are  bored  in  a manner  directly  the  reverse  of  that  employed  in  pre 
paring  steam-engine  cylinders.  The  bed  of  the  machine  employed  for  boring  out  guns  is  provided  with 
two  pedestals  having  bearings  of  a considerable  diameter,  in  which  the  gun  itself  is  caused  to  revolve, 
the  cutter  remaining  stationary  on  a sliding-carriage.  The  cutter  is  kept  up  to  its  work  by  means  of  a 
weighted-lever,  attached  to  a pinion-shaft  beneath  the  bed  of  the  machine.  This  pinion  geers  with  a 
rack  attached  to  the  cutter-carriage,  which  is  thus  impelled  forward  towards  the  gun,  until  the  weights 
in  the  loaded  lever  reach  near  the  ground,  when  the  lever  is  raised  and  the  weights  reset  by  a ratchet- 
wheel. 

The  punching  machine,  from  being  confined  to  the  tin-smith  and  ornamental  metal-worker’s  shop,  has 
latterly  become  an  instrument  of  no  slight  importance  to  the  engineer,  whose  ponderous  adaptations  of 
this  tool  excite  the  greatest  wonder  in  the  mind  of  a stranger  unaccustomed  to  their  operations.  Here 
the  punch  or  cutting  tool  seems  to  pass  through  an  enormously  thick  piece  of  cold  metal,  as  if  the  latter 
was  so  much  pasteboard,  the  whole  of  the  operation  being  conducted  without  producing  the  least  noLe. 

In  Fig.  3174  we  have  given  various  views  of  a compact  and  convenient  punching  machine,  constructed 
by  Messrs.  Caird,  of  Greenock.  The  framing  consists  of  one  solid  casting,  open  in  the  centre  for  the 
reception  of  the  large  driving  bevel-wheel  on  the  horizontal  puncliing-shaft.  The  driving  geering  and 
fly-wheel  for  steadying  the  motion  are  placed  overhead,  so  as  to  be  completely  out  of  the  way,  and 
leaving  a clear  space  all  round  the  machine  for  the  workmen.  The  shearing  and  punching  apparatus 
being  on  two  opposite  sides  of  the  machine,  these  two  operations  may  be  conducted  at  the  same  time, 
without  any  risk  of  confusion  among  the  men. 

-Of  late  years,  the  system  of  riveting  by  steam  power  has  made  rapid  progress,  and  promises  in  all 
large  works  to  supersede  entirely  the  old  laborious  and  noisy  process  of  riveting  by  hand.  We  are  in- 
debted to  Mr.  Fairbairn,  of  Manchester,  for  the  introduction  of  this  machine,  who  invented  it  upon  an 
emergency  to  supply  the  loss  of  a set  of  hand  riveters  who  had  left  their  employment  on  account  of 
some  business  disagreement.  Mr.  Fairbairn’s  machine,  see  Figs.  3226-7,  is  a highly  elegant  and  efficient 
apparatus.  The  essential  principle  of  the  machine  is  that  of  the  knee-joint  lever,  as  applied  to  printing- 
presses.  Motion  is  given  to  this  lever  by  means  of  a revolving-cam  driven  by  suitable  geeriug  ; this 
cam  acting  upon  a loose  anti-friction  pulley,  placed  at  the  centre  joint  of  the  lever.  The  saving  by  the 
use  of  this  machine  is  very  great,  and,  what  is  of  no  small  consequence,  the  whole  operation  of  riveting 
is  performed  in  silence  ; the  system  of  pressure,  too,  has  the  advantage  of  leaving  the  metal  of  the  rivets 
in  its  original  state.  By  the  old  plan  of  hammering,  the  rivets  were  extremely  subject  to  crystalliza- 
tion, and  as  a natural  consequence,  numbers  of  the  heads  gave  way  in  the  finishing. 

We  have  seen  a section  of  two  pieces  of  boiler-plate  riveted  together  in  this  manner,  the  section  be- 
ing taken  through  the  centre  of  the  rivet,  and  it  was  remarkable  to  see  how  the  pressure  of  the  ma- 
chines had  forced,  as  it  were,  the  metal  of  the  rivet  into  all  the  interstices  of  the  plates,  incorporating 
the  two  so  as  to  be  scarcely  distinguishable  from  one  piece  of  solid  metal.  M.  Lemaitre,  of  Paris,  has 
successfully  combined  the  two  operations  of  riveting  and  punching,  in  one  machine,  which  he  actuates 
by  the  direct  pressure  of  steam,  without  the  intervention  of  additional  geering.  We  have  detailed  this 
machine  fully  in  Fig.  3220,  where  also  is  shown  M.  Lemaitre’s  arrangement  for  riveting  long  and  nar- 
row tubes,  which  is  very  ingeniously  contrived. 

Messrs.  Schneider,  of  Creusot,  in  France,  have  also  applied  the  direct  action  of  the  steam  to  the  pur- 
pose of  riveting.  Their  modification  closely  resembles  in  principle  the  plan  adopted  by  Mr.  Fairbairn  ; 
the  piston  of  the  steam  cylinder  is  jointed  directly  to  the  central  joint  of  the  “ knee”  combination,  and 
the  rise  and  fall  of  the  former  of  course  gives  a lateral  traversing  motion  to  the  compressing  ferrule. 
Latterly,  also,  Messrs.  Garforth,  of  Duckintield,  have  applied  the  pressure  of  steam  in  a still  more  direct 
manner.  The  shaft  carrying  the  compressing  ferrule,  for  forming  the  rivet,  is  at  the  same  time  the 
piston-rod.  the  cylinder  of  which  is  placed  horizontally  in  the  frame  of  the  machine.  It  is  evident  that 
in  this  plan,  as  no  mechanical  power  intervenes  between  the  point  of  action  of  the  steam,  and  the  point 
of  resistance,  a very  large  cylinder  must  be  used  to  produce  the  required  pressure,  and  consequently  a 
large  amount  of  steam  must  be  used  at  each  stroke  of  the  riveter.  There  is  no  doubt  but  that  this 
machine  may  be  arranged  to  work  at  a high  speed,  but  we  think  it  must  fail  to  work  so  ecenomicahy 
as  the  machines  worked  by  a small  piston  assisted  by  additional  mechanical  power. 

Mr.  Walton,  of  Leeds,  has  produced  an  extremely  useful  punching  and  shearing  machine,  which  is 


TOOLS,  TURNING. 


7 1>0 


capable  of  being  worked  either  by  manual  or  mechanical  power.  The  framing  consists  of  a single 
casting,  having  a stud  keyed  in  the  thickness  of  the  metal  near  its  tep,  for  the  purpose  of  carrying  the 
fly-wheel  and  driving-pinion,  which  are  cast  together.  These  work  loose  on  the  stud,  the  pinion  geering 
with  a large  spur-wheel  keyed  on  the  horizontal  eccentric  punebing-shaft.  A slot  is  cast  through  the 
centre  of  the  frame  for  the  reception  of  this  shaft,  suitable  bearings  for  carrying  it  being  placed  within 
the  slot;  the  projecting  end  of  the  shaft  is  slightly  eccentric,  for  the  purpose  of  giving  motion  to  the 
vertical  punching  and  shearing  shaft.  The  latter  consists  of  a heavy  piece  of  metal,  having  a horizon- 
tal slot  in  the  centre,  for  the  purpose  of  allowing  a clear  space  for  the  lateral  working  of  the  eccentric 
end  of  the  driving-shaft.  Suitable  bearings  are  attached  to  the  front  of  the  frame,  in  which  the  punch- 
ing-shaft  is  arranged  to  slide,  the  top  of  the  latter  being  the  shearing  end,  and  the  bottom  carrying  the 
punch,  the  matrix  for  which  is  fixed  in  a projecting  piece  cast  to  the  frame. 

The  machine  is  adapted  to  punch  holes  up  to  £ inch  in  diameter  in  plates  § inch  in  thickness,  at  any 
distance  from  the  edge  not  exceeding  7^  inches,  the  frame  being  hollowed  out  to  this  extent  to  permit 
of  the  entrance  of  the  plates.  The  shears  are  capable  of  cutting  plates  § inch  in  thickness,  and  12  inches 
breadth,  without  curling  the  piece  sheared  off. 

The  construction  of  this  machine  is  exceedingly  simple,  and  being  set  in  an  independent  framing  of 
its  own,  may  be  moved  to  any  part  of  the  workshop  with  facility.  A somewhat  similar  machine,  but 
much  more  complete  in  its  details,  has  been  constructed  by  Messrs.  Nasmyth  and  Gaskell.  Here  the 
punching-slide  is  provided  with  four  punches,  by  which  means  the  same  number  of  holes  are  punched 
at  each  stroke  of  the  machine.  The  punching  operation  is  also  made  self-acting,  by  an  arrangement  of 
a self-moving  table  for  carrying  the  work.  The  plates  intended  to  be  punched  are  fixed  in  the  usual 
manner  on  a travelling-table,  moving  on  wheels  set  to  run  oc  i pair  of  triangular  rails.  A long  notched 
bar  is  attached  by  means  of  brackets  to  the  under  side  of  this  table ; this  is  arranged  to  traverse  the 
table  in  the  following  manner : — The  large  driving-wheel  on  the  eccentric  shaft  carries  a pin  fixed  in 
the  side  of  its  rim,  which,  once  during  each  revolution,  comes  in  contact  with  a lever  connected  to  a 
ratchet-catch  adapted  to  take  into  the  notches  of  the  bar  before  mentioned  ; thus  each  revolution  of  the 
spur-wheel  causes  the  table  to  advance  a distance  equal  to  the  length  included  between  each  notch  in 
the  bar. 

In  Fig.  3100  we  have  detailed  a machine  intended  for  the  bending  of  wrouglit-iron  plates.  This  ma- 
chine, owing  to  the  increase  of  iron  ship-building,  has  latterly  risen  to  be  of  great  importance  to  the 
engineer  and  ship-builder.  The  present  machine  being  principally  intended  for  the  use  of  the  ship- 
building yard,  where  few  plates  are  required  to  have  a regular  curve  throughout,  is  not  provided  with 
geering  for  simultaneously  altering  the  positions  of  the  ends  of  the  front  roller.  This  arrangement 
allows  of  the  setting  of  one  of  the  ends  of  the  roller  at  any  position  with  regard  to  the  other,  so  as  to 
give  any  required  twist  to  the  plate. 

In  the  original  application  of  the  bending-rollers  to  the  curving  of  boiler  plates,  none  of  the  rollers 
touch  each  other,  and  they  are  placed  so  that  lines  drawn  from  centre  to  centre  form  an  equilateral 
triangle,  the  upper  central  roller  being  made  adjustable  for  the  different  curvatures  required ; this 
arrangement  is,  however,  now  entirely  superseded  by  that  depicted  in  Mr.  Napier’s  machine. 

We  take  this  occasion  to  acknowledge  our  indebtedness  to  the  Engineer  and  Machinist’s  Assistant, 
published  by  Blackin  and  Son,  Glasgow,  for  the  very  valuable  articles  on  Geering,  as  also  this  one  on 
Tools.  The  work  mentioned  should  be  in  the  hands  of  every  engineer  and  machinist. 

TOOLS,  TURNING.  The  process  of  turning  is  accomplished  with  considerably  more  facility,  truth, 
and  expedition,  than  any  other  process  requiring  cutting  tools,  because  in  the  most  simple  application 
of  the  art,  the  guide  principle  is  always  present,  namely,  that  of  rotation.  The  expedition  of  the  process 
is  due  to  its  being  uninterrupted  or  continuous,  except  as  regards  the  progressive  changes  of  the  tool, 
and  which  is  slowly  traversed  from  part  to  part,  so  as  to  be  nearly  always  in  action. 

To  choose  the  most  simple  condition,  let  us  suppose  the  material  to  be  in  rotation  upon  a fixed  axis, 
and  that  a cutting  tool  is  applied  to  its  surface  at  fifty  places.  .Provided  the  tool  remain  quiescent  at 
one  place  for  the  period  of  one  revolution  of  the  material,  the  parts  acted  upon  will  each  become  one 
circle ; because  the  space  between  the  tool  and  the  axis  is  for  a period  constant,  and  the  revolution  of 
the  material  converts  the  distance  of  the  tool  from  the  centre  into  the  radius  of  one  circle,  and  the  same 
is  equally  true  of  the  fifty  positions. 

The  fifty  circles  will  be  concentric,  or  parallel  with  each  other,  because  the  same  axis,  extended  or 
continued  as  a line,  remains  constant,  or  is  employed  for  each  of  them ; and  therefore  conceiving  the 
fifty  circles  to  be  as  many  parts  of  the  outline  of  a vase  or  other  object,  simple  or  complex,  it  will  be 
strictly  symmetrical,  or  equidistant  from  the  central  line  at  corresponding  parts. 

Each  of  the  fifty  circles  will  also  become  the  margin  of  a plane  at  right  angles  to  the  axis,  and  which 
axis  being  a straight  line,  the  whole  of  the  circles  will  be  parallel,  and  therefore  the  top  and  bottom 
of  the  vase  will  be  also  exactly  parallel.  And  yet  all  these  accurate  results  must  inevitably  occur,  and 
that  without  any  measurement,  provided  the  material  revolve  on  one  fixed  axis,  and  that  the  tool  is 
for  a short  period  constant  or  stationary  at  each  part  of  the  surface — conditions  inseparable  from  the 
turner’s  art. 

The  principle  of  rotation  upon  a fixed  axis  removes  the  necessity  for  many  of  the  steps  and  measure- 
ments required  to  produce  with  accuracy  the  various  angular  solids  employed  in  carpentry  and  many 
other  arts. 

The  turner’s  box  consists  of  two  pieces,  as  the  bottom  and  its  four  sides  are  resolved  into  one  piece— 
when  of  wood,  by  nature  in  the  forest ; wThen  of  metal,  by  man  in  the  crucible.  The  surfaces  are  there- 
fore reduced  to  eight,  namely,  the  inner  and  outer  surfaces  of  the  bottom  and  lid  amounting  to  four,  and 
the  inner  a-nd  outer  sides  or  margins,  amounting  to  four  also,  and  the  revolution  of  the  work  upon  one 
axis  places  the  eight  in  exact  and  true  relation  with  extreme  rapidity. 

For  example,  the  ends  or  terminal  planes  of  the  box  are,  from  necessity,  at  right  angles  to  the  axis  of 
rotation,  and  parallel  with  each  other.  In  each  of  these  superficies  the  question  of  being  in  cr  out  oi 


TOOLS,  TURNING. 


761 


winding  ceases ; as,  if  straight,  they  can  only  be  planes  or  cones,  and  which  the  one  straight  edge  imme- 
diately points  out. 

The  principle  of  rotation  insures  circularity  in  the  work,  and  perpendicularity  or  equality  as  regards 
the  central  line  ; it  only  remains,  therefore,  to  attend  to  the  outline  or  contour.  The  right  line  serves  to 
produce  the  cylinder,  which  is  a common  outline  for  a box ; and  the  employment  of  mixed,  flowing,  and 
arbitrary  lines,  produces  vases  and  ornaments  of  all  kinds,  the  beauty  of  which  demands  attention  alone 
to  one  single  element,  or  conception,  namely,  that  of  form ; and  in  the  choice  and  production  of  which  a 
just  appreciation  of  drawing  and  proportion  greatly  assist. 

In  the  art  of  drawing,  it  is  almost  essential  to  the  freedom  of  the  result,  that  the  lines  should  be  de- 
lineated at  once,  and  almost  without  after  correction ; in  the  art  of  turning,  it  is  always  desirable 
to  copy  a drawing  or  a sketch,  but  having  nearly  attained  the  end,  the  tool  may  be  continually  re- 
applied, partially  to  remove  any  portions  which  may  appear  redundant,  until  the  most  scrupulous  eye 
is  satisfied. 

The  combining  of  the  several  parts  of  turned  objects,  as  the  separate  blocks  of  which  a column  or 
other  work  is  composed,  is  greatly  facilitated  from  the  respective  parallelism  of  the  ends  of  the  pieces 
of  which  turned  objects  consist ; and  the  circular  tenons  and  mortises,  whether  plain  or  screwed,  place 
the  different  pieces  perpendicular  and  central  with  very  little  trouble. 

These  several  and  most  important  facilities  in  the  art  of  turning,  are  some  amongst  the  many  reasons 
for  its  having  obtained  so  extensive  and  valuable  an  employment  in  the  more  indispensable  arts  of  life, 
as  well  as  in  its  elegances. 

The  tools  us.ed  in  turning  the  woods  act  much  in  the  manner  of  the  blades  of  the  carpenter’s  planes; 
but  as  we  have  now,  at  all  times,  a circular  guide  in  the  lathe-mandrel,  we  do  not  require  the  stock  ot 
the  plane  or  its  rectilinear  guide.  Although  if  we  conceive  the  sole  of  the  plane  applied  as  the  tangent 
to  the  circle,  the  position  it  would  give  is  nearly  retained,  but  we  are  no  longer  encumbered  with  the 
stock  or  guide.  In  turning-tools  for  soft  woods,  the  elevation  of  the  tool  and  the  angle  of  its  edge  are 
each  of  them  less  than  in  ordinary  planes,  and  in  those  for  the  hard  woods  both  angles  are  greater. 

Tor  example,  the  softest  woods  are  turned  with  tools  the  acute  edges  of  which  measure  about  20  to 
30  degrees,  and  are  applied  nearly  in  coincidence  with  the  tangent,  as  in  Fig.  3477. 


These  tools  closely  assimilate  to  the  spokeshave,  which  is  the  plane  of  the  lowest  pitch  and  keenest 
edge.  On  the  contrary,  the  hardest  woods  may  be  turned  with  the  above  soft-wood  tools,  applied  just 
as  usual ; but  on  the  score  of  economy  and  general  convenience,  the  edges  are  thickened  to  from  60  tc 
80  degrees,  and  the  face  of  the  tool  is  applied  almost  horizontally  on  the  lathe-rest,  or  as  a radius  to  the 
circle,  as  in  Fig.  3478,  thus  agreeing  with  the  opposite  extreme  of  the  planes,  in  which  the  cutter  is 
perpendicular  and  much  less  acute,  as  in  the  scraping  and  toothing  planes,  which  are  only  intended  to 
6crape,  and  not  to  cut. 

The  hard-wood  tools  may  be  figured  and  employed  as  scrapers  in  turning  the  members  of  the  capital 
or  the  base  of  a column,  or  similar  object  in  hard  wood  or  ivory ; but  if  we  try  the  same  tools  on  deal, 
ash,  and  other  soft  woods,  we  shall  in  vain  attempt  to  produce  the  capital  of  a column,  or  even  its  cy- 
lindrical shaft,  with  a thick  horizontal  tool  as  in  hard  wood  ; for  the  fibres  would  not  be  cut,  but  forcibly 
torn  asunder,  and  the  surface  would  be  left  coarse  and  ragged. 

But  a reference  to  the  planes  with  which  the  joiner  proceeds  across  the  fibres  of  deal,  will  convey  the 
particulars  suited  to  the  present  case ; the  iron  is  always  thin  and  sharp,  and  applied  in  an  oblique 
manner,  so  as  to  attack  the  fibre  from  the  one  end,  and  virtually  to  remove  it  in  the  direction  of  its 
length. 

It  is  proposed  now  to  describe  some  of  the  more  important  of  the  turning  tools,  commencing-  with 
those  employed  on  the  soft-grained  woods,  but  it  would  be  both  hopeless  and  unnecessary  to  attempt 
the  notice  of  all  the  varieties  which  are  to  be  met  with  in  the  hands  of  different  individuals;  and  only 
so  much  will  be  here  advanced  as,  it  is  hoped,  may  serve  to  explain  the  modifications  of  the  general 
principles  of  cutting  tools  to  some  of  the  more  usual  purposes  of  turning.  To  avoid  repetition,  it  may 
be  observed,  that  in  general  the  position  of  the  tool  for  turning  the  cylinder,  and  secondly,  that  for  the 
flat  surface  or  plane,  will  be  alone  described.  For  works  of  intermediate  angles,  whether  curves  or 
flowing  lines,  the  position  of  the  tool  slides  from  that  for  the  cylinder  to  that  for  the  plane,  or  the  re- 
verse ; and  these  changes  will  be  readily  made  apparent  when  the  reader  gradually  moves  either  a 
tool,  or  even  a rod  of  wood,  from  the  one  to  the  other  of  the  described  positions. 

It  may  be  added  that  most  of  the  tools  for  metal  are  applied  direct  from  the  grindstone,  the  oilstone 
being  used  for  such  tools  only  as  are  employed  for  the  more  delicate  metal-works,  or  for  the  last  finish 
of  those  ot  stronger  kinds;  all  the  tools  for  wood,  ivory,  and  similar  materials,  are  invariably  sharpened 
on  the  oilstone.  It  may  be  desirable  to  remark,  in  addition,  that  the  rough  exterior  faces  of  all  works 
should  be  turned  with  narrow  or  pointed  tools,  and  only  a narrow  portion  at  a time,  until  the  sur- 


7G2 


TOOLS,  TURNING. 


faces  are  perfectly  true  or  concentric ; as  wide  flat  tools  applied  to  rough  irregular  surfaces,  espe 
daily  of  metal,  would  receive  a vibratory,  or  rather  an  endlong  motion,  quite  incompatible  with  truth 
of  work. 

Turning-tools  for  soft  wood. — Angle  20°  to  30° — Figures  generally  half  size. — The  tools  most  gen- 
erally used  for  turning  the  soft  woods  are  the  gouge  and  chisel,  Figs.  3178  to  3479,  wherein  they  are 
shown  of  one-fourth  their  medium  size ; they  vary  from  one-eighth  to  two  inches  wide ; and  as  they  are 
never  driven  with  the  mallet,  they  do  not  require  the  shoulders  of  the  carpenter’s  tools,  they  are  alsc 
ground  differently.  The  turning-gouge  is  ground  externally  and  obliquely,  so  as  to  make  the  edge 
elliptical,  and  it  is  principally  the  middle  portion  of  the  edge  which  is  used ; the  chisel  is  ground  from 
both  sides,  and  with  an  oblique  edge,  and  Figs.  3481  and  3482  represent  the  full  thickness  of  the  chise1 
and  its  ordinary  angles,  namely,  about  25  to  30  degrees  for  soft,  and  40  for  hard  woods.  The  gouges 
and  chisels  wider  than  one  inch  are  almost  invariably  fixed  in  long  handles,  measuring  with  the  blades 
from  15  to  24  inches ; the  smaller  tools  have  short  handles,  in  all  from  8 to  12  inches  long. 


Fig.  3477  shows  the  position  of  the  gouge  in  turning  the  cylinder ; the  bevel  lies  at  a tangent,  and  tha 
tool  generally  rests  on  the  middle  of  the  back,  or  with  the  concave  side  upwards,  the  extremity  of  the 
handle  is  held  in  the  right  hand  close  to  the  person,  and  the  left  hand  grasps  the  blade,  with  the  fingers 
folded  beneath  it,  and  in  this  manner  the  gouge  is  traversed  along  the  cylinder. 

For  turning  the  flat  surface  the  gouge  is  supported  on  its  edge,  that  is,  with  the  convex  side  towards 
the  plane  of  the  work,  and  with  the  handle  nearly  horizontal,  to  bring  the  centre  of  the  chamfered  edge 
in  near  coincidence  with  the  plane ; the  tool  is  inclined  rather  more  than  tire  angle  at  which  its  chamfer 
is  ground,  and  it  is  gradually  thrust  from  the  margin  to  the  centre  of  the  work. 

The  gouge  is  also  used  for  hollow  works,  but  this  application  is  somewhat  more  difficult.  For  the 
internal  plane,  the  position  is  almost  the  same  as  for  the  external,  except  that  the  blade  is  more  inclined 
horizontally,  that  it  may  be  first  applied  in  the  centre  to  bore  a shallow  hole,  after  which  the  tool  is 
traversed  across  the  plane  by  the  depression  of  the  hand  which  moves  the  tool  as  on  a fulcrum,  and  it  is 
also  rotated  in  the  hand  about  the  fourth  of  a circle,  so  that  in  completing  the  margiu  or  the  internal 
cylinder  the  tool  may  lie  as  in  Fig.  3477,  but  with  the  convex  instead  of  the  concave  side  upwards,  as 
there  shown. 

In  Figs.  3483  and  3484  are  represented  the  plans,  and  in  Figs.  3485  and  3486  the  elevations  of  the 
hook-tools  for  soft  wood,  which  may  be  called  internal  gouges  ; they  differ  somewhat  in  size  and  form  : 
the  blades  are  from  6 to  12  inches  long,  the  handles  12  to  15.  They  are  sharpened  from  the  point 
around  the  hook  as  far  as  the  dotted  lines,  mostly  on  one,  sometimes  on  both  sides,  as  seen  by  the  sec- 


TOOLS,  TURNING. 


763 


tions.  The  hook-tools  follow  very  nearly  the  motion  of  the  gouge  in  hollowing,  the  rest  is  placed  rathe, 
distant  and  oblique ; the  tool  is  moved  upon  it  as  a fulcrum,  and  it  is  also  rotated  in  the  hand,  so  as  al- 
ways to  place  the  bevel  of  the  tool  at  a very  small  inclination  to  the  tangent. 

The  finishing  tools  used  subsequently  to  the  gouges  or  hook-tools  have  straight  edges  ; the  chisel,  Fig 
3487,  is  the  most  common ; its  position  closely  resembles  that  of  the  gouge,  subject  to  the  modifications 
called  for  by  its  rectilinear  edge.  If,  for  example,  the  edge  of  the  chisel  were  just  parallel  with  the  axis 
of  the  cylinder,  it  would  take  too  wide  a hold  ; there  would  be  risk  of  one  or  other  corner  digging  into 
the  work,  and  the  edge,  from  its  parallelism  with  the  fibres,  would  be  apt  to  tear  them  out.  All  these 
inconveniences  are  avoided  by  placing  the  edge  oblique,  as  in  Fig.  3487,  in  which  the  tool  may  be  sup- 
posed to  be  seen  in  plan,  and  proceeding  from  right  to  left,  Fig.  3477  being  still  true  for  the  other  view; 
the  tool  is  turned  over  to  proceed  from  left  to  right,  and  both  corners  of  the  tool  are  removed  from  the 
work,  by  the  obliquity  of  the  edge.  The  tool  may  be  ground  square  across,  but  it  must  be  then  held  in 
a more  sloping  position,  which  is  less  convenient. 

• 3489. 


Turning  a flat  surface  with  the  chisel  is  much  more  difficult.  The  blade  is  placed  quite  on  edge,  and 
with  the  chamfer  in  agreement  with  the  supposed  plane  a b c,  Fig.  3481 ; the  point  of  the  chisel  then  cuts 
through  the  fibres,  and  removes  a thin  slice  which  becomes  dished  in  creeping  up  a d,  the  bevel  of  the 
tool ; it  then  acts  something  like  the  scoring-point  of  the  planes,  or  the  point  of  a penknife.  Flat  sur- 
faces, especially  those  sunk  beneath  the  surface,  as  the  insides  of  boxes,  are  frequently  smoothed  with 
an  ordinary  firmer  chisel,  which  is  ground  and  sharpened  with  one  bevel,  but  rather  thicker  than  for 
carpentry.  The  edge  is  then  burnished  like  the  scraper,  and  it  is  applied  horizontally  like  a hard-wood 
tool,  as  in  Fig.  3478,  but  against  the  face  or  plane  surface.  The  wire  edge  then  lies  in  the  required  po- 
sition, but  it  must  be  frequently  renewed. 

The  broad,  represented  in  three  views  in  Fig.  3488,  endures  much  longer,  but  it  requires  to  be  held 
downwards  or  underhand  at  about  an  angle  of  40  to  50  degrees  from  the  horizontal,  in  order  to  bring  its 
edge  into  the  proper  relation  to  the  plane  to  be  turned.  Another  form  of  the  broad  is  also  represented 
in  Fig.  34-89  ; it  is  a cylindrical  stem,  upon  the  end  of  which  is  screwed  a triangular  disk  of  steel,  some- 
times measuring  three  inches  on  the  sides,  and  sharpened  externally  on  each  edge : this  tool  requires  the 
same  position  as  the  last.  Broads  of  the  forms  b c are  also  used,  but  principally  for  large  works  the 
plank  way  of  the  grain.  Similar  tools  are  also  used  for  turning  pewter  wares. 

For  the  insides  of  cylinders  the  side-tool,  Fig.  3490,  which  is  represented  in  three  views,  is  sometimes 
used;  it  is  sharpened  on  both  edges,  and  applied  horizontally.  The  tool  Fig.  3491,  also  shown  in  three 
views,  serves  both  for  the  sides  and  the  bottoms  of  deep  works,  but  it  does  not  admit  of  being  turned 
over;  and  Fig.  3492  is  another  form  of  the  same  tool  for  shallower  works,  the  cranked  form  of  which 
is  considered  to  give  it  a better  purchase. 

The  tools  used  for  cutting  screws  in  soft  wood,  by  aid  of  the  traversing  or  screw  mandrel-lathe,  par- 
take of  the  same  general  characters  as  the  others,  and  are  represented  in  their  relative  positions ; Fig. 
3493  is  for  the  outside,  and  Fig.  3494  for  the  inside  screw. 

To  conclude  the  notice  of  tools  of  this  class,  the  parting-tool,  Fig.  3495,  has  an  angular  notch  or  groove 
on  its  upper  surface,  from  which  it  results  that  when  the  tool  is  sharpened  on  the  bevel  b,  the  upper  face 
presents  two  points,  which  separate  the  fibres  by  a double  incision.  This  method  wastes  only  as  much 
wood  as  equals  the  thickness  of  the  tool,  and  it  leaves  the  work  smooth  and  flat;  whereas,  when  the 
angle  of  the  chisel  is  used  for  the  same  purpose  several  cuts  are  required,  and  the  gap  must  present  a 
greater  angle  than  the  bevel  of  the  tool,  and  which  consumes  both  more  time  and  wood. 

The  various  turning-tools  for  soft  woods  which  have  been  described  are,  with  the  exception  of  the 
gouge  and  chisel,  nearly  restricted  to  the  makers  of  Tunbridge- ware,  toys,  and  common  turnery ; with 
them  they  are  exceedingly  effective,  but  to  others  somewhat  difficult.  The  amateur  turner  scarcely  uses 
more  than  the  common  gouge  and  chisel,  and  even  these  but  insufficiently,  as  much  may  be  done  with 
them.  It  has  been  shown,  for  instance,  that  moulding  tools  cannot  be  used  for  the  soft  woods,  but  IFiey 
are  efficiently  replaced  by  the  gouge  for  the  concave,  and  the  chisel  for  the  convex  mouldings. 


7G4 


TOOLS,  TURNING. 


A good  fair  practice  on  the  soft  woods  would  be  found  very  greatly  to  facilitate  the  general  manipur 
lation  of  tools,  as  all  those  for  the  soft  woods  demand  considerably  more  care  as  to  their  positions  and 
management  than  those  next  to  be  described. 


3490. 


3491. 


Turning-tools  for  hard  wood  and  ivory. — Angles  40°  to  80° — Figures  generally  half  size. — The 
gouge  is  the  preparatory  tool  for  the  hard  as  well  as  for  the  soft  woods,  but  it  is  then  ground  less 
acutely;  the  soft-wood  chisel  may  indeed  be  employed  upon  the  hardest  woods,  but  this  is  seldom  done, 
because  the  tools  with  single  bevels  held  in  a horizontal  position,  as  in  Fig.  3478,  are  much  more  man- 
ageable, and  on  account  of  the  different  natures  of  the  materials  they  are  thoroughly  suitable,  notwith- 
standing that  their  edges  are  nearly  as  thick  again  as  those  of  soft-wood  tools.  In  general,  also,  the  long 
handles  of  the  latter  are  replaced  by  shorter  ones,  as  in  Figs.  3496  and  3497,  measuring  with  the  tools 
from  8 to  12  inches;  but  these  give  in  general  an  abundant  purchase,  as  from  the  nearly  horizontal  pc 
sition  of  the  tool,  the  lathe-rest  or  support  can  be  placed  much  nearer  to  the  work. 


349G.  3497. 


The  hard-wood  tools  are  often  applied  to  a considerable  extent  of  the  work  at  one  time,  and  the  fin- 
ishing processes  are  much  facilitated  by  selecting  instruments  the  most  nearly  in  correspondence  with 
the  required  shapes.  Rectilinear  surfaces,  such  as  cylinders,  cones,  and  planes,  whether  external  or 
internal,  necessarily  require  tools  also  with  rectilinear  edges,  which  are  sloped  in  various  ways  as  re- 
gards their  shafts  ; they  are  made  both  large  and  small,  and  of  proportionate  degrees  of  strength  to 
suit  works  of  different  magnitudes.  The  following  are  some  of  the  most  useful  kinds. 


3498.  3499. 


3300. 


3585.  3580.  3587.  3583. 


3589. 


3590.  3591. 


The  right-side  tool,  Fig.  3498,  cuts  on  the  side  and  end,  the  dotted  lines  being  intended  to  indicate  the 
undercut  bevel  of  the  edge — so  named  because  it  cuts  from  the  right  hand  towards  the  left.  The  left-side 
tool,  Fig  3499,  is  just  the  reverse.  The  fiat-tool,  Fig.  3500.  cuts  on  both  sides,  and  on  the  end  likewise  ; 


TOOLS,  TURNING. 


7G5 


and  in  all  three  tools  the  angle  seen  in  plan  is  less  than  a right  angle,  to  allow  them  to  be  applied  in 
rectangular  corners.  The  point-tool , Fig.  3585,  is  also  very  convenient ; and  bevel-tools , Figs.  3586  and 
3587,  the  halves  of  the  former,  are  likewise  employed  ; Figs.  3588  show  the  general  thicknesses  of  these 
tools.  When  any  of  them  are  very  narrow  they  are  made  proportionally  deep  to  give  sufficient  strength, 
the  extreme  case  being  the  parting-tool,  Fig.  3589,  which  is  no  longer  required  to  be  fluted,  as  in  the 
corresponding  tool  for  soft  wood ; but  the  side-tools,  when  used  for  small  and  deep  holes,  necessarily 
require  to  be  small  in  both  respects,  as  in  Fig.  3590.  The  inside  parting-tool,  Fig.  3591,  is  used  fur 
the  removal  of  rings  of  ivory  from  the  interior  of  solid  works,  in  preference  to  turning  the  materials  into 
shavings ; it  is  also  useful  in  some  other  undercut  works. 

Some  of  the  curvilinear  tools  for  hard  wood  are  represented  in  the  annexed  group  of  figures;  the 
semicircular  or  round  tool,  Fig.  3592,  is  the  most  general,  as  concave  mouldings  cannot  be  made  without 
it,  and  it  is  frequently  divided,  as  in  the  quarter  round  tools,  Figs.  3593  and  3594 ; it  is  convenient  that 
these  should  be  exact  counterparts  of  the  mouldings,  but  they  may  also  be  used  for  works  larger  than 
themselves,  bj»  sweeping  the  tools  around  the  curves.  Convex  mouldings  are  frequently  made  by  rec- 
tilinear tools,  which  are  carried  round  ir  a similar  manner,  so  as  to  place  the  edge  as  a tangent  to  the 
curve,  but  the  bead,  Fig.  3595,  the  astragal,  Fig.  3696,  or  the  quarter  hollows,  Figs.  3597  and  3598, 
facilitate  the  processes,  and  complete  the  one  member  of  the  moulding  at  one  sweep,  and  enable  it  to 
be  repeated  any  number  of  times  with  exact  uniformity 


3592.  3593.  3594.  3595.  3590. 


V 

■ 

w 

w 

L . — 

Frequently  the  tools  are  made  to  include  several  members,  as  the  entire  base  or  capital  of  a column, 
as  in  big.  3599.  Similar  figured  tools  have  been  applied  to  turning  profiles  of  about  one  or  one  and  a 
half  inches  high,  by  employing  four  different  tools,  embracing  each  about  a quarter  of  the  profile,  and 
applied  at  four  radial  positions,  around  a ring  of  some  three  to  five  inches  diameter;  the  rings  are  cut 
up  into  radial  slices,  and  turned  flat  on  each  face  prior  to  being  glued  upon  tablets.  Profiles  have  been 
likewise  successfully  and  more  skilfully  turned,  by  the  ordinary  round,  point,  and  fiat  tools. 

Figs.  3600  to  3603  represent  some  of  the  various  kinds  of  inside  tools,  which  are  required  for  hol- 
lowing vases  and  undercut  works ; and  Fig.  3604  the  inside  screw  tool,  and  Fig.  3605  the  outside  screw 
tool  for  hard  wood,  ivory,  and  the  metals : these  tools  are  made  with  many  points,  and  are  bevelled 
like  the  rest  of  the  group. 

The  hollow  tools,  Figs.  3595  to  3598,  may  be  sharpened  with  a narrow  slip  of  oilstone  used  almost 
as  a file ; but  their  sweeps  are  more  accurately  sharpened  by  conical  metal  grinders,  supplied  with 
emery,  as  will  be  explained ; most  other  moulding  tools,  and  the  screw  tools,  are  only  sharpened  upon 
the  face.  The  ends  of  these  tools  may  be  whetted  at  a slope,  if  it  be  more  gradual  than  in  Fig.  3604, 
this  however,  increases  the  angle  of  the  edge;  but  by  nicking  in  the  tools,  as  in  Fig.  3607,  by  applying 
them  transversely  on  the  grindstone,  the  original  angle  is  maintained,  and  which  is  the  better  mode  for 
screw  tools  more  especially. 

Turning-tools  for  brass. — Angles  70°  to  90° — Figures  generally  the  same  as  the  tools  for  hard 
wood. — The  turning-tools  for  brass  are  in  general  simple,  and  nearly  restricted  to  round,  point,  flat, 
right  and  left  side  tools,  parting-tools,  and  screw-tools ; they  closely  resemble  the  hard-wood  tools,  ex- 
cept that  they  are  generally  ground  at  angles  of  about  60°  or  70°,  and  when  sharpened  it  is  at  an 
angle  of  80°  or  90° ; some  few  of  the  finishing  or  planishing  tools  are  ground  exactly  at  90°,  upon 
metal  laps  or  emery  wheels,  so  as  to  present  a cutting  edge  at  every  angle  and  on  both  sides  of  the 
tools. 


3G08.  3009.  3610. 


It  is  not  a little  curious  that  the  angles  which  are  respectively  suitable  to  brass  and  to  iron,  art 
definitively  shown  to  be  about  90  and  60  degrees.  For  turning  brass,  a worn-out  square  file  is  occasion- 
ally ground  on  all  sides  to  deprive  it  of  its  teeth : it  is  used  as  a side-tool,  and  is  slightly  tilted,  as  in 
Fig.  3608,  just  to  give  one  of  the  edges  of  the  prism  sufficient  penetration  ; but  applied  to  iron,  steel,  O' 


766 


TOOLS,  TURNING. 


copper,  it  only  scrapes  with  inconsiderable  effect.  A triangular  file,  Fig.  3609,  similarly  ground,  cuts 
iron  with  great  avidity  and  effect,  but  is  far  less  suited  to  brass ; it  is  too  penetrative,  and  is  disposed 
to  dig  into  the  work.  It  appears,  indeed,  that  each  different  substance  requires  its  own  particular  angle, 
from  some  circumstances  of  internal  arrangement  as  to  fibre  or  crystallization  not  easily  accounted  for. 

A stout  narrow  round  tool,  Fig.  3592,  in  a long  handle,  serves  as  the  gouge  or  roughing-out  tool  for 
brass-work ; others  prefer  the  point,  Fig.  3585,  with  its  end  slightly  rounded,  which  combines,  as  it  were, 
the  two  tools  with  increased  strength ; a small  but  strong  right  side  tool,  Fig.  3582,  is  also  used  in 
rough-turning;  the  graver.  Figs.  3611  and  3612,  although  occasionally  employed  for  brass,  is  more 
proper  for  iron,  described  hereafter. 

The  wide  finishing  tools  should  not  be  resorted  to  under  any  circumstances  until  the  work  is  roughed- 
out  nearly  to  the  shape,  and  reduced  to  perfect  concentricity  or  truth,  with  narrow  tools  which  only 
embrace  a very  small  extent  of  the  work. 

It  is  the  general  impression  that  in  taking  the  finishing  cuts  on  brass  it  is  impolitic,  either  to  employ 
wide  tools,  or  to  support  them  in  a rigid  solid  manner  upon  the  rest,  as  it  is  apt  to  make  the  work  full 
of  fine  lines  or  strife.  This  effect  is  perhaps  jointly  attributable  to  the  facility  of  vibration  which  exists 
in  brass  and  similar  alloys,  to  the  circumstance  of  their  being  frequently  used  in  thin  pieces  on  the 
score  of  economy,  and  to  their  being  rotated  more  rapidly  in  the  lathe  than  iron  and  steel,  to  expedite 
the  progress  of  the  work. 

When  a wide  flat  tool  is  laid  close  down  on  the  rest,  and  made  to  cut  with  equal  effect  throughout  its 
width,  lines  are  very  likely  to  appear  on  the  metal,  and  which  if  thin,  rings  like  a bell  from  the  vibra- 
tion into  which  it  is  put ; but  if  the  one  corner  of  the  tool  penetrate  the  work  to  the  extent  of  the  thick- 
ness of  the  shaving,  whilst  the  other  is  just  flush  with  the  surface,  or  out  of  work,  the  vibration  is  les- 
sened, and  that  whether  the  penetrating  angle  or  the  other  move  in  advance. 

The  brass-turner  frequently  supports  the  smoothing-tool  upon  the  one  edge  only,  and  keeps  the  other 
slightly  elevated  from  the  rest  by  the  twist  of  the  hand,  which  thus  appears  to  serve  as  a cushion  or 
spring  to  annul  the  vibrations:  Fig.  3610  shows  about  the  greatest  inclination  of  the  tool.  Some  work- 
men with  the  same  view  interpose  the  finger  between  the  tool  and  the  rest,  in  taking  very  light  finish- 
ing cuts.  The  general  practice,  however,  is  to  give  the  tool  a constant  rotative  shuffling  motion  upon 
the  supported  edge,  never  allowing  it  to  remain  strictly  quiet,  by  which  the  direction  of  the  edge  of  the 
tool  is  continually  changed,  so  as  not  to  meet  in  parallelism  any  former  strife  which  may  have  been 
formed,  as  that  would  tend  to  keep  up  the  exciting  cause,  namely,  the  vibration  of  the  metal.  The 
more  the  inclination  of  the  tool,  the  greater  is  the  disposition  to  turn  the  cylinder  into  small  hollows. 

Some  workmen  burnish  the  edges  of  the  finishing  tools  for  brass,  like  the  joiners’  scraper,  or  the 
firmer  chisel  used  in  soft-wood  turning.  On  account  of  the  greater  hardness  and  thickness  of  the  edge 
of  the  tool,  it  cannot  be  supposed  that  in  these  cases  any  very  sensible  amount  of  burr  or  wire  edge  is 
thrown  up.  The  act  appears  chiefly  to  impart  to  the  tool  the  smoothness  and  gloss  of  the  burnisher, 
and  to  cause  it,  in  its  turn,  to  burnish  rather  than  cut  the  work ; the  gas-fitters  call  it  a planishing  tool, 
but  such  tools  should  never  be  used  for  accurate  works  until  the  surface  is  perfectly  true  and  smooth. 

The  hard-wood  and  brass-turners  avoid  the  continual  necessity  for  twisting  the  lathe-rest  in  its  socket 
to  various  angular  positions,  as  they  mostly  retain  it  parallel  with  the  mandrel,  and  in  turning  hollow 
works  they  support  the  tool  upon  an  arm  rest, ; this  is  a straight  bar  of  iron,  which  resembles  a long- 
handled  tool,  but  it  has  a rectangular  stud  at  the  end,  to  prevent  the  cutting-tool  from  sliding  off. 

The  position  of  the  arm-rest  and  tool,  as  seen  in'  plan,  are  therefore  nearly  that  of  a right  angle ; the 
former  is  held  under  the  left  arm,  the  latter  in  the  right  hand  of  the  workman,  the  fore-fingers  of  each 
hand  being  stretched  out  to  meet  near  the  end  of  the  tool.  This  may  appear  a difficult  method,  but  it 
is  in  all  respects  exceedingly  commodious,  and  gives  considerable  freedom  and  choice  of  position  in 
managing  the  tool,  the  advantage  of  which  is  particularly  felt  in  guiding  the  first  entry  of  the  drill,  or 
the  path  of  the  screw-tool ; and  in  brass-work  it  likewise  renders  the  additional  service  of  associating 
the  tool  with  the  elastic  frame  of  the  man.  But  when  particular  firmness  and  accuracy  are  required 
the  tool  should  be  supported  upon  the  solid  rest  as  usual. 

Turning-tools  for  iron,  steel,  etc. — Angles  60°  to  90° — Figures  generally  one-sixth  the  full  size. — 
The  triangular  tool  is  one  of  the  most  effective  in  turning  these  metals,  as  was  adverted  to  above ; 
the  triangular  tool  is  also  used  by  the  engravers  and  others  for  scraping  the  surfaces  of  the  metals, 
and  it  is  then  applied  nearly  perpendicular,  or  as  a penknife  in  erasing  ; but  when  the  triangular  tool  is 
placed  nearly  as  a tangent  against  the  inner  or  outer  edge  of  a ring  or  cylinder,  as  in  Fig.  3609,  it 
seems  almost  to  devour  the  metal,  and  instead  of  scratching,  it  brings  off  coarse  long  shavings.  In 
turning  the  flat  sides  of  the  ring,  the  face  of  the  tool  is  placed  almost  in  agreement  with  the  plane  to 
be  turned. 

The  graver,  which  is  also  an  exceedingly  general  tool,  is  a square  bar  of  steel  ground  off  at  the  end, 
diagonally  and  obliquely,  generally  at  an  angle  of  from  30  to  50  degrees.  The  parts  principally  used 
are  the  two  last  portions  of  the  edge  close  to  the  point,  and  to  strengthen  the  end  of  the  tool  a minute 
facet  is  sometimes  ground  off,  nearly  at  right  angles  to  the  broad  chamfer,  or  principal  face. 

The  proper  position  of  the  tool  in  turning  a cylinder,  will  be  most  readily  pointed  out  by  laying  the 
chamfer  of  the  tool  in  exact  contact  with  the  flat  end  of  such  cylinder ; it  will  be  then  found  that  one 
of  the  lateral  angles  of  the  tool  will  touch  the  rest,  and  the  obliquity  in  the  shaft  of  the  tool  would  be 
the  angle,  at  which  the  graver  is  ground,  instead  of  which  it  is  held  square  and  slightly  elevated  above 
the  horizontal  position,  as  shown  in  Fig.  3611.  The  graver  is  rotated  upon  the  supporting  angle,  which 
sticks  into  the  rest,  much  the  same  as  the  edge  of  the  triangular  tool ; in  fact,  the  two  tools,  although 
different  in  form,  remove  the  shaving  in  a very  similar  manner. 

In  using  the  graver  and  other  tools  for  the  metals,  it  is  the  aim  to  avoid  exposing  the  eDd  of  the  tool 
to  the  rough  gritty  surface  of  the  material.  This  is  done  by  cleaning  the  surface,  especially  the  extreme 
edge,  with  an  old  file,  and  beginning  at  that  edge,  the  work  is  at  one  sweep  reduced  nearly  to  its  re- 
quired diameter  by  a wide  thin  cut,  which  may  be  compared  with  a chamfer,  or  a conical  fillet,  con 


TOOLS,  TURNING. 


767 


necting  the  rough  external  surface  with  the  smooth  reduced  cylinder.  Therefore  after  the  first  entry, 
the  point  of  the  tool  is  buried  in  the  clean  metal  below  the  crust,  and  works  laterally,  which  is  indeed 
the  general  path  of  pointed  tools  for  metal. 

When  the  graver  is  used  in  the  turn-bench  with  intermittent  motion,  as  for  the  pivots  of  watches,  the 
axes  for  sextants,  and  other  delicate  works,  it  is  applied  overhand,  or  inverted,  as  in  Fig.  3612  ; but  it 
is  then  necessary  to  withdraw  the  tool  during  each  back  stroke  of  the  bow,  to  avoid  the  destruction  of 
the  acute  point,  and  which  alone  is  used.  The  graver,  when  thus  applied  in  lathes  with  continuous 
motion,  is  only  moved  on  the  rest  as  on  a fulcrum,  and  in  the  plane  in  which  it  lies,  rather  as  a test  ol 
work  done,  than  as  an  active  instrument. 


The  edge  of  the  graver  is  afterwards  used  for  smoothing  the  stronger  kinds  of  work  ; it  is  then  neces- 
sary to  incline  the  tool  horizontally,  to  near  the  angle  at  which  it  is  ground,  in  order  to  bring  the  sloping 
edge  parallel  with  the  surface.  But  the  smoothing  is  better  done  by  a thick  narrow  flat  tool,  ground 
at  about  sixty  degrees,  the  handle  of  which  is  raised  slightly  above  the  horizontal,  as  in  Fig.  3613,  in 
order  that  its  edge  may  approach  the  tangential  position ; here  also  the  tool  is  rotated  on  one  edge, 
after  the  manner  of  the  brass  tools  or  the  graver. 

For  many  slight  purposes  requiring  rather  delicacy  than  strength,  as  in  finishing  the  rounded  edge 
of  a washer,  the  flat  tool  is  inverted  or  placed  bevel  upwards,  as  in  Fig.  3614 ; the  lower  side,  then  be- 
comes the  tangent,  and  the  edge  the  axis  of  rotation  of  the  tool,  the  same  as  in  turning  convex  mould- 
ings with  the  soft-wood  chisel.  Indeed,  many  analogies  may  be  traced  between  the  tools  respectively 
used  for  soft  woods  and  iron,  except  that  the  latter  are  ground  at  about  twice  the  angle  to  meet  the 
increased  resistance  of  the  hard  metal,  and  the  tools  are  mostly  sustained  by  the  direct  support  of  the 
rest,  instead  of  resting  in  great  measure  against  the  hands  of  the  individual. 


3016. 


For  instance,  the  lieel-tool,  which  is  used  for  rough-turning  the  metals,  is  represented  of  the  full  size 
in  the  side  view,  Fig.  3615,  and  the  front  view,  Fig.  3616,  and  also  on  a, smaller  scale  in  Figs.  3617  and 
3618.  The  dotted  lines  a,  Fig.  3617,  denote  the  relative  position  of  the  fluted  gouge,  and  although  the 
heel  or  hook-tool  occupies  nearly  the  same  spot,  its  edge  is  of  double  the  thickness,  aud  the  entire  re- 
sistance of  the  cut  is  sustained  by  the  heel  of  the  tool,  which  is  poised  upon  the  flat  horizontal  surface 
of  the  rest ; the  shaft  of  the  tool  is  bent  nearly  at  right  angles,  that  it  may  be  held  either  above  or  be- 
low the  shoulder  of  the  workman,  as  preferred.  Some  variation  is  made  in  the  form  and  size  of  the 
heel-tools,  and  they  are  occasionally  pointed  instead  of  round  upon  the  cutting-edge. 

The  heel-tool  is  slightly  rotated  upon  its  heel  in  its  course  along  the  work,  so  that,  as  seen  at  h,  it? 


7G8 


TOOLS,  TURNING. 


edge  travels  in  short  arcs,  and  when  its  position  becomes  too  inclined,  a fresh  footing  is  taken  ; on  this 
account  the  straight  handle,  employed  in  ordinary  tools,  is  exchanged  for  the  transverse  handle  repre- 
sented. In  the  best  form  of  heel-tools  the  square  shaft  lies  in  a groove  in  the  long  handle,  and  is  fixed 
by  an  eye-bolt  and  nut,  passing  through  the  transverse  handle,  as  seen  in  the  section,  Fig.  3618.  Not- 
withstanding the  great  difference  the  materials  upon  which  tire  gouge  and  heel-tool  are  employed,  their 
management  is  equally  easy,  as  in  the  latter  the  rest  sustains  the  great  pressure,  leaving  the  guidance 
alone  to  the  individual. 

Fig.  3619  represents  another  kind  of  liook-tool  for  iron,  which  is  curiously,  like  the  tools  Figs.  3483  to 
3484,  p.  707,  used  for  soft  wood,  the  common  differences  being  here  also  observable,  namely,  the  in- 
creased strength  of  edge,  and  that  the  one  edge  is  placed  upon  the  rest  to  secure  a firm  footing  or  hold. 

Nail-head  tools  are  made  much  on  the  same  principle : one  of  these,  Fig.  3620,  is  like  a cylinder,  ter- 
minating in  a chamfered  overhanging  disk,  to  be  rolled  along  so  as  to  follow  the  course  of  the  work,  but 
it  is  rather  a theoretical  than  practical  instrument.  When,  however,  the  tool  is  made  of  a square  or 
rectangular  bar,  and  with  two  edges,  as  at  Fig.  3621,  it  is  excellent,  and  its  flat  termination  greatly 
assists  in  imparting  the  rectilinear  form  to  the  work.  Occasionally  the  bar  is  simply  bent  up  at  the 
end  to  present  only  one  edge,  as  in  Fig.  3622  ; it  is  then  necessary  the  curved  part  should  be  jagged  as 
a file  to  cause  it  to  dig  into  the  rest  like  the  others  of  its  class,  and  which  present  some  analogy  to  the 
soft-wood  tools,  Figs.  3488  and  3489,  p.  707. 

The  cranked,  or  hanging  tools,  Fig.  3623,  are  made  to  embrace  the  rest,  by  which  they  are  prevented 
from  sliding  away,  without  the  necessity  for  the  points  and  edges  of  the  heel-tools ; the  escape  of  the 
cranked-tool  sideways  is  prevented  by  the  pin  inserted  in  one  of  the  several  holes  of  the  rest.  The 
direct  penetration  is  caused  by  the  depression  of  the  hand ; the  sideway  motion  by  rotating  the  tool  by 
its  transverse  handle,  which  is  frequently  a hand-vice  temporarily  screwed  upon  the  shaft.  To  save 
the  trouble  of  continually  shifting  the  lathe-rest,  an  iron  wedge  (not  represented)  is  generally  intro- 
duced at  a,  between  the  rest  and  the  back  of  the  tool ; when  the  wedge  is  advanced  at  intervals  it  sets 
the  tool  deeper  into  the  work,  when  it  is  withdrawn  it  allows  more  room  for  the  removal  of  the  tool. 


Fig.  3624  represents  a tool  of  nearly  similar  kind  ; the  stock  is  of  iron,  and  it  carries  a piece  of  steel, 
about  three  or  four  inches  long,  and  one  inch  square,  which  is  forged  hollow  on  the  faces  by  means  of 
the  fuller,  to  leave  less  to  be  ground  away  on  the  stone.  The  rectilinear  edges  of  this  tool  are  used 
for  smoothing  iron  rollers,  iron  ordnance,  and  other  works  turned  by  hand,  and  to  preserve  the  edge  of 
the  tool,  thin  spills  of  hard  wood  are  sometimes  placed  between  the  cutter  and  the  bar.  Under  favora- 
ble arrangements  these  tools  also  are  managed  with  great  facility ; indeed,  it  occasionally  happens  that 
the  weight  of  the  handle  just  supplies  the  necessary  pressure  to  advance  the  tool,  so  that  they  will  rest 
in  proper  action  without  being  touched  by  the  hand ; a tolerable  proof  of  the  trifling  muscular  effort 
occasionally  required,  when  the  tools  are  judiciously  moulded  and  well  applied. 

These  hand-tools,  and  various  others  of  the  same  kinds,  although  formerly  much  used  by  the  mill 
wrights,  are  now  in  a great  measure  replaced  by  the  fixed  tools  applied  in  the  sliding-rest. 

Fixed  or  machine  tools  for  turning  and  planing. — Angles  as  in  the  hand-tools — Figures  generally 
one-fourth  to  one-eighth  the  full  size. — The  performance  of  fixed  tools  is,  in  general,  much  more  effective 
than  that  of  hand-tools ; as  the  rigid  guides  and  slides  now  employed  do  not  suffer  the  muscular  fatigue 
of  the  man,  nor  do  they  experience  those  fluctuations  of  position  to  which  his  hand  is  liable.  There- 
fore, as  the  tool  pursues  one  constant  undeviating  course,  the  corresponding  results  are  obtained  both 
more  economically  and  more  accurately  by  the  intervention  of  the  guide-principle,  or  the  slide-rest,  from 
which  we  derive  the  side-lathe,  and  thence  the  planing  machine,  and  many  other  most  invaluable  tools. 

The  cutting  edges  of  machine-tools  mostly  follow  the  same  circumstances  as  those  of  hand-tools,  but 
additional  care  is  required  in  forming  them  upon  principle ; because  the  shafts  of  the  fixed  tools  are 
generally  placed,  with  little  power  of  deviation,  either  at  right  angles  to,  or  parallel  with,  the  surfaces 
to  be  wrought ; the  tools  are  then  held  in  the  iron  grasp  of  screws  and  clamps,  in  mortises,  staples,  and 
grooves.  The  tools  do  not,  therefore,  admit  of  the  same  accommodation  of  position,  to  compensate  for 
erroneous  construction,  or  subsequent  deterioration  from  wear,  as  when  they  are  held  in  the  hand  of  the 
workman,  and  directed  by  his  judgment. 

It  must  also  be  additionally  borne  in  mind  that,  however  ponderous,  elaborate,  or  costly  the  machine 
may  be,  its  effectiveness  entirely  depends  upon  the  proper  adaptation  and  endurance  of  the  cutting-tool, 
through  the  agency  of  which  it  produces  its  results. 

The  usual  position  of  the  fixed  turning-tools  is  the  horizontal  line,  as  at  a,  Fig.  3625  ; and  unless  the 
tools  always  lie  on  the  radius,  (or  any  other  predetermined  line.)  various  interferences  occur.  For  in- 
stance, the  tool  proceeding  in  either  of  the  lines  b or  c,  could  not  reach  the  centre  of  the  work,  and  a 
portion  w’ould  then  escape  being  wrought;  the  curvature  of  the  circle  at  b would  sacrifice  the  proper 
angle,  and  expose  the  tool  to  fracture  from  the  obliquity  of  the  strain ; and  at  c,  the  edge  would  be 
altogether  out  of  contact,  and  the  tool  could  only  rub  anil  not  cut.  These  evils  increase  with  the  dim 
inution  of  the  circle ; and  although  the  diagram  is  greatly  exaggerated  for  illustration,  the  want  of 
centrality  is  in  truth  an  evil  of  such  magnitude  that  various  contrivances  are  resorted  to,  by  which  either 
the  entire  slide-rest,  or  the  cutter  alone,  may  be  exactly  adjusted  for  height  of  centre. 


TOOLS,  TURNING. 


769 


The  planing  tools  for  metals  are  in  general  fixed  vertically,  and  the  path  of  the  work  being,  in  the 
majority  of  planing-machines,  rectilinear  and  horizontal,  the  tool  may  be  placed  at  d,  e,  or  /,  indiffer- 
ently, there  being  no  interference  from  curvature  as  in  turning. 

In  those  modifications  of  the  planing-machine  in  which,  as  in  Brunei’s  mortising-engine,  the  cutter 
travels  perpendicularly,  and  is  also  fixed  perpendicularly,  as  in  the  key-groove  or  slotting-engines,  and 
the  paring-engines,  the  general  form  of  the  tool/,  or  that  of  a strong  paring  chisel,  is  retained,  but  the 
blade  is  slightly  inclined  in  its  length  as  at  j,  Fig.  3626,  to  avoid  touching  the  surface  to  be  wrought 
expect  with  its  cutting  edge,  and  the  length  of  the  tool  supplies  a little  elasticity  to  relieve  the  friction 
of  the  back  stroke. 


Although  all  the  various  forms  of  hand-turning  tools  are  more  or  less  employed  as  fixed  tools,  still 
the  greater  part  of  the  work  is  done  with  the  point-tool,  (such  as  g,  in  the  plan  Fig.  3626,)  the  angle  of 
which  should  be  slightly  rounded ; but  for  working  into  an  angle,  the  point  of  the  tool  is  thrown  off  as 
at  h,  so  that  its  shaft  may  avoid  either  side  of  the  angle,  and  it  is  then  called  a side-tool.  For  internal 
works,  and  in  small  apertures  especially,  the  abrupt  curvature  requires  particular  attention  to  the  cen- 
tral position  of  the  tool  i,  and  a frequent  sacrifice  of  the  most  proper  form  of  the  chamfer  or  edge.  We 
will  now  describe  a few  of  the  slide-rest  tools  in  the  previous  order,  namely,  those  for  soft  wood,  for 
hard  wood,  for  brass,  and  for  iron. 

The  fixed  tools  for  soft  wood  require  the  same  acute  edges  and  nearly  tangential  positions  as  those 
used  by  hand ; and  if  these  conditions  exist,  it  is  quite  immaterial  whether  the  tool  touch  the  work 
above  or  below  the  centre ; but  the  central  line,  or  a,  Fig.  3625,  is  the  most  usual.  The  soft-wood 
gouge,  or  hook-tool,  is  successfully  imitated  by  making  an  oblique  hole  in  the  end  of  a bar  of  steel,  as 
seen  in  two  views  in  Fig.  362/  but  it  is  not  very  lasting ; or  a bar  of  steel  may  be  bent  to  the  form  ot 
Fig.  8628,  and  sharpened  internally,  either  rounded  to  serve  as  a gouge,  or  straight  and  inclined  as  a 
chisel,  but  neither  of  these  tools  admits  in  itself  of  adjustment  for  centre. 

The  difficulty  of  centre  is  combated  by  the  use  of  a tool  exactly  like  a common  gouge  or  chisel,  but 
only  an  inch  or  two  long,  and  with  a cylindrical  stem  also  an  inch  or  two  long,  by  which  it  may  be  re- 
tained at  any  height,  in  the  end  of  a bar  of  iron,  having  a nearly  perpendicular  hole  and  an  appropriate 
side-screw  for  fixing  the  tool ; this  construction  is  abundantly  strong  for  wood. 

The  fixed  tools  for  hard  loood  and  ivory  follow  the  several  forms  of  the  hand-tools,  Figs.  3498  to  3605, 
except  in  having  parallel  stems ; they  are  always  placed  horizontally,  and  are  treated  in  all  respects 
just  as  before.  Care  should  be  taken,  however,  that  the  end  of  the  tool  is  its  widest  part ; in’  order  that, 
if  it  be  sent  in  below  the  surface  of  the  work,  as  in  cutting  a groove,  it  may  clear  well  and  not  rub 
against  the  sides. 

In  sharpening  the  tools  intended  for  hard  wood  and  ivory,  the  oil-stone  should  be  applied  principally 
at  the  end,  or  on  the  chamfer  of  the  tool,  as  this  will  not  reduce  the  height  of  centre,  which  it.  is  always 
important  to  retain.  If,  however,  the  tools  should  eventually  become  chamfered  off,  after  the  manner 
of  Fig,  3606,  they  may  be  annealed,  and  thrown  up  to  place  the  chamfered  part  in  the  line  of  the  gene- 
ral face ; they  are  then  rehardened,  and  ground  up  as  at  first.  But  as  most  of  the  slide-rests  for  wood- 
turning are  fitted  into  pedestals  by  means  of  a cylindrical  stem  with  a vertical  screw  adjustment,  the 
tools  may  be  at  all  times  accurately  centered  when  particular  care  is  required ; and  this  provision  is  of 
still  greater  importance,  with  the  several  revolving  cutters  applied  to  the  slide-rest,  which  will  be  here- 
after adverted  to. 

The  fixed  tools  for  brass  and  for  iron,  whether  used  in  the  lathe  or  the  planing-machine,  will  be  con 
Von.  II.— 49 


770 


TOOLS,  TURNING. 


sidered  in  one  group ; the  principal  difference  is,  that  the  tools  for  brass  present  an  angle  of  nearly  90 
degrees,  the  tools  for  iron  an  angle  of  60,  to  the  superficies  to  be  wrought.  Indeed,  the  angles  or  edges 
of  the  cube  may  be  considered  as  the  generic  forms  of  the  tools  for  brass,  and  the  angles  or  edges  of 
the  tetrahedron,  as  the  generic  forms  of  the  tools  for  iron ; that  is,  supposing  the  edges  or  planes  of 
these  solids  to  be  laid  almost  in  contact  with  the  line  of  motion  or  of  the  cut,  in  order  that  they  may 
fulfil  the  constant  conditions  of  the  paring  tools. 

The  fixed  tools  for  brass  and  similar  alloys  resemble,  as  in  hand- turning,  the  more  simple  of  the  hard 
wood  tools,  except  that  they  are  sharpened  a trifle  thicker  on  the  edge  ; they  are,  however,  nearly  re' 
stricted  to  the  point-tool,  the  narrow  round  tool,  and  to  the  side-tool,  which  is  represented  at  j,  Fig.  3626 
It  is  ground  so  that  the  two  cutting  edges  meet  at  an  angle  not  exceeding  about  80  degrees,  that  in 
proceeding  into  rectangular  corners  it  may  clear  each  face  by  about  five  degrees,  and  it  will  then  cut 
in  either  direction,  so  as  to  proceed  into  the  angle  upon  the  cylindrical  line,  and  to  leave  it  upon  the 
plane  surface,  or  it  may  be  applied  just  in  the  reverse  manner  without  intermission. 

When  the  tool  is  used  for  rough  work  the  corner  is  slightly  rounded,  but  in  finishing  it  is  usually 
quite  sharp ; and  as  it  differs  only  some  ten  degrees  from  the  solid  angle  of  a cube,  it  is  abundantly 
strong.  If  the  tools  acted  upon  a considerable  extent  or  width  of  the  brass,  they  would  be  liable  to  be 
set  in  vibration ; but  as  the  paths  of  the  cutters  are  determined  by  the  guide  principle  employed,  the 
point  fulfils  all  that  can  be  desired. 

The  fixed  tools  for  iron  present  more  difficulties  than  the  generality  of  the  foregoing  kinds;  first,  the 
edges  of  the  tools  are  thinner  and  more  interfered  with  in  the  act  of  grinding,  as  the  vertical  height  of 
the  cutting  edge  is  reduced  when  either  face  of  the  wedge  is  ground ; and  secondly,  they  are  exposed 
to  far  more  severe  strains  from  the  greater  hardness  of  the  material,  and  the  less  sparing  manner  in 
which  it  is  reduced  or  wrought,  owing  to  its  smaller  price  and  other  circumstances ; and  therefore,  the 
most  proper  and  economic  forms  of  the  tools  for  iron  are  highly  deserving  of  attention. 

The  fracture  of  a tool  when  it  is  overloaded  commonly  points  out  the  line  of  greatest  resistance  or 
strain.  Tire  tool,  Fig.  3629,  although  apparently  keen,  is  very  weak,  and  it  is  besides  disposed  to  pur- 
sue the  line  at  which  its  wedge-formed  extremity  meets  the  work,  or  to  penetrate  at  an  angle  of  some 
30  degrees.  Fig.  3629  would  probably  break  through  a line  drawn  nearly  parallel  with  the  face  a b of 
the  work  under  formation  ; that  portion  should  therefore  be  made  very  nearly  parallel  with  a b,  the  line 
of  resistance,  in  order  to  impart  to  the  tool  the  strength  of  the  entire  section  of  the  steel ; so  that  should 
it  now  break  it  will  have  a much  longer  line  of  fracture.  The  tool  thus  altered  is  very  proper  for  brass, 
an  alloy  upon  which  acute  tools  cannot  be  favorably  employed. 

But  with  the  obtuse  edge  of  Fig.  3630  other  metals  will  be  only  removed  with  considerable  labor,  as 
it  must  be  remembered  the  tool  is  a wedge,  and  must  insinuate  itself  as  such  amongst  the  fibres  of  the 
material.  To  give  the  strengthened  tool  the  proper 
degree  of  penetration,  the  upper  face  is  next  sloped, 
as  in  Fig.  3631,  to  that  angle  in  which  the  minimum 
of  friction  and  the  maximum  of  durability  of  the  edge 
most  nearly  meet ; and  which,  for  iron,  is  shown  to 
be  about  60  degrees,  as  in  the  triangular  tool,  Fig. 

3609.  The  three  planes  of  pointed  tools  for  iron, 
meeting  at  60  degrees,  constitute  the  angle  of  the  te- 
trahedron, or  the  solid  wdth  four  equilateral  planes, 
like  a triangular  pyramid,  the  base  and  sides  of  which  are.  exactly  alike. 

But  the  form  of  Fig.  3631  would  be  soon  lost  in  the  act  of  grinding;  therefore,  to  conclude,  the  tool 
is  made  in  the  bent  form  of  Fig.  3632,  in  which  the  angles  of  Fig.  3631  are  retained,  and  the  tool  may 
be  many  times  ground  without  departing  from  its  most  proper  form.  This  is  in  effect  extending  the 
angle  of  the  tetrahedron  into  the  triangular  prism  ground  off  obliquely,  or  rathfer,  as  seen  in  the  front 
view,  Fig.  3633,  into  a prism  of  five  sides,  the  front  angle  of  which  varies  from  60  degrees  to  120  de- 
grees, and  is  slightly  rounded,  the  latter  being  most  suitable  for  rough  work ; sometimes  the  front  of  the 
prism  is  half-round,  at  other  times  quite  flat:  these  forms  are  shown  in  Fig.  3639. 

The  extremities  of  Figs.  3631  and  3632  approach  very  closely  to  the  form  of  the  graver  used  for  en- 
graving on  steel  and  copper-plates,  than  which  no  instrument  works  more  perfectly.  The  slender  graver, 
whether  square  or  lozenge,  is  slightly  bent,  and  has  a flattened  handle,  so  that  the  ridge  behind  the 
point  may  lie  so  nearly  parallel  with,  and  so  completely  buried  in,  the  line  or  groove  under  formation, 
as  to  be  prevented  or  checked  by  the  surface  contact  from  digging  into  the  work.  This  is  another  con- 
firmation of  the  fact  that  the  fine  of  penetration  is  that  of  the  lower  face  of  the  cutter  or  wedge,  or  that 
touching  the  work. 

In  adopting  the  crank-formed  tools,  Fig.  3632,  the  principle  must  not  be  carried  into  excess,  as  it 
must  be  remembered  we  can  never  expunge  elasticity  from  our  materials,  whether  viewed  in  relation 
to  the  machine,  the  tool,  or  the  work. 

The  tool  should  be  always  grasped  as  near  the  end  as  practicable,  therefore  the  hook  or  crank  should 
occupy  but  little  length  ; as  the  distance  from  the  supposed  line  of  the  fixing-screw  c to  the  edge  of  the 
tool  being  doubled,  the  flexure  of  the  instrument  will  be  four-fold ; when  trebled,  nine-fold  ; in  fact,  as 
the  square.  And  also  as  the  flexure  may  be  supposed  to  occur  from  near  the  centre  of  the  bar,  (that 
.s,  neglecting  the  crook,)  the  point  of  the  tool  should  not  extend  beyond  the  central  line  o ; otherwise 
when  the  tool  bends,  its  point  would  dig  still  deeper  into  the  work  from  its  rotation  on  the  intersection 
of  c and  o;  the  point  situated  behind  the  central  line  would  spring  away  from,  or  out  of,  instead  of  into 
the  work.  To  extend  the  wear  of  the  cranked  tools  they  are  commonly  forged  so  that  the  point  is  nearly 
level  witli  the  upper  surface  of  the  shaft,  as  in  Fig.  3638 ; they  then  admit  of  being  many  times  ground 
before  they  reach  the  central  line,  and  they  are  ultimately  ground  (always  at  the  end  of  the  prism  and 
obliquely)  until  the  hook  is  entirely  lost.  This  avoids  such  frequent  recurrence  to  the  forge  lire,  but  i* 
is  a departure  from  the  right  principle  to  allow  the  point  to  extend  beyond  the  centre  line  o. 


3629.  3630.  3631.  3632.  3633. 

- | 


TOOLS,  TURNING. 


77] 


The  works  of  the  lathe  and  planing-machine  frequently  present  angles  or  rebates,  chamfers,  grooves' 
and  under-cut  lines,  which  require  that  the  tool  should  be  bent  about  in  various  ways,  in  order  that 
their  edges  may  retain  as  nearly  as  possible  the  same  relations  to  all  these  surfaces,  as  the  ordinary 
surfacing  tools,  Figs.  8631  and  3632,  have  to  the  plane  a b.  For  instance,  the  shaft  of  the  tool  Fig 
3631,  when  bent  at  about  the  angle  of  46  degrees,  becomes  a side  cutting  and  facing  tool,  as  shown  in 
plan  in  Fig.  3634,  in  elevation  in  Fig.  3635,  and  in  perspective  in  Fig.  3636 ; and  in  like  manner  the 
cranked  tool,  Fig.  3632,  when  also  bent  as  in  Fig.  3634,  becomes  Fig.  3637,  and  is  also  adapted  to  work- 
ing into  angular  corners  upon  either  face. 

/ 3634.  3636. 


Mr.  Nasmyth’s  tool-gage,  shown  in  elevation  in  Fig.  3638,  and  in  plan  in  Fig.  3639,  entirely  removes 
the  uncertainty  of  the  angles  given  to  these  irregular  bent  tools ; for  instance,  when  the  shaft  of  the  tool 
is  laid  upon  the  flat  surface  and  applied  to  the  iron  cone  c,  whose  side  measures  about  3°  with  the  per- 
pendicular, it  serves  with  equal  truth  for  s,  the  tool  for  surfaces;  p and/,  the  side-cutting  tools,  used 
also  for  perpendicular  cuts  and  fillets ; and  u for  under-cut  works. 


3638. 


3639. 


"1 


In  applying  tools  to  lathe  works  of  small  diameters,  it  is  necessary  to  be  very  exact,  and  not  to  place 
them  above  the  centre,  or  they  immediately  rub ; and  as  this  soon  occurs  with  tools  having  so  small  an 
angle,  it  appears  desirable  to  make  the  cone-gage  for  small  lathe  works  of  about  twice  the  given  angle, 
and  to  mark  upon  the  cone  a circle  exactly  indicative  of  the  height  of  centre ; the  tool  can  be  then 
packed  up  to  the  centre  line,  with  one  or  two  .dips  of  sheet-iron,  to  be  afterwards  placed  beneath  the 
tool  when  it  is  fixed  in  the  lathe-rest.  In  small  hollow  works,  the  most  lasting  or  the  crank-formed 
tools  are  entirely  inapplicable ; indeed,  so  much  attention  is  required  to  prevent  the  tool  from  rubbing 
against  the  interior  surfaces,  that  the  ordinary  angles  cannot  be  employed,  and  the  cone-gage  ceases  to 
be  useful,  but  in  every  other  case  it  should  be  constantly  resorted  to  ; the  additional  thickness  a is  re- 
quired to  make  it  applicable  to  the  crank-formed  tools. 

3640.  3641. 

I 


3643. 


3642. 


Fig.  3640  represents  a cutter  introduced  in  the  block  machinery  at  Portsmouth,  England,  to  lessen 
the  difficulty  of  making  and  restoring  the  tools  for  turning  the  wrought-iron  pins  for  the  sheaves  ; it 
consists  of  a cylindrical  wire  which,  from  being  ground  off  obliquely,  presents  an  elliptical  edge ; the 
tool  is  fixed  in  a stock  of  iron,  terminating  in  an  oblique  hole,  with  a binding-screw.  The  tool,  when 
used  for  iron,  in  the  “pin  turning  lathes,”  was  made  solid;  when  used  for -turning  the  surfaces  of  the 
wooden  shells,  in  the  “shaping  engine,”  it  was  pierced  with  a central  hole  ; the  latter  could  only  facili 


TOOLS,  TURNING. 


1 1 . 


tate  the  process  of  sharpening  without  altering  the  character  of  the  edge,  which  continued  under  tht 
same  circumstances  as  when  solid. 

About  sixteen  years  back  the  author  made  for  his  own  use  a tool  such  as  Fig.  3640,  but  found  that 
with  rough  usage  the  cutter  was  shivered  away,  on  account  of  its  breadth,  and  he  was  soon  led  to  sub- 
stitute for  the  solid  cylinder  a triangular  cutter,  the  final  edge  of  which  was  slightly  rounded,  and  placed 
more  nearly  perpendicular,  in  a split  socket  with  a side  screw,  as  in  Fig.  3641.  The  strength  of  the 
edge  was  greatly  increased,  and  it  became,  in  fact,  an  exact  copy  of  the  most  favorable  kind  of  tool  for 
the  lathe  or  planing-machine,  retaining  the  advantage  that  the  original  form  could  be  always  kept, 
with  the  smallest  expenditure  of  time,  and  without  continually  reforging  the  blade,  to  the  manifest  de- 
terioration of  the  steel  from  passing  so  frequently  through  the  fire  ; it  being  only  requisite  to  grind  its 
extremity  like  a common  graver,  and  to  place  it  so  much  higher  in  the  stock  as  to  keep  the  edge  at  all 
times  true  to  the  centre. 

A right  and  a left  hand  side-tool  for  angles,  the  former  seen  in  Figs.  3642  and  3643,  were  also  made; 
the  blade  and  set-screw  were  placed  at  about  45°,  and  at  a sufficient  vertical  angle  to  clear  both  the 
inside  of  a cylinder  of  three  inches  diameter  and  also  to  face  the  bottom  or  surface.  These  side-tools 
answered  very  well  for  cast-iron  ; but  Fig.  3641,  the  ordinary  surfacing  tool,  is  excellent  for  all  purposes, 
and  has  been  employed  in  many  extensive  establishments. 

The  prismatic  cutters  admit  of  the  usual  variations  of  shape  : sometimes  two  binding  screws  are  used, 
and  occasionally  a tail  screw,  to  receive  the  direct  strain  of  the  cut.  When  the  blades  are  only  used 
for  cutting  in  the  one  direction,  say  from  right  to  left,  they  may,  with  advantage,  be  ground  with  a 
double  inclination ; for  as  all  these  pointed  tools  work  laterally,  the  true  inclination  of  some  60°  to  the 
narrow  facet  or  fillet  operated  upon  is  then  more  strictly  attained. 

Considerable  economy  results  from  this  and  several  other  applications,  in  which  the  cutter  and  its 
shaft  are  distinct  parts.  The  small  blades  of  steel  admit  of  being  formed  with  considerable  ease  and 
accuracy,  and  of  being  hardened  in  the  most  perfect  manner.  And  when  the  cutters  are  fixed  in  strong 
bars  or  shafts  of  iron,  they  receive  any  required  degree  of  strength,  and  the  one  shaft  or  carriage  will 
serve  for  any  successive  number  of  blades. 

'The  blades  are  sometimes  made  flat,  or  convex  in  the  front,  and  ground  much  thinner,  to  servo  for 
soft  wood ; the  tools  for  hard  wood  and  ivory,  being  more  easily  ground,  do  not  call  for  this  application 
of  detached  blades. 

In  turning  heavy  works  to  their  respective  forms,  a slow  motion  and  strong  pointed  tools  are  em- 
ployed ; but  in  finishing  these  works  with  a quicker  rate  of  motion,  there  is  risk  of  putting  the  lathe  in 
a slight  tremor,  more  particularly  from  the  small  periodic  shocks  of  the  toothed  wheels,  which  in  light 
finishing  cuts  are  no  longer  kept  in  close  bearing  as  in  stronger  cuts. 

Under  these  circumstances,  were  the  tools  rigid  and  penetrative,  each  vibration  would  produce  a line 
or  scratch  upon  the  surface,  but  the  finishing  or  hanging  tools,  Figs.  8644  and  3645,  called  also  spring- 
ing tools,  which  are  made  of  various  curves  and  degrees  of  strength,  yield  to  these  small  accidental  mo- 
tions. The  first  resembles  in  its  angles  the  rest  of  the  tools  used  for  brass,  the  second  those  for  iron  ; 
their  edges  are  rectdinear,  and  sometimes  an  inch  wide.  The  width  and  elasticity  of  these  finishing  tools 
prevent  their  acting  otherwise  than  as  scrapers  for  removing  the  slight  superficial  roughness  without 
detracting  from  the  accuracy  of  form  previously  given.  In  a somewhat  similar  manner  the  broad  hand 
flat  tool,  rendered  elastic  by  its  partial  support,  as  in  Fig.  3610,  is  frequently  used  for  smoothing  brass 
works,  and  others  turned  with  the  slide-rest. 


Figs.  3646  and  3641  represent  a very  excellent  finishing  tool,  introduced  by  Mr.  Clement,  for  planing 
cast  and  wrought  iron  and  steel ; it  resembles  the  cranked  tools  generally,  but  is  slighter ; it  is  made 
smooth  and  flat  upon  the  extremity,  or  rather  in  a very  minute  degree  rounded.  This  tool  is  sharpened 
very  keenly  upon  the  oil-stone,  and  is  used  for  extremely  thin  cuts,  generally  one-quarter  of  an  inch 
wide,  and  when  the  corners  just  escape  touching  the  work  is  left  beautifully  smooth;  the  edge  should 
on  no  account  stand  in  advance  of  the  centre  line.  But  to  avoid  the  chatters  so  liable  to  occur  in  brass 
works,  Mr.  Clement  prefers  for  that  material  the  elastic  planing-tool,  Figs.  3648  and  3649 ; its  edge  is 
situated  considerably  behind  the  centre. 

In  concluding  the  notice  of  the  turning  tools  it  may  be  necessary  to  add  a few  words  on  those  used 
for  lead,  tin,  zinc,  copper,  and  their  ordinary  alloys.  The  softest  of  these  metals,  such  as  lead,  tin,  and 
soft  pewter,  may  be  turned  with  the  ordinary  tools  for  soft  wood ; but  for  the  harder  metals,  such  as 


TOOL,  RADIAL  DRILLING. 


773 


zinc,  and  hard  alloys  containing  much  antimony,  the  tools  resemble  those  used  for  the  hard  woods,  and 
they  are  mostly  employed  dry. 

Copper,  which  is  much  harder  and  tougher,  is  turned  with  tools  similar  to  those  for  wrought-iron,  but 
in  general  they  are  sharpened  a little  more  keenly,  and  water  is  allowed  to  drop  upon  the  work  to  lessen 
the  risk  of  dragging  or  tearing  up  the  face  of  the  copper,  a metal  that  neither  admits  of  being  turned  or 
filed  with  the  ordinary  facility  of  most  others.  Silver  and  gold,  having  the  tenacious  character  of  cop 
per,  require  similar  turning  tools,  and  they  are  generally  lubricated  with  milk. 

In  the  above,  and  nearly  all  the  metals  except  iron  and  those  of  equal  or  superior  hardness,  there 
seems  a disposition  to  adhere,  when  by  accident  the  recently  removed  shaving  gets  forcibly  pressed 
against  a recently  exposed  surface,  (the  metals  at  the  time  being  chemically  clean  ;)  this  disposition  to 
unite  is  nearly  prevented  when  water  or  other  fluid  is  used. 

Water  is  occasionally  resorted  to  in  turning  wrought-iron  and  steel ; this  causes  the  work  to  be  left 
somewhat  smoother,  but  it  is  not  generally  used,  except  in  heavy  work,  as  it  is  apt  to  rust  the  machin- 
ery ; oil  fulfils  the  same  end,  but  it  is  too  expensive  for  general  purposes. 

Cast-iron,  having  a crystalline  structure,  the  shavings  soon  break  without  causing  so  much  friction  as 
the  hard  ductile  metals ; cast-iron  is  therefore  always  worked  dry,  even  when  the  acute  edges  of  60 
degrees  are  thickened  to  those  of  80  or  90,  either  from  necessity,  as  in  some  of  the  small  boring  tools, 
or  from  choice  on  the  score  of  durability,  as  in  the  largest  boring  tools  and  others.  Brass  and  gun  metal 
are  also  worked  dry,  although  the  turning  tools  are  nearly  rectangular,  as  the  copper  becomes  so  far 
modified  by  the  zinc  or  tin,  that  the  alloys,  although  much  less  crystalline  than  cast-iron,  and  less  duc- 
tile than  copper,  yield  to  the  turning  tools  very  cleanly  without  water. 

But  when  tools  with  rectangular  edges  are  used  for  wrought-iron  and  steel,  on  account  of  the  greater 
cohesion  of  these  materials,  they  must  be  lubricated  with  oil,  greese,  soap  and  water,  or  other  matter, 
to  prevent  the  metals  from  being  torn.  And  the  screw-cutting  tools,  many  of  which  present  much  sur- 
face friction,  and  also  rectangular  or  still  more  obtuse  edges,  almost  invariably  require  oil  or  other  unc- 
tuous fluids  for  all  the  metals. 

In  the  practice  of  metal  turning  the  diamond  point  a b,  Big.  2845,  is  occasionally  used  in  turning 
hardened  steel  and  other  substances ; i f,  Fig.  2845,  are  constantly  used  in  engraving  by  machinery, 
and  in  graduating  mathematical  instruments. 


TOOL,  RADIAL  DRILLIISU — By  Messrs.  Whitworth  & Co.,  Manchester.  This  is  an  entirely 
different  arrangement  of  drilling  machine  from  those  before  described.  It  embodies  the  elegant  feeding 
apparatus  introduced  by  the  same  makers,  and  described  in  the  account  already  given  of  their  vertical 
drilling  machine,  p.  387  ; but  in  that  form  of  the  machine  the  drilling  spindle  does  not  admit  of  any  lat- 
eral motion ; it  is  strictly  confined  to  the  same  vertical  position,  and  in  that  can  rise  and  fall  at  the  wil.' 


774 


TOOL,  RADIAL  DRILLING. 


of  the  operator ; but  in  this  the  drill-spindle  has  not  only  the  same  vertical  and  revolving  motions  as  ir. 
that  form  of  the  machine,  but  admits  also  of  a lateral  motion  whereby  it  can  be  brought  over  the  work 
into  any  required  position  within  the  limits  of  the  radial  arm  D,  on  which  the  whole  drilling  apparatus 
is  carried. 

The  arrangement  consists  of  a strong  upright  framing  A A,  Fig.  3650,  with  a sole  by  which  it  can  be 
bolted  to  a stone  foundation.  To  this  is  attached  a vertical  sliding  bracket  B B B,  attached  by  dove- 
tailed guides.  This  bracket  is  raised  and  lowered  at  pleasure,  according  to  the  height  required  for  the 
work,  by  means  of  a handle  which  fits  on  the  end  of  the  tangent-screw  L ; this  screw  works  into  the 
tangent- wheel  K,  on  the  spindle  of  which  is  a small  pinion  which  geers  with  a rack  on  the  back  of  the 
bracket  B B.  The  bracket  is  secured,  when  raised  to  its  proper  position,  by  the  pinching-screw  w,  on 
the  outer  end  of  which  a handle  is  fixed. 

C C is  the  sole  of  the  radial  arm  D D.  It  is  supported  in  bearings  at  its  extremities  in  the  vertical 
slide  B B,  and  by  this  means  can  swing  through  an  arc  of  180  degrees.  On  this  arm  D D is  carried 
movable  slide,  to  which  all  the  drilling  apparatus  is  attached. 


3IS5J. 


E is  the  pulley-cone  by  which  motion  is  communicated  to  the  machine.  On  the  spindle  of  this  cone 
is  keyed  the  bevel-wheeiy,  which  geers  with  the  similar  wheel  marked  e on  the  vertical  spindle  g.  This 
spindle  is  provided  with  a sunk-feather  to  allow  it  to  slide  through  the  eye  of  the  wheel  e when  the 
bracket  is  moved  vertically.  On  the  upper  end  of  the  spindle  g is  keyed  the  bevel-wheel  h,  which 
works  into  another  similar  wheel  on  the  end  of  the  horizontal  and  hollow  shaft  G,  which  has  its  bearing 
in  the  boss  F.  This  hollow  shaft  G has  a groove-cut  inside  of  it  to  receive  a feather  inserted  into  the 
spindle  k,  which  passes  into  it,  and  with  which  it  must  of  necessity  turn  by  virtue  of  the  connecting 
feather  or  key  projecting  from  the  surface  of  k.  The  other  end  of  the  spindle  k has  its  extreme  bear- 
ings in  the  slide,  and  has  the  bevel-wheel  o keyed  upon  it ; this  wheel  geers  with  that  marked  n on  the 
drill-spindle.  It  is  therefore  clear  that  motion  being  communicated  to  the  driving  pulley-cone  E,  it  will 
be  transferred  to  the  bevel-pair  f and  e,  then  to  the  similar  bevel-pair  at  li,  and  from  that  point  through 
g and  k to  the  bevel-pair  o and  n,  the  last  of  which  is  placed  on  the  drill-spindle  l with  a sliding  feather 
or  key,  as  before  explained. 

We  have  described  the  wheel  which  geers  with  that  marked  h,  as  being  directly  keyed  on  the  hollow 


TOOL,  PORTABLE  DRILLING. 


775 


piece  G- ; this,  however,  is  not  the  case : the  wheel  is  keyed  on  an  independent  short  spindle  of  its  own, 
which  enters  G-  in  F,  and  connects  itself  also  by  a sunk  key,  so  that  the  piece  G is  nothing  more  than  a 
coupling  for  this  spindle  with  that  marked  k,  and  can  moreover  be  slid  considerably  further  into  the 
boss  F than  is  represented  in  the  drawing,  Fig.  3652. 

The  slide  is  moved  along  the  radial  arm  D by  a crank-handle  placed  on  the  squared  end  of  the  screw 
v v,  which  passes  through  a nut  fixed  on  the  back  of  the  slide  in  the  usual  manner. 

The  slide  moves  along  the  arm  in  dovetail  guides,  as  shown  in  the  front  view,  Fig.  3653 ; on  the 
upper  side  are  the  adjusting  piece  c and  setting-screws  d. 

As  already  stated,  the  feeding  apparatus,  and  in  fact  all  the  drilling  tackle,  is  identical  in  arrange- 
ment with  that  described  on  p.  387  : pp  are  the  friction-pulleys  on  the  same  axes  as  the  screw-wheels 
which  geer  with  the  screwed  part  r of  the  drill-spindle,  q q are  the  friction-clips  upon  the  pulleys  p p, 
and  s is  the  screwed  rod  by  which  the  clips  are  brought  into  action. 

For  some  special  purposes  the  radial  drill  affords  great  convenience,  hut  where  much  accuracy  is  re- 
quired it  cannot  be  so  well  depended  upon  as  the  ordinary  form,  as  it  rarely  possesses  the  requisite 
degree  of  rigidity. 

It  may  be  here  observed,  that  the  merit  of  first  introducing  this  description  of  drilling  machine  is  due 
to  Messrs.  Benjamin  Hick  & Son,  of  Bolton. 


3654.  3653.  3655. 


TOOL,  PORTABLE  DRILLING — By  Nasmyth,  Gaskell  <fe  Co.,  Manchester,  big.  3652  is  a side 
elevation  of  the  machine;  Fig.  3653,  a front  view. 

Fig.  3654  is  a partial  section  through  the  axis  of  the  drill-spindle. 

Fig.  3655,  a cross-section  above  the  table  N,  showing  the  form  of  the  frame  A.  A. 

This  frame  is  formed  of  one  casting,  and  is  bolted  to  a large  sole-plate,  which  serves  as  a foundation 
without  other  fixing. 

B B,  the  drill-spindle,  passes  through  a long  tube  marked  C C,  and  which  serves  as  a guide  to  the 
spindle,  in  ascending  and  descending.  The  spindle  is  attached  by  a sunk-featlier  to  the  interior  of  the 
tube,  so  that  the  spindle  can  slide  in  it  vertically,  but  cannot  turn  round  within  it. 

D D,  the  two  fixed  brackets  in  which  are  the  bearings  of  the  guide-table  C C,  the  plan  of  which  is 
shown  separately  by  Fig.  3658. 

E,  a set  of  driving  cone-pulleys  corresponding  to  the  lower  set  of  cone-pulleys  F.  On  these  two  set; 


TORSION. 


(76 


of  pulleys  is  placed  the  belt,  -which  directly  gives  motion  to  the  drill-spindle  by  means  of  the  bevel-pair 
a and  b,  of  which  the  wheel  marked  a is  keyed  on  the  guide-tube  0 C of  the  drill-spindle,  and  tha* 
marked  b is  fast  on  the  rod  of  the  same  spindle  on  which  are  the  cone-pulleys  E. 

G and  H,  a pair  of  pulleys,  one  fast  and  the  other  loose,  by  which  the  machine  is  driven.  They  are 
upon  the  same  spindle  as  the  lower  cone-pulleys  F,  by  w'hicli  the  motion  is  conveyed  through  a belt  to 
the  pulley  E. 

I,  a link  connecting  the  foot-lever  J with  the  weighted  lever  L,  one  end  of  which  enters  a recess  d of 
the  sliding  bracket  h h,  the  sole  of  which  is  guided  in  dovetail  grooves,  formed  by  the  pieces  bb  bb,  seen 
in  Fig.  3653.  From  this  arrangement  it  is  easy  to  perceive  that  when  the  foot  is  pressed  upon  the  foot- 
board at  J,  the  link  I will  cause  the  weighted  end  of  the  lever  L to  ascend,  and  the  other  to  descend ; 
and  at  the  same  time  the  sliding  bracket,  into  which  is  fitted  the  top  of  the  drill-spindle. 

The  manner  of  attaching  the  drill-spindle  to  the  sliding  bracket  is  rendered  obvious  by  Fig.  3654  : 
the  top  is  formed  with  a rutf  upon  it,  which  is  kept  in  the  screwed  recess  formed  in  c to  receive  it,  by 
the  hollow  screw  which  bears  against  the  under  side  of  the  ruff.  The  spindle  is  at  the  same  time  met 
above  by  a screwed  steel  pin.  The  end  of  this  pin  sustains  the  downward  pressure  when  the  foot  is 
placed  on  the  treddle  J. 

M is  the  bracket  of  the  table  1ST.  The  table  is  simply  a plank  of  wood  resting  upon  the  top  plate  of 
the  bracket. 

As  the  travel  of  the  drill-spindle  is  very  limited,  the  table-bracket  can  be  raised  and  lowered  at  pleas- 
ure, through  the  required  range,  by  means  of  the  screw  S.  Its  sole  is  guided  vertically  by  grooves  k k 
in  the  frame ; this  has  also  grooves  formed  in  it  to  receive  the  heads  of  the  setting-bolts  m m,  the  nuts  of 
which,  being  screwed  tight,  keep  the  bracket  in  its  place.  The  bolt-heads  are  entered  through  the  open- 
ings n,  and  slide  down  the  grooves  1 1 ; the  arrangement  of  the  table-screw  S,  with  the  hand-wheel  for 
working  it,  also  its  socket  with  the  treddle-lever  attached,  are  shown  in  plan,  Fig.  3659. 

Fig.  3656  is  a plan  of  the  sliding  bracket  for  feeding  the  drill-spindle ; and  Fig.  3657  is  a plan  of  the 
lever  by  which  it  is  worked  by  means  of  the  treddle  and  link  I. 

TORSION  in  mechanics  is  the  twisting  or  wrenching  of  a body  by  the  exertion  of  a lateral  force.  If 
a slender  rod  of  metal  suspended  vertically,  and  having  its  upper  end  fixed,  be  twisted  through  a cer- 
tain angle  by  a force  acting  in  a plane  perpendicular  to  its  axis,  it  will,  on  the  removal  of  the  force,  un- 
twist itself,  or  return  in  the  opposite  direction  with  a greater  or  less  velocity,  and,  after  a series  of  os- 
cillations, will  come  to  rest  in  its  original  position.  The  limits  of  torsion  within  which  the  body  will  re- 
turn to  its  original  state  depend  upon  its  elasticity.  A fine  wire  of  a few  feet  in  length  may  be  twisted 
through  several  revolutions  without  imparing  its  elasticity ; and  within  those  limits  the  force  evolved  is 
found  to  be  perfectly  regular,  and  directly  proportional  to  the  angular  displacement  from  the  position 
of  rest.  If  the  angular  displacement  exceeds  a certain  limit,  the  particles  of  the  body  will  be  wrenched 
asunder ; or  if  the  elasticity  is  not  perfect,  (as  in  a wire  of  lead,  for  example,  before  disruption  takes 
place,)  the  particles  will  assume  a new  arrangement,  or  take  a set,  and  will  not  return  to  then-  original 
position  on  the  withdrawal  of  the  disturbing  force. 

The  resistance  which  cylinders  or  prisms  formed  of  different  substances  oppose  to  torsion,  furnishes 
one  of  the  usual  methods  of  determining  the  elasticity  and  strength  of  materials ; and  the  property  which 
a metallic  wire  or  thread  stretched  by  a small  weight  possesses  of  becoming  twisted  and  untwisted  in 
a series  of  isochronous  and  perfectly  regular  oscillations,  has  been  ingeniously  applied  in  the  torsion 
balance  to  the  measurement  of  very  minute  forces,  and  thereby  to  the  establishment  of  the  fundamental 
laws  of  electricity  and  magnetism,  and  to  the  determination  of  the  mean  density  of  the  earth.  See  Bal- 
ance of  Torsion. 

The  laws  of  torsion  have  been  experimentally  investigated  by  Coulomb  in  a variety  of  substances ; 
as  metallic  wires,  hairs,  fibres  of  silk,  &c.  The  method  which  he  employed  consisted  in  attaching  a 
body  of  given  form  and  dimensions  to  the  extremity  of  the  wire,  and,  after  twisting  it  through  a certain 
angle,  to  abandon  it  to  the  action  of  the  force  evolved,  and  observe  the  time  of  the  oscillations.  The 
following  general  laws  were  found  to  hold  good : 

1.  On  loading  a wire  or  thread  with  different  weights,  it  will  settle  in  different  positions  of  stability; 
that  is  to  say,  an  index  attached  to  the  weight  will  point  in  different  directions  if  the  weight  be  varied, 
and  the  angular  deviation  may  amount  even  to  a whole  circumference. 

2.  The  oscillations  are  isochronous. 

3.  The  time  of  oscillation  is  proportional  to  the  square  root  of  the  weight  which  stretches  the  wire. 

4.  The  time  of  oscillation  is  as  the  square  root  of  the  length  of  the  wire. 

5.  The  time  of  oscillation  is  inversely  as  the  square  of  the  diameter  of  the  wire. 

From  the  second  of  these  laws  it  follows  that  when  the  wire  is  twisted  round  from  the  position  of  rest, 
the  force  with  which  it  tends  to  return  to  that  position  is  proportional  to  the  angle  to  be  described  in 
order  to  attain  it.  For  it  is  a general  result  of  mechanics  that  all  motions  produced  by  forces  acting 
according  to  this  law  have  the  property  of  tautochronism ; that  is  to  say,  the  oscillations  are  performed 
in  equal  times,  whatever  be  the  length  of  the  arc.  This  fundamental  property  is  usually  enunciated  by 
saying  that  the  force  of  torsion  is  proportional  to  the  angle  of  torsion. 

Let  F denote  the  force  of  torsion,  measured  by  the  weight  which  it  would  be  necessary  to  apply  by 
means  of  a pulley  to  a point  p,  situated  at  the  unit  of  distance  (one  inch)  from  the  axis  of  the  wire,  and 
invariably  connected  with  it,  to  cause  the  point  p to  describe  an  arc  of  a circle  equal  in  length  to  the 
unit  of  distance ; then,  by  the  property  enunciated,  the  force  which  must  be  applied  at  p in  order  that 
the  point  may  describe  any  arc  <p  is  expressed  by  F'  tp.  If  the  arc  of  torsion  is  expressed  in  degrees 
instead  of  parts  of  the  radius,  we  have  <p  — rr  <j>°  •—  ISO0  (r  being  the  semicircumference  to  radius  1,  or 
— 3-14159  ;)  whence  the  expression  of  the  force  becomes  F -|-  tt  <fi°  ~ 180°.- 

On  this  principle  of  the  proportionality  of  the  impelling  force  to  the  angle  or  deviation  the  problem 
of  determining  the  time  of  an  oscillation  is  solved.  Suppose  a body  of  any  form  attached  to  the  ex- 
tremity of  a slender  wire,  whose  weight  in  comparison  to  that  of  the  body  may  be  neglected,  and  le( 


TRANSIT  INSTRUMENT. 


777 


dm  be  an  element  of  the  mass,  r the  distance  of  dm  from  the  axis  of  the  -wire,  and  T the  time  of  ar 
oscillation  ; the  solution  of  the  problem  gives 

m , / nr2dm\  „„  , nr2 dm 

1 ^ (/—  ) ’ °r  T' = ' 

The  integral  J' r2  dm  is  the  moment  of  inertia  of  the  attached  body.  If  the  body  be  a cylinder  whose 
axis  coincides  with  that  of  the  wire,  and  if  a denote  its  radius  and  M its  mass,  then J'r2  dm  = \ Mu’; 
or,  substituting  the  weight  for  the  mass,  and  observing  that  if  the  weight  be  denoted  by  P,  and  the 
accelerating  force  of  gravity  by  <7  (=321908  feet  or  386.2894  inches  in  a second,)  we  have  P = 

M g,C r2  d rn  = P a2  -f-  2 g.  Hence  the  expression  for  the  time  becomes  T = r a if  — — . 

If  the  attached  body  were  a slender  cylindrical  needle  suspended  horizontally  by  its  middle  to  the 
wire,  we  should,  on  denoting  its  length  by  /,  have  J'r2  dm  = J M P ; whence  T = 7r  l if  - — -. 

The  following  results  are  deduced  from  the  formula:  1.  The  force  of  torsion  is  independent  of  the 
weight  which  stretches  the  wire,  or  F remains  constant  while  P is  varied.  For  suppose  P to  become 
P',  and  let  T'  be  the  corresponding  time  of  oscillation,  and  F'  the  corresponding  force,  we  have  then 

„„  id  ad  P d ad  P' 


2 y F ’ 2#F'  ’ 

whence  T2 : T/2 : : P F' : P'  F.  But,  by  the  third  experimental  law,  T2 : T'2 : : P : P' ; therefore  F'  = F. 

2.  The  force  is  inversely  as  the  length  of  the  wire.  For,  supposing  P to  remain  constant,  we  have 

T2 : T/2 : : F : F.  But,  bv  the  fourth  experimental  law,  T2 : T/2  whence  F' : F : : l : V. 

3.  The  force  is  proportional  to  the  fourth  power  of  the  diameter  of  the  wire.  Let  there  be  two  wires 
of  the  same  substance,  but  of  different  diameters,  D and  D',  and  stretched  by  the  same  weight  P ; and 
let  T and  T'  be  the  corresponding  times.  By  the  fifth  experimental  law,  we  have  T : T' : : D'2 : D2.  But 
it  has  been  shown  that  T2 : T'2 : : F' : F ; therefore  F : F' : : D4 : D'4. 

To  show  the  method  of  applying  the  formulae,  we  shall  compute  one  of  the  experiments  of  Coulomb. 
An  iron  wire  was  stretched  by  a vertical  cylinder  of  '8  of  an  inch  radius  and  weighing  2 lbs.,  and  it  was 
observed  to  make  20  oscillations  in  242  seconds,  or  one  in  12'1  seconds.  It  is  proposed  to  determine 

^2  p 

the  force  F.  From  the  formula  for  the  time  of  an  oscillation  we  have,  by  transposition,  F : 


a' 2 = 64,  P = : 


1 9- 


Substituting  numbers  in  this  formula,  we  have  id  — 9'8G96, 

12'633 

= 146'41  ; consequently  F = -A — — = -0001117  of  a pound,  or  about  -78  of  a grain 


86- 


2 g T2  ’ 
2894,  T2  = (12-l)2 

Hence  the  weight 


applied  at  the  distance  of  one  inch  from  the  axis  of  the  wire  that  would  be  required  to  twist  the  wire 
through  a complete  revolution,  or  360°,  is  6'283  times  this  quantity,  or  nearly  five  grains. 

For  the  demonstration  of  the  fundamental  formula,  namely,  T2  F — id J'r1  dm,  see  Coulomb,  Theorie 
des  Machines  Timples  ; or  Biot,  Traite  de  Physique,  tom.  i. 

TRANSIT  INSTRUMENT  for  the  correction  of  time-keepers.  Mr.  Dent  had  long  felt  persuaded 
that  the  interest  of  Horology  would  be  promoted  if  the  public  were  more  generally  possessed  of  a 
cheap,  simple,  and  correct  transit  instrument,  requiring  little  or  no  scientific  knowledge  for  its  right  use, 
and  not  readily  susceptible  of  injury  or  derangement.  To  this  end  he  had  devoted  much  time  and 
thought;  and,  in  1840,  he  considered  that  he  had  succeeded  in  inventing  an  apparatus  which,  by  means 
of  shadows,  would  produce  the  desired  result.  This  idea  he  communicated  to  J.  M.  Bloxam,  Esq.,  who 
thereupon  informed  him  that  his  own  attention  had  for  some  years  been  devoted  to  the  same  object, 
and  that  he  had  contrived  an  optical  arrangement,  which,  by  the  agency  of  a single  and  double  reflec- 
tion, determined  the  sun’s  passage  over  the  meridian  with  great  exactness.  Convinced  of  the  supe- 
riority of  Mr.  Bloxam’s  contrivance,  Mr.  Dent,  in  conjunction  with  that  gentleman,  after  two  years  of 
great  labor  and  expense,  produced  the  instrument  in  its  present  simple  and  accurate  form.  It  has  been 
made  the  subject  of  a patent,  and  may  be  had,  with  complete  instructions  for  its  use,  from  the  maker 
and  proprietor,  Mr.  Dent. 

Fig.  3660  gives  a general  outline  of  the  instrument,  in  readiness  for  taking  observations. 


3'&4'  3&4  l'  1 2 


The  Dipleidoscope  operates  by  reflecting  the  sun’s  rays  by  means  of  a simple  combination  of  reflect- 
ing surfaces.  Bearing  this  in  mind,  and  remembering  also  that  the  angle  of  the  incident  rays  of  light 
falling  upon  a plane  is  equal  to  the  angle  of  the  reflected  rays,  the  nature  and  action  of  the  instrument 
will  be  obvious  from  the  figure. 


778 


TRIP-HAMMER. 


The  instrument  consists  of  three  reflecting  planes  DC,  D B,  and  B C,  Fig.  3661.  D C represents  tlia 
exterior  plate  of  glass,  which  covers  in  the  other  two  opaque  glass  surfaces  D B and  B C,  set  in  the  in 
terior  of  the  instrument.  Suppose  D C to  be  so  divided  that  the  ray  No.  1 falling  on  D C,  at  E,  will 
be  reflected  to  the  eye  at  1',  and  the  image  of  the  sun  will  appear  to  advance  in  the  direction  from  1) 
towards  C.  The  ray  No.  2 passing  through  D C,  is  reflected  from  C B,  impinges  on  D B,  and  reaches 
the  eye  in  the  direction  2'.  The  image  of  the  sun  thus  formed  will  appear  to  move  from  C towards  D, 
because  it  has  been  twice  reflected,  and  thus  the  two  images  will  approach  each  other.  Suppose  the 
ray  No.  1 to  have  advanced  to  the  position  No.  3,  and  the  ray  No.  2 to  the  position  No.  4;  it  will  then 
be  evident  that  their  reflected  rays  will  be  in  the  same  direction  3'  and  4',  and,  therefore,  that  the  two 
images  of  the  sun  coincide,  as  shown  by  the  arrows  being  in  the  position  of  crossing  each  other,  and  in- 
dicating the  instant  of  apparent  noon ; as  the  rays  continue  to  advance,  the  images,  having  passed  over 
each  other,  will,  of  course,  be  seen  to  separate. 

The  following  familiar  illustration  is  introduced  to  further  explain  the  optical  construction.  When 
the  sun  is  about  setting,  it  is  not  uncommon  to  see  the  rays  so  reflected  from  the  windows  of  a whole 
range  of  houses,  as  to  convey  the  idea  of  a public  illumination.  While  some  portions  of  the  sun’s  rays 
are  thus  reflected,  other  portions  pass  through  the  glass  into  the  rooms.  The  rays  thus  transmitted 
(the  rays  of  incidence , as  they  were  styled  above)  may  be  thrown  at  pleasure  in  any  direction  consist- 
ent with  the  range  of  the  sun,  by  a person  within  the  room,  having  a looking-glass  in  his  hand:  exactly 
as  children  produce  what  they  call  a Jack-o’- Lantern.  Now  if,  instead  of  throwing  the  rays  upon  a 
non-reflecting  object,  (sucli  as  the  wall,  die.,)  he  were  to  transfer  them  to  another  looking-glass,  they 
would  be  again  reflected  from  this  latter  glass.  Supposing  these  two  looking-glasses  to  be  placed  at 
an  angle  of  less  than  90°,  in  a manner  corresponding  with  the  position  of  the  two  silvered  planes  seen 
in  the  instrument,  and  also  shown  in  the  figure  at  D B,  B C,  he  can  reflect  the  sun’s  rays  again  out  of 
the  window.  Now,  if  we  imagine  the  window  to  represent  the  outer  reflector  of  the  meridian  instru- 
ment, its  construction  is,  by  this  process,  completely  exemplified.  To  proceed  a little  further;  it  is 
evident,  that  the  angle  and  situation  of  the  two  looking-glasses  could  be  so  arranged  as  to  direct  the 
rays  of  the  sun  through  any  particular  pane  of  the  window ; so  that  a person  standing  without,  in  a 
proper  position,  would  see,  in  addition  to  the  sun’s  rays  reflected  from  the  outer  surface  of  the  pane,  the 
rays  of  incidence  that  had  passed  through  the  window,  and  were  thus  reflected  from  the  double  mirror. 
One  of  the  luminous  objects  (the  flash  or  glare  of  the  sun)  so  produced,  would  be  reflected  from  the 
surface  of  the  window,  and  would  be  a single  reflection ; while  the  rays  of  incidence,  which  had  passed 
through  the  window,  and  undergone  a double  reflection  by  means  of  the  two  mirrors  would,  on  being 
thrown  back  by  the  mirrors  tlirougli  the  window,  move  in  a direction  contrary  to  that  taken  by  the 
single  reflection  from  the  surface  of  the  window-pane.  Hence,  any  one  of,  the  heavenly  bodies,  sub- 
jected to  the  eye  by  a process  of  the  above  description,  would  not  only  appear  as  two  distinct  objects, 
but  those  objects  would  be  seen  to  approximate  and  cross  each  other  in  an  opposite  course : a desidera- 
tum being  hereby  secured  which  increases  the  power  of  the  instrument  in  a double  ratio,  and  renders  it 
proportionably  preferable  to  any  other  that  has  been  hitherto  employed. 

The  Dipleidoscope,  or  new  patent  meridian  instrument,  will  enable  any  person  to  obtain  correct  time 
with  the  greatest  facility,  by  an  observation  either  of  the  transit  of  the  sun  over  the  meridian  by  day,  or 
of  the  transit  of  the  stars  by  night.  It  possesses  great  advantages  over  any  other  of  similar  correctness  ; 
it  is  exceedingly  simple,  it  is  not  liable  to  get  out  of  adjustment  or  repair,  and  it  does  not  require  any 
attention  beyond  that  which  is,  of  course,  necessary  in  the  first  instance,  viz.,  that  it  be  placed  on  a 
level  surface,  and  in  the  meridian.  The  observations  to  be  taken  afterwards  can  be  made  by  any  one, 
although  previously  unacquainted  either  with  astronomical  apparatus  or  practical  astronomy ; the  in- 
strument being  as  simple  as  a sun-dial,  while  it  is  infinitely  more  correct,  since  it  gives  the  time  to 
within  a fraction  of  a second.  The  utility  of  possessing  an  indicator  of  this  kind  in  addition  to  the  most 
perfect  time-keeper,  must  be  evident : for,  however  excellent  a clock  or  watch  may  be,  experience 
shows  how  difficult  it  is  to  obtain  exact  time,  for  lengthened  periods , by  any  mere  mechanical  contriv- 
ance. To  remedy  the  defect  of  mechanism,  it  has  been  already  remarked,  that  actual  observation  of 
the  heavenly  bodies  becomes  indispensable ; as,  without  it,  the  best  time-keeper  cannot  be  implicitly 
depended  upon  for  any  considerable  interval. 


TRIP-HAMMER.  Fig.  3662  is  a side  elevation  of  a small  trip-hammer,  such  as  is  commonly  used 
/or  forging  spindles  and  bolts,  and  for  swaging  various  other  kinds  of  small  work 


TUBE-MAKING  MACHINERY. 


779 


Fig.  3663  is  an  end  elevation  of  the  same,  A is  the  driving-pulley,  with  a flanch  on  each  side  to 
guide  the  belt  while  running  loose.  This  pulley  is  attached  to  the  cam-shaft,  upon  the  other  end  of 
which  is  the  balance-wheel  E.  C a foot-lever,  connected  with  the  catch  b , by  a rod  and  spring,  and  by 
means  of  which  the  hammer  can  he  stopped  or  started  without  shipping  the  belt.  F,  bed  of  timbers 
bolted  together  to  support  hammer.  G,  post  in  which  the  hammer-block  is  placed — usually  extending 
into  the  ground  four  or  five  feet,  f is  the  husk-supporter  or  rocker,  adjusted  by  screws  and  bolts,  so 
that  the  hammer  can  be  set  at  any  taper.  S is  a heavy  cast-iron  bed-plate  to  which  all  other  parts  are 
connected.  This  plate  is  bolted  firmly  to  the  timbers  below. 

TRIP  or  TILTING  HAMMER.  From  the  Lowell  Machine  Shop.  Figs.  3661  and  3665  are  side 
and  end  elevations  of  a tilting  hammer,  with  a head  weighing  250  lbs. 

a is  the  driving-pulley.  As  the  Delt  runs  loose  around  the  pulley  when  the  hammer  is  not  in  use* 
here  is  a flanch  on  each  side  to  keep  the  belt  in  its  place. 

B,  large  timbers  on  which  the  heavy  iron-work  rests. 

P,  timbers  disconnected  with  B,  which  support  the  block  S in  which  the  lower  die  is  fastened. 


3665.  S6G4. 


e,  a spring  of  the  best  kind  of  timber,  which  serves  as  a stop  for  the  hammer  when  raised,  and  gives 
force  to  the  blow. 

b is  the  cam,  which  raises  the  hammer  twice  in  one  revolution. 

The  hush  of  this  hammer  is  hung  in  a rocking  stand,  adjusted  by  set-screws  and  bolts,  so  that  it  can 
be  set  at  any  taper  for  drawing  tapering  work. 

This  hammer  is  well  adapted  to  swaging  car-axles,  Ac. 

TUBE-MAKING  MACHINERY — Deakin’s  improvements,  1850.  The  patentee’s  invention  relates 
to  rolling  machinery  for  the  manufacture  of  metallic  cylindrical,  taper,  and  other  tubes  and  solids 

3666. 


Fig.  3666  represents  a longitudinal  vertical  section  of  the  machinery  for  making  tubes,  taken  centn- 
cally  through  the  rollers  at  the  line  1,  1 ; Fig.  3667  is  a plan  view.  A A,  the  side  framing  of  the  ap- 
paratus, upon  which  are  mounted  the  four  pairs  of  rollers,  B B B B.  The  patentee  does  not,  however, 
confine  himself  to  the  employment  of  this  number  of  rollers  in  each  apparatus,  as  a greater  or  less  num- 
ber may  be  used,  but  he  prefers  this  number  generally,  as  most  advantageous.  These  rollers  are  con- 
nected together  by  means  of  spur-wheels,  so  that  the  surface  velocities  of  the  rollers  acting  immediately 
upon  the  metal  passing  between  shall  be  equal,  although  the  diameters  of  such  rollers  may  be  unequal 
or  equal,  as  most  convenient.  Immediately  in  front  of  the  first  pair  of  these  rollers  B B are  placed  tk* 


780 


TUBE-MAKING  MACHINERY. 


pair  of  rollers  C C1,  the  centres  of  the  shafts  of  these  rollers  being  in  a direction  at  or  near  right  angles 
to  those  of  the  rollers  B B,  and  therefore  revolving  at  right  angles  to  them.  The  peripheries  of  the  roll- 
ers B B are  all  concave,  the  concavity  of  the  first  pair  from  the  rollers  C Cl  being  greater  than  the  con- 
cavity of  the  other  pairs,  and  this  concavity  decreases  in  each  pair  of  rollers  until  the  last,  in  which  the 
two  concavities  of  the  rollers  form  together  a circle.  The  peripheries  of  the  two  rollers  C C1  are  differ- 
ent from  each  other ; that  is,  one  of  them,  as  C,  is  convex,  and  the  other,  C1,  is  concave.  The  lower  ends 
of  the  vertical  shafts  D D,  carrying  the  rollers  C C1,  revolve  in  steps,  E1,  E2,  upon  the  bed-plate  F,  which 
thereby  supports  the  weight  of  them  and  the  rollers.  The  rollers  are  geered  together  by  spur-wheels, 
and  the  requisite  rotary  motion  is  given  to  them  and  to  the  rollers  B B by  any  well  known  and  conve- 
nient means.  G represents  the  plate  or  skelp  of  metal  in  the  process  of  being  bent  and  formed  into  a 
tube.  The  flat  skeip  is  previously  heated  in  a suitable  furnace,  and  then  passed  through  the  machine, 
first  between  the  convex  and  concave  rollers  C C1,  by  which  it  is  bent  from  its  previous  flat  form,  and 
assumes  that  of  the  peripheries  of  the  rollers,  being  about  semi-cylindrical,  of  considerably  larger  diam- 
eter or  radius  than  that  of  the  intended  tube,  and  then  passes  on  to  the  first  pair  of  the  horizontal  rollers 
B B,  by  which  the  edges  of  the  skelp  become  further  bent  round,  and  begin  to  approach  each  other,  and 
this  rounding  gradually  goes  on  in  the  passage  between  the  remaining  pairs  of  rollers.  In  passing  be- 
tween the  second  pair  of  rollers,  the  edges  are  caused  to  approach  nearer  together ; the  action  of  the 
third  pair  brings  the  edges  into  contact,  and  the  last  pair  effects  the  closing  or  welding  of  the  joint. 
When  the  whole  formation  of  the  tube  is  intended  to  be  effected  at  one  operation  of  the  machine,  it  is 
necessary  that  the  skelp  should  be  at  a welding  heat  when  passed  into  the  machine.  Thus  it  will  be 
seen,  that  at  one  operation  of  the  machine,  the  flat  plate  or  skelp  will  be  bent  up  to  the  cylindrical  form, 
the  joint  welded  up,  and  the  perfect  tube  produced  at  one  heat  of  metal.  This  result,  however,  cannot 
always  be  obtained,  as  when  very  thin  plates  or  skelps  are  used  for  the  manufacture  of  tubes.  In  this 
case  the  metal  cannot  be  retained  at  a welding  heat  sufficiently  long  to  insure  a perfect  junction  of  the 
edges  of  the  skelp  at  the  last  pair  of  rollers,  therefore  the  skelp  is  bent  up  to  the  tubular  form,  and  the 
edges  brought  together  at  the  first  operation,  preparatory  to  the  welding  process,  which  the  patentee 
then  effects  by  passing  it,  at  a welding  heat,  between  the  rollers  of  a second  machine  of  similar  construc- 
tion to  that  previously  described,  but  not  having  any  rollers  similar  to  these,  C Cl.  The  rollers  B B are 
sometimes  arranged  in  vertical  positions,  instead  of  horizontal,  as  described ; the  rollers  C C1  will  like- 
wise be  reversed  in  their  position,  but  their  action  on  the  skelp  and  the  result  will  be  precisely  the 
same  as  by  the  first  arrangements. 

The  next  improvement  consists  in  the  means  of  manufacturing  taper  tubes.  The  machinery  em- 
ployed for  this  purpose  is  the  same  as  that  previously  described  for  manufacturing  cylindrical  tubes, 
except  that  one  or  more  of  the  pairs  of  rollers  employed,  instead  of  having  their  grooves  regular,  and 
of  equal  size  throughout  the  whole  of  their  peripheries,  are  formed  of  varying  sizes,  either  increasing  or 
decreasing,  according  as  the  tube  to  be  manufactured  is  required  to  be  produced  of  increasing  or  de- 
creasing diameter.  One  of  the  rollers  is  represented  in  section,  Fig.  3668,  which  shows  the  form  of  the 

36CS.  8CC9. 


groove.  It  will  be  seen  that  proceeding  from  the  cutter  I2,  Fig.  3668,  in  one  direction  round  the  roller, 
the  size  of  the  groove  is  gradually  increased  until  it  arrives  at  the  same  point,  which  is  the  junction  of 
the  greatest  and  smallest  portions  of  the  groove ; proceeding  in  the  other  direction  from  the  same  point 
the  reverse  obtains,  the  corresponding  roller  working  with  the  one  shown  in  section,  both  being  grooved 
in  a similar  manner,  so  that  when  working  together  they  present  a circular  passage  of  gradually  vary- 
ing diameter,  and  thereby  produce  a tube,  the  taper  of  which  corresponds  with  the  varying  size  of  the 
grooves ; the  variation  in  the  sizes  of  the  grooves  will  of  course  depend  upon  the  degree  of  taper  the 
manufactured  tube  is  required  to  have.  The  patentee  sometimes  employs  taper  plates  or  skelps  of 
metal  in  the  manufacture  of  taper  tubes,  by  means  of  the  above-described  machinery ; and  when  he  re- 
quires to  manufacture  tubes  with  the  interior  cylindrical,  and  taper  upon  the  exterior,  he  then  employs 
skelps  of  metal  of  unequal  thickness.  The  means  adopted  for  forming  and  making  the  varying  grooves 
in  the  rollers,  so  that  they  shall  present  a smooth  surface,  and  also  that  their  variations  shall  be  perfectly 
regular  and  uniform  throughout  the  circumference,  is  this : — It  consists  of  a frame  or  head-stock  H,  Fig 
3668,  fitted  in  bearings,  in  the  top  of  the  uprights  of  which  is  mounted  the  shaft  or  mandril  H1,  upon 
which  is  fixed  the  driving  cone  of  pulleys  or  wheels,  H2,  by  which  the  requisite  rotary  motion  is  given 
to  the  mandril  H : the  mandril  is  hollow,  and  slotted  upon  opposite  sides.  A rod  I passes  into  the  hol- 
low of  the  mandril  from  one  end.  The  inner  end  of  the  rod  is  pointed  or  wedge  shaped,  and  passes 
into,  and  bears  against  a corresponding  recess  in  the  end  of  the  cutter  I1,  which  is  of  two  or  more  parts, 
the  cutting-edges  of  which  pass  through  the  slots  in  the  sides  of  the  mandril,  and  project  beyond  it 


TUBE-MAKING  MACHINERY. 


781 


The  rod  I is  caused  to  traverse  along  the  mandril  by  means  of  the  screw  I2,  passing  through  a bracket 
fixed  to  the  back  of  the  upright  carrying  the  open  end  of  the  mandril,  the  end  of  the  screw  bearing 
against  the  end  of  the  slotting-rod  I,  so  that  as  the  screw  is  screwed  up,  it  causes  the  cutter  to  expand 
by  acting  on  the  rod.  The  cutter  is,  of  course,  carried  round  with  the  mandril.  A spur-pinion  is  fixed 
upon  the  screw  I2,  by  which  a slow  but  regular  rotary  motion  is  given  to  it,  by  which  the  expansion  of 
the  cutter  is  effected  at  a regular  and  uniform  rate.  The  rollers  L L are  mounted  upon  shafts  in  a 
carrying-frame,  in  position  shown,  the  groove  to  be  cut  off,  one  being  above  and  one  beneath  the  cutter. 
A slow  rotary  motion  is  given  to  the  rollers,  both  moving  at  equal  velocities,  at  the  same  time  that  a 
rapid  motion  is  given  to  the  mandril  and  cutters ; when  the  cutter  is  in  the  position  shown  in  the  draw- 
ings, the  largest  part  of  the  groove  required  will  be  cut,  because  the  largest  part  of  the  cutter  is  then 
in  the  plane  passing  through  the  two  centres  of  the  rollers;  but  as  the  cutting  progresses,  the  size  of 
the  groove  cut  will  gradually  decrease,  by  reason  of  the  cutter  being  caused  to  traverse  along  the  man- 
dril, when  the  small  part  of  the  cutter  comes  gradually  into  action,  until  the  rollers  have  made  one 
revolution,  when  the  cutter  will  have  traversed  so  far  that  only  the  small  end  of  the  cutter  will  be  in 
action,  in  cutting  the  smallest  part  of  the  groove,  where  the  junction  with  the  largest  part  of  it  takes 
place.  The  degree  of  variation  of  the  grooves  cut  in  the  peripheries  of  the  rollers  will  depend  upon  the 
form  and  length  of  the  cutter,  and  amount  and  rate  of  traverse  given  to  it,  in  relation  to  that  of  the 
rollers  upon  their  axis.  In  manufacturing  other  forms  of  tube,  the  patentee  employs  the  cylindrical 
tubes  in  the  manner  before  described,  which  are  reheated  and  passed  between  rollers,  the  peripheries 
of  which  are  of  such  a form  as  to  cause  the  tubes  to  assume  the  exterior  form  desired.  A pair  of  rollers, 
the  forms  or  shapes  of  the  peripheries  of  which  are  such  as  to  compress  the  cylindrical  tubes  between 
them,  and  into  the  form  of  a hollow  railway  rail,  are  shown  in  Fig.  3671. 

Fig.  3669  shows  an  arrangement  of  these  rollers,  OOO,  placed  triangularly,  for  compressing  and  roll- 
ing cylindrical  tubes  into  hollow  trilateral  forms,  suitable  likewise  for  railway  rails,  the  peripheries  of 
the  rollers  being  of  such  shapes  as  to  produce  the  forms  required. 

Fig.  3670  shows  the  hollow  trilateral  rail  produced,  and  rolled  by  the  arrangement  of  rollers,  as  shown 

Fig.  3669. 


3670.  3673. 

<3» 


Fig.  3675  is  another  form  of  hollow  trilateral  rail,  slightly  differing  from  the  preceding. 

Fig.  3673  represents  a cylindrical  tube. 

Fig.  3674  is  a taper  tube,  the  interior  and  exterior  being  of  uniform  tape)-,  and  of  equal  thickness  ol 
metal  throughout. 

Fig.  3672  represents  a tube  tapered  exteriorly,  and  cylindrical  interiorly,  and  of  an  equal  thickness 
of  metal.  Mandrils  may  be  employed  or  not  in  the  above  modes  of  manufacturing  tubes,  as  convenient. 

The  next  improvement  relates  to  the  manufacture  of  spiral  or  helical  metal  tubes.  This  improve- 
ment is  illustrated  in  Fig.  3676,  which  represents  an  elevation  of  the  apparatus.  The  apparatus  con- 


sists of  a pair  of  rollers  P P,  mounted  one  above  the  other  in  the  framing  QQ,  the  bearings  in  which 
the  rollers  revolve  being  in  the  uprights  Q1  Q1  of  the  framing,  and  the  mode  of  attachment  to  the  bear- 
ings being  such  that  the  rollers  may  be  removed  or  replaced  with  facility,  as  it  is  necessary  to  remove 
the  rollers  from  the  frame  before  the  spiral  or  helical  tubes  can  be  removed  from  the  rollers.  These 
rollers  are  geered  together  at  one  end  by  the  geering-wheels  P1  P1,  so  that  they  revolve  in  unison.  The 
peripheries  of  the  rollers  are  formed  with  spiral  grooves  T T,  around  which  the  direction  of  the  spiral 
of  one  is  in  one  direction,  aud  that  of  the  other  is  in  another  direction,  so  that  as  the  rollers  revolve,  the 
grooves  of  one  always  coincide  with  the  grooves  of  the  other,  and  the  two  together  form  the  extei  ior 
of  the  spiral  tube,  as  is  the  case  with  grooved  rollers  generally.  The  grooves  may  be  of  any  form  so 
as  to  manufacture  the  spiral  or  helical  tubes  of  any  form  of  cross-section  desired.  Motion  is  given  to 
tlie  rollers  by  any  convenient  means.  When  a spiral  tube  is  to  be  formed,  the  tube  is  previously  man- 
ufactured cylindrical,  or  of  other  shape  suitable  for  the  purpose,  and  as  the  rollers  P P revolve,  one  end 
of  the  tube  is  applied  to  the  grooves  in  the  rollers  at  or  near  the  smaller  ends  of  them,  or  the  'everse,  a 


782 


TURN-TABLE. 


catch  being  provided  to  secure  it,  and  as  the  rollers  revolve,  the  tube  will  be  drawn  between  them,  and 
coiled  along  the  spiral  grooves  T T,  thus  forming  the  spiral  tube  required,  and  when  the  tube  has  been 
formed,  the  machinery  is  stopped  and  the  rollers  removed  from  their  bearings,  when  the  spiral  tube 
may  be  drawn  off.  The  rollers  are  then  replaced  in  their  bearings  preparatory  to  another  operation. 
The  rollers  may  be  formed  with  any  required  degree  of  taper,  so  as  to  manufacture  tubes  of  correspond- 
ing forms,  and  the  spiral  grooves  may  be  made  so  as  to  produce  spiral  tubes  either  regular  or  irregular 
in  the  pitch  of  the  spirals,  increasing  or  decreasing,  as  required.  When  it  is  required  to  manufacture 
helical  tubes,  the  patentee  employs  cylindrical  instead  of  taper  rollers,  and  proceeds  as  before  described, 
with  respect  to  spiral  tubes.  By  this  improved  machine  the  patentee  is  enabled  to  manufacture  spiral 
or  helical  tubes,  in  which  the  direction  of  the  spiral  or  helix  shall  be  either  right-handed  or  left-handed. 
This  is  effected  simply  by  causing  the  straight  tube  to  be  coiled  during  the  process,  and  wrapped 
around  either  one  or  the  other  of  the  two  rollers,  the  grooves  of  one  being  right-handed,  and  the  other 
left-handed,  and  therefore  a correspondingly  formed  tube  is  oroduced. 

TUNNELS.  From  an  examination  of  James  Hayward,  Esq.,  C.  E.,  before  a Committee  of  the  Mas- 
sachusetts Legislature. 

Mr.  Hayward  visited  Europe  and  examined  as  many  as  thirty  tunnels.  The  Marseilles  Tunnel  i. 
located  at  Nerthe  near  Marseilles,  is  three  miles  (15,153  feet)  long,  and  has  twenty-four  shafts.  The 
material  in  this  tunnel  is  a very  hard  limestone.  The  height  of  the  ground  over  it  is  a little  over  600 
feet.  The  aggregate  length  of  all  the  shafts  is  7,589  feet ; the  deepest  shaft  is  610  feet.  The  cost  per 
yard  down,  for  excavation,  was  $43.  The  shafts  are  nine  feet  in  diameter,  and  are  lined  with  masonry, 
at  a cost  of  $19  40  per  yard  down. 

The  deepest  shaft  cost  $73  per  yard  down,  entirely  completed.  The  entire  cost  of  all  the  shafts  for 
the  masonry  amounted  to  $47,000  ; and  $150,000  for  the  whole  cost  of  the  tunnel.  The  entire  cost  of 
the  tunnel  for  the  contractor  was  $125  for  the  lineal  yard;  this  includes  shafts.  The  tunnel  was  lined 
with  masonry  of  ditferent  thicknesses,  and  cost  $423,000.  The  entire  cost  of  the  tunnel,  exclusive  of 
masonry,  was  $705,000. 

Woodhead  Tunnel  between  Manchester  and  Sheffield,  is  a little  over  three  miles  long,  and  the  hill 
over  it  600  feet  high.  It  has  five  shafts,  10  feet  in  diameter,  which  vary  from  400  to  600  feet  in  depth. 
The  character  of  theroek  is  granite,  not  so  hard  as  our  granite;  it  is  called  there  “Mill-stone  rock.” 
The  tunnel  was  about  five  years  in  construction,  and  its  whole  cost  was  $1,026,705. 

There  are  various  ways  of  ventilating  the  tunnel  while  the  miners  are  at  work,  and  it  is  easily  done. 
It  was  supposed  that  the  shafts  would  be  necessary  for  ventilation  in  the  Woodhead  Tunnel,  as  the  cars 
passed  through  it,  hut  they  are  now  closed.  Mr.  H.  gave  an  explanation  of  the  various  modes  that  are 
adopted  for  ventilation.  In  the  mines  in  Cornwall,  there  are  excavations  extending  30  miles  under 
ground.  There  are  tunnels  in  the  Duke  of  Bridgewater’s  Canal,  which  make,  in  the  aggregate,  thirty 
miles.  On  the  Thames  and  Medway  Canal,  there  is  a tunnel  about  two  miles  long.  The  shafts  by 
which  it  was  originally  constructed,  except  one  in  the  centre,  are  closed.  The  tunnel  is  used  both  for 
a railway  and  canal,  and  trains  pass  through  it  every  half  hour  daily.  Gen.  Paisley,  the  superintendent 
of  public  works,  passed  nearly  a day  in  the  tunnel,  and  he  says  that  the  smoke  and  steam  from  the 
trains  passed  almost  immediately  away.  There  was  a constant  current  of  air  through  it. 

The  Box  tunnel,  on  the  Great  Western  Bailway,  about  100  miles  from  London,  is  the  largest  and 
most  expensive  tunnel  ever  constructed ; it  is  39  feet  high,  and  over  30  feet  wide.  The  shafts  were  25 
feet  in  diameter,  its  length  is  9579  feet.  Over  one-third  of  it  is  through  the  solid  rock. 

Upingham  Tunnel,  1320  feet  in  length,  cost  £25  per  lineal  yard.  Pulpit  Rock  Tunnel,  Pennsylvania, 
a difficult  tunnel  on  the  Beading  Road,  cost  $66  20  pier  lineal  foot.  Gen.  Barnard  gave  to  Mr.  Baldwin, 
in  answer  to  some  inquiries,  the  cost  of  five  tunnels,  the  highest  of  which  was  $4  36  per  cubic  yard. 

TURBINE.  See  Water  AVheel. 

TURN-TABLE.  A contrivance  on  railroads  by  means  of  which  the  engine  or  cars  may  be  turned 
round.  This  is  effected  by  excavating  a pit  under  a portion  of  the  track,  and  laying  in  the  bottom  of 
this  pit  a circular  track,  upon  which  a platform,  supported  by  friction-wheels,  is  made  to  revolve.  A 
great  many  plans  have  been  devised  to  effect  this  object.  The  following  is  the  method  of  constructing 
the  iron  turning  platform  used  in  England. 

These  tables  are  thus  constructed:  oo,  Fig.  3680,  is  the  surface  of  the  ground  whereon  the  rails  of 
the  railway  are  laid,  a circular  hole  being  dug  of  sufficient  depth  to  receive-the  table  ; around  this,  large 
stone  blocks  a a,  similar  to  the  railway  blocks,  are  placed  ; upon  these  blocks  eight  cast-iron  chairs,  rep- 
resented at  bbb,  &c.,  Fig.  3681,  are  placed,  and  pinned  down;  a circular  ring  of  cast-iron  cc  is  laid 
within  these  chairs,  about  two  inches  and  a half  broad  at  top,  and  a little  bevelled ; this  ring  is  laid 
perfectly  horizontal,  and  upon  it  the  small  bevelled  rollers  gg  g,  &c.,  revolve,  the  arms  1,  2,  3,  4 acting 
as  axles  to  them,  and  around  the  ends  of  which  they  turn  freely.  These  arms  pass  through  a ring  oi 

iron  near  the  extremity,  which  keeps  the  rollers  constantly  in  their  proper  position ; the  arms  are  fast- 

ened in  the  centre  to  a ring  of  irony)  which  turns  freely  round  the  spindle/',  Fig.  3680.  The  turn-table 
rests  upon  these  rollers,  which  are  for  the  purpose  of  causing  it  to  turn  round  as  freely  as  possible. 
Fig.  3682  shows  the  framework  of  the  table ; hhh,  (fee.,  are  the  outer  rim  ; Hi  the  arms  ; and  m n the 
inner  rim,  which  is  of  the  same  diameter  as  the  ring  of  iron  cc  c,  and  which  rests  on,  and  turns  lound 
upon,  the  periphery  of  the  rollers  gg  g-  The  table  is  kept  in  its  place  by  the  vertical  spindle  f fixed 

upon  the  table  at  e,  and  turning  with  it  upon  the  rest  e'. 

The  table,  it  will  therefore  be  seen,  turns  round  this  rest  as  a centre,  and  revolving  upon  the  periph- 
ery of  the  rollers,  it  moves  round  with  very  little  friction.  It  is  not  intended  that  the  spindle  f should 
support  any  part  of  the  weight  of  the  table,  the  use  of  it  being  solely  to  prevent  any  side  motion.  The 
outer  ring  ll  of  the  table  projects  above  the  level  of  the  arms  i i and  the  inner  part  of  the  ring  h'  h' 
Within  this  outer  ring  a platform  of  timber  is  laid,  resting  upon  and  fastened  to  the  arms  kk,  the  bolt 
holes  being  shown  in  the  figure;  upon  this  platform  the  rails  of  the  road  are  placed  -m,  Fig.  368U 


TURN-TABLE. 


783 


stows  the  timber,  the  upper  side  of  which  is  level  with  the  top  of  the  cuter  ring  h h.  A circular  ring 
o o of  cast-iron,  or  of  mason-work,  is  laid  around  the  outer  circle  of  the  table,  upon  which  the  rails  rest, 
and  which  abut  against  the  ends  of  the  rails  laid  upon  the  turn-table. 


We  have  said  that  the  top  of  tl  e turn-table  is  covered  with  timber,  on  which  the  rails  forming  tha 
railway  is  laid ; in  many  cases  the  top  is  formed  of  cast-iron,  the  rails  being  raised  a little  above  the 
surface  of  the  cast-iron  plate. 


3683. 


A very  much  improved  form  of  table  is  that  of  Mr.  Aldrich,  of  Worcester,  Mass.,  which  is  extensively 
used  in  New  England,  sometimes  as  large  as  48  feet  in  diameter.  A plan  and  section  is  shown  in  Figs. 
S6S3  and  3684.  It  will  be  seen  that  in  this  table  the  wheels  are  fixed  to  a framing  independently  of  the 
table ; in  fact,  the  principle  being  the  same  in  many  respects  as  the  one  above  described : the  number  of 


784 


TWISTING  MACHINE  FOR  IRON. 


friction-rollers  is  however  much  greater,  and  on  the  whole  the  arrangement  is  superior  to  the  English 
tables.  This  wheel  is  turned  by  means  of  a pinion  working  into  the  toothed  segment  shown  in  plan 
Fig.  3683.  These  tables  are  of  wood,  and  were  originally  patented.  The  arrangement  is  shown  in  the 
figures  so  clearly  as  to  require  no  further  description.  * 


3084. 


TWISTING  MACHINE  FOR  IRON — Melling’s.  The  great  advantages  of  obtaining  perfect 

homogeneity  of  matter  in  metal  surfaces  over  which  heavy  loads  are  passed,  either  with  an  abrading  or 
rolling  movement,  is  obvious ; and  by  a very  simple  process  a vast  increase  in  permanency  may  be  con- 
ferred upon  articles  of  this  class  as  well  as  upon  various  others,  as  axles,  shafts,  connecting-rods,  and 
piston-rods.  In  shafts,  for  instance,  where  the  mass  is  built  up  out  of  a series  of  bars,  flaws  are  of  fre- 
quent occurrence,  through  imperfect  welds ; and  where  the  weld  is  good,  a deficiency  in  strength  and 
durability  is  generally  the  resulting  effect  of  the  parallelism  of  the  fibre. 

To  overcome  this  practical  mechanical  difficulty,  Mr.  Melling,  of  the  Rainhill  Iron  Works,  Liverpool, 
has  proposed  to  twist  together  the  bundles  of  constituent  bars  which  go  to  form  a shaft,  or  other  forging 
of  large  size,  and  for  this  end  he  has  devised  and  introduced  the  machine  which  forms  the  subject  of 
our  figures.  This  machine  has  now  been  in  operation  for  a considerable  period ; it  is  not,  therefore, 
held  up  simply  as  a novelty,  but  as  a valuable  workshop  accessory. 

Fig.  3685  is  a complete  longitudinal  elevation  of  the  machine  in  working  order,  having  the  front 
heavy  driving  geering  removed  to  avoid  obscuring  the  twisting  details.  In  the  same  view  are  also 
shown  the  carriages  on  which  the  bars  under  treatment  are  conveyed  to  and  from  the  machine. 

Fig.  3686  is  a corresponding  plan,  partly  in  section,  showing  the  driving  geering.  In  this  view  a bar 
is  represented  as  in  the  act  of  passing  through  the  twisting  rollers. 

Fig.  3687  is  an  end  view,  looking  upon  the  delivering  rollers. 


3085. 


Fig.  3688  is  a side  elevation  of  a modification  of  the  delivering  rollers,  differing  slightly  from  the  same 
portion  in  Fig.  3687  in  point  of  regulation  of  the  upper  roller-bearing. 

Fig.  3689  is  a front  elevation  of  the  first  or  revolving  set  of  rollers,  exhibiting  the  actuating  mechan- 
ism whence  the  revolving  movement  round  the  axis  of  the  twisting  bar  is  obtained. 

Figs.  3690,  3691,  8#92,  3693,  3694,  and  3695  represent  various  kinds  of  work,  as  finished  from  the 
original  pile  of  bars. 

The  machine  stands  upon  a massive  foundation  of  masonry,  to  the  surface  of  which  the  cast-iron  bed- 
plate is  b(  Ited.  The  driving  power  is  communicated  to  the  shaft  A,  from  which  motion  is  communi- 
cated through  the  pair  of  wheels  B B to  the  transverse  shaft  C C,  passing  right  across  the  macliine,  and 
having  a heavy  fly-wheel  D at  its  opposite  end.  From  this  shaft  the  first  pair  of  rollers  E E,  from  their 
peculiar  movement  distinguished  as  the  revolving  rollers,  are  worked  by  the  worm  F,  which  geers  with 
the  large  worm-wheel  G,  cast  in  one  piece  with  the  back  of  the  plate  H,  and  bored  out  at  the  back  to 
work  upon  a fixed  carrier  bolted  to  an  upright  bracket  fixed  to  the  back  part  of  the  bed-plate.  The 
shafts  T T carrying  these  rollers  are  supported  in  four  bearings  K K,  fitted  into  a pair  of  transverse 
cheeks  L L,  bolted  and  keyed  between  the  two  plates  H M.  The  latter  is  supported  by  a corresponding 
plate  N,  into  which  is  fitted  a turned  ring  cast  on  the  front  of  the  plate  M,  and  this  Dlate  N is  again 


TWISTING  MACHINE  FOR  IRON. 


735 


bolted  to  flanges  0 0 on  the  upright  cheeks  of  the  delivering  rollers.  It  is  easy  to  see  how  by  this  ar- 
rangement the  revolution  of  the  main  shaft  C communicates  a revolving  movement  to  the  frame-work 
carrying  the  rollers  E E ; but  in  addition  to  this  movement  they  revolve  also  round  their  own  axes,  and 
this  is  obtained  by  means  of  the  t»o  plates  H and  M,  which  carry  round  with  them  two  small  spur- 
pinions  P P,  geering  with  the  fixed  toothed  rim  Q.  This  motion  is  then  transmitted  from  these  pinions 
*o  the  rollers,  through  the  two  worms  R R upon  their  shafts,  to  the  two  worm-wheels  cut  upon  the 
roller-shafts. 


3U80. 


In  the  plan,  Fig.  3686,  the  machine  is  shown  as  thrown  out  of  geer  with  the  driving-shaft,  whilst  a 
a bar  S S is  passing  through.  This  disengagement  is  effected  by  the  two  lever-handles  T T acting  each 
one  upon  a clutch-box,  corresponding  with  similar  clutches  on  the  worms  v and  v,  the  latter  being  that 
through  which  motion  is  communicated  to  the  front  delivering  rollers,  which  latter  may  be  thrown 
in  or  out  of  geer  by  the  attendant,  when  on  .the  opposite  side  of  the  machine,  by  means  of  a short 
handle  at  v. 


3087. 


The  lower  of  the  two  delivering  rollers  W W,  which  simply  revolve  round  their  own  axes,  receiver 
its  motion  from  the  main  shaft,  through  the  worm  geering  with  the  worm-wheel  X on  the  second  trans- 
verse shaft  Y,  carrying  a pinion  Z geering  with  a similar  one  on  the  lower  roller-shaft.  The  object  in 
giving  motion  to  the  lower  roller  first  being  to  admit  of  the  raising  and  lowering  of  the  upper  one  as 
Von.  II. — 50 


786 


TWISTING  MACHINE  FOR  IRON. 


may  be  required  to  suit  the  work,  the  upper  being  driven  from  the  lower  one  by  the  pair  of  pinions  a a 
on  the  opposite  side  of  the  roller-standards  b b.  In  the  combined  views  of  the  machine,  the  pressure 
upon  the  upper  delivering  roller  is  represented  as  obtained  from  the  weight  c,  adjustable  on  the  long 
lever  d having  its  fulcrum  at  e,  and  pressing  upon  the  journals  of  the  upper  roller  by  the  two  spindles  //. 
Crane-power  may  be  applied  to  raise  or  lower  this  weighted  lever,  by  attaching  a chain  to  either  of  the 
two  loops  formed  for  the  purpose,  both  on  the  weight  and  on  the  lever.  In  Fig.  3685  the  office  of  this 
weighted  lever  is  represented  as  supplied  by  a pair  of  adjusting  screws  pressing  upon  the  upper  rcller- 
bearings. 

3088. 


The  bars  to  be  operated  upon  are  brought  from  the  furnace  in  the  carriage  g g,  running  upon  four 
wheel?  on  a tramway.  The  body  of  this  carriage  carries  two  brackets  supporting  a cross-shaft,  on  which 
are  two  pulleys  li  h,  employed  for  the  withdrawal  of  the  bars  from  the  furnace.  The  pulley-shaft  is 
worked  by  a short  winch-handle,  as  in  Fig.  3686,  and  the  ends  of  the  two  chains,  coiled  on  the  pulleys, 
are  attached  to  a box  which  is  slipped  over  the  bar  whilst  in  the  furnace.  Guides  are  attached  to  the 
carriage  at  k k for  the  support  of  the  bar  or  pile  of  bars  to  be  twisted ; and  to  admit  of  their  free  revo- 
lution they  are  turned  on  the  outside  and  fitted  into  the  cast-iron  rings,  bored  to  correspond.  These 


3690. 


3691. 


3692. 


oearmg-nngs  are  put  together  in  halves,  and  are  carried  upon  a pair  of  parallel  longitudinal  rods  con 
nected  with  the  body  of  the  carriage,  or  they  may  be  simply  suspended  from  a crane.  The  carriage  for 
receiving  the  twisted  bar,  as  delivered  from  the  machine,  is  at  l on  the  opposite  or  delivering  end.  It 
is  nothing  more  than  a semicircular  iron  trough,  mounted  upon  a pair  of  wheels,  with  a drawing  handle. 

3694. 


TYPE  FOUNDING, 


787 


The  bar  or  pile  of  bars  being  entered  between  the  revolving  rollers,  and  passed  through  until  the  end 
reaches  the  delivering  pair,  the  upper  one  of  this  latter  pair  is  pressed  hard  down  upon  it,  so  as  to  pre- 
vent it  from  turning.  Being  thus  firmly  held  at  this  end  whilst  the  after  portion  is  carried  round  by 
the  revolvers,  it  is  clear  that  a twist  must  take  place,  an$  so  the  simultaneous  revolutions  of  each  pair 
upon  their  own  axes  carry  forward  the  bar ; it  is  preserved  perfectly  straight,  and  an  even  and  regular 
twist  is  given  to  it.  Fig.  3690  is  the  original  pile  of  rectangular  bars;  fig.  3691  represents  these  bars 
as  twisted  together  previous  to  the  subsequent  finish  under  the  hammer.  In  fig.  3692  the  twisted  metal 
is  shown  under  the  form  of  a double-T  rail.  3693  is  an  axle  formed  out  of  round  bars  twisted  together, 
and  welded  only  at  each  end  for  the  wheels  and  journals  ; and  fig.  369-1  is  a tire-bar  exhibiting  the  stri- 
ated texture,  as  in  fig.  3692.  . . . 

TYPE  FOUNDING.  There  are  two  kinds  of  fonts  which  are  used  respectively  for  book  printing  and 
job  printing,  the  latter  including  such  work  as  hand  and  posting  bills,  etc.  Book  types  include  eleven 
or  twelve  regular  bodies,  from  Great  Primer,  which  is  the  largest,  to  Pi&mond,  which  is  the  smallest 
type  used  for  printing  books.  The  following  are  specimens  of  book  types : 

Great  Primer, 

English, 

Pica, 

Small  Pica, 

Each  of  the  above  fonts  of  type  consist  of  five  alphabets,  viz. : A,  a,  a,  A,  a,  together  -with  many 
other  characters,  about  200  in  all,  and  these  must  all  be  exactly  alike,  except  in  device  and  width.  The 
greatest  width  is  for  the  W and  M,  and  the  least  for  the  i and  ! . 

Every  one  of  these  numerous  characters  requires  for  its  formation  a punch,  a matrix,  a mould,  and 
type  metal  in  a fused  state.  The  punch  is  a piece  of  steel  with  a single  letter  at  one  end.  It  is  formed  by 
hammering  down  the  hollows  and  filing  up  the  edges  of  the  metal  in  a softened  state.  Each  letter  must 
harmonize  with  all  the  others  in  the  font  with  regard  to  height,  breadth  of  stroke  whether  heavy  or  fine. 

The  matrix  is  a small  piece  of  copper  about  1 ^ inch  long,  -j)  inch  deep,  and  wide  in  proportion  to  the 
size  of  the  type  : into  this  the  hardened  punch  is  struck.  This  must  be  managed  with  care,  so  as  to 
allow  the  faces  of  the  types,  when  composed  or  set  up,  to  be  in  a perfect  plane.  Hence  the  depth  of  the 
impression  in  the  matrix  is  of  great  importance,  and  it  is  usual  to  adjust  this  depth  by  filing  down  the 
surface  of  the  copper.  The  matrix  having  thus  received  a sunken  impression  from  the  raised  letter  on 
the  punch,  all  that  is  required  is  to  pour  a quantity  of  fluid  metal  into  the  matrix  in  order  to  reproduce 
the  letter  as  it  is  engraven  on  the  punch.  But  in  addition  to  this  the  cast  letter  will  require  a support, 
or  body,  an  appropriate  width,  and  certain  nicks  or  notches,  which  enable  the  compositor  to  place  the 
letter  in  the  proper  position  in  his  composing-stick  without  having  to  examine  every  letter  by  eye.  The 
measure  of  the  type  with  regard  to  height,  width,  and  body,  is  determined  by  the  type  mould.  The 
mould  is  made  in  two  parts,  so  contrived  that  on  being  put  together,  the  two  halves  form  in  the  centre 
a space  or  mould,  in  which  the  type  is  formed : the  matrix  is  placed  at  the  bottom  of  the  mould,  and  is 
retained  in  its  place  by  a spring.  By  sliding  one  part  upon  the  other,  the  square  cavity  in  the  centre, 
while  retaining  the  same  height,  would  have  its  width  diminished  to  any  extent  required.  The  extent 
to  which  the  two  parts  of  the  mould  slide  upon  each  other  is  determined  by  the  width  of  the  matrix. 
The  metal  is  poured  in  at  the  orifice  formed  by  closing  the  upper  parts. 

These  details  being  understood,  a few  words  will  suffice  to  explain  the  operation  of  casting.  The 
caster  stands  by  the  side  of  a furnace  containing  the  melting-pot  and  the  fused  type-metal  (see  Metals 
akd  Alloys).  He  holds  the  mould  in  his  left  hand,  and  taking  up  a portion  of  the  metal,  in  a very 
small  ladle,  held  in  the  right,  he  pours  a sufficient  quantity  of  it  into  the  mould,  and  immediately  jerks 
it  up  for  the  purpose  of  expelling  the  air  from  the  cavity  and  driving  the  metal  into  the  finest  strokes  of 
the  matrix.  Then,  by  means  of  one  finger,  he  releases  the  spring,  separates  the  mould,  and  hooks  out 
the  letter.  The  small  and  the  large  sizes  require  more  time : the  former,  on  account  of  the  increased 
care,  and  the  latter,  to  allow  the  metal  to  set. 

The  types  are  removed  from  the  caster’s  table  by  a hoy,  who,  seizing  the  type  by  the  edges,  breaks 
or  bends  off  the  superfluous  metal  at  the  bottom  ; lie  then  conveys  them  to  a man  seated  at  a table, 
who,  with  his  finger  protected  by  a piece  of  tarred  leather,  mbs  the  side  of  every  letter  on  a slab  of 
gritty  stone  for  the  purpose  of  removing  knobs  or  globules.  The  letters  are  next  set  up  by  a boy,  in 
lines,  in  a long  stick,  or  shallow  frame,  -with  the  faces  uppermost,  and  the  nicks  outwards.  With  the 
assistance  of  other  frames,  a man  called  the  dresser  polishes  the  types  on  each  edge,  and  turning  them 
with  the  face  downwards,  planes  the  bottom,  and  planes  the  groove  which  brings  the  types  to  the  re- 
quired height,  and  enables  them  to  stand  steadily ; the  letters  are  carefully  inspected  -with  a lens,  and 
the  font  being  proportioned,  i.  e.  the  proper  proportion  of  each  letter,  together  with  the  spaces,  quadrats, 
etc.,  being  counted  out,  each  letter,  Ac.,  is  tied  up  in  lines  of  convenient  length  for  the  printer. 

TYPE  SETTING  MACHINE,  or  COMPOSING  APPARATUS.  For  a series  of  years  it  has  been 
attempted  to  supersede  manual  labor  in  composing  by  machinery.  The  most  successful  thus  far  is  the 
invention  of  William  H.  Mitchel,  of  Brooklyn,  which  has  now  been  for  some  two  or  three  years  in  prac- 
tical operation,  in  John  F.  Trow’s  establishment.  Fig.  3695  represents  a perspective  view  of  the  ma- 
chine : g g are  conductors  placed  in  a range,  and  eacli  conductor  allowed  to  a particular  letter  or  charac- 
ter, and  a range  of  finger  keys  marked  with  corresponding  character  are  so  arranged  that  upon  striking 
one  of  said  keys,  the  bottom  type  in  the  conductor  with  which  it  is  connected,  drops  on  to  a correspond- 
ing endless  belt  m,  of  a series  of  belts  of  successively  increasing  length,  or  speed,  towards  the  deliverin 
or  composing  part  of  the  machine,  which  belt  delivers  the  types  on  to  a diagonal  belt  o,  in'  such 


Fong  .Primer, 

Bourgeois, 

Brevier, 

Minion, 

Noapariel, 

Pent], 


w 03 


788  TYPE  DISTRIBUTING  AND  TYPE  SETTING  MACHINES. 


manner,  that  they  reach  the  composing  wheel  p in  the  order  in  which  the  keys  are  struck.  The  type: 
are  delivered  upon  the  composing  wheel  hv  an  inclined  conductor.  The  composing  wheel  delivers  the  type 
in  an  upright  position  to  the  composing  slide,  from  which  they  are  taken  and  justified  by  the  workman. 


* 


TYPE  DISTRIBUTOR.  Mr.  Mitchel  has  also  invented  a simple  and  efficient  distributing  machine, 
of  which  the  following  is  his  description. 

“ Before  the  types  are  made  use  of  or  composed,  each  letter  of  the  font  is  prepared,  by  cutting  or 
otherwise  forming  (as  the  assorted  letters  are  set  up  in  line)  one  or  more  grooves  or  notches  in  the  body 
of  the  type  at  a certain  distance  or  distances  from  its  bottom  or  lower  end,  each  respective  character 
having  its  notch  or  notches  differently  located  relatively  to  the  lower  end  of  the  body  from  those  of  any 
other  varieties  of  letters  or  types,  and  around  the  edge  of  the  wheel  pins  are  inserted  near  the  bottom 
of  each  groove  therein,  which  pins,  by  the  notches  before  mentioned,  sustain  the  types  in  different  posi- 
tions, according  to  the  position  of  the  notch  or  notches  in  the  types ; hence,  as  said  types  are  carried 
along  on  said  pins,  each  respective  letter  is  dropped  into  a groove  or  receptacle  provided  for  it  when  it 
arrives  opposite  to  said  receptacle,  by  its  lower  end  taking  an  off-set  or  incline,  which  removes  the 
t}rpe  from  its  pin ; or  any  suitable  means  may  be  made  use  of  to  deposit  the  type  in  the  receptacle 
adapted  to  its  peculiar  position  on  the  revolving  wheel ; and  by  a peculiar  arrangement  of  double 
notches,  a very  great  number  of  separate  characters  of  types  may  be  distributed  to  their  respective  re- 
ceptacles by  a very  simple  arrangement  of  inclines  and  off-sets.  The  lines  of  types  in  the  receptacles  or 
grooves  are  successively  pushed  along  to  give  room  for  the  succeeding  types,  and  a stop  motion  is  used, 
by  which  any  misplaced  type  arrests  the  rotation  of  the  machine. 

TYPE  DISTRIBUTING-  MACHINE,  Beaumonts  Patent.  This  machine  is  automatic  and  distributes 
with  perfect  accuracy  every  thing  but  two-em  and  three-em  quadrats,  without  any  attendance  except  to 
supply  the  matter  at  short  intervals.  The  types  are  carefully  picked  apart  and  are  left  standing  in  lines 
suitable  for  a type-setting  machine,  or  tumbled  unceremoniously  into  boxes,  as  may  be  desired,  the  lat- 
ter being  easier  as  requiring  less  labor  and  care  in  their  removal  by  the  attendants.  The  principle  on 
which  the  machine  is  able  to  discriminate  and  put  each  type  in  its  appropriate  place,  is  that  of  feeling, 
not  the  face,  but  the  sides  of  the  body.  Each  type  is  prepared  expressly  for  the  purpose  by  cutting 
three  nicks  on  its  edges,  differently  arranged  for  each  letter.  The  letter  a,  for  example,  is  manufactured 
with  three  nicks,  called  one,  two  and  three,  counting  from  the  highest ; c has  one,  two  and  four ; b has 
two,  three  and  five,  etc.  The  channel  leading  to  each  box  is  provided  with  a mouth  of  the  same  form, 
carefully  executed  in  hardened  steel  to  withstand  the  wear,  and  the  lines  of  type  are  pressed  up  succes- 
sively against  all  these  channels  until  the  right  one  is  presented,  when  the  first  type  in  the  line  pops  in, 
leaving  the  next  to  commence  a similar  round.  The  receiving  channels  are  arranged  in  a circle,  faces 
inward,  and  the  lines  of  type  to  be  distributed  are  ranged  radially  in  a horizontal  wheel  of  somewhat 
less  diameter.  This  wheel  is  properly  geared  and  rolls  around  within  the  enclosure,  presenting  each 
type  rapidly,  but  gently,  to  every  aperture.  The  lines  are  thrust  outward  in  the  wheel  by  suitable 
springs,  which  are  simultaneously  compressed  by  a simple  movement  when  it  is  desired  to  supply  more 
matter.  In  wmrking  out  the  details  of  this  machine  the  most  beautiful  simplicity  has  been  arrived  at, 
and  every  type  is  seized,  on  entering  its  proper  channel,  by  a spring  lever  of  sufficient  force  to  tear  it 
from  its  fellows,  however  adhesive  may  be  its  alkaline  and  inky  bond.  A similar  lever  guards  the  exit 
of  each  type  from  the  wheel,  and  the  hold  is  slackened  only  during  the  instant  it  presses  fairly  against 
the  steel  mouth  of  a channel  for  its  reception.  Thirty  lines  are  received  at  once  in  the  wheel,  and  the 
machine  has  been  for  several  months  in  operation  -without  appearing  to  wear,  or  otherwise  injure  the 
sides  of  the  type.  The  nicks  cause  a slight  annoyance  by  catching  the  rule  in  setting,  but  this  evil  will 
probably  be  overcome  by  practice.  Each  machiue  will  distribute  but  one  size  of  type ; but  the  inven- 
tor states  that  they  may  be  so  constructed  as  to  be  easily  adapted  to  the  different  sizes  of  small  type. 
If  worked  by  hand,  one  man  or  boy  can  distribute  12,000  ems  per  hour,  and  with  scarcely  a possibility 
of  an  error  of  a single  type  ; whereas  by  the  usual  process  of  hand  distribution,  3,000  ems  are  about 
the  average.  The  machines  can  be  worked  by  steam,  and  one  man  can  then  attend  to  three  of  them, 
.making  the  total  distribution  in  one  hour  36,000  ems. 


VALVES,  BALANCED. 


780 


URANIUM.  A metal  discovered  by  Klaproth  in  1789.  The  oxides  of  uranium  are  used  in  painting 
upon  porcelain,  yielding  a fine  orange  color  in  the  enamelling  fire,  and  a black  one  in  that  in  which  the 
porcelain  itself  is  baked.  3096. 

VALVES.  (See  Engines,  Varieties  and  Details  of.) 

Cornell  and  Hosking's  Treble  Beat  Hydraulic  Values. 

A is  the  valve  seat;  B,  the  valve;  CO,  the  passages 
through  the  seat,  and  D D,  passages  through  and  around 
the  valve  ; E is  the  guard  or  stop  to  prevent  the  valve  from 
being  thrown  out  of  its  seat  by  any  sudden  or  unusual  ac- 
tion of  the  engine.  In  fig.  3G96  the  valve  is  shown  in  its 
open  position,  and  the  arrows  indicate  the  course  taken  by 
the  water  in  passing  through  it ; a a,  b b,  c c,  are  the  seats 
or  bearing  surfaces.  The  most  prominent  advantage  of-  L 
fered  by  these  valves,  is  the  larger  opening  for  the  passage 
of  the  water  than  is  afforded  by  the  valves  of  the  forms  hitherto  in  use,  while  at  the  same  time  the  lift 
is  reduced,  and  consequently  the  concussion  very  considerably  lessened. 

VALVES,  BALANCED — Stevens’  Improvements,  1851.  The  patentee’s  object  is  a convenient 
adaptation  to  the  double-acting  steam-engines  of  balanced  valves,  commonly  known  as  the  Cornish 
double-beat  valves.  For  the  balanced  spindle  valve,  as  commonly  constructed,  is  liable  to  two  objec- 


tions : in  the  first  place,  the  valve  being  formed  by  two  disks  connected  by  a spindle,  the  force  of  tho 
steam  acting  against  the  disks  in  opposite  directions  puts  a great  strain  on  the  spindle,  so  that  should 
it  be  slightly  eccentric,  the  valve  will  be  sprung  from  the  seat  and  will  leak ; and  in  the  second  place, 
the  difference  of  expansion  between  the  valve  spindle,  which  is  completely  surrounded  by  steam,  and 


790 


VALVES.  BALANCED. 


the  steam-chests  holding  the  valves,  which  is  on  the  outside,  exposed  to  the  atmosphere,  will  also  cause 
the  valves  to  leak.  The  valves  commonly  known  as  the  Cornish  double-beat  valves  are  obviously 
superior  in  principle  to  the  spindle  valves  just  described,  and  having  been  invented  nearly  a century 
ago,  and  been  in  constant  use  ever  since,  it  may  be  presumed  that  their  general  introduction  in  the 
double-acting  steam-engine,  where  balanced  valves  are  used,  has  been  prevented  or  retarded  by  the 
difficulties  presented  for  their  adaptation  to  that  purpose.  These  difficulties  might  be  of  the  space 
occupied,  or  of  the  expense,  or  of  such  an  adaptation  as  would  alter  but  little  the  arrangements  of  the 
existing  parts  of  the  engine.  The  object  is  to  endeavor  to  arrange  these  valves  in  such  manner  tha* 


869a 


itie  advantages  gained  by  their  superiority  in  principle  may  not  be  so  counterbalanced  by  the  difficulties 
above  named,  as  to  prevent  their  general  introduction.  To  effect  this,  the  valves  are  arranged  on  the 
lame  level,  as  this  is  the  arrangement  most  generally  adopted  in  engines  having  balanced  valves  ; and 
for  the  same  purpose  certain  peculiarities  are  introduced  in  the  construction  of  the  valve,  that  render  it 
different  from  any  hitherto  in  use. 

Fig.  3698  represents  a side  view  of  one  of  each  of  the  steam  and  exhaust  valves  ; the  steam-valve 
being  the  Cornish  valve,  and  the  exhaust-valve  having  Stevens’  improvement. 

Fig.  3699  represents  a vertical  section  of  the  same  valves  both  raised  off  their  seats,  which  are  alse 
shown  in  section. 

Fig,  3700  represents  a horizontal  view  of  the  same  valves. 


VALVES,  BALANCED. 


791 


Fig  3C97  represents  a vertical  section  of  the  side-pipes,  steam-chests,  valves,  and  valve-seats. 

Fig.  3701  represents  a horizontal  cross-section  of  the  lower  steam-chest  valves  and  valve-seats,  taken 
through  the  dotted  line  xx  of  Fig.  3697. 

Fig.  3702  represents  a horizontal  view  of  the  lower  steam-chest. 

Fig.  3703  represents  a vertical  section  of  the  side-pipes,  taken  through  the  dotted  line  yy  of  Fig.  4082 

In  the  drawings,  a is  the  lower  steam-chest;  b is  the  upper  steam-chest,;  c and  c are  the  side-pipes, 
leading  respectively  to  the  boiler  and  condenser ; d and  d are  the  openings  from  the  side-pipes  into  the 
cylinder  nozzles;  e is  the  opening  into  the  condenser. 

h h represents  the  two  steam-valves,  differing  but  little,  if  any,  from  the  Cornish  valve  ; m and  m 
represents  the  two  exhaust-valves,  showing  the  alterations  made  to  adapt  them  to  the  position  in  which 
they  are  placed  relatively  to  the  steam-passages.  In  the  first  place  we  will  describe  the  different  parts 
of  the  Cornish  valve. 

/and/ are  respectively  the  lower  and  upper  seats,  the  upper  seat  being  formed  on  the  circumference 
of  a disk  supported  by  a cross ; g g,  cast  in  the  centre  of  the  ring,  forming  the  lower  seat;  the  valve  h 
is  formed  by  a hollow  cylinder,  the  lower  part  of  which  being  turned  in,  as  shown,  forms  the  valve- 
face  i ; that  rests  on  the  seat  / and  the  upper  part  also  turned  in,  forms  the  valve-face  i ; that  rests  on 
the  seat/;  k k are  ribs  cast  on  the  inside  of  the  valve  to  guide  it ; l is  a cross  by  which  the  valve  is 
lifted  by  the  valve-stem. 


The  steam-valve  h,  thus  drawn  and  described,  does  not  differ  materially,  if  in  any  respect,  from  a 
Cornish  double-beat  valve ; and  we  have  been  thus  particular  in  describing  it  in  order  to  explain  the 
manner  in  which  to  alter  it,  the  alteration  constituting  the  material  part  of  the  invention. 

It  will  be  observed  by  a reference  to  the  drawings  that  the  position  of  the  exhaust-valve  with  respect 
to  the  steam-passages,  and  also  with  regard  to  the  direction  in  which  it  is  opened,  is  such  that  if  it  were 
made  similar  to  the  valve  just  described,  the  pressure  of  the  steam  would  force  it  from  its  seat.  It  is 
necessary,  therefore,  in  order  that  the  valve  shall  be  retained  on  its  seat  by  the  pressure  of  the  steam, 
that  the  seat  formed  on  the  disk  supported  by  the  ribs  shall  be  larger  in  diameter  than  the  seat  that 
forms  the  circular  opening  through  which  the  steam  passes.  In  order  to  effect  this,  a ring  is  attached 
to  the  valve,  forming  the  bearing  for  the  smaller  seat,  this  ring  being  smaller  in  diameter  than  the  disk  ; 
there  is  also  a ring  attached  to  this  disk,  forming  the  larger  seat.  We  are  thus  enabled  to  put  the  valve 
together  by  slipping  the  smaller  ring  over  the  disk,  and  then  by  attaching  the  larger  ring  to  the  disk, 
and  finally  by  slipping  the  valve  over  the  disk  and  attaching  it  to  the  smaller  ring. 

The  faces  of  this  valve  having  respectively  the  smaller  and  larger  diameter  are  represented  respect- 
ively by  n and  n,  resting  on  the  seats  o and  o' ; p is  the  disk  supported  by  the  cross  q.  The  valve  is 
formed  in  two  pieces  by  bolting  it  to  the  ring  r,  on  the  edge  of  which  the  smaller  valve-face  n is  shown  ; 
the  disk  is  also  formed  into  two  pieces,  by  bolting  to  the  disk  p the  ring  s,  on  the  edge  of  which  the 
larger  valve-seat  o'  is  shown.  To  put  the  valve  in  its  place,  the  ring  r must  be  slipped  over  the  disk  p. 
then  the  ring  s must  be  bolted  to  the  disk  p,  and  finally  the  remainder  of  the  valve  must  be  slipped 
over  the  disk  p and  ring  s,  and  bolted  to  the  ring  r ; u is  a cross  by  which  the  valve  is  lifted  by  the 
valve-stem,  1 1 are  ribs  to  guide  the  valve.  From  the  position  in  which  this  valve  m is  shown  in  refer- 
ence to  the  steam-passages,  it  will  be  seen  that  when  the  valve  is  closed  the  pressure  of  steam  will  be 
below  the  valve,  and  the  vacuum  will  be  above  the  valve ; it  will  also  be  seen  from  the  construction  ol 
the  valve  that  it  will  be  held  down  on  its  seat  by  the  pressure  of  the  steam  acting  from  below. 

VELOCIMETER.  An  apparatus  for  measuring  the  rate  of  speed  of  machinery.  When  the  velocity 
is  unifonn,  the  instrument  is  merely  a measurer  of  distance  ; but  this  is  not  the  case  with  a variable 
velocity,  which  requires  a much  more  elaborate  contrivance  for  its  estimation.  Such  a velocity  meas- 
urer was  constructed  by  Breguet,  of  Paris,  under  the  direction  of  M.  Morin,  the  principle  of  which  may- 
be briefly  explained  as  follows : A circular  disc,  covered  with  card  or  paper,  is  made  to  revolve  with  an 
uniform  motion  by  means  of  clock-work,  regulated  by  air-vanes : upon  this  disc  a revolving  pencil, 
whose  motion  is  caused  by  and  corresponds  with  that  of  the  body  whose  vai-iable  velocity  is  to  be  meas- 
ured, describes  a curved  line  ; and  from  this  curve,  which  results  from  a combination  of  the  variable 
with  the  uniform  motion,  the  velocity  may  be  easily  ascertained  by  processes  and  formulae  adapted  to 
the  purpose. 

VELOCITY,  VIRTUAL.  Virtual  velocity,  in  mechanics,  is  the  velocity  which  a body  in  equilibrium 
would  actually  acquire  during  the  first  instant  of  its  motion  in  case  of  the  equilibrium  being  disturbed. 

The  general  principles  on  which  the  laws  of  equilibrium  in  machines  are  established  may  be  reduced 
to  three  ; namely,  the  principle  of  the  lever,  the  principle  of  the  composition  of  forces,  and  the  principle 
of  virtual  velocities.  The  last  consists  in  this,  that  forces  are  in  equilibrium  when  they  are  in  the  inverse 
ratio  of  the  virtual  velocities  of  the  points  to  which  they  are  applied,  estimated  in  the  direction  ip  which 


792 


VERNIER, 


they  respectively  act.  Thus,  let  F and  F'  be  two  forces  applied  to  the  points  p and  p'  of  a body  which 
is  in  equilibrium  between  their  joint  actions,  and  let  s and  s'  be  the  spaces  which  the  points  p and  p1 
would  describe  in  the  first  instant  of  time,  in  case  of  the  equilibrium  being  disturbed  ; then  F : F' : : s' : », 
or  Fs  = F' s'.  The  principle  is  thus  enunciated  generally  by  Lagrange,  ( Mcc . Analytique,  p.  22  :) 

“ If  any  system  of  bodies  or  material  points,  urged  each  by  any  forces  whatever,  be  in  equilibrium, 
and  there  be  given  to  the  system  any  small  motion,  by  virtue  of  which  each  point  describes  an  infinitely 
small  space,  which  space  will  represent  the  virtual  velocity  of  the  point;  then  the  sum  of  the  forces, 
multiplied  each  by  the  space  wrhich  the  point  to  which  it  is  applied  describes  in  the  direction  of  that 
force,  will  be  always  equal  to  zero  or  nothing,  regarding  as  positive  the  small  spaces  described  in  the 
direction  of  the  forces,  and  as  negative  those  described  in  the  opposite  direction.” 

In  order  to  illustrate  this  principle  we  may  take  as  an  example  the  case  of  the  bent  lever,  Fig.  3700. 
Let  P P'  P"  be  the  points  of  application  of  the  three  forces  F F'  F",  acting  on  the  lever  B A C,  in  the 
directions  P Q,  P'  Q',  P"  Q",  which  are  all  supposed  to  be  comprised  in  the  same  plane.  Suppose  the 
lever  to  describe  an  infinitely  small  angle  about  the  fulcrum 
A,  so  that  the  points  P P'  P"  come  into  the  positions  pp'  p". 

According  to  the  definition  given  above,  the  infinitely  small 
arcs  P p,  P'  pi',  P " p",  which  may  be  considered  as  straight 
lines,  will  be  the  virtual  velocities  of  the  points  of  applica- 
tion P P'  P",  of  the  three  forces  F F'  F".  From  the  points 
pp' p”  let  there  be  drawn  p m,  p'  m‘,  p"  in",  respectively 
perpendicular  to  the  lines  P Q,  P'  Q',  P"  Q"  ; then  P m will 
be  the  virtual  velocity  of  the  point  P reduced  to  the  direc- 
tion P Q of  the  force  F,  and  P'  m\  P"  m"  will  in  like  man- 
ner represent  the  virtual  velocities  of  the  points  P'  and  P" 
reduced  to  the  directions  in  which  the  forces  F'  and  F"  respectively  act.  Let  P m = s,  I"  in'  = s',  and 
P"  in"  — s"  ; and  as  the  force  F acting  in  the  direction  P Q tends  to  turn  the  lever  in  the  direction  in 
which  the  motion  has  been  supposed  to  take  place,  while  F'  and  F"  tend  to  turn  it  in  the  contrary  di- 
rection, the  space  s must  be  regarded  as  positive,  and  s'  and  s"  as  negative. 

Now,  according  to  the  principle  of  virtual  velocities  the  sum  of  the  given  forces,  each  multiplied  by 
the  velocity  of  its  point  of  application  reduced  to  the  direction  of  that  force,  is  zero  in  the  case  of  equili- 
brium ; and,  reciprocally,  when  this  sum  is  zero  the  system  is  in  equilibrium ; hence  the  equation  of  the 
equilibrium  of  the  lever  is 

F s F'  s'  + F"  s"  — 0. 

It  is  easy  to  verify  this  equation  by  showing  that  it  may  be  derived  from  the  equation  of  equilibrium 
deduced  from  the  principle  of  the  lever.  From  A let  A q,  A q‘,  A q",  be  drawn  respectively  perpen- 
dicular to  the  directions  P Q,  P'  Q',  P"  Q",  and  let  the  angle  P A p = 8 ; then,  since  the  angle  A Pp 
may  be  regarded  as  a right  angle,  m P p = P A q ; whence  the  two  triangles  m Pp,  q A P,  are  similar, 
arid  m P : A q : : Pp  : P A : : tan.  8 : 1 ; therefore  m P = A q tan.  6,  that  is,  s — A q tan.  $.  In  like  man- 
ner we  have  s'  — A q’  tan.  6,  s'  — A q"  tan.  8 ; whence,  by  substituting  in  the  above  equation,  and  leav- 
ing out  the  common  multiplier  tan.  8,  w^e  find 

F • A q -|-  F1  • A q'  + F"  • A q"  = 0, 
which  is  the  well-known  equation  of  equilibrium. 

The  equation  F s -f-  F'  s'  -f-  F"  s"  = 0 may  be  extended  to  a solid  body  of  any  form,  or  to  any  machine 
whatever.  Let  dm  be  an  element  of  the  body,  F an  accelerating  force  applied  to  dm,  v the  velocity  of 
that  element,  z the  angle  comprised  between  the  direction  of  the  force  F and  that  in  which  the  element 
d in  moves  ; then  the  moving  force  of  the  element  will  be  F dm,  and  v cos.  z,  its  velocity  estimated  in 
the  direction  of  this  force  ; and  consequently,  by  the  principle  of  virtual  velocities,  the  equation  of  equi- 
librium will  be J' F v cos. zdm  — 0. 

The  principle  of  virtual  velocities  is  easily  verified  by  experiment  with  respect  to  all  the  simple  ma- 
chines; namely,  the  lever,  the  pulley,  the  w'heel  and  axle,  the  inclined  plane,  and  the  screw.  Its  im- 
portance as  a fundamental  principle  in  rational  mechanics  was  first  recognized  by  John  Bernoulli,  (see 
the  Nouvelle  Mecanique  of  Varignon,  tom.  ii. ;)  and  Lagrange  has  derived  from  it  the  whole  theories  of 
statics  and  dynamics  in  his  celebrated  work,  the  Mecanique  Analytique.  Fourier  ( Journal  de  V Ecole 
Polytechnique,  cahier  v.)  has  demonstrated  the  principle  from  the  property  of  the  lever. 

VENTILATION.  See  Warming. 

VERNIER.  A contrivance  for  measuring  intervals  between  the  divisions  of  graduated  scales  or  cir- 
cular instruments.  The  name  is  given  from  that  of  the  inventor,  Peter  Vernier,  who  published  an 
account  of  the  contrivance  in  a work  printed  at  Brussels  in  1631.  It  consists  of  a small  movable  scale, 
which  slides  along  the  graduated  scale ; the  divisions  on  the  one  scale  beiifg  to  those  on  the  other  .u 
the  proportion  of  two  numbers  which  differ  from  each  other  by  unity.  The  theory  of  the  instrument, 
and  the  manner  in  which  it  is  used,  may  be  explained  as  follows : 


3700. 


B | 

1 A 

2 1 | 

987654321 

9 8 

?.’l  i ! i \ I I I I I I ir 
10  9876543210 


Let  AE  = (i  be  a distance  on  tlie  scale  containing  n of  its  divisions.  Let  vv  be  another  scale  equa. 
in  length  to  n — 1 of  the  divisions  oil  AB;  and  let  v v be  divided  into  n equal  parts.  Since  the  distance 


VERNIER. 


793 


A B — o,  and  contains  n equal  parts,  each  division  on  the  scale  — — . Hence  the  length  of  the  vetniet 

vv=-a  — — ; and,  as  it  is  divided  into  n equal  parts,  each  division  on  the  vernier  = — («-I) 

= — — — „ ; and  therefore  the  difference  between  a division  on  the  scale  and  one  on  the  vernier  . 

n n n 

Suppose  the  zero  of  the  vernier  to  coincide  with  the  division  marked  A on  the  scale ; then  the  first  di- 
vision on  the  vernier  will  not  coincide  with  the  first  after  A on  the  scale,  but  fall  behind  it  by  a quantity 

equal  to  their  difference,  or  equal  to  In  like  manner,  the  next  line  on  the  vernier  will  fall  behind 


the  next  on  the  scale  by  a quantity  equal  to  twice  the  difference  of  the  divisions,  or  equal  to  ■ 


The 


3 a 


third  on  the  vernier  will  fall  behind  the  third  on  the  scale  by  — ; and  so  on  to  the  nth  division  on  the 


vernier,  which  will  fall  behind  the  nth  on  the  scale  by  — - — — , that  is,  by  a whole  division ; and  there- 

J n2  n J 

fore  the  nth  on  the  vernier  coincides  with  the  division  n — 1 on  the  scale.  Conceive  the  scale  to  be  a 

scale  of  inches,  and  suppose  it  divided  into  tenths ; then  a = 1 inch,  n — 10,  — — -L  of  an  in.,  and  (the 

• n 1 u n 

difference  between  a division  on  the  scale  and  on  the  vernier)  = TiF ; so  that  the  yi^th  of  an  inch  is 
exhibited  on  the  scale,  though  its  divisions  are  only  to  tenths. 

The  vernier  is  connected  with  the  scale  in  such  a way  that  it  can  be  moved  along  it  by  means  of  a 
rack  and  pinion,  or  a tangent-screw,  or  some  similar  contrivance,  and  its  zero  be  brought  to  coincide  with 
any  point  on  the  scale.  If,  when  the  vernier  is  thus  adjusted,  its  zero  coincides  exactly  with  a division 
on  the  scale,  the  measure  is  read  off  at  once ; but  if  (as  must  generally  happen,  the  zero  falls  between 
two  of  the  divisions  on  the  scale,  then  some  one  of  the  lines  on  the  vernier  will  coincide,  or  very  nearly 
coincide,  with  one  of  the  divisions  on  the  scale,  and  the  distance  of  the  zero  beyond  the  last  division  on 
the  scale  behind  it  is  expressed  in  hundredths  by  the  number  of  the  division  on  the  vernier  which  is  co- 
incident with  a division  on  the  scale.  Suppose,  for  example,  the  position  of  the  vernier  with  respect  to 
the  scale  be  as  represented  in  Fig.  3701 , where  the  zero  of  the  vernier  is  brought  to  coincide  with  a cer  • 


1234501891  123 

rm  p\  s i tt  imi 

i i r i r i i r i . i 

0 123456789  10 


□J 


tain  point  p on  the  scale.  The  poiptp  is  read  on  the  scale  29  inches,  2-10ths,  and  a fraction,  which  is 
to  be  measured  by  the  vernier.  Here  the  division  6 on  the  vernier  coincides  with  that  which  is  marked 
7 on  the  scale ; therefore  the  distance  of  the  zero  of  the  vernier  from  the  last  division  (2)  behind  it  on 
the  scale  is  5-lOOths  of  an  inch;  for  as  5 on  the  vernier  coincides  with  7 on  the  scale,  the  distance  of  4 
from  6 is  l-100ths  ; of  3 from  5,  2-100ths ; of  2 from  4,  3-100ths ; of  1 from  3,  4-100ths  ; and  of  0 from  2, 
5-100ths.  In  like  manner,  if  the  vernier  were  pushed  along  till  the  division  8 coincided  with  30  inches 
on  the  scale,  then  the  reading  of  the  zero  point  would  be  29  inches,  2-10ths,  and  8-100ths.  If,  when  the 
zero  is  brought  to  coincide  with  p,  none  of  the  divisions  on  the  vernier  coincide  exactly  with  a division 
on  the  scale ; for  example,  if  the  5 on  the  vernier  should  be  a little  past  the  7 on  the  scale,  and  the  6 not 
up  to  the  8,  the  reading  would  be  between  5-100ths  and  6-100ths ; but  its  precise  amount  could  only  be 
stated  by  estimation.  If  the  line  5 appeared  nearer  7 than  6 to  8 lie  distance  measured  would  be 
greater  than  5-100ths,  or  10-200ths,  but  less  than  ll-200ths ; and  if  the  line  6 appeared  nearer  to  8 than 
5 to  7,  the  distance  would  be  greater  than  ll-200ths,  but  less  than  12-200ths,  or  6-100ths.  Thus  in  any 
case  the  limits  of  the  uncertainty  must  be  confined  within  a distance  = l-200ths  of  an  inch.  In  order  that 
the  coincidences  may  be  observed  with  greater  certainty,  the  divisions  are  generally  read  with  a lens. 

The  vernier  is  equally  applicable  to  circular  scales  as  astronomical  circles ; it  is  then  circular  also, 
and  must  move  concentric  with  the  limb  of  the  circle.  Suppose  the  limb  divided  into  intervals  of  10' ; 
and  let  n = 10.  We  have  then  10  divisions  on  the  limb  = 100,=a;  and  the  length  of  the  vernier 

— -^  = 100' — 10'  = 90';  which,  divided  into  10  equal  parts,  gives  9'  for  the  length  of  a divi- 
sion on  the  vernier,  and  consequently  the  difference  of  the  length  of  a division  on  the  scale  and  on  the 
vernier  =1'.  The  arc,  therefore,  can  be  read  to  minutes.  But  the  reading  may  be  carried  to  much 
more  minute  quantities  by  increasing  the  length  and  the  number  of  divisions  on  the  vernier.  Instead  of 
embracing  9 intervals  of  10'  on  the  scale,  let  the  vernier  embrace  59  such  intervals,  and  be  divided  into 

60  equal  parts.  We  have  then  a = 10'  X 60  = 600',  n = 60,  n 2 = 3600  ; therefore,  - = — — - — --  = 

’ ’ n2  3600  6 

10";  that  is  to  say,  the  arc  may  be  read  to  10". 

In  barometers,  where  a considerable  degree  of  accuracy  is  required,  the  inch  is  divided  into  20  equal 
parts ; the  vernier  is  made  equal  in  length  to  24  of  these,  and  divided  into  25  equal  parts.  In  this  case 


25 

we  have  a — — = T25  inch,  n — 25  ; 
20 

ing  to  l-500th  of  an  inch. 


therefore 


a 
n 1 


1-25 

= 0’002 ; so  that  the  vernier  gives  the  read 

625 


794 


WARMING  AND  VENTILATION. 


Instead  of  making  the  vernier  equal  to  n — 1 divisions  of  the  scale,  it  is  sometimes  made  equal  tc 
n ~f-  1 divisions,  and  the  object  will  still  be  accomplished  in  precisely  the  same  manner.  For  in  this 

case  the  length  of  a division  on  the  scale  being  as  before,  — , and  that  of  a division  on  the  vernier  - 

n n 

(a-\ — } = — 4-— „,  the  difference  is  still  The  principle  is  the  same  in  both  cases. 
nr  n ra2  n2  1 

The  vernier  is  often  called  a nonius,  but  improperly,  the  contrivance  invented  by  Nonius  or  Nunnez 
being  on  a quite  different  principle. 

VICE,  LEVER.  This  is  an  engraving  of  a vice  invented  by  Mr.  J.  Peck,  and  improved  by  Mr.  L. 
Pardee,  of  New  Haven,  Conn.  It  possesses  great  strength  and  great  power.  It  is  made  of  wrought- 
iron,  and  is  claimed  to  have  better  qualities  than  any  now  in  use.  It  is  w'orked  entirely  by  the  foot 
without  laying  down  a tool  for  that  purpose,  and  it  can  be  changed  to  receive  work  from  l-16th  to  8 or 
10  inches  in  width,  as  quickly  as  any  other  vice  can  be  moved  one-fourth  of  an  inch. 

3702. 


Description. — at  Fig.  3102,  sliding-jaw;  b,  jointed  or  swing  jaw;  c,  rail  on  which  the  sliding-jaw 
moves ; d,  click  which  catches  in  ratchet  on  rail  c,  and  holds  the  sliding-jaw  firmly  where  placed.  E 
jointed  lever  (elbow-joint)  w'hicli  turns  on  pins  ee,  and  is  attached  to  prong  of  rail  c and  the  lower  end 
of  the  swinging-jaw.  g,  foot-lever  w7ith  joint  attached  to  leg  of  bench,  and  connected  by  rod  i with 
jointed  lever,  h,  click  which  catches  in  ratchet  at  the  foot  of  the  forward  bench-leg,  and  holds  the  jaws 
firmly  as  forced  up  by  the  combined  levers ; it  is  easily  tripped  with  the  foot.  / is  a spiral  spring  which 
lifts  the  foot-lever  and  throws  open  the  jaw. 

It  will  be  recollected  that  when  this  vice  is  forced  up  it  becomes  very  firmly  attached  to  the  bench, 
and  very  solid  for  chipping  and  other  heavy  work  that  is  required  to  be  put  into  a vice,  and  heavy  work 
requiring  both  hands  to  lift  can  be  very  easily  placed  in  it.  It  is  certainly  much  easier  for  the  mechanic, 
for  the  strain  upon  the  breast  in  turning  the  screw  is  avoided.  This  vice  has  been  tested  and  found  to 
be  a useful  invention,  and  one  of  them  weighing  fifty  pounds  has  been  found  to  possess  as  much  power 
as  an  English  vice  weighing  seventy  pounds. 


WARMING  AND  VENTILATION.  Heat  is  given  off  from  bodies  by  two  distinct  processes — ra- 
diation and  conduction.  In  radiation,  rays  of  heat  diverge  in  straight  lines  from  every  part  of  a heated 
surface,  and  also  from  extremely  minute  depths  below  such  surface.  These  rays,  like  rays  of  light,  are 
subject  to  the  laws  of  refraction  and  reflection,  and  their  intensity  decreases  as  the  square  of  the  distance. 
When  we  approach  an  open  fire,  or  the  surface  of  a stove,  we  feel  its  heat  by  radiation,  and  it  has  been 
ascertained  that,  at  the  ordinary  temperature  of  hot-water  pipes,  about  one-fourth  of  the  total  cooling 
effect  is  due  to  radiation. 

But  the  amount  of  radiation  of  a body  heated  above  the  temperature  of  he  surrounding  atmosphere 
depends  greatly  upon  the  nature  of  its  surface.  If  a vessel  of  hot  water,  coated  with  lamp-black,  radiate 
100  parts  of  heat  within  a given  time,  a similar  vessel,  containing  water  of  the  same  temperature,  coated 
with  writing-paper,  will  radiate  98  parts  of  heat ; resin,  96  ; China  ink,  88 ; red  lead,  or  isinglass,  80 ; 
plumbago,  15;  tarnished  lead,  45;  tin,  scratched  wfith  sand-paper,  22;  mercury,  20;  clean  lead,  19; 
polished  iron,  15  ; tin-plate,  12. 

In  order  to  ascertain  the  velocity  of  cooling  from  a surface  of  a cast-iron  pipe  30  inches  long,  21 
inches  diameter  internally,  and  3 inches  diameter  externally,  the  rates  of  cooling  were  tried  with  differ- 
ent states  of  the  surface  : first,  when  covered  with  the  usual  brown  surface  of  protoxide  of  iron  ; next  it 
was  varnished  black,  and  finally  the  varnish  was  scraped  off,  and  the  pipe  painted  white  with  two  coats 
of  lead  paint.  The  ratios  of  coding  1°  were  found  to  be  for  the  black  varnished  surface  1'21  minutes- 


WARMING  AND  VENTILATION. 


79; 


for  the  iron  surface,  l'2o  minutes,  and  for  the  white  painted  surface,  T28  minutes.  “ These  ratios  are  in 
the  proportion  of  100,  103-3,  and  105’7  ; but,  as  the  relative  heating  effect  is  the  inverse  of  the  time  of 
cooling,  we  shall  find  that  100  feet  of  varnished  pipe,  1031  feet  of  plain  iron  pipe,  or  105J  feet  of  iron 
pipe,  painted  white,  will  each  produce  an  equal  effect.” 

Tarnished  surfaces,  or  such  as  are  roughened  by  emery,  by  the  file,  or  by  drawing  streaks  or  lines 
with  a graving  tool,  have  their  radiating  power  considerably  increased.  But,  according  to  Melloni,  the 
roughness  of  the  surface  merely  acts  by  altering  the  superficial  density  which  varies  according  as  the 
body  is  of  a greater  or  less  density,  previous  to  the  alteration  of  its  surface  by  roughening.  The  follow- 
ing experiment  gives  the  data  for  this  conclusion  : Melloni  took  four  plates  of.  silver,  two  of  which,  when 
cast,  were  left  in  their  natural  state,  without  hammering,  and  the  other  two  were  planished  to  a high 
degree  under  the  hammer.  All  four  plates  were  then  finely  polished  with  pumice-stone  and  charcoal, 
and  after  this  one  of  each  of  the  pairs  of  plates  was  roughened  by  rubbing  with  coarse  emery  paper  in 
one  direction.  The  quantity  of  heat  radiated  from  these  plates  was  as  follows : 

Hammered  and  polished  plate  10°  I Cast  and  polished  plate  13*T° 

Hammered  and  roughened  plate  18°  | Cast  and  roughened  plate  1T3° 

Thus  it  appears  that  the  hard  hammered  plate  was  increased  in  radiating  power  four-fifths  by  roughen- 
ing its  surface,  while  the  soft  cast  plate  lost  nearly  one-fifth  of  its  power  by  the  same  process. 

When  a body  is  exposed  to  a source  of  heat,  a portion  of  it  is  absorbed,  and  it  has  been  proved,  ex 
perimentally,  that  the  absorptive  power  of  bodies  for  heat  is  precisely  equal  to  their  radiative  power. 
It  was  long  supposed  that  color  had  great  influence  on  radiation  and  absorption.  By  exposing  variously 
colored  surfaces  to  the  heat  of  the  sun,  their  absorbing  power  was  in  the  following  order : black,  blue, 
green,  red,  yellow,  and  white.  Hence  it  would  naturally  be  expected  that  the  radiating  powers  of  dif- 
ferently colored  bodies  would  be  in  this  order,  and  that  by  painting  a body  of  a dark  color  we  should 
increase  its  radiating  power.  Such,  however,  is  not  the  case,  for  the  absorption  and  radiation  of  simpli 
heat , or  heat  without  light,  depend  on  the  nature  of  the  surface  rather  than  on  color. 

The  numbers  which  represent  the  radiating  powers  of  different  bodies  for  invisible  or  non-luminous 
heat,  or  heat  of  low  temperature,  evidently  bear  no  relation  to  color,  for  lamp-black  and  writing-paper 
are  nearly  equal ; Indian  ink  is  much  less,  and  plumbago  still  less.  A thermometer  bulb,  coated  with 
a paste  of  chalk,  is  affected  by  invisible  heat  even  more  than  a similar  one  coated  with  Indian  ink ; but, 
this  result  does  not  occur  when  the  heat  is  from  a luminous  source.  Thus  it  was  found  that  when  two 
spirit  thermometers,  one  containing  colored,  and  the  other  colorless  alcohol,  were  exposed  to  the  sun, 
the  colorwl  liquid  rose  much  more  rapidly  than  the  colorless,  but  when  they  were  both  plunged  into  a 
vessel  containing  hot  water,  they  rose  equally  in  equal  times. 

The  propagation  of  heat  by  conduction  is  a very  different  process  from  that  of  radiation.  By  conduc- 
tion, the  heat  travels  through  or  among  the  particles  of  solid  matter,  until  the  temperature  of  the  body 
in  contact  with  the  source  of  heat  is  raised  more  or  less  above  the  temperature  of  the  air.  When  heat, 
is  communicated  to  a fluid  body,  the  process  is  different.  In  consequence  of  the  great  mobility  of  its 
particles,  those  which  first  come  under  the  action  of  the  source  of  heat,  being  raised  in  temperature,  es- 
cape from  its  influence,  and  ascend  through  the  fluid  mass,  distributing  a portion  of  their  acquired  heat 
among  other  particles  on  its  way ; other  particles  immediately  take  its  place,  and  being  heated,  ascend 
in  like  manner  and  distribute  their  heat.  By  this  process  of  convection,  as  it  is  called,  the  whole  of  the 
particles  in  a confined  mass  of  fluid  come  under  the  action  of  the  heating  body ; those  first  heated  es- 
cape as  far  as  possible  from  the  source  cf  heat,  and  becoming  cooled,  descend  again  to  be  heated,  and 
again  to  ascend  and  descend.  In  this  w'ay  a circulation  is  maintained  in  the  whole  mass  of  fluid. 

It  is  only  by  this  process  of  convection  that  air  may  be  said  to  be  a conducting  body,  for  if  a mass  of 
air  be  confined  in  such  a way  as  to  prevent  the  free  motion  of  its  particles,  it  ceases  almost  entirely  to 
conduct  heat,  and  may  be  usefully  employed  to  retain  heat ; as  in  the  case  of  double  windows,  the 
inclosed  mass  of  air  prevents  the  heat  from  escaping  from  the  apartment,  and  shields  the  glass  which  is 
in  contact  with  the  warm  air  of  the  room  from  the  cooling  action  of  the  external  air.  According  to  some 
experiments  each  square  foot  of  glass  will  cool  1 ‘27 9 cubic  feet  of  air  1°  per  minute,  when  the  temper- 
ature of  the  glass  is  1°  above  that  of  the  external  air.  This,  however,  is  in  a still  atmosphere.  Glass 
is  a very  bad  conductor  of  heat,  and  the  cooling  effect  of  wind  upon  it  is  not  so  great  as  is  generally 
supposed. 

Solids  differ  greatly  in  their  heat-conducting  powers.  If  gold  conduct  100  parts  of  heat,  platina  will 
conduct  98T0  parts;  silver,  97‘30;  copper,  89'82;  iron,  3743;  zinc,  36'30  ; tin,  30‘39  ; lead,  17'96; 
marble,  23'60  ; porcelain,  1‘2'20  ; fire-brick,  1T40.  The  slow  conducting  power  of  such  bodies  as  porce- 
lain, brick,  and  glass,  may  be  contrasted  with  the  rapid  conducting  power  of  some  of  the  metals  by 
holding  one  end  of  a piece  of  each  substance  in  a flame ; the  metal  will  soon  become  too  hot  for  the 
hand,  while  the  porcelain  may  be  heated  to  redness  in  the  flame  without  its  being  felt  to  be  much 
warmer  at  the  other  end.  A joractical  application  of  this  property  is  also  to  be  found  in  the  materials 
of  close  stoves  for  heating  apartments ; for  while  those  in  which  the  outer  case  consists  of  copper  or 
iron  receive  their  heat  quickly  and  part  with  it  quickly,  those  which  are  lined  with  brick  and  covered 
with  porcelain  receive  their  heat  slowly,  and  communicate  it  slowly  to  the  air  of  the  apartment.  Much, 
however,  depends  on  the  thickness  of  the  metal  casing ; for,  by  increasing  this,  it  will,  of  course,  retain 
its  heat  longer. 

When  a heated  body  cools  under  ordinary  circumstances,  it  is  by  the  united  effects  of  radiation  and 
conduction,  and  the  rate  of  cooling  increases  considerably  in  proportion  as  the  temperature  of  the  heated 
body  is  greater  than  that  of  the  surrounding  medium.  We  have  seen  that  the  cooling  effect  of  radia- 
tion depends  greatly  on  the  nature  of  the  surface  ; but  it  is  a remarkable  fact,  that  the  cooling  effect  of 
the  air  by  conduction  has  no  reference  to  the  nature  of  the  surface  ; it  is  the  same  on  all  substances, 
and  in  all  states  of  the  surface  of  those  substances.  The  air  in  contact  with  such  surfaces  robs  them  of 
ft  portion  of  heat,  and  immediately  ascends  to  make  way  for  other  portions  of  air,  which  repeat  the 


796 


WARMING  AND  VENTILATION. 


process.  By  these  two  processes  the  body  cools  down  to  the  temperature  of  the  surrounding  air,  the 
conductive  power  of  which  varies  with  its  elasticity,  or  barometric  pressure;  the  greater  the  pressure 
the  greater  also  the  cooling  power.  It  has  also  been  shown  by  Dulong  and  Petit  that  the  ratio  of  heat 
lost  by  contact  of  the  air  alone,  is  constant  at  all  temperatures ; that  is,  whatever  is  the  ratio  between 
40°  and  80°  is  also  the  ratio  between  80°  and  160°,  or  between  100°  and  200°. 

It  was  long  supposed  that  a certain  relation  existed  between  the  radiating  and  conducting  powers  of 
heated  bodies.  This  does,  to  a certain  extent,  apply  where  low  temperatures  are  concerned,  but  does 
not  hold  at  high  temperatures.  Thus,  in  a set  of  experiments  by  Dmong  and  Petit,  the  total  cooling  at 
60°  . and  120°  (Centigrade)  was  found  to  be  about  as  3 to  7 ; at  60°  and  180°,  as  3 to  13;  and  at  60° 
and  240°,  as  3 to  21 ; whereas,  according  to  the  old  theory,  these  numbers  would  have  been  as  3 to  0, 
3 to  9,  and  3 to  12.  When  the  excess  of  temperature  of  the  heated  body  above  the  surrounding  air  is 
as  high  as  240°  Cent.,  or  432°  Fahr.,  the  real  velocity  of  cooling  is  nearly  double  what  it  would  have 
been  by  the  old  theory,  varying,  however,  with  the  surface. 

Since  the  heat  lost  by  contact  of  the  air  is  the  same  for  all  bodies,  while  those  which  radiate  most,  or 
are  the  worst  conductors,  give  out  more  heat  in  the  same  time  than  those  bodies  which  radiate  least,  or 
are  good  conductors,  it  might  be  supposed  that  those  metals  which  are  the  worst  conductors  would  be 
best  adapted  for  vessels  or  pipes  for  warming  rooms  by  radiation.  “ Such  would  be  the  case  if  the 
vessels  were  infinitely  thin ; but  as  this  is  not  possible,  the  slow  conducting  power  of  the  metal  (iron) 
opposes  an  insuperable  obstacle  to  the  rapid  cooling  of  any  liquid  contained  within  it,  by  preventing 
the  exterior  surface  from  reaching  so  high  a temperature  as  would  that  of  a more  perfectly  conducting 
metal  under  similar  circumstances;  thus  preventing  the  loss  of  heat  both  by  contact  of  the  air  and  by 
radiation,  the  effect  of  both  being  proportional  to  ■‘Tie  excess  of  heat  of  the  exterior  surface  of  the  heated 
body.  If  a leaden  vessel  were  infinitely  thin,  the  liquid  contained  in  it  would  cool  sooner  than  in  a 
similar  vessel  of  copper,  brass,  or  iron ; but  the  greater  the  thickness  of  the  metal,  the  more  apparent 
becomes  the  deviation  from  this  rule  ; and  as  the  vessels  for  containing  water  must  always  have  some 
considerable  thickness,  those  metals  which  are  the  worst  conductors  will  oppose  the  greatest  resistance 
to  the  cooling  of  the  contained  liquid.” 

The  reflective  power  of  different  substances  for  heat  is  inversely  as  their  radiating  power.  If  a sur- 
face of  brass  reflect  100  parts  of  heat,  a similar  surface  of  silver  will  reflect  90  parts ; tin-foil,  85  ; block- 
tin,  80  ; steel,  70  ; lead,  60 ; tin-foil,  softened  by  mercury,  10  ; glass,  10  ; glass,  coated  with  wax,  5. 

When  similar  substances  are  exposed  to  the  same  temperature  they  all  become  heated  to  the  same 
degree,  as  measured  by  the  thermometer ; but  if  the  temperatures  of  dissimilar  substances  have  to  be 
raised  to  the  same  degree,  the  quantities  of  heat  required  for  the  purpose  will  be  very  different  for  dif- 
ferent substances.  Thus,  if  we  place  side  by  side,  upon  a hot  plate,  two  equal  and  similar  vessels,  one 
containing  a certain  weight  of  water,  and  the  other  an  equal  weight  of  mercury,  the  mercury  will  soon 
become  much  hotter  than  the  water.  So  also,  on  lowering  the  temperature  of  dissimilar  substances  to 
an  equal  degree,  some  will  give  out  more  and  others  less  heat.  Different  bodies,  therefore,  display  dif- 
ferent degrees  of  susceptibility  for  receiving  free  heat  within  their  molecules ; this  is  called  their  capa- 
city for  heat,  and  the  quantity  required  to  raise  equal  masses  or  equal  weights  1°,  is  termed  their  spe- 
cific heat.  The  theory  of  specific  heat  is  of  great  importance  in  a practical  point  of  view,  for  on  it  de- 
pend many  of  the  calculations  for  ascertaining  the  proportions  of  the  various  kinds  of  apparatus  em- 
ployed in  warming  buildings. 

The  specific  heat  of  different  substances  can  be  ascertained  by  mixing  together,  with  certain  precau- 
tions, ascertained  quantities  of  the  substances  under  consideration,  when  their  mutual  capacities  for  heat 
are  determined  by  the  decrease  in  the  temperature  of  the  hotter  body,  and  by  its  increase  in  the  cooler. 
Thus,  if  1 lb.  of  mercury  at  32°,  and  1 lb.  of  water  at  62°,  be  mixed  together,  the  common  temperature 
will  be  61°.  The  temperature  of  the  metal  has,  therefore,  risen  30°,  while  that  of  the  water  has  fallen 
1°.  If  the  mercury  had  been  at  02°,  and  the  water  at  32°,  the  common  temperature  of  the  mixture 
would  have  been  33°.  In  this  case  the  water  would  have  gained  1°  of  temperature,  and  the  mercury 
would  have  lost  30°.  Thus  it  appears  that  the  capacity  of  water  for  heat  exceeds  that  of  mercury  30 
times.  If  the  water  be  taken  as  unity,  the  specific  heat  of  the  mercury  will  be  -Jj,  or  0'033. 

Again,  if  1 lb.  of  iron  filings  at  6S°  be  mixed  with  1 lb.  of  water  at  32°,  the  temperature  of  the  mix- 
ture will  be  36°.  That  quantity  of  heat,  therefore,  the  loss  of  which  lowers  the  temperature  of  iron 
32°,  raises  the  temperature  of  water  only  4°  ; so  that  eight  times  as  much  heat  is  required  to  raise  or 
depress  the  temperature  of  the  water  1°,  as  would  raise  or  depress  the  temperature  of  an  equal  weight 
of  iron  1°.  Hence  the  specific  heat  of  iron  is  §,  or  0T25. 

The  capacity  of  substances  for  heat  may  also  be  found  by  observing  the  quantity  of  ice  which  the 
body  under  investigation  is  capable  of  thawing.  Thus,  if  equal  weights  of  iron  and  lead  be  operated 
on,  it  will  be  found  that  the  iron  requires  a greater  quantity  of  heat  than  the  lead  to  produce  the  same 
change  of  temperature,  in  the  proportion  of  nearly  1 1 to  3.  If  a bar  of  iron,  in  falling  from  100°  to  95°, 
melt  11  grains  of  ice,  then  a bar  of  lead  of  equal  weight,  under  similar  circumstances,  would  melt  rather 
less  than  3 grains ; heat  is,  therefore,  more  effective  in  warming  lead  than  iron.  Again,  an  ounce  of 
mercury  and  an  ounce  of  water,  in  falling  from  60°  to  55°,  will  melt  quantities  of  ice,  in  the  proportion 
of  33  to  1000,  or  very  nearly  1 to  30 ; that  is,  to 'raise  water  from  55°  to  60°,  requires  a greater  quan- 
tity of  heat  than  to  raise  an  equal  weight  of  mercury  through  the  same  range  of  temperature,  in  the 
proportion  of  30  to  1.  The  quantity  of  ice  melted  by  different  kinds  of  fuel  affords  a convenient  method 
of  estimating  their  relative  values.  Thus  it  has  been  found  that 


1 lb.  of  coal,  of  good  quality 

coke,  “ “ 

“ wood,  “ “ 

“ wood  charcoal,  “ 

“ peat,  “ “ 


.melts  90  l’os.  of  ice. 
. “ 84 

. “ 32 

“ 95  “ 

. “ 19 


WARMING  AND  VENTILATION. 


797 


One  method  of  estimating  how  much  of  the  heat  of  a common  fire  is  radiated  around  it,  and  how  much 
combines  with  the  smoke,  is  to  allow  all  the  radiant  heat  to  melt  a quantity  of  ice  contained  in  a ves- 
sel surrounding  the  fire,  and  all  the  heat  of  the  smoke  to  melt  the  ice  in  another  vessel  surrounding  the 
chimney.  By  comparing  the  two  quantities  of  water  thus  obtained  with  the  quantities  of  ice  melted, 
it  will  be  found,  according  to  Dr.  Arnott,  that  the  radiant  portion  of  the  heat  is,  in  ordinary  cases,  rather 
less  than  the  combined,  or  less  than  half  the  whole  heat  produced. 

The  specific  heat  of  bodies  has  been  determinetLnot  only  for  equal  weights,  but  also  for  equal  vol- 
umes, and  this  is  called  their  relative  heat,  which  il*fo  the  specific  heat  of  any  substance  directly  as  its 
specific  gravity.  It  may  be  found  by  multiplying  the  specific  heat  into  the  specific  gravity ; and  con- 
versely, the  specific  heat  may  be  found  by  dividing  the  relative  heat  by  the  specific  gravity.  Now  as 
the  quantity  of  heat  required  to  raise  the  temperature  of  1 lb.  of  water  1°  is  sufficient  to  raise  1 lb.  oi 
mercury  30°,  we  say  that  the  specific  heat  of  mercury  is  -S'(T,  taking  water  as  unity ; and  since  the  spe- 
cific gravity  of  mercury  is  about  13  6,  it  follows  that  the  relative  heat  of  an  equal  volume  of  this  metal 
is  -3~X  13'G=0'453. 

With  respect  to  gaseous  bodies,  it  has  been  found  that  their  specific  heat  is  inversely  as  their  specific 
gravity  or  density ; and,  consequently,  equal  weights  of  such  gases  contain  a larger  quantity  of  heat, 
less  their  specific  gravity.  The  capacity  of  atmospheric  air  is  taken  as  the  unit  by  which  to  estimate 
the  specific  heat  of  gaseous  bodies;  but  sometimes  that  of  water  is  assumed  as  the  unit,  and  then  the 
capacities  of  gases  are  comparable  with  those  of  solids  and  liquids.  The  latter  values  are  obtained  by 
multiplying  the  former  into  0"2669,  which  is  the  index  of  the  specific  heat  of  atmospheric  air  compared 
with  that  of  water. 

The  following  table  shows  the  specific  heat  of  various  substances  referred  to  water  as  tire  standard, 
and  are  supposed  to  represent  the  quantity  of  heat  contained  n.  equal  weights  of  the  several  sub- 
stances : 


Water 1-0000 

Aqueous  vapor 0-8470 

Alcohol OTOOO 

Ether 06600 

Oil 0-5200 

Air 0-2669 

Hydrogen 3’2936 

Nitrogen 0'2754 

Oxygen 0-2361 


Carbonic  acid 0-2210 

Carbonic  oxide 0-2S84 

Charcoal 0'2631 

Sulphur 0'1850 

Wrought-iron 0-1100 

Mercury 0-0330 

Platinum 0-0314 

Gold 0-0298 


The  method  of  ascertaining  the  specific  heat  of  gases  is  as  follows  : — The  gas  to  be  examined  is  well 
dried,  and  then  brought  from  a vessel,  surrounded  with  water  at  212°,  gradually  through  a spiral  tube, 
surrounded  by  cold  water,  the  gas  escaping  through  the  opposite  end  of  the  spiral.  In  the  course  of  its 
passage,  the  gas  parts  with  a portion  of  its  heat  to  the  cold  water  which  surrounds  the  spiral,  and  the 
temperature  of  the  water  gradually  rises,  until  after  some  time  it  becomes  stationary.  The  equilibrium 
thus  established  between  the  water  and  the  gas  is  measured  by  a thermometer,  so  as  to  find  both  the 
rise  in  the  temperature  of  the  water,  and  the  full  in  that  of  the  gas.  If  the  experiment  be  made  with 
some  other  gas,  and  the  result  should  give  a higher  temperature  to  the  water,  then  this  second  gas  must 
have  imparted  to  the  fluid  a greater  amount  of  heat  than  the  former  one  did.  If,  on  the  contrary,  the 
temperature  of  water  be  less  this  time  than  before,  it  will  have  given  out  less  heat,  and  the  respective 
capacities  for  heat  of  these  two  gases  will  be  proportional  to  the  temperatures  of  the  water  through 
which  they  have  been  admitted.  The  capacity  of  atmospheric  air  being  taken  as  the  unit,  the  specific 
heat  of  other  gases  may  be  expressed  by  proportionate  numbers.  To  raise  1 lb.  of  water  from  32°  to 
212°,  requires  the  same  quantity  of  heat  as  will  raise  4 lbs.  of  atmospheric  air  the  same  number  of  de- 
grees. The  specific  heat  of  air  is  therefore  R or,  more  exactly,  0-2669  that  of  water,  as  stated  in  the 
above  table. 

When  heat  is  added  to  a solid  body,  the  first  effect  which  marks  the  increase  of  temperature  is  ex- 
pansion. At  a certain  point,  however,  the  temperature,  as  marked  by  the  thermometer,  becomes  sta- 
tionary ; and  although  the  heat  be  continually  applied,  the  temperature  does  not  rise.  The  solid  is 
now  undergoing  a change  of  state  ; it  is  passing  from  the  solid  into  the  liquid  state  ; and  no  rise  in  tem- 
perature will  be  observed  until  the  whole  of  the  solid  has  become  liquid.  The  point  at  which  a body 
begins  to  fuse  or  melt,  is  called  its  fusing  point  or  point  of  liquefaction,  and  is  different  in  different  sub- 
stances. The  quantity  of  heat  absorbed  by  the  body,  and  unaccounted  for,  as  far  as  the  thermometer  is 
concerned,  is  called  latent  heat.  When  the  body  is  liquefied,  the  temperature  again  begins  to  rise,  until 
another  point  is  attained,  when  it  again  becomes  stationary,  and  the  liquid  begins  to  pass  off  in  the  form 
of  vapor  or  steam.  This  point  is  called  the  boiling  point,  and  is  different  in  different  substances.  The 
heat  absorbed  during  the  process  of  boiling  or  vaporization  is  also  called  latent. 

In  the  following  table,  the  melting  points  of  a few  substances  are  noted,  together  with  the  quantity  of 
heat  rendered  latent  by  each  in  passing  from  the  solid  into  the  liquid  state.  From  these  and  other  re- 
sults, it  may  be  seen  that,  in  general,  the  higher  the  point  of  fusion,  the  greater  will  be  the  quantity  of 
heat  absorbed  in  liquefaction.  There  is,  however,  no  proportion  between  these  effects,  for  ice  and  sper- 
maceti melt  at  32°  and  112°,  and  yet  the  quantities  of  heat  rendered  latent  are  nearly  the  same. 


Melting  Point.  Latent  Heat. 


W ator  32  degrees.  140  degrees 

Sulphur 213  “ 143  7 “ 

Spermaceti 112  “ 145  “ 

Lead 612  “ 162  “ 

Bees’-wax  150  “ 17o  “ 


798 


WARMING  AND  VENTILATION. 


Melting  Point.  Latent  Heat. 


Zinc 773  degress.  493  degrees. 

Tin 442  “ 500 

Bismuth 476  “ 550  “ 


In  the  following  table,  the  boiling  points  of  a few  substances  are  given,  together  with  the  quantity  of 
heat  rendered  latent  by  each  in  passing  from  the  lij^id  into  the  aeriform  state  : 


Water 

Alcohol  (sp.  gr.  0'7947). 

Ether 

Oil  of  Turpentine 

Nitric  Acid  (sp.  gr.  1-50). 

Ammonia 

Vinegar  

Petroleum 


Boiling  Point.  Latent  Heat. 

.212  degrees.  1000  degrees. 

.173  “ (bar.  29-5)  457 

. 98  “ 312-9  “ 

.314  “ 183-8  “ 

.210  “ 550 

865-9  “ 

903 

183-8  “ 


These  details  respecting  latent  heat  will  enable  the  reader  to  compare  the  merits  of  the  two  systems 
ol  heating  buildings  by  pipes  filled  with  hot  water,  and  by  similar  pipes  filled  with  steam. 

In  the  former  system,  it  is  not  desirable  to  raise  the  water  to  the  boiling  point  (212°),  because,  in 
such  case,  steam  would  be  formed,  and  this  escaping  by  the  safety-pipe,  would  abstract  much  useful 
neat  from  the  apparatus.  In  the  latter  system,  it  is  desirable  to  maintain  the  pipes  at  212°,  because, 
at  a lower  temperature,  the  steam  would  condense,  and  also  absorb  much  useful  heat  from  the  appa- 
ratus. From  the  necessity  of  maintaining  the  temperature  of  212°  in  steam-pipes,  it  is  evident  that  a 
given  length  of  steam-pipe  will  afford  more  heat  than  the  same  quantity  of  hot-water  pipe  ; but  the  fol- 
lowing remarks  by  Mr.  Hood,  on  the  relative  permanence  of  temperature  of  the  two  methods,  will  show 
an  advantage  in  favor  of  the  hot-water  system : 

“ The  weight  of  steam,  at  the  temperature  of  212°,  compared  with  the  weight  of  water  at  212°,  is 
about  as  1 to  1694  ; so  that  a pipe  which  is  filled  with  water  at  212°  contains  1694  times  as  much  mat- 
ter as  one  of  equal  size  filled  with  steam.  If  the  source  of  heat  be  withdrawn  from  the  steam-pipes, 
the  temperature  will  soon  fall  below  212°,  and  the  steam  immediately  in  contact  with  the  pipes  will 
condense  ; but  in  condensing,  the  steam  parts  with  its  latent  heat ; and  this  heat,  in  passing  from  the 
latent  to  the  sensible  state,  will  again  raise  the  temperature  of  the  pipes.  But  as  soon  as  they  are  a 
second  time  cooled  down  below  212°,  a further  portion  of  steam  will  condense,  and  a further  quantity 
of  latent  heat  will  pass  into  the  state  of  heat  of  temperature ; and  so  on,  until  the  whole  quantity  of 
latent  heat  has  been  abstracted,  and  the  whole  of  the  steam  condensed,  in  which  state  it  will  possess 
just  as  much  heating  power  as  a similar  bulk  of  water  at  the  like  temperature  ; that  is,  the  same  as  a 
quantity  of  water  occupying  y-^Ly  part  of  the  space  which  the  steam  originally  did. 

“ The  specific  heat  of  uncondensed  steam,  compared  with  water,  is  for  equal  weights  as  -8470  to  1 ; 
but  the  latent  heat  of  steam  being  estimated  at  1000°,  we  shall  find  that  the  relative  heat  obtainable 
from  equal  weights  of  condensed  steam  and  of  water,  reducing  both  from  the  temperature  of  212°  to 
60°,  to  be  as  7'425  to  1 ; but  for  equal  bulks,  it  will  be  as  1 to  228,  that  is,  bulk  for  bulk,  water  will 
give  out  228  times  as  much  heat  as  steam,  on  reducing  both  from  the  temperature  of  212°  to  60°.  A 
given  bulk  of  steam  will,  therefore,  lose  as  much  of  its  heat  in  one  minute,  as  the  same  bulk  of  water 
will  lose  in  three  hours  and  three  quarters.” 

But  when  the  water  and  the  steam  are  both  contained  in  iron  pipes  of  the  same  dimensions,  the  rate 
of  cooling  will  differ  from  this  ratio,  in  consequence  of  the  greater  quantity  of  heat  contained  in  the 
metal  than  in  the  steam.  The  specific  heat  of  iron  being  nearly  the  same  as  that  of  water,  the  pipe 
filled  with  water  will  contain  4'68  times  as  much  heat  as  that  which  is  filled  with  steam;  and  if  the 
latter  cools  down  to  60°  in  one  hour,  the  other  will  require  about  four  hours  and  a half  to  do  the  same. 
There  are  other  circumstances  to  be  noticed  hereafter,  which  cause  the  hot  water  apparatus  to  be  six  or 
eight  times  (instead  of  4J)  more  efficient  as  a source  of  warmth  than  steam. 

The  process  of  boiling  is  by  no  means  indispensable  to  the  formation  and  escape  of  steam  or  vapor ; 
for  at  all  temperatures  below  the  boiling  point,  vapor  is  formed  at  the  surface  of  liquids,  and  escapes 
therefrom  by  a process  called  spontaneous  evaporation.  The  difference  between  this  process  and  ebul- 
lition is  chiefly  this  : — When  a liquid  boils,  the  vapor  which  escapes  therefrom  constantly  maintains  the 
same  temperature,  provided  the  pressure  remain  the  same  ; but  evaporation  may  go  on  at  all  tempera- 
tures and  pressures,  the  quantity  of  liquid  evaporated  depending  on  the  temperature  and  the  amount 
of  surface  exposed. 

We  have  seen  that  the  pressure  or  elasticity  of  vapor  at  212°  is  sufficient  to  support  a column  of 
mercury  30  inches  high.  The  force  of  vapor  at  lower  temperatures  is  also  measured  by  the  length  of 
the  mercurial  column  which  it  will  support.  Vapor  at  200°  will  support  23'64  inches  of  mercury  ; at 
150°,  7-42  inches;  at  100°,  1-86  inches;  at  80°,  1 inch;  at  60°,  -524  inch;  at  50°,  -375  inch;  at  32°, 
•2  inch. 

The  amount  of  evaporation,  however,  is  greatly  influenced  by  the  motion  of  the  air,  which  carries  off 
the  vapor  from  the  surface  of  a liquid  as  fast  as  it  is  formed.  A strong  wind  will  cause  twice  as  much 
vapor  to  be  discharged  as  a still  atmosphere.  Dalton  ascertained  the  number  of  grains’  weight  of  water 
evaporated  per  minute  from  a vessel,  six  inches  in  diameter,  for  all  temperatures  between  20°  and  212°, 
when  the  air  was  still,  or  in  gentle  or  brisk  motion.  When  the  water  was  at  212°,  the  quantity  evapo- 
rated was  120  grains  per  minute  in  a still  atmosphere ; 154  grains  per  minute  with  a gentle  motion  oi 
the  air  ; and  189  grains  per  minute  with  a brisk  motion  of  the  air.  The  following  is  an  extract  from 
his  table  between  the  temperatures  of  40°  and  60°  : 


WARMING  AND  VENTILATION. 


799 


Temperature. 

Force  of  vapor  in 
inches  of  mercury. 

Evaporating  force  in  grains  of  water. 

Fahrenheit. 

Still 

Gentle. 

Erislc. 

40  degrees. 

0'263  degrees. 

T05  degrees. 

T35  degrees. 

T65  degrees. 

42 

■283 

T13 

T45 

T78 

44 

305  “ 

1-22 

T57 

1-92 

40  ‘l 

•327 

T31 

T68 

2-00 

48 

•351 

1-40 

1-80 

2-20  “ 

50 

•375 

T50 

T9  2 

2-36 

52 

•401 

TOO 

2-06  “ 

2-51 

54 

•429 

1-71 

2-20  “ 

2-69 

50 

•458 

T83 

2-35 

2-88 

58 

■490 

1-96 

2-52 

3-08 

60 

•524 

2-10 

2.70 

3-30 

The  amount  of  spontaneous  evaporation  is  also  greatly  influenced  by  the  quantity  of  vapor  already 
existing  in  the  air.  In  order  to  find  this,  we  must  ascertain  the  dew-point  of  the  air,  or  the  temperature 
at  which  the  vapor  in  the  air  begins  to  condense,  and  then,  by  referring  to  the  table,  the  quantity  of 
vapor  in  the  air  at  the  time  can  be  found ; and  this,  deducted  from  the  quantity  shown  by  the  table  to 
be  given  off  at  the  ascertained  temperature  of  the  evaporating  liquid,  will  give  the  quantity  of  water 
that  will  be  evaporated  per  minute.  In  finding  the  dew-point,  we  must  bring  some  colder  body  into 
the  air,  or  have  the  means  of  cooling  some  body  to  such  a point  as  shall  just  condense  the  vapor  of  the 
air  upon  its  surface.  Dr.  Dalton  used  a very  thin  glass  vessel,  into  which  he  poured  cold  water  from  a 
well,  or  cooled  down  the  water  by  adding  a small  portion  of  a freezing  mixture.  If  the  vapor  was  in- 
stantly condensed,  he  poured  out  the  cold  water  and  used  some  a little  warmer,  and  so  on,  until  he 
could  just  perceive  a slight  dew  upon  the  surface.  The  temperature  at  which  this  took  place  was  the 
dew-point.  In  Daniell’s  hygrometer,  the  cold  is  produced  by  the  evaporation  of  ether.  Now  suppose 
the  dew-point  of  the  air  to  be  40°,  and  the  temperature  of  the  air  and  of  the  evaporating  liquid  to  be 
60°,  with  a still  atmosphere,  the  vapor  in  the  air,  as  shown  by  the  table  at  40°,  is  1'05  grains,  which, 
subtracted  from  that  at  60°,  or  210,  gives  To  grains  per  minute  as  the  quantity  of  vapor  given  off  from 
a surface  six  inches  in  diameter. 

During  the  spontaneous  evaporation  of  wet  surfaces,  a considerable  degree  of  cold  is  produced  by  the 
quantity  of  heat  rendered  latent  by  the  formation  of  the  vapor ; and  the  heat  is  mostly  derived  from  the 
liquid  itself,  or  the  surface  containing  it.  By  proper  contrivances,  water  may  be  frozen,  in  consequence 
of  the  abstraction  of  heat  during  the  rapid  formation  of  vapor.  When  a jJerson  takes  cold  from  wear- 
ing wet  clothes,  the  vapor  from  the  wet  clothes  obtains  its  heat  from  his  body,  and  the  chilling  sensa- 
tion is  often  the  greater  the  warmer  the  air.  A person  with  damp  clothes,  entering  a room  filled  with 
hot  dry  air,  is  very  likely  to  take  cold,  on  account  of  the  powerful  effect  of  warm  air  in  abstracting 
moisture. 

In  a badly  ventilated  room,  the  moisture  from  the  breath  of  the  inmates,  and  from  the  combustion  of 
lamps  and  candles,  accumulates  nearly  to  the  point  of  saturation.  This  is  well  shown  by  an  experi- 
ment of  the  late  Professor  Daniell.  The  temperature  of  a room  being  45°,  the  dew-point  was  39°  ; a 
fire  was  then  lighted  in  it,  the  door  and  window  shut,  and  no  air  was  allowed  to  enter.  The  thermome- 
ter rose  to  55°,  but  the  point  of  condensation  remained  the  same.  A party  of  eight  persons  afterwards 
occupied  the  room  for  several  hours,  and  the  fire  was  kept  up  ; the  temperature  rose  to  58°,  and  the 
point  of  condensation  rose  to  52°.  Now,  if  this  room  had  been  properly  ventilated,  the  vapor  would 
have  been  removed  as  it  was  formed,  and  with  it  the  effluvia  and  impure  air. 

On  the  warming  of  buildings  by  means  of  steam  and  hot  water. — The  method  of  warming  build 
ings  by  steam,  depends  on  the  rapid  condensation  of  steam  into  water  when  admitted  into  any  vessel 
which  is  not  so  hot  as  itself.  At  the  moment  of  condensation,  the  latent  heat  of  the  steam  is  given  out 
to  the  vessel  containing  it,  and  this  diffuses  the  heat  into  the  surrounding  space. 

The  first  practical  application  of  this  principle  was  made  by  James  Watt,  in  the  winter  of  1184-5, 
who  fitted  up  an  apparatus  for  warming  his  study.  The  room  was  18  feet  long,  14  feet  wide,  and  8£ 
feet  high.  The  apparatus  consisted  of  a box,  or  heater,  made  of  two  side  plates  of  tinned  iron,  about  3-J 
feet  long,  by  2-J-  feet  wide,  separated  about  an  inch  by  stays,  and  jointed  round  the  edges  by  tin-plate. 
This  heater  was  placed  on  its  edge,  near  the  floor  of  the  room.  It  was  furnished  with  a cock  to  let  out 
the  air,  and  was  supplied  with  steam  by  a pipe  from  a boiler,  entering  at  its  lower  edge ; and  by  this 
pipe  the  condensed  water  also  returned  to  the  boiler.  The  heating  effect  of  this  apparatus  was  not  so 
great  as  was  anticipated,  in  consequence,  perhaps,  of  the  bright  metallic  surfaces  of  the  box  not  being 
favorable  to  radiation. 

About  the  end  of  the  year  1199,  Mr.  Lee,  of  Manchester,  under  the  direction  of  Boulton  and  Watt, 
erected  a heating  apparatus  of  cast-iron  pipes,  which  served  also  as  supports  to  the  floor.  This  an- 
swered perfectly,  and  was,  in  point  of  materials  and  construction,  the  earliest  of  its  kind.  Mr.  Lee  af- 
terwards had  his  house  heated  by  steam  ; and  the  staircase,  hall,  and  passages  were  warmed  by  the 
apparatus  shown  in  Fig.  3703.  It  was  placed  in  the  underground  story,  and  consisted  of  a vertical  cast- 
iron  cylinder  a,  surrounded  by  a casing  of  brick-work,  leaving  a space  e e of  two  and  a half  inches  all 
round,  and  having  openings  i below,  to  admit  the  air.  This  casing  was  surrounded,  at  the  distance 
of  three  or  four  inches,  by  another  wall,  forming  a sort  of  well  c.  The  colder  and  heavier  air  falling  to 
the  bottom  of  this  well,  entered  by  the  holes  i into  the  space  e where  it  came  in  contact  with  the 
cylinder  a,  and,  being  heated,  ascended.  The  entrance  of  the  steam  into  the  cylinder  was  regulated  by  a 
ralve,  the  air  being  allowed  to  escape  by  a stop-cock,  while  the  steam  was  entering;  the  condensed 


800 


WARMING  AND  VENTILATION. 


water  escaping  by  a pipe  not  shown  in  the  figure.  The  transmission  of  the  heated  air  was  regulated 
by  a valve  at  a,  on  the  top  of  the  brick-work.  This  apparatus  was  so  effective,  and  heated  the  staircase 
to  such  a degree,  that  after  it  had  been  in  operation  a short  time,  it  was 
necessary  to  suspend  its  action  by  closing  the  valve  at  a,  or  by  closing  the 
valve  which  admitted  steam  into  the  cylinder. 

In  establishments  where  a steam-engine  is  in  daily  use,  the  ^team-pipes 
may  be  supplied  from  the  engine-boiler,  its  dimensions  being  enlarged  at  the 
rate  of  one  cubic  foot  for  every  2000  cubic  feet  of  space,  to  be  heated  to  the 
temperature  of  70°  or  80°.  A boiler  adapted  to  an  engine  of  one-horse 
power  is  sufficient  for  heating  50,000  cubic  feet  of  space.  Hence  an  appa- 
ratus specially  erected  for  the  purpose  need  not  be  of  very  large  size,  nor  is 
the  quantity  of  fuel  consumed  great.  If  the  fire  under  a small  boiler  be 
carefully  managed,  14  lbs.  of  coal  will  convert  one  cubic  foot  of  water,  at  50°, 
into  1800  cubic  feet  of  steam,  at  216°  ; and  only  12  lbs.  of  coal  are  required 
to  convert  the  same  quantity  of  water  into  steam,  at  212°.  The  shape  of  the 
boiler,  and  the  method  of  setting  it,  must  also  be  considered,  and  the  furnace 
must  be  arranged  so  as  to  admit  no  more  air  than  is  required  to  support  the 
combustion.  The  hot  air  must  also  be  kept  in  contact  with  the  sides  of  the 
boiler,  until  as  much  of  the  heat  as  possible  be  abstracted  from  it.  In  such 
an  arrangement,  according  to  Dr.  Arnott,  nearly  half  of  all  the  heat  produced 
in  the  combustion  is  applied  to  use. 

In  estimating  the  extent  of  surface  of  steam-pipe  required  to  raise  the  rooms  to  the  proper  tempera- 
ture, it  is  necessary  to  consider  how  the  heat  is  expended.  This  is  done  in  three  ways : — 1,  Through  the 
thin  glass  of  the  windows.  2,  More  slowly  through  the  walls,  floors,  and  ceiling;  and  3,  In  combination 
with  the  air  which  escapes  at  the  joinings  of  the  windows  and  doors,  or  through  openings  expressly 
made  for  the  purpose  of  ventilation.  The  amount  of  heat  lost  in  this  way  has  been  variously  estimated 
by  different  writers ; but  Dr.  Arnott  states  it  thus  : — That  in  a winter  day,  with  the  external  tempera- 
ture at  10°  below  freezing,  to  maintain  in  an  ordinary  apartment  the  agreeable  and  healthful  tempera- 
ture of  G0C,  there  must  be  of  surface  of  steam-pipe,  or  other  steam  vessel  heated  to  200°,  (which  is  the 
average  surface-temperature  of  vessels  filled  with  steam  of  212°,)  about  one  foot  square  for  every  six 
feet  of  single  glass  window  of  usual  thickness  ; as  much  for  every  120  feet  of  wall,  roof,  and  ceiling  of 
ordinary  material  and  thickness  ; and  as  much  for  every  six  cubic  feet  of  hot  air  escaping  per  minute  as 
ventilation,  and  replaced  by  cold  air.  A window,  with  the  usual  accuracy  of  fitting,  allows  about  eight 
feet  of  air  to  pass  by  it  in  a minute,  and  there  should  be  for  ventilation  at  least  three  feet  of  air  per 
minute  for  each  person  in  the  room.  According  to  this  view,  the  quantity  of  steam-pipe  or  vessel 
needed,  under  the  temperature  supposed,  for  a room  16  feet  square  by  12  feet  high,  with  two  windows, 
each  7 feet  by  three,  and  with  ventilation,  by  them  or  otherwise,  at  the  rate  of  16  cubic  feet  per  minute, 
would  be — 

For  42  square  feet  of  glass  (requiring  1 foot  for  6) 7 feet. 

“ 1238  feet  of  wall  floor  and  ceiling  (requiring  1 foot  for  120) 10J  “ 

“ 16  feet  per  minute  for  ventilation  (requiring  1 foot  for  6) 2§  “ 

Total  of  heating  surface  required 20  feet. 

Which  is  20  feet  of  pipe,  4 inches  in  diameter,  or  any  other  vessel  having  the  same  extent  of  surface, — 
as  a box  two  feet  high,  with  square  top  and  bottom  of  about  18  inches.  It  may  be  noticed,  that  nearly 
the  same  quantity  of  heated  surface  would  suffice  for  a larger  room,  provided  the  (quantity  of  window- 
glass  and  of  the  ventilation  were  not  greater ; for  the  extent  of  wall,  owing  to  its  slow  conducting 
quality,  produces  comparatively  little  effect. 

The  same  authority  also  supplies  the  following  illustrations  : — A heated  surface,  as  of  iron,  glass, 
die.,  at  temperatures  likely  to  be  met  with  in  rooms,  if  exposed  to  colder  air,  gives  out  heat  with  ra- 
pidity, nearly  proportioned  to  the  excess  of  its  temperature  above  that  of  the  air  around  it,  less  than 
half  the  heat  being  given  out  by  radiation,  and  more  than  half  by  contact  of  the  air.  Thus,  if  the  ex- 
ternal surface  of  an  iron  pipe,  heated  by  steam,  be  200°,  while  the  air  of  the  room  to  be  warmed  by  it 
is  at  60°,  showing  an  excess  of  temperature  in  the  pipe  of  140°,  such  pipe  will  give  out  nearly  seven 
times  as  much  heat  in  a minute  as  when  its  temperature  falls  to  80°,  because  the  excess  is  reduced  to 
20°,  or  \ of  what  it  was.  Supposing  wdndow-glass  to  cool  at  the  same  rate  as  iron-plate,  one  foot  of 
the  steam-pipe  would  give  out  as  much  heat  as  would  be  dissipated  from  the  room  into  the  external  air 
by  about  five  feet  of  window,  the  outer  surface  of  which  were  30°  warmer  than  (hat  air.  But  as  glass 
both  conducts  and  radiates  heat  about  -1  slower  than  iron,  the  external  surface  of  the  glass  of  a 
window  of  a room,  heated  to  60°,  would,  in  an  atmosphere  of  22°,  be  under  50°,  leaving  an  excess  of 
less  than  30°  ; and  about  six  feet  of  glass  would  be  required  to  dissipate  the  heat  given  off  by  one  foot 
of  the  steam-pipe.  In  double  windows,  whether  of  two  sashes  or  of  double  panes,  only  half  an  inch 
apart  in  the  same  sash,  the  loss  of  heat  is  only  about  one-fourth  of  what  it  is  through  a single  window. 
It  is  also  known  that  one  foot  of  black  or  brown  iron  surface,  the  iron  being  of  moderate  thickness,  with 
140°  excess  of  temperature,  cools  in  one  second  of  time  156  cubic  inches  of  water  one  degree.  From 
this  standard  fact,  and  the  law  above  given,  a rough  calculation  may  be  made  for  any  other  combina- 
tion of  time,  surface,  excess,  and  quantity.  And  it  is  to  be  recollected,  that  the  quantity  of  heat  which 
changes,  in  any  degree,  the  temperature  of  a cubic  foot  of  water,  produces  the  same  change  on  2850 
cubic  feet  of  atmospheric  air. 

The  arrangement  of  the  steam-pipes  has  next  to  be  considered.  A common  method  is  shown  in 
Fig.  3704,  in  which  a is  the  pipe  from  the  boiler,  rising  at  once  to  the  upper  story.  From  this  pipe  pro- 
ceed horizontal  branches  b b to  each  floor.  Each  branch  is  furnished  with  a stop-cock  at  o,  by  which 
means  the  steam  can  be  turned  on  or  off  at  pleasure,  in  any  one  of  the  three  stories.  The  water  aris- 


3703. 

J n t) 


c 

’ 

1 

71 

U 

c 

1 

© 

7 

WARMING  AND  VENTILATION. 


801 


3705. 


3700. 


ing  from  the  condensation  of  the  steam  in  each  pipe  flows  back  into  the  boiler  along  the  ascending  pipe 
But  if  it  be  not  convenient  to  place  the  boiler  below  the  level  of  the  lowest  floor,  the  condensed  steam 
is  received  into  a reservoir,  from  which  it  is  pumped  into  the  feeding-cistern.  At  the  extremity  of  each 
horizontal  branch  C is  a stop-cock,  which  is  opened  when  the  steam  is  filling,  to  allow  the  air  to  blow  off 

Another  arrangement  of  the  heating  pipes  is  shown  in  Fig.  3105.  Steam  from  the  boiler  enters  by 
the  connecting-pipe  a into  the  heatiqg-pipe  b,  placed  near  the  floor ; and  this  is  carried,  with  a gentle 
slope,  to  the  opposite  side  of  the  room,  whence  it  rises  into  the  next  story,  and  returns  along  its  floor  to 
the  opposite  side,  where  it  rises  to  the  third  floor,  and  proceeds  as  before.  Here,  also,  the  condensed 
water  flows  back  in  a direction  contrary 
to  the  current  of  the  steam,  and  is  re-  3701. 

moved  by  a siphon  at  a.  The  air-vent 
is  fixed  at  the  highest  point  of  the  ar- 
rangement c. 

It  is  necessary  to  prevent  the  con- 
densed water  from  accumulating  in  the 
pipes,  otherwise  it  would  be  impossible 
to  maintain  them  at  a uniform  tempera- 
ture. Moreover,  this  water  condenses  the 
steam  so  rapidly,  that  a vacuum  is  formed 
within  the  boiler  and  pipes  ; and  should 
they  not  be  firm  enough  to  resist  the  ex- 
ternal pressure  of  the  atmosphere,  the  boiler  may  be  crushed  in,  and  the  whole  system  deranged.  By  a 
special  arrangement,  the  condensed  water  is  collected  at  certain  parts  of  the  system,  where  it  continues  to 
give  out  heat  after  the  steam  has  ceased  to  flow  into  the  pipes.  In  such 
cases,  stop-cocks  may  be  employed,  so  arranged  as  to  allow  the  water  to 
be  afterwards  withdrawn  from  the  pipes  ; the  same  cocks  also  serve  for 
letting  the  air  out  of  the  pipes  when  the  steam  is  first  admitted.  But  when 
the  water  is  returned  into  the  boiler,  the  advantage  of  this  supply  of  heat 
cannot  be  reserved  ; and  in  these  cases,  a self-acting  apparatus  is  used 
for  taking  off  the  water  of  condensation.  Such  a siphon  is  represented  in 
Fig.  3706.  The  pipes  are  so  fixed,  that  A is  the  lowest  point  of  a branch 
pipe,  so  that  any  quantity  of  water  that  may  be  formed  in  it  will  flow 
into  the  siphon,  A 11  C,  at  A,  and  escape  at  C,  where  it  may  be  received 
into  any  vessel ; for  as  the  water  is  pure  distilled  water,  it  may  be  useful 
for  a variety  of  purposes.  The  water  in  the  legs  of  the  siphon  acts  as  a 
trap  to  the  steam  in  the  pipe  A ; hence,  the  length  of  the  leg  A B should 
not  be  less  than  is  equivalent  to  the  force  of  the  steam  in  the  pipes. 

When,  for  example,  the  steam  is  worked  at  the  rate  of  ten  pounds  per 
square  inch,  the  column  of  water  should  not  be  less  than  ten  feet ; and 
even  with  this  pressure,  there  will  be  considerable  oscillations,  unless  a 
valve  be  placed  at  some  intermediate  point  between  A and  B.  When 
the  legs  are  both  filled  with  water,  and  at  rest,  this  valve  should  be  open, 
so  as  to  close  whenever  the  water  has  a tendency  to  return  into  the  pipe. 

The  siphon  should  be  large  enough  to  carry  off  all  the  water  of  condensa- 
tion, but  not  too  large,  or  there  would  be  a loss  of  heat  in  the  leg  A B, 
from  its  being  filled  with  steam ; and,  in  all  cases,  the  siphon  should  be 
protected  from  frost.  In  connection  with  the  siphon,  it  is  usual  to  place 
a cock  for  letting  the  air  out  of  the  pipe,  instead  of  the  stop-cock  above 
referred  to.  Such  a cock  is  shown  at  E,  and  it  is  made  to  range  with  the 
lower  part  of  the  pipe,  because  the  air  being  heavier  than  steam,  will  occupy  only  the  per  portion  of  it. 

In  cases  where  sufficient  depth  cannot  be  afforded  for  a siphon,  a steam-trap  valve,  made  to 
open  by  a float-ball,  is,  employed.  Tredgold’s  arrangement  is  as 
follows  : — B C,  Fig.  3707,  is  a square  box  attached  to  the  end  A of 
the  steam-pipe;  D is  a hollow  copper  cylinder,  fixed  to  a conical 
valve  E.  When  steam  is  condensed,  the  square  box  will  fill  with 
water,  which  will  float  the  hollow  cylinder,  and  the  water  will 
escape,  and  run  by  the  pipe  F into  the  drain.  Whenever  the  quan- 
tity of  water  in  the  box  is  greater  than  is  required  just  to  float 
the  cylinder,  and  when  there  is  less  than  will  float  it,  the  valve 
will  be  closed.  In  this  case,  also,  a stop-cock  S will  be  necessary 
to  let  out  the  air  while  the  pipes  are  being  filled  with  steam. 

The  various  methods  of  connecting  the  cast-iron  pipes  are  by  the 
flange-joint,  and  the  spigot  and  faucet,  or  socket-joint.  Mr.  Bu- 
chanan gives  minute  directions  for  these,  but  he  seems  inclined  to 
recommend  the  thimble-joint.  Care  must  of  course  be  taken,  in 
joining  the  pipes,  to  allow  room  for  expansion.  This  is  sometimes 
done  in  the  thimble-joint,  Fig.  3708,  in  which  the  adjoining  ends  of 
the  pipes  a i are  turned  true  on  the  outside,  and  have  a thimble, 
or  short  cylinder  of  wrought-iron,  to  inclose  them,  leaving  only  a 
small  space  for  the  current.  A piece  of  tin  c,  or  inner  thimble,  is 
interposed,  and  made  to  fit  well  to  the  turned  parts  of  the  pipes, 
which,  under  the  influence  of  heat  or  cold,  work  forwards  or  backwards,  like  a piston  in  a cylinder.  In 
a range  of  pipes  T20  feet  in  length,  there  was  a motion  from  expansion  of  three-quarters  of  an  inch ; but 
Vol.  II.— 51 


802 


WARMING  AND  VENTILATION. 


the  usual  allowance  for  the  expansion  of  cast-iron  pipes  is  one-eighth  of  an  inch  in  10  feet,  or  c 
their  length.  Cast-iron,  heated  from  32°  to  212°,  expands  ?t-o  of  its  Iength,  which  is  nearly  1|  of  an 
inch  in  100  feet.  A similar  expansion-joint  applied  to  the  spigot  and  faucet  connection.  Fig.  3709,  am 
swered  very  well.  Lead  cannot  be  substituted  for  tin  or  iron  cement  in  joints,  for,  by  frequent  heating, 
it  becomes  permanently  expanded ; while  the  iron  pipes  always  contracting  in  cooling,  and  the  lead  not 
participating  in  the  contraction,  the  joints  soon  get  loose.  Count,  Rumford  introduced  an  expansion- 
drum  x,  Fig.  3710,  of  thin  copper,  between  the  extremities  of  two  pipes  a -which,  in  elongating, 
pressed  the  sides  of  the  drum  inwards,  and  in  cooling  drew  them  outwards.  The  pipes  should  not  be 
connected  with  any  part  of  the  building,  but  be  quite  independent  thereof.  All  the  horizontal  branches 
should  be  supported  on  rollers,  and  nothing  done  to  interfere  with  the  expansion  of  the  different  parts 


3708.  3710.  3711. 


In  private  dwellings,  where  the  appearance  of  the  pipes  is  objectionable,  they  may  be  concealed  be- 
hind perforated  mouldings,  or  skirtings,  or  cornices ; or  the  steam  may  be  brought  into  ornamental 
vases  dispersed  about  the  room,  each  furnished  with  a small  stop-cock,  to  allow  the  air  to  escape  while 
the  steam  is  entering. 

The  method  of  heating  buildings  by  steam  has  been  superseded  by  hot-water  apparatus  of  various 
kinds,  which,  however,  may  be  resolved  into  two  distinct  forms  or  modifications,  dependent  on  the  tem- 
perature of  the  water.  In  the  first  form  of  apparatus,  the  water  is  at  or  below  the  ordinary  tempera- 
ture of  boiling.  In  this  arrangement,  the  pipes  do  not  rise  to  any  considerable  height  above  the  level  of 
the  boiler,  so  that  the  apparatus  need  not  be  of  extraordinary  strength.  One  pipe  rises  from  the  top  of 
the  boiler,  and  traverses  the  places  to  be  warmed,  and  returns  to  terminate  near  the  bottom  of  the 
boiler.  Along  this  tube  the  heated  water  circulates,  giving  out  its  heat  as  it  proceeds.  The  boiler 
may  be  open  or  closed.  If  open,  the  tube,  when  once  filled  with  water,  acts  as  a siphon,  having  an  as- 
cending current  of  hot  water  in  the  shorter  leg,  and  a descending  current  of  cooled  water  in  the  longer 
leg.  If  the  boiler  be  closed,  the  siphon  action  disappears,  and  the  boiler,  with  its  tubes,  becomes  as  one 
vessel.  In  the  second  form  of  apparatus,  the  water  is  heated  to  350°  and  upwards,  and  is,  therefore, 
constantly  seeking  to  burst  out  as  steam,  with  a force  of  70  lbs.  and  upwards  on  the  square  inch,  and 
can  only  be  confined  by  very  strong  or  high-pressure  apparatus.  The  pipe  is  of  iron,  about  an  inch  in 
diameter,  made  very  thick.  The  length  extends  to  1000  feet  and  upwards  ; and  where  much  surface 
is  required  fur  giving  out  heat,  the  pipe  is  coiled  up  like  a screw.  A similar  coil  is  also  surrounded  by 
the  burning  fuel,  and  serves  the  place  of  a boiler. 

The  heating  of  rooms  by  the  circulation  of  hot  water  in  pipes  seems  to  have  occupied  the  attention 
of  a few  speculative  individuals,  long  before  the  attempt  was  actually  made.  The  first  successful  at- 
tempt, on  a large  scale,  was  made  in  France,  in  1777,  by  M.  Bonnemain,  in  an  app;yatus  for  hatching 
chickens,  for  the  purpose  of  supplying  the  market  of  Paris.  A section  of  this  heating  apparatus  is 
shown  in  Fig.  3711,  in  which  a is  the  boiler,  d a feed-pipe,  o a stop-cock,  for  regulating  the  quantity  of 
ascending  hot  water,  b the  pipe  by  which  the  hot  water  ascends  from  the  boiler  into  the  heating  pipes 
c c which  traverse  the  hatching-chamber.  These  heating  pipes  have  a gradual  slope  towards  the 
boiler,  to  which  the  water  returns  by  the  pipe  e,  carried  nearly  to  the  bottom.  In  this  way  the  water 
cooled  by  being  circulated  through  a long  series  of  pipes,  is  being  constantly  returned  to  the  lowest 
part  of  the  boiler,  where  it  receives  a fresh  amount  of  heat ; and  being  thus  rendered  lighter,  rises  up 
the  pipe  b,  and  descends  the  inclined  planes  of  the  pipes,  losing  a portion  of  its  heat  on  the  way,  and  at 
the  same  time  increasing  in  density ; the  velocity  of  the  current  depending  on  the  difference  between 
the  temperature  of  the  water  in  the  boiler  and  that  in  the  descending  pipe.  At  the  highest  point  of  the 
apparatus  is  a pipe  i,  furnished  with  a stop-cock  for  the  escape  of  the  air  which  the  cold  water  holds  in 
solution  on  entering  the  boiler.  The  water  that  rises  along  with  it  is  received  into  the  vessel  k. 

Whatever  be  the  arrangement  adopted  for  warming  buildings  by  this  method,  two  considerations  must 
be  specially  attended  to,  viz.,  sufficient  strength  to  bear  the  hydrostatic  pressure,  and  freedom  of  motion  for 
currents  of  water,  of  varying  temperatures,  and  consequently  of  varying  densities.  As  fluids  transmit 
their  pressure  equally  in  every  direction,  a column  of  water  rising  from  a strong  vessel  to  a certain 
height,  may  be  made  to  burst  the  vessel  with  enormous  force.  Thus  a tube  whose  sectional  area  is  one 
inch,  rising  to  the  height  of  34L  feet  from  the  bottom  of  a vessel  of  water,  will,  if  the  tube  be  also  full 
of  water,  exert  a bursting  pressure  on  every  square  inch  of  the  inner  surface  of  such  vessel  of  one  at- 
mosphere, or  15  lbs.  If  the  sectional  area  of  the  tube  be  increased,  the  pressure  remains  the  same,  be- 
cause it  is  distributed  over  a larger  surface  of  the  vessel.  If  a boiler  be  3 feet  long,  2 feet  wide,  and  2 
feet  deep,  with  a pipe  28  feet  high  from  the  top  of  the  boiler,  when  the  apparatus  is  filled  with  water, 
there  will  be  a pressure  on  the  boiler  of  66,816  lbs.,  or  very  nearly  30  tons.  This  will  show  the  neces- 
sity for  great  strength  in  the  boiler,  especially  when  it  is  considered  that  the  effect  of  heat  upon  it  is  to 
diminish  the  cohesive  force  of  its  particles.  But  even  supposing  the  apparatus  were  to  burst,  no  danger 
would  arise,  because  water,  unlike  steam,  has  but  a very  limited  range  of  elasticity.  The  boiler  just 
described  would  contain  about  75  gallons  of  water,  which,  under  a pressure  of  one  atmosphere  on  the 


WARMING  AND  VENTILATION. 


80:J 


Equare  inch,  would  be  compressed  about  one  cubic  inch ; and  if  the  apparatus  were  to  burst,  the  expan- 
sion would  only  be  one  cubic  inch,  and  the  only  effect  of  bursting  would  be  a cracking  in  some  part  of 
the  boiler,  occasioning  a leakage  of  the  water. 

The  circulation  of  the  water  is  brought  about  by  the  principle  of  convection.  When  heat  is  applied 
to  a vessel  containing  water,  the  principle  of  conduction  altogether  fails,  for  water  is  so  imperfect  a con- 
ductor of  heat,  that  if  the  fire  be  applied  at  the  top,  the  water  may  be  made  to  boil  there  without 
greatly  affecting  the  temperature  below.  But  when  the  fire  is  applied  below,  the  particles  in  contact 
with  the  bottom  of  the  boiler,  being  first  affected  by  the  heat,  expand,  and  thus  becoming  specifically 
lighter  than  the  surrounding  particles,  ascend,  and  other  particles  take  their  place,  which  in  like  manner 
becoming  heated,  ascend  also  ; and  the  process  goes  on  in  this  way  until  the  whole  contents  of  the 
boiler  have  received  an  accession  of  temperature.  If  the  process  be  continued  long  enough,  the  water 
will  boil  and  pass  off  in  steam.  If  the  boiler  be  closed  in  on  all  sides,  so  as  to  prevent  the  escape  of 
steam,  it  will  burst  with  a fearful  explosion.  If  a tube  full  of  water  rise  from  the  top  of  the  boiler  in  a 
vertical  line  to  any  required  height,  and  then  by  a series  of  gentle  curves  descend,  and  enter  near  the 
bottom  of  the  boiler,  the  process  of  heating  is  still  the  same.  The  particles  of  water  first  heated  will 
rise,  and,  in  doing  so,  distribute  their  heat  to  other  particles,  which  will  also  rise.  These  in  their  turn 
will  lose  a portion  of  their-  heat  to  other  particles,  which  rise  in  their  turn  ; until  at  length  an  equilibrium 
is  established.  But  as  the  source  of  heat  is  permanent,  other  particles  are  rapidly  brought  under  its 
action,  and,  being  heated,  ascend.  By  continuing  the  process  a short  time,  the  particles  in  the  vertical 
tube  become  heated,  and,  by  their  expansion,  exert  a pressure  on  the  water  contained  in  the  lateral 
branches.  This,  together  with  the  increasing  levity  of  the  water  in  the  boiler,  establishes  a current,  and 
the  water  from  the  branches  begins  to  set  in  in  the  direction  of  the  boiler ; the  water  in  the  lowest 
branch,  where  it  enters  the  boiler,  supplying  colder  and  heavier  particles  every  moment  to  take  the 
place  of  the  warmer  and  lighter  particles  which  are  being  urged  upwards  along  the  vertical  pipe. 

Now  to  ascertain  the  force  with  which  the  water  returns  to  the  boiler,  we  must  know  the  specific 
gravities  of  the  two  columns  of  water,  the  ascending  and  the  descending,  and  the  difference  between 
them  will  be  the  effective  pressure  or  motive  power.  This  can  be  done  by  ascertaining  the  temperature 
of  the  water  in  the  boiler  and  in  the  descending  pipe.  When  the  difference  amounts  to  only  a few  de- 
grees, the  difference  in  weight  is  very  small,  but  quite  sufficient,  in  a well-arranged  apparatus,  to  main- 
tain a constant  circulation.  For  example,  suppose  an  apparatus  to  be  at  work,  in  which  the  tempera- 
ture in  the  descending  pipe  is  170  deg.,  and  the  temperature  of  the  water  in  the  boiler,  the  height  of 
which  is  12  inches,  is  178  deg.  The  difference  in  weight  is  8'16 
grains  on  each  square  inch  of  the  section  of  the  return  pipe.  If 
the  boiler  A,  Fig.  8712,  be  two  feet  high,  and  the  distance  from 
the  top  of  the  upper  pipe  c to  the  centre  of  the  lower  pipe  d be 
18  inches,  and  the  pipe  four  inches  in  diameter,  the  difference  of 
pressure  on  the  return  pipe  will  be  153  grains,  or  about  one-third 
of  an  ounce  weight ; and  this  will  be  the  amount  of  motive  power 
of  the  apparatus,  whatever  he  the  length  of  pipe  attached  to  it.  If  such  an  apparatus  have  1 00  yards 
of  pipe,  four  inches  in  diameter,  and  the  boiler  contain  30  gallons,  there  will  be  190  gallons  or  1900 
lbs.  weight  of  water  kept  in  continual  motion  by  a force  equal  to  only  one-third  of  an  ounce. 

Another  method  of  estimating  the  velocity  of  motion  of  the  water  of  a hot-water  apparatus,  is  to 
regard  the  two  portions  of  the  system  as  the  lighter  and  heavier  fluids  in  the  two  limbs 
of  a barometrical  a-friometer.  This  instrument  is  an  inverted  siphon,  Fig.  3713,  and  its 
use  is  to  ascertain,  irv  a rough  way,  the  specific  gravities  of  immiscible  fluids.  If  mercury 
be  poured  into  one  limb  A and  water  into  the  other  B,  and  the  stop-cock  between  them 
be  turned  so  as  to  establish  a communication,  it  will  be  found  that  an  inch  of  mercury 
F D in  one  limb  will  balance  13J  inches  of  water  I E in  the  other  limb,  thus  showing  that 
the  densities  or  specific  gravities  of  the  two  fluids  are  as  13  J to  1.  If  oil  be  used  instead 
of  mercury,  it  will  require  10  inches  of  oil  to  balance  9 inches  of  water.  Or  if  equal  bulks 
of  oil  and  water  be  poured  into  the  limbs  of  the  siphon  and  the  stop-cock  be  then  turned, 
the  oil  will  be  forced  upwards  with  a velocity  equal  to  that  which  a solid  body  would  ac- 
quire in  falling  by  its  own  gravity,  through  a space  equal  to  the  additional  height  which 
the  lighter  body  would  occupy  in  the  siphon.  Now  as  the  relative  weights  of  water  and 
oil  are  as  9 to  10,  the  oil  in  one  limb  will  be  forced  upwards  by  the  water  with  a velocity 
equal  to  that  which  a falling  body  (in  this  case  the  water)  would  acquire  in  falling 
through  one  inch  of  space,  and  this  velocity  is  equal  to  138  feet  per  minute. 

In  estimating  the  velocity  of  motion  of  the  water  in  a hot-water  apparatus,  the  same 
rule  will  apply.  “If  the  average  temperature  be  170  deg.,  the  difference  between  the 
temperature  of  the  ascending  and  descending  columns  8 deg.,  and  the  height  10  feet ; 
when  similar  weights  of  water  are  placed  in  each  column,  the  hottest  will  stand  '331  of 
an  inch  higher  than  the  other,  and  this  will  give  a velocity  equal  to  79'2  feet  per  minute.  If  the  height 
be  five  feet,  the  difference  of  temperature  remaining  as  before,  the  velocity  will  be  only  55'2  feet  per 
minute  ; but  if  the  difference  of  temperature  in  this  last  example  had  been  double  the  amount  stated— 
that  is,  had  the  difference  of  temperature  been  16  deg.,  and  the  vertical  height  of  the  pipe  five  feet — 
then  the  velocity  of  motion  would  have  been  79'2  feet  per  minute,  the  same  as  in  the  first  example, 
where  the  vertical  height  was  10  feet,  and  the  difference  of  temperature  8 deg.” 

But  in  all  these  calculations  a considerable  deduction  must  be  made  for  the  effects  of  friction.  In  the 
centre  of  the  ascending  pipe,  the  heated  particles  meet  with  the  smallest  amount  of  obstruction,  and 
there  the  motion  is  quickest ; but  at  and  near  the  circumference  of  the  pipe,  the  retarding  effects  of 
friction  are  most  apparent.  In  the  descending  pipe  the  friction  is  less,  for  the  water  descends  more  as 
a whole,  and  is,  moreover,  assisted  by  the  gravity  of  the  mass.  In  an  apparatus  where  the  length  of 
pipe  is  not  great,  where  the  pipes  are  of  large  diameter,  and  the  bends  and  angles  few,  a large  deduc. 


804 


WARMING  AND  VENTILATION. 


tion  from  the  theoretical  amount  must  still  be  made,  to  represent  'with  any  thing  like  accuracy  the  true 
velocity ; and  Mr.  Hood  states  that  in  more  complex  apparatus  the  velocity  of  circulation  is  so  much 
reduced  by  friction  that  it  will  sometimes  require  from  50  to  90  per  cent,  and  upwards  to  be  deducted 
from  the  calculated  velocity,  in  order  to  obtain  the  true  rate  of  circulation. 

The  amount  of  friction  not  only  varies  according  to  the  arrangement  of  the  apparatus,  but  also  ae 
cording  to  the  size  of  the  pipes.  It  is  much  greater  in  small  pipes  than  in  large  ones,  on  account  of  the 
relatively  larger  amount  of  surface  in  the  former;  besides  this,  small  pipes  cool  quicker  than  large  }nes, 
and  this  increases  the  velocity  of  the  circulation,  and  with  it  the  friction  is  also  increased.  When  the 
velocity  with  which  the  water  flows  is  the  same  in  pipes  of  different  sizes,  tne  relative  amount  of  friction 
is  as  follows : 

Diameter  of  the  pipes,  ^ in.,  1 in.,  2 in.,  3 in.,  4 in. 

The  amount  of  friction,  8,  4,  3,  T3,  1. 


3714. 


So  that,  if  the  friction  in  a pipe  of  4 inches  diameter  be  represented  by  1,  the  friction  of  a pipe  2 
inches  in  diameter  is  twice  as  much,  and  a 1-inch  pipe  four  times  as  much.  By  increasing  the  velocity, 
the  friction  increases  nearly  as  the  square  of  the  velocity;  but  as  the  water  in  a hot-water  apparatus 
circulates  with  various  degrees  of  speed  in  its  different  parts,  it  is  not  easy  to  calculate  the  amount  of 
friction  from  this  cause. 

It  will  be  seen,  then,  that  when  all  the  deductions  are  made,  the  circulation  of  the  water  is  produced 
by  a very  feeble  power,  so  that,  as  may  be  supposed,  a very  slight  cause  is  sufficient  to  neutralize  it. 
Mr.  Hood  has  known  so  trifling  a circumstance  as  a thin  shaving  accidentally  getting  into  a pipe,  effect- 
ually to  prevent  the  circulation  in  an  apparatus  otherwise  perfect  in  all  its  parts. 

But  the  great  point  to  be  attended  to,  is  so  to  dispose  the  pipes,  that  the  water,  in  its  descent,  may 
not  be  obstructed  by  differences  ; level,  or  angles  in  the  pipes,  where  air  may  accumulate  ; for  this, 
by  dividing  the  stream,  effectually  prevents  the  circulation.  For  example,  in  an  apparatus  constructed 
in  the  form  represented  in  Fig.  3714,  the  motion  through  the  boiler 
and  pipe  A B takes  place  by  convection,  and  through  the  descend- 
ing  pipe  C D by  the  force  of  gravity,  as  already  described.  But 
it  will  be  seen  that,  when  the  motion  commences  in  the  return 
pipe  D B,  in  consequence  of  the  greater  pressure  of  C D than  of 
A B,  the  water  in  A will  be  forced  towards  e,  while  the  water  in 
ef  g h flows  towards  C.  But  when  a very  small  quantity  of  hot 
water  has  passed  from  the  pipe  and  boiler  A B into  the  pipe  ef 
the  column  of  water  g h will  be  heavier  than  the  column  ef  and 
the  current  will,  therefore,  tend  to  move  along  the  upper  pipe 
towards  the  boiler,  instead  of  from  it.  This  force,  whatever  its 
amount,  must  oppose  that  in  the  lower  or  return  pipe,  in  conse- 
quence of  the  pressure  of  C D being  greater  than  A B ; and  unless  the  force  of  motion  in  the  descend- 
ing pipe  C D be  sufficient  to  overcome  this  tendency  to  a retrograde  motion,  and  leave  a residual  force 
sufficient  to  produce  direct  motion,  no  circulation  of  the  water  can  take  place. 

With  respect  to  the  accumulation  of  air  in  the  pipes,  every  part  of  the  apparatus,  where  an  altera- 
tion of  level  occurs,  must  be  furnished  with  a vent  for  the  air.  Thus,  in  Fig.  3714,  if  the  air  accumu- 
late in  the  pipe  between  A and  e,  it  is  evident  that  a vent  at  C,  although  it  would  take  off  the  air  from 
g h , and  from  C D,  could  not  receive  any  portion  of  that  which  is  confined  between  A e,  or  between  ef 
because,  in  that  case,  it  must  descend  through  the  pipe  ef  before  it  could  escape,  and  as  air  is  so  very- 
much  lighter  than  water,  it  cannot  possibly  descend  so  as  to  pass  an  obstruction  lower  than  the  place 
where  it  is  confined.  The  same  remark  applies  to  all  cases,  however  large  or  small  the  descent  may 
be,  and  the  accidental  misplacing  of  a pipe  in  the  fixing,  by  which  one  end  may  be  made  a little 
higher  than  the  other,  will  as  effectually  prevent  the  escape  of  air  through  a vent  placed  at  the  lower 
end,  as  though  the  deviation  from  the  level  were  as  many  feet  as  it  may,  perhaps,  be  inches. 

When  it  is  required  to  heat  a number  of  separate  stories  by  the 
same  boiler,  one  of  two  methods  may  be  adopted.  The  vertical  pipe 
from  the  boiler  may  be  carried  up  to  the  highest  story,  and  the  re- 
turn pipe  meander  through  each  story,  until  it  finally  terminates  in 
the  boiler.  But  it  is  obvious,  that  in  such  case,  the  top  story  will  get 
the  larger  share  of  the  heat,  and  the  lower  stories  will  be  gradually 
less  heated,  on  account  of  the  cooling  of  the  water  in  its  passage  to 
the  boiler.  The  second  method  is  to  supply  each  story  with  a sep- 
arate range  of  pipes  branching  out  from  the  main  pipe,  and  returning 
either  together  or  separately  into  the  boiler.  The  application  of 
this  principle,  however,  requires  caution,  for  if  the  branch  pipes  are 
simply  inserted  into  the  side  of  a vertical  ascending  pipe,  the  hot 
current  may  pass  by,  instead  of  flowing  into,  them.  Some  con- 
trivance is,  therefore,  necessary  to  delay  the  motion  of  the  upward 
current,  and  to  cause  it  to  turn  aside  at  the  points  required.  This 
may  be  done  by  the  arrangement  shown  in  Fig.  3715,  which  is 
also  copied  from  Mr.  Hood’s  work.  Here  it  will  be  perceived, 
that  as  the  water  ascends  from  the  boiler  B it  receives  a check  at 
b,  whereby  it  tends  to  flow  through  the  horizontal  pipe,  at  that 
level.  The  same  also  occurs  at  c,  and,  by  this  means,  a nearly 
equal  flow  of  hot  water  may  be  obtained.  If  it  be  required  to 
cut  off  the  supply  of  heat  from  one  story,  while  the  others  are 
being  heated,  this  may  be  done  by  turning  a stop-cock  at  s,  by 


3715. 


WARMING  AND  VENTILATION. 


805 


which  the  heated  current  is  prevented  from  flowing  along  the  particular  branch  so  closed.  But  when- 
ever a branch  is  closed  as  at  s,  it  is  necessary  also  to  close  the  other  end  t of  the  same  branch,  other- 
wise the  water  in  the  descending  return  pipe  R,  being  warmer  and  lighter  than  that  in  the  branch  closed 
at  s,  will  circulate  therein,  and  thus  raise  the  temperature  of  the  room  intended  to  be  kept  cool. 

In  some  arrangements,  the  hot  ascending  current  of  the  vertical  main  is  made  to  discharge  into  an 
open  cistern  at  the  top,  as  in  Fig.  3716,  and  from  the  bottom  of  this  cistern  the  various  flow-pipes  are 
made  to  branch  off.  By  this  means,  the  expense  of  cocks  or 
valves  is  avoided ; for  by  driving  a wooden  plug  into  one  or 
more  of  the  pipes  which  open  into  the  cistern,  the  circulation 
will  be  stopped  until  the  apparatus  is  heated ; but,  in  that 
case,  water  will  flow  back  through  the  return  pipe.  This, 
however,  may  be  prevented,  by  bending  a lower  portion  of 
the  return  pipe  into  the  form  of  an  inverted  siphon,  as  shown 
in  the  figure.  This  will  not  prevent  the  circulation  when  the 
flow-pipe  is  open ; but  if  that  be  closed  by  a plug  in  the 
cistern,  the  hot  water  will  not  return  back  through  the  lower 
pipe.  Any  sediment  that  may  accumulate  in  the  siphon  may 
be  removed,  from  time  to  time,  by  taking  off  the  cap  at  the 
lower  part  of  the  bend. 

In  such  an  arrangement  as  that  shown  in  the  last  two  figures,  the  vertical  main  £ .pe  need  not  be  01 
larger  diameter  than  the  branches,  unless  these  extend  to  a very  considerable  distance,  and  then  the 
diameter  of  the  main  pipe  may  be  somewhat  enlarged.  It  is  not,  however,  desirable  to  increase  the 
diameter  of  the  main,  because  it  is  an  object  to  economize  the  heat  in  this  pipe,  and  there  are  circum- 
stances in  which  a small  main  loses  less  heat  than  a large  one,  as,  for  example,  in  the  arrangement 
shown  in  Fig.  3716.  If  one  main  pipe,  eight  inches  in  diameter,  supply  four  branches  in  a given  time, 
it  is  evident,  that  by  reducing  the  main  to  four  inches  in  diameter,  the  water  must  travel  four  times 
faster  through  the  smaller  pipe  to  perform  the  same  amount  of  work ; and,  under  such  circumstances, 
the  water  will  lose  only  half  as  much  heat  in  passing  through  the  small  main  as  it  would  do  in  ascend- 
ing the  larger  one,  for , the  loss  of  heat  sustained  by  the  water  is  directly  as  the  time  and  the  surface 
conjointly.  ’ 

Hence,  in  warming'  by  the  same  boiler  two  rooms  separated  from  each  other,  by  a considerable  dis- 
tance, the  pipe  connecting  the  two  rooms  may  be  of  smaller  diameter  than  the  pipes  used  for  diffusing 
the  heat  Thus  a pipe  of  one  inch  diameter  may  be  used  to  connect  pipes  four  inches  in  diameter. 

The  great  specific  heat  of  water,  whereby  it  is  enabled  to  retain  its  heat  for  a very  long  time,  has 
been  already  shown  (page  743)  to  be  a great  advantage  of  this  method  of  warming  buildings.  The 
rate  at  which  this  apparatus  cools  depends  chiefly  on  the  quantity  of  water  coritaiued  in  it  with  respect 
to  the  amount  of  surface  exposed,  and  the  excess  of  temperature  of  the  apparatus  above  that  of  the 
surrounding  air ; but  for  temperatures  below  the  boiling  point,  this  last  circumstance  need  only  be  taken 
into  account  in  estimating  the  velocity  with  which  this  apparatus  cools.  Now  the  variation  in  the  rate 
of  cooling  for  bodies  of  all  shapes,  is  inversely  as  the  mass  divided  by  the  superficies.  In  cylindrical 
pipes,  the  inverse  number  of  the  mass  divided  by  the  superficies  is  exactly  equal  to  the  inverse  of  the 
diameters ; so  that,  supposing  the  temperature  to  be  the  same  in  all, 

In  pipes  of 1 2 3 4 inches  diameter, 

The  ratio  of  cooling  will  be 4 2 T3  1 “ 

That  is,  a pipe  of  one  inch  in  diameter  will  cool  four  times  as  quickly  as  a pipe  of  four  inches  in 
diameter,  and  so  on.  These  ratios,  multiplied  by  the  excess  of  heat  in  the  pipes  above  that  of  the 
surrounding  air,  will  give  the  relative  rates  of  cooling  for  different  temperatures  below  212  deg.;  but 
if  the  temperatures  be  the  same  in  all,  the  simple  ratios  given  above  will  show  their  relative  rate  of 
cooling  without  multiplying  by  the  temperatures. 

These  calculations  supply  practical  rules  for  estimating  the  size  of  the  pipes  under  different  circum- 
stances. If  the  heat  be  required  to  be  kept  up  long  after  the  fire  is  extinguished,  large  pipes  should 
be  used ; if,  on  the  contrary,  the  heat  is  not  wanted  after  the  fire  is  put  out,  then  small  ones  will  answer 
the  purpose.  Pipes  of  larger  diameter  than  four  inches  should  never  be  used,  because  they  require  a 
very  long  time  in  being  heated  to  the  proper  temperature.  Pipes  of  four  inches  in  diameter  are  well 
adapted  for  hot-houses,  green-houses,  and  conservatories.  Pipes  of  two  or  three  inches  may  be  used 
for  warming  churches,  factories,  and  dwelling-houses  ; such  pipes  retain  their  heat  for  a sufficient  length 
of  time,  and  they  can  be  more  quickly  and  more  intensely  heated  than  larger  pipes,  so  that,  on  this 
account,  a smaller  quantity  of  pipe  will  often  suffice. 

With  respect  to  the  quantity  of  pipe  required  for  warming  a building  of  ascertained  size,  it  is  neces- 
sary to  bear  in  mind  the  rate  at  which  a given  quantity  of  hot  water,  in  an  iron  pipe,  will  impart  its 
heat  to  the  surrounding  air.  Now,  it  has  been  shown  by  Mr.  Hood,  that  the  water  contained  in  an  iron 
pipe  four  inches  in  diameter  internally,  and  four  and  a half  inches  externally,  loses  "Sol  of  a degree  of 
heat  per  minute  when  the  excess  of  its  temperature  is  125  deg.  above  that  of  the  surrounding  air ; and, 
as  one  cubic  foot  of  water  in  losing  1 deg.  of  its  heat  will  raise  the  temperature  of  2990  cubic  feet  of 
air  the  like  extent  of  1 deg.,  so  one  foot  length  of  four-inch  pipe  will  heat  222  cubic  feet  of  air  1 deg. 
per  minute,  when  the  difference  between  the  temperature  of  the  pipe  and  the  air  is  125  degrees. 

We  must  now  take  into  account  the  loss  of  heat  per  minute  arising  from  the  cooling  power  of  glass, 
ventilation,  radiation,  cracks  in  doors  and  windows,  and  other  causes.  An  allowance  of  from  three  and 
a half  to  five  cubic  feet  of  air  ought  to  be  made  per  minute  for  each  person  in  the  room,  so  that,  for 
the  purposes  of  respiration,  this  quantity  will  have  to  be  discharged,  and  an  equal  supply  of  air  brought 
in  to  be  warmed. 

One  square  foot  of  glass  will  cool  1'279  cubic  feet  of  air  as  many  degrees  per  minute  as  me  internal 


3716. 


806 


WARMING  AND  VENTILATION. 


temperature  of  the  room  exceeds  the  temperature  of  the  external  air.  If  the  difference  between  ther. 
be  30  deg.,  the  T279  cubic  feet  of  air  will  be  cooled  30  deg.  by  each  square  foot  of  glass,  that  is,  aj 
much  heat  as  is  equal  to  this  will  be  given  off  by  each  square  foot  of  glass. 

The  quantity  of  air  to  be  warmed  per  minute  in  habitable  rooms  and  public  buildings  must  be  three 
and  a half  cubic  feet  for  each  person  the  room  contains,  and  one  and  a quarter  cubic  feet  for  each  square 
foot  of  glass.  For  conservatories,  forcing-houses,  and  other  buildings  of  this  description,  the  quantity 
of  air  to  be  warmed  per  minute  must  be  one  and  a quarter  cubic  feet  for  each  square  foot  of  glass 
which  the  building  contains.  When  the  quantity  of  air  required  to  be  heated  has  been  thus  ascertained, 
the  length  of  pipe  which  will  be  necessary  to  heat  the  building  may  be  found  by  the  following  rule  : — 
multiply  125  (the  excess  of  temperature  of  the  pipe  above  that  of  the  surrounding  air)  by  the  differ- 
ence between  the  temperature  at  which  the  room  is  purposed  to  be  kept  when  at  its  maximum,  and 
the  temperature  of  the  external  air ; and  divide  this  product  by  the  difference  between  the  temperature 
of  the  pipes  and  the  proposed  temperature  of  the  room ; then,  the  quotient  thus  obtained,  when  mul- 
tiplied by  the  number  of  cubic  feet  of  air  to  be  warmed  per  minute,  and  this  product  divided  by  222 
(the  number  of  cubic  feet  of  air  raised  1 deg.  per  minute  by  one  foot  of  4-inch  pipe)  will  give  the 
number  of  feet  in  length  of  pipe  four  inches  diameter,  which  will  produce  the  desired  effect. 

When  3-incli  pipes  are  used,  the  quantity  of  pipe  required  to  produce  the  same  effect  will,  of  course, 
be  different.  To  obtain  it,  the  number  of  feet  of  4-inch  pipe  obtained  by  the  above  rule  must  be  mul- 
tiplied by  l-33.  If  2-inch  pipe  be  used,  the  quantity  of  4-inch  pipe  must  be  multiplied  by  two. 

If  we  wish  to  determine  the  quantity  of  pipe  required  to  maintain  a constant  temperature  of  75  deg. 
in  a hot-house,  we  must  suppose  the  external  air  occasionally  to  fall  as  low  as  10  deg.,  and  calculate 
from  this  temperature.  The  amount  of  heat  to  be  supplied  by  the  pipes  is  obviously  that  which  is 
expended  by  the  glass,  the  cooling  power  of  which  is  exactly  proportioned  to  the  difference  between 
the  internal  and  the  external  temperature,  the  actual  cubical  contents  of  the  house  making  no  difference 
in  the  result.  If  such  a house  have  800  square  feet  of  glass,  it  can  easily  be  calculated,  from  the  pre- 
ceding data,  that  this  quantity  will  cool  down  1000  cubic  feet  of  air  per  minute  from  75  deg.  to  10  deg., 
which  will  require  292  feet  of  4-inch  pipe.  If  the  maximum  temperature  of  the  pipe  be  200  deg.,  and 
the  water  be  at  40  deg.  before  lighting  the  fire,  the  maximum  temperature  will  be  attained  in  about 
four  hours  and  a half ; with  3-inch  pipe,  in  about  three  hours  and  a quarter ; and  with  2-inch  pipe,  in 
about  two  hours  and  a quarter ; depending,  however,  upon  the  structure  of  the  furnace,  and  the  quantity 
of  coal  consumed.  If  the  external  temperature  be  higher  than  10  deg.,  the  effect  will  be  produced  in 
a proportionally  shorter  time. 

In  churches  and  large  public  rooms,  with  an  average  number  of  doors  and  windows,  and  moderate 
ventilation,  a more  simple  rule  will  apply  for  ascertaining  the  quantity  of  pipe  required.  Where  a 
number  of  persons  are  assembled,  a large  amount  of  heat  is  generated  by  respiration,  so  that  a very 
moderate  artificial  temperature  is  sufficient  to  prevent  the  sensation  of  cold.  In  such  a case,  the  air 
does  not  require  to  be  heated  above  55  deg.  or  58  deg.,  and  the  rule  is  to  take  the  cubical  measurement 
of  the  space  to  be  heated,  and  dividing  this  by  200,  the  quotient  will  be  the  number  of  feet  of  4-inch 
pipe  required. 

The  efficiency  of  any  form  of  hot-water  apparatus  will,  of  course,  greatly  depend  on  the  boiler, 
which  ought  to  be  so  constructed  as  to  expose  the  largest  amount  of  surface  to  the  fire  in  the  smallest 
space  ; to  absorb  the  heat  from  the  fuel,  so  that  as  little  as  possible  may  escape  up  the  chimney ; to 
allow  free  circulation  of  the  water  throughout  its  entire  extent,  and  not  be  liable  to  get  out  of  order  by 
constant  use.  A variety  of  boilers  are  figured  in  Mr.  Hood’s  work,  and  their  respective  merits  con- 
sidered on  scientific  grounds.  One  of  these  boilers  is  shown  in  Fig.  3717.  3717. 

It  is  of  cast-iron,  and  the  part  exposed  to  the  fire  is  covered  with  a series 
of  ribs  two  inches  deep,  and  about  one-fourth  or  three-eighths  of  an  inch 
thick,  radiating  from  the  crown  of  the  arch  at  an  average  distance  of  two 
inches  from  each  other.  These  ribs  greatly  increase  the  surface  exposed 
to  the  fire,  exactly  where  the  effect  is  greatest ; for  being  immediately  over 
the  burning  fuel,  it  receives  the  whole  of  the  heat  radiated  by  the  fire.  The  form  of  this  boiler  being 
hemispherical,  will  also  expose  the  largest  amount  of  surface  within  a given  area.  The  boiler  shown 
in  Fig.  3715  being  of  wrought-iron,  and,  therefore,  thinner  than  cast-iron,  absorbs  the  greatest  amount 
of  heat  from  the  fuel. 

With  respect  to  the  size  of  the  boiler,  it  has  been  shown  by  experiment  that  four  square  feet  of  sur- 
face in  an  iron  boiler  will  evaporate  one  cubic  foot  of  water  per  hour  when  exposed  to  the  direct  action 
of  a tolerably  strong  fire.  The  same  extent  of  heating  surface  which  will  evaporate  one  cubic  foot  of 
water  per  hour  from  the  temperature  of  52  deg.,  will  be  sufficient  to  supply  the  requisite  amount  of 
heat  to  232  feet  of  4-inch  pipe,  the  temperature  of  which  is  required  to  be  kept  140  deg.  above  the  sur- 
rounding air ; or  one  square  foot  of  boiler  surface  exposed  to  the  direct  action  of  the  fire,  or  three  square 
feet  of  flue  surface,  will  supply  the  necessary  heat  to  about  58  superficial  feet  of  pipe ; or,  in  round  num- 
bers, one  foot  of  boiler  to  50  feet  of  pipe.  But  as  this  is  the  maximum  effect,  a somewhat  larger  allow- 
ance ought  in  general  to  be  made.  If  the  difference  of  temperature  be  120  deg.  instead  of  140  deg., 
the  same  surface  of  boiler  will  supply  the  requisite  amount  of  heat  to  one-sixth  more  pipe,  and  if  the 
difference  be  only  100  deg.,  the  same  boiler  will  supply  above  one-third  more  pipe  than  the  quantity 
stated. 

With  respect  to  the  furnace,  the  rate  of  combustion  of  the  fuel  will  depend  chiefly  on  the  size  of  the 
furnace-bars,  provided  the  furnace-door  be  double  and  fit  tightly.  The  ash-pit  should  also  be  provided 
with  a door  to  exclude  the  excess  of  air  when  the  fire  is  required  to  burn  slowly.  A dumb-plate  should 
also  be  provided,  to  cause  the  combustion  to  be  most  active  at  the  hinder  part  of  the  furnace  instead  of 
directly  under  the  boiler.  The  fuel  will  thus  be  gradually  coked,  the  smoke  consumed,  and  the  fuel 
economized. 

In  an  apparatus  containing  600  feet  of  4 inch  pipe,  the  area  of  the  furnace-bars  should  be  300  square 


WARMING  AND  VENTILATION. 


80? 


inches,  so  that  14  inches  in  width  and  22  inches  in  length  will  give  the  amount  of  surface  required.  Tc 
obtain  the  greatest  heat  in  the  shortest  time,  the  area  of  the  bars  should  be  proportionally  increased, 
so  that  a larger  lire  may  be  obtained.  The  fire  ought  at  all  times  to  be  kept  thin  and  bright;  and  to 
obtain  a good  effect  from  the  fuel,  one  pound  weight  of  coal  ought  to  raise  39  lbs.  of  water  from  32 
degrees  to  212  degrees. 

The  best  kind  of  pipes  for  hot-water  apparatus  are  those  with  socket-joints,  flange-joints  having  long 
been  out  of  use  for  this  purpose.  Where  the  socket-joints  are  well  made,  there  is  no  fear  of  leakage, 
for  the  pipes  themselves  will  yield  before  the  joints  will  give  way,  or  before  the  faucet  end^f  one  pipe 
can  be  drawn  out  of  the  socket  of  the  other.  The  joints  must  be  well  caulked  with  spun  yarn,  and 
tilled  up  with  iron  cement,  or  with  a cement  made  of  quicklime  and  linseed  oil. 

Soft  or  rain  water  ought  always  to  be  used  in  the  hot-water  apparatus,  because,  if  hard  water  be 
used,  its  salts  will  form  a sediment  or  crust  in  the  boiler,  and  interfere  with  its  action.  But  as  there  is 
very  little  evaporation  from  this  kind  of  apparatus,  the  boiler  will  not  require  cleaning  out  for  years, 
if  a moderate  degree  of  attention  be  bestowed  on  the  water  employed. 

When  the  apparatus  is  not  in  use,  care  must  be  taken  to  prevent  the  water  from  freezing  in  the  pipes, 
or  the  sudden  expansive  force  of  the  water  in  freezing  may  crack  them.  If  the  apparatus  is  not  likely 
to  be  used  for  some  time  during  winter,  it  is  better  to  empty  the  pipes  than  incur  the  risk  of  free/, 
ing.  It  has  been  proposed  to  till  the  pipes  with  oil  instead  of  water,  and  as  the  boiling  point  of  oil  is 
nearly  three  times  higher  than  that  of  water,  it  was  thought  that  a temperature  of  400  deg.  might 
be  safely  given  to  the  pipes.  It  was  found,  however,  that  the  oil  at  high  temperatures  became  thick  and 
viscid,  and  at  length  changed  into  a gelatinous  mass,  completely  stopping  all  circulation  in  the  pipes. 

In  the  forms  of  apparatus  to  which  the  preceding  details  refer,  the  temperature  of  the  water  never 
rises  to  the  ordinary  boiling  point,  (212  deg. ;)  but  we  have  now  to  notice  a method  in  which  the  tem- 
perature of  the  water  is  often  beyond  300  deg. ; this  is  the  high-pressure  method  contrived  by  Mr. 
Perkins.  In  its  simplest  form,  the  apparatus  consists  of  a continuous  or  endless  pipe,  closed  in  all  parts, 
and  filled  with  water.  There  is  no  boiler  to  this  apparatus,  its  place  being  supplied  by  coiling  up  a 
portion  of  the  pipe  (generally  one-sixth  of  the  whole  length)  and  arranging  this  in  the  furnace.  The 
remaining  five-sixths  of  the  pipe  are  heated  by  the  circulation  of  the  hot  water,  which  flows  from  the 
top  of  the  coil,  and  cooling  in  its  progress  through  the  building,  returns  to  the  bottom  of  the  coil  to  be 
reheated.  The  diameter  of  the  pipe  is  one  inch  externally,  and  half  an  inch  internally,  and  is  formed 
of  wrought-iron.  The  coil  in  the  furnace  being  entirely  surrounded  by  the  fire,  the  water  is  quickly 
heated,  and  becoming  also  filled  with  innumerable  bubbles  of  steam,  these  impart  a great  specific 
levity  to  the  ascending  current.  At  the  upper  part  of  the  pipe,  the  steam  bubbles  condense  into  water, 
and  uniting  with  the  column  in  the  return  pipe,  which  is  comparatively  cool,  the  descent  is  rapid  in 
proportion  to  the  expansion  of  the  water  in  the  ascending  column,  or,  in  other  words,  according  to  the 
relative  specific  gravities  of  the  two  columns  of  water. 

As  the  expansive  force  of  water  is  almost  irresistible,  in  consequence  of  its  extremely  limited  elas- 
ticity, it  is  necessary  in  the  high-pressure  apparatus  to  make  some  provision  for  the  expansion  of  the 
water  when  heated.  The  necessity  for  this  will  appear  from  the  fact,  that  water  heated  from  39'45  deg. 
(the  point  of  greatest  condensation)  to  212  deg.,  expands  about  l-23d  part  of  its  bulk;  and  the  force 
exerted  on  the  pipes  by  this  expansion  would  be  equal  to  14,121  lbs.  on  the  square  inch.  The  method 
adopted  is  to  connect  a large  pipe,  called  the  expansion-pipe,  2^-  inches  diameter,  with  some  part  of  the 
apparatus,  either  horizontally  or  vertically.  It  should  be  placed  at  the  highest  point  of  the  apparatus, 
and  at  the  bottom  of  the  expansion-pipe  is  inserted  the  filling-pipe  through  which  the  apparatus  is  filled. 
While  the  apparatus  is  being  filled  with  water,  the  expansion-tube  is  left  open  at  the  top ; water  is  then 
poured  in  through  the  filling  tube,  and  as  it  rises  in  the  pipes,  drives  out  the  air  before  it.  When  the 
pipes  are  full,  the  filling-pipe  and  the  expansion-tube  are  carefully  closed  with  screw-plugs.  It  is  im- 
portant to  expel  all  the  air  from  the  pipes,  and  this  is  done,  in  the  first  instance,  by  pumping  the  water 
repeatedly  through  them.  The  expansion-pipe  is,  of  course,  left  empty,  as  its  use  is  to  allow  the  water 
in  the  pipes  to  expand  on  being  heated,  and  thus  prevent  the  danger  of  bursting.  From  15  to  20  per 
cent,  of  expansion  space  is  generally  allowed  in  practice. 

The  furnace  is  generally  so  arranged  in  the  building  required  to  be  heated,  as  to  allow  the  tube  pro- 
ceeding from  the  top  of  the  coil  to  be  carried  straight  up  at  once  to  the  highest  level  at  which  the  water 
has  to  circulate  ; here  the  expansion-tube  is  situated,  and  from  this  point  two  or  more  descending 
columns  can  be  formed,  which,  after  circulating  through  different  and  distant  parts  of  the  building, 
unite  at  length  in  one  pipe,  just  before  entering  the  bottom  of  the  coil  in  the  furnace. 

The  whole  arrangement  will  be  better  understood  by  referring  to  Fig.  3718,  in  which  a is  the  ascend- 
ing column  ; 5,  the  expansion-tube  ; c,  the  descending  columns ; d,  the  coil  in  the  furnace  ; and  ss  s s, 
stop-cocks  for  turning  off  the  circulation  from  the  coils  when  desired. 

The  heat  is  communicated  to  the  air  of  the  rooms  from  the  external  surface  of  the  pipes,  which  are 
coiled  up  as  at  e e,  and  placed  within  pedestals,  ranged  about  the  room  with  open  trellis- work  in  front, 
or  they  may  be  sunk  in  stone  floors,  placed  behind  skirtings,  or  in  the  fireplaces  of  each  floor,  the  flues 
being  stopped,  or  arranged  in  any  other  convenient  manner. 

In  consequence  of  the  great  internal  pressure  which  these  tubes  have  to  sustain,  considerable  care 
is  required  in  their  manufacture.  They  are  made  of  the  best  wrought-iron,  rolled  into  sheets  a 
quarter  of  an  inch  thick,  and  of  the  projrer  width.  The  edges  are  then  brought  nearly  together  the 
whole  length  of  the  iron,  which  is  generally  about  12  feet.  In  this  state  it  is  placed  in  a furnace,  and 
heated  to  a welding  heat.  One  end  is  then  grasped  by  an  instrument  firmly  attached  to  an  endless 
chain,  revolving  by  steam  power,  and  a man  applies  a pair  of  circular  nippers,  which,  when  closed,  press 
the  tube  into  the  required  size,  and  which  lie  holds  firmly  while  the  tube  is  drawn  through  them  by  the 
engine.  The  edges  are  thus  brought  into  perfect  contact,  and  are  so  completely  welded  after  passing 
I wo  or  three  times  through  the  nippers,  that  a conical  piece  of  iron  driven  into  the  end  of  the  tube  wiD 
not  opeu  it  at  the  joint  sooner  than  at  any  other  part. 


>508 


WARMING  AND  VENTILATION. 


When  the  tubes  are  screwed  together  at  each  end,  they  are  proved  by  hydrostatic  pressure,  with  s 
force  equal  to  3000  lbs.  on  the  square  inch  of  internal  surface. 

When  the  tubes  are  properly  arranged  and  fixed  in  the  building,  the  whole  apparatus  is  filled  with 
water  by  a force-pump,  and  subjected  to  considerable  pressure,  before  lighting  the  fire.  In  this  way 
faulty  pipes  or  leaky  joints  are  detected. 

The  tubes  are  joined  by  placing  the  ends  within  a socket,  forming  a right  and  left  hand  screw,  the  edge 
of  one  tube  having  been  flattened,  and  the  other  sharpened ; they  are  then  screwed  so  tightly  together, 
that  the  sharpened  edge  of  one  pipe  is  indented  in  the  flattened  surface  of  the  other.  Another  method 
of  connecfing  the  pipes  is  by  a cone-joint.  A double  cone  of  iron  is  inserted  into  the  ends  of  the  pipes 
to  be  joined,  and  is  made  tight  by  two  screw-bolts,  as  shown  in  Fig.  3719.  This  joint  is  quickly  made, 
and  is  very  strong. 

3718. 


3719. 


3720. 


The  furnace  varies  in  form  and  dimensions  according  to  circumstances  ; but  a very  common  arrange- 
ment is  shown  in  Fig.  3720.  The  size  is  about  three  and  a half  feet  square,  increasing  to  six  feet, 
according  to  the  extent  of  pipe  connected  with  it.  The  fire  occupies  a small  space  in  the  centre,  raised 
about  one  foot  from  the  ground,  and  the  fuel  is  supplied  through  the  hopper-door  m,  at  the  top.  The 
outer  casing  a is  of  common  brick-work  ; cc  are  fire-bricks,  supporting  the  coil  k ; dd  reservoirs  for  the 
dust  and  soot,  which  would  otherwise  clog  the  coil ; g bearing-bars  for  the  grate ; h the  grate  : the  fire-door 
is  double,  and  there  are  also  doors  to  the  ash-pit  and  dust  reservoirs.  Fig.  3721  shows  the  descending 
tube  entering  the  fire-chamber,  and  passing  through  the  bearing-bars  g g of  the  grate  h.  Fig.  3722  is  a 
section  of  the  back  well  or  reservoir  d d,  formed  so  as  to  support  the  coil,  and  to  cause  the  soot  and  dust 
to  fall  to  the  bottom. 

In  this  arrangement  of  the  furnace,  the  ignited  coal  is  surrounded  on  three  sides  by  a thickness  ot 
nine-inch  fire-brick ; the  hopper-door  is  also  placed  in  one  of  these  lumps ; the  coil  is  contained  in  a 
chamber  round  the  fire-brick,  four  and  a half  inches  wide ; the  pipe  enters  this  chamber,  passing  through 


WARMING  AND  VENTILATION. 


309 


the  bearing-bars  of  the  grate,  which  tends  to  preserve  the  grate  from  burning ; the  pipe  passes  out  from 
the  top  of  the  coil,  at  the  upper  part. of  the  chamber.  The  smoke  passes  through  the  chamber  con- 
taining the  pipes,  and  escapes  through  an  opening  at  the  back.  The  coil  is  in  actual  contact  with  tire 
fire  only  in  front.  The  best  fuel  for  this  furnace  is  coke  or  Welsh  hard  coal,  such  as  is  not  liable  to  clog. 
The  furnace  may  be  placed  in  a cellar,  or  be  completely  removed  from  the  building  to  be  warmed. 
The  heat  of  the  furnace  can  be  moderated  by  closing  the  ash-pit  door,  and  opening  the  furnace  door,  or 
the  reservoir  doors,  so  as  to  lesson  the  draught  and  admit  cold  air  to  the  coil. 

In  the  apparatus  erected  at  the  British  Museum  for  warming  the  print-room  and  the  bird-room,  the 
furnace  is  in  a vault  in  the  basement  story,  and  the  pipes,  entering  a flue,  are  carried  up  about  forty 
feet  to  two  pedestals,  one  in  each  room  ; one  containing  360  feet  of  pipe,  and  the  other  400  feet.  About 
140  feet  of  pipe  are  employed  in  the  flow  and  return  pipes  in  the  flue,  and  150  feet  are  coiled  up  in 
the  furnace.  In  this  way,  1050  feet  of  pipe  are  employed:  the  apparatus  is  very  powerful,  and  sup- 
plies the  requisite  amount  of  heat.  The  print-room  is  about  40  feet  long,  by  30  feet  wide,  and  the 
ceiling  contains  large  sky-lights.  The  temperature  of  65  deg.  can  easily  be  maintained  in  this  room 
during  winter.  The  fire  is  lighted  at  0 a.  m.,  and  is  allowed  to  burn  briskly  till  sufficient  heat  is  pro- 
duced in  the  rooms,  when  the  damper  in  the  flue  is  partially  closed.  A slow  fire  is  thus  maintained  : 
at  11  a.  m.,  a fresh  supply  of  fuel  is  added,  and  this  supports  the  fire  till  4 p.  m.,  when  all  the  fires  at  the 
Museum  are  extinguished. 

The  above  details  will  suffice  to  show  the  nature  and  application  of  this  apparatus. 

It  is,  however,  of  great  importance  to  ascertain  whether  this  apparatus  is  perfectly  safe,  for  even  a 
doubt  on  the  subject  must  be  fatal  to  its  general  introduction.  The  average  temperature  of  the  pipes 
is  stated  to  be  generally  about  350  deg. ; but  a very  material  difference  in  temperature,  amounting 
sometimes  to  200  deg.  or  300  deg.,  is  said  to  occur  in  different  parts  of  the  apparatus,  in  consequence 
of  the  great  resistance  which  the  water  meets  with  in  the  numerous  bends  and  angles  of  this  small 
pipe.  The  temperature  of  the  coil  will,  of  course,  give  the  working  effect  of  the  apparatus,  but  the 
temperature  of  any  part  of  the  pipe  will  furnish  data  for  estimating  its  safety ; for  whatever  is  the 
temperature,  and,  consequently,  the  pressure  in  the  coil,  must  be  the  pressure  on  any  other  part  of  the 
apparatus ; for  by  the  law  of  equal  pressures  of  fluids,  an  increased  pressure  at  one  part  will  generate 
an  equally  increased  pressure  at  every  other  part  of  the  system. 

A very  elegant  method  of  ascertaining  the  temperature*  of  a heated  surface  of  iron  or  steel,  consists 
in  filing  it  bright,  and  then  noting  the  color  of  the  thin  film  of  oxide  which  forms  thereon,  as  follows : 


Steel  becomes  a very  faint  yellow at  430  deg.  Fahr. 

“ pale  straw-color “ 450  “ 

“ full  yellow “ 470  “ 

“ brown “ 490  “ 

“ brown,  with  purple  spots “ 510  “ 

“ purple.. “ 530  “ 

blue “ 550  “ 

“ full  blue “ 560  “ 

“ dark  blue,  verging  on  black “ 600  “ 


Mr.  Hood  states,  that  in  some  apparatus,  if  that  part  of  the  pipe  which  is  immediately  above  the  lur 
nace  be  filed  bright,  the  iron  will  become  of  a straw  color,  showing  a temperature  of  about  450  deg. 
In  other  instances,  it  will  become  purple  = about  530  deg.,  and,  in  some  cases,  of  a full  blue  color  = 
660  deg.  Now,  as  there  is  always  steam  in  some  part  of  the  apparatus,  the  pressure  can  be  calculated 
from  the  temperature,  and  a temperature  of  450°  = a pressure  of  420  lbs.  ou  the  square  inch ; 630°  = 
900  lbs. ; and  560°  = 1150  lbs.  per  square  inch. 

Although  these  pipes  are  proved,  at  a pressure  of  nearly  3000  lbs.  per  square  inch,  and  the  force 
required  to  break  a wrought-iron  pipe  of  one  inch  external,  and  half  an  inch  internal  diameter,  requires 
8822  lbs.  per  square  inch  on  the  internal  diameter,  yet  these  calculations  are  taken  for  the  cold  metal. 
By  exposing  iron  to  long-continued  heat,  it  loses  its  fibrous  texture,  and  acquires  a crystalline  character, 
whereby  its  tenacity  and  cohesive  strength  are  greatly  weakened. 

In  order  to  make  this  apparatus  safe,  Mr.  Hood  suggests  that,  instead  of  hermetically  sealing  the 
expansion-pipe,  it  should  be  furnished  with  a valve  so  contrived  as  to  press  with  a weight  of  185  lbs. 
on  the  square  inch.  This  would  prevent  the  temperature  from  rising  above  350  deg.  in  any  part : the 
pressure  would  then  be  nine  atmospheres,  which  is  a limit  more  than  sufficient  for  any  working  appa- 
ratus where  safety  is  of  importance. 

But,  supposing  the  apparatus  were  to  burst  in  any  part,  the  effects  would,  by  no  means,  resemble  those 
which  accompany  the  explosion  of  a steam-boiler.  One  of  the  pipes  would  probably  crack,  and  the 
water,  under  high-pressure,  escaping  in  a jet,  a portion  of  it  would  instantly  be  converted  into  steam, 
while  that  which  remained  as  water  would  sink  to  212  deg.  This  would  have  the  effect  of  scalding 
water  under  ordinary  circumstances,  but  the  high-pressure  steam  would  not  scald,  because  its  capacity 
for  latent  heat  is  greatly  increased  by  its  rapid  expansion,  on  being  suddenly  liberated,  so  that 
instead  of  imparting  heat,  it  abstracts  heat  from  surrounding  objects.  The  only  real  danger  that 
would  be  likely  to  ensue,  would  be  from  the  jet  of  hot  water,  and  this  must,  in  any  case,  be  of  trifling 
amount. 

The  methods  of  warming  most  generally  practised  in  this  country  are  the  hot-air  furnaces,  so  called 
in  which  anthracite  coal  is  consumed  in  an  inclosed  iron  furnace,  lined  usually  with  fire-brick,  and  placed 
within  a brick  chamber,  either  double  or  single ; and  the  heated  air,  after  being  moistened  by  the  evap- 
oration of  water,  is  conveyed  through  the  building  !y  tin  conductors.  The  external  air  is  introduced  in 
iarge  quantities,  supplying  the  means  of  a continuous  curren'-  of  fresh  warm  air.  We  give  several 
methods  now  ii_  use 


810 


WARMING  AND  VENTILATION. 


Culver's  hot-air  and  portable  furnaces. — These  furnaces  are  represented  in  the  accompanying  draw 
ings,  Figs.  3723,  3724,  and  3725. 

A,  Fig.  3723,  iron  or  brick  ash-pit. 

B,  ash-pit  door. 

C,  pot,  or  coal-burner,  with  or  without  soap- 
stone lining. 

D,  fire-chamber. 

E,  lower  half  of  tubular  drum. 

F,  elliptical  tubes. 

G,  upper  half  of  tubular  drum. 

II,  top  of  tubular  drum. 

1,  cap  and  smoke-pipe. 

K,  flat  radiator. 

L,  water-basin,  or  evaporator. 

M,  smoke-pipe  to  chimney. 

N,  conductors  of  hot  air. 

O,  cold-air  conductor  and  chamber. 

P,  feed-door. 

Q,  hot-air  chamber. 

It,  damper  in  globe  with  rod  attached. 

S,  pendulum  valve  for  cleaning. 

The  arrows  show  the  direction  of  the  currents  of 

hot  or  cold  air. 

Fig.  3724  represents  a large  size  portable  fur- 
nace in  outline  or  skeleton  form,  in  double  cover- 
ings of  sheet-iron,  tin,  or  zinc,  with  same  letter 
references  as  in  Fig.  3723. 

These  portables  may  be  used  to  warm  stores  or 
buildings  where  it  is  not  convenient  or  desirable  to 
erect  brick  walls,  and  may  be  placed  in  basements 
or  cellars,  warming  the  rooms  in  which  they  stand, 
if  need  be,  as  well  as  those  above.  They  have 
sufficient  power  to  warm  a moderate  sized  building,  and  can  be  removed  as  easily  as  a common  stove. 

Fig.  3275  represents  a portable  furnace  with  two  metal  coverings,  with  the  inlets  and  outlets  of  cold 
and  hot  air,  smoke-pipe,  &c.,  w’ith  evaporating  pan  standing  upon  the  top  of  the  drum. 


3726. 


McGregor’s  hot-air  furnace. — Fig.  3726  is  a front  view  of  largest  furnace  set  in  mason- work.  1,  feed 
door;  2,  fire-chamber;  3,  4,  and  5,  hot-air  pipes;  6,  ash-pit  door  ; 7,  cold-air  box;  8,  cylinder  chamber 
for  generating  hot  air. 

Fig.  3727  exhibits  an  internal  view  of  the  structure  of  the  furnace.  A C D,  the  course  of  the  heat 
ascending  into  the  drum,  descending  Aid  passing  off  into  the  smoke-pipe.  H,  the  feed-door  for  fuel, 
D,  the  back  damper  by  which  the  fire  is  checked  by  admitting  cold  air  into  the  smoke-pipe. 

The  aim  of  this  furnace  is  to  exclude  entirely  the  red  and  unwholesome  heat  made  by  the  hot  or  fire 
chamber,  in  which  the  coal  is  burnt,  from  coming  into  the  hot  air  chamber,  and  instead,  all  the  heat  is 
thrown  into  the  large  cylinder  drum  in  the  air-chamber,  which  is  never  allowed  to  become  so  heated  ae 


WARMING  AND  VENTILATION. 


811 


to  burn  the  air ; and  into  this  chamber  is  continually  allowed  to  pass  a large  volume  of  fresh  air,  and 
from  thence  into  the  apartments.  The  serious  objection  to  furnaces  has  been,  not  that  they  would  not 
produce  sufficient  heat,  but  that  the  air  was  burnt  and  poisoned  by  coming  in  contact  with  the  red-hot 
cylinder  as  it  passed  through  the  hot-air  chamber,  which  in  this  furnace  is  obviated  by  shutting  off  in  a 
separate  brick  chamber  all  the  heat  thrown  out  from  the  cylinder. 

Walker's  hot-air  furnace  for  heating  and  ventilating  dwellings,  churches,  school-houses,  d'c. — Walker’s 
hot-air  furnace  is  now  very  much  in  vogue,  and  we  extract  from  his  treatise  on  warming  as  follows : 

The  principle  of  heating  by  hot-air  furnaces  is  to  take  fresh  air  from  outside  the  building,  warm  it, 
and  then  let  it  flow  into  the  rooms  as  temperature  and  ventilation  require.  Thus,  a pipe  conducts  the 
air  from  outside  of  the  building  to  the  air-chamber  of  the  furnace,  i.  e.,  the  space  inclosed  about  the  fur- 
nace ; here  it  is  warmed,  and  is  then  conducted  by  pipes  into  the  apartments,  while  the  smoke  and  gas 
generated  by  the  combustion  of  the  fuel  pass  off  by  another  pipe  to  the  chimney. 

But  if  the  air-chamber  and  the  pipes  leading  from  it  are  small,  or  if  the  furnace  itself  is  so  small  that 
in  order  to  get  the  heat  required  its  surface  must  be  kept  at  a high  red-heat,  a furnace  will  be  found  to 
be  one  of  the  most  expensive  and  disagreeable  modes  of  heating.  To  construct  a good  furnace,  there- 
fore, several  things  must  be  considered. 

1.  Ventilation. — The  problem  is  how  to • secure  a pleasant,  genial  heat,  with  thorough  ventilation. 
Either  of  these  alone  may  be  very  easily  and  economically  obtained.  Stoves  of  various  kinds  will  pro- 
duce heat  at  little  cost,  but  they  afford  no  ventilation.  Open  doors  and  windows  will  produce  ventila- 
tion, but  at  the  expense  of  that  warmth  which  health  and  comfort  require. 

To  make  a furnace  the  means  of  ventilating  an  apartment  does  not  appear  to  have  been  thought  of. 
The  uniform  plan  was  to  admit  into  the  apartments  to  be  warmed  by  the  furnace  but  a small  quantity 
of  air,  which,  to  produce  sufficient  heat,  was  necessarily  raised  to  a very  high  temperature— intensity  of 
heat  being  substituted  for  quantity.  This  was  in  various  ways  productive  of  bad  results.  The  small 
volume  of  air  introduced  into  a room  from  the  air-chamber  of  the  furnace  was  worth  very  little  for 
ventilation. 

But  the  question  arises,  how  is  the  requisite  amount  of  ventilation  to  be  secured  ? What  limit  shall 
be  assigned  to  the  introduction  of  fresh  air  into  an  apartment  which  is  to  be  heated  to  a given  temper- 
ature ? The  answer  to  this  question  must  vary  with  the  relative  importance  of  economy  in  fuel,  and  of 
the  health  and  comfort  of  the  occupants  of  the  room.  The  limit  of  the  amount  of  ventilation  must 
sometimes  be  that  which  can  be  afforded.  The  heating  of  air  for  this  process  is  just  so  much  fuel 
thrown  away. 

The  most  economical  stove  is  that  which  is  placed  in  the  room  to  be  warmed,  and  the  smoke  of  which 
is  reduced  to  the  temperature  of  the  room ; if  no  change  of  air  then  take  place,  by  crevices  or  otherwise, 
we  have  arrived  at  perfection  in  the  economy  of  fuel.  Whether  it  is  advisable  to  practise  such  econo- 
my, or  rather  parsimony,  for  this  is  its  nature,  is  quite  another  question.  It  is  upon  this  principle  of  the 
non-renewal  of  the  air  and  low  temperature  of  the  smoke,  that  air-tight  stoves  consume  but  little  wood  ; 
that  the  odor  of  the  rooms  warmed  by  them,  in  which  several  people  are  assembled,  is  offensive,  and 
their  influence  upon  the  health  injurious.  In  New  England  the  winter  temperature  is  such  that  the 
expense  of  heating  up  the  air  to  a comfortable  point  is  a serious  item,  and  the  temptation  to  economize 
in  this  respect  is  with  some  not  easily  resisted. 

If  pure  and  healthy  air  be  worth  what  it  will  cost,  then  should  hot-air  furnaces  be  so  constructed  as 
to  admit  freely  large  quantities  of  fresh  air  into  the  apartments.  But  while  this  object  is  secured,  fur- 
naces should  be  so  constructed  also  that  the  ample  volume  of  air  thus  freely  introduced  shall  be  raised 
to  the  required  temperature  with  the  least  possible  expense  of  fuel. 

2.  Evaporation. — There  appears  to  be  a great  ■want  of  information  on  this  branch  of  the  subject,  even 
among  those  who  ought  to  be  sufficient  masters  of  their  business  to  know  its  use.  Thus  one  man  will 
advertise  as  a recommendation  of  his  furnace,  that  “ a large  quantity  of  water  is  evaporated,  to  restore 
to  the  air  the  oxygen  taken  from  it  by  the  heat  of  the  furnace.”  Another  has  a furnace  “ so  constructed 
that  evaporation  is  not  necessary,  as  it  never  becomes  sufficiently  hot  to  destroy  the  vitality  of  the  air,” 
it  being  lined  with  soap-stone,  or  something  similar. 

But  all  such  statements  are  based  upon  an  incorrect  idea  of  the  use  of  evaporation.  They  imply  that 
heat  destroys  the  vitality  of  the  air,  and  that  the  evaporation  of  water  will  restore  it,  neither  of  which 
is  correct.  Heat  without  combustion  does  not  destroy  the  vitality  of  the  air  ; and  if  it  did,  evaporation 
would  not  be  a remedy.  The  necessity  for  evaporation  arises  wholly  from  the  fact,  that  as  the  temper- 
ature of  the  air  is  increased,  its  capacity  to  hold  and  its  tendency  to  absorb  moisture  are  increased  also. 
Thus  a given  volume  of  air  at  the  temperature  of  40  deg.  is  capable,  like  a sponge,  of  holding  in  suspen- 
sion a certain  quantity  of  water.  If  now,  without  adding  to  the  quantity,  the  temperature  be  raised  to 
65  deg.,  the  capacity  for  moisture  is  nearly  doubled  ; if  raised  to  90  deg.  it  is  nearly  quadrupled  ; and 
if  additional  moisture  is  not  supplied  by  the  evaporation  of  water,  what  may  be  termed,  for  convenience, 
the  drying  powers  of  the  air  will  be  manifested  in  its  effects  upon  the  wood-work  of  the  apartments, 
upon  the  furniture,  and  also  upon  the  skin  and  lungs  of  the  occupants.  It  is  impossible,  therefore,  to 
contrive  a heating  apparatus  which  shall  dispense  with  the  necessity  for  evaporation.  The  laws  of 
nature  require  this  expedient,  to  supply  air  at  an  increased  temperature  with  the  moisture  which  it 
demands. 

But  evaporation,  important  as  it  is,  must  be  judiciously  conducted.  The  evaporating  pan  should  have 
a large  surface,  and  should  be  so  arranged  that  the  water  shall  never  be  heated  to  the  boiling  point. 
When  water  boils,  steam  will  rise  whether  the  air  requires  it  or  not ; but  when  the  water  is  below  the 
boiling  point,  evaporation  proceeds  in  some  measure  according  to  the  wants  of  the  air.  When  the  air  is 
very  dry  the  evaporation  is  rapid,  and  when  moist  it  proceeds  slowly.  In  a dry  day  a number  of  gal- 
lons will  be  evaporated,  while  in  a very  moist  state  of  the  atmosphere,  when  the  same  amount  of  heat 
is  required,  the  evaporation  is  scarcely  perceptible.  If  nature  is  consulted  in  arranging  this  department 
vf  the  furnace,  the  supply  of  moisture  will  always  be  regulated  by  the  demand. 


S12 


WARMING  AND  VENTILATION. 


3.  Temperature. — To  keep  the  apartments  at  a comfortable  temperature,  well  ventilated,  without  dust 
or  gas,  and  without  injury  to  furniture  or  to  health  by  the  extreme  dryness  of  the  atmosphere,  in  a 
word,  to  keep  up  a continual  supply  of  pure,  fresh,  invigorating  air  at  summer  heat,  is  the  desideratum 
in  a hot-air  furnace.  To  effect  tins  the  heat  must  be  imparted  by  a surface  so  large  that  no  part  of  it 
wall  be  highly  heated  in  obtaining  the  requisite  temperature.  The  chief  objections  against  furnace? 
have  arisen  from  the  fact  that  very  small  surfaces  have  been  used,  and  were  heated  to  such  a degree 
that  the  innumerable  particles  of  animal  and  vegetable  matter  that  are  always  floating  in  the  air  were 
burned,  rendering  the  air  offensive  and  unhealthy.  The  air  also  was  very  highly  heated,  which  not  only 
made  it  very  unpleasant,  especially  when  it  came  in  contact  with  the  person  before  its  temperature  was 
reduced,  causing  headache,  lassitude,  and  other  disagreeable  sensations,  but  also  very  injurious  to  the 
Dannels  and  other  wood-work  of  the  room,  furniture,  &c..  by  reason  of  its  extreme  dryness. 

When  the  temperature  of  the  air  cannot  be  diminished  ■without  depositing  water  upon  the  walls  of 
the  containing  vessel,  or  appearing  as  a mist,  it  is  said  to  be  saturated.  If  the  temperature  of  saturated 
air  be  raised,  it  will,  to  the  feelings,  become  drier,  and  will  immediately  begin  to  take  up  water  which 
is  exposed  to  it ; air  is  dry  or  mo>«t,  not  in  proportion  to  the  water  it  contains,  but  in  proportion  as  it  b 
more  or  less  removed  from  the  point  of  saturation. 


3728. 


Walkers  patent  improved  hot-air  furnace,  manufactured  at  No.  S9J  Leonard-street,  New  York,  is 
represented  in  Figs.  3728  and  3729. 

The  objects  aimed  at  by  the  patentee  in  the  construction  of  his  hot-air  furnace  are — 

1st.  By  means  of  one  tire  to  produce  a mild,  uniform,  and  agreeable  temperature  throughout  several 
apartments,  and  to  warm  a whole  house  sufficient  for  sleeping-rooms,  or  to  keep  plants  of  all  kinds  in 
the  coldest  weather. 

3729. 


2d.  To  avoid  all  dust  and  gas,  and  to  keep  the  apartments  well  ventilated  by  means  of  a constant 
supply  of  fresh  air  from  without. 


WARMING  AND  VENTILATION. 


81.: 


8d.  To  be  simple,  so  that  any  one  capable  of  managing  a stove  can  take  care  of  it. 

4th.  To  be  economical  in  point  of  fuel. 

5th.  To  be  durable,  so  as  not  to  require  frequent  or  expensive  repairs. 

The  furnace  is  constructed  of  cast-iron,  is  placed  in  the  cellar  and  inclosed  in  brick  walls,  in  such  a 
manner  that  there  is  very  little  heat  wasted  by  escaping  into  the  cellar  or  chimney-flue.  Consequently 
all  the  fuel  consumed  is  made  available  to  heating  the  apartment ; and  in  no  case  where  they  have  been 
erected,  have  they  failed  to  give  entire  satisfaction. 


A,  upper  smoke-pipe. 

B,  damper. 

C,  drums,  or  radiators. 

D,  feed-door. 

E,  fire-pot,  fluted. 

F,  cold-air  flues. 


Literal  References. 

G,  space  between  walls  for  cold  air. 

H,  hot-air  flues. 

I,  lower  smoke-pipe. 

J,  evaporating  pan — 12  gallons. 

K,  door  to  put  in  or  take  out  the  heater. 

L,  door  to  remove  ashes. 


We  extract  from  the  Journal  of  the  Franklin  Institute  a report  on  warming  and  ventilating  the  west 
half  of  the  Lunatic  Asylum  of  Blockley  Almshouse,  Philadelphia,  by  steam  : 

Much  difficulty  was  experienced  in  the  adaptation  of  an  old  edifice,  not  originally  designed  for  such 
a system  as  has  been  adopted,  and  which  added  greatly  to  our  labor  and  made  it  more  difficult  to  effect 
our  purpose. 

In  constructing  the  heating  chambers  and  necessary  flues,  we  were  obliged  to  cut  through  a system 
of  arches,  which,  on  account  of  the  substantial  manner  in  which  the  building  was  constructed,  added 
greatly  to  the  expense  and  time  attending  the  prosecution  of  the  work.  The  want  of  proper  flues  and 
conduits  for  the  warmed  and  extracted  or  foul  air,  all  of  which  we  were  obliged  to  construct,  or  alter  to 
answer  the  purpose  of  the  present  arrangement;  the  insufficient  height  of  the  cellar  ceiling  for  our  pur- 
poses, and  the  impossibility  of  going  any  deeper  on  account  of  water,  presented  another  serious  difficulty 
in  the  great  distance  the  steam  had  to  be  convoyed  and  the  condensed  water  returned  again  to  the 
boilers,  being  600  feet;  a greater  depth  would  have  facilitated  the  return  of  the  condensed  water. 

Running  underneath  the  building  are  a number  of  sewers,  into  which  the  sinks  are  drained,  conse- 
quently making  them  very  foul.  These  made  a system  of  ventilation  very  desirable,  but  at  the  same 
time  greatly  interfered  with  our  efforts  to  produce  a pure  atmosphere  throughout  the  building.  The 
building  itself  is  one  very  difficult  to  warm,  on  account  of  the  great  height  of  the  ceilings,  the  first  story 
being  14  feet  11  inches,  the  second  16  feet  4 inches,  and  the  third  14  feet  8 inches  in  height.  The 
number  and  large  size  of  the  windows  making  the  glass  surface  equal  to  3447  square  feet,  and  the  im- 
perfect fitting  of  the  windows,  together  with  the  large  size  of  the  doors,  and  the  very  exposed  situation 
of  the  building,  render  it,  perhaps,  more  difficult  to  warm  than  any  of  the  buildings  connected  with  the 
Institution. 

Explanation  of  the  figures. — Fig.  3730,  plan  of  building,  and  warming  and  ventilating. 

Fig.  3731,  elevation  of  heating  chambers. 

Fig.  3732,  longitudinal  vertical  section  of  the  arrangement  for  warming  and  ventilating. 

Fig.  3733,  plan  of  a part  of  the  heating  and  ventilating  chamber. 

Fig.  3734,  elevation  of  Fig.  3733. 

Fig.  3731  is  a plan  of  the  west  half  of  the  Lunatic  Asylum  : the  main  building,  running  east  and  west, 
is  168  feet  long  by  69  feet  wide,  inside  measurement,  three  stories  high,  with  an  attic.  On  each  floor 
of  the  main  building  there  is  a large  hall  running  the  length  of  it,  a stairway,  kitchen,  dining-room,  and 
three  large  associate  rooms,  in  each  of  which  there  is  a nurse’s  room,  wash-room,  and  water-closet. 

The  wing  at  right  angles  to  the  main  building  is  119  feet  long  by  46  feet  wide,  inside  measurement, 
three  stories  high,  with  an  attic.  On  each  floor  of  the  wing  there  is  a hall  running  the  length  of  it,  and 
connected  with  the  main  building  by  another  hall,  two  stairways,  a nurse’s  room,  a bath-room,  two  asso- 
ciate rooms,  and  twenty  cells. 

Great  pains  have  been  taken  to  procure  air  for  the  supply  of  the  house  from  pure  sources,  and  to  keep 
it  from  being  contaminated  while  in  the  equalizing  and  heating  chambers  under  the  building.  The  ar- 
rangements are  such  that  the  patients  cannot  interfere  with  them  in  any  way ; there  are  no  valves  in 
any  of  the  flues  except  those  in  the  hall,  nor  have  they  been  found  desirable,  as  there  is  but  a trifling 
difference  in  the  temperature  of  the  different  parts  of  the  house,  thus  avoiding  the  consequent  annoyance 
from  interference  with  them. 

The  heating  chamber  A A,  for  warming  the  main  building,  runs  along  the  centre  of  the  cellar 
until  within  23  feet  of  the  wing,  where  it  was  found  necessary  to  stop,  on  account  of  a sewer 
crossing  it  at  right  angles.  For  warming  the  halls  in  the  main  building,  another  chamber  B is  con- 
structed. For  warming  the  cells  and  halls  in  the  wing,  the  heating  chamber  A'  runs  the  length  of  the 
wing  at  right  angles  to  the  main  chamber.  For  warming  the  associate  find  nurse's  rooms,  the  chambers 
A"  A"  A”  are  constructed. 

The  air  for  supplying  the  main  building  is  drawn  from  the  garden  on  the  south  side  into  equalizing 
chambers  L L L,  and  from  thence  through  the  small  apertures  OOO,  Ac.,  in  the  bottom  of  the  chamber 
wall,  as  indicated  by  the  arrows,  Fig.  3733,  into  the  heating  chamber  A where  it  is  heated,  and  then 
distributed  through  the  flues  F F F,  Figs.  3732,  3733,  and  3734,  into  the  different  parts  of  the  house  to 
be  warmed. 

The  air  for  supplying  the  cells  and  halls  in  the  wing  is  drawn  from  the  inclosure  on  the  west  side  of 
the  building.  It  is  received  into  a shaft  S sufficiently  high  to  be  beyond  the  reach  of  the  patients  who 
may  be  exercising  in  the  yard,  conveyed  down  this  and  through  a tunnel  50  feet  in  length  into  the 
heating  chamber  A',  where  it  is  heated,  and  from  thence  distributed  into  the  cells  and  halls. 

The  associate  rooms  in  the  wing  receive  their  supply  of  air  from  the  garden,  and  the  nurse’*  room* 


«14 


WARMING  AND  VENTILATION. 


from  the  yard.  Their  arrangements  for  the  equalizing  and  heating  chambers,  flues,  Ac.,  are  the  same  as 
the  others. 

The  arrangements  by  which  the  heated  air  is  introduced  and  the  foul  air  extracted  from  the  rooms, 
will  be  understood  by  referring  to  Figs.  3732,  3733,  and  3734,  which  represent  the  arrangement  for 
warming  and  ventilating  three  of  the  large  associate  rooms  in  the  main  building,  which  are  each  47  by 
44  feet.  The  flues  F F F lead  from  the  heating  chamber  A to  near  the  ceiling  in  the  centre  of  the 
rooms  ; these  supply  the  heated  air  for  warming-  the  roo™'  throwing  it  out  in  the  directions  as  inchoated 
by  the  arrows. 


The  foul  air  is  drawn  off  by  means  of  the  foul-air  flues  Y V placed  in  the  sides  of  the  rooms,  opposite 
to  the  entrance  for  warm  air ; they  open  close  to  the  floor,  thus  producing  a downward  ventilatioa 
Through  these  it  is  conducted  to  the  main  foul-air  flue  K K,  Figs.  3733  and  3734 ; from  thence  conducted 
to  the  extracting  shaft  E,  which  is  90  feet  high,  fitted  with  a cast-iron  chimney  30  inches  diameter 
and  25  feet  high,  through  which  the  smoke  and  gases  from  the  fire  are  discharged.  The  extracting 
shaft  is  also  fitted  with  a steam-jet,  by  means  of  which  additional  force  can  be  given  to  the  ventilation 
if  it  should  be  desirable.  There  is  also  a small  furnace  in  the  base  of  the  shaft,  so  arranged  as  to  pro- 
duce ventilation  when  the  heating  apparatus  is  not  in  use. 

The  main  sewer  which  runs  under  the  building  is  so  connected  with  the  fire  under  the  boiler  that  the 
necessary  air  for  supplying  the  furnace  may  be  drawn  from  it,  thus  creating  a current  of  air  into  the 
sewer,  and  in  a measure  preventing  the  escape  of  fetid  gases. 

GG,  Figs.  3730  and  3731,  are  two  cylindrical  boilers,  86  inches  in  diameter  and  40  feet  long,  having 
a capacity,  together,  equal  to  565  cubic  feet.  We  would  here  assure  jtou  of  the  perfect  safety  of  these 


WARMING  AND  VENTILATION. 


815 


boilers.  They  are  constructed  of  tire  best  Pennsylvania  iron,  by  experienced  workmen,  and  are  of  un- 
usual thickness;  the  heads,  although  of  cast-iron,  are  concave;  the  boilers  weigh  together  12,186  lbs., 
the  great  amount  of  water  they  contain,  and  consequently  the  amount  of  time  necessary  to  evaporate 
it,  makes  them  safe  as  regards  explosion  from  the  most  frequent  cause,  the  want  of  water ; and  their 
proportion  in  relation  to  the  fire  and  radiating  surfaces  is  such  that,  were  the  safety-valves  chained 
down,  it  would  be  impossible  to  generate  a pressure  of  100  lbs.  to  the  square  inch.  With  the  present 
weight  at  the  extreme  end  of  the  safety-valve  levers,  72  lbs.  pressure  would  raise  them.  The  boilers 
will  sustain  a pressure  of  300  lbs.  to  the  square  inch  without  any  danger ; 30  lbs.  is  the  greatest  pressure 
under  which  the  apparatus  is  generally  worked.  Plain  cylinder  boilers  are  always  preferable  to  tubu 
lar  boilers  where  there  is  room  enough  to  make  them  sufficiently  large — they  can  be  made  stronger  on 
account  of  their  form  ; they  have,  also,  more  steam  and  water  room.  The  boiler  of  a first-class  locomo- 
tive of  ordinary  construction  will  generate  enough  steam,  when  the  fire  is  in  full  operation,  to  fill  the 
steam  space  in  four  seconds,  and  enough,  could  there  none  escape,  to  burst  the  boiler  in  about  ten  min- 
utes ; they  will  evaporate  the  water  so  as  to  become  dangerous  in  from  30  to  60  minutes  when  the 
supply  of  water  is  stopped. 


3732. 


3733. 


The  smoke  and  gases  from  the  furnace  are  conveyed  through  the  smoke  flue  D,  Figs.  3730  and  3731, 
within  the  heating  chamber  A,  until  it  is  opposite  the  extracting  shaft  E ; from  here  it  is  conducted 
across  and  into  the  cast-iron  chimney  P,  within  the  extracting  shaft  E.  The  smoke-flue  within  the  heat- 
ing chamber  A is  covered  with  cast-iron  plates,  and  these  with  clean  sand.  The  arrangements  are  such 
that  the  temperature  of  the  smoke  and  gases  is  reduced  below  200  deg.  Fahr.  before  they  are  permitted 
to  escape,  thus  preventing  any  unnecessary  waste  of  heat,  and  consequently  of  fuel. 

To  the  boilers  are  connected,  by  means  of  a 6-inch  cast-iron  main  R,  systems  of  radiating  pipes  li  li  h 
of  wrought-iron,  f inch  inside  diameter ; they  are  distributed  through  the  different  heating  chambers 
A A'  A",  <fec.  These  systems  are  so  arranged  that  the  condensed  water  is  returned  to  the  boilers  to  be 
again  converted  into  steam,  thus  producing  a circulation.  There  are  between  8000  and  9000  feet  of 
radiating  pipe  distributed  through  all  the  heating  chambers. 

If  a rapid  circulation  through  the  radiating 
pipes  is  desired,  for  the  purpose  of  raising  the 
temperature  of  the  building  in  a comparatively 
short  time,  it  is  effected  by  opening  a blow-otf 
cock  which  discharges  into  a sewer;  or  by 
means  of  a steam-pump,  so  arranged  as  to  take 
the  water  from  the  condensed  water  pipes  and 
force  it  into  the  boilers.  This  pump  is  also  used 
for  supplying  the  boilers  with  water  when  the  51 
pressure  of  steam  is  too  great  to  do  so  from  the 
reservoir. 

In  the  third  story  of  the  wing  is  an  iron  tank, 
of  a capacity  of  1200  gallons,  in  which  the  water 
for  washing  and  bathing  purposes  is  heated  by 
means  of  a coil  which  is  supplied  with  steam  from  the  boilers  GG,a  distance  of  200  feet. 

The  boilers  also  supply  the  steam  for  cooking  the  food  for  the  inmates.  In  the  kitchen  are  two 
boilers  of  95  gallons  each,  and  one  of  about  50  gallons ; in  these  the  food  is  cooked.  The  k'tchen  in  the 


* 


816  WARMING  AND  VENTILATION. 


eastern  or  male  part  of  the  house  is  arranged  in  the  same  way.  They  are  all  supplied  with  steam  from 
the  same  source. 

There  is  no  fire  in  the  west  half  of  the  Asylum  excepting  under  the  boilers  G G,  and  a small  cooking 
stove  for  preparing  food  for  the  sick. 

The  cubical  contents  of  the  building  warmed,  without  deducting  partition  walls,  stairways,  <fec.,  is 
*780,000  cubic  feet ; the  amount  actually  warmed  by  the  apparatus,  deducting  partition  walls,  stairways, 
<fcc.,  is  730,000  cubic  feet,  or  90  rooms  and  6 halls. 

The  consumption  of  fuel  in  cold  weather  is  1-J  tons  of  coal  per  day,  (24  hours ;)  allowing  75  days  cold 
and  100  days  moderate  weather  through  the  winter,  the  consumption  would  be  213 — say  225  tons;  30 
tons  of  this  should  be  deducted,- which  is  the  amount  used  in  cooking,  and  15  tons  of  this  should  be 
charged  to  the  eastern  or  male  part  of  the  house.  The  consumption  of  fuel,  as  near  as  we  can  ascertain, 
for  heating  this  part  last  year  by  close  stoves,  (fee.,  and  there  was  no  ventilation,  was  from  275  to  300 
tons  of  coal,  say  275  tons,  when  but  a portion  of  the  rooms  were  warmed,  and  that  imperfectly  ; while 
by  the  arrangement  introduced  by  us,  the  whole  of  the  building  is  warmed  at  a saving  of  at  least  75 
tons  of  coal,  which,  at  $4  per  ton,  would  be  $300. 

The  advantages  of  the  present  arrangement  are — 

1st.  Producing  a pure  atmosphere  throughout  the  building,  the  air  being  supplied  in  great  abundance 
from  pure  sources,  and  so  arranged  as  to  keep  it  from  contamination. 

2d.  A system  of  downward  ventilation,  which  diffuses  the  warmth  uniformly  throughout  the  various 
apartments ; the  air  being  admitted  near  the  ceiling  and  drawn  off  at  the  floor  is  constantly  sinking,  and 
in  this  way  the  colder  and  impure  air  passes  off  by  the  foul-air  flues,  and  is  ejected  from  the  extracting 
shaft  above  the  building. 

3d.  The  safety  from  fire,  both  in  the  building  and  as  regards  the  patients,  which,  in  a lunatic  asylum, 
is  a very  important  consideration. 

4th.  The  freedom  from  noise,  dust,  and  dirt  usually  attendant  upon  fires  in  grates  and  stoves. 

5th.  The  whole  heating  arrangement  being  under  the  care  of  a single  individual,  is  more  easily  man- 
aged than  by  a number  of  attendants,  who  are  now  dispensed  with. 

6th.  The  economy  of  the  arrangement,  saving  about  25  per  cent,  in  fuel ; the  repairs  will  not  exceed 
those  of  stoves  and  grates. 

Ventilation. — The  following  hints  on  ventilation  will  be  found  of  value  in  this  place ; they  are  by 
W.  Walker,  Engr.,  of  Manchester. 

However  useful  steam  agency,  as  applied  to  ventilating  purposes,  may  be  in  factories  or  buildings 
connected  with  them,  and  in  theatres  or  other  places  liable  to  great  and  sudden  influx  or  efflux  of  per- 
sons— and  well  as  it  has  been  found  to  answer  in  its  appplication  to  other  buildings,  such  as  club-houses, 
banks,  collegiate  institutions,  and  hospitals,  in  which  manifest  advantages  have  been  derived  from  its 
employment — there  will  still  be  great  numbers  and  many  classes  of  edifices  in  which  it  would  be 
from  various  causes  inadmissible.  Churches,  chapels,  and  houses  for  worship,  may  be  enumerated  under 
this  head — the  numbers  contained  within  their  walls  being,  on  the  whole,  tolerably  constant,  and  not 
liable  to  very  sudden  fluctuations  ; but  especially  from  the  circumstance  that  they  are  seldom  used  more 
than  two  days  in  the  week,  with  intervals  of  two  or  three  days  between ; and  when  used  it  is  only  for 
two  hours  consecutively,  with  intervals  of  two  or  three  hours  between.  With  such  proper  quantity  and 
sizes  of  ingress  and  egress  flues  as  can  readily  be  obtained  in  the  thick  walls  and  piers  of  such  edifices, 
(if  planned  prior  to  their  construction,)  this  short  period  of  occupation  will  not  permit  their  atmosphere 
to  become  very  highly  charged  with  impurities,  while  the  intervals  between  the  services  will  be  found 
sufficient  for  an  entire  change  of  the  whole  atmosphere  left  in  them  at  the  close  of  each  service,  without 
resorting  to  mechanical  means.  In  churches  with  lofty  open  roofs,  of  the  mediceval  or  early  English 
construction,  without  galleries,  the  total  cubic  space  bears  so  large  a proportion  to  that  portion  of  it 
occupied  at  the  floor  level  by  the  congregation,  that  scarcely  any  injurious  vitiation  of  the  entire  atmos- 
pheric contents  can  take  place  during  the  short  period  of  occupation,  provided  moderate  preparations 
have  been  made  for  ingress  and  egress.  Hence,  very  sudden  and  powerful  ventilation  is  scarcely  re- 
quired in  such  churches,  and  the  purification  of  their  atmosphere  may  safely  be  left  to  the  spontaneous 
action  of  those  preparations ; but  on  special  occasions,  and  in  hot  weather,  the  action  of  the  fresh-air 
flues  may  be  accelerated  by  the  exhausting  power  of  a shaft  or  trunk  of  adequate  size  running  up  within 
the  tower  or  steeple,  its  upper  end  discharging  into  the  external  air,  while  its  lower  end  communicates 
with  the  interior  by  openings  in  or  near  the  roof ; and  this  shaft  may  be  made,  in  very  hot  weather,  to 
perform  two  or  three  times  its  usual  duty,  by  rarefaction  produced  at  its  lower  end  g,  Fig.  3735,  by  a 
large  number  of  gas-burners  fixed  there  in  tolerably  close  proximity  with  each  other,  and  supplied  with 
gas  from  the  mains  which  furnish  light  to  the  whole  building.  These  ideas  have  been  successfully  car- 
ried out  in  numerous  instances,  and  in  large  buildings.  The  whole  process  recommended  for  such  a 
building  will  be  better  understood  by  a reference  to  the  upper  portion  of  Fig.  3736,  which  represents  a 
section  of  a church  ventilated  in  this  manner ; a a are  openings  all  round  the  church  for  admission  of 
fresh  air  ; b b,  hot-water  pipes,  over  which  it  is  made  to  pass  on  its  way  to  the  gratings  cc;  dd  are 
openings,  by  which  the  vitiated  air  enters  a horizontal  trunk  e,  from  the  end  of  which  rises  the  shaft  f 
with  a collection  g of  gas-jets  in  the  bottom  of  it;  h i is  the  gallery  line,  and  k an  excavated  room  for 
the  boiler,  the  floor  of  which  should  be  five  feet  below  the  floor  line  of  the  church. 

By  simply  turning  the  cock  in  the  gas-pipe  which  supplies  the  jets,  the  rarefaction  in  the  shaft,  and, 
consequently,  the  velocity  and  quantity  of  the  air  passed  through  the  church,  may  be  controlled  with 
tolerable  accuracy,  and  instantly  proportioned  to  any  greater  or  smaller  number  of  persons  assembled. 
The  cost  of  piping  and  cock  for  bringing  the  gas  to  the  jets  has  been  found  to  be  but  trifling ; and  as 
they  need  oidy  be  lighted  during  the  time  the  church  is  occupied  for  worship,  which  is  seldom  of  longer 
duration  than  two  hours  and  a half,  the  consumption  of  gas  is  not  very  great,  and  amply  compensated 
by  the  beneficial  result  obtained. 

The  means  most  proper  to  be  adopted  for  the  plentiful  supply  of  fresh  air  in  the  low-roofed,  galleried 


WARMING  AND  VENTILATION. 


811 


and  crowded  meeting-house,  will  be  found  to  consist  in  abundance  of  fresh-air  openings  all  round  under 
the  windows,  communicating  by  brick  flues  with  the  lower  part  of  the  spaces  under  the  aisles  and  seat® 
in  which  the  hot-water  pipes  that  are  to  warm  the  air  should  be  fixed.  Fresh-air  flues  should  be  con- 
structed in  all  the  piers  between  the  windows,  running  as  high  as  the  gallery,  to  supply  it  with  fresh 
warmed  air.  A vitiated  air-flue  should  also  commence  in  each  pier  under  the  gallery  (in  order  to  give 
free  egress  to  that  which  would  otherwise  be  intercepted  and  detained  under  the  gallery)  and  pass  up 
into  a horizontal  trunk,  running  over  the  roof,  along  each  side,  into  the  foot  of  the  upright  shaft  below 
the  gas-jets,  as  before  explained.  Openings  should  also  be  left  in  the  roof,  communicating  with  these 
horizontal  trunks,  to  carry  off  the  bad  and  heated  air  over  the  galleries.  Hot-water  pipes  should  be 
conveyed  along  the  side-walls,  under  the  floor,  so  as  to  warm  the  air  that  passes  up  within  the  piers  intc 
the  gallery. 

The  leading  points  to  be  observed  in  such  a case  are  delineated  in  the  lower  part  of  Fig.  3735,  below 
the  line  h i. 


A much  larger  provision  should  be  made  for  supplying  fresh  air  to  such  a house  for  worship,  or  other 
galleried  building,  than  in  one  which  has  no  gallery,  and  which  possesses  the  advantage  of  an  open  roof ; 
and  those  who  would  object  to  the  copious  measures  here  recommended  as  unnecessary,  should  well 
consider  the  following  facts  and  calculations.  A chapel  or  meeting-house  with  large  galleries  nearly 
all  round,  capable  of  accommodating  on  special  occasions  2000  persons,  is  frequently  made  about  75  feet 
square  and  25  feet  average  height,  givfing  a total  cubic  content  of  rather  more  than  140,000  feet.  Now 
the  authorities  from  Tredgold  to  Reid  who  have  written  on  the  subject  of  the  quantity  of  fresh  air  re- 
quired per  minute  by  each  individual,  to  replace  that  which  such  individual  has  rendered  unfit  for  res- 
piration, vary  in  their  conclusions  from  3^  to  10  cubic  feet;  and  if  7 cubic  feet  be  assumed  to  be  the 
proper  quantity,  an  allowance  near  the  average  of  their  scientific  opinions  will  be  given.  The  total 
quantity  required,  therefore,  on  this  low  standard  in  such  a building,  to  maintain  its  atmosphere  in  a 
state  of  purity  when  filled,  will  be  (2000  X 7 =)  14,000  cubic  feet  every  minute,  and  a like  quantity  ol 
vitiated  ah'  must  be  carried  off  in  the  same  time.  The  atmosphere  of  the  building  will  therefore  require 
to  be  completely  changed  or  renewed  (140,000  -f- 14,000  = 10)  once  in  every  ten  minutes.  Let  it  now 
be  supposed  that  the  unusual  provision  of  16  openings  has  been  made  all  round  the  building  for  fresh 
air,  each  opening  measuring  18  inches  by  6 inches.  Deducting  one-third  of  the  area  for  impediment 
caused  by  gratings,  will  allow  to  each  opening  a clear  area  of  half  a superficial  foot,  and  the  aggiegate 
area  of  all  the  openings  will  be  eight  feet.  Now,  to  supply  the  required  quantity  of  air  (14,000  cubic 
feet)  in  the  given  time  (one  minute)  through  these  openings,  the  air  must  pass  through  them  all  at  the 
velocity  of  (14,000  8 =)  1750  feet  per  minute,  or  more  than  20  miles  per  hour : which  it  will  not  do, 

especially  on  a calm  day  in  hot  weather,  when  ventilation  is  most  needed , without  the  aid  of  some  pow- 
erful stimulus ; and  if  such  artificial  impulse  be  wanting,  these  openings  will,  under  the  circumstances, 
be  quite  insufficient  to  prevent  the  rapid  deterioration  of  the  atmosphere  within,  and  ought,  therefore, 
to  be  considerably  enlarged.  The  bad  effects  of  the  usual  way  of  obtaining  a partial  supply  of  air  in 
such  a case  by  opening  the  windows,  have  been  already  commented  on. 

Take  another  example  from  a larg«  Gothic  church,  with  galleries  and  lofty  side-aisles  and  nave,  in 
the  neighborhood  where  this  is  written ; measuring  80  feet  by  65  feet,  with  a roof  approaching  to  flat- 
Vol.  II.— 52 


818 


WARMING  AND  VENTILATION. 


ness,  about  30  feet  in  average  height.  This  church  has  often  contained  1800  persons ; its  cubic  contentG 
being  156,000  feet,  and  the  requirement  of  air,  allowing,  as  before,  seven  feet  per  minute  to  each  person, 
(1800  X 7 =)  12,600  feet.  The  time  in  which  the  whole  atmosphere  of  this  church  would,  when  con- 
taining its  full  complement  of  persons,  require  to  be  changed,  is  (156,000-1-12,600=)  12-J-  minutes ; 
and  large  openings  will  obviously  be  required  to  pass  the  quantity  in  the  time. 

These  figures  will  suffice  to  show  the  necessity  for  a very  much  larger  provision  for  ventilation  than 
has  been  customary  in  buildings  containing  galleries,  in  which  the  cubic  contents  bear  a small  propor- 
tion to  the  numbers  assembled. 

The  management  of  the  warming  of  a church  being  a matter  frequently  intrusted  to  a sexton  or  verget 
charged  with  other  duties,  which  necessitate  his  making  a clean  appearance,  and  demand  his  exclusive 
attention  during  the  service,  it  is  a matter  of  some  importance,  where  hot-water  apparatus  are  used,  to 
adopt  such  form  of  boiler  as  will  require  the  smallest  possible  attention.  The  kind  shown  in  Fig.  3736, 
in  section,  will  be  found  to  fulfil  this  requirement.  In  this,  a is  the  fire-box ; b,  ash-box ; c,  smoke-box  ; 
d,  fire-bars  ; e,  smoke-tubes ; f fuel-box ; g,  damper  ; h,  flow  or  steam  pipe  ; i,  return  or  condensation 
pipe ; j,  ash-box  door ; k,  fire-door ; /,  smoke-pipe.  Many  large  churches  have  been  kept  by  it  at  a uni- 
form temperature  with  only  three  attendances  in  twenty-four  hours.  This  sort  of  boiler  will  be  found 
very  desirable  in  many  other  buildings  besides  churches.  They  are  to  be  filled  to  the  top  with  coke 
broken  into  small  pieces,  which  falls  on  the  fire  as  required.  A very  useful  kind  of  Arnott  stove  has 
icei  largely  adopted  on  the  same  principle. 


3730. 


The  stove  here  described  appears  to  us  a very  simple  arrangement  for  effecting  the  purposes  desired, 
and  to  be  well  worthy  of  adoption. 

In  the  whole  raDge  of  ventilation  there  is,  perhaps,  nothing  so  much  neglected  as  the  ventilation  of 
schools ; and  as  it  is  most  desirable  public  attention  should  be  turned  to  the  subject,  we  give  room  to 
Mr.  Walker’s  statement  of  his  views  on  the  subject : 

Schools  are  frequently  very  crowded,  and  their  atmosphere  in  a most  unwholesome  condition.  The 
great  increase  in  their  number  in  the  populous  manufacturing  districts,  is  a gratifying  sign  of  the  times, 
and  affords  good  reason  to  hope  that  the  succeeding  generation  will  grow  up  with  improved  ideas  and 
habits,  and,  as  is  most  needful  in  those  districts,  stand  some  degrees  higher  than  their  predecessors  in 
the  scale  of  civilization. 

Fig.  3737  is  a section  representing  a boys’  and  girls’  school  ventilated  (except  as  regards  the  windows) 
in  a satisfactory  manner : a a are  the  fresh-air  openings ; b b,  pipes  for  heating ; c c,  gratings  for  entrance 
of  fresh  warmed  air ; d d,  openings  for  foul  air,  leading  into  a trunk  e,  whence  it  is  drawn  down  the  shaft 
f by  the  rarefying  furnace  g , whence  it  is  discharged  up  the  shaft  h into  the  atmosphere. 

This  arrangement  of  a rarefied  shaft,  continued  down  to  the  ground  for  the  purpose  of  obtaining  a 
quick  draught  by  a heated  column,  and  requiring  a down-shaft  to  connect  the  ventilating  trunk  from  the 
top  of  the  building  with  its  lower  end,  so  that  the  foul  air  may  enter  it  below  the  fire,  is  the  same  that 
has  been  adopted,  at  very  great  cost,  by  Dr.  Reid,  in  the  new  houses  of  Parliament.  There  is  a com- 
plexity and  expense  about  this  arrangement  which  would  seem  to  be  needless.  The  drawing  down  to 
the  ground  level  of  the  whole  of  the  vitiated  air  of  the  building,  and  then  sending  it  up  again ; the  cost 
of  connecting  the  main  down-shaft  with  the  up-shaft,  which  circumstances  may  require  to  be  at  a con- 
siderable distance  ; and  the  trouble  of  forming  air-tight  connecting-flues  to  convey  the  vitiated  air  from 
numerous  rooms  to  one  main  down-shaft,  to  say  nothing  of  the  double  space  and  materials  occupied  by 
(he  two  shafts,  w ould  render  this  plan  in  numerous  cases  impracticable.  To  overcome  some  of  these 


WARMING  AND  VENTILATION. 


819 


difficulties  tlie  fire  has,  in  many  cases,  been  provided  for  at  the  roof  level,  (i,  Fig.  3737,)  thus  relinquish- 
ing the  down-shaft  and  the  lower  part  of  the  up-shaft,  and  so  far  has  been  an  improvement ; but  in 
many  cases  the  trouble  of  carrying  up  fuel  and  ascending  to  attend  to  the  fire  was  too  great,  and  the 
ventilation  was,  therefore,  uncertain.  The  best  mode  of  effecting  forcible  ventilation  by  a shaft  doubt- 
less is,  to  adopt  the  last-named  arrangement ; substituting  gas  rarefiers  for  a furnace,  as  shown  in  the 
church,  Fig.  3735.  By  bringing  the  pipe  which  supplies  gas  to  the  burners  to  some  accessible  point 
near  the  ground-floor,  with  a stop-cock  at  that  point,  the  handle  of  which  should  work  in  a graduated 
quadrant,  the  ventilation  can  be  regulated  from  below  with  great  precision. 

Window  ventilation  of  a kind  very  frequently  adopted  in  churches  and  schools,  has  been  introduced 
into  this  figure,  (. Tc , Fig.  3737,)  not  with  a view  to  represent  it  as  part  of  Dr.  Reid’s  system,  but  to  illus- 
trate its  bad  effects,  either  where  it  is  the  sole  provision  made,  or  where  it  is  used  in  combination  with 
a better  process.  If  it  be  the  sole  provision  made,  and  the  room  be  heated  by  a fireplace  or  stove  to 
B0°,  a downward  rush  of  air  at  10°  (should  that  low  temperature  happen  to  prevail  outside  at  the  time) 
will  play  upon  the  heads  of  those  near  it.  If  it  be  in  force,  as  in  the  figure,  simultaneously  with  proper 
means  of  introducing  fresh  warmed  air,  its  force  will  be  modified,  and  partially  deflected  upwards,  towards 
the  egress  openings  ; but  whatever  cold  air  thus  enters  is  so  much  deducted  from  that  which  ought  to 
have  entered  warmed  through  the  proper  channel  c. 

Arnott's  ventilating  apparatus  in  use  in  the  York  County  Lunatic  Asylum,  England. — The  apparatus 
is  shown  in  the  annexed  engravings,  of  which  Fig.  3738  is  a plan,  and  Fig.  3739  a section,  taken  through 
the  centre  from  A to  B.  It  consists  of  a fixed  cylinder,  placed  in  the  centre  of  a room,  and  which  cyl- 
inder is  about  5 ft.  6 in.  diameter  and  5 ft.  high,  with  a chamber  above  and  below,  each  furnished  with 
inlet-valves  to  receive  the  air  from  the  fresh-air  shaft,  and  crtlet-valves  to  deliver  the  air  into  the  adja- 
cent chamber,  and  thence  distributed  through  the  building.  The  cylinder  is  made  of  galvanized  iron,  is 


3738. 


>pen  at  both  ends,  and  has  an  outer  case  at  about  3 inches  distance,  and  the  whole  depth  of  the  cylin- 
der filled  with  water,  which  forms  an  annular  hydraulic  joint.  Within  this  cylinder  is  another  cylinder, 
5 ft.  9 in.  diameter,  inclosed  on  the  top,  similar  to  the  rising  bell  of  a gas-holder ; the  rim  of  this  cylinder 
works  up  and  down  in  the  water  contained  in  the  annular  rim  just  described.  By  this  arrangement  the 
communication  with  the  upper  and  lower  compartments  is  cut  off. 

The  working  cylinder  is  suspended  to  the  end  of  a movable  beam  about  10  feet  long,  and  balanced 
by  a weight  or  bob  suspended  at  the  other  end,  equal  in  weight  to  the  movable  bell,  minus  a sufficient 


WATCHMAKING. 


8’dO 


weight  to  cause  the  bell  to  descend  and  expel  the  air  in  the  lower  compartment.  Now,  for  the  purpose 
of  setting  the  beam  in  motion,  it  is  necessary  to  have  some  movable  power  to  overcome  the  friction  01 
the  movable  parts  and  the  air.  For  this  purpose  Dr.  Arnott  has  adopted  a single-action  water-engine, 
having  a cylinder  2 inches  diameter  and  12  inches  stroke;  to  be  supplied  by  water  from  a reservoir 
placed  on  the  top  of  the  building,  60  feet  above  the  engine.  A column  of  water  of  this  altitude  acts 
with  a pressure  of  about  30  lb.  on  every  movable  square  inch  of  the  piston  ; and  if  the  piston  be  2 
inches  diameter,  it  will  be  equal  in  round  numbers  to  3 square  inches,  consequently  the  force  of  the 
water  acting  on  the  piston  will  be  3 X 30  = 90  lb. ; and  this  is  the  power  with  which  the  Doctor  pro- 
poses to  work  the  apparatus,  and  as  the  engine  is  single-acting,  the  cylinder  will  require  about  a pint 
of  water  for  every  stroke.  Thus,  if  the  engine  works  8 strokes  per  minute,  it  will  require  8 pints  of 
water,  or  1 gallon  per  minute,  to  keep  the  beam  moving. 

This  engine  is  placed  so  that  the  connecting-rod  is  connected  with  the  movable  beam  at  1 foot  from 
the  fulcrum  ; and  if  the  beam  have  a radius  of  5 feet,  and  the  working  cylinder  be  suspended  at  the  end 
of  the  beam,  the  bell  will  be  elevated  5 feet  at  every  stroke  of  the  engine.  When  the  piston  has  per- 
formed one  upward  stroke  by  the  pressure  of  the  water,  the  water  is  cut  off  by  a slide-valve,  and  that 
which  is  within  the  cylinder  is  discharged  into  an  open  pipe ; consequently,  the  extra  weight  of  the 
movable  parts  will  cause  the  piston  to  descend,  and  at  the  same  time  the  working  cylinder  will  also 
descend.  Now,  if  we  suppose  that  at  the  commencement  of  the  working  of  the  apparatus  the  working 
cylinder  is  close  down  on  to  the  fixed  cylinder,  the  upper  compartment  will  be  filled  with  air,  and  as  it 
rises  it  will  displace  a quantity  of  air  equal  in  capacity  to  the  cubic  contents  of  the  working  cylinder, 
and  force  it  out  of  the  valves  that  open  outwards ; and  at  the  same  time  that  the  cylinder  is  rising,  the 
space  below  is  increasing  equal  in  capacity  to  the  cylinder,  and  a quantity  of  air  rushes  in  through  the 
valves  opening  inwards,  and  fills  up  the  space  ; and  when  the  bell  begins  to  descend,  the  lower  inlet- 
valves  close  and  the  lower  outlet-valves  open,  and  the  air  that  is  below  is  forced  out  through  the  outlet- 
valves  of  the  lower  compartment,  and  at  the  same  time  the  air  is  being  admitted  into  the  upper  com- 
partment, as  before  described.  By  this  means  the  action  is  double,  and  a constant  stream  of  air  is  being 
taken  in  through  either  of  the  inlet-valves,  and  forced  out  through  the  upper  or  lower  outlet-valves  into 
the  adjacent  chamber,  and  thence  through  trunks  and  cases  to  all  parts  of  the  building. 

Now,  it  has  been  shown  that  for  every  stroke  of  the  engine  the  working  cylinder  displaces  a quantity 
of  air  equal  to  its  capacity  in  both  the  bottom  and  upper  compartments  ; and  as  the  capacity  of  the 
working  cylinder  is  equal  to  125  cubic  feet,  it  displaces  in  both  compartments  250  cubic  feet  for  every 
upward  and  downward  stroke  of  the  engine,  at  an  expense  of  one  pint  of  water,  descending  from  an 
altitude  of  60  feet ; and  if  the  engine  works  8 strokes  per  minute,  it  will  displace  2000  cubic  feet  of  air 
at  an  expense  of  8 pints,  or  one  gallon  of  water,  which  is  equal  to  2,880,000  cubic  feet  of  air  displaced 
by  the  aid  of  1440  gallons  of  water  for  24  hours.  These  are  the  proportions  proposed  by  Dr.  Arnott  for 
ventilating  York  Hospital. 

For  the  purpose  of  feeding  the  apparatus,  pure  air  is  brought  down  a shaft,  the  top  of  which  is  con- 
siderably above  the  top  of  the  building,  and  which  communicates  at  the  bottom  with  the  chambers  be- 
fore described ; and  if  it  be  desired  that  the  air  be  warmed,  it  is  effected  by  allowing  the  air,  as  it  is 
expelled  from  the  chambers  on  its  passage  to  the  trunks,  to  pass  between  a series  of  hollow  copper  ves- 
sels filled  with  hot  water. 

The  adaptation  of  the  water-engine  which  Dr.  Arnott  proposes  to  adopt  is  particularly  desirable,  as 
it  can  be  worked  at  comparatively  little  expense,  and  the  water,  after  it  has  done  its  work  in  the  en- 
gine, may  be  used  for  domestic  purposes.  It  will  also  be  seen  that  by  this  apparatus  the  whole  of  the 
air  forced  in  for  ventilation  can  be  accurately  measured  if  a counter  be  attached  to  the  engine  to  show 
the  number  of  strokes  the  engine  has  performed  during  the  day. 

Literal  references. — Similar  letters  refer  to  similar  parts  in  each  figure. 

A is  a fixed  cylinder,  open  at  both  ends  with  outer  case  a,  filled  with  water,  forming  an  annular  hy- 
draulic joint. 

B,  working  cylinder  inclosed  on  the  top  and  open  at  the  bottom ; the  rim  works  up  and  down  in  the 
hydraulic  joint  a. 

C C',  upper  and  lower  chambers,  with  inlet-valves  i v opening  inwards  to  take  in  the  air  from  the  ex- 
ternal air-shaft  E ; and  outlet-valves  o v opening  outwards  to  convey  the  air  to  the  shaft  D,  and  thence 
to  the  building  through  the  trunk  T. 

F,  furnace-room,  in  which  is  placed  the  boiler  with  four  square  fire-boxes////,  to  heat  the  water  for 
supplying  the  copper  cells  g,  when  it  is  required  to  warm  the  air  as  it  is  being  forced  into  the  building ; 
there  are  several  of  these  copper  heating  cells  placed  side  by  side,  with  narrow  spaces  between  for  the 
air  to  pass  through. 

H,  a water-engine,  acted  on  by  a column  of  water  on  one  side  of  the  piston,  which  is  brought  by  a 
pipe  h from  a cistern  placed  on  the  roof  60  feet  above ; j is  an  air-vessel  to  prevent  concussion  by  cut- 
ting off  the  water  suddenly  ; k,  geer  for  opening  and  shutting  the  eduction  and  induction  valves  ; l,  pis- 
ton and  connecting-rod. 

K,  balance-beam ; at  one  end  is  fixed  a chain  to  suspend  the  working  cylinder,  and  at  the  other  end 
is  another  chain  to  suspend  a balance-weight  m. 

WATCHMAKING,  or  Horology — the  construction  of  instruments  for  the  measurement  of  time. 
The  most  satisfactory  of  the  ancient  instruments  for  the  measurement  of  time,  was  the  Clepsydra  or 
water-clock ; in  which  the  hours  were  indicated  by  marks  upon  the  side  of  a vessel  filled  with  water, 
from  whose  bottom  a small  stream  was  allowed  to  flow  out.  As  the  water  in  the  vessel  ran  off,  its 
surface  sank ; and  its  height,  as  shown  by  the  marks,  indicated  the  time  that  had  elapsed.  It  was  soon 
found  that  the  water  does  not  run  from  such  an  orifice  with  a regular  velocity ; for,  when  the  vessel  is 
full,  the  pressure  of  the  fluid  is  much  greater  than  when  it  is  nearly  empty,  and  its  flow  will  be  pro- 
portionally faster. 


WATCHMAKING. 


821 


The  simplest  mode  of  overcoming  the  difficulty,  arising  from  the  unequal  flow 
of  water  through  an  orifice  in  the  bottom  of  a vessel,  is  shown  in  Fig.  3*740.  This 
clepsydra  consists  of  a cylinder  of  glass,  furnished  with  a float  a , which  carries  the 
siphon  h.  When  this  siphon  has  been  once  filled  with  water,  the  fluid  will  run 
out  at  the  cock  c,  until  the  whole  water  in  the  vessel  has  been  drawn  off.  The 
rate  at  which  the  water  is  discharged  may  be  regulated  by  the  cock  c ; and  as,  by 
the  connection  of  the  siphon  with  the  float,  the  mouth  of  the  pipe  is  always  at  the 
same  distance  below  the  surface  of  the  water,  the  quantity  will  always  be  the 
same,  whatever  be  the  height  of  the  fluid  in  the  vessel ; and  a scale  d,  on  its  side, 
divided  into  equal  parts,  will  always  indicate,  by  the  place  of  the  float,  the  lapse 
of  equal  intervals  of  time. 

All  these  instruments,  however,  were  but  rude  attempts  to  effect  that  which  is 
at  present  accomplished  far  more  perfectly  by  other  means.  By  the  combination 
of  wheel-work  (acting  upon  principles  already  described)  with  the  pendulum, 
the  laws  of  whose  vibration  have  also  been  explained,  clocks  rre  now  constructed, 
which  indicate  the  passage  of  time  with  a degree  of  accuracy  which  it  would  have 
been  thought  but  a short  time  since  quite  impossible  to  attain.  It  is  to  these  in- 
struments that  the  term  Clock  is-  now  restricted.  A watch  is  a portable  instru- 
ment, in  which  the  same  mechanism  is  employed  as  in  the  clock,  but  in  which, 
instead  of  a pendulum,  there  is  a balance-wheel,  whose  vibrations  are  regulated 
by  a spring.  Any  clocks  or  watches  might  be  termed  chronometers  or  time-measurers ; but  this  name 
is  now  appropriated  to  those  which  are  constructed  with  the  utmost  attention  to  the  perfection  of  every 
part,  and  with  means  for  compensating  certain  errors  to  which  they  are  liable.  The  most  perfect  clocks 
are  those  constructed  for  astronomical  observations,  in  which  the  greatest  possible  accuracy  is  required  ; 
and  hence  these  are  ordinarily  termed  astronomical  clocks.  It  must  be  borne  in  mind,  however,  that 
these  differ  from  ordinary  clocks  in  no  essential  particular;  though  their  appearance  is  often  puzzling 
to  those  who  see  them  for  the  first  time,  in  consequence  of  the  hour  and  minute  hands  being  fixed  on 
distinct  centres,  and  pointing  to  different  circles,  instead  of  revolving  about  the  same  centre,  and  point- 
ing to  the  same  circle,  as  in  ordinary  clocks.  Again,  the  most  perfect  watches  are  those  constructed 
for  the  purposes  of  navigation,  to  which  they  give  the  most  important  assistance ; and  these,  being 
much  larger  than  ordinary  watches,  though  constructed  on  the  same  principle,  are  distinguished  as  ma- 
rine chronometers. 

General  principles — Moving  and  regulating  powers. — The  object  of  clock-work  is  to  maintain  the  os- 
cillations of  a pendulum,  by  continually  communicating  to  it  a slight  additional  impulse ; and,  at  the 
same  time,  to  register  the  number  of  these  oscillations,  so  as  to  indicate  the  passage  of  time.  In  order 
to  effect  these  purposes,  a train  of  wheels  and  pinions  is  put  in  motion  by  a power  acting  on  the  first 
of  them,  whilst  the  last  is  connected  with  the  pendulum  by  a peculiar  contrivance,  termed  the  escape- 
ment. In  clocks  which  are  to  remain  stationary,  and  in  which  a saving  of  room  is  no  object,  the  moving 
power  is  a weight,  which  is  suspended  by  a string  coiled  round  a drum  or  barrel ; this  drum  carries 
the  first  wheel  of  the  clock,  and  imparts  to  the  train  the  movement  it  derives  from  the  gradual  descent 
of  the  weight.  If  the  whole  of  this  force  acted  on  the  wheel-work  alone,  which  it  would  do  if  the  es- 
capement were  taken  off,  the  weight  would  run  down  comparatively  fast,  and  the  train  would  be  caused 
to  move  with  great  rapidity.  But  a part  of  it  is  expended  in  keeping  up  the  vibrations  of  the  pendu- 
lum ; and  the  connection  of  this  with  the  wheel  work  is  such,  that  not  a tooth  of  the  latter  can  advance, 
unless  permitted  to  do  so  by  the  swing  of  the  pendulum.  Hence  a clock  will  not  go,  even  when  wound 
up,  unless  the  pendulum  be  set  in  motion ; but  when  its  vibrations  have  once  commenced,  they  will 
continue  until  the  string  has  been  unwound  from  the  barrel  by  the  descent  of  the  weight.  In  “ winding 
up"  the  clock,  we  raise  the  weight  by  again  coiling  its  string  round  the  barrel ; and  thus  communicate 
(as  it  were)  to  the  machine  a power  which  will  keep  it  in  action  for  a certain  limited  time.  It  would 
not  be  difficult  to  extend  that  time,  to  any  desired  amount,  by  adding  to  the  number  of  wheels.  Ordi- 
nary watches,  and  the  commonest  kinds  of  clocks,  require  to  be  wound  up  every  day ; chronometers 
for  ships,  and  house-clocks,  are  commonly  made  to  go  without  winding  for  a week ; many  clocks  have 
been  constructed  which  only  required  winding  once  a month  ; and  a few  have  been  made  to  go  for  a 
year.  It  will  be  easily  understood,  upon  the  principle  of  the  wheel  and  pinion,  that  the  greater  the 
multiplication  of  velocity,  the  greater  will  be  the  sacrifice  of  power ; so  that,  the  longer  a clock  is  made 
to  go — or,  in  other  words,  the  more  slowly  its  weight  is  made  to  descend — the  greater  must  be  the 
power  required  to  produce  the  same  effect ; and  the  weight  must  therefore  be  increased  in  the  same 
proportion. 

In  small  portable  clocks,  however,  and  in  watches  and  chronometers,  a weight  cannot  be  thus  em- 
ployed ; and  motion  is  given  to  the  wheel-work  by  means  of  a spring,  made  of  elastic  steel,  and  coiled 
in  a spiral.  One  end  is  secured  to  a fixed  point ; and  the  other,  in  the  effort  to  uncoil  itself,  will  carry 
round  any  thing  to  which  it  may  be  attached.  Now  it  is  easy  to  understand,  that  a spiral  spring,  in 
uncoiling  itself  after  having  been  tightly  wound,  exercises  a much  greater  degree  of  force  than  it  will 
do  when  it  has  become  slackened  ; and  therefore,  if  the  spring  were  immediately  connected  with  the 
wheel-work,  the  impulse  which  it  would  give  to  the  train  would  be  much  greater  at  the  beginning  than 
at  the  end  of  the  action.  An  attempt  has  been  made,  in  France,  to  correct  this  inequality,  by  making 
a variation  of  strength  in  different  parts  of  the  spring  itself,  so  that  it  shall  unwind  with  equal  force, 
whether  it  be  tight  or  slack ; and  if  this  can  be  effected,  the  spring  may  be  made  to  act  at  once  upon 
the  first  wheel  of  the  train,  as  shown  in  Fig.  3746,  where  O P is  the  spring,  of  which  the  outer  end  0 is 
fixed,  so  that  the  inner  end,  being  fixed  on  the  axis  or  spindle  of  the  wheel  N,  carries  this  round  in  its 
effort  to  uncoil  itself.  But  it  is  found  impossible  to  make  such  a correction  with  sufficient  accuracy ; 
and  a different  method  is  generally  adopted. 

The  spring  is  inclosed  within  a hollow  barrel  or  drum,  to  which  its  outer  end  is  attached ; and  the 


37 4C 


822 


WATCHMAKING. 


3741. 


inner  or  central  end  of  the  spring  is  attached  to  a fixed  axle.  Hence,  when  the  spring  has  been  coiled 
up,  its  elasticity  will  carry  round  the  barrel,  in  its  attempt  to  uncoil  itself.  The  barrel,  in  turning  round, 
pulls  a chain,  which  was  previously  coiled  round  a conical  axle, 
which  is  termed  the  fusee.  This  axle  carries  along  with  it  the  first 
wheel  of  the  train.  In  winding  up  the  watch,  we  coil  the  chain 
round  the  fusee,  and  draw  it  off  from  the  barrel ; by  which  action 
the  spring  within  the  barrel  is  coiled  up  and  its  power  becomes 
very  strong.  In  attempting  to  uncoil  itself,  it  pulls  the  chain,  which 
now  acts  upon  the  small  part  of  the  fusee.  When  it  has  gradually 
uncoiled  itself,  the  power  of  the  spring  is  weakened ; but  by  this  time  nearly  the  whole  of  the  chain  is 
coiled  upon  the  barrel,  having  been  unwound  from  the  fusee ; and  its  pull  or  strain  acts  upon  the  large 
part  of  the  fusee.  Now  upon  the  principles  stated  in  a former  part  of  this  work,  the  more  distant 
the  point  to  which  a force  is  applied  from  the  central  axis,  the  greater  will  be  its  power  of  giving 
the  required  motion.  When  the  spring  is  acting  most  strongly,  therefore,  its  power  is  applied  at  a far 
less  mechanical  advantage  than  when  its  power  is  nearly  exhausted ; and  thus  its  action  on  the  spindle 
of  the  fusee  is  equalized,  so  that  from  a variable  power  it  is  made  to  become  nearly  as  regular  as  that 
produced  by  the  descent  of  a weight. 

The  contrivance  by  which,  in  winding  up  a clock  or  watch,  we  can  turn  the  fusee 
without  influencing  the  wheel- work,  is  shown  in  Fig.  3742.  The  first  wheel  is  hol- 
lowed out  to  receive  the  small  ratchet-wheel  d,  of  which  the  teeth  are  so  cut  as  to  slant 
on  one  side,  but  to  be  upright  in  the  other.  In  the  same  hollow,  there  is  a movable 
click  or  ratchet  b,  which  is  pressed  down  by  the  spring  c.  Now  if  the  ratchet-wheel 
be  turned  in  the  direction  of  the  slanting  sides  of  its  teeth  (that  is,  from  left  to  right 
in  the  accompanying  figure)  it  will  not  carry  the  large  wheel  with  it ; fur  the  ratchet 
will  be  lifted  by  the  inclined  side  of  each  tooth,  and  will  consequently  pass  over  them 
all.  But  if  the  ratchet-wheel  be  made  to  turn  in  the  contrary  direction,  it  will  carry 
the  large  wheel  with  it ; for  the  upright  side  of  the  tooth  will  be  caught  by  the  ratchet ; so  that  any 
force  applied  to  the  ratchet-wheel  will  act  upon  the  ratchet,  and  consequently  upon  the  large  wheel 
with  which  it  is  connected.  Now  the  fusee  is  attached  to  the  ratchet-wheel;  and  hence,  when  the  fusee 
is  being  drawn  by  the  chain  in  the  direction  last  mentioned,  it  carries  round  the  large  wheel  with  it, 
and  gives  motion  to  the  whole  train ; whilst,  if  the  fusee  be  turned  in  the  contrary  direction,  as  it  is  by 
the  key  in  the  act  of  winding,  the  teeth  of  the  ratchet-wheel  lift  the  ratchet,  and  there  is  no  motion 
given  to  the  large  wheel.  The  same  contrivance  is  applied  in  clocks,  to  the  drum  round  which  is  coiled 
the  string  that  suspends  the  weight.  In  the  better  class  of  time-keepers,  whether  clocks  or  watches, 
there  is  another  contrivance  introduced  into  the  fusee,  by  which  the  train  of  wheels  is  kept  in  motion 
during  the  time  when  the  weight  or  spring  is  being  wound  up ; so  that  the  inaccuracy  that  would  be 
tfnerwise  occasioned  by  the  stoppage  of  the  movement  (which  any  one  may  observe,  who  notices  the 
*econd-hand  of  an  ordinary  clock  or  watch,  whilst  it  is  being  wound  up)  is  prevented.  This  contrivance 
is  termed  the  maintaining  power  or  going-fusee. 

Having  now  considered  the  moving  power,  by  which  the  train  of  wheels  is  kept  in  action,  we  shall 
examine  the  regulating  power,  by  which  its  action  is  controlled.  This,  in  all  clocks  now  constructed,  is 
the  pendulum  ; whilst  in  watches  and  chronometeus,  it  is  a wheel  termed  the  balance.  The  balance  of 
a watch  serves  the  same  purpose  as  the  pendulum,  having  the  advantage  of  occupying  much  less  space, 
and  of  acting  equally  well  in  almost  any  position.  It  consists  of  a wheel,  having  an  axle  which  ter- 
minates in  two  very  fine  pivots,  and  so  exactly  balanced,  as  to  be  capable  of  being  moved  with  a very 
small  impulse  in  either  direction.  To  the  axle,  however,  is  attached  one  end  of  a very  delicate  spiral 
spring ; of  which  the  other  end  is  attached  to  the  frame-work  of  the  watch,  as  shown  in  Fig.  3747.  Now 
the  action  of  this  spring  is  like  that  of  any  other  elastic  body ; it  will  produce  a certain  degree  of  re- 
sistance to  any  change  of  position  of  the  balance ; and  the  greater  the  alteration  of  its  place,  the  greater 
will  be  the  resistance,  until  at  last  the  force  which  set  the  balance  in  motion  is  overcome  by  it,  and  the 
rotation  ceases.  But  the  spring  has  been  so  much  displaced,  that  it  tends  to  bring  the  balance  back  to 
its  original  position,  with  a gradually  increasing  rapidity ; and  when  it  has  arrived  there,  the  force 
which  it  has  acquired  will  carry  it  as  far  on  the  other  side.  Again  this  force  is  resisted  by  the  spring, 
and  again  will  this  bring  back  the  balance  to  its  former  position. 

Thus  a balance,  provided  with  a spring  that  possesses  perfect  elasticity,  and  uninfluenced  either  by 
friction  or  the  resistance  of  the  air,  would  go  on  vibrating  backwards  and  forwards  without  cessation. 
But  three  retarding  influences  really  act  upon  it — want  of  perfect  elasticity  in  the  spring,  so  that  each 
reacting  force  is  somewhat  less  than  the  force  which  acted  on  it ; friction  of  the  pivots  ; and  resistance 
of  the  air.  Hence,  in  order  to  keep  up  these  vibrations,  it  is  necessary  that  a slight  additional  impulse 
should  be  continually  given  to  the  balance,  as  to  the  pendulum.  When  a balance  is  well  constructed, 
its  vibrations  become  almost  perfectly  isochronous,  whether  the  space  through  which  it  moves  be  long  or 
short ; hence  it  is  not  much  affected  by  moderate  differences  in  the  strength  of  the  impulses  given  to  it 
by  the  moving  power,  and  in  this  respect  has  even  advantages  over  the  pendulum.  It  is  found  advan- 
tageous to  construct  the  balance-spring  of  the  best  chronometers  not  in  the  form  of  a flat  spiral,  like 
that  of  the  common  watch,  shown  in  Fig.  3747,  but  in  that  of  a helix  or  cork-screw,  as  shown 
in  Fig.  3743.  And  the  balance  itself  is  not  a complete  wheel,  but  is  made  in  a peculiar  3~43. 

form,  which  will  be  described  hereafter,  for  the  purpose  of  compensating  the  influence  of  L_j=hi 

heat  or  cold  upon  the  spring.  The  time  occupied  by  each  vibration  of  the  balance  depends 
upon  the  strength  of  the  spring — other  things  being  supposed  equal;  and  the  strength  is  in- 
fluenced  by  the  length.  A short  spring,  of  equal  thickness  with  a long  one,  is  very  much  'w 
more  elastic;  hence,  by  shortening  the  balance-spring,  we  increase  its  elastic  force  ; whilst 
by  lengthening  it,  we  diminish  that  force.  The  greater  the  elastic  force,  the  shorter  will  be  the  vibra- 
tions of  the  balance,  and  the  less  will  be  the  time  occupied  by  each  of  them ; consequently  the  time- 


WATCHMAKING. 


828 


piece  will  gain  when  the  spring  is  shortened,  and  will  lose  when  its  length  is  increased.  It  is  by 
slightly  altering  the  length  of  this  spring  that  a time-keeper  is  regulated,  so  as  to  go  faster  or  slowe’ 
than  before. 

The  contrivance  by  which  the  pendulum  or  the  balance  is  connected 
with  the  moving  power,  is  termed  the  escapement.  The  simplest  form 
of  this  is  represented  in  Fig.  8714.  Let  xy  be  the  axis  on  which  the 
balance  turns,  or  from  which  the  pendulum  is  suspended ; projecting 
from  it  in  different  directions  are  two  leaves  c and  d,  which  are  termed 
pallets.  At  fb  is  seen  a crown-wheel,  turning  on  a perpendicular  axis 
oe;  its  teeth  are  cut  like  those  of  a saw ; and  the  direction  of  its  move- 
ment is  from  right  to  left, — that  is,  / moves  towards  b,  whilst  on  the 
further  side  i moves  towards  a,  and  a comes  gradually  round  to  f. 

This  wheel,  termed  the  balance-wheel,  is  connected  with  the  rest  of  the 
movement  by  the  pinion  on  its  axis,  as  will  be  shown  hereafter.  The 
pallets  are  so  placed,  with  regard  to  the  teeth  of  this  wheel,  that,  as 
the  axle  turns  from  one  side  to  the  other  by  the  swinging  of  the  pen- 
dulum or  the  vibrations  of  the  balance,  the  teeth  are  permitted  to 
escape  alternately  from  each  of  them,  and  thus  the  wheel  turns  round 
with  an  interrupted  motion.  In  the  figure,  the  pendulum  or  balance  is 
represented  as  at  the  extremity  of  its  excursion  towards  the  right,  and 
the  movement  of  the  axis  has  just  allowed  the  tooth  a to  escape  from 
the  pallet  c ; whilst  at  the  same  time  the  tooth  b is  just  about  to  fall 
on  the  pallet  d.  Now,  whilst  the  pendulum  or  balance  is  moving  to 
the  left,  that  is,  from  p to  g,  the  tooth  b still  presses  against  the  pallet 
d,  and  is  prevented  by  it  from  moving  further  on,  until  the  pallet  has 
changed  its  position  so  far  towards  the  left,  as  to  allow  the  tooth  to 
escape  from  it.  During  all  the  time  that  the  tooth  is  pressing  against 
the  pallet,  the  balance-wheel  is  communicating  to  the  pendulum  or 
balance,  through  its  means,  a part  of  the  power  by  which  it  is  itself  moved  ; and  thus  supplies  the  im- 
pulse required  to  keep  its  vibrations  up  to  the  proper  extent.  When  the  tooth  b has  escaped  from  d, 
the  tooth  i,  on  the  other  side  of  the  wheel,  will  drop  against  the  other  pallet  c;  and  will  remain  press- 
ing against  it,  in  like  manner,  until  the  return  of  the  pendulum  or  balance  to  the  position  represented 
in  the  figure  lifts  the  pallet  c sufficiently  to  allow  the  tooth  i to  escape  from  beneath  it,  as  a had  pre- 
viously done.  In  this  manner,  then,  the  wheel  is  allowed  to  advance  by  an  interval  of  half  a tooth  at 
each  vibration  of  the  pendulum  or  balance;  and  thus,  if  the  wheel  have  15  teeth,  and  the  pendulum 
vibrate  seconds,  it  will  make  one  revolution  in  half  a minute.* 

This  escapefnent  was  in  use  long  before  either  the  pendulum  or  balance-spring  was  applied  to  the 
regulation  of  time-keepers. 

The  escapement  first  used  to  connect  the  pendulum  with  the  clock,  precisely  resembled  that  which 
has  just  been  described.  The  axis  of  the  crown-wheel  was  vertical,  as  in  Fig.  3744 ; and  the  pendulum 
was  attached  to  the  horizontal  axis  x y.  In  fact,  there  was  no  essential  variation  from  that  representa- 
tion, except  that,  instead  of  a cross-bar  with  weights  p and  q at  either  end,  the  lower  portion  only,  x p, 
was  left,  to  serve  as  a pendulum.  It  was  found,  however,  that  the  extensive  vibrations  which  a pen- 
dulum must  make  when  so  hung  were  injurious  to  the  regular  going  of  the  clock  ; and  various  contriv- 
ances have  been  devised  to  prevent  this  source  of  error,  by  constructing  the  escapement  in  such  a man- 
ner that  the  pendulum  shall  make  shorter  vibrations.  These  have  completely  superseded  the  use  of 
this  original  escapement  (termed  the  crown-wheel  and  verge ) in  clock-work ; but  it  is  stdl  used  in 
watches,  where,  indeed,  it  is  an  object  to  make  the  vibrations  of  the  balance  as  extensive  as  possible. 
All  ordinary  watches  are  constructed  upon  this  plan  ; and  they  are  distinguished  as  vertical  watches, 
because  the  last  crown-wheel  has  a vertical  or  upright  position,  as  seen  in  Fig.  3745. 

The  first  watches  that  were  made  were  as  imperfect  as  the  early  clocks  ; and  differed  only  from  them 
in  being  made  upon  a smaller  scale,  and  in  the  use  of  a spring  instead  of  a weight,  as  the  moving  power. 
They  had  only  an  hour-hand  ; and  most  of  them  required  winding  twice  a day.  The  invention  of  the 
spiral  balance-spring  followed  the  application  of  the  pendulum  to  the  clock,  at  no  long  interval ; and 
thus  both  machines  were  made  to  receive  the  greatest  possible  improvement  in  the  principles  of  their 
construction,  at  a very  short  interval.  The  honor  of  this  invention  is  claimed  by  Huyghens,  the  A’obe 
Hautefeuille,  a Frenchman,  and  Dr.  Hooke.  There  can  be  little  doubt  that  it  is  really  due  to  the  last 
of  these  ; for  he  was  able  to  produce  proof  that  he  had  employed  the  balance-spring,  and  had  applied 
for  a patent  for  his  invention,  in  the  year  1658  ; whilst  the  claim  of  Huyghenswas  not  made  until  1674. 

Construction  of  ordinary  watches  and  clocks. — The  general  construction  of  an  ordinary  watch  will 
now  be  explained.  That  of  a clock  is  precisely  the  same,  whether  it  be  large  or  small ; with  the  ex- 
ception of  the  substitution  of  a weight  and  barrel  for  the  mainspring  and  fusee.  On  opening  an  ordi- 
nary watch-case,  we  see  that  the  wheel-work  is  for  the  most  part  contained  between  two  round  plates, 
which  are  connected  together  by  pillars.  One  of  these  plates  is  attached  to  the  dial ; but  there  is  a thin 
space  between  them,  which  is  occupied  by  the  wheel-work  that  connects  the  motion  of  the  hour  and 
minute  hands.  On  the  other  plate  is  a raised  portion,  beneath  which  the  balance  works. 

A general  view  of  the  work  of  a common  watch,  as  seen  from  the  side,  is  shown  in  Fig.  3745.  For 
convenience  of  display,  the  parts  are  all  arranged  in  one  line,  instead  of  being  disposed  in  a circle  at 
they  really  are  ; and,  in  order  to  make  them  more  distinguishable,  the  distance  of  the  two  plates,  be- 
tween which  most  of  the  work  is  contained,  is  much  increased  ; as  is  also  the  space  between  the  upper 


3744. 


* A crown-wheel  of  this  kind  must  always  have  an  odd  number  of  teeth  ; else  the  teeth  on  the  opposite  sides  would  norae 
against  the  pallets  at  the  same  time. 


824 


WATCHMAKING. 


plate  and  the  dial,  which  really  lie  close  together.  The  balance  is  seen  at  A ; and  on  its  axis  or  spindle  are 
the  two  pallets  p p,  which  together  constitute  what  is  termed  the  verge.  At  C is  seen  the  balance-wheel,  the 
teeth  of  which  resemble  those  of  a saw.  By  the  vibrations  of  the  balance,  the  teeth  of  this  wheel  are  per- 
mitted to  escape  from  each  of  the  pallets  alternately,  as  already  explained.  On  the  axis  of  the  bal- 
ance-wheel is  a pinion  d,  which  is  driven  round  by  the  crown-wheel  K.  This  wheel  is  termed  by  watch- 
makers the  contrate-wheel.  On  the  axis  of  this  last  is  a pinion  c which  works  into  the  third-wheel  L; 
and  the  axis  of  the  third-wheel  is  another  pinion  b which  works  into  the  wheel  M,  termed  the  centre- 
wheel,  from  its  position  in  the  centre  of  the  watch,  (see  Fig.  3746,  e.)  The  axle  of  this  wheel  passes  up 
through  the  centre  of  the  dial,  and  carries  the  minute-hand;  making  one  complete  revolution  in  an 
hour.  Upon  this  axle  is  placed  the  pinion  a which  works  in  the  great-wheel  N.  This  wheel  is  acted  on 
by  the  mainspring,  which  is  either  fixed  upon  its  own  axis,  as  represented  at  0 P in  this  figure,  or  is 
contained  within  a barrel  or  circular  box,  which  acts  by  means  of  a chain  upon  the  f usee  which  carries 
the  great-wheel,  as  already  explained.  Upon  the  axis  of  the  centre-wheel,  between  the  upper  plate 
and  the  dial,  is  fixed  the  pinion  Q;  and  this  drives  the  wheel  T.  Upon  the  spindle  of  this  wheel  is  a 
pinion  g which  works  into  the  wheel  Y.  The  axis  of  this  last  wheel  is  hollow,  so  as  to  allow  the  axis 
of  the  centre-wheel  to  pass  up  through  it ; and  upon  this  hollow  spindle  the  hour-hand  is  fixed. 

Z~io. 


It  !s  seen,  then,  that  in  the  watch,  as  in  the  clock,  the  moving  power  acts  on  a wheel  which  drives  a 
pinijn  ; that  this  pinion  carries  on  its  axis  awheel,  which  drives  another  pinion  carrying  another  wheel ; 
and  so  on.  Hence  there  is  a continual  increase  of  velocity,  and  at  the  same  time  a loss  of  power.  The 
revolution  of  the  balance-wheel  c is  very  rapid  in  proportion  to  that  of  the  great-wheel  N,  but  its  force 
is  less  in  the  same  proportion  ; so  that  the  slightest  interruption  (such  as  a thickening  of  the  oil  on  the 
teeth  and  pivots)  is  sufficient  to  check  the  movement  of  the  former,  whilst  the  power  of  the  latter,  com- 
municated to  it  by  the  spring,  is  sufficient  to  overcome  a considerable  resistance. 

Many  different  trains  may  be  adopted,  to  give  the  required  proportions  between  the  times  of  revolu- 
tion of  the  several  wheels  ; since  their  rates  depend  not  upon  their  absolute  number  of  teeth,  but  upon 
the  proportion  between  the  teeth  of  the  wheels  and  the  leaves  of  the  pinions.  The  centre-wheel  must, 
of  course,  make  one  revolution  in  an  hour ; the  balance-wheel  is  generally  made  to  turn  94  times  in  a 
minute  ; whilst  the  great-wheel  makes  one  revolution  in  about  four  hours ; so  that,  if  the  spring  can 
turn  it  seven  times  round,  the  watch  will  go  for  28  hours.  The  following  is  the  train  (or  arrangement 
of  the  number  of  teeth  in  the  wheels  and  joinions)  usually  adopted  in  common  watches.  The  great- 
wheel  N has  48  teeth,  and  the  pinion  a into  which  it  works  has  12  teeth ; consequently  this  pinion  will 
make  four  revolutions  whilst  the  wheel  revolves  once ; and  if  the  great-wheel  turn  round  in  four  hours, 
the  centre-wheel  will  make  one  revolution  every  hour.  The  centre-wheel  M has  54  teeth,  and  the  pinion 
b has  6 leaves  ; so  that  it,  together  with  the  third-wheel,  turns  round  nine  times,  whilst  the  centre-wheel 
revolves  once,  and  hence  makes  nine  revolutions  in  an  hour.  The  third-wheel  L has  48  teeth,  and  the 
pinion  c has  6 leaves,  so  that  the  velocity  is  again  multiplied  by  8 ; and  the  contrate-wheel  which  is  on 
the  axis  of  the  pinion  c will  make  (8X9)  72  turns  in  an  hour.  The  contrate-wheel  K also  has  48  teeth, 
and  the  pinion  d into  which  it  works  has  6 teeth,  so  that  a further  multiplication  of  velocity  takes  place, 
to  the  amount  of  8 times ; and  the  balance-wheel  C,  which  is  carried  round  by  the  pinion  d,  turns 
(72X8)  576  times  in  an  hour,  or  about  9-J  times  in  a minute.  The  balance-wheel  0 has  15  teeth,  and 
naif  of  one  of  these  escapes  with  every  turn  of  the  balance  ; hence  there  are  about  (94X15X2)  305 
impulses  given  to  the  balance  in  a minute,  so  that  each  of  its  vibrations  occupies  60-305th  parts,  or  about 
l-5th  of  a second. 

It  is  often  an  object,  however,  to  cause  the  fourth  or  contrate  wheel  to  revolve  exactly  once  in  a 
minute ; so  that  its  spindle  may  carry  a hand  which  shall  indicate  seconds  on  the  dial.  This  may  be 
done  by  making  the  balance  perform  exactly  five  beats  in  a second,  and  by  giving  15  teeth  to  the  bal- 
ance-wheel, 6 leaves  to  its  pinion,  and  60  teeth  to  the  contrate-wheel.  The  contrate-wheel,  in  turning 
once  round,  causes  the  balance-wheel  to  revolve  10  times  ; and  hence  the  number  of  escapes  its  teeth 
will  make  is  (10X15X2)  300  in  a minute,  or  one  in  every  fifth  part  of  a second.  Or  the  balance  may 
be  adjusted  to  beat  nine  times  in  two  seconds ; and  then  the  number  of  teeth  in  the  contrate-wheel  must 
be  nine  times  that  of  the  pinion  it  turns — that  is,  54  to  6,  or  63  to  7.  Or  the  number  of  beats  may  be 
four  in  a second ; and  for  this  arrangement  the  contrate-wheel  must  have  eight  times  the  number  of 
teeth  in  the  pinion  it  turns — that  is,  48  to  6,  or  54  to  7.  When  the  contrate-wheel  is  to  be  thus  made 
to  turn  60  times  in  an  hour,  instead  of  72,  (as  in  the  ordinary  train,)  the  number  of  teeth  in  the  centre- 
wheel  and  third-wheel,  and  the  number  of  leaves  in  the  pinions  they  tun},  must  be  regulated  accord- 


WATCHMAKING. 


825 


ingly.  The  usual  plan  is  to  give  the  centre-wheel  64;  teeth,  and  to  the  pinion  it  turns  8 leaves  ; so 
that  this  pinion,  carrying  with  it  the  third-wheel,  revolves  eight  times  for  each  turn  of  the  centre-wheel 
The  third-wheel,  having  60  teeth,  works  into  a pinion  of  8 leaves ; and  this  last,  carrying  the  contrate- 
wheel,  turns  7-J  times  for  each  revolution  of  the  third-wheel.  Hence  the  contrate-wheel  turns  (8X7T) 
60  times  for  each  revolution  of  the  centre-wheel ; and  as  the  latter  makes  one  revolution  in  an  hour,  so 
does  the  former  complete  one  in  each  minute. 

3746.  3747. 


llm  mode  in  which  the  parts  of  a watch  are  actually  arranged  is  shown  in  ? r.  3746,  representing  the 
interior  of  a watch,  from  which  one  of  the  plates  has  been  removed,  seen  from  above.  Here  a is  the 
barrel,  containing  the  mainspring  coiled  within  it.  By  the  elasticity  of  this,  the  barrel  is  made  gradu- 
ally to  wind  upon  itself  the  chain  b,  which  was  previously  coiled  around  the  fusee,  and  thus  to  give  mo- 
tion to  that  fusee,  which  carries  round  with  it  the  great- wheel  c.  The  pinion  turned  by  the  great-wheel 
is  seen  at  d ; and  this  carries  on  its  axis  the  centre-wheel  e.  It  is  the  spindle  of  this  wheel  which,  pro- 
longed through  the  dial,  carries  the  minute-hand.  The  wheel  e turns  the  pinion  f which  carries  round 
the  third-wheel  g;  and  this  works  into  the  pinion  (which  cannot  be  shown  is  this  view)  that  carries 
round  the  contrate-wheel  h.  This  wheel  turns  the  pinion  i,  which  carries  round  the  balance-wheel-  k. 
The  balance  itself  and  the  verge  are  supposed  to  have  been  removed  with  the  upper  plate,  which  is 
shown  separately  in  Fig.  3747.  This  gives  a view  of  the  back  of  the  works  of  an  ordinary  watch,  as 
seen  when  the  case  is  opened.  The  balance  is  seen  at  p ; its  spiral  spring  is  shown  by  s ; and  the  end 
of  this  is  fixed  at  t.  In  order  to  regulate  the  length  of  this  spring,  so  as  to  bring  the  vibrations  of  the 
balance  precisely  to  their  required  number  in  a minute,  there  is  a movable  piece,  marked  o,  through  a 
slit  in  which  the  balance-spring  passes.  This  piece  (which  is  termed  the  curb)  can  be  made  to  travel 
towards  one  side  or  the  other,  by  means  of  a wheel  acted  on  by  the  circular  scale  r,  to  which  the  key 
is  applied  for  the  purpose  of  regulating  the  watch.  The  position  of  the  curb  o determines  the  acting 
length  of  the  balance-spring,  since  the  part  between  o and  t is  cut  off,  as  it  were,  from  the  rest.  Hence, 
if  the  curb  be  moved  towards  t,  the  acting  length  of  the  spring  is  increased •,  whilst,  if  it  be  moved  away 
from  t,  the  spring  is  shortened.  The  effect  of  this  alteration 
has  been  already  explained.  At  q is  seen  the  square  end  of 
the  spindle  of  the  fusee,  to  which  the  key  is  applied  for  wind- 
ing the  chain  off  the  barrel.  In  Fig.  3748  is  shown  the  work 
which  lies  between  the  dial  and  the  plate  on  which  it  rests, 
having  for  its  object  to  give  motion  to  the  hour-band.  The 
wheel  x is  turned  by  a pinion  on  the  axis  of  the  centre-wheel, 
concealed  in  this  figure  by  the  wheel  v,  but  shown  at  Q in  Fig. 

3745.  The  wheel  x carries  round  with  it  the  pinion  w,  which 
gives  motion  to  the  wheel  v ; and  on  the  hollow  spindle  of 
this  last  the  hour-hand  is  fixed.  The  number  of  teeth  in  these 
wheels  and  pinions  must  be  so  proportioned,  therefore,  that  the 
wheel  v shall  turn  round  with  only  l-12th  of  the  velocity  of 
the  central  axis.  Thus,  suppose  the  centre-pinion  to  have  15 
teeth,  and  the  wheel  x to  have  60  teeth,  the  latter  will  only 
revolve  once  whilst  the  former  revolves  four  times.  Again,  if 
the  pinion  w have  20  teeth,  and  the  wheel  v have  60  teeth,  the 
wheel  v will  turn  round  once  whilst  the  pinion  w revolves  three 
times,  and  the  central  pinion  (3X4)  12  times. 

It  is  not  exactly  correct  to  say,  however,  that  the  central  pinion  and  the  minute-hand  are  fixed  upon 
the  spindle  of  the  centre-wheel ; for  if  they  were,  the  hands  could  not  be  moved  without  turning  the 
centre-wheel,  and  we  should  not  be  able  to  set  them,  without  disturbing  the  whole  movement  of  the 
vratch.  I here  is  a very  simple  provision  for  permitting  this  to  be  done.  The  pinion  and  minute-hand 
are  fixed,  not  to  the  axis  of  the  centre-wheel,  but  to  a hollow  spindle  which  is  fitted  upon  this,  and  car- 
ried round  by  friction,  so  long  as  there  is  no  opposing  resistance.  When  we  set  the  watch,  however,  the 
central  axis  remains  unmoved,  and  we  merely  turn  round  the  hollow  spindle  which  carries  the  minute- 
hand  and  the  pinion.  This  pinion  acts  upon  the  wheel  x,  which,  through  the  pinion  w and  the  wheel  y, 
turns  the  hour-hand  one-twelfth  of  the  amount  that  the  minute-hand  has  been  moved  ; and  thus  the  two 
are  always  made  to  turn  conformably  to  each  other  whether  they  be  carried  round  bv  the  going  of  thy 


3748. 


820 


WATCHMAKING. 


watch,  or  by  the  action  of  the  key  in  setting  it.  If  the  face  of  any  ordinary  watch  1 e examined,  thert 
will  be  seen  a small  round  spindle  projecting  in  the  centre.  This  is  the  spindle  of  the  centre-wheel 
Inclosing  this  is  the  first  hollow  spindle,  which  carries  the  minute-hand,  and  which  is  squared  at  the 
top  to  receive  the  key ; and  this  is  again  inclosed  in  a second  hollow  spindle,  to  which  the  hour-hand  is 
atl  ached.  These  are  seen  in  Fig.-  37-15.  Precisely  the  same  means  are  adopted  to  connect  the  motion 
of  the  two  hands  in  ordinary  clocks  ; but  where  great  accuracy  is  required,  as  in  clocks  used  for  astro- 
nomical observations,  it  is  desirable  to  avoid  unnecessary  friction  as  completely  as  possible.  This  is  done 
by  making  the  hour-hand  turn  on  a different  centre  from  the  minute-hand  ; and  the  former  receives  its 
motion  from  the  latter,  by  means  of  a wheel  containing  12  times  as  many  teeth  as  the  pinion  which 
turns  it,  and  therefore  making  its  revolution  in  12  times  the  period.  In  astronomical  clocks,  however, 
the  hour-circle  is  not  unfrequently  divided  into  21  parts,  instead  of  12;  and  the  hand  requires  a whole 
day  and  night  to  traverse  it.  The  object  of  this  is  to  avoid  any  mistake,  arising  from  the  same  numbers 
being  repeated  twice  between  noon  and  noon,  or  midnight  and  midnight.  Some  clocks  have  been  con- 
structed, especially  at  Venice,  to  strike  all  the  numbers,  from  1 to  21 ; but  in  this  there  can  be  no  ad- 
vantage. 

The  mechanism  of  a portable,  eight-day  clock  is  represented  in 
Fig.  3719.  Of  the  two  barrels,  fusees,  and  trains  of  wheel-work 
here  seen,  the  one  on  the  right-hand  side  alone  has  for  its  office  the 
measurement  of  time.  The  other  is  called  the  striking-train,  and 
its  office  will  he  separately  considered.  The  works  are  arranged,  as 
in  the  watch,  between  the  plates,  in  which  are  holes  for  the  pivots  of 
the  axles  of  the  various  wheels,  <fcc.  The  front  plate  is  attached  to 
the  dial,  with  an  interval  in  which  the  hour-hand  movement  is  con- 
tained, as  in  the  watch.  This  interval  also  contains  the  mechanism 
by  which  the  striking  is  regulated.  The  dial  and  the  front  plate  are 
supposed  to  be  here  removed,  so  as  to  give  an  uninterrupted  view  of 
the  train  of  wheels.  The  back  plate  is  shown  by  the  letters  ABCD. 

The  springs  inclosed  in  the  barrels  E E give  motion  to  the  fusees  F F, 
as  in  the  watch,  either  by  a chain  or  a piece  of  catgut.  The  main- 
wheel  a of  the  going-train  has  96  teeth,  and  this  acts  on  the  centre- 
wheel  pinion  k,  having  8 leaves.  This  pinion  carries  with  it  the  cen- 
tre-wheel b ; and  on  the  same  spindle,  as  in  the  watch,  the  minute- 
hand  is  placed.  The  centre-wheel  b acts  on  the  pinion  l ; and  this 
carries  round  with  it  the  third-wheel  c.  This  third-wheel,  in  its  turn, 
acts  on  a pinion  (not  seen  in  the  engraving)  which  carries  round  the 
scape-wheel  <7;  and  this  wheel,  acting  on  the  pendulum  by  the  pal- 
lets n o of  the  escapement,  communicates  to  it  the  impulse  received 
from  the  spring,  whilst  its  own  motion  is  entirely  determined  by  the  duration  of  the  vibrations  of  the 
pendulum.  For  if,  on  the  very  same  escapement,  we  were  to  hang  a pendulum  of  9f  inches,  another  of  39 
inches,  and  another  of  13  feet,  the  duration  of  each  beat,  and  consequently  the  interval  between  the  escape ot 
each  tooth,  would  be  half  a second  in  the  first  pendulum,  a second  in  the  next,  and  two  seconds  in  the  last. 

The  number  of  teeth  in  the  wheels  and  pinions,  therefore,  must  depend  upon  the  length  of  the  pen- 
dulum. Thus,  for  a pendulum  vibrating  seconds,  the  number  of  teeth  in  the  scape-wheel  is  usually 
30,  since,  as  the  wheel  only  advances  to  the  amount  of  half  a tooth  at  each  escape,  its  revolution  is  then 
performed  in  a minute,  and  it  may  be  made  to  carry  a seconds-hand.  If  the  centre-wheel  and  the  third- 
wheel  have  64  and  60  teeth  respectively,  and  their  pinions  have  8 leaves,  the  multiplication  of  velocity 
will  be  (60  X 64  ~~  8 X 8)  exactly  60  ; so  that  the  scape-wheel  will  turn  round  60  times  for  one  revolution 
of  the  minute-hand.  Where  the  pendulum  vibrates  half-seconds,  however,  it  would  be  necessary  to 
make  the  scape-wheel  with  60  teeth,  if  it  be  required  to  perform  but  one  revolution  in  a minute.  Small 
portable  clocks,  however,  such  as  those  designed  for  a table  or  mantel-piece,  are  not  made  with  a sec- 
onds-hand ; and  in  these  the  scape-wheel  is  made  with  a small  number  of  teeth,  and  revolves  in  a shorter 
time  ; the  number  of  teeth  in  the  wheels  and  pinions  which  connect  it  with  the  centre-wheel  being  ad- 
justed accordingly.  In  a clock  now  before  the  author,  the  centre-wheel  has  84  teeth.  This  turns  a 
pinion  of  7 leaves,  which  must  therefore  revolve  12  times  as  fast,  or  once  in  every  five  minutes.  This 
pinion  carries  round  with  it  the  third-wheel,  which  has  77  teeth  in  it ; and  the  latter  drives  the  scape- 
wheel  by  a pinion  of  7 leaves,  so  that  a velocity  of  1 1 'to  1 is  gained.  The  scape-wheel  goes  round, 
therefore,  1 1 times  in  five  minutes,  or  once  in  somewhat  less  than  half  a 
minute.  It  has  32  teeth  ; and  the  pendulum,  being  not  quite  eight  inches 
• ong,  allows  each  to  escape  in  rather  less  than  half  a second. 

Clock-escapements.- — The  construction  of  the  anchor-pallet  escapement, 

To  called  from  its  having  some  resemblance  to  an  anchor,)  which  is 
now  applied  to  nearly  all  ordinary  clocks,  is  seen  in  Fig.  3750.  The 
scape-wheel  has  its  teeth  cut  upon  its  edge,  and  not  raised  up  as  they 
are  in  the  scape-wheel  of  a verge  watch.  The  centre,  from  which  the  pen- 
dulum is  suspended,  is  seen  at  A;  and  the  same  point  is  the  centre  of  mo- 
tion of  the  piece  of  metal  ABC,  which  is  termed  the  crutch,  the  extremi- 
ties B and  O being  the  pallets.  This  crutch  is  usually  not  fixed  to  the  pen- 
dulum, since  it  is  convenient  to  detach  the  latter,  when  the  clock  is  to  be 
moved  from  one  place  to  another  ; but  it  is  so  connected  with  it,  that,  as  the 
pendulum  swings  from  side  to  side,  the  two  ends  of  the  crutch  move  up 
and  down.  The  position  of  the  crutch  shown  in  the  figure  is  that  which  cor- 
responds with  the  direction  A E of  the  pendulum.  If  the  pendulum  be 
jarried  to  A F,  the  end  B of  the  crutch  would  be  raised  still  more ; whilst  if  it  swing  to  the  other  sid" 


3750. 


3749. 


WATCHMAKING. 


827 


A.  F',  the  end  B of  the  crutch  would  sink  between  the  teeth  of  the  scape-wheel,  whilst  the  end  C would 
be  raised  quite  clear  of  them.  The  scape-wheel  is  driven  by  its  pinion  in  the  direction  of  the  arrows  ; 
but  its  motion  sutlers  interruption  by  the  alternate  locking  and  disengagement  of  its  teeth  against  the 
pallets  of  the  crutch ; and  as  the  movements  of  these  depend  upon  the  pendulum,  its  time  of  vibration 
regulates  the  period  in  which  the  wheel  revolves. 

In  the  position  of  the  escapement  shown  in  the  figure,  the  pendulum  is  to  be  supposed  to  be  at  E, 
and  to  be  moving  towards  F.  Now  the  elevation  of  the  pallet  B,  against  whose  under  side  tooth  5 -was 
previously  pressing,  has  disengaged  the  point  of  that  tootli ; and  the  scape-wheel  is  consequently  at 
liberty  to  move  onwards.  But  it  is  prevented  from  doing  so  to  more  than  the  interval  of  half  a tooth  ; 
for  whilst  the  pallet  B was  being  withdrawn  from  the  space  between  5 and  6,  the  pallet  C was  sinking 
into  the  interval  between  2 and  3 ; consequently  the  wheel's  revolution  is  checked  by  the  fall  of  the 
point  of  tooth  2 against  the  upper  surface  of  the  pallet  0.  But  as  the  pendulum  continues  to  swing  to 
F,  the  pallet  C is  still  further  lowered  ; and  it  gives  a slight  backward  impulse  to  the  tooth  which  was 
resting  upon  it,  and  consequently  to  the  whole  wheel.  This  backward  movement,  termed  the  recoil, 
may  be  seen  in  the  seconds-hand  of  any  common  clock;  this  hand  being  attached  to  the  scape-wheel, 
and  carried  round  with  it.  Having  completed  its  swing  to  F,  the  pendulum  begins  to  move  back  again, 
and  in  doing  so  it  is  assisted  by  the  pressure  of  tooth  2 against  the  upper  surface  of  the  pallet  C.  This 
pallet  is  gradually  withdrawn  from  the  tooth  that  rests  upon  it,  so  that  this  at  last  escapes.  But  in  the 
mean  time  the  pallet  B has  sunk  into  the  interval  between  5 and  4 ; so  that  when  tooth  2 has  escaped 
from  the  pallet  C,  tooth  4 drops  against  the  under  side  of  pallet  B.  The  further  motion  of  this  pallet, 
which  continues  until  the  pendulum  has  reached  the  position  F',  again  causes  the  recoil  of  the  wheel ; 
but  when  the  pendulum  begins  to  swing  back  towards  B,  it  is  again  assisted  by  the  moving  power  of 
the  wheel,  which  tends  to  make  the  tooth  4 (now  resting  on  pallet  B)  press  that  pallet  towards  the 
left.  When  the  pendulum  lias  moved  to  E,  tooth  4 escapes,  as  5 had  done  before  ; and  tooth  1 falls 
upon  the  pallet  13,  as  2 previously  did ; tooth  5 having  in  the  mean  time  moved  on  to  6,  and  tooth 
2 to  3. 


The  objection  to  the  recoil  escapement  consists  chiefly  in  this,  that  the  impelling  power  of  the  weight, 
communicated  through  the  train  of  wheels,  is  acting  on  the  pendulum,  by  means  of  the  inclined  surfaces 
of  the  pallets,  during  the  whole  of  each  of  its  vibrations.  Hence,  any  inequalities  in  the  moving  power 
are  liable  to  produce  a considerable  effect  on  the  pendulum,  so  as  to  vary  its  rate  of  vibration  ; and  such 
inequalities  are  continually  liable  to  occur  from  various  causes.  It  was  to  avoid  this  source  of  error  that  the 
dead-beat  escapement  was  invented  by  Graham,  a celebrated  cloekmaker  at  the  commencement  of  the  last 
century,  to  whom  we  owe  also  the  invention  of  the  mercurial  pendulum.  The  peculiarity  of  this  escape- 
ment consists  in  the  form  of  the  pallets  ; the  surface  of  each  of  which  is  partly  a circle,  having  the  point 
of  suspension  for  its  centre,  and  partly  an  inclined  plane.  The  construction  and  action  of  this  escape- 
ment are  seen  in  Fig.  3751.  The  centre  of  suspension  is  at  A ; whilst  A B and 
A C are  the  two  legs  of  the  crutch,  moving  from  side  to  side  with  the  vibra- 
tions of  the  pendulum,  whose  line  of  direction  is  shown  by  A D.  The  scape- 
wheel  moves  in  the  direction  shown  by  the  arrow  ; and  the  position  of  the 
whole  is  seen  to  be  such  in  Fig.  3751,  that  the  pendulum  having  nearly 
reached  the  limit  of  its  vibration  on  the  left  hand,  the  tooth  6 has  escaped 
from  the  pallet  B,  having  just  slid  off  the  inclined  portion  of  its  surface,  of 
which  the  dotted  line  b shows  the  direction.  The  tooth  2 now  drops  against 
the  pallet  c,  and  the  further  motion  of  the  scape-wheel  is  thereby  checked. 

The  pendulum  then  begins  to  vibrate  towards  the  right,  carrying  with  it  the 
crutch;  so  that  the  pallet  B enters  the  interval  between  the  teeth  5 and  6; 
whilst  the  pallet  C is  drawn  out  from  the  interval  between  1 and  2.  During 
this  movement,  however,  the  scape-wheel  remains  at  rest ; for  so  long  as  the 
tooth  2 bears  upon  the  circular  part  of  the  pallet  C,  it  does  not  either  ad- 
vance or  recede,  and  its  moving  power  is  not  communicated  to  the  pendu- 
lum. But  as  soon  as  the  pallet  G has  been  sufficiently  withdrawn  for  the  Dl 

edge  of.  the  tooth  2 to  press  against  the  inclined  plane,  of  which  the  dotted 

line  c is  a continuation,  the  wheel  is  allowed  to  move  forwards  ; and  it  communicates  an  impulse  to  the 
pendulum,  which  aids  it  in  its  vibration. 

When  the  pallet  C has  been  completely  withdrawn  by  the  continued  motion  of  the  pendulum,  the 
tooth  2 is  entirely  disengaged  from  it  ; and  the  wheel  would  move  onwards,  but  for  the  check  it  re- 
ceives on  the  other  side.  Whilst  the  pallet  C was  being  withdrawn,  the  pallet  B was  entering  the 
interval  between  5 and  6 ; consequently,  just  as  the  tooth  2 is  disengaged  from  the  former,  tooth  5 falls 
upon  the  upper  surface  of  the  latter. 

The  pendulum,  having  completed  its  vibration  towards  the  right,  commences  its  return ; and  whilst 
it  is  moving  in  that  direction,  the  tooth  5 remains  at  rest,  and  the  whole  wheel  is  consequently 
stationary,  until  the  pallet  B has  been  withdrawn  far  enough  for  the  tooth  to  rest  against  tbo  inclined 
portion  of  its  surface.  When  it  does  so,  the  wheel  again  begins  to  move  onward,  and  gives  the  pendu- 
lum a fresh  impulse,  in  a contrary  direction  to  the  first.  When  the  pallet  B shall  have  been  completely 
withdrawn,  and  the  pendulum  have  arrived  at  D,  the  tooth  5 will  be  disengaged,  and  will  take  up  the 
position  of  the  tooth  6 in  Fig.  3751. 

Hence,  during  a large  part  of  each  vibration  of  the  pendulum,  the  scape-wheel  is  stationary,  in  con- 
sequence of  the  resting  of  its  teeth  upon  the  circular  portion  of  the  pallets  ; and  it  is  only  whilst  they 
are  sliding  down  the  inclined  plane,  which  action  occupies  but  a small  proportion  of  the  whole  time, 
that  the  wheel  moves  on.  Its  movement,  therefore,  as  indicated  by  the  seconds-hand,  is  a succession 
of  jerks,  very  different  from  the  recoiling  movement  of  the  scape-wheel  of  the  ordinary  clock.  As  the 
dead-beat  escapement  is  the  one  now  universally  adopted  in  this  country  for  the  best  kind  of  clocks 
whether  those  designed  for  astronomical  purposes  or  for  regulators  of  time,  (such  as  almost  every  watcb 


WATCHMAKING. 


8-28 


3752. 


maker  possesses,)  and  also  in  many  large  public  clocks,  most  of  the  readers  of  this  description  may  ob 
tain  the  opportunity  of  observing  its  action. 

Compensation  pendulum. — Although  every  part  of  a clock  may  be  constructed  with  the  greatest  per- 
fection, its  performance  will  be  very  inaccurate,  unless  it  be  provided  with  the  means  of  compensating 
for  those  changes  which  result  from  an  alteration  of  temperature.  A very  minute  difference  in  the 
length  of  a pendulum  will  produce  a decided  influence  upon  the  rate  of  going  of  a clock.  For  if  this 
alteration  be  so  trifling  as  to  cause  an  increase  or  decrease  of  the  time  of  each  vibration  by  l-1440th 
part  of  its  whole  length,  it  will  occasion  the  clock  to  lose  or  gain  a minute  in  every  twenty-four  hours — 
a minute  being  the  l-1440th  part  of  a day.  The  alteration  in  length  required  to  produce  a difference 
of  a second  a day  will  therefore  be  almost  inconceivably  small,  and  such  as  a trifling  variation  in  the 
temperature  of  the  air  would  be  sufficient  to  produce.  The  amount  will  vary  with  the  material  em- 
ployed. If  the  pendulum-rod  be  of  dry  varnished  deal,  an  alteration  of  the  temperature  to  the  amount 
of  10°  (Fahr.)  will  only  affect  its  going  by  one  second  a day.  But  if  iron  wire  be  employed,  the  al- 
teration is  three  times  as  great ; and  it  is  increased  to  five  seconds  by  employing  brass.  Hence,  to  in- 
sure the  accurate  going  of  a clock,  some  means  must  be  devised  to  compensate  for  this  source  of  error. 

This  compensation  is  sometimes  effected  in  clocks  by  the  appa- 
ratus termed  the  mercurial  pendulum,  the  form  of  which  is  shown 
in  the  annexed  drawing,  Fig.  3752.  The  rod  of  the  pendulum  con- 
sists of  a flat  piece  of  steel,  which  is  formed  at  the  bottom  into  a kind 
of  stirrup,  to  carry  a glass  jar  securely  fixed  to  it.  This  jar  is  partly 
filled  with  mercury,  which  serves  as  the  weight  or  bob  of  the  pendu- 
lum. When  a change  of  temperature  causes  the  steel  rod  to  expand 
downwards  from  its  point  of  suspension,  it  also  occasions  an  expan- 
sion of  the  mercury  upwards  from  the  bottom  of  the  jar ; and  as  the 
expansion  of  any  given  bulk  of  mercury  is  many  times  greater  than 
that  of  the  same  bulk  of  steel,  the  rise  of  the  mercury  in  the  jar 
counteracts  the  lowering  of  the  whole  jar  by  the  expansion  of  the 
rod ; so  that  the  place  of  the  centre  of  oscillation  remains  the  same, 
and  the  rate  of  vibration  continues  unaffected.  The  quantity  of  mer- 
cury requisite  for  the  purpose  can  only  be  accurately  determined  by 
experiment ; but  in  general  it  will  be  found  that  the  height  of  the 
column  should  be  about  6'7  inches.  If  the  column  is  not  high  enough, 
its  expansion  will  not  counteract  that  of  the  steel  rod;  if  it  be  too 
high,  the  pendulum  will  be  over-compensated,  so  that  heat  will  cause 
it  to  gain,  and  cold  to  lose, — contrary  to  the  usual  rule.  Of  course 
what  has  been  said  of  the  mode  in  which  the  two  expansions  balance 
each  other,  equally  applies  to  the  contractions  which  will  take  place, 
in  the  steel  rod  and  in  the  mercury,  from  the  operation  of  cold.  The 
absolute  length  of  the  pendulum  is  adjusted  by  a screw  at  D,  by 
turning  which  the  stirrup  is  raised  or  lowered  upon  the  rod.  At  C is  a projecting  index,  which  points 
to  a circular  scale  below,  by  which  the  pendulum’s  arc  of  vibration  may  be  observed  from  time  to 
time. 

A very  simple  compensation  pendulum,  which  may  be  applied  to  any  clock  at  the  most  trifling  ex- 
pense, consists  of  a wooden  rod,  dried  and  varnished ; carrying  at  its  lower  end,  by  way  of  bob,  a hollow 
leaden  cylinder,  which  rests  on  a serew  at  the  bottom  of  the  rod.  If  the  rod  be  made  about  46  inches 
long,  and  the  lead  cylinder  about  14  inches  long,  it  will  nearly  vibrate  in  seconds,  (since  the  centre  of 
oscillation  will  be  at  about  the  middle  of  the  leaden  cylinder,  and  therefore  at  about  7 inches  from  the 
end  of  the  rod ;)  and  the  expansion  of  the  lead  upwards  is  sufficient,  or  nearly  so,  to  counteract  that  of 
the  rod  downwards.  There  is  another  very  ingenious  compensation  pendulum,  which  was  invented  by 
Harrison,  to  whom  we  are  so  much  indebted  for  his  improvements  in  chronometers.  This  is  termed, 
from  its  form  and  aspect,  the  gridiron  pendulum.  (See  Pendulum.)  Many  other  contrivances  have 
been  devised  for  the  same  purpose ; but  they  are  not  superior  to  these. 

The  regular  going  of  a clock  will  partly  depend  also  upon  the  steadiness  with  which  it  is  fixed ; and, 
it  is  therefore  desirable  that  a clock  for  scientific  purposes  should  be  as  firmly  supported  as  possible. 
After  all,  however,  there  is  one  source  of  error  for  which  it  does  not  seem  easy  to  devise  a remedy; — 
this  is  the  varying  density  of  the  air,  which  wall  produce  a variation  in  the  resistance  to  the  motion  of 
the  pendulum.  When  the  air  is  dense,  as  shown  by  a rise  of  the  mercury  in  the  barometer,  the  resist- 
ance is  increased,  and  the  clock  will  go  slower ; the  contrary  result  occurs  when  the  pressure  of  the 
air  is  diminished,  as  shown  by  a fall  of  the  mercury.  An  attempt  has  been  made  to  correct  this  error, 
by  attaching  small  barometers  to  the  sides  of  the  pendulum ; it  being  intended  that  the  rise  of  the  mer- 
cury in  the  tube,  by  slightly  raising  the  centre  of  oscillation,  should  counterbalance  the  effect  of  the 
increased  resistance.  This  ingenious  idea  has  not  yet  been  properly  applied  to  practice.  To  show  the 
perfection  at  which  clockmaking  has  arrived,  it  may  be  mentioned  that  several  clocks  are  now  going, 
whose  errors  are  less  than  l-10th  of  a second  daily. 

Watch  escapements. — As  in  the  clock  it  is  desirable  to  remove  the  pendulum  as  much  as  possible 
from  the  constant  influence  of  the  moving  power,  so  is  it  desirable  in  the  watch  to  withdraw  the  balance 
from  the  same  influence,  slight  variations  of  which  (such  as  must  be  continually  occurring  from  various 
causes)  must  otherwise  greatly  affect  its  regularity.  In  order  to  effect  this,  various  kiuds  of  escape- 
ments have  been  devised. 

The  vertical  escapement  is  the  oldest  escapement  of  all,  which,  after  having  first  been  adopted  in 
flocks,  was  applied  in  the  construction  of  watches.  Its  nature  is  explained  by  Fig.  3754,  (a  contrate- 
whcel,  b escape  or  wheel,  c the  verge,  d the  balance.)  That  which  is  here  called  the  balance-wheel 
was,  when  originally  applied  in  a horizontal  position  to  the  primitive  clocks,  termed  the  croVn-wheel 


WATCHMAKING. 


829 


evidently  from  its  resemblance  to  a crown : this  same  wheel,  when  employed  in  the  watch,  (supposing 
the  latter  to  be  placed  on  its  face  or  back,)  obviously  revolves  vertically  to  the  plane  of  the  horizon ; 
hence,  watches  made  with  this  escapement  are  termed  vertical.  Watches  are  still  manufactured  on 
this  principle,  which  has  its  conveniences,  as  it  is  understood  in  every  part  of  the  world  where  a man 
pretends  to  repair  watches,  and  is  the  cheapest  of  ail  movements,  and  perhaps  for  this  reason  will 
never  be  wholly  superseded. 

In  this  escapement,  as  in  the  common  recoil  escapement  of  clocks,  the  teeth  of  the  balance-wheel  are 
continually  pressing  -on  the  pallets,  in  such  a manner  as  to  be  exercising  a constant  influence  over  the 
vibrations  of  the  balance ; and  a fresh  impulse  is  communicated  at  each  vibration.  In  all  the  improved 
escapements,  the  balance  is  so  detached  from  the  train  of  wheels,  that  it  only  receives  a momentary 
impulse  from  the  moving  power ; and  in  the  intervals,  the  whole  train  of  wheels  is  checked.  In  general 
this  impulse  is  communicated  only  at  every  second  vibration  of  the  balance ; that  is,  the  balance,  after 
receiving  one  impulse,  completes  its  vibration  in  that  direction  and  returns  to  the  same  point  again, 
before  it  receives  the  next. 

3754.  3755. 

3756. 


One  of  the  contrivances  by  which  these  objects  are  fulfilled,  is  that  known  as  the  duplex  escape- 
nent,  so  named  from  the  escapement-wheel  having  two  sets  of  teeth  on  its  rim ; the  action  of  which 
will  be  easily  comprehended  by  reference  to  Figs.  3755  and  3750.  A A represents  the  scape-wheel, 
which  is  provided  with  two  sets  of  teeth ; — 1,  2,  3,  Ac.,  projecting  from  its  sides,  and  termed  the 
teeth  of  repose  ; — and  ahe,  Ac.,  rising  from  the  surface  of  the  wheel,  and  termed  the  teeth  of  impulse. 
On  the  axle  of  the  balance  there  is  fixed  a piece  0 D,  termed  the  impulse-pallet;  this  stands  just  above 
the  surface  of  the  scape-wheel,  so  that  the  teeth  a b c must  strike  the  projecting  portion  D,  when  the 
wheel  revolves.  On  the  same  axis,  but  placed  a little  below  it,  so  as  to  be  on  the  level  of  the  teeth  1, 
2,  3,  Ac.,  is  a small  roller  made  of  ruby;  this  has  a notch  cut  out  of  one  side  of  it,  as  seen.  in.Fig.  3755. 
The  scape-wheel  is  constantly  being  urged,  by  its  connection  with  the  going-train,  in  the  direction  from 
3 to  1 ; and  consequently,  in  the  position  represented  in  Fig.  3755,  the  tooth  a is  just  about  to  strike 
the  impulse-pallet  D.  The  impulse  being  given,  the  balance  moves  round,  and  the  tooth  a escapes 
from  the  pallet.  The  next  tooth  h does  not  immediately  fall  against  it,  however ; since,  before  it  can 
do  so,  the  tooth  1 has  been  stopped . against  the  ruby  roller.  There  it  is  held,  during  the  vibration  of 
the  balance  and  its  return,  until  the  roller  comes  back  into  the  position  shown  in  Fig.  3755,  which  will 
permit  the  point  of  the  tooth  1 to  pass  by  the  notch ; so  that  the  tooth  b may  fall  on  the  pallet  D,  and 
give  the  balance  a renewed  impulse  just  as  its  next  vibration  is  commencing.  Thus  it  is  seen  that  the 
teeth  abc  are  those  which  give  the  impulses  to  the  pallet ; whilst  by  means  of  the  check  which,  in  the 
intervals,  the  points  of  the  teeth  1,  2,  3 receive  against  the  ruby  roller,  the  train  is  kept  in  repose. 

Fig.  3756  is  a perspective  view  of  this  escapement,  the  cogs  a being  placed  upright  nearer  the 
centre,  while  the  long  teeth  b are  in  the  plane  of  the  wheel ; hence  arises  a double  action  : c is  the 
balance.  This  escapement  is  of  English  invention  : watches  having  it  are  perhaps  to  be  ranked  next 
to  the  chronometer  in  value,  particularly  as  regards  the  length  of  time  which  they  will  continue  to  per- 
form without  cleaning,  or  requiring  a fresh  application  of  oil. 

To  this  movement  there  are,  it  must  be  acknowledged,  some  objections.  It  is  of  very  delicate  con- 
struction, and  if  not  made  and  put  together  by  a workman  of  superior  talent,  the  watch  is  liable  to 
stop  in  the  pocket. 

This  escapement  is  not  so  commonly  employed,  however,  as  the  one  known  under  the  name  of  the 
detached  lever.  This  essentially  consists  of  the  dead-beat  escapement,  applied  to  the  balance  in  such  a 
manner,  that  a straight  piece  prolonged  from  the  anchor  or  crutch,  on  the  other  side  of  its  centre  of 
motion,  shall  give  a momentary  impulse  to  a ruby  roller  fixed  on  the  axle  of  the  balance,  each  time 
that  either  of  the  pallets  escapes. 

Neither  of  these,  however,  is  equal  in  perfection  to  that  known,  after  the  name  of  its  inventor,  as 
Earnshaw’s  detached  escapement.  This  is  the  one  at  present  universally  employed  for  chronometers 
and  the  most  accurate  time-keepers ; and  nothing  but  the  delicacy  of  its  construction,  and  its  consequent 
expensiveness,  prevents  it  from  coming  into  general  use.  Its  action  will  now  be  explained  by  the  help 
of  Fig.  3757.  A A represents  the  scape-wheel,  the  teeth  of  which,  1,  2,  3,  4,  Ac.,  are 
considerably  undercut  on  the  side  or  face  towards  which  they  move.  At  B B is  shown 
the  steel  roller  or  main-pallet,  which  is  fixed  on  the  axle  of  the  balance.  This  has  a 
large  notch  cut  in  it;  and  the  side  of  this  notch  nearest  the  tooth  1 is  guarded  by  a thin 
plate  of  ruby,  on  which  the  points  of  the  teeth  strike  as  they  pass  it.  The  same  arbor 
carries  the  small  lifting-pallet  q , which  has  a projection  on  one  side,  that  lifts  the  end 
E p of  the  locking-lever  or  detent  next  to  be  described.  This  lever  EE  has  its  centre 
of  motion  at  c,  where  it  is  attached  by  a screw  to  a stud  S,  which  is  firmly  fixed  to  one 
of  the  plates  of  the  chronometer.  Near  this  stud,  the  lever  is  made  thin  and  elastic ; 
so  that  it  has  a springing  power  which  keeps  it  pressing  towards  the  scape-wheel,  un- 
less removed  from  that  position.  It  is  prevented  from  pressing  too  far,  however,  by  the  screw  d,  which. 
>.«  fixed  into  the  stud  D ; for  the  head  of  this  screw  acts  as  a stop  to  the  lever,  and  prevents  it  from 


S30 


WATCHMAKING. 


moving  further  towards  the  right  than  the  place  in  which  it  is  seen.  At  the  other  end  of  the  lever  is 
an  extremely  delicate  springy),  which  extends  a little  beyond  the  extremity  of  the  detent.  In  the  mid- 
dle of  the  lever  is  the  pin  o,  which  serves  to  stop  the  teeth  of  the  scape-wheel,  when  the  detent  is  in 
the  position  represented  in  Fig.  3757,  which  is  that  of  repose. 

The  following  is  the  mode  in  which  these  parts  act  upon  one  another.  The  tooth  5 of  the  scape- 
wheel  is  seen  to  be  resting  against  the  pin  o ; whilst  the  tooth  1 is  nearly  ready  to  advance  and  strike 
the  ruby  face  of  the  main-pallet  BBB,  but  is  prevented  from  doing  so  by  this  locking  of  the  wheel. 
The  balance,  however,  being  in  motion  from  right  to  left,  (by  the  elasticity  of  its  spring,)  carries  round 
with  it  the  lifting-pallet  q , the  projection  on  which  acts  against  the  end  of  the  lifting-spring ; and  this 
spring,  pressing  against  the  end  of  the  detent  E E,  raises  it  a little  from  its  place,  towards  D,  so  as  to 
withdraw  the  pin  o from  the  point  of  the  tooth  5.  The  wheel  being  thus  unlocked,  the  tooth  1 strikes 
against  the  ruby  face  of  the  main-pallet,  and  gives  the  balance  an  impulse,  which  increases  the  extent 
of  its  vibration.  Before  the  tooth  has  entirely  escaped,  however,  from  the  ruby  face,  the  lifting-pallet  q 
lias  completely  passed  the  point  of  the  lifting-spring  p ; so  that  the  detent  is  at  liberty  to  fall  back  into 
its  place,  which  it  is  caused  to  do  by  the  spring  at  its  fixed  end.  Hence,  by  the  time  that  the  tooth  1 
has  escaped  from  the  main-pallet,  the  pin  o will  be  in  a position  to  check  the  next  tooth  6,  which  ad- 
vances against  it ; and  the  whole  train  of  wheels,  therefore,  again  comes  to  repose.  The  balance,  hav- 
ing completed  its  vibration  forwards,  begins  to  return,  by  the  elasticity  of  its  spiral  spring.  In  this 
return,  the  lifting-pallet  q has  again  to  pass  the  end  of  the  lifting-spring  p ; but  it  now  merely  separates 
this  from  the  end  of  the  detent,  and  does  not  move  the  detent  itself.  The  locking  of  the  scape-wheel 
still  continues,  therefore,  until  the  balance  has  completed  its  return  vibration,  and  again  begins  to  move 
forwards;  the  lifting-pallet  will  then  again  raise  the  detent  and  set  free  the  scape-wheel;  the  balance 
will  receive  a fresh  impulse  from  the  action  of  the  teeth  upon  the  ruby  face  of  the  main-pallet ; and 
the  detent  will  again  lock  the  wheel,  as  soon  as  the  tooth  has  escaped.  All  this  complex  action,  which 
occupies  so  long  in  the  description,  is  really  repeated  in  every  half-second, — that  being  the  time  in 
which  the  balance  is  usually  made  to  perform  its  double  vibration. 

Compensation  balance. — It  is  essential  to  the  accurate  going  of  a chronometer,  that  it  should  be  fur- 
nished with  some  means  of  compensating  the  action  of  heat  or  cold  upon  the  balance-spring,  analogous 
to  those  by  which  compensation  is  made  for  the  effect  of  change  of  temperature  upon  the  pendulum. 
This  is  here  also  effected,  by  taking  advantage  of  the  unequal  expansion  of  different  metals ; so  that 
the  change  produced  in  the  length  of  the  spring  may  be  antagonized  by  a change  in  the  form  of  the 
balance,  producing  a variation  in  the  amount  of  force  necessary  to  move  it.  From  what  has  been 
formerly  stated  of  the  principles  of  the  lever,  and  wheel,  and  axle,  it  is  evident  that,  the  nearer  the 
chief  weight  of  the  balance  is  disposed  to  the  centre  of  motion,  the  less  amount  of  force  will  be  required 
to  turn  it.  Consequently  if — when  the  action  of  heat  upon  the  balance-spring  has  weakened  it,  by  in- 
creasing its  length — the  same  action  can  be  made  to  cause  the  weight  which  the  spring  has  to  move 
to  approach  nearer  the  centre,  a perfect  compensation  may  be  effected.  In  the  same  manner,  the  spring 
being  shortened  by  cold,  and  thereby  rendered  more  powerful,  the  weight  ought  to  be  carried  further 
from  the  centre,  so  as  to  require  a greater  moving  power. 

These  objects  are  accomplished  by  the  compensation  balances  represented  in  Figs.  3758  and  3759. 
The  principle  of  both  is  the  same ; and  the  only  difference  consists  in  this,  that  the  necessary  weight  is 
given  in  Fig.  3759  by  a single  piece  W on  each  arm  of  the  balance ; whilst  in  Fig.  3758  it  is  distributed 
among  the  four  screws  1,  2,  3,  4,  which  are  inserted  into  each  arm.  These  balances  are  not  made  in  the 


3758. 


3759. 


37C0. 


form  of  a complete  wheel ; but  are  composed  of  the  cross-bar  A B attached  to  the  axis,  and  of  the  two 
circular  arms  carried  by  its  ends.  Each  of  these  circular  arms  is  a compound  bar  of  brass  and  steel, 
the  brass  being  on  the  outside.  As  brass  expands  by  heat  much  more  than  steel,  the  effect  of  a rise  of 
temperature  is  to  cause  the  curvature  of  the  bars  to  increase,  so  that  their  ends  a a curl  in,  as  it  were, 
towards  the  cross-piece  A B,  carrying  inwards  the  weights  W W,  Fig.  3759,  or  the  screws  1,  2,  3, 4,  Fig. 
3758  ; hence  the  balance  will  be  more  easily  made  to  revolve,  and  the  weakened  action  of  the  spring 
will  be  compensated.  On  the  other  hand,  the  effect  of  cold  will  be  to  make  the  brass  contract  more 
than  the  steel,  and  thus  to  diminish  the  curve  of  the  circular  bars,  rendering  them  straighter,  so  as  to 
increase  the  distance  of  the  weights  from  the  centre,  and  thereby  to  increase  the  power  requisite  to 
move  them ; thus  counterbalancing  the  increased  power  given  to  the  spring  by  its  own  contraction. 

There  is  much  difficulty  in  exactly  adjusting  this  compensation  to  the  error  it  is  desired  to  correct. 
It  may  be  that  it  is  too  great ; in  which  case  the  chronometer  will  gain  by  heat  and  lose  by  cold.  This 
is  corrected  by  shifting  the  weights  ~W  W,  Fig.  3759,  towards  a part  of  the  circular  bars  nearer  to  their 
attachment,  so  that  they  may  be  less  influenced  by  the  alteration  of  the  curvature  of  the  bars ; and  the 
same  result  is  obtained  in  the  other  form  of  the  balance,  Fig.  3758,  by  drawing  out  the  screws  4,4,  and 


WATCHMAKING. 


831 


screwing  in  1,1.  On  the  other  hand,  if  the  compensation  be  not  sufficient,  the  weights  must  be  shifted 
towards  the  ends  a a oi  the  circular  bars,  so  as  to  be  more  altered  in  place,  when  the  curvature  of  the 
bars  is  changed  by  an  alteration  of  temperature.  The  screws  C 0 are  obviously  not  affected  by  these 
changes  of  curvature,  since  (liey  pass  into  the  ends  of  the  straight  bar  A B ; but  the  effect  of  screwing 
them  in  or  drawing  them  out,  is  to  alter  the  rate  at  which  the  balance  will  vibrate ; for  if  the  moving 
power  remain  the  same,  and  a portion  of  the  weight  be  carried  to  a greater  distance  from  the  centre — 
as  it  is  by  partly  drawing  out  the  screws  C C — the  vibrations  will  be  rendered  slower  ; and  the  contrary 
effect  will  be  produced  by  screwing  them  in.  Now  in  finally  adjusting  a chronometer,  it  is  found  unde- 
sirable to  alter  the  length  of  the  balance-spring,  after  the  point  has  once  been  ascertained  at  which  its 
vibrations  are  isochronous,  or  nearly  so.  Hence,  in  order  to  bring  it  to  the  proper  rate,  it  is  found  ad- 
vantageous to  make  it  go  faster  or  slower  as  required  by  slightly  altering  these  screws,  which  are  hence 
called,  to  distinguish  them  from  the  others,  mean-time  screws. 

The  chronometer. — Fig.  3760  shows  the  balance-wheel  of  a chronometer;  a is  the  balance-spring,  the 
elastic  force  of  which,  when  wound  up  by  the  motive  power,  acting  through  the  escapement,  into  a state 
of  tension,  gives  motion  to  the  balance  h.  The  elastic  force  of  this  balance-spring  varies  by  change  of 
temperature,  producing  an  error  of  six  minutes  in  twenty-four  hours  in  the  time  indicated  by  the  chro- 
nometer, for  68°  of  Fahrenheit.  This  irregularity  is  corrected  by  the  balance  b varying  its  diameter, 
much  in  the  same  manner  as  the  balls  of  a steam-engine  govern  that  machine  ; with  this  exception,  that 
while  the  balls  of  a steam-engine  act  by  gravity  and  centrifugal  force,  the  effect  is  here  mechanically 
produced  from  the  different  metals  (brass  and  steel)  expanding  and  contracting  differently  under  a 
change  of  temperature,  thus  varying  the  diameter,  and  consequently  the  inertia  of  the  balance  in  ac- 
cordance therewith.  It  must  be  recollected  that  no  chronometer  can  keep  a uniform  rate  unless  the 
tension  of  the  balance-spring  has  an  invariable  ratio  to  the  inertia. 

Heat  renders  the  balance-spring  a weaker,  while  the  inertia  of  the  compensation  balance  b is  de- 
creased, thus  compensating  the  loss  occasioned  by  the  relaxation  of  the  spring. 

The  compensation  balance,  by  which  the  error  is  compensated,  may  be  thus  explained  : The  compen- 
sation, as  already  observed,  is  produced  by  the  variation  in  the  diameter  of  the  circle  b.  The  internal 
part  of  the  rim  c is  of  steel,  while  the  external  part  d is  of  brass  ; these  are  united  by  heat,  causing  a 
partial  fusion  of  the  brass,  and  consequent  union  with  the  steel.  The  degree  of  expansion  of  these 
metals  upon  application  of  the  same  degree  of  heat  varies ; the  brass  expands  more  than  the  steel,  and 
as  it  cannot  release  itself  from  this,  so  neither  has  it  the  power  of  expanding  itself  in  length,  being  re- 
strained by  the  steel : consequently  an  increase  of  curvature  is  produced  by  the  brass  forcing  the  steel 
to  change  its  original  circular  form,  the  inertia  or  power  of  the  compensation  balance  hence  varies,  and 
compensates  for  the  loss  or  gain  in  the  balance-spring  occasioned  by  a change  of  temperature.  The  rim 
of  the  balance  is  cut  open  at  e,  to  admit  of  this  variation  in  its 
form;  the  screws/ can  be  inserted  in  any  of  the  holes  g,  and 
according  to  their  position  in  one  or  the  other,  these  screws  are 
moved  more  or  less  in  towards  the  centre  by  the  increase  of 
curvature  of  the  rim  before  mentioned,  thus  contributing  to  vary 
the  inertia  of  the  balance  in  a small  degree,  but  admitting  of 
original  adjustment  for  this  purpose — giving  that  finish  to  the 
principle  of  this  contrivance  on  which  the  exquisite  accuracy  of 
the  chronometer  in  great  measure  depends.  This  principle  of 
compensation  is  the  same  in  all  watches  to  which  a compensa- 
tion balance  is  applied,  viz.,  to  those  of  the  duplex  and  lever 
kind.  The  escapement  used  in  the  chronometer,  as  seen  in  Fig. 

3761,  is  termed  a “ detached”  one,  which  means,  that  the  vibrations  performed  by  the  balance  arc  nearly 
detached  from  the  pressure  of  the  motive  power  during  the  greater  part  of  its  arc  of  vibration ; one 
great  advantage  is,  that  it  requires  no  oil.  This  escapement  is  of  French  invention,  but  improved  by 
English  artists. 

These  are  the  principles  on  which  the  excellence  of  a time-keeper  depends.  In  their  application  to 
practice,  however,  every  thing  depends  on  the  perfection  with  which  the  machine  is  constructed ; and 
the  minuteness  of  the  conditions  required  for  the  good  going  of  a chronometer  may  be  judged  of  from 
the  fact  with  which  practical  men  are  familiar — that,  of  two  chronometers,  constructed  upon  the  same 
plan,  and  finished  with  equal  care  in  all  respects  by  the  same  hand,  one  may  go  very  well,  and  the 
other  comparatively  badly,  without  any  discoverable  difference  between  them.  In  finally  adjusting  a 
chronometer  no  attempt  is  made  to  keep  it  exactly  to  mean  time ; that  is,  to  make  it  continue  to  point, 
day  after  day,  and  week  after  week,  exactly  to  the  correct  hour;  for  it  is  just  as  advantageous  to  allow 
it  to  gain  or  to  lose  a few  seconds  a day,  provided  that  the  gain  or  loss  be  regular  in  its  amount;  since 
the  real  time  may  be  known  with  equal  accuracy  from  that  which  the  chronometer  indicates.  Thus, 
suppose  that  we  have  a chronometer  which  was  set  36  days  ago,  since  which  time  it  has  been  gaining 
5 seconds  a day  ; if  its  gain  have  been  regular,  its  whole  gain  during  that  period  will  be  (5  X 36)  180 
seconds,  or  three  minutes ; and  three  minutes  being  deducted  from  the  time  to  which  the  hands  point, 
we  shall  have  the  real  time.  This  regular  amount  of  gain  or  loss  is  called  the  rate  of  a chronometer ; 
and  it  is  thus  expressed  : When  the  chronometer  is  said  to  have  a rate  of  2'53,  we  understand  that 
it  is  gaining  2-}  seconds  per  day ; but  if  its  rate  is  — 3'2,  we  know  that  it  is  losing  31-  seconds  per  day. 
The  more  closely  it  keeps  to  this  rate  the  better  the  instrument  will  obviously  be ; but  if  it  vary  much 
from  its  rate,  even  though  its  errors  should  be  sometimes  on  one  side,  and  sometimes  on  the  other,  so  as 
to  compensate  one  another,  and  make  the  general  average  the  same,  the  performance  is  bad,  and  can- 
not be  relied  on. 

When  the  minuteness  of  the  parts  of  a chronometer  is  considered,  and  the  variety  of  disturbances  to 
which  it  is  exposed,  the  accurate  performance  to  which  it  may  be  brought  is  most  wonderful.  For  it 
must  be  remembered  how  very  trifling  a cause,  if  constantly  aedng,  (such  as  a slight  thickening  of  the 


832 


WATCHMAKING. 


oil,)  will  greatly  alter  the  result.  Thus,  as  there  are  1440  minutes  in  a day,  any  cause  which  makes 
each  vibration  of  the  balance  (of  which  there  are  five  in  a common  watch)  take  place  in  l-7200th  part 
less  or  more  than  its  usual  time,  will  cause  the  time-keeper  to  gain  or  lose  a minute  a day.  And  as 
there  are  86,400  seconds  a day,  any  cause  which  makes  each  vibration  of  the  balance  of  a chronometer 
(which  usually  occurs  4 times  in  a second)  take  place  in  1-432, 000th  part  less  or  more  than  its  usual 
time,  will  cause  it  to  gain  or  lose  a second  a day — an  error  of  very  considerable  magnitude.  When  it 
was  first  supposed  that  chronometers  could  be  made  sufficiently  perfect  to  give  important  assistance  in 
the  determination  of  the  longitude  at  sea,  (the  mode  of  doing  which  will  be  explained  hereafter,)  a par- 
liamentary reward  of  £10,000  was  offered  in  1714  to  any  one  who  should  construct  a time-keeper  capa- 
ble of  doing  so  within  the  limit  of  sixty  geographical  miles;  £15,000  if  to  forty  miles;  and  £20,000  if 
to  thirty  miles.  Now  a chronometer  that  has  so  much  changed  its  rate  a9  to  have  gained  or  lost,  in  a 
few  weeks,  two  minutes  more  than  it  was  estimated  to  have  done,  would  gain  the  highest  of  these  re- 
wards; so  that  the  utmost  degree  of  accuracy  which  was  contemplated  as  possible,  at  the  beginning  of 
the  last  century,  when  this  act  was  passed,  is  far  surpassed  at  present. 

The  reward  was  gained  by  John  Harrison,  who,  in  1736,  completed  the  first  chronometer  used  at  sea, 
after  many  years  of  patient  study  and  laborious  experiment.  He  gradually  improved  his  machine ; 
and  in  1761  the  first  trial  was  made  of  it,  according  to  the  regulations  of  the  act  of  Parliament,  by  a 
voyage  to  Jamaica.  In  consideration  of  his  advancing  years  his  son  was  allowed  to  take  this  voyage 
instead  of  himself.  After  eighteen  days’  navigation  the  vessel  was  supposed  by  the  captain  to  be  13° 
50'  west  of  Portsmouth;  but  the  watch  giving  15°  19',  or  a degree  and  a half  more,  was  condemned 
as  useless.  Harrison  maintained,  however,  that  if  Portland  Island  were  correctly  marked  on  the  chart, 
it  would  be  seen  on  the  following  day ; and  in  this  he  persisted  so  strongly,  that  the  captain  was  in- 
duced to  continue  in  the  same  course,  and  accordingly  the  island  was  discovered  the  next  day  at  seven 
o’clock.  This  raised  Harrison  and  his  watch  in  the  estimation  of  the  crew ; and  their  confidence  was 
increased  by  his  correctly  predicting  the  several  islands  as  they  were  passed  in  the  voyage  to  Jamaica. 
When  he  arrived  at  Port  Royal,  after  a voyage  of  81  days,  the  chronometer  was  found  to  be  about  5 
seconds  too  slow ; and  finally,  on  his  return  to  Portsmouth,  after  a voyage  of  five  months,  it  had  kept 
time  within  about  one  minute  and  five  seconds,  which  gives  an  error  of  about  18  miles.  This  amount 
was  much  within  the  limits  prescribed  by  the  act ; but  Harrison  did  not  receive  the  whole  reward  until 
a second  voyage  had  been  made  ; and  large  as  the  sum  appears,  it  cannot  be  regarded  as  more  than 
equivalent  to  the  devotion  of  extraordinary  talents,  with  unwearied  perseverance,  during  40  years,  to 
the  attainment  of  an  object  whose  importance  can  scarcely  be  estimated  too  highly. 

As  an  illustration  of  the  improvements  which  have  been  since  made  in  the  construction  of  chronome- 
ters, the  following  circumstance,  mentioned  by  Dr.  Arnott  as  having  occurred  to  himself,  is  of  great  in- 
terest. “ After  several  months  spent  at  sea,”  he  says,  “ in  a long  passage  from  South  America  to  Asia, 
my  pocket  chronometer  and  others  on  board  announced  one  morning  that  a certain  point  of  land  was 
then  bearing  north  from  the  ship  at  a distance  of  fifty  miles ; in  an  hour  afterwards,  when  a mist  had 
cleared  away,  the  looker-out  on  the  mast  gave  the  joyous  call  of  ‘ Land  ahead  !’  verifying  the  report  of 
the  chronometers  almost  to  one  mile,  after  a voyage  of  thousands.  It  is  allowable  at  such  a moment, 
with  the  dangers  and  uncertainties  of  ancient  navigation  before  the  mind,  to  exult  in  contemplating 
what  man  has  now  achieved.  Had  the  rate  of  the  wonderful  little  instrument,  in  all  that  time,  been 
quickened  or  slackened  ever  so  slightly,  its  announcement  would  have  been  useless,  or  even  worse ; but 
in  the  night  and  in  the  day,  in  storm  and  in  calm,  in  heat  and  in  cold,  its  steady  beat  went  on,  keeping 
exact  account  of  the  rolling  of  the  earth  and  of  the  stars  ; and  in  the  midst  of  the  trackless  waves  which 
retain  no  mark,  it  was  always  ready  to  tell  its  magic  tale,  indicating  the  very  spot  of  the  globe  over 
which  it  had  arrived.” 

It  is  surprising  that,  in  spite  of  the  great  advantages  resulting  from  the  use  of  chronometers  in  navi- 
gation, many  ships  are  sent  to  sea  without  them,  even  for  long  voyages.  Not  unfrequently  must  it  occur 
that  the  knowledge  of  the  exact  position  of  the  ship,  which  may  be  obtained  by  the  chronometer,  pro- 
duces a great  saving  of  time,  as  well  as  contributes  to  the  avoidance  of  danger.  A remarkable  instance 
of  this  was  mentioned  to  the  author,  a few  years  since,  as  having  just  then  occurred.  Two  ships  were 
returning  to  London  about  the  same  time,  after  long  voyages,  one  of  them  provided  with  chronome- 
ters, the  latter  destitute  of  them.  The  weather  was  hazy,  and  the  winds  baffling;  so  that  no  ship,  whose 
position  was  uncertain,  could  be  safely  carried  up  the  British  Channel.  Confident  in  his  position,  how- 
ever, the  captain  of  the  first  ship  stood  boldly  onwards,  and  arrived  safely  in  the  Thames,  whilst  the 
other  ship  was  still  beating  about  in  uncertainty  near  the  entrance  to  the  Channel.  The  first  ship  dis- 
charged her  cargo,  took  in  another,  set  sail  on  a fresh  voyage,  and  actually,  in  running  down  the  Chan- 
nel, encountered  the  second  ship  still  toilsomely  making  her  way  to  her  port ! 

Of  the  degree  of  accuracy  which  chronometers  are  capable  of  exhibiting,  some  idea  may  be  formed 
from  the  following  statement,  kindly  communicated  to  the  author  by  a gentleman  practically  conversant 
with  them.  A chronometer  made  by  Molyneux  had  its  daily  rate  determined,  in  August,  1839,  to  be  a 
loss  of  7 seconds  per  day.  It  was  then  placed  in  a ship  which  traded  to  the  coast  of  Africa,  and  was 
consequently  exposed  to  great  variations  of  temperature.  Yet  when  again  placed  under  careful  obser- 
vation in  November,  1840,  (sixteen  months  afterwards,)  its  daily  loss  had  only  changed  to  6'7  seconds, 
being  a difference  of  only  3-10tbs  of  a second  a day.  As  opportunities  for  ascertaining  the  real  position 
of  the  ship,  without  chronometers,  frequently  occur  at  sea,  any  error  in  these  may  almost  always  be 
detected  before  it  has  accumulated  to  any  great  extent ; but  even  supposing  that  no  such  opportunity 
had  occurred  for  six  months,  and  that  the  alteration  of  the  rate  had  taken  place  at  once,  and  had  been 
entirely  unknown,  the  whole  error  would  have  been  under  a minute  of  time,  and  consequently  less  than 
15  miles  of  space.  Another  chronometer,  constructed  by  Muston,  which  had  made  the  same  voyage, 
and  been  out  about  the  same  length  of  time,  had  its  previous  gaining  rate  of  1’9  seconds  a day  increased 
to  2'3  seconds;  the  difference  being  here  4-10ths  of  a second.  It  is  customary  for  two  or  more  chro- 
nometers to  be  carried  by  the  same  ship,  that  they  may  check  one  another ; for  if  one  alone  were 


WATCHMAKING. 


833 


3762. 


trusted  to,  an  accidental  irregularity  in  its  going  might  lead  to  great  error.  The  average  of  several — • 
their  errors  counterbalancing  each  other — will  be  most  likely  to  give  the  real  time  with  great  exactness. 

Striking  apparatus. — The  apparatus  for  striking  the  hour  is  somewhat  complex ; but  we  shall 
endeavor  to  make  its  action  intelligible,  as  it  is  a very  beautiful  specimen  of  ingenious  mechanism. 
The  form  which  will  be  described  is  that  which  is  adopted  in  the  best  English  clocks  : a simpler  plan  is 
adopted  in  the  cheap  German  clocks,  which  are  now  so  largely  employed  in  this  country ; but  they  are 
very  liable  to  get  out  of  order.  The  difference  consists,  however,  only  in  the  apparatus  by  which  the 
striking  is  regulated,  as  to  time  and  number  of  strokes  ; the  mechanism  by  which  the  hammer  is  made 
to  strike  the  bell  is  the  same  in  both  cases.  It  consists  of  a train  of  wheels  and  pinions,  put  into  action 
by  the  spring  contained  in  the  barrel  E,  Fig.  8749,  which  turns  the  fusee  F.  The  fusee  carries  round 
with  it  the  main-wheel  e,  which  has  81  teeth ; this  drives  the  pinion  p of  8 leaves,  which  carries  on  its 
axle  the  pin-wheel  f,  having  64  teeth.  In  the  rim  of  this  pin-wheel  are  8 pins,  which  lift  the  hammer 
s by  acting  on  its  tail  t when  the  train  is  in  motion.  The  hammer  being  gradually  lifted  by  each  pin. 
is  at  last  let  go  by  it,  and  is  made  to  strike  the  bell  by  the  spring  u.  The  pin-wheel  drives  a pinion  q 
of  8 leaves,  which  carries  round  the  pallet-wheel  g of  56  teeth : as  the  pin-wheel  has  64  teeth,  it  turns 
the  pallet-wheel  pinion  8 times  for  each  revolution  of  its  own,  consequently  this  pinion  makes  one  revo- 
lution for  every  stroke  of  the  hammer,  an  arrangement  of  which  the  use  will  be  presently  shown. 
The  pallet-wheel  acts  on  a pinion  z of  7 leaves,  on  which  is  the  warning-wheel  h of  48  or  50  teeth,  and 
this  last  turns  the  fly-pinion  i.  The  object  of  this  part  of  the  train  is  only  to  equalize  the  motion, 
which  is  principally  effected  by  the  constant  resistance  of  the  air  against  the  surface  of  the  plate  (termed 
the  fly)  which  is  whirled  very  rapidly  round  by  the  highest  pinion.  If  it  were  not  for  this  addition,  the 
pin-wheel  would  move  onwards  with  a jerk,  after  each* pin  had  escaped  from  the  tail  of  the  hammer. 

The  striking-train  remains  completely  at  rest  during  each  hour’s  movement  of  the  going-train,  and 
is  only  allowed  to  act  at  the  conclusion  of  one  hour  and  the  commencement  of  the  next.  The  mode 
in  which  it  is  restrained  in  the  intervals,  and  its  action  at  the  proper  time  permitted  and  regulated, 
will  now  be  explained.  The  mechanism  by  which  this  is  effected  is  shown  in  Fig.  3162.  It  is  situated 
immediately  behind  the  dial.  The  axis  of  the  centre-wheel,  as 
already  mentioned,  is  prolonged  through  the  dial,  to  bear  the 
minute-hand.  In  the  striking  clock  this  also  bears  a small  wheel 
a,  which  gives  motion  to  another  wheel  b of  the  same  size  and 
number  of  teeth ; hence  this  wheel,  like  the  former,  revolves  once 
in  each  hour.  On  the  centre  of  this  wheel  is  a pinion  of  6 or  8 
leaves,  which  turns  a wheel  c with  a hollow  axle,  moving  on  the 
same  centre  as  a,  but  at  a different  rate,  as  in  the  watch.  This 
wheel  has  12  times  the  number  of  teeth  that  the  pinion  contains, 
and  therefore  moves  at  only  1-1 2th  of  the  rate.  To  it  the  hour- 
hand  is  affixed ; and  it  also  carries  a peculiarly  shaped  piece  of 
metal  d,  which  is  called  the  snail.  The  edge  of  this  snail  is  cut 
into  12  steps,  each  of  which  is  a twelfth  of  the  circle  of  which  it 
forms  a part ; but  the  distance  of  each  from  the  centre  increases  regularly  from  1 to  1 2. 
a circular  rack,  fixed  to  the  end  of  a bent  lever  ef  g h,  whose  centre  of  motion  is  at/i  By  the  action  of 
the  bent  spring  i this  rack  will  be  made  to  fall  towards  the  left,  when  permitted  to  do  so ; but  the 
amount  to  which  it  shall  fall  is  governed  by  the  position  of  the  snail,  against  the  edge  of  which  the  pin 
h will  be  brought  to  bear.  This  spring  is  prevented  from  forcing  the  rack  out  of  the  position  shown  in 
the  figure,  by  means  of  the  projecting  piece  on  the  lever  k,  which  turns  on  the  centre  /,  and  drops  by 
its  own  weight  into  the  teeth  of  the  rack.  The  form  of  these  teeth  is  such,  that  when  the  rack  is  moved 
from  left  to  right,  the  catch  is  lifted  by  them  and  allows  them  to  pass ; but,  so  long  as  it  is  allowed  to 
drop  between  the  teeth,  it  completely  prevents  the  motion  of  the  rack  from  right  to  left.  The  lever  k, 
with  its  catch,  may  be  lifted  by  the  bent  lever  m p n,  whose  centre  of  motion  is  at  p ; and  this  is  acted 
on  by  a pin  in  the  circumference  of  the  wheel  b,  which  is  seen  in  the  figure,  close  against  the  tail  of 
the  lever. 

Only  one  other  part  remains  to  be  described — that  which  is  known  as  the  gathering-pallet.  The  axle 
of  the  pallet- wheel g,  Fig.  3749,  projects  through  the  front  plate;  and  is  furnished  with  a projection, 
seen  at  o,  resembling  one  leaf  of  a pinion.  This  works  into  the  teeth  of  the  rack  in  such  a manner  that, 
as  the  axle  turns  round,  the  rack  is  gathered  up  by  it,  to  the  amount  of  one  tooth  for  each  revolution. 
When  the  machinery  is  in  the  position  shown  in  the  figure — which  it  has  during  the  whole  time  that  the 
striking-train  .is  at  rest — a projection  on  the  gathering-pallet  rests  on  a pin  which  projects  from  the  rack, 
as  seen  at  r.  It  is  this  which  keeps  the  striking-train  from  acting ; for,  so  long  as  this  projection  from 
the  axle  of  the  pallet-wheel  bears  upon  the  pin,  so  long  must  the  pallet- wheel,  and  consequently  the 
whole  remainder  of  the  striking-train,  be  prevented  from  running  on. 

But  when  the  time  of  striking  is  nearly  come,  the  pin  on  the  wheel  b acts  on  the  tail  of  the  lever 
npm;  the  end  q of  which  raises  the  lever  k l,  and  consequently  lifts  its  catch  out  of  the  rack  o,  which 
is  thus  set  free.  The  spring  i,  therefore,  pressing  upon  the  projection  below  f,  causes  the  rack  to  fall 
towards  the  left;  and  therefore  sets  free  the  projection  on  the  gathering-pallet,  by  withdrawing  the  pin 
on  which  it  rested.  Hence  the  whole  striking-train  would  be  set  in  action  by  its  weight ; if  it  were  not 
that,  at  the  same  time  that  the  gathering-pallet  is  freed,  another  check  is  provided.  The  end  q of  the 
bent  lever  mpn  bears  a projecting  piece,  which,  when  the  lever  is  raised,  stops  a pin  placed  on  the  cir- 
cumference of  the  warning-wheel  h,  Fig.  3749.  So  long  as  the  lever  remains  in  this  position,  therefore, 
the  striking-train  is  prevented  from  acting.  The  amount  of  motion  given  to  the  rack  is  determined  by 
the  place  of  the  snail.  In  the  position  represented  in  the  figure,  the  pin  h would  be  stopped  by  the 
second  step ; and  thus  the  rack  would  only  be  permitted  to  move  to  the  amount  of  two  of  its  teeth. 
If  the  position  of  the  hour-wheel  were  such,  that  the  twelfth  step  of  the  snail  corresponded  with  the 
end  h of  the  rack -lever,  then  the  pin  would  not  be  stopped  so  soon ; and  the  rack  would  fall  towards 
Vol.  n. — 53 


At  e is  seen 


834 


WATCHMAKING. 


the  left  to  the  amount  of  twelve  teeth.  This  preparatory  action  is  usually  made  to  take  place  about  3 
or  5 minutes  before  the  expiration  of  the  hour,  and  it  is  called  (jiving  warning. 

The  machinery  remains  in  this  position  until  the  minute-hand  points  to  XII.,  at  which  time  the  wheel 
h has  so  far  advanced  that  its  pin  escapes  from  under  the  end  of  the  lever,  and  thus  allows  it  to  fall,  so 
that  the  end  q no  longer  checks  the  pin  on  the  warning-wheel.  The  striking-train  is  now  set  entirely 
free ; the  weight  or  spring  that  moves  it  produces  a rapid  revolution  of  its  wheels ; and  the  pins  on  the 
pin-wheel,  acting  on  the  tail  of  the  hammer-lever,  cause  the  successive  strokes  on  the  bell.  This  move- 
ment goes  on  until  it  is  checked  by  the  action  of  the  gathering-pallet  on  the  rack.  It  has  been  alreadv 
mentioned  that  the  pallet-wheel,  from  the  axle  of  which  the  gathering-pallet  projects,  turns  round  once 
for  every  stroke  given  to  the  hammer;  and  in  each  turn  it  gathers  up  one  tooth  of  the  rack,  causing  it 
to  move  towards  the  right,  so  as  to  regain  jis  original  position.  The  projecting  catch  of  the  lever  kl 
drops  between  the  teeth  at  each  advance,  and  prevents  the  rack  from  being  moved  back  by  the  spring  i. 
This  goes  on  until  the  rack  has  been  completely  brought  back  to  its  first  position,  and  then  the  projec- 
tion on  the  gathering-pallet  will  be  again  checked  by  the  pin  r,  and  the  striking-train  would  be 
brought  to  rest. 

It  is  evident,  then,  that  the  number  of  strokes  will  be  determined  by  the  number  of  revolutions 
which  the  gathering-pallet  is  allowed  to  make ; this  depends  upon  the  number  of  teeth  on  the  rack 
which  have  to  be  gathered  up  by  it ; and  this  number  is  regulated  by  the  extent  to  which  the  rack  is 
permitted  to  fall,  by  the  bearing  of  the  pin  h against  the  edge  of  the  snail.  It  is  almost  impossible  for 
any  error  to  be  committed  by  a movement  so  constructed ; but  the  striking-train  of  the  common  Ger- 
man clocks,  now  so  largely  imported  into  Britain,  is  regulated  by  an  apparatus  of  simpler  construction, 
which  is  very  liable  to  give  wrong  indications.  . It  principally  consists  of  a large  wheel,  (termed  the 
count-wheel,)  usually  placed  at  the  back  of  the  clock,  on  which  are  cut  18  teeth  ; this  is  so  connected 
with  the  striking-train,  that  it  moves  on  one  tooth  for  each  stroke.  The  number  78  is  the  sum  of  all  the 
strokes  which  the  clock  should  make  in  12  hours  ; consequently,  after  all  these  strokes  have  been  made, 
the  wheel  returns  to  the  same  place  again.  From  the  surface  of  the  wheel,  near  its  edge,  there  projects 
a rim,  in  which  are  cut  a series  of  notches,  at  intervals  corresponding  with  the  number  of  strokes.  Thus, 
between  the  first  and  second  notches  there  is  an  interval  amounting  only  to  one  tooth  of  the  wheel ; 
between  the  second  and  third  notches  an  interval  of  two  teeth ; and  so  on  up  to  the  twelfth  notch,  the 
interval  between  which  and  the  first  is  12  teeth.  The  use  of  these  notches  is  to  receive  a catch  or  pro- 
jection, which  keeps  the  striking-train  at  rest  during  the  hour,  and  regulates  the  number  of  strokes. 
When  the  clock  gives  warning,  this  catch  is  lifted  out  of  the  notch;  but  there  is  a temporary  check 
applied  to  the  warning-wheel  as  in  the  last  case.  When  this  check  is  removed,  the  train  immediately 
begins  to  move,  and  continues  in  action  until  it  is  stopped  by  the  falling  of  the  catch  into  the  succeed- 
ing notch.  The  number  of  strokes  is  determined,  therefore,  by  the  number  of  teeth  which  the  count- 
wheel  shall  have  moved  on  before  the  catch  falls  into  this  notch — or,  in  other  words,  by  the  number  of 
teeth  between  each  notch  and  the  succeeding  one. 

The  advantage  of  this  last  plan  consists  in  its  simplicity,  and  the  facility  with  which  the  apparatus 
may  be  constructed.  Its  disadvantage  consists  in  the  readiness  with  which  it  may  be  put  out  of  order. 
For  it  will  be  easily  seen  that  if,  from  any  cause,  the  clock  be  made  to  strike  at  an  improper  time,  the 
count-wheel  advances,  and  the  number  of  strokes  made  will  be  one  more  than  the  last ; so  that,  when 
it  should  next  strike  the  hour,  the  number  of  strokes  is  one  too  many.  Or  if  any  cause  (such  as  neglect- 
ing to  wind  up  the  weight  of  the  striking-train)  should  prevent  the  clock  from  striking  at  the  proper 
time,  the  count-wheel  remains  stationary  ; and  when  the  clock  next  strikes,  it  gives  the  number  succeed- 
ing the  one  which  it  last  struck,  which  may,  of  course,  be  altogether  wrong.  On  the  other  hand,  in  the 
more  perfectly  constructed  clock,  the  striking  may  be  repeated  any  number  of  times  within  the  hour,  or 
it  may  be  made  to  cease  for  a time  altogether  ; and  yet,  when  the  clock  next  strikes  the  hour,  it  shall 
do  it  correctly.  For  the  number  of  strokes,  as  just  explained,  is  dependent  upon  the  position  of  the 
snail,  which  is  carried  round  by  the  hour-wheel  whether  the  clock  strikes  or  not ; and  which  must,  there- 
fore, always  correspond  with  the  place  of  the  hour-hand.  In  some  clocks  of  this  construction,  there  is 
a simple  contrivance  for  causing  the  hour  to  be  struck  at  any  time.  This  consists  of  a lever  x,  to  one 
end  of  which  the  string  t is  attached,  whilst  the  other  carries  a pin  that  raises  the  lever  rn.  The  action 
of  this  lever  is  checked  by  the  two  pins  s and  z,  which  prevents  it  from  being  moved  too  far  in  either 
direction.  When  the  string  t is  pulled  the  lever  m is  lifted,  and  all  those  changes  take  place  which 
have  been  described  as  occurring  in  the  ordinary  warning  of  the  clock.  When  the  string  is  let  go,  the 
lever  is  made  to  return  to  its  place  by  the  spriug  y ; the  lever  m falls,  the  warning-wheel  is  released, 
and  the  proper  number  of  strokes  is  made.  Such  a contrivance  is  convenient  to  those  who  desire  to 
know  the  hour  during  the  night. 

Where  a clock  is  made  to  strike  the  quarters  as  well  as  the  hours,  a third  train  of  wheels  is  required. 
The  mechanism  is  the  same  in  principle  with  that  which  regulates  the  striking  of  the  hours.  The  axle 
of  the  minute-hand  carries  round  a snail  cut  into  four  steps ; and  on  a wheel  corresponding  to  b,  and 
revolving  therefore  in  an  hour,  there  are  four  pins,  one  of  which  lifts  the  lever  that  sets  free  the  rack 
every  quarter  of  an  hour.  The  rack  has  four  teeth,  corresponding  with  the  four  steps  of  the  snail ; and 
the  passage  of  each  tooth  permits  one  stroke  on  the  quarter-bell.  Most  frequently  the  quarter-stroke  is 
made  upon  two  bells ; and  this  is  accomplished  simply  by  having  a set  of  pins  on  each  side  of  the  pin- 
wheel,  of  which  one  set  acts  on  one  lever,  and  the  other  set  (acting  a little  afterwards,  so  that  the  two 
strokes  may  not  be  made  at  the  same  moment)  on  the  other  lever.  In  clocks  constructed  for  purposes 
in  which  great  accuracy  is  required,  it  is  necessary  to  dispense  altogether  with  the  striking  apparatus ; 
since  a certain  degree  of  force  is  required  to  set  it  in  action,  that  would  derange  the  very  regular  move- 
ment of  a delicate  and  perfect  clock,  in  which  the  power  of  the  weight  ought  to  be  no  more  than  is 
requisite  to  keep  the  pendulum  in  action. 

The  same  apparatus  has  been  applied  to  watches ; but  when  made  on  so  small  a scale  and  carried  about 
in  the  racket,  its  action  is  extremely  liable  to  become  deranged,  and  it  is  therefore  of  little  use.  The 


WATCHMAKING. 


835 


ordinary  repeating-watches  are  made,  not  to  strike  the  hours  regularly,  but  merely  to  indicate  them 
when  desired  to  do  so.  In  order  to  effect  this,  it  is  not  requisite  that  the  watch  should  be  furnished 
with  a second  barrel  and  fusee  with  a distinct  striking-train  of  wheels,  for  it  is  easy  to  apply  a power 
sufficient  to  produce  the  strokes  every  time  that  the  watch  is  applied  to.  for  this  information.  This  is 
usually  accomplished  by  pushing  in  the  pendant,  or  projecting  portion  to  which  the  chain  is  attached ; 
and  by  this  a spring  is  compressed,  which  sets  in  action  the  mechanism  that  produces  the  strokes.  The 
number  of  strokes  is  regulated  by  a snail,  resembling  that  employed  in  clocks.  The  ordinary  repeating- 
watches  are  still  very  complex  in  their  construction ; and  we  prefer  describing  one  invented  some  years 
ago  by  Mr.  Elliott,  of  Clerkenwell,  in  which  the  number  of  parts  is  greatly  reduced  by  the  combination 
of  several  into  one.  The  striking  portion  of  this  watch  is  represented  in  Figs.  3763  and  3764.  The 
most  important  part  of  it  is  a flat  ring  or  centreless  wheel,  of  nearly  the  same  diameter  with  the  watch, 
supported  in  its  place  so  as  to  admit  of  a circular  motion,  by  four  grooved  pulleys  round  its  external 
circumference.  In  Fig.  3763,  A IS  represents  the  plate  to  which  the  dial  is  attached;  and  the  flat  ring 
C D,  with  the  rest  of  the  striking  mechanism,  lies  between  this  plate  and  the  dial.  The  four  pulleys 
are  seen  at  E F G H.  This  ring  has  teeth  cut  in  the  part  of  the  outer  edge  b nearest  to  the  pendant, 
and  the  rack  may  be  thus  turned  by  the  wheel  a,  to  which  motion  is  given  by  turning  the  pendant. 
At  the  lower  part  of  this  ring  is  a series  of  projecting  pins,  which,  in  the  position  shown  in  Fig.  3763, 
act  upon  the  projecting  pallet  i;  whilst  in  the  position  shown  in  Fig.  3764,  they  act  upon  the  pallet  r. 
Of  these,  the  former  is  destined  to  strike  the  hours,  and  the  other  the  quarters.  The  internal  edge  of 
the  ring  is  cut  into  two  series  of  steps,  of  which  the  one  seen  on  the  left-hand  side  of  each  figure  contains 
twelve,  and  regulates  the  striking  of  the  hours ; whilst  the  one  on  the  right  contains  only  four,  and  reg- 
ulates the  striking  of  the  quarters.  When  the  ring  has  had  its  position  changed  by  turning  the  pen- 
dant, it.  is  brought  back  again  by  a spring  contained  in  the  box  or  barrel  Y ; the  action  of  this  spring  is 
communicated  to  the  ring  by  a chain  which  winds  off  the  barrel,  passes  between  the  pulleys  U and  W, 
and  is  attached  to  the  ring  at  X.  Hence,  in  whichever  direction  the  ring  is  turned,  the  chain  will  be 
drawn  off  the  barrel,  and  the  spring  put  on  the  stretch,  as  seen  in  Fig.  3764;  and  the  elasticity  of  the 
spring  will  tend  to  bring  back  the  ring  to  its  previous  position,  shown  in  Fig.  3763. 


37G3.  37G4. 


The  regulation  of  the  number  of  strokes  is  effected  by  means  of  a snail,  exactlv  resembling  that  of  a 
clock.  At  I in  either  of  the  figures  is  seen  the  quarter-snail,  placed  on  the  axis  of  the  minute-hand,  so 
as  to  revolve  every  hour,  and  cut  into  four  steps.  The  same  axle  carries  a projecting  piece  2,  which 
acts  on  the  star-wheel  1,  Fig.  3764,  in  such  a manner  as  to  push  it  on  to  the  amount  of  one-twelfth  of  a 
circle  at  each  revolution  of  the  minute-hand ; consequently  the  whole  star  is  made  to  turn  once  in  the 
twelve  hours.  To  this  wheel  is  attached  the  hour-snail,  as  seen  in  Fig.  3764;  the  common  centre  on 
which  they  turn  is  marked  at  L,  Fig.  3763.  The  hour-snail  acts  upon  the  bent  lever  P O Q,  whose  cen- 
tre of  motion  is  at  0 ; and  the  end  P is  always  kept  against  the  step  of  the  snail  by  the  spring  seen  in 
Fig.  3763.  In  the  position  in  which  the  lever  is  there  shown,  the  snail  having  been  removed,  the  end 
Q of  the  lever  is  pressing  against  the  last  or  lowest  step  of  the  flat  ring,  and  consequently  the  ring  can- 
not be  moved.  But  supposing  the  end  P to  be  lifted  by  the  snail  to  the  2d,  3d,  4th,  or  any  other  step, 
the  end  Q will  be  raised  to  exactly  the  same  amount,  and  will  permit  the  ring  to  be  turned  from  right 
to  left,  until  it  is  stopped  by  the  contact  of  Q with  the  corresponding  step  of  the  ring.  In  exactly  the 
same  manner  the  quarter-snail  acts  upon  the  steps  cut  in  the  inner  edge  of  the  ring  at  />,  by  means  ot 
the  bent  lever  SRT,  whose  centre  is  R, 

Now  when  it  is  desired  to  ascertain  the  hour,  the  watch  is  held  in  one  hand  and  the  pendant  turned 
from  right  to  left  with  the  other.  This  causes  a corresponding  motion  in  the  ring ; and  every  pin,  as  it 
passes  the  pallet  i,  gives  an  impulse  to  the  hammer,  which  causes  a stroke  upon  the  sounding  body. 
The  extent  to  which  the  ring  may  be  turned,  and  consequently  the  number  of  pins  allowed  to  pass  the 
pallet,  depends  upon  the  position  of  the  lever  POQ;  and  this,  as  just  explained,  is  determined  by  the 
position  of  the  snail.  Hence  the  ring  is  stopped  just  when  as  many  pins  have  passed  the  pallet  as  cor- 
respond with  the  step  of  the  snail  against  which  the  end  P of  the  lever  is  resting.  After  the  hours  have 
been  struck,  the  ring  is  brought  to  its  original  position  by  the  spring  contained  in  the  barrel  V,  and  the 
pendant  may  then  be  turned  in  the  opposite  direction,  so  as  to  cause  the  other  set  of  pins  to  act  upon 
the  pallet  k and  to  strike  the  quarters.  Its  motion  in  this  direction  is  governed  by  the  position  of  the 
lever  SRT,  of  which  the  end  S rests  upon  the  quarter-snail,  whilst  the  end  T checks  the  steps  cut  in 
the  ring  at  h.  In  the  position  represented  in  Fig.  3764,  the  ring  has  been  turned  as  far  as  possible  in 
this  direction ; for  the  end  S rests  upon  the  highest  step  of  the  snail,  and  has  lifted  the  end  so  high 


836 


WATER-CLOSET. 


that  the  motion  of  the  ring  is  not  checked  until  it  stops  at  the  last  step,  by  which  time  four  pins  have 
passed  the  pallet,  and  four  strokes  have  been  made. 

Denis  new  patent  watch  without  a key. — There  are  two  improvements  which  have  recently  been  made 
in  the  construction  of  watches,  and  patented,  which  will  now  be  described.  The  daily  recurrence  oi 
the  act  of  winding  up  our  watch,  and  its  imperative  necessity,  renders  it  obviously  desirable  that  the 
power  of  doing  this  should  be  facilitated  as  much  as  possible ; and  that  whatever  may  be  the  situation 
in  which  we  may  be  placed,  whether  travelling,  or  in  the  dark,  that  we  should  be  able  to  perform  this 
operation  with  the  greatest  ease  and  certainty : now  the  use  of  a key  detached  from  the  watch,  and 
requiring  to  be  applied  to  a small  hole,  which  must  be  seen  to  be  used,  is  dispensed  with  by  the  im- 
provement alluded  to,  so  that  the  winding  up  of  the  watch  may  be  effected  in  the  dark  by  simply  turn- 
ing part  of  the  pendant,  by  which  the  watch  is  attached  to  the  chain  to  connect  it  with  our  person. 

But  this  improvement  is  not  the  only  one  now  made : thus  much  has  been  partially  accomplished  by 
former  artists,  who,  while  they  rendered  the  watch  independent  of  a key  for  winding  it  up,  suffered  the 
necessity  for  this  adjunct,  for  the  purpose  of  adjusting  the  hands,  still  to  exist,  and  thus  did  not  make 
the  machine  quite  independent  of  appendages  of  any  kind.  By  a simple  contrivance,  which  will  now 
be  described,  it  will  be  seen  that  the  adjustment  of  the  hands  can  also  be  effected  by  the  motion  of  the 
pendant  at  the  pleasure  of  the  wearer,  and  that  with  a greater  latitude  than  could  be  done  under  ordi- 
nary conditions. 

In  Fig.  3 765,  a is  the  knob  next  to  the  pendant-ring, 
but  in  the  improved  watch  independent  of  it,  and  mova- 
ble with  a rotatory  motion  like  a common  watch-key  : 
on  the  axis  b of  this  knob  there  is  a bevelled  pinion 
which  acts  by  means  of  an  intermediate  wheel  c on  a 
larger  one  d,  which  is  carried  on  the  axis  of  the  main- 
spring ; this  completes  the  arrangement  for  simply 
winding  up  the  watch : that  for  setting  the  hands  con- 
sists of  a pinion  e attached  to  the  arbor  of  the  minute- 
hand.  This  pinion,  it  must  be  observed,  is  free  of  the 
wheel  d,  or,  in  technical  language,  not  in  geer  with  it ; 
but  it  can  be  put  so  by  means  of  another  and  equal 
pinion  / which  is  carried  on  an  arm,  or  lever,  moving 
on  a centre  at  g and  terminating  in  a stud  h,  which 
projects  through  the  rim  of  the  case  ; if  this  stud  is 
moved  by  the  finger  from  the  pendant,  the  pinion  / will 
obviously  be  brought  into  geer  with  d,  and  thus  will 
impart  the  motion  of  that  wheel  to  e when  the  hands 
require  setting  ; but  when  the  stud  h is  released,  a 
spring  removes  the  pinion /from  d,  and  the  winding-up 
part  is  detached  as  before.  It  must  be  mentioned, 
that  as  it  is  requisite  to  be  able  to  move  the  hands 
either  backwards  or  forwards,  the  wheel  d is  made  to 
admit  of  motion  from  the  knob  a in  either  direction,  for 
this  purpose.  Since  the  winding  up  must  always  take  place  in  the  same  constant  direction,  there  is  a 
ratchet  and  click  of  the  usual  principle  connected  with  the  wheel  d to  admit  of  this  double  motion : by 
this  arrangement  also,  the  injury  to  the  watch  produced  by  over-winding  is  guarded  against. 

It  will  be  inferred  from  the  foregoing  description  that  the  frequent  necessity  for  opening  the  watch  is 
done  away ; hence  results  another,  and  not  the  least  improvement  effected  by  the  contrivance : in  the 
old  construction  of  the  watch-case,  dust  will  penetrate  to  the  interior  of  the  watch,  however  seldom  it 
may  be  opened,  through  the  number  of  passages  necessarily  consequent  on  the  existence  of  hinges  in 
the  case ; these  being  dispensed  with  in  the  watch  now  described,  the  glass  and  case  are  as  nearly  air- 
tight as  possible,  while  the  dust  which  makes  its  way  in  the  ordinary  watch  to  the  works  each  time  the 
case  is  opened  for  the  purpose  of  winding  up,  or  of  setting  the  hands,  is  now  altogether  excluded ; thus 
cleaning  the  watch  will  not  be  so  frequently  required  as  heretofore. 

WATER-CLOSET — By  G.  Jennings.  This  closet  is  intended  to  remedy  the  defects  of  the  pan  and 
valve  closet.  It  has  neither  the  usual  metal  pan  or  valve,  so  that  no  chamber  is  required,  which  prevents 
displacement  of  pure  air  when  used — an  evil  so  justly  complained  of  in  pan  or  other  closets. 


376G.  3765. 


3707.  3768. 


The  raising  of  the  handle,  as  shown  in  Fig.  3768,  causes  the  water  to  fall  from  the  cistern  to  the 
closet,  and  suddenly  discharges  the  contents  of  the  basin  with  all  its  force  through  a four-inch  India-rub- 
ber pipe,  flushing,  as  it  is  termed,  the  trap  and  soil-pipe  each  time  the  closet  is  used.  The  lowering  of 
the  handle,  as  shown  in  Fig.  3767,  compresses  the  tube,  and  retains  the  water  in  the  b""’"  'T’k« 

water  passes  off  through  the  overflow  pipe,  which  also  regulates  the  proper  quat: 
letained. 


WATER-METRE. 


«37 


This  closet  in  its  action  is  perfectly  silent,  as  the  metal-flaps  fall  without  noise  against  the  India-nib- 
ber  tube.  It  is  also  free  from  all  complication  ; and  a fresh  piece  of  India-rubber  tube,  if  ever  needed, 
will  make  the  closet  as  good  as  new. 

WATER-METRE — By  W.  II.  Lindsay.  The  invention  of  an  instrument  that  will,  on  inspection, 
show  accurately  the  amount  of  water  evaporated  during  any  given  time — as,  for  instance,  during  a voy- 
age— by  a steam-boiler,  is  a desideratum  which  has  long  been  sought  after. 


The  water-gage  represented  in  Figs.  3769  and  3770  is  the  invention  of  William  H.  Lindsay,  con- 
structing-engineer, New  York,  who  has,  after  a large  outlay  of  time  and  money,  succeeded  in  producing 
a durable  and  critically  accurate  instrument,  and  is  the  only  one  yet  brought  into  practical  operation 
which  can  lay  claim  to  that  title.  It  has  been  subjected  to  the  most  thorough  and  repeated  trials,  un- 
der the  supervision  of  many  of  our  most  distinguished  engineers,  and  a board  of  officers  appointed  by  the 
Navy  Department  to  examine  and  leport  upon  its  merits.  The  trials  took  place  after  it  had  been  in 


838 


WATER-METRE. 


operation  more  or  less  every  day  for  the  previous  five  months.  On  measuring  accurately  the  quantity 
of  water  passed  through  it,  in  the  tanks  that  received  it,  and  comparing  the  amount  as  indicated  by  the 
instrument,  the  difference  on  nine  experimental  trials,  under  different  or  varying  circumstances,  was 
found  not  to  exceed  30  cubic  inches  in  one  hundred  thousand. 

By  the  use  of  this  instrument  on  board  steam-ships,  the  owners  will  be  enabled  to  place  themselves  in 
as  advantageous  a position,  in  a pecuniary  point  of  view,  as  that  of  the  Cornish  mine-owners,  who  some 
years  since  adopted  the  system  of  registering  the  duty  performed  by  their  engines,  and  the  amount  of 
fuel  consumed  ; in  other  words,  the  work  done  in  relation  to  the  fuel  consumed  is  registered.  This  ob- 
ject is  accomplished  there  by  means  of  a counter,  which  merely  registers  the  number  of  strokes  made 
by  the  engine  ; but  this  expedient  will  only  answer  where  the  load  upon  the  engine  is  constant  and 
easily  measurable,  but  is  of  no  avail  in  a steam-vessel,  where  the  load  is  continually  var3'ing ; which  can 
only  be  done  by  measuring  and  recording  the  quantity  of  water  evaporated  by  the  boilers,  and  con- 
verted into  steam,  which  is  the  measure  of  the  power  exerted  by  the  engines. 

The  best  proof  of  the  saving  in  fuel  derivable  from  the  plan  of  registering  the  duty  performed  by 
steam-engines,  consists  in  the  enumeration  of  the  wonders  it  has  already  done.  According  to  a report 
made  by  a committee  of  the  House  of  Commons  appointed  to  investigate  the  matter,  it  appears  that  the 
Cornish  mine-owners,  even  in  their  limited  operations,  are  saving  the  sum  of  $400,000  per  year,  by  the 
simple  expedient  of  registering  the  duty  of  their  engines.  If  such  a saving  can  be  realized  by  this  sys- 
tem out  of  the  contracted  sphere  of  Cornish  engineering,  the  results  that  would  ensue  by  its  adoption  in 
our  ocean  steam-ships  are  incalculable.  Such  a practice  insures  a rigid  attention  to  their  duties  on  the 
part  of  the  engineers  and  firemen,  as  any  negligence  will  be  sure  to  tell  to  their  disadvantage.  Its  adop- 
tion puts  all  the  engineers  upon  their  mettle,  and  induces  an  emulation,  out  of  which  improvement  can- 
not but  spring,  with  corresponding  advantages  resulting  to  the  owners.  Yet  the  saving  of  fuel  in  the 
case  of  steam  navigation,  important  as  it  would  be,  is  not  the  greatest  benefit  that  would  be  derived. 
The  powers  of  steam  navigation  would  be  extended,  and  its  profits  correspondingly  augmented.  Re- 
quiring a less  amount  of  fuel  to  perform  the  same  duty,  they  could  carry  more  cargo,  and  the  growth  of 
our  steam  marine  would  just  be  in  proportion  to  the  extension  of  the  limit  which  now  hinders  its  develop- 
ment. It  is  needless,  however,  to  dwell  further  on  the  advantages  derivable  from  the  system  of  regis- 
tration, as  they  must  be  conspicuous  enough  to  every  one  who  gives  attention  to  the  subject,  the  ac- 
knowledgment  of  which  has  been  made  by  its  adoption  in  the  naval  service,  by  order  of  the  Navy  De- 
partment. A series  of  experiments  will  shortly  be  commenced  at  one  of  our  navy  yards  with  one  of 
these  instruments,  by  a board  of  officers  appointed  by  the  Department,  for  the  purpose  of  establishing  a 
standard  of  evaporation  due  the  different  varieties  of  coal  used  for  the  generation  of  steam,  for  the  use 
of  the  naval  and  mercantile  marine ; also  to  institute  a series  of  experiments  to  ascertain  the  relative 
merits  of  boilers  of  different  construction,  which  may  lead  to  the  solution  of  the  problem,  what  are  the 
true  principles  which  should  govern  their  construction  in  every  respect ; and  determine,  beyond  all  cavil, 
the  best-constructed  boiler  in  use  at  the  present  time.  The  results  that  may  be  arrived  at  by  the  use 
of  this  instrument  will  be  a subject  of  much  importance  to  all  concerned  in  steam  navigation. 

Having  given  an  outline  of  the  use  of  this  important  invention,  we  will  proceed  to  give  a description 
of  the  figures,  &c. : — Fig.  3710  is  an  elevation.  Fig.  3769,  sectional  do.  The  figures  are  lengthened 
out,  with  the  view  only  of  showing  the  metre’s  general  arrangement,  without  reference  to  the  economy 
of  space  that  may  be  attained  by  a compact  arrangement  of  its  several  parts. 

Literal  references. — D,  connecting  pipe  from  the  feed-pump  of  the  engine  to  the  drop-valve  chest,  G ; 
E.  an  overflow-valve  chest  bolted  on  the  pipe  E ; F,  air-chamber ; G,  drop-valve  chest  bolted  to  the 
forcing  metre-chamber  or  cylinder  H ; T,  plunger  or  ram  working  in  the  cylinder  H ; R,  metre-cylinder  ; 
L,  plunger  working  in  the  metre-cylinder — the  tYvo  plungers  being  connected  by  a coupling-rod ; M, 
metre  valve-chest  bolted  to  the  cylinder  R;  N,  stop-cock  on  the  pipe  O leading  to  the  boiler  ; R,  feed- 
pipe from  the  hot  well  bolted  to  the  bottom  of  the  valve-chest  M,  for  supplying  the  metre-chamber  R ; 
P,  side-frames,  to  which  the  cylinders  H and  R are  bolted. 

b,  valve  in  chest  E,  loaded  by  means  of  the  springs  attached  to  the  cross-head  on  the  valve  spindle ; 

c,  drop  or  cut-off  valve  in  the  chest  G';  g,  cut-off  valve  spindle  passing  through  a stuffing-box  on  the 
cover  or  bonnet  of  the  drop-valve  chest ; d , stud  keyed  on  the  spindle  g ; e,  an  inclined  slide  receiving 
motion  from  the  connecting  link  y.  It  works  in  a slot  in  the  shde-piece  that  springs  in  under  the  stud 

d.  When  the  valve  c rises,  and  when  it  is  drawn  down  by  the  rod  y,  it  draws  back  the  slide-piece  from 
under  the  stud  d,  thereby  allowing  the  valve  c to  fall  on  its  seat,  and  prevent  the  return  of  any  more 
water  from  the  forcing-cylinder  H through  the  pipe  D into  the  engine  feed-pump,  during  its  exhaust 
stroke,  h 2 li2,  seat  on  the  frame/,  on  which  the  drop-valve  slide  (not  shown)  works,  and  through  which, 
at  the  back  part,  the  inclined  slide  e also  passes  ; / stand  for  the  seat  li2  li2,  its  lower  end  being  bolted 
on  the  bonnet  of  the  chest  G.  Its  upper  end  is  curved,  the  valve-rod  g working  through  it,  which  confines 
the  valve-rod  to  its  place.  There  is  a spring  not  shown  fastened  to  the  inside  of  the  frame  in  its  curved 
portion,  the  lower  end  of  which  being  in  contact  with  a small  stud  on  the  slide-piece  working  on  the 
seat  h 2 li2,  springs  it  under  the  stud  d.  When  the  valve-rod  g rises,  by  the  water  lifting  the  valve  c on  its 
passage  to  the  cylinder  H,  the  slide-piece  retains  the  valve  c,  leaving  a free  passage  for  the  water  to  and 
from  the  cylinder  H and  the  engine  feed-pump  during  the  force  and  exhaust  strokes  of  the  feed-pump 
plunger,  until  such  time  as  the  plungers  T and  L have  completed  their  required  amount  of  force  and 
exhaust  travel,  when,  by  the  motion-rod  l,  on  which  is  keyed  the  bracket  s,  in  the  slot  of  which  is  ad- 
justed the  pin  t,  coming  in  contact  with  the  arm  u,  thereby  giving  motion  to  the  arm  to,  the  connecting 
link  y,  and  the  inclined  slide  e,  the  slide-piece  is  withdrawn  from  the  under  side  of  the  stud  d,  and 
the  valve  c drops  on  its  seat,  having  arrested  the  motion  of  the  plungers  T and  L.  It  remains  at  rest 
until  the  feed-pump  plunger  again  commences  its  force  stroke,  when  the  valve  rises  as  before,  and  is 
again  locked  by  the  slide-piece.  The  motion-rod  has  the  same  motion  as  the  plungers  T and  L,  being 
worked  by  a cross-arm  from  the  plunger  coupling-rod,  (not  shown,)  the  end  of  which  works  on  the 
guide-rod  k.  The  arm  i being  bolted  to  the  cross-arm  at  the  upper  end,  and  keyed  to  the  motion-rod 


WATER-PRESSURE  ENGINE. 


839 


at  the  lower,  the  travel  of  the  plungers  is  recorded  by  means  of  the  rack,  keyed  on  the  rod  b,  giving 
motion  to  the  segment  n,  which  works  freely  on  the  spindle  n 2,  on  which  the  arm  is  keyed.  The  mo- 
tion of  the  arm  is  communicated  by  the  link  h to  the  counter  arm  r,  which  has  a slot  in  it,  by  which 
the  required  length  of  counter  arm  may  be  obtained  by  means  of  a pin  having  a nut  on  the  back.  1, 
feed-valve  in  metre-chest ; 2,  delivery-valve  in  same. 

On  reference  to  the  sectional  figure,  it  will  be  perceived,  that  by  the  drop-valve  c and  the  deliverv- 
valve  2 being  open,  that  the  cylinder  H is  receiving  water  from  the  engine  feed-pump  during  a force 
stroke,  and  that  the  metre-cylinder  R is  discharging,  by  the  advance  of  the  plunger  L into  it,  a quantitv 
of  water  through  the  valve  2 and  the  pipe  0,  provided  the  stop-cock  N is  not  closed,  equal  to  its  area 
of  surface  and  length  of  travel.  But,  supposing  all  the  parts  in  the  position  as  represented,  that  the 
stop-cock  should  now  be  closed,  there  being  no  passage  for  the  water  from  the  cylinder  R,  the  plungers 
are  at  once  brought  to  a state  of  rest,  the  water  from  the  feed-pump  finds  -an  escape  by  lifting  the 
loaded  valve  b,  and  passing  off  by  the  overflow-pipe ; so  in  like  manner  if  the  stop-cock  N is  only  part 
open,  the  plungers  T and  L will  only  move  a distance  equal  to  the  quantity  of  water  received  into  the 
cylinder  H,  the  rest  going  to  waste  by  the  valve  b. 

On  the  engine  feed-pump  plunger  commencing  its  exhaust  stroke,  the  delivery-valve  2 having  closed, 
the  pressure  of  the  water  from  the  hot  well  causes  the  feed- valve  1 to  rise,  admitting  of  a supply  to  the 
cylinder  as  the  plunger  L recedes,  by  reason  of  the  plunger  T being  acted  on  by  the  vacuum  caused 
by  the  exhaust  stroke  of  the  engine  feed-pump  plunger,  and  the  pressure  of  the  water  from  the  hot  well 
on  the  plunger  L,  by  the  plunger  T following  the  vacuum,  the  water  in  the  cylinder  II  during  the  pre- 
vious force  stroke  of  the  engine  feed-pump  is  returned  to  it  on  the  exhaust ; and  in  case  that  only  a part 
of  the  water  discharged  by  the  feed-pump  during  its  previous  force  stroke  should  have  entered  the 
cylinder  H,  by  reason  of  the  stop  cock  IST  being  partly  closed,  the  rest  having  escaped  by  the  valve  b, 
then  the  cylinder  H first  returns  all  it  received,  the  valve-rod  g is  disengaged,  the  valve  c drops,  and  the 
deficiency  is  supplied  to  the  feed-pump  by  the  feed-pipe  from  the  hot  well. 

From  the  above,  it  will  be  seen  that  the  travel  of  the  plungers  L and  T is  dependent  on  the  quantity 
of  water  received  during  each  stroke  of  the  engine  feed-pump  by  the  cylinder  H,  and  the  quantity  of 
water  displaced  from  the  cylinder,  and  thence  into  the  boiler,  is  dependent  on  the  area  of  surface  and 
length  of  travel  of  the  plunger  L ; from  which  it  follows,  that  if  the  travel  of  the  plungers  is  correctly 
recorded,  we  can  at  any  time  ascertain,  by  inspection  of  the  counter-face,  the  actual  amount  delivered. 

WATER-PRESSURE  ENGINE.  The  first  engine  erected  in  England  with  cylinder  or  piston- 
valves,  was  that  put  up  in  the  Alport  mines,  Derbyshire,  in  the  year  1842.  This  was  a single  cylinder 
engine.  Its  success  was  complete,  and  others  were  erected  on  the  same  plan.  But  in  1845,  a com- 
bined cylinder  engine  was  designed,  and  erected  by  the  same  engineer,  which  is  found  practically  to 
have  several  advantages  for  such  large  supplies  of  water  as  that  consumed  by  the  pumping-engine,  ol 
which  we  subjoin  accurate  reductions  of  the  working-drawings. 

3773. 


Fig.  3771  is  a front  elevation  of  the  combined  cylinder  engine.  Fig.  3772  is  a sectional  view,  ana 
Fig.  3773  is  a general  plan.  PC  is  the  bottom  of  the  pressure  column,  130  feet  high,  and  24  inches 
internal  diameter.  C C are  the  combined  cylinders,  each  24  inches  diameter,  open  at  top,  with  hemp- 
packed  pistons  a,  Fig.  3772,  and  piston-rods  m , combined  by  a cross-head  n,  working  between  guides  in 
a strong  frame.  The  admission  throttle-valve  is  a sluice-valve,  shown  at  o,  Fig.  3771,  and  between  the 
letters  b and  e in  Fig.  3773.  The  main  or  working  valve,  is  a piston  g,  18  inches  in  diameter,  Fig.  3772, 
with  its  counter  or  equilibrium  piston  above.  The  orifice  for  the  admission  of  the  pressure  water  is 
netween  the  two  pistons.  The  intermediate  pipe  a is  a flat  pipe,  into  which  numerous  apertures  lead 
from  the  valve-cylinder,  seen  immediately  under  g,  Fig.  3772.  The  valve-piston  is  in  the  position  for 
discharging  the  water  from  the  cylinders  through  the  pipe  e,  Fig.  3772,  by  the  sluice-valve  k. 

The  valve-geer  is  worked  by  an  auxiliary  engine  h,  by  means  of  the  lever  v.  The  auxiliary  engine- 
valves,  are  piston-valves  in  the  valve-cylinder  i,  Figs.  3772  and  3773,  communicating  with  the  pressure- 
pipes  by  a small  pipe,  provided  with  cocks,  as  shown  in  Fig.  3773.  The  motion  of  the  auxiliary  engine- 
valves  is  effected  by  a pair  of  tappets  t’ t",  set  on  a vertical  rod  attached  to  the  cross-head  n.  These 
tappets  move  the  fall-bob  b,  by  means  of  the  cauti-lever  t,  Fig.  3771,  the  other  end  of  the  lever  beins 


840 


WATER-PRESSURE  ENGINE. 


linked  to  the  rod  s,  Fig.  3772,  (s,  Fig.  3771,  is  misplaced,)  -which  again  is  linked  to  the  auxiliary  piston- 
valve  rod. 

The  play  of  the  machine  is  now  manifest.  It  is  in  every  respect  analogous  to  the  Harz  and  Huel- 
goat  engines,  described  by  Weisbach.  The  average  speed  of  the  engine  is  140  feet  per  minute,  or  7 
double  strokes  per  minute.  This  requires  a velocity  of  something  less  than  2-^r  feet  per  second  of  the 
water  in  the  pressure-pipes  ; and  as  all  the  valve  apertures  are  large,  the  hydraulic  resistances  must  be 
very  small.  The  engine  is  direct-acting,  drawing  water  from  a depth  of  135  feet,  by  means  of  the 
spear  ww,  Figs.  3771  and  3772.  The  “box,”  or  bticket  of  the  pump,  is  28  inches  in  diameter,  so  that 


3771. 


the  discharge  is  266  gallons  per  stroke,  or  when  working  full  speed,  1862  gallons  per  minute.  The 
mechanical  effect  due  to  the  fall  and  quantity  of  water  consumed  is  nearly  140  horse-power.  The 
mechanical  effect  involved  in  the  discharge  of  the  last-named  quantity  of  water  is  nearly  74  horse- 
power, so  that  supposing  the  efficiency  of  the  engine  and  pumps  to  be  on  a par  with  each  other,  the 


efficiency  of  the  two  being  r j,  = 71'15,  the  efficiency  of  the  engine  alone  r> 


1 + Vi 


1 + T1 
2 


•85,  oi 


n the  language  of  Cornish  engineers,  85  per  cent,  is  the  duty  of  the  engine. 


WATER-WHEELS. 


841 


WATER-WHEELS — -Theory  and  Construction  of.  Although  in  localities  where  mineral  reservoirs 
of  motive  power  are  convenient,  the  ever-available1  steam-engine  has  much  diminished  the  importance 
of  hydraulic  movers,  these  must  always  continue  to  be  the  most  economical,  and  therefore  the  most 
frequently  resorted  to,  in  situations  where  the  liquid  element  can  be  attained  in  sufficient  abundance, 
and  under  the  necessary  circumstances  to  answer  the  conditions  contemplated.  A waterfall  is  rendered 
available  comparatively  without  labor,  and  furnishes  its  supplies  without  the  intervention  of  human  aid 
The  energies  of  the  steam-engine,  on  the  contrary,  can  be  commanded  in  any  situation,  only  by  the 
influence  of  the  miner ; and  in  localities  much  removed  from  sources  of  fuel,  can  only  be  sustained  at 
an  expense  which  falls  heavily  upon  the  operations  to  which  they  are  subservient.  That  expense,  it  is 
true,  is  continually  being  diminished,  and  by  means  of  the  steam-engine  itself,  in  its  character  of  a car- 
rier ; but  no  happy  discovery,  no  possibility,  can  reduce  it  to  the  minimum  at  which  our  water-runs  are 
maintained. 

But  while  water-power  has  the  advantage  of  economy,  where  it  is  abundant  and  constant,  in  other 
localities  where  it  is  more  immediately  dependent  upon  the  condition  of  the  seasons,  it  is  under  the  dis- 
advantage of  being  less  certain,  and  less  under  control,  than  the  more  artificial  agency  developed  in  the 
steam-engine.  It  is  this  independence  of  time  and  season,  of  circumstances  and  locality,  which  mark 
the  great  superiority  of  this  potent  creation  of  engineering  skill,  and  which,  in  its  multiform  applications 
and  applicability,  have  invested  it  with  an  importance  and  an  interest  which  success  seems  only  to 
stimulate  and  render  more  intense.  The  complexity  of  parts,  and  the  diversity  of  combination,  offer  a 
scope  for  the  exercise  of  ingenuity,  alike  highly  inviting  to  the  theoretical  and  the  practical  mechanic. 
The  steam-engine,  even  as  a stationary  power,  is,  moreover,  of  recent  origin ; and  contemplating  the 
phases  which  it  has  already  assumed,  in  connection  with  the  general  feeling  that  its  energies  have  not 
yet  been  fully  developed,  it  is  not  matter  of  wonder  that  it  has  diverted  attention  from  the  less  inviting 
problem  which  we  are  about  to  discuss.  Water-power  is  an  old,  if  not  an  antiquated  subject,  on  which 
the  light  of  modern  improvement  has  been  but  feebly  reflected  since  the  days  of  Smeaton.  With  a few 
exceptions,  it  has  been  abandoned  to  the  management  of  those  who  recognize  in  it  no  principle,  and  no 
scope  for  improvement ; and  whose  practice  is  not  more  opposed  to  improvement  than  it  is  empirical 
and  opposite  to  all  true  principle. 

The  fact  that  water-power  is  an  agency  which  cannot  be  augmented  at  pleasure,  and  which,  in  most 
situations  where  it  is  employed,  has  a full  share  of  duty  imposed  upon  it,  renders  it  desirable  that  the 
best  means  of  economizing  it  be  adopted.  This  implies  a knowledge  of  some  of  the  fundamental  prin- 
ciples of  hydraulics,  in  addition  to.  that  acquaintance  with  the  general  laws  of  mechanics  which  every 
engineer  is  assumed  to  possess.  It  is  with  the  view  of  placing  the  subject  in  a distinct  and  concise 
form,  and  of  pointing  out  precisely  those  principles  which  ought  to  guide  the  practice  of  the  engineer 
in  his  dealings  with  this  agency,  that  we  undertake  a brief  exposition  of  the  general  problem.  Under 
the  title  assumed,  is  implied  the  economy  of  water-power,  and  the  various  means  of  rendering  it  avail- 
able for  purposes  of  industry.  Without  avoiding  those  abstract  questions  which  beset  the  subject,  and 
which  imply  some  acquaintance  with  elementary  analysis,  we  shall  endeavor  to  keep  in  view  that 
theory  is  valuable  only  in  its  relations  to  practice. 

Characteristic  varieties  of  water-wheels , and  the  theory  of  their  action. — By  far  the  most  numerous, 
and,  therefore,  important  order  of  hydraulic  movers,  are  those  which  come  under  the  denomination  of 
vertical  wheels , from  their  movement  being  in  vertical  planes,  and  their  axis  of  rotation  consequently 
horizontal.  Of  these  we  have  three  varieties — named  according  to  the  points  at  which  the  water  is 
received  upon  the  periphery — overshot,  undershot , and  breast  wheel.  This  last  is  further  distinguished 
as  high  and  low  breast,  according  as  the  water  is  received  upon  the  wheel  above  or  below  the  horizontal 
plane  of  the  axis.  When  the  point  of  reception  approaches  the  lowest  point  of  the  circle,  it  becomes 
an  under  shot-wheel ; and  on  the  contrary,  when  the  water  is  laid  on  within  a few  degrees  of  the  sum- 
mit, it  takes  the  name  of  overshot. 

A second  order,  of  which  the  varieties  are  more  numerous,  and  even  less  distinct,  come  under  the 
denomination  of  horizontal  wheels,  because  they  move  in  planes  parallel  with  the  .horizon,  and  conse- 
quently have  their  axis  of  rotation  vertical.  Of  these,  the  best  known  types  are  the  reaction-wheel, 
the  turbines  of  Burdin,  Fourneyron,  and  Jonval,  the  tub-wheels  of  America,  (the  moulines  a cuve  of  the 
French,)  and  the  wlieelets  common  in  the  south  of  France  (in  Provence  and  Dauphine),  and  which  con- 
sist simply  of  a series  of  spoon-shaped  (and  somet  imes  flat)  paddles  or  floats,  set  on  the  periphery  of  a 
strong  wooden  axis,  and  against  which  the  water  is  projected  from  a conical  adjutage.  The  danaide, 
better  known  to  theory  than  practice,  belongs  to  the  same  order. 

The  effects  of  these  different  varieties  of  wheels  arise  from  three  sources — weight,  impulse,  and  re- 
action. But  in  stating  these  as  the  primary  and  simple  elements  of  hydraulic  power,  it  is  to  be  re- 
marked that  we  very  rarely  find  the  effect  reducible  to  a single  mode  of  action  ; more  commonly  we 
find  two,  and  sometimes  even  the  three  acting  simultaneously,  and  not  unfrequently  in  nearly  equal 
degrees.  Centrifugal  force  is  also  an  element  which  in  most  forms  of  wheels  requires  to  be  appreciated ; 
and  in  some  constructions — the  reaction-wheel,  for  example — it  is  the  most  difficult  influence  which 
enters  into  the  calculation  of  the  ultimate  effect. 

Directing  our  attention,  in  the  first  instance,  to  the  element  of  weight,  it  is  easy  to  prove  that  when 
a given  volume  of  water  descends  through  a known  height  H,  its  effect,  as  a mechanical  agent,  will  be 
expressed  by  the  product  of  the  weight  into  the  height  H fallen  through.  Asa  familiar  illustration,  in 
lieu  of  a more  precise  demonstration,  take  the  case  of  a horse  drawing  a load  upon  a horizontal  road, 
and  suppose  that  the  movement  is  uniform  over  a certain  distance : the  constant  effort  exercised  by  the 
) orse  may  manifestly  be  measured  by  a dynamometer  placed  between  the  horse  and  the  load.  Sup- 
posing this  done,  and  that  the  number  of  lbs.  indicated  by  the  instrument  as  the  force  expended  by  the 
animal  in  moving  the  load  is  P,  and  that  the  distance  travelled  over  is  D feet ; the  product  P X D,  or 
simply  P L,  will  be  a measure  of  the  amount  of  effort  exercised  by  the  animal  in  passing  over  the  given 
distance  D.  Now  if,  in  place  of  the  horse,  we  suppose  a weight  of  W lbs.  to  be  attached  to  the  load. 


842 


WATER-WHEELS. 


by  a rope  passing  over  a pulley  fixed  in  the  mouth  of  a pit,  of  the  depth  H,  equal  to  the  length  D,  thl 
pulley  being  assumed  to  have  no  friction,  and  the  rope  no  weight,  (conditions  which  can  be  virtually 
attained,)  the  weight  W,  which  is  a measure  of  the  constant  effort  exerted  by  the  animal,  will  descend 
and  drag  the  carriage  along  the  level  road  with  the  same  uniform  velocity,  and  arrive  at  the  bottom  of 
the  pit  at  the  same  moment  that  the  horse  would  have  arrived  at  the  extremity  of  the  distance  D.  In 
both  cases,  the  carriage  passes  over  the  same  space  and  with  the  same  velocity ; the  weight  W is  there- 
fore capable  of  effecting  all  that  the  horse  had  done  ; as  a prime  mover,  it  is  therefore  identical.  It  has 
given  the  same  quantity  of  action  W X II  or  W H = P D in  the  same  time.  Its  dynamical  effect  may 
therefore  be  expressed  in  terms  of  the  power  of  the  horse,  as  a known  unit.  And  in  general  the  power 
developed  by  any  mover,  animate  or  inanimate,  may  in  like  manner  be  measured  by  that  of  a weight 
W descending  through  a certain  height  H,  and  expressed  by  the  product  W H. 

Keeping  this  principle  in  view,  it  is  further  obvious  that  the  greater  the  height  through  which  the 
weight  descends,  the  greater  will  be  the  effect  produced.  But  as  a current  of  water  may  be  regarded 
as  a continuous  succession  of  weights,  descending  from  the  higher  to  the  lower  level,  it  is  necessary  to 
ascertain  the  rate  of  succession — in  other  words,  the  measure  of  the  weight  which  descends  in  a given 
unit  of  time.  Let  that  unit  be  1 minute,  and  let  the  quantity  of  water  flowing  be  500  cubic  feet,  which 
multiplied  by  624,  the  weight  in  lbs.  of  a cubic  foot  of  water,  gives  31,250  lbs.  as  the  weight  which  has 
descended  in  a minute.  Further,  let  it  be  supposed  that  the  whole  height  H,  through  which  it  descends, 
that  is,  the  whole  height  of  the  fall  or  head , is  120  feet;  if  this  quantity  of  water  be  made  to  act  upon 
the  circumference  of  a gigantic  overshot-wheel,  so  constructed  as  to  be  free  from  all  those  detrimental 
influences  to  be  hereafter  considered,  and  the  wheel  be  attached  by  a suitable  connection  to  a train  of 
carriages  upon  an  incline,  which  by  experiment  is  found  to  require  the  application  of  a force  (measured 
dynamometrically)  of  31,250  lbs.  to  move  it  through  120  feet  in  a minute,  then,  the  power  and  resistance 
being  equal,  the  water  will  give  motion  to  the  wheel,  and  descend  with  it  through  the  height  of  a fall 
equal  to  120  feet  in  the  same  time  that  the  load  is  moved  through  an  equal  distance  upon  the  incline. 
In  this  case  we  have  manifestly  WH  = PD,  since  W = P,  and  H = D.  The  first  of  these  conditions 
only  is  necessary  to  establish  an  equality  of  dynamical  action.  Let  us  assume  the  height  of  the  fall  to 
be  reduced  to  30  feet,  and  the  force  necessary  and  sufficient  to  drag  the  train  of  carriages  up  the  incline, 
with  a velocity  of  120  feet  a minute,  to  be  only  78121-  lbs.,  the  other  conditions  remaining  unchanged, 
the  quantity  of  water  constantly  in  action  upon  the  circumference  of  the  wheel  will  be  4th  of  31,250 
lbs.  = 78124  lbs.,  since  the  rate  of  descent  is  120  feet  per  minute ; and  the  distance  4th  of  120  feet,  or 
30  feet.  In  this  case,  D = 4 X H,  and  W = 31,250  lbs.  of  water  expended  in  the  unit  of  time  is  equal 
to  four  times  the  load  moved  ; but  4 W X H = 4 P X D is  W II  = P D,  by  cancelling  the  common 
multiplier  4- 

The  dynamical  force  of  a current  of  water  is  therefore  correctly  represented  by  W H lbs.  per  minute ; 
and  since  the  height  of  fall  H feet  is  independent  of  the  time,  W lbs.  must  express  the  weight  of  water 
which  descends  in  a minute.  A stream  on  which  there  is  a fall  of  30  feet,  with  a supply  of  500  cubic 
feet  of  waiter  per  minute,  will  afford  the  same  amount  of  power  as  another  stream  of  1000  cubic  feet 
with  a fall  of  15  feet,  the  product  W H of  the  two  factors  being  the  same,  whether  we  take  30  X (500 
X 624),  or  15  X (1000  X 62-4). 

In  thus  estimating  the  motive  force  of  a current  of  water,  the  height  H is  the  difference  of  level  be- 
tween the  surface  of  the  water  at  the  higher  and  lowTer  points  between  which  its  power  is  developed. 
This  is  termed  the  fall,  and  is  either  real  or  Active  : it  is  real  when  the  fluid  descends  abruptly  from  a 
higher  to  a lower  level,  and  Active  when  it  acts  in  virtue  of  a velocity  of  motion  due  to  that  height.  Thus 
if  a current,  flowing  in  an  inclined  channel,  be  ascertained  by  experiment  to  have  a uniform  velocity  of 
12  feet  in  a second,  then  we  know,  from  the  laws  of  falling  bodies,  that  the  fictive  head  is  2-25  feet 
nearly,  and  is  found  from  the  formula  Y = g H.  In  this  formula,  V expresses  the  velocity  of  the 
current  in  feet  per  second,  and  g = 32-2  feet  the  velocity  communicated  to  a falling  body  by  gravity  at 
the  end  of  the  first  second,  when  it  falls  freely.  H is  the  height  capable  of  generating  the  velocity  V, 
Va 

and  is  therefore  represented  by  — 0'0155  V2 ; and  if  s be  the  area  of  the  cross  section  of  the  fluid  cur- 
rent in  square  feet,  then  the  weight  of  water  passing  a given  point  in  a second  will  be  62'5  s V;  and 
therefore  the  whole  dynamical  force  in  a second  will  be  expressed  by 

62-5  s V X 0-0155  V2  = 0'97  s V3, 

and  this  result  multiplied  by  the  number  of  seconds  in  a minute,  the  unit  assumed  in  speaking  of  the 
dynamical  value  of  a real  fall  of  H feet,  gives  W H = 58  23  s V3. 

In  illustration : let  the  mean  velocity  of  a current  be  10  feet  per  second,  the  mean  depth  2 feet,  and 
the  mean  width  15  feet ; then  V3  = 1000,  and  s = 30  square  feet ; 


. • . W H = 58-23  X 30  X 1000  = 1746900, 


the  dynamical  force  of  the  current,  of  which  the  fictive  head  is  0 0155  V2,  equivalent  to  1'553  feet,  and 
the  quantity  of  water  flowing  per  minute  is  1,125,000  lbs. 

Tiie  fictive  head  of  a stream  flowing  in  an  inclined  channel  may  then  be  determined  in  terms  of  a 
real  or  vertical  head,  and  measured  accordingly.  They  are,  indeed,  mutually  convertible  ; and  were  it 
not  that  the  expression  W H is  arithmetically  more  convenient  than  58-128  s V3,  we  might  in  every 
case  determine  H in  terms  of  V,  and  employ  the  latter  formula  in  our  calculations  of  the  power  of  a 


ivaterfall.  Thus  generally  II  = : — ; therefore,  if  II  be  known,  the  value  of  Y can  be  readily  deter- 
64'4 


mined ; and  conversely,  if  V be  ascertained,  the  corresponding  value  of  H may  in  like  manner  ba 
found. 

We  have  hitherto  employed  these  expressions  abstractly;  but  in  speaking  of  the  dynamical  force  o; 


WATER-WHEELS. 


843 


a fall  of  water,  it  is  found  convenient  to  introduce  a unit  of  comparison  by  which  the  amount  may  be 
more  readily  conceived.  The  mind  does  not  readily  apprehend  the  value  of  a product,  even  of  such 
magnitude  as  1,746,900 ; and  it  is  often  necessary  to  deal  with  much  higher  results.  In  this,  as  in  all 
other  estimates  of  mechanical  power  on  a large  scale,  the  unit  adopted  is  the  horse-power,  reckoned  at 
150  lbs.  raised  through  a height  of  220  feet  in  a minute,  or  33,000  lbs.  1 foot  high  per  minute — as  from 
the  bottom  of  a mine  by  a rope  passing  round  a pulley.  This  is  the  unit  introduced  by  Watt  in  rating 
his  steam-engines,  and  is  supposed  to  have  been  taken  as  the  maximum  work  of  the  London  dray 
horses.  The  estimate  is  found  to  be  a third  part  too  high,  as  applied  to  draught  horses  generally ; but 
as  a measure  of  dynamical  force,  when  applied  to  inanimate  sources  of  power,  it  is  unexceptionable  on 
that  account.  The  object  is  served  by  a definition  of  the  unit ; and  horse-power  is  a name  less  objec- 
tionable than  any  others  which  have  been  proposed,  unless  we  are  to  except  the  cheval  vapeur  of  the 
French  writers. 

We  have  already  shown  that  the  magnitude  of  the  individual  factors  of  the  product  W II  may  rel- 
atively change  without  affecting  the  result.  Now,  in  the  estimate  of  the  horse-power,  we  have  taken 
150  lbs.  = W raised  (or  descending)  through  220  feet  = H in  a minute  ; but  these  numbers  will  mani- 
festly give  the  same  product  by  multiplication  as  33,000  lbs.  — W,  raised  (or  descending)  through  1 
foot  = H in  a minute.  This  affords  the  simpler  enunciation,  and  is  that  uniformly  adopted. 

To  estimate,  therefore,  the  moving  force  of  a current  of  water  in  units  of  this  kind,  it  is  only  neces- 
sary to  divide  the  product  W H by  33,000,  and  the  quotient  will  indicate  the  equivalent  in  horse-power. 
Thus  in  the  example  above,  we  find  W H = 1,746,900  dynamic  units;  which  divided  by  33,000  gives 
52'936  as  the  horse-power  of  the  current. 

The  same  result  may,  of  course,  be  obtained  by  taking  the  reciprocal  of  33,000  = ‘000030,303  as  a 
multiplier.  And  if  we  take  Q to  represent  the  number  of  cubic  feet  of  water  supplied  in  a minute,  we 


shall  have  W = 62'5  Q,  and,  therefore, 


62‘5  Q II 
33,000 


QH 

523 


■0018,939  QHwill  express  the  horse-power 


of  the  current.  Thus  in  the  preceding  example,  the  fall  due  to  a velocity  of  10  feet  per  second  is  1 ‘5 5 3 
feet  = H,  and  the  quantity  of  water  supplied  per  minute  will  be  (2  X 15  X 10)  X 60  = 18,000  cubic 
feet  - Q.  Then  ‘0018939  X 18,000  X 1'553  = 52‘94  horse-power  as  before  determined. 

It  may  also  be  here  observed,  that  33,000  lbs.  raised  a foot  in  a minute  being  the  same  as  550  lbs. 
raised  to  the  same  height  in  a second,  if  we  take  w to  represent  the  weight  of  water  supplied  in  the 


WH 

smaller  unit  of  time,  then  will  ■ = ‘00182  W H represent  the  horse-power  of  the  stream.  Thus  in 

WH 

the  preceding  example,  w = 300  X 62J  = 18,750  lbs. ; and  II  = 1‘553  ; therefore,  ■ ■ = 52‘94  horse- 


power as  before. 

Also,  since  550  lbs.  = 8 8 cubic  feet  of  water,  if  q be  the  number  of  cubic  feet  furnished  per  second, 
then  2-—  will  in  like  manner  represent  the  horse-power  of  the  current. 

O'O 


As  all  calculations  of  the  velocity  are  referred  to  a second  as  the  unit  of  time,  these  forms  of  expres- 
sion will  sometimes  be  useful  in  our  subsequent  investigations,  and  may  be  borne  in  mind. 

We  have  hitherto  spoken  of  the  power  of  the  water;  but  in  the  application  of  a motive  power  by 
means  of  machinery,  we  in  no  case  realize  the  theoretical  effect.  To  produce  an  effect  by  a machine, 
is  to  overcome  the  resistances  continually  and  periodically  reproduced  in  a direction  opposed  to  the 
direction  of  the  moving  force  during  the  time  of  its  action  ; but  in  this  a certain  loss  invariably  occurs. 
Thus,  confining  our  attention  to  the  agency  under  consideration,  all  the  force  W H of  a current  of  water 
directed  upon  the  buckets  of  a water-wheel  does  not  take  effect.  A part  of  the  water  W commonly 
escapes,  especially  in  low  breast  and  undershot  wheels,  between  the  wheel  and  the  arc  by  which  the 
water  is  confined ; and  a part  of  the  head  H is  also  lost,  both  on  the  entrance  of  the  water  upon  the 
wheel  and  on  its  leaving  it.  To  these  sources  of  loss  we  must  generally  add  the  amount  of  motive 
force  annihilated  by  the  counteraction  or  hack  lash  of  the  water  in  striking  the  buckets,  and  the  con- 
traction of  the  stream  at  the  penstock.  These  circumstances,  to  which  we  shall  return,  prevent  the 
transfer  of  a certain  amount  of  the  power  possessed  by  the  water  to  the  wheel ; but  there  are,  besides, 
absorbing  influences  which  diminish  the  useful  effect  of  the  power  actually  developed.  In  the  machine 
itself,  we  have  the  friction  of  the  journals ; and  if  the  velocity  be  high,  as  in  horizontal  wheels  working 
under  high  falls,  the  resistance  of  the  atmosphere  becomes  a sensible  quantity.  At  the  geering  by 
which  the  power  is  transmitted  to  the  working  points,  another  loss  takes  place  by  the  friction  and 
shocks  of  the  teeth — individually  very  small,  it  is  true,  but  being  constantly  and  often  repeated,  the 
sum  becomes  an  appreciable  quantity. 

These  resistances,  which  for  our  present  purpose  it  is  sufficient  to  indicate,  being  in  some  part  essen- 
tial to  every  arrangement  of  mechanism,  have  in  consequence  obtained  the  name  of  passive  resistances, 
in  contradistinction  to  active  resistance,  by  which  we  understand  the  useful  effect  developed.  The  sum 
of  the  two — that  is,  the  whole  resistance  overcome  by  the  machine,  active  and  passive,  useful  and  non- 
productive— is  its  dynamic  effect,  and  is  less  than  the  dynamical  effect  of  the  water  expended  by  the 
amount  of  loss  incurred  by  the  factors  W X H. 

From  what  has  been  observed,  respecting  the  development  of  mschanical  power,  its  measurement 
Deing  the  force  requisite  to  elevate  a given  weight  through  a known  space  in  a defined  unit  of  time,  it 
is  manifest  that  the  higher  the  velocity  of  the  machine,  the  greater  will  be  its  efficiency,  supposing 
always  the  resistance  overcome  to  preserve  the  same  intensity.  If,  therefore,  we  put  w to  represent 
the  weight  equivalent  to  the  useful  or  active  resistance,  and  v the  velocity  with  which  it  is  overcome, 
also  w'  X v'  to  denote  the  same  quantities  in  respect  of  the  passive  resistances,  we  shall  have  as  the 


844 


WATER-WHEELS. 


expression  of  the  ■whole  dynamical  effect  of  the  machine,  wv  v'.  But  as  all  resistances,  active 
and  passive,  upon  the  machine  are  reducible  to  the  common  velocity  v,  we  may  put  W to  represent 
their  entire  sum ; and,  therefore,  denoting  by  E the  whole  dynamical  effect,  we  shall  have  E = W «. 
In  words : the  effect  of  the  mover  is  equal  to  the  resistances  overcome. 

From  this,  we  observe  that  the  effect  does  not  depend  upon  the  magnitude  of  the  individual  factors, 
but  upon  that  of  their  product.  By  means  of  geering,  the  working  speed  may  be  made  a hundred  or  a 
thousand  times  greater  or  less  than  that  of  the  first  mover ; but  when  this  is  the  case,  the  weight  ele- 
vated will  be  correspondingly  diminished  or  increased  in  amount,  agreeably  to  the  maximum  univer- 
sally recognized  in  mechanics,  that  whatever  is  gained  in  speed  is  lost  in  force,  and  vice  versa. 

The  factor  v is  in  practice  easily  ascertained  by  observation ; but  W being  the  sum  of  resistances 
opposed  to  the  movement  of  the  machine,  and  often  consisting  of  many  particulars  imperfectly  ascer- 
tained, and  only  ascertainable  by  direct  experiment,  usually  of  some  difficulty,  this  factor,  and  conse-' 
quently  the  whole  effect  E,  does  not  always  partake  of  that  certainty  which  is  desirable,  in  comparing 
the  work  done  with  the  power  expended.  But  this  last,  which  we  have  represented  by  W H,  being 
always  greater  than  E,  we  know  that  whatever  may  be  the  efficiency  of  the  wheel,  these  forces  must 
have  the  relation  E = in  W H,  in  which  m is  a fraction  less  than  1,  but  different  in  different  cases  and 
conditions,  and  only  determinable  by  direct  experiment.  Taking  the  force  expended,  viz.,  ¥H  = 1, 
the  coefficient  m will  express  the  ratio  of  the  effect  realized  in  the  active  and  passive  resistances  of  the 
mover  to  that  force.  It  can  never  equal  1,  for  then  the  whole  moving  force  would  be  realized  by  the 
wheel,  which  cannot  possibly  happen  by  any  adaptation  hitherto  discovered  ; much  less  can  it  exceed  1, 
which  would  imply  that  the  power  realized  is  greater  than  that  expended.  The  values  which  it  bears 
in  particular  cases  will  be  subsequently  investigated  at  considerable  length,  taking  as  the  basis  of  dis- 
cussion the  numerous  experiments  which  have  been  directed  to  its  determination.  In  the  mean  time,  it 
will  be  sufficient  to  observe,  that  it  very  rarely  exceeds  0 80,  and  not  unfrequently,  in  undershot-wheels, 
it  falls  below  0’25.  In  wheels  coming  under  the  denomination  of  high  breast  and  overshot,  the  common 
value  ranges  from  0-75  to  0-66. 

The  formula  E = a WH  is  general ; it  applies  to  any  hydraulic  mover  under  any  circumstances, 
and,  therefore,  the  effect  and  producing  cause  may  always  be  thus  compared.  When  the  fall  is  Active, 
we  have  seen  that  it  may  be  determined  in  terms  of  H,  from  the  known  relations  of  the  velocity  Y 
generated  in  the  current,  to  the  generating  head  H.  But  in  the  case  of  an  undershot-wheel  acting  by 
a Active  head,  although  the  formula  of  ultimate  comparison  remains  the  same  as  for  an  overshot-wheel 
acting  under  a real  head,  the  mode  of  action  is  different,  and  requires  a separate  consideration.  Taking 
a case  of  the  most  simple  kind,  in  which  the  wheel  is  furnished  with  radial  floats,  and  acts  in  a confined 
rectilineal  course,  in  which  the  current  of  water  flows  with  a velocity  of  V feet  per  second,  it  is  obvious 
that  the  motion  of  the  floats  must,  under  the  supposition  of  the  wheel  beiffg  burdened,  be  less  than  Y 
when  impelled  by  the  current ; since  it  is  clear  that  the  fluid  could  have  no  effect  upon  them  if  they 
moved  at  the  same  velocity,  and  would  retard  rather  than  impel  the  wheel  at  any  higher  velocity. 
Moreover,  in  impelling  the  floats  at  a given  velocity  v,  there  must  remain  in  the  water,  after  it  has 
passed  the  wheel,  a certain  velocity  which  is  always  greater,  and  cannot  manifestly  be  less  than  v.  If, 
according  to  the  supposition,  the  floats  so  completely  occupy  the  watercourse  that  no  particle  of  the 
fluid  can  pass  without  acting  upon  them,  the  velocity  retained  by  the  current  would  evidently  be  the 
difference  between  the  initial  velocity  V,  and  that  imparted  to  the  surfaces  opposed  to  its  motion.  But 
this  condition,  although  not  actually,  is  virtually  fulfilled  in  every  case  analogous  to  that  assured,  how- 
ever imperfect  the  arrangements  in  scheme  and  construction.  Although  a highly  mobile  fluid,  there  is 
a certain  cohesion  among  the  particles  of  a current  of  water,  by  which  an  equilibrium  of  motioii  is,  if  not 
uniformly  maintained,  at  least  quickly  established  in  cases  of  disturbance.  The  interruption  offered  tc 
one  portion  of  the  mass  is  speedily  communicated  to  the  whole.  The  uninterrupted  particles,  by  the 
mutual  cohesion  existing  in  the  mass,  act  upon  those  to  which  the  interruption  has  occurred,  and  there- 
by reciprocally  communicate  and  lose  a portion  of  the  velocity  which  they  possessed.  An  equilibrium 
may  not  be  thus  instantaneously  established.  Like  other  ponderous  bodies,  the  fluid  particles  possess 
inertia,  and,  therefore,  require  time  to  receive  and  communicate  motion ; but  the  action  is  no  less  certain 
and  essential  to  the  conditions  assumed.  We  may,  consequently,  without  risk  of  error,  presume  that 
in  all  cases  the  velocity  retained  by  the  water  after  it  has  acted  upon  the  float  of  the  wheel,  will  be 
fairly  expressed  by  V — v.  This  velocity  is,  moreover,  lost  as  respects  the  efficiency  of  the  wheel:  it 
has  produced  no  effect.  Now,  from  what  has  been  before  stated,  we  know  that  the  head  equivalent  to 


V2 

the  initial  velocity  V of  the  current  may  be  expressed  by  — — ; and  extending  the  same  principle  to  the 

~9  v 2 

velocity  v communicated  to  the  wheel,  the  head  equivalent  will  be  expressed  by— — ; and  the  head  lost 

J (V— -vf 

in  consequence  of  the  unemployed  velocity  V — v will,  in  like  manner,  be  represented  by  — . The 


vertical  section  of  the  stream  being,  therefore,  designated  as  before  by  s , the  whole  weight  of  water 
acting  upon  the  wheel,  in  a second  of  time,  will  be  represented  by  62'5  s V,  and  this  multiplied  by  60 
will  be  the  quantity  acting  in  a minute  = W.  The  dynamical  effect  of  the  impulse  will;  therefore,  be 
expressed  by 

(V2  d2  (V  — A2\  W 

— J reducible  to  — (V  — v)v 

2 3 *3  2 g ) gK 

by  performing  the  operations  indicated.  And  designating  by  li  h'  h",  the  heights  of  head  due  to  the 
three  velocities  Y,  v,  and  V — v,  we  have  the  equivalent  expression 

W Ih  — h'  — h”\ 


WATER-WHEELS. 


845 


The  two  last  terms  in  the  parentheses  manifestly  diminish  the  effect  produced.  Were  they  zero,  this 
effect  would  then  be  W h,  which  is  the  whole  dynamic  force  of  the  current,  since  h represents  the  total 
head  due  to  the  velocity  V.  In  order  that  the  first  of  the  two  last  terms  may  be  zero,  it  i*necessary 
that  v = 0 ; and  on  this  supposition,  the  whole  expression  vanishes,  showing  that  no  effect  is  realized — 
which  is  manifestly  the  case  where  the  wheel  has  no  velocity.  The  expression  further  shows  that  the 
velocity  preserved  by  the  water  after  it  had  acted  upon  the  floats  depends  upon  the  relation  of  V and 
v,  and  in  order  that  V — v = 0,  the  wheel  must  have  the  same  velocity  as  the  current.  In  this  case  also 
the  whole  expression  vanishes,  or  the  power  realized  is  nothing ; for  then  the  whole  force  of  the  water 
will  be  absorbed  by  its  own  velocity,  and  could  only  turn  the  wheel  at  an  equal  velocity  when  the 
burden  (including  its  own  weight  and  passive  resistances)  of  the  w7heel  is  nothing.  The  formula  is, 
therefore,  consistent  with  itself  in  the  most  extreme  cases,  and  may  be  accepted  as  a fair  representation 
of  the  effect  realized  in  all  intermediate  conditions. 

There  are  other  modes  of  establishing  the  rule,  which  it  may  be  at  least  satisfactory  to  state,  more 
especially  as  it  will  be  necessary  to  resort  to  them  in  a subsequent  part  of  the  inquiry.  According  to 
a well-known  notation  in  dynamics,  the  weight  of  a body  divided  by  gravity  g is  called  tbe  mass  ; and 
the  mass  multiplied  into  the  velocity  in  feet  per  second  is  denominated  the  quantity  of  movement,  or 
pressure  of  the  body. 

Adopting  this  notation,  and  denoting  the  weight  of  fluid  which  flows  in  a second  by  w,  and  its  velocity 
by  V ; then  the  mass  will  be  represented  by  — and  tbe  quantity  of  movement  or  pressure  by  — V.  But 
the  floats  of  the  wheel  are  assumed  to  recede  from  the  impulse  with  a velocity  of  v feet  per  second  ; 


the  pressure  exercised  upon  them  will  therefore  be  reduced  to  - (V  — v) ; but  the  space  passed  through 
by  the  wheel,  impelled  by  this  pressure,  is  v feet  per  second  ; consequently  the  dynamical  force  (the 
product  of  the  pressure  and  velocity)  will  be  — (V  — v)  v per  second;  or  taking  W = 60  w,  it  will  be 

W 3 

— (V  — v)  v per  minute.  But  as  before  observed, 

9 

W,„  , ,Tr  \ V2  v (V— u)2) 


( V — v)v  = VV  < 

9 1*9  2 g 


’■9  2 g S 

as  may  be  found  by  reduction  of  this  last  expression. 

From  the  principle  formerly  adverted  to  of  the  relation  of  the  velocity  possessed  by  a falling  body, 
to  the  height  through  which  it  must  have  fallen  to  acquire  that  velocity,  it  follows  that  the  weight 
being  w pounds,  and  the  velocity  Y feet  per  second,  there  must  be  accumulated  in  the  body  a number 

. . . V 2 

of  units  of  dynamical  force  represented  by  the  former  w — as  before  shown.  After  it  has  passed  from 

the  velocity  V to  the  less  velocity  U,  there  will  be  accumulated  in  it  the  number  of  units  of  force  rep- 
U2 

resented  by  w — — There  will  therefore  have  been  taken  from  its  dynamic  force  a number  of  units 
2 9‘ 

V 2 U 2 W 

represented  by  w w — = — (V2  — U)2.  Now  this  must  be  equally  true  of  a current  of  water 

"9  ^ 9 " g 

or  of  any  other  body  ; consequently,  if  the  velocity  with  which  it  meets  the  floats  of  the  wheel  be  V, 
and  it  escape  with  the  reduced  velocity  U,  the  force  lost  by  its  action  will  be  expressed  by 

W 

__  (V2-U2). 

But  this  force  has  been  lost  by  impulse  upon  the  floats,  and  ought,  theoretically,  to  have  been  en- 
tirely communicated  to  them.  On  this  assumption,  if  v denote  the  velocity  of  the  wheel  in  feet  per 

W 

second,  and  p the  pressure  overcome,  then  will  p v = — — (V 2 — U 2). 

But  on  the  assumption  that  the  water  meets  the  floats  of  the  wheel  without  shock,  it  will  leave  them 
with  a velocity,  as  before  shown,  of  (V  — v — U)  feet  per  second  ; consequently,  putting  for  U 2 its 
equivalent  (V  — v)'1  and  reduce  our  formula  by  performing  the  operations  indicated,  we  find 


pv=rg (v'2 


-(Y- 

2 D 


W 

■ vf)  = --  (V  — v)  v 


which  is  the  same  expression  which  resulted  from  the  preceding  modes  of  investigating  the  question 
In  the  case  of  purely  undershot  and  other  impulsive  wheels,  we  may  therefore  assume  the  effect, 

E = Wi|^(V— '’)  ^ 

in  which,  as  before,  m is  coefficient  determined  by  experiment,  and  W the  weight  of  water  in  pounds 
per  minute ; and  V and  v are  respectively  the  velocities  of  the  water,  and  of  the  periphery  of  the  wheel 
in  feet  per  second. 

This  formula  was  first  given  in  all  its  precision  and  generality  by  Borda,  in  his  memoir  on  water- 
wheels, presented  to  the  French  Academy  in  1767.  Having  called  z the  velocity  with  which  the  wal“- 


846 


WATER-WHEELS. 


abandons  the  machine,  and  — to2  the  sum  of  the  losses  of  vis-viva  sustained  by  the  fluid,  he  gives,  as  a gen- 
eral corollary  to  the  principles  demonstrated  in  his  memoir,  the  relation, 


Pv  = 'P(h—~ 

‘ V 2y2u/ 


which  is  exactly  the  same  as  that  above  established,  p being  the  pressure  overcome  by  the  wheel,  v its 
velocity  in  feet  per  second ; P the  total  pressure  due  to  the  weight  of  water,  and  h the  head  real  or 
Active  ; u — V ■ — v the  difference  of  velocity  of  the  current  and  of  the  periphery  of  the  wheel.  Deceived 
by  his  formula,  he,  however,  remarks  that  in  the  case  of  the  greatest  effect  u = 0 and  z = 0 ; whence 
p v = P h,  which  in  plain  language  signifies  that  the  wheel  being  at  rest,  the  whole  power  of  the  stream 
is  realized.  This  is  evidently  absurd  ; but  the  absurdity  is  in  the  interpretation,  not  in  the  formula. 
When  u and  z are  respectively  zero,  no  power  is  realized,  but  the  floats  of  the  wheel  entirely  obstruct 
the  passage  of  the  water,  and  sustain  the  whole  pressure  P h.  But  pressure  without  motion  is  not 
power.  The  error  has,  however,  been  reiterated  until  it  has  assumed  the  position  of  an  established  prin- 
ciple. Thus  every  writer  since  Carnot  has  laid  it  down,  as  the  basis  of  the  theory  of  hydraulic  ma- 
chines, “ that  in  order  that  the  machine  may  produce  the  greatest  possible  effect,  it  is  necessary  that  the 
water  shall  arrive  and  act  upon  it  without  shock,  and  quit  it  without  velocity.”  That  the  maximum 
effect  be  obtained,  it  is  admitted  that  there  must  be  no  percussive  action  ; the  fluid  must  lose  its  velocity 
by  insensible  degrees ; but  to  suppose  that  it  shall  quit  the  wheel  without  velocity,  is  to  suppose  that 
the  wheel  itself  has  motion  equal  to  that  of  the  stream,  and  consequently  produces  no  mechanical  effect. 
The  doctrine  is,  however,  true,  if,  instead  of  velocity,  we  read  “ relative  velocity.”  In  this  case  no  water 
will  escape  that  has  not  given  up  a certain  amount  of  its  movement  to  the  wheel,  and  it  will  clearly  pos- 
sess the  least  quantity  of  motion  consistent  with  its  action  upon  the  floats,  namely,  an  absolute  velocity 
equal  to  theirs.  On  this  condition  we  shall  have  v — Y — v and  therefore  v — $ V,  which  implies  that 
the  wheel  ought  to  take  half,  and  only  half,  the  velocity  of  the  current. 

We  shall  hereafter  And  that  this  conclusion  requires  modiAcation  ; but  in  the  mean  time  it  is  suffi- 
cient to  intimate  the  mode  of  calculation,  and  to  point  out  the  theoretical  conditions  which  form  the 
basis  of  inquiry. 

It  now  only  remains  in  this  place  to  indicate  the  general  principle  of  the  reaction  of  water.  Accord- 
ing to  Newton’s  third  law  of  motion,  action  and  reaction  are  equal  in  amount  and  opposite  in  direction. 
This  proposition  assumes  the  character  of  an  axiom,  when  the  mind  is  directed  to  the  reciprocal  action 
of  solids,  since  it  is  clear  that  any  body  acting  upon  another  by  pressure,  for  example,  must  itself  ex- 
perience a reaction  equal  and  directly  opposed  to  the  action  which  it  exercises.  In  the  same  manner, 
whenever  a force,  as  that  of  gravity,  pressing  upon  a fluid,  causes  it  to  issue  through  an  orifice  formed 
in  the  side  of  a containing  vessel,  a force  equal  and  contrary  to  that  with  which  the  stream  issues  will, 
in  consequence,  be  expended  upon  the  side  of  the  vessel  opposite  to  the  oriflee  of  escape.  To  explain 
this  very  briefly  : when  a part  of  the  weight  of  a fluid  is  expended  in  producing  motion  in  any  direc- 
tion, an  equal  pressure  is  necessarily  deducted  from  its  pressure  in  the  opposite  direction,  for  the  gravi- 
tation employed  in  generating  velocity  cannot  at  the  same  instant  be  causing  pressure.  Supposing  an 
oriflee  to  be  made  in  the  bottom  of  a vessel  Ailed  with  water,  a column  of  the  fluid  will  descend 
through  it,  and  will  expend  during  its  descent  a quantity  of  pressure  equal  to  a column  of  twice  the 
depth  of  the  fluid  in  the  vessel,  and  having  an  area  equal  to  the  least  section  of  the  stream.  For  exam- 
ple : suppose  the  vessel  to  be  16  feet  deep,  and  to  be  kept  constantly  full,  the  velocity  of  the  stream 
will  be  32  feet  in  a second  ; and,  therefore,  a column  of  32  feet  of  length  will  pass  through  the  oriflee 
in  each  second,  with  the  whole  velocity  derivable  from  its  weight  acting  for  the  time.  It  is  therefore 
clear  that  an  equal  amount  of  the  pressure  of  the  fluid  in  the  vessel  must  be  expended  in  producing 
that  velocity,  and  must  of  course  be  deducted  from  the  weight  of  the  whole  fluid — that  is,  from  the 
entire  pressure  which  it  would  otherwise  exercise  on  the  bottom  of  the  vessel.  Now,  what  is  true  with 
respect  to  vertical  descent,  is  equally  true  when  the  motion  is  in  any  other  direction.  When  the  orifice 
is  formed  in  the  side  of  the  vessel,  the  pressure  upon  that  side  will  be  diminished  by  as  much  as  the 
pressure  employed  in  producing  the  motion  ; and  the  effect  of  the  diminution  of  the  pressure  in  that 
direction  will  be  the  same  as  if  the  vessel  were  subjected  to  an  equal  pressure  of  any  other  kind  in  an 
opposite  direction.  And,  moreover,  the  pressure  being  lateral,  and  therefore  perpendicular  to  the  only 
direction  in  which  a vertical  force,  like  that  of  gravity,  can  itself  act.  it  must  be  derived  from  reaction  of 
the  opposite  surface  of  the  vessel  upon  the  moving  particles  of  the  fluid,  and  may  be  assimilated  to  the 
constant  pressure  of  a spring  interposed  between  the  moving  particles  and  the  part  of  the  vessel  im- 
mediately opposite  to  the  orifice.  In  this  position  the  spring  must  needs  act  in  a direction  exactly  con- 
trary to  that  of  the  movement  impressed  upon  the  fluid,  and  with  an  intensity  exactly  equal  to  the  hy- 
draulic pressure — that  is,  to  the  force  due  to  the  volume  of  water  issuing  by  the  orifice.  Now,  if  .$  be 
taken  to  denote  the  cross  sectional  area,  in  square  feet,  of  the  stream,  and  h the  depth  of  the  water  above 
the  centre  of  the  orifice,  then  the  quantity  of  water  discharged  in  a second  will  be  s V 2g  h cubic  feet, 
and  the  weight  62'5  s V 2g  h.  But  the  hydraulic  pressure  due  to  this  volume  of  water  will  be  62-5 
s X 2 h,  which  is  the  weight  in  pounds  which  would  be  necessary  and  sufficient  to  prevent  the  vessel 
from  receding  in  a direction  opposite  to  that  in  which  the  water  issues.  To  approach  the  actual  condi- 
tions : suppose  a vertical  cylinder  with  two  hollow  tubes  inserted  near  its  base,  and  projecting  laterally 
at  right  angles  to  its  axis ; that  these  tubes  are  closed  at  their  outward  extremities,  and  communicate 
freely  with  the  interior  of  the  cylinder  ; that  an  orifice  is  pierced  near  the  extremity  of  each  on  opposite 
sides  of  their  common  axis,  and  in  a plane  passing  through  that  axis  perpendicular  to  the  axis  of  the 
cylinder.  If  this  apparatus  be  placed  on  a vertical  axis,  round  which  it  is  free  to  revolve,  it  will  consti- 
tute that  variety  of  hydraulic  machine  known  as  Barker’s  Mill,  and  may  be  considered  a type  of  those 
machines  which  derive  their  power  from  the  reaction  of  fluids.  Water  being  let  in  to  fill  the  vertical 


WATER-WHEELS. 


847 


cylinder,  it  will  flow  into  the  horizontal  tubes,  and  issue  by  the  lateral  orifices  , but  in  thus  finding  vent 
into  the  atmosphere  through  the  (contrary)  sides  of  the  tubes,  these  will  be  made  to  recede  in  a direc- 
tion opposite  to  that  in  which  the  water  flows  out,  and  thereby  produce  a circular  motion  of  the  appa- 
ratus round  the  axis  by  which  it  is  confined. 

To  arrive  at  a general  notion  of  the  power  developed  by  the  revolution  of  the  machine,  let  us  denote 
the  depth  of  the  cylinder  above  the  level  of  the  orifices  by  H,  and  the  sum  of  the  cross-sectional  areas 
of  the  jets  by  S ; if  the  cylinder  be  kept  constantly  full  of  water  to  the  depth  H,  then  the  weight  which 
must  be  applied  in  an  opposite  direction  to  that  in  which  the  machine  tends  to  revolve,  and  at  the  same 
distance  from  the  axis  of  revolution  as  the  centres  of  the  orifices,  to  prevent  the  machine  from  getting 
into  motion,  will  be  624  S X 2H  lbs.,  this  being  the  hydraulic  pressure  due  to  the  quantity  of  water 
S s/iyti.  cubic  feet  discharged  each  second.  Otherwise  expressed,  the  weight  necessary  and  sufficient 
to  balance  the  hydraulic  pressure,  and  thereby  to  prevent  the  machine  from  revolving,  is  that  of  a col- 
umn of  water  equal  in  length  to  twice  the  head,  and  having  an  area  of  base  equal  to  the  sum  of  the 
cross-sectional  areas  of  the  two  jets.  This  is  found  to  agree  with  experiment,  and  it  may  be  determined 
from  a priori  reasoning.  In  every  body  falling  freely,  the  velocity  acquired  in  a given  unit  of  time  is 
such  as  would  carry  it  through  double  the  space  which  it  has  fallen  during  the  next  equal  unit  of  time, 
supposing  gravity  to  cease  to  act  upon  it.  There  must,  therefore,  have  issued  by  each  of  the  orifices  of 
the  machine,  a column  of  water  equal  to  double  the  height  of  the  surface  above  the  orifices,  that  is,  2 II, 
and  the  weight  of  such  column  is  manifestly  624  S X 2H. 

This  will  then  be  the  condition  of  the  machine  held  in  a state  of  rest  by  a weight  balancing  the  hy- 
draulic pressure  of  the  water  discharged  by  its  orifices.  But  when  it  is  allowed  to  get  into  motion 
another  important  condition  is  superadded.  Centrifugal  force  is  brought  into  action,  and  increases  the 
pressure  of  the  water  at  the  orifices,  and  thereby  augments  the  quantity  discharged  in  a given  time, 
and  also  the  intensity  of  the  reaction,  exactly  as  if  the  head-pressure  or  depth  of  the  cylinder  were  cor- 
respondingly increased. 

A common  expression  for  the  centrifugal  force  of  a body  revolving  in  a circle  at  a distance  x from  the 
w . . v 

centre  of  motion  is  — J2  x,  in  which  w is  the  angular  velocity  at  the  distance  x,  and  is  = - when  v ex 

presses  the  absolute  velocity  in  feet  per  second,  at  the  distance  x.  Now,  if  the  mass  — of  the  body  ad- 
vance in  the  direction  of  the  radius  outwards,  through  the  element  of  space  d x,  in  an  instant  of  time,  the 


. . , V) 

quantity  of  action  (vis  viva)  created  by  the  centrifugal  force  will  be  -uLIi.  But  this,  being  true  of 

n solid  body,  will  be  equally  true  of  the  molecules  of  water  in  the  arms  of  the  machine.  If,  therefore, 
these  arms  commence  at  a distance  r and  extend  to  a distance  R (the  centres  of  the  orifices)  from 
the  centre  of  rotation,  we  shall  have,  by  integrating  for  the  space  between  r and  R.  the  length  of 
each  arm. 

R 


/ 


u2.rd.r  = 4-u,2(R2  — r2). 
r 9 9 


And  since  u>  = — , if  we  take  the  quantity  of  water  vi  = 1,  we  have,  as  the  pressure  at  the  orifices  due 
to  the  velocity  of  rotation, 

w v1  / r2  \ 

4-u*(R*_f.*)=  (i__y 

9 2.0  \ R-/ 


If,  therefore,  we  add  this 
orifices  of  the  machine, 


to  the  initial  head-pressure  H,  we  shall  have  as  the  whole  pressure  at  the 


II 


Now,  under  this  pressure,  the  expenditure  of  water  will  be  increased  as 


v'2y  II  to  v/2y  II  -f  v*  ^1  — -^Y  that  is, 
as  1 to  ^l+4i(l-^)’ 

putting  V for  the  velocity  due  to  the  initial  head  H;  and  supposing  the  permanent  head  II  to  have 

been  increased  by  the  quantity  ~ ^ l _ L ^ by  directly  increasing  the  depth  of  the  cylinder,  it  is 

plain,  from  what  has  before  been  stated  respecting  the  force  of  reaction,  that  the  weight  which  would 
just  be  sufficient  to  keep  the  machine  from  getting  into  motion,  would  be 

«2-5SX2|h  + £(,_^)|u* 


This,  then,  is  the  whole  pressure  of  reaction  due  to  the  increased  head  II  + — ( 1 ■ but  the  le- 

'2  g \ R7  ’ 

p J p V 

action  due  to  the  Active  part  — p — is  obtained  in  consequence  of  the  rotatory  motion  of  the 


848 


WATER-WHEELS. 


machine,  with  a velocity  of  v feet  per  second ; a portion,  therefore,  of  the  whole  reaction  due  to  the 
quantity  of  water  expended,  must  have  been  consumed  in  communicating  that  velocity  to  the  volume 
of  water  discharged  in  that  second  of  time.  The  pressure,  thereby  withdrawn  from  that  due  to  the 
condition  of  rest  will  be  expressed  by  the  mass  X into  the  velocity,  that  is,  by 


62'5Sv/2i/H  + »!(l-j|i) 


9 XV’ 

and  this  pressure  being  subtracted  from  the  pressure  due  to  the  whole  force  of  reaction,  there  remains 
the  whole  effective  pressure,  that  is,  the  resistance  or  load  which  the  machine  can  overcome  at  the  given 
velocity,  v feet  per  second.  The  operation  being  performed,  we  obtain 

62JS 
9 

But  the  weight  of  water  discharged  in  a second  is 


624  5 


therefore, 


624  S = 


If,  then,  we  put  for  624  S in  the  foregoing  expression  this  equivalent,  and  reduce,  we  obtain  the  conve- 
nient formula, 


Now,  this  being  the  pressure  acting  upon  the  machine,  and  the  velocity  being  v feet  per  second,  the 
power  transmitted,  supposing  no  loss,  will  be 


and 


putting  V = v/2£rH  + ws  (l  — 

or 

(V  — v)  v, 


the  formula  takes  the  form 


9 

in  which  w = the  weight  of  water  discharged  in  a second ; V the  velocity  of  the  issuing  jets,  and  v the 
absolute  velocity  of  the  machine,  in  feet  per  second.  The  theoretical  rule  thus  agrees  with  that  estab- 
lished for  wheels  which  derive  their  efficiency  from  the  impulse  of  the  stream,  thereby  verifying  the 
doctrine  that  action  and  reaction  are  equal.  There  still  remains,  however,  to  determine  the  value  of 
the  experimental  coefficient  m,  with  which  this  expression  must  likewise  be  affected  to  render  it  avail- 
able in  practice ; but  this  being  different  for  differently  constructed  machines,  we  cannot  pursue  the 
inquiry  in  this  place. 

The  rule  may  be  otherwise  established  thus : The  whole  laboring  force,  or  mechanical  efficiency  of  the 
water,  expended  under  a head-pressure  of  H + ^ 1 — — J feet,  will  be 

But  of  this  efficiency  there  is  consumed  in  giving  rotatory  motion  to  the  water,  and  thereby  raising  the 
v1  / r~  \ v'  / r2  \ 

head-pressure  — ^1  — — 2^,  the  quantity  — v1  ^1  — wHch  consequently  falls  to  be  deducted 
from  the  entire  efficiency  of  the  fluid. 

Again,  the  water  leaves  the  machine  with  a certain  amount  of  velocity  remaining  in  it,  namelv, 
a velocity  equal  to  the  difference  between  that  with  which  it  issues  from  the  orifices  under  the  virtual 

/ r2  \ 

head  H -f-  — ^1 — — and  the  velocity  of  the  machine  measured  on  the  tangent  to  the  circle 
through  which  the  orifices  revolve ; this  difference  of  velocity  will  be  expressed  by 

v'2s'H  + u2(l  — ^5)—  v, 

and  the  quantity  of  laboring  force  due  to  it  will  be 


2 9 


jv/l2yH+*2(l--L)_rj. 


WATER- WHEELS. 


849 


This  likewise  falls  to  be  deducted  from  the  laboring  force  due  to  the  water  expended  under  the  head 
II  -f-  — — W')’  *eav*n»  efficiency  communicated  to  the  machine 


which  is  the  same  formula  as  we  obtained  by  the  preceding  investigation,  and  which,  it  may  be  well  to 
ooserve,  would  correctly  represent  the  action  of  the  machine,  were  it  not  that  it  is  liable  to  modification 
by  certain  incidental  influences,  which  remain  to  be  examined  when  we  come  to  treat  of  the  details  of 
construction,  and  other  circumstances  by  which  the  efficiency  of  the  machine  is  affected. 

We  now  pass  to  the  examination  of  the  different  varieties  of  wheels  before  indicated,  and  shall  take 
them  nearly  in  the  order  given,  but  under  a somewhat  more  convenient  division 

Bucket-wheels. — Under  this  head  we  include  those  nominal  varieties  of  vertical  wheels — overshot  and 
breast — which  are  provided  with  buckets  upon  their  peripheries  for  the  reception  of  the  water,  and 
which,  therefore,  derive  their  efficiency  chiefly  from  the  weight  of  the  fluid  received  into  the  buckets. 
This  form  of  wheel,  at  whatever  point  the  water  may  be  received  upon  its  circumference,  is  the  most 
obvious  in  its  action.  No  hydraulic  machine  could  be  more  simple : a given  weight  descends  from  a 
given  height ; a known  power  is  thus  expended,  to  which  the  work  performed  ought  to  bear  an  assign- 
able relation. 

The  older  bucket-wheels  which  we  encounter  are  constructed  of  wood ; but  that  material,  once  of 
almost  universal  use  in  constructive  mechanics,  is  fast  giving  place  to  iron,  and  in  a few  years  hence  we 
may  expect  that  a wooden  water-wheel  will  be  as  rare,  and  as  much  an  object  of  antiquarian  interest 
to  those  who  take  pleasure  in  reviewing  the  progress  of  the  industrial  arts,  as  wooden  geering  has 
already  become.  Many  of  those  wheels  still  continue  to  exhibit  in  their  constructive  details  a very  su- 
perior style  of  workmanship,  and  an  attention  to  durability  which,  in  several  instances  within  the  knowl- 
edge of  the  writer,  the  lapse  of  a century  has  hardly  conquered.  The  best  specimens,  no  doubt,  only 
remain  of  the  truly  old  construction,  while  those  of  an  inferior  grade  have  disappeared  and  been  replaced 
by  wheels  of  modern  construction,  in  which  iron,  if  not  the  sole  material,  holds  at  Jeast  a prominent 
place. 


3774. 


Another  peculiarity,  not  indeed  uncommon  in  wheels  of  recent  construction,  although  generally  aban 
doued  by  millwrights  who  make  pretensions  to  a superior  knowledge  of  the  principles  which  ought  to 
govern  the  transmission  of  hydraulic  power,  unless  the  conditions  be  dictated  by  extraneous  circumstan- 
ces, consists  in  passing  the  water  over  the  summit  of  the  wheel  into  the  buckets  in  the  manner 
'represented  in  Fig.  3174.  This  arrangement  constitutes  literally  an  overshot-wlieel;  but  while  we 
have  preserved  the  name,  it  is  no  longer  deemed  necessary  to  apply  it  literally.  In  the  present  accep- 
tation of  the  term,  nothing  more  is  implied  than  that  the  water  is  received  into  the  buckets  near  the 
summit  of  the  wheel ; and,  in  ordinary  practice,  those  wheels  reckoned  as  overshot,  by  strict  definition 
Vol.  II.— 54 


850 


WATER-WHEELS. 


some  under  the  designation  of  high-breast  -wheels.  One  of  the  finest  specimens  of  this  construction  yet 
erected  is  that  represented  in  Figs.  3778  and  3779,  in  which  the  height  of  the  fall  bears  to  the  diameter 
of  the  wheel  the  relation  of  9 to  10.  In  the  purely  overshot-wheel  this  relation,  as  we  shall  immedi- 
ately have,  occasion  to  show,  is  very  nearly  inverted. 


3778.  3779. 


In  the  construction  of  wheels  of  this  class,  the  technical  points  which  remain  to  be  considered,  after  de- 
termining the  diameter  and  breadth  of  the  wheel  from  the  height  of  fall  and  quantity  of  water  furnished 
by  the  stream,  are  the  axle  and  its  journals,  the  arms  and  their  connections,  the  shrouding,  sole,  and 
buckets. 

The  subject  of  the  axle  and  journals  has  already  been  very  fully  noticed  w7hen  treating  of  shafts  in 
the  article  on  Geering,  (which  see ;)  but  it  may  be  here  added  that  in  iron  wheels  of  great  weight  and 
breadth,  in  which  the  axle  is  consequently  of  corresponding  diameter  and  length,  and  especially  when 
the  wheel  is  to  be  transported  to  a considerable  distance  from  the  work  at  which  it  is  constructed,  it  is 
not  uncommon  to  make  the  axle  of  two,  or  even  of  three  parts.  When  the  axle  is  formed  in  this  man- 
ner, the  parts  are  fitted  together  by  turning,  and  are  secured  by  bolts  in  strong  flanges  cast  upon  the 
contiguous  extremities.  Fig.  3775  will  convey  an  idea  of  this  arrangement  in  its  best  and  most  endur- 
ing form — that  in  which  it  is  least  liable  to  objection.  But  no  force  of  ingenuity  can  render  it  safe ; 
the  constantly  changing  position  of  the  weight  ultimately,  and  sometimes,  indeed,  very  speedily,  acts 
injuriously  on  the  bolts,  thereby  relaxing  the  joint,  which  it  is  all  but  impossible  to  refit  with  any  pros- 
pect of  durability.  This  result  is  greatly  delayed  by  boring  the  bolt-holes  in  the  flanges,  and  turning 
the  bolts  exactly  to  fill  them.  In  fitting  the  parts  together  permanently  the  bolts  ought  to  be  inserted 
hot  and  have  the  nuts  fully  screwed  up  before  they  have  contracted  to  their  normal  length.  As  a fur- 
ther precaution,  the  bearing  surfaces  may  be  rusted  together  by  washing  them  immediately  before 
they  are  put  together  with  a dilute  solution  of  sal-ammoniac. 

In  wheels  composed  entirely  of  wood,  the  eight  principal  arms  are  commonly  disposed  in  parallel 
pairs,  crossing  each  upon  the  axle  to  which  they  have  no  positive  attachment.  The  arms  at  the  points 
•»f  crossing  are  bolted  together  in  sets  of  four,  and  the  two  frames  thus  formed  are  set  apart  upon  the 
axle  at  a distance  from  each  other,  determined  by  the  intended  breadth  of  the  wheel,  and  are  bound  to- 
gether by  tie-rods,  and  not  unfrequently  by  diagonal  struts  when  the  breadth  of  the  wheel  is  cousidera 
He,  yet  not  sufficient  to  require  the  introduction  of  an  intermediate  set  of  arms  and  partition  shrouding 


WATER-WHEELS. 


851 


The  framing  is  further  secured  in  its  place  upon  the  axle  by  wedging.  The  material  used  for  this  pur- 
pose is  commonly  oak,  which,  on  being  driven  as  firmly  as  the  nature  of  the  material  will  admit,  is  in- 
terspersed with  thin  iz’on  wedges  to  give  further  compactness  and  solidity  to  the  joint,  and  to  prevent 
the  packing  from  relaxing.  These  crosses  of  four  arms  each  thus  fixed  in  position  sustain  the  two  late- 
ral shroudings  between  which  the  buckets  of  the  wheels  are  inserted.  They  are  termed  the  master, 
main,  or  principal  arms  ; and  in  wheels  of  very  small  diameter — 14  feet  and  under — there  are  no  other 
employed.  But  when  the  diameter  of  the  wheel  exceeds  the  limit  at  which  the  arcs  of  the  shrouding 
would  be  safely  supported  at  that  minimum  number  of  points,  a series  of  auxiliary  arms  are  introduced, 
in  sets  of  four,  on  each  side  of  the  wheel.  These  secondary  arms  do  not  cross  each  other  at  the  axle 
as  the  principal  arms  do,  but  are  simply  made  to  abut  against  its  faces,  where  they  are  secured  by 
filling  blocks,  laid  in  in  different  ways,  according  to  the  number  of  auxiliaries  introduced.  They  are 
further  secured  by  bolts  to  the  master-arms,  which  they  are  always  made  to  cross  in  the  manner  rep- 
resented. 

When  the  wood  is  sound,  and  no  particular  circumstances  intervene  to  increase  the  strain  upon  the 
wheel,  the  strength  of  the  arms  may  be  computed  by  the  ordinary  rules  applicable  to  the  kind  of  wood 
employed  in  the  construction.  In  a very  elegant  specimen  of  48  feet  diameter  the  arms  at  the  base  are 
8 inches  square,  and  taper  to  6 inches  at  the  extremities. 

In  wooden  wheels  of  more  modern  construction,  instead  of  the  arms  being  framed  together  upon  the 
axle  in  the  manner  just  described,  their  bases  are  inserted,  and  generally  fixed  by  wedges  in  iron  cen- 
tres previously  fitted  upon  the  axle.  This  is  a much  more  elegant  and  substantial  arrangement,  and  is 
applicable  to  all  the  varieties  of  vertical  wheels,  and  to  all  diameters  ; but  it  does  not  always  happen 
that  the  mode  of  fitting  is  the  best  adapted  for  durability  or  convenience  of  repair.  Very  commonly 
the  centres  are  solid  castings,  with  recesses  in  the  periphery  corresponding  in  number  and  size  to  the 
arms  which  they  are  intended  to  receive  ; and  when  the  arms  are  formed  of  malleable-iron  bars,  this 
arrangement  is  all  that  could  be  desired.  But  for  wooden  arms,  the  recesses  ought  to  be  considerably 
more  in  breadth  than  the  butts  to  be  inserted  into  them ; and  these  ought  to  be  fixed,  not  with  iron,  but 
by  wooden  keys,  and  without  the  aid  of  bolts.  If  the  outside  cover  be  cast  separately  as  a loose  ring, 
and  bolted  upon  the  centre  after  the  butts  of  the  arms  are  fitted,  it  will  allow  of  the  recesses  to  be 
formed  widest  at  bottom,  and  the  butts  to  be  made  dovetail-shaped,  and  secured  by  parallel  keys  a a, 
in  the  manner  represented  by  the  arms  A A,  in  Fig.  3776.  These  recesses,  when  the  work  is  of  a 
superior  character,  would  be  planed  on  all , the  bearing  surfaces,  and  the  cover  might  be  fitted  by 
turning. 

This  mode  of  fitting  is  equally  suitable  for  cast-iron  arms,  except  that  the  keys  are  in  that  case  ren- 
dered unnecessary  by  the  butts  being  made  to  fill  the  recesses,  and  are  carefully  fitted-  by  planing. 
They  are  also  secured  by  bolts,  and  it  is  not  often  that  any  cover  is  employed. 

When  the  wheel  is  of  small  diameter  the  centres  and  arms  are  sometimes,  and  advantageously,  formed 
of  one  casting.  In  this  case  no  fitting  is  required  ; and  although  the  moulder’s  labor  is  greater,  there 
is  an  ultimate  economy,  when  the  diameter  does  not  much  exceed  12  feet,  which  more  than  balances 
the  excess  of  foundry  cost.  In  one  small  example  we  have  observed  the  principle  extended  to  the  shroud 
ing ; each  side  of  the  wheel  consisted  of  a single  casting,  and  the  two  were  simply  bound  together  by 
a few  tie-rods,  and  the  sheet-iron  plates,  of  which  the  buckets  were  composed. 

The  shrouding  is  formed  of  two  annular  plates,  which,  in  wooden  wheels,  are  composed  of  plank,  of 
3-J  inches  to  7 inches  thick,  shaped  and  jointed  together  similarly  to  the  felloes  of  a carriage-wheel. 
Instead,  however,  of  the  joints  being  formed  by  simply  abutting  the  extremity  of  one  piece  upon  that 
adjacent,  the  extremities  are  checked  to  half  their  thickness  upon  opposite  sides,  and  overlapped. 
Sometimes  also  the  joints  are  made  by  scarfing,  when  not  opposite  to  the  arms,  and  strengthened  by 
plates  of  iron  laid  into  recesses  flush  with  the  general  surface.  The  other  joints  which  receive  the  ex- 
tremities of  the  arms  are  half-checked  on  the  exterior  surface,  and  are  connected  by  the  palms,  which 
are  usually  counter-checked  on  the  inner  face,  to  fall  flush  into  the  recesses  prepared  for  them  in  the 
ends  of  the  pieces  which  they  are  intended  to  connect.  With  the  old  millwrights  it  was  not  uncommon 

to  form  the  joints  of  the  better  class  of  wheels  by  mortise-and-tennon,  and  sometimes  by  joggles a 

method  which  seems  to  us  equally  efficient  and  less  expensive. 

In  the  older  wooden  wheels  the  shrouding  is  usually  of  a greater  depth  than  is  consistent  with  mod- 
ern practice.  At  present  we  meet  with  few  examples  in  which  the  shrouding  is  more  than  12  to  15 
inches  deep,  whereas  a depth  of  20  inches  was  formerly  not  uncommon.  This  is  a subject,  however, 
which  will  require  to  be  considered  subsequently,  as  also  the  width  of  the  wheel  or  distance  between 
the  shrouds. 

The  width  of  the  wheel  determines  the  length  of  the  buckets.  These  extend  between  the  shrouds, 
except  in  very  broad  wheels,  in  which  an  intermediate  or  partition  shrouding  is  sometimes  introduced 
to  give  support  to  the  buckets  at  the  middle  of  their  length.  This  is  usually  resorted  to  in  wooden 
wheels  when  the  breadth  exceeds  8 feet,  but  it  is  not  uncommon  to  find  iron  wheels  of  double  that 
breadth  without  any  partition  shrouding.  In  this  class  of  wheels  it  is,  indeed,  an  excepted  case  in  which 
we  find  this  arrangement  adopted  in  the  entirety  exhibited  by  the  older  specimens.  In  these  the  par- 
tition shrouding  was,  in  all  respects,  a duplicate  of  the  lateral  shrouds,  and  was  like  them  attached  upon 
arms  radiating  from  an  independent  centre,  placed  intermediate  to  the  two  others  upon  the  axle  of  the 
wheel.  Besides  giving  additional  rigidity  to  the  struction,  it  served  to  carry  the  medial  extremities  of 
the  buckets,  which  being  formed  of  plank,  did  not  admit  of  that  ready  mode  of  staying,  so  convenient 
with  sheet-iron  buckets,  as  exemplified  in  Fig.  3778  and  elsewhere. 

The  shrouds  being  properly  adjusted  and  fixed  in  relation  to  the  axis  of  motion,  a circular  runner  ot 
plank  having  a transverse  section  of  3 X 3 inches,  is  attached  by  wood-screws  to  the  interior  face  of 
each  of  the  shroud-plates,  and  upon  this  the  ends  of  the  sole-planks  are  supported.  We  speak  of  the 
best  form  of  construction  ; but  more  frequently  the  sole-planks  are  simply  fitted  and  fixed  upon  the  in- 
terior circumference  of  the  shrouding  ; and  this  arrangement  has  its  advantage  in  the  facility  which  it 


852 


WATER-WHEELS. 


allows  for  the  repair  of  the  sole,  a9  the  planks  may  be  taken  off  without  disturbing  the  buckets  in  then 
vicinity.  When  the  sole  is  completed  the  wheel  has  the  appearance  of  a large  drum  with  radial  flanges, 
between  which  the  buckets  are  to  be  fixed.  The  extremities  of  the  planks  of  which  the  buckets  are 
formed  are  commonly  received  into  mortises  cut  in  the  contiguous  faces  of  the  shroud-plates  ; or  into 
grooves  formed  by  narrow  runners  of  wood  nailed  upon  the  plates.  A still  better  mode  of  fitting  is  to 
sprig  the  buckets  in  their  places,  or  to  mark  off  their  form  and  positions  upon  the  inner  surfaces  of  the 
shrouding,  and  fill  in  the  spaces  between  them  by  plates  of  board  cut  to  the  proper  form.  When  the 
first  method  is  adopted  it  is  necessary  to  insert  the  radial  part  DF  of  Fig.  3780,  before  fixing  the  sole- 
planks  ; but  by  forming  grooves  according  to  the  latter  methods,  the  sole  may  be  completed  previous 
to  any  part  of  the  bucketing  being  prepared.  When  the  method  of  mortising  is  adopted  it  is,  on  the 
contrary,  more  convenient  to  make  the  bucketing  precede  the  application  of  the  sole-planking.  It  is  of 
little  moment  which  of  these  methods  be  adopted  in  practice,  and  the  circumstances  of  the  particular 
case  will  invariably  determine  that  which  may  be  resorted  to  with  most  advantage ; but  it  is  of  the  ut- 
most importance  that  in  the  process  of  deeding  the  wheel  be  not  thrown  out  of  truth.  To  avoid  this, 
the  operations  ought  to  proceed  from  at  least  two  points ; and  if  the  wdieel  be  of  large  diameter  it  will 
give  a better  chance  of  correctness  to  distribute  the  operations  over  the  four  quadrants  of  the  wheel, 
taking  alternately  that  immediately  opposite  and  contiguous  as  the  next  in  succession  to  be  operated 
upon. 


Each  bucket  consists  usually  of  two  plates  placed  at  a determinate  angle  A D F,  Fig.  3780  ; and  some- 
times of  three,  as  in  the  form  indicated  at  P M.  The  bucket  is  an  essential  part  of  the  wheel,  which  ought 
to  be  determined  not  by  the  rule-of-thumb  practice  admissible  in  some  of  the  less  important  details,  but  from 
a competent  regard  to  the  conditions  involved.  Upon  their  form  depends,  in  a great  measure,  the  effi- 
ciency of  the  wheel  as  a hydraulic  motor ; and  although  with  wood  the  true  conditions  which  lead  to 
the  best  effect  can  only  be  very  distantly  approximated,  it  may  still  be  of  advantage  to  indicate  these 
as  nearly  as  the  circumstances  will  admit. 

Having  determined  the  diameter  of  the  wheel  and  the  depth  of  the  shrouding — the  rules  for  which 
will  be  hereafter  adverted  to  at  length — let  portions  of  their  circles  A S and  B Q be  described  from  a 
common  centre,  as  O in  Fig.  3780.  Let  the  depth  A B of  the  buckets  be  divided  into  three  equal  parts 
and  with  a radius  to  C,  making  BC  = | AC  describe  the  arc  C D E of  the  third  circumference  upon 
which  the  centre  of  gravity  of  the  water  contained  in  the  buckets  will  always  be  found,  at  least  very  nearly. 
This  radius,  marked  0 r in  Fig.  3774,  is  termed  the  dynamic  radius  of  the  wheel,  and  it  is  of  importance 
that  it  be  correctly  defined.  The  distance  of  one  bucket  from  that  succeeding  it  is  measured  upon  this 
last  circumference,  and  may  be  taken  generally  at  12  to  134  inches.  The  common  practice  is  to  divide 
the  circumference  into  four  equal  parts,  and  in  each  quarter  is  inserted  the  same  number  of  buckets,  the 
distance  being  made  to  vary  slightly  with  the  size  of  the  wheel.  But  it  also  follows  from  this  practice 
that  the  number  of  buckets  will  not  be  exactly  proportional  to  the  diameter.  An  approximate  rule  is 
to  double  the  number  expressing  the  diameter  of  the  wheel  in  feet,  and  call  that  or  the  next  higher 
number  divisible  by  4,  the  number  of  buckets. 

Thus  the  diameter  being  12  feet,  the  number  of  buckets  24. 

“ “ 17  “ “ “ 36. 

“ “ 21  “ “ “ 44. 

» « 05  « “ “ 50, 

In  greater  diameters,  the  proportion  increases  thus : 

Diameter,  28  feet Buckets,  60 

“ 32  “ “ 72 

“ 38  “ “ 84 

We  do  not  instance  these  as  examples  to  be  copied,  but  simply  in  illustration  of  a practice  not  yet  quite 
obliterated,  of  referring  the  mo3t  vital  conditions  of  the  question  to  a haphazard  empiricism,  which  pre- 
tends to  no  better  foundation  than  its  affording  an  easy  approximation.  The  proper  elements  from  which 
the  capacity  of  the  buckets  ought  to  be  determined  are  the  quantity  of  water  to  be  used  and  the  angu- 
lar velocity  of  the  wheel,  subjects  which  will  be  subsequently  considered  in  relation  to  this  and  other 
questions  of  equal  importance. 

The  circumference  described  by  the  dynamical  radius  of  the  wheel  being  divided  into  equal  parts, 
C,  D,  E,  &c.,  in  number  equal  to  the  number  of  buckets  which  the  wheel  is  intended  to  have,  the  radial 
lines  C B,  D F,  E G,  <fec.,  will  determine  the  direction  and  breadth  of  the  starts  of  the  buckets.  Th e. flats 
A D,  H E,  Ac.,  are  determined  by  regard  to  the  condition  that  the  angle  H E G,  comprised  between  the 
Btart  and  flat  of  the  same  bucket,  ought  to  open  as  little  as  possible,  in  order  that  the  bucket  may  re- 
tain its  water  as  long  as  possible  ; but  at  the  same  time  the  angle  must  be  sufficiently  great  that  the 
water  shall  have  free  admission  through  the  space  D 6,  otherwise  a portion  of  it  would  be  thrown  back 
chiefly  by  the  action  of  the  air  confined  in  the  bucket — an  evil  now  almost  entirely  remedied  by  the  sys- 
tem of  ventilation  introduced  in  the  construction,  but  which  in  wooden  wheels  could  only  be  effected  very 


Diameter,  40  feet Buckets,  22 

“ 42  “ “ 96 

“ 46  “ “ 108 


WATER-WHEELS. 


853 


imperfectly.  In  all  cases  it  is  essentially  and  obviously  requisite  that  the  space  between  the  flats  be 
considerably  greater  than  the  thickness  of  the  sheet  of  water  which  is  thrown  upon  the  wheel.  It  is 
true,  that  by  increasing  the  breadth  of  the  stream,  its  thickness  may  be  diminished  at  pleasure.  Still 
it  is  necessary  to  give  to  D b a minimum  of  5 to  6 inches,  to  insure  free  ingress  to  the  water  in  all  posi- 
tions of  the  bucket,  while  receiving  its  charge.  This  condition  is  attained  by  giving  to  the  angle  IT  E G 
a value  of  110°  to  118°,  supposing  the  wheel  to  have  a diameter  not  less  than  15  feet.  Under  this  ar- 
rangement, the  flat  will  have  an  inclination  to  the  interior  circumference — rather  to  a tangent  drawn  to 
that  circumference  from  the  point  of  intersection  with  the  exterior  circumference — of  about  31°,  and  not 
more  than  33°.  This  angle  is  indicated  by  the  tangent  in  Fig.  3774. 

Some  millwrights  have  endeavored  to  lessen  the  evil  experienced  in  the  water  being  thrown  out  of 
the  buckets  by  increasing  the  breadth  of  the  starts,  as  in  the  bucket  LKI,  in  which  I K = \ I P.  And 
as  an  approach  to  the  more  modern  curved  bucket,  the  form  P M has  been  employed,  in  which  the  flat 
is  composed  of  two  parts,  P 0,0  N,  joined  together  at  an  angle  of  about  150°.  This  form  has  an  ad- 
vantage in  so  far  as  it  retains  the  water  longer;  but  besides  increasing  the  labor  and  difficulty  of  fitting 
and  repairing  the  buckets,  it  has  the  further  effect  of  contracting  the  space  through  which  the  water  is 
received  into  the  bucket,  which,  under  the  very  imperfect  system  of  ventilation  practicable  in  wood 
wheels,  is  an  evil  more  than  equivalent  to  the  advantage  secured  Even  the  mode  of  fitting  the  two 
plates  of  the  bucket  together  by  a bevel-joint,  as  at  D,  is  considered  by  some  millwrights  as  an  unneces- 
sary technical  difficulty,  which  they  avoid  by  fitting  the  start-board  at  an  angle  of  90°  with  the  flat- 
board.  This  practice  has  an  advantage  in  point  of  simplicity  of  construction,  and  it  does  not  seem  liable 
to  any  serious  theoretical  objection.  But  the  difficulty  complained  of  is  more  effectually  removed  by 
the  introduction  of  sheet-iron  buckets,  which  is  not  now  uncommon,  even  in  wheels  principally  con- 
structed of  wood.  The  usual  practice  is  to  curve  the  plate  into  the  form  S Q,  in  which  the  start  to  tire 
point  R on  the  dynamical  circumference  approaches  the  circumference  of  the  wheel  at  an  angle  of  90°, 
and  the  extremity  S meets  that  circumference  at  an  angle  of  not  more  than  3°.  In  this  mode  of 
bucketing,  which,  when  introduced,  was  reckoned  an  improvement  of  much  value,  and  which  in  modern 
practice  is  the  simplest  that  can  be  adopted,  the  buckets  carry  their  water  to  the  lowest  point  of  the 
revolution  of  the  wheel ; but  like  that  previously  noticed,  although  it  has  an  advantage  in  this  respect, 
it  has  been  considered  liable  to  the  objection  of  affording  a less  ready  admission  to  the  water  in  filling. 
In  early  practice,  and,  indeed,  until  very  recently,  the  necessity  of  facilitating  the  escape  of  the  air  from 
the  buckets,  when  receiving  their  charge  of  water  at  the  summit,  was  not  understood.  The  importance 
of  making  the  buckets  of  a form  to  carry  the  water  to  the  lowest  point  of  the  revolution  of  the  wheel 
was  obvious ; but  when  this  was  accomplished,  it  was  usually  found  that  the  wheel  neither  received  nor 
parted  with  the  water  freely.  The  late  Professor  Robinson  seems  to  have  been  the  first  to  give  a full 
explanation  of  these  circumstances,  and  to  have  pointed  out  at  least  a partial  remedy.  In  reference  to 
the  first,  he  observes  that  “ the  half-taught  millwright  attempts  to  retain  the  water  a longer  time  in  the 
buckets,  but  finds  that  it  gets  into  them  with  a difficulty  for  which  he  cannot  account,  and  spills  it  about 
even  after  they  have  ceased  to  receive  any  from  the  spout.  This  arises  from  the  air,  which  must  find 
its  way  out  to  admit  the  water,  but  is  obstructed  by  the  entering  water,  and  occasions  a great  splutter- 
ing at  the  entry.  This  obstruction  is  vastly  greater  than  one  would  imagine,  for  the  water  drags  along 
with  it  a great  quantity  of  air,  as  is  evident  in  the  water-blast  described  by  many  authors.” 

After  observing  that  “ this  evil  may  be  entirely  prevented  by  making  the  spout  considerably  nar- 
rower than  the  wheel,  and  thereby  leaving  room  at  the  two  ends  of  the  buckets  for  the  escape  of  the 
air,”  he  proceeds  to  consider  the  circumstances  attending  the  emptying  of  the  buckets.  He  observes, 
“ There  is  another  very  serious  obstruction  to  the  motion  of  an  overshot  or  bucketed  wheel,  especially 
when  it  revolves  in  backwater.  It  is  not  much  resisted  by  the  water  on  account  of  the  slowness  of  its 
motion  ; but  it  lifts  a great  deal  of  the  water  in  the  rising  buckets.  In  some  particular  states  of  back- 
water the  descending  bucket  fills  itself  completely  with  water  ; and  in  other  cases  it  contains  a very 
considerable  quantity  of  air  of  common  density,  while  in  some  rare  cases  it  contains  both  water  and  air 
in  a compressed  state.  In  the  first  case,  the  rising  bucket  must  come  up  filled  with  water,  which  it 
cannot  drop  till  its  mouth  gets  out  of  the  (tail)  water.  In  the  second  case,  part  of  the  water  goes  out 
before  this  ; but  the  air  rarefies,  and  therefore  there  is  still  some  water  dragged  or  lifted  up  by  the 
wheel,  but  (which  is  as  detrimental  to  its  performance)  the  descending  side  is  employed  in  condensing 
the  air ; and  although  this  air  aids  the  ascent  of  the  rising  side,  it  does  not  aid  it  so  much  as  it  impedes 
the  descending  side,  being  (by  the  form  of  the  bucket)  nearer  to  the  vertical  line  drawn  through  the 
axis.” 

Without  acquiescing  in  the  correctness  of  the  objection  and  explanation  contained  in  tins  second  case, 
it  is  not  difficult  to  perceive  that  if  the  bucket  be  quite  air-tight,  and  of  such  a form  a's  to  carry  its  charge 
of  water  to  the  bottom  of  the  circle  of  revolution,  in  the  process  of  emptying  itself  against  the  atmos- 
pheric pressure,  and  in  a direction  contrary  to  the  direction  of  motion  of  the  wheel,  there  will  be  a par- 
tial vacuum  formed  in  the  bucket,  and  to  that  extent  the  effect  of  the  wheel  will  be  diminished.  If 
the  bottom  segment  of  the  wheel  be  immersed  in  tail  water,  which  is  a very  frequent  circumstance,  the 
evil  will  be  greatly  increased,  for  then  the  bucket  cannot  relieve  itself  until  its  mouth  has  ascended 
above  the  water-level ; and  in  consequence  of  the  resistance  offered  to  the  descent  of  the  water,  the 
bucket  will  have  ascended  considerably  higher  before  i!  is  entirely  relieved  of  its  load. 

The  earliest  remedy  applied  to  the  removal  of  these  difficulties,  and  which  has  been  continued  to 
some  extent  to  the  present  time,  was  to  bore  holes  in  the  starts  of  the  buckets.  As  respects  the  admis- 
sion of  the  water,  this  contrivance  is  of  little  value,  as  the  escape  of  the  contained  air  by  the  holes  is 
prevented  by  the  presence  of  the  water  in  the  inferior  bucket.  But  its  success  in  promoting  the  easy 
discharge  of  the  water  from  the  buckets  soon  became  obvious,  from  the  increased  efficiency  of  the  wheels 
in  which  it  was  adopted.  And  besides  its  effect  in  facilitating  the  relief  of  the  buckets  by  the  admis- 
sion of  the  air  to  replace  the  water  discharged,  it  has  the  further  advantage  of  preventing  the  trouble- 
some and  often  dangerous  effect  of  bucketing  when  the  works  are  stopped,  as  the  small  quantity  of 


854 


WATER-WHEELS. 


water  escaping  by  the  sluice  and  falling  upon  the  wheel  runs  through  the  air-holes  without  accumula- 
ting in  the  buckets  of  the  wheel,  and  starting  it  into  motion  at  intervals. 

Mr.  Fairbairn,  of  Manchester,  to  whom  we  owe  the  present  improved  system  of  ventilation,  relates 
in  a paper  submitted  to  the  Institution  of  Civil  Engineers,  that  about  twenty  years  ago  he  constructed 
a wheel  for  Mr.  James  Brown,  of  Linwood,  near  Paisley,  “ which  in  floodwaters,  when  the  wheel  was 
loaded,  every  bucket  acted  as  a water-blast,  and  threw  the  water  and  spray  to  a height  of  six  to  eight 
feet  above  the  orifice  at  which  it  entered.  This  was  complained  of  as  a great  evil;  and  in  order  to  get 
rid  of  the  difficulty,  incisions  were  made  through  the  sole-plates,  and  small  interior  buckets  were 
attached  to  the  inner  sole-plates,  as  represented  in  Fig.  3781.  ii'he  air  made  its  escape  by  the  openings 


3731. 


a a a into  the  interior  buckets  bbb  inside  of  tlie  wheel  during  the  time  of  filling ; and,  when  working 
in  backwater,  it  presented  the  same  facilities  for  its  emission  before  even  a partial  vacuum  could  be 
formed  in  the  ascending  bucket  when  rising  through  the  tailwater.  The  changes  which  this  remarkable 
alteration  effected  can  scarcely  be  credited  ; the  wheel  not  only  took  and  parted  with  the  water  with 
perfect  freedom,  but  an  increase  of  power  of  nearly  a fourth  was  obtained.  The  wheel  is  still  in  the 
same  state,  and  continues  in  all  states  of  the  water  to  perform  an  apparent  and  satisfactory  amount  of 
duty.” 

This  was  an  important  advance  on  the  scheme  of  piercing  the  starts  of  the  buckets ; and  although  in 
this  case  applied  to  an  iron  wheel,  it  admits  of  easy  application  to  wooden  wheels,  by  making  a species 
of  internal  sole,  and  dividing  it  off  into  portions  answering  to  the  small  buckets  bbb,  and  of  course 
equal  in  number  to  the  number  of  main  buckets  in  the  wheel. 

The  improvement  effected  upon  Mr.  Brown’s  wheel  subsequently  induced 
Mr.  Fairbairn  to  extend  the  principle  of  ventilation ; and  instead  of  waiting 
to  ascertain  the  action  of  the  wheel  when  started,  to  apply  it  as  a funda- 
mental requisite  to  be  provided  for  in  the  construction.  The  primary  form 
ui  the  contriS’ance,  although  very  effective,  is  manifestly  liable  to  objection 
m respect  of  the  additional  workmanship  which  it  required ; and  besides, 
if  thoroughly  carried  into  effect,  would  tend  to  weaken  the  sole-plate  of 
the  wheel.  To  obviate  these  objections,  Mr.  Fairbairn  introduced  the 
elegant  arrangement  depicted  in  Fig.  3782,  by  which  the  integrity  of 
the  sole  is  preserved,  and  in  which,  with  very  little  additional  cost  of  con- 
struction, the  object  is  most  effectually  accomplished.  The  method  consists 
in  forming  the  buckets — each  consisting  of  a single  plate — with  independent 
soles,  which  are  applied  parallel  with  the  sole  of  the  wheel,  leaving  between 
the  two  contiguous  surfaces  a vacant  space  of  about  an  inch,  for  the  escape 
of  the  air  into  the  superior  bucket  during  the  process  of  filling,  and  which 
will  obviously  serve  to  readmit  the  air  to  replace  the  water  when  the 
bucket  begins  to  empty  itself  towards  the  lowest  point  of  its  revolution 
and  begins  to  ascend.  When  it  has  attained  this  position,  it  ought  mani- 
festly to  be  entirely  relieved  of  its  burden ; but  it  has  been  already  inti- 
mated that,  in  certain  conditions  of  backwater,  this  can  be  accomplished 
only  by  some  contrivance  for  admitting  the  pressure  of  the  atmosphere 
upon  the  water  in  the  bucket  immediately  on  its  beginning  to  ascend.  If 
the  atmosphere  be  then  excluded,  and  the  bucket  he  full  of  water,  a cer- 
tain amount  of  weight  will  be  made  to  act  adversely  to  the  motion  of  the 
wheel,  and  to  that  extent  will  diminish  its  efficiency.  This  takes  place 
more  commonly  with  iron  than  with  wooden  buckets  destitute  of  provision 
for  their  ventilation,  on  account  of  the  more  contracted  form  of  the  inlet 
passages  produced  by  the  curvature  of  the  flats  of  the  former. 

On  this  subject  Mr.  Fairbairn  remarks,  that  “ water-wheels  constructed  entirely  of  iron,  and  having 
thin  plates  instead  of  wood  for  the  buckets,  give  decreased  facilities  for  the  admission  of  the  water,  and 
for  the  escape  of  the  air  contained  in  them.  So  great  difficulty  is  experienced  in  effecting  the  discharge 
of  the  air  in  a close  bucket  through  the  same  orifice,  and  at  the  same  time  that  the  water  is  being  ad- 
mitted, as  in  some  wheels  almost  entirely  to  prevent  the  entrance  of  the  water ; and  in  cases  where  the 
buckets  are  closely  formed,  the  wheel  is  deprived  of  almost  half  its  power  by  the  reaction  of  the  in- 
closed air.  This  defect  is  most  obvious  in  water-wheels  having  contracted  openings — which  may  be 
easily  accounted  for  in  every  case  where  the  water  is  discharged  upon  the  wheel  in  a larger  section 
than  the  opening  between  the  buckets.  Under  these  circumstances  the  air  is  suddenly  condensed,  and 
again  reacting  by  its  elastic  force,  throws  back  the  water  upon  the  orifice  of  the  cistern,  and  thus  allows 
the  buckets  to  pass  without  being  more  than  half  tilled.” 

These  remarks  are  intended  to  show  the  extent  of  the  difficulties  which  have  been  removed  by  the 
introduction  of  the  ventilated  bucket,  and  to  induce  the  adoption  of  that  system,  which,  we  may  remark. 


3782. 


WATER-WHEELS. 


85b 


.a  always  applicable,  and  presents  none  of  those  constructive  objections  which  are  so  often  fatal  to  the 
introduction  of  technical  improvements  in  hydraulic  machinery.  This  has,  indeed,  been  acknowledged 
by  the  almost  universal  adoption  of  the  principle  by  those  engineers  capable  of  appreciating  its  advan- 
tages ; but  examples  in  which  it  has  been  disregarded — possibly  through  ignorance  of  its  use — 
have  fallen  under  our  notice  very  recently,  and  in  more  than  one  instance  very  fully  illustrated  the 
danger  of  dealing  with  hydraulic  power  on  mere  empirical  rules. 

When  the  wheel  is  wholly  constructed  of  iron,  the  buckets  are  usually  supported  at  their  extremities 
on  narrow  flanges,  cast  of  the  intended  form  upon  the  inside  faces  of  the  shrouding,  and  secured  by 
small  bolts,  (usually  half  inch  in  diameter,)  for  which  the  holes  are  cast  in  the  flanges,  and  bored  in  the 
bucket-plates.  They  are  further  supported  upon  each  other  by  intermediate  stays,  cast  witli  palms  ni 
opposite  curvature  at  their  extremities,  to  meet  the  interior  and  exterior  surfaces  of  the  buckets  which 
they  are  intended  to  connect.  The  details  are  fully  illustrated  in  Figs.  3783  to  3795. 


3783. 


3790.  3?91 . 


It  is,  however,  to  be  remarked  that,  except  in  the  undershot-wheel  of  M.  Poncelet,  no  attempt  has 
hitherto  been  made  to  give  the  buckets  a definite  form  with  reference  to  the  action  of  the  water  upon 
them  on  its  admission ; and  possibly  under  the  system  now  generally  adopted,  of  introducing  it  below 
the  summit,  and  under  as  small  a head-pressure  as  can  be  obtained,  consistently  with  the  volume  to  be 
used,  it  is  of  little  importance  to  bring  that  element  into  the  calculation.  It  may,  however,  be  remarked 
that,  in  strictness,  when  the  water  is  allowed  to  fall  simply  over  the  lip  of  the  bucket,  the  curve  ought 


3795. 


to  be  that  of  quickest  descent ; and  in  no  case  ought  it  to  descend  from  so  great  a height  that  its  reac- 
tion upon  the  under  side  of  the  succeeding  bucket  shall  be  sensibly  felt.  This  appears  to  be  well  illus- 
trated by  the  well-known  experiments  of  Mr.  Smeaton,  to  which  we  shall  hereafter  have  occasion  more 
particularly  to  advert.  His  overshot  model  was  24  inches  in  diameter : and  when  the  whole  descent,  of 


356 


WATER-WHEELS. 


the  water  was  27  inches,  the  maximum  effect  of  the  wheel  was  76  per  cent,  of  the  power  of  the  water 
but  when  increased  to  35  inches,  the  ratio  fell  to  52.  In  other  words,  the  head  being  increased  in  the 
ratio  of  7 to  9,  the  increase  of  effect  is  only  in  the  ratio  of  81  to  84,  and,  consequently,  the  increase  o: 
effect  is  not  1-7 th  of  the  increase  of  perpendicular  height.  From  this  he  concludes,  and  correctly,  as 
respects  purely  overshot-wheels,  “ that  the  higher  the  wheel  is  in  proportion  to  the  whole  descent,  the 
greater  will  be  the  whole  effect.”  But  the  explanation  which  he  offers  is  founded  entirely  on  the  opinion 
“ that  the  effect  of  the  same  quantity  of  water,  descending  through  the  same  perpendicular  height,  is 
double  when  acting  by  its  gravity  upon  an  overshot-wheel,  to  what  the  same  produces  when  acting  ly 
its  impulse.”  It  is  unnecessary,  in  the  mean  time,  to  examine  this  proposition,  as  it  is  sufficient  for  our 
present  purpose  to  intimate  that  a high  velocity  of  the  current  entering  the  buckets  is  attended  with  a 
lass  of  effect,  and  that  at  least  a portion  of  that  loss  seems  to  us  to  result  from  the  reaction  of  the 
water  against  the  sole  of  the  bucket  into  which  it  is  received,  and  against  the  bottom  of  the  next  suc- 
ceeding bucket;  and  it  is  obvious  that  any  impulsive  force  expended  on  these  surfaces  must  propor- 
tionally resist  the  motion  of  the  wheel  in  the  contrary  direction. 

As  respects  the  mode  of  supplying  the  water  to  the  overshot-wheel,  the  arrangement  is  sometimes 
made  to  differ  slightly,  according  as  the  level  of  the  water  in  the  reservoir  or  dam  is  nearly  constant, 
or  varies  between  wide  limits.  In  the  first  case,  especially  if  the  dam  be  close  at  hand  and  the  duty 
of  the  wheel  nearly  constant,  the  channel  is  simply  formed  of  the  proper  width  to  bring  forward  the 
maximum  quantity  which  is  intended  to  be  employed  upon  the  wheel ; and  a sluice  is  placed  at  the 
origin  of  the  channel  in  the  dam-breast  to  regulate  the  quantity  drawn  off  for  immediate  use.  From 
this  sluice,  the  channel — often  formed  of  wooden  troues — follows  the  most  direct  line  over  the  summit 
of  the  wheel,  and  is  terminated  by  a spout  inclined  at  an  angle  sufficient  to  throw  tile  water  perpen- 
dicularly upon  the  start  of  the  second  or  third  bucket  counted  from  the  summit.  The  apron  or  sole  of 
this  spout  is  usually  from  18  to  24  inches  long,  and  declines  from  the  bottom  level  of  the  channel  at  an 
angle  of  12  to  18  degrees,  forming  an  incline  plane  on  which  the  water  attains  the  required  velocity 
before  entering  the  buckets,  and  which  ought  to  be  at  least  equal  to  that  of  the  circumference  of  the 
wheel ; otherwise  it  is  struck,  and  some  portion  of  it  thrown  off  by  the  flat-boards  of  the  buckets  as 
they  successively  come  into  position  with  the  current. 

When  the  dam  is  at  some  considerable  distance,  rendering  it  inconvenient  to  have  recourse  to  the 
sluice  there  situated,  on  every  occasion  that  it  may  be  necessary  to  modify  the  power  of  the  wheel,  a 
second  sluice  or  shuttle  is  placed  contiguous  to  the  spout,  and  which,  in  the  common  class  of  wheels,  is 
usually  set  by  hand  at  the  required  height,  often  directly,  but  sometimes  a simple  contrivance,  consist- 
ing of  a weighted  lever,  intervenes,  by  which  the  shuttle  can  be  adjusted  by  a cord  brought  inside  of 
the  building.  In  the  higher  class  of  wheels,  and  especially  when  great  steadiness  of  motion  is  required, 
the  shuttle  is  worked  by  a self-acting  apparatus — shown  in  its  most  complete  form  in  Figs.  3796  to 
i-'SOS,  with  all  the  improvements  and  appliances  of  modern  mechanism,  as  applied  to  the  large  wheel 
m Greenock. 

3793.  3797. 


When  the  course  is  of  considerable  length,  and  the  level  of  the  water  in  the  reservoir  or  dam  is  sub- 
let to  sudden  variations,  it  is  of  advantage  to  adopt  a slight  modification  of  the  spout  by  which  the 
water  is  thrown  upon  the  wheel.  If  the  sluice  in  the  dam-breast  be  set  to  furnish  the  proper  supply  ol 
water  under  a given  head,  and  the  level  be  increased,  it  will,  of  course,  discharge  a greater  quantity 
than  is  required,  and  thereby  produce  an  increased  head-pressure  upon  the  shuttle.  This  may  be  low- 
ered to  diminish  the  quantity  thrown  upon  the  wheel ; but,  in  consequence  of  the  bead-pressure  accu- 


WATER-WHEELS. 


857 


mulated  in  the  course,  the  velocity  of  efflux  -would  be  increased  often  to  such  an  extent  as,  -without 
precaution,  to  throw  the  water  entirely  over  the  buckets.  To  prevent  this,  and,  at  the  same  time,  to  take 
advantage  of  the  increased  impulse  of  the  water,  the  spout  is  provided  with  a cover  inclined  to  the  axis 
of  the  orifice,  and  connected,  water-tight,  with  the  back-plate  of  the  shuttle.  The  spout  has  thus  the 
outline  of  a truncated  pyramid,  of  which  the  faces  converge  towards  the  extremity  at  an  angle  of  6 to 
V degrees  with  the  axis,  which  is  directed  towards  the  superior  surface  of  the  start  of  the  bucket  im- 
mediately in  advance  of  it.  The  direction  of  the  current  upon  the  wheel  is  thus  preserved  under  any 
variations  of  head-pressure  upon  the  shuttle ; and  the  impulse  being  directed  as  nearly  as  possible  in 
the  line  of  motion  of  the  point  impelled,  its  value  becomes  an  increment  to  the  force  of  gravity  of  the 
water,  and,  to  some  extent,  economizes  a power  which  would  otherwise  act  injuriously  in  projecting  the 
water  beyond  the  proper  range.  The  horizontal  dimension  of  the  orifice,  under  this  arrangement,  and 
especially  when  the  system  of  ventilation  is  incomplete,  ought  to  be  a little  less  than  that  of  the  buckets, 
and  the  height  perpendicular  to  the  axis  ought  not,  in  general,  to  be  more  than  four  inches,  and  it  is 
almost  always  better  to  be  less. 


This  form  of  spout  is  represented  in  Fig.  3774.  It  has  not  been  in  very  general  use  in  this  country, 
although  examples  are  still  met  with  ; but  it  is  still  very  commonly  employed  in  Europe,  espe- 
cially in  France,  where  it  bears  the  significant  name  of  “ duck's-bill.”  In  some  cases,  also,  the  spout  is 
attached  to  the  feed-box  or  small  reservoir  formed  over  the  wheel  in  some  works,  where  the  water  is 
brought  forward  from  the  main  dam  by  a large  pipe  or  covered  conduit  passing  along  the  surface  of 
some  intervening  ground  situated  on  a lower  level  than  the  summit  of  the  wheel,  and  sometimes  entirely 
under  ground,  when  it  is  necessary  to  keep  the  surface  free  of  interruption  for  any  particular  reason,  as 
the  crossing  of  a road  and  the  like.  In  this  arrangement,  there  is  always  a certain  amount  of  loss  of 
head  incurred  by  the  passage  of  the  water  through  the  conduit,  which  must  be  taken  into  account  in  the 
construction  of  the  wheel.  The  effect  of  this  diminution  of  head-pressure  is  to  prevent  the  water  from 
rising  to  the  same  level  in  the  feed-box  as  in  the  reservoir,  by  diminishing  the  force  of  the  current ; and 
this  loss,  which  is  also  a loss  of  fall  upon  the  wheel,  and  consequently  a loss  of  moving  force,  without 
any  compensating  advantage,  except  the  convenience  afforded  under  particular  circumstances,  must  be 
deducted  from  the  height  of  the  fall  in  determining  the  diameter  of  the  wheel. 

The  natural  situation  for  the  opening  to  the  culvert  for  carrying  away  the  tail-water  is  on  the  side 
opposite  to  that  at  which  the  water  is  received  by  the  wheel ; for,  in  that  case,  should  the  lower  arc  of 
the  wheel  dip,  which  it  almost  invariably  does,  from  the  desire  entertained  by  the  millwright  to  econo- 
mize the  fall  as  much  as  possible,  the  run  of  the  water  will  impede  it  less  than  if  its  motion  were  op- 
posed to  the  motion  of  the  wheel.  When  the  wheel  is  kept  entirely  above  the  level  of  the  tail-water, 
this  arrangement  may,  of  course,  be  reversed.  It  is  then  immaterial  at  what  point  the  culvert  opens 
into  the  wheel-pit,  except  that  the  water  will  rise  higher  when  the  direction  of  its  motion  is  changed 
from  that  impressed  upon  it  by  the  motion  of  the  wheel,  and  consequently  a greater  amount  of  tail- 
clearance  must  be  allowed  when  the  escape  is  retarded  by  a change  of  movement.  This  is,  therefore, 
always  avoided  as  much  as  possible  ; but  in  situations  where  the  lead  of  the  water  is  determined  by 
circumstances  of  locality,  and  the  direction  of  the  motion  of  the  wheel  by  circumstances  of  convenience, 
we  commonly  find  that  when  these  conditions  conspire  to  render  the  common  arrangement  inapplicable 
consistently  with  economy,  that,  instead  of  the  water  being  led  over  the  summit  of  the  wheel,  it  is  thrown 
upon  that  side  to  which  the  current  approaches,  the  spout  of  the  shuttle  being  deflected  sufficiently 
backwards  to  reverse  the  motion  of  the  current,  and  direct  it  upon  the  circumference  at  some  distance  be- 
low the  summit.  It  is  easy  to  perceive  that  under  this  arrangement,  which  at  first  was  resorted  to 
rather  as  an  artifice  to  avoid  an  inconvenience,  very  severely  felt  in  cases  where  the  direction  of  the 
waste-water  culvert  was  fixed  by  local  circumstances,  and  in  which  the  wheel-pit  was  liable  to  be  flooded 
with  backwater,  allows  of  the  wheel  being  made  of  any  desired  diameter  even  greater  than  tire  height 
of  the  fall.  It  also  requires  less  of  the  head  to  be  sacrificed  between  the  shuttle  and  the  point  of  the 
wheel  at  which  the  water  is  received,  and  is,  therefore,  more  economical  than  the  primary  arrangement 
from  which  it  was  considered  a deviation  merely  allowable  in  obedience  to  the  local  conditions  of  the 
particular  case.  Its  advantages,  however,  soon  began  to  be  perceived,  especially  in  low  falls,  and  exam- 


858 


WATER- WHEELS. 


pies  of  its  application  speedily  became  numerous.  This  was  favored  by  the  theoretical  notion,  that  a 
wheel  of  large  diameter  is,  in  all  cases,  the  most  economical ; and.  as  already  observed,  this  arrange- 
ment gives  free  scope  to  the  millwright  to  adopt  any  diameter  of  wheel  he  may  think  fit.  The  system 
has  now  become  general,  and  constitutes  one  of  the  main  characteristic  features  of  the  modern  bucketed 
wheel.  It  has,  besides,  removed  the  distinction  between  overshot  and  breast  wheels,  which  was  formerly 
significant.  The  term  overshot  is,  indeed,  not  now  applicable  to  any  of  our  larger  modern  examples, 
except  by  a forced  interpretation  of  the  term,  and  instead  we  ought,  in  strictness,  to  employ  the  term 
high-breast,  as  better  expressing  the  actual  conditions.  We  have  still,  indeed,  some  wheels  of  a minor 
class  scattered  over  the  country,  and  employed  chiefly  for  agricultural  purposes,  which  belong  to  the 
primitive  order  ; but  they  are  only  retained  in  situations  where  the  power  is  superabundant,  and  where 
it  is,  therefore,  not  necessary  to  look  narrowly  into  the  economy  of  its  employment. 


3804. 


In  the  higher  class  of  wheels  constructed  according  to  this  principle,  and  which  were  originally  de- 
nominated  breech-wheels,  the  shuttle  consists  of  an  accurately  fitted  sluice,  usually  commanded  by  an 
adjusting  apparatus  bearing  the  name  of  governor,  which  regulates  the  supply  of  water  admitted  upon 
the  wheel  to  the  power  required.  The  technical  details  and  mode  of  action  of  this  apparatus  are  fully 
shown  and  described,  in  reference  to  the  large  wheel  erected  at  Greenock  for  the  Shaws  Water  Spin- 
ning Co.,  and  need  not  be  here  recapitulated ; but  it  may  be  well  to  observe  that  a fault  is  often  com- 
mitted in  making  the  governor  not  only  bring  the  sluice-geering  into  action,  but  to  hold  it  in  action  un- 
til the  motion  of  the  wheel  has  been  sufficiently  increased  or  diminished  by  the  elevation  or  depression 
of  the  sluice-plate.  This  is  done  for  economy ; and  it  is  admitted  that  the  apparatus  is  thus  greatly 
simplified  in  its  constructive  details.  But  as  all  the  pressure  of  throwing  the  geering  out  of  action  must 
be  overcome  by  the  centrifugal  force  of  the  pendulum  balls,  these  must,  therefore,  of  necessity  be  of 
great  weight,  and  consequently  less  susceptible  of  being  affected  by  slight  variations  of  motion,  on  ac- 
count of  their  greater  inertia.  But  the  far  greater  evil  consists  in  the  geering  being  kept  in  action  until 
the  movement  has  been  so  far  altered  that  the  balls  have  acquired  sufficient  power  to  overcome  the  fric- 
tion due  to  the  pressure  of  the  geering,  and  disengage  itself ; and  which  cannot  possibly  happen  until 
the  speed  has  been  increased  or  diminished  beyond  the  point  required.  To  correct  this,  the  governor 
immediately  falls  into  action  to  produce  the  contrary  effect,  which  again  is  overdone,  and  must  again  be 
corrected.  From  this  cause,  the  movement  of  the  wheel  is  never  steady,  but  continually  oscillates  be- 
tween two  extremes,  and  the  governing  apparatus,  though,  in  the  first  instance,  less  expensive,  is 
speedily  worn  out,  being  constantly  in  action,  and  is  never  satisfactory.  The  principle  to  be  kept  in 
view  is,  to  allow  the  pendulum  balls  to  adjust  themselves  with  perfect  freedom  to  the  velocity  of  the 
wheel,  by  giving  them  no  other  duty  to  perform ; and,  by  a cam,  obeying  the  motion  of  the  balls,  and 
shifting  its  position  in  obedience  to  theirs,  to  throw  the  geering  into  action  in  the  manner  done  in  the 
example  above  referred  to. 

When  the  height  of  the  fall  is  considerably  less  than  the  diameter  of  the  wheel,  we  then  apply  the 


WATER-WHEELS. 


85S 


term  breast  as  expressing  the  relation.  The  -wheel  depicted  in  Figs.  3804  and  3805  comes  under  this 
general  denomination ; and  to  denote  that  the  water  is  received  above  the  line  passing  horizontally 
through  the  axis,  it  takes  the  name  of  high-brcast.  These  terms,  however,  are  manifestly  only  relative  ; 
for  if  the  wheel  had  been  made  of  somewhat  larger  diameter,  the  water  would  have  been  thrown  upon 
a lower  point  of  the  circumference,  and  changed  the  character  of  the  wheel  to  that  of  low-breast.  These 
terms,  therefore,  convey  no  other  positive  intimation  respecting  the  size  of  the  wheel  than  that  its  axis 
is  below,  above,  or  in  the  plane  of  the  water  level.  It,  however,  usually  suggests  that  the  fall  is  low, 
and,  consequently,  that  every  precaution  is  taken  to  render  it,  as  much  as  possible,  available  upon  the 
wheel..  For  this  purpose  an  arc  is  usually  constructed  of  the  same  radius  as  that  of  the  wheel,  to  con 


fine  tlie  water,  and  prevent  it  from  being  spilt  from  the  buckets  before  it  has  arrived  at  the  lowest  point 
of  the  run.  In  the  example  referred  to,  this  arc  is  built  of  hewn  stone ; but  sometimes  it  is  constructed 
»f  timber,  and  not  unfrequently  of  cast-iron  plates.  Sufficient  clearance  is  of  course  necessary  to  allow 
oi  the  wheel  moving  free  of  the  arc,  and  to  this  extent  there  must  always  be  a waste  of  water ; but 
when  the  arc  is  properly  constructed  and  wrought  to  the  circle,  this  clearance  need  not  exceed  half  an 
inch,  which  will  be  the  measure  of  the  plate  of  water  which  escapes  without  producing  its  effect  upon 
the  buckets  immediately  on  their  passing  the  plane  of  the  axis.  This  arrangement  is  sometimes  adopted 
with  good  effect  in  wheels  belonging  to  the  class  called  overshot,  and  it  is  applicable  in  all  cases.  But 
when  the  height  of  the  fall  is  considerable,  and  the  buckets  properly  constructed  to  retain  and  carry 
down  the  water,  it  is  of  less  importance,  as  the  small  loss  at  the  lower  part  of  the  revolution  bears  a 


SGO 


WATER-WHEELS. 


diminished  proportion  to  the  whole  effect  realized.  In  the  breast-wheel,  the  buckets  are  made  more  flat 
and  radial  than  in  wheels  which  receive  the  water  near  the  summit,  and  are  therefore  not  so  well  adapted 
to  retain  the  water.  The  only  reason  assignable  for  this  difference  of  form  is,  that  it  to  some  extent 
economizes  the  fall ; for  in  every  wheel  the  lip  of  the  bucket  must  descend  below  the  water-level  before 
any  water  can  enter  it,  and  consequently  there  is  a loss  of  fall  incurred  in  filling  equal  to  something 
more  than  the  depth  of  the  bucket ; and  the  lower  the  fall  is,  this  will  evidently  bear  a greater  ratio  to 
the  entire  value  of  the  water. 

The  power  of  all  large  wheels  is  taken  off  by  a second  shaft  carrying  a pinion,  which  geers  with  a 
large  spur-wheel  bolted  upon  the  shrouding  of  the  water-wheel.  This  spur-wheel  is  cast  in  parts  or 
segments  and  bolted  together,  and  is  generally,  though  not  invariably,  an  internal  wheel.  When  there 
is  considerable  breadth  between  the  shrouds,  it  is  of  importance  to  take  the  power  at  both  sides,  as 
shown  in  Figs.  3804  and  3806,  and  always  from  the  loaded  arc  of  the  water-wheel.  By  this  arrangement, 
all  strain  is  taken  off  the  arms  and  journals  of  the  wheel,  wnich  otherwise  would  be  excessive.  The 
circumstances  also  accommodate  themselves  to  this  arrangement,  in  so  far  as  the  centre  of  pressure 
of  the  mass  falls  usually  within  the  depth  of  the  shrouding,  and  renders  any  calculation  unnecessary. 

Wheels  of  a diameter  up  to  20  feet  are  frequently  fitted  with  cast-iron 
arms,  instead  of  being  of  the  spider  construction  of  that  above  referred  to ; 
and  they  have  an  advantage  in  being  more  rigid  though  more  heavy,  and 
inerefore  more  severe  on  their  journals.  The  common  and  best  mode  of 
fitting  the  cast-iron  arms  to  the  centres  is  shown  by  Fig.  3806.  The 
arms  A A are  cast  with  projecting  cheeks  on  their  lower  extremities,  which 
are  planed  and  fitted  into  the  dressed  recesses  of  the  centre,  and  are  secured 
generally  by  three,  but  sometimes  by  one  bolt.  The  other  extremities  are 
cast  with  T ends,  which  are  likewise  planed  and  fitted  into  corresponding 
recesses  in  the  shrouds,  and  fastened  by  two  bolts,  and  sometimes  by  ad- 
justable keys. 

It  is  not  uncommon  to  find  the  arms  of  spider-wheels  secured  with  nuts  instead  of  cotterals,  as  shown 
in  the  two  examples  given ; but  the  latter  mode  is  usually  reckoned  preferable,  on  account  of  the  diffi- 
culty of  maintaining  the  truth  of  the  wheel  in  screwing  up  the  nuts  to  the  requisite  degree  of  tightness  ; 
and  the  cotterals  has  the  further  advantage,  that  they  are  more  secure,  and  less  expensive.  The  con- 
structive details  of  this  mode  of  fitting  have  been  already  shown,  and  have  been  highly  approved  by 
some  of  the  first  builders  both  in  Europe  and  in  this  country.  The  example  to  which  these  drawings 
refer  is  not  only  one  of  the  very  largest,  but  perhaps  the  most  complete  in  its  details,  of  any  water- 
wheel yet  constructed. 

To  determine  the  capacity  of  the  wheel  answering  to  a given  supply  of  water,  it  is  necessary  to  take  into 
account  the  rapidity  with  which  the  buckets  are  filled  and  emptied ; in  other  words,  the  angular  velocity 
of  the  wheel.  This  velocity,  it  has  been  remarked,  ought  to  be  slightly  less  than  that  of  the  lamina  of 
water  falling  into  the  wheel  to  prevent  the  back  of  the  buckets,  as  they  pass  the  receiving  point,  from 
striking  against  the  descending  stream,  and  thereby  not  only  wasting  a portion  of  the  water  by  throw- 
ing it  over  the  circumference  of  the  wheel,  but  also  diminishing  the  useful  effect  of  that  which  passes 
into  the  buckets  by  the  counteraction  produced  on  the  wheel. 

The  velocity  of  the  stream  may  be  generally  determined  in  the  following  manner.  Thus  at  the  dam- 
sluice — if  H be  the  depth  to  the  centre  of  the  sluice-opening,  the  velocity  U of  efflux  will  be  ex- 
pressed by 


m being  a coefficient  depending  for  its  value  upon  the  particular  form  of  the  sluice-gate,  but  which  may 
be  taken  generally  = 0’64 ; and  g the  symbol  of  gravity  = 32'2.  Consequently,  if  we  substitute  the 
numerical  values  of  these  symbols,  we  shall  have  the  simple  arithmetical  rule 

U = 7-13371 

And  if  the  lead  or  course  be  short,  and  h the  total  fall  from  its  origin  to  the  extremity  where  the  water 
is  delivered  upon  the  wheel,  the  velocity  u at  that  point  will  be  found  from  the  formula 

U = y/  U2  + 2 (jll, 

m which  U and  g have  the  same  significations  as  above. 

But  if  the  lead  be  of  considerable  length,  it  will  be  necessary  to  take  into  account  the  retardation 
which  the  water  experiences  in  its  passage.  This  is  found  from  a calculation  of  the  surface  which  the 
water  passes  over  in  its  transit,  and  knowing  approximately  the  velocity  with  which  it  moves.  If  we 
call  u (found  as  above)  the  ultimate  velocity  of  the  stream,  and  U that  at  its  origin,  calculated  at  the 
dam-sluice,  then  ■§■  ( u -J-  U)  will  be  nearly  the  mean  velocity  in  the  lead  ; and  dividing  the  number  ol 
cubic  feet  of  water  to  be  delivered  in  a second  by  this  mean  velocity,  the  quotient  will  be  the  mean 
transverse  area  A of  the  current ; and  this  divided  by  the  mean  width  of  the  channel  will  give  the  depth 
of  water.  Now,  the  frictional  retardation  of  a stream  of  water  varying  according  to  the  amount  of  sur- 
face of  the  fluid  in  contact  with  the  bed  upon  which  it  moves,  is,  therefore,  inversely  as  the  whole  quan- 
tity of  fluid — that  is,  for  any  given  quantity  of  water,  the  resistance  being  as  the  surface,  of  the  bottom 
anil  sides  of  the  channel  directly,  and  as  the  whole  quantity  of  water  inversely,  the  diminution  of  velcc 
S L 

city  will  be  as  — ■ in  which  L is  the  length  of  the  channel  in  feet,  and  S the  surface  (bottom  ano 
A 

sides)  over  which  the  water  glides.  The  retardation  is  expressed  by 


3800. 


WATER-WHEELS. 


8G1 


J S SL/U  + w \ 5 


in  which  c is  a coefficient  determined  by  experiment  = -007.  If,  therefore,  U be  the  velocity  due  to 
the  pressure  at  the  sluice,  and  h be  the  total  fall  upon  the  channel,  the  ultimate  velocity  will  be  ex 
pressed  by 


Y 


= v7 


IP  + 2 g h — 0-007 


SL/U  + u\ 

~X\  tT  J 


It  is  scarcely  necessary  to  remark  that  this  is  only  an  approximation,  which,  however,  may  bo  con- 
sidered sufficiently  correct  for  all  practical  purposes ; and  if  greater  exactness  be  desired,  the  value  ol 
V thus  found  may  be  substituted  for  u and  the  equation  resolved  anew  for  a nearer  value  of  V. 

As  the  value  of  h can  be  modified  at  pleasure  in  making  the  channel,  it  is  of  moment  that  these  cal- 
culations be  considered  previous  to  determining  the  position  of  the  shuttle.  If  the  channel  be  already 
existing,  and  it  is  wished  to  determine  the  quantity  of  water  flowing  in  it,  this  may  be  done  with  suffi- 
cient correctness,  by  finding  the  surface  velocity,  and  multiplying  it  by  the  mean  cross-sectional  area  of 
stream : four-fifths  of  the  quantity  thus  found  will  be  very  nearly  the  actual  quantity  flowing  in  the 
channel. 

This  rule,  although  often  employed,  and  without  material  error  when  the  quantity  of  water  flowing 
is  considerable  and  the  velocity  not  great,  is  not  to  be  relied  upon  when  more  than  a rough  approxima- 
tion is  desired.  In  some  cases  it  is  of  importance  to  determine  exactly  the  quantity  of  water  supplied, 
as  when  a rental  is  paid  for  the  power,  when  testing  the  efficiency  of  a wheel,  or  determining  the  power 
necessary  to  impel  certain  kinds  of  machinery ; in  these,  and  analogous  cases,  we  must  have  recourse 
to  more  accurate  formulae.  When  the  surface  of  the  stream  can  be  correctly  ascertained  over  a portion 
of  the  channel,  of  which  the  cross-section  is  nearly  uniform,  the  following  rule,  which  is  founded  on  that 
of  M.  de  Prony,  may  be  employed  with  considerable  confidence.  Let  U denote  the  mean  velocity  of 
the  stream,  (which  is  sought  to  be  determined,)  and  V the  surface  velocity  measured  by  a float  in  the 
middle  of  the  stream,  both  reckoned  in  feet  per  second,  then 


V + 6-50 

V + 8-92 


X V. 


As  an  example — let  the  surface  velocity  be  5 feet  in  a second,  then  will  V -4-  6-5  = 11 ’5  and  V -4-  8'92 
= 13-92,  and 

= — = 'S24  ; therefore,  6'5°  X V = -824  X 5 = 4-12  feet,' 

V + 8-9  13-9  ’ ’ Y + 8-92 


that  is,  the  surface  velocity  of  the  stream  being  5 feet  per  second,  the  mean  velocity  U is  4'12  feet. 
And  this  velocity  being  multiplied  by  the  sectional  area  of  the  stream,  the  result  will  be  the  volume 
of  water  flowing  in  a second ; and  therefore, 


Q = 60  S X U, 


will  be  the  quantity  furnished  in  60  seconds  or  1 minute. 

The  maintaining  power  in  a moving  volume  of  water  is  obviously  proportional  to  the  quantity  of  de- 
scent in  a given  space ; when,  therefore,  the  motion  is  uniform,  and  is  neither  retarded  nor  accelerated 
by  the  force  of  gravitation,  it  is  manifest  that  the  whole  weight  of  the  water  is  employed  in  overcoming 
the  frictional  resistance  ottered  by  the  bottom  and  the  sides  of  the  channel ; and  it’  the  inclination  vary, 
the  relative  weight,  or  the  force  which  urges  the  particles  along  the  inclined  plane,  will  vary  as  the 
height  of  the  plane  when  the  length  is  given,  or  as  the  fall  in  a given  distance.  The  retarding  force, 
which  is  equal  to  the  relative  weight,  must  therefore  also  vary  as  the  fall,  and  the  velocity,  which  is  as 
tire  square  root  of  the  impeding  influence,  must  be  as  the  square  root  of  the  fall ; and  supposing  the 
hydraulic  mean  depth — that  is,  the  depth  which  a current  of  water  would  take  if  spread  out  upon  a 
horizontal  surface  equal  to  the  bottom  and  sides  of  its  channel— to  be  increased  or  diminished,  the  in- 
clination remaining  the  same,  the  frictional  resistance  would  be  diminished  or  increased  in  the  same 
ratio  ; and,  therefore,  in  order  to  preserve  its  equality  with  the  relative  weight,  it  must  be  proportion- 
ally increased  or  diminished  by  increasing  the  square  of  the  velocity  in  the  ratio  of  the  hydraulic  mean 
depth,  or  the  velocity  in  the  ratio  of  its  square  root.  We  may,  therefore,  expect  that  the  velocities  will 
be  conjointly  as  the  square  root  of  the  hydraulic  mean  depth  and  of  the  fall  in  a given  distance,  or  as  a 
mean  proportional  between  these  two  lines.  From  this  reasoning,  Eytelwein  and  some  other  writers 
on  hydraulics,  have  deduced*"* rules  for  determining  the  mean  velocity  of  large  bodies  of  water.  Let  <5 


denote  the  measure  of  declivity,  and  d the  mean  hydraulic  depth  of  the  current,  then  100 


express  the  resulting  velocity  in  feet  per  second — showing  that,  if  the  rate  of  descent  were  only  one  in 
100  X 100,  the  stream  would  acquire  a velocity  represented  simply  by  the  square  root  of  the  hydrau- 
lic mean  depth.  If  / denote  the  fall  in  feet  each  mile,  the  formula  for  the  velocity  will  take  the  form 


5280 


100  11  

y/V  — 8 -v/o/- 


Hence,  the  velocity  reckoned  in  miles  an  hour  is  expressed  by 

11  15  _ 15  _ 

8 '22''/'5/  — T 6V,<5/- 


The  square  root  of  the  product  of  the  hydraulic  depth  into  the  fall  each  mile  in  feet  being  diminished 
by  1 -1 6th,  will  hence  represent  the  mean  velocity  of  a river  in  miles  each  hour. 


862 


WATER-WHEELS. 


* 


This  rule,  'which  is  that  deduced  by  Sir  John  Leslie  for  the  velocity  of  water  in  rivers,  may  be  com- 
pared with  the  result  of  Eytelwein’stformula  for  the  same  purpose,  as  rendered  by  Dr.  T.  Young 
Taking  two  English  miles  as  a given  length,  he  finds  a mean  proportional  between  the  hydraulic  mean 
depth  and  the  fall  in  that  space,  and  inquiring  what  relation  this  bears  to  the  velocity  in  a particular 
case,  finds  that,  in  general,  the  mean  proportional  sought  is  jAths  of  the  velocity  in  a second. 

In  order  to  test  the  accuracy  of  this  rule,  Dr.  Young  takes  an  example  which  could  not  have  been 
known  to  Eytelwein.  Mr.  Watt  observed,  as  Prof.  Robison  informs  us  in  the  article  River,  of  the  En- 
cyclopaedia Britannica,  that  in  a canal  18  feet  wide  above,  and  7 below,  and  4 feet  deep,  having  a fall 
of  4 inches  in  a mile,  the  velocity  was  17  inches  in  a second  at  the  surface,  14  in  the  middle,  and  10  at 
the  bottom ; so  that  the  mean  velocity  will  be  14  inches  or  somewhat  less  in  a second.  Now,  to  find 
the  hydraulic  mean  depth,  we  must  divide  the  area  of  the  section,  2 (18  + 7)  = 50,  by  the  breadth  of 

50 

the  bottom  and  length  of  the  sloping  sides  added  together,  whence  we  have  ■ X 12  = 29T3  inches; 


and  the  fall  in  two  miles  being  8 inches,  we  have  ^/(S  X 29T3)  = 15'26  for  the  mean  proportional  of 
which  — is  13'87,  the  mean  velocity  in  inches  each  second. 

29T3 

To  test  Sir  John  Leslie’s  rule  by  the  same  example,  we  have  f — J ft.  and  S = ■*'  ■ = 2-4275  ft. ; 

therefore,  if  — '8092  nearly,  and  y/cf  = -8996.  Hence,  — y/i f X '8996  = 1-236  feet; 

8 8 

that  is,  14-83  inches,  a result  in  excess  of  that  found  by  Eytelwein’s  rule  of  14-83  — 13-87  = 0‘96  inch. 

17 

By  M.  de  Prony’s  rule  we  have,  V = — = 1-4167  feet,  and 

Y -f  6-50 

Y + 8-92 

which,  multiplied  by  17,  the  surface  velocity  gives  13'1  inches  as  the  mean  velocity.  And,  taking  the 
common  rule  of  deducting  a fifth  from  the  surface  velocity  for  the  mean  velocity  of  the  current,  we 
17 

have  17  — — = 13-6  inches,  which  does  not  differ  greatly  from  M.  Eytelwein’s  rule,  in  which  we  have 

most  confidence,  from  our  own  experience,  when  the  volume  of  water  is  very  great.  For  smaller  quan- 
tities of  water,  such  as  we  find  in  leads  cut  to  supply  bucketed  wheels,  the  modification  which  we  have 
given  of  De  Prony’s  rule  is  much  more  convenient,  and  we  have  found  it,  in  general,  very  correct. 

It  is  frequently  difficult,  and  sometimes  impossible,  to  apply  any  of  these  rules  to  determine  the 
volume  of  water  furnished ; and  it  is  often  of  importance,  as  when  considerable  accuracy  is  desired,  to 
resort  to  more  than  one  mode  of  measurement.  In  all  ordinary  experiments  of  this  kind,  there  is  a 
certain  degree  of  uncertainty  arising  from  inaccuracy  of  measurement ; it  is  therefore  of  importance  to 
have  the  means  of  checking  the  result  of  one  rule  by  that  obtained  by  a different  process.  The  follow- 
ing method,  which  is  not  only  simple  and  generally  applicable,  but  likewise  admitting  of  considerable 


o?07.  A 


accuracy,  will  therefore  be  useful.  This  consists  in  erecting  a notch  in  some  convenient  part  of  the 
watercourse  where  the  velocity  is  not  great.  The  notch  is  easily  formed  in  leads  of  moderate  size  by 
aboard  A A,  Fig.  3806,  stretched  across  the  channel,  and  having  a rectangular  part  AcdA  cut  or 
notched  out  in  the  manner  shown  in  Fig.  3807,  and  through  which  the  whole  of  the  watev  will  be  made 


WATER-WHEELS. 


SOB 


to  pass.  The  notch-board  being  fixed,  a rod  B must  be  fixed  vertically  in  the  channel  a few  yards  be- 
hind, and  having  a mark  n upon  it  at  exactly  the  level  of  the  edge  c d,  of  the  notch.  The  water  being 
then  permitted  to  descend  in  the  lead,  let  its  depth  nm  upon  the  rod  B be  carefully  noted  in  inches, 
then  taking  from  the  second  or  third  column  of  the  annexed  table  the  quantity  corresponding  to  one 
inch  of  width  at  the  depth  noted,  multiply  that  quantity  by  the  whole  width  in  inches,  and  the  result 
will  be  the  whole  quantity  flowing  through  the  notch  in  cubic  feet  per  minute. 

Thus,  if  the  depth  from  m to  n on  the  rod  B be  16 
inches,  and  the  width  of  the  notch  a b be  7 feet  = 84 
inches,  then  corresponding  to  16  inches  is  25'8  cubic 
feet  in  the  second  column,  and  which  multiplied  by 
84  gives  2167‘2  cubic  feet  as  the  whole  quantity  pass- 
ing through  the  notch  in  a minute. 

The  quantity  corresponding  to  16  in  the  third  column 
is  2 7 '4 1 3 cubic  feet,  which  multiplied  by  84  gives 
2202'7  cubic  feet  as  the  supply  per  minute,  which  is 
35^-  cubic  feet  in  excess  of  the  result  obtained  by  em- 
ploying the  second  column.  This  discrepancy  arises 
from  the  third  column  being  calculated  for  weirs 
which  discharge  more  water  in  a given  time  than 
notches,  on  account  of  their  offering  less  impediment 
to  the  motion  of  the  fluid.  A weir  is  a wall  built 
generally  of  solid  masonry  across  the  channel,  with  a 
parallel  plank  fixed  horizontally  on  edge  along  the 
top  of  the  building.  The  plank  is  termed  the  waste- 
board,  and  the  water  flows  over  it  along  the  whole 
breadth  of  the  channel,  and  thus  suffers  no  lateral 
obstruction  as  it  does  in  meeting  the  notch-board,  in 
which  the  passage  is  usually  contracted.  But  if  the 
notch  be  made  equal  in  width  to  the  width  of  the 
channel,  then  this  column  ought  to  be  employed,  since 
under  these  circumstances  the  conditions  are  strictly 
analogous,  and  the  notch  may  be  called  a weir. 

When  the  preceding  table  cannot  be  conveniently 
applied,  the  value  of  Q,  the  quantity  of  water  dis- 
charged in  a minute,  will  be  found  very  nearly  from 
the  expression, 

Q = 200HL  ,/  H, 

in  which  H is  the  height  m n of  the  surface  level  of  the  water  above  the  sole  of  the  notch,  and  L the 

4 

width,  all-in  feet.  Thus  taking  the  example  given  above,  we  have  H = - ft.,  and  T,  = 7 ft.,  therefore, 


Depth  of  the 
upper  edge  of 
the  waste- 
board  below 

Cubic  feet  of  water 
discharged  in  a min- 
ute by  every  inch  of 
the  notch,  accord- 

Cubic  feet  of  water 
discharged  in  a min- 
ute by  eveiy  inch  of 
the  waste-board  of  a 

the  surface,  in 
inches. 

ing  to  Du  liuat’s  for- 
mula. 

ments  made  by  Mr. 
Smeaton. 

i 

0403 

0-428 

2 

1-140 

1-211 

2-095 

2-226 

4 

3-225 

3-427 

5 

4-507 

4-789 

6 

5 925 

6-295 

7 

7-466 

7-933 

8 

9-122 

9-692 

9 

10-884 

11-564 

10 

12-748 

1 3-535 

11 

14-707 

15-632 

12 

16-758 

17-805 

13 

18-895 

20-076 

14 

21-117 

22-437 

15 

23-419 

24-883 

16 

25-800 

27-413 

17 

28-258 

30-024 

18 

30-786 

32-710 

3S08. 


4 4 

Q = 200  X - X 7 v/  - — 2155-3  cubic  feet. 

3 3 

To  find  the  mean  curve  described  by  the  lamina  of  fluid  discharged  upon  the  circumference  of  the 
wheel,  when  the  water  is  carried  over  its  summit,  it  is  necessary,  in  the  first  place,  to  determine  the 
velocity  of  the  fluid  vein  at  that  point.  Its  rate  of  descent  from  the  horizontal  line  inn,  in  Fig.  3808, 
may  then  be  assigned  by  the  following  method : 

Let  u designate  the  velocity  of  the  water  at  the  ex- 
tremity of  the  course,  and  a the  angle,  which  the  direc- 
tion-board of  the  spout  forms  with  the  horizontal  line 
m n,  and  which  expresses  the  deflection  of  the  line 
denoting  the  velocity  u from  the  plane  of  the  horizon ; 
then  the  curve  described  by  the  sheet  of  water  will  be 
expressed  by  the  equation 

gz1  , , 

V = ; — r s h x tan  a, 

J 2 v?  cos2  a n 

x being  the  abscissae  measured  upon  the  horizontal 
plane,  taken  at  half  the  depth  of  the  fluid  vein,  where 
the  mean  velocity  is  u\  and  y the  vertical  ordinates  referred  to  the  same  initial  point  at  n. 

This  equation  may  be  expressed  verbally  thus  : 

To  find  the  ordinates  of  the  mean  curve  described  by  the  water  issuing  upon  a wheel  from  a shuttle 
of  which  the  direction-board  is  inclined  at  a small  angle  with  the  horizontal  plane,  corresponding  to  any 
given  horizontal  absciss®  of  the  curve,  multiply  double  the  square  of  the  velocity  u of  the  water  at  the 
extremity  of  the  direction-board  by  the  square  of  the  cosine  of  the  angle  formed  by  its  direction  with 
the  horizontal  plane,  and  by  this  product  divide  the  square  of  the  given  abscissa  multiplied  into  g ■= 
S2-2.  To  the  quotient  which  results,  add  the  product  of  the  same  abscissa,  multiplied  into  the  tangent 
of  the  angle  a of  the  velocity  u with  the  plane  in  n.  The  sum  will  be  the  ordinate  sought  —y. 

In  giving  any  values  to  x equal  to  3 inches,  6 inches,  9 inches,  &c.,  we  obtain  the  corresponding  values 
of'  y,  and  a curve  being  traced  through  them,  will  give  the  path  of  the  middle  film  of  water 


864 


WATER-WHEELS. 


When  the  direction-board  is  horizontal,  we  have 


and,  therefore, 


a — 0,  cos  a = 1,  tan  a = 0, 


'J  * g „ 

* = 277=2^’ 


which  is  the  following  verbal  rule:  divide  32  2 by  double  of  the  square  of  the  velocity  of  tie  water 
at  the  extremity  of  the  course,  and  multiply  the  quotient  by  the  square  of  the  given  abscissa  x.  The 
product  will  be'  the  ordinate  y , corresponding  to  the  value  assigned  to  x. 

If  the  water  falls  over  a waste-board,  as  in  breech  and  breast  wheels,  the  mean  velocity  of  the 
sheet  will  be  obtained  by  taking  4-5ths  of  that  due  to  the  whole  height  H of  the  level  of  the  water 
above  the  edge  of  the  board. 

Thus,  u = - — 

5 v/2jiH=6'4^/H 

This  velocity  will  project  it  only  slightly  in  a horizontal  direction ; and,  if  much  accuracy  is  required, 
it  is  easy  to  determine  for  any  such  case  the  parabola  described  by  the  stream. 

To  exemplify  the  rule,  as  applied  to  the  overshot-wheel,  we  must,  in  the  first  place,  determine  the 
point  of  the  circumference  where  the  mean  jet  encounters  the  wheel,  draw  a tangent  to  the  parabolic 
curve  described  by  the  fluid  in  the  direction  of  its  final  velocity  V ; and,  having  done  this,  we  calculate 
the  height  due  to  the  velocity  u , adding  the  distance  of  the  point  of  contact  below  the  origin  of  the 
curve.  The  velocity  due  to  the  sum  of  these  heights  is  that  with  which  the  water  falls  into  the 
buckets. 

Thus  let  it  be  required  to  find  the  final  velocity  of  the  water  falling  upon  a wheel  of  111  feet  diam- 
eter, of  which  the  axis  is  10  inches  before  the  vertical  line,  falling  from  the  extremity  of  the  direction- 
board,  which  has  an  inclination  of  1 in  12  ? If  we  suppose  that  the  extremity  of  the  direction-board  is 
•8  inch  above  the  wheel,  and  that  the  piean  velocity  of  the  lamina  of  water  is  4 inches,  and  its  velocity 
9 '84  feet  in  a second,  then, 

tan  a = = 0’083,  cos  a = 0'995,  u = 9'84  ft. 

32 ‘2  xI  2 

y = -5  + 0-083  x = 0468  x 2 + 0'083  x. 

J 2 (9-84  X 0-995)2 

Taking,  therefore,  any  values  of  x at  pleasure,  we  find  the  value  of  y by  a simple  arithmetical  process. 
Thus,  let  x — 3 in.,  we  have  0168  x 2 - 0168  X 9 = T512  and  0'083  x — 0147  ; hence  y = T512  + 
0147  = 2'259  inches. 

The  intersection  of  the  curve  thus  determined  with  the  circumference  of  the  wheel  is  about  2f  inches 
below  the  middle  film  of  the  vein  at  the  extremity  of  the  direction-board ; that  is,  from  the  origin  of  the 
curve,  and  the  height  due  to  the  velocity,  9'84  feet,  a second  being  1-52  feet,  the  total  height  due  to  the 
required  velocity  is  1 foot  9 inches,  and,  consequently,  the  velocity  with  which  the  water  will  strike  the 
bottom  of  the  buckets  will  be  y/64'4  X 115  = 10  6 feet  in  a second. 

The  lead  or  channel  by  which  the  water  is  supplied  to  the  wheel  ought  obviously  to  be  so  constructed 
that  it  shall  consume  as  little  as  possible  of  the  available  fall.  As  a first  condition,  it  ought  therefore  to 
be  as  nearly  straight  as  the  local  circumstances  will  admit;  for  at  every  bend  which  it  makes,  a portion 
of  the  impulse  of  the  water  will  be  absorbed  by  the  concave  side  of  the  channel,  and  therefore  a greater 
declivity  will  be  necessary  to  bring  forward  a given  quantity  of  water  in  the  unit  of  time.  Moreover, 
the  centrifugal  force  created  at  the  sinuosities  has  the  effect  of  raising  the  surface  and  augmenting  the 
abrasion  of  the  banks  at  those  points ; and  if  by  any  accident  a breach  be  produced,  the  sweep  of  the 
current  must  necessarily  tend  to  enlarge  the  concavity  with  an  accelerated  progression.  The  inclination 
ought  likewise  to  be  as  nearly  as  possible  uniform — more  correctly,  it  ought  to  be  so  regulated  that  the 
transverse  sectional  area  of  the  stream  shall  remain  constant  throughout  its  whole  length.  If  the  course 
be  constructed  of  masonry,  it  is  obvious,  from  the  remarks  made  respecting  the  effects  of  the  hydraulic 
mean  depth  on  the  velocity  of  the  current,  that  it  will  be  of  advantage  to  build  the  side-walls  verti- 
cally ; and  in  order  that  the  resistance  may  be  the  least  possible,  the  depth  of  the  stream  should  be 
equal  to  half  the  width.  This  rule  may  be  followed  when  the  quantity  of  water  is  small ; but  in  leads 
of  large  area,  the  width  at  bottom  is  usually  from  four  to  six  times  the  depth.  When  the  depth  is  con- 
siderable, the  walls  are  moreover  built  with  a certain  amount  of  batter.  Mr.  Eytelwein,  indeed,  recom- 
mends that  the  breadth  at  the  bottom  be  fds  of  the  depth,  and  at  the  surface  3J.  The  area  of  such  a 
section  is  twice  the  square  of  the  depth,  and  the  hydraulic  mean  depth  fds  of  the  actual  depth. 

The  slope  here  recommended  is  4 to  3,  forming  an  angle  to  the  plane  of  the  horizon  with  the  water- 
way of  37° ; whereas,  in  this  country,  the  ratio  commonly  adopted  for  canals  is  3 to  2,  making  an  angle 
of  34°,  which  is  far  more  than  sufficient  for  any  watercourse  intended  merely  for  the  purpose  under 
consideration.  The  best  angle  to  insure  durability  will,  however,  very  much  depend  upon  local  circum- 
stances, and  the  material  of  which  the  banks  are  constructed  or  composed. 

Having  fixed  upon  the  dimensions  of  the  lead  and  the  intended  depth  of  the  current,  if  we  call  A 
the  area  of  its  transverse  section,  and  q the  volume  of  water  to  be  brought  forward  in  a second,  the 

mean  velocity  U,  which  the  water  must  have,  will  be  expressed  by  U = And  calling  S the  peri- 

inetrical  surface,  (bottom  and  sides,)  and  I the  inclination  or  fall  in  100  feet,  which  the  channel  ought  to 
have  to  give  the  velocity  U required,  we  shall  have 

I = f U (-00042  U -j-  -00444 J. 

.A. 


WATER-WHEELS. 


865 


Thnt  is,  to  find  the  fall  in  100  feet  of  length  of  the  channel,  multiply  '00942  by  the  given  velocity  TJ : 
add  to  the  product  '00444 ; multiply  the  sum  again  by  the  velocity,  and  the  product  by  the  perimetri- 
cal  surface,  and  divide  the  last  product  by  the  transverse  sectional  area  of  the  channel. 

Thus,  if  the  quantity  of  water  to  be  brought  forward  be  40  cubic  feet  every  second,  in  a channel  of 
18  feet,  width,  the  depth  of  the  water  not  to  extend  feet,  we  shall  have, 

A the  area  of  the  section  = 10  X 2'5  ft.  = 25  sq.  ft. 

40 

U the  mean  velocity  = — — = T6  feet  in  a second. 

1 5 

S the  perimetrical  surface  = 10  -j-  (2  X 24)  = 15  feet;  therefore  I = — — X 1'6  (0'00942  X 1'6  -f- 

•00444)  ='0585  feet,  the  fall  in  100  feet  of  length  of  the  channel. 

This  rule,  at  least  the  latter  part  of  it,  referring  to  the  inclination,  may  be  dispensed  with  when  the 
channel  is  short.  In  cases  where  the  whole  run  does  not  exceed  a length  of  two  or  three  hundred  feet, 
the  bottom  may  be  made  quite  level,  as  the  depth  of  the  water  in  the  channel  will  give  sufficient  fall 
for  the  velocity  required,  provided  the  area  of  section  be  made  of  ordinary  magnitude. 

Equal  care  is  usually  necessary  in  the  construction  of  the  tail-race  as  in  that  of  the  lead-run  ; for  it  is 
of  quite  as  much  importance  that  the  water  leave  the  wheel-pit  freely,  as  that  it  be  brought  forward 
with  as  little  loss  of  fall  as  possible.  The  same  rule  will  apply  in  both  cases  ; but  without  some  .judg- 
ment in  the  engineer  to  apply  it,  with  allowance  for  sinuosities,  it  is  better  to  err  on  the  side  of  excess 
in  the  case  of  the  tail-race,  than  to  encounter  the  risk  of  flooding  the  wheel  in  backwater. 

The  quantity  of  water  to  be  used  being  ascertained  by  the  preceding  methods,  the  capacity  of  the 
wheel  may  be  readily  determined.  If  q denote  the  volume  of  water  flowing  in  a second  of  time,  d the 
distance  between  two  buckets  reckoned  upon  the  exterior  circumference  of  the  wheel,  and  v the  velocity 
of  those  points  of  the  circumference,  it  is  evident  that  in  one  second  there  will  pass  under  the  apron  of 


the  shuttle  a number  of  buckets  equal  to  — , and  consequently  that  each  will  receive  a volume  of  water 
equal  to  q divided  by  — ; that  is,  = q— . But  it  is  manifestly  necessary  that  the  bucket  be  capable  of 


containing  not  only  this  quantity,  but  even  a quantity  about  three  times  as  great,  otherwise  a portion  of 
the  water  will  be  spilt  from  the  buckets  too  soon,  and  without  producing  its  effect  upon  the  wheel.  If 
l represent  the  width  of  the  bucket,  that  is,  the  width  of  the  wheel  within  the  shrouds,  and  s the  area 
of  its  transverse  section— more  correctly,  the  area  of  the  section  of  the  mass  of  fluid  which  it  .contains  at 
the  moment  it  passes  the  jet — s l will  represent  its  capacity,  and  in  relation  to  the  section  of  the  bucket 
itself  we  shall  have 


*1  = 3 


d q 

o-=180-T_ 
W M hi 


M being  the  number  of  buckets  in  the  wheel,  and  N the  number  of  revolutions  which  the  wheel  makes 
in  a minute.  And  since 

d = - - and  v — — , therefore  l = ■ T — - 

M 60  M N S 


which  is  the  width  of  the  wheel  when  Q is  tl.c  volume  of  water  to  be  employed  upon  it  in  a minute,  and 
when  it  is  expected  to  realize  the  maximum  mechanical  effect  of  the  water. 

We  proceed  to  establish  the  values  of  these  symbols  from  considerations  involved  in  the  modus  ope- 
rands of  the  wheel ; but  for  practical  purposes,  we  may  remark  that,  with  slight  variation,  s may  be 

Q 

taken  = \ square  foot ; l — 4'5  - and  M = 2'88  D. 

We  have  already  seen  that  the  whole  dynamical  force  of  the  stream  of  water  employed  in  impelling 
a wheel  of  any  form  is  expressed  by  W 11 ; but  as  the  whole  height  H can  in  no  case  be  rendered  effec- 
tive, we  have  found  it  necessary  to  affect  this  product  by  a coefficient  m,  which  is  always  a proper  frac- 
tion, expressing  the  ratio  of  the  force  expended  to  that  realized  by  the  particular  mover.  To  ascertain 
the  theoretical  value  of  m,  which  often,  however,  differs  considerably  from  the  actual  value,  let  us  take, 
in  the  first  place,  the  overshot-wheel,  as  the  simplest  case  which  the  problem  presents.  Referring  to 
Fig.  Slid,  let  the  horizontal  lines  M A and  F B represent  the  higher  and  lower  water  levels  ; the  verti- 
cal distance  A B will  then  indicate  the  entire  height  H of  the  fall.  If  we  divide  this  height  into  three 
parts — A c the  part  comprised  between  the  higher  surface  of  the  water  and  the  point  where  the  stream 
strikes  the  wheel ; c D equal  to  the  height  of  the  arc  of  the  wheel,  which  may  be  considered  as  filled 
with  water  ; and  B D the  distance  between  the  point  at  which  the  water  may  be  considered  to  be  wholly 
discharged  and  the  bottom  of  the  fall — this  division  will  enable  us  to  particularize  and  estimate  the  losses 
which  take  place  between  the  several  partial  limits,  and  therefore  between  the  extreme  limits  A and  B. 

Within  the  limit  c and  D we  have  the  whole  effect  of  the  expenditure  realized  upon  the  wheel,  since 
the  whole  volume  of  fluid  acts  constantly,  and  with  its  whole  weight  in  the  vertical  direction,  it  must 
realize  upon  this  part  of  the  wheel  an  effect  corresponding  to  the  height  through  which  it  descends,  and 
yield  a result  which,  in  conformity  with  the  notation  adopted,  will  be  expressed  by  W X c D.  The 
height  A c is  that  due  to  the  velocity  with  which  the  water  falls  into  the  buckets,  and  with  which  it 
would  strike  the  start-boards,  if  it  did  not  experience  any  diminution  between  the  shuttle  and  the  point 
of  impulse.  But  this  condition  does  not  hold  true  ; for  at  the  point  where  the  fluid  encounters  the  wheel, 
the  height  due  to  the  velocity  is  not  A c,  (which,  for  brevity,  we  shall  put  = A,)  but  to  a height  h — ^ A. 
The  value  of  the  coefficient  ^ will  depend  upon  various  conditions.  In  the  first  place,  there  arises  a loss 
equivalent  to  a loss  of  velocity  from  the  contraction  of  the  fluid  vein  ( vena  contractu)  which  the  fluid  ex 
Vol.  II. — 55 


866 


WATER-WHEELS. 


periences  in  its  passage  through  the  orifice  of  the  shuttle ; secondly,  from  the  resistance  offered  by  the 
surfaces  over  -which  it  passes  ; thirdly,  from  the  dispersion  of  the  filaments  of  the  iluid  by  striking 
against  the  oblique  plates  of  the  buckets  ; and  fourthly,  from  the  oblique  direction  with  which  the  mean 
volume  of  fluid  arrives  at  the  bottom  of  the  buckets.  This  obliquity  may,  in  general,  be  taken  at  30°, 
causing  a diminution  in  tire  value  of  A of  0T4,  and  consequently  a corresponding  diminution  of  the  force 
of  the  impulse.  All  these  causes  combined  are  fouud  according  to  local  circumstances,  such  as  a good 
or  bad  arrangement  of  the  shuttle  and  direction-plate  or  apron,  to  be  equivalent  to  form  two  tenths  tc 
three-tenths  of  the  whole  value  of  A.  Let  A a be  the  portion  of  the  height  A c,  representing  the  value 
of  n A,  the  remaining  part  a c will  then  represent  the  height  A — ^ A,  due  to  the  actual  velocity  V of  the 
jet,  and  consequently  equal  to  -0155  V2. 

From  what  has  been  before  explained  regarding  the  impulsive  action  of  a current  of  water,  this  height 
will  be  subject  to  two  other  reductions : the  one  A'  = '0155  v 2 is  that  due  to  the  velocity  v of  the  wheel 
in  feet  per  second,  and  therefore  increases  with  that  velocity  ; the  other  A"  = '0155  (V  — vf  is  the 
height  due  to  the  velocity  lost  by  the  shock,  and  which,  on  the  contrary,  decreases  as  the  velocity  v in- 
creases. The  sum  of  these  losses  will  be  the  least  possible,  or  ’0155  j vl  + (V  — vf  j-  will  be  a minimum 
when  9 = 1 V.  They  will  be  respectively  equal,  that  is,  each  will  be  | X '0155  V2  = i A (1  — f) ; and 
the  two  together,  that  is,  a b -f-  b d,  will  be  equal  to  -J  A (1  — fi).  In  this  case  of  minimum  loss,  the  re- 
maining part  d c,  which  is  all  of  the  fell  A c that  can  be  regarded  as  effective,  will  therefore  be  equal 
also  to  -J  A (1  — n)  = -J  a c,  and  consequently  less  than  -J-  h = \ A c,  that  is,  than  half  the  head  reserved 
between  the  surface  level  of  the  water  and  the  point  at  which  it  is  received  upon  the  wheel. 

Although  the  sum  of  the  two  losses  h'  and  h"  cannot  thus  be  less  than  $ A (1  — //),  we  know  that  it 
can  be,  and  is,  indeed,  almost  always  considerably  greater,  and  increases  as  the  difference  between  hi 
and  A"  increases.  It  will  obtain  its  maximum , if  one  of  the  two  quantities,  A"  for  example,  should  be- 
come zero,  giving  rise  to  the  condition  V = v.  In  that  case  we  have  h'  = -0155  V“  = A (1  — n),  that  is, 
ab  = a c,  showing  that  no  part  of  the  fall  A c remains  effective.  But  in  practice  this  condition  can  never 
arise,  unless  by  miscalculation  of  the  primary  values  of  V and  v.  This  last  must  always  be  less  than 
the  former,  and  consequently  h"  must  always  have  a real  value ; and  in  every  case  where  h"  is  greater 
than  zero,  it  is  manifest,  from  what  has  gone  before,  that  a certain  portion,  however  small,  of  the  height 
A c must  remain  effective.  Theoretically,  this  is  shown  to  be  less  than  -J-  A ; and  under  the  very  best 
arrangements  it  cannot,  in  practice,  be  expected  to  amount  to  § A,  and  in  ordinary  cases  it  ought  not  tc 
be  assumed  greater  than  -J  A.  As  a general  rule  in  practice,  it  may  therefore  be  admitted,  that  in  bucket- 
wheels,  about  two-thirds  of  the  part  of  the  fall  comprised  between  the  level  of  the  water  at  the  shuttle, 
and  the  point  where  the  fluid  encounters  the  wheel,  is  lost,  as  respects  the  effect  produced.  The  actual 
value  of  this  height  A.  which  may  be  generally  expressed  by  W j A (1  — v)~  A'  — h"\ , will  therefore 
he  represented  by 

W (A  — ! A)  = § W A, 

a result  which  we  shall  subsequently  find  is  closely  analogous  to  that  obtained  experimentally  as  the 
effect  of  the  best  forms  of  impulsive  wheels. 

Since,  then,  a third  only  of  the  part  of  the  fall  above  the  wheel  is  available  as  power,  whilst  the  whole 
of  the  part  from  that  point  downwards  to  the  turn  of  the  buckets,  namely,  c D,  the  height  of  the  loaded 
arc,  is  entirely  realized,  it  is  manifestly  of  advantage  to  augment  this  latter  part  as  much  as  possible,  at 
the  expense  of  the  former.  But  this  augmentation  has  a near  limit,  since  there  would  be  no  economv, 
but  the  converse,  in  raising  the  point  of  reception  so  much,  that  the  water,  in  arriving  at  the  wheel,  would 
have  a less  velocity  than  the  buckets.  In  this  case,  it  could  not  begin  to  act  upon  the  wheel,  except  as 
a retarding  influence,  until,  by  an  acceleration  of  its  velocity,  it  established  the  necessary  condition 
V v. 

The  portion  of  the  fall  D B,  from  the  bottom  of  the  loaded  arc  downwards,  is  evidently  lost,  without 
answering  any  beneficial  purpose.  This  loss  arises  from  two  causes — rather  consists  of  two  parts.  The 
part  e B is  a measure  of  the  loss  resulting  from  the  form  of  the  buckets,  and  the  small  portion  D e of 
that  caused  by  the  velocity  of  the  wheel,  or,  more  correctly,  it  is  a measure  of  the  loss  occasioned  by 
the  centrifugal  force  produced  in  the  fluid  by  the  angular  velocity  communicated  to  it  in  its  descent  in 
the  buckets.  Leaving  this  effect  out  of  view  in  the  mean  time,  it  is  evident  that,  if  not  influenced  by 
any  central  force,  the  surface  of  the  water  contained  in  the  buckets  would  continue  horizontal.  In  pro- 
portion as  the  buckets  descend,  in  consequence  of  the  revolution  of  the  wheel,  this  surface  gradually  ap- 
proaches the  lip  of  the  containing  or  front  plate  of  the  bucket ; and  the  instant  after  it  arrives  at  this 
position,  marked  A i , it  begins  to  be  discharged,  and  the  bucket  will  be  completely  emptied  when  the 
face  has  attained  the  horizontal  position  marked  k l.  The  arc  F A,  which  measures  the  distance  of  the 
base  of  the  wheel  to  the  point  where  the  water  begins  to  be  discharged,  will  therefore  include  the  par- 
tially loaded  arc  A k and  the  empty  arc  k S’.  This  last  is  equal  to  the  angle  u k l,  which  the  front  plate 
of  the  bucket  makes  with  the  tangent  to  the  circumference,  an  angle  which  is  known  from  the  rules  em- 
ployed in  tracing  the  lines  of  the  buckets,  and  which  we  may  here  designate  by  a.  The  arc  F h=F  k 
-j-  k A,  and  this  last  k h is  equal  to  the  angle  x h i,  which  the  front  plate  of  the  bucket  makes  with  the 
surface  of  the  water  at  the  point  where  the  fluid  begins  to  be  discharged,  and  which,  for  brevity,  may 
be  called  z.  We  have  therefore  F A = a-j-  '. 

Whatever  may  be  the  magnitude  of  the  two  arcs  of  discharge,  from  these  data  we  can  always  deter- 
mine the  rate  of  diminution  of  the  quantity  of  water  remaining  in  the  buckets  between  the  extreme 
points  where  it  begins  to  overflow  and  where  it  leaves  the  bucket  entirely  empty,  and  therefore  can 
determine  the  mean  arc  of  discharge,  and  from  this  the  mean  quantity  of  effect  due  to  the  water  carried 
below  the  commencement  of  the  arc  at  A,  in  terms  of  the  whole  quantity  which  the  buckets  would  be 
capable  of  carrying  in  their  horizontal  position  in  passing  through  the  height  c D.  By  determining  the 
mean  of  this  arc,  we  find  the  point  at  which,  if  the  whole  water  were  instantly  discharged  irom  each 
bucket  as  it  passed,  the  effect  upon  the  wheel  would  be  the  same  as  takes  place  when  it  is  prolonged 


WATER-WHEELS. 


8G7 


over  the  whole  length  of  the  arc  h k.  Generally,  indeed,  the  mean  is  the  arithmetical  mean  distance 
between  h and  k,  and  may  be  expressed  by  a -f-  1-  2.  If  upon  A B we  take  e at  such  a height  that  a 
horizontal  line  meeting  the  circumference  of  the  wheel  at  a point  equidistant  from  h and  k,  then  will 
e B be  the  total  loss  of  fall  arising  from  the  reversion  of  the  buckets  ; and  the  wheel  will  yield  the  same 
result  as  if  the  entire  water,  instead  of  being  gradually  discharged  between  these  points,  were  carried 
down  to  the  point  e,  and  then  instantly  thrown  from  the  buckets.  The  arc  below  that  point  may  there- 
fore be  regarded  as  entirely  empty,  and  producing  no  effect ; and  to  designate  its  relation,  we  have  e B 
equal  to  the  versed  sine  of  that  mean  arc,  of  which  the  semi  diameter  of  the  wheel  is  the  radius  ; and 
therefore  putting  D to  denote  the  diameter,  we  shall  have 

e B = J D ] 1 — cos  (ct  + iz)\. 

It  may  be  remarked  that  the  angle  z,  which  the  surface  of  the  fluid  makes  at  the  commencement  of 
the  discharge  with  the  front  plate  of  the  bucket,  will  depend  upon  the  volume  of  water  in  the  buckets, 
as  well,  as  upon  the  form  and  dimensions  of  these,  both  of  which  are,  of  course,  either  known  from  the 
rules  employed  in  the  design  of  the  wheel,  or  may  be  ascertained  by  direct  measurement. 

It  remains  to  determine  the  loss  of  head  resulting  from  the  centrifugal  force  produced  in  the  fluid 
filling  the  buckets,  by  the  motion  of  the  wheel.  This  loss  is  sometimes  considerable,  although  not  com- 
monly reckoned  among  the  influences  to  which  wheels  of  this  class  are  liable.  M.  Poncelet  was  the  first, 
we  believe,  to  direct  attention  to  it,  and  has  established  a theorem  for  its  determination,  which  may  be 
said  to  complete  the  theory  of  the  modus  operandi  of  bucketed  wheels. 

It  has  been  already  stated  that  if  a body  move  in  a circle  at 
a distance  x from  the  centre,  its  centrifugal  force  will  be  express- 

w w v2  , v . . 

ed  by  — u2  x = — . — , when  — is  put  for  the  angular  velocity 
ff  g x x 

with  which  the  body  revolves.  Now,  since  every  molecule  of 
fluid  contained  in  the  buckets  of  a wheel  in  motion  is  subjected 
to  the  action  of  the  two  forces — that  of  gravity  and  the  centrifu- 
gal action — we  may  confine  our  attention  to  one  such  molecule  e 
w 

of  which  the  mass  — may,  for  brevity  of  expression,  be  called  m. 

If  e ip  in  the  annexed  diagram,  Fig.  3809,  represent  the  force  m g 
of  gravity  acting  vertically,  and  e q , measured  in  the  direction  of 
the  radius  C e,  represent  the  centrifugal  force  m wax,  the  diagonal 
e r of  the  parallelogram  will  be  the  resultant  of  the  two  forces, 
and  may  be  regarded  as  representing  the  measure  and  direction 
of  a new  force  replacing  the  two  actual  forces  ep  and  e q,  and 
producing  upon  the  molecule  the  same  intensity  of  action.  If  we 
prolong  e r until  it  meets  the  vertical  fine  E O passing  through 

the  centre  C in  O,  this  point  will  be  such  that  C 0 = and, 

Ul 

therefore,  is  independent  of  the  position  of  the  molecules,  and  the 
same  for  all — all  the  resultants  of  the  forces  converging  to  that 
point,  which  is  therefore  the  centre  of  action  whence  all  the  forces 
are  directed.  The  surface  of  the  fluid  being  always  perpendicu- 
lar to  the  direction  of  the  force  which  acts  upon  the  molecules, 
that  of  the  fluid  contained  in  all  the  buckets  will  be  so  to  the 
lines  passing  to  the  point  0 from  any  point  of  the  wheel,  and, 
consequently,  the  section  s t of  any  given  surface  will  be  an  arc 
of  a circle  having  0 for  its  centre. 

In  the  revolution  of  the  wheel,  the  extremity  s of  this  arc  ap- 
proaches gradually  the  lip  of  the  front  plate  of  the  bucket,  and 
will  arrive  at  it  whenever  the  bucket  shall  have  come  into  the 
position  A B I.  Immediately  after  it  will  begin  to  be  discharged, 
and  the  discharge  will  continue  until  the  bucket  has  descended  \ 

to  the  position  A'  B'  I',  where  the  limiting  arc  of  the  fluid  surface  ''Q 

will  have  passed  under  the  bucket-plate  A'  B'. 

In  wheels  moving  at  ordinary  velocities  the  surface  of  the  water  m the  buckets  may  be  regarded  as 
planes  perpendicular  to  fines  drawn  to  them  from  the  centre  0.  On  this  supposition  the  two  arcs  of 
discharge,  A E and  A E,  may  be  thus  determined.  The  first,  that  is,  the  whole  arc  measured  by  the 
angle  A C E,  is  equal  to 

G A F = GAB-f  BAf-f  IAF  = a -f-  2 -j-  y 

m designating  the  angle  l AF  = «OC  by  y,  the  point  a being  equidistant  between  s'  and  V.  Taking 
o,g  pei  pendicular  to  a C,  and  calling  b the  angle  which  the  first  of  these  fines  makes  with  the  tangent 
A G,  supposing  both  produced  until  they  meet,  and  which  will  necessarily  be  equal  to  the  arigl  j 
A C a ■ and 

Z.  OaC  = /_  g at'  = /_  G A t'  — b. 

Moreover,  the  triangle  0 a C gives 

-4n  a 0 0 : a C : : sin  0 a 0 : 0 C, 

(i  f* 

sin  y : p : : sin  [a  -f  Z — b)  : — 

v 


that  is, 


868 


WATER-WHEELS. 


in  ■which  r is  the  dynamical  radius  of  the  wheel,  and  p the  same  radius,  diminished  by  half  the  depth  a 
the  buckets.  From  this  analogy  we  obtain 


sin  y ■- 


p v*  sin  (a  + " — b) 

~7  ^ ' 


The  angle  b being  generally  very  small,  will  very  slightly  influence  the  value  of  ?/,  and  may,  there- 
fore, be  neglected  in  determining  the  angle  of  discharge  without  sensible  error;  but  by  way  of  compen- 
sation, we  may  substitute  for  p the  dynamical  radius  r,  making 

sin  y = — . sin  ( a -4-  z). 
gr 


To  find  the  measure  of  the  arc  A'  E : if  we  take  y'  to  denote  the  angle  a'  0 E we  shall  have  A’  E 
= Z.  («  + y')-  And  from  the  same  species  of  reasoning  employed  for  y we  find 

• , ^ ■ 
sin  ?/  = — . sin  a. 
gr 

From  these  values  we  might  establish  a general  expression  for  the  mean  arc  of  discharge ; but,  as 
already  remarked,  this  does  not  ditfer  sensibly  from  the  arithmetical  mean,  and  may  therefore  be  rep- 
resented by  a + \ z -f-  i y + -J  y'.  And  reverting  to  Fig.  3808,  its  versed  sine  will  be  represented  by 
D B,  which  is  the  whole  loss  of  head  resulting  from  the  form  of  the  buckets  and  the  centrifugal  force 
conjoinedly,  and  may  thus  be  calculated  previous  to  the  construction  of  the  wheel.  If  we  designate 
this  loss  by  k'",  we  shall  have 

h"'  = lD  jl  — cos(a  + \z  + \y  + ly')\ 


As  an  example  of  the  arithmetical  process  of  determining  this  loss  of  head  from  a priori  data,  let  the 
diameter  of  the  wheel  be  37-J  feet,  the  number  of  buckets  92,  the  width  l = 3'55  feet  = 3 feet  6 J inches, 
and  the  depth  12'8  inches.  The  breadth  A B of  the  first  plate  of  the  buckets  is  1-522  feet,  and  a line 
joining  A I = 1 -683  feet.  The  angle  GAB  which  A B makes  with  the  tangent  A G to  the  circumfer- 
ence is  31°  37'  = a ; B A I = 9°  8' ; and  A I B = 53°  10' ; the  surface  of  the  triangle  B A I B is  there- 
fore = '20344  square  feet  = s'.  The  dynamical  radius  r of  the  wheel  is  17'935  feet,  and  the  distance  d 
between  the  buckets  measured  on  the  circle  described  by  that  radius  is  1'225  feet ; the  velocity  v at  the 
same  circle  = 8'2  feet  in  a second.  The  quantity  of  water  furnished  in  the  same  unit  of  time  is  6'3 
cubic  feet  = q.  The  section  s of  water  contained  in  a bucket  before  it  begins  to  discharge  will  there- 
fore be 


s 


q d 5-3  X 1'225 

lv~  3-55  X 8 2 


0-22299  sq.  ft. 


But  this  section  being  greater  than  -20344  = .s',  shows  that  the  water  surface  meets  the  sole  at  some 
point  V higher  than  I.  Now  the  angle  z,  that  is,  the  angle  which  the  surface  of  the  water  makes  with 
the  face-plate  of  the  bucket,  will  be  equal  to  the  sum  of  the  angles  B A I and  I A V. 

To  find  this  last  we  may  take,  without  sensible  error,* 


tan  I A t'  — 


2 (s — s') 


•0391 


A I2  — 2 (s  — s')  tan  A B I 2'8325  — -006286 


= tan  0°  47'  34"; 


therefore,  z = A B I + 1 A t'  — 9°  8'  -j-  0°  47'  34"  = 9°  56'  nearly. 
To  find  y and  y'  we  have,  for  the  first, 


v*  . , , N (8-2)2 

sin  ?/  = — sin  (a  4-  z)  = 

J gr  K ^ ' 32-2  X 17-935 


X sin  (31°  37'  -+-  9°  56')  = sin  4°  26'  very  nearly. 


sin  y'  = — . sin  a - 
gr 


(8-2)2 


32-2  X 17-935 


X sin  31°  37'  = sin  3°  30'  very  nearly. 


For  the  whole  ineffective  arc  of  discharge  we  have,  therefore, 

a + i--  + ll/  + hy'  = I00  S3' ; 

and  from  this  we  obtain  as  the  total  loss 

h'"  — i X 37-J  (1  — cos  40°  33')  = 4-502  feet 

If  we  decompose  this  into  the  losses  incurred  by  the  form  of  the  buckets  and  the  centrifugal  force,  we 
find  for  the  former 

c B = ^ X 37  £ (I  — cos  36°  35')  = 3-694  feet ; 
and  . • . c D = (4-502  — 3'694)  feet  = 0'808  feet. 

These  parts  are,  therefore,  very  nearly  as  100  to  22 ; consequently,  retaining  these  numbers,  the  loss  ol 
fall  below  the  loaded  arc  is  shown  to  be  increased  by  the  centrifugal  force  communicated  to  the  fluid 
from  100  to  122. 

In  conformity  with  the  principle  before  indicated,  we  must,  in  order  to  arrive  at  a complete  theoret- 
ical expression  of  the  value  of  the  fall,  subtract  these  several  losses,  and  multiply  the  remainder  by  the 
weight  of  water  for  the  total  effect,  which  will  then  be  expressed  by 

W (H  — tlh  — W — h"  — h"’). 

But  this  expression  being  deduced  entirely  from  theoretical  considerations,  we  must,  in  order  to  com- 


* When  the  point  ('  falls  below  I,  that  is,  when  s'  is  greater  than  s,  the  formula  for  z becomes 

2s- AB 

tan  z = A B.2  + 2s  CQt  ( lg0o  _•  A j}  jy 


WATER-WHEELS. 


869 


pare  it  with  the  results  of  experience,  applicable  to  every  particular  case,  introduce  our  coefficient  of 
reduction  m,  when  we  will  have  as  the  actual  effect  developed  by  the  wheel 

E = i#W  (H  — — h‘  — h"  — /<"'). 

From  this  it  therefore  appears  that  in  every  bucket-wheel  the  ultimate  effect  will  be  increased  as  the 
five  quantities  //,  h,  li',  h" . h'"  are  diminished.  Now  these  have  respect, 

*<,  to  the  construction  of  the  shuttle  and  watercourse,  which  ought  accordingly  to  be  adapted  with 
care  to  the  particular  case ; 

h,  to  the  diameter  of  the  wheel,  which,  therefore,  ought  to  be  as  great  as  the  other  conditions  will 
admit,  (it  being  understood  here  that  the  wheel  is  constructed  on  the  overshot  principle ;) 

h'  and  h",  to  the  difference  of  velocity  between  the  water  and  the  wheel  for  a given  value  of  h ; a 
condition  which  will  be  satisfied  the  more  nearly  as  the  velocity  of  the  wheel  approaches  half  the  ve- 
locity of  the  water  at  the  moment  it  arrives  at  the  bottom  of  the  buckets  ; 

h"1,  to  the  proper  disposition  and  form  of  the  buckets,  and  a small  velocity  of  the  wheel,  by  which 
the  water  will  be  carried  to  the  lowest  point  possible  of  the  fall  before  it  is  discharged. 

The  only  trustworthy  experiments  on  wheels  of  this  class,  which  have  been  published,  are  those  of 
Mr.  Smeaton,  made  in  1759,  upon  a small  model  wheel  of  two  feet  diameter.  Various  details  are, 
however,  wanting  to  enable  us  to  compare  hi9  results  with  the  preceding  formulae — especially  the  form 
and  dimensions  of  the  buckets.  The  following  table  contains  the  summary  of  his  results : 


No. 

Whole 

descent. 

Water 
expend- 
ed in  a 
minute. 

Turn9  at 
the  max- 
imum in 
a min- 
ute. 

Weight 
raised  at 
the  max- 
imum. 

Power  of 
the  whole 
descent. 

Power  of 
the  wheel. 

Effect. 

Ratio  of  the 
whole  power 
and  effect. 

Ratio  of  pow- 
er of  the 
wheel  and 
effect. 

Mean 

Ratio. 

Jnch. 

lb. 

lb. 

i 

27 

30 

19 

64 

810 

720 

556 

10  : 6-9 

10  : 7-7 

2 

27 

56-| 

16! 

144 

1530 

1360 

1060 

10  : 6-9 

10  : 7-8 

3 

27 

56| 

20$ 

12! 

1530 

1360 

1167 

10  : 7-6 

10  : 8-4 

s 

4 

27 

63! 

20! 

13! 

1710 

1524 

1245 

10  : 73 

10  : 8-2 

5 

27 

76§ 

21! 

15! 

2070 

1840 

1500 

10  : 7-3 

10  : 8-2 

0) 

6 

28! 

73| 

18$ 

17! 

2090 

1764 

1476 

10  : 7- 

rR 

00 

O 

ca 

7 

28jr 

96$ 

20$ 

20! 

2755 

2320 

1868 

10  : 6-8 

10  : 8- 

o 

8 

30 

90 

20 

19! 

2700 

2160 

1755 

10  : 6-5 

10  : 8T 

Cl 

GO 

9 

30 

96§ 

20$ 

204 

2900 

2320 

1914 

10  : 6-6 

10  : 8-2 

10 

30 

113! 

21 

23! 

3400 

2720 

2221 

10  : 6 5 

10  : 8-2 

o 

11 

33 

56§ 

20$ 

13! 

1870 

1360 

1230 

10  : 66 

10  : 9- 

> a 
00 

12 

33 

106§ 

22$ 

214 

3520 

2560 

2153 

10  : 6T 

10  : 8-4 

13 

33 

146§ 

28 

274 

4840 

3520 

2846 

10  : 5-9 

10  : 8T 

O 

14 

35 

65 

19$ 

164 

2275 

1560 

1466 

10  : 6-5 

10  : 9-4 

JO 

15 

35 

120 

214 

254 

4200 

2880 

2467 

10  : 5-9 

10  : 8-6 

16 

35 

163! 

25 

26! 

6728 

3924 

2981 

10  : 5-2 

10  : 7 6 

o 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

From  this  table  we  perceive  the  small  effects  produced  by  an  increase  of  the  head  A c — li  above 
the  wheel.  On  the  general  results,  he  observes,  that  “ the  power  of  the  water  computed  from  the 
height  of  the  wheel  only,  appears  to  observe  a more  constant  ratio”  than  that  between  the  power  of 
the  water  reckoned  from  the  whole  descent  and  the  ultimate  effect.  Thus  the  ratios  in  column  9 differ 
from  that  of  10  : 7-6  to  10  : 5'2  ; whereas,  taking  the  mean  set  down  in  column  11,  “we  find  the  ex- 
tremes to  differ  no  more  than  from  the  ratio  of  10  : 8T  to  10  : 8'5  ; and  as  the  second  term  of  the  ratio 
gradually  increases  from  8T  to  8‘5,  by  an  increase  of  head  from  8 inches  to  11  inches,  the  excess  of  8'5 
above  8T  is  to  be  imputed  to  the  superior  impulse  of  the  water  at  the  head  of  11  inches  above  that  of 
3 inches ; so  that,  if  we  reduce  8T  to  8,  on  account  of  the  impulse  of  the  3-inch  head,  we  shall  have  the 
ratio  of  the  power,  computed  upon  the  height  of  the  wheel  only,  to  the  effect  at  a maximum  as  10  : 8, 
or  as  5 to  4 nearly ; and  from  the  equality  of  the  ratio  between  the  power  and  effect,  subsisting  when 
the  constructions  are  similar,  we  must  infer  that  the  effects,  as  well  as  the  powers,  are  as  the  quantities 
of  water  and  the  perpendicular  heights  multiplied  together  respectively.” 

These  inferences  are  corroborative  of  the  principles  which  we  have  attempted  more  formally  to  illus- 
trate ; but  we  must  also  quote  his  remarks  “ concerning  the  velocity  of  the  circumference  of  the  wheel, 
in  order  to  produce  the  greatest  effect,”  as  they  are  still  frequently  appealed  to  in  justification  of  an 
erroneous  interpretation  of  a true  doctrine.  The  doctrine  is  thus  stated  by  the  author : — “ If  a body  is 
let  fall  freely  from  the  surface  of  the  head  to  the  bottom  of  the  descent,  it  will  take  a certain  time  in 
falling ; and  in  this  case  the  whole  action  of  gravity  is  spent  in  giving  the  body  a certain  velocity : but 
if  this  body  in  falling  is  made  to  act  upon  some  other  body,  so  as  to  produce  a mechanical  effect,  the 
falling  body  will  be  retarded ; because  a part  of  the  action  of  gravity  is  then  spent  in  producing  the 
effect,  and  the  remainder  only  giving  motion  to  the  falling  body : and  therefore  the  slower  a body  de • 


870 


WATER-WHEELS. 


»cends,  the  greater  will  be  the  portion  of  the  action  of  gravity  applicable  to  the  producing  a mechanical 
effect ; and  in  consequence  the  greater  that  effect  may  he. 

“ If  a stream  of  water  falls  into  the  bucket  of  an  overshot-wheel,  it  is  there  retained  until  the  wheel 
by  moving  round  discharges  it : of  consequence  the  slower  the  wheel  moves,  the  more  water  each  bucket 
will  receive ; so  that  what  is  lost  in  speed,  is  gained  by  the  pressure  of  a greater  quantity  of  water  acting 
in  the  buckets  at  once ; and,  if  considered  only  in  this  light,  the  mechanical  power  of  an  overshot-wheel 
to  produce  effects  will  be  equal  whether  it  moves  quick  or  slow : but  if  we  attend  to  what  has  been 
just  now  observed  of  the  falling  body,  it  will  appear  that  so  much  of  the  action  of  gravity,  as  is  em- 
ployed in  giving  the  wheel  and  water  therein  a greater  velocity,  must  be  subtracted  from  its  pressure 
upon  the  buckets,  so  that,  though  the  product  made  by  multiplying  the  number  of  cubic  inches  of  water 
acting  in  the  wheel  at  once  by  its  velocity  will  be  the  same  in  all  cases ; yet  as  each  cubic  inch,  when 
the  velocity  is  greater  does  not  press  so  much  upon  the  bucket  as  when  it  is  less,  the  power  of  the  wa- 
ter to  produce  effects  will  be  greater  in  the  less  velocity  than  in  the  greater : and  hence  we  are  led  to 
this  general  rule,  that  cteteris  paribus,  the  less  the  velocity  of  the  wheel,  the  greater  will  be  the  effect 
thereof." 

According  to  this  view  of  the  subject  we  ought  to  introduce  into  our  formula  a further  reduction  of  H 
depending  upon  the  velocity  of  revolution,  and  which  would  therefore  be  a function  of  v.  But  if  the 
mode  in  which  li"  has  been  obtained  be  observed,  it  will  be  found  that  the  circumstance  which  Mr. 
ijmeaton  had  in  view  is  there  included.  It  is  admitted  that  the  gravitation  of  the  fluid  in  the  buckets 
cannot  at  the  same  time  be  producing  pressure  and  velocity ; but  we  have  laid  it  down  as  a condition, 
which  Mr.  Smeaton  also  insists  upon,  that  the  water  must  have  a higher  velocity  than  the  circumference 
of  the  wheel  at  the  moment  of  its  passing  into  the  buckets.  This  condition  being  fulfilled,  it  is  then 
clear  that  as  no  additional  velocity  has  been  generated  in  the  fluid,  after  it  has  entered  the  buckets,  no 
part  of  its  power  is  thereby  consumed  below  that  level,  and  that  all  its  effect  will  be  realized  upon  the 
wheel.  In  other  words,  the  effect  of  the  volume  of  water  on  the  loaded  arc  will  be  expressed  by 
W X c D. 

This  may  be  exhibited  somewhat  more  formally,  and  as  a preliminary  step  let  it  be  required  to  prove 
that  the  weight  of  fluid  carried  in  the  loaded  arc  of  the  wheel,  from  the  level  of  c to  the  lower  level  D, 
is  equal  to  the  effort  which  would  be  exercised  by  the  weight  of  a prism  of  water  G II  placed  at  the 
extremity  of  the  dynamical  radius  O P,  the  height  of  the  prism  being  equal  to  c D,  and  the  area  of  its 
base  equal  to  the  cross-section  of  the  fluid  arc,  if  the  water  in  the  buckets  were  uniformly  distributed, 
and  formed  a continuous  arc.  To  show  that  this  is  true  statically,  it  will  be  sufficient  to  prove  that  the 
moments  of  pressure  are  in  the  two  cases  equal.  For  this  purpose  let  it  be  supposed  that  the  lengtl 
of  the  fluid  arc  is  divided  into  an  infinite  number  of  small  elementary  arcs,  such  as  m n having  a cross 
section  <r.  If  then  we  designate  by  <p  the  specific  gravity  of  the  fluid,  we  shall  have  a . m n . <p  as  the 
weight  of  the  small  arc  m n.  And  since  it  acts  vertically,  the  distance  between  the  direction  of  its  pres- 
sure and  the  centre  of  rotation  will  be  the  horizontal  line  r s.  Thus  then  we  have  as  the  moment  of  its 
pressure  a . mn  . <j>  . r s.  But  the  triangles  m n t and  rOs  are  similar ; hence  mn  . r s = 0 r . p q, 
and  therefore, 

a . m n . $ . r s =■  a . <p  . O r . p>  q. 

Now  the  sum  of  all  the  partial  moments  will  be  the  moment  of  the  entire  arc,  and  will  be  found  by 
multiplying  the  common  factor  a . <j>  . 0 r by  the  sum  of  all  the  small  heights  p q of  the  elementary 
arcs ; this  sum  is  evidently /<?  = c D ■ the  entire  moment  will  therefore  be  a . <p  . O r . c D.  But  that 
of  the  prism  G H is  manifestly  — o . f G H . 0 P ; and  since  GH  = cD  and  Or  = OP,  the  two  mo- 
ments are  equal. 

If  we  now  bring  into  view  the  dynamical  conditions  imposed  by  the  motion  of  the  wheel,  and  keep 
in  view  that  no  motion  is  communicated  to  the  water  within  the  limits  of  the  arc,  we  have  as  data  a 
pressure  applied  at  P in  the  direction  of  movement  a . <p  ■ c D,  and  a velocity  at  that  point  of  v feet  per 
second : the  force  impressed  will  therefore  be  expressed  by  a . <p  . c D . v.  And  if  q be  the  volume  ol 
water  flowing  in  a second,  with  a continuous  section  a , and  velocity  v communicated  independently  of 
the  motion  of  the  wheel,  and  acquired  before  it  reached  it,  we  have  q = <j  . v ; and  w being  the  weight 
of  the  volume  q,  we  have  besides  w = <p  . q.  Taking  the  values  of  a and  $ in  these  two  equalities,  and 
substituting  them  in  the  expression  above  of  the  force  impressed,  it  becomes 

q w 

— . — . c V . v — io  . c D, 
v q 

which  is  the  condition  we  undertook  to  demonstrate,  and  upon  which,  it  will  be  observed,  the  velocity 
of  the  wheel  has  no  influence. 

The  best  data  which  we  possess  for  determining  the  value  of  the  coefficient  m in  our  formula  of  the 
actual  efficiency  of  the  wheel  is  a table  of  experiments  furnished  by  M.  D’Aubuisson  containing  all  the 
conditions.  The  mean  of  these  cases  gives  m ='8997,  and  the  highest  value  is  '917,  and  the  lowest 
•874.  We  may,  therefore,  without  serious  error  put  m = '9.  The  other  terms  may  also  be  simplified 
for  the  purposes  of  ready  application.  Thus  the  three  terms  nh,  h',  h" , taken  together,  we  have  already 
shown,  do  not  differ  widely  from  § h ; and,  except  in  extreme  cases,  h"'  will  not  vary  more  than  be- 
tween 4 and  } of  the  diameter  of  the  wheel.  Let  us  assume  the  mean  of  these  extremes,  namely,  l-  1), 
and  substitute  these  quantities  with  a value  of  m = 0'9  in  our  formula,  it  will  then  be  reduced  to  the 
following : 

E = 0'9  W (H  — § h — 1 D), 

and  by  putting  Q = the  number  of  cubic  feet  of  water  furnished  in  a minute,  and  expressing  the  effect 
in  units  of  horse-power,  conformably  to  the  principle  before  explained,  w<“  have 

E = '0017  Q (H  — ^ h — ^ B). 


WATER-WHEELS. 


871 


As  an  example,  let  the  quantity  of  water  be  1000  cubic  feet  a minute,  and  the  fall  25  feet;  in  this  case 
the  wheel  would  be  made  about  22  feet  diameter  ; therefore  § h = 2 feet  and  ^ D = 3§  feet.  Hence, 
the  value  of  the  fall  would  be  reduced  to  25  — (3  — (-  3§)  = 19J  feet,  and  this  multiplied  by  1000  = 
19333.  Finally,  19333  X •001'?  = 32-87  horse-power. 

This  formula  may  also  be  employed  to  determine  the  volume  of  water  which  it  would  be  necessary 
to  employ,  with  a given  head,  to  obtain  any  required  amount  of  power — a problem  which  very  fre- 
quently occurs  in  practice. 

In  this  we  have  confined  our  attention  to  the  case  of  the  overshot- wheel,  on  account  of  its  being  the 
most  obvious ; but  the  same  formula  may,  by  a very  slight  modification,  be  applied  to  determine  the 
effect  of  a breech- wheel.  The  modification  referred  to  is  simply  the  replacing  of  ^-D  by  its  assumed 
equivalent  It1",  by  which  we  have 

E = -0017  Q (H  — § h — h'"). 

We  replace  h'",  because  in  wheels  of  this  kind  its  value  ought  to  be  always  less  than  in  the  overshot 
arrangements.  The  breech-wheel,  as  we  have  already  seen,  has  usually  a diameter  somewhat  greater 
than  the  height  of  the  fall ; and  as  h'"  is  proportional  to  the  diameter,  we  have  by  this  arrangement 
the  advantage  of  making  it  as  small  as  possible  within  the  limits  of  practice.  We  can,  indeed,  increase 
the  diameter  at  pleasure,  and  thereby  proportionally  increase  the  length  of  the  loaded  arc — the  grand 
source  of  power  in  the  bucketed  wheel  of  whatever  form. 

Robertson  Buchanan,  in  his  Essay  on  Water-Wheels,  has  endeavored  to  fix  the  proportion  of  the 
radius  of  the  wheel  to  the  height  of  fall  to  yield  a maximum  effect,  but  seems  to  have  left  out  of  view 
the  effect  of  the  centrifugal  force,  and  to  have  sujtposed  the  wheel  to  revolve  in  an  arc— which  is,  in- 
deed, the  usual  arrangement  now  adopted.  The  following  is  his  mode  of  calculation  : — Let  c — that 
portion  of  the  circumference  which  is  to  be  loaded  with  water — that  is,  the  portion  of  the  half  circum- 
ference below  the  point  at  which  the  water  flows  upon  the  wheel ; and  let  x — the  arc  comprehended 
between  that  point  and  the  horizontal  plane  passing  through  the  axis  of  the  wheel ; also  make  b — the 
area  of  the  stream  supplying  the  buckets.  Then  the  solid  which  represents  the  effective  force,  that  is, 

(c1  — 2 x*\ 

— J , and  this  is  to  be  the  greatest  pos- 

(p" 2 op 

sible,  or  = a maximum.  By  the  principle  of  maxima  and  minima,  this  takes  place  when  x = c 


(1  — y/  4)  or  x = 0'2929  c.  Accordingly,  the  arc  c — x must  be  a quadrant,  and  the  arc  x = 37’27°. 

From  this  it  appears  that  the  wheel  will  produce  its  greatest  effect  when  the  diameter  is  so  propor- 
tioned to  the  height  of  the  fall  that  the  water  flows  upon  the  circumference  at  a point  90°  — 37'27°  — 
52-73°  (nearly  62J-  degrees)  distant  from  the  summit  of  the  wheel. 

If  R,  then,  be  radius  of  the  wheel  to  the  extreme  edge  of  the  bucket,  and  h the  height  of  fall  meas- 
ured to  the  point  where  it  may  be  delivered  upon  the  wheel,  and  which  may  be  called  the  effective 
height,  then  we  shall  have 

R = * _ = 

1 -f-  sm  37|  1'605 


Since  sin  37i  degrees  = -305-  We  have  also  by  reduction  R = -623  li. 

The  effective  height  of  the  foil  is  less  than  the  entire  height  H by  as  much  as  is  necessary  to 
give  the  water  the  required  velocity,  which  may  be  taken  generally  at  10  feet  in  a second,  or  1-J 
feet  of  fall. 

The  French  mechanicians  calculate  a somewhat  greater  diameter  for  their  wheels  than  that  given  by 
the  foregoing  rule.  Instead  of  laying  on  the  water  at  52-J  degrees  from  the  summit,  as  is  commonly 
done  in  this  country,  they  lay  it  on  at  a distance  of  60°,  that  is,  30  degrees  above  the  horizontal  plane 

passing  through  the  axis  of  the  wheel.  Accordingly  R = — = §7i.  They  also  allow,  as  above  recom- 


mended, li  feet  of  the  fall  to  give  the  required  velocity  to  the  water. 

No  line  of  demarcation  has  yet  been  determined  to  separate  this  species  of  wheel  from  the  breast- 
wheel,  except  that  this  name  is  applied  when  the  water  is  received  upon  the  wheel  at  a greater  dis- 
tance from  the  summit  than  52|  degrees.  But  it  has  not  been  decided  when  this  rule  ought  to  be  set 
aside,  and  the  wheel  become  a breast-wheel.  A notion,  not  without  foundation,  prevails  among  mill- 
wrights that  a wheel  of  large  diameter  is  more  advantageous  than  one  of  small  diameter ; in  a wheel 
of  large  diameter  the  influence  of  the  centrifugal  force  is  less,  and  the  mass  in  motion  being  greater, 
the  movement  is  more  uniform  and  may  be  proportionally  slower,  which,  in  the  case  of  a low  fall,  is 
no  inconsiderable  advantage.  There  is,  however,  the  disadvantage  of  additional  friction  upon  the  jour- 
nals, and  which,  as  these  wheels  are  usually  very  broad,  goes  far  to  counterbalance  the  loss  arising  from 
centrifugal  force. 

As  the  question  is  therefore  entirely  one  of  practice,  and  incapable,  we  believe,  of  a theoretical  solu- 
tion, it  may  be  stated  as  an  opinion  founded  on  a good  example,  that  the  diameter  of  the  wheel,  even 
for  very  large  quantities  of  water,  may  be  made  to  conform  to  the  rule  above  given,  down  to  12  feet 
diameter.  The  example  which  we  have  in  view  is  a double  wheel  of  that  size,  using  at  least. 3000 
cubic  feet  of  water  per  minute  very  satisfactorily.  The  same  size  of  wheel  might  be  used  till  the  fall 
descends  to  about  6 feet,  when  a wheel  on  the  undershot  principle  will  be  found  less  expensive  and 
equally  efficient.  Under  these  circumstances  the  wheel  will  act  partly  by  the  impulse  and  partly  by 
the  gravity  of  the  water — that  is,  partly  as  an  overshot  and  partly  as  an  undershot  wheel ; its  effect 
may  therefore  be  ascertained  by  computing  the  effect  due  to  the  difference  of  level  between  the  surface 
of  the  water  at  the  penstock  and  the  point  where  it  strikes  the  wheel,  and  adding  the  result  to  the 
effect,  realizable  from  the  height  of  a fall  equal  to  the  difference  of  level  between  the  point  where  the 


872 


WATER-WHEELS. 


water  meets  the  circumference  of  the  wheel  and  the  level  of  the  tail-water,  and  which  may  be  calculated 
by  the  methods  above  indicated. 

Undershot-wheels. — By  undershot  we  understand  here  those  varieties  of  wheels  which  move  chiefly 
by  the  direct  impulse  of  the  fluid.  In  construction  they  differ  little  from  the  bucketed  wheel,  except 
that  the  buckets  are  replaced  usually  by  radial  floats  upon  which  the  impulse  of  the  current  is  received. 
They  are,  also,  usually  confined  in  an  arc,  below  the  level  of  the  water-line,  to  confine  and  economize 
the  motive  power;  but,  as  this  arrangement  is  also  common  to  bucketed  wheels,  especially  when  the 
fall  is  low,  it  cannot  be  regarded  as  a peculiarity.  In  this  form  of  wheel,  especially  if  the  volume  of 
water  be  considerable,  the  spider  construction  is,  however,  only  admissible  when  the  power  is  taken  off 
at  the  circumference  by  a pinion  placed  slightly  above  the  point  of  impulse  and  on  the  same  side, 
't  here  is,  then,  only  the  small  portion  of  the  sole-frame  put  on  strain  by  tension,  between  the  two  points. 
But,  wdten  the  power  is  taken  off  at  the  axis,  the  construction  ought  to  be  of  . the  more  rigid  kind,  other- 
wise the  continually  changing  direction  of  the  strain,  acting  through  a leverage  equal  to  the  radius  of 
the  wheel,  will  speedily  prove  fatal  to  the  points  of  connection,  if  in  any  degree  elastic. 

The  water  is  admitted  upon  the  wheel  by  a sluice  or  shuttle  in  its  immediate  vicinity,  as  in  the  case 
of  the  bucket-wheel.  What  has  been  stated  in  reference  to  the  loss  of  head  experienced  by  the  water 
passing  through  an  opening  in  its  course  is  therefore  applicable  in  this  case  as  before.  It  is  also  of 
moment,  both  on  theoretical  and  practical  grounds,  that  the  sluice  be  placed  as  closely  upon  the  wheel 
as  other  considerations  will  permit ; and  that  the  retaining  cheeks  of  the  aperture,  inside  of  the  sluice, 
be  slightly  contracted,  answering  to  the  natural  contraction  of  the  stream  after  passing  through  the 
orifice,  in  consequence  of  the  resistance  which  it  there  encounters.  The  sides  of  the  course  or  arc  in 
which  the  wheel  moves,  must  necessarily  be  parallel ; but,  immediately  on  passing  the  vertical  plane 
passing  through  the  axis  of  the  wheel,  the  floor  ought  to  deepen  and  the  sides  expand  and  leave  the 
water  as  much  space  to  diffuse  itself  over  as  possible.  This  arrangement  is  shown  in  Figs.  3810  and 
3811,  as  far  as  it  is  applicable  with  a sluice-framing  entirely  constructed  of  wood;  but,  when  the  cod 
struction  is  of  iron,  the  confinement  of  the  water  may  be  made  much  more  complete. 


3810. 


Supposing  the  floats  to  be  placed  radially,  their  breadth  or  depth  in  the  direction  of  the  radius  ought 
obviously  to  be  such,  that  in  the  rising  of  the  water  against  the  float  which  it  first  strikes,  the  portion 
which  tends  to  pass  over  its  superior  edge  shall  not  be  thrown  against  the  back  of  the  succeeding  float. 
Any  action  of  this  kind  would  manifestly  be  attended  with  a corresponding  diminution  of  the  effect  of 
the  wheel;  and  ought,  therefore,  to  be  avoided,  as  perhaps  the  most  serious  error  which  is  liable  to  be 
committed  in  this  form  of  wheel.  This  source  of  loss  may,  however,  be,  in  general,  entirely  avoided, 
by  giving  to  the  floats  a depth  of  about  three  times  the  thickness  of  the  lamina  of  water  acting  upon 
them*  The  thickness  of  the  lamina  is  usually  from  four  to  six  inches,  giving  the  range  of  depth  of  the 
floats  from  twelve  to  eighteen  inches.  The  velocity  with  which  the  fluid  precipitates  itself  upon  the 
floats,  ought  also  to  be  taken  into  account  in  providing  for  its  expansive  movement.  The  distance  of 
the  one  float  from  the  other,  measured  upon  the  exterior  circumference  of  the  wheel,  may  be  generally 
taken  equal  to  the  depth.  Their  number  will,  of  course,  depend  upon  the  diameter  of  the  wheel,  and 
this  is  almost  arbitrary.  W e will,  however,  endeavor  briefly  to  indicate  the  general  principle  which 
ought  to  be  kept  in  view  in  fixing  the  diameter,  without  entering  upon  any  strict  investigation  of  the 
question. 


WATER-WHEELS. 


873 


As  a consequence  of  the  general  theory  already  explained,  it  follows  that  the  dynamical  effect  of  the 
wheel  is  dependent  upon  the  relation  which  the  velocity  of  the  floats  bears  to  that  of  the  water ; but 
this  relation  is  manifestly  independent  of  the  diameter.  The  velocity  due  to  the  current  of  water  to  be 
used  is  always  an  ascertainable  quantity,  and  may  therefore  be  regarded  as  known.  Another  deter 
ruinate  element  of  the  calculation  is  the  number  of  revolutions  which  it  is  desirable  the  wheel  should 
make  in  a certain  unit  of  time,  as  a minute,  in  order  that  the  effect  may  be  transmitted  to  the  working 
points,  with  a rate  of  velocity  the  most  advantageous  for  the  particular  purposes  intended,  and  obtained 


3811. 


expressed  by 


60  u u 

= 111  1 N 


And  to  obtain  an  effect  approaching  the  maximum,  we  may  assume  u = 2-4  y H ; and  therefore  the 
diameter  expressed  in  terms  of  the  velocity  and  height  of  fall  will  be 


19T  X 


2-4  v/  H 46 

— N — = \r  V 11  vei7  nearly. 


Thus,  supposing  the  fall  to  be  6 feet,  and  the  number  of  turns  per  minute  required  to  be  10  = N; 
then  the  diameter  will  be  4k  X ,/  6 = 4 6 X 2-45  = 1 Ilf  feet  nearly.  This  is  nearly  the  minimum 
diameter  of  wheel  which  would  under  any  circumstances  be  employed;  12  feet  to  25  feet  may  indeed 
be  taken  as  the  usual  range ; but  unless  the  volume  of  water  be  extraordinarily  great — and  then  breadth 
is  better  than  diameter — we  cannot  conceive  of  any  advantage,  other  than  may  arise  from  some  pecu- 
liarity in  the  nature  of  the  machinery  to  be  impelled,  which  may  not  be  obtained  with  a diameter  of 
16  feet  to  18  feet.  It  is,  however,  to  be  observed,  that  the  smaller  the  diameter  the  greater  is  the  nicety 
of  adjustment  required  to  make  the  water  yield  its  effect  upon  the  buckets ; and  possibly  the  errors 
which  have  been  committed  in  this  particular  have  led  to  the  common  opinion  that  a wheel  of  large 
diameter  is  always  in  practice  the  most  effective. 


38 12. 


Before  the  introduction  of  Poncelet’s  system  of  curved  floats,  various  attempts  were  made  to  increase 
the  efficiency  of  the  undershot-wheel,  by  placing  the  floats  at  some  determinate  angle  with  the  circum- 
ference. And  where  the  wheel  moved  in  backwater,  and  especially  in  an  unconfined  channel,  a certain 
beneficial  effect  was  experienced.  But  in  the  ordinary  cases  of  a confined  course  or  arc,  with  proper 
provision  for  tail-water  clearance,  these  schemes  do  not  seem  to  have  been  attended  with  any  advan- 
tage. According  to  Bossut’s  experiments,  indeed,  the  result  appears  to  indicate  that  the  radial  float  is 
the  most  efficient.  Taking  the  effect  obtained  with  the  radial  float  as  unity,  the  results  which  he 
obtained  with  (he  angular  positions  noted,  arc  thus  stated: 


Angle  of  float 0°  8°  12°  16° 

Comparative  effect, 1 0 949  0 956  0’99S 


o74 


WATER-WHEELS. 


Showing  that  at  least  no  advantage  is  derived  from  feathering  the  floats,  as  it  is  denominated.  In  aa 
indefinite  volume  of  fluid,  the  case  is,  however,  different ; the  inclination  of  the  floats  favors,  not  the 
action  of  the  impelling  fluid,  but  their  disengagement.  This  is  manifest  when  it  is  observed  that  aa 
60on  as  the  radial  float  passes  into  water,  having  a less  velocity  than  its  own,  it  begins  to  be  retarded ; 
and  besides,  in  rising  to  the  surface,  it  tends  to  lift  with  it  a portion  of  the  fluid,  which,  acting  by  ita 
weight  in  the  contrary  direction  to  that  of  the  wheel,  also  proportionally  diminishes  the  useful  effect. 

This  is  sometimes  obviated  at  great  expense,  in  large  wheels  placed  in  situations  where  the  fall  is 
very  small  and  liable  to  be  flooded,  by  rendering  them  capable  of  being  raised  and  lowered  at  pleasure, 
in  conformity  with  the  state  of  the  river.  The  mechanism  for  this  purpose  is  generally  worked  by 
manual  labor ; but  sometimes  also  it  is  rendered  self-acting,  as  in  the  case  of  some  wheels  worked  by 
the  tide  in  situations  where  the  tidal  oscillations  are  considerable.  In  these  the  floats  are  usually, 
though  not  always  advantageously,  inclined  to  the  radius  to  assist  the  other  arrangements. 

Various  other  schemes  for  increasing  the  efficiency  of  impulsive  wheels  have  been  resorted  to.  One 
of  these  was  to  place  a lodging  on'  the  ends  of  the  floats  to  confine  the  action  of  the  fluid ; but  with 
very  little  beneficial  effect ; and,  it  is  obvious,  that  if  any  arrangement  of  this  kind  was  likely  to  be  ox 
advantage,  it  could  be  most  effectually  secured  by  placing  the  floats  within  slnouds,  as  in  the  common 
bucket-wheel — a form  of  construction  not  uncommon.  Another  supposed  improvement,  still  common 
in  some  parts  of  Europe,  though  never  introduced  into  this  country,  and  only  applicable  to  very 
narrow  wheels,  is  to  form  the  floats  of  cylindrical  arcs,  with  the  axis  of  the  cylinder  in  the  direction  oi 
the  radius  of  the  wheel,  and  the  concave  face  of  the  arc  opposed  to  the  motion  of  the  water.  This 
arrangement  is  stated  to  possess  certain  advantages,  but  we  cannot  conceive  that  they  can  possibly  be 
60  marked  as  to  compensate  the  additional  cost  of  construction ; and  we  must  still  believe  that  the  plain 
float  with  shrouding  is  both  the  simplest  and  most  complete  of  all  the  deviations  which  have  been  at- 
tempted, excepting,  indeed,  M.  Poncelet’s  application  of  the  curved  float,  and  even  in  this  the  advantage 
does  not  so  much  consist  in  the  form  of  the  float,  as  in  the  other  beneficial  adaptations  with  which  it  is 
associated. 

To  understand  the  action  of  the  water  upon  the  floats  of  a wheel  of  the  kind  under  discussion,  it  io 
necessary  to  observe  that  the  moment  the  sluice  is  raised,  the  fluid  precipitates  itself  against  the  first 
float  which  obstructs  its  passage,  and,  in  consequence,  an  accumulation  takes  place,  which  ultimately 
succeeds  in  putting  the  wheel  in  motion,  and  gradually  accelerates  its  velocity  until  an  equilibrium  is 
established  between  the  force  of  the  current  and  the  resistances  to  be  overcome.  In  proportion  as  the 
velocity  of  the  wheel  increases,  the  pressure  of  the  current  becomes  less,  since  this  action  is  proportional 
to  the  relative  velocities  ; and  very  soon  the  acceleration,  which  gradually  diminishes,  becomes  imper- 
ceptible, and  finally  ceases ; and  the  wheel,  after  a certain  number  of  revolutions,  in  consequence  of 
the  velocity  impressed  upon  it,  and  in  consequence  also  of  its  inertia,  continues  to  revolve  as  of  itself, 
e;ther  with  a motion  perfectly  uniform,  or  with  a velocity  oscillating  between  limits  imposed  by  the 
varying  nature  of  the  resistances,  and  which  may  be  reduced  in  effect  to  a mean  continuous  velocity 
always  ascertainable. 

Supposing  the  wheel  to  derive  its  effect  entirely  from  the  impulse  of  the  current,  and  to  obtain  no 
advantage  from  confinement  in  an  arc,  by  which  a certain  amount  of  the  weight  of  the  fluid  is  made  to 
act  in  aid  of  the  impulsive  force,  the  dynamical  effect,  considered  theoretically,  of  any  given  weight  W 
of  water  upon  a float  receding  before  the  stream  with  a velocity  of  v feet  in  a second,  is  expressed  by 

y(V  — r)  v. 

Hut  it  may  be  questioned  whether  the  same  effect  will  be  produced  upon  a suite  of  floats  presenting 
themselves  successively  to  the  current,  usually  two  and  three  at  a time,  and  under  various  angles  of  in- 
clination. On  this  point  we  derive  our  most  important  information  from  experience  ; but  admitting,  in 
the  mean  time,  that  the  action  of  the  impulse,  although  not  equal,  is  of  the  same  kind,  and  susceptible 
of  an  expression  of  the  same  form  as  that  above,  we  shall  ultimately  succeed  in  comparing  the.  results 
of  experiment  with  those  of  calculation. 

In  the  expression  above,  when  the  wheel  is  moved  by  a confined  current,  v is  the  only  variable  quan- 
tity. If  v = 0,  the  effect  is  also  cipher,  for  a machine  which  does  not  move  yields  no  power.  The  power 
will  also  be  cipher,  when  Y = v,  since,  as  before  remarked,  if  the  wheel  move  at  the  same  rate  as  the 
current,  it  can  receive  no  motive  effect  from  the  fluid.  It  is  still  more  obvious  that  v cannot  be  greater 
than  V.  The  limit  is  therefore  between  v = 0 and  v = V,  and  between  these  extremes  there  will  be  a 
maximum  of  effect.  If,  then,  we  differentiate  the  variable  part  (V  — v)  v,  and  equate  to  zero  in  the 
usual  manner,  we  have 

V d v — v d v — 0 ; whence  v — Y, 

showing  that  the  effect  of  the  wheel  is  the  greatest  possible  when  it  moves  with  half  the  velocity  of  the 
stream. 

W 

Now,  the  pressure  of  the  water  upon  the  floats  being  — (V  — v),  this  will  also  be  a measure  of  the 

resistances  (including  all  the  passive  resistances)  overcome  by  the  wheel,  since  the  moments  of  pressure 
must  obviously  be  equal  in  every  case  of  equilibrium ; hence,  if  in  this  expression  we  substitute  for  v its 
equivalent  -J-  Y,  we  have,  as  the  measure  of  the  load  when  the  dynamical  effect  is  a maximum, 

w X V 
2 9 

And  the  dynamical  effect  being  equal  to  the  load  multiplied  into  the  velocity  of  motion,  viz.,  v = $ V, 
we  have,  using  tins  last  as  the  measure  of  the  velocity  of  the  wheel. 


WATER-WHEELS. 


875 


V2 

IW  X equivalent  to  -5-  W H, 

2 9 


when  H is  put  to  denote  the  height  of  fall  due  to  the  velocity  V,  as  before  explained. 

If,  therefore,  V be  the  whole  velocity  of  the  stream,  and  H the  entire  fall  due  to  that  velocity,  thk 
result  shows  that  the  greatest  possible  effect  which  can  be  realized  from  a wheel  moved  entirely  by  the 
impulse  of  the  fluid,  is  only  half  of  the  mechanical  power  of  the  water  expended ; that  is,  considering 
both  cases  theoretically,  is  only  equal  to  half  the  effect  which  a wheel  acting  entirely  by  the  gravity  of 
the  fluid,  ought  to  realize.  But  even  this  moiety  is  subject  to  reduction,  and  can  be  only  distantly  ap 
proached  in  practice. 

We  do  not,  unfortunately,  possess  many  experiments  upon  which  we  can  implicitly  rely,  with  wheels 
of  this  kind.  We  have  many  of  a mixed  kind,  in  which  the  effects  of  impulse  and  gravity  are  combined, 
but  few  in  which  the  impulsive  action  alone  appears.  Those  of  Mr.  Smeaton,  indeed,  stand  nearly  alone 
in  importance  and  accuracy ; and,  fortunately,  they  are  complete  in  the  necessary  data.  Although  the 
model  apparatus  with  which  they  were  made  was  small,  the  well-known  accuracy  of  the  experimenter, 
and  the  purpose  for  which  the  investigation  was  undertaken,  warrants  the  confidence  which  they  have  long 
commanded.  The  wheel  was  the  same  in  diameter  as  his  overshot  model,  viz.,  2 feet,  and  was,  indeed, 
adapted  to  the  same  apparatus.  The  power  was  measured  directly  by  raising  a weight  vertically  by 
a cord  over  a pulley;  and  perhaps  the  only  objection  which  can  be  validly  urged  against  the  results, 
consists  in  his  neglecting  the  additional  friction  thereby  produced  at  the  journals  of  the  wheel.  The 
data  for  this  correction  is,  however,  furnished,  and  may  still  be  applied. 

We  subjoin  the  author’s  table  of  results,  the  columns  of  which  are  fully  explained  by  the  hcadimjt 
placed  over  them : 


6 

c*  ® 

o ‘o 

’3 

X 

Turns  of  the  wheel  un- 
loaded. 

Virtual  head  deduced 
therefrom. 

Turns  at  the  maximum. 

'p 

of 

0> 

o 

5 

| Load  at  the  maximum. 

1 

Water  expended  in  a | 
minute. 

I 

Power. 

Effect. 

Ratio  of  the  power  and 
effect. 

Ratio  of  the  velocity  of 
the  water  and  wheel. 

Ratio  of  the  load  at  the 
equilibrium,  to  the 
load  at  the  maximum. 

•sjuouiuodrj 

• ‘ 1 

i 

In. 

33 

88 

in. 

15-85 

30- 

lb. 

13 

oz. 

10 

lb.  oz. 
10  9 

275- 

4358- 

1411- 

10:3-24 

10:3-4 

10:7-75 

2 

30 

86 

150 

30- 

12 

10 

9 6 

264-7 

3970- 

1266- 

10:3-2 

10:3-5 

10:7-4 

o 

27 

82 

13-7 

28- 

11 

2 

8 6 

243- 

3329- 

1044- 

10:3-15 

10:3-4 

10:7-5 

4 

24 

78 

12-3 

27-7 

9 

10 

7 5 

235- 

2890- 

901-4 

10:3-12 

10:3"55 

10:7-53 

At 

5 

21 

75 

11-4 

25-9 

8 

10 

G 5 

214- 

2439- 

735-7 

10:3-02 

10:3-45 

10:7-32 

the 

6 , 

18 

70 

9-95 

23-5 

6 

10 

5 5 

199- 

1970- 

561-8 

10:2-85 

10:3-36 

10:8-02 

1st 

7 

15 

65 

854 

23-4 

6 

2 

4 4 

178-5 

1524- 

442-5 

10:2-9 

10:3-6 

10:8-3 

t.ole. 

8 

12 

60 

7-29 

22* 

3 

10 

3 6 

161- 

1173- 

328- 

10:2-8 

10:3-77 

10:9-1 

9 

9 

52 

5-47 

19- 

2 

12 

2 8 

134- 

733- 

213-7 

10:2-9 

10:3-65 

10:9-1 

10 

6 

42 

3-55 

16- 

i 

12 

1 10 

114- 

404-7 

117- 

10:2-82 

10:3-8 

10:9-3 

11 

24 

84 

142 

30-75 

13 

10 

10  14 

342- 

4890- 

1505- 

10:3-075 

10:3-66 

10:7-9 

12 

21 

81 

13-5 

29- 

11 

10 

9 6 

297- 

4009- 

T223- 

10:3-01 

10:3-62 

10:8-05 

13 

18 

72 

10-5 

26- 

9 

10 

8 7 

2S5- 

2993- 

975- 

10:3-25 

10:3-6 

1 0:8-7 f 

At 

14 

15 

69 

9-6 

25- 

7 

10 

6 14 

277- 

2659- 

774- 

10:2-92 

10:3-62 

10-9- 

the 

15 

12 

63 

8-0 

25* 

5 

10 

4 14 

234- 

1872- 

549- 

10:2-94 

10:3-97 

10:8-7 

2d. 

16 

9 

56 

6-37 

23- 

4 

0 

3 13 

201- 

1280- 

390- 

10:3-05 

10:4-1 

10:9-5 

17 

6 

46 

4-25 

21- 

2 

8 

2 4 

167-5 

712- 

212- 

10:2-98 

10:4-55 

10:9- 

18 

15 

72 

10-6 

29- 

ii 

10 

9 6 

357- 

3748- 

1210- 

10:3  23 

10:4-02 

10:8-0  5 

19 

12 

66 

8*75 

26-75 

8 

10 

7 6 

330- 

2887- 

878- 

10:3-05 

10:4-05 

10:8-1 

The 

20 

9 

58 

6-8 

24-5 

5 

8 

5 0 

255- 

1734- 

541- 

10:3-01 

10:4-22 

10:9-1 

3d. 

21 

6 

48 

4-7 

23-5 

3 

9 

3 0 

228- 

1064- 

317' 

10:2-99 

10:4-9 

10:9-6 

22 

12 

68 

9-3 

27- 

9 

2 

8 6 

359’ 

3338- 

1006- 

10:3-02 

10:3-97 

10:9-17 

23 

9 

58 

6-8 

26-25 

6 

2 

5 13 

332- 

2257- 

6S6- 

10:3-04 

10:4-52 

10:9-5 

4th. 

24 

0 

48 

4-7 

24-5 

3 

12 

3 8 

262- 

1231- 

385- 

10:3-13 

10:5-1 

10:9-35 

25 

9 

60 

7-29 

27-3 

6 

12 

6 6 

355- 

2588- 

785- 

10:303 

10:4-55 

10:9  45 

5th. 

26 

6 

50 

5-03 

24-6 

4 

6 

4 1 

307- 

1544- 

450- 

10:2-92 

10:4-9 

10:9-3 

27 

6 

50 

5-03 

26- 

4 

15 

4 9 

360- 

1811- 

534' 

10:295 

10:5-2 

10:9-25 

6th. 

1- 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

13. 

But  it  may  be  observed  that  several  other  columns  of  ratios  might  be  deduced  from  the  data  therein 
furnished,  and  which  would  still  further  illustrate  the  action  of  this  order  of  wheels.  The  last  column 
has  reference  to  the  aperture  at  the  sluice  for  the  admission  of  the  water  to  the  wheel.  The  holes  in 


87G 


WATER-WHEELS. 


the  scale  were  placed  diagonally,  and  to  these  a pin  was  fitted  ; so  that  when  the  pin  was  in  the  same 
hole,  the  opening  for  the  water  continued  the  same  for  all  the  experiments  of  that  series. 

From  this  table  we  find,  on  comparing  the  effect  pv  produced  at  the  maximum  with  the  product  i 
W h,  in  which  h is  the  virtual  or  effective  head,  that  the  coefficient  of  reduction  m is  very  nearly  0'64 ; 
consequently,  we  shall  have 

E or  p v = 0 C-t  X |W  /(  = 032  W h. 

The  ratio  of  p v to  W /<,  we  observe,  varies  from  0 28  to  0 32,  giving  a mean  of  0'30.  This  led  Hr. 
Smeaton  to  infer  that  one-third  of  the  force  produced  on  the  floats  by  the  current,  may  be  realized  in 
the  larger  wheels. 

If  we  compare  the  effect  realized  with  the  entire  power  of  the  water  expended,  we  find  that  the 
ratio  increases  from  0‘16  in  the  first  experiment,  when  the  total  head  was  33  inches,  to  0'25  in  the  last, 
when  the  entire  head  was  reduced  to  6 inches.  From  this  it  therefore  appears,  that  the  greatest  effect 
which  can  be  obtained  from  a given  head  of  water,  acting  impulsively,  is  between  a sixth  and  a fourth 
of  the  entire  motive  force  expended  ; and  in  the  case  of  large  wheels,  it  is  very  doubtful  whether  even 
this  last  result  can  be  obtained,  although,  as  we  have  already  seen,  theory  indicates  as  much  as  W H, 
or  double. 

The  ratio  of  the  velocity  of  the  wheel  to  that  of  the  current  gradually  augments  from  0 34  to  0'52, 
giving  a mean  of  0'43.  Mr.  Smeaton,  however,  takes  040  as  the  mean ; and  it  is  worthy  of  remark  that 
Bossut,  in  an  analogous  series  of  experiments,  also  adopted  the  same  number.  It,  however,  seems  to 
us,  from  the  nature  of  the  case,  that  the  proper  velocity  will  approximate  much  more  closely  to  the 
maximum  limit,  and  will  not  deviate  greatly  from  0 50  of  the  mean  velocity  of  the  current,  as  indicated 
by  theory.  0'45  will  at  least  be,  in  general  cases,  a safe  number  to  adopt  in  practice ; that  is, 
ti  = 045  V. 


Another  result  worthy  of  notice  is  the  weight  or  “load  at  the  equilibrium;”  that  is,  the  weight  which 
is  just  sufficient  to  keep  the  wheel  at  rest  against  the  force  of  the  current.  This,  at  an  average,  is  little 
more  than  two-tenths  greater  than  the  load  which  the  wheel  was  capable  of  carrying  when  yielding  its 
maximum  effect.  According  to  theory  it  ought  to  be  double,  for,  as  already  shown,  the  weight  corres- 


ponding to  v = 0 is 


W X v 
9 


and  that  at  the  maximum  is 


W X V 
2 9 


The  cases  to  which  these  observations  apply  are  those  in  which  the  velocity  of  the  wheel  is  adapted 
strictly  to  that  of  the  current.  But  this  is  not  always  obtained,  and  accordingly  the  coefficient  m being 
a function  of  v , fluctuates  between  extremes  which  it  is  impossible  to  comprehend  in  a general  formula. 
However,  when  the  velocity  of  the  wheel  does  not  fall  below  certain  limits — from  a third  to  two-thirds 
of  that  of  the  current — we  may,  without  much  chance  of  error,  especially  in  excess,  assume  0'60  as  the 
c* /efficient,  and  accordingly  we  shall  have  as  a general  rule, 


W 1 

E = 060  — (V  — v)v=  — — W (V  — v)  v = 1-54  Q (Y  — v ) v. 

The  velocity  Y with  which  the  water  arrives  upon  the  floats  cannot  always  be  easily  assigned.  It 
experiences  certain  losses  between  the  sluice  and  the  point  of  impulse,  but  it  is  not  perhaps  possible  to 
give  a general  expression  of  their  amount,  even  for  an  individual  case,  and  much  less  for  different  forms 
and  conditions  of  construction.  Independent  of  any  reducing  influence,  we  have  Y = V 2 g h,  in  which 
h denotes  the  difference  of  level  between  the  surface  of  the  water  in  the  lead  and  the  centre  of  percus- 
sion of  the  floats,  and  which  can  readily  be  measured.  But  from  Mr.  Smeaton's  observations  on  this 
point,  it  appears  that  the  loss  is  sometimes  as  much  as  a fifth  of  this  velocity  ; and  he  further  remarked 
that  the  difference  between  the  actual  and  calculated  velocities  diminished  as  the  vertical  opening  ol 
the  sluice  was  augmented.  In  some  instances,  indeed,  where  the  volume  of  water  was  very  great,  and 
the  head  small,  he  found  that  V hardly  differed  from  V 2 y h.  M.  Poncelet  also  remarked  the  same 
circumstance — that  the  loss  of  velocity  diminishes  with  the  magnitude  of  the  aperture  through  which 
the  fluid  issues.  Even  in  the  case  of  an  opening  of  about  8J  inches  in  height,  and  with  a head  of  4^ 
feet,  he  had  V = 0’99  V 2 g h.  This,  however,  supposes  the  sluice  to  be  constructed  to  the  best  advan- 
tage ; and  to  make  a slight  allowance  for  untoward  circumstances,  we  may  take  V =0'95  V 2 g h 
= 7'6  V h.  Substituting  this  value  of  V in  the  preceding  result,  we  have 


E = T54  Q (T6  V h — v)  v. 

And,  again,  putting  for  v its  equivalent  JY  = 3'8  V h,  this  expression  is  reduced  to  the  following  con- 
venient form, 

E = 221  Q h,  or Q h, 

’ 148 

when  expressed  in  units  of  horse-power. 

This  is  the  case  of  the  purely  impulsive  wheel ; but  in  practice  it  is  very  rarely  found  that  some 
slight  amount  of  head  cannot  be  reserved  to  act  by  its  gravity.  Under  these  circumstances  an  arc  is 
formed  concentrically  with  the  wheel  between  the  point  at  which  the  water  strikes  the  wheel,  and  the 
lowest  level  terminating  in  the  vertical  plane  passing  through  the  axis.  The  clearance  need  not  exceed 
•4  inch,  and  may,  if  the  arc  be  carefully  constructed,  be  reduced  to  ’3  inch.  To  indicate  the  effect,  let 
II,  as  before,  be  the  whole  height  of  fall ; and  let  h be  the  portion  employed  in  generating  the  required 
velocity.  After  that  the  water  has  struck  the  first  float  at  the  level  H — h it  will  afterwards  descend 
by  its  weight  through  that  height,  producing  an  effect  expressed  by  W (H  — h) ; and  the  effect  c f the 
W 

impulse  being  as  before  — ( W — v)  v,  we  shall  have  as  the  sum  of  these  partial  actions. 


WATER-WHEELS. 


877 


W {(H  — /t)+  — (V  — v)  vy 

But  we  formerly  found  in  discussing  tlie  impulsive  action  in  the  case  of  the  overshot-wheel  that 
-~(V  — v)v—  W (h  — ^h  — h’  — h"), 


in  which  the  three  quantities  h\  h"  have  the  significations  then  assigned.  We  may  therefore  make 
use  of  this  expression  as  more  definite.  It  is,  however,  in  this  case  subject  to  two  corrections  which  may 
be  thus  exhibited. 

In  the  first  place,  when  the  whole  volume  of  water  has  expended  its  impulsive  effect  upon  the  first 
float  which  it  encounters,  it  immediately  begins  to  descend  by  its  pressure  to  the  bottom  of  the  arc; 
but  let  us  observe  what  takes  place  in  the  spaces  between  the  floats  during  the  descent.  The  arc  sus- 
tains a certain  amount  of  the  pressure  of  the  fluid,  and  there  is  moreover  a certain  amount  of  clearance 
between  it  and  the  radial  extremities  of  the  floats.  A portion  of  the  fluid  will  therefore  escape  through 
this  space  without  producing  any  effect,  since  its  pressure  is  entirely  exercised  upon  the  superficies  of 
the  arc.  This  must,  consequently,  be  subtracted  from  W in  the  expression  W (H  ■ — h).  This  loss  can- 
not, indeed,  be  rigorously  assigned,  but  may  be  pretty  closely  approximated  by  considering  that  the  re- 
sistance experienced  by  this  water  against  the  face  of  the  arc  diminishes  the  velocity  which  gravity 
tends  to  give  it,  and  that  this  diminution  increases  with  its  descent:  also,  that  this  velocity  is  further 
diminished  by  the  continual  entanglements  to  which  the  water  is  subjected  by  the  varying  conditions  of 
the  intervals  between  the  floats,  and  which  likewise  become  greater  towards  the  bottom  of  the  arc ; and, 
finally,  that  the  velocity  is  altered  by  the  continual  mingling  of  the  descending  laminae,  corresponding 
to  the  several  spaces  between  the  floats  and  the  varying  positions  of  the  portions  of  fluid  therein  con- 
tained. We  may  therefore  conceive,  with  all  these  retarding  influences  in  action,  that  the  velocity  ol 
the  ineffectual  portion  will  not  differ  greatly  from  that  of  the  floats ; accordingly,  in  this  state  of  things 
if  we  denote  by  A the  cross-section  of  the  plate  of  water  falling  upon  the  wheel,  and  by  a that  correa 

ponding  to  the  intervals  between  the  extremities  of  the  floats  and  the  arc,  then  will  W ^ be  the  por 

tion  of  fluid  lost  as  regards  the  effect  of  pressure ; hence,  by  subtracting  this  from  W,  the  expression  ot 
the  effect  given  above,  we  shall  have 

W(1  «)(H-A). 

e A 

In  the  second  place,  the  portion  of  the  base  of  the  wheel  which  dips  in  the  water  contained  in  the 
lower  part  of  the  course,  loses  there  a part  of  its  weight  equal  to  the  weight  of  water  displaced.  In 
consequence  of  this  loss  the  equal  distribution  of  the  weight  of  the  wheel  about  the  axis  of  rotation  no 
longer  exists  ; and  the  wheel  tends  to  turn  in  a direction  contrary  to  that  of  the  current.  If  we  repre- 
sent by  p'  the  diminishing  influence  of  this  tendency,  this  will  be  a new  resistance  which  the  wheel  has 
to  overcome,  and  which  ought,  consequently,  to  be  added  to  these  other  resistances  of  which  the  sum 
is  p.  We  shall  then  have,  taking  m as  the  coefficient  of  reduction  of  the  results  of  calculation  to  those 
of  observation, 


(p  rf- p')v  —m  W j (H  — h)  (1 -)  -f-  h -f-  /<  /t  — /V  — A"}. 

In  practice  this  formula  may  be  considerably  simplified.  The  quantities  p'  and  1 — — , sujoposing  the 

A 


construction  judiciously  and  carefully  finished,  will  be  very  nearly  proportional  to  the  power  of  the 
wheel,  that  is,  to  W ; they  may,  consequently,  be  comprised  in  the  value  of  in.  We  have  also  before 
shown  that  the  quantity  nh-\-h'  + h"  is  always  greater  than  ^ h,  and  differs  little  in  ordinary  cases 
from  | h.  Hence  our  formula  may  be  reduced  by  these  substitutions  to  the  convenient  form, 


E = t»W  (H  — | h). 


In  this  the  indefinite  quantity  is  in,  and,  perhaps,  the  best  authenticated  experiments,  by  which  its 
value  may  be  assigned  for  the  particular  case  assumed,  are  those  of  M.  Morin,  on  a wheel  constructed 
by  Messrs.  Aitken  & Steel  for  the  crystal  works  of  Baccarat,  in  the  Department  of  Meurthe,  in  France. 
The  diameter  of  the  wheel  is  13  feet  3 inches;  its  width  parallel  to  the  axis  12  feet  94  inches;  the 
number  of  floats  32,  of  which  the  breadth  in  the  direction  of  the  radius  is  1 foot  4 inches.  The  whole 
fall  is  6 feet  9 inches,  and  the  versed  sine  of  the  arc  6'04  feet.  The  water  is  thrown  upon  the  wheel 
over  the  waste-board  of  a sluice,  of  the  same  width  as  the  wheel.  The  results  varied  with  the  thick- 
ness of  the  lamina  of  water  admitted  upon  the  wheel,  as  exhibited  in  the  table  on  the  following  page. 
From  this  table  then,  it  appears  that  m = 07  72 ; but  as  this  is  reputed  to  be  a particularly  well  con- 
structed wheel — considerably  above  the  average — we  maybe  generally  safe  in  taking  in  = 0'75,  by 
which  our  formula  is  reduced  to 

E = 0T5  W (H  — | h). 


From  the  same  table  it  appears  that  the  ratio  of  the  effect  to  the  whole  power  expended,  is  0'717  ; 
this  is  a good  result,  and  warrants  us  in  taking,  as  the  general  expression  of  effect  for  a wheel  of  ordi- 
nary character  under  like  circumstances,  0'65  W H. 

The  effect  of  curving  the  floats,  as  in  M.  Poncelet’s  wheel,  is  thus  indicated  : Supposing,  in  the  first 
place,  that  the  wheel  is  at  rest,  and  that  a film  of  fluid  arrives  horizontally  with  a velocity  V upon  the 
lower  edge  of  the  float,  in  continuing  to  advance  it  rises  along  the  curve,  and  during  its  elevation  the 
velocity  which  it  possessed  is  gradually  diminished,  and  becomes  nothing  when  it  has  attained  a height 
expressed  by  0'0155  V2.  The  velocity  is  not,  however,  lost ; it  is  simply  changed  into  gravity,  in  obe- 


378 


WATER-WHEELS. 


dience  to  which  the  fluid  immediately  begins  to  descend  upon  the  curved  surface  of  the  float,  over 
which  it  ascended,  and  quits  it  with  the  same  velocity  V,  which  it  possessed  at  the  moment  it  arrived 
upon  it.  This  velocity  is  acquired  by  falling  from  the  height  00155  V2,  and  under  the  circumstances 
we  have  supposed  to  exist,  its  direction  would  be  contrary  to  that  first  impressed  upon  the  fluid.  Let 
us  now  assume  that  the  wheel  turns  with  a velocity  of  v in  a second  at  its  periphery.  When  the  fila 
ment  of  fluid,  having  the  velocity  V,  shall  have  arrived  at  the  float,  it  will  then  have  a relative  velocity 


Velocity  of  the 
wheel  in  feet  per 
secoud. 

V. 

Ratio 

of  water  upon  the 
waste-board  of 
the  sluice. 

of  effect  to  power 
expended  VV  11 
pv 

VV  H * 

of  effect  to  virtual 
head  H — 
pv 

W (H-U/ 

7'65 

Feet. 

0-719 

0-707 

0-762 

3-83 

0-711 

0-734 

0-792 

3T8 

0-711 

0-726 

0783 

2-71 

0714 

0-720 

0-777 

2-40- 

0-714 

0-716 

0-773 

2T3 

0-718 

0-700 

0 755 

Mean. 

0-717 

0-772 

of  V — v,  and  it  will  only  be  with  this  velocity  that  it  will  commence  to  ascend  upon  the  curved  sur 
face  of  the  float;  it  will  therefore  rise  to  a height  of  only  00155  (V  — v)\  and  after  descending,  will 
quit  the  lower  edge  of  the  float  with  the  same  velocity  V — v.  Tut  this  element  will  now  have  itself 
a velocity  v in  the  contrary  direction,  for  it  partakes  of  the  motion  of  the  wheel ; the  absolute  velocity 
with  which  it  escapes  will  therefore  be  Y — (t>  -|-  v).  Consequently,  if  v — $ V,  the  absolute  velocity 
of  escape  will  be  Y — V = 0,  showing,  that  if  the  velocity  of  the  wheel  be  half  of  that  with  which  the 
water  arrives,  its  absolute  velocity  in  quitting  the  floats  will  be  nothing.  We  have,  therc-fme,  the  case 
of  a motive  current,  which  experiences  neither  shock  nor  loss  of  velocity  at  the  moment  of  impulse  upon 
the  wheel,  and  which  possesses  none  at  the  moment  it  quits  the  float ; it  has  then  expended  all  its 
movement  upon  the  wheel,  and  communicated  to  it  all  its  force.  The  two  conditions,  shown  to  be  un- 
attainable in  the  bucket  and  common  impulsive  wheels,  is  therefore  theoretically  attained  with  this 
arrangement,  so  that,  if  W be  the  weight  of  water,  and  h the  height  of  fall  due  to  the  velocity  V,  we 
shall  have  as  the  expression  of  effect  W h. 

But  although  this  may  be  nearly  true  for  a simple  film,  it  is  not  true  for  a volume  or  sheet  of  water 
of  a certain  thickness.  Those  molecules  which  strike  the  floats,  making  an  angle  more  or  less  great 
with  the  element  struck,  lose  both  a portion  of  their  velocity  and  force  ; and  at  the  moment  when  the 
mass  of  particles  quit  the  float  upon  which  they  have  expended  their  action,  their  direction  is  not  ex- 
actly opposite.  Besides,  as  with  all  wheels  which  revolve  in  an  arc,  a part  of  the  motive  fluid  escapes 
without  yielding  any  useful  effect.  We  may,  therefore,  conclude  that  the  real  effect  is  not  W h,  but 
m W h,  in  which  m is  some  fraction  less  than  1. 

A series  of  experiments  was  undertaken  by  M.  Poncelet  for  the  purpose  of  determining  this  fraction ; 
that  is,  the  ratio  between  the  actual  effect  realized  and  the  power  expended.  The  annexed  table  con- 
tains the  most  important  conclusions.  The  wheel,  it 

may  be  observed,  had  a diameter  of  11|  feet;  30  i ' ] 

floats  of  12^-  inches  depth  in  the  direction  of  the  ra-  Ratios, 

dius,  and  25  inches  breadth  between  the  shrouds.  Rise  of  sluice  ' * ' 

From  these  experiments  and  observations  M.  Poncelet  in  inches.  JL.  1[”_  . ZJL  . 

concludes : V YV  k W H 

1.  That  the  velocity  of  the  wheel  which  gives  the  “ 

maximum  of  effect  is  0'55  of  the  velocity  of  the  cur-  o..V’I  o -o  r.-o  n--- 

rent ; but  that  it  might  be  varied  from  0’5  to  0 6 with-  „ 

out  any  marked  disadvantage.  ^ g™ 

2.  That  the  dynamical  effect  is  not  under  0'7 5 W h ^74  zM>a  o.qi  n '-- 

for  low  falls  with  large  volumes  of  water,  and  may  ,,  y ^ 

be  taken  at  0‘65  W h when  the  volume  of  water  is  a ^ 

small  and  the  fall  considerable.  1 0 

3.  That  this  same  effect,  compared  with  the  entire  __ 

force  expended,  namely,  W H,  may  be  taken  at  0-60 

in  ordinary  cases,  and  at  0-50  when  the  rise  of  the  sluice  is  very  small. 

For  those  cases  which  ordinarily  present  themselves  in  practice,  and  supposing  the  wheels  constructed 
with  due  care,  and  to  be  adjusted  to  velocities  differing  little  from  '55  of  the  current,  we  may  therefore 
take 

E = 0’7 5 W h or  E = 0 60  W 11. 

Comparing  this  result  with  that  determined  for  impulsive  wheels  having  radial  floats,  it  appears  that 
the  effect  is  more  than  doubled.  This  conclusion,  to  which  we  arrive  in  both  cases  by  experimental 
guidance,  ought,  of  course,  to  decide  which  of  the  two  forms  of  wheel  ought  to  be  employed  in  genera] 


Rise  of  sluice 
in  inches. 

Ratios. 

V 

V 

P V 

Wh,  * 

p V 

WH* 

3-937 

0-46 

0-51 

0-46 

8-268 

0-52 

0-70 

0'56 

8-661 

0-60 

0-68 

0-56 

7-874 

0-52 

0-60 

0-52 

11-969 

0-69 

0-81 

0'55 

“ 

0-61 

0-74 

0'55 

0-59 

0-63 

0-52 

WATER-WHEELS. 


879 


cases.  It  is  admitted  that  M.  Poncelet’s  -wheel  involves  a more  precise  acquaintance  with  the  nature  of 
the  force  employed  than  the  common  float-wheel ; but  nothing  beyond  the  application  of  a few  rules, 
which  any  millwright  may  readily  comprehend  and  apply.  These  have  in  part  been  given  in  our  de- 
scription of  Figs.  3810  to  3812.  The  extreme  and  interior  circles  of  the  shrouds  being  drawn  such, 
that  o k = i the  effective  fall  when  not  more  than  4 % feet,  the  circle  rn  n is  described  with  a radius 
determined  by  the  following  considerations.  From  the  point  k at  which  the  water  is  supposed  to  meet 
the  exterior  circumference  of  the  wheel,  draw  the  line  kp  perpendicular  to  the  direction  of  the  fluid.  It 
will  form  an  angle  of  24°  to  28°  with  the  radius.  In  that  line  take  a point  p equal  to  about  a sixth  of 
its  length  between  the  circles  of  the  shrouding,  within  the  inner  circle,  and  through  that  point  from  the 
centre  of  the  wheel  describe  the  circle  rn  n.  Then  will  p k or  p q be  the  radius  of  the  curved  float  k q ; 
and  similarly  all  the  radii  of  the  other  floats  will  terminate  in  that  circle.  Having  determined  the  num- 
ber of  floats,  and  marked  their  extremities  upon  the  external  circle  of  the  wheel,  draw  radii  from  these 
points  to  the  axial  centre,  and  upon  the  circle  mn  set  off  the  corresponding  distances  from  these  radii 
equal  to  Ip,  and  the  points  thus  found  will  be  the  centres  of  curvature  of  the  floats.  The  distance 
between  the  floats  will  be  about  half  that  recommended  when  placed  radially,  and  ought  to  be  formed 
of  sheet-iron  both  for  convenience  of  making  and  subsequent  economy  of  action. 

The  mode  of  constructing  the  arc  at  the  base  of  the  wheel  has  been  explained  in  describing  the 
figures  referred  to ; it  is  further  only  necessary  to  observe  that  every  care  ought  to  be  employed  to  ab- 
sorb as  little  as  possible  of  the  velocity  of  the  water  previous  to  the  moment  of  impulse,  and  to  provide 
for  its  escape  when  it  has  expended  its  force  upon  the  wheel. 

It  is  also  to  be  understood  that  this  species  of  wheel,  or,  more  correctly,  the  mode  of  supplying  the 
water,  will  not  be  economical  for  falls  of  more  than  44-  feet ; when  the  fall  exceeds  this  limit,  advantage 
ought  to  be  taken  of  its  weight  as  well  as  of  its  impulsive  force.  We  conceive,  however,  that  the  form 
of  wheel  is  itself  well  adapted  to  this  double  purpose ; but  the  water,  instead  of  issuing  from  the  undei 
pilp-o  of  the  sluice-plate,  ought  to  be  directed  over  it,  as  over  a waste-board ; and  the  height  of  the  arc 
ougnt,  at  the  same  time,  to  be  proportionally  increased. 

Wheels  which  move  in  an  indefinite  current  of  water,  as  a river,  are  usually  of  a heavier  construction 
than  those  we  have  been  considering;  but  differ  only  in  that  respect,  and  in  the  inclination. of  their 
floats,  from  the  common  impulsive  wheel.  It  is  usually  found  of  advantage  to  make  them  of  a dianie 
ter  of  15  to  20  feet,  with  12  to  16  floats,  of  which  the  best  inclination  appears  from  experiment  to  be 
30°.  Their  best  velocity — that  at  which  the  effect  is  a maximum — is  a third  of  that  of  the  current ; 
and,  under  these  conditions,  it  will  be  fouud  that  they  yield  an  effect  of  about  '006  W V2  of  the  water 
received  upon  the  area  of  the  floats — that  is,  about  jj-  W h if  /t  = 0'0155  V2.  This  result  may  seem,  at 
first  sight,  surprising,  when  it  is  remembered  that  the  effect  of  the  undershot-wheel  working  in  a con 
fined  rectilineal  course,  does  not  yield  more  than  J W h ; but  it  is  to  be  observed  that  in  this  last  we 
include  the  whole  volume  of  water  acting ; whereas,  in  the  other,  we  take  into  account  only  the  quan- 
tity received  upon  the  floats,  without  reference  to  the  large  amount  which  escapes  without  producing 
any  effect  whatever,  and  which  we  cannot  attempt  to  estimate. 

This  species  of  wheel  is  of  very  rare  occurrence  ; yet  there  are  numerous  situations  where  it  might  be 
employed  with  good  effect. 

Horizontal  Water  Wheels.  In  horizontal  water  wheels,  the  water  produces  its  effect  by  impact,  by 
pressure,  or  by  reaction,  or  by  an  union  of  these  forces,  but  never  directly  by  its  weight.  Impact  wheels 
have  plane  or  hollow  pallets  or  floats  on  which  the  water  acts  more  or  less  perpendicularly.  The  pres- 
sure wheels  have  curved  buckets  along  which  the  water  flows,  and  the  reaction  wheels  have  as  their  type 
a close  pipe  from  which  the  water  discharges  more  or  less  tangentially.  Pressure  wheels  and  reaction 
wheels  are  generally  very  similar  to  each  other  in  construction ; the  essential  difference  in  them  being 
that  in  the  former  the  ules  or  conduits  between  two  adjacent  buckets  are  not  filled  by  the  water  flowing 
thi-ough  them,  while  in  reaction  wheels  the  section  is  quite  filled. 

Impact  Wheels.  To  this  class  belong  that  variety  of  horizontal  wheels  usually  called  tub  wheels. 
They  consist  of  inclined  pallets  or  floats  on  the  inner  or  outer  periphery  of  a drum,  and  the  water  is 
laid  on  by  a short  incline  at  such  an  angle  that  it  strikes  the  float  at  right  angles.  The  inclination  of  the 
floats  is  from  60  to  70°  to  the  horizon.  This  wheel  is  extremely  simple  in  its  construction,  and  is  found 
in  all  parts  of  the  world.  In  the  older  saw  mills  it  was  almost  invariably  used  for  the  running  back  of 
the  carriage.  The  simplicity  of  its  construction  is  its  chief  recommendation : it  seldom  exceeds  in 
mechanical  effect  33J-  per  cent,  of  the  water  expended.  The  effect  of  impact  wheels  is  increased  by 
surrounding  the  buckets  with  a projecting  border  or  frame,  and  by  forming  their  surfaces  like  the  bowls 
of  spoons.  If  we  give  the  buckets  greater  length,  and  form  them  to  such  a curve  that  the  water  leaves 
the  wheel  in  nearly  a horizontal  direction,  the  water  then  not  only  impinges  on  the  bucket,  but  exerts  a 
pressure  upon  it,  and  the  mechanical  effect  is  proportionately  increased.  If  the  water  be  laid  on  with- 
out impact,  the  wheel  becomes  a pressure  wheel  solely.  Among  this  class,  though  not  strictly  within 
the  distinction  made  above  between  pressure  and  reaction  wheels,  may  be  included  most  of  the  wheels 
constructed  on  the  principle  of  the  smoke  jack,  the  discharge  being  downwards;  such  wheels  as  are  de- 
signated by  the  French  as  roues  eu  cures. 

Reaction  Wheels.  As  a solid  body  endowed  with  an  accelerated  motion,  reacts  in  an  opposite  direc- 
tion with  a force  equal  to  the  moving  force  ; so  it  is  in  the  case  of  water  when  it  issues  from  a vessel 
with  an  accelerated  motion  from  the  orifice.  If  a vessel  filled  with  water  be  suspended  by  a cord,  and 
a horizontal  aperture  be  formed  near  the  bottom,  the  vessel  is  forced  backward,  proportionately  to  the 
size  of  the  aperture  and  the  velocity  of  the  issuing  current.  The  simplest  of  all  reaction  wheels  is  what 
is  usually  termed  Barker’s  Mill ; a horizontal  tube  movable  on  an  axis,  is  furnished  with  a cross  tube 
extending  at  right  angles  across  the  bottom  of  the  upright  tube  and  connecting  with  it;  this  branch  is 
closed  at  the  ends,  and  orifices  are  formed  near  the  extremities,  one  near  each  end  of  the  tube,  on  opposite 
silks  • it  now  the  central  tube  be  filled  with  water,  the  discharge  through  the  orifice  gives  a rotarv 


880 


WATER-WHEELS. 


motion  to  the  machine,  and  if  the  supply  be  maintained,  a permanent  motion  results,  available  for  prac 
tical  purposes ; by  curving  the  arms,  and  properly  proportioning  the  capacity  of  the  tubes,  the  effect 
may  be  increased.  Reaction  wheels  have  from  time  to  time  been  popular  in  this  country  from  their 
cheapness,  hut  till  very  recently  they  have  not  been  introduced  into  the  larger  mills  from  the  defects  in 
their  construction  and  rudeness  of  workmanship. 

Among  the  first  reaction  wheels  introduced  here  were  those  patented  by  Q.  and  A.  Parker  of  Ohio, 
in  1829,  which  embodies  many  improvements  which  have  since  been  claimed  by  foreign  inventors. 

The  claims  of  the  original  patent  of  1829  which  expired  1850,  were  for  the  compound  vertical  per- 
cussion and  reaction  wheel,  for  saw'-mills  and  other  purposes,  with  two,  four,  six,  or  more  wheels  on 
one  horizontal  shaft.  The  concentric  cylinder,  with  the  manner  of  supporting  them.  The  spouts 
which  conduct  the  water  into  the  wheels  from  the  penstock,  with  their  spiral  terminations  between  the 
cylinders. 

Second,  the  improvement  in  the  reaction  wheel,  by  making  the  buckets  as  thin  at  both  ends  as  they 
can  safely  he  made,  and  the  rim  no  wider  than  sufficient  to  cover  them.  The  inner  concentric  cylinder, 
the  spout  that  directs  the  water  into  the  wheel,  and  the  spiral  termination  of  the  spout  between  cylin- 
ders. 

Third.  The  rim  and  blocks  ; planks  that  form  the  apertures  in  the  wheel,  and  the  manner  of  form- 
ing the  apertures.  The  conical  covering  on  the  blocks,  with  cylinder  or  box  in  which  the  shaft  runs, 
and  the  hollow  or  box  gate,  in  any  form,  either  cylindrical,  square,  rectangular  or  irregular. 

Another  patent  was  issued  to  Messrs.  Parker  for  improvements  in  water  wheels,  June  27,  1810,  which 
expired  June  27,  1854.  The  claim  is,  the  placing  of  the  said  wheel,  or  wheels  analogous  thereto  in 
their  construction  and  mode  of  operation,  within  air  or  water-tight  cases  or  boxes  denominated  drafts, 
substantially  in  the  manner,  and  for  the  purpose  set  forth. 

It  will  be  observed  that  in  the  first  patent,  the  wheels  are  placed  vertically;  this  is  a convenient  form 
of  application  to  saw-mills ; the  shaft  of  the  wheel  being  used  as  the  crank  shaft,  connected  directly 
with  the  saw  gate.  For  most  other  applications  the  horizontal  wheel  is  more  suitable,  and  is  most 
economical  in  the  use  of  water. 

The  varieties  of  reaction  wheels  at  present  in  operation  throughout  the  country  are  innumerable,  dif- 
fering in  the  form  of  floats,  of  guides,  and  of  discharge.  Among  the  most  prominent  are  the  Foumev- 
ron  and  Jouval  Turbine,  and  the  Whitelaw  reaction  wheel. 

Fourneyron's  Turbine.  Fig.  3813  represents  a general  vertical  section  of  the  entire  machine,  showing 
its  internal  construction.  Fig.  3814  is  a half  vertical  section,  on  an  enlarged  scale,  of  the  turbine  and 
crown,  showing  the  mode  in  which  these  are-fixed  to  their  respective  centres,  and  exhibiting  distinctly 
the  manner  in  which  the  sluice-cylinder  operates.  Fig.  3815  is  a quarter  plan  of  the  same  parts  as  the 
above,  with  the  sluice-cylinder  and  top  plate  of  the  turbine  removed,  in  order  to  exhibit  the  form  and 
relative  disposition  of  the  partition-plates  of  the  turbine,  and  the  direction-plates  of  the  crown. 

In  1834  M.  Fourneyron  received  the  prize  of  6,000  francs  offered  by  the  Society  for  the  Encourage- 
ment of  the  Arts  at  Paris,  for  the  construction  of  the  best  horizontal  wheel  on  the  large  scale.  This 
was  his  first  turbine  erected  at  Pont,  on  the  Oguon.  In  consequence  of  this  decision  the  turbine  excited 
great  attention  and  discussion  among  the  continental  savans  ; and  it  must  be  remarked,  that  matters  of 
practical  utility  are  more  subjects  of  interest  among  scientific  men,  especially  in  France,  than  elsewhere, 
where  every  thing  of  a technical  character  is  considered  to  belong  exclusively  to  the  workshop. 


In  an  elaborate  report  of  this  machine  submitted  to  the  Academy  of  Sciences  of  Paris  by  M.  Ponce- 
let,  it  is  stated  that  the  essential  quality  of  the  turbine  consists  in  its  high  velocity,  and  its  capability  of 
working  under  water  without  much  loss  of  effect.  The  expedient  of  bringing  the  water  horizontally 
over  all  the  interior  circumference  of  the  wheel,  and  of  making  it  issue  through  the  greater  exterior 


WATER-WHEELS. 


SSI 


circumference,  allows  also  a large  expenditure  of  power  with  a machine  of  very  moderate  diameter. 
Finally,  it  operates  favorably  under  almost  any  fall,  and  at  any  velocity,  without  suffering  any  reduction 
of  its  effect  from  the  hydrostatic  pressure  of  the  water,  and  which  is  stated  to  be  a source  of  great  in- 
convenience in  wheels  of  this  class. 

The  peculiar  character  of  the  machine  is  sufficiently  explained  in  the  description  of  the  figures  re 
ferred  to,  and  which  are  supposed  to  represent  one  of  the  inventor's  most  successful  applications  of  his 
principle ; but,  in  order  to  bring  the  value  and  relation  of  the  forces  more  closely  into  view,  the  action 
of  the  water  may  be  here  briefly  indicated.  Supposing  the  annular  sluice  to  be  so  far  let  down  as  en- 
tirely to  close  the  spaces  d,  which  form  the  communication  between  the  interior  cistern  b and  the  chan- 
nels c of  the  revolving  disk  e,  which  is  the  turbine,  properly  so  called,  if  the  sluice  between  the  reser- 
voir and  the  supply-pipe  a be  opened,  the  water  will  precipitate  itself  into  the  cistern  b and  entirely 
“fill  it.  The  pressure  on  the  interior  of  this  cistern,  as  well  as  on  the  annular  sluice  at  the  orifices^}, 
will  be  in  proportion  to  the  depth  from  the  higher  level  of  the  water,  and,  therefore,  for  a unit  of  are.-, 
of  the  surface  acted  upon,  the  pressure  will  be  directly  as  the  height  H.  If,  then,  the  sluice  be  raised, 
the  water  rushes  into  the  channels  c with  the  velocity  due  to  the  head  of  pressure,  and  in  the  direction 
prescribed  by  the  guide-curves,  and  impinging  against  the  diaphragms  of  the  channels  c causes  the 
disk  e to  revolve  in  a direction  opposite  to  the  direction  of  impulse,  and  finally  escapes  by  the  external 
extremities  of  the  channels  at  the  greater  circumference  of  the  turbine-disk. 

The  lower  divisions  of  the  sluice-ring,  it  may  be  remarked,  are  considerably  increased  in  thickness, 
and  rounded  to  avoid  the  contraction  of  the  veins  of  fluid  issuing  into  the  channels  c,  and  which  would 
take  place,  if  no  provision  were  made  for  correcting  the  oblique  motions  impressed,  when  the  water  is 
projected  through  the  apertures  at  the  extremities  of  the  guide-curves  in  a horizontal  direction. 

The  construction  of  the  machine  depends  upon  the  application  of  a few  fundamental  principles.  Like 
all  other  hydraulic  motors,  its  size  ought  to  be  proportioned  to  the  effect  which  it  is  intended  to  pro- 
duce— that  is,  in  effect  to  the  quantities  W or  Q and  H.  Thus  the  interior  diameter  D,  one  of  the  prin- 
cipal dimensions,  is  directly  as  the  ratio  of  these  two  quantities  ; and  as  the  turbine  ought  to  be  capable 
of  expending  the  volume  of  water  Q,  arriving  to  it  with  the  velocity  V,  the  orifices  must  have  an  area, 
determined  from  the  condition  Q = A Y,  in  which  we  denote  by  A the  sum  of  the  orifices  of  admission. 
On  the  water  arriving  in  the  same  time  upon  all  the  whole  interior  circumference  of  the  turbine,  A will 
be  equal  to  that  surface,  (after  subtracting  the  area  occupied  by  the  thicknesses  of  the  diaphragms),  and, 
consequently,  will  be  equal  to  rr  D d,  in  which  d denotes  the  depth  of  the  courses.  The  proportion 
fixed  by  M.  Fourneyron,  is  d—  ] D ; and,  therefore,  by  making  this  substitution,  we  shall  have 

A = | it  D2  = 0-45  D2. 

But  Q = A V - 0 45  D2  Y. 

x\nd  V = 6 60  y/  H therefore  Q = 3 D2  y/  H 


From  this  we  have  the  diameter  D = 


V 3 y/  II 


This  value  of  D ought,  according  to  the  views  of  the  inventor,  to  be  further  affected  by  a coefficient, 
to  allow  for  the  entanglements  which  the  fluid  experiences  in  the  cylinder  and  in  entering  the  turbine, 
and  for  the  effect  of  the  obliquity  with  which  the  water  is  thrown  by  the  diaphragms  upon  the  moving 
circumference.  This  coefficient  being  introduced  according  to  the  practice  of  M.  Fourneyron,  we  have 


It  is  here  assumed  that  Q is  the  greatest  volume  of  water  which  the  machine  is  capable  of  discharg- 
ing ; but  it  is  to  be  understood,  that  smaller  quantities  may  be  employed,  and  that  the  machine  is 
capable  of  working  with  almost  any  less  quantity  without  losing  any  remarkable  amount  of  its  pro- 
portional efficiency. 

The  diameter  D may  thus  be  taken  as  a function  of  the  power  of  the  machine,  that  is,  of  E,  the 
dynamical  effect  in  units  of  horse-power.  Now,  assuming  the  machine  to  realize  15  per  cent,  of  the 
power  which  it  expends,  and  that  <4  is  the  volume  of  water  supplied  in  1 minute,  we  have 


E 


QH 
700  ‘ 


Hence,  Q 


700  E 
H 


And,  substituting  this  value  of  Q in  the  expression  for  D above  given,  it  becomes 


D = l-3 


700  E 

hTh 


35 


E 

h71' 


The  exterior  diameter,  in  the  practice  of  M.  Fourneyron,  varies  from  I2D  to  1-44D.  For  turbines  of 
large  diameter,  6 feet  and  upwards,  the  first  of  these  coefficients  is  taken,  and  for  smaller  diameters, 
the  last. 

The  number  of  channels,  of  course,  also  varies  as  the  diameter,  but  not  proportionally.  In  the  rules 
published  by  the  iuventor,  36  is  given  as  a constant  number  with  the  same  number  of  guide-curves  on  the 
interior  disk  ; but  in  some  of  the  machines  of  later  construction  these  numbers  are  reduced.  D’Aubuisson 
mentions  turbines  which  he  has  examined  having  as  few  as  18  channels  with  from  16  to  9 guide-curves. 
Jariez  gives  the  following  rule  for  the  number  :■ — Divide  the  interior  circumference  by  the  height  d,  and  the 
quotient  number  which  results  is  the  number  of  channels  in  the  turbine.  If  this  number  be  comprised 
between  18  and  24,  its  half  represents  the  number  of  fixed  guide-curves;  if  it  be  greater  than  24,  thee 
Yol.  II. — 56 


WATER-WHEELS. 


882 


ii  third  of  it  'trill  be  the  number  of  these  fixed  compartments.  It  is,  however,  easy  to  perceive  that  this 
rule  must  only  be  a distant  approximation  ; but  even  an  approximation  is  better  than  no  rule  where 
theory  seems  insufficient  to  determine  the  question.  The  number,  according  to  Prof.  Ruhlmau,  depends 
principally  upon  the  available  quantity  of  water ; they  must  be  greater  as  more  water  is  discharged  in 
a given  time.  In  any  case,  a large  number  of  channels  is  an  advantage,  when  they  are  formed  of  thin 
sheets,  as  thereby  a greater  number  of  filaments  of  water  act  directly  upon  their  surfaces,  and  not  in- 
directly through  a mass  of  other  water  interposed. 

We  have  above,  following  the  rules  laid  down  by  M.  Fourneyron,  giving  the  depth  of  the  channels  as 
a seventh  of  the  inside  diameter  of  the  turbine ; but  when  the  sluice  is  raised  only  a small  part  of  this 
height,  as  it  must  be  at  times  when  the  supply  of  water  is  scarce,  the  effect  is  not  only  absolutely  less  : 
it  is  relatively  so  on  account  of  the  water  losing  a portion  of  its  force  in  diffusing  itself  over  too  much 
space.  'To  avoid  this,  M.  Fourneyron,  in  some  of  his  last  constructed  machines,  has  divided  the  turbine, 
as  before  intimated,  horizontally  into  two  or  three  stages,  by  means  of  thin  plates  of  sheet-iron  placed 
in  the  channels. 

The  curvature  of  the  water  channels  of  the  turbine 
and  of  the  guide-curves  in  the  fixed  crown,  may  be 
determined  by  the  following  mode.  Describe  the  in- 
terior circumference  with  radius  o a = D,  found  as 
above  directed  ; also  the  external  or  greatest  circum- 
ference of  the  turbine  with  radius  o G = l-4  D.  These 
circumferences  being  described,  draw  a h making  sin 
Y 

it  a o = From  the  centre  o draw  o d,  making:  with 

2 v ’ ° 

a o an  angle  doa  = dav,  and  from  the  point  e,  where 

0 d cuts  the  circle  representing  the  tube  or  pipe 
through  which  the  spindle  of  the  turbine  ascends, 
take  e b parallel  to  o a ; from  b draw  b c perpendicu- 
lar to  a d,  and  from  d draw  dc  perpendicular  to  e b ; 
the  point  c where  these  two  perpendiculars  meet  will 
lie  the  centre  of  the  fixed  or  guide-curve  e dba. 

To  find  the  curve  of  the  vertical  diaphragm  a I of  the  turbine,  draw  ap  a tangent  to  the  point  a ; and 
let  ap  and  a h be  proportional  to  the  velocities  v and  V of  the  turbine  and  water: -the  diagonal  a q of 
the  parallelogram  constructed  upon  these  two  lines  will  be  the  direction  of  the  first  element  of  the 
curve.  Prolong  a q to  G,  making  a G perpendicular  to  a L,  which  is  p a prolonged  indefinitely,  cutting 
m K the  exterior  circumference  of  the  turbine-disk.  The  point  I at  which  the  extremity  of  the  curve 
terminates,  is  2-oth  of  G K.  The  two  extreme  points  being  thus  found,  the  curvature  i3  determined  as 
follows : — From  the  point  K as  a centre,  and  with  a radius  I K,  describe  the  arc  of  a circle  I i , and  pro- 
long indefinitely  the  right  line  I K.  Measure  the  line  a i,  with  any  scale  of  equal  parts,  and  divide  the 
number  expressing  its  length  by  1 — cos  M K L,  and  the  quotient  number  of  this  division,  taken  in  units 
of  the  same  kind  as  a i,  will  express  the  length  K M.  From  this  point  M draw  M L perpendicular  tc 
K L ; divide  M L into  any  number  of  parts  as  m,  m as  many  as  convenient,  and  the  more  the  bet- 

ter ; from  each  of  these  points  draw  a straight  line  passing  through  the  point  K,  and  with  the  length 

1 M in  the  compasses  mark  off  equal  distances  from  the  points  in on  their  prolongations  beyond  K. 

aud  the  points  thus  marked  off  will  be  points  in  the  curve  a I,  which  may  accordingly  be  traced  through 
them. 

* The  attention  of  American  engineers  was  directed  to  the  improved  reaction  water-wheels  in  use  in 
France  and  other  countries  in  Europe,  by  several  articles  in  the  Journal  of  the  Franklin  Institute  ; and 
in  the  year  1843,  there  appeared  in  that  journal,  from  the  pen  of  Mr.  Elwood  Morris,  an  eminent  engi- 
neer of  Pennsylvania,  a translation  of  a French  work,  entitled  “Experiments  on  Water-Wheels  having 
a Vertical  Axis,  called  Turbines,  by  Arthur  Morin,  Captain  of  Artillery,”  etc.  In  the  same  journal, 
Mr.  Morris  also  published  an  account  of  a series  of  experiments,  by  himself,  on  two  turbines  constructed 
from  his  own  designs,  and  then  operating  in  the  neighborhood  of  Philadelphia.  The  experiments  on 
one  of  these  wheels,  indicate  a useful  effect  of  seventy-five  per  cent,  of  the  power  expended,  a result  as 
good  as  that  claimed  for  the  practical  effect  of  the  best  overshot-wheels. 

BOYDEN’S  TURBINE.*  In  the  year  1844,  Uriah  A.  Boyden,  Esq.,  an  eminent  hydraulic  engineer 
of  Massachusetts,  designed  a turbine  of  about  seventy-five  horse-power,  for  the  Picking  House  of  the 
Appleton  Company’s  cotton-mill,  at  Lowell,  in  Massachusetts,  in  which  wheel,  Mr.  Boyden  introduced 
several  improvements  of  great  value.  The  performance  of  the  Appleton  Company’s  turbine,  was  care- 
fully ascertained  by  Mr.  Boyden,  and  its  effective  power  exclusive  of  that  required  to  carry  the  wheel 
itself,  a pair  of  bevel  gears,  and  the  horizontal  shaft  carrying  the  friction  pulley  of  a Prony  dynamom- 
eter-, was  found  to  be  seventy-eight  per  cent,  of  the  power  expended.  In  the  year  1846,  Mr.  Boyden 
superintended  the  construction  of  three  turbines  of  about  one  hundred  and  ninety  horse  power  each, 
for  the  same  company.  By  the  terms  of  the  contract,  Mr.  Bovden’s  compensation  depended  upon  the 
performance  of  the  turbines,  and  it  was  stipulated  that  two  of  them  should  be  tested.  The  mean  max- 
imum effective  power  of  the  two  turbines  tested,  was  eighty-eight  per  cent,  of  the  power  of  the  water 
expended. 

The  principal  points  in  which  one  of  them  differs  from  the  constructions  of  Fourneyron  are  as  follows. 

The  wooden  flume,  conducting  the  water  immediately  to  the  turbine,  is  in  the  form  of  an  inverted 
truncated  cone,  the  water  being  introduced  into  the  upper  part  of  the  cone,  on  one  side  of  the  axis  of 
the  cone  (which  coincides  with  the  axis  of  the  turbine)  in  such  a manner,  that  the  water,  as  it  descends 


3613. 


* Lowell  Hydraulic  Experiments.  J.  B.  Francis. 


WATER-WHEELS. 


883 


in  the  cone,  has  a gradually  increasing  velocity,  and  a spiral  motion ; the  horizontal  component  of  the 
spiral  motion  being  in  the  direction  of  the  motion  of  the  wheel.  This  horizontal  motion  is  derived  from 
the  necessary  velocity  with  which  the  water  enters  the  truncated  cone  ; and  the  arrangement  is  such 
that,  if  perfectly  proportioned,  there  would  be  no  loss  of  power  between  the  nearly  still  water  in  the 
principal  penstock  and  the  guides  or  leading  curves  near  the  wheel,  except  from  the  friction  of  the  water 
against  the  walls  of  the  passages. 

The  guides  or  leading  curves  are  not  perpendicular,  but  a little  inclined  backwards  from  the  direction 
of  the  motion  of  the  wheel,  so  that  the  water,  descending  with  a spiral  motion,  meets  only  the  edges  of 
the  guides.  This  leaning  of  the  guides  has  also  another  valuable  effect. ; when  the  regulating  gate  is 
raised  only  a small  part  of  the  height  of  the  wheel,  the  guides  do  not  completely  fulfil  their  office  of  di- 
recting the  water,  the  water  entering  the  wheel  more  nearly  in  the  direction  of  the  radius,  than  when 
the  gate  is  fully  raised ; by  leaning  the  guides,  it  will  be  seen  that  the  ends  of  the  guides,  near  the 
wheel,  are  inclined,  the  bottom  part  standing  further  forward,  and  operating  more  efficiently  in  directing 
the  water,  when  the  gate  is  partially  raised,  than  if  the  guides  were  perpendicular. 

In  Fourneyron’s  constructions,  a garniture  is  attached  to  the  regulating  gate,  and  moves  with  it,  for 
the  purpose  of  diminishing  the  contraction ; this,  considered  apart  from  the  mechanical  difficulties,  is 
probably  the  best  arrangement.  In  the  Appleton  Turbine,  the  garniture  is  attached  to  the  guides, 
the  gate  (at  least  the  lower  part  of  it)  being  a simple  thin  cylinder.  By  this  arrangement,  the  gate 
meets  with  much  less  obstruction  to  its  motion  than  in  the  old  arrangement,  unless  the  parts  are  so  loose- 
ly fitted  as  to  be  objectionable  ; and  it  is  believed  that  the  coefficient  of  effect,  for  a partial  gate,  is  pro- 
portionally as  good  as  under  the  old  arrangement. 

On  the  outside  of  the  wheel  is  fitted  an  apparatus,  named  by  Mr.  Boyden  the  diffuser.  The  object 
of  this  extremely  interesting  invention,  is  to  render  useful  a pai-t  of  the  power  otherwise  entirely  lost,  in 
consequence  of  the  water  leaving  the  wheel  with  considerable  velocity.  It  consists,  essentially,  of  two 
stationary  rings  or  discs,  placed  concentrically  with  the  wheel,  having  an  interior  diameter  a very  little 
larger  than  the  exterior  diameter  of  the  wheel ; and  an  exterior  diameter  equal  to  about  twice  that  of 
the  wheel ; the  height  between  the  discs,  at  their  exterior  circumference,  is  a very  little  greater  than 
that  of  the  orifices  in  the  exterior  circumference  of  the  wheel,  and  at  the  exterior  circumference  of  the 
discs,  the  height  between  them  is  about  twice  as  great  as  at  the  interior  circumference  ; the  form  of 
the  surfaces  connecting  the  interior  and  exterior  circumferences  of  the  discs,  is  gently  rounded,  the  first 
elements  of  the  curves,  near  the  interior  circumferences,  being  nearly  horizontal.  There  is,  consequent- 
ly. included  between  the  two  surfaces,  an  aperture  gradually  enlarging  from  the  exterior  cirumference 
of  the  wheel,  to  the  exterior  surface  of  the  diffuser.  When  the  regulating  gate  is  raised  to  its  full 
height,  the  section,  through  which  the  water  passes,  will  be  increased  by  insensible  degrees,  in  the  pro- 
portion of  one  to  four,  and  if  the  velocity  is  uniform  in  all  parts  of  the  diffuser  at  the  same  distance 
from  the  wheel,  the  velocity  of  the  water  will  he  diminished  in  the  same  proportion;  or  its  velocity  on 
leaving  the  diffuser,  will  he  one-fourth  of  that  at  its  entrance.  By  the  doctrine  of  living  forces,  the 
power  of  the  water  in  passing  through  the  diffuser  must,  therefore,  be  diminished  to  one-sixteenth  of  the 
power  at  its  entrance.  It  is  essential  to  the  proper  action  of  the  diffuser,  that  it  should  be  entirely  un- 
der water ; and  the  power  rendered  useful  by  it,  is  expended  in  diminishing  the  pressure  against  the 
water  issuing  from  the  exterior  orifices  of  the  wheel ; and  the  effect  produced,  is  the  same  as  if  the 
available  fall  under  which, the  turbine  is  acting,  is  increased  a certain  amount.  The  action  of  the  diffu- 
ser depends  upon  similar  principles  to  that  of  diverging  conical  tubes,  which,  when  of  certain  propor- 
tions, it  is  well  known,  increase  the  discharge.  Experiments  on  the  same  turbine,  with  and  without  a 
diffuser,  show  a gain  in  the  coefficient  of  effect  due  to  the  latter,  of  about  three  per  cent. 

Suspending  the  wheel  from  the  top  of  the  vertical  shaft,  instead  of  running  it  on  a step  at  the  bottom. 
This  had  been  previously  attempted,  but  not  with  such  success  as  to  warrant  its  general  adoption. 

The  manner  adopted  by  Mr.  Boyden  is  fully  illustrated  in  the  accompanying  plates. 

TURBINE  WHEEL.  Plate  VIII.  is  a vertical  section  through  the  centre  of  a turbine  wheel,  and 
the  axis  of  the  supply  pipe.  Plate  XI.  is  a plan  of  the  turbine  and  wheelpit.  Fig.  3810  is  a plan  of 
the  whole  wheel,  the  guides  and  garniture.  This  turbine  was  constructed  for  the  Tremont  Manufactur- 
ing Co.  at  Lowell,  by  Mr.  James  B Francis,  and  contains  most  of  Mr.  Boyden’s  improvements.  Its  ex- 
penditure of  water,  under  13  feet  head  and  fall,  is  about  139  cubic  feet  per  second,  and  its  ratio  of  use- 
ful effect  to  the  power  expended,  about  79  per  cent. 

B,  the  surface  of  the  water  in  the  wheelpit,  represented  at  the  lowest  height  at  which  the  turbine  is 
intended  to  operate.  C,  the  masonry  of  the  wheelpit.  D,  the  floor  of  the  wheelpit.  To  resist  the 
great  upward  pressure  which  takes  place  when  the  wheelpit  is  kept  dry  by  pumps,  three  cast-iron  beams 
are  placed  across  the  pit,  the  ends  extending  about  a foot  under  the  walls  on  each  side ; on  these  are 
laid  thick  planks,  which  are  firmly  secured  to  the  cast-iron  beams  by  bolts.  To  protect  the  thick  plank- 
ing from  being  worn  out  by  the  constant  action  of  the  water,  they  are  covered  with  a flooring  of  one 
inch  boards.  E,  the  wrought-iron  supply  pipe.  This  is  constructed  of  plate  iron  three-eighths  of  an 
inch  thick,  riveted  together.  The  supply  pipe  is  furnished  with  the  man  hole  and  ventilating  pipe  G, 
and  the  leak  box  II,  to  catch  the  leakage  of  the  head  gate,  whenever  it  is  closed  for  repairs  of  the 
wheel. 

The  lower  end  of  the  supply  pipe  is  formed  by  the  cast-iron  curbs  III.  The  curbs  are  supported 
from  the  wheelpit  floor  by  four  columns,  resting  on  the  cast-iron  beam  0 ; the  beams  N',  rest  immedi- 
ately upon  the  columns,  and  the  curb  upon  the  beams,  the  latter  projecting  over  the  columns  far  enough 
for  that  purpose.  The  beams  N'  also  act  as  braces  from  the  wheelpit  wall  to  the  curb,  and  are  strongly 
bolted  at  each  end. 

K,  the  disc.  This  is  of  cast-iron,  and  is  turned  smooth  on  the  upper  surface,  and  also  on  its  circum- 
ference. It  is  suspended  from  the  upper  curb  I,  by  means  of  the  disc  pipes  M M.  The  disc  carries  on 
its  upper  surface,  thirty-three  guides,  (fig.  3816,)  for  the  purpose  of  giving  the  water  entering  the  wheel 


8S4  WATER-WHEELS. 


--C3 


WATER-WHEELS. 


885 


proper  directions.  They  are  made  of  Russian  plate  iron,  one-tenth  of  an  inch  in  thickness,  secured  to 
the  disc  by  tenons,  riveted  on  the  under  side.  The  upper  corners  of  the  guides,  near  the  wheel,  are 
connected  by  the  garniture  L,  which  is  intended  to  diminish  the  contraction  of  the  streams  entering  the 
wheel,  when  the  regulating  gate  is  fully  raised.  The  garniture  is  composed  of  thirty-three  pieces  of 
cast-iron,  carefully  fitted  to  fill  the  spaces  between  the  guides ; they  are  strongly  riveted  to  the  guides 
and  to  each  other. 

The  upper  flange  of  the  disc  pipe  is  furnished  with  adjusting  screws,  by  which  the  weight  is  support 
ed  upon  the  upper  curb.  The  escape  of  water  between  the  upper  curb  and  the  upper  flange  of  the  disc 
pipe,  is  prevented  by  a band  of  leather  on  the  outside,  which  is  retained  in  its  place  by  the  wrought- 
iron  ring  P.  The  top  of  the  disc  pipe,  just  below  the  upper  flange,  has  two  wings,  fitting  into  recesses 
in  the  top  of  the  curb,  to  prevent  the  disc  from  rotating  in  the  opposite  direction  to  the  wheel. 

R,  R,  the  regulating  gate.  Represented  Plate  XI.  as  fully  raised.  The  gate  is  of  cast-iron  ; the  up- 
per part  of  the  cylinder  is  stiffened  by  a rib,  to  which  are  attached  three  brackets  S 'S.  To  these  brack- 
ets are  attached  wrought-iron  rods,  by  which  the  gate  is  raised  or  lowered.  To  one  of  the  rods  is  at- 
tached the  rack  Y.  The  other  two  rods  are  attached  by  means  of  links,  to  the  levers  T T.  The  other 
ends  of  these  levers  carry  geered  arch  heads,  into  which,  and  into  the  rack  V,  work  three  pinions,  W, 
of  equal  pitch  and  size,  fastened  to  the  same  shaft,  so  arranged  that  by  the  revolution  of  the  pinion 
shaft,  the  gate  is  moved  up  or  down,  equally  on  all  sides.  The  shaft  on  which  the  pinions  are  fastened, 
is  driven  by  the  worm  wheel  X ; this  is  driven  by  the  worm  a,  either  by  the  governor  Y,  or  the  hand 
wheel  Z.  The  shaft  on  which  the  worm  a is  fastened,  is  furnished  with  movable  couplings,  which,  when 
the  speed  gate  is  at  any  intermediate  points  between  its  highest  and  lowest  positions,  are  retained  in 
place  by  spiral  springs ; in  either  of  the  extreme  positions,  the  couplings  are  separated  by  means  of  a 
lever  moved  by  pins  in  the  rack  Y ; by  this  means,  both  the  regulator  and  hand  wheel  are  prevented 
from  moving  the  gate  in  one  direction,  when  the  gate  has  attained  either  extreme  position.  If,  how- 
ever, the  regulator  or  hand  wheel  should  be  moved  in  the  opposite  direction,  the  couplings  would  catch, 
and  the  gate  would  he  moved.  The  weight  of  the  gate  is  counterbalanced  by  weights  attached  to  the 
levers  T T,  and  by  the  intervention  of  a lever  to  the  rack  V. 

b b,  the  wheel  consists  of  a central  plate  of  cast-iron,  and  two  crowns  c c,  of  the  same  material  to 
which  the  buckets  are  attached.  The  buckets  are  forty-four  in  number,  made  of  Russian  plate  iron, 
pj-  of  an  inch  in  thickness,  and  are  secured  to  the  crowns  by  grooves  cut  in  the  crowns  of  the  exact 
form  of  the  buckets,  and  by  tenons,  entered  into  the  mortises  in  both  crowns,  and  riveted  on  the  opposite 
sides. 

d d , the  vertical  shaft,  of  wrought-iron,  runs  upon  a series  of  collars,  resting  upon  corresponding  pro- 
jections in  the  suspension  box  e' . The  part  of  the  shaft  on  which  the  collars  are  placed,  is  made  sepa- 
rate from  the  main  shaft,  and  is  pinned  to  it  at  f by  means  of  a socket  in  the  top  of  the  main  shaft, 
which  receives  a corresponding  part  of  the  collar  piece.  The  collars  are  made  of  cast  steel ; they  are 
separately  screwed  on,  and  keyed  to  a wrought-iron  spindle. 

The  suspension  box  is  made  in  two  parts,  to  admit  of  its  being  taken  off  and  put  on  the  shaft ; it  is 
lined  with  Babbit  metal.  It  is  found  that  bearings  thus  lined  will  carry  from  fifty  to  a hundred  pounds 
to  the  square  inch,  with  every  appearance  of  durability. 

f'f\  the  upper  and  lower  bearings,  are  of  cast  iron,  lined  with  Babbit  metal,  adjustable  horizontally 
by  means  of  screws.  The  suspension  box  e1,  rests  upon  the  gimbal  g.  The  gimbal  itself  is  supported 
on  the  frame  h h by  adjusting  screws,  which  give  the  means  of  raising  and  lowering  the  suspension  box, 
and  with  it,  the  vertical  shaft  and  wheel.  The  lower  end  of  the  shaft  is  fitted  with  a cast-steel  pin  i. 
This  is  retained  in  its  place  by  the  step,  which  is  made  in  three  parts,  and  lined  with  case-hardened 
wrought-iron. 

The  weight  of  the  wheel,  upright  shaft,  and  bevel  geer,  is  supported  by  means  of  the  suspension  box 
e on  the  frame  k,  which  rests  upon  the  long  beams  m,  reaching  across  the  wheelpit,  and  supported  at 
the  ends  by  the  masonry,  and  also  at  intermediate  points  by  the  braces  n n. 

Mr.  Francis  deduces  the  following  rules  for  proportioning  turbines: 

The  sum  of  the  shortest  distances  between  the  buckets,  should  be  equal  to  the  diameter  of  the  wheel. 

The  width  of  the  crowns  should  be  four  times  the  shortest  distance  between  the  buckets. 

The  sum  of  the  shortest  distances  between  the  curved  guides,  taken  near  the  wheel,  should  he  equal 
to  the  interior  diameter  of  the  wheel. 

The  number  of  buckets  is,  to  a certain  extent,  arbitrary.  As  a guide  in  practice,  to  he  controlled  by 
particular  circumstances,  and  limited  to  diameters  of  not  less  than  two  feet,  the  number  of  buckets 
should  he  three  times  the  diameter  in  feet,  plus  thirty.  The  Tremont  Turbine  is  8£  feet  in  diameter, 
and  according  to  the  proposed  rule,  should  have  fifty-five  buckets  instead  of  forty-four.  The  number 
of  the  guides  is  also  to  a certain  extent  arbitraiy;  the  practice  at  Lowell  has  been,  usually,  to  have  from 
a half  to  three-fourths  of  the  number  of  buckets. 

As  turbines  are  generally  used,  a velocity  of  the  interior  circumference  of  the  wheel,  of  about  fifty- 
six  per  cent,  of  that  due  to  the  fall  acting  upon  the  wheel,  appears  most  suitable. 

To  lay  out  the  curve  of  the  buckets — 

Referring  to  fig.  3817,  the  number  of  buckets  N,  having  been  determined  by  the  preceding  rules,  set 

IT  I) 

off  the  arc  yi  — Let  u — gh,  the  shortest  distance  between  the  buckets  : t the  thickness  of  the 

N 

metal  forming  the  buckets.  Make  the  arc  glc  = 5 w.  Draw  the  radius  o k,  intersecting  the  interior  cir- 
cumference of  the  wheel  at  l ; the  point  l will  be  the  inner  extremity  of  the  bucket.  Draw  the  direc- 
trix Im  tangent  to  the  inner  circumference  of  the  wheel.  Draw  the  arc  o re,  with  the  radius  w + t,  from 
i,  as  a centre ; the  other  directrix  y pi,  must  be  found  by  trial,  the  required  conditions  being,  that  when 
the  line  ml  is  revolved  round  to  the  position  gt,  the  point  m being  constantly  on  the  directrix  g p,  and 
another  point  at  the  distance  m g = r s,  from  the  extremity  of  the  line  describing  the  bucket,  being  con- 


88G 


WATER-WHEELS. 


■ •tantly  on  the  directrix  m l,  the  curve  described  shall  just  touch  the  arc  n o.  A convenient  line  for  a 
jrst  approximation,  may  be  drawn  by  making  the  angle  0 y p — 11°.  After  determining  the  directrix 
according  to  the  preceding  method,  if  the  angle  0 gp  should  be  greater  than  12°,  or  less  than  10°,  the 
length  of  the  arc  g h should  be  changed,  to  bring  the  angle  within  these  limits. 

The  trace  adopted  for  the  corresponding  guides  is  as  follows  : — The  number  n having  been  determined, 
divide  the  circle  in  which  the  extremities  of  the  guides  are  found,  into  n equal  parts,  v w,  w x,  the.  Put 
to'  for  the  width  between  two  adjoining  guides,  and  t'  for  the  thickness  of  the  metal  forming  the  guides 

We  have  by  rule  =lL.  With  w as  a centre,  and  the  radius  w +<',  draw  the  arc  y z;  and  with  £ as  a 
n 

centre,  and  the  radius  2(«'  +<'),  draw  the  arc  a b' . Through  v draw  the  portion  of  a circle  v c'  touching 
the  arcs  yz  and  a b' ; this  will  be  the  curve  for  the  essential  part  of  the  guide.  The  remainder  of  the 
guide  c d',  should  be  drawn  tangent  to  the  curve  c'  v , a convenient  radius  is  one  that  would  cause  the 
curve  c1  d1,  if  continued,  to  pass  through  the  centre  0. 

Passot’s  Turbine , Figs.  3818,  3819,  3820. 

“ Are  composed  of  cylindrical  vessels  fixed  to  vertical  arbors,  and  supplied  at  the  circumference 
with  orifices  intended  for  the  introduction  or  ejection  of  the  water.  The  modification  which  M.  Passot 
has  introduced  into  the  old  reacting  wheels,  and  which  he  claims  as  his  invention,  consists  of  having 
suppressed  or  got  rid  of  the  internal  partitions,  and  reduced  the  old  wheels  to  their  only  true  essential 
elements — a motive  cylinder  to  contain  the  motive  fluid,  with  surfaces  to  receive  its  action,  and  corres- 
ponding orifices  for  discharge.  The  surfaces  and  the  orifices  are  exactly  included  between  two  concen- 
tric circumferences ; that  is  to  say,  that  he  carefully  retrenches  all  other  surface,  or  projection,  capable 
of  impressing  the  water  with  the  angular  movement  of  the  wheel  before  having  reached  the  parts 
destined  to  receive  its  action,  as  well  as  the  orifices  of  discharge.  “ I form  the  new  wheel,”  says  M 
Passot,  “ simply  by  placing  either  in  the  interior  or  exterior  of  a cylindrical  drum,  according  as  I want 
the  pressure  of  the  fluid  to  be  exerted  on  the  interior  or  exterior  curved  vanes  in  the  arc  of  a circle, 
such  as  abed,  Figs.  3819  and  3820  ; then  I make  orifices  of  discharge,  by  removing  from  these  vanes 
and  from  the  cylinder  the  part  in  form  of  a wedge,  a b d,  and  the  motion  is  effected  by  virtue  of  the 
pressure  on  the  faces  c d,  c' d' , c"  d" . 

“ While  the  machine  is  very  simple,  its  properties  are  very  remarkable.  When  the  wheel  turns 
without  load  or  work,  under  a given  difference  of  level  or  fall,  its  vanes  take  exactly  the  theoretical 
velocity  due  to  the  fall.  It  is  no  longer  the  same  when  in  any  manner  the  form  of  the  new  wheel  is 
altered  so  as  to  approach  those  formerly  known;  all  partitions,  projections,  and  asperities  which  are 
either  within  or  without  two  concentric  circumferences,  considerably  diminish  the  theoretic  velocity  of 
rotation  due  to  the  fall,  on  account  of  the  continual  shock  of  these  bodies  in  motion  against  the  water  in 
repose.  Then  it  is  not  surprising  if  the  useful  effect  of  reacting  wheels,  when  experimented  upon,  has 
never  risen  above  50  per  cent. ; that  is  to  say,  about  the  rate  of  breast-wheels  of  the  usual  varieties. 

“ The  expenditure  of  water  in  Fig.  3820  with  the  internal  action,  is  sensibly  independent  of  the 
greater  or  less  reaction  of  the  wheel.  In  Fig.  3819,  with  external  action,  this  cannot  take  place  on  ac- 
count of  the  counter-pressure  arising  from  the  formation  of  an  eddy  in  the  interior  ; but  this  counter 
;r  assure  is.  however,  much  less  than  might  be  supposed.  I have  demonstrated  that  when  a fluid  forms 


3S19. 


an  eddv  in  the  interior  of  a cylinder,  the  effects  of  the  centrifugal  force  show  themselves  differently 
according  to  the  different  inclinations  of  the  projections  or  orifices  made  on  the  . influ 

“ In  Fig.  3819  the  orifices  are  disposed  in  the  direction  in  which  the  centufugal  foice  ca 


WATER-WHEELS. 


8S7 


snce  the  expenditure  of  water.  Thus  the  coefficient  of  theoretical  expenditure  due  to  the  work,  during 
the  experiments  on  the  turbine  which  I constructed  at  Bourges,  has  been  found  very  little  different  front 
that  which  agrees  with  the  openings  of  ordinary  sluices  disposed  so  as  to  avoid  contractions  on  three  of 
the  sides.  The  wheel  which  turned  in  work,  with  about  half  the  velocity  due  to  the  fall,  and  the  co- 
efficient, was  070  to  0'79.” 

M.  Poncelet,  adopting  an  arrangement  the  reverse  of  that  of  M.  Fourneyron,  has  proposed  a system 
of  turbines  of  the  nature  of  the  horizontal  wheels  used  in  the  centre  and  south  of  France.  The  water 
enters  by  a spout  placed  on  the  outside,  stretches  the  vanes,  and  is  discharged  by  two  openings  made 
towards  the  centre.  M.  Cardelhac  has  constructed  at  Toulouse  turbines  on  this  plan  ; and  Messrs. 
Mellet  and  Sarrus,  of  Lodeve,  have  exhibited  one  with  the  same  arrangement.  The  principal  part  ol 
their  turbines  consists  in  a case  of  particular  form,  provided  with  three  openings,  of  which  one  is  for 
the  water  to  enter,  and  the  two  others  to  allow  it  to  escape  after  its  action  on  the  wheel.  In  conse- 
quence of  the  spiral  form  of  this  casing,  the  water  arrives  on  the  wheel  placed  in  the  interior  without 
any  shock,  and  with  a velocity  due  to  half  the  height  of  the  fall.  Each  of  these  veins  or  streams  of 
water  acts  at  the  same  distance  from  the  axis,  as  if  it  were  isolated  and  independent  of  the  other.  Its 
velocity  is  transformed  into  pressure  by  insensible  degrees,  and  without  any  loss  of  power. 

Whitelaw  s reaction-wheel — Figs.  3814  to  3821. — The  principle  of  this  machine  has  been  already  ex- 
plained, it  therefore  only  remains  in  this  place  to  indicate  briefly  the  practical  details  and  features  of 
the  construction.  In  this  latter  respect  it  is  a much  simpler  machine  than  that  above  described  ; but 
still  its  efficiency. depends  in  nearly  an  equal  degree  upon  a correct  appreciation  of  the  principles  in- 
volved in  its  modus  operandi.  The  merely  technical  details  have  already  been  pretty  fully  pointed 
out  in  describing  the  figures  enumerated  above,  but  it  may  be  necessary  to  indicate  the  rules  employed 
in  assimilating  these  to  the  conditions  furnished  by  the  particular  circumstances  of  the  individual  case. 

As  in  all  other  hydraulic  machines,  the  data  necessary  to  be  assigned  as  the  basis  of  any  calculation 
of  the  size  and  angular  velocity  of  the  reaction-wheel,  are  the  values  of  H and  Q,  that  is,  the  height  of 
fall  under  which  it  is  intended  to  act,  and  the  volume  of  wTater  to  be  used.  We  have  before  seen  that 
if  the  water  in  the  arms  of  the  machine  experienced  no  increase  of  pressure  from  centrifugal  force, 
the  discharge  assigned  by  theory  is  expressed  by  S 2 cj  H ; but  in  consequence  of  the  centrifugal 
force  produced  by  the  rotation  of  the  machine  about  its  axis,  this  quantity  will  be  increased  to 

S\/2pII-f-i'2  (l  — ■ But  we  know  from  experiment  that  in  consequence  of  frictional  disturb- 


ance of  the  fluid  in  passing  through  the  apparatus,  the  real  quantity  discharged  is  uniformly  less  than 
that  assigned  by  theory,  and  that  the  reduction  depends  upon  conditions  which  to  some  extent  are 
within  the  control  of  the  mechanician.  On  this  subject  we  quote,  with  slight  modification,' from  a paper 
read  by  Mr.  W.  M.  Buchanan  before  the  Philosophical  Society  of  Glasgow  (1846)  on  the  theory  of  this 
species  of  machine.  After  stating  the  loss  of  head,  observed  in  his  experimental  apparatus,  by  com- 
paring the  actual  fall  with  the  quantity  of  water  actually  discharged  by  a machine,  of  which  the  jet- 
orifices  were  accurately  determined,  the  author  assigns,  as  the  sources  of  that  reduction, 

1.  The  pressure  absorbed  by  the  friction  of  the  water  in  passing  through  the  supply-pipe.  This  he 
regards  as  a known  quantity,  which  is  expressed  in  character  and  amount  by 


tt2 

2? 


in  which  C denotes  the  internal  perimeter,  A,  the  cross-sectional  area,  and  L the  length  of  the  pipe ; it, 
the  velocity  with  which  the  water  descends  through  it,  and  f an  empirical  coefficient  = -0035.  If. 
therefore,  S denote  the  sum  of  the  areas  of  the  orifices,  Y the  velocity  of  efflux,  and  D the  diameter  ot 
the  pipe,  all  in  feet,  this  expression  may  be  put  under  the  form 


„ , L S2 
f' ' D ‘ A2 


XI 
2 1 


2.  The  loss  of  head  arising  from  the  acceleration  of  the  water  in  passing  from  the  supply-pipe  into 
ilie  interior  of  the  machine  through  the  water-joint  neck,  formed  by  the  mouth-piece  and  central  open- 
ing, and  which  is  commonly  less  in  diameter  than  the  supply-pipe,  as  shown  in  Fig.  3818.  This  he 
expresses  by  the  formula 


» 


A ,1 

Ay 


in  which  A;/  is  the  area  of  the  central  opening,  and  u the  velocity  of  the  water  passing  through  it : m 
a coefficient  determined  from  experiment  to  be  =-9378. 

3.  The  small  loss  of  head  resulting  from  the  resistance  encountered  by  the  water  in  traversing  the 
arms  of  the  machine,  which  he  expresses  by 


8/.S2  — A-d*  = y— . 

J 2, /JO  Ajjj  7 2 a 


in  which  C,  and  Alu  are  respectively  the  transverse  perimeter  and  area  of  the  channels  at  a distance  * 
from  their  origin. 

4.  The  loss  resulting  from  what  is  called  the  contracted  vein.  Although  the  volume  of  water  dis- 
charged by  any  orifice  under  a given  head-pressure  is  invariably  proportional  to  the  area  of  that  orifice 
and  the  square  root  of  the  head,  the  actual  quantity  is  found  to  depend  much  upon  the  form  of  the 
orifice  through  which  it  issues.  If  the  fluid  be  confined  in  a vessel  of  thin  material,  and  the  orifice  be 


888 


WATER- WHEELS. 


simply  a hole  pierced  in  its  side,  the  discharge  in  cubic  feet  per  second  -will  be  nearly  expressed  by 
W2  g H,  the  area  of  the  orifice  being  a.  If  the  jet  from  an  orifice  of  this  kind  be  closely  observed, 
it  will  be  perceived  to  converge  through  a short  distance  from  its  origin,  forming,  when  the  orifice  is 
circular,  a conoid,  of  which  the  area  of  the  least  section  is  gths  of  the  area  of  the  orifice.  If  advantage 


oe  taken  of  this  circumstance  to  apply  an  ajutage  to  the  orifice  of  the  form  assumed  by  the  jet,  tfte 
discharge  will  be  found  to  approximate  very  closely  to  that  assigned  by  the  theoretical  formula. 

This  difference  of  discharge  in  the  two  kinds  of  aperture  is  usually  ascribed  to  the  inclined  directions 
which  the  molecules  of  the  fluid  assume  previous  to  their  exit,  and  which  they  tend  to  retain  after  pass- 
ing the  thin  parietes  of  the  simple  orifice.  For  greater  clearness,  let  us  assume  that  the  aperture  is 


890 


WATER- WHEELS. 


horizontal,  circular,  and  of  small  area  in  comparison  with  the  area  of  the  containing  vessel ; under  these 
conditions  a large  portion  of  the  fluid  will  be  put  in  motion,  and  will  slowly  approach  the  orifice  during 
the  efflux,  in  the  form  of  an  inverted  cone,  of  which  the  orifice  is  the  apex.  The  particles,  as  they  come 
opposite  to  the  orifice,  are  therefore  impressed  with  motions  converging  to  an  axis  ; but  these  motions, 
in  consequence  of  the  mutual  cohesion  of  the  particles,  must  tend  to  a common  velocity  in  that  axis ; 
and  the  length  of  the  external  conoid  will  express  the  time  in  which  the  oblique  motions  are  converted 
into  motions  parallel  to  the  axis  of  the  jet.  It  is  therefore  only  at  the  point  of  least  section  that  the 
molecules  of  fluid  have  attained  the  effective  velocity  due  to  the  head  under  which  they  issue  ; and  it  is 
therefore  only  in  reference  to  that  point  that  the  hydraulic  pressure  of  the  jet  is  equal  to  a column  of 
the  fluid  of  double  the  actual  head.  By  adopting  an  ajutage  to  the  orifice  of  the  shape  indicated,  the 
oblique  motions  of  the  particles  are  corrected  in  passing  through  it,  and  reduced  to  parallelism  with  the 
axis  at  the  moment  of  efflux  into  the  atmosphere.  There  still,  however,  remains  to  depreciate  the  dis- 
charge assigned  by  the  formula  q—a  ^/2 g H,  the  imperfections  of  wormanship  in  the  construction,  and 
the  adhesion  of  the  fluid  to  the  perimeter  of  the  ajutage,  with  possibly  a slight  atmospheric  influence 
not  yet  defined.  But  assuming  the  ajutage  to  be  made  with  all  possible  care,  both  as  to  form  and 
finish,  if  we  call  the  area  of  the  orifice  1000,  that  of  the  contracted  vein  will  be  915  ; and  these  num- 
bers taken  inversely  will  express  the  velocity  of  the  jet  at  the  two  points  measured  by  the  discharge. 
The  value  of  q for  an  orifice  of  this  form  will  therefore  be 


y = -975  a ^/2  g H, 

showing  a loss  of  head-pressure,  as  measured  by  the  discharge,  of 

U2 

(1  — -9752)  — = -049375  H 
2 9 

when  IT  = ^2^11  the  theoretical  velocity  due  to  the  head  H.  And  generally,  if  Y be  the  actual  ve- 


V 

locity  of  efflux,  and  k the  practical  coefficient  of  discharge  for  any  orifice,  so  that  U =— , the  head- 

/I  \ V2  V2 

pressure  not  realized  in  the  measure  of  q,  will  be  ( — 1}  — —S  — . And  the  pressure  not  realized 

/2p  2p 

in  the  measure  of  the  reaction,  will  be  expressed  by 


Sin 


/ 1 \ 

(l2_  V 2 


V2 

9' 


V2 


in  which  <p  denotes  the  mean  angle  formed  by  the  filaments  of  water  of  the  jet  with  the  axis. 

But  betwixt  this  the  least  contraction  of  the  fluid  vein,  and  that  which  takes  place  when  the  orifice  is 
formed  in  a thin  plate,  we  may  evidently  have  a series  of  any  number  of  terms  expressing  successive 
degrees  of  approximation  of  the  ajutage  to  the  theoretical  form  of  least  contraction.  This  is  obvious,  as 
regards  the  discharge  from  a fixed  ajutage ; and  it  is  equally  obvious,  that  if  an  ajutage  be  constructed 
to  fulfil  the  conditions  of  least  contraction  when  the  vessel  is  at  rest,  it  will  no  longer  answer  that  con- 
dition when  it  moves  in  the  line  of  the  jet  with  any  given  velocity.  If  its  motion  be  in  the  direction  of 
the  jet,  its  length  will  manifestly  be  virtually  increased,  and  the  contraction  will  approach  to  that  of  a 
jet  issuing  from  a parallel  pipe,  the  coefficient  for  which  is  -8 ; and  if  the  movement  be  in  the  contrary 
direction,  the  length  of  the  ajutage  will  be  in  effect  diminished,  and  the  contraction  will  approach  that 
from  an  orifice  in  a thin  plate.  This  last  is  the  actual  case  which  falls  to  be  considered  in  the  reaction 
machine;  the  ajutages  have  a determinate  velocity,  in  an  opposite  direction  to  that  in  which  the  fluid 
issues,  and  accordingly  have  their  length  virtually  reduced.  This  must  necessarily  be  provided  against 
in  the  construction  of  the  machine,  and  a length  and  form  of  the  ajutages  determined,  which  shall  ex- 
actly correspond,  at  the  given  angular  velocity  of  the  machine,  to  the  proper  dimensions  at  which,  if 
stationary,  they  would  yield  their  maximum  discharge.  This  is  a problem  which  requires  to  be  resolved 
for  every  machine. 

It  may,  however,  be  stated  as  a general  rule,  that  the  contraction  of  the  channels  towards  the  orifices 
is  half  of  that  which  would  give  the  maximum  discharge  if  the  machine  was  at  rest,  and  may  therefore 
be  taken  at  7°. 


If  to  these  absorbing  influences  we  add  c - — , comprehending  the  loss  of  atmospheric  pressure  due  to 

the  head  H,  and  the  effect  of  the  cohesion  of  the  water  to  the  perimeter  of  the  orifices,  (not  valued,)  we 
shall  have  as  the  total  calculated  loss  of  head-pressure, 


(a  + ff  + y + ^ + e)— , 

and  putting  a-f/3-fy-)-(l-|-£  = K,  we  shall  have  as  the  velocity  of  efflux,  taking  the  formula  of  p.  792, 


TPfSnAh +e(i-A). 

In  those  machines  constructed  according  to  the  proportions  usually  adopted  by  the  makers,  tha 
quantity  - — does  not  differ  sensibly  in  ordinary  cases  from  0‘94 ; and  it  has  been  stated  that 

V 1 + K 

It  = 2-5  r ; if,  therefore,  we  substitute  these  numbers  in  this  formula,  it  is  reduced  to  the  following : 
0-94  V 2 g H A\s4  — 7-5  y/ H + i e2  = V 


WATER-WHEELS. 


891 


A.nd  multiplying  this  last  expression  by  60  times  the  area  of  the  two  orifices,  (in  feet,)  we  shall  have,  aj 


the  quantity  of  water  discharged  in  a minute,  450  S 


II  -f-  — v1  cubic  feet  = Q. 


We  have  already  found  as  the  measure  of  the  effect  of  the  machine  — (V  — v)v;  if,  therefore,  in  this 

9 

expression  we  substitute  the  actual  value  of  Y found  above,  we  shall  have 


But,  in  practice,  the  velocity  v of  the  machine  is  taken  equal  to  8 ,/  H.  If,  therefore,  we  substitute 
this  value  in  that  found  for  E,  and  put  for  w its  equivalent  62  5 q,  and  for  g its  value  32'2,  we  shall  have 

E = 50  q H very  nearly. 

Or,  taking  the  quantity  of  water  expended  in  a minute,  and  expressing  E in  units  of  horse-power, 
we  have 

e = «5, 

660 

which  is  this  rule  : Multiply  the  quantity  of  water  expended  in  a minute  by  the  given  height  of  fall,  and 
divide  the  product  by  660 : the  resulting  quotient  will  express  the  effect  in  units  of  horse-power,  (the 
horse-power  being  33,000  lbs.  raised  through  a height  of  1 foot  in  a minute.) 

This  rule  shows  that  the  machine  ought  to  yield,  in  practice,  an  effect  of  79}  per  cent,  of  the  power 
expended,  independently  of  the  partial  losses  of  head  above  enumerated,  taking  the  fall  from  the  mid- 
dle of  the  depth  of  the  machine  to  the  surface  of  the  water  in  the  reservoir. 


Height  of  fall. 

II. 

Quantity  of  wa- 
ter expended  in 
1 minute. 

Q. 

Weight  on  the 
arms  of  the  fric- 
tion brake. 

V' 

Velocity  in  the 
circle  of  the 
brake. 

V. 

Percentage  cf 
effect. 

W H 

100  . 

pv 

Diameter  of 
model. 

Feet. 

9’335 

Cubic  feet. 
10169 

Oz. 

9 

Feet. 

7910 

75-212 

10-520 

11-530 

9} 

9510 

76-664 

•* 

10'355 

10-360 

10} 

7820 

74-933 

10-210 

10-330 

10 

7820 

74-433 

p 

10-040 

10-338 

“ 

7900 

76-333 

9-735 

10-250 

9| 

7820 

76-630 

§ 

9'575 

9-790 

7330 

76-460 

9-390 

9-305 

“ 

6690 

74-868 

1 

10-335 

11-090 

“ 

8960 

76-440 

ft 

10-165 

11-010 

“ 

8840 

77-236 

2 

9-830 

10-350 

“ 

8030 

77-173 

r-’ 

9-680 

10-080 

<( 

8420 

77-887 

10-010 

10-740 

“ 

85S0 

78-040 

L~- 

10-700 

13-69 

to 

5340 

74-945 

OJ* 

10-545 

13-44 

“ 

5240 

76-015  * 

2, 

10-415 

13-05 

u 

5040 

76-237 

10-250 

12-79 

u 

4900 

76-845 

10-130 

12-73 

“ 

4870 

77-644 

£ 

9-980 

12-48 

“ 

4630 

76-425 

C 

O 

9-820 

12-44 

“ 

4500 

75-745 

9 660 

11-92 

a 

4280 

76-420 

i 

9-840 

12-33 

20} 

4600 

77-000 

£ 

9-700 

12-45 

19} 

4750 

77-910 

9-950 

12-40 

20} 

4700 

78-320 

10-270 

12-68 

21 

4740 

76-660 

10-460 

12-47 

22 

4540 

76-800 

8-05 

Lbs. 

562-32 

14 

37620 

72-69 

“ 

560-33 

3685-4 

74-03 

“ 

558-75 

15 

3647-3 

75-84 

2 0 

553-61 

154 

34S8-5 

7601 

(( 

548-36 

16 

3380-4 

76-56 

Jl 

“ 

53000 

164 

3202-5 

77-39 

‘4 

514-25 

17 

2973-7 

76-31 

The  preceding  table  of  experiments,  upon  three  model  machines,  will  show  that  this  high  percentage 
n effect  is  attainable.  In  the  experiments  with  the  first  models,  the  fall  was  variable,  aud  the  proper 
relocity  of  the  machine  was,  therefore,  in  no  case  strictly  attained.  The  correct  velocity  was  not  at- 


892 


WATER-WHEELS. 


tained  in  the  third  set  of  experiments,  although  the  fall  was  constant,  in  consequence  of  the  successive 
variations  of  load  being  too  great.  The  maximum  of  effect  is  therefore  not  obtained  in  any  of  the  re- 
sults given,  but  some  of  the  results  approach  it  very  closely. 

The  mode  of  performing  the  experiments  was  nearly  the  same  throughout.  The  load  was  applied 
upon  the  equal  arms  of  a friction  brake  of  T59155  feet  radius,  (as  nearly  as  could  be  measured,)  so  that 
its  circle  was  exactly  10  feet.  The  revolutions  of  the  machine  were  ascertained  by  a counter  worked 
by  a screw  cut  on  its  vertical  spindle  ; and  the  water  discharged  was  received  into  a cistern,  of  which 
the  dimensions  were  accurately  determined.  The  circle  of  the  arms  of  the  brake  at  the  points  where 
the  weight  was  attached  being  10  feet,  the  numbers  in  the  column  stating  the  velocity  in  that  circle 
being  divided  by  10,  the  quotient  will,  of  course,  show  the  number  of  revolutions  made  by  the  machine 
in  the  unit  of  time,  1 minute. 

The  constructive  rules,  published  by  Mr.  Wliitelaw  in  the  Artizan  for  Nov.  1845,  are  as  follows,  the 
height  of  fall  and  the  quantity  of  water  furnished  in  a minute  being  known  : 

A horse-power  being  taken  at  33,000  lbs.  raised  one  foot  in  a minute,  this  will  be  represented  by 
43,421  lbs.  of  wTater  per  minute,  with  a fall  of  one  foot,  supposing  the  machine  to  realize  only  *76  per 
cent,  of  the  power  expended;  and  the  weight  of  a cubic  foot  of  water  being  taken  at  62,321  lbs.,  the 
c-quivalent  of  43,421  lbs.  will  be  696'7 3 cubic  feet.  Taking  Q and  H as  before,  the  quantity  of  water 
furnished  in  a minute  and  height  through  which  it  descends,  we  have  as  the  value  of  E in  units  of  horse- 
power, 

69673 

From  this  the  dimensions  of  the  principal  parts  and  the  velocity  of  the  machine  are  determined,  as 
stated  in  the  following  expressions — it  being  understood  that  the  machine  has  two , and  only  two  jet 
orifices,  and  these  so  formed  as  not  to  cause  the  issuing  jets  to  contract  more  than  in  the  proportion  of 
97  to  100  after  the  fluid  has  left  the  orifices. 


Width  of  each  discharging  orifice  ■ 


V7 


135  E 

1000  Hy/H ' 


Width  of  each  arm  of  machine  = 4 w,  = w„ 
Diameter  of  the  machine  = 50  w,  = d, 
Diameter  of  central  opening  = 10  w,  = on 

Number  of  revolutions  in  a minute  _ 


All  these  rules,  except  the  last,  may  be  departed  from  with  impunity ; but  it  is  impossible  to  enumer- 
ate the  circumstances  and  conditions  under  which  modifications  may  be  safely  introduced,  and  where 
they  would  be  prejudicial.  These  can  only  be  appreciated  by  practice  and  a close  investigation  of  the 
action  of  the  machine.  The  rules  are,  however,  safe  within  a wide  range  of  fall — in  fact,  for  all  ordi- 
nary cases. 

Comparison  of  the  different  species  of  wheels. — -From  what  we  have  seen  of  the  different  conditions 
necessary  to  produce  the  maximum  effect,  it  is  evident  that  we  ought  not  to  be  indifferent  to  the  kind 
of  wheel  to  be  adopted  in  any  particular  case.  The  wheel  ought  especially  to  be  adapted  as  far  as 
possible,  not  only  to  the  height  of  fall  and  quantity  of  water  to  be  employed,  but  also  to  the  kind  ot 
machinery  which  it  is  intended  to  propel.  If  the  motion  required  be  slow,  and  especially  if  it  be  besides 
irregular,  a vertical  wheel,  of  large  diameter  and  considerable  weight,  will  in  general  be  the  most  sat 
isfactory.  On  the  cijptrary,  where  a high  velocity  is  required,  a horizontal  wheel  will  be  the  most 
economical.  The  undershot-wheel  is  only  commendable  in  cases  where  no  other  is  applicable,  on  ac- 
count of  the  lowness  of  the  fall  and  large  supply  of  water.  It  has  the  advantage,  however,  of  being 
constructed  at  comparatively  small  cost,  and  if  the  run  of  the  water  be  considerable,  its  velocity  will 
be  proportionally  high  in  order  that  it  may  yield  its  maximum  effect.  Its  great  inconvenience  is  the 
emallness  of  that  effect,  which  is  in  part  remedied  by  employing  the  arrangement  recommended  by  M. 
Poncelet  now  extensively  adopted  on  the  continent.  This  may  be  made  to  yield  an  effect  of  50  to  60 
per  cent,  of  that  of  the  water,  when  the  head  of  water  does  ndt  exceed  4|-  feet.  It  also  takes  compara- 
tively a high  velocity,  and  it  is  to  be  kept  in  mind  that  the  higher  the  velocity  of  any  wheel  of  this 
species,  the  less  will  be  its  breadth,  size  of  sluice,  arc,  and  other  parts  influenced  by  the  volume  ot 
water.  It  will,  moreover,  continue  to  work  in  backwater  until  the  levels  before  and  behind  approach 
equality,  and  is  therefore  particularly  fitted  for  level  districts  subject  to  inundations.  It  is,  however, 
liable  to  this  inconvenience,  that  its  velocity  cannot  deviate  sensibly  from  that  at  which  it  yields  its 
maximum  effect  without  losing  greatly  in  power. 

From  falls  from  4 to  7 feet,  the  breast-wheel  with  radial  floats  inclosed  in  an  arc  may  be  employed 
with  advantage.  If  well  constructed,  and  the  arc  be  accurately  fitted,  to  prevent  waste  of  water,  this 
species  of  wheel  is  capable  of  yielding  from  60  to  70  per  cent,  of  the  power  of  the  water  expended.  It 
may  besides  deviate  very  considerably  from  the  correct  velocity  without  losing  much  in  effect ; but  it 
is  to  be  observed  that  this  velocity  ought  never  to  be  very  high.  This  species  of  wheel  is  therefore 
particularly  applicable  in  cases  where  the  ultimate  velocity  of  the  machinery  impelled  is  low ; but  it 
lies  under  the  disadvantage  that,  on  account  of  the  slowness  of  its  motion,  its  breadth  must  be  great, 
and  all  its  constructive  details  conformably  large  and  heavy.  It  is,  besides,  not  well  suited  for  situa- 
tions subject  to  backwater,  which  very  speedily  brings  it  to  rest.  The  bucket-wheel  is  applicable  for 
higher  falls  and  smaller  supplies  of  water.  It  has  all  the  advantages  of  the  breast-wheel,  with  some 
of  its  defects.  It  may  have  a velocity  varying  from  3 feet  a second  to  7 feet ; and  adopting  this  highei 
speed,  and  allowing  the  buckets  to  be  half  filled  with  water,  its  expeDse  will  be  greatly  lessened 


TABLE  OF  THE  PROPORTIONS  OF  WATER-WHEELS  CONSTRUCTED  BY  MR.  WILLIAM  FAIRBAIRN,  OF  MANCHESTER. 


WATER-WHEELS 


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Note. — Mr.  Fairbairn’s  maximum  velocity  of  the  periphery  of  the  wheel  is  about  7 feet  per  second  for  a fall  of  5 or  f»  feet,  and  his  minimum  velocity  from  2£  to  3 feet  for  a fall  of  40  to  45  feet. 


894 


WATER-WHEELS. 


When  the  fall  is  high,  18  feet  and  upwards,  it  is  not  common  to  provide  any  arc  to  economize  the  wa- 
ter at  the  lower  part  of  the  revolution  ; and  when  the  buckets  are  properly  formed,  an  arc  is  not  greatly 
wanted.  But  in  general  cases  the  buckets  are  formed  without  much  attention  seemingly  to  the  func- 
tions which  they  are  intended  to  perform,  and,  accordingly,  a large  waste  of  power  is  incurred  which 
an  arc  would  go  for  to  prevent. 

The  inconvenience  of  the  bucket-wheel  is  the  low  rate  of  its  maximum  speed  where  high  working 
velocities  are  required.  This  occasions  the  multiplication  of  intermediate  geering  with  all  its  concomi- 
tant evils.  It  is  applicable,  we  have  said,  to  high  falls ; but  this  has  its  limits.  To  obtain  the  full 
value  of  the  water,  the  diameter  must  increase  as  the  fall,  and  the  dimensions  and  weight  assume  cor- 
responding proportions.  The  construction,  accordingly,  becomes  expensive  in  a high  degree. 

The  preceding  table  of  the  proportions  of  wheels  of  this  class,  constructed  by  Mr.  William  Fairbairn, 
of  Manchester,  will  be  useful. 

When  the  height  of  foil  exceeds  that  for  which  it  would  be  judicious  to  attempt  to  construct  a bucket- 
wheel,  it  is  then  necessary  to  have  recourse  to  one  or  other  of  the  horizontal  wheels  described — namely, 
the  turbine  of  M.  Fourneyron,  or  the  reaction-wheel  of  Mr.  Whitelaw.  The  first  of  these  may  be  made 
fo  yield  an  effect  of  about  50  per  cent,  of  value  of  the  water  even  on  very  low  falls,  and  when  immersed 
in  tail- water;  and  about  70  per  cent,  on  higher  falls.  The  letter  has  also  been  made  for  situations  in 
which  it  was  intended  to  work  occasionally  in  backwater,  and  with  very  considerable  success ; and,  for 
high  falls,  we  have  seen  that  it  is  capable-  of  yielding  an  effect  at  least  equal  to  the  bucket-wheel.  It 
has  advantage  of  the  turbine  in  being  less  expensive,  much  more  simple,  and,  we  believe,  is  essentially 
more  effective,  on  account  of  there  being  less  loss  of  vis  viva  of  the  fluid  in  passing  through  the  ma- 
chine. Both  have  the  advantage  of  being  applicable  to  falls  of  any  height,  and  of  moving  at  velocities 
differing  widely  from  that  at  which  they  yield  their  maximum,  without  much  loss  of  effect.  On  low 
falls  they  have,  what  is  generally  reckoned,  an  advantage ; they  give  immediately  a comparatively 
high  velocity  which,  in  the  case  of  cotton  factories  and  the  like,  allows  much  heavy  geering  to  be  dis- 
pensed with.  They  have  also  a further  very  marked  advantage  in  the  little  space  which  they  occupy 
Several  reaction-wheels,  of  50  horse-power  and  upwards,  might  be  referred  to,  placed  in  situations 
where,  it  may  be  said,  they  literally  occupy  no  room,  being  situated  in  a small  pit  under  the  floors  of 
the  factories  to  which  they  furnish  the  motive  power.  In  cases  where  the  fall  is  very  high — and  both 
the  turbine  and  reaction-wheel  have  been  applied  to  falls  which  could  not  have  been  employed  on 
wheels  of  the  common  kind — the  high  speed  becomes  an  inconvenience,  causing  the  use  of  intermediate 
geering  for  the  purpose  of  reducing  it.  This  can  be  remedied,  to  a certain  extent,  by  increasing  the 
diameter  of  the  machine ; but,  when  it  is  desired  to  take  advantage  of  falls  of  100  feet  and  upwards, 
perhaps  some  little  inconvenience  may  be  submitted  to  without  reluctance. 

There  remains  to  be  exhibited  the  turbine  of  Jonval,  now  being  introduced  in  this  country  extensively. 

Jonval’s  Turbine , as  built  by  E.  Geyelin , Hydraulic  Engineer,  Philadelphia. — The  Jonval  turbine 
was  invented  and  patented  in  France  a few  years  since,  by  a French  gentleman  whose  name  it  bears. 

The  first  turbine  of  this  species,  made  by  Messrs.  Andre  Koechlin  & Co.,  was  erected  and  put  in 
operation  in  a large  paper  mill  at  Pont  d’Aspach,  in  the  vicinity  of  Mulhouse,  upon  which  a committee 
of  the  Societe  Industrielle  de  Mulhouse  experimented,  and  reported  the  following  tables  of  the  results. 

The  experiments  were  made  with  the  friction  brake  of  Prony. 


Table  of  experiments  with  the  Friction  Brake,  made  on  the  Turbine  of  Pont  d’Aspach,  and  reported  by 
Mr.  Amede  Riedek,  Member  of  the  Committee  of  the  Industrial  Society  of  Mulhouse. 


Number  of  the  Experi- 
ments. 

Depth  of  the  discharge 
of  water,  through  an 
overflow  of  3-200  m. 
wide* 

Weight  of  water  in 
kilogrammes  expended 
per  second. 

Height  of  the  fall  in 
metres. 

Theoretic  pow- 
er of  the  Motor. 

1 

i Weight  on  the  trie-  1 
1 lion  brake  in  kilo- 
grammes. 

Number  of  revolutions 
of  the  Turbine. 

Ti  O 

lli 

o ZZ  — 

Pel 

=!i 

5 ” * 

Si  © <D 

2 = -2 
z'oi 

1 Velocity  which  the 
1 point  of  suspension  of 
the  resistance  took  in 
one  second. 

Effective  power 
of  the  Motor. 

1 
o . 

II 

|S 

Kilog.  lifted  1 
metre  high  in 
one  second. 

1 

NumbV  of  horses 
of  75  kilog. 

■".S 

~ o 

JM 

*i§ 

Is 

JO 

So 

■z 

m. 

i 

0-187 

439 

2-87 

1-259 

16-72 

7000 

76-00 

38-00 

12-229 

856 

9-24 

56 

2 

0-190 

447 

2-87 

1-282 

17-10 

65-00 

96-00 

48-00 

15-448 

1004 

14-72 

86 

3 

0195 

403 

2-90 

1-351 

18-03 

57-00 

1-2400 

62-00 

19*94 

1136 

15-15 

84 

4 

0-195 

4G3 

2"  82 

1-305 

17-47 

47-00 

134-00 

07-00 

21-56 

1013 

13-50 

77 

5 

0-195 

403 

2-71 

1-254 

16-73 

37-00 

164-00 

82-00 

26-39 

976 

1302 

77 

6 

0198 

473 

2-95 

1-399 

18-05 

35-00 

178-00 

80-00 

28-64 

1002 

13-36 

72 

1 

0-239 

039 

2-78 

1-770 

23-68 

89-80 

84-00 

42*00 

13  51 

1213 

16-17 

68 

2 

0-243 

054 

2-78 

1-818 

24-24 

67-25 

124-00 

62-00 

19-94 

1341 

17-85 

73 

3 

0-243 

054 

2-78 

1-818 

24-24 

65-00 

128-00 

64-00 

20-59 

1338 

17-85 

73 

4 

0-230 

041 

2-78 

1-782 

23-76 

67-25 

128-00 

64*00 

20-59 

1385 

18-47 

77 

5 

0-225 

581 

2-78 

1-618 

21-57 

52-00 

134-00 

07-00 

21-56 

1421 

14-95 

69 

7 

0-245 

069 

2-78 

1-859 

24-78 

60-00 

142-00 

71-00 

22-85 

1371 

18-28 

73 

8 

0245 

009 

2-78 

1-859 

24*78 

57-25 

144-00 

72*00 

2315 

1326 

17-68 

71 

9 

0-248 

078 

2-78 

1-884 

2513 

50-00 

164-00 

82-00 

26-39 

1319 

17-59 

70 

General  Observations. — The  metre  is  3 feet  3 and  1-8  inches. 

It  will  be  observed  here,  that  only  a very  strong  change  in  the  speed  will  alter  the  percentage 
of  the  wheel.  The  large  wheel  was  in  bad  condition,  as  the  guide-wheel  rested  on  the  turbine  and 
created  friction. 


TABLE  OF  EXPERIMENTS,  made  6?/ Mr.  Theodore  Bippert,  on  the  Turbines  of  Messrs.  Geigy,  of  Steinen.  Duchy  of  Baden,  (These  Turbines  ucre  improved 

in  the  curves  of  the  wheels.) 


WATER-WHEELS. 


895 


General  Remarks. 

The  numbers  5 and  6, 
experiments  on  the  large 
Turbine,  show  that  the 
power  can  be  reduced  to 
one-fifth  without  greatly 
diminishing  the  percent- 
age 

The  coefficient  of  con- 
traction used  here  is  0'40, 
given  by  Mr.  Poncelet,  on 
overflows  discharging1  in 
the  open  air. 

Percentage  of  the  Turbine. 

d 

JT-  to 

0 0 0)0 
OD  CO  op  05 
O O O O 

to  to 

to  co  04  i— i Jr-  O 
9 a)  oo  co  9 p- 
© o © © © © 

Number  of  horse-power  indicated  by  the 
brake. 

Ph 

X 

1 

o 

to 

Jr- 

O O L—  > — 1 
to  p p P 
05  05  05 

04  c©  to  co  a 

CO  J-  (N  H r|i 

O O O O 04  04 

Weight  lifted  by  the  brake. 

pi 

t p O O O 
co  cb  to  o 
CO  CO  CO  CO 

to 

tC^  10)  j ^ 05 

CO  00  CO  CO 

Circumferential  velocity  of  the  brake  per 
second. 

P-, 

X 

o 

> 

60 

05  tO  CO  c© 

p p co 

05  OH  -H 
1—1  04  04  04 

Jr-  Jr-  —+•  co  co  to 
H 05  CO  CO  CQ  If 
04  04  lb  rH  05 

04  Ol  04  04  04  i— 1 

Number  of  revolutions  per  minute. 

CO  to  o o 
Jo-  Jr*  co  go 

CO  CO  CO  to  O H4 
GO  05  05  00  JT-  00 

Circumference  of  the  friction-brake. 

C© 

p 
■ cb 

r^i 

II 

o 

s 

16026 

H 

CO 

04 

O - - - - 51 

0 

Number  of  horse-power. 

MF 

O 

to 

XT- 

O O GO  H* 
p p Op 
rH  r— i 04  04 

O to  Jr  r H to 

H 04  rji  rji  00  ip 
04  04  04  04  OO  CO 

Height  of  the  fall. 

* 

rft  JT- 

0999 

to 

-H  CO  05  05  CO  CO 
p p p O Jr-  JT- 

Quantity  of  water  discharged  per  second. 

• 

O 

o 

II  X 

§ ° 
w 

i> 

litres. 

^ to  o co 
-+<  rH  to 

to  to  to  to 

litres. 

CO  CO  CO  CO  to  05 

to  0 to  to  CO 
to  to  to  to  1— 1 r- ( 

Width  of  the  overflow. 

G 

s 

4.09 

05 

0 s - - - - 

Theoretical  velocity  corresponding  to  the 
discharge  of  overflow. 

> 

S’ 

O to  JO  o 
r-  Jr-  Jr-  co 

oo  CO  oo  CO 

g 

0 0 0 0 0 to 

CO  CO  CO  GO  CO  H 
00  p 00  p 04  04 

Depth  of  discharge  on  the  overflow. 

W 

s 

0T780 

OT781 

0T782 

0T800 

£’ 

0 0 0 0 0 to 
cocococooor- 
--h  ' 0 0 

OOOOOO 

Number  of  Experiments. 

r-H  04  CO 

H 04  CO  rH  to  CO 

Small  Turbine.  Large  Turbine. 



89G 


WATER-WHEELS. 


H.  Amede  Rieder,  in  his  report  on  Jonval’s  turbine,  enumerates  the  following  as  its  advantages : 

1st.  Its  superior  mechanical  construction  and  simplicity. 

2d.  The  great  amount  of  power  obtained  from  the  quantity  of  water  used. 

Sd.  The  regularity  of  its  motion,  and  the  facility  of  access  to  it. 

4th.  The  great  practical  advantage  of  its  being  placed  at  the  top  of  the  fall. 

Experiments  have  been  made  on  a Jonval  turbine  at  the  powder-works  of  Messrs.  E.  J.  Dupont,  by 
Professor  C’resson,  and  Messrs.  Alfred  Dupont,  Alexis  Dupont,  S.  Y.  Merrick,  G.  Harding,  and  E.  Gey- 
elin,  members  of  the  Franklin  Institute.  The  following  is  the  report,  published  in  the  Journal  of  the 
Institute,  vol.  xx.,  No.  3,  1850. 

The  Koechlin  turbine. — The  hydraulic  motor  known  by  this  title  has  just  been  introduced  in  this 
vicinity  by  Mr.  E.  Geyelin,  at  the  powder-works  of  the  Messrs.  Dupont,  near  Wilmington,  Delaware,  and 
at  his  request  a trial  was  recently  made  by  certain  members  of  the  Institute,  to  determine  the  practical 
coefficient  of  the  wheel. 

The  turbine  experimented  upon  is  intended  to  produce  I horse-power  under  a fall  of  10.  feet,  and.  to 
drive  the  machinery  of  the  new  mixing  mill  at  the  lower  works.  It  is  21-J  inches  in  diameter,  3^  inches 
deep,  and  is  to  make  190  revolutions  per  minute,  giving  63J  revolutions  of  a horizontal  shaft,  to  which 
it  is  geered  3 to  1.  To  this  shaft  was  attached  a Prony  dynamometer,  whose  lever  was  7’96  feet  long, 
giving  50  feet  circumference.  At  the  time  of  the  experiments,  a wooden  box,  nearly  water-tight,  was 
placed  in  the  tail-race,  surrounding  tile  lower  part  of  the  wheel.  One  side  of  it  was  cut  away,  forming 
a waste-board  3’83  feet  wide,  over  which  the  water  was  discharged,  and  at  the  same  time  diminishing 
the  usual  head  and  fall  about  9 inches. 

Experiment  No.  1. — The  distance  between  the  level  of  water  in  the  penstock  or  forebay  and  that  of  the 
bottom  of  the  waste-board  was  10'  1",  and  the  depth  of  water  flowing  over  the  waste-board  8 J",  leaving 
the  actual  head,  and  fall  10'11,/  — 8 J"  = 9',  4§  = 9-34  feet.  By  Morin’s  formula,  {Aide  Memoire,  p.  37,) 
Q = m L h y/'2  z h ; Q being  discharge  per  second,  m the  constant,  which  for  -74  depth  = '383,  L = width 
of  waste-board,  = 3-83  feet,  and  h — depth  of  water  upon  it,  =-74.  Then  in  this  case  Q = '383  X 
3’88  X '74  y/  04  X '74  =7'468  cubic  feet,  and  the  theoretical  power  due  to  the  water  was  7'468  X 62'5 
X 9'34  X 60  = 261,537  lbs.  raised  1 foot  per  minute  = 7'92  horse-power. 

It  was  found  that  at  63  revolutions  per  minute  of  the  horizontal  shaft,  63  pounds  balanced  the  lever 
Hence  the  power  developed  by  the  wheel  was  63  X 63  X 50  = 198,450  lbs.  = 6'014  horse-power. 

Experiment  No.  2. — The  gates  from  the  head-race  were  so  far  closed  as  to  reduce  the  head  1 foot, 
and  maintain  it  at  that  level  during  the  experiment.  The  depth  of  water  on  waste-board  was  8J,/,  so 
that  the  head  and  fall  was  9'T"  — 8 J"  = 8'-4§"  = 8'41  feet.  Therefore,  by  the  same  formula,  in  being 
•39  for  this  depth,  Q = '39  X 3'83  X '677  ,/64  X '677  = 6'66  cubic  feet,  and  the  theoretical  power  due 
to  the  water  was  6'66  X 62'6  X 8'41  X 60  = 210,000  lbs.  raised  1 foot  per  minute  ==  6'36  horse-power. 

It  was  found  that  63  pounds  balanced  the  lever  at  49  revolutions  per  minute  of  the  shaft.  Hence 
the  power  developed  by  the  wheel  was  49  X 63  X 50  = 164-350  lbs.  = 4'98  horse-power. 

The  coefficients  are,  then,  for  experiment  No.  1,  = '760  per  ct. 


“ “ “ No.  2,  — =-783 

6'66 

And  making  allowance  for  leakage  around  the  waste-board  box,  which  was  partially  counterbalanced 
by  the  friction  of  the  geering  and  horizontal  shaft,  the  useful  coefficient  of  the  wheel  may  be  taken  at 
75  per  cent.,  and,  as  has  been  seen,  remains  the  same  when  the  wheel  is  working  at  5 horse-power, 
which  is  but  70  per  cent,  of  its  full  power. 

For  the  information  of  those  who  are  not  familiar  with  this  wheel,  it  may  be  stated  that  it  is  placed 
as  near  the  top  of  the  fall  as  possible,  and  revolves  within  a cast-iron  pipe  leading  below  the  level  of 
the  tail-race.  The  “ curved  guides”  are  directly  over  the  wheel,  and  may,  therefore,  be  easily  reached 
for  cleaning  or  repair  These  curved  guides  are  disposed  radially  around  a hub,  curving  spirally  around 
it  as  they  descend,  in  such  a manner  that  any  horizontal  linear  element  of  a ^uide  is  in  a radial  line 
drawn  from  the  axis.  The  buckets  of  the  wheel  are  similarly  curved,  but  in  an  opposite  direction. 

The  following  experiments  were  made  on  one  of  the  60-horse  power  turbines  of  Messrs.  Jessup  & 
Moore,  with  a dynamometer  of  Prony,  and  the  quantity  of  water  calculated  by  an  overflow  discharging 
in  the  open  air. 

JXCxW 

Effective  power  = S3Q00 — num^er  rev°luti°ns  Per  minute;  C,  circumference  of  the  lever; 

W,  the  weight  of  the  lever  and  balance. 

R = 104.  C = 80  feet.  W = 223-50  lbs. 


Effective  power 
Theoretical  power  of  the  water  = 


104  X 80  X 223-50 


33000 

Q X 62-5  X F 


= 56'30  horse-powei. 


33000 


Q,  number  of  cubic  feet  of  water  discharged 


through  the  wheel  per  minute.  62'5,  weight  in  pounds  of  the  cubic  feet  of  water.  F,  fall  of  the  water 
in  feet  and  fraction. 

The  quantity  of  water  was  measured  by  an  overflow  of  17 2‘87  5 inches  width.  The  depth  of  water 
discharging  through  it  was  13j-^-  inches.  This,  with  the  coefficient  of  contraction,  0’45,  adapted  by  Mr 
Poncelet  for  large  overflows,  gives  3794  cubic  feet  of  water  per  minute.  The  total  fall  during  the  op- 
eration of  the  turbine  was  8 feet  lOf  inches,  = 8-89  feet. 


WATER-WHEELS. 


897 


Hence  the  theoretical  power  is 


3794  X 62-5  X 8‘89 


33000 

88  coefficient  of  the  turbine. 


63'92  horse-power. 


Effective  power,  56'30  ) „ 

Theoretical  power,  63  92  j 
General  description  of  the  Jonval  Turbine. — Fig.  3823  represents  a vertical  section  of  a turbine.  A 
represents  the  movable  wheel , consisting  of  a cast-iron  rim,  having  a given  number  of  wrouglit-iron  buck- 
ets, of  the  proper  curve,  mortised  into  and  riveted  to  it,  and  occupying  the  space  marked  B ; it  is  keyed 
to  the  main  or  upright  shaft  C,  and  revolves  freely  in  the  cylinder  D,  the  outside  of  the  buckets  and  the 
cylinder  having  a small  space  between  them.  The  stationary  wheel  E consists  of  a cast-iron  rim,  hav 


ing  also  a given  number  of  wrouglit-iron  guides  mortised  into  and  riveted  to  it,  and  occupying  the  space 
F.  This  wheel  occupies  the  conical  part  of  the  cylinder,  just  above  the  movable  wheel,  with  sufficient 
space  between  them  to  allow  the  movable  wheel  to  revolve  freely.  The  upper  edges  of  the  guides  are 
level  with  the  upper  surface  of  the  flanch  of  the  cylinder.  The  upright  shaft  0 has  its  lower  bearing  or 
step  running  in  the  oil-box  H;  the  upper  bearing  C',  runs  in  a pedestal  attached  to  the  bridge  G.  This 
bridge,  made  of  cast-iron,  is  supported  on  some  of  the  cross  timbers  of  the  forebay,  and  supports  also 
the  pedestal  for  the  journal  of  the  line-shaft  J. 


3826. 


I 


The  oil-box  H,  is  supported  by  the  cast-iron  bridge  M,  which  rests  on  the  lugs  1ST  N,  on  the  inside  of 
the  cylinder.  The  gate  0,  resembling  a throttle-valve,  is  fastened  to  the  shaft  P,  which  works  in  stuff- 
ing-boxes, cast  in  the  cylinder.  To  one  end  of  this  shaft  a worm-wheel  is  attached,  which,  being  moved 
by  the  endless-screw  R,  opens  and  shuts  the  gate. 

Vol.  II— 57 


81)8 


WATER-WHEELS. 


The  screw  R is  moved  by  the  hand-wheel  or  governor  S.  The  cylinder  D D D,  cast  in  one  or  mor« 
pieces,  is  supported  by  the  timbers  T T.  U represents  a section  of  the  forebay  and  tail-race.  The  oil- 
box  is  filled  with  oil  through  the  gas-tube  a,  which  runs  from  the  top  of  the  forebay.  The  tube  marked 
b is  to  allow  the  air  to  escape  from  the  box  when  it  is  being  filled ; that  marked  c is  for  drawing  off  the 
oil  when  it  is  necessary  to  change  it.  Should  the  step  wear  any,  the  toe  can  be  changed  wifh  great 
facility.  The  oil-box  is  held  to  its  proper  position  in  the  bridge  by  set-screws  h h.  As  it  is  represented 
in  the  different  figures  of  this  article,  there  are  sometimes  wooden  steps  where  it  is  preferred. 


The  operation  of  the  wheel. — The  operation  of  this  wheel  is  very  simple ; the  top  of  the  cylinder  is 
placed  from  4 to  6 feet  from  the  upper  level  of  the  water,  or  at  a sufficient  distance  to  prevent  the 
water  from  becoming  agitated ; thus  it  will  be  seen  that  the  movable  wheel  or  turbine  is  suspended 
between  the  two  levels  of  the  fall.  The  water  is  made  to  come  on  the  wheel  and  leave  it  so  as  to  exert 


WATER-WHEELS. 


899 


its  utmost  effect  by  the  proper  construction  of  the  guides  and  buckets,  which,  together,  form  an  annular 
section.  The  following  is  the  action  of  the  water  discharging  through  the  wheels. 

The  water,  as  it  leaves  the  forebay,  follows  the  guides  of  the  stationary  wheel,  curved  in  a spiral 
form,  and  leaves  them  at  an  angle  of  16°  to  the  horizontal  line  and  tangential  to  the  circumference,  and 
thus  presses  on  the  movable  wheel,  which,  by  the  proper  course  of  its  buckets,  retrogrades  and  lets  the 


water  descend  in  a spiral  direction.  Then,  by  the  contracted  form  of  the  buckets  of  the  movable  whee., 
the  water  has  a second  action,  that  of  lifting  the  wheel  in  the  direction  of  18°  to  the  horizontal  line  and 
tangential  to  the  circumference ; this  second  action  is  upon  the  principle  of  discharge  of  water  through 
a conical  pipe,  and  has  the  effect  of  throwing  the  pipe  back. 

These  two  forces  are  in  the  proportion  of  10  to  1,  and  in  constructing  the  parallelogram  of  forces  in 
the  respective  directions,  the  diagonal  or  resultant  will  be  at  an  angle  of  11°  to  the  horizontal  line  and 
tangential  to  the  circumference. 


900 


WATER-WHEELS. 


The  water  discharged  through  this  contracted  space  falls  in  a large  air-tight  cylinder,  and  descends, 
partially  suspended  by  the  tendency  of  vacuum , to  the  tail-race.  The  following  is  the  effect  of  the  col 
umi.  of  water  on  the  wheel. 

As  mentioned  above,  the  column  of  action  on  these  kind  of  turbines  is  divided  into  two  distinct  ones- 
1st,  from  the  upper  level  of  the  fall  to  the  upper  part  of  the  turbine;  2d,  from  the  upper  part  of  this 
turbine  to  the  lower  level  of  the  fall. 


i 


The  first  part  of  the  column  operates  by  the  same  laws  as  in  ordinary  wheels,  that  is  to  say,  the 
quantity  of  water  multiplied  by  the  velocity  corresponding  to  the  height  of  the  fall.  The  second  part 
of  the  column,  that  is  to  say,  from  the  turbine  to  the  lower  part  of  the  fall,  would,  in  ordinary  wheels 
which  discharge  in  open  air,  be  of  no  additional  effect  to  the  wheel,  as  the  water  would  leave  this  point 
without  velocity,  and  would  only  fall  by  its  gravity ; but  by  this  peculiar  arrangement  of  excluding  the 
air  from  the  whole  column  by  means  of  an  air-tight  cylinder  immersed  in  the  lower  level  of  the  fall,  the 
water  passing  through  a contracted  part  of  the  air-tight  cylinder  discharges  in  a larger  part,  which  also, 
below,  has  a larger  discharge  than  admission  from  the  wheel. 

The  water,  consequently,  cannot  fill  the  wholu  space  of  the  cylinder  below  the  wheel,  and  the  ail 
would  rush  in  to  till  the  vacant  space,  but  this  element  being  completely  excluded,  the  tendency  to 


WATER-WHEELS. 


901 


form  a vacuum  keeps  the  column  of  water  suspended  to  the  proportion  of  the  height  to  that  of  perfect 
vacuum ; and  the  velocity  which  the  water  would,  through  its  gravity,  acquire  at  the  lowest  part  of  its 
fall,  would  be  communicated  to  the  upper  part,  where,  instead  of  pressure,  the  water  acts  as  suction. 

This  principle  is  true  as  far  as  the  tendency  of  vacuum  can  be  rendered  perfect,  (that  is  to  say,  to  the 
height  of  32  feet,)  and  thus  produce  by  suction  an  equal  in  effect  to  the  atmospheric  pressure  ; above 
this  the  surplus  of  pressure  would  force  air  in  the  column  from  below,  and  so  reduce  the  effect,  which, 
in  placing  the  wheel  below  32  feet  from  the  lower  level,  would  be  equal  to  pressure. 

Reduction  of  power  in  the  wheel. — The  difference  of  quantity  of  water  in  dry  and  wet  seasons,  and 
also  the  difference  of  power  used  in  certain  kinds  of  mills,  at  different  times,  in  the  working  operations, 
have  shown  that  it  is  necessary  for  these  iron  wheels  to  be  adaptable  to  these  changes. 

In  consequence  of  their  operating  with  much  higher  speed  than  wooden  wheels,  the  difference  of 
power  affects  its  operation  more  sensibly  if  there  is  no  means  to  regulate  it. 

Various  forms  of  gates  have  been  tried,  but  not  found  to  give  full  satisfaction.  In  these  wheels  there 
have  been  employed  a series  of  movable  divisions,  by  which  a part  of  the  inner  periphery  of  the  wheel 
is  inclosed,  and  the  whole  water  to  be  absorbed  is  thrown  to  the  external  periphery.  This  arrangement 
has  been  most  satisfactory  in  its  operation,  and  a wheel  used  for  60  horse-power  in  wet  seasons  can 
operate  at  40  horse-power  in  dry  seasons,  and  does  not  vary  in  its  percentage  more  than  5 to  6 per 
cent,  in  its  effect  by  this  change. 


It  will  require  only  half  an  hour  to  insert  these  divisions,  but  for  instant  change  of  speed  or  power, 
there  is  also  the  gate  by  which  one-fifth  of  its  power  can  be  taken  off  without  any  considerable  change 
in  effect. 

Advantages  obtained  by  these  wheels  over  other  first-class  wheels. — 1st.  In  consequence  of  its  suspen- 
sion between  the  two  levels  of  the  fall,  in  case  of  backwater,  the  power  only  changes  by  its  diminution 
of  fall,  but  should  the  fall  remain  the  same,  the  backwater  would  not  have  a bad  effect. 

2d.  As  expressed  above,  the  velocity  of  turbines  in  general  is  greater  than  that  of  wooden  wheels, 
and  in  all  factories  and  mills  where  a high  velocity  is  required,  the  amount  of  power  absorbed  in  the 
geering  is  gained,  and  the  use  of  greasing  and  chance  of  getting  out  of  order  is  greatly  lessened. 

3d.  As  shown  in  Figs.  3827,  3828,  and  3842,  the  water  can  ieave  the  wheel  at  any  angle,  even  to  the 
horizontal  line,  and  such  presents  very  great  advantages  where  there  exist  rocks  below,  or  quicksand, 
or  structures  which  could  not  be  removed  without  much  expense. 

4th.  By  the  position  of  the  stationary  wheel  placed  above  the  movable,  where  it  is  suspended  in  the 
conical  part  of  the  air-tight  cylinder,  and  its  only  being  kept  down  by  the  column  of  water  above  and 
its  own  weight,  it  cannot  present  the  chance  of  breaking  should  some  stick  or  stone  come  between  its 
plates,  as  would  be  the  case  in  Fourneyron’s  wheels,  which  are  bolted  to  their  respective  places.  A 
Jonval  turbine  will,  by  such  obstruction,  have  the  stationary  wheel  lifted  out  of  its  place.  In  other 
wheels,  where  the  guides  cannot  give  way,  the  division  plates  must  be  broken. 

5th.  In  breast,  pitchback,  and  overshot  wheels,  the  water  acts  partly  by  its  weight  and  partlv  by  the 
velocity  due  to  the  head  on  the  gates  of  discharge,  on  the  wheel,  and  on  this  account  loses  a head  of 
water  equal,  first,  to  the  half  of  the  head  on  the  gate  ; second,  the  depth  of  the  buckets  on  the  wheel 
itself.  In  turbine  wheels  this  is  not  the  case,  as  the  full  fall  is  utilized. 

6th.  In  case  of  repair  this  wheel  can  be  rendered  instantly  dry  and  accessible,  while  all  other  iron 
wheels,  acting  only  by  pressure,  are  submerged,  and  in  order  to  reach  the  wheel  the  watci  nas  to  be 
pumped  out  of  the  tail-race. 


002 


WEIGHTS  AND  MEASURES. 


Tlie  Jonval  turbines  are  guarantied  to  give,  1st,  *75  per  cent,  of  its  effect  with  a fall  fiom  30  feet  and 
above  clown  to  12  feet.  2d,  TO  per  cent,  of  its  effect  with  a fall  from  12  feet  to  6 feet,  fed,  60  per 
cent,  of  its  theoretical  effect  from  6 feet  to  4 feet. 

These  wheels  are  built  by  Mr.  E.  Geyelin,  Philadelphia. 

Figs.  3827  and  3828,  elevation  and  plan  of  a 15  horse-power  turbine,  built  by  E.  Geyelin  for  Mr.  Le 
Carpentier,  Philadelphia.  Fig.  3824,  section  of  the  turbine-wheel  of  the  same. 

Figs.  3840  and  3841,  plan  and  elevation  of  a turbine  of  50  horse-power,  22  feet  fall,  in  operation  in 
the  paper-mill  of  Messrs.  Manning,  Peckham,  A Howland,  of  Troy,  New  York,  built  at  the  West  Point 
Foundry,  by  E.  Geyelin. 

Fig.  3842,  turbine  built  at  the  powder-works  of  the  Messrs.  Dupont,  Wilmington,  Delaware. 

Fig.  3843,  turbine  built  for  the  Fairmount  Water-works  of  Philadelphia. 

WEIGHTS  AND  MEASURES.  The  weights  and  measures  of  this  country  are  identical  with 
those  of  England.  In  both  countries  they  repose,  in  fact,  upon  actually  existing  masses  of  metal  (brass) 
which  have  been  individually  declared  by  law  to  be  the  units  of  the  system.  In  scientific  theory  they 
are  supposed  to  rest  upon  a permanent  and  universal  law  of  nature — the  gravitation  of  distilled 
water  at  a certain  temperature,  and  under  a certain  atmospheric  pressure.  And  in  this  aspect,  the 
origination  is  with  the  giains,  which  must  be  such,  that  252,458  of  these  units,  in  brass,  will  be  in  just 
equilibrium  with  a cubic  inch  of  distilled  water,  when  the  mercury  stands  at  30  inches  in  a barometer, 
and  in  a thermometer  of  Fahrenheit  at  62  degrees,  both  for  the  air  and  for  the  water.  Unfortunately, 
the  expounders  of  this  theory  in  England  used  only  the  generic  term  brass,  and  failed  to  define  the 
specific  gravity  of  the  metal  to  be  employed ; the  consequence  of  this  omission  is  to  leave  room  for  an 
error  of  jq^ViTo  'n  ever)'  attempt  to  reproduce  or  compare  the  results.  This  is  the  minimum  possible 
error : the  maximum  would  be  a fraction  of  the  difference  in  specific  gravity  between  the  heaviest  and 
lightest  brass  that  can  be  cast. 

Length. — 1 yard  = 3 feet  = 36  inches  = 432  lines  = 5184  seconds  = 62,208  thirds. 

In  the  actual  government  standards  at  the  custom-houses,  the  yard  is  divided  decimally  into  tenths 
and  hundredths. 

In  the  measurement  of  cloths,  muslins,  linens,  cottons,  silk,  and  in  general  of  what  are  termed  dry 
mods,  the  yard  only  is  .used — subdivided  into  halves,  quarters,  eighths,  sixteenths,  and  half-sixteenths. 
This  lowest  denomination  = IT 25  inch. 

Surveyors  and  engineers  employ  neither  the  yard  nor  the  inch,  but  use  the  foot  and  its  decimal 
divisions. 

Architects  and  artificers  reckon  by  the  foot  and  subdivisions,  as  given  above.  Nevertheless,  the  most 
usual  and  most  recent  workmen’s  scales  bear  the  foot  divided  into  inches,  and  eighths  and  sixteenths 
of  an  inch. 

Mariners  measure  by  cable-lengths  and  fathoms : 

1 cable-length  = 120  fathoms  = 240  yards  = 720  feet. 

The  unit  of  length — the  yard,  upon  whose  subdivisions  all  the  weights  and  capacity  measures  repose 
for  verification — is,  in  fact,  derived  from  ancient  arbitrary  standards  of  England.  In  theory,  the  inch — 
the  l-36th  of  the  yard — is  presumed  to  be  contained  39T3929  times  in  the  length  of  a pendulum  that, 
in  a vacuum,  and  at  the  level  of  mid-tide,  under  the  latitude  of  London,  vibrates  seconds  of  mean  time. 

Itinerary. — 1 statute  mile  = 2 half  miles  = 4 quarter  miles  = 7J  cable-lengths  = 8 furlongs  = 80 
chains  = 320  perches  or  poles  = 880  fathoms  = 1760  yards  = 5280  feet  = 8000  links  = 63,360  inches. 

1 nautical  league  = 3 equatorial  miles  = 3457875  statute  miles. 

Chains  and  links  are  denominations  employed  by  land  surveyors,  thus  : 

1 chain  = 4 poles  = 66  feet  = 100  links. 

Agrarian  and  superficial. — 1 square  mile  = 640  acres. 

1 acre  = 4 roods  = 10  square  chains  = 160  square  perches  = 4840  square  yards  = 43,560  square  feet 
1 square  yard  = 9 square  feet  = 1296  square  inches. 

Architects  and  builders  reckon  1 square  = 100  square  feet. 

Liquid  capacity. — 1 gallon  = 2 half  gallons  = 4 quarts  = 8 pints  = 16  gills. 

The  gill  is  not  among  existing  standards  of  public  authority,  though  it  is  used  in  commerce.  There 
are  other  denominations  higher  than  the  gallon,  such  as  barrels,  hogsheads,  pipes,  etc.,  but  these  are 
only  vessels,  not  measures,  and  are  always  gaged  and  sold  by  their  actual  capacity  in  gallons.  The 
gallon,  in  fact,  is  almost  exactly  equivalent  to  a cylinder  7 inches  in  diameter  and  6 inches  high.  In 
theory,  it  must  contain  just  231  cubic  inches ; and,  filled  with  distilled  water  at  the  temperature  of  maxi- 
mum density,  (say  39°-8  Fall.,)  weighs,  according  to  the  official  report,  at  that  temperature,  and  at  30 
inches  of  the  barometer,  8339  commercial  or  avoirdupois  pounds;  or,  more  nearly,  58372T754  grains. 
It  is  in  the  temperature  only  that  this  unit  differs  from  the  former  wine-gallon  of  Great  Britain. 

The  apothecaries  use  the  same  gallon,  but  divide  it  differently,  as  follows : 

1 gallon  = 8 pints  = 128  fluid  ounces  = 1024  fluid  drachms  = 61,440  minims  (or  drops)  = 231 
cubic  inches. 

These  are  graduated  measures  : they  also  use  sometimes  the  following  approximate  ones  from  vessels 
in  domestic  use : 

1 tea-cup  = 2 wine-glasses  = 8 table-spoons  = 32  tea-spoons  = 4 fluid  ounces. 

Dry  capacity. — 1 bushel  = 2 half  bushels  = 4 pecks  = 8 gallons. 

There  are  also  in  this,  as  in  the  former  measure,  higher  denominations  (barrels,  sacks,  etc.)  known  in 
commerce,  wdiose  capacity  is  intended  to  be  constant.  They  are,  however,  always  gaged  by  the 
bushel.  This  bushel  is  the  old  Winchester  bushel  of  England.  In  fact,  it  is  a cylinder  18:5  inches  in 


WEIGHTS  AND  MEASURES. 


908 


diameter,  and  8 inches  deep.  In  theory,  it  must  contain  2150-42  cubic  inches,  and  holds,  of  distilled 
water  at  the  temperature  of  maximum  density,  and  at  30  inches  of  the  barometer,  77  6274  commercial 
or  avoirdupois  pounds;  or,  more  nearly,  543391-89  grains. 

Solid. 

1 cubic  yard  = 27  cubic  feet  = 46,656  cubic  inches. 

1 cubic  foot  = 12  reduced  feet  (plank  measure)  = 1728  cubic  inches. 

1 reduced  foot  (plank  measure)  = 1 square  foot  X 1 inch  thick  = 144  cubic  inches. 

In  practice,  all  planks  and  scantlings  less  than  an  inch  in  thickness  are  reckoned  at  an  inch. 

1 perch  of  masonry  = 1 perch  (164  feet)  long  X 1 foot  high  X 14  foot  thick  = 25  cubic  feet. 

In  fact,  the  dimensions  given  for  the  perch  do  not  result  in  25  cubic  feet,  but  this  last  number  ha.* 
been  adopted  for  convenience. 

1 cord  of  fire-wood  = 8 feet  long  X 4 feet  high  X 4 feet  deep  = 128  cubic  feet. 

Weight. 

1 mint  or  troy  pound  = 12  ounces  = 240  pennyweights  = 5760  grains. 

1 apothecary  pound  = 12  ounces  = 96  drachms  = 288  scruples  = 5760  grains. 

1 commercial  pound  = 16  ounces  = 256  drachms  = 7000  grains. 

1 long  ton  = 20  cwt.  = 80  quarters  = 2240  commercial  pounds. 

1 short  ton  = 20  hundred  weight  = 2000  commercial  pounds. 

In  the  actual  government  standards  the  ounce  troy  is  divided,  decimally,  down  to  the  part. 


TABLES  OF  UNITED  STATES  WEIGHTS  AND  MEASURES. 


MEASURES  OF  LENGTH. 


12 

inches 

Inches. 

Feet. 

Yards.  Rods.  Furl. 

3 

feet 

— 1 yard. 

36  = 

3. 

H 

yards 

198  = 

164 

= 54. 

40 

rods 

7920  = 

660 

= 220  = 40. 

8 

furlongs . . 

63360  = 

5280 

= 1760  =320  = 8. 

Gunter's  Chain. 

Bop 

es  and  Cables. 

7-92 

inches 

. — 1 link. 

6 feet.. 

— 1 fathom. 

100 

links 

. — 4 rods,  or  22  yards. 

120  fathoms  . ... 

Geographical  and  Nautical  Measure. 

1 degree  of  a great  circle  of  the  earth ■. = 69-77  statute  miles. 

1 mile = 2046-58  yards. 


Log  Lines. 

1 knot.'..... = 51-1625  feet,  or  5'  feet  If  + inches. 

1 fathom = 5-11625  feet,  or  6 feet  1J  -f-  inches. 

Estimating  a mile  at  61394  feet,  and  using  a 30"  glass.  If  a 28'  glass  is  used,  and  eight  divisions,  then 

1 knot =47  feet  9 -j-  inches. 

1 fathom....... = 5 feet  Ilf  inches. 

The  line  should  be  about  150  fathoms  long,  having  10  fathoms  between  the  chip  and  first  knot  for 
stray  line. 

Note. — Bowditch  gives  6120  feet  in  a sea  mile,  which,  if  taken  as  the  length,  will  make  the  divisions 
51  feet  and  5 1-10  feet. 

Cloth. 

1 nail = 2f  inches = l-16th  of  a yard. 

1 quarter :....=4  nails. 

6 quarters =1  ell  English. 

Pendulums. 

6 points = 1 line. 

12  lines = 1 inch. 

Shoemakers'. 

No.  1 is  4 J inches  in  length,  and  every  succeeding  number  is  § of  an  inch. 

There  are  28  divisions,  in  two  series  of  numbers,  viz.,  from  1 to  13,  and  1 to  15. 


Circles. 

60  seconds = 1 minute. 

60  minutes = 1 degree. 

360  degrees = 1 circle. 

1 day  is 

1 minute  is 


n 


3600  = 60. 
1296000  = 21600. 
•002739  of  a year. 
•000694  of  a day. 


Miscellaneous. 

1 palm = 3 inches.  I 1 span = 9 inches. 

1 hand =4  inches.  | 1 metre. = 3-28174  feet. 

The  standard  of  measure  is  a brass  rod,  which,  at  the  temperature  of  ? 2°  Fahrenheit,  is  tho 
standard  yard. 


904 


WEIGHTS  AND  MEASURES. 


1 yard  is . ‘000568  of  a mile. 

1 inch  is ‘0000158  of  a mile. 


MEASURES  OF  SURFACE. 

144  square  inches = 1 square  foot. 

9 square  feet — 1 square  yard. 

Land. 


Inches. 

1296. 


Yards.  Rods.  Roods. 

1210. 

4840  = 160. 

8097600  = 102400  = 2560. 


30}  square  yards = 1 square  rod. 

40  square  rods = 1 square  rood. 

4 square  roods  ) , 

^ ,.  V = 1 acre. 

1 0 square  chains  ) 

640  acres = 1 square  mile. 

Note. — 208'710321  feet,  69‘5701  yards,  or  220  by  198  feet  square  = 1 acre. 

Paper. 

24  sheets = 1 quire.  I Sheets. 

20  quires = 1 ream.  | 480. 

Drawing  Paper. 


Cap 

Columbier 

..  33}  X 

23  inches 

Demy 

19}X15}  “ 

Atlas 

. 33  X 

26  “ 

Medium 

22  X 18  “ 

Theorem 

. 34  X 

28  “ 

Royal 

24  X 19  “ 

Double  Elephant.. 

.40  X 

26  “ 

Super-royal 

27  X 19  “ 

Antiquarian 

. 52  X 

31  “ 

Imperial 

29  X 211  “ 

Emperor 

..40  X 

60  “ 

Elephant 

27}  X 22}  “ 

Uncle  Sam 

..48  X 

120  ‘ 

MEASURES  OF  CAPACITY. 

Liquid. 

■ 1 pint. 


Gills.  Pints. 


32  = 


Pints.  Qrts.  Galls. 


16  = 8. 

64  = 32  = I 


4 gills 

2 pints = 1 quart. 

4 quarts = 1 gallon. 

Dry. 

2 pints = 1 quart. 

4 quarts = 1 gallon. 

2 gallons = 1 peck. 

4 pecks = 1 bushel. 

United  States  standard  bushel. — The  standard  bushel  is  the  Winchester,  which  contains  2150’43 
cubic  inches,  or  77'627413  lbs.  avoirdupois  of  distilled  water  at  its  maximum  density. 

Its  dimensions  are  184  inches  diameter  inside,  19}  inches  outside,  and  8 inches  deep;  and  whet 
heaped,  the  cone  must  not  be  less  than  6 inches  high,  equal  2747‘70  cubic  inches  for  a true  cone. 

1728  cubic  inches = 1 foot.  I Inches. 

27  cubic  feet = 1 yard.  | 46656 

Miscellaneous. 

1 chaldron  = 36  bushels,  or 57'25  cubic  feet. 

1 cord  of  wood 128  cubic  feet. 

1 perch  of  stone 24‘7  5 cubic  feet. 

MEASURES  OF  WEIGHT. 

Avoirdupois. 

16  drachms = 1 ounce.  1 Drachms.  Ounces.  Pounds. 

16  ounces = 1 pound.  | 256. 

112  pounds = 1 cwt.  28672  = 1792. 

20  cwt = 1 ton.  573440  = 35840  = 2240 


1 lb. 


= 14  oz.  11  dwt.  16  gr.  troy. 


Dwt. 


Troy. 

24  grains = 1 dwt. 

20  dwt = 1 ounce. 

12  ounces = 1 pound. 

Apothecaries'. 

20  grains = 1 scruple. 

3 scruples = 1 drachm. 

8 drachms =1  ounce. 

12  ounces = 1 pound. 

Diamond. 

16  parts = 1 grain = 0’8  troy  grains. 

4 grains = 1 carat = 3 2 “ 


Grains. 

480. 

5760  = 240. 


Grains.  Scruples.  Drachms. 
60. 

480  = 24. 

5760  = 288  = 96. 


WEIGHTS  AND  MEASURES. 


905 


WOO  troy  grains = 1 lb.  avoirdi  pois. 

175  troy  pounds = 144  lbs.  “ 

175  troy  ounces = 192  oz. 

437  i troy  grains = 1 oz. 

1 troy  pound = '8228  + lb-  “ 


Miscellaneous. 


1 cubic  foot  of  anthracite  coal  from . 
1 cubic  foot  of  bituminous  coal  from 


1 cubic  foot  Cumberland  coal = 53  lbs. 

1 cubic  foot  charcoal = 18-5  “ 

1 cubic  foot  charcoal = 18  “ 

1 cord  Virginia  pine =2700  “ 

1 cord  Southern  pine = 3300  “ 

1 stone — 14  “ 


50  to  55  lbs. 
45  to  55  lbs, 

(hard  wood), 
(pine  wood). 


Coals  are  usually  purchased  at  the  conventional  rate  of  28  bushels  (5  pks.)  to  a ton  = 43’56  cubic  feet 


MEASURES  OF  VALUE. 

1 eagle = 258  troy  grains. 

1 dollar =412-5 

1 cent = 168  “ 

The  standard  of  gold  and  silver  is  900  parts  of  pure  metal,  and  100  of  alloy,  in  1000  parts  of  coin. 


MEASURES  OF  LENGTH. 

British. — Yard  is  referred  to  a natural  standard,  which  is  the  length  of  a pendulum  vibrating  sec- 
onds in  vacuo  in  London,  at  the  level  of  the  sea ; measured  on  a brass  rod,  at  the 
temperature  of  62°  Fahrenheit,  = 39-1393  inches. 


French.  Old  system. — 1 Line — 12  points. 


Inch . 

Foot 

Toise  . .. 
League 


= 12  lines. 

= 12  inches.... 

= G feet 

= 2280  toises 
= 2000  toises 
= 5 feet. 


1 League 
1 Fathom 

“ New  system. — 1 Millimetre 

1 Centimetre  

1 Decimetre 

1 Metre 

1 Decametre  

1 Hecatometre 

Austrian 1 Foot 

Prussian 1 Foot 

Swedish 1 Foot 

SrANisH 1 Foot 

1 League  (common) 


0'08884  United  States  inches 
1-06604 

12-7925  “ “ 

76-755 
(common). 

(post). 


•03938 
•39380 

3-93809  “ 

39-38091  “ 

393-80917  “ 

3938-09171 
12-448 
12-361 
11-690 
11-034 

3-448  United  States  miles. 


Table  showing  the  relative  length  of  Foreign  Measures  compared  with  those  of  the  United  States. 


Places. 

Measures. 

Inches. 

Places. 

Measures. 

Inches. 

Amsterdam  ... 

Foot 

11-14 

11-24 

11- 42 

12- 19 
11-38 

11- 45 

13- 12 

12- 71 

13- 32 
12-58 
12-35 

11- 14 
1200 
21-60 

12- 79 
39-381 
19-20 

9-72 

11-29 

11- 45 
11-11 

12- 96 
8p64 

Malta  

Foot 

11- 17 
13-17 
10-38 

12- 36 
38-27 

12- 35 

10- 79 

11- 60 

13- 75 
9-78 
9-53 

11-03 

66-72 

8-34 

11-39 

11- 69 

12- 72 

13- 40 
12-45 
11-81 
10-74 
14.03 

it 

Palmo 

Berlin 

ll 

Foot 

Bremen 

it 

Arish  

it 

Foot 

“ Mathematician’s 
“ Builders 

Rome  

« 

« 

“ Tradesman’s... 
“ Surveyor’s  

a 

u 

a 

Palmo 

Copenhagen  ... 

Sicily 

ti 

Foot 

it 

a 

Strasburgh 

Sweden 

Foot 

Turin 

« 

Venice  

a 

Hamburgh 

u 

u 

u 

tt 

a 

tt 

DOG 


WEIGHTS  AND  MEASURES. 


Table  showing  the  relative  length  of  Foreign  Road  Measures  compared  with  those  of  the  United 

States. 


Places. 

Measures. 

Yards. 

Places. 

Measures. 

Yards. 

Arabia  

Mile  

2148 

Hungary 

Mile  

9113 

Bohemia 

‘t 

10137 

3038 

China  

Li  

629 

« 

1093 

Denmark 

Mile  

8244 

Persia  

Parasang  

6086 

England  

“ Statute  

1760 

Poland  

Mile,  long 

8101 

“ 

“ Geographical. 

2025 

Portugal 

League 

6760 

Flanders 

U 

6869 

Mile  

8468 

6075 

2025 

4861 

1167 

u 

4264 

1984 

10126 

7416 

8244 

Mile  ...' 

11700 

il 

11559 

9153 

Holland 

ll 

6395 

1826 



— 

Measures  of  Surface. 


French. 


Old  system. — 1 Square  Inch 

1 Arpent  (Paris)  

1 Arpent  (woodland) 

New  system. — 1 Are 

1 Decare 

1 Hecatare  

1 Square  Metre 

1 Are 


= 1‘1 364  United  States  inches. 

= 900  square  toises. 

=•100  square  royal  perches. 

= 100  square  metres. 

= 10  ares. 

= 100  ares. 

= 1550-85  square  inches,  or  10-7698  sq.  ft 
= 1076-98  square  feet. 


Table  showing  the  relation  of  Foreign  Measures  of  Surface  compared  with  those  of  the  United  States 


Places. 

Measures. 

Sq.  yards. 

Places. 

Measures. 

Sq.  yards. 

Amsterdam  ... 

Morgen 

9722 

Portugal 

Geira  

6970 

Berlin  

“ great  

6786 

Prussia 

Morgen 

3053 

U 

3054 

3158 

Canary  Isles... 

9490 

13066-6 

4840 

Acre 

6150 

6179 

Fanegada 

5500 

Hamburgh  

Morgen 

11545 

Sweden 

Tunneland  

5900 

3100 

Faux 

Ireland 

Acre 

7840 

Vienna 

Joch 

6889 

3998 

Common  acre 

3875-6 

Measures  of  Capacity. 

British.  The  Imperial  gallon  measures  277-274  cubic  inches,  containing  10  lbs.  avoirdupois  of 
distilled  water,  weighed  in  air,  at  the  temperature  of  62°,  the  barometer  at  30  inches 
For  Grain.  8 bushels  = 1 quarter. 

1 quarter  = 10’2694  cubic  feet. 

Coal,  or  heaped  measure.  3 bushels  = 1 sack. 

12  sacks  = 1 chaldron. 

Imperial  bushel  = 2218-192  cubic  inches. 

* Heaped  bushel,  19-^  inches  diameter,  cone  6 inches  high  = 2815  4872  cubic  inches. 

1 chaldron  = 58'658  cubic  feet,  and  weighs  3136  pounds. 

1 chaldron  (Newcastle)  = 5936  pounds. 

French.  New  system. — 1 Litre  = 1 cubic  decimetre,  or  6P074  U.  S.  cubic  inches. 

Old  system. — 1 Boisseau  = 13  litres  = 793'964  cubic  inches,  or  3'43  gallons. 

1 Pinte  = 0-931  litres,  or  5 6 ’8 17  cubic  inches. 

Spanish.  1 Wine  Arroba  = 4-2455  gallons. 

1 Fanega  (common  measure)  = 1'593  bushels. 


* When  heaped  in  the  form  of  a true  cone. 


WEIGHTS  AND  MEASURES. 


907 


Table  showing  the  relative  Capacity  of  Foreign  Liquid  Measures  compared  with  those  of  the 

United  States. 


Places. 

Measures. 

Cub. inch. 

Places. 

Measures. 

Cub.  inch. 

Amsterdam  ... 

Anker. 

2331 

Naples  

Wine  Barille  

2544 

« 

146 

1133 

194 

Oporto 

1555 

Bordeaux 

Barrique 

14033 

Rome  

Wine  Barille  

2560 

Bremen 

194-5 

Oil  “ 

2240 

949 

a 

80 

Constantinople 

Almud 

319 

Russia 

Weddras  

752 

Copenhagen  ... 
Florence  

2355 

94 

Oil  Barille  

1946 

Scotland 

Pint  

103-5 

U 

2427 

Sicily 

662 

61-07 

22'5 

Setier  

2760 

30-5 

Genoa 

Wine  Barille  

4530 

Sweden 

Eimer 

4794 

Pinte 

90-5 

Trieste 

4007 

Hamburgh  

Stubgen  

221 

Tripoli 

Mattari  

1376 

231 

Oil  “ 

1157 

628 

Hungary 

Eimer 

4474 

Venice 

Seccliio 

Leghorn  

Oil  Barille  

1942 

Vienna  

Eimer 

3452 

Lisbon 

Almude  

1040 

« 

86-33 

Malta  

Caffiri 

1270 

Table  showing  the  relative  Capacity  of  Foreign  Dry  Measures  compared  with  those  of  the  United 

States. 


Places. 

Measures. 

Cub.  inch. 

Places. 

Measures. 

Cub.  inch. 

Alexandria 

Rebele 

9587 

Malta  

Salme 

16930 

“ 

Kislos 

10418 

Marseilles  

Charge 

9411 

Algiers 

Tarrie 

1219 

Milan 

Moggi 

8444 

Amsterdam  ... 

Mudde  

6596 

Naples 

Tomoli  

3122 

Sack 

4947 

Oporto. .' 

Alquiere 

1051 

Antwerp 

Viertel 

4705 

Persia 

Artaba 

4013 

Azores 

Alquiere 

731 

Poland  

Zorzec 

3120 

Berlin  

Scbeffel 

3180 

Riga  

Loop 

3978 

Bremen 

4339 

16904 

Candia  

Charge 

9288 

49.0fi 

Constantinople 

Kislos 

2023 

Rotterdam  .... 

Sach 

6361 

Copenhagen  ... 

Toende 

8489 

Russia 

Chetwert 

12448 

Corsica  

Stajo 

6014 

Sardinia  

Starelli 

2988 

Florence  

Stari 

1449 

Scotland " 

Firlot  

2197 

Geneva 

Coupes 

4739 

91  014 

Genoa  

Mina 

7382 

1 

Greece  

Medimni 

2390 

Smyrna 

Kislos 

2141 

Hamburgh 

Scheffel., 

6426 

Spain 

Catrize 

41269 

Hanover 

Malter  

6868 

Sweden 

Tunnar  .1 

8940 

Leghorn  

Stajo 

1501 

Trieste 

Stari 

4521 

“ 

Sacco  

4503 

19780 

Lisbon 

Alquiere 

817 

21  855 

Fanega 

3268 

4945 

Madeira 

Alquiere 

684 

Vienna  

Metzen 

3753 

Malaga 

Fanega 

3783 

French. 


Measures  of  Solidity. 

1 Cubic  foot 

Decistre 

Stere  (a  cubic  metre) 

Decastere 

1 Stere 


= 2093-470  U.  S.  inches. 
= 3-5375  cubic  feet. 

= 35'375  “ 

= 353-75 

= 6107T1564 


Measures  of  Weight. 

British 1 troy  Grain  ==  .003961  cubic  inches  of  distilled  water. 

1 troy  Pound  = 22-815689  cubic  inches  of  water. 

French.  Old  system. — 1 Grain = 0-8188  grains  troy 

1 Gros = 58-9548  “ 

1 Once = 1 0780  oz.  avoirdupois. 

1 Livre  = 1-0780  lbs.  “ 


908 


WHEELS. 


Measures  of  Weight- 

French.  New  system. — Milligramme 

Centigramme  


-Continued. 

= "01543  troy  grains. 

— "15433 

= 1-54331 

= 15-43315 

= 154-33159 

= 1543-3159 


Decigramme  

Gramme 

Decagramme  

Hecatogramme 

1 Millier  = 1000  Kilogrammes  = 1 ton  sea  weight. 


Spanish  ... 
Swedish  . 
Austrian  . 


1 Kilogramme 

1 Pound  avoirdupois 

1 Pound  troy  

. 1 “ 

. 1 “ 

. 1 “ 


Prussian  1 


2’20 4737  lbs.  avoirdupois. 
0-4535685  kilogramme. 

0- 3732223 

1- 0152  lbs.  avoirdupois. 

0- 9376 

1- 2351 
1-0333 


Note. — In  the  new  French  system,  the  values  of  the  base  of  each  measure,  viz.,  Metre,  Litre,  St  era, 
Are,  and  Gramme,  are  decreased  or  increased  by  the  following  words  prefixed  to  them.  Thus, 


Milli  expresses  the  1 000th  part. 

Centi  “ “ 100  th  “ 

Deci  “ “ 10  th  “ 

Deca  “ “ 10  times  the  value. 


Hecato  expresses  100  times  the  value. 

Chilio  “ 1000 

Myrio  “ 10000  “ 


Table  showing  the  relative  value  of  Foreign  Weights  compared  with  those  of  the  United  States. 


Places. 

, Weights. 

Number 
equal  to 
100  avoir- 
dupois 
pounds. 

Places. 

Weights. 

Number 
equal  to 
100  avoir- 
dupois 
pounds. 

Rot  toll  

2046 

93-20 

Oke 

35*80 

Catty  

76-92 

Rottoli 

107- 

Pound 

133-56 

84- 

“ (common)... 
“ (silk) 

97-14 

Amsterdam  ... 

Pound  

9P8 

Lyons  

98-81 

143-20 

112*6 

Maund  

33-33 

Batavia 

Catty  

70-78 

Morea 

Pound 

90-79 

Bengal  

Berlin  

Seer  

53-57 

Naples  

Rottoli  

5091 

Pound 

96-8 

Rome  

Pound 

133-69 

125*3 

91-80 

« 

90*93 

« 

110-86 

« 

97*14 

Sicily 

(4 

142-85 

105* 

Oke 

85-9 

Catty  

Pound 

106-67 

Constantinople 
Copenhagen  ... 

Oke. 

3555 

120-68 

Pound 

90-80 

Tangiers  

“ (miner’s) 

94-27 

131-72 

Rottoli 

89-28 

19-07 

9009 

25-28 

Pound  (heavy) 

94-74 

133.56 

“ (light)! 

150- 

82*35 

81- 

92-86 

« 

112-25 

Hamburgh 

“ “ 

93.63 

To  convert  English  Imperial  gallons  into  United  States  gallons,  multiply  by  1-20032.  And  to  con- 
cert United  States  gallons  into  English  Imperial  gallons,  multiply  by  -83311. 

For  an  extended  view  of  the  various  systems  of  weights  and  measures  in  use,  see  a work  on  this 
subject  by  Professor  J.  H.  Alexander,  of  Baltimore. 

WHEELS.  Under  this  head  we  give  a few  of  the  best  forms  of  railroad-car  wheels  in  use.  Se« 
also  A ppendix. 


3844— g.  Hawks’  patent,  1807.  3845,  3846— W.  Losh  & G.  Stephenson’s  patent,  1816. 


WHEELS. 


DO[J 


3858 — B.  Hicks’  patent,  1834. 


3859 — R.  Whiteside’s  patent,  1834. 


3860— W.  B.  Adams’  patent,  1835. 


38G1 — I.  Day’s  patent,  1835. 


3862— R.  R.  Reinagle’s  patent,  1836. 


3863 — H.  Van  Wart’s  patent,  1830. 


38CG — G.  Cottam’s  patent,  1837 


3869 — J.  Grimes’  patent,  1838. 


910 


WHEELS. 


3870.  ...I  F.  Rnurne  & I.  Bartley’s  patent,  .838. . .3871. 


3872—1.  Rivington,  1839. 


3885 1.  O.  Young 3886 Patented  in  1811 3887. 


WHEELS. 


911 


3891 VV.  Losh 


3892 Patented  in  1842 3893. 


3894— T.  Banks’  patent,  1842 


3903 Thomas  Melling 3904 


Patented  in  184G 3905. 


3908 — H.  Grafton’s  patent,  1847, 


3909 — B.  P.  Stratton’s 


patent,  1847 


3910— F.  Abate,  registered  in  (847.  3911-F.  Chaplin’s  patent,  1847. 


912 


WHEELS,  PADDLE. 


3912 — VV.  E.  Newton’s  patent,  1847. 


3913 — G.  Stephenson  & Co. 


3914— Locomotive-engine  wheel. 


3915 — I.  G.  Bodmer,  1842. 


3918 — Bristol  and  Exeter  Railway,  1840. 


WHEELS,  PADDLE,  the  wheels  employed  in  the  propulsion  of  steamboats.  Common  paddle- 
wheels  mostly  consist  of  iron  framing,  supporting  paddle-boards  or  floats  fixed  at  equal  distances  around 
the  rim,  and  radiating  from  the  centre ; they  are  placed  one  upon  each  side  of  the  vessel,  and  are  se- 
cured to  a strong  shaft  passing  across  it,  which  is  turned  round  by  the  engines,  each  engine  working  a 
crank  fixed  upon  it ; and  are  placed  at  right  angles  to  each  other.  Fig.  3920  represents  the  common 
paddle-wheel. 


3920. 


3923. 


There  is  a supposed  loss  of  power  attending  this  description  of  wheel,  on  account  of  only  one  of  the 
floats  striking  the  water  in  a vertical  position  at  the  same  time,  the  action  of  the  others  being  oblique; 
some  of  them,  in  fact,  backwater,  or  partially  oppose  the  motion  of  the  vessel.  Attempts  have  been  made 
to  obviate  these  defects  by  constructing  improved  wheels,  the  paddles  of  which  maintain  a vertical  po- 
sition in  their  passage  through  the  water,  when  in  front  of  the  wheel,  by  having  feathering  floats,  and 
these  are  called  vertical paddle-wheels.  Figs.  3921  and  3922  represent  a section  and  elevation  of  the 
vertical  paddle-wheels  of  the  “ Medea.”  They  have  been  found  to  answer  well  for  sea-going  packets, 
where  the  paddle-wheels  are  deeply  immersed  in  the  water;  but  they  are  more  liable  to  derangement 
than  the  ordinary  wheels ; the  floats  may  be  made  to  leave  the  water  at  any  required  angle.  Mr.  P. 
W.  Barlow,  C.  E.,  states  the  proportion  of  the  power  expended  on  Morgan's  vertical  wheels  at  546,  and 
of  the  former  at  151  to  197. 

The  Cycloidal  paddle-wheel,  Fig.  3923,  (the  paddle-wheel  of  the  “Great  1768161-0,”)  forms,  the  most 
recent  improvement,  and  is  said  to  possess  the  advantages  of  each  of  the  former,  being  effective  and 
strong,  yet  simple,  in  point  of  construction.  It  was  patented  by  Mr.  Galloway  in  the  year  1835,  although 
first  used  by  Mr.  Field  in  1833.  The  floats  are  divided  into  a number  of  parts,  which  are  placed  upon 


WIRE  ROPE  MACHINERY. 


913 


the  wheel  in  the  curve  of  a cycloid,  so  that  they  enter  the  water  at  the  same,  spot,  and  follow  one  an- 
other so  rapidly  as  to  cause  little  resistance  to  the  engine  ; in  passing  the  centre,  there  is  full  scope  to 
their  action,  and  in  coming  out  they  allow  the  water  to  escape  readily  from  them. 

The  draught  of  the  vessel  is  necessarily  greatest  at  the  commencement  of  a voyage,  particularly  if 
it  should  be  a long  one,  on  account  of  the  full  quantity  of  coals  for  the  whole  voyage  increasing  the 
amount  of  tonnage,  and  other  similar  contingencies  ; the  wheels  are,  therefore,  immersed  very  deep  in 
the  water,  which  has  the  etfect  of  increasing  the  resistance ; but  this  loss  of  power  diminishes  as  the. 


3921. 


3922. 


vessel  proceeds.  The  adjusting  of  the  floats  of  paddle-wheels  to  the  requisite  depth  of  immersion  is 
called  reefing  the  fi oats,  and  there  is  some  difficulty  connected  with  it ; but  this  defect  may  be  partly 
rectified  with  the  cycloidal  wheels,  as  the  outer  floats  need  not  be  fixed  at  starting,  but  fitted  on  as  the 
voyage  proceeds ; and  the  larger  the  wheel,  the  less  will  the  vessel  be  affected  by  this  defect,  as  the 
diameter  of  the  wheel  increases  in  a greater  proportion  than  the  variation  of  immersion  of  the  vessel ; 
the  latter  is  consequently  proportionately  less  than  other  vessels,  when  each  are  laden. 

WIRE  COVERING-  MACHINE.  Fig.  3924  is  a simple,  machine  for  covering  bonnet  or  telegraph 
wire,  and  which  may  be  easily  constructed.  There  are  other  kinds  of  machines  which  we  have  seen  in 
operation  that  can  cover  five  and  six  wires  at 
once,  but  this  one  is  certainly  not  surpassed  for  3924. 

simplicity. 

A A,  sole  of  machine,  made  of  wood,  into 
which  are  mortised  the  two  uprights  B B,  only 
one  of  which  is  shown — they  are  placed  about 
three  inches  apart;  C,  upright  frame  for  carry- 
ing shaft  D and  tube  E ; F F,  two  rollers  for 
drawing  through  the  wire  as  it  is  covered : the 
top  roller  is  made  of  lead,  so  as  to  give  pres- 
sure to  the  wire  to  take  it  through  ; E,  tube  or 
hollow  spindle  through  which  the  wire  passes ; 

G G,  spur-wheel  and  pinion  for  driving  hollow 
spindle  and  bobbin  A ; I,  brackets  for  carrying 
end  of  hollow  spindle  ; J,  endless-screw  for 
working  the  pulley-wheel  0,  fixed  on  the  outer 
end  of  the  under-roller  F ; K,  support  for 
steadying  the  wire  as  it  passes  through  the 

spindle  E.  H,  bobbin  containing  the  thread  for  covering  the  wire  ; L is  a small  eye  fixed  into  the  fram6 
that  carries  the  bobbin,  through  which  the  thread  passes  on  to  the  wire.  In  using  the  machine  the 
wire  to  be  covered  is  held  by  the  hands,  and  kept  stretched  as  it  is  drawn  through  by  the  two  roll- 
ers ; another  pair  of  rollers  might  be  applied  to  keep  the  wire  stretched,  the  same  as  the  drawing-rollers. 

WIRE  ROPE  MACHINERY.  The  machinery  by  which  so  intractable  a material  as  iron  wire, 
when  compared  with  hemp,  is  spun  into  a rope,  is  most  simple  and  complete,  and  has  been  patented 
in  England  by  Mr.  Smith.  As  the  drums  on  which  the  wire  is  wound  deliver  it  to  the  spinning  portion 
of  the  machinery,  the  rope,  beautifully  and  regularly  finished,  is  seen  flying  away  with  inconceivable 
rapidity,  and  the  harmony,  smoothness,  and  freedom  from  jar  or  strain  with  which  the  whole  works  is 
truly  admirable.  The  motion  is  entirely  new  for  such  a purpose,  being  without  wheels,  and  is  effected 
by  a mechanical  arrangement  similar  to  an  orrery,  or  the  sun  and  planet  motion ; it  effects  great  econo- 
my in  working  cost  from  the  decreased  friction,  takes  up  much  less  space  than  the  ordinary  machines, 
and  makes  but  little  noise  when  in  most  rapid  operation.  The  following  is  the  specification  and  de- 
scription : 

Firstly,  my  invention,  in  so  far  as  it  regards  machinery  for,  or  methods  of  manufacturing  rope  or  cord- 
age, has  relation  to  the  means  employed  to  give  motion  to  the  reels  or  bobbins  in  laying  the  yarn  or 
wire  into  strands,  or  in  laying  strands  into  rope  or  cordage,  and  consists  in  the  improved  arrangements 
Vol.  II. — 58 


on 


WIRE  ROPE  MACHINERY. 


for  that  purpose  represented  in  Figs.  3925  and  3926,  the  former  of  which  is  a plan  of  the  machinery  or 
the  line  y x,  and  the  latter  a side  elevation  thereof.  The  bobbins  or  reels  gg  (of  any  convenient  num- 
ber) are  mounted  in  a circular  frame  A,  which  is  upheld  by  screw-rods  v v,  with  an  outer  framework  A1 
consisting  of  a basement  k,  four  pillars  pp,  an  entablature  y1,  spandrills  x‘  x1,  and  conical  apex  w.  The 
principal  parts  of  the  frame  A are  three  six-armed  rings  R1,  R2,  R3,  which  are  connected  vertically  to 


gether  in  the  manner  to  be  presently  explained,  and  two  laying-plates  1 1 at  top  of  all.  The  undermost 
ring  R1,  is  connected  by  a series  of  cranks  Gee,  with  the  second  ring  R2,  and  R2  with  the  third  ring  F„3, 
by  straight  vertical  rods  s s.  The  centre  crank  C is  stationary,  and  stepped  by  its  short  arm  in  a pe- 
destal N,  attached  to  the  basement  of  the  outer  framework  A2,  while  the  undermost  ring  R1  is  attached 
to  a loose  boss  r,  slipped  over  the  short  arm  of  the  crank  C,  so  that  on  a rotating  movement  being  given 


to  the  ring  R1,  it  carries  round  with  it  the  ring  R2  by  means  of  the  side-cranks  e e — that  is  to  any,  the 
side-cranks  e e,  which  may  be  called  live  cranks,  are  made  to  revolve  round  the  centre  or  dead  crank 
C ; while  the  ring  R2  in  its  turn  imparts,  through  the  medium  of  the  vertical  rods  ss,  a simultaneous  ro- 
tary movement  to  the  top  ring  R3.  The  long  arms  of  the  connecting  cranks  e e carry  the  reels  or  bob- 
bins gg,  on  which  the  yarn  or  wire  is  wound,  and  as  they  revolve  at  fixed  and  invariable  distances 


WOODS,  VARIETIES  OF. 


•DM 


ror.nd  the  centre  or  dead  crank  C,  any  twist  of  the  yarn  or  wire,  which  is  in  the  course  of  being  laid,  is 
effectually  prevented.  The  requisite  rotary  motion  is  given  to  the  machine  by  means  of  a pair  of  bevel- 
wheels  B1  and  B2,  the  former  of  which  (B1)  is  attached  to  the  loose  boss  r on  the  short  arm  of  the  dead 
crank  C,  and  the  latter  (B2)  to  a shaft  S,  which  is  turned  by  a steam-engine,  or  other  first  mover,  through 
the  medium  of  the  riggers  a a.  The  long  arm  of  the  dead  crank  0 carries  at  top  a reel  or  bobbin  u, 
from  which  the  heart  or  core  for  the  rope  or  cordage  (of  whatever  material  such  heart  or  core  may  be) 
is  supplied.  The  yarns  or  wires  from  the  different  bobbins  pass  through  guide-holes  in  the  topmost  ring 
R3,  and  meet  and  unite  with  the  core  at  the  laying-plates  tt.  To  the  revolving  shaft  S,  and  at  a little 
distance  from  the  riggers  a a,  there  is  attached  a worm-wheel  h,  the  threads  of  which  take  into  a tan- 
gent-wheel i,  and  thereby  give  motion  to  a whelp-wheel/  keyed  to  the  axis  k1,  of  i.  The  whelp-wheel 
»'  serves  to  receive  or  take  away  the  strand  or  rope  as  it  is  delivered  from  the  twisting  or  bobbin-frame 
A over  the  pulley  Q.  The  whelps  1 1 of  the  wheel  ;'  are  movable  to  and  fro  in  slots,  as  usual,  so  that 
they  may  expand  or  contract  (as  it  were)  in  proportion  to  the  lay  of  the  strand  or  rope.  On  the  axis 
k of  the  wheels  i and/  and  outside  of  both,  there  is  keyed  a flat  grooved  rigger  m,  which  is  connected 
by  a band  n to  a similar  flat  grooved  rigger  o,  keyed  on  a separate  shaft  P,  which  carries  a double 
whelp-wdieel  q , by  which  the  strand  or  rope  is  carried  along  as  it  is  completed. 

And,  secondly,  my  invention,  in  so  far  as  it  regards  the  fitting  and  using  rope  or  cordage,  has  special 
relation  to  the  application  of  wire  rope  or  cordage  to  the  standing  rigging  of  ships,  and  consists  in  the 
improved  contrivance  for  the  purpose  represented  in  the  figure  ; a represents  the  side  of  a vessel ; B, 
the  chain-plate ; D,  a spring  lanyard  of  the  ordinary  form ; / a tube,  in  which  the  lanyard  is  inclosed ; 
c,  a slip  shackle ; e,  a stud  attached  to  the  front  of  the  tube/)  and  having  an  orifice  in  it,  through  which 
the  forelock  e‘  is  passed.  By  taking  out  the  forelock  e\  and  pulling  down  the  tube/,  the  shackle  slips 
up  and  opens  out,  whereby  the  rope  can  be  instantly  disengaged  as  may  be  required. 

WIRING  MACHINE,  for  the  manufacture  of  tin , sheet-iron,  and  other  plate-ware — Patented  by  A. 
W.  Whitney,  Woodstock,  Vermont,  1817. 

The  face-plates  or  rolls  HIP  are  made  of  cast-steel  of  an  improved  form,  having  the  journal-boxes  of 
their  shafts  in  a cast-iron  frame.  This  frame  consists  of  two  pieces,  fitted  together  at  A,  and  at  the  top 
of  the  upright  piece  under  K.  The  journal-box  A has 
two  projecting  ears  or  bearings,  (one  of  which  is  seen 
at  A,)  at  right  angles  to  the  shaft  B H,  on  which  ears 
it  is  supported,  forming  a fulcrum  to  the  shaft  B H ; 
thus  preserving  the  bearing  of  the  shaft  A perfect, 
while  the  end  H is  raised  and  depressed  in  the  process 
of  working.  B is  a movable  collar  for  adjusting  the 
shaft  and  rolls  longitudinally,  with  great  nicety.  C 
is  a binding  screw  for  keeping  the  collar  in  place.  In 
the  shaft  concealed  by  the  collar  B,  is  a spiral  groove, 
into  which  the  binding  screw  enters.  Thus,  by  turn- 
ing the  collar  on  the  shaft,  a nice  longitudinal  adjust- 
ment can  readily  be  obtained.  The  movement  of  the 
rolls  H H is  secured  in  the  usual  manner  by  the  con- 
necting geering  G G.  F is  a gage  extending  between 
the  rolls,  with  a spring  F,  and  a thumb-nut  L,  for  ad- 
justment. I is  a forming  gage,  consisting  of  a friction 
roll  attached  to  the  side  of  a short  rod  or  shaft,  and 
having  its  journal  bearing  in  the  frame.  On  the  inner 
end  of  this  shaft  is  a ratchet-wheel  N,  for  placing  the  gage  in  any  desired  position.  Fitted  to  the  ratch- 
et is  a latch  E for  holding  it  in  place.  At  D is  a spring,  pressing  the  latch  into  the  teeth  of  the  ratchet. 

In  the  working  of  the  machine  the  bearing  at  A always  remains  perfect ; for  its  journal-box,  by  turn- 
ing on  its  ears,  accommodates  itself  to  the  shaft  in  all  positions.  Again,  the  inclination  of  the  shaft  B H 
is  always  towards  H,  so  as  to  bring  the  collar  B in  contact  with  the  box.  Now  to  compensate  for  any 
wear  which  may  displace  the  rolls  HH,  as  well  as  to  adjust  them  to  different  kinds  of  work,  the  collar 
B is  always  immediately  adequate. 

It  will  readily  be  seen  that  the  above  improvements  secure  advantages  not  possessed  by  any  former 
construction,  rendering  the  machine  susceptible  of  immediate  adaptation  to  plates  of  different  thickness. 

The  above  improvements  are  applied  to  other  machines. 

WOODS,  VARIETIES  OF,  used  in  the  Mechanical  Arts. — By  far  the  most  numerous  and  important 
ot  the  materials  from  the  vegetable  kingdom  are  the  woods,  with  which  most  parts  of  our  globe  are 
abundantly  supplied ; great  numbers  of  them  are  used  in  their  respective  countries,  and  are  known  to 
the  naturalist,  although  but  a very  inconsiderable  portion  of  them  are  familiar  to  us  in  our  several  local 
practices. 

The  woods  that  are  most  commonly  employed  in  this  country  are  enumerated  in  an  alphabetical 
list,  together  with  the  most  authentic  information  obtainable  concerning  them. 

The  general  understanding  of  the  principal  differences  of  the  woods  will  be  greatly  assisted  by  a 
brief  examination  into  their  structure  which  is  now  so  commonly  and  beautifully  developed  by  the  sec- 
tions for  the  microscope.  The  Figs.  3928,  3929,  3930  are  drawn  from  thin  cuttings  of  beech-wood, 
prepared  by  the  optician  for  that  instrument:  the  principal  lines  alone  are  represented,  and  these  are 
magnified  to  about  twice  their  linear  distances,  for  greater  perspicuity. 

Fig.  3928,  which  represents  the  horizontal  or  transverse  section  of  a young  tree  or  a branch,  shows 
the  arrangement  of  the  annual  rings  around  the  centre  or  pith ; these  rings  are  surrounded  by  an  ex- 
terior covering,  consisting  also  of  several  thinner  layers,  which  it  will  suffice  to  consider  collectively,  in 
their  common  acceptation,  or  as  the  bark.  The  fibres  which  are  seen  as  rays  proceeding  from  the  pith 
to  the  bark,  are  the  medullary  rays  or  plates. 


a 16 


WOODS,  VARIETIES  OF. 


Fig9.  3929  and  3930  are  vertical  sections  of  an  older  piece  of  beech-wood.  Fig.  3929  is  cut  through 
a plane,  such  as  from  a to  a,  in  which  the  edges  of  the  annual  rings  appear  as  tolerably  parallel  fibres 
running  in  one  direction,  or  lengthways  through  the  stem ; the  few  thicker  stripes  gu'e  the  edges  o> 
6ome  of  the  medullary  rays. 


Fig.  3930  is  cut  radially,  or  through  the  heart,  as  from  b to  b.  In  this  the  fibres  are  observed  to  be 
arranged  in  two  sets,  or  to  run  crossways  ; there  are,  first,  the  edges  of  the  annual  rings,  as  in  Fig.  3929  ; 
and,  secondly,  the  broad  medullary  rays  or  plates. 

The  whole  of  these  figures,  but  especially  the  last,  show  the  character  of  all  the  proper  woods,  namely, 
those  possessing  two  sets  of  fibres,  and  in  which  the  growth  of  the  plant  is  accomplished,  by  the  yearly 
addition  of  the  external  ring  of  the  wood,  and  the  internal  ring  of  the  bark,  whence  these  rings  are 
called  annual  rings,  and  the  plants  are  said  to  be  exogenous,  from  the  growth  of  the  wood  being  external. 

In  Fig.  3928  the  medullary  rays  are  the  more  distinctly  drawn,  in  accordance  with  the  appearance  of 
the  section,  as  they  seem  to  constitute  more  determinate  lines ; whereas  the  annual  rings  consist  rather 
of  series  of  tubes  arranged  side  by  side,  and  in  contact  with  each  other,  and  which  could  not  be  repre- 
sented on  so  small  a scale.  At  the  outer  part  of  each  annual  ring  these  tubes  or  pores  appear  to  be 
smaller  and  closer ; the  substance  is,  consequently,  more  dense,  from  the  greater  proportion  of  the  mat- 
ter forming  the  walls  of  the  tubes  ; and  the  inner  or  the  softer  parts  of  the  annual  rings  have  in  general 
larger  vessels,  and  therefore  less  density. 

In  many  plants  the  wedge-form  plates,  intermediate  between  the  medullary  rays,  only  appear  as  an 
irregular  cellular  tissue  full  of  small  tubes  or  pores,  without  any  very  definite  arrangement*  The  me- 
dullary rays  constitute,  however,  the  most  characteristic  part  of  the  structure,  and  greatly  assist  in 
determining  the  difference  between  the  varieties  of  the  exogenous  plants,  as  well  as  the  wide  distinc- 
tion between  the  entire  group  and  those  shortly  to  be  described.  The  medullary  rays  also  appear,  by 
their  distinct  continuity,  to  constitute  the  principal  source  of  combination  and  strength  in  the  substance 
of  the  woods  ; most  of  the  medullary  rays,  in  proceeding  from  the  centre  to  the  circumference,  divide 
into  parts  to  fill  out  the  increased  space. 

In  the  general  way,  the  vertical  fibres  of  the  annual  rings,  and  the  horizontal  fibres  of  the  medullary 
rays,  are  closely  and  uniformly  intermingled ; they  form  collectively  the  substance  of  the  wood,  and 
they  also  constitute  two  series  of  minute  interstices,  that  are  viewed  to  be  either  separate  cells  or  ves- 
sels, the  majority  of  which  proceed  vertically,  the  others  radially.  In  many,  as  the  oak,  sycamore, 
maple,  and  sweet  chestnut,  the  medullary  rays,  when  dissected,  exhibit  a more  expanded  or  foliated 
character,  and  pervade  the  structure,  not  as  simple  radial  tubes,  but  as  broad  septa  or  divisions,  which 
resemble  flattened  cells  or  clefts  amongst  the  general  groups  of  pores,  giving  rise  to  the  term  silver- 
grain,  derived  from  them  light  and  glossy  appearance  : they  vary  considerably  in  size  and  number. 

The  beech-wood,  Fig.  3930,  has  been  selected  as  a medium  example  between  this  peculiarity  and  the 
ordinary  crossings  of  the  fibres,  which  in  the  firs  and  several  others  seem  as  straight  as  if  they  were 
lines  mechanically  ruled,  and,  even  in  the  most  dense  woods,  are  in  general  easily  made  out  under  the 
microscope. 

The  vessels  or  cells  running  amidst  the  fibres  are  to  the  plant  what  the  blood-vessels  and  air-cells 
are  to  the  animal ; a part  of  them  convey  the  crude  sap  from  the  roots,  or  the  mouths  of  the  plant, 
through  the  external  layers  of  the  wood  to  the  leaves,  in  which  the  sap  is  evaporated  and  prepared ; 
the  fluid  afterwards  returns  through  the  bark  as  the  elaborated  sap,  and  combines  with  that  in  the  ex- 
ternal layers  of  the  wood,  the  two  constituting  the  cambium.  The  latter  ultimately  becomes  consoli- 
dated for  the  production  of  the  new  annual  ring  that  is  deposited  beneath  the  loosened  bark,  and  which 
is  eventually  to  constitute  a part  of  the  general  substance  or  wood ; the  bark  also  receives  a minute 
addition  yearly,  and  the  remainder  of  the  fluid  returns  to  the  earth  as  an  excretion. f 

The  other  order  of  the  plants  grows  in  an  entirely  different  manner,  namely,  by  a deposition  from 
within,  whence  they  are  said  to  be  endogenous ; these  include  all  the  grasses,  bamboos,  palms,  d:c. 
Endogens  are  mostly  hollow,  and  have  only  one  set  of  fibres,  the  vertical,  which  appear  in  the  trans- 
verse section,  Fig.  3931,  as  irregular  dots  closely  congregated  around  the  margin,  and  gradually  more 
distant  towards  the  centre,  until  they  finally  disappear,  and  leave  a central  cavity,  or  a loose  cellular 
structure.  Fig.  3932  represents  the  horizontal,  and  Fig.  3933  the  vertical  section  of  portions  of  the 
same,  or  the  cocoanut  palm  (Cocos  nucifera)  of  half  their  full  size. 


* In  the  Cissampctos  Pwrcira,  belonging  to  the  natural  order  Menispcrmaceae,  this  structure  is  singularlv  evident;  the 
medullary  rays  are  very  thick,  and  almost  detached  from  the  intermediate  wedge-form  plates,  which  are  nearly  solid, 
except  the  few  pores  by  which  they  are  pierced,  much  like  the  substance  of  the  common  cane. 

f The  reader  is  referred  to  the  following  articles  in  the  three  editions  of  Dr.  Lindley’s  Introduction  to  Botany,  namely, 
“ Exogenous  structure and  Of  the  stem  and  origin  of  wood and  also,  u Exogens and  u Endogens, ” by  the  same 
Wthor,  in  the  Penny  Cyclopaedia;  all  are  replete  with  physiological  interest. 


WOODS,  VARIETIES  OF. 


917 


All  the  endogens  are  considered  to  commence  from  a circular  pithy  stem,  which  is  entirely  solid 
some,  as  the  canes,  maintain  this  solidity,  with  the  exception  of  the  tubes  or  pores  extending  through 
out  their  length.  The  bamboos  extend  greatly  in  diameter,  so  as  to  become  hollow,  except  the  dia 
phragms  at  the  knots ; these  are  often  used  as  cases  for  rolls 
of  papers.  The  palms  generally  enlarge  still  more  consider- 
ably to  their  extreme  size,  which,  in  seme  cases,  is  fifty  times 
the  diameter  of  the  original  stem,  the  centre  being  soft  and 
pithy. 

Some  of  the  palms,  &c.,  denote  each  yearly  increase  by  one 
of  the  rings  or  markings  upon  their  stems,  which  are  always 
soft  in  the  upper  part,  like  a green  vegetable,  and  terminate 
in  a cluster  of  broad  pendent  leaves,  generally  annual,  and 
when  they  drop  off  they  leave  circular  marks  upon  the  stem, 
which  are  sometimes  permanent,  and  indicate  by  their  num- 
ber the  age  of  the  plant.  The  vertical  fibres  above  referred 
to  proceed  from  the  leaves,  and  are  considered  to  be  analogous 
to  their  roots,  and  likewise  to  assimilate  in  function  to  the 
downward  flow  of  the  sap  from  the  leaves  of  the  exogens : 
whereas  in  the  palms  they  constitute  separate  and  detached 
fibres,  that  first  proceed  inwards,  and  then  again  outwards, 
with  a very  long  and  gradual  sweep,  thereby  causing  the 
fibres  to  be  arranged  in  part  vertically,  and  in  part  inclined, 
as  in  the  figure.* 

The  substance  of  the  stems  of  the  palms  is  not  allowed  by 
physiological  botanists  to  be  proper  wood,  (which  in  all  cases 
grows  exteriorly,  and  possesses  the  two  sets  of  fibres  shown 
in  Fig,  3930,)  whereas  the  endogenous  plants  have  only  the  one 
set,  or  the  vertical  fibres ; and  although  many  of  this  tribe 
yield  an  abundance  of  valuable  gifts  to  the  natives  of  the  trop- 
ical climates  in  which  they  flourish,  only  a portion  of  the  lower 
as  wood ; amongst  other  purposes,  the  smaller  kinds  are  used  by  the  natives  as  tubes  for  the  convey- 
ance of  water,  and  the  larger  pieces  as  joists  and  beams. 

The  larger  palms  generally  reach  us  in  slabs  measuring  about  the  sixth  or  eighth  part  of  the  circle, 
as  in  Fig.  3931,  the  smaller  sizes  are  sent  entire;  Fig.  3932  represents  a small  piece  near  the  outside, 
with  the  fibres  half  size ; but  the  different  palms  vary  considerably  in  the  shapes,  magnitudes,  and  dis- 
tances of  the  fibres,  and  the  colors  and  densities  of  the  two  parts. 

In  the  vertical  section,  Fig.  3933,  which  is  also  drawn  half  size,  the  fibres  look  like  streaks  or  wires 
imbedded  in  a substance  similar  to  cement  or  pith,  which  is  devoid  of  fibrous  structure.  The  inhab- 
itants of  the  Isthmus  of  Darien  pick  out  the  fibres  from  some  of  the  palms  and  use  them  as  nails  ; they 
are  generally  pointed,  and  in  the  specimens  from  which  the  drawing  was  made,  they  are  as  hard  as 
rosewood,  whereas  the  pithy  substance  is  quite  friable.  Some  of  the  smallest  palms  are  imported 
into  this  country  for  walking-sticks,  under  the  names  of  partridge  and  Penang  canes,  <fcc.  The  ordi- 
nary canes  and  bamboos  are  too  well  known  to  require  more  than  to  be  named. 

To  return  to  the  more  particular  examination  of  the  woods  that  most  concern  us,  it  will  be  observed 
that  the  central  pith  in  Fig.  3928  happens  to  be  of  an  irregular  triangular  shape.  This,  the  primary 
portion  of  the  plant,  is,  in  the  first  instance,  always  cylindrical ; it  is  supposed  to  assume  its  accidental 
form  (which  is  very  frequently  hexagonal)  from  the  compression  to  which  it  is  subjected.  The  pith 
governs,  in  a considerable  degree,  the  general  figure  or  section,  as  all  the  series  of  rings  will  be  ob- 
served, in  Fig.  3928,  to  have  a disposition  to  project  at  three  points ; but  with  the  successive  additions, 
the  angular  form  is  gradually  lost,  as  it  would  be  if  we  wound  a ribbon  upon  a small  triangular  wire  ; 
for,  after  a time,  no  material  departure  from  the  circular  form  would  be  observable. 

A greater  variation  amongst  the  rings  is  due  to  the  more  or  less  favorable  growth  of  the  successive 
years,  and  to  the  different  exposure  of  the  tree  to  thevsun  and  air,  which  develop  that  side  of  the  plant 
in  an  additional  degree ; whereas  the  tree  growing  against  a wall  or  any  other  obstruction,  becomes 
remarkably  stunted  on  that  side  of  its  axis,  from  being  so  shielded. 

The  growth  of  a tree  is  seldom  so  exactly  uniform  that  is  section  is  circular,  or  its  heart  central ; 
often  far  from  it ; and  as  every  annual  ring  is  more  consolidated,  and  of  a deeper  color  on  its  outer  sur- 
face, they  frequently  serve  to  denote  very  accurately,  in  the  woods  growing  in  cold  and  temperate  cli- 
mates, the  age  of  the  plant,  the  differences  of  the  seasons,  the  circumstances  of  its  situation,  and  the 
general  rapidity  of  its  growth.  “ But  in  many  hot  countries  the  difference  between  the  growing  season 
and  that  of  rest,  if  any  occur,  is  so  small,  that  the  zones  are  as  it  were  confounded,  and  the  observer 
finds  himself  incapable  of  distinguishing  with  exactness  the  formation  of  one  year  from  that  of  another.”  f 

It  is,  however,  difficult  to  arrive  at  any  satisfactory  conclusion  respecting  the  qualities  of  woods, 
from  the  appearance  of  their  annual  rings  ; for  instance,  in  two  specimens  of  larch,  considered  by  Mr. 
Finchamj;  to  be  exceedingly  similar,  in  specific  gravity,  strength,  and  durability ; in  the  one,  Scotch 
larch,  there  were  only  three  annual  rings  in  five-eighths  of  an  inch,  whereas  in  Italian  larch  there  were 
twenty-four  layers  in  the  same  space.  In  some  of  the  tropical  woods  the  appearance  of  the  rings  can 
scarcely  be  defined,  and  in  a specimen  of  the  lower  or  butt-end  of  teak,  now  before  us,  three  annual 
rings  alone  cover  the  great  space  of  one  inch  and  three-eighths. 


part  of  the  shell  of  the  tree  is  available 


* The  leaves  of  the  exogens  are  by  some  thought  to  send  down  similar  roots  or  fibres  between  the  bark  and  wood  foi 
the  formation  of  the  annual  ring.  t Dr.  Lindley’s  Introduction  to  Botany,  second  edition,  p.  74. 

t Principal  builder  of  the  Chatham  Dock-yard,  England,  and  a writer  on  ship-h’iilding. 


918 


WOODS,  VARIETIES  OF. 


The  horizontal  section  of  a tree  occasionally  looks  as  if  it  were  the  result  of  two,  three,  or  more  sepa- 
rate shoots  or  stems  consolidated  into  one  ; in  some  of  the  foreign  woods  in  particular  this  irregularity 
often  gives  rise  to  deep  indentations,  and  most  strange  shapes,  which  become  eventually  surrounded  by 
one  single  covering  of  sap ; so  that  a stem  of  considerable  girth  may  yield  only  an  insignificant  piece 
of  wood,  scarcely  available  for  the  smallest  purposes  of  turnery,  much  less  for  cabinet-work.* 

The  circulation  of  the  sap  is  considered  to  be  limited  to  a few  of  the  external  layers,  or  those  of  the 
sap-wood,  or  alburnum , which  are  in  a less  matured  state  than  the  perfect  wood,  or  duramen,  beneath 
The  last  act  of  the  circulation,  as  regards  the  heart-wood,  is  supposed  to  be  the  deposition  of  the 
coloring  matter,  resin  or  gum,  through  the  agency  of  the  medullary  rays  that  proceed  from  the  bark 
towards  the  centre,  and  leave  their  contents  in  the  layer  outside  the  true  wood  perfected  the  year  pre- 
vious. We  may  fairly  suppose  by  analogy,  that  as  one  ring  is  added  eacli  year,  so  one  is  perfected 
annually,  and  thrown  out  of  the  circulatory  system. 

That  the  circulation  has  ceased  in  the  heart-wood,  and  that  the  connection  between  it  and  the  bark 
has  become  broken,  is  further  proved  by  the  fact,  that  numbers  of  trees  may  be  found  in  tolerably 
vigorous  growth  within  the  bark,  whereas  at  the  heart  they  are  decayed  and  rotten.  In  fact,  some  of 
the  hardest  foreign  woods,  as  kingwood,  tulip-wood,  and  others,  are  rarely  sound  in  the  centre,  and 
thus  indicate  very  clearly  that  their  decay  commenced  whilst  they  were  in  their  parent  soil ; and  as  in 
these  the  appearance  of  annual  rings  is  scarcely  to  be  distinguished,  this  also  appears  to  indicate  a 
great  term  of  age,  enough  to  account  for  this  relatively  premature  decay. 

The  quantity  of  sap-wood  is  various  in  different  plants,  and  the  line  of  division  is  usually  most 
distinctly  marked;  in  some,  as  boxwood,  the  sap-wood  is  very  inconsiderable,  and  together  with  the 
bark  is  on  the  average  only  about  the  thickness  of  a stout  card,  whereas  in  others,  as  the  snakewood, 
it  constitutes  fully  two-thirds  of  the  diameter,  so  that  a large  tree  yields  but  an  inconsiderable  stick  of 
wood,  of  one-third  or  fourth  the  external  diameter. 

It  may  be  presumed  that,  in  the  same  variety  of  wood,  about  an  average  number  of  the  layers  exist 
as  sap-wood,  as  in  cutting  up  a number  of  pieces  of  the  same  kind,  such  as  the  black  Botany-Bay  wood, 
and  others,  it  is  found  that,  in  those  measuring  about  two  inches  diameter,  the  piece  of  heart-wood  is 
only  about  as  large  as  the  finger,  but  in  pieces  one,  two,  or  three  inches  larger,  the  heart-wood  is  also 
respectively  one,  two,  or  three  inches  larger,  or  nearly  to  the  full  extent  of  the  increase  of  the  diameter. 

The  sap-wood  may  be  therefore,  in  general,  considered  as  of  about  an  average  thickness  in  each  kind 
of  wood : it  is  mostly  softer,  lighter,  more  even  in  color,  and  more  disposed  to  decay  than  the  heart-wood, 
which  prove  it  to  be  in  a less  matured  or  useful  state,  whether  for  mechanical  or  chemical  purposes. 

At  the  time  the  tree  is  separated  from  its  root,  its  organic  life  cease?,  and  then  commences  the 
gradual  evaporation  of  the  sap,  and  the  drying  and  contracting  of  the  tubes,  or  tissues,  previously 
distended  by  its  presence. 

The  woods  are  in  general  felled  during  the  cold  months,  when  the  vegetative  powers  of  the  plant  are 
(.early  dormant,  and  when  they  are  the  most  free  from  sap ; but  none  of  the  woods  are  fit  for  use  in  the 
state  in  which  they  are  cut  down,  for  although  no  distinct  circulation  is  going  on  within  the  heart-wood, 
still  the  capillary  vessels  keep  the  trees  continually  moist  throughout  their  substance,  in  which  state 
they  should  not  be  employed. 

If  the  green  or  wet  woods  are  placed  in  confined  situations,  the  tree  or  plank  first  becomes  stained  or 
doated,  and  this  speedily  leads  to  its  decomposition  or  decay,  effects  that  are  averted  by  careful  drying 
with  free  access  of  air.f 

Other  mischiefs  almost  as  fatal  as  decay  also  occur  to  unseasoned  woods ; round  blocks  cut  out  of  the 
entire  circular  stem  of  green  wood,  or  the  same  pieces  divided  into  quarterings,  split  in  the  direction  of 
the  medullary  rays,  or  radially,  also,  though  less  frequently,  upon  the  annual  rings.  Such  of  the  round 
blocks  as  consist  of  the  entire  section  contract  pretty  equally,  and  nearly  retain  their  circular  form,  but 
those  from  the  quarterings  become  oval  from  their  unequal  shrinking. 


* This  is  not  peculiar  to  the  tropical  woods;  for  example,  some  of  the  yew-trees  in  Hampton  Court  gardens  appear  to 
have  grown  in  this  manner  from  three  or  lour  separate  stems,  that  have  joined  into  one  at  a short  distance  above  the 
ground.  As  an  instance  of  the  singular  manner  in  which  the  separate  branches  of  trees  thus  combine,  I may  mention  that 
stones,  pieces  of  metal,  and  other  substances,  are  occasionally  met  with  in  the  central  parts  of  timber,  from  having  been 
accidentally  deposited  in  a cleft,  or  the  fork  of  a branch,  and  entirely  inclosed  or  overgrown  by  the  subsequent  increase  ot 
the  plant. 

f On  this  account  the  timbers  for  ships  are  usually  cut  out  to  their  shape  and  dimensions  for  about  a year  before  they 
are  framed  together,  and  they  are  commonly  left  a twelvemonth  longer  in  the  skeleton  state,  lo  complete  ihe  seasoning,  as 
in  that  condition  they  are  more  favorably  situated  as  regards  exposure  to  the  air  than  when  they  are  closely  covered  in  with 
the  planking. 

Sir.  Fincham  considers  that  the  destruction  of  timber  by  the  decay  commonly  known  as  dry-rot  cannot  occur,  unless  air, 
moisture,  and  heat,  are  all  present,  and  that  the  entire  exclusion  of  any  of  the  three  stays  the  mischief.  By  way  of  experi- 
ment, he  bored  a hole  in  one  of  the  timbers  of  an  old  ship,  built  of  oak,  whose  wood  was  at  the  time  perfectly  sound  ; the 
admission  of  air,  the  third  element,  to  the  central  par  t of  the  wood,  (the  two  olhers  being  to  a certain  degree  present,) 
caused  the  hole  to  be  filled  up  in  the  course  of  twenty-four  hours  with  mouldiness,  a well-known  vegetation,  which  very 
speedily  became  so  compact  a fungus  as  to  admit  of  being  withdrawn  like  a slick.  He  considers  the  shakes  or  splits  in 
Umber  to  predispose  it  to  decay,  in  damp  and  confined  situations,  from  admitting  the  air  in  the  same  manner. 

The  woods  differ  amazingly  in  their  resistance  to  decay ; some  perish  in  one  or  two  years,  whereas  others  are  very  durable, 
and  even  preserve  their  fragrance  when  they  are  opened  afier  many  years,  or  almost  centuries. 

Mr.  G.  Loddiges  says  the  oak-boxes,  for  the  plants  in  his  green-houses,  decay  in  two  or  three  years,  whereas  he  has  found 
jhoso  of  teak  to  last  fully  six  or  seven  times  as  long:  the  situation  is  one  of  severe  trial  for  the  wood. 

There  are  two  quarto  works  on  dry-rot;  the  one  by  Mr.  Me  William,  1818;  the  other  by  Mr.  John  Knowles,  Surveyor  o 1 
Her  Majesty’s  Navy,  1821. 

The  process  of  Kyanizing  is  intended  to  prevent  the  re-vegetation  of  timber,  by  infusing  into  its  pores  an  antiseptic  salt : 
the  corrosive  sublimate  is  generally  employed,  other  metallic  salts  are  also  considered  to  be  applicable,  but  the  general 
utility  of  the  process,  especially  in  thick  timbers,  or  those  exposed  to  much  wet,  is  still  unsettled  amongst  practical  men. 

The  Kyanizing  is  sometimes  done  in  open  tanks,  at  others,  (by  Timperley’s  process,  Hull  and  Selby  Railway,)  in  close 
vessels  from  which  the  air  is  first  exhausted  to  the  utmost,  and  the  fluid  is  then  admitted  under  a pressure  of  about  10(1 
pounds  on  the  inch. 


WOODS,  VARIETIES  OF. 


919 


As  a general  observation,  it  may  be  said  the  tvoods  do  not  alter  in  any  material  degree  in  respect  tc 
length.  Boards  and  flat  pieces  contract,  however,  in  width,  they  warp  and  twist,  and  when  they  are 
fitted  as  panels  into  loose  grooves,  they  shrink  away  from  that  edge  which  happens  to  be  the  most 
slightly  held ; but  when  restrained  by  nails,  mortises,  or  other  unyielding  attachments,  which  do  not 
allow  them  the  power  of  contraction,  they  split  with  irresistible  force,  and  the  materials  and  labor  tho. 
improperly  employed  will  render  no  useful  service. 

In  general,  the  softest  woods  shrink  the  most  in  width,  but  no  correct  observations  on  this  subject 
have  been  published.  Mr.  Fincham  considers  the  rock-elm  to  shrink  as  much  as  any  wood,  namely, 
about  half  an  inch  in  the  foot,  whereas  the  teak  scarcely  shrinks  at  all ; in  the  “ Tortoise”  store-ship, 
when  fifty  years  old,  no  openings  were  found  to  exist  between  the  boards. 

In  the  woods  that  have  been  partially  dried,  some  of  these  effects  are  lessened  when  they  aru 
, defended  by  paint  or  varnish,  but  they  do  not  then  cease,  and,  with  dry  wood,  every  time  a new  surface 
is  exposed  to  the  air,  even  should  the  work  have  been  made  for  many  years,  these  perplexing  alterations 
will  in  a degree  recommence,  even  independently  of  the  changes  of  the  atmosphere,  the  fluctuations  of 
which  the  woods  are  at  all  times  too  freely  disposed  to  obey. 

The  disposition  to  shrink  and  warp,  from  atmospheric  influence,  appears  indeed  to  be  never  entirely 
subdued ; some  bog-oak,  supposed  to  have  been  buried  in  the  island  of  Sheppy  not  less  than  a thousand 
years,  was  dried  for  many  months,  and  ultimately  made  into  chairs  and  furniture  ; it  was  still  found  to 
shrink  and  cast,  when  divided  into  the  small  pieces  required  for  the  work. 

Seasoning  and  preparing  the  woods. — Having  briefly  alluded  to  the  mischiefs  consequent  upon  the 
use  of  woods  in  an  improper  condition,  I shall  proceed  to  describe  the  general  modes  pursued  for  avoiding 
such  mischiefs  by  a proper  course  of  preparation : 

The  woods,  immediately  after  being  felled,  are  sometimes  immersed  in  running  water  for  a few  days, 
weeks,  or  months,  at  other  times  they  are  boiled  or  steamed ; this  appears  to  be  done  under  the  expec- 
tation of  diluting  and  washing  out  the  sap,  after  which  it  is  said  the  drying  is  more  rapidly  and  better 
accomplished,  and  also  that  the  colors  of  the  white  woods  are  improved,  (see  article  Holly  in  Catalogue, 
also  Ebony  ;)  but  the  ordinary  course  is  simply  to  expose  the  logs  to  the  air,  the  effect  of  which  is  assisted 
by  the  preparation  of  the  wood  into  smaller  pieces,  approaching  to  the  sizes  and  forms  in  which  they 
will  be  ultimately  used,  such  as  square  logs  and  beams,  planks  or  boards  of  various  thicknesses,  short 
lengths  or  quarterings,  <ftc. 

The  stems  and  branches  of  the  woods  of  our  own  country,  such  as  alder,  birch,  and  beech,  that  are 
used  by  the  turner,  frequently  require  no  reduction  in  diameter;  but  when  they  are  beyond  the  size  of 
the  work,  they  are  split  into  quarterings  and  stacked  in  heaps  to  dry,  which  latter  proceeding  should 
never  be  forgotten  under  any  circumstances. 

We  know  but  little  of  the  early  treatment  of  the  foreign  woods  used  for  cabinet-work  and  turning  ; 
some  few  of  them,  as  mahogany  and  satin-wood,  are  imported  in  square  logs  ; others,  as  rosewood, 
ebony,  or  Coromandel,  are  sometimes  shipped  in  the  halves  of  trees,  or  in  thick  planks  ; but  the  general- 
ity of  those  used  for  turning  are  small,  and  do  not  require  this  reduction ; these  only  reach  us  in  billets, 
sometimes  with  the  rind  or  bark  upon  them,  and  sometimes  cleaned  or  trimmed. 

The  smaller  hard  woods  are  very  much  more  wasteful  than  the  timber  woods  ; in  many  of  the  former, 
independently  of  their  thick  bark,  the  section  is  very  far  from  circular,  as  they  are  often  exceedingly 
irregular,  indented,  and  ill-defined ; others  are  almost  constantly  unsound  in  their  growth,  and  eithei 
present  central  hollows  and  cavities,  or  cracks  and  radial  divisions,  which  separate  the  stem  into  three 
or  four  irregular  pieces. 

Probably  none  of  the  hard  woods  are  so  defective  as  the  black  Botany-Bay  wood,  in  which  the 
available  produce,  when  it  is  trimmed  ready  for  the  lathe,  may  be  considered  to  be  about  one-third  or 
fourth  of  the  original  weight,  sometimes  still  less ; but  unfortunately  many  others  approach  too  nearly 
to  this  condition,  as  a very  large  proportion  of  them  partake  of  the  imperfections  referred  to,  more 
especially  the  cracks  ; the  larger  hard  woods  are  by  comparison  much  less  wasteful. 

All  the  harder  woods  require  increased  care  in  the  seasoning,  which  is  often  badly  begun  by  exposure 
to  the  sun  or  hot  winds  in  their  native  climates : their  greater  impenetrability  to  the  air  the  more 
disposes  them  to  crack,  and  their  comparative  scarcity  and  expense  are  also  powerful  arguments  on 
the  score  of  precaution.  It  is  therefore  desirable  to  prepare  them  for  the  transition  from  the  yard  or 
cellar  to-  the  turning-room,  by  removing  the  parts  which  are  necessarily  wasted,  the  more  intimately  to 
expose  them  to  the  air  some  time  before  they  are  placed  in  the  house,  and  they  should  be  always  kept 
away  from  the  fire,  or  at  first  in  a room  altogether  without  one. 

It  is  usual  to  begin  by  cutting  the  logs  into  pieces  a few  inches  or  upwards  in  length,  to  the  general 
size  of  the  work ; and  if  possible  to  prepare  every  piece  into  a round  block,  or  into  two  or  three,  when 
the  wood  is  irregular,  hollow,  or  cracked.  In  the  latter  case,  a thin  wedge  is  inserted  into  the  principal 
crack,  and  driven  down  with  a wooden  maul ; or  a cleaver  which  has  a sharp  edge,  and  a poll  to  receive 
the  blow,  is  used  in  the  same  manner ; these  tools,  or  the  hatchet,  are  likewise  used  in  splitting  up  the 
English  woods,  when  they  are  beyond  the  diameters  required.*  The  cleft  pieces  are  next  roughly 
trimmed  with  the  hatchet,  or  else  with  the  paring-knife,  a tool  of  safer  and  more  economical  application 
in  the  hands  of  the  amateur : it  is  a lever  knife,  from  two  and  a half  to  three  feet  long  ; the  cutting-edge 
is  near  that  end  which  terminates  in  a hook,  the  other  extremity  has  a transverse  handle ; an  eye-bolt 
for  the  hook  to  act  against  is  screwed  into  the  bench  or  block,  and  a detached  cutting-board  is  fixed 
under  the  blade,  to  serve  as  the  support  for  the  wood,  and  for  the  knife  to  cut  upon.  To  avoid  waste 
of  material,  it  is  advisable,  until  the  eye  is  well  accustomed  to  the  work,  to  score  with  the  compasses 
upon  each  end  of  the  rough  block  as  large  a circle  as  it  will  allow,  to  serve  as  a guide  for  the  knife. 

The  block  is  adapted  to  the  bearers  of  the  lathe,  but  any  other  support  will  serve  equally  well.  The 
paring-knife  is  also  employed  for  other  purposes  besides  those  of  the  turner  : it  is  sometimes  made  with 


* Sometimes  the.  glazier’s  chipping  knife  is  used  for  small  pieces  of  wood  instead  of  the  cleaver. 


920 


WOODS,  VARIETIES  OF. 


a curved  edge  like  a gouge,  and  is  used  in  many  shaping  operations  in  wood,  as  in  the  manufacture  of 
shoe-lasts,  clogs,  pattens,  and  toys.* * * § 

In  the  absence  of  the  paring-knife  or  hatchet,  the  work  is  fixed  in  the  vice,  and  rounded  with  a coarse 
rasp,  but  this  is  much  less  expeditious : by  some  manufacturers  the  preparation  botli  of  the  foreign  and 
English  woods  is  prosecuted  still  further,  by  cutting  the  material  into  smaller  pieces,  rough  turned  and 
hollowed  in  the  lathe,  to  the  forms  of  boxes,  or  other  articles  for  which  they  are  specifically  intended ; 
and  in  fact  every  measure  that  tends  to  make  the  change  of  condition  gradual,  assists  also  in  the 
economy,  perfection,  and  permanence  of  the  work. 

Many  of  the  timber-woods  are  divided  at  the  saw-pit  into  planks  or  boards,  at  an  early  stage,  in  order 
to  multiply  the  surfaces  upon  which  the  air  may  act,  and  also  to  leave  a less  distance  for  its  penetration : 
after  sawing,  they  should  never  be  allowed  to  rest  in  contact,  as  the  partial  admission  of  the  air  often 
causes  stains  or  doating ; but  they  are  placed  either  perpendicularly  or  horizontally  in  racks,  or  they 
are  more  commonly  stacked  in  horizontal  piles,  with  parallel  slips  of  wood  placed  between  at  distances 
from  about  three  to  six  or  eight  feet,  according  to  the  quantity  of  support  required ; the  pile  when 
carefully  stacked  forms  a press,  and  keeps  the  whole  flat  and  straight. 

Thin  pieces  will  be  sufficiently  seasoned  in  about  one  year’s  time,  but  thick  wood  requires  two  or 
three  years,  before  it  is  thoroughly  fit  to  be  removed  to  the  warmer  temperature  of  the  house  for  the 
completion  of  the  drying.  Mahogany,  cedar,  rosewood,  and  the  other  large  foreign  woods,  require  to 
be  carefully  dried  after  they  are  cut  into  plank,  as  notwithstanding  the  length  of  time  that  sometimes 
intervenes  between  their  being  felled  and  brought  into  use,  they  still  retain  much  of  their  moisture  whilst 
they  remain  in  the  log.f 

In  some  manufactories  the  wood  is  placed,  for  a few  days  before  it  is  worked  up,  in  a drying-room 
heated  by  means  of  stoves,  steam,  or  hot  water,  to  several  degrees  beyond  the  temperature  to  which  the 
finished  work  is  likely  to  be  subjected. 

Such  rooms  are  frequently  made  as  air-tight  as  possible,  which  appears  to  be  a mistake,  as  the  wood 
is  then  surrounded  by  a warm  but  stagnant  atmosphere,  which  retains  whatever  moisture  it  may  have 
evaporated  from  the  wood.  Of  late,  a plan  has  been  more  successfully  practised  in  seasoning  timber 
for  building  purposes,  by  the  employment  of  heated  rooms  with  a free  circulation  of  air,  which  enters 
at  the  lower  part  in  a hot  and  dry  state,  and  escapes  at  the  upper  charged  with  the  moisture,  which  it 
freely  absorbs  in  the  heated  condition.  The  continual  ingress  of  hot  dry  air,  greedy  of  moisture,  so  far 
expedites  the  drying,  that  it  is  accomplished  in  one-third  of  the  time  that  is  required  in  the  ordinary 
way  in  the  open  air.j: 

Hard  and  soft  woods,  etc. — The  relative  terms  hard  and  soft,  elastic  or  non-elastic,  and  the  proportions 
of  resins,  gums,  <fcc.,  as  applied  to  the  woods,  appear  to  be  in  a great  measure  explained  by  their  exam- 
ination under  the  microscope,  which  develops  their  structure  in  a very  satisfactory  manner. 

The  fibres  of  the  various  woods  do  not  appear  to  differ  so  materially  in  individual  size  or  bulk,  as  in 
their  densities  and  distances : those  of  the  soft  woods,  such  as  willow,  alder,  and  deal,  appear  slight 
and  It.  >se ; they  are  placed  rather  wide  asunder,  and  present  considerable  intervals  for  the  softer  and 
more  s longy  cellular  tissue  between  them  ; whereas  in  oak,  mahogany,  ebony,  and  rosewood,  the  fibres 
appeal  rather  smaller,  but  as  if  they  possessed  a similar  quantity  of  matter,  just  as  threads  containing 
the  same  number  of  filaments  are  larger  or  smaller,  accordingly  as  they  are  spun.  The  fibres  are  also 
more  closely  arranged  in  the  harder  woods,  the  intervals  between  them  are  necessarily  less,  and  the 
whole  appears  a more  solid  and  compact  formation. 

The  very  different  tools  used  by  the  turner  for  the  soft  woods  and  hard  woods  respectively,  may  have 
assisted  in  fixing  these  denominations  as  regards  his  art ; a division  that  is  less  specifically  entertained 
by  the  joiner,  who  uses  the  same  tools  for  the  hard  and  soft  woods,  excepting  a trifling  difference  in 
their  angles  and  inclinations ; whereas  the  turner  employs,  for  the  soft  woods,  tools  with  keen  edges  of 
thirty  or  forty  degrees,  applied  obliquely,  and  as  a tangent  to  the  circle ; and  for  the  hard  woods,  tools 
of  from  seventy  to  ninety  degrees  upon  the  edge,  applied  as  a radius,  and  parallel  with  the  fibres,  if  so 
required.  The  tools  last  described  answer  very  properly  for  the  dense  woods,  in  which  the  fibres  are  close 
and  well  united ; but  applied  to  the  softer  kinds,  in  which  the  filaments  are  more  tender  and  less  firmly 
joined,  the  hard-wood  tools  produce  rough,  torn,  and  unfinished  surfaces. 

In  general,  the  weight  or  specific  gravity  of  the  woods  may  be  taken  as  a sure  criterion  of  their 
hardness ; for  instance,  the  hard  lignum-vitre,  boxwood,  iron-wood,  and  others,  are  mostly  so  heavy  as  to 
sink  in  water ; whereas  the  soft  firs,  poplar,  and  willow,  do  not,  on  the  average,  exceed  half  the  weight 
of  water,  and  other  woods  are  of  intermediate  kinds.§ 


* A paring-knife  working  in  a guide,  and  with  an  edge  twelve  or  fourteen  inches  long,  i9  a most  effective  instrument  in 
the  hands  of  the  toy-makers.  The  pieces  of  birch,  alder,  &c.,  are  boiled  in  a cauldron  for  about  an  hour  to  soften  them, 
and  whilst  hot  they  may  be  worked  with  great  expedition  and  perfection.  The  workmen  pare  off  slices,  the  plankway  of 
the  grain,  as  large  as  four  by  six  inches,  almost  as  quickly  as  they  can  be  counted:  they  are  wedged  tight  in  rows,  like 
books,  to  cause  them  to  dry  tint  and  straight,  and  they  seldom  require  any  subsequent  smoothing.  In  making  the  little 
wheels  for  carts,  &c.,  say  of  one  or  two  inches  diameter,  and  one-quarter  or  three-eighths  of  an  inch  thick,  they  cut  them 
the  cross-way  of  the  grain , out  of  cylinders  previously  turned  and  bored ; the  flexibility  of  the  hot  moist  wood  being  such 
that  it  yields  to  the  edge  of  the  knife,  without  breaking  transversely  as  might  be  expected. 

t Scientifically  considered,  the  drying  is  only  said  to  be  complete  when  the  wood  ceases  to  lose  weight  from  evaporation : 
this  does  not  occur  after  twice  or  thrice  the  period  usually  allowed  for  the  process  of  seasoning. 

In  many  modern  buildings  small  openings  are  left,  through  the  walls  to  the  external  air,  to  allow  a partial  circulation 
amidst  the  beams  and  joists,  as  a preservative  from  decay,  and  for  the  entire  completion  of  the  seasoning. 

X Price’s  Patent. 

§ The  most  dense  wood  is  the  Iron  Hark  wood  from  New  South  Wales:  in  appearance  it  resembles  a close  hard  ma- 
hogany, but  more  brown  than  red ; its  specific  gravity  is  P420, — its  strength  (compared  with  English  oak,  taken  as  usual  at 
1*000)  is  l'5o7.  On  the  other  hand,  the  lightest  of  the  true  woods  is  probably  the  Cortica , or  the  el  none  palustris , from 
Brazil,  in  Mr.  Mier’s  collection  ; the  specific  gravity  of  this  is  only  0*206,  whereas  that  of  cork  is  0*240  ; it  has  only  one- 
seventh  the  weight  of  Iron  Bark  wood.  The  Cortica  resembles  ash  in  color  and  grain,  except  that  it  is  pale.',  finer,  and 
much  softer ; it  is  used  by  the  natives  lor  wooden  shoes.  &.c. 


WOODS,  VARIETIES  OF. 


9liJ 


The  density  or  weight  of  many  of  the  woods  may  be  increased  by  their  mechanical  compression, 
which  may  be  carried  to  the  extent  of  fully  one-third  or  fourth  of  their  primary  bulk,  and  the  weight 
and  hardness  obtain  a corresponding  increase.  This  has  been  practised  for  the  compression  of  tree-nails 
for  ships,  by  driving  the  pins  through  a metal  ring  smaller  than  themselves  directly  into  the  hole  in  tho 
ship’s  side  •* * * * §  at  other  times,  (for  railway  purposes,)  the  woods  have  been  passed  through  rollers,  but 
this  practice  has  been  discontinued,  as  it  is  found  to  spread  the  fibres  laterally,  and  to  tear  them 
asunder  ;f  an  injury  that  does  not  occur  when  they  are  forced  through  a ring,  which  condenses  the  wood 
at  all  parts  alike  without  any  disturbance  of  its  fibrous  structure,!  even  when  tested  by  the  microscope  ; 
after  compression,  the  wood  is  so  much  harder  that  it  cuts  very  differently,  and  the  pieces  almost  ring 
when  they  are  struck  together ; fir  may  be  thus  compressed  into  a substance  as  close  as  pitch-pine. 

In  many  of  the  more  dense  woods,  we  also  find  an  abundance  of  gum  or  resin,  which  fills  up  many  of 
those  spaces  that  would  be  otherwise  void : the  gum  not  only  makes  the  wood  so  much  the  heavier,  but 
at  the  same  time  it  appears  to  act  in  a mechanical  manner,  to  mingle  with  the  fibres  as  a cement,  and 
to  unite  them  into  a stronger  mass  ; for  example,  it  is  the  turpentine  that  gives  to  the  outer  surface  of 
the  annual  rings  of  the  red  and  yellow  deals  the  hard,  horny  character,  and  increases  the  elasticity  of 
those  timbers. 

Those  woods  which  are  the  more  completely  impregnated  with  resin,  gum,  or  oil,  are  in  general  also 
the  more  durable,  as  they  are  better  defended  from  the  attacks  of  moisture  and  insects. 

Timbers  alternately  exposed  to  wet  and  dry,  are  thought,  by  Tredgold  and  others,  to  suffer  from 
losing  every  time  a certain  portion  of  their  soluble  parts ; if  so,  those  which  are  naturally  impregnated 
with  substances  insoluble  in  water  may,  in  consequence,  give  out  little  or  none  of  their  component  parts 
in  the  change  from  wet  to  dry,  and  on  that  account  the  better  resist  decay : this  has  been  artificially 
imitated  by  forcing  oil,  tar,  <fcc.,  through  the  pores  of  the  wood  from  the  one  extremity.^ 

Many  of  the  woods  are  very  durable  when  constantly  wet ; the  generality  are  so  when  always  dry, 
although  but  few  are  suited  to  withstand  the  continual  change  from  one  to  the  other  state ; but  these 
particulars,  and  many  points  of  information  respecting  timber-woods  that  concern  the  general  practice 
of  the  builder,  or  naval  architect,  such  as  their  specific  gravities,  relative  strengths,  resistances  to  bending 
and  compression,  and  other  characters,  are  treated  of  in  Tredgold’s  Elements  of  Carpentry,  at  consider- 
able length.  || 

Elastic  and  non-elastic  woods. — The  most  elastic  woods  are  those  in  which  the  annual  or  longitudinal 
fibres  are  the  straightest,  and  the  least  interwoven  with  the  medullary  rays,  and  which  are  the  least 
interrupted  by  the  presence  of  knots;  such  woods  are  also  the  most  easily  rent,  and  the  plainest  in  fig- 
ure, as  the  lancewood,  hickory,  and  ash ; whereas  other  woods,  in  which  the  fibres  are  more  crossed  and 
interlaced,  are  considerably  tougher  and  more  rigid ; they  are  also  less  disposed  to  split  in  a straight  or 
economical  manner,  as  oak,  beech,  and  mahogany,  which,  although  moderately  elastic,  do  not  bend  with 
the  facility  of  those  before  named. 

Eishing-rods,  unless  made  of  bamboo,  have  generally  ash  for  the  lower  joint,  hickory  for  the  two  mid- 
dle pieces,  and  a strip  cut  out  of  a bamboo  of  three  or  four  inches  diameter  as  the  top  joint.  Archery 
bows  are  another  example  of  elastic  works  ; the  “ single-piece  bow”  is  made  of  one  rod  of  hickory,  lance- 
wood, or  yew-tree,  which  last,  if  perfectly  free  from  knots,  is  considered  the  most  suitable  wood : the 
“ back  or  union  bow”  is  made  of  two  or  sometimes  three  pieces  glued  together.  The  back-piece , or  that 
furthest  from  the  string,  is  of  rectangular  section,  and  always  of  lancewood  or  hickory  ; the  belly , which 
is  nearly  of  semicircular  section,  is  made  of  any  hard  wood  that  can  be  obtained  straight  and  clean,  as 
ruby-wood,  rosewood,  greenheart,  kingwood,  snakewood,  and  several  others : it  is  in  a great  measure  a 
matter  of  taste,  as  the  elasticity  is  principally  due  to  the  back-piece ; the  palmyra  is  also  used  for  bows.^j 

The  elasticity,  or  rather  the  flexibility  of  the  woods,  is  greatly  increased  for  the  time,  when  they  are 
heated  by  steaming  or  boiling  ; the  process  is  continually  employed  for  bending  the  oak  and  other  tim- 
bers for  ship-building,  the  lancewood  shafts  for  carriages,  the  staves  of  casks,  and  various  other  works. 

The  woods  are  steamed  in  suitable  vessels,  and  are  screwed  or  wedged,  at  short  intervals  throughout 
their  length,  in  contact  with  rigid  patterns  or  moulds,  and  whilst  under  this  restraint  they  are  allowed 
to  become  perfectly  cold  ; the  pieces  are  then  released.  These  bent  works  suffer  very  little  departure 
from  the  forms  thus  given,  and  they  possess  the  great  advantage  of  the  grain  being  parallel  with  the 
curve,  which  adds  materially  to  their  strength,  saves  much  cost  of  material  and  time  in  the  preparation, 
and  gives,  in  fact,  a new  character  to  the  timber. 

The  inner  and  outer  plankings  of  ships  are  steamed  or  boiled  before  they  are  applied  ; they  are 
brought  into  contact  with  the  ribs  by  temporary  screw-bolts,  which  are  ultimately  replaced  by  the  cop- 


Th'e  Pita  wood,  that  of  the  Fourcroya  gigantea , of  the  Brazils,  an  cmlogen  almost.  like  pith,  fused  by  the  fishermen  of 
Rio  Janeiro,  as  a slow  match,  for  lighting  cigars,  &c. ; also  like  cork  for  lining  the  drawers  of  cabinets  for  insects,)  and  the 
rice-paper  plant  of  India  and  China,  which  is  still  lighter  and  more  pithy,  can  hardly  be  taken  into  comparison. 

* Sir.  Aunersley’s  Patent,  1821,  for  building  vessels  of  planks  only,  without  ribs. 

f Dublin  and  Kingston  Railway. 

j The  mode  at  present  practised  by  the  Messrs.  Ransome,  of  Ipswich,  (under  their  patent.)  is  to  drive  the  pieces  of  oak 
Into  an  iron  ring  by  means  of  a screw-press,  and  to  expose  them  within  the  ring  to  a temperature  of  about  180°  for  twelve 
or  sixteen  hours  before  forcing  them  out  again. 

The  tree-nails  may  be  thus  compressed  into  two-thirds  their  original  size,  and  they  recover  three-fourths  of  the  compres- 
sion on  being  wetted;  they  are  used  for  railway  purposes,  but  appear  equally  desirable  for  ship-building,  in  which  the 
tree-nails  fulfil  an  important  office,  and  in  either  case  their  after-expansion  fixes  them  most  securely. 

§ The  durability  of  pitch  pine,  when  “wet  and  dry,”  is  however  questioned. 

J The  work  contains  a variety  of  the  most  useftd  tables. 

®]  The  union  bow  is  considered  to  be  “softer,”  that  is,  more  agreeably  elastic  than  the  single-piece  bow.  even  when  the 
wo  require  the  same  weight  to  draw  them  to  the  length  of  the  arrow.  In  the  act  of  bending  the  bow  the  back  is  put  into 
tension,  and  the  inner  piece  into  a state  of  compression,  and  each  wood  is  then  employed  in  its  most  suitable  manner. 
Sometimes  the  union  bow  is  imitated  by  one  solid  piece  of  straight  cocoa-wood,  (of  the  West  Indies,  not  that,  of  the  cocna- 
n ■ t palm,)  in  which  case  the  tough  fibrous  sap  is  usr  d for  the  back,  and  in  its  nature  sufficiently  resembles  t ht  lancewood 
m ire  generally  used. 


922 


WOODS,  VAKIETIES  OF. 


per  bolts  inserted  through  the  three  thicknesses  and  riveted : or  they  are  secured  by  oak  or  locust  tree- 
nails, which  are  caulked  at  each  end.* 

Boiling  and  steaming  are  likewise  employed  for  softening  the  woods,  to  facilitate  the  cutting  as 
well  as  bending  of  them. I 

When  the  two  sets  of  fibres  meet  in  confused  angular  directions,  they  produce  the  tough  cross- 
grained  woods,  such  as  lignum-vit®,  elm,  &c.,  and,  like  the  diagonal  braces  in  carpentry  and  shipping, 
they  deprive  the  mass  of  elasticity,  and  dispose  it  rather  to  break  than  to  bend,  especially  when  the 
pieces  are  thin,  and  the  fibres  crop  out  on  both  sides  of  the  same ; the  confusion  of  the  fibres  is,  at  the 
same  time,  a fertile  source  of  beauty  in  appearance  to  most  woods. 

Elm  is  perhaps  the  toughest  of  the  European  woods  ; it  is  considered  to  bear  the  driving  of  bolts 
and  nails  better  than  any  other,  and  it  is  on  this  account,  and  also  for  its  great  durability  under  water, 
constantly  employed  for  the  keels  of  ships,  for  boat-building,  and  a variety  of  works  requiring  great 
strength  and  exposure  to  wet. 

A similar  rigidity  is  also  found  to  exist  in  the  crooked  and  knotted  limbs  of  trees  from  the  confu- 
sion amongst  the  fibres,  and  such  gnarled  pieces  of  timber,  especially  those  of  oak,  were  in  former  days 
particularly  valued  for  the  knees  of  ships  : of  later  years  they  have  been  in  a great  measure  super- 
seded by  iron  knees,  which  can  be  more  accurately  and  effectively  moulded  at  the  forge  to  suit  their 
respective  places,  and  they  cause  a very  great  saving  in  the  available  room  of  the  vessel. 

The  liguum-vitse  is  a most  peculiar  wood,  as  its  fibres  seem  arranged  in  moderately  thick  layers, 
crossing  each  other  obliquely,  often  at  as  great  an  angle  as  thirty  degrees  with  the  axis  of  the  tree  ; 
when  the  wood  is  split,  it  almost  appears  as  if  the  one  layer  of  annual  fibres  grew  after  the  manner 
of  an  ordinary  screw,  and  the  succeeding  layer  wound  the  other  way  so  as  to  cross  them  like  a left- 
hand  screw.  The  interlacement  of  the  fibres  in  lignum-vit®  is  so  rigid  and  decided,  although  irregular, 
that  it  exceeds  all  other  woods  in  resistance  to  splitting,  which  cannot  be  effected  with  economy ; the 
wood  is  consequently  always  prepared  with  the  saw.  It  is  used  for  works  that  have  to  sustain  great 
pressure  and  rough  usage,  several  examples  of  which  are  given  under  the  head  Lighum-vim  in  the 
Catalogue  already  referred  to. 

Fibre  or  grain , knots,  etc. — The  ornamental  figure  or  grain  of  many  of  the  woods  appears  to  de- 
pend as  much  or  more  upon  the  particular  directions  and  mixings  of  the  fibres,  as  upon  their  differences 
of  color.  We  will  first  consider  the  effect  of  the  fibre  assisted  only  by  the  slight  variation  of  tint,  ob- 
servable between  the  inner  and  outer  surfaces  of  the  annual  layers,  and  the  lighter  or  more  silky  char- 
acter of  the  medullary  rays. 

If  the  tree  consisted  of  a series  of  truly  cylindrical  rings,  like  the  tubes  of  a telescope,  the  hori- 
zontal section  would  exhibit  circles  ; the  vertical,  parallel  straight  lines  ; and  the  oblique  section  would 
present  parts  of  ovals ; but  nature  rarely  works  with  such  formality,  and  but  few  trees  are  either 
exactly  circular  or  straight,  and  therefore,  although  the  three  natural  sections  have  a general  disposi- 
tion to  the  figures  described,  every  little  bend  and  twist  in  the  tree  disturbs  the  regularity  of  the  fibres, 
and  adds  to  the  variety  and  ornament  of  the  wood. 

The  horizontal  section,  or  that  parallel  with  the  earth,  only  displays  the  annual  rings  and  medul- 
lary rays,  as  in  Fig.  3928 ; and  this  division  of  the  wood  is  principally  employed  by  the  turner,  as  it 
is  particularly  appropriate  to  his  works,  the  strength  and  shrinking  being  alike  at  all  parts  of  the  cir- 
cumference, in  the  blocks  and  slices  cut  out  of  the  entire  tree,  and  tolerably  so  in  those  works  turned 
out  of  the  quarterings  or  parts  of  the  transverse  pieces. 

But  as  the  cut  is  made  intermediate  between  the  horizontal  line  ana  the  one  parallel  with  the  axis, 
the  figure  gradually  slides  into  that  of  the  ordinary  plank,  magnified  portions  of  which  are  shown  in 
Figs.  3929  and  3930 ; and  these  are  almost  invariably  selected  for  carpentry,  &c. 

The  oblique  slices  of  the  woods  possess  neither  the  uniformity  of  grain  of  the  one  section,  nor  the 
strength  of  the  other,  and  it  would  be  likewise  a most  wasteful  method  of  cutting  up  the  timber ; it  is 
therefore  only  resorted  to  for  thin  veneers,  when  some  particular  figure  or  arrangement  of  the  fibres  has 
to  be  obtained  for  the  purposes  of  ornamental  cabinet-work. 

The  perpendicular  cut  through  the  heart  of  the  tree  is  not  only  the  hardest  but  the  most  diversified, 
because  therein  occurs  the  greatest  mixture  and  variety  of  the  fibres,  the  first  and  the  last  of  which,  in 
point  of  age,  are  then  presented  in  the  same  plank ; but  of  course  the  density  and  diversity  lessen  as 
the  board  is  cut  further  away  from  the  axis.  In  general  the  radial  cut  is  also  more  ornamental  than  the 
tangential,  as  in  the  former  the  medullary  rays  produce  the  principal  effect,  because  they  are  then  dis- 
played in  broader  masses,  and  are  considered  to  contain  the  greater  proportion  of  the  coloring  matter  of 
the  wood. 

The  section  through  the  heart  displays  likewise  the  origin  of  most  of  the  branches,  which  arise  first  as 


* See  the  description  of  Mr.  William  Hookey’s  apparatus  for  bending  ships’  timbers,  rewarded  by  the  Society  of  Arts, 
and  described  in  their  Trans.,  vol.  32,  p.  91. 

Preference  is  now  given  to  the  “ Steam  Kiln”  over  the  “ Water  Kiln,”  and  the  time  allowed  is  one  hour  for  every  inch 
of  the  thickness  of  the  timber ; it  loses  much  extractive  matter  in  the  process,  which  is  never  attempted  a second  time,  as 
the  wood  then  becomes  brittle. 

Colonel  G.  A.  Lloyd  devised  an  ingenious  and  economical  mode  of  bending  the  timbers  to  constitute  the  ribs  of  a teak- 
bridge  which  he  built  in  the  Mauritius.  Every  rib  was  about  180  ft.  long,  and  of  8 ft.  rise,  and  consisted  of  five  thicknesses 
of  wood  of  various  lengths  and  widths.  The  wood  had  been  cut  down  about  a month  ; it  was  well  steamed  and  brought 
into  contact  with  a strong  mould,  by  means  of  an  iron  chain  attached  to  a hook  at  the  one  extremity  of  the  mould  and 
passed  under  a roller  fixed  at  the  other;  the  chain  was  drawn  tight  by  a powerful  capstan.  Whilst  under  restraint  the 
neighboring  pieces  were  pinned  together  by  tree-nails,  after  which  a further  portion  of  the  rib  was  proceeded  with:  the 
seasoning  of  the  timber  was  also  effected  by  the  process. 

t Thus  in  Taylc 's  Patent  Machinery  for  making  casks,  the  blocks  intended  for  the  staves  are  cut  out  of  white  Canada 
oak  to  the  size  of  thirty  inches  by  five,  and  smaller.  They  are  well  steamed,  and  then  sliced  into  pieces  one-half  or  five- 
eighths  inch  thick,  at  the  rate  of  200  in  each  minute,  by  a process  far  more  rapid  and  economical  than  sawing;  the  instru- 
ment being  a revolving  iron  plate  of  12  or  14  feet  diameter,  with  two  radial  knives,  arranged  somewhat  like  tho  irons  of 
Ui  ordinary  plane  or  spokeshuve. 


/ 


WOODS,  VARIETIES  OF. 


92c' 


knots,  in  or  near  the  central  pith,  and  then  work  outwards  in  directions  corresponding  with  the  arms  oi 
the  trees,  some  of  which,  as  in  the  cypress  and  oak,  grow  out  nearly  horizontally,  and  others,  as  in  the 
poplar,  shoot  up  almost  perpendicularly. 

Those  parts  of  wood  described  as  curls  are  the  result  of  the  confused  filling  in  of  the  space  between 
the  forks,  or  the  springings  of  the  branches.  Fig.  3934 
represents  the  section  of  a piece  of  yew-tree,  which  shows 
remarkably  well  the  direction  of  the  main  stem  A B,  the 
origin  of  the  branch  C,  and  likewise  the  formation  of  the 
curl  between  B and  C ; Fig.  3935  is  the  end  view  of  the 
stem  at  A.  In  many  woods,  mahogany  especially,  the 
curls  are  particularly  large,  handsome,  and  variegated, 
and  are  generally  produced  as  explained. 

It  would  appear  as  if  the  germs  of  the  primary 
branches  were  set  at  a very  early  period  of  the  growth 
of  the  central  stem,  and  gave  rise  to  the  knots,  many  of 
which,  however,  fail  to  penetrate  to  the  exterior  so  as  to 
produce  branches,  but  are  covered  over  by  the  more  vig- 
orous deposition  of  the  annual  rings.  All  these  knots  and 
branches  act  as  so  many  disturbances  and  interruptions 
to  the  uniformity  of  the  principal  zones  of  fibres,  which 
appear  to  divide  to  make  way  for  the  passage  of  the  off- 
shoots, each  of  which  possesses  in  its  axis  a filament  of 
the  pith,  so  that  the  branch  resembles  the  general  trunk 
in  all  respects  except  in  bulk ; and  again  from  the  prin- 
cipal branches  smaller  ones  continually  arise,  ending  at 
last  in  the  most  minute  twigs,  each  of  which  is  distinctly 
continuous  with  the  central  pith  of  the  main  stem,  and 
fulfils  its  individual  share  in  causing  the  diversity  of  fig- 
ure in  the  wood. 

The  knots  are  commonly  harder  than  the  general  substance,  and  that  more  particularly  in  the  softer 
woods  ; the  knots  of  the  deals,  for  example,  begin  near  the  axis  of  the  tree,  and  at  first  show  the  min- 
gling of  the  general  fibres  with  those  of  the  knot,  much  the  same  as  in  the  origin  of  the  branch  of  the 
yew,  in  Fig.  3^)34 ; but  after  a little  ■while  it  appears  as  if  the  branch,  from  elongating  so  much  more 
rapidly  than  the  deposition  of  the  annual  rings  upon  the  main  stem,  soon  shot  through  and  became 
entirely  detached,  and  the  future  rings  of  the  trunk  were  bent  and  turned  slightly  aside  when  they 
encountered  the  knot,  but  without  uniting  with  it  in  any  respeGt. 

This  may  explain  why  the  smooth  cylindrical  knots  of  the  outer  boards  of  white  deal,  pine,  efec.,  so 
frequently  drop  out  when  exposed  on  both  sides  in  thin  boards;  whereas  the  turpentine  in  the  red  and 
yellow  deals  may  serve  the  part  of  a cement,  and  retain  these  kinds  the  more  firmly. 

The  elliptical  form  of  the  knots  in  the  plank  is  mostly  due  to  the  oblique  direction  in  which  they  are 
cut,  and  their  hardness  (equal  to  that  of  many  of  the  tropical  hard  woods)  to  the  close  grouping  of  the 
annual  rings  and  fibres  of  which  they  are  themselves  composed.  These  are  compressed  by  the  sur- 
rounding wood  of  the  parent  stem,  at  the  time  of  the  deposition ; whereas  the  principal  layers  of  the 
stem  of  the  tree  are  opposed  alone  by  the  loosened  and  yielding  bark,  and  only  obtain  the  ordinary 
density. 

The  knots  of  large  trees  are  sometimes  of  considerable  size.  The  writer  has  portions  of  one  of  those 
of  the  Norfolk  Island  pine,  ( Araucaria  excelsa,)  which  attained  the  enormous  size  of  about  four  feet 
long,  and  four  to  six  inches  diameter.  In  substance  it  is  throughout  compact  and  solid,  of  a semi-trans- 
parent hazel-brown,  and  it  may  be  cut  almost  as  well  as  ivory,  and  with  the  same  tools,  either  into 
screws,  or  with  eccentric  or  drilled  work,  &c. ; it  is  an  exceedingly  appropriate  material  for  ornamental 
turning. 

It  is  by  some  supposed,  that  the  root  of  a tree  is  divided  into  about  as  many  parts  or  subdivisions  as 
there  are  branches,  and  that,  speaking  generally,  the  roots  spread  around  the  trunk  under  ground  to 
about  the  same  distance  as  the  branches  wave  above  ; the  little  germs  or  knots  from  which  they  proceed 
being  in  the  one  case  distributed  throughout  the  length  of  the  stem  of  the  tree,  and  in  the  other  crowded 
together  in  the  shorter  portion  buried  in  the  earth. 

If  this  be  true,  we  have  a sufficient  reason  for  the  beautiful  but  gnarled  character  of  the  roots  of  trees 
when  they  are  cut  up  for  the  aits ; many  a block  of  the  root  of  the  walnut-tree,  thus  made  up  of  small 
knots  and  curls,  and  that  was  first  intended  for  the  stock  of  a fowling-piece,  has  been  cut  into  veneers 
and  arranged  in  angular  pieces  to  form  the  circular  picture  of  a table ; and  few  pictures  of  this  natural 
kind  will  be  found  more  beautiful.  The  roots  of  many  trees  also  display  very  pretty  markings ; some 
are  cut  into  veneers,  and  those  of  the  olive-tree,  and  others,  are  much  used  on  the  continent  for  making 
snuff-boxes. 

The  tops  of  the  pollard-trees,  such  as  the  red  oak,  elm,  ash,  and  other  trees,  owe  their  beauty  to  a 
similar  crowding  together  of  the  little  germs,  whence  have  originated  the  numerous  shoots  which  pro- 
ceeded from  them  after  they  have  been  lopped.  The  burrs  or  excrescences  of  the  yew,  and  some  other 
trees,  appear  to  arise  from  a similar  cause,  apparently  the  unsuccessful  attempts  at  the  formation  of 
branches  from  one  individual  spot ; from  this  may  arise  those  bosses  or  wens,  which  almost  appear  as 
the  result  of  disease,  and  exhibit  internally  crowds  of  knots,  with  fibres  surrounding  them  in  the  most 
fantastic  shapes.  Sometimes  the  burrs  occur  of  immense  size,  so  as  to  yield  a large  and  thick  slab  of 
highly  ornamental  wood  of  most  confused  and  irregular  growth : such  pieces  are  highly  prized,  and  are 
cut  into  thin  veneers  to  be  used  in  cabinet-w'ork. 

It  appears  extremely  clear  likewise  that  the  beautiful  East  Indian  wood,  called  both  Kiabooca  and 


D24 


WOODS,  VARIETIES  OF. 


Amboyna,  is,  in  like  manner,  the  excrescence  of  a large  timber-tree.  Its  character  is  very  similar  to  (hi 
burr  of  the  yew-tree,  but  its  knots  are  commonly  smaller,  closer,  and  the  grain  or  fibre  is  more  silky. 
The  Kiabooca  has  also  been  supposed  to  be  cut  from  around  the  base  of  the  cocoanut  palm,  a surmise 
that  is  hardly  to  be  maintained,  although  the  latter  may  resemble  it,  as  the  Kiabooca  is  imported  alone 
from  the  East  Indies,  whereas  the  cocoanut  palm  is  common  and  abundant  both  in  the  eastern  and 
western  hemispheres.  (See  Kiabooca  in  the  Catalogue.*) 

The  bird’s-eye  maple  shows,  in  the  finished  work,  the  peculiar  appearance  of  small  dots  or  ridges,  01 
of  little  conical  projections  with  a small  hollow  in  the  centre,  (to  compare  the  trivial  with  the  grand 
like  the  summits  of  mountains,  or  the  craters  of  volcanoes,)  but  without  any  resemblance  to  knots,  which 
are  the  apparent  cause  of  ornament  in  woods  of  somewhat  similar  character,  as  the  burrs  of  the  yew 
and  kiabooca,  and  the  Russian  maple,  (or  birch-tree :)  this  led  us  to  seek  a different  cause  for  its 
formation. 

On  examination,  we  found  the  stem  of  the  American  bird’s-eye  maple,  stripped  of  its  bark,  presented 
little  pits  or  hollows  of  irregular  form,  some  as  if  made  with  a conical  punch,  others  ill-defined  and 
flattened  like  the  impression  of  a hob-nail ; suspecting  these  indentations  to  arise  from  internal  spines 
or  points  in  the  bark,  a piece  of  the  latter  was  stripped  off  from  another  block,  when  the  surmise  was 
verified  by  their  appearance.  The  layers  of  the  wood  being  moulded  upon  these  spines,  each  of  their 
fibres  is  abruptly  curved  at  the  respective  places,  and  when  cut  through  by  the  plane,  they  give,  in  the 
tangential  slice,  the  appearance  of  projections,  the  same  as  in  some  rose-engine  patterns,  and  the  more 
recent  medallic  glyptographic  or  stereographic  engravings,  in  which  the  closer  approximation  of  the 
lines,  at  their  curvatures,  causes  those  parts  to  be  more  black,  (or  shaded,)  and  produces  upon  the  plane 
surfaces  the  appearances  of  waves  and  ridges,  or  of  the  subject  of  the  medaL 

The  short  hues  observed  throughout  the  maple-wood,  between  the  dots  or  eyes,  are  the  edges  of  the 
medullary  rays;  and  the  same  piece  of  wood,  when  examined  upon  the  radial  section, exhibits  the  ordinary 
silver  grain,  such  as  we  find  in  the  sycamore,  (to  which  family  the  maple-tree  belongs,)  with  a very  few 
of  the  dots,  and  those  displayed  in  a far  less  ornamental  manner. 

The  piece  examined  measured  eight  inches  wide,  and  five  and  a half  inches  radially,  and  was  appa- 
rently the  produce  of  a tree  of  about  sixteen  inches  diameter ; the  effect  of  the  internal  spines  of  the 
bark  was  observable  entirely  across  the  same,  that  is,  through  each  of  the  130  zones  of  which  it  con- 
sisted. The  curvature  of  the  fibres  was  in  general  rather  greater  towards  the  centre,  which  is  to  be 
accounted  for  by  the  successive  annual  depositions  upon  the  bark,  detracting  in  a small  degree  from  the 
height  or  magnitude  of  the  spines  within  the  same,  upon  which  the  several  deposits  of  wood  were  formed. 
Other  woods  also  exhibit  spines,  which  may  be  iutended  for  the  better  attachment  of  the  bark  to  the 
stem,  but,  from  their  comparative  minuteness,  they  produce  no  such  effect  on  the  wood  as  that  which 
exists,  we  believe  exclusively,  in  the  bird’s-eye  maple. 

This  led  me  to  conclude  that  in  woods,  the  figures  of  which  resemble  the  undulations,  or  the  ripple- 
marks  on  the  sands,  that  frequently  occur  in  satin-wood  and  sycamore,  less  frequently  in  boxwood,  and 
also  in  mahogany,  ash,  elm,  and  other  woods,  to  be  due  to  a cause  explained  by  Fig.  3936,  namely,  a 
serpentine  or  guilloche  form  in  the  grain : and  on  inspection,  the  fibres  of  all  such  pieces  will  be  found 
to  be  wavy,  on  the  face,  at  right  angles  to  that  on  which  the  ripple  is  observed,  if  not  on  both  faces. 
Those  parts  of  the  wood  which  happen  to  receive  the  light  appear  the  brightest,  and  form  the  ascending 
sides  of  the  ripple,  just  as  some  of  the  medallic  engravings  appear  in  cameo  or  in  intaglio,  according  t« 
the  direction  in  which  the  fight  falls  upon  them. 


:«36. 


The  woods  possessing  this  wavy  character  generally  split  with  an  undulating  fracture,  the  ridges 
being  commonly  at  right  angles  to  the  axis  of  the  tree,  or  square  across  the  board ; but  in  a specimen 
of  an  Indian  red  wood,  the  native  name  of  which  is  6 'aliatour,  the  ridges  are  inclined  at  a considerable 
angle,  presenting  a very  peculiar  appearance,  seen  as  usual  on  the  polished  surface. 

In  those  woods  which  possess  in  abundance  the  septa  or  silver  grain,  described  by  the  botanist  as  the 
medullary  plates  or  rays,  the  representations  of  which,  as  regards  the  beech-tree,  are  given  in  Fig.  3930, 
another  source  of  ornament  exists ; namely,  a peculiar  damask  or  dappled  effect,  somewhat  analo- 
gous to  that  artificially  produced  on  damasked  linens,  moreens,  silks,  and  other  fabrics,  the  patterns 
on  which  result  from  certain  masses  of  the  threads  on  the  face  of  the  cloth  running  lengthways,  and 
other  groups  crossways.  Tins  effect  is  observable  in  a remarkable  degree  in  the  more  central  planks  of 
oak,  especially  the  light-colored  wood  from  Norway,  and'the  neighborhood  of  the  Rhine,  called  wainscot 
and  Dutch  oak,  (fee.,  and  also  in  many  other  woods,  although  in  a less  degree. 

In  the  oak  plank,  the  principal  streaks  or  fines  are  the  edges  of  the  annual  rings,  which  show,  as  usual 


* Mr.  G.  Loddiges  considers  the  burrs  may  occur  upon  almost  all  old  trees,  and  that  they  result  “rom  the  last  attempt  at 
the  plant  to  maintain  life,  by  the  reparation  of  any  injury  it  may  have  received. 


WOODS,  VARIETIES  OF. 


925 


parallel  lines  more  or  less  waved  from  the  curvature  of  the  tree,  or  the  neighboring  knots  and  branches 
and  the  damask  pencillings,  or  broad  curly  veins  and  stripes,  are  caused  by  groups  of  the  medullary 
rays  or  septa , which  undulate  in  layers  from  the  margin  to  the  centre  of  the  tree,  and  creep  in  betwixt 
the  longitudinal  fibres,  above  some  of  them  and  below  others.  The  plane  of  the  joiner,  here  and  there, 
intersects  portions  of  these  groups,  exactly  on  a level  with  their  general  surface,  whereas  their  recent 
companions  are  partly  removed  in  shavings,  and  the  remainder  dip  beneath  the  edges  of  the  annual 
rings,  which  break  their  continuity ; this  will  be  seen  when  the  sepiia  are  purposely  cut  through  by  the 
joiner’s  plane. 

Upon  inspecting  the  ends  of  the  most  handsome  and  showy  pieces  of  wainscot  oak  and  similar  woods, 
it  will  be  found  that  the  surface  of  the  board  is  only  at  a small  angle  with  the  lines  of  the  medullary 
rays,  so  that  many  of  the  latter  “crop  out”  upon  the  surface  of  the  work:  the  medullary  plates  being 
seldom  flat,  their  edges  assume  all  kinds  of  curvatures  and  elongations  from  their  oblique  intersections. 
All  these  peculiarities  of  the  grain  have  to  be  taken  into  account  in  cutting  up  woods,  when  the  most 
showy  character  is  a matter  of  consideration. 

The  same  circumstances  occur  in  a less  degree  in  all  the  woods  containing  the  silver  grain,  as  the 
oriental  plane-tree,  or  lacewood,  sycamore,  beech,  and  many  others,  but  the  figures  become  gradually 
smaller,  until  at  last,  in  some  of  the  foreign  hard  woods,  they  are  only  distinguishable  on  close  inspec- 
tion under  the  magnifier.  Some  of  the  foreign  hard  woods  show  lines  very  nearly  parallel,  and  at  right 
angles  to  the  axis  of  the  tree,  as  if  they  were  chatters  or  utters  arising  from  the  vibration  of  the  plane- 
iron.  The  medullary  rays  cause  much  of  the  beauty  in  all  the  showy  woods,  notwithstanding  that  the 
rays  may  be  less  defined  than  in  the  woods  cited.* 

Jn  many  of  the  handsomely  figured  woods,  some  of  the  effects  attributed  to  color  would,  as  in  dam- 
ask, be  more  properly  called  those  of  light  and  shade,  as  they  vary  with  the  point  of  view  selected 
for  the  moment.  The  end  grain  of  mahogany,  the  surfaces  of  the  table-cloth,  and  of  the  mother-of-pearl 
shell,  are  respectively  of  nearly  uniform  color,  but  the  figures  of  the  wood  and  the  damask  arise  from 
the  various  ways  in  which  they  reflect  the  light. 

Had  the  fibres  of  all  these  substances  been  arranged  with  the  uniformity  and  exactitude  of  a piece 
of  plain  cloth,  they  would  have  shown  an  even  uninterrupted  color,  but  fortunately  for  the  beautiful 
and  picturesque,  such  is  not  the  case ; most  fibres  are  arranged  by  nature  in  irregular  curved  lines,  and 
therefore  almost  every  intersection  through  them,  by  the  hand  of  man,  partially  removes  some  and 
exposes  others,  with  boundless  variety  of  figure. 

If  further  proof  were  wanted,  that  it  is  only  the  irregular  arrangement  that  causes  the  damask  or 
variegated  effect,  we  might  observe  that  the  plain  and  uniform  silk,  when  passed  in  two  thicknesses  face 
to  face,  between  smooth  rollers,  comes  out  with  the  watered  pattern ; the  respective  fibres  mutually 
emboss  each  other,  and  with  the  loss  of  their  former  regular  character  they  cease  to  reflect  the  uniform 
tintf 

To  so  boundless  an  extent  do  the  interferences  of  tints,  fibres,  curls,  knots,  &c.,  exist,  that  the  cab- 
inet-maker scarcely  seeks  to  match  any  pieces  of  ornamental  wood  for  the  object  he  may  be  constructing. 
He  covers  the  nest  of  drawers,  or  tliQ  table,  with  the  neighboring  veneers  from  the  same  block,  the 
proximity  of  the  sections  causing  but  a gradual  and  unobserved  difference  in  the  respective  portions  : 
as  it  would  be  in  vain  to  attempt  to  find  two  different  pieces  of  handsomely  figured  wood  exactly  alike. 

Variations  of  color. — The  figures  of  the  woods  depend  also  upon  the  color  as  well  as  on  the  fibre ; 
in  some  the  tint  is  nearly  uniform,  but  others  partake  of  several  shades  of  the  same  hue,  or  of  twro  or 
three  different  colors,  when  a still  greater  change  in  their  appearance  results. 

In  the  horizontal  sections  of  such  woods,  the  stripes  wind  partly  round  the  centre,  as  if  the  tree 
had  clothed  itself  at  different  parts  with  coats  of  varied  colors  with  something  like  caprice  : tulip-wood, 
kingwood,  zebra-wood,  rosewood,  and  many  others,  show  this  very  distinctly  ; and  in  the  ordinary  plank 
these  markiugs  get  drawn  out  into  stripes,  bands,  and  patches,  and  show  mottled,  dappled,  or  wavy  figures 
of  the  most  beautiful  or  grotesque  characters,  upon  which  it  would  be  needless  to  enlarge,  as  a glance 
at  the  display  of  the  upholsterer  will  convey  more  information  than  any  description,  even  when  assisted 
by  colored  figures.:): 

Those  wroods  which  are  variegated  both  in  grain  and  color,  such  as  Amboyna,  kingwood,  some 
mahogany,  maple,  partridge,  rosewood,  satin-wood,  snakewood,  tulip-wood,  zebra-wood,  and  others, 
are  more  generally  employed  for  objects  with  smooth  surfaces,  such  as  cabinet-work,  vases,  and  turned 
ornaments,  as  the  beauties  of  their  colors  and  figures  are  thereby  the  best  displayed.  Every  little  detail 
in  the  object  causes  a diversion  in  the  forms  of  the  stripes  and  marks  existing  in  the  wood  : these  ter- 
minate abruptly  round  the  mouldings  which  have  sharp  edges,  and  upon  the  flowing  lines  they  are 
undulated  with  infinite  variety  into  curves  of  all  kinds,  which  often  terminate  in  fringes  from  the  acci- 
dental intersections  of  the  stripes  in  the  woods. 

The  elegant  works  in  marquetry,  in  which  the  effect  of  flowers,  ornamental  devices,  or  pictures,  is 
attempted  by  the  combination  of  pieces  of  naturally  colored  woods,  are  invariably  applied  to  smooth 


* The  Cuticaem  liranco,  from  Carvalho  da  Terra,  Brazils,  and  Cuticaem  vcrmo , brought  over  by  Mr.  Morney,  (Admiralty 
Museum,)  show  the  silver  grain  very  prettily ; the  first  in  peculiar  straight  radial  stripes,  the  other  in  small  close  patches. 
The  llcioa-rewa , ( Knightia  cxcelsa,)  from  New  Zealand,  is  of  similar  kind;  all  would  be  found  handsome  light-colored 
furniture  woods. 

t The  brilliant  prismatic  colors  of  the  pearl  are  attributed  to  the  decomposition  and  reflection  of  the  light  by  the 
numerous  minute  grooves  or  stria:,  a more  vivid  effect  of  the  same  general  kind. 

A beautiful  artificial  example  of  the  same  description  was  produced  by  Sir  John  Barton,  comptroller  of  the  English 
mint;  he  engraved  with  the  diamond  the  surfaces  of  hard  steel  dies  in  lines  as  fine  as  2000  in  the  inch,  arranged  in  hex- 
agons, &c.  The  gold  buttons  struck  from  these  dies  display  the  brilliant  play  of  iridescent  colors  of  the  originals. 

X Attempls  have  been  made  to  stain  some  European  woods  during  their  growth,  by  inserting  certain  portions  of  their 
roots  in  vessels  tilled  with  coloring  matters,  but  we  are  not  aware  with  what  success.  It  is  not,  however,  to  be  expected 
.hat  such  a mode  would  be  either  so  effective  or  permanent  as  that  produced  by  the  natural  absorption  during  the  entire 
period  of  the  life  of  the  plant,  an  experiment  of  too  lengthened  and  speculative  a character  to  be  readily  undertaken. 


926 


WOODS,  VARIETIES  OF. 


surfaces.  In  the  same  manner  the  beautifully  tesselated  wood  floors,  abundant  in  the  buildings  of  one 
or  two  centuries  back,  which  exhibit  geometrical  combinations  of  the  various  ornamental  woods,  (an  art 
that  has  been  recently  pursued  in  miniature  by  the  Tunbridge  turners  in  tbeir  Mosaic  works,)  are  other 
instances,  that  in  such  cases  the  plain  smooth  surface  is  the  most  appropriate  to  display  the  effect  and 
variety  of  the  colors,  for  such  of  the  last  works  as  are  turned  into  mouldings  fail  to  give  us  the  same 
pleasure. 

Even-tinted  woods  are  best  suited  to  the  work  of  the  eccentric  chuck,  the  revolving  cutters,  and 
other  instruments  to  be  explained;  in  which  works,  the  carving  is  the  principal  source  of  ornament: 
the  variation  of  the  wood,  in  grain  or  color,  when  it  occurs,  together  with  the  cutting  of  the  surface,  is 
rather  a source  of  confusion  than  otherwise,  and  prevents  the  effect  either  of  the  material,  or  of  the 
work  executed  upon  it,  from  being  thoroughly  appreciated. 

The  transverse  section,  or  end  grain  of  the  plain  woods,  is  the  most  proper  for  eccentric  turning,  as 
all  the  fibres  are  then  under  the  same  circumstances ; many  of  the  woods  will  not  admit  of  being  worked 
with  such  patterns,  the  plankway  of  the  grain:  and  of  all  the  woods  the  black  Botany  Bay  wood,  or 
the  Black  African  wood,  by  which  name  soever  it  may  be  called,  is  most  certainly  the  best  for  eccen- 
tric turning;  next  to  it,  and  nearly  its  equal,  is  the  cocoa-wood,  (from  the  West  Indies,  not  the  cocoa- 
nut  palm ;)  several  others  may  also  be  used,  but  the  choice  should  always  fall  on  those  which  are  of 
uniform  tint,  and  sufficiently  hard  and  close  to  receive  a polished  surface  from  the  tool , as  such  works 
admit  of  no  subsequent  improvement. 

Contrary  to  the  rule  that  holds  good  with  regard  to  most  substances,  the  colors  of  the  generality  of 
the  woods  become  considerably  darker  by  exposure  to  the  light ; tulip-wood  is,  we  believe,  the  only  one 
that  fades.  The  tints  are  also  rendered  considerably  darker  from  being  covered  with  oil  or  lacker,  and 
although  the  latter  checks  their  assuming  the  deepest  hues,  it  does  not  entirely  prevent  the  subsequent 
change.  The  yellow  color  of  the  ordinary  varnishes  greatly  interferes  also  with  the  tints  of  the  light 
woods,  for  which  the  whitest  possible  kinds  should  be  selected.*  When  it  is  required  to  give  to  wood 
that  has  been  recently  worked  the  appearance  of  that  which  has  become  dark  from  age,  as  in  repair- 
ing any  accident  in  furniture,  it  is  generally  effected  by  washing  it  with  lime-water;  or,  in  extreme 
cases,  by  laying  on  the  lime  as  water-color,  and  allowing  it  to  remain  for  a few  minutes,  hours,  or  days, 
according  to  circumstances.  In  many  cases  the  colors  of  the  woods  are  heightened  or  modified,  by 
applying  coloring  matters  either  before,  or  with  the  varnish ; and  in  this  manner  handsome  bircliwood 
is  sometimes  converted  into  factitious  mahogany,  by  a process  of  coloring  rather  than  dyeing,  that  often 
escapes  detection. 

The  bog-oak  is  by  some  considered  to  assume  its  black  color  from  the  small  portion  of  iron  contained 
in  the  bog  or  moss,  combining  with  the  gallic  acid  of  the  wood,  and  forming  a natural  stain,  similar  to 
writing  ink.  Much  of  the  oak  timber  of  the  Royal  George,  that  was  accidentally  sunk  at  Spithead,  in 
1782,  and  which  has  been  recently  extricated  by  Colonel  Pasley’s  sub-marine  explosions,  is  only 
blackened  on  its  outer  surface,  and  the  most  so  in  the  neighborhood  of  the  pieces  of  iron  ; the  inside  of 
the  thick  pieces  is,  in  general,  of  nearly  its  original  color  and  soundness.  Some  specimens  of  camwood 
have  maintained  their  original  beautiful  red  and  orange  colors,  although  the  inscription  says  that  they 
were  “ washed  on  shore  at  Kay  Haven,  in  October,  1840,  with  part  of  the  wreck  of  the  Royal  Tar,  lost 
near  the  Needles  twenty  years  ago,  when  all  the  crew  perished.” 

The  recent  remarks  on  color  apply  equally  to  the  works  of  statuary,  carving,  and  modelling  gener- 
ally : the  materials  for  which  are  either  selected  of  one  uniform  color,  or  they  are  so  painted.  Then 
only  is  the  full  effect  of  the  artist’s  skill  apparent  at  tire  first  glance  ; otherwise  it  frequently  happens 
either  that  the  eye  is  offended  by  the  interference  of  the  accidental  markings,  or  fails  to  appreciate  the 
general  form  or  design,  without  a degree  of  investigation  and  effort  that  detracts  from  the  gratification 
which  would  be  otherwise  immediately  experienced  on  looking  at  such  carved  works. 

This  leads  me  to  advert  to  modes  sometimes  practised  to  produce  the  effect  of  carving ; thus,  in  the 
Manuel  du  Tourneurf  a minute  description  will  be  found  of  the  mode  of  making  embossed  wooden 
boxes,  which  are  pressed  into  metallic  moulds,  engraved  with  any  particular  device.  The  wood  is  first 
turned  to  the  appropriate  shape,  and  then  forced  by  a powerful  screw-press  into  the  heated  mould, 
(which  is  made  just  hot  enough  to  avoid  materially  discoloring  the  wood;)  it  is  allowed  to  remain  in 
that  situation  until  it  is  cold ; this  method,  however,  only  applies  to  subjects  in  small  relief,  and  is 
principally  employed  on  knotty  pieces  of  boxwood  and  olive-wood  of  irregular  curly  grain. 

The  following  method  may  be  used  for  bolder  designs,  more  resembling  ordinary  carving : the  fine 
sawdust  of  any  particular  wood  it  is  required  to  imitate,  is  mixed  with  glue  or  other  cementitious  mat- 
ter, and  squeezed  into  metallic  moulds ; but  in  the  latter  case  the  peculiar  characteristic  of  the  wood, 
namely,  its  fibrous  structure,  is  entirely  lost,  and  the  eye  only  views  the  work  as  a piece  of  cement  or 
composition,  which  might  be  more  efficiently  produced  from  other  materials,  and  afterwards  colored. 

Each  of  these  processes  partakes  rather  of  the  proceeding  of  the  manufacturer  than  of  the  amateur ; 
extensive  preparations,  such  as  very  exact  moulds  consisting  of  several  parts,  a powerful  press  and 
other  apparatus,  are  required,  and  the  results  are  so  proverbially  alike,  from  being  “ formed  in  the 
same  mould,”  that  they  lose  the  interest  attached  to  original  works,  in  the  same  manner  that  engravings 
are  less  valued  than  the  original  paintings  from  which  they  are  copied. 

Another  method  of  working  in  wood  may  be  noticed,  which  is  at  any  rate  free  from  the  objections 
recently  advanced : we  will  transcribe  its  brief  description.^; 

“ Raised  figures  on  wood,  such  as  are  employed  in  picture-frames  and  other  articles  of  ornamental 
cabinet-work,  are  produced  by  means  of  carving,  or  by  casting  the  pattern  in  Paris  plaster  or  other 


* Specimens  of  woods  for  cabinets  should  be  left  in  their  natural  state,  or  at  most  they  should  be  polished  by  friction 
only ; or,  if  varnished,  then  upon  the  one  side  alone.  Their  colors  are  best  preserved  when  they  are  excluded  from  tin 
light,  either  in  drawers  or  in  glass  cases  covered  with  some  thick  blind, 
t Second  edition,  vol.  ii.,  pp.  441-451.  J Transactions  of  the  Society  of  Arts,  xlii.,  p.  B. 


WOODS,  VARIETIES  OF. 


927 


composition,  and  cementing  or  otherwise  fixing  it  on  the  surface  of  the  wood.  The  former  mode  is 
expensive,  the  latter  is  inapplicable  on  many  occasions. 

The  invention  of  Mr.  Straker  may  be  used  either  by  itself  or  in  aid  of  carving ; and  depends  on  the 
facts,  that  if  a depression  be  made  by  a blunt  instrument  on  the  surface  of  wood,  such  dejrressed  part 
will  again  rise  to  its  original  level  by  subsequent  immersion  in  water. 

“ The  wood  to  be  ornamented  having  first  been  worked  out  to  its  proposed  shape,  is  in  a state  to 
receive  the  drawing  of  the  pattern ; this  being  put  in,  a blunt  steel  tool,  or  burnisher,  or  die,  is  to  be 
applied  successively  to  all  those  parts- of  the  pattern  intended  to  be  in  relief,  and  at  the  same  time  is 
to  be  driven  very  cautiously,  without  breaking  the  grain  of  the  wood,  till  the  depth  of  the  depression 
is  equal  to  the  subsequent  prominence  of  the  figures.  The  ground  is  then  to  be  reduced  by  planing 
or  filing  to  the  level  of  the  depressed  part ; after  which,  the  piece  of  wood  being  placed  in  water, 
either  hot  or  cold,  the  parts  previously  depressed  will  rise  to  their  former  height,  and  will  thus  form  an 
embossed  pattern,  which  may  be  finished  by  the  usual  operations  of  carving.'’ 

Shrinking  and  warping. — The  permanence  of  the  form  and  dimensions  of  the  woods  require  par- 
ticular consideration,  even  more  than  their  comparative  degrees  of  ornament,  especially  as  concerns 
tnose  works  which  consist  of  various  parts,  for  unless  they  are  combined  with  a due  regard  to  the 
strength  of  the  pieces  in  different  directions,  and  to  the  manner  and  degree  in  which  they  are  likely  to 
be  influenced  by  the  atmosphere,  the  works  will  split  or  warp,  and  may  probably  be  rendered  entirely 
useless. 

The  piece  of  dried  wood  is  materially  smaller  than  in  its  first  or  wet  state,  and  as  it  is  at  all  times 
liable  to  re-absorb  moisture  from  a damp  atmosphere,  and  to  give  it  off  to  a dry  one,  even  after  having 
been  thoroughly  seasoned,  the  alterations  of  size  again  occur,  although  in  a less  degree. 

The  change  in  the  direction  of  the  length  of  the  fibres  is  in  general  very  inconsiderable.*  It  is  so 
little  in  those  of  straight  grain,  that  a rod  split  out  of  clean  fir  or  deal  is  sometimes  employed  as  the 
pendulum  of  a clock,  for  which  use  it  is  only  inferior  to  some  of  the  compensating  pendulums : whereas 
a piece  of  the  same  wood  taken  diametrically  out  of  the  centre  of  a tree,  or  the  crossway  of  the  grain, 
forms  an  excellent  hygrometer,  and  indicates  by  its  change  of  length  the  comparative  degree  of  moist- 
ure of  the  atmosphere.  The  important  difference  in  the  general  circumstances  of  the  woods,  in  the 
two  directions  of  the  grain,  we  propose  to  notice,  first  as  regards  the  purposes  of  turning,  and  afterwards 
those  of  joinery  work,  which  will  render  it  necessary  to  revert  to  the  wood  in  its  original,  or  unseasoned 
state. 

The  turner  commonly  employs  the  transverse  section  of  the  wood,  and  we  may  suppose  the  annual 
rings  then  exhibited  to  consist  of  circular  rows  of  fibres  of  uniform  size,  each  of  which,  for  -the  sake  of 
explanation,  I will  suppose  to  be  the  one-hundredth  of  an  inch  in  diameter. 

When  the  log  of  green  wood  is  exposed  to  a dry  atmosphere,  the  outer  fibres  contract  both  at  the 
sides  and  ends,  whereas  those  within  are  in  a measure  shielded  from  the  immediate  effect  of  the  atmos- 
phere, and  nearly  retain  their  original  dimensions.  Supposing  all  the  outside  fibres  to  be  reduced  to 
the  one  hundred  and  tenth,  or  the  one  hundred  and  twentieth  of  an  inch,  as  the  external  series  can  no 
longer  fill  out  the  original  extent  of  the  annual  ring,  the  same  as  they  did  before  they  were  dried  ; they 
divide,  not  singly,  but  into  groups,  as  the  unyielding  centre,  or  the  incompressible  mass  within  the  arch, 
causes  the  parts  of  which  the  latter  is  composed  to  separate,  and  the  divisions  occur  in  preference  at 
the  natural  indentations  of  the  margin,  which  appear  to  indicate  the  places  where  the  splits  are  likely 
to  commence. 

The  ends  being  the  most  exposed  to  the  air,  are  the 
first  attacked,  and  there  the  splits  are  principally 
radial,  with  occasional  diversions  concentric  with  the 
layers  of  fibres,  as  in  Fig.  3937,  and  on  the  side  of  the 
log  the  splits  become  gradually  extended  in  the  direc- 
tion of  its  length.  The  air  penetrates  the  cracks,  and 
extends  both  cause  and  effect,  and  an  exposure  of  a 
few  weeks,  days,  or  even  one  day,  to  a hot,  dry  atmos- 
phere, will  sometimes  spoil  the  entire  log,  and  the 
more  rapidly  the  harder  the  wood,  from  its  smaller 
penetrability  to  the  air.  This  effect  is  in  part  stayed 
by  covering  the  ends  of  the  wood  with  grease,  wax, 
glue,  or  paper,  to  defend  them,  but  the  best  plan  is  to 
transfer  the  pieces  very  gradually  from  the  one  atmos- 
phere to  the  other,  to  expose  them  equally  to  the  air 
at  all  parts,  and  to  avoid  the'  influence  of  the  sun  and 
hot,  dry  air. 

The  horizontal  slice  or  block  of  the  entire  tree  is  the 
most  proper  for  the  works  of  the  lathe,  as  it  is  presented  by  nature  the  most  nearly  prepared  to  oui 
hand,  and  its  appearance,  strength,  grain,  and  shrinking,  are  the  most  uniform.  The  annual  rings,  if  any 
be  visible,  are,  as  in  Fig.  3938,  nearly  concentric  with  the  object,  the  fibres  around  the  circumference  are 


393/. 


* Good  boxwood  and  lancewood  were  approved  as  materials  for  the  verified  scales  to  be  employed  in  laying  down  the 
plans  for  the  recent  parliamentary  survey,  as  being  next  in  accuracy  to  those  of  metal ; whereas  scales  of  ivory  are  entirely 
rejected  by  them,  owing  to  their  material  variation  in  length  under  hygrometrical  influence.  See  their  printed  papers. 

Mr.  Fincham  says  he  has  found  a remarkable  variation  in  the  New  Zealand  pine,  the  Kowrie  or  Cowrie,  corrupted  into 
Cowdie,  which  expands  so  much  as  to  cause  the  strips  constituting  the  inside  mouldings  of  ships  to  expand  and  buckle, 
probably  from  the  comparative  moisture  of  our  atmosphere;  and  Colonel  Lloyd  says  he  found  the  teak  timbers  used  by 
nim  in  constructing  a large  room  in  the  Mauritius,  to  have  shrunk  three-quarters  of  an  inch  in  lentr'h  in  thirty-eigh*  leei, 
although  this  wood  is  by  many  considered  to  shrink  sideways  least  of  all  others. 


928 


WOODS,  VARIETIES  OF. 


alike,  and  the  contraction  occurs  without  causing  any  sensible  departure  from  the  circular  form.  Al- 
though thin  transverse  slices  are  necessarily  weak  from  the  inconsiderable  length  of  the  fibres  of  which 
they  are  composed,  (equal  only  in  length  to  the  thickness  of  the  plate,)  they  are  strengthened  in  the 
generality  of  turned  works  by  the  margin,  such  as  we  find  in  the  rim  of  a snulf-box,  which  supports  the 
bottom  like  the  hoop  of  a drum  or  tamborine. 

The  entire  circular  section  is  therefore  most  appropriate  for  turning ; next  to  it  the  quartering,  Fig. 
3939,  should  be  chosen,  but  its  appearance  is  less  favorable ; and  a worse  effect  happens,  as  the  shrink- 
ing causes  a sensible  departure  from  the  circle,  the  contraction  being  invariably  greater  upon  the  circu- 
lar arcs  of  fibres,  than  the  radial  lines  or  medullary  rays.  If  such  works  be  turned  before  the  materials 


3938.  3939.  3940. 


are  thoroughly  prepared,  they  will  become  considerably  oval ; so  much  so,  that  a manufacturer  who  is 
in  the  habit  of  working  up  large  quantities  of  pear-tree,  informs  me  that  hollowed  pieces  rough-turned 
to  the  circle,  alter  so  much  and  so  unequally  in  the  drying,  that  works  of  three  inches  will  sometimes 
shrink  half  an  inch  more  on  the  one  diameter  than  the  other,  and  become  quite  oval ; it  is  therefore 
necessary  to  leave  them  half  an  inch  larger  than  the  intended  size.  Even  in  woods  that  were  com- 
paratively dry,  a small  difference  may  in  general  be  detected  by  the  callipers,  when  they  have  been 
turned  some  time,  from  their  unequal  contraction. 

In  pieces  cut  lengthways,  such  as  Fig.  3940,  circumstances  are  still  less  favorable ; there  being  no 
perceptible  contraction  in  the  length  of  the  fibres,  the  whole  of  the  shrinking  takes  place  laterally,  at 
right  angles  to  them,  and  the  wTork  becomes  oval  to  the  full  extent  of  the  contraction  that  occurs  in  the 
fibres. 

The  plank-wood  is  almost  solely  employed  for  large  disks  which  would  be  too  weak  if  cut  out  trans- 
versely ; and  in  some  cases  for  objects  made  of  those  ornamental  woods  which  are  best  displayed  in 
that  section,  as  the  tulip,  rose,  king,  zebra,  partridge,  and  satin  woods.  Specimens  of  oak  from  ancient 
buildings  are  sometimes  thus  worked,  but  in  all  such  cases  the  wood  should  be  exceedingly  well  dried 
beforehand ; otherwise,  in  addition  to  the  inconvenience  arising  from  the  greater  departure  from  the 
circle,  the  pieces  will  warp  and  twist,  an  effect  that  more  generally  concerns  the  joiner’s  art,  and  to  the 
consideration  of  which  we  will  now  proceed. 

When  the  green  wood  is  cut  up  into  planks,  boards,  and  veneers,  the  splitting  which  occurs  in  the 
transverse  section  is  less  to  be  feared  than  distortion  or  warping,  from  the  unequal  contraction  of  the 
fibres.  Thick  planks  are  partially  stayed  from  splitting  and  opening,  by  cleets  nailed  upon  each  end ; 
boards  are  left  unprotected,  and  veneers  are  protected  from  accidental  violence  by  slips  of  cloth  glued 
upon  each  end. 

One  plank  only  in  each  tree  can  be  exactly  diametrical,  the  others  are  parallel  therewith,  and,  as 
shown  in  Fig.  3937,  the  two  sides  of  all  the  boards,  but  that  from  the  centre  are  differently  circum- 
stanced as  regards  the  arrangement  of  the  fibres,  and  contract  differently.  It  will  be  generally  found 
that  the  boards  exposed  to  similar  conditions  on  both  sides,  become,  from  the  simple  effect  of  drying, 
convex  on  the  side  towards  the  centre  of  the  tree ; this  will  be  explained  by  a reference  to  the  diagram. 


3941. 


Fig.  3941,  which  shows  that  the  longest  continuous  line  of  fibres  is  concentric  with  the  axis  of  the  tree. 
Thus  let  a,  h,  c,  d,  e,f  represent  the  section  of  a board,  the  line  b e of  which  is  supposed  to  contain  five 
fibres,  and  the  arc  d bf  thirty : therefore,  supposing  every  fibre  to  shrink  alike  in  general  dimensions, 
the  contraction  on  the  arc  will  be  six  times  that  upon  the  short  radial  line,  and  the  new  margin  of  the 
board  will  be  the  dotted  line  which  proceeds  from  g to  h,  the  departure  of  which  from  the  original 
straight  line  will  be  five  times  as  much  at  d as  at  e. 


3942. 

1 2 3 4 5 6 


This  is  not  imaginary,  as  it  is  in  all  cases  borne  out  by  observation,  where  the  pieces  are  exposed  to 
similar  circumstances  on  both  sides.  When  a true  flat  board  is  wanted,  it  is  a common  practice  to  saw 


WOODS,  VARIETIES  OF. 


02!) 


the  wide  plank  in  two  or  four  pieces,  to  change  sides  with  them  alternately,  and  glue  them  together 
again,  as  in  Fig.  3942,  so  that  the  pieces  1,  3,  5 may  present  the  sides  towards  the  axis  of  the  tree,  and 
2,4,  6 those  towards  its  circumference  ; the  curvature  from  shrinking  will  then  become  a serpentine  line 
consisting  of  six  arcs,  instead  of  one  continuous  circular  sweep. 

When  the  opposite  sides  of  a board  are  exposed  to  unequal  conditions,  the  moisture  will  swell  the 
fibres  on  the  one  side  and  make  that  convex,  and  in  the  opposite  manner  that  exposed  to  the  dry  air 
or  heat  will  contract  and  become  concave  ; from  these  circumstances',  when  several  pieces  of  wood  are 
placed  around  the  room  or  before  the  fire,  “ to  air’'  the  sides  should  be  continually  changed,  that  both 
may  have  equal  treatment,  so  as  to  lessen  the  tendency  to  curvature.  To  remedy  the  defect  when  it 
may  have  occurred,  the  joiner  exposes  the  convex  side  to  the  fire,  but  it  is  obviously  better  to  be  spar  - 
ing of  these  sudden  changes. 

Any  unequal  treatment  of  the  two  sides  is  almost  sure  to  curl  the  board ; if,  for  instance,  we  paste 
a sheet  of  paper  upon  one  side  of  a board,  it  will  in  the  first  instance  swell  the  surface  and  make  it 
convex ; as  the  paper  dries  it  contracts,  it  forces  the  wood  to  accompany  it,  and  the  papered  side  be- 
comes hollow  ; when  two  equal  papers  are  pasted  on  opposite  sides,  this  change  does  not  generally 
occur.  A similar  effect  is  often  observed  when  a veneer  is  glued  on  a piece  of  wood  ; hence  it  is  usual 
to  swell  the  surface  on  which  the  veneer  is  to  be  laid,  by  wetting  it  with  a sponge  dipped  in  thin  size, 
so  as  to  make  it  moderately  round ; in  this  case,  the  wetted  surface  of  the  board,  and  the  glued  surface 
of  the  veneer,  are  expanded  nearly  alike  by  the  moisture,  and  in  drying  they  also  contract  alike,  so  that 
under  favorable  management  the  board  recovers  its  true  flat  figure. 

The  woods  are  much  less  disposed  to  become  curved  in  the  direction  of  their  length,  than  crossways ; 
but  another  evil  equally  or  more  untractable  is  now  met  with,  as  the  general  figure  of  the  board  is  more 
or  less  disposed  to  twist  and  warp,  so  that  when  it  is  laid  upon  a flat  surface  it  touches  only  at  the  two 
diagonal  corners,  and  is  said  to  be  “ in  winding.”  This  error  is  the  less  experienced  in  the  straight- 
grained pines  and  mahogany,  which  are  therefore  selected  for  works  in  which  constancy  of  figure  is  a 
matter  of  primary  importance,  as  in  models  for  the  foundry,  and  objects  exposed  to  great  vicissitudes 
of  climate. 

The  warping  may  arise  from  the  curved  direction  of  the  fibres  in  respect  to  the  length  of  the  plank, 
and  also  from  the  spiral  direction  in  which  many  trees  grow ; in  some,  for  example,  the  furrows  of  the 
bark  are  frequently  twisted  as  much  as  fifteen  or  twenty  degrees  from  the  perpendicular,  and  some- 
times even  thirty  and  forty.  The  woods  themselves  when  split  through  the  centre  of  the  tree  differ 
materially ; they  sometimes  present  a tolerably  flat  surface,  at  others  they  are  much  in  winding  or 
twisted,  a further  corroboration  of  the  “spiral  growth;”  we  cannot  be  therefore  much  surprised  that 
the  planks  cut  out  from  such  woods  should  in  a degree  pursue  the  paths  thus  early  impressed  upon 
them. 

Boxwood  is  often  very  much  twisted  in  this  manner.  The  writer  had  a block,  the  diameter  of  which 
was  nine  inches ; its  surface  was  split  at  five  parts,  with  spiral  grooves,  at  an  angle  of  nearly  thirty 
degrees  with  the  axis ; these  made  exactly  one  complete  revolution,  or  one  turn  of  a screw  in  the  length 
of  the  piece,  which  was  just  three  feet. 

On  the  other  hand,  the  Alerce,  a pine  growing  in  the  island  of  Chiloe  in  South  America,  to  the  diam- 
eter of  about  four  feet,  and  whose  wood  resembles  the  cedar  of  Lebanon  in  color,  is  so  remarkably 
straight  in  the  grain,  that  it  is  the  custom  of  the  country  to  split  it  into  planks  about  eight  feet  long  and 
seven  inches  wide,  which  are  almost  as  true  as  if  they  were  cut  witli  the  saw,  although  of  course  not 
cpiite  so  smooth. 

To  correct  the  errors  of  winding  and  curvature  in  length,  the  joiner,  :'n  working  upon  rigid  pieces,  first 
planes  off  the  higher  points  so  as  to  produce  the  true  form  by  reduction.  But  when  the  objects  are 
long  and  thin,  they  are  corrected  by  the  hands,  just  as  we  should  straighten  a cane,  or  a walking  stick, 
except  that  the  one  angle  of  the  board  is  rested  upon  the  bench  or  floor,  the  other  is  held  in  the  hand, 
and  the  pressure  is  applied  between  them. 

Broad  thin  pieces  are  sometimes  warmed  on  both  sides  before  the 
fire  to  lessen  their  rigidity ; they  are  then  fixed  between  two  stout 
flat  boards  by  means  of  several  hand-screws,  and  allowed  to  remain 
until  they  are  quite  cold ; this  is  just  the  reverse  of  the  mode  of  bend- 
ing timber  for  ship-building  and  other  purposes,  but  applied  in  a less 
elaborate  manner. 

In  concluding  this  division  of  the  subject,  we  may  observe  that  the 
shrinking  and  contracting  of  the  straight-grained  woods,  especially 
deal  and  mahogany,  cause  but  little  distortion  of  their  general  shape 
after  they  have  been  properly  dried ; but  the  diversity  of  grain,  a 
principal  cause  of  beauty  of  figure  in  the  ornamental  woods,  is  at  the 
same  time  a source  of  confusion  in  their  shrinking,  which  being  called 
on  to  pursue  many  paths,  (which  are  parallel  with  the  fibres,  however 
tortuous,)  gives  rise  to  a greater  disturbance  from  the  original  shape, 
or  in  extreme  cases,  even  causes  them  to  split  where  the  contraction 
is  restrained  by  the  peculiarity  of  growth. 

In  the  handsome  furniture  woods  the  economy  of  manufacture  cor- 
rects this  evil,  as  from  their  great  value  they  are  cut  into  very  thin 
slices  or  veneers,  and  glued  upon  a stout  fabric  of  straight-grained 
wood,  commonly  inferior  mahogany,  cedar,  or  deal,  by  which  the  op- 
posite characters,  of  beauty  of  appearance  and  permanence  of  form,  are  combined  at  a moderate  ex- 
pense ; these  processes  will  be  explained. 

Combining  different  pieces  of  wood. — In  combining  several  pieces  of  wood  for  works  in  carpentry 
and  cabinet-makiug,  the  different  circumstances  of  the  plank  as  respects  its  length  and  width  should 
Yon.  II. — 59 


3943. 


930 


WOODS,  VARIETIES  OF. 


l>e  always  borne  in  mind.  Provision  must  be  made  that  the  shrinking  and  swelling  are  as  little  re- 
strained as  possible,  otherwise  the  pieces  may  split  and  warp  with  an  irresistible  force : and  the  prin- 
cipal reliance  for  permanence  or  standing,  should  be  placed  on  those  pieces,  (or  lines  of  the  work,)  cut 
out  the  lengthway  of  the  plank,  which  are,  as  before  explained,  much  less  disposed  to  break  or  become 
crooked,  than  the  crossway  sections : these  particulars  will  be  more  distinctly  shown  by  one  or  twe 
illustrations. 

Let  abed  represent  the  flat  surface  of  a board  ; e f,  the  edge  of  the  same,  and  g li  the  end ; no  con- 
traction will  occur  upon  the  line  e f or  the  length,  and  in  the  general  way,  that  line  will  remain 
pretty  straight  and  rigid;  but  the  whole  of  the  shrinking  will  take  place  on  gh,  the  width,  which  is 
slender,  flexible,  and  disposed  to  become  curved  from  any  unequal  exposure  to  the  air;  the  four 
marginal  lines  of  abed,  are  not  likely  to  alter  materially  in  respect  to  each  other,  but  they  will 
remain  tolerably  parallel  and  square,  if  originally  so  formed. 

A dovetailed  box  consists  of  six  such  pieces,  the  four  sides  of  which,  ABCD,  Fig.  3944,  are  inter- 
laced at  the  angles  by  the  dovetails,  so  that  the  flexible  lines,  as  g h,  on  B,  are  connected  with,  and 
strengthened  by,  the  strong  lines,  as  c d,  on  A,  and  so  on : the  whole  collectively  form  a very  rigid 
frame,  the  more  especially  when  the  bottom  piece  is  fixed  to  the  sides  by  glue  or  screws,  as  it  entirely 
removes  from  them  the  small  power  of  racking  upon  the  four  angles,  (by  a motion  like  that  of  the 
jointed  parallel  rule,)  which  might  happen  if  the  dovetails,  shown  on  a larger  scale  in  Fig.  3945,  were 
loosely  fitted. 

3945.  3944. 


When  the  grain  of  the  four  sides  ABCD  runs  in  the  same  direction,  or  parallel  with  the  edges  Of 
the  box  or  drawer,  as  shown  by  the  shade  lines  on  A and  B,  and  the  pieces  are  equally  wet  or  dry, 
hey  will  contract  or  expand  equally,  and  without  any  mischief  or  derangement  happening  to  the  work ; 
to  insure  this  condition,  the  four  sides  are  usually  cut  out  of  the  same  plank.  But  if  the  pieces  had  the 
grain  in  different  directions,  as  C and  D,  and  the  twro  were  nailed  together,  D would  entirely  prevent 
the  contraction  or  expansion  of  C,  and  the  latter  would  probably  be  split  or  cast,  from  being  restrained. 
When  admissible,  it  is  therefore  usual  to  avoid  fixing  together  those  pieces,  in  which  the  grain  runs 
respectively  lengthways  and  crossways,  especially  where  apprehension  exists  of  the  occurrence  of 
swelling  or  shrinking. 

A wide  board,  Fig.  8945-J-,  composed  of  the  slips  ABODE,  (reversed  as  in  Fig.  3942,)  is  rendered 
still  more  permanent,  and  very  much  stronger,  when  its  ends  are  confined  by  two  clamps,  such  as  G H, 
(one  only  seen ;)  the  shade  lines  represent  the  direction  of  the  grain.  The  group  of  pieces,  A to  E,  con- 
tract in  width  upon  the  line  A E,  and  upon  it  they  are  also  flexible,  whereas  the  clamp  G H is  strong 
and  incapable  of  contraction  in  that  direction,  and  therefore  unless  the  wood  is  thoroughly  dry  the  two 
parts  should  be  connected  in  a manner  that  will  allow  for  the  alteration  of  the  one  alone.  This  is 
effected  by  the  tongue  and  groove  fitting  as  represented  ; the  end  piece  G H is  sometimes  only  fastened 
by  a little  glue  in  the  centre  of  its  length,  but  in  cabinet-work,  where  the  seasoning  of  the  wood  is  gen- 
erally better  attended  to,  it  is  glued  throughout. 


If  the  clamp  GII  were  fixed  by  tenons,  (one  of  which,  ij,  is  shown  detached  in  Fig.  3946,)  the  con 
fraction  of  the  part  of  the  board  between  the  tenons  might  cause  it  to  split,  the  distance  between  the 


WOODS,  VARIETIES  OF. 


931 


mortises  in  G H being  unalterable ; or  the  swelling  of  the  board  might  cause  it  to  bulge,  and  become 
rounding ; or  the  entire  frame  would  twist  and  warp,  as  the  expansion  of  the  centre  might  be  more 
powerful  than  the  resistance  to  change  in  the  two  clamps,  and  force  them  to  bend. 

It  is  therefore  obvious  that  if  any  question  exist  as  to  the  entire  and  complete  dryness  of  the  wood, 
the  use  of  clamps  is  hazardous;  although  in  their  absence,  the  shrinking  might  tear  away  the  wood 
from  the  plain  glue-joint,  even  if  it  extended  entirely  across,  without  causing  any  further  mischief,  but 
more  generally  the  shrinking  would  split  the  solid  board. 

Another  mode  of  clamping  is  represented  at  K ; it  is  there  placed  edgeways,  and  attached  by  an 
undercut  or  dovetailed  groove,  slightly  taper  in  its  length,  and  is  fixed  by  a little  glue  at  the  larger 
end,  which  holds  the  two  in  firm  contact : each  of  these  modes,  and  some  others,  are  frequently  em- 
ployed for  the  large  drawing-boards  required  by  architects  and  engineers  for  the  drawings  made  with 
squares  and  instruments. 

From  a similar  motive,  the  thin  bottom  of  a drawer  is  grooved  into  the  two  sides  and  front,  and  only 
fixed  to  the  back  of  the  drawer  by  a few  small  screws  or  brads,  so  that  it  may  swell  or  shrink  without 
splitting,  which  might  result  were  it  confined  all  around  its  margin.  It  is  more  usual,  however,  to  glue 
thin  slips  along  the  sides  of  large  drawers,  as  in  Fig.  3947,  which  strengthen  the  sides,  and  being  grooved 
to  receive  the  bottom,  allow  it  to  shrink  without  interfering  either  with  the  front  or  back  of  the  drawer. 

In  an  ordinary  door  with  two  or  more  panels,  all  the  marginal  pieces  ruu  lengthways  of  the  grain ; 
the  two  sides,  called  the  stiles,  extend  the  whole  height,  and  receive  the  transverse  pieces  or  rails,  now 
mortised  through  the  stiles,  and  wedged  tight,  but  without  risk  of  splitting,  on  account  of  their  small 
width ; every  panel  is  fitted  into  a groove  within  four  edges  of  the  frame.  The  width  of  the  panel 
should  be  a trifle  less  than  the  extreme  width  of  the  grooves,  and  even  the  mouldings,  when  they  are 
not  worked  in  the  solid,  are  fixed  to  the  frame  alone,  and  not  to  the  panel,  that  they  may  not  interfere 
with  its  alterations  ; therefore  in  every  direction,  we  have  the  framework  in  its  strongest  and  most 
permanent  position  as  to  grain,  and  the  panel  is  unrestrained  from  alteration  in  width  if  so  disposed. 

This  system  of  combination  is  carried  to  a great  extent  in  the  tops  of  mahogany  billiard-tables,  which 
consist  of  numerous  panels  about  8 inches  square,  the  frames  of  which  are  3-J-  in.  wide  and  1-^-  in.  thick ; 
the  panels  are  ploughed  and  tongued,  so  as  to  be  level  on  the  upper  side,  and  from  their  small  size  the 
individual  contraction  of  the  separate  pieces  is  insignificant,  and  consequently  the  general  figure  of  the 
table  is  comparatively  certain.  Of  late  years,  we  are  told  that  slate,  a material  uninfluenced  by  the 
atmosphere,  has  been  almost  exclusively  used ; the  top  of  a full-sized  table,  of  1 2 by  6 feet,  consists 
of  four  slabs  one  inch  thick,  ground  on  their  lower,  and  planed  by  machinery  on  their  upper  surfaces : 
the  iron  tables  are  almost  abandoned  for  several  reasons.  Large  thin  slates,  from  their  permanence  of 
form,  are  sometimes  used  by  engineers  and  others  for  drawing  upon,  and  also  in  carpentry  for  the 
panels  of  superior  doors. 

On  glueing  various  works  in  wood. — Glue  is  the  cement  used  for  joining  different  pieces  of  wood  ; 
it  is  a common  jelly,  made  from  the  scraps  that  are  pared  off  the  hides  of  animals  before  they  are 
subjected  to  the  tan-pit  for  conversion  into  leather.  The  inferior  kinds  of  glue  are  often  contaminated 
with  a considerable  portion  of  the  lime  used  for  removing  the  hair  from  the  skins,  but  the  better  sorts 
are  transparent,  especially  the  thin  cakes  of  the  Salisbury  glue,  which  are  of  a clear  amber  color. 

In  preparing  the  glue  for  use,  it  is  most  usually  broken  into  small  pieces,  and  soaked  for  about 
twelve  hours  in  as  much  water  as  will  cover  it ; it  is  then  melted  in  a glue-kettle,  which  is  a double 
vessel  or  water-bath,  the  inner  one  for  the  glue,  the  outer  for  the  water,  in  order  that  the  temperature 
applied  may  never  exceed  that  of  boiling  water.  The  glue  is  allowed  at  first  to  simmer  gently  for  one 
or  two  hours,  and  if  needful  it  is  thinned  by  the  addition  of  hot  water,  until  it  runs  from  the  brush  in  a 
fine  stream;  it  should  be  kept  free  from  dust  and  dirt  by  a cover,  in  which  a notch  is  made  for  the 
brush.  Sometimes  the  glue  is  covered  with  water,  and  boiled  without  being  soaked. 

Glue  is  considered  to  act  in  a twofold  manner,  first  by  simple  adhesion,  and  secondly  by  excluding 
the  air,  so  as  to  bring  into  action  the  pressure  of  the  atmosphere.  The  latter,  however,  alone  is  an 
insufficient  explanation,  as  the  strength  of  a well-made  glue-joint  is  frequently  greater  than  the  known 
pressure  of  the  atmosphere : indeed,  it  often  exceeds  the  strength  of  the  solid  wood,  as  the  fracture 
does  not  at  all  times  occur  through  the  joint,  and  when  it  does,  it  almost  invariably  tears  out  some  of 
the  fibres  of  the  wood ; mahogany  and  deal  are  considered  to  hold  the  glue  better  than  any  other 
woods. 

It  is  a great  mistake  to  depend  upon  the  quantity  or  thickness  of  the  glue,  as  that  joint  holds  the 
best  in  which  the  neighboring  pieces  of  wood  are  brought  the  most  closely  into  contact ; they,  should 
first  be  well  wetted  with  the  glue,  and  then  pressed  together  in  various  ways  to  exclude  as  much  of  it 
as  possible,  as  will  be  explained. 

The  works  in  turnery  do  not  in  general  require  much  recourse  to  glue,  as  the  parts  are  more  usually 
connected  by  screws  cut  upon  the  edges  of  the  materials  themselves ; but  when  glue  is  used  by  the 
turner,  the  mode  of  proceeding  is  so  completely  similar  to  that  practised  in  joinery-works,  that  no 
separate  instructions  appear  to  be  called  for,  especially  as  those  parts  in  which  glue  is  required,  as  for 
example  in  Tunbridge  ware,  partake  somewhat  of  the  nature  of  joinery-work. 

When  glue  is  applied  to  the  end  grain  of  the  wood,  it  is  rapidly  absorbed  in  the  pores  ; it  is  therefore 
usual  first  to  glue  the  end  wood  rather  plentifully,  and  to  allow  it  to  soak  in  to  fill  the  grain,  and  then 
to  repeat  the  process  until  the  usual  quantity  will  remain  upon  the  face  of  the  work  ; but  it  never 
holds  so  well  upon  the  endway  as  the  lengthway  of  the  fibres. 

In  glueing  the  edges  of  two  boards  together  they  are  first  planed  very  straight,  true,  and  square  ; 
they  are  then  carefully  examined  as  to  accuracy,  and  marked,  to  show  which  way  they  are  intended 
to  be  placed.  The  one  piece  is  fixed  upright  in  the  chaps  of  the  bench,  the  other  is  laid  obliquely 
against  it,  and  the  glue-brush  is  then  run  along  the  angle  formed  between  their  edges,  which  are  then 
placed  in  contact,  and  rubbed  hard  together  lengthways,  to  force  out  as  much  of  the  glue  as  possible. 
When  the  joint  begins  to  feel  stiff  under  the  hand,  the  two  parts  are  brought  into  their  intended 


932 


WOODS,  VARIETIES  OE. 


position  and  left  to  dry ; or  as  the  bench  cannot  in  general  be  spared  so  long,  the  work  is  cautiously 
removed  from  it,  and  rested  in  contact  with  a slip  of  wood  placed  against  the  wall,  at  a small  incli- 
nation from  the  perpendicular.  Two  men  are  required  in  glueing  the  joints  of  long  boards. 

In  glueing  a thin  slip  of  wood  on  the  edge  of  a board,  as  for  a moulding,  it  is  rubbed  down  very 
close  and  firm,  and  if  it  show  any  disposition  to  spring  up  at  the  ends,  it  is  retained  by  placing  thereoa 
heavy  weights,  which  should  remain  until  the  work  is  cold ; but  it  is  a better  plan  to  glue  on  a wide 
piece,  and  then  to  saw  off  the  part  exceeding  that  which  is  required. 

Many  works  require  screw-clamps  and  other  contrivances,  to  retain  the  respective  parts  in  contact 
whilst  the  glue  is  drying ; in  others,  the  fittings  by  which  the  pieces  are  attached  together  supply  the 
needful  pressure.  For  instance,  in  glueing  the  dovetails  of  a box,  or  a drawer,  such  as  Fig.  3944,  dove- 
tails, if  properly  fitted,  hold  the  sides  together  in  the  requisite  manner,  and  the  following  is  the  order 
of  proceeding. 

The  dovetail  pins,  on  the  end  B,  Fig.  3944,  are  first  sparingly  glued,  that  piece  is  then  fixed  in  the 
chaps  of  the  bench,  glue  upwards,  and  the  side  A,  held  horizontally,  is  driven  down  upon  B by  blows 
of  a hammer,  which  are  given  upon  a waste  piece  of  wood,  smooth  upon  its  lower  face,  and  placed 
over  the  dovetail  pins,  which  should  a little  exceed  the  thickness  of  the  wood,  so  that  when  their 
superfluous  length  is  finally  planed  off,  they  may  make  a good  clean  joint.  When  the  pins  of  the 
dovetails  come  flush  with  the  face,  the  driving-block  is  placed  beside  them  to  allow  the  pins  to  rise 
above  the  surface.  The  second  end,  D,  is  then  glued  the  same  as  B,  it  is  also  fixed  in  the  bench,  and 
A is  driven  down  upon  it  as  before  ; this  unites  the  three  sides  of  the  square.  The  other  pins  on  the 
ends  B and  D are  then  glued,  and  the  first  side,  A,  is  placed  downwards  on  the  bench,  upon  two  slips 
of  wood  placed  close  under  the  dovetails,  that  it  may  stand  solid,  and  the  remaining  side,  D,  is  driven 
down  upon  them  to  complete  the  connection  of  the  four  sides. 

The  box  is  then  measured  with  a square,  to  ascertain  if  it  have  accidentally  become  rhomboidal,  or 
out  of  square,  which  should  be  immediately  corrected  by  pressure  in  the  direction  of  the  longer 
diagonal ; lastly,  the  superfluous  glue  is  scraped  off  whilst  it  is  still  soft  with  a chisel,  and  a sponge 
dipped  in  the  hot  water  of  the  glue-kettle  is  occasionally  used,  to  remove  the  last  portion  of  glue  from 
the  work. 

The  general  method  pursued  in  glueing  the  angles  of  the  frame  for  a panel  is  somewhat  similar, 
although  modified,  to  meet  the  different  structure  of  the  joints.  The  tenons  are  made  quite  parallel 
both  ways,  but  the  mortises  are  a little  bevelled  or  made  longer  outside,  to  admit  the  small  wedges  by 
which  the  tenons  are  fastened  ; and  the  stiles  are  made  somewhat  longer  than  when  finished,  to  pre- 
vent the  mortises  from  being  broken  out  in  driving  the  wedges,  which  are  mostly  cut  out  of  the  waste 
pieces  sawn  off  from  the  tenons  in  forming  their  shoulders  or  haunches.  These  details  are  seen  in  Fig.  3946. 

In  glueing  the  frame  for  a single  panel  which  is  fitted  into  a groove,  the  whole  of  the  frame  is  put 
together  before  commencing  the  glueing,  and  the  stiles  are  knocked  off  one  at  a time,  by  which  the 
misplacement  of  the  pieces  is  avoided.  The  tenons  are  glued,  and  a little  glue  is  thrust  into  the  two 
mortises  with  a thin  piece  of  wood;  when  the  stiles  have  been  driven  down  close,  the  joint  is  com- 
pleted by  the  insertion  of  a wedge  on  each  side  of  the  tenon ; their  points  are  dipped  in  the  glue,  and 
they  are  driven  in  like  nails,  so  as  to  fill  out  the  mortises,  after  which  the  tenons  cannot  be  with- 
drawn : sometimes  the  wedges  are  driven  into  saw-kerfs,  previously  made  near  the  sides  of  the  tenons ; 
the  other  stile  is  then  knocked  off,  glued,  and  fixed  in  the  same  manner.  Occasionally  all  four  tenons 
are  glued  at  the  same  time,  and  the  two  stiles  are  pressed  together  by  screw-clamps,  stretching  across 
the  frame  just  within  the  tenons;  the  wedges  are  lastly  driven  in,  before  the  removal  of  the  damps, 
and  the  door,  if  square  and  true,  is  left  to  dry. 

In  many  other  cases  also,  the  respective  pieces  are  pressed  together  by  screws  variously  contrived  ; 
the  boards  employed  to  save  the  work  from  being  disfigured  by  the  screws  are  planed  flat,  and  are 
warmed  before  the  fire,  to  supply  heat  to  keep  the  glue  fluid  until  the  work  is  screwed  up,  and  the 
warmth  afterwards  assists  in  drying  the  glue : such  heated  boards  are  named  cauls,  and  they  are  par- 
ticularly needed  in  laying  down  large  veneers,  which  process  is  thus  accomplished. 

The  surfaces  of  the  table  or  panel,  and  both  sides  of  the  veneer,  are  scratched  over  with  a tool  callec 
a toothing-plane,  which  has  a perpendicular  iron  full  of  small  grooves,  so  that  it  always  retains  a notchec 
or  serrated  edge ; this  makes  the  roughness  on  the  respective  pieces,  called  the  tooth  or  key,  for  the  hold 
of  the  glue.  A caul  of  the  size  of  the  table  is  made  ready ; and  several  pairs  of  clamps,  each  consisting 
of  two  strong  wooden  bars,  placed  edgeways,  and  planed  a little  convex  or  rounding  on  their  inner 
edges,  and  connected  at  their  extremities  with  iron  screw-bolts  and  nuts,  are  adjusted  to  the  proper 
opening ; the  table  is  warmed  on  its  face,  and  the  veneer  and  caul  are  both  made  very  hot* 

All  being  ready,  the  table  is  brushed  over  quickly  with  thin  glue  or  size,  the  veneer  is  glued  and  laid 
on  the  table,  then  the  hot  caul,  and  lastly  the  clamping-bars,  which  are  screwed  down  as  quickly  as 
possible,  at  distances  of  three  or  four  inches  asunder,  until  they  lie  exactly  flat.  The  slender  veneer  is 
thereby  made  to  touch  the  table  at  every  point,  and  almost  the  -whole  of  the  glue  is  squeezed  out,  as 
the  heat  of  the  caul  is  readily  communicated  through  the  thin  veneer  to  the  glue  and  retains  it  in  a 
state  of  fluidity  for  the  short  space  of  time  required  for  screwing  down,  when  several  active  men  are 
engaged  in  the  process.  The  table  is  kept  under  restraint  until  entirely  cold,  generally  for  the  whole 
night  at  least,  and  the  drying  is  not  considered  complete  under  two  or  three  days.f 


* If  the  clamps  were  straight,  their  pressure  would  be  only  exerted  at  the  sides  of  the  table ; but  being  curved  to  the 
extent  of  one  inch  in  three  or  four  feet,  their  pressure  is  first  exerted  in  the  centre,  and  gradually  extends  over  their  entire 
length,  when  they  are  so  far  strained  as  to  make  the  rounded  edge  bear  flat  upon  the  table  and  caul  respectively. 

+ In  some  of  the  large  manufactories  for  cabinet-work,  the  premises  are  heated  by  steam-pipes,  in  which  case  the}  have 
frequently  a close  stove  in  every  workshop,  heated  many  degrees  beyond  the  general  temperature,  for  giving  the  final 
seasoning  to  the  wood,  for  heating  the  cauls,  and  for  warming  the  glue,  which  is  then  done  by  opening  a small  steam-pips 
Into  the  outer  vessel  of  the  glue-pot.  The  arrangement  is  extremely  clean,  safe  from  fire,  and  the  degree  of  the  heat  is 
very  much  under  control. 


WOODS,  VARIETIES  OF. 


When  the  objects  to  be  glued  are  curved,  the  cauls,  or  moulds,  must  be  made  of  the  counterpart 
cm  ve,  so  as  to  fit  them  ; for  example,  in  glueing  the  sounding-board  upon  the  body  of  a harp,  which 
may  be  compared  to  the  half  of  a cone,  a trough  or  caul  is  used  of  a corresponding  curvature,  and  fur- 
nished all  along  the  edge  with  a series  of  screws  to  bring  the  work  into  the  closest  possible  contact. 

In  glueing  the  veneers  of  maple,  oak,  and  other  woods  upon  curved  mouldings,  such  as  those  for  pic- 
ture-frames, the  cauls  or  counterpart  moulds  are  made  to  fit  the  work  exactly.  The  moulding  is  usu- 
ally made  in  long  pieces  and  polished,  previously  to  being  mitred  or  joined  together  to  the  sizes  re- 
quired. 

In  works  that  are  curved  in  their  length,  as  the  circular  fronts  of  drawers,  and  many  of  the  foundry 
patterns  that  are  worked  to  a long  sweep,  the  pieces  that  receive  the  pressure  of  the  screws  used  in 
fixing  the  work  together  “ whilst  it  is  under  glue,”  are  made  in  narrow  slips,  and  pierced  with  a small 
hole  at  each  end;  they  are  then  strung  together  like  a necklace,  but  with  two  strings.  This  flexible 
caul  can  be  used  for  all  curves  ; the  strings  prevent  the  derangement  of  the  pieces  whilst  they  are  being 
fixed,  or  their  loss  when  they  are  not  in  use. 

We  have  mentioned  these  cases  to  explain  the  general  methods,  and  to  urge  the  necessity  of  thin  glue, 
of  a proper  degree  of  warmth  to  prevent  it  from  being  chilled,  and  of  a pressure  that  may  cause  the 
greatest  possible  exclusion  of  glue  from  the  joint.  But  for  the  comparatively  small  purposes  of  the 
amatuer,  four  or  six  hand-screws,  or  ordinary  clamps,  or  the  screw-chaps  of  the  bench,  aided  by  a string 
to  bind  around  many  of  the  curvilinear  and  other  works,  will  generally  suffice. 

As,  however,  the  amateur  may  occasionally  require  to  glue  down  a piece  of  veneer,  we  will,  in  con- 
clusion, describe  the  method  of  “ laying  it  with  the  hammer,”  which  requires  none  of  the  apparatus  just 
described,  but  the  veneering  hammer  alone.  This  is  either  made  of  iron  with  a very  wide  and  thin  plane, 
or  more  generally  of  a piece  of  wood  from  three  to  four  inches  square,  with  a round  handle  projecting 
from  the  centre ; the  ODe  edge  of  the  hammer-head  is  Sawn  down  for  the  insertion  of  a piece  of  sheet- 
iron  or  steel,  that  projects  about  one-quarter  of  an  inch,  the  edge  of  which  is  made  very  straight,  smooth, 
and  round ; and  the  opposite  side  of  the  square  wooden  head  of  the  veneering  hammer  is  rounded,  to 
avoid  its  hurting  the  hand. 

The  table  and  both  sides  of  the  veneer  having  been  toothed,  the  surface  of  the  table  is  warmed,  and 
the  outer  face  of  the  veneer  and  the  surface  of  the  table  are  wetted  with  very  thin  glue  or  with  a stiff 
size.  The  inner  face  of  the  veneer  is  next  glued ; it  is  held  for  a few  moments  before  a blazing  fire  of 
shavings  to  render  the  glue  very  fluid,  it  is  turned  quickly  down  upon  the  table,  and  if  large  is  rubbed 
down  by  the  outstretched  hands  of  several  men  ; the  principal  part  of  the  remainder  of  the  glue  is  then 
forced  out  by  the  veneering  hammer,  the  edge  of  which  is  placed  in  the  centre  of  the  table ; the  work- 
man leans  with  his  whole  weight  upon  the  hammer,  by  means  of  one  hand,  and  with  the  other  he  wrig- 
gles the  tool  by  its  handle,  and  draws  it  towards  the  edge  of  the  table,  continuing  to  bear  heavily  upon 
it  all  the  time. 

The  pressure  being  applied  upon  so  narrow  an  edge,  and  which  is  gradually  traversed  or  scraped 
over  the  entire  surface,  squeezes  out  the  glue  before  it,  as  in  a wave,  and  forces  it  out  at  the  edge ; hav- 
ing proceeded  along  one  line,  the  workman  returns  to  the  centre,  and  wriggles  the  tool  along  another 
part  close  by  the  side  of  the  former ; and  in  fact  as  many  men  are  generally  engaged  upon  the  surface 
of  the  table  as  the  shop  will  supply,  or  that  can  cluster  around  it.  The  veneer  is  from  time  to  time 
wetted  with  the  hot  size,  which  keeps  up  the  warmth  of  the  glue,  and  relieves  the  friction  of  the  ham- 
mers, which  might  otherwise  tear  the  face  of  the  wood. 

The  wet  and  warmth  also  render  the  veneer  more  pliable,  and  prevent  it  from  cracking  and  curling 
up  at  the  edges,  as  should  the  glue  become  chilled  the  veneer  would  break  from  the, sudden  bending  to 
which  it  might  be  subjected,  by  the  pressure  of  the  hammer  just  behind  the  wave  of  glue,  which  latter 
would  be  then  too  stiff  to  work  out  freely,  owing  to  its  gradual  loss  of  fluidity  ; the  operation  must, 
therefore,  be  conducted  with  all  possible  expedition. 

The  concluding  process  is  to  tap  the  surface  all  over  with  the  back  of  the  hammer,  and  the  dull  hol- 
low sound  will  immediately  indicate  where  the  contact  is  incomplete,  and  here  the  application  of  the 
hammer  must  be  repeated ; sometimes  when  the  glue  is  too  far  set  in  these  spots,  the  inner  vessel  of 
the  glue-pot  or  heated  irons  are  laid  on  to  restore  the  warmth.  By  some,  the  table  is  at  the  conclusion 
laid  flat  on  the  floor,  veneer  downwards,  and  covered  over  with  shavings,  to  prevent  the  too  sudden  ac- 
cess of  air.  Of  course,  the  difficulty  of  the  process  increases  with  the  magnitude  of  the  work  ; the  mode 
is  more  laborious  and  less  certain  than  that  previously  described,  although  it  is  constantly  resorted  to 
for  the  smaller  pieces  and  strips  of  veneer. 

CHARACTERS  AND  USES  OF  THE  WOODS  COMMONLY  EMPLOYED  IN  MECHANICAL  AND 

ORNAMENTAL  ARTS. 

Abele.  See  Poplar. 

Acacia,  true.  The  Acacia  proximo,  Mordi,  A.  Guillard’s  MSS.,  called  in  Cuba  Sabicii,  and  in  England 
Savico  and  Savacu,  is  a heavy,  durable  wood  of  the  red-mahogany  character,  but  rather  darker  and 
plainer ; it  is  highly  esteemed  in  ship-building. 

The  true  acacias  are  found  in  warm  parts  of  the  world,  and  yield  valuable  though  usually  small 
timber,  which  is  remarkable  for  being  hard  and  tough,  as  Acacia  tortuosa,  called  Cashaw-tree 
in  the  West  Indies.  On  the  west  coast  of  Africa,  Acacia  verek  has  very  hard  white  wood,  as 
well  as  other  species.  A.  mclanoxylon,  black  wattle-tree  and  blackwood,  and  A.  decurrens, 
green  wattle,  occur  in  Hew  Holland. 

In  India,  Acacia  arabica  and  farnesiana,  commonly  called  bubool,  A.  speciosa,  and  A.  sundra, 
yield  timber  valued  for  different  purposes.  Many  of  these  trees  exude  gum,  and  their  bark  ij 
employed  in  tanning  leather. 

Acacia,  Arise,  the  common  acacia  or  locust-tree.  See  Locust-tree. 

African  Black- wood.  See  Black  Botany-Bay  Wood. 


034 


WOODS,  VARIETIES  OF. 


Alder,  ( Alnus  glutinosa,)  Europe  and  Asia.  There  are  other  species  in  North  America  and  the  Hima- 
layas. The  common  alder  seldom  exceeds  40  feet  in  height,  is  very  durable  under  water,  and  wa» 
used  for  the  piles  of  the  Rialto  at  Venice,  the  buildings  at  Ravenna,  Ac. : the  wood  is  also  much 
used  for  pipes,  pumps,  and  sluices.  The  color  of  alder  is  reddish-yellow  of  different  shades,  and 
nearly  uniform ; the  wood  is  soft,  and  the  smaller  trees  are  much  used  for  inferior  turnery,  as  tooth- 
powder  boxes,  common  toys,  brushes  and  bobbins,  and  occasionally  for  foundry  patterns.  The  roots 
and  knots  are  sometimes  beautifully  veined,  and  used  in  cabinet-work.  The  charcoal  of  the  alder 
is  employed  in  the  manufacture  of  gunpowder. 

Aloes-wood.  See  Calembeg. 

Almond-tree,  ( Amygdalus  communis ,)  is  very  strongly  recommended  by  Desormeaux,  as  being  hard, 
heavy,  oily  or  resinous,  and  somewhat  pliable ; he  says,  the  wood  towards  the  root  so  much  resem- 
bles lignum-vitce  as  to  render  it  difficult  to  distinguish  between  them.  It  is  sometimes  called  false 
lignum-vitcc,  and  is  used  for  similar  purposes,  as  handles,  the  teeth  and  bearings  of  wheels,  pulleys, 
Ac.,  and  any  work  exposed  to  blows  or  rough  usage.  It  is  met  with  in  the  south  of  Europe,  Syria, 
Barbary,  Ac.  The  wood  of  the  bitter  almond,  grown  in  exposed  rocky  situations,  is  preferred. 

Amboyna-wood.  See  Kiabooca-wood. 

Angica-wood.  See  Cangica-wood. 

Aps.  See  Poplar. 

Apple-tree,  ( Pyrus  Malus.)  The  woods  of  the  apple-trees,  especially  of  the  uncultivated,  are  in  gen- 
eral pretty  hard  and  close,  and  of  red-brown  tints,  mostly  lighter  than  the  hazelnut.  The  butt  of 
the  tree  only  is  used  ; it  is  generally  very  straight  and  free  from  knots  up  to  the  crown,  whence 
the  branches  spring.  The  apple-tree  splits  very  well,  and  is  one  of  the  best  woods  for  standing 
when  it  is  properly  seasoned ; it  is  very  much  used  in  Tunbridge  turnery,  for  bottle-cases,  Ac. : it 
is  a clean-working  wood,  and  being  harder  than  chestnut,  sycamore,  or  lime-tree,  is  better  adapted 
than  they  are  for  screwed  work,  but  is  inferior  in  that  respect  to  pear-tree,  which  is  tougher.  The 
millwright  uses  the  crab-tree  for  the  teeth  of  mortise-wheels. 

Apri,cot-tree,  {Armeniaca  vulgaris ,)  a native  of  Armenia,  is  mentioned  in  all  of  the  French  works  on 
turning,  beginning  with  Bergeron,  (1192,)  who  says  the  wood  of  the  apricot-tree  is  very  rarely  met 
with  sound,  but  that  it  is  agreeably  veined,  and  better  suited  to  turning  than  carpentry.  He  else- 
where very  justly  adds,  that  we  are  naturally  prejudiced  in  favor  of  those  trees  from  which  we 
derive  agreeable  fruits,  and  expect  the  respective  woods  to  be  either  handsome  in  appearance  or 
agreeable  in  scent,  but  in  each  of  which  expectations  we  are  commonly  disappointed : this  applies 
generally  to  the  orange  and  lemon  trees,  and  we  may  add,  to  the  quince,  pomegranate,  and  coffee 
trees,  the  vine,  and  many  others  occasionally  met  with,  rather  as  objects  of  curiosity  than  as  ma- 
terials applicable  to  the  arts. 

Arbor  vitye.  The  different  species  of  Thuja  are  called  Arbor  vita:,  and  are  chiefly  found  in  North 
America  and  China.  T.  occidentals,  or  American  Arbor  vit<e,  attains  a height  of  from  40  to  50 
feet,  and  has  reddish-colored,  somewhat  odorous,  very  light,  soft  and  fine-grained  wood.  It  is 
softer  than  white  pine,  and  much  used  in  house-carpentry,  and  also  for  fences. 

The  Chinese  Arbor  vitce,  or  T.  orienlalis,  is  smaller,  but  the  wood  is  harder.  T.  articulata,  a 
native  of  the  north  coast  of  Africa,  is  the  Alerce  of  the  Moors,  and  was  employed  in  the  wood- 
work of  the  mosque,  now  the  cathedral,  of  Cordova.  The  plant  is  now  called  Callitris 
quadrivalvis. 

Asii,  ( Fraxinus  cxcelsa  ;)  Europe  and  north  of  Asia;  mean  size,  38  feet  long  by  23  inches  diameter, 
sometimes  much  larger.  The  young  wood  is  brownish-white  with  a shade  of  green ; the  old  oak- 
brown,  with  darker  veins.  Some  specimens  from  Hungary  with  a zigzag  grain,  and  some  of  the 
pollards,  are  very  handsome  for  furniture. 

Ash  is  superior  to  almost  any  other  timber  for  its  toughness  and  elasticity ; it  is  excellent  for 
works  exposed  to  sudden  shocks  and  strains,  as  the  frames  of  machines,  wheel-carriages,  agricul- 
tural implements,  the  felloes  of  wheels,  and  the  inside  work  of  furniture,  Ac.  The  wood  is  split 
into  pieces  for  the  springs  of  bleachers’  rubbing-boards,  which  are  sometimes  40  feet  long;  also 
for  handspikes,  billiard  cues,  hammer  handles,  rails  for  chairs,  and  numerous  similar  works,  which 
are  much  stronger  when  they  follow  the  natural  fibre  of  the  wood. 

Ash  is  too  flexible  and  insufficiently  durable  for  building  purposes ; the  young  branches  serve 
for  hoops  for  ships’  masts,  tubs,  churns,  Ac. 

Several  species  are  found  in  North  America : of  these  it  is  thought  that  the  white-ash,  or  Frax- 
inus amcricana,  comes  the  nearest  in  quality  of  wood  to  the  common  ash.  F.  fioribunda  and 
zanthoxyloides  are  two  ashes  found  in  the  Himalayas. 

Fraxinus  ornus  produces  manna ; Fraxinus  excelsa  produces  a manna  somewhat  similar. 

Ash,  the  Mountain  Ash,  or  Quicken  or  Rowan  tree,  Pyrus  Aucuparia,  grows  in  almost  every 
soil  or  situation,  has  fine-grained  hard  wood,  which  may  be  stained  of  any  color,  and  takes  a 
high  polish,  and  is  applied  to  the  same  purposes  as  the  wood  of  the  Beam  and  Service  trees. 
See  Service-tree. 

Aspen.  See  Poplar. 

Barberry- wood,  ( Berberis  vulgaris,)  is  of  small  size,  generally  about  4 inches  diameter ; the  rind  is 
yellow,  and  about  half  an  inch  thick : the  wood  resembles  elder,  and  is  tolerably  straight  and 
tenacious. 

Barwood,  Africa.  Two  kinds  are  imported  from  Angola  and  Gaboon  respectively,  in  split  pieces  4 to 
5 feet  long,  10  to  12  inches  wide,  and  2 to  3 inches  thick.  It  is  used  as  a red  dyewood — the  wood 
is  dark-red,  but  the  dye  rather  pale  ; it  is  also  used  for  violin-bows,  ramrods,  and  turning. 

Bay-tree.  The  sweet  bay-tree,  ( Laurus  nobilis,)  a native  of  Italy  and  Greece,  grows  to  the  height  ot 
30  feet,  and  is  an  aromatic  wood.  It  is  the  laurel  that  was  used  by  the  ancients  for  their  military 
crowns. 


WOODS,  VARIETIES  OF. 


Beech.  Only  one  species  ( Fagus  sylvatica ) is  common  to  Europe ; in  England  the  Buckinghamshire 
and  Sussex  beech  are  esteemed  the  best.  Mean  dimensions  of  the  tree,  44  feet  long  and  27  inches 
diameter.  The  color  (whitish-brown)  is  influenced  by  the  soil,  and  is  described  as  white,  brown 
and  black. — ( Tredgold .) 

Beech  is  used  for  piles  in  wet  foundations,  but  not  for  building;  it  is  excellent  from  its  uniform 
texture  and  closeness  for  in-door  works,  as  the  frames  of  machines,  common  bedsteads  and  furniture  , 
it  'is  very  much  used  for  planes,  tools,  lathe-chucks,  the  keys  and  cogs  of  machinery,  shoe-lasts, 
pattens,  toys,  brushes,  handles,  &c.  Carved  moulds  for  the  composition  ornaments  of  picture-frames, 
and  for  pastry,  and  large  wooden  types  for  printing,  are  commonly  made  of  beech : the  wood  is 
often  attacked  by  worms  when  stationary,  as  in  framings,  but  tools  kept  in  use  are  not  thus 
injured. 

Beech  is  stained  to  imitate  rosewood  and  ebony,  and  it  is  considered  to  be  almost  chemically 
free  from  foreign  matters ; for  example,  the  glass-blowers  use  the  wood  almost  exclusively  in  weld- 
ing, or  fusing  on,  the  handles  of  glass  jugs,  which  process  fails  when  the  smallest  portion  of  sulphur, 
<fcc.,  is  present : oak  is  next  in  estimation  for  the  purpose. 

The  white-beech  of  North  America,  Fagus  sglvestris,  is  little  valued  in  this  country ; the  bark, 
however,  is  employed  in  tanning. 

Beefwood.  Red-colored  woods  are  sometimes  thus  named,  but  it  is  generally  applied  to  the  Botany- 
bay  oak — which  see. 

Betle-nuts,  or  Areca-nuts,  are  the  fruit  of  the  Areca  catedru,  or  Faufel ; they  have  a thin,  brown 
rind,  and  in  size  are  intermediate  between  walnuts  and  hazelnuts  ; their  general  substance  is  of  a 
faint  oily-gray  color,  thickly  marked  with  curly  streaks  of  dark-brown  or  black.  The  betle-nuts, 
although  softer,  resemble  ivory,  as  regards  the  art  of  turning ; they  are  made  into  necklaces,  the 
tops  of  walking-sticks,  and  other  small  objects.  The  substance  of  the  betle-nut,,  together  with 
quicklime,  is  chewed  by  the  generality  of  the  natives  of  India. 

Fig.  3947  is  the  section  of  the  betle-nut  full  size,  and  at  right  angles  to  the  stalk.  Fig.  3948  is 
the  section  through  the  line  of  the  stalk,  which  shows  the  central  cavity.  Externally  the  marks 
constitute  a tortuous  running  pattern,  as  seen  in  the  turned  knob,  Fig.  3949. 

3948.  3949. 


Birch  wood.  A forest-tree  common  to  Europe  and  North  America ; the  finest  is  from  Canada,  St. 
John’s,  and  Pictou.  It  is  an  excellent  wood  for  the  turner,  being  light-colored,  compact,  and  easily 
worked : it  is  in  general  softer  and  darker  than  beech,  and  unlike  it  in  grain. 

Birchwood  is  not  very  durable ; it  is  considerably  used  in  furniture.  Some  of  the  wood  is  almost 
as  handsomely  figured  as  Honduras  mahogany,  and  when  colored  and  varnished  is  not  easily  dis- 
tinguished from  it.  The  bark  of  the  birch-tree  is  remarkable  for  being  harder  and  more  durable 
than  the  wood  itself : amongst  the  Northern  nations  it  is  used  for  tiles  for  roofs,  for  shoes,  hats,  ifcc., 
and  in  Canada  for  boats.  The  Russians  employ  the  tan  of  one  of  the  birch-trees  to  impart  the 
scent  to  Russia  leather,  which  is  thereby  rendered  remarkably  durable.  The  inner  bark  is  used 
for  making  the  Russia  mats. 

The  English  birch  is  much  smaller  than  the  American,  and  lighter  in  color  ; it  is  chiefly  used  for 
common  turnery.  Some  of  the  Russian  birch  (called  Russian  maple)  is  very  beautiful,  and  of  a 
full  yellow  color. 

Betula  alba  is  the  common  birch  of  Europe,  and  the  most  common  tree  throughout  the  Russian 
Empire.  The  Russian  maple  of  commerce  is  thought  to  be  the  wood  of  the  birch.  Betula 
lenta,  mahogany  birch  and  mountain  mahogany  of  America,  has  close-grained,  reddish-brown 
timber,  which  is  variegated,  and  well  adapted  to  cabinet-work.  It  is  exported  in  considerable 
quantities  to  England  under  the  name  of  American  birch. 

Betula  excelsa,  tall,  also  called  yellow-birch,  has  wood  much  like  the  last,  and  B.  nigra,  or  black, 
is  also  much  esteemed.  B.papyracea,  paper  or  canoe  birch,  is  employed  by  the  North  Amer- 
ican Indians  in  constructing  their  portable  canoes.  B.  Bhojputtra  is  a Himalayan  species,  of 
which  the  bark  is  used  for  writing  upon,  and  for  making  the  snakes  of  hookahs. 

Bitter-nut  wood,  a native  of  America,  is  a large  timber  wood  measuring  30  inches  when  squared,  plain 
and  soft  in  the  grain,  something  like  walnut. 

Juglans  amara,  white  or  swamp  hickory  or  bitter-nut,  and  J.  aquatica,  or  water  bitter-nut 
hickory,  are  probably  the  trees  which  yield  this  wood. 

Brack  Botany-Bay  wood,  called  also  African  Blackwood,  is  perhaps  the  hardest  and  also  the  most 
wasteful  of  all  the  woods  ; the  billets  are  veiy  knotty  and  crooked,  and  covered  with  a thick  rind 
of  the  color  and  hardness  of  boxwood;  the  section  of  the  heart-wood  is  very  irregular,  and  mostly 
either  indented  from  without,  or  hollow  and  unsound  from  within ; many  of  the  pieces  have  the 
irregular  scrawling  growth  that  is  observed  in  the  wood  of  the  vine.  The  largest  stem  of  Black 
Botany-Bay  wood  we  have  ever  seen,  measured  transversely  11  inches  the  longest  and  7J  the  short- 
est way,  but  it  would  only  produce  a circular  block  of  5 inches,  and  this  is  fully  two  or  three  times 
the  ordinary  size 


3947. 


D36 


WOODS,  VARIETIES  OF. 


The  wood,  when  fresh  cut,  is  of  a bluish-black,  with  dark-gray  streaks,  but  soon  changes  to  an 
intense  jet  black ; of  the  few  sound  pieces  that  are  obtained,  the  largest  may  perhaps  be  five 
inches,  but  the  majority  less  than  two  inches  in  diameter.  It  is  most  admirably  suited  to  eccentric 
turning,  as  the  wood  is  particularly  hard,  close,  free  from  pores,  but  not  destructive  to  the  tools, 
from  which,  when  they  are  in  proper  condition,  it  receives  a brilliant  polish.  It  is  also  considered 
to  be  particularly  free  from  any  matter  that  will  cause  rust,  on  which  account  it  is  greatly  esteemed 
for  the  handles  of  surgeons’  instruments. 

The  exact  locality  of  this  wood  has  long  been  a matter  of  great  uncertainty.  It  has  been  con- 
sidered to  be  a species  of  African  ebony,  but  its  character  is  quite  different  and  peculiar ; we  have 
however  recently  heard,  from  two  independent  sources,  that  it  comes  from  the  Mauritius,  or  Isle  oi 
France.  Col.  Lloyd  says  the  wood  is  there  called  Cocobolo  prieto  ; that  it  is  not  the  growth  of  the 
Mauritius,  but  of  Madagascar,  to  the  interior  of  which  island  Europeans  are  not  admitted  ; and  that 
it  is  brought  in  the  same  vessels  that  bring  over  the  bullocks,  for  the  supply  of  food.  The  stone- 
masons of  the  country  use  splinters  of  it  as  a pencil  for  marking  the  lines  upon  their  work ; it 
makes  a dark-blue  streak  not  readily  washed  off  by  rain. 

We  have  only  met  with  one  specimen  of  this  wood  in  the  numerous  collections  we  have  searched, 
namely,  in  Mr.  Fincham’s:  he  assures  us  that  his  specimen  grew  in  Botany  Bay,  and  was  brought 
direct  from  thence,  with  several  others,  by  Captain  Woodroff'e,  It.  N.  As  we  have  recently  purchased 
a large  quantity  imported  from  the  Mauritius,  it  is  probable  that  this  wood,  in  common  with  many 
others,  may  have  several  localities. 

It  would  be  very  desirable  for  the  amateur  turner  that  the  wood  should  be  selected  on  the  spot, 
and  the  better  pieces  alone  sent,  as  a large  proportion  is  scarcely  worth  the  expense  of  shipment, 
but  the  tine  pieces  exceed  all  other  woods  for  eccentric-turned  works. 

Blue  Gumwood.  See  Gumwood. 

Botany-Bay  Oak,  sometimes  called  Beefwood,  is  from  Mew  South  Wales ; it  is  shipped  in  round  logs, 
from  9 to  14  in.  diam.  In  general  color  it  resembles  a full  red  mahogany,  with  darker  red  veins ; 
the  grain  is  more  like  the  evergreen  oak  than  the  other  European  varieties,  as  the  veins  are  small, 
slightly  curled,  and  closely  distributed  throughout  the  whole  surface.  It  is  used  in  veneer  for  the 
backs  of  brushes,  Tunbridge  ware,  and  turnery ; some  specimens  are  very  pretty. 

The  trees  called  oaks  in  New  South  Wales  do  not  belong  to  the  genus  Quercus,  like  the  European, 
North  American,  and  Himalayan  oaks.  There,  the  tree  called  Forest  Oak,  is  Casuarina  toru- 
losa  ; Swamp  Oak  is  C.  paludosa  ; He-Oak  is  C.  equisiti folia  ; while  C.  stricta  is  called  She- 
Oak,  and  also  Beefwood. 

Boxwood  ( Buxus  sempervirens ) is  distinguished  as  Turkey  and  European  boxwood.  The  former  is 
imported  from  Constantinople,  Smyrna,  and  the  Black  Sea,  in  logs  felled  with  the  hatchet,  that 
measure  from  2 to  6 ft.  long,  and  2-J-  to  14  in.  diam.  The  wood  is  yellow,  inclining  to  orange ; it  has 
a thin  rind  with  numerous  small  knots  and  wens  ; some  of  it  is  much  twisted,  and  such  pieces  do 
not  stand  well  when  worked;  on  the  whole,  however,  it  is  an  excellent,  sound,  and  useful 
wood. 

Boxwood  is  much  used  for  clarionets,  flutes,  and  a great  variety  of  turned  works ; it  makes 
excellent  lathe-chucks,  and  is  selected  by  the  wood-engraver  to  the  exclusion  of  all  other  woods. 
It  is  also  used  for  carpenters’  rules  and  drawing-scales ; although  lancewood,  satin-wood,  and  elder, 
are  sometimes  substituted  for  it.  Boxwood  is  particularly  free  from  gritty  matter,  and  on  that 
account  its  sawdust  is  much  used  for  cleaning  jewelry ; it  is  frequently  mentioned  by  the  iioman 
authors  as  a wood  in  great  esteem  at  the  period  in  which  they  wrote. 

Some  of  the  boxwood  is  as  handsomely  mottled  as  flue  satin-wood ; but  it  differs  much  in  color, 
apparently  according  to  the  age  and  season  at  which  it  is  cut,  as  only  a small  portion  of  the  Turkey 
boxwood  is  of  the  full  yellow  so  much  admired, 

European  boxwood  is  imported  from  Leghorn,  Portugal,  &c.  The  English  boxwood  is  plentiful 
at  Boxhill  in  Surrey,  and  in  Gloucestershire  ; it  is  more  curly  in  growth,  softer  and  paler  than  the 
Turkey  boxwood;  its  usual  diameters  are  from  1 to  5 in.;  it  is  used  for  common  turnery,  and  is 
preferred  by  brass-finishers  for  their  lathe-chucks,  as  it  is  tougher  than  the  foreign  box  and  bears 
rougher  usage.  It  is  of  very  slow  growth,  as  in  the  space  of  20  to  25  years  it  will  only  attain  a 
diameter  of  to  2 inches.  A similar  wood,  imported  from  America  under  the  name  of  Tugmutton, 
was  formerly  much  used  for  making  ladies’  fans. 

Murraya,  ( JIackay  B.  fr.  Tavoy,)  specimen  of  Dr.  Wallich’s  and  of  Captain  Baker’s  Collection 
of  Indian  woods,  and  the  Garipe  apugne  bravo , from  the  Brazils,  seem  fully  equal  to  boxwood  in 
most  respects. 

Buxus  sempervirens , or  common  evergreen  box,  is  found  throughout  Europe,  attaining  a height 
sometimes  of  from  15  to  20  feet.  Turkey  box  is  yielded  by  Buxus  balearica,  which  is  found 
in  Minorca,  Sardinia,  and  Corsica,  and  also  in  both  European  and  Asiatic  Turkey. 

A new  species  has  lately  been  introduced  from  the  Himalayas,  Buxus  emarginatus,  of  Dr. 
Wallicli:  this  is  found  of  considerable  size  and  thickness,  and  the  wood  appears  as  good  and 
compact  as  that  of  the  boxwood  in  use  in  Europe.  Royle,  Illust.  Himal.  Bot.  p.  '321.  On  actual 
comparison  the  Himalayan  boxwood  is  found  to  be  softer  than  the  common  kinds,  but  is  like 
them  in  other  respects. 

Brazil-wood,  called  also  Pernambuco,  was  supposed  by  Dr.  Bancroft  to  have  been  known  as  a red 
dyewood  before  the  discovery  of  the  Brazils,  which  country,  he  says,  was  so  named  by  Europeans 
from  its  abounding  in  this  wood.  The  best  kind  is  from  Pernambuco,  where  it  is  called  Pao  da 
rainha,  or  queen’s-wood,  and  by  the  natives  Ibirapitanga ; it  is  also  found  in  the  West  Indies 
generally,  and  is  often  called  Pernambuco-wood.  The  tree  is  large,  crooked,  and  knotty,  and  the 
bark  is  so  thick  that  the  wood  only  equals  the  third  or  fourth  of  the  entire  diameter ; the  leaves 
are  of  a beautiful  red,  and  exhale  an  agreeable  odor.  The  Pao  da  rahiha  grows  to  the  diameii-t 


WOODS,  VARIETIES  OF. 


937 


of  15  or  1G  inches,  the  Pao  Brazil,  an  inferior  kind,  to  50  or  60  in.  Brazil-wood  is  a royal  monop- 
oly, and  the  best  quality  has  the  imperial  brand  mark  at  the  end  ; it  is  shipped  in  trimmed  sticks, 
from  1 to  4 in.  diam.  and  3 to  8 ft.  long,  and  its  color  becomes  darker  by  exposure  to  the  air.  Its 
principal  use  is  for  dyeing ; the  best  pieces  are  selected  for  violin-bows  and  turning. 

Ccesalpinia  echinata,  the  Ibirapitanga  of  Piso,  yields  the  Brazil-wood  of  commerce.  De  Candolle 
inquires  whether  it  is  not  rather  a species  of  Guilandina.  C.  crista,  a native  of  the  West 
Indies,  is  called  Bresillet,  because  its  wood  is  reddish-colored  like  Brazil-wood.  C.  Sapan  is 
a native  chiefly  of  the  Asiatic  Isles  and  of  the  Malayan  Peninsula ; its  wood  is  like  Brazil- 
wood, and  well  known  in  commerce  as  Sapan-wood. 

Braziletto  is  quite  unlike  the  Brazil-wood ; its  color  is  ruddy  orange,  sometimes  with  streaks ; it  is 
imported  from  Jamaica  in  sawn  logs  from  2 to  6 ft.  long  and  2 to  8 in.  diam.,  with  the  bark  (which 
is  of  the  ordinary  thickness)  left  on  them;  and  also  from  New  Providence,  in  small  cleaned  sticks. 
Braziletto  is  thought  to  be  an  inferior  species  of  Brazil-wood  ; it  is  principally  used  for  dyeing,  also 
for  turnery  and  violin-bows. 

It  is  considered  to  be  botanically  allied  to  the  above,  and  is  called  Ccesalpinia  braziliensis,  a 
native  of  the  West  Indies,  but  also  found  in  Brazil. 

Bullet-wood,  from  the  Virgin  Isles,  West  Indies,  is  the  produce  of  a large  tree,  with  a white  sap;  the 
wood  is  greenish-hazel,  close  and  hard.  It  is  used  in  the  country  for  building  purposes,  and  resem- 
bles the  Greenheart. 

The  name  of  Bullet-wood  is  perhaps  taken  from  the  Bois  de  balle  or  Bullet-wood  of  the  French, 
Guarea  trichilioides,  which  in  Jamaica  is  called  musk  or  alligator  wood.  Bullet  is  perhaps  a 
change  from  Bully-wood,  which  is  that  of  the  bully-tree,  called  also  Naseberry  bullet-tree,  or 
Achras  Sapota  of  botanists,  described  as  one  of  the  best  timber-trees.  The  bully-tree  of 
Guiana  is  also  an  Achras.  The  bastard  bully-trees  of  Jamaica  are  species  of  Bumelia. 

Bullet-wood,  another  sjrecies  so  called,  is  supposed  to  come  from  Berbice ; its  color  is  hazel-brown,  of 
an  even  tint  without  veins ; it  is  a very  close,  hard,  and  good  wood,  well  adapted  to  general  and 
to  eccentric  turning,  but  is  not  common. 

The  latter  agrees  pretty  closely  with  a wood  described  by  Dr.  Bancroft  as  Bow-wood,  ovWasceba, 
of  Guiana. 

Different  specimens  marked  Naseberry  bullet-wood,  and  one  of  an  iron-wood,  were  exceedingly 
near  to  the  above,  if  not  identical  with  it,  and  the  Bull  Ploof  and  Bread-nut  Heart,  all  from  Jamaica, 
approached  more  distantly. 

Button-wood  Tree.  See  Plane-tree. 

Cabbage-wood.  See  Partridge-wood. 

Calamander,  Biospt/ros  hirsuta.  See  Coromandel. 

Calamberrl  See  Coromandel. 

Calembeg.  A wood  similar  to  Sandal-wood  in  grain,  and  similarly,  but  less  powerfully,  scented  ; its 
color  is  olive-green,  with  darker  shades.  It  appears  entitled  to  the  name  of  Green  Sandal-wood. 

Calembeg,  or  Calambac,  sometimes  called  Aloes-wood,  is  the  Agallochum  of  the  ancients,  and 
the  Agila  or  Eagle-wood  of  the  moderns.  It  is  produced  in  Siam  and  Silhet  by  Aquilaria 
Agallocha. 

Campeachy  Logwood.  See  Logwood. 

Camphor-wood  is  imported  from  China,  the  East  Indies,  and  Brazils,  in  logs  and  planks  of  large  size ; 
it  is  a coarse  and  soft  wood,  of  a dirty  grayish-yellow  color,  sometimes  with  broad  iron-gray  streaks, 
and  is  frequently  spongy,  and  difficult  to  work.  It  is  principally  used  in  England  for  cabinet-work 
and  turnery,  on  account  of  its  scent. 

The  Camphor-tree  of  Sumatra  is  Dryobalanops  Camphora,  of  which  the  wood  is  hard,  compact, 
and  brownish-colored ; there  is  a genuine  specimen  in  the  museum  of  King’s  College,  Loudon. 
The  fragrant  light-colored  soft  wood  of  which  the  trunks  and  boxes  from  China  are  made,  is 
supposed  to  be  that  of  the  Camphor-tree  of  Japan,  Laurus  Camphora,  now  Camphora  officinalis. 
One  or  more  of  the  tribe  of  Laurels  yield  the  Sirwabqli  wood  of  Guiana,  which  is  light,  fragrant, 
and  much  used  in  the  building  of  boats. 

Camwood,  an  African  dyewood,  is  shipped  from  Rokella,  Sierra  Leone,  <fcc.,  in  short  logs,  pieces,  roots, 
and  splinters.  When  first  opened,  it  is  tinted  with  red  and  orange ; the  dust  is  very  pungent,  like 
snuff;  it  would  be  a beautiful  wood  if  it  retained  its  original  colors,  but  it  changes  to  dark  red, 
inclining  to  brown.  Camwood  is  the  best  and  hardest  of  the  red  dyewoods ; it  is  very  fine  and 
close  in  the  grain,  and  suitable  to  ornamental  and  eccentric  turning. 

Canary-wood  from  the  Brazils,  Para,  <fec. ; known  at  the  Isthmus  of  Darien  as  Amarillo.  It  is  imported 
in  round  logs  from  9 to  14  in.  diam.,  and  sometimes  in  squared  pieces.  The  wood  is  of  a light 
orange  color,  and  generally  sound ; it  is  straight  and  close  in  the  grain,  and  very  proper  for  cabinet 
work,  marquetry,  and  turnery ; is  similar,  if  not  the  same,  to  a wood  called  Vantatico  and  Vigniatico, 
corrupted  from  Vinliatico,  a Portuguese  name  for  several  yellow  woods,  besides  that  imported  from 
the  Brazils  under  the  same  name. 

Laurus  indica,  or  Royal  Bay,  is  a native  of  the  Canary  Isles.  The  wood  is  of  a yellow  coloi 
not  heavy,  but  well  suited  to  furniture ; it  is  called  Vigniatico  in  the  island  of  Madeira. 

Caxgica-wood,  from  the  Brazils,  also  called  in  England  Angica,  is  of  the  rosewood  character,  but  of  a 
lighter  and  more  yellow  brown,  less  abrupt,  and  more  fringed,  sometimes  straight  in  grain  and 
plain  in  figure.  It  is  imported  in  trimmed  logs  from  6 to  10  in.  diam.,  and  is  used  for  cabinet-work 
and  turning. 

Cedar.  The  name  cedar  has  been  given  to  trees  of  very  different  natural  orders,  and  has  occasioned 
much  confusion. 

The  cedar  of  Lebanon,  or  great  cedar,  ( Pinvs  Cedrics,)  is  a cone-bearing,  resinous  tree,  and  one 
of  the  pines.  It  is  tall  and  majestic,  and  grows  to  a great  size  ; the  mean  dimensions  of  it-1  trunk 


938 


WOODS,  VARIETIES  OF. 


are  50  feet  high  and  39  Indies  diameter.  The  wood  is  of  a ridi  yellowish  brown,  straight-grained 
and  it  has  a peculiar  odor.  The  tree  is  famous  in  Scripture  for  its  size  and  durability,  (Ezekiel  xxxi 
3,  5,  8 ;)  it  was  used  in  the  construction  of  Solomon's  temple  at  Jerusalem,  and  many  Grecian  tem- 
ples and  statues.  A few  fine  trees  are  said  still  to  remain  on  Mount  Lebanon  ; but  the  wood  wa» 
also  procured,  iu  the  time  of  Vitruvius,  from  other  parts  of  Syria,  and  from  Crete,  Africa,  &c  — 
Tredgold.  1 

The  Pencil  cedar  is  the  Juniperus  virginiana ; it  is  also  of  the  same  natural  order  as  the  pine- 
tree.  It  is  a native  of  North  America.  The  grain  of  the  wood  is  remarkably  regular  and  soft,  on 
which  account,  principally,  it  is  used  for  the  manufacture  of  pencils,  and  from  its  agreeable  scent, 
for  the  inside  work  of  small  cabinets ; from  the  same  reason  it  is  made  into  matches  for  the 
drawing-room. 

Another  species  is  the  Juniperus  bermudiana  ; it  is  a much  harder  and  heavier  wood  than  the 
pencil  cedar,  with  a similar  smell  and  appearance.  It  was  formerly  much  used  in  ship-building; 
many  of  the  timbers  of  the  Spanish  ships  taken  in  the  last  war  were  of  the  Bermuda  cedar. 

The  cedar  known  to  cabinet-makers  by  the  name  of  Havana  cedar,  is  the  wood  of  the  Cedrcla 
odorata  of  Linnaeus,  and  belongs  to  the  same  natural  order  as  mahogany,  which  it  resembles, 
although  it  is  softer  and  paler,  and  without  any  variety  of  color.  It  is  imported  in  considerable 
quantities  from  the  island  of  Cuba,  and  is  excellent  for  the  insides  of  drawers  and  wardrobes : all 
the  cigar-boxes  from  Havana  are  made  of  this  kind  of  cedar  ; the  wood  is  brittle  and  porous.  Some 
kinds  of  the  Havana  cedar  are  not  proper  for  cabinet-work,  as  the  gum  oozes  out  and  makes  the 
surface  of  the  work  very  sticky  and  unpleasant. 

There  is  another  kind  more  red  in  color,  called  red  cedar ; there  are  also  white  cedars  common 
to  America  : one  kind  is  called  prickly  cedar,  from  its  being  covered  with  spines  ; this  is  very  like 
the  white  hemlock,  and  grows  to  4 feet  diameter,  and  60  to  70  feet  high,  and  is  much  used  for 
railway  works. 

Another  sort,  from  New  South  Wales,  is  the  wood  of  the  Ccdrela  Toona ; it  is  somewhat  similar 
to  the  Havana,  but  more  red  in  color,  and  of  a coarser  grain ; it  sometimes  measures  4 feet  diam- 
eter. This  kind  is  also  found  in  the  East  Indies ; it  is  in  common  use  in  joinery-work.  Most  of 
the  cedars  have  been  used  for  ship-building. 

The  Himalayan  cedar  ( Juniperus  excclsa ) is  harder  and  less  odoriferous  than  the  pencil  cedar, 
but  is  an  excellent  light  wood  between  pencil  cedar  and  deal  in  general  character. 

The  cedar  of  Lebanon  is  usually  called  Pinus  Cedrus,  but  sometimes  Cedrus  Li banus  ; the  lofty 
Deodara,  a native  of  the  Himalayas,  with  fragrant  and  almost  imperishable  wood,  and  often 
called  the  Indian  cedar,  is  sometimes  referred  to  the  genus  Pinus , and  sometimes  to  that  of 
Cedrus  or  Larix,  with  the  specific  name  of  Deodara. 

The  wood  of  several  of  the  Conifers;  is,  however,  called  cedar.  The  wood  of  Juniperus  vir- 
giniana is  called  red  or  pencil  cedar,  and  that  of  J.  bermudiana  is  called  Bermuda  cedar ; of 
J hcm-badensis  is  called  Barbadoes  cedar  ; while  the  Juniper  of  the  North  of  Spain,  and  South 
of  France,  and  of  the  Levant,  is  called  J.  oxycedrus : the  white  cedar  of  North  America,  a 
less  valuable  wood  than  the  red  cedar,  is  yielded  by  Cuprcssus  Thyoides,  and  the  cedar-wood 
of  Japan,  according  to  Thunberg,  is  a species  of  cypress. 

The  name  cedar  is,  however,  applied  to  a number  of  woods  in  our  different  colonies,  which  are 
in  no  way  related  to  the  Coniferm : thus  the  cedar  of  Guiana  is  the  wood  of  Idea  altissima, 
white  wood  or  white  cedar  of  Jamaica  is  Bignonia  leucoxylon,  and  bastard  cedar  is  Guazuma 
ulmifolia.  In  New  South  Wales,  again,  the  term  white  cedar  is  applied  to  Melia  Azedera.ch, 
and  red  cedar  to  that  of  Flindersia  australis,  as  well  as  to  the  wood  of  the  Toon-tree,  or 
Cedrcla  Toona. 

Jherb.y-tk.ee  is  a hard,  close-grained  wood,  of  a pale  red  brown,  that  grows  to  the  size  of  20  or  24 
inches,  but  it  is  more  Usually  of  half  that  size.  When  stained  with  lime,  and  oiled  or  varnished, 
it  closely  resembles  mahogany  ; it  is  much  used  for  common  and  best  furniture  and  chairs,  and  is 
one  of  the  best  brown  woods  of  the  Tunbridge  turners.  The  wood  of  the  black-heart  cherry-tree 
is  considered  to  be  the  best.  The  Spanish  American  cherry-tree  is  very  elastic,  and  is  used  for 
felucca  masts. 

Cerasus  avium  is  the  wild  cherry.  C.  duracina  is  the  heart  cherry  or  Bigarreau.  The  wood  of 
C.  Mahaleb  is  much  used  by  the  French,  and  is  called  bois  de  Sainte  Ijucie. 

Chestnut  ( Castanea  vesca ) is  common  to  Europe  ; mean  size  44  feet  high,  37  inches  diameter;  is  very 
long-lived  and  durable.  The  sweet,  or  Spanish  chestnut,  is  very  much  like  oak,  and  is  sometimes  mis- 
taken for  it;  it  was  formerly  much  used  in  house-carpentry  and  furniture.  The  young  wood  is 
very  elastic,  and  is  used  for  the  rings  of  ships’  masts,  the  hoops  for  tubs,  churns,  &c.,  but  the  old 
wood  is  considered  to  be  rather  brittle.  See  Horse-chestnut. 

The  edible  or  sweet  chestnut  is  the  Castanea  vesca , but  the  horse-chestnut  (which  see)  belongs  to 
a very  different  genus.  The  wood,  formerly  much  used  in  house-building  and  carpentry,  and 
which,  famed  for  its  durability,  has  been  mistaken  for  chestnut,  is  now  considered  to  be  that  of 
an  oak,  Quercus  sessilifiora. 

Cocoa- wood,  or  Cocus,  is  imported  from  the  West  Indies  in  logs  from  2 to  8 inches  diameter,  sawn  to 
the  length  of  3 to  6 feet,  tolerably  free  from  knots,  with  a thick  yellow  sap : the  heart,  which  is 
rarely  sound,  is  of  a light  yellow  brown,  streaked,  when  first  cut,  with  hazel  and  darker  brown, 
but  it  changes  to  deep  brown,  sometimes  almost  black.  Cocoa-wood  is  much  used  for  turnery  of 
all  kinds,  and  for  flutes ; it  is  excellent  for  eccentric  turning,  and  in  that  respect  is  next  to  the 
African  blackwood. 

An  apparent  variety  of  cocoa-wood,  from  2 to  6 or  7 inches  diameter,  with  a large  proportion  of 
hard  sap  of  the  color  of  beechwood,  and  heartwood  of  a chestnut-brown  color,  is  used  for  tree- 
nails and  pins  for  ship-work,  and  purposes  similar  to  lignum-vitie,  to  which  it  bears  some  resem- 


WOODS,  VARIETIES  OF. 


939  • 


blance,  although  it  i3  much  smaller,  has  a rough  bark,  the  sap  is  more  red,  and  the  heart  darker 
and  more  handsomely  colored  when  first  opened  than  lignum-vitae  ; it  is  intermediate  between  it 
and  cocoa-wood.  Another  but  inferior  wood  exactly  agrees  with  the  ordinary  cocoa-wood,  but 
that  the  heart  is  in  wavy  rings,  alternately  hard  and  soft. 

Cocoa-wood  has  no  connection  with  the  cocoanut,  which  is  the  fruit  of  a palm-tree  common  to 
the  East  and  West  Indies,  the  Cocos  nucifera  ; neither  can  it  have  any  relation  to  the  other  endo- 
genous trees  which  produce  the  coquilla-nut,  the  Attalia  funifera  according  to  Martius,  and  Cocos 
lapidea  of  Gasrtner,  or  of  the  Cacao  Theobroma,  or  the  chocolate-nut  tree. 

It  is  really  singular  that  the  exact  localities  and  the  botanical  name  of  the  cocoa-wood  that  is  so 
much  used,  should  be  uncertain : it  appears  to  come  from  a country  producing  sugar,  being  often 
imported  as  dunnage,  or  the  stowage  upon  which  the  sugar  hogsheads  are  packed  : it  is  also  known 
as  brown  ebony,  but  the  Amerimnum  Ebenus  of  Jamaica  seems  dissimilar. 

The  cocus-wood  of  commerce  is  not  easy  to  trace  to  any  of  the  trees  of  the  West  Indies ; the 
cocoa  plum  is  Chrysobalanus  Icaco,  which  forms  only  a shrub  ; Coccoloba  uvifera,  or  mangrove 
grape-tree,  grows  large  and  yields  a beautiful  wood  for  cabinet-work,  but  which  is  light  and 
of  a white  color.  In  appearance  and  description  it  comes  near  to  the  Greenlieart  or  Laurns 
chloroxylon,  which  is  also  called  Cogwood. 

Oocoanut-tree.  See  Palms. 

Cocoanut-shell.  The  general  characters  of  this  fruit,  the  produce  of  the  palm  Cocos  nucifera,  are 
too  well  known  to  need  particular  description  : in  India  its  thick  fibrous  husk  is  made  into  the  coir- 
rope,  and  in  Europe  into  rope,  matting,  brushes,  <fcc.  The  substance  of  the  shell  is  very  brittle, 
and  its  structure  is  somewhat  fibrous,  but  it  admits  of  being  turned  in  an  agreeable  manner. 
Those  shells  which  are  tolerably  circular  are  used  for  the  bodies  of  cups  and  vases,  the  feet  and 
covers  being  made  of  wood  or  ivory.  Common  buttons  are  also  made  of  the  cocoanut-shell,  and 
are  considered  better  than  those  of  horn,  as  they  do  not,  like  that  material,  absorb  moisture,  which 
causes  them  to  swell  and  twist. 

Cocus.  See  Cocoa-wood. 

Coffee-tree,  ( Coffea  arabica.)  The  wood  is  of  a light  greenish-brown  or  dusky -yellow,  with  a bark 
externally  resembling  boxwood,  but  thicker  and  darker ; it  has  no  smell,  and  but  little  taste.  The 
tree  does  not  grow  more  than  a few  feet  high,  and  it  is  cut  down  in  the  plantations  to  five  or  six 
feet,  and  is  not  therefore  useful  in  manufactures. 

The  tree  called  Kentucky  coffee-tree,  or  hardy  bonduc,  is  very  different  from  the  common  coffee  : 
it  forms'  a large  tree  called  Gymnocladus  canadensis ; the  wood  is  compact,  of  a rosy  hue,  and  used 
by  cabinet-makers. 

Coral-wood,  says  Bergeron,  is  so  named  from  its  color.  When  first  cut  it  is  yellow,  but  soon  changes 
to  a fine  red  or  superb  coral;  it  is  hard,  and  receives  a fine  polish  : he  also  speaks  of  a damasked 
coral-wood.  It  is  difficult  to  associate  these  with  the  red  woods ; they  are,  perhaps,  from  the  de- 
scriptions, nearest  to  the  camwood  from  Africa. 

The  coral-tree,  so  called  from  the  color  of  its  flowers,  is  Efythrina  Corallodendron  ; but  the 
bois  de  corail  of  the  French  is  the  wood  of  Adenanthera  pavonina,  which  is  hard,  reddish- 
• ' colored,  and  sometimes  confounded  with  red  sanders-wood. 

Coquill a-nuts  are  produced  in  the  Brazils  by  Attalia  funifera,  according  to  Martius,  or  the  Cocos 
lapidea  of  Gsertner ; the  latter  title  is  highly  descriptive.  The  coquilla-nut  is  represented  in  sec- 
tion, half  size,  in  Fig.  3950  : the  shell  is  nearly  solid,  with  the  exception  of  the  two  separate  cavities 
represented,  each  containing  a hard,  flattened,  greasy  kernel,  generally  of  a disagreeable  flavor  : 
the  cells  occasionally  inclose  a grub  or  chrysalis  similar  to  that  figured,  which  consumes  the  fruit 

3950.  3951.  3952. 


The  passages  leading  into  the  chambers  are  lined  with  filaments  or  bristles,  and  this  end  of  the 
shell  terminates  exteriorly  in  a covering  of  these  bristles,  which  conceal  the  passages ; this  end  is 
consequently  almost  useless,  but  the  opposite  is  entirely  solid,  and  terminates  in  the  pointed  attach- 
ment of  the  stalk.  Sometimes  the  shell  contains  three  kernels,  less  frequently  but  one  only,  and 
we  have  heard  of  one  coquilla-nut  that  was  entirely  solid.  The  substance  of  the  shell  is  brittle, 
hard,  close,  and  of  a hazel-brown,  sometimes  marked  and  dotted,  but  generally  uniform.  Under 
the  action  of  sharp  turning  tools  it  is  very  agreeable  to  turn,  more  so  than  the  cocoanut-shell , it 
may  be  eccentric-turned,  cut  into  excellent  screws,  and  admits  of  an  admirable  polish,  and  of  being 
lackered.  On  the  whole  it  is  a very  useful  material,  and  suitable  for  a great  variety  of  smaD 


940 


WOODS,  VARIETIES  -OF. 


ornamental  works,  both  turned  and  filed  ; coquilla-nuts  are  extensively  manufactured  into  th* 
knobs  of  umbrellas  and  parasols,  small  toys,  dzc. 

Coromandel,  or  Calamander,  the  produce  of  Ceylon,  and  the  coast  of  India,  is  shipped  in  logs  and 
planks  from  Bombay  and  Madras.  The  figure  is  between  that  of  rosewood  and  zebra-wood  ; the 
color  of  the  ground  is  usually  of  a red  hazel-brown,  described  also  as  chocolate-brown,  with  black 
stripes  and  marks.  It  is  said  to  be  so  hard  as  almost  to  require  grinding  rather  than  cutting ; this 
is  not  exactly  true,  as  the  veneer  saws  cut  it  without  particular  difficulty : it  is  a very  handsome 
furniture  wood,  and  turns  well ; it  is  considered  to  be  a variety  of  ebony. 

There  are  three  varieties  of  Coromandel:  the  Calamander  or  Coromandel,  which  is  the  darkest, 
and  the  most  commonly  seen  in  this  country,  the  Calemberri , which  is  lighter  colored  and  striped, 
and  the  Omander,  the  ground  of  which  is  as  light  as  English  yew,  but  of  a redder  cast,  with  a few 
slight  veins  and  marks  of  darker  tints.  The  wood  is  scarce,  and  almost  or  quite  limited  to  Ceylon  ; 
it  grows  between  the  clefts  of  rocks  ; this  renders  it  difficult  to  extract  the  roots,  which  are  the 
most  beautiful  parts  of  the  trees. 

The  Calamauder-wood  tree  is  Diospyros  hirsuta,  and  Kadum  Beriya  is  I).  Ebcnaster,  according 
to  Moore’s  Catalogue  of  Ceylon  Plants,  and  therefore  of  the  same  genus  as  the  true  ebony. 

Coromandel,  falsely  so  called,  has  a black  ground,  and  is  either  striped,  mottled,  or  dappled,  with  light 
yellow,  orange,  or  red ; it  is  a description  of  accidental  or  imperfect  East  Indian  black  ebony. 
Some  of  the  pieces  are  very  handsome  ; it  is  used  for  similar  purposes  to  the  true  Coromandel, 
from  which,  however,  it  is  entirely  different,  and  generally  inferior,  although  it  is  considered  a 
variety  of  the  same  group. 

Corosos,  or  Ivory-nuts,  are  produced  by  Phyteleplias  macrocarpa,  growing  in  Central  America,  and 
Columbia. — {Humboldt.)  They  are  described  as  seeds  with  osseous  albumen  ; the  tree  is  a genus 
allied  to  the  Pandanece,  or  Screw  Pines,  and  also  to  the  Palms.  The  nuts  are  of  irregular  shapes, 
from  one  to  two  inches  diameter,  and  when  inclosed  in  their  thin  husks,  they  resemble  small  pota- 
toes covered  with  light-brown  earth : the  coat  of  the  nut  itself  is  of  a darker  brown,  with  a few 
loose  filaments  folded  upon  it.  The  internal  substance  of  the  ivory-nut  resembles  white  wax  rather 
than  ivory;  it  has,  when  dried,  a faint  and  somewhat  transparent  tint,  between  yellow  and  blue, 
but  when  opened  it  is  often  almost  green  from  the  quantity  of  moisture  it  contains,  and  in  losing 
which  it  contracts  considerably.  Each  nut  has  a hole,  which  leads  into  a small,  central,  angular 
cavity ; this,  joined  to  the  irregularity  of  the  external  form,  limits  the  purposes  to  which  they  are 
applied — principally  the  knobs  of  walking-sticks,  and  a few  other  small  works.  Fig.  8951  is  the 
section  of  the  ivory-nut  at  right  angles  with  the  stalk,  and  half  size  ; and  Fig.  8952  is  the  section 
through  the  stalk  itself,  which  proceeds  from  s. 

Cowdje.  See  Pines. 

Cr/.b-tree,  the  wild  Apple-tree;  principally  used  by  millwrights  for  the  teeth  of  wheels.  See 
Apple-tree. 

Cypress-tree.  Of  this  there  are  many  varieties  ; the  principal  are  the  Cuvressus  sempervirens,  and 
the  white  cypress  or  white  cedar  of  North  America,  the  Cupressus  Tliyoides  ; the  latter  is  much 
used  as  a timber  wood  ; it  is  an  immense  tree,  and  is  considered  to  be  more  durable  even  than 
the  cedar  of  Lebanon.  The  Cupressus  sempervirens  is  said  to  have  been  much  used  bj^  the 
ancients ; by  the  Egyptians  for  the  cases  for  some  of  their  mummies,  by  the  Athenians  for 
coffins,  and  for  the  original  doors  of  St.  Peter’s  at  Rome,  which,  on  being  replaced  after  six  hun- 
dred years  by  gates  of  brass,  were  found  to  be  perfectly  free  from  symptoms  of  decay,  and 
within,  to  have  retained  part  of  the  original  odor  of  the  wood. — Tredgold. 

It  is  probable  that  the  wood  of  Thuja  articulata  (see  Arbor  vitce)  w*as  also  used  by  the  an- 
cients, and  has  sometimes  been  mistaken  for  that  of  Cypress. 

Deal.  See  Pines. 

Dogwood,  a small  underwood,  which  is  so  remarkably  free  from  silex,  that  little  splinters  of  the 
wood  are  used  by  the  watchmaker  for  cleaning  out  the  pivot-holes  of  watches,  and  by  the  opti 
cian  for  removing  the  dust  from  small  deep-seated  lenses  ; dogwood  is  also  used  for  butchers’ 
skewers,  and  tooth-picks. 

The  charcoal  of  the  black  dogwood  is  employed  in  the  manufacture  of  the  best  sporting  gun 
powder,  alder  and  willow  charcoal  for  the  government  powder. — Wilkinson' s Engines  of  War 
1811. 

Cornns  sanguined  is  the  wild  cornel  or  common  dogwood,  C.  mas.  is  the  male  dogwood  or 
Cornelian  cherry,  while  C.florida  is  an  American  species ; others  are  found  in  the  Himalayas. 
The  name  dogwood  is  applied  in  Jamaica  to  Piscidia  Erithrina. 

East  Indian  Blackwood,  ( Dalbergia  latifolia,)  called  Blackwood-tree  by  the  English  and  Sit  Sal 
by  the  natives  of  India,  on  the  Malabar  coast,  where  it  grows  to  an  immense  size.  The  wood  of 
the  trunk  and  large  branches  is  extensively  used  for  making  furniture  ; it  is  heavy,  sinking  in 
water,  close-grained,  of  a greenish  or  greenish-black  color,  with  lighter-colored  veins  running  in 
various  directions,  and  takes  a fine  polish. 

Ebony  is  described  as  of  several  colors,  as  yellow,  red,  green,  and  black.  The  existence  of  yellow 
and  red  ebonies  appears  questionable.  The  black  ebony  is  the  kind  always  referred  to  when 
the  name  is  mentioned  alone  ; in  fact,  “ as  black  as  ebony”  is  an  old  proverb.  The  wood  is 
surrounded  by  a white  sap  3 or  4 inches  thick.  The  green  ebony  is  an  entirely  different  tree, 
with  a thin  smooth  bark,  growing  in  the  West  Indies. 

Three  kinds  are  imported : No.  1,  from  the  Mauritius,  in  round  sticks  like  scaffold  poles,  they 
seldom  exceed  14  in.  diameter ; No.  2,  the  East  Indian,  which  grows  in  Ceylon,  the  East  India 
islands,  and  on  the  continent  of  India ; this  is  mostly  shipped  from  Madras  and  Bombay  in  logs 
from  6 to  20  and  sometimes  even  28  in.  diameter,  and  also  in  planks;  and  No.  3,  tie  African 
ebony,  shipped  from  the  Cape  of  Good  Hope  in  billets,  the  general  sizes  of  which  are  from  3 to 


WOODS,  VARIETIES  OF. 


941 


6 ft.  long,  3 to  6 in.  wide,  and  2 to  4 in.  thick;  these  are  rent  out  of  the  trees,  and  are  thence 
often  called  billet-wood. 

No.  1,  the  Mauritius,  is  the  blackest  and  finest  in  the  grain,  as  well  as  the  hardest  and  most 
beautiful  of  the  three,  but  also  the  most  costly  aud  unsound ; No.  2,  the  East  Indian,  is  lesa 
wasteful,  but  of  an  inferior  grain  and  color  to  the  above  ; and  No.  3,  the  African,  is  the  least 
wasteful,  as  all  the  refuse  is  left  behind,  and  all  th&t  is  imported  is  useable,  but  it  is  the  most 
porous,  and' the  worst  in  point  of  color. 

They  are  all  used  for  cabinet,  mosaic,  and  turnery  works  ; also  for  flutes,  the  handles  of  doors, 
knives,  and  surgeons’  instruments,  and  many  other  purposes.  Piano-forte  keys  are  generally  made 
of  the  East  Indian  variety. 

The  African  stands  the  best,  and  is  the  only  sort  used  for  sextants. 

Colonel  Lloyd  says,  the  Mauritius  ebony  when  first  cut  is  beautifully  sound,  but  that  it  splits 
like  all  other  woods  from  neglectful  exposure  to  the  sun.  The  workmen  who  ttse  it,  immerse  it 
in  water  as  soon  as  it  is  felled  for  6 to  18  months ; it  is  taken  out,  and  the  two  ends  are  secured 
from  splitting  by  iron  rings  and  wedges.  He  considers  the  Mauritius  ebony  to  be  the  finest,  next 
the  Madagascar,  and  afterwards  the  Ceylon. 

The  black  ebony  is  also  met  with  in  South  America,  but  much  less  generally  than  in  Asia  ana 
Africa. 

The  ebony  of  Mauritius  is  yielded  by  Diospyros  Ebenus,  that  of  Ceylon  is  I).  Ebenaster,  while 
the  ebony-tree  of  the  Coromandel  coast  is  D.  melanoxylon  ; other  species,  as  I>.  tomentosa 
and  I).  Boylei,  yield  ebony  on  the  continent  of  India.  The  tree  yielding  the  African  ebony 
is  not  ascertained.  A kind  of  ebony  is  produced  by  Ameriinnum  Ebenus , in  the  West  In- 
dies, and  called  Jamaica  ebony. 

Mountain  Ebony.  The  different  species  of  Banhinice  are  so  called:  B.  porrecta  grows  on 
the  hills  in  Jamaica,  and  has  wood  which  is  hard  and  veined  with  black. 

See  Green  Ebony  and  Coromandel. 

Elder,  ( Sambucus  nigra).  The  branches  of  the  elder  contain  a very  light  kind  of  pith,  which  is  used 
when  dried  for  electrical  purposes.  The  surrounding  wood  is  peculiarly  strong  and  elastic.  The 
trunk-wood  is  tough  and  close-grained  ; it  is  frequently  used  for  common  carpenters’  rules  ana 
inferior  t-urnery-work,  for  weavers’  shuttles,  (many  of  which  are  also  made  of  boxwood,)  for 
fishermen's  netting  pins,  shoemakers’  pegs,  (fee. 

Elm,  ( Ulmus ,)  a timber-tree,  of  which  there  are  five  species;  mean  size,  44  ft.  long,  32  in.  diameter. 
The  heartwood  is  red  brown,  darker  than  oak,  the  sap  yellowish  or  brownish  white  .with  pores 
inclining  to  red  ; the  wood  is  porous,  cross-grained,  and  shrinks  and  twists  much  in  drying.  Elm 
is  not  liable  to  split,  and  bears  the  driving  of  nails  or  bolts  better  than  any  other  timber,  and  it 
is  exceedingly  durable  when  constantly  wet ; it  is  therefore  much  used  for  the  keels  of  vessels, 
and  for  wet  foundations,  waterworks,  piles,  pumps,  and  boards  for  coffins ; from  its  toughness, 
elm  is  selected  for  the  naves  of  wheels,  shells  for  tackle-blocks,  and  sometimes  for  the  gunwales 
of  ships,  and  also  for  many  purposes  of  common  turnery,  as  it  bears  very  rough  usage  without 
splitting. 

Wych  Elm.  This  sometimes  grows  to  the  height  of  10  feet,  and  the  diameter  of  3J  feet ; the 
branches  are  principally  at  the  top,  the  wood  is  lighter  and  more  yellow  in  color  than  the  above, 
also  straighter  and  finer  in  the  grain.  It  is  tough,  similar  to  young  sweet  chestnut  for  bending, 
and  is  much  used  by  coachmakers,  and  by  shipwrights  for  jolly-boats. 

Bock  Elm  appears  very  like  the  last ; it  is  extensively  used  for  boat-building,  and  sometimes 
for  archery  bows,  as  it  is  considered  to  bend  very  well. 

Ulmus  campestris  is  the  common  small-leaved  elm,  U.  effusa  is  the  spreading-branched,  U. 
glabra  is  the  smooth-leaved,  and  U.  montana  the  Wych  elm.  Ulmus  Americana,  or  the 
American  elm,  is  used  for  the  same  purposes  as  the  European  siiecies,  though  the  wood  is 
inferior  in  quality.  U.  fulva  and  alata  are  other  American  species,  and  several  species  are 
found  in  the  Himalayas. 
irs  and  Pines.  See  Pines. 

Eustio  is  the  wood  of  a species  of  Mulberry,  (Morns  tinctorial  growing  in  most  parts  of  South 
America,  the  United  States,  and  West  Indies.  It  is  a large  and  handsome  tree  ; it  is  shipped  in 
trimmed  logs  from  2 to  4 ft.  long,  3 to  8 in.  diameter  ; the  color  of  the  wood  is  a greenish- 
yellow  ; it  is  principally  used  for  dyeing  greens  and  yellows,  and  also  in  mosaic  cabinet-work  and 
turning. 

Grexadillo,  Granillo,  or  Grenada  Oocus,  from  the  West  Indies,  is  apparently  a lighter  description  of 
the  common  cocoa  or  cocus-wood,  but  changes  ultimately  to  as  dark  a color,  although  more  slowly. 
It  is  frequently  imported  without  the  sap. 

The  tree  yielding  this  has  not  been  ascertained  ; the  hois  dc  Grenadille  of  the  French  is  also 
called  red  ebony  by  their  cabinet-makers. 

Green  Ebony,  from  Jamaica,  and  the  West  Indies  generally.  It  is  cut  in  lengths  of  3 to  6 ft.,  has  a 
bark  much  like  cocus,  but  thinner  and  smoother ; the  heartwood  is  of  a brownish  green,  like  the  green 
fig.  It  is  used  for  round  rulers,  turnery,  and  marquetry-work,  and  it  cleaves  remarkably  well. 
The  dust  is  very  puugent,  and  changes  to  red  when  the  hands  are  washed  with  soap  and  water. 
The  wood  is  very  much  used  for  dyeing,  and  it  contains  so  much  resinous  matter,  that  the  negroes 
in  the  West  Indies  employ  it  in  fishing  as  a torch.  The  candle-woods  of  the  West  Indies  obtain 
their  name  probably  from  the  same  circumstance ; they  are  allied  to  the  rosewoods,  but  are  ol 
lighter  yellow  colors. 

The  ebony  of  Jamaica  is  Amcrimnum  Ebenus,  and  has  been  mentioned  under  Ebony.  The 
wood' is  described  as  being  of  a fine  greenish-brown  color,  hard,  durable,  and  capable  of  tak 
ing  a fine  polish ; B.  leucoxylon  of  South  America  yields  le  hois  d'ebene  verte. 


942 


WOODS,  VARIETIES  OF. 


Gr.kexhe,\rt  ; from  Jamaica,  Demerara  and  the  Brazils,  bears  a general  resemblance  to  cocoa-wood 
both  in  size  and  bark,  but  the  latter  has  a redder  tint.  Greenheart  when  first  cut  is  of  a light 
green  brown,  and  striped,  but  it  changes  to  the  color  of  Lignum-vitce,  and  is  by  some  considered 
to  be  Dernicioua.  It  is  used  for  turnery  and  other  works,  but  its  texture  is  coarse,  and  it  will 
not  cleave  at  all  profitably. 

Greenheart  used  in  ship-building  is  entirely  different  from  the  above,  and  runs  into  several 
varieties. 

Dr.  Bancroft  describes  Greenheart,  or  the  Sipicra-t ree,  to  be  in  size  like  the  locust-tree,  say  60 
or  70  feet  high  : there  are  two  species,  the  black  and  the  yellow,  differing  only  in  the  color  of 
tiieir  bark  and  wood.  He  says  there  is  also  a purple-heart  wood,  of  a bright  crimson  color,  but 
which  changes  to  purple,  and  is  esteemed  more  valuable  than  the  preceding. 

The  Greenheart  of  Jamaica  and  Guiana  is  the  Laurus  Chloroxylon  of  botanists  ; it  is  also 
called  Cogwood  in  the  former,  and  Sipicri  in  the  latter  locality. 

Gpmwood.  or  blue  Gumwood,  is  the  produce  of  New  South  Wales;  it  is  sent  over  in  large  logs  and 
planks  ; the  color  is  similar  to  that  of  dark  Spanish  mahogany,  with  a blue,  sometimes  a purple- 
gray  cast : it  is  used  in  ship-building.  There  is  also  a variety  of  a redder  tint,  called  red  Gum- 
wood,  which  is  used  for  ramrods ; both  are  also  employed  by  the  turner. 

Eucalyptus  piperita  is  the  blue  gum-tree  of  New  South  Wales,  while  red  gum-tree  is  another 
species,  probably  E.  resinifera. 

Hackmetack  Larch.  See  Pines. 

Harewood.  See  Sycamore. 

Haavthorn  ( Cratcegus  oxyacantha ) has  hard  wood  of  a whitish  color,  with  a tinge  of  yellow;  the 
grain  is  fine,  and  the  wood  takes  a good  polish  ; but  being  small  and  difficult  to  work,  it  is  not 
much  used. 

Hazel,  a small  underwood,  but  little  used  for  turning,  except  for  a few  toys.  It  is  very  elastic,  and 
is  used,  as  well  as  the  ground-ash,  for  the  rods  of  blacksmiths’  chisels,  hoops  of  casks,  <fcc.  Its 
botanical  name  is  Corylus  Avellana. 

Hickory,  or  White  Walnut,  ( Juglans  alba,)  is  a native  of  this  country  ; it  is  a large  tree,  sometimes 
exceeding  3 ft.  diameter.  The  wood  of  young  trees  is  exceedingly  tough  and  flexible,  and  makes 
excellent  handspikes,  and  other  works  requiring  elasticity.  The  bark  of  hickory  is  recommended 
by  Dr.  Bancroft  as  a yellow  dye. 

Holly  ( Ilex  cequifolium)  is  a very  clean,  fine-grained  wood,  the  whitest  and  most  costly  of  those 
used  by  the  Tunbridge-ware  manufacturer,  who  employs  it  for  a variety  of  his  best  works, 
especially  those  which  are  to  be  painted  in  water-colors.  It  is  closer  in  texture  than  any  other 
English  woods,  and  does  not  readily  absorb  foreign  matters,  for  which  reason  it  is  used  for  painted 
screens,  the  squares  of  draft-boards,  and  for  the  stringings  or  lines  of  cabinet-work,  both  in  the 
white  state  and  when  dyed  black,  also  for  some  of  the  inside  works  of  piano-fortes,  harps,  for 
calico-printers’  blocks,  &c.  When  larger  wood  than  holly  is  required,  the  horse-chestnut  is  em- 
ployed, but  the  latter  is  much  softer.  . 

The  holly  requires  very  particular  care  in  its  treatment:  immediately  it  is  felled  it  is  prepared 
into  pieces  of  the  form  ultimately  required,  as  planks,  veneers,  or  round  blocks  for  turning.  The 
veneers  are  hung  up  separately  to  dry,  as  resting  in  contact  even  for  two  or  three  hours  would 
stain  them ; the  round  blocks  are  boiled  in  plain  water  for  two  or  three  hours,  and  on  removal 
from  the  copper  they  are  thrown  in  a heap  and  closely  covered  up  with  sacking  to  exclude  the  air, 
which  would  otherwise  cause  them  to  split.  The  heap  is  gradually  exposed  as  it  dries ; at  the 
end  of  about  four  weeks  the  pieces  look  greenish,  and  are  covered  with  mildew  sometimes  as 
thickly  as  one-sixteenth  of  an  inch ; this  is  brushed  off  at  intervals  of  three  or  four  weeks,  and  in 
about  six  months  the  wood  is  fit  for  use. 

Holly  is  a remarkably  tough,  clean  wood,  and  is  used  for  chucks ; but  this  troublesome  prepa 
ration  to  whiten  the  wood  (and  which  is  not  generally  practised  on  other  woods)  is  not  then  re- 
quired, although  a good  boil  hastens  the  extraction  of  the  sap,  and  the  subsequent  seasoning  of 
the  wood. 

The  American  species  of  this  genus  is  the  Ilex  opaca,  opaque-leaved  or  American  holly,  of 
which  the  wood  is  employed  in  turnery  and  cabinet-making ; there  are  other  species  in  the 
Himalayas. 

Hornbeam,  (Carpinus  Betulus,)  sometimes  also  called  yoke-elm,  is  a very  tough  and  stringy  wood, 
which  is  used  by  millwrights  for  the  cogs  of  wheels,  plumbers’  dressers  or  mallets,  and  a variety 
of  things  required  to  bear  rough  usage.  Hornbeam  is  sometimes  used  for  planes ; it  turns  very  well. 

Horse-chestnut  (pEsculus  hippocastum)  has  no  relation  to  the  Spanish  or  sweet  chestnut,  which  lat- 
ter is  more  nearly  allied  to  the  oaks.  The  horse-chestnut  is  one  of  the  white  woods  of  the  Tun- 
bridge turner ; it  is  close  and  soft,  even  in  the  grain,  and  is  much  used  for  brush-backs ; it  turns 
very  well  in  the  lathe,  and  is  a very  useful  wood.  It  is  softer  than  holly,  but  is  preferable  to  it  for 
large  painted  and  varnished  works,  on  account  of  its  greatly  superior  size.  It  is  but  little  used 
in  this  country. 

Horse-flesh  Wood,  one  of  the  Mangroves,  which  see. 

Indian  Blackwood.  See  East  Indian  Blackwood. 

Iron-wood  is  imported  from  the  Brazils,  the  East  and  West  Indies,  and  other  countries,  in  square  and 
round  logs,  6 to  9 in.  and  upwards  through.  Its  colors  are  very  dark  browns  and  reds,  sometimes 
streaked,  and  generally  straight-grained. 

The  iron-woods  are  commonly  employed  by  the  natives  of  uncivilized  countries  for  their  sev- 
eral sharp-edged  clubs  and  offensive  weapons ; in  England  they  are  principally  used  for  ramrods, 
walking-sticks,  for  turning,  and  various  purposes  requiring  great  hardness  and  durability : the 
more  red  varieties  are  frequently  called  beefwood. 


WOODS,  VARIETIES  OF. 


943 


Iron-wood  is  a term  applied  to  a great  variety  of  woods,  ill  consequence  of  their  hardness,  and 
almost  every  country  has  an  iron-wood  of  its  own.  Mesua  ferrea , which  has  received  its 
specific  name  from  the  hardness  of  its  wood,  is  a native  of  the  peninsula  of  India  and  of  the 
islands. 

Metrosidcros  vera  is  called  true  iron-wood : the  Chinese  are  said  to  make  their  rudders  and 
anchors  of  it,  and  among  the  Japanese  it  is  so  scarce  and  valuable,  that  it  is  only  allowed  to 
be  manufactured  for  the  service  of  their  king.  The  iron-wood  of  Southern  China  is  Baryxy- 
lumrufum;  of  the  island  of  Bourbon  Stadmannia  Sideroxylon,  and  of  the  Cape  of  Good 
Hope  Sideroxylon  melanophleum,  which  latter  is  very  hard,  close-grained,  and  sinks  in 
water. 

The  iron-wood  of  Guiana  is  Robinia  Panacoco,  (of  Aublet ;)  that  of  Jamaica  is  Fagara  Pterota, 
and  also  Erytliroxylum  areolatum , which  is  also  called  redwood.  JEgiphila  mariinicensis, 
and  Cocoloba  latifolia,  are  other  West  Indian  trees,  to  the  woods  of  which  the  name  of  iron- 
wood  has  been  applied. 

Ostrya  virginica,  called  American  hop  hornbeam,  has  wood  exceedingly  hard  and  heavy, 
whence  it  is  generally  called  iron-wood  in  this  country,  and  in  some  places  lever-wood. 

Jakwood  is  the  wood  of  Artocarpus  integrifolia,  or  the  entire-leaf  bread-fruit  tree,  a native  of  India ; 
is  imported  in  logs  from  3 to  5 feet  diameter,  and  also  in  planks;  the  grain  is  coarse  and  crooked, 
and  often  contains  sand.  The  wood  is  yellow  when  first  cut,  but  changes  to  a dull  red  or  ma- 
hogany color.  It  is  very  much  used  in  India  for  almost  every  purpose  of  house-carpentry  and 
furniture.  The  jakwood  is  very  abundant,  and  its  fruit  is  commonly  eaten  by  the  natives, 
and  also  sometimes  by  Europeans  at  dessert,  with  salt  and  water,  like  olives.  The  jakwood  is 
sometimes  misnamed  orange-wood  from  its  color,  and  also  jackwood,  Jaack- wood,  and  Kutliul. 
See  Baker’s  Papers. 

Jackaranda,  the  Portuguese  and  continental  name  for  Rosewood,  which  see. 

Juniper-wood.  The  wood  of  all  the  species  is  more  or  less  aromatic,  and  very  durable ; they  are 
found  in  the  cold  and  temperate  parts  of  the  world.  'Some  have  already  been  mentioned  under 
the  head  of  Cedar.  The  common  juniper,  Juniperus  communis,  has  wood  which  is  aromatic, 
finely  veined,  and  of  a yellowish-brown  color ; J.  excclsa,  lofty  or  Himalayan  cedar,  is  found  on 
those  mountains,  as  well  as  in  Siberia  and  North  America. 

Kiabooca-wood,  or  Amboyna-wood,  imported  from  Sincapore,  appears  to  be  the  excrescence  or  burr 
of  some  large  tree ; it  is  sawn  off  in  slabs  from  2 to  4 ft.  long,  4 to  24  in.  wide,  and  2 to  8 in. 
thick ; it  resembles  the  burr  of  the  yew-tree,  is  tolerably  hard,  and  full  of  small  curls  and  knots ; 
the  color  is  from  orange  to  chestnut-brown,  and  sometimes  red-brown.  It  is  a very  ornamental 
wood,  that  is  also  much  esteemed  in  China  and  India,  where  it  is  made  into  small  boxes  and 
writing-desks,  and  other  ornamental  works,  the  same  as  by  ourselves. 

The  Kiabooca  is  said  by  Prof.  Reinwardt,  of  Leyden,  to  be  the  burr  of  the  Plerosperrnum  in- 
dicum ; by  others  that  of  Pterocarpus  draco,  from  the  Moluccas,  the  island  of  Borneo,  Amboyna, 
<fcc.  The  native  name  appears,  from  Mr.  Wilson  Saunders’  specimen,  to  be  Serioulcut : the  wood 
itself  is  of  the  same  color  as  the  burr,  or  rather  lighter,  and  in  grain  resembles  plain  mahogany. 

“ The  root  of  the  cocoanut-tree  is  so  similar,  when  dry  and  seasoned,  to  the  ‘ bird’s-eye’  part 
of  the  wood  here  termed  kiabooca,  that  I can  perceive  no  difference ; the  cocoa  has  a tortuous 
and  silky  fracture,  almost  like  indurated  asbestos.” — Col.  G.  A.  Lloyd. 

The  comparison  of  the  palmwood  with  the  kiabooca  renders  the  question  uncertain,  as  amongst 
the  multitudes  of  ordinary  curly  woody  fibres,  that  one  cannot  account  for  in  a palm,  there  are 
a few  places  with  soft  friable  matter  much  resembling  its  cement. 

Eingwood,  called  also  Violet-wood,  is  imported  from  the  Brazils,  in  trimmed  logs  from  2 to  1 in. 
diameter,  generally  pipy,  or  hollow  in  the  heart.  It  is  beautifully  streaked  in  violet  tints  of  dif- 
ferent intensities,  finer  in  the  grain  than  rosewood,  and  is  principally  used  in  turning  and  small  cab- 
inet-work; being  generally  too  unsound  for  upholstery.  It  is  perhaps  one  of  the  most  beautiful  • 
of  the  hard  woods  in  appearance. 

Kourie.  See  Pines. 

Laburnum  ( Cytisus  Laburnum ) possesses  poisonous  seeds,  and  a small  dark  greenish-brown  wood, 
that  is  sometimes  used  in  ornamental  cabinet-work  and  marquetry.  Mr.  Aikiu  sayfe : “ In  the 
Laburnum  there  is  this  peculiarity,  which  I have  not  observed  in  any  other  wood,  namely,  that 
the  medullary  plates,  which  are  large  and  very  distinct,  are  white,  whereas  the  fibres  are  a dark 
brown;  a circumstance  that  gives  quite  an  extraordinary  appearance  to  this  wood.” 

The  Alpine  laburnum,  with  blackish  wood,  is  Cytisus  alpinus. 

Lancewood  is  imported  in  long  poles  from  3 to  6 in.  diameter  from  Cuba  and  Jamaica  ; it  has  a thin 
rind,  externally  similar  to  that  of  cocoa-wood ; it  is  called  one  of  the  rough-coated  woods,  and  has 
a bark  distinct  from  the  sap-wood,  but  together  they  are  very  thin.  Lancewood  is  of  a paler 
yellow  than  box,  and  rends  easily ; it  is  selected  for  elastic  works,  such  as  gig-shafts,  archery 
bows  and  springs ; these  are  bent  by  boiling  or  steaming ; lancewood  is  also  used  for  surveyors’ 
rods,  billiard-cues,  and  for  ordinary  rules,  which  are  described  as  being  made  of  boxwood. 

The  lancewood  of  Jamaica  is  Guatteria  virgata,  formerly  Uvaria  l-anccolata.  That  of  Guiana 
is  an  Anonaceous  plant,  and  probably  the  same  species. 

Larch.  See  Pines. 

Letter-wood.  See  Snakewood. 

Lemon-tree.  See  Orange-tree. 

LEorARD-wooD.  See  Palms. 

Ltc.num-vit/e,  or  Guaiacum,  is  a very  hard  and  heavy  wood.  It  is  shipped  from  Cuba,  Jamaica,  St. 
Domingo,  and  New  Providence,  in  logs  from  2-J-  to  36  in.  diameter,  and  is  one  of  the  heaviest  of 
the  woods.  It  grows  in  the  Isthmus  of  Darien  to  the  size  of  5 or  6 ft.,  and  is  there  calle  1 Gual- 


944 


WOODS,  VARIETIES  OE. 


lacan,  and  is  one  of  the  most  abundant  woods  of  the  country.  When  first  cut,  it  is  soft 
and  easily  worked,  but  it  becomes  mucli  harder  on  exposure  to  the  air.  The  wood  is  cross 
grained,  covered  with  a smooth  yellow  sap  like  box,  almost  as  hard  as  the  wood,  which  is  of  a 
dull  brownish-green,  and  contains  a large  quantity  of  the  gum  guaiacum,  which  is  extracted  for 
the  purposes  of  medicine.  Lignum-vitae  is  much  used  in  machinery,  Ac.,  for  rollers,  presses,  mills, 
pestles  and  mortars,  sheaves  for  ship-blocks,  and  a great  variety  of  other  works  requiring  hard- 
ness and  strength.  It  was  employed  by  the  Spaniards  for  making  gun-carriages  and  wheels. 

The  fibrous  structure  of  this  wood  is  very  remarkable  : the  fibres  cross  each  other  sometimes  as 
obliquely  as  at  an  angle  of  30  degrees  with  the  axis,  as  if  one  group  of  the  annual  layers  wound 
to  the  right,  the  next  to  the  left,  and  so  on,  but  without  much  apparent  exactitude. 

The  wood  can  hardly  be  split,  it  is  therefore  divided  with  the  saw;  and  when  thin  pieces, 
such  as  old  sheaves,  are  broken  asunder,  they  exhibit  a fracture  more  like  that  of  a mineral  than 
an  ordinary  wood.  The  chips,  and  even  the  corners  of  solid  blocks,  may  be  lighted  in  the  candle, 
and  will  burn  freely  from  the  quantity  of  gum  they  contain,  which  is  most  abundant  in  the 
heart- wood. 

The  Bahama  lignum-vitas  has  a very  large  proportion  of  sap-wood  ; pieces  of  8 or  10  inches 
diameter  have  heart-wood  that  scarcely  exceeds  1 or  2 inches  diameter.  One  variety  of  cocoa- 
wood,  and  also  the  almond-wood,  are  somewhat  similar  to  lignum-vitse. 

There  are  two  species,  Guaiacum  officinale  and  G.  sanctum , both  of  which  probably  yield  the 
lignum-vitse  of  commerce.  This  name  is  also  sometimes  applied  to  the  wood  of  Arbor  vitce. 

Lime-tree,  called  also  the  Linden-tree,  Tilia.  This  wood  is  very  light-colored,  fine  and  close  in  the 
grain,  and  when  properly  seasoned  it  is  not  liable  to  split  or  warp.  It  is  nearly  or  quite  as  soft 
as  pine,  and  is  used  in  the  construction  of  piano-fortes,  harps,  and  other  musical  instruments,  and 
for  the  cutting-boards  for  curriers,  shoemakers,  Ac.,  as  it  does  not  draw  or  bias  the  knife  in  any 
direction  of  the  grain,  nor  injure  its  edge ; it  turns  very  cleanly ; this  wood  has  recently  been 
used  for  the  frames  of  the  best  japanned  chairs  inlaid  with  mother-of-pearl.  Lime-tree  is  par- 
ticularly suitable  for  carving,  from  its  even  texture  and  freedom  from  knots : the  works  of  Gib- 
bons, at  Windsor  Castle  and  St.  Paul’s,  London,  are  of  lime-tree. 

The  lime-tree,  Tilia  europea :,  is  usually  divided  into  several  species : as  T.  intermedia , micro- 
phylla , rubra,  and  platyphylla. 

Locust-tree.  The  locust-tree  of  North  America  is  Robinia  pscudacacia.  The  wood  is  greenish-yel- 
low, with  a slight  tinge  of  red  in  the  pores  ; it  is  u=ed  like  oak.  Locust  is  much  esteemed  for  tree- 
nails for  ships,  and  for  posts,  stakes,  pales,  Ac.,  as  it  is  very  tough  and  durable  ; it  works  similarly 
to  ash,  and  is  very  good  for  turning. 

It  grows  most  abundantly  in  the  Southern  States ; but  it  is  pretty  generally  diffused  throughout 
the  whole  country.  It  sometimes  exceeds  four  feet  in  diameter  and  seventy  feet  in  height.  I here 
are  no  less  than  140  species  of  forest-trees  indigenous  to  the  United  States  which  exceed  thirty 
feet  in  height.  In  France  there  are  about  thirty,  and  in  Great  Britain  nearly  the  same  number. 

The  locust-tree  of  the  West  Indies  and  Guiana  is  Hymenea  Courbaril,  (Semiri,)  a tree  from  60 
to  80  feet  in  height,  and  five  or  six  feet  in  diameter  : the  color  of  the  wood  of  West  Indian  locust- 
tree  is  light  reddish-brown,  with  darker  veins,  and  the  main  size  36  inches.  The  wood  in  its  native 
country  is  used  for  mill-rollers  and  cogs  of  wheels.  Another  tree,  called  honey  locust,  Gleditschia 
triacanthus,  of  which  the  wood  splits  with  great  ease,  is  coarse-grained,  and  but  little  used. 

Logwood,  called  also  Campeacliy  logwood,  is  from  the  bay  of  that  name,  and  from  Jamaica,  Honduras, 
Ac.  It  is  scarcely  used  for  turning,  and  is  a dark  purple-red  dyewood,  that  is  consumed  in  large 
quantities  : its  botanical  name  is  Hcematoxylon  campechianum. 

Mahogany,  the  Swietenia  Mahogoni,  is  a native  of  the  West  Indies  and  the  country  round  the  Bay  of 
Honduras.  It  is  said  to  be  of  rapid  growth,  and  so  large  that  its  trunk  often  exceeds  40  feet  in 
length  and  6 feet  in  diameter.  This  wood  was  first  brought  to  London  in  the  year  1724  ; its  Span 
ish  name  is  Cadba. 

Spanish  mahogany  is  imported  from  Cuba,  Jamaica,  Hispaniola,  St.  Domingo,  and  some  other 
of  the  West  India  islands,  and  the  Spanish  Main,  in  logs  from  about  20  to  26  in.  square,  and  10  ft. 
long.  It  is  close-grained,  hard,  sometimes  strongly  figured,  and  generally  of  a darker  color  than 
Honduras  mahogany ; but  its  pores  frequently  appear  as  if  chalk  had  been  rubbed  into  them. 

Honduras  mahogany  is  imported  in  logs  of  larger  size  than  the  above,  that  is,  from  2 to  4 ft 
Square,  and  12  to  18  ft.  in  length:  sometimes  planks  have  been  obtained  6 or  7 ft.  wide.  Hon- 
duras mahogany  is  generally  lighter  than  the  Spanish,  and  also  more  open  and  irregular  in  the 
grain : many  of  the  pieces  are  of  a fine  golden  color,  with  showy  veins  and  figures.  The  worst 
kinds  are  those  the  most  filled  with  gray  specks,  from  which  the  Spanish  mahogany  (except  the 
Cuba)  iso  comparatively  free. 

Both  Spanish  and  Honduras  mahogany  are  supposed  to  be  produced  by  the  same  tree,  Swietenia 
Mahogoni  of  botanists,  but  some  suppose  that  the  Honduras  is  the  wood  of  a different  spe- 
cies, (V.  Don,  Syst.  1.  p.  688  ;)  but  Long,  in  his  history  of  Jamaica,  says,  “ What  grows  on  rocky 
grounds  is  of  small  diameter,  but  of  closer  grain,  heavier  weight,  and  more  beautifully  veined  ; 
what  is  produced  in  low,  rich,  and  moist  land  is  larger  in  dimensions,  more  light  and  porous, 
and  of  a pale  complexion.  This  constitutes  the  difference  between  the  Jamaica  wood  and  that 
which  is  collected  from  the  coast  of  Cuba  and  the  Spanish  Main ; the  former  is  mostly  found 
on  rocky  eminences,  the  latter  is  cut  in  swampy  soils  near  the  sea-coast.” 

. African  mahogany,  ( Swietenia  senegalensis.)  from  Gambia,  is  a more  recent  importation  ; it 
twists  much  more  than  either  of  the  above,  and  is  decidedly  inferior  to  them  in  all  respects,  except 
hardness.  It  is  a good  wood  for  mangles,  curriers’  tables,  and  other  uses  where  a hard  and  cheap 
wood  of  great  size  is  required : it  admits  of  being  turned  equally  as  well  as  the  others. 

African  mahogany  is  the  wood  of  Khaya  senegalensis,  a genus  very  closely  allied  to  the  Swietenia. 


WOODS,  VARIETIES  OF. 


945 


Mahogany  shrinks  but  little  in  drying,  and  twists  and  warps  less  than  any  other  wood  ; on 
which  account  it  is  used  for  founders’  patterns,  and  other  works  in  which  permanence  of  form  is  of 
primary  importance.  For  the  same  reason,  and  from  its  comparative  size,  abundance,  soundness, 
and  beauty,  it  is  the  most  useful  of  the  furniture  woods,  and  it  holds  the  glue  the  best  of  ali, 
Mahogany  is  also  used  for  a variety  of  turned  works,  apart  from  upholstery  and  cabinet-work. 
The  Spanish  mahogany  is,  in  general,  by  far  the  best,  although  some  of  the  Honduras  nearly  ap- 
proaches it,  except  in  hardness  and  weight.  The  African  is  by  no  means  so  useful  or  valuable  as 
either  of  the  above,  especially  as  it  alters  very  much  in  drying. 

There  are  two  other  species  of  Swietenia,  besides  the  mahogany-tree,  which  are  natives  of  the  East 
Indies:  the  one,  a large  tree  of  which  the  'wood  is  of  a dull  red  color,  and  remarkably  hard  ami 
heavy ; the  other  is  only  a middle-sized  tree,  the  wood  of  which  is  close-grained,  heavy,  and  dur- 
able, of  a deep  yellow  color,  and  much  resembles  boxwood  ; but  neither  of  these  species  is  in  com- 
mon use  in  this  country. — Tredgold. 

The  first  of  these  trees  was  formerly  referred  to  Swietenia,  but  is  now  Soymida  febrifuge/ ; the 
second  is  probably  Chloroxylon  Swietenia , which  is  the  satin-wood  of  India  and  Ceylon.  A 
third  species,  much  admired  for  its  light  color,  close  grain,  and  being  elegantly  veined,  is  the 
Chikrassee  of  the  natives,  and  Chikrassia  tabularis  of  botanists  : the  wood  is  much  employed 
in  making  furniture  and  cabinet-work. , The  wood  of  the  Toon-tree,  Cedrela  Toona,  is  some- 
times called  Indian  Mahogany. 

Maxchineel,  a large  tree  of  the  West  Indies  and  South  America;  the  wood  possesses  some  of  the 
general  characters  of  mahogany,  and  is  similarly  used,  but  it  is  much  less  common.  The  wood  is 
described  as  being  yellow-brown,  beautifully  clouded,  and  very  close,  hard,  and  durable.  It  is 
said  the  Indians  poison  their  arrows  with  its  juice,  and  that  the  wood-cutters  make  a fire  around 
it  before  felling  it,  to  cause  the  poisonous  sap  to  run  out,  to  avoid  injuring  their  eyes. 

This  has  been  accurately  described  in  Bancroft’s  Guiana,  p.  36-^1 : “ The  juice  of  this  tree  is  a 
deadly  poison ; it  bears  a little  apple  appearing  so  tempting,  that  many  new-comers  have  been 
poisoned  by  eating  it.  The  tree  is  poisonous  while  green  ; sleeping  under  it  has  been  said  to  have 
the  most  deadly  effect. 

Hippomane  Mancinella  is  the  Manchineel-tree  of  the  West  Indies.  Cameraria  lat  folia  is  called 
bastard  Mancliineel. 

Mangrove.  Native  woods  of  the  shores  of  the  tropics,  bearing  this  name,  and  those  of  Mango,  Mangle, 
Maniglier,  (Fr.)  &c.,  differ  very  much  in  kind:  some  bear  the  appearance  of  very  indifferent  ash 
and  elm,  others  of  good  useful  woods  of  the  same  kind,  some  are  dark-colored,  and  many  of  them 
have  the  red  mahogany  character. 

One  of  the  latter  kind  known  to  cabinet-makers  has  less  of  the  brown  and  more  of  the  red  tint 
than  mahogany ; it  becomes  darker  on  exposure,  but  not  in  general  as  much  so  as  mahogany. 
This  Mangrove  is  straight-grained,  hard,  and  elastic,  and  stands  better  than  Spanish  mahogany, 
and  it  is  therefore  preferred  for  straight  edges  and  squares. 

The  Mangrove-tree  is  Rhizopliora  Mangle,  of  which  the  wood  is  employed  in  making  staves 
for  sugar  hogsheads.  Growing  in  the  same  situations  with  it  are  two  trees  to  which  the  name 
mangrove  is  also  applied : the  Conocarpus  racemosa  is  called  the  white  Mangrove  by  Sloane, 
and  Avicennia  tomentosa,  olive  Mangrove.  Coccoloba  uvifera,  sea-side  grape,  also  grows  in 
the  same  situations,  and  is  a large  tree,  of  which  the  wood  is  of  a reddish  color. 

Maple  is  considered  to  be  allied  to  the  sycamore,  which  is  sometimes  called  the  great  maple,  (Acer 
Pseudo-platanus,)  or  the  plane-tree.  The  English,  or  common  maple,  is  of  this  kind ; its  color  is 
pale  yellow-brown. 

The  American  is  very  beautiful,  and  distinguished  as  bird’s-eye  maple  and  mottled  maple. 
The  latter  is  principally  used  for  picture-frames ; the  former  is  full  of  small  knots  that  give  rise 
to  its  name : the  grain  varies  accordingly  as  the  saw  has  divided  the  eyes  transversely  or  longi- 
tudinally, as  pieces  cut  out  in  circular  sweeps,  such  as  chair-backs,  sometimes  exhibit  both  the 
bird's-eye  and  mottled  figures  at  different  parts.  Much  sugar  is  made  from  this  variety  of  maple. 
The  common  maple  ( Acer  campestris ) is  very  much  used  for  house-carpentry  and  furniture. 

The  so-called  Russian  maple  is  considered  to  be  the  wood  of  the  birch-tree ; it  is  marked  in  a 
manner  similar  to  the  American  maple,  but  is  unlike  it,  inasmuch  as  there  are  little  stripes  that 
appear  to  connect  the  eyes,  which  in  the  American  are  quite  distinct,  and  arise  from  a different 
cause.  All  but  the  first  are  much  used  in  handsome  cabinet-work,  and  their  diversities  of  grain 
are  very  beautifully  shown  in  turned  works. 

Acer  campcstre  is  the  common  maple,  and  A.  platanoides  the  platanus-like  or  Norway  maple, 
while  A.  pseudo-platanus  is  the  great  maple,  sycamore,  or  mock  plane-tree.  A.  saccharinum 
is  the  sugar-maple,  and  its  wood  is  often  called  bird’s-eye  maple.  A.  rubrum,  circinatum, 
striatum,  and  eriocarpum,  are  other  American  species  of  which  the  timber  is  employed  and 
more  or  less  valued.  Acer  oblongum,  cultratum,  caudatum,  sterculiaceum,  and  v illosum,  are 
Himalayan  species,  of  which  the  timbers  may  be  employed  for  the  same  purposes. 

SIaracaybo  is  a furniture-wood  of  moderate  size,  as  hard  as  good  mahogany,  and  in  appearance  be- 
tween it  and  tulip-wood.  It  is  sometimes  called  Maracay bo-cedar,  but  it  has  no  resemblance  to 
the  cedar,  although  it  may  grow  in  the  vicinity  of  the  Bay  of  Maracaybo. 

Medlar-tree,  ( Mespilus  germanica :)  the  wood  is  white,  soft,  and  being  small,  is  not  much  used,  ex- 
cept for  walking-sticks. 

Micocoulier.  See  Nettle-tree. 

Mora-wood.  Specimens  of  the  Mora-tree  have  been  described  by  Mr.  Bentham  under  the  head  Mora 
excelsa ; the  tree  is  100  feet  high,  and  abundant ; the  wood  is  close-grained  like  teak,  and  superior 
to  oak,  esteemed  for  ship-building,  and  likewise  fitted  for  knees  from  the  branches  growing  crooked  ; 
in  color  ,t  resembles  moderately  red  mahogany. 

Vol.  II. (10 


WOODS,  VARIETIES  OF. 


946 


Mosatahiba.  See  Mustaiba. 

Mulberry-tree,  ( Morus ,)  consists  of  about  twenty  varieties,  of  which  the  yellow  fustic  is  one  that  is 
imported  in  considerable  quantities  from  Rio  de  Janeiro.  Bergeron  very  strongly  recommends 
the  white  mulberry,  which  he  describes  as  similar  to  elm,  but  very  close  in  the  grain,  and  suitable 
for  furniture.  He  says  the  white  is  greatly  superior  to  the  black  mulberry. 

Morns  nigra  is  the  black,  and  Morus  Alba  the  white  mulberry ; there  are  several  other  species 
of  which  the  wood  is  esteemed  for  its  toughness,  as  of  Morus  parvifolia  in  India,  for  hard- 
ness and  tenacity.  See  Fustic. 

Mustaiba,  from  the  Brazils  and  Rio  Janeiro,  is  imported  in  logs  about  1 by  10  in.,  also  in  planks;  it  is 
generally  of  an  inferior  rosewood  character,  but  harder,  and  is  sometimes  equally  good ; the  veins 
are  of  a chestnut  brown,  running  into  black.  In  its  grain  it  resembles  some  of  the  iron-woods  and 
black  partridge-wood ; it  has  fewer  resinous  veins  than  the  rosewoods.  Mosatahiba,  as  well  as 
lignum-vitse,  cocoa- wood,  Ac.,  is  used  at  Sheffield  for  the  handles  of  glaziers’  and  other  knives ; some 
of  the  better  kinds  are  very  good  for  turning,  as  the  wood  is  close,  sound,  and  heavy. 

Nettle-tree,  ( Celtis  australis.)  Micocoulier  of  the  French,  has  wood  that  is  compact,  between  oak  and 
box  for  density,  and  takes  a high  polish;  it  is  described  in  the  French  works  as  a heavy,  dark, 
close  wood,  without  bark,  very  durable  and  free  from  flaws.  It  is  said  to  be  used  for  flutes,  and 
for  carving ; it  is  also  called  bois  de  Perpignan. 

Nicaragua-wood,  a native  of  South  America,  is  imported  from  the  bay  of  Nicaragua,  and  also  from  St. 
Lucia,  Rio  de  la  Hache,  Mexico,  Ac.,  in  rough  groovy  logs  without  sap,  that  measure  from  2 to  9 
inches  through,  and  2 to  3 feet  long. 

Another  sort,  from  Lima,  Jamaica,  and  Peru,  called  by  the  dyers  Peachwood,  apparently  from 
the  color  for  which  it  is  used,  is  shipped  in  logs  sometimes  as  large  as  18  inches  diameter,  and  6 
feet  long.  Both  are  similar  to  Brazil-wood  in  color,  and  are  generally  too  unsound  for  turning. 

The  trees  yielding  Nicaragua  and  Peach  woods  have  not  been  yet  ascertained,  but  have  been 
supposed  to  be  species  of  Casa/pinia,  or  of  Hoematoxylon,  but  they  may  be  very  distinct,  as 
colored  woods  belong  to  other  genera. 

Nutueg-wood.  See  Palm. 

Qae,  ( Quercus .)  Of  this  valuable  timber  there  are  great  varieties.  Oak  of  good  quality  is  more  dura- 
ble than  any  other  wood  that  attains  the  same  size ; its  color  is  a well-known  brown.  Oak  is  a 
most  valuable  wood  for  ship-building,  carpentry,  frames,  and  works  requiring  great  strength  or 
exposure  to  the  weather ; also  for  the  staves  of  casks,  spokes  of  wheels  generally,  and  the  naves 
of  wagon-wheels,  for  tree-nails,  and  numerous  small  works.  The  red  varieties  are  inferior,  and  are 
only  employed  for  ornamental  furniture. 

The  English  oak  is  one  of  the  hardest  of  the  species;  it  is  considerably  harder  than  the  Ameri- 
can, called  white  and  red  oak,  or  than  the  wainscot  oak  from  Memel,  Dantzic,  and  Riga ; the  latter, 
which  are  the  more  interspersed  with  the  ornamental  markings  or  flower,  from  the  septa  or  me 
dullary  rays  in  the  wood,  are  the  least  suitable  as  timber. 

The  wainscot  oak  of  Norway  is  remarkably  straight,  and  splits  easily ; so  much  so,  that  it  is  the 
practice  of  the  country  to  bore  a small  hole  in  the  top  of  the  tree  at  the  beginning  of  the  winter, 
and  to  fill  it  with  water,  the  expansion  of  which  in  freezing  rends  the  tree  from  top  to  bottom. 

The  live  oak  is  a fine  tree,  that  is  met  with  in  the  Southern  States  ; it  is  very  different  in  ap- 
pearance from  the  others,  as  the  veins  are  small,  and  more  evenly  distributed  throughout  the 
wood ; it  is  used  in  this  country,  along  with  the  North  American  red  cedar,  for  our  finest  ships ; it 
is  considered  to  be  durable  when  dry,  but  not  when  exposed  to  wet. 

“ The  sea  air  seems  essential  to  its  existence,  for  it  is  rarely  found  in  the  forests  upon  the  main- 
land, and  never  more  than  15  or  20  mile9  from  the  shore.”  “ The  live  oak  is  commonly  40  or  50 
feet  in  height,  and  from  1 to  2 feet  in  diameter,  but  it  is  sometimes  much  larger.” 

There  is  also  a fine  evergreen  oak  in  the  Cordilleras  of  the  Andes. 

The  African  oak  is  well  adapted  to  the  construction  of  merchant  vessels,  but  it  is  apt  to  sjrlinter 
when  struck  by  shot ; it  is  therefore  less  used  for  ships  of  war.  They  are  all  softened  by  steaming, 
and  are  then  much  more  easily  cut  or  bent ; the  African  bends  less  than  the  others,  and  is  the 
darkest  in  color,  but  it  has  not  the  silver  grain  nor  the  variegated  appearance  of  the  others  : it  is 
sometimes  called  Teak,  (which  see.) 

Of  the  British  oak  there  are  two  distinct  species  according  to  modern  botanists.  The  Quercus 
Pobur,  sometimes  called  pedunculata,  has  acorns  which  are  supported  on  long  footstalks  or 
peduncles ; this  timber  is  considered  by  some  superior  to  that  of  the  other  species  Q.  sessili- 
flora,  but  this  probably  depends  on  situation,  as  the  strength  and  toughness  of  this  kind,  as 
well  as  its  durability,  have  been  proved  to  be  great.  Dr.  Lindley  says  its  wood  may  be 
known  by  its  medullary  rays  or  silver  grain  being  so  far  apart  that  it  cannot  be  rent,  and  this 
gives  it  quite  a peculiar  aspect. 

Quercus  Ilex,  the  evergreen  or  holm  oak,  is  common  to  the  South  of  Europe  ; the  wood  is  hard, 
heavy,  and  tough.  Q.  Suber  is  the  cork-tree.  Q.  Cerris,  called  the  Turkey  oak,  is  common 
in  the  southeast  of  Europe ; its  timber  is  ornamental,  being  beautifully  mottled,  in  conse- 
quence of  the  abundance  of  its  silvery  grain,  and  is  supposed  to  be  often  as  good  as  any  other ; 
the  Sardinian  oak  is  apparently  produced  by  it.  The  Wainscoat  oak  is  supposed  by  some  to 
be  produced  by  Q.  Cerris.  Dr.  Lindley  considers  it  to  be. a variety  of  Q.  sessilijlora,  grown 
fast  in  rich  oak  land.  Q.  hispanica,  the  Spanish  oak,  and  Q.  austriaca,  the  Austrian  oak,  are 
found  in  the  countries  from  which  they  are  named ; and  Q.  MDyilops  is  the  Valonia  oak 
abounding  in  Greece  and  Asia  Minor,  from  which  countries  such  large  quantities  of  its  acorns 
are  imported  into  England.  Q.  Crini/a  is  common  in  Asia  Minor,  yields  excellent  timber,  and 
is  employed  by  the  Turks  in  naval  architecture. 

The  American  oaks  are  numerous,  but  the  timber  of  Quercus  alba , or  the  white  oak,  comes  near 


WOODS,  VARIETIES  OF. 


947 


est  to  the  English  oak,  and  is  largely  exported  to  England  as  'well  as  to  the  West  Indies. 
Q.  virens,  the  live  oak,  is  confined  to  the  southern  of  the  United  States,  and  is  also  found  in 
Texas ; it  is  said  to  yield  the  best  oak  in  America,  the  timber  being  heavy,  compact,  and  fine- 
grained. 

Q.  tinctoria,  dyers’  or  black  oak,  is  best  known  from  its  inner  bark  being  used  as  a yellow  dye, 
under  the  name  of  Quercitron ; its  wood  is  strong,  but  coarse.  The  other  American  oaks  are 
inferior  in  the  quality  of  their  timber.  Besides  these  there  are  Indian  and  Himalayan  oaks  : 
rue  timber  of  some  of  the  latter  is  excellent  in  quality. 

The  African  oak,  or  Teak,  as  it  is  also  called,  is  not  a species  of  Quereus,  V.  Teak. 

Olive-wood,  principally  imported  from  Leghorn,  is  the  wood  of  the  fruit-tree,  (Olea  europea ;)  it  is  much 
like  box,  but  softer,  with  darker  gray-colored  veils.  The  roots  have  a very  pretty  knotted  and 
curly  character ; they  are  much  esteemed  on  the  Continent  for  making  embossed  boxes,  pressed 
into  engraved  metallic  moulds. 

There  is  another  wood,  apparently  from  South  America,  called  Olive-wood,  but  it  does  not  agree 
in  color,  either  with  the  fruit  or  wood  of  the  olive-tree,  but  is  of  a greenish  orange,  with  broad 
stripes  and  marks  of  a darker  brown  tint ; it  is  a handsome  wood  for  turning,  but  not  very  hard. 

Elmodendron  glaucum  is  called  bois  d'olive,  but  there  is  no  proof  that  it  yields  the  olive-wood 
alluded  to,  as  the  country  from  which  this  is  imported  is  not  distinctly  known. 

Omander.  See  Coromandel. 

Orange-tree.  The  orange,  lemon,  and  lime  trees,  (Citrus,)  are  evergreens  that  seldom  exceed  about 
15  feet  in  height.  The  wood  is  only  met  with  as  an  object  of  curiosity:  it  is  of  a yellow  color, 
but  devoid  of  smell.  See  Apricot-tree. 

The  orange  is  Citrus  Aurantium , the  lemon  C.  Lhnonum,  the  lime  C.  Lbnetta,  and  the  citron 
C.  Medica. 

Palm-trees.  Several  varieties  of  the  four  or  five  hundred  which  are  said  to  exist  are  imported  from 
the  East  and  West  Indies:  they  are  known  by  the  names  palm,  palmetto,  palmyra,  and  nutmeg, 
leopard,  and  porcupine  wood,  <fcc.,  from  their  fancied  resemblances,  as  when  they  are  cut  horizon- 
tally they  exhibit  dots  like  the  spice,  and  when  obliquely,  the  markings  assimilate  to  the  quills  of 
the  porcupine. 

The  trunks  of  the  palms  are  not  considered  by  physiological  botanists  to  be  true  wood ; they  all 
grow  from  within,  and  are  always  soft  and  spongy  in  the  centre,  but  are  gradually  harder  towards 
the  outside : they  do  not  possess  the  medullary  rays  of  the  proper  woods,  but  only  the  vertical 
fibres,  which  are  held  together  by  a much  softer  substance,  like  pith  or  cement,  so  that  the  hori- 
zontal section  is  always  dotted,  by  which  they  may  be  readily  distinguished  from  all  true  woods. 

The  Areca  Catechu,  or  betle-nut  palm,  is  remarkably  perpendicular ; it  grows  to  the  height  of 
about  30  feet,  and  rarely  exceeds  4 or  5 inches  diameter ; it  bears  a small  tuft  of  leaves,  and  the 
fruit  is  in  clusters  like  grapes.  The  betle-nut  is  chewed  by  the  Indians  along  with  quicklime,  and 
the  leaf  of  the  Piper  Betle,  in  the  manner  of  tobacco.  The  general  color  of  the  wood  is  a light 
yellow-brown ; the  fibres  are  large,  hard,  and  only  a few  shades  darker  than  the  cementitious 
portions. 

The  Cocos  nucifera,  or  cocoanut  palm,  flourishes  the  best  in  sandy  spots  near  the  sea-beach,  and 
sometimes  grows  to  90  feet  in  height  and  3 feet  in  diameter,  but  is  generally  less ; it  is  rarely 
quite  straight  or  perpendicular,  and  has  broad  pendent  leaves  from  12  to  14  feet  long,  in  the  midst 
of  which  is  a sort  of  cabbage,  which,  as  well  as  the  fruit,  the  cocoanut,  is  eaten ; the  husk  of  the 
nut  supplies  the  material  for  coir-rope  and  matting.  No  part  of  this  interesting  tree  is  without  its 
grateful  service  to  the  Indian  : the  leaves  are  used  for  making  baskets,  mats,  and  the  covering  of 
his  dwelling ; he  also  obtains  from  this  tree  oil,  sugar,  palm-wine,  and  arrack ; and  although  the 
upper  part  of  the  trunk  is  soft  and  stringy,  the  lower  supplies  a useful  wood,  the  fibres  of  which 
are  of  a chestnut  brown,  and  several  shades  darker  than  the  intermediate  substance  ; the  wood  is 
employed  for  joists,  troughs  for  water,  and  many  purposes  of  general  carpentry.  The  Asiatic  So- 
ciety has  specimens  marked  male,  1st,  2d,  3d,  4th  sorts,  and  the  same  number  of  female  varieties  ; 
no  material  distinction  is  observable  between  them. 

The  Niepere  palm  is  much  darker  than  either  of  the  preceding  kinds  ; the  fibres  are  nearly  black 
and  quite  straight,  and  the  cement  is  of  a dark  brown,  but  in  other  varieties  with  these  black  fibres, 
the  softer  part  is  very  light-colored,  and  so  friable  that  it  may  be  picked  out -with  the  fingers  ; at 
the  Isthmus  of  Darien,  they  use  the  fibres  of  some  of  the  palms  as  nails  for  joinery-work. 

Palmyra-wood,  or  that  of  Borassus  Jlabelliformis,  says  Mr.  Laird,  is  largely  imported  into  Madras 
and  Pondicherry,  from  the  Jaffna  district  at  the  northern  part  of  Ceylon,  for  the  construction  of  flat 
roofs,  the  joists  of  which  consist  of  two  slabs,  the  third  or  fourth  part  of  the  tree,  bolted  together 
by  their  flat  sides  so  as  to  constitute  elliptical  rafters.  They  are  covered  first  with  flat  tiles,  and 
then  with  a white  concrete  called  Clvunam,  consisting  of  shell-lime,  yolks  of  eggs,  and  Jaggree, 
(sugar,)  beaten  together  with  water  in  which  the  husks  of  cocoanuts  have  been  steeped. 

The  prickly  pole  ( Cocos  guianensis ) of  Jamaica,  tfec.,  a palm  growing  40  feet  high,  and  of  small 
diameter,  is  said  to  be  very  elastic,  and  fit  for  bows  and  rammers. 

The  smaller  kinds  are  imported  under  the  names  of  Partridge  canes,  (called  also  Chinese  or 
fishing  canes,)  Penang  canes  from  the  island  of  that  name,  together  with  some  other  small  palms 
which  are  used  for  walkiDg-sticks,  the  roots  serving  to  form  the  knobs  or  handles  The  knobs  of 
these  sticks  exhibit  irregular  dots  something  like  the  scales  of  snakes ; these  arise  from  the  small 
roots  proceeding  from  the  principal  stem,  which  latter  shows  dotted  fibres  at  each  end  of  the  stick, 
and  streaks  along  the  side  of  the  same. 

The  twisted  palm  sticks  are  the  central  stems  or  midribs  of  the  leaves  of  the  date  palm;  they 
are  twisted  when  green,  and  stretched  with  heavy  weights  until  they  are  thoroughly  dry  : thej 
are  imported  from  the  Neapolitan  coast,  but  arc  considered  to  be  produced  in  Egypt. 


948 


WOODS,  VARIETIES  OF. 


The  bamboos,  •which  like  the  palms  are  endogens,  are  used  in  India  and  China  for  almost  even 
purpose  in  the  arts  ; amongst  others,  in  working  iron  and  steel,  as  the  bamboo  is  preferred  as  fuel 
in  this  art : the  large  pieces  serve  as  the  blowing  cylinders,  the  small  as  the  blast-pipe,  and  also 
when  combined  with  a cocoanut-shell  constitutes  the  hookah  of  the  artisan.  The  bamboos,  and 
several  of  the  solid  canes,  are  used  as  walking-sticks,  and  for  umbrella  and  parasol  sticks. 

The  shells  of  the  cocoanut  and  coquilla-nut,  and  the  kernels  of  the  areca  or  betle-nut,  and  those 
of  the  corosos  or  ivory-nut,  have  likewise  their  uses  in  our  workshops. 

Palisander,  a name  used  in  Europe  for  rosewood. 

There  is  considerable  irregularity  in  the  employment  of  this  name;  ii^tlie  work  of  Bergeron  a 
kind  of  striped  ebony  is  figured  as  hois  de  Palixandre ; in  other  French  works  this  name  is 
considered  a synonym  of  hois  violet,  and  stated  as  a w’ood  brought  by  the  Dutch  from  their 
South  American  colonies,  and  much  esteemed. 

Partiudge-wood  is  the  produce  of  the  Brazils  and  the  West  Indian  Islands  ; it  is  sent  in  large  planks, 
or  in  round  and  square  logs,  called  from  their  tints  red,  brown,  and  black,  and  also  sweet  partridge ; 
the  wood  is  close,  heavy,  and  generally  straight  in  the  grain.  The  colors  are  variously  mingled, 
and  most  frequently  disposed  in  fine  hair-streaks  of  two  or  three  shades,  which  in  some  of  the  curly 
specimens  cut  plankways  resemble  the  feathers  of  the  bird  ; other  varieties  are  called  piheasant- 
wood.  The  partridge-woods  are  very  porous ; cut  horizontally  the  annual  rings  appear  almost  as 
two  distinct  layers,  the  one  hard  woody  fibre,  the  other  a much  softer  substance  thickly  interspersed 
with  pores : this  circumstance  gives  rise  to  its  peculiar  figure,  which  often  resembles  that  of  the 
palm-tree  woods. 

Partridge-wood  was  formerly  employed  in  the  Brazils  for  ship-building,  and  is  also  known  as 
cabbage-wood : the  red-colored  variety  is  called  Angelim  and  Cangelim  in  the  Brazils,  and  Yava 
in  Cuba. 

It  is  now  principally  used  for  walking-sticks,  umbrella  and  parasol  sticks,  and  in  cabinet-work 
and  turning  ; the  ladies  have  patronized  it  also  for  fans. 

The  partridge-wood  imported  from  the  West  Indies  is  yielded  by  Heisteria  coccinea.  The  wood 
of  several  trees  is  no  doubt  included  under  this  name. 

Peachwood.  See  Nicaragua-wood. 

Pear-tree  ( Pyrus  communis)  is  a native  of  Europe.  The  wild  trees  are  principally  used,  and  they 
may  be  obtained  from  7 to  Id  inches  diameter.  The  color  is  a light  brown,  approaching  that  of 
pale  mahogany  or  cedar,  generally  less  red  than  the  apple-tree ; and  it  is  esteemed  a very  good 
wood  for  carving,  as  it  cuts  with  nearly  equal  facility  in  all  directions  of  the  grain,  and  many  of 
the  old  works  are  cut  in  it.  It  is  now  much  used  for  the  engraved  blocks  for  calico-printers,  paper- 
stainers,  and  pastry-cooks  ; it  does  not  stand  very  well,  unless  it  is  exceedingly  well  seasoned. 

Some  pieces  of  pear-tree  much  resemble  lime-tree  from  being,  in  the  language  of  the  workmen, 
“ without  grain,”  but  the  pear-tree  is  harder  and  tougher,  and  has  a few  darker  streaks  : they  are 
used,  however,  for  similar  purposes. 

Pernambouca.  See  Brazil-wood. 

Peruvian-wood,  a fine  sound  wood  so  called,  is  of  a rosewood  character,  and  measures  about  12  to  16 
inches  through  ; it  is  harder,  closer,  and  lighter  in  color  than  rosewood,  with  a straighter  distribu- 
tion of  its  dark  red-brown  and  black  veins ; it  has  no  scent.  Its  true  name  and  locality  are  unknown. 

Pigeon-wood.  See  Zebra-wood. 

Pines>  and  Firs  ( Pinus ) constitute  a very  numerous  family  of  cone-bearing  timber-trees,  that  thrive  the 
best  in  cold  countries.  The  woods  differ  somewhat  in  color,  partly  from  the  greater  or  less  quantity 
of  resinous  matter  or  turpentine  contained  in  their  pores,  which  gives  rise  to  their  popular  distinc- 
tions, red,  yellow,  and  white  firs  or  deals,  and  the  red,  yellow,  and  white  spruce,  or  pitch  pines, 
and  larches.  They  are  further  distinguished  by  the  countries  in  which  they  grow,  or  the  parts 
from  whence  they  are  shipped,  as  Norway,  Baltic,  Memel,  Riga,  Dantzic,  and  American  timber,  Ac. 

The  general  characters  of  the  wood,  and  its  innumerable  uses  besides  those  of  ship  and  house 
carpentry,  are  too  generally  known  to  call  for  any  description  in  this  place ; but  those  who  may 
require  it  will  find  abundant  information  in  Tredgold’s  Carpentry,  pages  208  to  218.  The  Swiss 
pine,  imported  under  the  name  Belly-boards,  are  used  for  the  sounding-boards  of  musical  instruments 
The  larch  is  particularly  durable,  from  the  quantity  of  turpentine  it  contains ; it  has  of  late  been 
considerably  employed  for  naval  architecture,  as  likewise  the  Hackmetack  larch : larch  is  consid- 
ered the  best  wood  for  the  sleepers  of  railways ; its  bark  is  also  used  for  tanning.  The  American 
pitch-pine  is  likewise  exceedingly  durable,  and  is  much  used  for  flooring.  The  white  hemlock 
contains  very  little  turpentine,  and  is  remarkably  free  from  knots  : it  is  sometimes  from  2 to  3 feet 
square,  and  60  to  70  feet  long,  and  is  suitable  for  piling,  the  staves  of  dry  casks,  Ac. ; it  stands 
extremely  well. 

The  Cowdie,  Kaurie,  or  New  Zealand  Pine,  or  Dammar  a australis,  is  the  most  magnificent  of  the 
coniferous  woods,  although  not  a true  pine.  It  is  said  to  grow  from  -4  to  12  feet  diameter ; one  that 
had  been  blown  down  by  the  wind  was  found  to  measure  upwards  of  1 70  feet.  The  Norfolk  Island 
pine,  Araucaria  excclsa,  has  enormous  knots. 

In  Norway,  when  they  desire  to  procure  a hard  timber  with  an  overdose  of  turpentine,  they  riug 
the  bark  of  the  branches  just  before  the  return  of  the  sap ; the  next  year  they  ring  the  upper  part 
of  the  stem  ; the  third  year  the  central,  and  lastly,  the  lower  part  near  the  ground.  By  these 
means  the  sap  or  turpentine  is  progressively  hindered  from  returning,  and  it  very  much  increases 
the  solidity  and  durability  of  the  timber.  The  roots  of  some  of  the  red  deals  so  abound  in  turpentine, 
that  the  Scottish  Highlanders,  the  natives  of  the  West  Indies,  and  of  the  Himalayas,  use  splinters 
of  them  as  candles.  The  knots  of  deal,  especially  white  deal,  are  particularly  hard  ; they  are 
altogether  detached  from  the  wood  in  the  outer  planks,  and  often  fall  out  when  exposed  in  thin 
boards. 


WOODS,  VARIETIES  OF. 


949 


The  pines  and  firs  being  so  numerous,  and  the  timbers  of  many  being  known  in  commerce  by  such 
a variety  of  names,  it  is  difficult  to  ascertain  the  trees  which  yield  them. 

The  Finns  sylvestris,  however,  called  the  wild  pine,  or  Scotch  fir,  yields  the  red  deal  of  Riga, 
called  yellow  deal  in  London ; Abies  excelsa,  or  Norway  spruce  fir,  yields  white  deal,  Abies 
picea,  or  silver-fir,  has  whitish  wood,  much  used  for  flooring ; Larix  europea  is  the  larch  commoD 
on  the  Alpine  districts  of  Germany,  Switzerland,  and  Italy.  Several  other  pines,  as  P.  Pinaster , 
Pinea,  Cembra,  austriaca  and  pyrenaica,  are  found  in  the  south  of  Europe,  but  their  timber  is 
less  known  in  commerce. 

The  North  American  pines,  P.  strobus,  or  Weymouth  pine,  called  white  pine  in  North 
America,  and  much  used  throughout  the  Northern  States  ; P.  mitis  or  lutea,  the  yellow  pine, 
is  chiefly  employed  in  the  Northern  and  Middle  States  for  house  and  ship  building ; it  is  con- 
sidered next  in  durability  to  P.  australis,  Southern  pine,  called  also  P.  palustris,  and  yellow 
pine,  pitch  pine,  and  red  pine  in  different  districts : it  is  said  to  form  four-fifths  of  the  houses 
in  the  Southern  States,  and  to  be  preferred  for  naval  architecture.  Its  timber  is  exported  to 
the  West  Indies  and  to  Liverpool,  where  it  is  called  Georgia  pitch-pine.  Pinus  tecda,  frank- 
incense pine,  called  w'hite  pine  in  Virginia ; P.  rigida,  Virginian  or  pitch-pine ; P.  banksiana, 
Hudson’s  Bay  or  Labrador  pine ; P.  inops,  Jersey  or  poor  pine,  and  P.  resinosa.  The  American 
pitch-pine  or  red  pine,  called  Norway  pine  in  Canada,  and  yellow  pine  in  Nova  Scotia,  and 
many  others,  yield  deals  of  various  qualities,  more  or  less  used  in  different  districts. 

The  American  spruce  firs  are  the  Abies  alba,  nigra,  and  rubra,  the  white,  black,  and  red 
spruce  firs;  the  last  is  sometimes  called  Newfoundland  red  pine,  and  employed  in  ship- 
building; botli  it  and  the  black  pine  are  exported  to  England;  Abies  canadensis,  hemlock 
spruce  fir,  and  A.  balsamea,  balm  of  Gilead  fir,  are  also  employed,  although  less  valued  foi 
their  timber,  but  the  American  larch,  Larix  americana,  is  much  esteemed.  On  the  west  coasl 
of  America  some  magnificent  pines  have  been  discovered,  as  P.  Douglasii  and  Lambertiana 
and  others  in  Mexico.  In  the  southern  hemisphere  the  Cowdie  pine  or  New  Zealand  pitch- 
tree,  Dammara  australis,  considered  so  valuable  for  masts,  belongs  to  the  same  genus  as  the 
Dammar- tree,  D.  Orientalis.  The  Himalayas  abound  in  true  pines  : a splendid  species  is  the 
Finns  Dcodara  already  mentioned  under  Cedar ; so  also  are  Pinus  excelsa,  Khutrow  longifolia, 
with  Abies  Webbiana,  Findrow,  and  others. 

Pi-ane-tree,  (the  Platanus  occidentalism)  a buttonwood-tree,  is  a native  of  North  America ; it  is  abun- 
dant on  the  banks  of  the  Mississippi  and  Ohio.  This,  perhaps  one  of  the  largest  of  the  American 
trees,  is  sometimes  12  ft.  in  diameter;  it  is  much  used  in  the  Western  States.  .The  color  of  the 
wood  resembles  beech,  but  it  is  softer.  The  American  variety  is  sometimes  called  water-beech 
and  sycamore.  Plane-tree  is  used  for  musical  instruments  and  other  works  requiring  a clean 
light-colored  wood. 

The  Platanus  orientalis,  called  also  lacewood,  is  a native  of  the  Levant,  and  other  Eastern 
countries ; it  is  smaller,  softer,  and  more  ornamental  than  the  above ; the  beauty  of  its  septa  gives 
it  the  damasked  appearance  from  which  it  is  sometimes  named.  It  is  commonly  used  by  the 
Persians  for  their  doors,  windows,  and  furniture,  and  is  suitable  to  ornamental  cabinet-work  and 
various  kinds  of  turnery.  The  first  kind  also  has  septa,  but  they  are  smaller. 

The  true  lacewood-tree  is  the  Daphne  Lagetta. 

Plum-tree,  ( Prunus  domestica  and  F.  spinosa)  Europe,  similar  in  general  character  to  pear-tree,  is 
used  principally  in  turning.  This  is  a handsome  wood  : in  the  endway  of  the  grain  it  resembles 
cherry-tree,  but  the  old  trees  are  of  a more  reddish-brown,  with  darker  marks  of  the  same  color. 
It  begins  to  rot  in  small  holes  more  generally  away  from,  rather  than  in  the  centre  of  the  tree,  and 
it  is  very  wasteful  on  that  account. 

Poon-wood,  or  Peon-wood,  of  Singapore,  is  of  a light  porous  texture,  and  light-grayish  cedar  color ; it  is 
used  in  ship-building  for  planks,  and  makes  excellent  spars.  The  Calcutta  poon  is  preferred. 

Calophyllwn  inophyllum  is  called  Poona  in  the  peninsula  of  India,  and  C.  angusti folium,  Dr. 
Roxburgh  says,  is  a native  of  Penang  and  of  countries  eastward  of  the  Bay  of  Beugal,  and 
that  it  yields  the  straight  spars  commonly  called  Poon,  and  which  in  those  countries  are  used 
for  the  masts  of  ships. 

Pkixces-wood,  from  Jamaica,  is  generally  sent  in  logs  like  cocoa-wood,  from  4 to  I in.  diameter,  and  4 
to  5 ft.  long ; it  is  a light-veined  wood,  something  like  West  India  satin-wood,  but  of  a browner 
cast ; the  sapwood  resembles  dark  birchwood.  It  is  principally  used  for  turning. 

The  Princes-wood  of  Jamaica,  called  also  Spanish  elm,  is  L'ordia  Gerascanthus,  but  the  above 
appears  to  be  different. 

PorLAR,  ( Fopulus .)  The  woods  are  soft,  light,  easy  to  work,  suited  to  carving,  common  turnery,  and 
works  not  exposed  to  much  wear.  It  is  considered  to  be  very  durable  when  kept  dry,  and  it  does 
not  readily  take  fire.  The  bark  of  white  poplar  is  almost  as  light  as  cork. 

The  wooden  polishing-wheels  of  the  glass-grinder  are  made  out  of  horizontal  slices  of  the  entire 
stem,  about  one  inch  thick,  as  from  its  softness  it  readily  imbibes  the  polishing  materials. 

The  wood  of  the  Abele,  or  white  poplar,  is  also  commonly  known  as  Ars  ; it  is  extensively  used 
m Europe  for  toys  and  common  turnery,  and  is  frequently  of  a uniform  reddish  color,  like  red  deal, 
but  with  very  small  veins. 

Populus  alba  is  the  white  poplar  or  Abele,  P.  canescens  the  gray  or  common  white,  L\  Tremida 
is  the  aspen,  and  P.  pyramidalis  or  fasligiata,  the  Lombardy  poplar.  There  are  other  species 
in  North  America  and  the  Himalayas. 

Prize-wood.  A large  ill-defined  wood,  from  the  Brazils,  apparently  of  the  cocus-wood  kind,  but  lighter, 
arid  generally  of  reddish  color. 

Purple-heart  is  mentioned  by  Dr.  Bancroft,  (see  Grccuhcart ;)  it  is  perhaps  the  more  proper  name  for 
the  wood  next  described. 


950 


WOODS,  VARIETIES  OF. 


Purple-wood,  or  Amaranthus,  from  the  Brazils,  is  imported  in  logs  from  8 to  12  in.  square  and  8 te 
10  ft.  long,  or  in  planks:  its  color  is  dark  gray  when  first  cut,  but  it  changes  rapidly,  and  ulti- 
mately becomes  a dark  purple. 

Varieties  of  Kingwood  are  sometimes  called  purple  and  violet  woods:  these  are  variegated : 
but  the  true  purple-wood  is  plain,  and  principally  used  for  ramrods,  and  occasionally  for  buhl- 
work,  marquetry,  and  turning.  A few  logs  of  purple-wood  are  often  found  in  importations  ol 
Kingwood ; it  is  probable  also  that  the  purple-heart  is  thus  named  occasionally. 

Quassia- wood.  The  quassia-tree  is  a beautiful  tall  tree,  of  North  and  South  America  and  the  West 
Indies.  The  wood  is  of  a pale  yellow,  or  light  brown,  and  about  as  hard  as  beech ; its  taste  is 
intensely  bitter,  but  the  smell  is  very  agreeable ; the  wood,  bark,  and  fruit  are  all  medicinal. 

“ This  wood  is  well  known  in  the  Isthmus  of  Darien,  and  is  invariably  carried  by  all  the  natives 
as  a ‘ contra’  against  the  bite  of  venomous  snakes ; it  is  chewed  in  small  slices,  and  the  juice  is 
swallowed.” — Col.  G.  A.  Lloyd. 

Quassia  amara,  is  a small  tree  ; Simaruba  amara  is  the  Mountain  damson  of  the  West  Indies, 
and  Picrama  excelsa,  the  lofty  Bitter- wood.  All  have  a similarly  colored  wood,  which  is 
intensely  bitter 

Queenwood,  from  the  Brazils,  a term  applied  occasionally  to  woods  of  the  Greenheart  and  Cocoa- 
wood  character. 

Quince-tree,  {Cydonia  vulgaris.)  See  Apricot-tree. 

Red  Gumwood.  See  Gumwood. 

Red  Saunders,  or  Ruby-wood,  an  East  Indian  wood,  the  produce  of  Pterocarpus  santalinus,  is  prin- 
cipally shipped  from  Calcutta  in  logs  from  2 to  10  in.  diameter,  generally  without  sap,  and  some- 
times in  roots  and  split  pieces ; it  is  very  hard  and  heavy  ; it  is  very  much  used  as  a red  dye- 
wood,  and  often  for  turning.  The  logs  are  often  notched  at  both  ends,  or  cut  with  a hole  as  for 
a rope,  and  much  worn  externally  from  being  dragged  along  the  ground ; other  woods,  and  also 
the  ivory  tusks,  are  sometimes  perforated  for  the  like  purpose. 

The  wood  of  Adenanthera  pavonia  (see  Coral-wood)  is  similar  in  nature,  and  sometimes  con- 
founded with  the  red  saunders. 

Rosetta-wood  is  a good  sized  East  Indian  wood,  imported  in  logs  9 to  14  in.  diameter ; it  is  hand- 
somely veined  ; the  general  color  is  a lively  red-orange,  (like  the  skin  of  a Malta  orange,)  with 
darker  marks,  which  are  sometimes  nearly  black;  ths  wood  is  close,  hard,  and  very  beautiful 
when  first  cut,  but  soon  gets  darker. 

Rosewood  is  produced  in  the  Brazils,  the  Canary  Isles,  the  East  Indies,  and  Africa.  It  is  imported 
in  very  large  slabs,  or  the  halves  of  trees  which  average  18  inches  wide.  The  best  is  from  Rio 
de  Janeiro,  the  second  quality  from  Bahia,  and  the  commonest  from  the  East  Indies:  the  latter 
is  called  East  India  blackwood,  although  it  happens  to  be  the  lightest  and  most  red  of  the  three  ; 
it  is  devoid  of  the  powerful  smell  of  the  true  rosewood,  which  latter  Dr.  Lindley  considers  to  be 
a species  of  Mimosa.  The  pores  of  the  East  India  rosewood  appear  to  contain  less  or  none  of 
the  resinous  matter,  in  which  the  odor,  like  that  of  the  flower  Acacia  armata,  arises.  Rosewood 
contains  so  much  gum  and  oil,  that  small  splinters  make  excellent  matches. 

The  colors  of  rosewood  are  from  light  hazel  to  deep  purple,  or  nearly  black : the  tints  are 
sometimes  abruptly  contrasted,  at  other  times  striped  or  nearly  uniform.  The  wood  is  very  heavy  ; 
some  specimens  are  close  and  fine  in  the  grain,  whereas  others  are  as  open  as  coarse  mahogany, 
or  rather  are  more  abundant  in  veins : the  black  streaks  are  sometimes  particularly  hard,  and 
very  destructive  to  the  tools. 

Next  to  mahogany,  it  is  the  most  abundant  of  the  furniture  woods;  a large  quantity  is  cut 
into  veneers  for  upholstery  and  cabinet-work,  and  solid  pieces  are  used  for  the  same  purposes, 
and  for  a great  variety  of  turned  articles  of  ordinary  consumption. 

In  the  Brazils,  the  ordinary  rosewood  is  called  Jacaranda  Cabuna ; there  is  a sort  which  is 
much  more  free  from  resinous  pores, that  is  called  Cabuna  only : and  a third  variety,  Jacaranda 
Tam,  is  of  a pale  red,  with  a few  darker  veins ; it  is  close,  hard,  and  very  free  from  resinous  veins ; 
its  colors  more  resemble  those  of  tulip-wood. 

Mr.  Edwards  says,  that  “ at  the  time  when  rosewood  was  first  imported  into  England,  there 
was  on  the  scale  of  Custom-house  duties,  ‘ Lignum  Rhodium,  per  ton,  £40,’  referring  to  the  wood 
from  which  the  ‘ oil  of  Rhodium’  was  extracted,  which  at  that  time  realized  a very  high  price. 
The  officers  claimed  the  like  duty  on  the  furniture  rosewood;  it  was  afterwards  imported  as 
Jacaranda,  Palisander,  and  Palaxander-wood,  by  which  names  it  is  still  called  in  Europe.  The 
duty  was  first  reduced  to  six  guineas,  then  in  1842  to  one  pound,  and  in  1845  the  duty  was  en- 
tirely removed ; the  consumption  has  proportionately  increased.  It  is  now  only  known  as  rose- 
wood, some  logs  of  which  have  produced  as  much  as  £150,  when  cut  into  veneers.” 

Rosewood  is  a term  as  generally  applied  as  iron-wood,  and  to  as  great  a variety  of  plants  in 
different  countries,  sometimes  from  the  color  and  sometimes  from  the  smell  of  the  woods. 
The  rosewood  which  is  imported  in  such  large  quantities  from  Bahia  and  Rio  Janeiro,  called 
also  Jacaranda,  is  so  named  according  to  Prince  Maximilian,  as  quoted  by  Dr.  Lindley,  be- 
cause when  fresh  it  has  a faint  but  agreeable  smell  of  roses,  and  is  produced  by  a Mimosa 
in  the  forests  of  Brazil.  Mr.  D.  Loddiges  informs  us  it  is  the  Mimosa  Jacaranda. 

The  rosewood,  or  candle-wood,  of  the  West  Indies,  is  Amyris  balsamifera  according  to 
Browne,  and  is  also  called  Sweetwood,  while  Amyris  montan  a is  called  Yellow  candle- 
wood,  or  rosewood,  and  also  yellow  saunders.  Other  plants  to  which  the  name  is  also  ap- 
plied, are  Licaria  guianensis  of  Aublet,  Erythroxylurn  areolatum,  Colliguaya  odorifsra, 
Molina,  Ac. 

The  rosewood  of  New  South  Wales  is  Trichilia  r/landulosa  ; that  of  the  East  Indies,  if  flu 
same  as  what  is  there  called  Blackwood,  is  Dalbergia  latifolia. 


WOODS,  VARIETIES  OF. 


95  i 


The  lignum  rhodium  of  the  ancients,  from  which  the  oil  of  the  same  name  and  having  the  odor 
of  roses  was  prepared,  has  not  yet  been  ascertained  ; it  has  been  supposed  to  be  the  Genista 
canariensis,  and  by  others,  Convolvulus  scoparius. 

Ruby-wood.  See  Red  Saunders. 

Sallow  ( Salix  caprea)  is  white,  with  a pale-red  cast,  like  red  deal,  but  without  the  veins.  The 
wood  is  soft,  and  only  used  for  very  common  works,  such  as  children’s  toys : like  willow,  of  which 
it  is  a variety,  it  is  planed  into  chips,  and  made  into  bonnets. and  baskets;  it  splits  well.  Se<- 
Willow. 

Sandal-wood  is  the  produce  of  Santalum  album,  a tree  having  somewhat  the  appearance  of  a large 
myrtle.  The  wood  is  extensively  employed  as  a perfume  in  the  funeral  ceremonies  of  the  Him 
doos.  The  deeper  the  color,  which  is  of  a yellow  brown,  and  the  nearer  the  root,  the  better  i- 
tbe  perfume.  Malabar  produces  the  finest  sandal-wood  ; it  is  also  found  in  Ceylon  and  the 
South  Sea  Islands.  It  is  imported  in  trimmed  logs  from  3 to  8 and  rarely  14  in.  diameter ; the 
wood  is  in  general  softer  than  boxwood,  and  easier  to  cut.  It  is  used  for  parts  of  cabinets,  neck- 
laces, ornaments,  and  fans.  The  bark  of  the  sandal-wood  gives  a most  beautiful  red  or  ligh* 
claret-colored  dye,  but  it  fades  almost  immediately  when  used  as  a simple  infusion ; in  the  hamb 
of  the  experienced  dyer  it  might,  it  is  supposed,  be  very  useful. 

There  are  woods  described  in  the  French  works  as  red  sandal-woods.  See  Calembeg. 

The  sandal-wood  tree  of  the  Malabar  coast  is  the  Santalum  album  ; that  of  the  South  Sea 
Islands  is  considered  to  be  a distinct  species,  and  has  been  named  Santalum  Freycinetianuin  . 
there  is  a spurious  sandal-wood  in  the  Sandwich  Isles,  called  by  the  natives  Nailiio , (J/yo 
porum  tenuifolium.) 

Sapan-wood,  or  Buckum-wood,  (Ccesalpinia  Sapan,)  is  obtained  from  a species  of  the  same  genu- 
that  yields  the  Brazil-wood.  It  is  a middle-sized  tree,  indigenous  to  Siam,  Pegu,  the  coast  of 
Coromandel,  the  Eastern  Islands,  &c.  It  is  imported  in  pieces  like  Brazil-wood,  to  which,  for 
the  purposes  of  dyeing,  it  is  greatly  inferior  ; it  is  generally  too  unsound  to  be  useful  for  turning. 

Satin-wood.  The  best  variety  is  the  West  Indian,  imported  from  St.  Domingo,  in  square  logs  and 
planks,  from  9 to  20  in.  wide ; the  next  in  quality  is  the  East  Indian,  shipped  from  Singapore 
and  Bombay  in  round  logs  from  9 to  30  in.  diameter ; and  the  most  inferior  is  from  Hew  Provi- 
dence, in  sticks,  from  3J  to  10  in.  square ; the  wood  is  close,  not  so  hard  as  boxwood,  but  some- 
what like  it  in  color,  or  rather  more  orange ; some  pieces  are  very  beautifully  mottled  and 
curled.  It  was  much  in  vogue  a few  years  back  for  internal  decoration  and  furniture  ; it  is  now 
principally  used  for  brushes,  and  somewhat  for  turning ; the  finest  kinds  are  cut  into  veneers, 
which  are  then  expensive;  the  Nassau-wood  is  generally  used  for  brushes.  Satin-wood,  of  hsiid- 
some  figure,  was  formerly  imported  in  large  quantities  from  the  island  of  Dominica.  The  wood 
has  an  agreeable  scent,  and  is  sometimes  called  yellow  saunders.  Bergeron  mentions  a “ bois 
saline  rouge? 

The  satin-wood  of  Guiana  is  stated  by  Aublet  to  be  yielded  by  his  Ferolia  guianensis,  which 
has  both  white  and  reddish-colored  wood,  both  satiny  in  appearance.  The  satin-wood  of 
India  and  Ceylon  is  yielded  by  Chloroxylon  Swietenia. 

Sassafras-wood  is  a species  of  laurel,  ( Sassafras  officinalis;)  the  root  is  used  in  medicine.  The- 
small  wood  is  of  a light  brown,  the  large  is  darker ; both  are  plain,  soft,  and  close.  Sassafras- 
wood  measures  from  4 to  12  in.  diameter;  it  is  sometimes  chosen  for  cabinet-work  and  turning, 
on  account  of  its  scent. 

Saul,  or  S&l,  an  East  Indian  timber-tree,  the  Shorea  robusta,  (see  377,  Dr.  Wallich’s  Catalogue:) 
this  wood  is  in  very  general  use  in  India  for  beams,  rafters,  and  various  building  purposes;  Saul 
is  close-grained  and  heavy,  of  a light  brown  color,  not  so  durable,  but  stronger  and  tougher  than 
teak,  and  is  one  of  the  best  timber- trees  of  India.  Captain  Baker  considers  Saul  to  resist  strains, 
howsoever  applied,  better  than  any  other  Indian  timber;  he  says  the  Morung  Saul  is  the  best. 
The  Sissoo  appears  to  be  the  next  in  esteem,  and  then  the  teak,  in  respect  to  strength.  See 
Baker’s  Papers. 

Saunders.  See  Red  Saunders. 

Service-tree.  This  is  a kind  of  thorn,  and  bears  the  service-berry,  which  is  eaten  ; it  is  very  much 
like  English  sycamore  in  every  character  as  regards  the  wood. 

Bergeron  describes  the  service-tree  as  a very  hard,  heavy,  and  useful  wood,  of  a red-brown 
color,  and  well  adapted  to  the  construction  of  all  kinds  of  carpenters’  tools.  He  says  they  will 
glue  slips  of  the  service-tree  upon  moulding  planes,  the  bulk  of  which  are  of  oak,  on  account 
of  its  hardness  and  endurance.  He  also  speaks  of  a foreign  service-tree,  (Cormier  des  Isles.) 
which  is  harder,  but  more  gray  in  color,  and  more  veined : these  appear  to  be  totally  different 
woods. 

Sissoo  (Balbergia  Sissoo). is  one  of  the  most  valuable  timber-trees  of  India,  and,  with  the  Saul,  is 
more  extensively  employed  than  any  other  in  Northwest  India.  The  ship-builders  in  Bengal 
select  it  for  their  crooked  timbers  aud  knees ; . it  is  remarkably  strong ; its  color  is  a light  grayish- 
brown,  with  darker-colored  veins.  “In  structure  it  somewhat  resembles  the  finer  species  of 
teak,  but  it  is  tougher  and  more  elastic.”  There  are  two  kinds  used  respectively  in  Bengal  and 
Bombay;  the  latter  is  much  darker  in  color.  The  Indian  black  rosewood  ( Balbergia  latifolia ) 
is  a superior  species  of  Sissoo  from  the  Malabar  coast. 

Snakewood,  Letter  or  Speckled  wood,  is  used  at  Demerara,  Surinam,  and  along  the  banks  of  the 
Oronoko,  for  the  bows  of  the  Indians.  The  color  of  the  wood  is  red  hazel,  with  numerous  black- 
spots  and  marks,  which  have  been  tortured  into  the  resemblance  of  letters,  or  the  scales  of  the 
reptile  ; when  fine,  it  is  very  beautiful,  but  it  is  scarce  in  England  and  chiefly  used  for  walking- 
sticks,  which  are  expensive ; the  pieces,  that  are  from  2 to  6 in.  diameter,  are  said  to  be  thf 
produce  of  large  trees,  from  three  to  four  times  those  diameters,  the  remainder  being  sap. 


952 


WOODS,  VARIETIES  OK 


Dr.  Bancroft  says,  “ Bourra  courra,  as  it  is  called  by  the  Indians,  by  the  French  hois  da  lettre. 
and  by  the  Dutch  Letter  hout,  is  the  heart  of  a tree  growing  30  feet  in  height  with  many  branch- 
es,” die. 

“The  above  must  not  be  confounded  with  the  Snakewood  of  the  West  Indies  and  South 
America,  the  Cecropia,  of  which  there  are  three  species,  all  furnishing  trees  of  straight  and  tall 
growth,  and  a wood  of  very  light  structure,  presenting  sometimes  distinct  and  hollow  cells. 
The  Balsas,  or  floats,  used  by  the  Indians  of  South  America  for  fishing,  &c.,  are  very  commonly 
constructed  of  this  wood.” 

It  is  thought  by  some  to  be  the  Tapura  guianensis,  of  Aublet. 

Speckled-wood.  See  Snakewood. 

Spanish  Chestnut.  See  Chestnut. 

Spindle-tree  ( Euonymus  europa)  is  a shrubby  tree,  with  a yellow  wood,  similar  to  the  English  box- 
wood, but  straighter  and  softer : it  is  turned  into  bobbins  and  common  articles.  Bergeron  says 
the  wood  is  used  in  France  for  inferior  carpenters’  rules,  and  that  its  charcoal,  prepared  in  a 
gun-barrel  or  any  closed  vessel,  is  very  suitable  to  the  artist,  as  its  mark  may  be  readily 
effaced. 

Sycamore,  the  Acer  pseudo-platanus,  is  called  in  Europe  the  great  maple,  and  in  Scotland  and 
the  north  of  England,  plane-tree ; its  mean  size  is  32  ft.  high.  Sycamore  is  a very  clean 
wood,  with  a figure  like  the  plane-tree,  but  much  smaller  ; it  is  softer  than  beech,  but  rather 
disposed  to  brittleness.  The  color  of  young  sycamore  is  silky  white,  and  of  the  old  brownish 
white  ; the  wood  of  middle  age  is  intermediate  in  color,  and  the  strongest ; some  of  the  pieces  are 
very  handsomely  mottled.  It  is  used  in  furniture,  piano-fortes,  and  harps.  Sycamore  may  be  cut 
into  very  good  screws,  and  it  is  used  for  presses,  dairy  utensils,  (fee.  See  Maple. 

Teakwood  is  the  produce  of  the  Tectona  grandis,  a native  of  the  mountainous  parts  of  the  Malabar 
coast,  and  of  the  Rajahmundry  Circars,  as  well  as  of  Java,  Ceylon,  and  the  Moulmein  and  Tenas- 
serim  coasts. 

It  grows  quickly,  straight,  and  lofty ; the  wood  is  light  and  porous,  and  easily  worked,  but  it  is 
nevertheless  strong  and  durable  ; it  is  soon  seasoned,  and  being  oily,  does  not  injure  iron,  and 
shrinks  but  little  in  width.  Its  color  is  light  brown,  and  it  is  esteemed  most  valuable  timber  in 
India  for  ship-building  and  house-carpentry ; it  has  many  localities.  The  Malabar  teak  grown  on 
the  western  side  of  the  Ghaut  mountains  is  esteemed  the  best.  Teak  is  considered  a more  brittle 
wood  than  the  Saul  or  the  Sissoo. 

In  25  years  the  teak  attains  the  size  of  two  feet  diameter,  and  is  considered  serviceable  timber 
but  it  requires  100  years  to  arrive  at  maturity.  There  is  a variety,  says  Dr.  Roxburgh,  which 
grows  on  the  banks  of  the  Godavery  in  the  Deccan,  of  which  the  wood  is  beautifully  veined, 
closer  grained  and  heavier  than  the  common  teak-tree,  and  which  is  well  adapted  for  furniture. 

Some  of  the  old  trees  have  beautiful  burrs,  resembling  the  Amboyna,  which  are  much 
esteemed. 

The  woods  in  general  do  not  very  perceptibly  alter  in  respect  to  length  ; Teak,  says  Colonel 
Lloyd,  is  a remarkable  exception.  He  found  the  contraction  in  length,  in  the  beams  of  a large 
room  he  erected  in  the  Mauritius,  to  be  three-quarters  of  an  inch  in  38  feet. 

The  teakwood  when  fresh  has  an  agreeable  odor,  something  like  rosewood,  and  an  oil  is  ob- 
tained from  it.  He  adds,  “ The  finest  teak  now  produced  comes  from  Moulmein  and  other  parts 
of  Burmah  ; some  of  this  timber  is  usually  heavy  and  close-grained,  but  in  purchasing  large 
quantities  care  must  be  taken  that  the  wood  has  not  been  tapped  for  its  oil,  which  is  a frequent 
custom  of  the  natives,  and  renders  the  wood  less  durable.” 

“ At  Moulmein,  so  much  straight  timber  is  taken  and  the  crooked  left,  that  thousands  of  pieces 
called  ‘ shin  logs,’  and  admirably  adapted  for  ship-timbers,  are  left.  Teak  contains  a large  quantity 
of  silicious  matter,  which  is  very  destructive  to  the  tools.” 

African  teak  does  not  belong  to  the  same  genus  as  the  Indian  teak ; by  some  it  is  thought  to 
be  a Euphorbiaceous  plant,  and  by  Mr.  Don  to  be  a Vitex. 

Toonwood  has  already  been  mentioned  under  the  head  of  Cedar,  as  being  similar  to  the  so-called 
Havana  cedar,  the  Ccdrcla  odorata.  The  toon-tree  is  C.  Toona ; its  wood  is  of  a reddish- 
brown  color,  rather  coarse-grained,  but  much  used  all  over  India  for  furniture  and  cabinet- 
work. 

Tulip-wood  is  the  growth  of  the  Brazils.  The  wood  is  trimmed  and  cut  like  Kingwood,  but  it  is  in 
general  very  unsound  in  the  centre,  its  color  is  flesh-red,  with  dark  red  streaks ; it  is  very  hand- 
some, but  it  fades.  The  wood,  which  is  very  wasteful  and  splintery,  is  used  in  turnery,  Tunbridge- 
ware  manufactures,  and  brushes. 

A wood  sometimes  called  French  tulip-wood,  from  its  estimation  in  that  country,  appears  to 
resemble  a variegated  cedar  : it  is  much  straighter  and  softer  in  the  grain  than  the  above,  the 
streaks  are  well  contrasted,  the  light  being  of  an  orange  red ; it  appears  to  be  a very  excellent 
furniture  and  turnery- wood,  but  has  no  smell ; it  contains  abundance  of  gum,  and  is  considered  to 
come  from  Madras,  but  which  peninsula  has  no  pines. 

Minhatico.  The  Portuguese  name  for  several  yellow  and  yellow-brown  woods.  See  Canary-wood, 

Violet-wood.  See  Kingwood. 

Vjxewood.  See  Apricot-tree. 

Walnut.  The  Royal  or  Common  "Walnut  (Jv.gl.ans  regia ) is  a native  of  Persia  and  the  north  of 
China.  Walnut  was  formerly  much  used  in  England  before  the  introduction  of  mahogany.  The 
heart-wood  is  of  a grayish  brown,  with  black-brown  pores,  and  often  much  veined  with  darker 
shades  of  the  same  color  ; the  sap-wood  is  grayish  white.  Some  of  the  handsome  veneers  are 
now  used  for  furniture,  but  the  principal  consumption  is  for  gun-stocks,  the  prices  of  which  in  the 
rough  vary  from  a few  pence  to  one  and  two  guineas  each,  according  to  quality.  An  inferior 


WOODS,  VARIETIES  OF. 


953 


kind  of  walnut  is  very  much  used  in  France  for  furniture,  frames  of  machines,  <fec. ; it  is  less 
brown  than  the  line  sort. 

The  Black  Virginian  Walnut  ( Juglans  nigra ) is  found  from  Pennsylvania  to  Florida.  It  is 
a large  tree,  has  a fine  grain,  is  beautifully  veined,  and  is  the  most  valuable  of  the  American 
kinds  for  furniture. 

The  White  Walnut  is  the  Hickory,  which  see. 

Willow.  There  are  many  varieties  of  the  willow,  ( Salix .)  It  is  perhaps  the  softest  and  lightest  of 
our  woods.  Its  color  is  tolerably  white,  inclining  to  yellowish-gray  ; it  is  planed  into  chips  for 
hat-boxes,  baskets,  and  wove  bonnets  ; it  has  been  attempted  to  be  used  in  the  manufacture  of 
paper.  The  small  branches  of  willow  are  used  for  hoops  for  tubs,  the  large  wood  for  cricket- 
bats.  From  the  facility  with  which  it  is  turned,  it  is  in  demand  for  boxes  for  druggists  and  per- 
fumers, which  are  otherwise  made  of  small  birchwood. 

The  wood  of  the  willow  is  described  by  Mr.  Loudon  as  soft,  smooth,  and  light ; the  wood  of 
the  larger  species,  as  Salix  alaba  and  Russelliana,  is  sawn  into  boards  for  flooring.  The  red- 
wood willow,  S.  fragiiis,  is  said  to  produce  timber  superior  to  any  other  species  : it  is  used 
for  building  light  and  swift-sailing  vessels  ; S.  Russelliana,  being  closely  allied  to  S.  fragiiis, 
is  probably  allied  to  it  in  properties.  The  wood  of  S.  caprea  is  heavier  than  that  of  any 
other  species.  Hats  are  manufactured  in  France  from  strips  of  the  wood  S.  alba. 
Yacca-wood,  or  Yacher,  from  Jamaica,  is  sent  in  short  crooked  pieces  like  roots,  from  4 to  12  in.  thick. 
The  wood  is  pale  grown,  with  streaks  of  hazel  brown  ; it  is  principally  used  for  ornamental 
cabinet  and  marquetry  work,  and  turning  ; some  pieces  are  very  handsome. 

Yellow-wood.  There  is  a fine  East  India  wood  thus  called ; it  appears  to  be  larger  and  straighter 
than  boxwood,  but  not  so  close-grained. 

This  is  probably  a Nauclea.  The  wood  of  Nauclea  cordifolia,  according  to  Dr.  Roxburgh,  is 
exceedingly  beautiful  in  color,  like  boxwood,  but  much  lighter,  and  at  the  same  time  very 
close-grained.  It  is  used  by  the  inhabitants  of  Northern  India  to  make  combs  of. 

Yew.  The  yew-tree  is  common  in  Spain,  Italy,  and  England.  The  tree  is  not  large,  and  the  wood  is 
of  a pale  yellow-red  color,  handsomely  striped,  and  often  dotted  like  Amboyna.  It  has  been 
long  famed  for  the  construction  of  bows,  and  is  still  so  employed,  although  the  undivided  sway  it 
held  in  the  days  of  Robin  Hood  has  ceased.  The  English  species  ( Taxus  baccata ) is  esteemed  a 
hard,  tough,  and  durable  wood : it  is  a common  saying  amongst  the  inhabitants  of  the  New 
Forest  in  Hampshire,  that  a post  of  yew  will  outlive  a post  of  iron  ; it  would  appear  the  yew- 
tree  lives  to  a great  age,  as  some  of  those  in  Norbury  Park  are  said  to  have  been  recorded  in 
Domesday  Book.  The  yew-tree  is  used  for  making  chairs,  handles,  archery-bows  and  walking- 
sticks.  Some  of  the  older  wood  is  of  a darker  color,  more  resembling  pale  walnut-tree,  and  very 
beautifully  marked  ; the  finer  pieces  are  reserved  for  cabinet-work,  and  it  is  a clean  wood  for 
turning.  The  Irish  yew  is  preferred  for  bows. 

The  burrs  of  the  yew-trees  are  exceedingly  beautiful,  and  although  larger  in  figure,  they  some- 
times almost  equal  the  Iviabooca. 

The  American  yew,  Taxus  canadensis,  is  supposed  to  be  only  a variety  of  T.  baccata;  the 
Himalayan  species  are  closely  allied  to  this  and  to  T.  nucifera. 

Zanie,  or  Young  Fustic,  from  the  Mediterranean,  is  a species  of  sumach,  (Rhus  Cotinus.)  It  is  small, 
and  of  a golden  yellow,  with  two-thirds  sap  ; it  is  only  used  for  dyeing,  and  is  quite  distinct  from 
the  Morus  tinctoria,  or  old  fustic. 

Speaking  of  this  tree,  Dr.  Bancroft  says  : “ A distinction  was  improperly  created  at  least  130 
years  ago,  (now  180,)  calling  that  of  the  Venice  sumach  Young  Fustic,  (as  being  manifestly  the 
wood  of  a small  shrub,)  and  that  of  Morus  tinctoria,  (which  is  always  importe.d  in  the  form  of 
large  logs  or  blocks,)  Old  Fustic.” — Bancroft's  Phil,  of  Colors,  v.  i.  p.  413. 

The  Zante  is  also  called  Chloroxylon  ; its  modern  Greek  name  is  Imppore. 

Zebra-wood  is  the  produce  of  the  Brazils  and  Rio  Janeiro  ; it  is  sent  in  logs  and  planks,  as  large  as 
twenty-four  inches.  The  color  is  orange-brown,  and  dark-brown  variously  mixed,  generally  in 
straight  stripes  ; it  is  suitable  to  cabinet-work  and  turnery,  as  it  is  very  handsome.  A wood 
from  New  South  Wales  bearing  some  resemblance  to  the  above  is  sometimes  called  by  the  same 
name,  as  are  also  some  other  woods  in  which  the  stripes  are  of  a distinct  and  decided  character. 

The  zebra-wood  is  considered  by  upholsterers  to  be  intermediate  in  general  appearance  be- 
tween mahogany  and  rosewood,  so  as  to  form  a pleasing  contrast  with  either  of  them.  The 
Portuguese  name  for  the  zebra-wood  appears  from  Mr.  G.  Loddiges’  collection  to  be  Burapinima, 

and  from  Mr. 's  Goncalo  do  para  : No.  53,  of  the  last  group,  Casco  do  tartarua,  is  like  Zebra, 

but  heavier,  more  handsome,  and  of  a rich  hazel-brown,  with  black  wavy  streaks.  The  pigeon- 
woods  are  usually  lighter,  and  of  more  yellow-browns. 

Zebra-wood  is  also  called  Pigeon-wood ; one  kind  of  Pigeon-wood  in  Jamaica  is  Gucttarda 
speciosa. 

Memoir  on  the  preservation  of  woods. — A paper  bearing  this  title  was  lately  read  before  the  French 
-ieademy  of  Sciences,  by  its  author,  Dr.  Boucherie,  and  as  an  appropriate  sequel  to  the  foregoing  pages 
ipon  the  woods,  we  append  a synopsis  of  the  numerous  experiments  referred  to. 

He  contrasts  the  increasing  consumption  and  the  rapid  decay  of  timber,  with  its  slow  rate  of  produc. 
tion,  which  make  it  necessary  to  economize  its  employment.  He  adverts  to  the  many  projects  for  its 
preservation,  enumerated  by  Mr.  John  Knowles,  and  the  methods  subsequently  proposed,  to  many  of 
which  he  objects  from  their  uselessness  ; to  others  from  the  slow  and  superficial  manner  in  which 
timbers  part  with  their  contained  fluds,  or  absorb  new  ones  by  simple  immersion,  (circumstances 
long  since  proved  by  Duhamel ;)  and  t > all  from  their  expense,  which  is  of  course  the  ultimate  test  of 
general  application. 


954 


WOODS,  VARIETIES  OF 


Dr.  Boucherie  argues,  that  all  the  changes  in  woods  are  attributable  to  the  soluble  parts  they  contain, 
which  either  give  rise  to  fermentation  or  decay,  or  serve  as  food  for  the  worms  that  so  rapidly  penetrate 
even  the  hardest  woods.  As  the  results  of  analyses,  he  says  that  sound  timbers  contain  from  three  to 
seven  per  cent,  of  soluble  matters,  and  the  decayed  and  worm-eaten  rarely  two,  commonly  less  than 
one,  per  cent. ; he  therefore  concludes  that  “ since  the  soluble  matters  of  the  wood  'were  the  causes  of 
the  changes  it  undergoes,  it  is  necessary  to  its  preservation,  either  to  abstract  the  soluble  parts  in  any 
way,  or  to  render  them  insoluble  by  introducing  substances  which  should  render  them  infermentable 
or  inalimentary which  he  considers  may  be  done  by  many  of  the  metallic  salts  and  earthy  chlorides. 

Dr.  Boucherie  shows,  by  parallel  experiments  upon  “vegetable  matters  very  susceptible  of  decom- 
position, as  flour,  the  pulps  of  carrot  and  beet-root,  the  melon,  &c.,  (which  only  differ  from  wood,  of 
which  they  possess  the  origin  and  constitution,  by  the  greater  proportion  of  soluble  matter  which  they 
contain,”)  that  in  the  natural  states  they  rapidly  alter,  but  are  preserved  by  the  pyrolignite  of  iron, 
(pyrolignite  brut  de  fer,)  a cheaper  material  than  the  corrosive  sublimate  commonly  used,  and  one  very 
desirable  in  several  respects.  He  presumed  that  by  immersing  the  end  of  a tree  immediately  after  it 
was  felled  into  a liquid,  the  vital  energies  not  having  ceased,  the  tree  would  then  absorb  such  fluid 
through  all  its  pores,  by  a process  which  he  calls  aspiration ; and  in  this  fortunate  surmise  he  was  en- 
tirely successful.  This  led  step  by  step  to  numerous  practical  results,  which  their  inventor  enumerates 
as  follows,  and  describes  in  separate  chapters. 

1st.  “ For  protecting  the  woods  from  the  dry  or  wet  rot.” 

2d.  “ For  augmenting  their  hardness.” 

3d.  “For  preserving  and  developing  their  flexibility  and  their  elasticity.” 

4th.  “ For  rendering  impossible  the  changes  of  form  (jcu)  they  undergo,  and  the  splits  ( disjonctions ) 
which  take  place  when  they  are  brought  into  use,  or  are  submitted  to  atmospheric  changes.” 

5th.  “For  greatly  reducing  their  inflammability  and  combustibility.” 

6th.  “ For  giving  them  various  and  lasting  colors  and  odors.” 

We  shall  endeavor  to  convey  a general  notion  of  the  methods  in  the  same  order. 

1.  Durability.  He  took  a poplar  tree  measuring  28  mitres  in  height  and  40  centimetres  diameter, 
simply  divided  from  its  root  with  its  branches  and  leaves  undisturbed,  and  immersed  it  erect  to  the 
depth  of  20  centimetres  in  a vessel  containing  pyrolignite  of  iron  ; in  six  days  it  was  entirely  impreg- 
nated even  to  the  leaves,  and  had  absorbed  the  large  quantity  of  three  hectolitres.  This  method  re- 
quired powerful  lifting  apparatus,  and  a support  for  the  tree  to  lean  against,  and  hence  was  objectionable. 

He  repeatedly  operated  upon  trees  lying  on  the  ground,  by  attaching  to  their  bases  water-proof  bags 
containing  the  liquid : the  experiments  were  varied  in  many  ways ; sometimes  portions  of  the  branches 
were  lopped  oft)  but  the  crown  or  tuft  was  always  left  upon  the  principal  stem ; at  other  times  the 
aspiration  was  effected  by  boring  detached  holes  near  the  earth  supplied  with  different  fluids,  which 
gave  rise  to  all  kinds  of  diversities  in  the  result ; and  other  trees  were  pierced  entirely  through,  and  a 
horizontal  cut  extending  to  within  an  inch  or  so  of  each  side  was  made  with  a thick  saw,  leaving  only 
sufficient  wood  for  the  support  of  the  trees. 

For  fear  of  losing  the  trees  upon  which  he  had  the  opportunity  of  experimenting,  the  process  was 
not  deferred  beyond  24,  36,  or  48  hours  after  they  were  felled,  as  the  vigor  of  the  absorption  was  found 
to  abate  rapidly  after  the  first  day,  and  that  at  about  the  tenth  day  it  was  scarcely  perceptible : it  was 
also  found  the  aspiration  entirely  failed  in  dead  wood,  whether  occurring  at  the  heart  of  old  trees,  or  at 
parts  of  others  from  any  accidental  interruption  of  the  flow  of  the  sap  during  the  growth ; and  also  that 
resinous  trees  absorbed  the  fluids  less  rapidly  than  others. 

Observations  were  also  made  of  the  quantities  of  the  liquids  taken  up ; these  fluids,  when  of  a neu- 
tral kind,  as  the  chloride  of  soda,  often  equalled  in  bulk  that  of  the  wood  itself,  without  causing  any 
addition  to  its  weight ; the  acid  and  alkaline  fluids  were  less  abundantly  absorbed,  apparently  from 
contracting  the  vessels  by  their  astringent  action.  It  is  stated  that  the  pyrolignite  of  iron  effected  the 
preservation  of  the  substance  when  equal  to  less  than  a fiftieth  of  the  weight  of  the  green  wood.  These 
points  are  all  separately  treated  in  the  original  paper. 

2.  The  hardness  of  the  wood  was  considered  by  various  workmen  to  be  more  than  doubled  by  the 
action  of  the  pyrolignite. 

3.  The  flexibility  (due  to  a certain  presence  of  moisture)  was  increased  in  a remarkable  manner  by 
the  chloride  of  lime  and  other  deliquescent  salts,  the  degree  of  elasticity  depending  upon  their  greater 
or  less  concentration.  As  a cheap  substitute  for  the  above,  the  stagnant  water  of  salt  marshes  was 
adopted,  with  a fifth  of  the  pyrolignite,  for  the  greater  certainty  of  preservation.  Pieces  of  prepared 
deal,  3 millimetres  thick  and  60  centimetres  long,  were  capable  of  being  twisted  and  bent  in  all  direc- 
tions, as  into  screws,  also  into  three  circular  coils;  the  wood  immediately  regained  its  figure  when  re- 
leased ; this  condition  lasted  eighteen  months,  that  is,  until  the  time  his  paper  was  read. 

4.  The  warping  and  splitting,  principally  due  to  the  continual  effect  of  the  atmosphere  in  abstracting 
and  restoring  the  moisture,  was  stayed  by  impregnating  the  wood  with  a weak  infusion  of  the  chloride, 
so  as  always  to  retain  it  to  a certain  degree  moist ; one-fifth  of  pyrolignite  was  also  added  in  this  case. 
The  seasoning  of  the  wood  was  also  considered  to  be  expedited  by  the  process,  and  which  was  not 
found  to  interfere  with  the  ordinary  use  of  oil-paint,  <fcc.  Large  boards  of  the  prepared  wood,  some  of 
which  were  painted  on  one  or  both  sides,  and  similar  boards  of  unprepared  wood,  were  compared ; at  the 
end  of  twelve  months,  the  former  were  perfect  as  to  form,  the  latter  were  warped  and  twisted  as  usual. 

5.  The  inflammability  and  combustibility  of  the  woods  were  also  prevented  by  the  earthy  chlorides, 
which  fuse  on  their  surfaces  by  the  application  of  heat,  and  render  them  difficult  of  ignition.  Twc 
similar  cabins  were  built  of  prepared  and  of  ordinary  wood  respectively,  and  similar  fires  were  lighted 
in  each ; the  latter  was  entirely  burned,  the  other  was  barely  blackened. 

6.  In  respect  to  colors  infused  by  the  aspiratory  process,  the  vegetable  colors  were  found  to  answei 
less  perfectly  than  the  mineral,  and  the  latter  succeeded  best  when  the  color  was  introduced  at  two 
processes,  so  that  the  chemical  change  (that  of  ordinary  dyeing)  occurred  in  the  pores  of  the  wood 


WOOD  STEAM  CARBONIZING  MACHINE. 


95. 


itself.  Odorous  matters,  required  to  be  infused  in  weak  alcoholic  solutions,  or  essential  oils,  they  were 
considered  to  be  equally  durable  with  those  supplied  by  the  hand  of  nature  ; and  resins  similarly  intro- 
duced were  found  to  increase  amazingly  the  inflammability  of  the  woods,  and  to  render  them  imper 
vious  to  water. 

On  the  whole,  the  method  is  considered  to  promise  the  means  of  working  almost  any  desired  change 
in  the  constitution  and  properties  of  woods,  when  the  fluids  are  presented  to  them  before  the  vitality 
of  the  tree  has  ceased.  It  is  true  we  have  as  yet  only  two  years’  trial  of  these  experiments,  but  they 
have  been  scientifically  deduced,  and  their  inventor  is  still  engaged  in  prosecuting  them.  It  is  to  be 
hoped,  and  also  expected,  that  these  interesting  and  flattering  promises  of  success  will  be  realized,  and 
even  extended,  when  tried  by  that  most  severe  of  all  tests,  time.* 

For  the  preceding  article  on  Woods,  we  acknowledge  our  indebtedness  to  Holtzapffel’s  Turning  and 
Mechanical  Manipulation,  a work  we  conceive  of  great  merit. 

WOOD  STEAM  CARBONIZING  MACHINE.  Description  of  an  apparatus  for  carbonizing  wood 
by  means  of  heated  steam.  By  M.  Violette.  It  is  well  known  that  the  nature  of  the  product  of  the 
carbonization  of  wood,  in  a close  vessel,  varies  according  to  the  temperature : for  instance,  a very  great 
heat  produces  a black  charcoal,  deprived  of  the  greater  part  of  its  volatile  hydrogenated  parts  ; whilst 
a more  moderate  heat  gives  a red  charcoal,  retaining  more  of  the  properties  of  wood,  and  still  charged 
with  volatile  principles.  It  is  this  latter  quality  of  charcoal  which  produces  the  best  gunpowder;  and 
it  is  therefore  important  to  discover  the  best  means  of  preparing  it.  With  this  object  in  view,  M. 
Violette  has,  by  experiment,  determined  the  limits  within  which  a red  charcoal  may  be  obtained : that 
is  to  say,  a product  which  is  not  wood,  and  yet  is  not  perfect  charcoal.  To  effect  this  object  he  employs 
a bath  of  metal,  fusible  at  160°,  composed  of  one  part  bismuth,  4 parts  of  lead,  and  3J  parts  of  tin. 
This  metal  he  keeps  in  fusion  in  a deep  glass  vessel,  suspended  over  a Carcel  lamp.  A thermometer, 
graduated  at  350°,  is  immersed  in  this  bath  to  show  the  temperature.  The  pieces  of  wood  to  be  experi- 
mented upon  are  fastened  to  the  ends  of  platina  wires,  and  put  into  glass  tubes,  closed  at  one  end,  and 
immersed  in  the  metallic  bath.  By  this  arrangement  the  wood  is  maintained  at  the  temperature  indi- 
cated by  the  thermometer,  and  sufficiently  protected  from  contact  with  the  atmosphere.  The  wood 
may  be  withdrawn  for  inspection,  when  required,  by  means  of  the  platina  wires.  A suitable  and  un- 
varied temperature  may  be  maintained  by  raising  or  lowering  the  wick  of  the  lamp  at  the  beginning  of 
the  operation.  The  wood  exposed  in  this  apparatus  during  an  hour  to  a temperature  of  from  200°  to 
250°,  does  not  become  converted  into  charcoal;  at  the  end  of  two  hours,  at  the  same  temperature,  it  is 
converted  into  red  charcoal,  its  surface  being  properly  carbonized,  but  its  interior  being  still  wood  ; at 
the  end  of  three  hours  it  is  converted  into  a hard  red  charcoal,  brittle,  and  burning  with  flame,  but  inca- 
pable of  extending  its  combustion  ; if  submitted  for  an  hour  to  a heat  of  300'  a very  good  red  charcoal 
is  obtained,  of  sufficient  hardness,  but  easily  pulverizable ; on  the  prolongation  of  the  experiment 
to  two  hours  a more  perfect  charcoal  is  obtained,  which  burns  with  flame;  and  lastly7,  at  a temperature 
of  350°,  and  at  the  end  of  half  an  hour,  a charcoal  is  obtained  which  is  black,  friable,  and  easily 
pounded. 

The  first  experiments  were  made  with  a small  apparatus,  capable  of  containing  about  2 lbs.  of  wood  ; 
and,  independently  of  the  superior  quality  of  the  powder  manufactured  with  the  charcoal  thus  obtained, 
it  was  found  that  the  product  was  augmented  to  as  much  as  42  per  cent,  of  the  weight  of  the  wood. 

The  apparatus  now  employed  for  this  purpose  is  shown  below,  Fig.  3953  being  a longitudinal  vertical 
section,  and  Fig.  3954  a transverse  section  in  the  line  a b of  Fig.  3953.  It  consists  of  two  hollow  con- 
3954.  3953. 


centric  iron  cylinders,  H and  II ; in  the  inner  one  (II)  of  which  the  wood  to  be  carbonized  is  placed. 
C is  a coil  of  steam  pipe,  communicating  at  one  end  with  a steam-boiler,  and  at  the  other  with  the 
outer  cylinder  H.  A is  the  fire  place,  (which  may  be  fed  with  wood  or  coke,  or  some  other  suitable 
fuel,)  wherein  the  steam-pipe  is  heated  to  any  required  degree  of  temperature.  The  cylinder  H is 
closed  by  a wrouglit-iron  cover  1,  and  the  apparatus  is  provided  with  two  outside  cast-iron  doors  FF, 
by  which  it  is  protected  from  the  cooling  action  of  the  atmosphere.  Lisa  pipe  for  letting  off  the  steam 
and  the  products  of  the  distillation  of  the  wood  from  the  cylinder  K.  G is  the  flue,  for  the  escape  of 
the  smoke  from  the  fireplace  A.  The  whole  apparatus  is  surrounded  by  brickwork  or  masonry,  N. 

* In  France,  Ur.  Boucherie  has  relinquished  his  brevet , and  thrown  the  process  open  to  the  public  in  consideration  of  a 
national  reward ; and  immense  preparations  are  being  there  made,  by  the  Minister  of  Marine,  for  the  employment  of  the 
preservative  process  for  the  French  navy.  In  England  Dr.  Boucherie  and  Company  have  obtained  two  patents,  and  Mr. 
Puddock,  their  agent,  has  specimens  of  pine,  plane-tree,  &c..'  variously  prepared  and  colored,  with  the  pyrolignite  of  iron, 
the  prussiate  of  iron,  the  prussiate  of  copper,  and  various  other  metallic  salts,  &c. 


956 


WRENCH,  CYLINDER. 


The  wood  to  be  carbonized  is  first  placed  in  a cylinder,  made  either  of  wire  work  or  perforated  metal, 
which  is  introduced  into  the  cylinder  K;  by  this  arrangement,  should  the  charcoal  become  ignited  on 
being  taken  out,  the  flame  will  be  prevented  from  spreading.  The  charge  in  this  apparatus  weighs 
from  30  to  40  lbs. 

Mode  of  operation. — The  first  thing  to  be  done  is  to  get  up  the  steam,  until  the  manometer  indicates 
one  atmosphere ; the  fireplace  for  heating  the  steam-pipe  is  then  to  be  lighted,  and  in  about  a quartet 
of  an  hour  the  doors  may  be  opened,  and  the  perforated  cylinder  containing  the  wood  introduced  into 
the  cylinder  Iv,  which  is  then  closed  by  means  of  the  cover  I ; a luting  of  clay  being  made  round  the 
edge  thereof,  and  a screw  ni  applied  to  fasten  the  cover  in  its  place,  the  outer  doprs  may  then  be 
closed.  After  the  lapse  of  ten  minutes,  when  the  luting  has  become  sufficiently  dried,  the  induction 
steam-cock  is  opened,  and  the  steam  rushes  into  the  steam-pipe  C,  where  it  becomes  heated;  from 
thence  it  passes  into  the  outer  cylinder  H,  and  into  the  inner  cylinder  K at  its  open  end,  where  it  grad- 
ually insinuates  itself  into  the  pores  of  the  wood,  acting,  by  its  great  heat,  in  such  a manner  as  to  car- 
bonize it,  and  finally  makes  its  escape  through  the  pipe  L,  carrying  with  it  the  gases  evolved  from  the 
wood.  In  order  to  keep  the  fire  at  a certain  temperature,  there  is  a small  glazed  opening  at  a,  through 
which  the  workman  can  see  that  the  flame  acts  properly  upon  the  steam-pipe.  After  some  time,  a ther- 
mometer, (specially  constructed  for  the  purpose,)  on  being  introduced  into  the  cylinder  K,  shows  that 
the  temperature  has  reached  such  a height  as  to  melt  tin ; and  the  steam  which  escapes  shows,  by  its 
color  and  odor,  that  it  is  mixed  with  the  first  products  of  distillation  of  the  wood,  and  that  the  carboni- 
zation has  commenced.  The  smoke  or  vapor  thickens,  and  takes  successively  various  aspects,  which 
are  certain  signs  of  the  progress  of  the  operation.  After  about  two  hours  from  the  time  the  distillation 
was  first  apparent,  the  smoke  shows  that  the  operation  is  finished.  The  attendant  then  proceeds  to 
discharge  the  charcoal ; and  for  this  purpose  two  other  attendants  are  ready  with  what  is  called  the 
extinguisher , a large  iron  cylinder,  about  three  feet  in  diameter,  and  about  six  feet  in  length,  to  receive 
the  charcoal.  The  chief  attendant  then  shuts  off  the  steam,  opens  the  doors  F,  turns  the  screw  m,  lays 
hold,  by  means  of  wooden  handles,  of  the  respective  ends  of  the  cross-bar  J,  which  keeps  the  disk  in  its 
place,  detaches  it,  and  plunges  it  into  a vessel  full  of  water  close  by  ; then,  by  means  of  the  same  wooden 
handles,  he  takes  hold  of  the  disk,  and  twisting  it  round,  so  as  to  break  the  luting,  detaches  it,  and  plunges 
it  also  into  the  vessel  of  water.  The  attendants  holding  the  extinguisher  put  it  in  a horizontal  position 
in  front  of  the  cylinder  K,  so  as  to  close  the  orifice.  The  chief  attendant  then  pushes  a long  rod  through 
the  pipe  L,  so  ns  to  push  the  cylinder  containing  the  charcoal  into  the  extinguishing  cylinder,  which  is 
then  quickly  placed  on  the  ground,  and  the  hydraulic  joint  with  which  it  is  provided  is  filled  with 
water.  The  operation  is  then  completed. 

The  inventor  has  observed  that  there  are  no  traces  of  tar  in  the  apparatus,  as  it  is  all  driven  off  by 
the  steam.  The  charcoal  obtained  is  of  very  fine  quality,  and  varies  according  to  the  temperature  ; 
that  is  to  say,  is  red  or  black,  according  to  the  degree  of  heat  and  the  length  of  time  during  which  it  has 
been  maintained.  The  former  is  suitable  for  manufacturing  the  finer  sorts  of  powder  for  sporting  pur 
poses,  and  the  latter,  inferior  powder,  for  blasting  mines,  &c. 

The  apparatus  above  described  has  been  in  operation  more  than  a year,  and  has  produced  5000  lbs. 
of  superior  charcoal,  and  is  now  in  very  good  condition. 

Various  modifications  may  be  made  in  this  apparatus  without  in  any  manner  altering  the  main  fea- 
ture of  the  invention  ; for  instance,  the  inventor  jaroposes,  in  some  cases,  to  use  an  apparatus  containing 
three  carbonizing  cylinders,  one  of  which  shall  not  be  supplied  with  steam,  but  merely  serve  to  dry  the 
wood,  and  prepare  it  for  either  of  the  other  cylinders,  on  either  side  of  the  steam-pipe  ; this  arrange- 
ment has  the  effect  of  rendering  the  operation  continuous. 

WRENCH,  CYLINDER.  Invented  by  S.  Merrick,  of  Springfield,  Massachusetts,  and  patented 
January  2,  1849. 

This  wrench  is  designed  for  grasping  and  turn- 
ing round  bolts,  nuts,  gas  and  water  pipes,  and 
other  cylindrical  substances. 

By  reference  to  the  accompanying  drawings, 
its  construction  and  operation  will  be  readily 
understood. 

Fig.  3955  is  a side  elevation ; Fig.  3956  a cen- 
tral vertical  section.  The  same  letters  refer  to 
like  parts  in  each  figure.  A,  main  bar ; B,  nut, 
fitted  to  a screw,  cut  on  the  two  opposite  edges 
of  the  main  bar ; C,  slide,  made  to  move  easily 
upon  the  main  bar,  and  connected  with  the  nut 
by  a collar  on  the  end  of  the  nut  and  a groove  underneath  the  end  of  the  slide;  D,  tightening  lever, 
attached  to  slide  C by  a joint,  as  seen  at  H ; E,  spring  for  the  purpose  of  pressing  the  lever  D upon 
the  main  bar;  F,  handle.  The  end  of  the  lever  D is  made  circular,  the  centre  of  which  circle  is  shown 
at  G,  for  the  purpose  of  pressing  more  firmly  against  the  cylinder  I,  as  the  end  of  the  lever  is  forced 
down  towards  the  main  bar.  The  circular  end  of  the  lever  is  also  indented  or  roughened  that  it  may 
not  slip  on  the  cylinder  I.  H,  joint  of  the  lever  D and  slide  C ; I,  the  cylindrical  substance  to  be  turned. 

To  operate  the  wrench,  it  is  placed  upon  the  cylinder  to  be  turned,  as  seen  in  Fig.  3955,  and  the 
indented  eud  of  the  lever  D is  brought  in  contact  with  it  by  means  of  the  nut  B.  The  handle  is  then 
moved  backwards,  and  the  lever  advanced  at  the  same  time,  until  the  end  of  the  lever  is  somewhat 
raised  from  the  main  bar  ; the  handle  is  then  carried  forward  in  the  direction  shown  by  the  arrow,  which 
causes  the  lever  to  take  firm  hold  of  the  cylinder  and  carry  it  around  in  the  same  direction  ; and  by 
reversing  the  motion  of  the  handle,  the  cylinder  is  instantly  released  for  a new  hold.  It  will  be  ob- 
vious that  the  wrench  can  be  readily  adapted  to  any  size  of  cylinder  within  its  compass,  and  will  thus 
supply  the  place  of  a pair  of  tongs  (the  only  tool  in  use  for  the  same  purpose  previous  t>e  *his  inven- 


3955. 


ZINC. 


1)57 


tion)  for  each  particular  size  of  cylinder.  It  also  possesses  the  advantage  of  being  worked  with  cna 
hand  after  being  set  to  the  particular  size  required. 

WRENCH,  SCREW.  Invented  by  S.  Merkjck,  of  Springfield,  Massachusetts,  and  patented  Au- 
gust 17,  1835  ; patent  extended  May  14,  1849. 

In  the  drawings,  Fig.  3957  denotes  a side  ele- 
vation ; Fig.  3958,  a vertical  central  section. 

The  same  letters  refer  to  like  parts  in  each 
figure. 

A is  the  main  bar ; B,  the  nut  fitted  to  a 
screw,  cut  on  the  two  opposite  edges  of  the 
main  bar ; C,  a strap , which  passes  around  in  a 
groove  formed  in  the  nut  B,  and  is  riveted  to 
the  end  of  the  slide-jaw  D.  The  collar  on  the 
end  of  the  nut  B takes  into  a corresponding 
groove  in  the  slide  D ; E,  the  end  of  the  main 
bar,  which  forms  the  stationary  jaw  of  the 
wrench  ; F,  the  handle.  The  nut  is  made  to 
move  freely  in  the  strap  C,  and,  by  turning  it  to 
the  right  or  left,  the  slide  D is  moved  to  any  desired  point  on  the  main  bar. 

The  principal  advantages  possessed  by  this  wrench  are,  its  simplicity  of  construction  and  consequent 
cheapness— its  compactness,  durability,  and  strength ; the  size  of  the  main  bar  being  duly  proportioned 
to  the  power  applied,  as  will  be  seen  in  the  figure. 


3957. 


ZINC,  composition  and  use  of.  Zinc  or  Spelter  has  a crystalline  texture,  is  brittle  at  ordinary  tem- 
peratures, and  of  a bluish-white  color : at  300°,  it  is  both  malleable  and  ductile,  and  at  a white  heat 
it  is  converted  into  vapor.  When  pure  zinc  is  exposed  to  air  and  moisture,  it  acquires  a dull  color  from 
partial  oxydizement ; and  great  electric  action  takes  place  when  it  is  in  contact  with  copper,  and  the 
zinc  decays  in  consequence.  Its  specific  gravity  is  7",  and  it  has  a great  attraction  for  oxygen;  the 
weight  of  a cubic  foot  is  439^  pounds. 

Oxide  of  zinc  is  obtained  by  intensely  heating  the  metal  exposed  to  air ; it  takes  fire  at  a red  heat, 
if  the  air  is  freely  admitted,  burning  with  a very  bright  flame. 


Zinc 1 32  80 

Oxygen J_  _8  20 


1 40  100 

Sulpliuret  of  zinc  ( blende ) is  found  native,  and  is  a brittle,  soft  metal,  of  a brown  and  black  color  ; its 
primitive  form  is  a rhomboidal  dodecahedron,  and  it  is  a most  abundant  mineral.  The  pure  metal  is 
obtained  from  it  by  roasting  the  oar,  and  afterwards  distilling  it  when  mixed  with  charcoal. 

Zinc 1 32  66'5 

Sulphur  1 16  33o 

T"  48"  100-0 

Carbonate  of  zinc,  ( calamine  .■)  when  found  crystallized,  its  primitive  form  is  an  obtuse  rhomboid. 

Oxide  of  zinc  1 40  64'5 

Carbonic  acid  1 22  35  5 

T 62  100-0 

Zinc  is  obtained  from  the  sulpliuret  and  carbonate ; the  ore  when  broken  is  submitted  to  a dull  red 
heat  in  a reverberatory  furnace,  when  the  carbonic  acid  is  driven  off  from  the  calamine,  and  the  sul- 
phur from  the  blende  : it  is  then  mixed  with  one-eighth  of  its  weight  of  powdered  charcoal,  being  first 
ground  and  thoroughly  washed,  and  distilled  by  the  application  of  a red  heat ; the  metal  being  put 
into  earthen  pots  with  iron  tubes  cemented  into  the  lower  parts,  dipping  into  water,  where  it  is  collected, 
and  afterwards  cast  into  cakes.  A bar  of  zinc  12  inches  long  and  1 inch  square,  weighing  3'05  pounds, 
expands  in  length  at  one  degree  of  heat  , and  melts  at  648°  ; it  will  bear,  without  permanent 
alteration,  a pressure  on  a square  inch  of  5700  pounds. 

Zinc  is  used  for  the  preservation  of  iron,  by  electro-deposition.  The  iron  is  first  rendered  perfectly 
clean  and  free  from  oxide,  by  placing  it  in  a bath  of  heated  sulphuric  acid  and  water ; then  in  a cold 
solution  of  sulphate  of  zinc.  The  positive  pole  of  a galvanic  battery  is  attached  to  a zinc  plate,  and 
the  negative  to  the  iron  to  be  covered ; the  pure  metal  is  deposited,  and  the  zinc  and  iron  are  amal- 
gamated. Wooden  troughs  are  employed  for  the  process,  and  iron  plates  so  covered  are  extensively 
used  for  roofing,  and  do  not  after  many  months  exhibit  any  signs  of  decay.  The  iron  being  coated  with 
zinc  in  a cold  solution  Joes  not  in  any  way  change  its  condition ; but  when  the  zincing  of  iron  is  per- 
formed by  steepmg  it  in  a bath  of  melted  zinc,  a combination  takes  place  between  the  two  metals,  and 
a brittle  alloy  is  the  consequence,  the  iron  losing  all  its  tenacity. 

Tin  is  usually  prepared  from  the  native  oxide  its  oxygen  being  removed  by  charcoal:  the  purer 
kinds  are  called  grain  tin,  and  the  others  block  tin.  The  common  ores  are  known  under  the  name  of 
mine  tin,  and  furnish  a less  pure  metal  than  the  stream  tin.  Tin  has  a silvery -white  color;  its  specific 
gravity  is  7'3,  and  the  air  and  moisture  have  little  effect  upon  it:  it  melts  at  442°,  and  is  converted 
into  a white  oxide  by  exposure  to  heat  and  air. 

The  specific  gravity  of  the  native  peroxide  of  tin  is  7‘,  and  its  primitive  crystal  an  obtuse  octohedron 

Protoxide  of  tin : specific  gravity  6'6  : 


Tin 1 58  87-S 

Oxygen  1 8 12 '2 


1 66  10U-0 


9£»S 


ZINC 


Bmilphuret  of  tin  ( Auruin  musivum,  Mosaic  gold ) is  a mixture  formed  by  heating  peroxide  of  tin 
which  contains  two  of  oxygen  and  one  of  tin,  with  its  weight  of  sulphur.  Bisulphuret  of  tin  is  also 
formed  by  decomposing  perchloride  of  tin  by  sulphuretted  hydrogen  ; it  is  quite  insoluble  in  the  acids, 
except  nitro-muriatic ; it  forms  the  bronze  powder  used  by  paper-stainers. 

Tin 1 58  64-4 

Sulphur 2 82  35  6 

1 90  lUO'O 

The  weight  of  a cubic  foot  of  cast  tin  is  455'7  pounds,  and  the  weight  of  a bar  12  inches  long  and  an 
inch  square  is  3-165  pounds  ; it  expands,  according  to  Smeaton,  at  one  degree  of  heat  and  melts 

at  442°.  It  will  bear  on  a square  inch  2880  pounds  without  any  permanent  alteration”  and  an  exten- 
sion of  length  of  ^-1-^.  Compared  with  cast-iron,  its  strength  is  0182  times,  and  its  extensibility  075 
times,  and  its  stiffness  0’25  times,  cast-iron  being  considered  as  unity. 

Zinc  white , a carbonate  of  zinc,  which  is  destined  to  supersede  the  white-lead  as  a paint.  It  is 
equally  durable  with  lead  as  a color,  and  docs  not  turn  yellow  as  does  lead.  It  is  also  free  from  the 
poisonous  qualities  possessed  by  preparations  of  lead  which  render  its  effects  upon  the  workmen  who 
use  it  so  disastrous. 

Brooman  s improvements  in  the  manufacture  of  zinc. — The  general  object  of  this  invention  is  to  do 
away  with  the  troublesome  and  expensive  processes  of  assorting,  pounding,  and  crushing,  now  ordinarily 
followed  in  order  to  the  extraction  of  zinc  from  its  ores ; and  this  is  effected  by  a method  of  direct  reduc- 
tion. We  extract  the  following  description  of  the  apparatus  employed,  and  of  the  peculiar  processes 
followed  in  connection  therewith,  from  the  patentee’s  specification  : 

Fig.  3959  is  a vertical  section  of  the  apparatus  on  the  line  A D of  Fig.  3960,  which  is  a horizontal 
section  on  the  (dotted)  line  A,  B,  C,  D of  Fig.  3959.  C is  the  hearth  of  the  furnace ; F,  F,  F are  the 
tuyeres,  which  are  three  in  number;  H is  the  shoot;  U the  chamber  of  the  furnace.  So  far  the  parts 
of  the  structure  are  very  similar  to  those  of  a small  blast-furnace.  At  IK  the  upper  part  of  the  cham- 
ber U is  suddenly  contracted,  so  as  to  form  a neck  Y,  or  narrow  passage,  between  the  upper  and  lower 
parts  of  the  furnace.  The  charge,  as  it  falls  through  this  neck,  leaves,  necessarily,  a vacant  annular 
space  at  x x,  between  it  and  the  sides  of  the  furnace,  where  the  volatilizable  matters  may  collect.  F F 
are  four  rectangular  passages,  formed  of  cast  or  sheet  iron,  which  lead  off  at  right  angles,  and  in  an 


inclined  direction,  from  the  annular  space  xx,  and  each  passage  is  encased  for  a certain  distance  within 
a chamber  G,  through  which  cold  water  is  kept  continually  circulating,  flowing  in  from  the  tube  P,  Q,  R, 
and  escaping  through  the  pipe  S S.  At  the  lower  end  of  each  of  the  rectangular  passages  there  is  a 
tubular  passage  A1,  by  which  the  uncondensed  gases  of  the  furnace  are  carried  off  to  different  points, 
to  be  employed  for  heating  purposes,  as  hereafter  explained ; and  each  passage  is  provided  at  its  lower 
end  with  a sliding  door  A2  which  may  be  closed  or  opened  as  required.  W is  a lid  or  cover  by  which 
the  furnace  is  closed  at  top,  and  which  fits  into  a groove  made  for  it,  so  that  there  may  be  no  escape  of 
the  gases  at  that  part.  All  the  interior  parts  of  the  furnace  are  formed  of  fire-brick,  with  an  outer 
wall  or  casing  V1,  which  may  be  made  of  ordinary  brick ; and  between  the  outer  and  inner  walls  there 
is  left  a space  Z Z,  which  is  filled  with  some  substance  which  is  a bad  conductor  of  heat.  H H are 
strengthening  plates  of  cast-iron,  which  are  inserted  into  the  lower  brick-work  V1,  immediately  over 
the  tuy£re  openings  E1  E1.  L1  are  cast-iron  frames,  which  carry  the  passages  F F and  cold-  water 
chamber  G. 

The  mode  of  operating  w7ith  the  apparatus  is  as  follDws  : — After  (he  furnace  has  been  built,  it  is  left 


ZINC. 


959 


to  dry;  then  a fire  is  kindled  on  the  hearth,  and  kept  up  for  about  three  weeks  by  supplies  of  fuel  (by 
preference  coke)  introduced  through  the  throat.  The  furnace  being  in  this  manner  filled  with  incan- 
descent fuel,  a small  charge  of  quicklime  is  thrown  in.  As  soon  as  this  charge  has  descended  as  far 
down  as  the  tuyhres,  a mixture  of  ore,  flux,  and  fuel  is  fed  into  the  furnace,  the  top  of  the  furnace 
closed,  and  a moderate  blast  of  atmospheric  air  applied  by  means  of  a blowing  machine. 

Tlie  fuel,  the  flux,  and  the  ore  are  in  such  proportions  to  one  another  that  the  whole  of  the  zinc  con- 
tained in  the  ore  shall  be  reduced,  and  then  volatilized,  while  all  the  foreign  matters  shall  form  with  the 
flux  a residual  slag  of  more  or  less  fluidity  when  in  the  heated  state.  The  fuel  employed  may  be  either 
charcoal,  or  coke,  or  common  coal,  or  anthracite,  or  turf,  taking  care  always  that  it  is  of  a sufficiently 
hard  nature  to  resist  the  incumbent  pressure  of  the  charge  in  the  furnace. 

The  quantity  of  fuel  employed  should  be  greater  at  the' commencement  than  during  the  subsequent 
stages,  and  should  in  all  cases  be  sufficient  not  only  for  the  complete  reduction  of  the  zinc,  but  also  to 
leave  so  considerable  an  excess  that  when  it  arrives  directly  before  the  tuyeres,  the  combustion  of  the 
fuel  shall  not  give  rise  to  any  gaseous  oxidating  product ; such,  for  example,  as  carbonic  acid.  The  flux 
(the  selection  of  which,  as  well  as  that  of  the  fuel,  depends  on  the  quality  of  the  ore)  must  be  used  in 
such  a state  as  not  to  produce  any  oxidating  matter  during  the  formation  of  the  slag.  For  this  reason, 
when  the  nature  of  the  ore  requires  the  employment  of  lime  as  a flux,  the  lsme  should  be  used  in  a 
caustic  state,  and  not  as  a carbonate ; and  for  the  same  reason  it  is  advisable  to  use  a blast  of  dry  air, 
that  is  to  say,  air  deprived  of  aqueous  vapor.  The  products  of  the  furnace  are,  in  the  first  place,  the 
gases  arising  from  the  combustion  of  the  fuel ; secondly,  the  vapors  of  zinc ; thirdly,  the  non-volatilizable 
matters,  consisting  of  scoriae  or  slag,  and  of  reduced  metallic  substances  of  greater  density  than  the 
zinc.  The  throat  of  the  furnace  being  closed,  “ the  gases  arising  from  the  combustion  of  the  fuel”  pass 

3300. 


off  through  the  passages  A1,  and  are  made  use  of  either  for  the  purpose  of  heating  the  boiler  of  ths 
steam-engine  which  drives  the  blowing  machine,  or  to  burn  lime  when  used  for  a flux,  or  to  melt  the 
zinc  which  is  carried  over  in  a state  of  vapor,  or  to  dry  and  roast  the  ores.  The  “ vapors  of  zinc”  are 
condensed  in  the  passages  F F,  and  may  be  easily  withdrawn  therefrom  by  means  of  a rake,  (the  rec- 
tangular form  of  the  passages  FF  affording  great  facilities  for  this  purpose,)  after  which  they  are  re- 
duced and  formed  into  ingots  or  bars.  The  “ non-volatilized”  or  residual  matters,  which  collect  on  the 
sole  or  hearth  of  the  furnace,  are  run  off  from  time  to  time  according  as  they  accumulate. 

The  ores  containing  zinc  may  be  divided  into  two  classes : firstly,  those  in  a state  of  oxide,  either 
free  or  combined  with  carbonic  or  silicic  acid  ; secondly,  those  containing  sulphuret  of  zinc,  (blende.) 
When  the  ores  are  of  the  first  class,  (oxides,)  they  are  first  dried,  and  if  they  contain  a carbonate,  they 
are  subjected  to  a roasting  process.  The  flux  employed  for  the  treatment  of  ores  of  this  class  is  quick- 
lime, the  quantity  of  which  varies  according  to  the  quantity  of  earthy  matters  contained  in  the  ore,  but 
should  be  sufficient  for  the  formation  of  a bisilicate,  or,  as  it  is  commonly  called,  a good  slag.  When 
the  ores  contain  any  other  metals,  such  as  iron  or  lead,  these  metals  are  reduced  to  the  metallic  state, 
when  they  collect  on  the  sole  of  the  furnace,  where  they  arrange  themselves  in  different  strata  accord- 
ing to  their  respective  densities,  and  may  be  drawn  off  separately.  When  the  ores  are  of  the  second 
class,  (blende,)  they  are  treated  in  one  of  two  ways : either  by  roasting,  which  brings  them  into  the 
state  of  oxide,  'which  oxide  is  then  mixed  with  a little  damp  clay  and  formed  into  blocks,  which,  after 
being  dried,  are  treated  in  the  manner  before  described ; or  (which  is  considered  the  preferable  way) 
these  sulphurous  ores  are  mixed  with  a quantity  of  iron  ore,  so  that  when  the  metals  are  fused  the  iron 
‘-hall  combine  with  the  sulphur,  and  set  the  zinc  at  liberty. 


ZINC. 


9(50 


The  flux  employed  in  this  case  is  quicklime ; and  if  the  ore  contain  a portion  of  baryta  or  gypsum, 
then  fluorine  is  added.  The  quantity  of  quicklime  employed  depends  on  the  quantity  of  earthy  mat- 
ters contained  both  in  the  zinc  and  iron  ores.  The  iron  ore  best  suited  for  this  purpose  is  that  contain 
ing  zinc,  but  in  too  small  a quantity  to  be  treated  separately  as  a zinc  ore.  When,  however,  the  iron 
ore  contains  water  or  carbonic  acid,  it  is  necessary  that  these  should  be  expelled  by  roasting,  in  ordei 
that  no  substance  susceptible  of  oxidizing  the  zinc  may  be  introduced  into  the  furnace.  If  the  iron 
ore  contain  too  great  a quantity  of  oxidating  matter,  then  it  is  preferable  to  expel  the  sulphur  from 
the  zinc  ore  by  means  of  cast-iron  or  malleable  iron.  This  plan  presents  the  advantage  of  driving  otf 
the  whole  of  the  substances  capable  of  reoxidizing  the  zinc  which  has  been  reduced.  When  a sul- 
phuret  of  zinc  in  which  there  are  several  other  metals,  such  as  iron,  copper,  lead,  silver,  Ac , is  treated 
in  the  furnace,  there  collects  on  the  sole,  besides  the  slag,  a stratum  of  argentiferous  lead,  on  which  is 
superimposed  a stratum  of  cast-iron  arising  from  the  excess  of  iron  ore  used  in  the  process.  Again 
above  the  stratum  of  iron  there  collects  a mass  composed  principally  of  sulphuret  of  iron,  sulphuret  of 
copper,  and  portions  of  the  sulphurets  of  other  metals. 

If  white,  gray,  or  yellowish  oxide  of  zinc  should  be  formed  accidentally  in  the  passages  FF,  it  can 
oe  made  use  of  directly  as  a coloring  matter,  and  sold  as  such ; or  else  it  can  be  mixed  with  damp  clay, 
made  up  into  blocks,  dried,  and  again  passed  through  the  furnace ; in  which  case  a sufficient  quantity 
of  quicklime  should  be  added,  to  convert  all  the  clay  into  a fusible  slag. 

When  ore3  containing  zinc  in  a state  of  oxide  have  to  be  treated,  they  should  be  previously  assayed, 
in  order  to  effect  an  analysis,  and  to  ascertain  the  quantity  of  earthy  matters  contained  therein  capable 
of  being  converted  into  scoria,  and  which  will  determine  the  proper  proportion  of  quicklime  to  be 
added.  The  lime  and  magnesia  contained  in  the  ore  are  also  taken  into  account. 

When  ores  containing  zinc  in  the  state  of  sulphurets  have  to  be  treated,  the  quantities  of  sulphur, 
earthy  matters,  and  metallic  substances  contained  therein  should  also  be  ascertained  by  preliminary 
assay,  so  that  the  quantity  of  iron  ore  used  in  the  charge  shall  be  sufficient  to  produce  the  cast-iron 
requisite  for  combining  with  all  the  sulphur  that  may  be  in  the  zinc.  In  order  that  the  combination  of 
the  sulphur  and  iron  may  be  the  more  completely  effected,  it  is  advisable  to  employ  a slight  excess  of 
iron  ore.  But  if  there  should  be  reason  to  apprehend  that  the  iron  ores  might  produce  too  great  a 
quantity  of  oxidating  matter,  and  thereby  create  too  great  a quantity  of  oxide  of  zinc,  then  cast  or 
malleable  iron  may  be  directly  used  for  the  purpose  of  combining  with  the  sulphur,  in  which  case  the 
proportion  of  cast-iron  or  malleable  iron  is  to  be  determined  by  the  quantity  of  sulphur  contained  in 
the  ore,  always  employing  a slight  excess  of  the  iron.  The  proportion  of  quicklime  or  of  fluorine  used 
for  making  a fusible  slag  will  depend  on  the  quantity  of  earthy  matters  contained  in  the  ore  to  be 
treated,  as  well  as  in  the  iron  ore  when  used  for  combining  with  the  sulphur.  The  quantity  of  fuel 
employed  in  this  case  will  depend  not  only  on  what  has  been  already  stated,  but  also  on  the  richness 
and  fusibility  of  the  iron  ores,  and  in  all  cases  should  be  so  regulated  that  the  working  of  the  furnace 
shall  in  all  respects  resemble  that  of  a blast-furnace  for  casting  purposes. 

As  sulphuretted  ores  contain  generally  other  metallic  substances  besides,  zinc,  a great  quantity  of 
reduced  metals,  and  of  crude  metals,  composed  principally  of  sulphuret  of  iron,  will  collect  on  the 
hearth  of  the  furnace,  and  combine  with  the  sulphuret  of  copper  and  a portion  of  the  sulphurets  of 
the  other  metals.  In  this  case,  therefore,  it  is  better  to  run  off  the  metal  more  frequently  than  in  the 
preceding  cases.  The  lead  thereby  obtained  can  be  recast  into  pigs  ready  for  sale,  or  submitted  to  the 
process  of  cupellation,  if  it  should  contain  silver ; and  any  other  masses  of  crude  metal  may  be  treated 
by  any  of  the  well-known  processes,  in  order  to  extract  the  copper  therefrom.  As  in.the  preceding 
cases,  the  whole  of  the  zinc  will  be  volatilized,  and  collected  condensed  in  the  passages  F F,  and 
chamber  G. 


END  OF  VOL.  II. 


I N D E X 


Abacus 

Absorbing  and  Productive!  Cas- 
cade. 

Acceleration. 

Affinity. 

Air  Escape. 

Air-Gun. 

Air-Valve. 

Air-V  essel. 

Air  in  motion,  or  Wind  and  Wind- 
Mills. 

Air-Pumps,  in  general. 

“ Kennedy’s  Horizontal 
Double  Cylinder. 

Air-Pipes, 

Alarm,  Fire-Damp. 

“ Whistle. 

American  Steam  Excavating  Ma- 
chine 
Anchor. 

Anemometer. 

Annealing. 

Angle,  Definition  of. 

Animal  Kingdom,  Materials  from : 
as,  Porcelanous  and  Nacreous 
Shells,  Bones,  etc. ; 
Horn ; 

Tortoise-shell ; 

Ivory. 

Anthracite  Coal. 

Aqueduct,  Wire-Suspension. 
Aqueducts,  Modern. 

Aqueduct,  Croton. 

Archimedean  Boiler-Furnace,  and 
Self-Acting  Stern-Propeller. 
Artesian  Wells. 

“ “ Grenelle’s  Bor- 

ing Apparatus  of. 

Auger,  Ship  Carpenter’s. 

“ Improved. 

Augers,  Machinery  for  making. 

“ Double  and  Single  Twist. 
Auger  Machine. 

Automatic  Dividing  Machine. 
Axle  Grease. 

Axles  for  turning  narrow  Curves. 
■'  Vibrating-Box,  for  Loco- 
motives. 

Axle  and  Wheel. 

Backwater  or  Scouring  rower. 

1 


Ballast-Wagon. 

Ballasting,  or  Metalling. 
Balustrade. 

Bar. 

Barrel. 

Barrow. 

Base-Lines. 

Bath-Stones. 

Batter. 

Bearings. 

Beetle. 

Bench,  or  Berm. 

Beetling  Machine. 

Bench-Marks. 

Beton. 

Belting. 

Biram's  Tell-Tale. 

Blasting,  under  water. 
Blast-Furnace. 

Blast-Pipes. 

Blasting. 

I Block  Machinery. 

Blocks 

Blood. 

Bloom. 

Blow-Pipe  Analyzer. 

Blowing  Machine. 

“ “ or  Air-Fan. 

Blow-Pipe. 

“ “ Dr.  Hare’s  Hydro- 

oxygen. 

Bobbinet  Machinery. 
Boiler-Plates,  Machine  for  Punch- 
ing. 

Boilers,  Varieties  of,  and  circum- 
stances attending  their  use  and 
construction. 

Bolting-Mill  for  Flour. 

Bolts,  Iron. 

Bolsters. 

Bond. 

Boring  Machine,  Vertical,  by 
Messrs.  Nasmyth,  Gaskell  & 
Co. 

Boring  Machine,  Great,  by  the 
same. 

Boring  Machine,  Vertical,  by 
Messrs.  Benj.  Hick  & Son. 
Boring  Tools. 

Bow-string  Bridge,  or  Tension- 
j Bridge. 


Drake,  or  Convov 
Bran  Separator 
Breakwater. 

Breakwater  Glacis. 

Breasts. 

Breast-W  all. 

Brick-Machine. 

Brick-Making. 

Bridges. 

Bronzing,  Improvements  in. 
Buffing  Apparatus. 

Bullets,  Manufacture  of  by  rolling 
Bung-Cutting  Machine. 

Bush. 

Button  Machinery. 

Byrnegraph,  or  new  Proportional 
Compasses. 

Calender,  with  five  Rollers. 
Calender. 

Calico,  Machine  for  Printing  it. 

four  Colors. 

Candles,  Wax. 

“ Stearine,  Manufacture  of 
Cannons,  or  Great  Guns. 

Carding  Engine. 

Cask-Gaging. 

Casting  and  Founding. 

Centre  of  Gravity. 

Cheese  Press. 

Cider  Mill  and  Press. 

Circular  Saw  for  cutting  Veneer., 
Cloth-Shearing  Machine. 
Condensing  Machine,  by  Neilson 
and  Mitchell. 

Coining  Machine. 

Connecting  Crank. 

Conway  Tubular  Bridge 
Cop-Spinner. 

Corn-Mill. 

Coal,  Anthracite. 

Corn-Sheller. 

Counter  Proportional 
Cracker  Machine. 

Crane,  Movable. 

Crane,  Foundry. 

Cutting  and  Carving  Machine. 
Cutting  Tools. 

Deal  Sawing  Machine. 

Derrick,  Stone  Laying. 


2 


INDEX. 


Distillation. 

Diving-Bell. 

Docking  Ships,  Apparatus  for. 
Dredging  Machine. 

Dredging  aud  Raising  Machine. 
Dresser. 

Dressing  Machines. 

Dressing  Millstones,  Machine  for. 
Drilling  Machines. 

Drilling  Machine,  Vertical. 

Dry  Dock. 

Dynamometric  Crane. 
Dynamometer. 

Earthwork,  Wagons  for  Execut- 
ing.. 

Electricity. 

Electric  Light. 

Electric  Clock. 

El  ectro-Metallurgy. 
Electro-Motive  Engine. 
Electro-Magnetic  Ore-Separator. 
Elevators. 

Elliptograpb. 

Embossing  Machine. 
Embankments,  Movable  Machine 
for  executing. 

Engines,  Details  of: 

Pumping  Engine. 

Rotative  Engines. 

The  Parallel  Motion. 

Marine  Engines. 

Boilers. 

Locomotive  Engine. 

Fire-box. 

Stnoke-box  and  Chimney. 
Framing. 

Steam-dome,  pipes,  and  regu- 
lator. 

Safety-Valves  and  Fusible 
Plugs. 

Cylinders  and  Valves. 

Wheels. 

Cranked  Axle. 

Connecting-rods. 

Eccentric  and  Eccentric-rod. 
Valve  motion. 

How  to  set  the  Valves  of  Loco- 
motives. 

Miscellaneous  Remarks  respect- 
ing Locomotives. 

Rules  for  Calculating  the  Parts 

of. 

Varieties  of  the  Steam  En- 
gine. 

Eng-raving  on  Copper 
“ on  Steel. 

“ on  Stone. 

on  Silver  and  Gold. 

“ on  Wood. 

Envelope  Machinery. 

Etching. 

Fan. 

Falling  Stocks. 

Felloe  Machine. 

Felting. 

Files. 

File  and  Rasp  Machine. 

Filing. 

Filtration. 

Fire-Annihilator. 

Fire  Bricks. 


Fire-Engine. 

Flash-Boards. 

Flax,  Machinery  for  Preparing 
and  Spinning. 

Floating  Sectional  Docks. 
Floor-Cloth. 

Fly-Wheel. 

Focus. 

Folding  and  Measuring  Machine. 
Force. 

Forge. 

Forging. 

Fortification. 

Foundations. 

Foundry  Crane. 

Freezing  Apparatus. 

Friction. 

Friction-Rollers. 

Fringe  Machine,  Shawl. 

Frog. 

Fulcrum. 

Fulling. 

Fulling-Mill,  for  Cloth. 

Furnace. 

“ Reverberatory. 

Fusible  Metals. 

Futtock,  or  Ship  Timber  Convert- 
ing Machine. 

Futtock  Plates. 

Futtocks. 

Galvanism. 

Galvanized  Iron. 

Galvanometer. 

Gas,  and  the  Machinery  employed 
in  the  Manufacture  of. 

Gates,  Wrought-iron,  for  the  Uni- 
ted States  Dry  Dock  at  Brook- 
lyn. 

Gates,  Floating,  for  the  United 
States  Dry  Dock  at  Brooklyn. 
Gates,  Guard. 

Geer  Cutting  Machine,  Bevel. 
Geer  Cutting  Engine. 

Geering. 

Geodesy. 

German  Silver. 

Gig-. 

Gilding. 

Gimbals  or  Gimbols. 

Gin. 

Glass. 

Glue. 

Glyphograpliy. 

Gold. 

Gold-Beating. 

Goniometer. 

Governors. 

Grain  Separator. 

Graphometer. 

Gravity,  Centre  of. 

Gravity,  Specific. 

Grinding  Machine,  Double. 

| Grinding  Mill,  Eccentric, 
i Grindstone. 

1 Grist-Mill. 

' Gage,  Steam  and  Water-Safety, 
for  Steam  boilers. 

Gage,  Telegraphic  Steam. 
Gudgeon. 

Guns. 

Gun-Barrels,  Lathe  for  Turning. 
Gun-Cotton. 


Gun-Metal. 

GunpowTder. 

Gunter’s  Chaim 
Gunter’s  Line. 

Gunter’s  Scale. 

Gutta  Percha. 

Gyration,  the  Centre  of. 

Hammer,  Anderson’s  patent 
Hammer,  Steam. 

Hammer,  Tilt  or  Trip.  See  Tilt- 
ing. 

Harvester.  See  Reaper. 
Hat-Making. 

Hay  and  Corn  Cutter. 
Heart-Wheel. 

Heat. 

Heddles,  Machine  for  making 
Weavers’. 

Heliotrope,  Reflecting  Lantern. 
Heptagon. 

Hexsedron. 

Hexagon. 

High-Pressure  Engine. 
High-Pressure  Steam-EngiQc. 
Hinge. 

Horn. 

Horse. 

Horse-Power. 

Horse-Shoe. 

Hydrodynamics. 

Hydro-Electrical  Machine. 
Hydro-Extractor. 

Hydrometer. 

Hydrostatic  Press. 

Hygrometer. 

Hyperbola. 

Hyperbolic  Logarithms. 

Ice. 

Ice-Boats. 

“ House. 

“ Saws. 

“ Trade. 

Icosahedron  or  Icosaedron. 
Illumination. 

Impact. 

Impenetrability. 

Impetus. 

Incidence. 

Inclination. 

Inclined  Plane. 

Indicators. 

Indigo. 

Inertia. 

Involute  Curve. 

Iron. 

Jack. 

Jack-Screw. 

“ Lever. 

“ Traversing  Screw. 

“ Traversing. 

Jacket,  Steam. 

Jacquard. 

“ Perforating  Machine 
Japanning. 

Joint,  Clasp  Coupling. 

Joint,  Patent  Expansion. 

Joints,  and  Joining  Timbers, 

Kaleidoscope. 

Kedge. 


INDEX. 


3 


Iveel. 

Keelson. 

Kiln. 

Kite. 

Kneading. 

Knives. 

Knife  Sharpeners. 

Laburnum  Wood. 

Lac. 

Lace. 

Lacquering. 

Lactometer. 

Ladder. 

Lamps. 

“ Spirit  Gas. 

Lathe  for  Turning  Irregular 
Forms. 

Lathe  for  Small  Engine. 

“ Boring  and  Reaming. 

“ Engine. 

“ Large  Boring  and 

“ Reaming. 

“ Gun  Boring,  Turning, 

“ and  Planing. 

“ Small  Self-acting  and 

Screw  Cutting. 
Boring  and  Turning. 

“ Boring-Mill  and  Large 

Turning. 

Lap  and  Lead  of  the  Slide-Valve. 
Lead. 

Lens. 

Lever. 

Lewis. 

Light. 

“ Artificial. 

Light-Houses. 

Lightning  Conductors. 

Life-Boat. 

Lime. 

Lithography. 

Lochs  of  Canals. 

Locomotive  Engine. 

Logarithm. 

Logwood. 

Loom,  Power. 

“ Bigelow’s  Counterpane. 

Double-Stroke. 

" Power  Carpet. 

Machines. 

Magnet — Magnetism. 

Mahogany. 

Manometer. 

Mangle. 

Maple- Wood. 

Marble  Sawing  and  Polishing  Ma- 
chinery. 

Marine  Steam-Engine. 

Matches. 

Materials. 

Mean. 

Measure. 

Mechanical  Powers. 

Mechanical  Power  of  Steam. 
Mensuration. 

Metals  and  Alloys. 

Metallurgy. 

Micrometer 

Microscope. 

Mile. 

Mill. 


Millstone. 

Mineral  Kingdom. 

Mines,  Engines  for. 

Modulus. 

Momentum. 

Mortar. 

Mortising  Machine. 

Motion. 

Moulding  Machine. 

“ “ Sheet-Metal. 


Mule. 


Nail  Machine. 

Needles. 

Nickel. 

Nonagon. 

Normal. 

Nut-Cutting  Machine. 

Octagon. 

Octahedron. 

Odometer. 

Oils. 

Oil  Test. 

Ombrometer. 

Operameter. 

Opsiometer. 

Ordinate. 

Ore-Separator. 

Orthochronograph. 

Oscillation,  Centre  of. 

Oscillating  Engines. 

Oyster  Opener. 

Paints,  Grinding  of. 

Paper,  Manufacture  of. 

“ Cutting. 

Parallel  Motions. 

Parameter. 

Pendulum. 

Pens,  Steel. 

Percussion. 

Percussion-cap  Machine. 
Perpetual  Motion. 

Persian  Wheel 
Photography. 

Photometer. 

Pile-Driver. 

Piling  Machine. 

Pin-Making  Machine. 

Piston. 

Planing  Machine. 

“ “ Hand. 

Plate-Bending  Machine. 

Platinum. 

Pneumatics. 

Polarization  of  Light. 

Potassium. 

Press,  Anti-Friction  Cam. 
Printing-Press,  Lithographic. 
Press,  Progressive  Lever  Steam. 
Printing-Press. 

Projection. 

Proving  Machine,  Hydrostatic. 
Puddler’s  Balls,  Machine  for  com 
pressing. 

Pulley. 

Pumps. 

“ Steam. 

Punch,  Revolving  Steam. 
Punching  Machine,  Steam 
Punching  and  Plate-Cutting  Ma- 
chine. 


Punching  and  Shearing  Machine 
Pyrometer. 

Picker,  Rag  and  Waste. 

Railroads. 

Retorts. 

Rice-Cleaner. 

Rivets  and  Blank  Screws,  Ma- 
chine for  making. 

Riveting  and  Steam  Punching 
Machine. 

Rolling  Machine. 

Ropes,  Stiffness  of. 

Sawing  Machine. 

Saw-Filing  Machine. 

Screws,  Self-ojierating  Shaver. 
Screw-Blanks. 

Screws,  Burring  Machine  for 
Screw-cutting  Machine. 
Screw-Finisher. 

Screws,  Machine  for  Nicking. 

“ Machine  for  Shaving  and 
Turning. 

“ Machine  for  Threading, 
Screwing  Machine  for  Bolts. 

“ “ "tauble. 

Sea-Lights. 

Seaming  Machine. 

Sewing  Machine. 

Shears,  Rotary. 

Sliingler. 

Shingle  Machine. 

Shot. 

Slotting  Machine. 

Sluice-Cocks. 

Smut  Machine. 

Soldering. 

Spike  Machine. 

Spinning-Frame  Banding,  Ma 
chine  for  making. 
Stave-Dressing  Machine. 
Stave-Joining  Machine. 

Steel. 

Strength  of  Materials  of  Con 
struction. 

Sugar-Mills  and  Machinery. 
Switch. 

Telegraph. 

Telescope. 

Tempering,  Hardening,  and  Soft 
ening  Metals. 

Thermometer. 

Threshing  Machine. 

Throstle. 

Tilting  Hammer. 

Tobacco-Cutting  Machine. 

Tools,  Cutting,  Drilling,  Turning 
&c. 

Torsion. 

Transit. 

Trip-Hammer. 

Tube-Cocks. 

Turbine. 

Turn-Table. 

Twisting  Machine  for  Iron. 
Uranium. 

, Valves. 

I Valve,  Expansion. 

| Velocity. 


4 


INDEX. 


Ventilation. 

Vernier. 

Vice,  Lever. 

"Warming  and  Ventilation. 
Watchmaking. 
Water-Closet 
Water-Metre. 


W ater  Pressure  Engine. 
Water- Wheels. 

Weights  and  Measures. 
Wheels,  Railway. 
Wheels,  Paddle. 
Wire-covering  Machinery 
Wire  Rope  Machinery. 
Wiring  Machine. 


Woods,  Variety  of. 

Wood,  Steam  Carbonizing  Ma 
chine. 

Wrench,  Cylinder. 

Wrench,  Screw. 

Zinc. 


Boilers,  American. 
Brick-Making  Machine. 

Cart-Wheels. 
Cask-Making  Machine, 

Iron  Rolling  Machine 

Placing  Machine. 


APPENDIX. 


Pumping-Engine,  from  the  United 
States  Dry  Dock  at  Brooklyn. 

Railway  Bars. 

Regulating  and  Numbering  Ma- 
chine. 


Smut  Machine. 

Spark  Arrester 
Stove,  Cooking. 

Sugar,  Manufacture  of 

Tube-Making  Machine 


Sewing  Machine, 


Valves. 


GETTY  RESEARCH  INSTITUTE 


3 3125  01159  8436 


